Experts

Mixing

Mixing by Dave Dickey, senior consultant, MixTech Inc.

Dave Dickey is senior consultant for MixTech Inc., Dayton, Ohio, which focuses on mixing processes and equipment. He has 25 years of experience in the field, both as a consultant and with equipment suppliers. He gives a number of short courses related to mixing and has written numerous articles and contributed to several handbooks.

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How do I select the optimal location for an impeller inside a tank?
I am new to tank mixing and I have a question about selecting the optimal location (and orientation) for an impeller inside a tank. I am dealing with a tank that contains very light materials (0.7 and 0.8 SG). The contents have been sitting in the tank and are stratified. Please let me know if there is some sort of general process for selecting the proper impeller position.

The tank is 120 ft. in diameter, 45 ft. high. It is allowed to only have one mixer. The first layer of material has a specific gravity of 0.75 is 32 ft. high. The second layer of the tank has a specific gravity of 0.67 and is 10 ft. high; making the total contents of the tank 42 ft. high. The purpose of the mixer is to have complete mixing within 6 hours.
Category: Mixing

Is a UDIF impeller suitable?
We have been using a UDIF agitator for emulsion polymerization mixing for 1cp to 8,000 cp. Is this type of agitator suitable for mixing?
Category: Mixing

What kind of agitator is suitable for a range of viscosities?
Our process dissolves several types of polymers in appropriate solvents. During the solving process, the viscosity might reach to the value of 8,000 cp. Our vessel dimension is 30 cm in diameter and 70 cm in height. What kind of agitator is suitable for this purpose?
Category: Mixing

What is the best way to approach gas-gas mixing?
I want to mix two low viscous gas streams in laminar regime. I am planning to mix them by passing through a pipe filled with spherical pebbles or some structured packing. I want to calculate the length required for the mixing expected. My required process stream details are as follows:

Q = 1Nm³/hr
He= 0.99
H₂= 0.01
P= 1.2 bar
Dia of pipe = 1/2 inch
Temp= 25 degrees C

I have gone through the text book "Handbook of Industrial Mixing." But that textbook has procedure for only commercially available static mixers. Please guide me through the design. Is dispersion model helpful in finding the length? If so, how?
Category: Mixing

We would like to have a general idea of pumping number for our reactors. Can you help us with blend-time calculations?
To characterize one of the reactors at plant scale, we use the discoloration method. The parameters for the mixing time are calculated based according to the following formula:

t_mix= K/(aN(D/T)^b (T/Z)^0.5 )
N = impeller speed
D = diameter stirrer
T = diameter tank
Z = liquid height
The divisor is known as Kmix

Because we don't really know the uniformity (U) reached with this method we don't replace K with

K = -ln (1-U)

But get the best fit for K, a and b by means of the least square method. It is known that the pumping number can be determined by

N_Q= (Vk_mix)/(ND^3 )

We would like to have a general idea of pumping number for our reactors. So if we would like to deviate the pumping number from the above method would it be correct that for T=Z (so at a fixed volume based on the reactor geometry) we use the following formula.

N_Q= (VaN(D/T)^b)/(ND^3 )

Working in a turbulent regime, this result in a constant pumping number related to the tank geometry. Would the above approach be correct to compare pumping and mixing time capabilities of different reactor set ups? I think that not working at a fixed uniformity results in a gap in the above approach.
Category: Mixing

What's the best way to mix in a horizontal, cylindrical vessel?
What would be the optimum blade size, speed and motor power required for a power stirrer for a horizontal cylindrical chamber (650mm diameter x 1500 length)? It will stir around 500 kg of sludge inside it (density 2.2kg/liter).
Category: Mixing

Do plastic mixing shafts and propellers exist?
My firm needs to blend some fairly insoluble solutions of aluminum chloride. Afraid that the solution might erode a steel mixing shaft, we're looking for plastic shafts and propellers instead. Do these exist? And if so, who would carry such items?
Category: Mixing

How do I design my agitation system?
How can I design an agitator (pitched-blade turbine) for dissolution solid particles (iron powder in water)? I have to design a mixing tank to mix iron powder 150 microns density = 2450 kg/m³ amount 100kg in the water 200L (batch process). I design the mixing time is around 10 minutes. And tank dimension, elliptical bottom, diameter = 0.75m and height = 0.85 m with 2 baffles. I want to know how many blades for each impeller and how many numbers of impellers are suitable and their dimension? And how can I calculate power number for one or two impellers if two impellers are require? At last, I want to know the speed of the impellers that you recommend.
Category: Mixing

How can I calculate my power number and power required for two different impellers?
How can I calculate my power number and power required for two different impellers? I have a solid suspension mixing tank with two different types of impellers but same size as below.

• Vessel: diameter = 510 mm, height = 710 mm, dished bottom
• Impeller: one 3PBT45 at bottom and 3-blade paddle at top both diameter = 165 mm, different height = 360 mm
• Shaft diameter = 35 mm
• Rotational speed around 1,400 rpm
• liquid density = 1000 kg/m³
• solid density = 8000 kg/ m³
• mixing ratio is 2:1
• viscosity = 1 mPas

Category: Mixing

Can I use any correlation factor of liquid mixing for solid suspension?
Can I use any correlation factor of liquid mixing for solid suspension? For example:
1. Np of 4PBT = 1.37 for liquid equal to solid
2. w/D ratio = 1.25
Please explain any correlation of solid equal to liquid and how can I find solid correlation for 2 impellers of 4PBT?
Category: Mixing

What would be the optimum blade size, speed, motor power required for a power stirrer?
We have a requirement for an industrial stirrer -- vertically mounted on top for 0.9 x 0.9 x 1m height square tank of capacity -- 0.81 m3, for 48% caustic solution obtained by mixing caustic flakes. We want to go for a high-speed stirrer. What would be the optimum blade size, speed, motor power required?
Category: Mixing

I want to make a portable stirrer for mixing various types of liquid soaps. Can I use an electric drill?
I want to make a portable stirrer for mixing various types of liquid soaps and emulsifiers with initial viscosity of water and the end viscosity varying from 50 cps -- 3,500 cps. The mixing is done presently in plastic barrels of 200 liter capacity. I presently hand mix it with the help of a 1 inch pvc pipe, 4-foot length.

My batch size is 200 kg at one time. Water is first, followed by addition of alkali and surfactants. I want to design a portable stirrer, electric drill type due to cost reasons, which can be clamped onto the plastic barrel for mixing.

Kindly suggest the type of electric drill and the type of blade and the shaft size -- I want to avoid excess foaming.
Category: Mixing

Is there some correlation to estimate the Np and Power consumption for anchor and helical ribbon impellers for non-newtonian fluids?
I have seen some similar questions in here, but haven't found the exact information I'm looking for. I'd like to know if there's some correlation to estimate the Np and Power consumption for anchor and helical ribbon impellers for non-newtonian fluids (pseudo-plastic) operating in laminar flow.
Category: Mixing

How do we select tank size and agitators?
If we want to mix an organic acidic powder with water for 5,000 liters capacity, how do we select tank size and agitators? The feed rate will be around 300kg/hr and the concentration will be 50 kg/m³
Category: Mixing

How can I calculate the power number and mixing time?
To characterize one of the reactors at plant scale, we use the discoloration method. During the discoloration method we also measured the power draw at different RPMs so that we are able to determine power number and mixing time at once. The latest reactor, however, consists of two different impellers at one shaft. Can you explain how I can calculate the power number and mixing time?
Category: Mixing

Does a method exist for determining blade angle when the use of a bevel protractor is not possible?
Does a method exist for determining blade angle when the use of a bevel protractor is not possible?
Category: Mixing

How do I build a mixer for a wide range of liquid detergents?
I have multiple plastic drum open head: width = 50cm, height = 90cm. I want to build a mixer(s) for a wide range of liquid detergent where viscosity is between 1 – 80,000 cps at ambient temperature ~30C. What is the most suitable design for motor power, shaft and impeller?
Category: Mixing

During scale-up, which dimensionless number should match?
During scale up in high-shear granulation, which dimensionless number should we match? Currently we are trying to match Froude number for dry mixing, Newton power number for binder addition and Reynolds number for kneading.
Category: Mixing

Is there a calculation to determine the difference in mixing when I change an agitator?
Is there a straightforward calculation to determine the difference in mixing when I change an agitator in a large vessel? I am "backtracking" a change in an agitator that has already been replaced. I seem to have a significant increase in mixing profiles, and am wondering how to proportionately decrease the agitator speed?
Category: Mixing

Can we thoroughly mix without breakage of the CPGs?
We currently produce our own derivatized controlled pore glass (CPGs). We purchase the CPG, derivatize with a linker and attach our reagents. Current batch size is 10 grams to 20 grams with mixing done on a wrist action shaker. We would like to scale up to 200-gram to 400-gram batch sizes. Derivatization processes use Acetonitrile, dichloromethane, THF, ether, methanol at various stages. We need to have the CPGs suspended and thoroughly mixing for uniform derivatization across the surface area (1000A pore size). Are there mixers that can thoroughly mix without breakage of the CPGs? At 400-gram batch size, there will be 4,000 - 8,000 L of solvent at different stages. I would like to keep the suspension in the same unit during most of the process and would like the ability to drain and wash the CPGs at various stages in the process.
Category: Mixing

How do I calculate agitator shaft size?
How do I calculate the effect of supporting the agitator shaft (at bottom or in the middle) on diameter size of shaft? Agitator is suspended from the top in a conventional way.
Category: Mixing

How can we ensure a successful scale-up?
During scale up in high-shear granulation, which dimensionless number should we match? Currently we are trying to match Froude number for dry mixing, Newton power number for binder addition and Reynolds number for kneading.
Category: Mixing

Where should the impellers be located?
We are designing a chromatography resin slurry vessel. Max volume is 300 liter. Minimum mixing volume is 50 liter. The tank will have 30 degree conical bottom head and flat top head. Agitator will be top-center mounted and must have two impellers and different heights to achieve complete mixing of 50% slurry of resin at the following volumes: 70 liter and 275 liter.

At which heights should I set two impellers to achieve complete mixing of the above slurry? At this time I do not have viscosity data on the slurry.
Category: Mixing

Can you offer specifications regarding the ideal RPM required for optimum mixing of lime slurry?
Can you offer specifications regarding the ideal RPM required for optimum mixing of lime slurry with effluent for optimum neutralization?

Details of our system and specification:

• Our daily inflow at ETP is 20,000 cubic meter per day.
• We are preparing and using 2.5% slurry of hydrated lime.
• As per our understanding, we have considered seven minutes of retention time in each tank and according to that, tank volume is 95 cubic meter (6.5x6.5x2.25(meter)).

