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1 What is Gasification?
2 Advantage of Gasification
3 Lists of Feedstocks that can be used in gasification
4 Chemistry of Gasification
5 References

What is Gasification?Edit

Gasification is the process of converting of carbonaceous feedstocks into synthesis gas (syngas - composed primarily of Hydrogen and Carbon Monoxide) using oxygen and steam to react with the solid fuel. It is a method of extracting green energy from different types of organic materials.

Advantage of GasificationEdit

The advantage of gasification is that using the syngas is potentially more efficient than direct combustion of the original fuel because it can be combusted at higher temperatures or even in fuel cells, so that the thermodynamic upper limit to the efficiency defined by Carnot's rule is higher or not applicable. Syngas may be burned directly in internal combustion engines, used to produce methanol and hydrogen, or converted via the Fischer-Tropsch process into synthetic fuel. Gasification can also begin with materials that are not otherwise useful fuels, such as biomass or organic waste. In addition, the high-temperature combustion refines out corrosive ash elements such as chloride and potassium, allowing clean gas production from otherwise problematic fuels.

Gasification of fossil fuels is currently widely used on industrial scales for power generation. However, almost any type of organic material can be used as the raw material for gasification, such as wood, biomass, and even municipal solid wastes. Gasification relies on chemical processes at elevated temperatures >700°C, which distinguishes it from biological processes such as anaerobic digestion that produce biogas.

An example of gasification is the Biosphere Gasification Technology or biosphere technology. This process harnesses the calorific value (combustibility) of Municipal Solid Wastes (MSW) to create a heat source that produces super heated steam via boiler, which then drives a combination stream turbine, to generate green electricity. It begins at the biosphere chamber wherein solid wastes are entered to begin the thermal transformation and derive a clean combustible gas or referred as syngas which is then used in a combined cycle gas/stream turbine to produce electricity. The heat generated by the process can be used to produce electricity, superheat steam, heat boiler feed water and distil desalinate seawater.

Lists of Feedstocks that can be used in gasificationEdit

Municipal Solid Waste
Automobile and Truck Tires
Petroleum and Polychlorinated Biphenyl (PBC) Waste
Agricultural Surpluses, animal waste or animal Parts Wastes and Affluent Industrial
Waste
Sour or Wet Natural Gas without refining
Soil-contaminated Waste
Land Fill Reclamation
Traditional Fossil Fuels, including sulfur contaminated coal and untreated Shale Oil
Petroleum drilling waste such as oil contaminated Top Soil, drill cuttings and
Oil-contaminated Ground Water

Chemistry of GasificationEdit

Following are the processes when carbonaceous material goes through in a gasifier;

The pyrolysis (or devolatilization) process occurs as the carbonaceous particle heats up. Volatiles are released and char is produced, resulting in up to 70% weight loss for coal. The process is dependent on the properties of the carbonaceous material and determines the structure and composition of the char, which will then undergo gasification reactions.
The combustion process occurs as the volatile products and some of the char reacts with oxygen to form carbon dioxide and carbon monoxide, which provides heat for the subsequent gasification reactions. Letting C represent a carbon-containing organic compound, the basic reaction here is
The gasification process occurs as the char reacts with carbon dioxide and steam to produce carbon monoxide and hydrogen, via the reaction
In addition, the reversible gas phase water gas shift reaction reaches equilibrium very fast at the temperatures in a gasifier. This balances the concentrations of carbon monoxide, steam, carbon dioxide and hydrogen.