Design and experimental investigation of a 190 kWe biomass fixed bed gasification and polygeneration pilot plant using a double air stage downdraft approach

This paper presented a systematic design and experimental results of a 190 kWe biomass fixed bed gasification and polygeneration pilot plant using a double air stage downdraft approach. Wood chips were used as feedstock that was converted through gasification polygeneration into three-phase (GSL) products, namely producer gas (gas), charcoal (solid) and extract (liquid). The pilot plant mainly encompassed double air stage GSL gasifier, gas cleaning system, gas engine, feed and discharge system and programmable logic controller (PLC) system. The results demonstrated that due to the secondary air supply, a temperature as high as 900 °C was achieved in the oxidation zone for better tar cracking. Use of both stirrer and reciprocating grate avoided bridging and channeling. Modified pipe bundle condenser and purification tower exhibited excellent performance in removing tar, water and particles in the producer gas with the maximal LHV (lower heating value) of 5.25 MJ/N m3. During the operation of a full capacity, the flow rate of producer gas was 500 N m3/h, whereas the production of charcoal and yield of extract were 60 kg/h, and 65 kg/h, respectively. The overall polygeneration efficiency from three-phase products (ηGSL) was 95.84%. Those pilot plant results will be used as reference in designing a scale-up 500 kWe gasification system.

► Three-phase products: gas, charcoal (solid) and extract (liquid) were produced through gasification polygeneration process. ► An innovative GSL gasifier with double air stage was designed to fulfill the polygeneration. ► Stirrer, grate, condenser and purification tower exhibited good performance in stablizing the operation of the system. ► T5 and LHV were improved as the increase of secondary intake air. ► Producer gas with stable compositions and LHV and low O2% was produced.