How to reduce carbon content in fly ash of circulating fluidized bed boiler.

The influence of boiler bed temperature, increasing boiler bed temperature, can effectively reduce the carbon content of fly ash; On the contrary, when the boiler bed temperature is low, the carbon content of fly ash is naturally high. Of course, increasing the operating load percentage of the boiler as much as possible can also increase the bed temperature of the boiler, and the burning degree of particles (particles that can not be collected by the separator) passing through the combustion chamber at one time is naturally higher, and the carbon content of fly ash is low; On the contrary, fly ash has high carbon content. Influence of excess air coefficient. Adjusting the ratio of primary air and secondary air to effectively reduce the carbon content of fly ash is the main means to ensure the economic combustion of boilers. Properly increasing the excess air coefficient and increasing the oxygen concentration in the combustion zone will help to improve the combustion efficiency. The influence of particle size and moisture of coal in the furnace: on the one hand, the bed laminar flow is not good, on the other hand, the total surface area of carbon particles is reduced, and the diffusion resistance of coal particles is large, resulting in a small reaction area, which prolongs the time for burning out of particles, and the carbon particles in the center of particles cannot be burned out, resulting in black cores, which reduces the combustion efficiency, and at the same time causes insufficient circulating ash, insufficient combustion in dilute phase area and decreased output. In addition, a large number of deposits and poor fluidization increase the possibility of local coking and make slag discharge difficult. Particle size is too small, bed expansion is high, and it is easy to burn, but it is easy to cause flue gas entrainment, and many fine particles can not be captured and separated by the separator and escape, which is not conducive to burning out, and the carbon content of fly ash is high. The reason why the particles are too small and the carbon content of fly ash is high is that the residence time of pulverized coal in the furnace is too short to burn. The influence of separator separation efficiency: the separator has high separation efficiency, small cutting particle size and low carbon content in fly ash; On the contrary, the separator has low separation efficiency, large cutting particle size and high carbon content in fly ash. The influence of circulating combustion of dust removal ash for anthracite which is difficult to burn out, the carbon content of fly ash after circulating combustion of separated ash is still high. In order to further reduce the carbon content of fly ash, a more effective measure is to adopt dust circulation combustion.