Coking treatment of biomass particles
Conventional coking treatment method - in the early biomass power plants, steam soot blowers were generally used for coking and dedusting treatment on the heating surface, but from the actual effect, it did not meet the requirements of coking. Only after the furnace is shut down, rinse with high pressure water for treatment. The main reason is that the potassium content in biomass fuel is high, which reduces the ash melting point, and the silicon element forms a low melting point compound with potassium in the combustion process, resulting in a low softening temperature of ash. According to the experimental data, the deformation temperature of grass and wood ash is about 800℃, and the temperature of the furnace superheater of the boiler is mostly within this range. Therefore, under high temperature conditions, The softened ash is easy to adhere to the outer wall of the heating surface pipe, and it is difficult to treat the accumulated coke with steam soot blower. According to previous experience, the use of steam soot blower general boiler after cleaning and put into use for 15 days, the main steam temperature control does not need to use warm water adjustment, the temperature is normally maintained at about 510 0C, after a month of operation need to stop the furnace for water flushing, otherwise the main steam temperature will be more and more deviated from the rating (540℃), the efficiency of the boiler decreases, The smoke exhaust temperature rises 5-10℃.
And the use of steam blowing ash will have the following problems:
(1) the medium blowing area is limited, there are some dead corners, easy to form a smoke corridor, aggravate local wear;
(2) The long blowing period makes the heating surface accumulate too much ash, and even makes the ash sintering and hardening, increasing the difficulty of blowing ash;
(3) If the pressure of steam blowing ash is too high or long-term use, it will accelerate the wear of the metal pipe wall, and the pressure is too low and affects the effect of blowing ash;
(4) Increase the flue gas humidity in the furnace, forming low temperature condensation at the air preheater, resulting in serious corrosion of the air preheater pipe;
(5) The mechanical parts of the high failure rate, high maintenance costs.
