Adoption of advanced dry-solids feed pump would benefit power and chemical production. Gasification is a versatile technology that uses coal to produce power, chemicals, and fuels. Inherently low in air emissions, solid byproducts, and wastewater, commercial gasification plants have proven capable of exceeding the most stringent regulations for air- and solids-emissions. However, capital and operational costs have prohibited its widespread adoption, especially for power production-a major source of anthropogenic carbon dioxide (CO2) emissions.
Now, in a project funded by the US Department of Energy’s Office of Fossil Energy, Pratt & Whitney Rocketdyne has developed a high-pressure dry-solids feed pump that could make gasification economically competitive by improving efficiencies and introducing low-rank Western US coal as a viable feedstock option. The project is a collaborative effort among Pratt & Whitney Rocketdyne, the Office of Fossil Energy’s National Energy Technology Laboratory (NETL), ExxonMobil Research and Engineering Co, Alberta Innovates – Energy and Environment Solutions, and the Environmental and Engineering Research Center at the University of North Dakota.
Today’s commercial dry-feed gasification systems are limited to processing pressures of about 31 bar. Pratt & Whitney Rocketdyne’s feed pump more than doubles those pressures to 70 bar. Higher system pressures mean higher system efficiencies; higher efficiencies translate into less coal used to produce power and other products. Capital, operations, and maintenance costs are lower and resources are extended.
Add in the ability of the Pratt & Whitney Rocketdyne system to feed low-rank coal into gasifiers, and costs are further reduced. Low-rank coal contains less energy per pound than higher-ranked bituminous coal, so it is typically considered too low in energy density for current slurry-fed gasification systems. However, approximately 50% of the coal produced in the US is low-rank sub-bituminous coal and lignite, mined predominantly in the western states. The ability of the system to use these lower-cost feedstocks can further enhance the option of gasification and provide an economic boon to low-rank-coal-producing states like North Dakota, Wyoming, and Texas.
Environmental gains could be considerable. Coal gasification holds the promise of making industrial carbon management a reality by producing a CO2 stream that is ready for capture, utilization, and storage. Widespread adoption of gasification for power-production could significantly reduce CO2 emissions and mitigate climate change. Gasification-based power generation also uses about half the water consumed by combustion-based coal power production. Compared to conventional slurry-feed systems, the Pratt & Whitney Rocketdyne feed pump further reduces water use by cutting or eliminating its addition.
With broad commercialisation of gasification in the US, especially with the option of using low-rank coal, adoption of gasification technology could be realized around the world. India, China, Turkey, Australia, and Eastern Europe, in particular, have considerable reserves of low-rank coal. Their ability to gasify these resources would not only benefit the US gasification technology industry through technology transfer, but it would result in a global environmental benefit by enabling these countries to more actively participate in carbon capture, use and storage initiatives.
The first Pratt & Whitney Rocketdyne commercial-scale high-pressure dry-solids feed pump was commissioned at the Environmental and Engineering Research Center on April 10, 2012. There it will undergo nine to 12 months of demonstration-scale testing to determine the pump’s flexibility in handling feed types, particle sizes, and pressure ranges. If successful, Pratt & Whitney Rocketdyne will make the pump available to industry for commercial use, and gasification will have an opportunity to make a difference in the economic and energy security of the world.