Category: Mixing

Is there a textbook that I can purchase that works through mixing calculations?
I was wondering if there is a textbook that I can purchase that works through mixing calculations?
Category: Mixing

Is there a science for sizing submersible mixers?
Is there a science for sizing submersible mixers? I need to design an anoxic tank for a wastewater plant.
Category: Mixing

Is there a science for sizing submersible mixers?
I need to design an anoxic tank for a wastewater plant. Would you help me figure out the arrangement and quantities of submersible mixers? Dimension of anoxic tank is: 12*12.5*4m(L*W*H).
Category: Mixing

Can you offer guidance on polymer mixing and wastewater?
We are currently designing a static mixer to mix polymer and wastewater before the mixture is fed to a dewatering unit. In the lab, we have conducted a CSTR experiment to estimate the residence time required for good mixing. The results that we gathered for a 500 ml sample, 60 rpm CSTR is 15 minutes. However, we have realized that we cannot use this residence time for a static mixer since it is a different case. The wasterwater flow is 7 cu.m per hr and the polymer flowrate is 0.500 cu.m per hour with a pipe of 3 in diameter. We are planning to use a 4-inch diameter static mixer but we need to know the required residence time for the static mixer to determine the volume of the static mixer.
Category: Mixing

What's the easiest way to do impeller power calculations?
How do you calculate the power number, the Reynolds number and the hydraulic power for a tank ribbon mixer? The tank diameter is 2,700 mm and the height is 3,000 mm. The proposed ribbon diameter is 2,500 mm, pitch diameter is 2,500, number of ribbons is two. Also, what width should the ribbon be? SP.GR = 1.0; Viscosity - 100 CP; Suggested speed = 25 RPM.
Category: Mixing

Can you offer advice on a horizontal ribbon impeller?
I need to model a horizontal ribbon impeller mixing a viscous fluid in CFD. Do you have any hints how to accomplish this? I have access to both CFX and Fluent. This is an existing unit with vibration problems and a rather robust structural system supporting the ribbon.
Category: Mixing

What if we can't use a top-mounted mixer?
We have a closed U trough, capacity 8 cu.m with internal and external electric heaters to heat solvent waste and recover the solvents. In this circuit it took us a long time to finish one batch (10-12 hours), since we don't have any rotating parts inside the U trough. Solvent waste will be stationary. We are recovering 30% solvent/batch.

To reduce the batch time, we planned to agitate the solvent waste to get the effective heat transfer. We are not able to put the agitator on top cover to agitate the internal area. It took a long time to open the top cover and clean the waste. Also, to remove the solvent waste after completion of one batch, this reactor is designed to tilt and clean the waste.

Operating Pressure: 2 psi g
Operating Temperature: 600 -700 deg C
Category: Mixing

How do I calculate the power required by a motor?
How do I calculate the power required by a motor? I am designing a mixer that has the following specifications:

• Capacity = 15 ton
• Height of tank = 12 ft
• Diameter of tank = 8 ft
• Diameter of shaft = 101.6 mm
• Fluid viscosity = 650 dpa.s
• Impeller type = Helical Ribbon Impeller
• Rotational Speed = 50 rpm (max)
• Gear box = Reduction Gear having ratio 1:17

Category: Mixing

How can we improve our mixing?
We have a rectangular tank 3.3m x 2.1m x 1.6m deep. It has two 45-degree PTB stirrers located 1.0m from each end of the tank and 0.3m from the tank bottom. Each stirrer has 8 blades 50mm wide and 400mm long (diameter 800mm). Each stirrer has a max rpm of 130. The liquid we are mixing is latex paint with a viscosity of 16000 cp. Can you give any suggestions on how to improve our mixing.
Category: Mixing

Can you suggest proper mixing design?
We want to mix 3,000 liters of rubber solution (PTBP) (1.6 specific gravity). What is the best tank size --1,600mm x 1,600 or 1500 x 1800 mm? What type of impellor is required -- 2 stages or 3 impellors in equal distance at shaft? What is the power required? Will 60 rpm be enough? What is the shaft diameter and torque required?
Category: Mixing

How do we mix a solid slurry and solvent for best results?
We are mixing a solid slurry and solvent and need 2 micron size. What is the motor hp when the solid slurry's viscosity is 5,000cp? Its specific gravity is 1.5 and its total material weight is 5000 kg (70% solid slurry and 30% solvent.)
Category: Mixing

How do we modify a holding container to a mixing container?
We would like to modify the current holding container to a mixing container. What type of impeller will be recommended? How do you choose the correct one?

• Dimension = rectangular (8ft x 6ft x 5ft)
• Viscosity = initial at 400,000 cps (semi-solid state), after mixing with solvent, should drop to 5000 cps
• Circulated pump will be install to facilitate the mixing
• Objective: blending the semi-solids hydrocarbon and fatty oil with solvent in order to pump to the downstream system
  Category: Mixing

  What is the ideal diameter-to-length ratio for a vessel?
  What is the ideal diameter-to-length ratio for a vessel of 10kl capacity that is to be used for suspension preparation (solid-liquid mixing)? What is the disadvantage if I go for L/D=2?
  Category: Mixing

  How can we estimate the Reynolds number?
  How can we estimate the Reynolds number of an agitated conical flask in orbital shaker? How does it differ from estimation in stirred tank reactor with impellers?
  Category: Mixing

  What's the best way to check mixing design?
  We are designing a mixing process for a new installation in India. The first two mix tanks will be small volume -- 5 drum and 10 drum capacities. The question is based upon the 5 drum tank, which will be about 43 inches in diameter. A colleague has suggested that I locate the lower impeller 2 inches off the dish bottom. He suggests a radial impeller with a diameter of 4 - 6 inches. To avoid pump cavitation with the impeller in this location, he requested that I offset the mixer from the tank center by 1/2 blade diameter or 7 inches. In total he suggests three impellers. The two upper impellers would be axial type. For speed he suggests 60 RPM, 120 RPM and 240 RPM. The drivers behind these suggestions are several: 1) Produce volumes from 2 - 5 drums in the same tank. 2) Dissolve powders quickly when added early in the formula.
  
  Traditionally our tanks are designed using standard guidelines: Impeller 1/3 tank diameter spaced 1 impeller diameter off the bottom and 1 impeller diameter between each.
  
  Do his suggestions make sense? Our products are metal working fluids.
  Category: Mixing

  What is the type of blade to be used for mixing slurries of high viscosity?
  What is the type of blade to be used for mixing slurries of viscosity 100,000 poise? How is the power required calculated ?
  Category: Mixing

  Can you provide guidance on mixer design for an agitator mounted on a tank with these dimensions?
  Can you provide guidance on mixer design for an agitator mounted on a tank with these dimensions:

  • Tank: diameter = 8 m, height = 5.5,capacity = 250 m^3, material = mild steel (rubber lined), type=open, input/output = 260 m^3/h
  • Liquid: slurry, solid = iron ore, solid 40% to 60%, grain size = 0.3mm, gravity = 2.93 t/m^3, temperature = ambient, abrasive = 1200-1400 g/ton
  agitator purpose = to prevent sedimentation at the top
  Category: Mixing

  Can you calculate the power required by an anchor impeller to mix a fluid of known viscosity and density?
  Is it possible to calculate the power (in HP) of a motor required to mix product of viscosity X if you know the dimensions of the vessel and assume some standard design of mixing anchor? I want to be able to specify the power of the mixing motor to mix product with a specified viscosity in a vessel of known dimensions.
  Category: Mixing

  Is creating a vortex the best way to achieve the greatest amount of composition and temperature uniformity?
  I have two round containers in which I would like to create a vortex with the greatest amount of surface area. I would like to use impellors centralized at the bottom of the units, which would provide the greatest amount of mixing/density and thermo linearity in the fluid as well as the least turbulence.
  
  The liquid material in each container would have a range of viscosity from that of water (1-5 centipoise) to that of light motor oil -- approximately 200 centipoise).
  
  The range of volume in each container would be from approximately 85% full to approximately the top of the impellor blade on the bottom of the container.
  
  Dimensions of the first container are: Height- 2.25 meters, Diameter- 2 meters, Volume- approx. 6000 liters
  
  Dimensions of second container are: Height- 1 meter, Diameter- 0.5 meter, Volume- approx. 200 liters

  1. What size of impellors/drive motor would I need for these containers to cover the range of volumes in each ( from almost full to almost empty) and its distance from the bottom of the container?
  2. Is a variable speed drive available with tank level feedback control?
  3. Is an impellor blade unit available that can also perform heating operations (say 0 to boiling and beyond) with feedback temperature control from within the tank?
  4. If ingredients are added to the containers, will they be mixed/suspended evenly with the liquid volume?
  5. What are the pressure considerations if these units are sealed/closed?
  6. The tanks are insulated, can you estimate how much power consumption is required?
  7. Lastly, do you have a formula to calculate the surface area of a vortex and the impellor size required to produce it-is there a vorticity equation?
  
  Category: Mixing

  How do you create an emulsion?
  Please tell me what type and size of a mixer I need to mix oil and water to make an emulsion. I understand I need high shear for the process.
  
  The diameter of the tank is 2.6m and the height is 1.5m. The solutions that I want to mix have the density as follows:

  • Solution 1 ρ = 0.89 kg/m³
  • Solution 2 ρ = 1.2 kg/m³
  • The operational temp is 60 C since solution 1 will burn at higher temperature and solidify at temp below 20 C
  • Solution 2 will degrade at temp above 60 C
  
  Category: Mixing

  Why is the mixer getting stuck?
  We have a stainless steel reactor running with isopropyl alcohol. We add potassium carbonate and then add methyl acetoacetate. My problem is during the methyl acetoacetate addition and mixing -- the reactor is getting stuck. The reactor capacity is 5 kl; the agitator is anchor type; the RPMs are 30 and the motor capacity is 15hp.
  
  Are there any standards for gear box, motor horsepower and anchor size?
  Category: Mixing

  What type of impeller and engine power should I use for the following service?
  What type of impeller and engine power should I use for the following service?
  
  

  • Tank: Diameter = 2m, L = 5m (17m³ Capacity)
  • Fluid = Vegetable oil (I think viscosity = 60 cP, density = 900 kg/m³)
  • Temperature: Reaches 130 degrees C
  
  Category: Mixing

  What is the best mixer for solids and liquids?
  I want to mix a solid with a liquid with the ratio of 50/50. But the solid is water wet 30% and I have to drive off the water while mixing the two components. What is the best mixer to use to first get the water to the top of the vessel, evaporate off and also mix the solids and liquid? Solids density is 1.6 g/cc, liquid is 1.5 g/cc.
  Category: Mixing

  What is causing the mechanical problems with agitators?
  I am currently mixing 4 tons of product with a density of 8.4lb/gal that is very sensitive to over mixing. My current mixer design has reliability issues. There are two counter rotating agitators in the tank which are about 8' long by 5' wide. While running, the agitators sway due to either fabrication quality or design flaws. I currently have 2" and 4" shafts extending down from the gear box into the tank. I am being sold on two different design options:
  
  1.) Add a steady bearing to bottom of tank to reduce movement and my issues with this are the following:
  a. Ability to CIP;
  b. Have not corrected the problem just hid they symptom;
  c. Failure of the tank due to shaft hitting steady bearing in the repeatedly in the same place.
  
