An experimental study of NO{sub x} recycle in the NOXSO flue gas cleanup process. Quarterly technical progress report, July 1--September 31, 1992

NO{sup x} recycle represents one part of the NOXSO process. This process can remove 90% of NO{sub x} and SO{sub 2} simultaneously from flue gas by using a fluidized bed of sorbent. Spent sorbent is regenerated by treatment at high temperatures with a reducing gas. Adsorbed NO{sub X} is evolved on heating the sorbent to a regeneration temperature. The concentrated stream of NO{sub x} produced is returned to the boiler with the combustion air and reduced in the flame, which is called NO{sub x} recycle. In the previous reporting period (from April to June), NO injection series of tests have been completed. Part of NO simultaneous injection and NO{sub 2} injection tests were conducted. All the test results showed consistent trends. About 70% average NO{sub x} reduction efficiency has been achieved when NO is injected into the primary air duct, which was not affected by the NO injection flow rate, the furnace load and exit O{sub 2} concentration. When NO is injected into the secondary air duct, the NO{sub x} reduction efficiency ranges from 46% to 60 % with dependence on the exit O{sub 2} concentration. The NO simultaneous injection tests showed that the NO{sub x} reduction efficiency increases with the percentage of total NO injected into the primary air duct. About 67% average NO{sub x} reduction efficiency was demonstrated with injection of NO{sub 2} into the secondary air duct, which is higher than that with injection of NO at the same test conditions