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Cyclic Variations and Control of a Batch-Loaded Biomass Gasifier-Combustor

1996; Taylor & Francis; Volume: 113; Issue: 1 Linguagem: Inglês

10.1080/00102209608935513

1563-521X

D. Beedie, Philip John Bowen, Timothy O'Doherty, N. Syred,

Thermal and Kinetic Analysis

Abstract Uncontrolled batch-loaded biomass gasification systems exhibit large variations in gasification rate during the fuel cycle. A portable batch-loaded biomass gasification-combustion system has been improved by a control system regulating the supply of air to the gasifier (‘primary air’). The resulting time-varying gasification characteristic has been investigated by continuous measurements of air supply flow rates and the major flue gas species concentrations. It was found that a simple control system may use combustor exit temperature to monitor overall Excess Air Value (EXAV). With the control system maintaining a reasonably steady EXAV throughout the fuel cycle (requiring considerable variation in primary air), gasification rate falls while higher heating value (HHV) rises, causing thermal input to reach a minimum in mid-cycle. HHV was evaluated using a correlation accurate for a range of biomass materials. The correlation was found to be well approximated by considering carbon flux only.