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Combustion

Rakesh Gupta, supervising process engineer, URS Washington Division

Rakesh Gupta is a supervising process engineer for URS Washington Division. He has more than 25 years of experience with combustion and incineration technology. He has focused on this area both at engineering firms and equipment vendors, and has written a dozen papers on the topic.

What safety requirements are necessary for a fuel switchover on a furnace?
We have a natural draft furnace designed to use the fuels hydrogen, natural gas and LPG. In the event of a fuels changeover while the furnace is on-line, what are all the safety instruments and controls that should be considered to safeguard the equipment and operating personnel?
Category: Combustion

Is there a formula to calculate how much wood was present prior to burning?
Is there a formula for calculating remaining wood as residue to calculate how much wood was present prior to being burned? And if so, could the formula be used on remaining wood ash residue that has been exposed to the elements for seven months?
Category: Combustion

Are there any resources for designing batch furnaces?
My company is planning to construct a batch furnace that can endure the following two severe conditions: (50 barg, 500 degrees C) and (1 barg, 1200 degrees C). Processing rate is around 10-30 tons of hydrocarbon per batch (may use multiple furnaces). Do you have any recommended vendors? What kind of burners and chambers shall I use? What are the critical design parameters for such a furnace? Are there any references that you recommend me to take a look at?
Category: Combustion

What are the values and viscosities of vanadium, sodium and aluminum?
Regarding No. 5 fuel oil, what are the values and viscosities of vanadium, sodium and aluminum?
Category: Combustion

How do I improve combustion of lignite coal?
I need to reduce the un-burnt carbon in a lignite-fired thermal power plant. I need to reduce it by 20% via a chemical treatment.

What chemicals are suited for the above purpose? And what dosing?
Category: Combustion

Changing Fuel To A Lower Wobbe Index
I use a burner that has specs for natural gas Wobbe index 42. What will happen if I use natural gas that has Wobbe index below 42 (say 30)?
Category: Combustion

Maximum Inlet Velocity In Gas Flue Burners
What's the maximum inlet velocity in gas flue burners? Also, what is the effect of gas velocity in the burner’s performance?
Category: Combustion

What is the cause of high silica and aluminum?
The result of a residue analysis from the bottom of the furnace is: Na 2.61%; Mg 1.39%; Al 31.34%; Si 48.16%; Ca 9.17%; V 1.59%; Cr 0.32%; and Fe 5.42%. The residue is a form of glass contaminated with trace of metallic elements. We fire fuel oil No. 5 with high ash content. We need your comments and suggestions on the above and what is the cause of the high silica and aluminum.
Category: Combustion

Replacing natural gas by hydrogen
What must be considered to replace natural gas by hydrogen as combustible for burners in a cracking furnace?
Category: Combustion

Hydrogen vs. LNG
What are the advantages of using hydrogen as fuel over LNG for co-generation plants?
Category: Combustion

Convection bank performance
We have a 50 MMKcl/hr fuel oil-fired, natural draft, box-type furnace. It has a convection bank with a super-heater steam coil sandwiched in between process lines. It is also equipped with soot blowers and normally operates once every 24 hours. Suddenly, stack temperature went up and the furnace is firing is very hard. Please let me know how to confirm whether the convection bank is fouled up or not?
Category: Combustion

Fixed carbon in proximate analysis
What is the fixed carbon in proximate analysis? Is it used in calorific value calculation as %C? At what temperature fixed carbon completely burn?
Category: Combustion

Hydrogen halides reactions
I want to know in what ways the hydrogen halides forms in incineration if it contains halogen gases at high temperatures. I am confused about the reactions, i.e. H2 + x2 = 2HX or if there are no hydrogen gas and steam is available, then H2O + X2 = 2HX + 1/2O. Please comment on the above reactions.
Category: Combustion

