|
PRB COAL AND CYCLONE BOILERS
Most of the cyclone fired boilers have switched from their design fuel to PRB coal. This has been done to reduce SO2 emissions, lower NOx levels and reduce fuel costs. These boilers were designed for high sulfur Midwestern bituminous coal and using PRB in them is not without some issues.
COMMON PROBLEMS
- Slag layer in cyclone barrel is too thin for good combustion
- “Eyebrows” of slag build up in cyclone
- Slag freezes in the “monkey hole” and won’t tap easily
- More coal burns in suspension and increases flyash loading
- Incomplete combustion raises LOI in flyash
- Less bottom ash produced
- Must blend in bituminous “kicker” coal to unclog slag tap
- Only one or two PRB coals are “acceptable” fuels
- Unit cannot operate at lower load levels without slag tap freeze-up
CAUSE OF THESE PROBLEMS
PRB coals have a much steeper temperature vs viscosity curve than bituminous coals. This means that the temperature range for the slag to stay at the proper viscosity is much smaller than with the design fuel. Small changes in temperature can cause the slag to be too thin or too thick.
REFINED COAL TAX CREDIT
The American Jobs Creation Act of 2004, Section 45 contains provisions to incentivize the production of Refined Coal that will reduce emissions of several pollutants to qualify for a tax credit of $6.00/ton. ADA-ES CyClean has been tested full scale at three power plants and shown that it can reduce NOx and mercury emissions to qualify for this tax credit.
ADA-ES and NexGen Resources have created a joint venture to produce and qualify
CyClean for the Section 45 Tax Credit. We will work with your plant to test CyClean and build a qualifying facility that will be simple and cost effective.
SOLUTION: CYCLEAN
ADA CyClean is a cost effective coal additive that is added to the coal just prior to the crusher, enabling it to be evenly distributed in the coal supply before combustion. CyClean comes in a granular form that is delivered by dump truck. (See picture) The product flows easily and can be added to a coal supply belt with a simple storage and conveying system. It will not harm coal crushers or coal conveying belts.
RESULTS OF CYCLEAN
Our coal additive will flatten out the temperature vs. viscosity curve of the PRB coal slag to allow it to behave more like the bituminous coal the cyclone boiler was designed for. This will increase the temperature range of the optimum viscosity of the slag and improve the combustion of the fuel in the cyclone boiler.
BENEFITS OF CYCLEAN
- Creates proper slag layer thickness in cyclone barrel for good combustion
- More coal is burned in the slag layer, less coal burns in suspension
- Eliminates “eyebrows” and slag deposits in cyclone
- Eliminates the need for “kicker” coals
- Can help lower LOI in flyash
- Increases amount of bottom ash produced
- Allows more PRB coals to be “acceptable” fuels, increasing fuel flexibility
- Allows unit to operate at lower loads without slag tap freeze-up
- Reduced NOx emissions
- Reduced mercury emissions
- Qualify for a Refined Coal tax credit
Better slag tapping, reduced frozen slag and increased fuel flexibility, all add up to improved operations for the cyclone unit and reduced costs for generation.
ADA will assist in the design and installation of the equipment needed to add Cyclean at your plant. We also provide operation guidance for the system and help optimize the amount of additive needed to get the best results
|
