Low NOx emission variable cross-section circulating fluidized bed staged combustion boiler system and method

Abstract

The invention discloses a low NOx emission variable cross-section circulating fluidized bed staged combustion boiler system and method. The system comprises a variable cross-sectional area furnace, afluidized bed activation chamber and a CO catalytic device; an upper flue gas outlet of the variable cross-sectional area furnace is connected with an adiabatic cyclone separator, the fluidized bed activation chamber is additionally arranged between a lower part returning mechanism of the adiabatic cyclone separator and a fuel-rich combustion chamber, the upper flue gas enters a vertical flue channel after discharging, and enters a supplementary air combustion chamber after heat exchange with a convection heat exchange surface; and a CO catalytic oxidation device is arranged on the downstreamof the supplementary air combustion chamber. According to the variable cross-section circulating fluidized bed boiler system, graded and efficient combustion of coal can be achieved, original emissionof NOx is reduced, and air pollution is reduced; to a certain extent, the problem of ash accumulation and slagging on the heating surface of the tail part is alleviated; returned materials are activated before entering a furnace, and the carbon conversion rate is improved; and an SCR denitrification device is eliminated, so that construction costs are saved, and problems such as catalyst deactivation and air preheater blockage caused by ammonia escape are avoided.

Description

technical field [0001] The invention belongs to the field of boiler design, and in particular relates to a low NOx emission variable cross-section circulating fluidized bed staged combustion boiler system and method. Background technique [0002] Circulating fluidized bed (CFB) boilers have the advantages of low-temperature combustion, excellent burnout conditions, and wide fuel adaptability. Compared with pulverized coal boilers, they have the advantage of naturally low NOx emissions. With the continuous improvement of people's requirements for environmental protection, the strict ultra-low emission standards for coal-fired units make the environmental protection advantages of CFB boilers no longer significant, and have to adopt a variety of low NOx combustion measures and even add selective non-catalytic reduction (SNCR) Or selective catalytic reduction (SCR) flue gas treatment equipment. The addition of SNCR equipment or SCR equipment will, to a certain extent, promote S...

AI Technical Summary

Problems solved by technology

The existing technologies for reducing the carbon content of fly ash focus on reducing the carbon content of fly ash as much as possible in the original boiler, and are limited by the wear and tear of the heating surface at the tail, energy consumption, etc., and the influence of the deactivation of fly ash particles. The carbon content of the fly ash treated by this technology still has a lot of room for reduction

Images