Using glycerol as fuel
Of late, bio-diesel projects are coming up. While manufacturing, bio-diesel crude glycerol comes out as by-product. It contains some sodium sulfate. The bio-diesel project also requires steam. Will it be possible to use the by-product glycerol as fuel? If yes, who could be the likely supplier of such burner?
Category: Combustion

Dioxine information
What is the dioxine? How is it formed? How do you avoid it?
Category: Combustion

Identify wax buildup cause
I have a reformer furnace in the HMU unit. There are 56 burners in there. Every time during the statutory shutdown, the fouled burners need to be cleaned to remove wax. The source of the wax is from the fuel. If I do not take out the wax from the fuel gas, are there any other ways I could solve this, such as changing the burner tips, or installing a knockout drum for the wax? Additionally, can you help calculate the burner fouling coefficient? I want to monitor the burner fouling rate, and if there is no shutdown, when would we know when is the time to shutdown the reformer for the burner cleaning?
Category: Combustion

Slag formation in incinerator
I am working for a local oil refinery to find a solution to a problem they are having with their off-gas incinerator at the end of a rotary kiln calciner. When it is necessary to perform maintenance on the unit, it must cool down. Therefore, during the cooling process, the slag that has accumulated within the incinerator has nowhere to go, resulting in deformation of the incinerator structure. What is a suitable solution in this matter?
Category: Combustion

Brick lining variation
After starting an aq incinerator plant, we took a shut down. During the inspection we found a change in brick lining (230 to 125). In our system, we use aq waste and a small amount of solvent. The waste contains Cl, Na, Mg, P, S, CL, N, etc. Are there any effects on high alumina brick lining due to molten slag or chemical attack at 1,100ºC?
Category: Combustion

Waste incineration and refractories
My question is related with refractories use in waste incineration. In incineration, we use many type of waste at 1,100°C and cause a molten slag formation. What type of effect on refractories (alumina/silica) occurs under these conditions and is there any effect on the flue gas velocity on refractories erogen?
Category: Combustion

Caprolacton waste handling
I have been working with GSFC Ltd-India as a process engineer mainly looking after troubleshooting and modification/upgrade activities of a caprolacton plant. At one of our old plants, the unit burns process liquid fluid west — one mixed/purged hydrocarbons with high CV (approx. 7,500 Kcal/Kg) and the other mainly inorganic (soda) with low CV (approx. 1,200 Kcal/Kg). We are facing the perennial problem of inconsistent burning due to fluid properties resulting in the frequent choking of the burner gun. Moreover, the plant’s thermal design is highly inefficient. We intend to go for new plant with better design that can also handle solid waste generated in plant to deal with the environmental issues. Are there alternatives available to improve the performance in situation? Can you recommend design aspects to be considered and a competent supplier/designer for such a plant? The preliminary data of the fluids to be handled is 1) High CV fluid — 40 MT/day; 2) Low CV fluid — 400 MT/day; and 3) Solid waste 1 MT/week (CV unsteady or less than 200 Kcal/Kg).
Category: Combustion

Burner design references
Could you refer me to publications that cover the physical design of a burner suitable to burn sawdust as a flame?
Category: Combustion

Efficient combustion equipment options
Can you recommend combustion equipment options for a 1,000 scfm off gas stream from a WWTP dissolved nitrogen flotation (DNF) unit? This inermittent stream (as little as 30 minutes/day) is saturated with water vapor at approx 100°F and also includes up to 30 lb/min organics (approx 15% by volume), mostly BTXE (benzene, toluene, xylenes, and ethylbenzene) and MTBE (methyl tert-butyl ether). The required efficiency is greater than 95%. Note, the DNF unit is covered and operates under a nitrogen blanket.
Category: Combustion

Unusual slag formation
We recently ran into unusual slag buildup problems in a No. 6 fuel oil-fired utility boiler. The fuel oil contained 20-40 ppm of silica and alumina. Can you point me to references or information on the effect of Si and Al on slag formation? The dominant slag forming species are vanadium oxides and sulfur oxides (SO₂, SO₃)?
Category: Combustion