Catalytic Steam Reforming of Gasifier Tars: On-Line Monitoring of Tars with a Transportable Molecular-Beam Mass Spectrometer; Milestone Completion Report

Carpenter, D. ; Ratcliff, M. ; Dayton, D.

National Renewable Energy Laboratory (U.S.)

关键词: Alternative Fuels;    10 Synthetic Fuels;    Monitoring;    Carbon Monoxide;    Catalytic Steam Reforming;   

DOI  :  10.2172/15000383
RP-ID  :  NREL/TP-510-31384
RP-ID  :  AC36-99-GO10337
RP-ID  :  15000383

美国|英语

来源: UNT Digital Library

【 摘 要 】

A method for evaluating catalytic tar decomposition in real time is presented. The effectiveness of two catalysts are compared. A key technical and economic barrier to commercialization of biomass gasification technologies is the removal of tars that are unavoidably formed in this thermochemical process. Tars contain fuel value; however, they are problematic in gas engines (both reciprocating and turbine) because they condense in the fuel delivery system, forming deposits that negatively affect operation and efficiency. These tars also combust with high luminosity, potentially forming soot particles. The conventional technology for tar removal is wet scrubbing. Although this approach has shown some success, there are significant equipment and operating costs associated with it. In order to prevent the generation of toxic wastewater, the tars must be separated and either disposed as hazardous waste or, preferably, combusted in the gasification plant. A conceptually better approach is catalytic steam reforming of the tars to hydrogen and carbon monoxide (CO), effectively increasing the gasification efficiency and eliminating the problems mentioned above. In FY2000, Battelle Columbus Laboratories attempted to demonstrate integrated gasification-gas turbine operation using catalytic steam reforming of tars. NREL participated in those tests using the transportable molecular-beam mass spectrometer (TMBMS) to monitor the catalytic reactor's performance on-line [10]. Unfortunately, the pilot plant tests encountered operational problems that prevented conclusive determination of the efficacy of the selected catalyst (Battelle's DN34). In FY2001, NREL performed on-site tar steam reforming tests using a slip-stream of hot pyrolysis gas from the Thermochemical Process Development Unit (TCPDU), which was directed to a bench-scale fluidized bed reactor system designed expressly for this purpose. Supporting this effort, the TMBMS was employed to provide on-line analysis of the tar conversion. The gas composition changes were monitored by two identical gas chromatographs (GCs), and modified method 5 sampling was performed to obtain gravimetric conversion data. The combination of these analytical techniques provided definitive catalyst performance data, as well as linkage to previous and on-going work elsewhere. Two catalysts were tested: nickel (Ni) on potassium promoted alumina (Sued-Chemie C11-NK), used commercially for naphtha steam reforming, and alumina (Battelle's DN34) claimed to be effective for gasifier tar decomposition. In addition, sand was tested as an inert reference material.