Optimization Of CFB Garbage Incinerator Combustion

Municipal solid waste is an urgent problem in China's current urban development.Under the pressure of"garbage siege",garbage incineration technology is being vigorously promoted and used in our country.Some circulating fluidized bed incinerators have problems with CO exceeding the standard.This paper analyzes the causes of CO exceeding standards by combining theoretical analysis,numerical simulation,and field testing.And this work has important practical significance to fluidized bed waste incineration enterprises.The theoretical analysis part calculates the combustion reaction of CO under different temperature,oxygen amount and residence time according to the combustion reaction mechanism and confirms the correctness of the 3T+E principle.The reasons for the excessive emissions of CO in some circulating fluidized bed waste incinerators were analyzed,mainly due to feed fluctuations,low reaction temperature,and insufficient combustion residence time,and corresponding suggestions were given based on theoretical calculations.Through numerical simulation,the rationality of the primary and secondary air under the operating conditions and feed fluctuations in the circulating fluidized bed waste incineration enterprise were determined.It was determined that the main factor of the CO emissions exceeded the standard is the fluctuation of the feed,and the primary and secondary air under the operating conditions has little effect on the exceeding CO emission concentration.On-site testing of the circulating fluidized bed waste incinerator was conducted,and the main directions were to increase the combustion temperature and realize feed automation.The tests to increase the combustion temperature mainly include increasing the amount of coal fed,installing methane burners,and reducing air leakage in the empty flue.After testing,it is found that when the coal is added to increase the temperature to 886°C,the CO emission concentration will be steadily lower than 100mg/m³.After installing a methane burner and the temperature rises to846°C,the CO emission concentration will be steadily lower than 100mg/m³.This may be the reason for the rapid and stable combustion of methane.After reducing air leakage in the empty flue,the CO emission concentration is reduced by about 11.3%and the concentration is141.5mg/Nm³.Feeding automation is achieved through program control.Compared with manual control,the CO emission concentration during automatic control is reduced by approximately63.6%and the concentration is 67 mg/Nm³,which successfully achieves standard discharge.The experimental study of dechlorination by adding calcium in the furnace was carried out.It was found that when the content of chlorine in the mixed fuel of waste and coal is higher than that of sulfur,the optimal calcium-chlorine ratio of sprayed limestone in the circulating fluidized bed waste incinerator is 2:1,and dechlorination efficiency can reach 61.1%.When the temperature is higher than 800?,CaCl₂ has a reaction ratio of up to 80%,and the reaction is mainly concentrated in the first 20 minutes.After the chlorine is fixed by limestone,it mainly exists in the solid form of CaCl₂ and collects in the ash with a small granularity.