  2.) Increase the size of the shaft to 6" and 3" my issues are the following:
  a. Work required to perform repair (cut off top of tank and replace with new cover);
  b. Cost associated with new gear box installs.
  
  My question is for this application in a pharmaceutical environment, what would be the best course of action? Is there any published literature on the subject? Lastly are these design solution accurate or should I be looking at other alternatives?
  Category: Mixing

  What are the motor powers and shaft diameters for these agitators?
  To be used in various tanks we need to get your answer for agitator motor power and shaft diameter for the following agitator data:
  
  Agitator A:

  • Liquid in tank: Density = 1.09 t/m³ Dynamic viscosity = 150 mPa.s Temperature = 85 degrees C (average)
  • Speed: 95 rpm
  • Length in tank = 3650 mm
  • Impeller: 1 row, 2 blades , 900 mm in dia.
  • Tank volume= 40 m³
  Agitator B:
  • Liquid in tank: Density = 1.4 t/m³ Dynamic viscosity = 100 mPa.s Temperature = 80 degrees C (average)
  • Speed: 85 rpm
  • Length in tank = 4750 mm
  • Impellers: 2 rows, 2m between rows, 2 blades at each row , 1300 mm in dia.
  • Tank volume= 28 m³
  Agitator C:
  • Liquid in tank: Density = 1.48 t/m³ Dynamic viscosity = 10000 mPa.s (average) Temperature = 70 degrees C (average)
  • Speed: 66 rpm
  • Length in tank = 5630 mm
  • Impellers: 3 rows, 1m between rows, 2 blades at each row , 800 mm in dia.
  • Tank volume= 15 m³
    For the above agitators, I need motor powers and shaft diameters.
    Category: Mixing

    How do I calculate the dynamic force on the agitator?
    How do I calculate the dynamic force on the agitator? The details are as given:

    • Capacity of mixer: 15 Kl
    • Motor: HP 75 HP
    • shaft speed: 48 rpm
    • diameter of vessel: 2450 mm
    • st. height: 3000 mm
    • dish height: 491 mm
    • stirrer: anchor type
    • sweep dia: 2300 mm
    • material viscosity: 40 poise (emulsion-based paint)
    
    Category: Mixing

    How do I calculate the Reynolds Number of a multiple-blade agitated vessel?
    I am trying to calculate the Reynolds Number inside an agitated vessel with two 45-degree-pitched turbine blades and internal cooling coils. I know all of the geometric data for the vessel, blades, and coils. How does the Reynolds Number equation change to account for having two blades? Right now I'm using Re=rho*D^2*N/mu where D is the agitator diameter and N is RPMs.
    
    Also, is there a way to correct for the internal cooling coils, which act as baffles? How would the Reynolds Number change? Are there any equations you can suggest that takes into account fluid flow changes due to the coils?
    Category: Mixing

    How would I determine a dimensionless mixing coefficient?
    Given a ribbon mixer with a Froude Number of 1.04, how would you determine the dimensionless mixing coefficient?
    Category: Mixing

    How do you scale a flat-blade mixer for a small container?
    I am designing a flat-blade mixer for only 5 liters of fluid at a density of roughly 1500kg/m³. I'm having trouble scaling this mixer. Are these numbers about right?

    • Container Diameter: 0.19m
    • Container Height: 0.21m
    • Impeller Clearance: 0.04m
    • Impeller Diameter: 0.1m
    • Impeller Height: 0.05
    • Impeller Forces: 1N
    • RPM: 120
    • Motor Power: Approx 0.5HP
    
    Category: Mixing

    What are the required changes for re-rating a mixer?
    Can a chemical mixer of 316ss rated at -40 degrees F be re-rated to -80 degrees F? The vessel walls are 1/2-in. thick.
    Category: Mixing

    How do you calculate pipe diameter, mixer size and type, and other design parameters?
    Currently we are working on a water treatment plant and we chose static mixture for our rapid mixing process. Here is what we have:
    
    Application: Surface water treatment (river water)
    

    1. Designed flow rate : 160m³/hr
    2. Water temp : 30 C
    3. Viscosity : 0.9499 m NS/m²
    4. Density of water : 0.994 mg/l
    Please advise how to calculate pipe diameter, mixer size and type, numbers of elements and other design parameters.
    Category: Mixing

    What is the best way to minimize air bubbles?
    1. How do I minimize air bubble in Latex compounds?
    2. What is the recommended stirrer/agitator type to avoid air-bubble formation during mixing (compounding)?
    3. What is the effective de-aeration method for latex compounds?
    Category: Mixing

    How would you design an agitator for equalization tank of wastewater treatment plant?
    Can you please help me to design an agitator for equalization tank of wastewater treatment plant?
    
    It is a rectangular tank with the dimensions L=8.5m x w=8.5m x D=3.75m and water depth=3.25m. Density is 1000kg/m^3.
    
    Please tell me which impeller types I can use to agitate water in equalization tank, what should be diameter of impeller, rpm, and what will be motor power. If it is possible, please tell me the formulas you will use to calculate these so that I can use them for my future calculations.
    Category: Mixing

    Can you offer advice for impeller diameter and speed?
    I would like to maintain homogeneity between water and solid. The solid content is 5% weight. My tank dimension would be 3380 mm (ID) and 3700 mm (height) -- it's cylindrical. I want to use three-blade hydrofoils impeller with 889 mm diameter impeller, 84 rpm and power motor will be 0.75 Kw. Will this produce good mixing?
    Category: Mixing

    How do I determine the thermal energy introduced into the system by dispersion blades?
    I am adding two 15-inch dispersion blades (Indco Design D) to a blender with a helical sweep blade. The dispersion blades will be powered by a 15 hp motor geared down to an output of 475 rpm. The material mixed in the tank is thixotropic: 150,000 cps at 5 rpm and 35,000 cps at 50 rpm with a density of 8.4 lbs/gal. The blender has a diameter of 61 inches and a straight side height of 49 inches.
    
    I would like to maintain a temperature in the blender of about 80 degrees F. Can you please show me how to determine the thermal energy introduced into the system by the dispersion blades?
    Category: Mixing

    Is there a formula available for the Reynolds number, power number and correction factor?
    I need to calculate the power required by Lightnin A320 impeller, in viscous (laminar) and transition region. Is there a formula available for:

    1. Reynolds Number
    2. Power Number
    3. Correction factor for Power Number
    
    I will be using 0.64 as the Turbulent Power Number.
    Category: Mixing

    Will a change occur in impeller power number if we change the blade angle?
    Will a change occur in impeller power number if we change the blade angle of the pitched turbine impeller 45 degrees to 60 degrees? And how can I calculate this value?
    Category: Mixing

    For mixing solids application what is the recommended baffles length?
    For mixing solids application what is the recommended baffles length? Should the baffles start above the liquid level and end at the bottom of the tank or only past the impeller? I heard that for better mixing at the surface the baffles should start a little bit below the liquid surface and end above the tank bottom to reduce stagnation points. Is it true? At which height should the baffles start and end?
    Category: Mixing

    What could cause drag to where the rpm output isn't constant?
    What could cause drag to where the rpm output isn't constant? We have a thin/shade tank where grind potion and latex are blended. We have a variable speed motor with shaft and propeller driven agitation. It doesn't matter the weight of the product.
    Category: Mixing

    Is there a formula to calculate axial thrust?
    When we recommend submersible mixers for a circular or rectangular tank containing effluent or sewage, there is a software solution that gives the axial thrust required for the particular tank when we feed in the dimensions of the tank and concentration of solids present. Is there any simple formula to calculate the Axial thrust for a particular tank?
    Category: Mixing

    How can I stop fluctuations at the fluid surface?
    I'm using 140mm diameter tank to mix two liters of fluid with viscosity of 0.5 Poise. On the tank there are four 13mm baffles. The impeller is Rushton Turbine with 6 blades.
    
    The mixer is operating at 10,000 rpm (the application is particle size reduction). At high rpms (above ~6000), I'm having serious fluctuations at the fluid surface, which causes splashing of the fluid. I also see big fluctuations at the torque of the motor during the operation.
    
    What can cause it and how it can be solved?
    Category: Mixing

    Is my mixer design correct?
    Is my mixer design correct? I have a tank 28-feet diameter, 33 feet tall with 26 feet of side water depth. I am mixing 7% sludge with viscosity in the range of 0 - 3000 cP. The mixer has a 40 HP motor with two impellers -- each 128-inch in diameter. The shaft diameter is 5.5 inch (upper) and 4.5 inch (lower). Mixer will mix with a 25 rpm. Liquid level will vary significantly in the tank with one or both exposed.
    Category: Mixing

    Is my motor the appropriate size for the mixing intensity I need?
    I have 100 liter vessel. The diameter of vessel is 470 mm. Impeller size is 140mm, impeller shaft height is 900 mm. I need to run impeller at 200 rpm. The solution to be mixed has the same viscosity and density like water.
    
    Can I use 0.5 hp motor for above application or do I need a higher size motor?
    Category: Mixing

    Is my mixer design correct?
    Is my mixer design correct? I have a tank 28 feet in diameter, 33 feet tall with 26 feet of side-water depth. I am mixing 7% sludge with viscosity in the range of 0 - 3000 cP. The mixer has a 40 HP motor with two impellers -- each 128 inches in diameter. The shaft diameter is 5.5 inch (upper) and 4.5 inch (lower). Mixer will mix with a 25 rpm. Liquid level will vary significantly in the tank with one or both exposed.
    Category: Mixing

    Can you offer an equation to determine mixer torque based on a viscosity?
    I am looking for an equation to determine the torque required for a vertical mixer based on a viscosity in cps. I have a known volume and impeller power number.
    Category: Mixing

    Is there any formula for calculating the height of an anchor agitator?
    Is there any formula for calculating the height of an anchor agitator? We have a reactor with these specifications:

    • Reactor capacity 5 KL
    • ID 1650 mm
    • Height of shell 2400 mm
    • Motor 10 hp
    • Sweep diameter 1160 mm
    • Height of liquid 2071 mm
    • Liquid is MDC
    
    Category: Mixing

    How do we determine residence time in the dissolution tank?
    After we know the dissolution rate and the amount of the salt to be dissolved, how can we determine the residence time required in the dissolution tank?
    
    The process of dissolution is required on continuous basis.
    Category: Mixing

    Is my mixer sizing correct?
    Is my sizing correct? I have a tank with the following dimensions: 30-inch diameter x 48 inches deep. I have a 3 hp motor and two 11-inch marine propellers I plan on using. The fluid viscosity is between 8,000 to 11,000 centipoise. My calculations show that if I run that system at about 350 rpm I will actually need 0.5 hp and I will be in the transition region with about 10 tank turnovers per minute. The fluid will drop below the first propeller. Is this a problem? I also plan on making a lid to mount the 3 hp motor with direct drive and no bearings. Will the mount be OK with out bearings? The mixer will be directly over the tank (vertical).
    Category: Mixing

    What speed should I target for maximum agitation?
    I have a process tank that boils water to approximately 250 degrees F. It is horizontal and has dimensions of 36 inches in diameter and 5 ft. sidewall. There is a mixer .75 HP in the center of the tank operating at 1750 RPM. The mixer has a shaft that is 5\8 inches in diameter and uses a marine style propeller at 8 inches from the bottom (length to bearing approximately 28 inches). What would my critical speed be? What speed should I target for maximum agitation?
    
