Commercial
Gasifier
Fuel
Environmental
Commercial
Can I buy the gasifier?
Certain client situations could offer a purchase option but the standard EPIC business model is to build, own, and operate the gasification system to provide syngas to customers.
How long of a contract must I sign?
The typical term is fifteen years. Other terms are negotiable.
What is the plan availability ?
Typical plan availability is in excess of 92%.
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Gasifier
What is the temperature in the gasifier?
The temperature at the top gas outlet is approximately 2800F. The temperature at the lower gas exit is around 12000F. The temperature in the gasifier is approximately 21000F. The temperature in the gasification zone is controlled to stay below the ash fusion temerature of the coal.
Does your gasifier require an air separation plant ?
No! And that is one of the major advantages to the EPIC system.
What happens to all of the tars you produce?
Tars are separated from the fuel gas and recycled to the gasification zone of the gasifier.
What is the BTU content of your gas?
The BTU content depends upon the composition and reactivity of the coal feed stock. It typically varies between 170 BYS/scf and 200 BTU/scf.
What is the pressure of the gas at the outlet of the sulfur removal system?
This depends on the operating pressure of the gasifier and the level of clean up of the fuel gas. Typically, the pressure would be between 5 to 10 PSIG.
How much does a gasifier produce?
This depends on the size and operating pressure of the gasifier and on the properties of the feed coal. In general, a 2ST-3.0 meter gasifier will produce approximately 70 million BTU/hr and a 2ST-3.6 meter gasifier will produce 100 million BTU/hr or more.
What is the pressure of the gasifier?
The gasifier operates at 12-14 PSIG.
How often do you have to do maintenance?
Maintenance is required annually or longer.
How long will the refractory last?
The refractory has been proven to last over ten years in continuous operation.
Do I have to provide makeup steam?
Start-up steam is needed. At stable operation the system is self-sufficient for steam. In certain circumstances, excess low pressure steam is produced and available for integration into customer processes.
Can I burn the gas in a turbine?
Yes, but not in all turbines. Typically, industrial frame machines can be modified (relatively minor modifications) to accomodate 100% coal gas. Aero-derivative turbines can normally use a blend of coal gas and natural gas, depending upon specific manufacturers' specifications. This could allow some significant cost reductions as the typical blend would be at least 50% coal gas.
Can I burn the gas in a boiler? Will I have to take a derate on the boiler?
The fuel gas can be burned in virtually any application that uses natural gas. The lower heating value of the fuel gas may require burner modifications to handle the increased volume, but derating is not necessarily a result. The total flue gas flow from the boiler is typically equal to or less than that when firing natural gas.
What is the efficiency of the gasifier?
The gasification process typically returns coal gas heating value of at least 80% of the heat value of the feed. That is, the BTU content of the fuel gas will be at least 80% of the BTU value of the feedstock.
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Fuel
Can you use pet coke?
Yes, when mixed with coal, the exact composition would have to be checked.
What kinds of coal work well in your process?
The preferred types of coal are more reactive coals such as sub-bituminous or lignite. Some bituminous coals will also work. The preferred coal should have a free swelling index of 4.0 or less, be between 1/8" and 2" in size, and less that 18% ash. Higher ash content is possible, depending on the other coal properties. The initial softening temperature in an oxidizing atmosphere should be 22000F or higher.
Can you burn wood waste and MSW ?
Yes, when mixed with coal, the exact composition would have to be verified. In general wood waste is an excellent material to add, especially to less reactive coals.
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Environmental
What are the emissions from your system?
Air emissions are limited to dust emissions from the coal handling and feeding system. All miscellaneous fumes from process tanks are collected and recycled for destruction in the gasifier.
What is the ash like? What is the chemical makeup of the ash?
The ash is dry and free flowing and similar to a mixture of bottom ash and fly ash from a typical boiler. The actual composition depends on the chemical composition of the ash in the coal.
Where can I dispose of the ash? Is it hazardous?
The ash can be disposed of in several ways. The ash is similar in characteristics to conventional pulverized coal plants except it is more like sand than fine fly-ash or coarse bottom ash. Depending on the coal that is used, the ash may be used as cement aggregate, road-bed material or disposed in non-hazardous landfills. If the gasification facility is close enough and local permits allow, the ash may be returned to the mine for reclamation purposes.
Where can I dispose of the sulfur? Is it hazardous?
The sulfur may be sold to companies that process sulfur into agricultural grade sulfur. This is somewhat area dependant. Other areas have sulfur burning systems installed on power plants for enhancing particulate collection systems. If the sulfur is not sold for these purposes, it can normally go to a non-hazardous landfill.
What is the makeup of sulfur that is produced by the 888 system?
The sulfur purity is 90+% with some water content, depending upon how the recovery process is designed .
What's in the blow down water?
Residual amounts of sulfur and sulfur removal catalyst (non-hazardous) and small amounts of ammonia and phenol. All blow down water is either used to produce steam for the gasifiers or is educted into the steam fed to the gasifiers. There is usually little or no liquid discharge from the plant.
How much sulfur is removed from the gas?
The standard design removes sulfur to a residual value of under 10 ppm as H 2 S. Additional polishing to lower residuals is available.
Is the sulfur in a wet or dry form?
It can be either form.
How do you handle mercury?
In the presence of H2S mercury forms as mercuric sulphide, which may precipitate in water and/or be absorbed in commercially available activated carbon beds.
Do you ever flare the gas?
Fuel gas is flared for brief periods during start-up and emergency shut downs.
If the gas is used in a gas turbine, boiler, kiln or furnace, how will the NOx emission compare to natural gas?
A study by industry recognized consultants indicates that EPIC coal gas NOx formation compared to natural gas would result in NOx reduction of 50% ± for gas turbines and 70% ± for boilers, kilns and process furnaces.
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