Pilot Plant Results With the Piperazine Advanced Stripper at NGCC Conditions

Abstract

CO2 capture is necessary to decarbonize natural gas combined cycles (NGCC) that will be used to provide power when renewable power is unavailable. The PZAS™ (Piperazine (PZ) with the Advanced Stripper) second generation capture technology has been successfully tested with coal-fired flue gas. This paper reports reliable testing of PZAS at NGCC conditions for 2000 hours in a 0.66 m ID absorber at the National Carbon Capture Center (NCCC). Coal-fired flue gas diluted with air entered the absorber at 77 oC. 5 m PZ was regenerated by the Advanced Stripper with 2.45 gJ steam/tonne CO2 at 6.2 bara. With 40 feet of packing and pump-around intercooling the absorber provided 90–95% CO¬2¬ removal with a rich loading of 0.40–0.41 mol CO2/mol N. The apparent rate of PZ oxidation was 0.3 kg/tonne CO2. The water wash reduced PZ emission to less than 1 ppm. In the last 400 hours of testing, carbon treating clarified the solvent color, reduced ammonia production by as much as 40%, and improved both absorber and stripper performance. Testing with coupons showed that 304 SS had an acceptable corrosion rate even at the severe conditions of the stripper at 150 oC.