Development of a regenerative fluidized-bed process for simultaneous removal of SO, and NO, from flue gas has been underway at the Pittsburgh Energy Technology Center(PETC) since the late 1960's. In 1970, McCreaet d. [I] reported on the bench-scale evaluation of SO, removal using copper-impregnated alumina spheres and presented preliminary design criteria for a process to be used to treat flue gases from a 1000-MW utility boiler burning a 3%-sulfur coal. A copper-impregnated UOP alumina sorbent, containing 6.3 wt.% Cu, was tested over 200 cycles of SO, absorption arid regeneration with CH, in a fixed-bed bench-scale reactor. No deterioration of the physical or chemical properties of the sorbent was observed during these tests.Fluidized-bed testing(& PETC) ofthe same sorbent material was begun in 1975 using a 6-inch (15.2-cm)-diameter reactor, and the initial results were reported by Strakey et al. [Z]. The tests were conducted with the combustion products of natural gas, spiked with SO,. The SO, removal was measured as a function of solids feed rate, bed height (18 inches and 36 inches; 0.457 m and 0.914 m), and bed temperature (662°F and 750°F or 350°C and 400°C); 75 absorption-regeneration cycles were completed. During several cycles, ammonia was injected for the simultaneous removal of NO,.The results of this study were sufficiently promising to merit continued development of the process. In addition to a continuing evaluation of repeated sorptiodregeneration cycles on sorbent activity, the test program included the following: a determination of the effect of NHJNO, mole ratio on simultaneous removal of SO, and NO,; measurement of ammonia "slip" (unreacted ammonia); in situ measurements of sorbent attrition occurring in t h e fluidized bed; and an evaluation of the effect of fly ash addition on reactor performance. The results of these successful tests were reported at the 1982 Summer National Meeting of the AIChE in Cleveland , Ohio [3].Based on the results ofthe previous research, a 3 ft4 inch x 4ftOinchcross-section x 12ftOinch(1.016 m x 1.219 m cross-section x 3.658 m) high fluidized-bed absorber was designed, fabricated, and installed in a 500 lb/hr (2.268 kg/h) pulverized-coal-fired combustion test facility. A 2 ft 6 inch (0.762 m) diameter x 26 ft 0 inch (0.66 m) high regenerator was also constructed to regenerate the spent sorbent from the absorber. The results of tests conducted in this facility are discussed in this report.

An experimental unit was built to burn 125 lb of coal an hour at 4000 deg F in a cyclone burner with oxygen-enriched air preheated to 1500 deg F to ascertain the fireside corrosion problems that might be encountered in the coal-fired MHD generation of power. Potassium carbonate was added to the coal at seed concentrations that would be expected in an MHD combustor. Tubes having a metal composition used in conventional steam generators, and also having a range of alloy compositions that might have potential use in an MHD system, were maintained at surface temperatures of 800–1500 deg F and exposed to products of combustion at 1800–2500 deg F. The seeded flue gas was generally more corrosive than the unseeded. In tests up to 100-hr duration, Haynes 25 was slightly attacked at a wall temperature of 1500 deg F in combustion gas at 2500 deg F; the stainless steels 310, 316, and 446 were resistant at a metal temperature of 1100 deg F in gas at 2100 deg F; carbon steel was attacked at 800 deg F wall temperature and 1800 deg F flue gas.

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Crucial and limiting engineering and naterials problems associated with the design of an MHD steam bottoming plant are discussed. Existing experimental and theoretical results ori corrosion, fouling and deposits, potassium seed recovery and regeneration, are reviewed. The state of knowledge regarding the design of heat recovery and seed recovery units for coal-fired MHD plants is inadequate at the present time. nones ^ fORTIONS OF THIg_gEPOgT^RE ILLEGIBLE. It has been reproduced from the"biit1^;ia^ie copy to permit the broadest possible avail-BMlltV. MASTER DISTRIBOTIOI? OF THIS mmi^J IS UNLIMITED sfet iJs'M'mB DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government.