    I don't think full agitation is possible, due to prop size vs. amount of water. However, I would like to move as much water as possible. Should I consider a steady bearing at the bottom of the vessel?
    
    What would the critical speed be for a 5\8 inch shaft 28 inches in length with a marine prop in water be?
    Category: Mixing

    Can you help me size a mixer?
    I have a tank that is 5 meters diameter and 7.5 meters tall. The bottom is flat. The liquid is water. The solid is small metal oxide particles very easy to suspend. Settling time is more than minutes. Would like to build a mixer for suspension only (not vigorous mixing).
    
    Question: 1. What mixer diameter do I need? 2. What RPM? 3. What shaft diameter needed? 4. What HP do I need? 5. Do I need bottom shaft support and bearing?
    Category: Mixing

    How do I calculate the agitator power in terms of volume increasing?
    How do I calculate the agitator power in terms of volume increasing?
    
    

    • Diameter of reactor-1.95m
    • Diameter of agitator-1.1m speed-96rpm
    • Volume of rector-6.3 kL
    • Volume of material-3.75 kL
    • Viscosity of material-30000 cp density of material-800 kg/m3 reactor type- GLR
    • Agitor type- 3 blade propeller no baffles
    What is the power consumption of this volume? I am increasing the volume of material up to 5 kL what is the power consumption in the same reactor, same material?
    Category: Mixing

    How do I calculate the agitator power in terms of increasing volume?
    How do I calculate the agitator power in terms of increasing volume?
    
    Here are the specs: Diameter of reactor - 1.95m
    Diameter of agitator - 1.1m
    Speed - 96rpm
    volume of rector - 6.3 kL
    volume of material - 3.75 kL
    Viscosity of material - 30000 cp
    Density of material - 800 kg/m³
    Reactor type -- GLR
    Agitor type - 3 blade propeller with no baffles
    
    What is the power consumption of this volume? I am increasing the volume of material up to 5 KL. What is the power consumption in the same reactor, same material?
    Category: Mixing

    Can you suggest a mixer for minimal suspension of slowly settling particles?
    I have a tank that is 5 meters in diameter and 7.5 meters tall. The bottom is flat. The liquid is water. The solid is small metal oxide particles that are very easy to suspend. Settling time is more than minutes. Would like to build a mixer for suspension only (not vigorous mixing).
    
    Question: 1. What mixer diameter do I need? 2. What RPM? 3. What shaft diameter needed? 4. What HP do I need? 5. Do I need bottom shaft support and bearing?
    Category: Mixing

    How can I size a dissolution unit?
    I've just started to work on a project and I need to size a dissolution unit for salt and a dissolution unit for soda ash. I don't know where to start. What formula can I use to calculate the size of the dissolution vessel (diameter, length)? Is there a database with types of mixers?
    Category: Mixing

    How do I calculate the size of the dissolution vessel?
    I need to size a dissolution unit for salt and a dissolution unit for soda ash but I don't know where to start. What formula can I use to calculate the size of the dissolution vessel (diameter, length, etc.)? Is there a database with types of mixers?
    Category: Mixing

    Can you suggest a motor horse power and gearbox torque?
    We have a carbon steel vessel that is rubber lined with data: vertical; cylindrical 4,450 mm by 4,540 mm; flat top with a conical bottom that is1,290 mm by 4,540mm; impeller ANCHORE type with blade width 365 mm (rubber lined); impeller diameter is 4,540 mm and height is 1,555 mm. Temperature is 60 degrees C; capacity 75 cubic meters; specific gravity 1.13; viscosity 15 Cp.; RPM 30.
    Category: Mixing

    Can you tell me how to design a simple mixer for mixing solids and liquids?
    Can you tell me how to design a simple mixer for mixing solids and liquids? The specifications: Tank total capacity is 220 liters; diameter is 1,000 mm by 1,200 mm; liquid for mixing 150 liters (120 liters and solids 30 kGS); 60 RPM.
    
    Can you suggest a shaft diameter, the type of agitator/anchor/blade and capacity of the motor?
    Category: Mixing

    What is the maximum viscosity of fluid I can mix with a certain agitator?
    I have a 5,000 liter reactor with the following geometry: 56-inch ID, 126-inch straight side length, ASME bell top and bottom. There are three baffles along the straight sides of the tank spaced 120 degrees apart and are 6.25 inches in width. The agitator I have is center-mounted with three blades approximately 13 inches in diameter. The drive is 1 hp with a 1,725 rpm motor and a 175 rpm output gear reducer. The shaft size is 1.5 inches and approximately 153 inches in length.
    
    Unfortunately, the viscosity of my product changes during the process. It starts out as a low viscosity (close to water) fluid, becomes thick as it is heated, and then thins out again as the reaction progresses. I need good agitation for heat transfer.
    
    What is the maximum viscosity of fluid I can mix with this type of agitator?
    Category: Mixing

    Can you suggest motor speed and RPM for a viscosity index improver kettle?
    We are erecting a viscosity index improver kettle in which we are going to heat base oil (5 to 11 cst) up to 160 degrees centigrade to mix with polymer. The product final viscosity will be 1,400 to 3,000 cst at 100 degrees centigrade.
    
    The size of the kettle: 1.9 diameter and is 2.75 meters in height. The mixing will be through agitator of 4 blades of (750X10mm) of approx 45 degrees.
    
    How much RPM should we use? Is a 15 HP motor is sufficient?
    Category: Mixing

    What size impeller will disperse fine carbon powder in ethanol/water mixture?
    What size impeller should I use to mix ethanol and water (40% ethanol) in a 275-gallon plastic IBC tank? I also want to disperse and mix a fine carbon powder into the thoroughly mixed ethanol/water mixture. I'd really like to use something that can be attached to an electric drill.
    Category: Mixing

    Can I estimate how much I need blend using the recirculation loop?
    I had previously asked regarding the use of recirculation loop for mixing. Here are couple scenarios to use recirculation loop for mixing:
    
    1) The batch size smaller than minimum batch size to use agitator in the existing vessel
    2) Impeller mixing not desired (I am guessing due to high shear from the existing impeller)
    
    Yes, the recirculation loop will be inefficient, but for the products that may not be made ever again, upgrading the existing resources is not an option.
    
    If I can use the Betty Crocker equation or the data from various studies to estimate the max volume or the time for the blending using the agitator, can I estimate how much I need to scale down or how much longer I need to blend using just recirculation loop? I can't find any study on the role of recirculation loop in mixing. Neither did I get any insights from "Handbook of industrial mixing: science and practice."
    Category: Mixing

    Can you provide a guide to baffles?
    Somebody said to me that the pipe used as baffle will not break vortex in the tank and the flat baffle across the flow is needed (300 mm min in my case). Is this correct?
    Category: Mixing

    Can you help me determine impeller diameter and torque?
    I need to determine torque required to mix H₂O and some chemicals in a 4,000 gallon vertical tank with a viscosity of SAE90 after mixing. The tank inside has a diameter of 119 inches with 4 blades that are 45 inches across, 8 inches wide with a 45 degree angle. The blade is 31 inches from the bottom and is mounted on a 2 inch vertical shaft. They need to run this from 60 RPM to 120 RPM.
    Category: Mixing

    Is there a means to accurately have the deflection measured and to check center of shaft relative to bottom bearing?
    I read your article in ChemicalProcessing.com on mixers and would like to determine if you could help me in a problem seal we have on a high pressure reactor. The reactor operates at 350 degrees F, 135 psig and the 4-inch diameter shaft speed is 100 rpm (10 foot shaft length). Seal is John Crane type 8 and uses mineral oil flush with 160 psig nitrogen pressure.
    
    We have frequent seal leaks into vessel as seen with loss of barrier fluid. Sometimes we blow seal out but most it is internal.
    
    Shaft deflection is high due to worn bottom bearing and to it being possible off center. We really need to verify how much deflection we have and verify if we are center to reactor (long story). My question: Is there a means to accurately have the deflection measured and to check center of shaft relative to bottom bearing?
    Category: Mixing

    How do you determine the liquid force on the baffle?
    I have a tank of 1.6 m diameter and 3.5 m height containing liquid of 1.1 density. I need to install an agitator with one impeller of 300 mm diameter, 3 m shaft length, and with one baffle at 600 mm from the tank center. The agitator's speed is 420 rpm, motor power 2HP. I would like to determine the liquid force on the baffle.
    Category: Mixing

    How do you estimate the torque needed for a small chopper/blender assembly?
    We are trying to calculate the torque needed for a small chopper/blender assembly, which will operate at two different speeds. The lower speed is <50 rpm and the higher speed is around 2000 rpm.
    
    Diameter of the bowl is 100mm
    Height of the bowl is 100mm
    Rod diameter is 10 mm
    Agitator has 4 sharp propeller blades
    Length of blade is 30mm
    Diameter of agitator with blade is 70mm
    
    The material will be a solids/liquid mixture to start with. The solids are coarsely chopped food contents, and take about 60-70% of the volume.
    
    The intention is to use the low speed to agitate the mixture gently in the early process, then use the high speed to chop/blend the content into a homogenous mixture later.
    
    How should we estimate the torque involved in these two processes?
    Category: Mixing

    Are there conditions when the agitation system cannot suspend a catalyst?
    I have a 500 ml Parr reactor, equipped with a 4-blade turbine impeller. My reaction solvent is diglyme and the catalyst is a noble metal on silica gel. The catalyst loading is 0.3 wt%. At room temperature, using the glass reactor liner, I can visually confirm suspension of the catalyst at a given RPM. My question is: Holding the RPM value constant, what happens at near critical conditions when the fluid viscosity and density drop? (300 Deg C, 300 psig). Are there conditions when the agitation system cannot suspend my catalyst? Assume particle size is 100 microns.
    Category: Mixing

    How do I design a multi-concentric shaft for a fixed tank unit?
    I want to design a multi-concentric shaft for a fixed tank unit of 2m³ capacity. The mixing materials are PVC and DOP for blending of Plastisol.
    
    The unit has to have a solid shaft fitted with cowels for dispersion and the hollow shaft will move in contra-motion and shall have scrappers for scrapping the layer formations on the tank inside walls during mixing.
    
    Can you suggest a reference book?
    Category: Mixing

    How do you calculate the power required for helical impeller mixer?
    I need help in calculating the power required for helical impeller mixer. Here is the data:
    
    1. Helical Impeller diameter 0.600m
    2. Diameter of tank 0.650m
    3. Height of tank 1m
    4. Viscosity of polymer 200 poise
    5. Density of polymer 1560 Kg/m³
    6. Pitch of helical impeller 0.3m
    
    I also need the power factor for helical impeller please.
    Category: Mixing

    What are the specs to construct a computer controlled Agitation Experimental Module?
    I'd like to construct a computer controlled Agitation Experimental Module for students.
    
