Coal gasification process

Clean energy technology

Red Mountain Energy recognizes that Coal Gasification is a flexible, reliable, and clean energy technology that can turn a variety of low-value feedstocks into high-value products, help reduce dependence on imported oil and natural gas, and can provide a clean alternative source of baseload electricity, fertilizers, fuels, and chemicals.

Coal Gasification was originally developed in the 1800s to produce town gas for lighting and cooking. The basic coal gasification process has been utilized for the production of synthetic chemicals and fuels since the 1920s.

Feedstock

Gasifiers can be designed to use one or more of these feedstocks: coal, petroleum coke and biomass.

Air separation units (ASUs) and Cryogenic technology

Most gasification systems use almost pure oxygen (as opposed to air) to help facilitate the reaction inside the gasifier. This oxygen (95-99% pure) is generated in an air separation unit (ASU) using proven cryogenic technology.

Gasifier

The core of the gasification system is the gasifier, a pressurized vessel where the hydrocarbon feedstock is converted into syngas in a partial oxidation reaction. A controlled amount of oxygen, steam and feedstock enter the gasifier. The temperatures in a gasifier range from 1,400-2,800 degrees Fahrenheit (700-1500°С). The heat and pressure break apart the chemical bonds of the feedstock, forming syngas.

By-products

Most solid liquid-feed gasifiers produce a vitrified or glass-like byproduct called slag which is non-hazardous and can be used in roadbed construction and in roofing materials. Also, in most gasification plants, more than 99% of the sulfur is removed and recovered either as elemental sulfur or sulfuric acid.

Gas cleanup

The raw syngas contains trace levels of impurities which must be removed before it can be used as a fuel. Trace minerals, particulates, sulfur, mercury, and unconverted carbon are removed to very low levels using processes common to the chemical and refining industries. Any remaining carbon, in the form of CO₂ can be removed as the syngas is cleaned.

Gas shift conversion

The clean gas is then converted primarily into hydrogen (H₂) and carbon dioxide (CO₂). The CO₂ is then removed from the converted gas using a number of commercial technologies. Ammonia and hydrogen manufacturing plants routinely remove CO₂ using a commercially proven process, as do plants which manufacture fuels and substitute natural gas.

CO₂ removal (for power)

Many predict that coal-based power plants and manufacturing facilities will be required to capture and store CO₂ or participate in a carbon cap and trade market. In this scenario, the Coal Gasification projects will have a cost advantage over conventional coal combustion technologies. Removing CO₂ at an IGCC plant costs $36-42 per ton compared with $75 per ton for pulverized coal plants, according to the US Department of Energy.

CO₂ removal (for products)

It is now a design requirement in all industrial Coal Gasification projects (such as those used to produce chemicals, fertilizers or substitute natural gas), to separate and capture any CO₂ formed in the syngas, and for this reason the added cost to compress and store CO₂ from these projects can be as low as $10 per ton.