Adding gas from biomass to the gas grid - SGC

The process achieves a 97% conversion of biomass carbon to useful syngas without producing troublesometars, oils, or other contaminating effluents. The process is robust in its ability to handle feedstocks withvarying degrees of inherent moisture, ranging from dry wood (in which case moisture is actually added tothe feedstock) to organic sludge with moisture contents of over 60%. In traditional gasification systems anymoisture in the feedstock results in an energy efficiency penalty. This process utilises a part of the moistureto produce hydrogen and other combustible gases. At 40% moisture in the feedstock, the system achievesan efficiency of about 80%.Figure 22: Process Flow Diagram of the Brightstar process Feed SystemDepending on the size, consistency and nature of the biomass, the material is often routed through ahammer-mill or tub grinder/classifier before entering the plant’s metering bin located above the feed system.The material is fed by gravity into the metering bin where it enters a screw feed system. The material is thenconveyed through a proprietary sealing mechanism that serves as the pressure seal on the front end of thesystem, keeping air out of the reformer and keeping syngas from backing up into the feed system. Thematerial received from the screw feeder is then conveyed with recycled compressed syngas into the primaryheat exchanger.page: 135