ECN SYSTEM FOR METHANATION (ESME)

摘要

The Energy research Centre of the Netherlands (ECN) has developed and patented a novel concept forrnthe methanation of gas from biomass gasification. The ECN System for Methanation (ESME) is especially designedrnfor gas from fluidized bed gasifiers such as Bubbling Fluidized Beds, Circulating Fluidized Beds and allothermalrngasifiers such as the ECN MILENA process or the FICFB process developed by the Technical University of Vienna.rnProducer gas from the gasifier must be first compressed to approximately 6 bar (in case of atmospheric gasification)rnafter tar and water removal. The ESME concept is unique because of the smart sequence and the operating conditionsrnof the different units. ESME allows the efficient conversion of producer gas to SNG because the hydrocarbonsrncontained in the producer gas (e.g. benzene, toluene) are not removed but converted, thus being available to bernconverted to methane. The prereformer catalyst simultaneously reforms aromatic hydrocarbons (e.g. benzene) andrnproduces methane, which has a positive consequence on the heat balance of the prereformer, since the heat releasedrnin the exothermic methanation reactions is supplied to the endothermic reforming of aromatic hydrocarbons. Otherrnadvantages of ESME include reduced compression cost and no need for gas recycling in the methanation units. Thernmain parts of the ESME system have been extensively tested under realistic conditions. In October 2014 a durationrntest of 500 hours was successfully performed with producer gas generated in the ECN MILENA gasifier and cleanedrnin the OLGA tar removal system. The availability of MILENA during the test was close to 90%, and the availabilityrnof the whole methanation system (MILENA + OLGA + ESME) was approximately 85%. The “raw bio-SNG”rnproduced contains (in dry basis) 52% vol. CO_2, 39% vol. CH_4, 2% vol. H_2, and traces of CO (~130 ppmv) and C2H6.rnThe gas composition after the methanation section was found to be at chemical equilibrium. Gas composition remainsrnnearly constant after several hundred hours operation despite variations in the inlet producer gas composition.rnCatalyst degradation was not observed or near detection limits. The produced bio-SNG should further undergo CO_2rnremoval (e.g. by amine scrubbing or ECN regenerative dry adsorption), water removal and a last high-pressurernmethanation step to remove the remaining H_2 and CO prior to injection to the grid. This milestone paves the way forrnthe scale-up of bioSNG production. In particular, a consortium formed by ECN and a number of partners intends tornbuild a 300 m~3/h SNG pilot-scale facility in the Netherlands.