Bio-SNG - CNG Services

BIO-SNG FEASIBILITY STUDY – ESTABLISHMENT OF A REGIONAL PROJECTthe system could reduce the Wobbe Index or Calorific value of the resulting Bio-SNG below the GS(M)Rlimits for pipeline quality. This is a key issue that would require resolution as part of the selection andspecification process for a gasification technology.ApproachNo penalty for oxygenproductionMethane content ex gasifierProven at substantive scaleDeployable at moderatescaleDeployable at large scaleFuel preparationTrack record on waste fuelsOptions to minimisepressurisation loadsTars ex unitChemical ContaminationIndirect gasification - -Direct gasification(fluidised bed) -Entrained flowPyrolysis to bio-oil - - Table 5-1Technical ideals and commercial realityGasification of wastes: It should be appreciated that for a considerable period of time the pursuit of thegasification of wastes has been focussed in the main not on the production of a quality syngas but inpursuit of the following:To assure destruction of hazardous chemicals at extreme temperaturesTo produce fused ash streams in which heavy metals may be trappedTo take advantage of particular support mechanisms (e.g. the Renewables Obligation)In an attempt to give lower emissions to the environment than conventional waste incinerationAccordingly it is important to understand that the technologies that are targeted at these objectives arenot necessarily focussed on the efficient production of a high quality syngas, which would be the overridingobjective of a gasifier producing syngas for Bio-SNG synthesis. Hence waste gasification systemsare in general unsuitable for this application. The HTW gasifier has, however, a track record of successfuloperation with waste-derived fuels 42 . Relevant examples of gasification projects are shown in Appendix1.42 The British Gas -Lurgi (BGL) fixed bed slagging gasifier at Schwartezepumpe had also some considerableoperating experienced with waste derived fuels, but only when co-fired with >70% coal.38