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Enhanced Gasification; TurnW2E™

W2E has developed waste-to-energy technology for utilizing a variety of waste materials to make renewable and alternative energy products. The technology can process virtually any carbonaceous material, converting it into forms of usable energy that can be consumed or sold easily. At the core of the W2E technology is a process known as gasification. It is a well-known technology for converting materials into a clean-burning synthesis gas, which is then combusted for power production, or further processed to produce hydrogen for transportation fuels, or ammonia for use in fuel cells or as fertilizer. The history of gasification process goes back many decades. There is significant experience with wood gasification at various system sizes, and with coal gasification, at relatively large applications. The W2E technology has incorporated the best elements of past gasification designs and performances to yield a very flexible and reliable waste-to-energy system.


Gasification converts any carbon-containing material into a synthesis gas (syngas). The syngas is a combustible gas mixture, sometimes known as ‘producer gas’, typically contains carbon monoxide, hydrogen, nitrogen, carbon dioxide and methane. The syngas has a relatively low calorific value, ranging from 100 to 300 BTU/SCF. The syngas can be used as a fuel to generate electricity or steam. Alternatively, it can be used as a basic chemical building block for a large number of applications in the petrochemical and refining industries. The overall thermal efficiency of gasification process is more than 75%. Gasification can accommodate a wide variety of gaseous, liquid, and solid feed stocks and it has been widely used in commercial applications for more than 50 years in the production of fuels and chemicals. Conventional fuels such as coal and oil, as well as low- or negative-value materials and wastes such as petroleum coke, heavy refinery residuals, secondary oil-bearing refinery materials, municipal sewage sludge, hydrocarbon contaminated soils, and chlorinated hydrocarbon byproducts have all been used successfully in gasification operations.


The chemical reactions in gasification process take place in the presence of steam in an oxygen-lean,reducing atmosphere. The ratio of oxygen molecules to carbon molecules is far less than one in the gasification reactor.

A portion of the fuel undergoes partial oxidation by precisely controlling the amount of oxygen fed to the gasifier. The heat released in the first reaction provides the necessary energy for the other gasification reaction to proceed very rapidly. In the Turn W2E™ system, gasification temperatures and pressures within the refractory-lined reactor typically range from 800 Deg C to 1200 Deg C and near atmospheric pressure to few inches of water respectively.

At higher temperatures the endothermic reactions of carbon with steam are favored. A wide variety of carbonaceous feed stocks can be used in the gasification process. Low-BTU wastes may be blended with high - BTU supplementary fuels such as coal or petroleum coke to maintain the desired gasification temperatures in the reactor.

The reducing atmosphere within the gasification reactor prevents the formation of oxidized species such as SO2 and NOx which are replaced by H2S (with lesser amounts of COS), ammonia, and nitrogen (N2). These species are much easier to scrub from the syngas than their oxidized counterparts before the syngas is utilized for power.

While gasification and incineration are both thermal processes, it is important to point out the advantages of gasificati on over incineration. Incineration is simply a mass burn technology with heat recovery to produce steam and/or electricity. It has negative connotations because during the direct combustion of the waste, dangerous carcinogenic compounds such as dioxins and furans are formed, which are discharged into the atmosphere. In contrast, gasification employs the conversion of waste into syngas, which can then be used for generating steam and/or electricity, for producing chemicals for high-value products, or for producing liquid fuels.

1850-1940 • To produce “town gas” for light & heat
• Gasification of coa - All gas for fuel and light
1940-1975 • To produce synthetic fuel
• To produce liquid fuels and chemicals
1975-1990 • First Integrated Gasification Combined Cycle (IGCC) electric power plant
1990-2000 • US agencies provided fi nancial support for IGCC process
2000-Present • Turnkey thermal & power Green house gas from biomass
• Renewed focus on reducing GHG emissions
• Biomass to liquid fuel conversion commercialized

The synthesis gas is produced under controlled conditions, and is generated without the formation of impurities associated with incinerator flue gas. Gasification emissions are generally an order of magnitude lower than the emissions from an incinerator.

Key differences between Gasification and Incineration
Combustion Vs. Gasification
Designed to maximize the
conversion of waste to CO2 and H2O
Designed to maximize the conversion of
waste to CO and H2
Employs large quantities of
excess air
Operates under controlled amount of air
Highly oxidizing environment Reducing environment
Gas Cleanup
Treated flue gas discharged to atmosphere. Flue gas contains dioxins and furans Cleaned syngas used for chemical production and / or power production (with subsequent clean flue gas discharge)
Fuel sulfur converted to SOx and discharged with flue gas Recovery of reduced sulfur species in the form of a high purity elemental sulfur or sulfuric acid byproduct is feasible
Residue and Ash Slag Handling
Bottom ash and fly ash collected and disposed as waste Bottom ash and fl y ash collected and disposed of as waste



There are many carbonaceous materials that are suitable for gasification. These include wood, paper, peat, lignite, coal, including coke derived from coal, saw dust and agro-residues. All of these solid fuels are composed primarily of carbon with varying amounts of hydrogen, oxygen, and impurities, such as sulfur, ash, and moisture.Municipal Solid Waste (MSW) is also a good candidate for gasification; however, it poses a special challenge for waste processors, due its non-homogenous characteristics, high moisture content and unpredictable calorific value.


W2E has overcome this challenge by designing a unique gasifier. Thus, the TurnW2E™ gasification process presents a new and better method for the treatment of non-homogenous waste streams. Gasification is fast becoming a favored technology for recovering energy from MSW and other solid wastes, and the TurnW2E™ system stands ready to provide this service to the industry.




Moving Bed: The fuel is dry-fed through the top of a reactor onto a bed – usually a slow-moving metal grate. As the fuel descends, it reacts with gasifying agents (steam and oxygen) flowing in a counter-current through the bed. The syngas has a low temperature (400-500 Deg C) and contains significant quantities of tars and oils.

Entrained Flow: The fuel and gasifying agents flow in the same direction (and at rates in excess of other gasifier types). The feedstock – which may be dry-fed (mixed with nitrogen) or wet-fed (mixed with water) – goes through the various stages of gasification as it moves with the steam and oxygen flow.

Fluidized Bed:
The fuel, introduced into an upward flow of steam/ oxygen, remains suspended in the gasifying agents while the gasification process takes place.

Rotary Reactor: Gasifying agents, air and/or oxygen and steam are introduced along a rotating horizontal cylindrical reactor vessel. Gasification takes place along the length of the vessel in stages until SynGas is released from the end while ash drops out. Rotary reactors, such as the TurnW2E(TM) developed by W2E, enable complete mixing of the gasifying agents with air while the process is closely controlled by the rotational speed and air flow. The lower gas temperatures (800 - 900 Deg C) - while high enough to volatilize tar and oils – allows easier handling of ash.
Gasification Methods
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