    The tank Volume can be 1 L up to 10 L. The liquid viscosity can be water up to lubricant Oil SAE 140. We can do it with the presence or absence of baffles. We can do it with different impellers, different position of impellers. The speed will be near to 2000 rpm.
    
    Could you please advise what kind of electro-motor I should use? Can I use 3-phase inductive motor 2800 rpm (2-pole), 1-HP power? How about the torque? Please suggest also how to calculate.
    Category: Mixing

    What is the torque required for speed reducer and what horsepower is required to run it smoothly?
    What torque of speed reducer is required to mix 300 kgs of sand? Mixing type where drum is stationary and blades rotates in horizontal position. Features a 3 hp motor, gearbox ratio 30:1.
    
    Additionally, the drum size is 30 inches in diameter and 42 inches in length in horizontal position. Blades are paddle type.
    Category: Mixing

    What is the general formula of agitator flow capacity?
    I'd like to know the general formula of agitator flow capacity. I found as follows:
    
    Flow capacity: Q = C1 x n x D2 x S
    
    Power required: P = C2 x r x n3 x D5
    
    Q = Agitator flow (m³/min)
    P = Power (kW)
    n = Revolution speed (rps)
    D = Propeller diameter
    S = Propeller pitch
    r = Density (Kg/m³)
    C1 = Factor specific for the propeller
    C2 = Factor depending on turbulence
    
    Can this be applied to a side-entry agitator?
    Category: Mixing

    How do you determine the power number for a mixing system?
    I am looking for an estimated power number for a low-shear impeller (commonly called an elephant ear impeller) for a system operating in the turbulent regime with the following characteristics:
    
    Baffled Tank (4 baffles)
    Dagit/Dtank ~ 0.4 - 0.5
    Density/Visc ~ water
    The impeller is down-pumping
    
    How would you recommend experimentally determining the power number for a larger system if torque measurement isn't an available option?
    Category: Mixing

    Is my mixer size too large?
    Would a four-blade, 45-deg pitched, 14-inch diameter impeller be too large or about right to mix a square IBC - 340 gallons of sp gr = 1 and viscosity of up to 100 centipose liquid, turning at up to 350 rpm, 2 HP motor.
    Category: Mixing

    For mixing, how do I convert from hydraulic power to an electric motor?
    Presently we are using hydraulic drive for the mixing of our paint ingredients in 150 lit mixer pot (maximum viscosity 35000 cP at RT).This pot is having heavy duty stirrer centrally located and one cowler at the off center (pot wall side located). The directions of these stirrers are opposite to each other. The shaft diameter of center stirrer is 52mm and of cowler is 40.5mm. Can I convert this to electrical drive? Also we are going to have 300 lit capacity new pot mixer so can I go for electrical drive instead of hydraulic drive to get cost benefit?
    Category: Mixing

    What is the best indicator of performance and efficiency of a mixer?
    We will be constructing a plant that will require many agitators. We have bids out to suppliers and have received responses. In addition to the cost, what would be the best indicator of performance and efficiency that could be used given the normal feedback from vendors such as installed power, weight, gearboxes, shafts, shaft speed, impellers, and materials of construction? Is there a best factor or ratio of these parameters that one could use to decide upon the best vendor? Simple relationships would be preferred that do not need such things as mixing constants and fluid densities.
    Category: Mixing

    Can you recommend an agitator that will fully suspend and dissolve salt?
    I am looking to dissolve fine salt in water in a continuous process. The aim is to produce near-saturated brine without any suspended solids.
    
    Fine Salt
    • Mass flow rate = 1000 kg/hr
    • Bulk density = 1200kg/m³
    • Temperature = 60-70 degrees C
    
    Water
    • Mass flow rate = 4000 kg/hr
    • Temperature = 20-50 degrees C (water is generally at 50 degrees But sometimes at lower temp of 20 degrees)
    • Dynamic Viscosity = 1.003 – 0.55 cP
    • Pressure = 4 Bar
    • Total flow rate into the tank = 5 m³/hr
    • Residence time of 5 minutes
    • Total flow rate out of tank= 5 m³/hr
    
    Vessel is under atmospheric pressure. I am having difficulty in selecting a stirrer that can both fully suspend the salt while also dissolving it. Can you recommend an agitator and a desired operating speed?
    Category: Mixing

    What are the problems with running a mixer in air?
    Agitator mechanical test in air is one of the requirements of our client. But most vendors claim they can't test in air. They say, "We cannot satisfy the deflection requirement when agitator would be tested in air, but if you want the 4 hour air test the shaft and agitator should be overdesigned." But they don't clarify the reason why the deflection will be increased in case of air operation. Could you clarify technically why deflection is increased?
    
    Our liquid contents are 45% mixing xylene and solid contents is px-xylene.
    Motor power is 7.5kW
    Shaft diameter is 63.5mm
    Length 5500mm
    RPM 56RPM
    Category: Mixing

    How do I determine torque?
    I need to determine the torque required to mix H₂O and some chemicals in a 4,000 gallon vertical tank. The viscosity is SAE90 after mixing. The tank inside diameter is 119 inches with four blades that are 45 inches across, 8 inches wide with a 45 degree angle. The blade is 31 inches from the bottom and is mounted on a 2-inch vertical shaft. They need to run this from 60 rpm to 120 rpm -- can you help?
    Category: Mixing

    Is chemical "Injection" used anywhere other than the carwash industry?
    Is chemical "Injection" used anywhere other than the carwash industry? It seems to me that there would be quite a few applications in the paper-making industry where this might make sense.
    Category: Mixing

    How do I determine the mixer design size of the impeller, the baffle plates and motor?
    I have a formalin flat-bottom tank made of stainless steel and the size of 8m (height) and 4.570 diameter wide. The formalin viscosity is very low -- close to water. How do I determine the size of the impeller, the baffle plates and motor?
    Category: Mixing

    How can I update the efficiency of very old mixers?
    I am new to the job and have been assigned to look at the efficiency of our very old mixers (salvaged from other plants). We use our mixers to dissolve rubber in solvents to make adhesives. (Final products viscosity ranges from average 5000cP, max around 10,000 cP)
    
    Some data I have collected:
    
    Tank: vertical cylinder diam = 1.25m, height = 5m, no baffles
    Stirrer: 2 number of Rushton turbine, 8 blades
    Motor: belt type 40hp, 330rpm
    
    Deep vortexes are noticed during operation. From what I have read this indicates fluid swirling, which is the worst kind of mixing because very little axial mixing is taking place.
    
    Using the general guidelines for solid dissolution, I am considering installing baffles and changing the stirrer to a pitched blade turbine in the hope to bring down mixing time and hopefully the hp of the motor as well. Where do I start and how do I estimate the "improvement" quantitatively?
    Category: Mixing

    Can you provide the power number for anchor-type impeller and Cowles disc impeller?
    Can you provide the power number for anchor-type impeller and Cowles disc impeller?
    
    I am calculating power for agitator by using P = (Np * Sp. Gr * N3 * D5)/ (1.524*1013)
    Category: Mixing

    Why does the motor trip on the anchor impeller with wall baffles?
    I am have a 12 KL reactor with 4 Nos of baffle. I have fixed anchor agitator with 48 RPM. But during trial, the motor is tripping at volume of 6.5 KL. The media is water.
    
    Reactor diameter: 2250 mm ID
    Shell length: 2700 mm WL to WL
    Agitator details
    
    Capacity: 12KL
    Shaft Diameter: 115mm, SS 316
    RPM: 48
    Agitator: Anchor, SS 316
    Sweep Diameter: 1850 mm
    Height: 1300 mm
    Blades: 125W x 12Thk
    Stiffeners: 50W x 8Thk
    Bushes: ID115 x OD170 x 135Ht
    Shaft Sealing: Single Dry Mechanical Seal
    Gearbox: Ratio 30:1, In-line Helical
    Motor: FLP Vertical Flange Mounted,1440RPM
    Category: Mixing

    How do I calculate the kLa of a mixed gas system using 75% air and 25% O₂?
    How do I calculate the kLa of a mixed gas system using 75% air and 25% O₂ from mass transfer data collected using the gassing out method with 100% air?
    Category: Mixing

    How do you calculate the power number of an impeller?
    How do you go about calculating the power number (Np) of an impeller?
    Category: Mixing

    When is it appropriate to use a recirculation loop?
    How does the mixing from recirculation loop from the bottom of the vessel compare to that provided by the agitator? I am guessing this will depend on various parameters like agitator rpm, agitator impeller types, recirculation flow rate, recirculation discharge height, where is recirculation discharged from, volume to be mixed.
    Category: Mixing

    Mixing: What's causing the blades to bend?
    Many blades on our melter agitator line have become bent. Can you give advice based on the below specification?
    
    Specification of melter agitator line 1:
    • tank size diameter 2200 mm x 2500 mm height
    • using gear box with ratio: 20:1
    • motor KW: 7.5 KW, 750 rpm
    • rpm shaft agitator: 48 rpm
    • shaft agitator dia 80 mm pipe schedule 80
    • 2 – blades position (bottom and center of tank height) with size diameter 1590 mm x 100 mm wide
    • Handle slurry liquid with spec: sodium sulphate slurry (Na₂SO₄), temperature 110 deg C, concentration 20%, density 1.4, level 100%
    Category: Mixing

    Are power requirements for multiple impellers additive?
    With multiple impellers on a single shaft, are the effects on total power additive? For example, if two impellers are of the same type, would the power be determined as P = Np*rho*N^3*(D1^5+D2^5)? Also, what is a "rule of thumb" for empirically calculated power requirements vs. actual power input that a VFD might show?
    Category: Mixing

    What are the power requirements for turbulent mixing?
    We have an agitator with the following designation:
    
    Speed: 31/46 rpm
    Absorbed power:1.5/5.4 kW
    Impeller type: paddle (and blades angle is reversed in tip area)
    Shaft dia: 85 mm
    Shaft length: 3300 mm
    Impeller dia: 1600 mm
    Impeller num.: 2
    Space in: 650 mm
    Motor rating: 12/3.7 kW
    Motor speed: 1470/980 rpm
    
    Materials specification: density (kg/m³)/viscosity (cp)
    1- liquid 1166/1
    2- powder 600/-
    3- liquid 794/0.32
    4- liquid 971/0.36
    5- liquid 1408/9.1
    
    This agitator is installed on a drum with 2400 mm diameter and 3754 mm height and the agitator is top entry.
    
    We want to change the process media with a liquid that its density is 1200 kg/m³ and the viscosity is 200 cp.
    
