The Rocketdyne plug flow gasifier (RPFG) (also referred to by DOE as compact gasifier) is a single stage plug flow entrained flow slagging gasifier, with dry coal feed, short residence time, and quench. The gasifier also features a rapid mix multi-port feed injector and actively cooled walls. These features are claimed to result in lower capital cost, higher efficiency, greater durability, higher availability, ability to handle low rank coal/lignite and better carbon conversion all resulting in a lower cost of electricity in associated IGCC plants.
This combination of features potentially overcomes most of the drawbacks of current commercial gasifiers. In a EPRI presentation they stated: "with further enhancements, e.g. Jacobs desaturator, this could be the best gasifier for CO2 capture." The gasifier is in early development with pilot plant tests not scheduled for 2007.
This gasifier is an advanced gasifier being developed by DOE that promises higher efficiencies and lower capital cost than present gasifers as well as excellent carbon capture. If development goes as planned the technology will have been demonstrated on a pilot scale by 2010.
Requirements for the gasifier include operation 1000 psig or more at 2600 F and in the presence of corrosive H2S gas and slag. The high heating rates of this gasifier make possible very short gasification residence times, increased thermal efficiency and carbon conversions approaching 100 percent. Another result of the high heating rates is that the reactor is one-tenth the size of an equivalent conventional gasifier, reducing capital costs.
Projected performance of the RPFG is 75.7% efficiency vs 68.8 % for a conventional entrained flow gasifier operating with bituminous coal without carbon capture. With carbon capture the efficiencies are 73.5% vs 66.5 %. The increased efficiency is primarily due to the novel dry coal feed system.
This project is the first step in removing the technical and economic barriers that have prevented the widespread commercial deployment of coal-based gasification systems. The project objectives are to:
- Demonstrate long-life rapid-mix injectors in a commercial gasifier.
- Test cooled refractory liner coupons.
- Perform conceptual design and hardware definition of a 24 tpd pilot plant gasifier.
Both the long-life rapid-mix injectors and the actively cooled liners are based on Rocketdyne’s rocket technologies. The injector design uses multi-element injection to rapidly mix the coal with hot steam and oxygen while rapidly dispersing the coal across the reactor’s cross-section. Water cooling circuits are embedded inside the rocket engine style face plates to ensure long life of the injector unit – over 1 year.
The liner is also actively cooled, using slots in the refractory to carry coolant through and heat away, resulting in a frozen layer of slag inside the gasifier. This frozen layer of slag is expected to protect the refractory underneath, which is anticipated to have an operational life exceeding three years. By comparison, existing state-of-the-art gasifiers have injector lifetimes of two to six months, and refractory life of six to 18 months.
The period of performance is from Sept. 29 2004 to March 31 2007 and contract value is $7,083,204 with 80% being paid by DOE. The injectors and liner coupons will be tested at the Eastman gasification plant, Kingsford, TN which has a GE gasifier.
Rocketdyne is now a division of United Technologies Corporation operating as Pratt & Whitney Rocketdyne, a wholly owned subsidiary of UTC. It was a division of Boeing until 2005. The design stems from their work, while a part of Boeing, on ceramic fiber materials used in aerospace which they have extended into the refractory liner design. They have received two patents on their water cooled ceramic fiber liner systems. Likewise they have several patents on multi-fluid injection systems into combustion chambers which extends their experience with combustion turbines and rocket fuel injection systems.
Overview of Gasification Technologies, NETL, March 2005
Project Data for "Advanced Gasification Systems Development', approximately Oct, 1,2004
The Energy Blog: Rocketdyne Plug Flow Gasifier