Bench Scale Demonstration Of Hot Gas Desulfurization Technology Quarterly Technical Progress Report January 1 March 31 1994

The U.S. Department of Energy (DOE), Morgantown Energy Technology Center (METC), is sponsoring research in advanced methods for controlling contaminants in hot coal gasifier gas (coal gas) streams of integrated gasification combined-cycle (IGCC) power systems. Through bench-scale development, both fluidized-bed zinc titanate and Direct Sulfur Recovery Process (DSRP) technologies have been shown to be technically and economically attractive. In the zinc titanate approach, sulfur dioxide is the produced and must be disposed of in an environmentally sound manner. In the DSRP, elemental sulfur is the catalytic product.

Research Triangle Institute (RTI) with DOE/METC sponsorship has been developing zinc titanate sorbent technology since 1986. In addition, RTI has been developing the Direct Sulfur Recovery Process (DSRP) with DOE/METC sponsorship since 1988. Fluidized-bed zinc titanate desulfurization coupled to the DSRP is currently the most advanced and attractive technology for sulfur removal/recovery for IGCC systems, and it has recently been proposed in a Clean Coal Technology project. The goal of this project is to continue further development of the zinc titanate desulfurization and DSRP technologies by: scaling up the zinc titanate reactor system; developing an integrated skid-mounted zinc titanate desulfurization-DSRP reactor system; testing the integrated system over an extended period with real coal-gas from an operating gasifier to quantify the degradative effect, if any, of the trace contaminants present in coal gas; developing an engineering database suitable for system scaleup; and designing, fabricating and commissioning a larger DSRP reactor system capable of operating on a six-fold greater volume of gas than the DSRP reactor used in the bench-scale field test. During this reporting period the Construction Permit Application was completed and approved by the Process Safety Committee, and a final revised Application has been submitted to DOE/METC. A draft Test Plan for the field test was formulated. Finally, progress was made in the reactor system fabrication with the submission of purchase orders for nearly all major equipment, and with the final design of the trailer (mobile laboratory).

At the start of the current project, the DSRP (Direct Sulfur Recovery Process) technology was at the bench-scale development stage with a skid-mounted system ready for field testing. The process had been extended to fluidized-bed operation in the Stage 1 reactor. A preliminary economic study for a 100 MW plant in which the two-stage DSRP was compared to conventional processes indicated the economic attractiveness of the DSRP. Through bench-scale development, both fluidized-bed zinc titanate and DSRP technologies have been shown to be technically and economically attractive. The demonstrations prior to the start of this project, however, had only been conducted using simulated (rather than real) coal gas and simulated regeneration off-gas. Thus, the effect of trace contaminants in real coal gases on the sorbent and DSRP catalyst was not known. Also, the zinc titanate desulfurization unit and DSRP had not been demonstrated in an integrated manner. The overall goal of this project is to continue further development of the zinc titanate desulfurization and DSRP technologies by scale-up and field testing (with actual coal gas) of the zinc titanate fluidized-bed reactor system, and the Direct Sulfur Recovery Process.

The US Department of Energy (DOE), Morgantown Energy Technology Center (METC), is sponsoring research in advanced methods for controlling contaminants in hot coal gasifier gas (coal gas) streams of integrated gasification combined-cycle (IGCC) power systems. The programs focus on hot-gas particulate removal and desulfurization technologies that match or nearly match the temperatures and pressures of the gasifier, cleanup system, and power generator. The purpose is to eliminate the need for expensive heat recovery equipment, reduce efficiency losses due to quenching, and minimize wastewater treatment costs. Hot-gas desulfurization research has focused on regenerable mixed-metal oxide sorbents which can reduce the sulfur in coal gas to less than 20 ppmv and can be regenerated in a cyclic manner with air for multicycle operation. Zinc titanate (Zn2TiO4 or ZnTiO3), formed by a solid-state reaction of zinc oxide (ZnO) and titanium dioxide (TiO2), is currently the leading sorbent. The sulfidation/regeneration cycle can be carried out in fixed-bed, moving-bed, or fluidized-bed reactor configuration, and all three types of reactors are slated for demonstration in the DOE Clean Coal Technology program. The fluidized-bed reactor configuration is most attractive because of several potential advantages including faster kinetics and the ability to handle the highly exothermic regeneration to produce a regeneration offgas containing a constant concentration of SO2.

The U.S. Department of Energy (DOE), Morgantown Energy Technology Center (METC), is sponsoring research in advanced methods for controlling contaminants in hot coal gasifier gas (coal gas) streams of integrated gasification combined-cycle (IGCC) power systems. The programs focus on hot-gas particulate removal and desulfurization technologies that match or nearly match the temperatures and pressures of the gasifier, cleanup system, and power generator. The work seeks to eliminate the need for expensive heat recovery equipment, reduce efficiency losses due to quenching, and minimize wastewater treatment costs. Hot-gas desulfurization research has focused on regenerable mixed-metal oxide sorbents which can reduce the sulfur in coal gas to less than 20 ppmv and can be regenerated in a cyclic manner with air for multicycle operation. Zinc titanate (Zn2TiO4 or ZnTiO3), formed by a solid-state reaction of zinc (ZnO) and titanium dioxide (TiO2), is currently one of the leading sorbents. This report summarizes the highlights and accomplishments of the October slipstream test run of the Zinc Titanate Fluid Bed Desulfurization/Direct Sulfur Recovery Process (ZTFBD/DSRP) Mobile Laboratory at the Department of Energy's Morgantown Energy Technology Center. Although the run had to be shortened due to mechanical problems with METC's gasifier, there was sufficient on-stream time to demonstrate highly successful operation of both the zinc titanate fluid bed desulfurization and the DSRP with actual coal gas.