Design and Research on Denitrification of Urea in a New Household Biomass Boiler

Abstract

In order to make full use of the biomass resources such as straw and wood in rural areas, the hourglass furnace structure and urea spray denitrification system were designed to solve the problem of high nitrogen oxide emission in rural household biomass boilers, and the combustion experiments were carried out by building a boiler test bench. In this paper, three kinds of biomass briquette fuel were selected for experimental research. By measuring the emission concentration of nitrogen oxides, the oxygen content of flue gas, and burning temperature in the furnace, combined with the formation mechanism of nitrogen oxides, the influence of the position of spraying urea solution, the mass concentration of spraying urea solution, and the influence of biomass fuel types on the emission concentration of nitrogen oxides was analyzed in details. The results show that the nitrogen oxides of biomass fuel are mainly produced in the secondary combustion area of the boiler, so spraying urea solution in the secondary combustion area can remove more nitrogen oxides generated by combustion. With the increase of the mass fraction of urea solution, the nitrogen oxide emission concentration showed a trend of decrease at first and then increase. When the mass fraction of urea solution was 9.96%, the nitrogen oxide emission concentration of boiler was the lowest. When different biomass fuels burned, the yield of nitrogen oxides changed with the change of the content of N element in the fuel itself, but the value of flue gas oxygen content should also be taken into account when calculating the reference oxygen content conversion concentration.

Keywords

• biomass energy
• nitrogen oxides
• boiler denitrification
• urea
• oxygen content of flue gas