Advanced Process Technologies

There are several technologies currently under research and development (R&D) to improve the performance and economics of a gasification value chain. Some of the technologies are being developed in conjunction with other closely-aligned NETL programs: e.g., Carbon Capture and Sequestration, Turbines, and Hydrogen & Clean Fuels. Two examples of gasification-based process technologies of interest are briefly discussed below and in more detail on their linked pages.

Ion-Transport Membranes (ITM) Oxygen Separation
A major gasification R&D program objective is the development of cost-effective oxygen separation membranes. These can provide substantial cost reduction for oxygen separation in comparison with the current cryogenic technology. There are several major process advantages to using oxygen-blown gasifiers, and many existing and future gasification plants are or will be oxygen-blown. Since the air separation unit (or oxygen plant) is a major cost item in a gasification complex, as well as a major in-plant power user, there is substantial opportunity to improve the overall gasification plant’s economics and efficiency with improved air separation technologies.

Warm Gas Cleanup
In the overall gasification process, contaminants have to be removed from the raw synthesis gas (syngas) leaving the gasifier before it can be sent onto the downstream processes. This is done not only to meet environmental emission requirements, but also to protect downstream processes, such as gas turbines, catalysts, and fuel cells. Potential contaminants include particulates, ammonia (NH₃), hydrochloric acid (HCl), hydrogen sulfide (H₂S), carbon dioxide (CO₂), mercury, and other heavy trace metals. The raw syngas leaving the gasifier is at high temperature. It is immediately scrubbed to remove fine particulates and water soluble compounds like NH₃ and HCl. The gas requires cooling before it can be routed to a conventional acid gas removal (AGR) process downstream to remove the H₂S and CO₂. Current AGR technologies operate at about 100 ºF or below. The ‘clean syngas’ requires being re-heated before sending downstream, either to a gas turbine for power generation, or to a synthesis reactor. This cooling and reheating cycle imposes an efficiency penalty onto the overall gasification process.

Currently, a variety of different processes have to be used, in combination, for effective syngas cleanup. There is substantial opportunity to improve the overall gas cleaning system by developing technologies that can:

• Operate at higher temperature and remove multiple contaminates (Warm Gas Cleanup).

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