    Is the change in density and viscosity (as above mentioned) allowed or is this agitator (with no change in motor rating, gear box, shaft diameter and blade length) capable to mix the new media without any failure?
    Could you please to send us the required formula to obtain the shaft power, power number and etc.?
    Category: Mixing

    Which agitator seal will work best for outlet piping?
    I have a question about outlet piping of condensers. I have made a pilot reactor (top entry agitator) and now I want to use an agitator seal (except mechanical seal). Which type of agitator seals can I use so it works in higher pressure, stuffing box or the others?
    
    Reactor properties:
    
    Cap diameter: 500mm
    Max viscosity: 50000 cp
    Max temperature: 110 C
    Max pressure: 6 bar
    pH range:3-9
    Shaft diameter: 48 mm
    Max rotation speed: 160 rpm
    Reactor content: water, emulsifiers, monomers such as: acrylic esters, styrene, vinyl acetate, oxidizer initiators and etc.
    Category: Mixing

    How much horsepower is required to mix this specific material?
    I am designing a jacketed mixer that will mix coconut oil + 60% water. The operating speed is 10 rpm, and the operating temperature is 70 degrees C. The mixer has these specifications:
    
    • material SS304
    • inner vessel 1,250 mm X 1,295 mm
    • gross capacity 1,650 liter
    • blades: anchor & marine
    • shaft rod 63 mm diameter
    • housing shaft 70 mm diameter
    
    Please tell me the correct hp required to mix the material. Per my thinking, 15 hp will be more than sufficient.
    Category: Mixing

    Are there limitations to the Zwietering correlation for suspending solids in liquids?
    I'm curious as to the limitations of the Zwietering correlation for suspending solids in liquids.
    
    I'm particularly interested in how well it applies to very large tanks, say 500,000 gallons, and how to determine a representative mean particle diameter in a substance where particle diameter can vary dramatically.
    
    Furthermore, how can I be sure of uniform suspension? If the Zwietering correlation is not a good fit for this application, can you recommend another method for determining the impeller speed and estimating the power requirement?
    Category: Mixing

    Can I simplify mixing calculations for a bottom-mounted impeller?
    Can I simplify mixing calculations for a bottom-mounted impeller on a Breddo Likwifier by using the equations for a six-blade turbine with disk?
    If so, what would I substitute for the gap between the bottom of the impeller and tank?
    Category: Mixing

    Calculating the Agitator Torque For Adhesive Production
    We are trying to calculate the agitator torque for adhesive production. What size electrical motor and gearbox is required to drive this agitator? How about with a hydraulic drive?
    
    Here are the specs:
    
    ID of reactor is 1,250 mm
    Height of reactor is 2,360 mm
    Rod diameter is 80 mm
    Agitator has two 45-degree pitched blades
    Length of blade is 530 mm
    Diameter of agitator with blade is 1,140 mm
    Material viscosity is 100,000 cp
    Require speed is variable from 30 to 100 rpm
    Density of material is 1250 kg/m³
    
    Category: Mixing

    How do we calculate unbalanced horizontal load, amplitude and mass movement?
    We have a mixing vessel (diameter 2,000 mm , height 2,200 mm, weight 4,000 kg). It is an anchor type mixer -- length 1,900 mm (tip blade 2no.,180D, diameter 11 in., 2nd step 800 mm - blade 2no.,180D, perpendicular to associate steps, diameter 9 in., 3rd step 1,600 mm - blade 2no.,180D, diameter 6 in.);140 rpm; 3no. baffle 120D spacing.
    
    We mix sulphuric acid (sp. gr. 1.80) = 5,000 kg, LAB (sp. gr.0.85) = 2,500 kg, water =1,000 kg.
    
    How do we calculate unbalanced horizontal load, amplitude of the vessel, and mass movement of inertia for proposed 4 lug support?
    Category: Mixing

    What is a suitable mixer design for liquid detergents?
    I have a mixer tank with these dimensions: width 1.55m, height 2.5m. I want to use this mixer for liquid detergent industries where viscosity is between 1000-3000 cps at ambient temperature. What is the most suitable design for motor power, shaft, and impeller?
    Category: Mixing

    Planning the Perfect Mixing Tank
    We are planning a mixing tank for making a uniform solution.
    It is heat transfer activity. The density is 1,200 kg/m³ and viscosity of 35,000 cps. It is a thick solution with no solid particles. The jacketed tank has an internal diameter of 1,800 mm and tank shell length is 2,000 mm. The bottom and top of the tank have torispherical dished ends. What is the right type of mixture, its geometry and motor?
    Category: Mixing

    What is the formula for laminar mixing?
    I wanted to know the formula for power for laminar mixing.
    
    I have read the “Handbook of Industrial Mixing” as you previously advised. But it doesn’t have a clear formula for laminer flow stirrer (power, shaft design, gearbox design, etc.)
    
    tank inner diameter = 36 inches
    impeller diameter = 15 inches
    impeller type = pitched blade (45 degree)
    Reynolds no. = 3
    specific gravity = 1.2
    cp;(viscosity coefficient)= 10000, nearly. (tomato suspension in boiling water)
    tank height = 84 inches
    RPM = 15
    Category: Mixing

    Why are identical product units drawing different electric current?
    We have two identical production units in our facility. In each production unit there is one agitator and two stage impellers - one impeller with parabolic blades and one impeller with flat blades. The vessel on which the agitator is mounted is a flash crystallizer. The agitator is used to maintain the solid in a suspended state. The flash vapor is removed from the top of the vessel. The dimensions of vessel in both units are identical.
    
    The problem is, since commissioning the motor in one of the units it is drawing more electric current than the motor in other unit. Why?
    
    Another question, what will be the effect of rotating an impeller with parabolic blades in the reverse direction?
    Category: Mixing

    What type of impeller ensures good dispersion?
    I have a 1-ton mixing tank with dimension of 1 m (dia) x 1.5m (H). The tank is used to mix two different kinds of liquids: Butter oil, viscosity of 50-80 Pa.s @ 45 degrees C; and emulsifier, viscosity of 800 mPa.s @ 20 degrees C. What type of impeller is good for mixing to have good dispersion, homogeneous and have some shearing force? How many hp for the motor is sufficient?
    Category: Mixing

    What is a suitable mixer for square tanks?
    We would like to install a mixer for a square effluent tank that is 15 meters x 15 meters x 5 meters water depth containing 3% settling solids. What is a suitable mixer that will keep the solids from settling at the bottom?
    Category: Mixing

    Finding the Hydraulic Load
    How do I find the hydraulic load to calculate the shaft deflection of a vessel agitator? A mixing agitator incorporates a six-blade turbine impeller (90 degree - flat) that spins at 650 rpm to mix 200L of a water-like fluid in a 260L fermenter. The tank has a 31" ID. What is the calculation used to determine the hydraulic load at this high rate of mixing? The impeller pulls a vortex to the bottom of the vessel, so it is not fully submerged in the fluid at all times. The next step would be to then calculate the shaft deflection that is experienced with this hydraulic load.
    Category: Mixing

    Can you predict the vortex depth?
    I am looking for an equation that will predict the vortex depth in an unbaffled tank with a centrally mounted mixer. Process is a solid liquid dispersion where powder must be drawn from top of the tank and incorporated into the mix.
    Category: Mixing

    Specifications for Agitating Hot Water
    I had to design a tank for agitating hot water with CB (stone-like material of size 5/8 inches and specific gravity of 1.51) of 10 MT. What are suitable gearbox, agitator dimension, motor capacity and tank specifications?
    Category: Mixing

    Understanding The Baffle Effect
    I have a reactor with:

    • Tank Diameter = 2.736 m
    • Volume = 24 cubic meters
    • 2 Baffles = D-Baffles for glass lined tanks;
    • The distance from reactor wall is 0.723 m
    • 1 rushton 6 flat bladed turbine with W/D = 0.2 and impeller D = 1.012 m
    • Fluid density = 835 Kg/cubic meter @220°C
    • Fluid viscosity = 18.1 cP @220°C
    • N = 120.7 rpm
    • With the equation P = Np * density *N^3*D^5
    • Np = 5.2 for standard rushton with turbulent conditions
    • P = 37.52 KW, considering our driver and gear reducer efficiency = 41.14 KW.
    We monitored the power consumption directly on the driver, and we obtained power consumption much lower than calculations (about 26 - 27 KW). I probably have to use a power correction factor because of D-Baffles, then the power should be lower. Can you suggest the correction factor for this kind of baffles?
    Category: Mixing

    Determining the Agitator Shaft Loading and Power
    I am working on the design for a fluid bed reactor. The design includes an agitator that will move the aggregate in the bed. Do you know of equations that I can use to determine the agitator shaft loading and the power required for the agitation?
    Category: Mixing

    Calculating The Bending Moment on a Mixer Shaft
    We have one agitator with the following configuration: A single shaft with two mounted impellers -- one flat-blade impeller (inclined at 45 degrees to shaft) and 06 blades are present in an impeller assembly, and one gas-foil impeller (Parabolic contour), 06 blades are present in an impeller assembly. The power consumption is split in 70:30 with 70% for gas-foil blade. The agitator works in a gassed condition -- air bubbles are dispersed in liquid/solid stream, and for decontamination, the same agitator is run in 5% caustic solution. The question -- How do I calculate the force, which can cause a bending moment in the shaft, at gas-foil impeller and flat-blade impeller? And how can the resulting bending moment be calculated?
    Category: Mixing

    Merging Two Gas Streams
    If a cold gas stream merges in a hot gas stream, how do you calculate the distance where their temperature becomes uniform?
    Category: Mixing

    Calculating the Power Requirement for Mixing
    I'm trying to calculate the power requirement for mixing. The company makes tanks of all sizes and has to be able to mix many different liquids. They gave me equations for the Reynolds Number, Froude Number and the Power Number and one more equation that relates them. However, I'm not sure how this translates to a power requirement. Is there an equation I can use to find the power requirement for mixing?
    Category: Mixing

    Mixing Time and Residence Time
    I'm going to calculate residence time in a static mixer, but I don't know what the exact difference is between mixing time and residence time. Are the baffles shape and their numbers and the Re number of the mixed fluid the only parameters that affect the residence time? What about the entrance distance of the mixer? Is that up to me, or it has a specified amount? If the mixed flow regime is laminar at the beginning, it must be Turbulent after passing the inserts? Should I consider this change of Re number through mixer for my calculation? About the mixer specification, I am going to use a helical static mixer for just mixing two different fluids (there is no suspension or bubble in the mixed flow.)
    Category: Mixing

    Finding The Right Agitator Design for PVC Production
    We have a 20 m3 reactor for PVC production and H/D ratio of 6.0m/2.26m. The agitator consists of a 40kw motor, stirrer of 3 layer, 2 blades impeller of 1200mm x 200mm, and a paddle type at 120 rpm plus a single-blade baffle. The issue we are facing is a quality problem with the resins produced. Despite many trials in recipe changes, as it is lower in porosity and bulk density and consists of many odd shaped particles instead of round particles, some looked like tadpoles. Do you think we have the right agitator design and what can be done to improve it?
    Category: Mixing

