Power generation from biomass

NOx reduction

High NOx content in diesel exhausts represents a great environmental challenge. A number of technical approaches are suggested to solve the problem. One of them is based on the reaction of selective catalytic reduction (SCR) of NOx in diesel exhausts by reducing gas additives, such as unsaturated hydrocarbons, propane, diesel fuel, ammonia, or urea. Recent studies showed a mixture of hydrogen and carbon oxide (products of autothermal reforming of diesel fuel) to be an efficient NOx reducing agent. Application of this technology in the framework of Bioliquids-CHP project at the first purification stage implies the conversion of a mixture of refined pyrolysis oil and diesel fuel to synthesis gas using a part of exhaust gases. At the second purification stage, it is suggested to add the obtained synthesis gas to diesel exhausts to provide the reaction of SCR of NOx to nitrogen. The reaction is run in a reactor with a radial catalyst bed. The optimum conditions of the reaction of synthesis gas production are as follows: О2/С = 0.5-0.6, Н2О/C = 1.5-1.7, GHSV=12000-15000h-1, inlet temperature 300-400°С. The optimum SCR conditions are as follows: GHSV=20000h-1, inlet temperature 250-350°С, typical inlet gas composition: 6.3% CO2, 10-12.5% H2O, 13.4-7.2% O2, 1000 ppm CO, 500 ppm NOx, 2000-3000 ppm Н2.