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Solid dosing
Q: Please suggest a system that can dose a variety of solids (powdery, free-flowing types) into a batch reactor for a batch process to cater to the accurate weighing of a variety of solids into a resin reactor using automatic systems.
A: This is a complex question without more details provided about the solids. Some solids may not be dosed to a batch reactor using automatic systems very easily. The reference to resins may indicate you are trying to put in cohesive solids and maybe solids of a wide size distribution. Also, you may have a formula that requires very small amounts of some of the different ingredients. These usually need to be added by hand or by using a pre-weighed container.
Most loss-in-weight feeders will work well for free-flowing solids and even on some less cohesive solids. If you have more than three components, it can be very costly. These can be incorporated into most automated control systems. If you have cohesive solids, the reactor can be placed on weight cells (in some cases) or an intermediate hopper can be used, which would be on weigh cells. In this case, only a volumetric feeder would be required. However, the solids flow properties need to be determined to insure proper design of the feeder and hopper. They need to be based on shear cell tests and the hopper needs to empty completely.
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How to Avoid a Break in the Main Shaft Screw
We have a twin screw conveyor for transferring Na2SO4 as per spec data below. To avoid a break in the main shaft screw, I would like to install a torque limiter for safety device. What is your opinion and is there a best way to do this? Is there any torque limiter product that accommodates our screw design?
See the data below:
Product to be handled: Sodium sulphate (salt)
Chemical formula: Na2SO4
Density at 20 degree C: 2700 kg/M3
Bulk density: 1500 kg/M3
Shape of particles: Rhombic
Sieve analysis:
- above 0.1 mm: 70% by weight
- 0.06 – 0.1 mm: 15% by weight
- below than 0.06 mm: 15% by weight
Average particle size: 0.18 mm
Specific particle surface area: 68 M2/kg
Total throughput: 6000 kg/hrs dry salt, 6250 kg/hrs wet salt
Temperature: 40 degree C
Residual moisture: 3% - 4% by weight
Material of construction:
- all wetted parts: SS 316L
- all non wetted parts: SS 316L
Speed of screw conveyor: Fixed 36 rpm
Electrical data: 380/680 V, 50 Hz, IEC standard, IP 53, non explosion proof, F insulation class
Spec for geared motor: SEW EURO drive R107DV132M4, 7.5 KW, 36 rpm
Can you recommend formulas for calculating power consumption?
Can you recommend a formula or a reference to calculate power consumption for a screw conveyor and a pulverizer?
Decreasing Filtration Time
Our plant is currently investigating methods to decrease filtration time for one of our products. The process involves a neutralization reaction in which Calcium Salt of Dodecylbebzene Sulfonic Acid is formed. Sulfuric acid also exists in the raw materials, which leads to a secondary reaction that yields calcium sulfate. It is the calcium sulfate that is removed during filtration. Currently, a filter press is employed for the removal of the CaSO4. We are hoping to employ some type of agglomeration technique to improve the filtration rate.