    Mixing thixotropic fluid
    I need to mix a 4000 cp thixotropic fluid on a 10-in. diameter by 15-in. 5-gallon container. I am planning to use two 6.5-in. plastic propellers placed on a 14.5-in. shaft. The mixing will be at 180 rpm. I need to know the torque required for this.
    Category: Mixing

    What are the power numbers for standard agitator impellers?
    I wish to know different power numbers for standard agitator impellers (Pitched blade. Straight blade. Anchor. Disperser etc.)
    Category: Mixing

    Calculating the Effect of Baffles on Power Calculations
    Agitator power calculation formula does not include Baffle's size or width, but it definately affects. How to calculate the effect of Baffles on Power Calculations?
    Category: Mixing

    Achieve good top to bottom slurry suspension
    A general question regarding suspension of fine ore slurries, of the following properties: solids spg=2.9, mean dp=60 microns; liquid is 50wt% sulfuric acid at 100oC. slurry is 45wt% solids. Vessel is 90% full The vessel is brick lined, approx 16ft diam x 17ft T-T. Bottom head is ASME F&D, OD=204 inches,1/2" thick. There are 3 baffles made into "V" shape using bricks fastened to the vessel walls (ie, no spacing between baffle and vessel wall) The agitator is 40 HP, and there are 2 hydrofoil type impellers, approx 68 inch diam. I believe that they are A310'S. The impellers are spaced approx 68" apart. I do not know the distance from the bottom to the lower impeller, but I suspect it is about 35 -40". In your expert opinion, is this system adequate to achieve good top to bottom slurry suspension? The desired objective is to achieve as close as possible a uniform suspension within the vessel. Please give me your assessment and recommendations on how to improve this system?
    Category: Mixing

    Shaft and gearbox size
    What should be the required power for agitating a syrup with a density of 1500kg/m3, volume is 15m3, minimum rpm is 350, impeller diameter is 600mm. What should be the size of the shaft and gearbox?
    Category: Mixing

    Making an agitator for a composting unit
    I am interested in making an agitator for a composting unit. The diameter of the compost tub is about 2000 millimeters, while the diameter of the agitator will be about 1500 millimeters. The vertical shaft will be approximately 500 millimeters long, and I want the unit to run at 15 RPM. I need to find out the motor capacity, the shaft diameter and the expected torque for this operation.
    Category: Mixing

    Redesigning the impeller blade for a batch polyurethane tank
    I need to redesign the impeller blade of my batch polyurethane tank. I'm currently using a marine-type impeller, which incorporates a lot of air into the polymer polyol while mixing, causing a lot of bubbles. I need an impeller that mixes well but does not cause turbulence or a lot of bubbles. Please suggest the best option. Polyol has a viscosity of around 420-520 cSt. I'm mixing approximately 50 to 130 kilograms per batch.
    Category: Mixing

    Reducing dissolving time
    We are using a mixing system including v=40000lit,d=1m rpm=56 visc=120-800cst mixer type=pitched turbine kw=2.4. We want to reduce dissolving time by upgrading mixer diameter or rpm. Which one is the best selection for this viscous liquid? What about the other required changes followed selected upgrading? What about the amount of increasing diameter or rpm?
    Category: Mixing

    Power estimation for turbulent and laminar mixing
    Is there a simple rule of thumb for power estimation in either turbulent or laminar mixing?
    Category: Mixing

    Proposing a suitable tank volume for a specific viscosity
    We have experienced when the mixture viscosity increase the proper mixing tank volume would be reduced why is that for theoretically? And how we can propose the suitable tank volume for a specific viscosity by the way how we can specify the required rpm for a specified impeller diameter against viscosity of mixture?
    Category: Mixing

    HP Motor Size Requirements
    If I currently have a mixer that has a one hp motor inputting 3300 rpm to a gear reducer to obtain 800 RPM output, then if I was to remove the motor and reducer to put a VFD driven 1750 motor direct drive to my mixer what size HP motor would be required. If you know please can you also provide the formula.
    Category: Mixing

    Designing a Support Bracket for a Baffle
    I have a vertical 3100mm dia nad 7000 overall length agitator. The baffle supports were failing due to improper loading. I do not have any book so that I can use the formulae for redesign the support. Please provide me a sample calculation for designing support bracket for the baffle.
    Category: Mixing

    Pilot plant digester mixing
    I would like to continually mix 4% DS anearobic sludge in a 1cu.m pilot plant digester(h/d aspect ratio 1.3/1), using an external pump system with 2 nozzle injections. Sludge throughput is 3l/hour. @ 37degC. Max. solids size = 10mm. What would be minimum injection velocity and flow rate required? Any other requirements i.e nozzle angles, nozzle, injection height, baffles, etc.?
    Category: Mixing

    Vessel | Fixing a Vessel Agitator | Chemical Processing
    I want to fix an agitator to a vessel for mixing viscous chemicals. The viscosity of the fluid range from 600 cPs-800cPs. vessel. The capacity is 3000 gallons. I want to keep the agitator rpm at 60. What should the HP of the motor and gear box be?
    Category: Mixing

    Input power of electromotor, power of gearbox and the safety factor
    We are going to produce water base resins. These resins have an average viscosity of 60000 cp in a 6-ton industrial reactor, and an anchor mixer has been used for mixing the content of reactor (with the speed of 20-60 rpm). Therefore, we have made the impeller with proper dimensions (shown below). Now we must fix an electromotor and gearbox to the shaft and impeller system. What is your recommend about input power of electromotor, power of gearbox and the safety factor (the agitation system works continuously about 7 hours /day). My calculations show, M2(out put torque) is about 3000N.m and P(motor)= 20 KW and P(gearbox)=20*1.5=30KW, f=1.5 Characteristics of our anchor Impeller with two horizontal arm: D=1.75m, w (blade wide) =0.2 m, H=2m, t (thickness of blades)=0.02m blades are in 45 degree.
    Category: Mixing

    Efficient Impeller Blade or Mixer
    We make a solution of water & benzoyl peroxide (in various percentages - 1%, 4%, 8%, etc...) in a mix tank & transfer it into several poly lined 55 gallon drums to store the solution until we are ready to fill from each drum - one at a time - until empty - into finished product containers. We have to stir each drum for approx. 2 hrs prior to beginning filling to get a homogenous solution in the drum - to get the BP back in suspension. Do you have any suggestions as to a more efficient, specific type of impeller blade or mixer to keep the BP in suspension - so we can keep the drum of solution as homogenous as possible in each drum? We currently have air mixers with a stirrer type 3 blades at the bottom of the shaft. Drum dimensions: int.hgt.= 37 1/16", int.diam. = 21.8 with 2 " Bung/opening with removable lid. Must be kept covered.
    Category: Mixing

    Designing a Mixing Tank
    I want to design a mixing tank to prepare a slurry of very fine catalysts in water. This tank will have an agitator to keep solids suspended. In this case how would you consider the vortex height generated during mixing?
    Category: Mixing

    Jet Mixers vs. Mechanical Mixers
    I would like to know the differences between jet mixers and mechanical mixers. Are there any situation that I have to use jet mixers instead mechanical ones?
    Category: Mixing

    KW Rating | KW Rating and Bearing Size | Chemical Processing
    We need to offer a drive ( GearMotor) for a Mixer with Blade sweep Dia. of 6.56 Ft., Height of Stirrer shaft is 8.202 Ft., rpm - 60, Viscosity - 30 poise, but there is no bearing at the bottom. The question is what would be the KW rating of the Motor and what size of Bearing should be there at the Gearbox output shaft ?
    Category: Mixing

    Mixing Time and Multipropeller
    I would like to know if there is a correlation to estimate mixing time in a vessel with a multipropeller?
    Category: Mixing

    Horsepower calculations for a specific viscosity
    I need to calculate the horsepower required to agitate a solution with viscosity of 0.3 cps and density of 839 kg/m3 at 60 rpm. The tank has an inner diameter of 1,500 mm and tangent-to-tangent length of 4,500 mm. The agitator has three impellers (pitched turbine, I do not know the number of blades) with 900-mm diameter. The tank has four mixing baffles. Using equations from a handbook, I found that the power required is about 1 hp. However, I am not sure if this equation considers the use of multiple impellers.
    Category: Mixing

    Baffle fabrication
    I am presently setting up a micro manufacturing plant for mixing Polymers and other cleaning products. I have two tanks, one that is eight feet,a stainless steel tank and one four-foot poly tank. My question is regarding baffles. Can I fabricate something locally that would work for both steel and poly tanks and is there any tricks to installing these baffles?
    Category: Mixing

    Calculate "downward force" on an impeller
    I am trying to calculate the "downward force" of an impeller. Is this the same a hydraulic force? (e.g. (19,000 x horsepower x service factor)/(rpm x impeller diameter).
    Category: Mixing

    Blended viscosity and stirred tank content relation
    I feel there would be a relation between the blended viscosity of any stirred tank content and the tank volume physically, is that correct? If so, why and what is the rule of thumb criteria for selecting a vessel’s volume with respect to blended viscosity?
    Category: Mixing

    Agitator design procedures
    I want to know the selection criteria and standard design procedure for all types of agitators, mainly anchor and turbine). Please also suggest some books.
    Category: Mixing

    Sizing mixers
    How do you select the type of impeller for different applications? How do you determine the measurement of the impeller size and dimension?
    Category: Mixing

    Suitable reactor capacity
    We have installed a cylindrical dish-end type of SS reactor with a capacity of 1,500 L, diameter of 1,200 mm; height of 1,350 mm; depth of 50 mm; total height of 1,650 mm; and the required rpm at the agitator end is 500-600 rpm. Process details are: paste type liquid (free flowing); specific gravity around 1.0; viscosity of liquid is 350-600 cSt.; agitator is vertical with four, 45-degree vertical turbine-type impellers. Suggest the suitable capacity of torque with its rpm selection to have the desired rpm at the end of the impeller withstanding the torque generated by the liquid during the mixing. Can we operate the same system with gear motor?
    Category: Mixing

    Agitator capable of dispersing air through the shaft/blades
    I am looking for an agitator that can disperse compressed air through the agitator shaft/blades. Is there a manufacturer out there that makes an agitator like that?
    Category: Mixing

    Motor requirements for varying fluid viscosity
    I have an agitator with a 40-hp motor. The service fluid viscosity is 1,000 cp. I want to use the same shaft and motor for a 10,000-cp fluid. Can I use same shaft, and if so, what parameters need to be changed?
    Category: Mixing

    Power requirement for a constant stirring vessel
    What is the power requirement (motor specification, gearbox size and the shaft size) for a constant stirring vessel that is an open type with a 60-degree inclined pitched blade agitator running at 14-15 rpm? The contents of the vessel can be UF (Urea Formaldehyde resin), Melamin formaldehyde resin, MUF, phenol formaldehyde resin, etc. The diameter of the tank is 3,500 mm and the height is 5,500 mm. The stirring is required to not let the liquid gel-up.
    Category: Mixing

