Thermal Gasification of Biomass Introduction

Amergas BV ProjectThis 30 MW e project is under construction at the Amerpowerstation at Geertruidenberg in southern Holland, togasify low quality demolition wood (about 150,000 TPY)which cannot be recycled by the chipboard industry. Thegasifier is an 83 MW th low-pressure, Lurgi CFB gasifier.The product gas will be cooled for steam recovery, scrubbedto remove particulates and ammonia and burnt in the coalfired Amer 9 cogeneration unit. The unit has a netproduction capacity of 600 MW e and 350 MW th . The startup of the plant is planned for early 2000.NorwayCourtesy of NOVEM,The NetherlandsAt present there are no demonstration or commercial biomass gasification projects inNorway. Potential applications for gasification may be to improve pulp and paper milloperations and for cogeneration in remote sites.SwedenGotaverken Project (Varo)The Gotaverken (Kvaerner) process employs a CFB gasification process developed in a2 MW th pilot plant at the Royal Institute of Technology. Sized and dried fuel is fed afew meters above the bottom of the gasifier to create two distinct zones. In the upperzone, biomass is flash pyrolyzed by coming in contact with hot circulating dolomite, ata temperature of 645°C, and produces fuel gas rich in C 2 + and some tars. In the lowerzone the recycled residual char is combusted with air to produce the hot flue gases thatpromote flash pyrolysis in the upper zone. The circulating bed of dolomite promotes tarcracking and reduces the amount of heavy hydrocarbons produced in the gasifier.The LCV fuel gas is partially cooled in a heat exchanger to preheatgasification air and then burnt in a lime kiln. The plant start up was in1987 and turned over to the customer in 1988. A typical gascomposition is 15% CO, 10% H 2 , 5% CH 4 , 3% C 2 +, 16% CO 2 , 8%H 2 O, and 43% N 2 . Gotaverken has not built any more such biomassgasification plants due to low oil prices.13