    Power requirement for a gearbox
    I have a 1,000-mm diameter and 1,800-mm high tank. Material to be mixed with an agitator is 76% solid and 24% water (calcium carbonate slurries), with a viscosity of 350-450 cps. I want to use a gearbox for mixing with output speed between 18-36 rpm. How much power (kW) do I need for the gearbox? How many blades must be made in order to make slurries?
    Category: Mixing

    Agitator type for batch reactor
    I would like to know what kind of agitator in a batch reactor I should use. Reactor dimensions are 1160 mm in height and 800 mm in diameter. Reactor contents are 250 Kg of 853 Kg/cubic meter dense liquid and the gas is purged to the liquid through dip tube at 75Kg/hr. What kind of agitator should we introduce to this batch reactor?
    Category: Mixing

    Power consumption equation
    I would like to know the formula for calculating power consumption for an agitator and grinding mill. I have all the process data information for this equipment, but I don’t know how to calculate approximate power from the data.
    Category: Mixing

    Follow-up to previously answered impeller diameter question
    A few days ago, I posed this question: Q: I have a vessel with a top entering agitator without baffles. The vessel height is 2 m and vessel inside diameter is 1.5 m. The impeller type is three 60-degree pitched blades. Each blade has an inclination of 60-degress in respect to the agitator shaft too. The impeller diameter is 880 mm. The pitched blades are fixed to a cylinder that is 122 mm in height and with a 125 mm diameter. The width of the blade at the cylinder is 112 mm and at the end is 80 mm. The shaft diameter is 100 mm. The agitator has a velocity redactor of 1 to 10. The agitator has no driver and has no characteristics label. I want to use this vessel in the production of 50% calcium nitrate solution with a density of 1,450 Kg/cubic meters and a dynamic viscosity of 1.35-1.8 cp. What will be the calculated power at 180 rpm and 360 rpm?
    
    I received this answer: A: The answer is don’t do it. There is no way an impeller that large should ever be rotated at 180 rpm in a vessel that size. Without baffles, the liquid contents would swirl over the top to the tank an splash everywhere around the tank. At 180 rpm, without baffles, the impeller power draw would be about 7.8 kW, that's kilowatts, not watts. At 360 rpm, the power jumps to 61 kW. The mixer described is suitable for a much larger tank, not for one 2 m tall and 1.5 m in diameter, regardless of the contents. Baffles only make the design >worse, because the power levels are about three times the levels without baffles. Do not attempt to operate the mixer in the manner described!
    
    Of course, I am satisfied with the answer, but now I have a new idea. Can I do the blades of my impeller shorter, keeping up the original design, except the diameter? If I can do it, what would be the optimum impeller diameter to avoid having the liquid contents swirl over the top of the tank and splash? What would be the consumed power in this case? I attempted to calculate it, using the Perry’s Manual, but there wasn’t any similar impeller in the figure.
    Category: Mixing

    Agitator speeds for different fluids
    Can I get the same maximum agitator speed for a given motor for different types of fluid?
    Category: Mixing

    Calculating rpm power
    I have a vessel with a top entering agitator without baffles. The vessel height is 2 m and vessel inside diameter is 1.5 m. The impeller type is three 60-degree pitched blades. Each blade has an inclination of 60-degress in respect to the agitator shaft too. The impeller diameter is 880 mm. The pitched blades are fixed to a cylinder that is 122 mm in height and with a 125 mm diameter. The width of the blade at the cylinder is 112 mm and at the end is 80 mm. The shaft diameter is 100 mm. The agitator has a velocity redactor of 1 to 10. The agitator has not driver and has not characteristics label. I want to use this vessel in the production of 50% calcium nitrate solution with a density of 1450 Kg/cubic meter and a dynamic viscosity of 1.35-1.8 cp. What will be the calculated power at 180 rpm and 360 rpm?
    Category: Mixing

    Agitator design
    How do you design the shaft diameter, impeller rpm and power required to drive an agitator?
    Category: Mixing

    Agitator efficiency equation
    I am looking for a formula to calculate the efficiency of an agitator. I am currently designing a mixing impeller for the dissolution of ammonium persulphat in denim water. Now I want to compare between the efficiencies of the propeller and the turbine impeller designs with respect to their efficiencies. Can you help with the formula? The shaft is a top, off-center entering at an angle in a closed hemispherical tank.
    Category: Mixing

    Pitched-blade impeller direction
    I would like to know the direction of 60-degree angle pitch-blade impeller and whether it should be facing upward or downward while the agitation is in clock-wise direction. I also am seeking information on how much distance is required from the bottom dish of the reactor to the bottom impeller. As far as I know, if the pitch-blade impeller's angle is facing upward during its clock-wise rotation, the material lifts from bottom to top and gets radial and axial agitation to lift the reaction mixture. If the pitch-blade impeller's angle is facing downward during its clock-wise rotation, the material pushes down and may be not getting proper mixing effect. In either case what should it be?
    Category: Mixing

    Agitator design
    I have a tank of 4.5m diameter and 2m height containing water. I want to install an agitator consist of two blades of sweep diameter 2 m. The agitator's speed should be 20 rpm. Gear ratio is 60:1. Motor is of 3.7 kW. Please tell me how I should design this agitator? Also tell me the specification of the gear box and motor.
    Category: Mixing

    Suspension agitation
    In several parts of our process we are making suspensions of solids in mixing tanks with agitators. Some solids tend to float on the surface. Some suspensions also tend to create a lot of foam on top of the water surface causing problems (flooding). A higher rotation speed creates a better mixing but creates also more foam. We use antifoam chemicals to reduce the foam. Is there a way to prevent or reduce foam? By using another agitator or agitator position or another trick?
    Category: Mixing

    Design for an off-centered agitator shaft
    I am trying to design an off-centered agitator shaft. The shaft would be offset 20% of the tank’s inner diameter. What service factor would I need to use for the off-center?
    Category: Mixing

    Hydraulic load factor for water, oil mix
    What is the hydraulic load factor for a fluid made up of oils and water being stirred by a three-blade propeller with the blade fully submerged under the mixer? Can you also help with the diameter of the shaft? Details are: power equals 2.2 kw; length of shaft equals 2.228s; speed equals 460 rpm; and impeller diameter is 390 mm.
    Category: Mixing

    Liquid mixing equation
    I know there is an equation that can be used to determine the adequate mixing time of two liquids (viscosity of water). Can you give me the name of the equation? I saw it once a long time ago and, if I remember correctly, it was a person's name.
    Category: Mixing

    Agitator force
    I have an agitator which is used to mix the dough. The agitator is running at 150 hp motor at 84 rpm. Taking 1005 efficiency, how do I calculate how much force will the dough exert on a fixed cold bar? The idea is that the dough gets squeezed between the agitator and the fixed cold bar.
    Category: Mixing

    Hydraulic load calculations
    An agitator has a steady bearing (a PTFE bush bearing), a radial bearing (rolling element bearing) and a locating bearing (rolling element bearing - in the gear box). How do you calculate the reaction loads at each of these bearings due to hydraulic load and other loads. Do you have any examples for this type of problem?
    Category: Mixing

    Mix throttled liquid/flash gas and hot gas
    What is a good way to mix throttled liquid/flash gas and hot gas in the low side of a refrigeration system to achieve a uniform superheated vapor? Both the feed streams are currently injected at a common point and then allowed to run through about 20 ft of tubing with four 180-degree return bends. There is a liquid stream rolling along the bottom of the pipe where incomplete evaporation is evident. There is insufficient room to add much additional piping. Would static mixers, which I believe are typically used for liquid blending, be of any benefit?
    Category: Mixing

    Calculating torque exerted by liquid
    We have a vessel of 6,500-L capacity. It needs to be driven by a top agitator with 2 Nos. of turbine impeller with four 300-diameter blades. I want to know the torque exerted by the liquid. The viscocity of the liquid is 250 cp.
    Category: Mixing

    Service factor for an unbalanced hydraulic load
    The following is the data for an application:

    • Fluid composition: Hydrocarbon/Acid/Water/0.5% suspended solid
    • Solid concentration %w/w: 0.5
    • Motor: 24.79 hp
    • Speed: 68 rpm
    • Single impeller downflow turbine type, with a steady bearing about 800 mm above the impeller.

      Can you please give the service factor that needs to be used while computing the hydraulic unbalanced load?

      
      Category: Mixing

      Calculating unbalanced hydraulic force
      When calculating the unbalanced hydraulic force on an agitator impeller, one of the articles says that the calculation of force can be done by the formula: Force = (2000*Output hp*12*Position factor)/(rpm*DIa. of turbine in inches). What does that position factor stand for, and what are the values for a top entry type agitator, with a 11kW motor? In another text it was written that the force can be computed by the formula F = Torque/(0.75*Radius of blade in mm). Which of the two gives an accurate result?
      Category: Mixing

      Suspending salt mixtures in a PVC solution
      I am interested in keeping a mixture of 30% salt suspended in a liquid PVC material. The goal is to produce products that are heavy and weigh the same without any salt collecting on the bottom.
      Category: Mixing

      Installing an agitator in a reactor | Chemical Processing
      We represent a company that sells second - hand equipment, our customer needs a practical way to mix a viscous product and the agitator is a 36 hp - 120 RPM, but the structure to handle this agitator in a 1200 gal SS reactor is very complicated according to our main engineer in USA. We do not have more in the inventory, what could be the mechanical structure suitable to install the agitator in the reactor?
      Category: Mixing

      Recommendation for small pilot plant batch mixer
      I'm looking for a recommendation for small pilot plant batch mixer (idal capacity target 1 to 4 liters) that handles powder and can be heated to about 80 C. Mixing should be possible at low speed.
      Category: Mixing

      Formula for position of impeller
      We have a pilot mixing plant here on site. Ever since it was stripped down and rebuilt due to its PM schedule, it hasn't worked properly. We use the tank to mix a powder and a liquid. Now when it runs, no vortex is created (or be it a very poor one) and the powder does not go into solution, it just sits on the top of the liquid. We have tried moving the impeller up and down the shaft but to no avail. Unfortunately, the original dimension drawing are missing and so we do not know the original position of the impeller and its dimensions etc. Are there formula that might help us to determine the optimum position for the impeller etc. if we measure the various aspects of the tank, baffles etc.?
      Category: Mixing

      Solid particle size distribution
      Can give me the various general solid particle size distribution used in chemical industries in various applications or a link or reference where i can get this data?
      Category: Mixing

      Blade RPM speed
      I have a tank (7-meter diameter 8.5-meter told), with and old agitator for milk of lime suspension and a double blade 84 inches wide each. At what RPM do I have to turn the blades in order to keep the lime in suspension at 8 or 10% of solid?
      Category: Mixing

      Mixing powders of similar micron sizes
      I would like to know what are the factors to consider when mixing two types of powder with similar micron sizes. What would be the most cost effective way to mix big volume quantity in the rangeof 500 000 to 1 million lbs a year? This mix will have to be filled in individual products, and I would like to know if there is a group out there that can guide us in the design and implementation of a production system.
      Category: Mixing