| In this paper,the mixed combustion of circulating fluidized bed boiler sludge is the research object,and the elemental analysis of urban sludge in Xuzhou City is carried out,and the pyrolysis characteristics under different gases are analyzed by thermogravimetric analyzer.At the same time,an on-site mixed combustion experiment of sludge in a circulating fluidized bed boiler was carried out,and the FLUENT software was used to numerically simulate the furnace temperature distribution and products of the combustion process.Finally,in order to increase the mixing ratio of wet sludge,the sludge low-temperature drying scheme was designed and optimized.The main work of this paper is summarized as follows:First,the overall situation of urban domestic sludge in Xuzhou area was investigated,including geographical distribution,total amount,and elemental analysis of the composition of the sludge.It was found that the highest element content was Zn,which exceeded the environmental quality standard value of agricultural land,and Cr Exceeds the quality standard value of acid soil.Through analysis,it is concluded that the content of Cd and Hg in the sludge in Xuzhou is very low,and in the case of incineration,there will be no obvious toxic effects,and the feasibility of mixed sludge incineration is initially clear.A laboratory study of sludge was carried out using thermogravimetric analyzers and other equipment.It is found that the sludge heating rate has a significant effect on the pyrolysis and combustion of the sludge.With the increase of the heating rate,the maximum weight loss rate will greatly increase,and the temperature corresponding to the maximum weight loss rate also tends to high temperature with the increase of the heating rate Move in direction.The flue gas analysis of the combustion process shows that the harmful gases emitted with the change of sludge temperature are mainly NO and SO2.It further clarifies the feasibility of mixed burning sludge in circulating fluidized bed power plants.Secondly,an on-site experiment of sludge blending was carried out.It was verified that when the ratio of sludge blending was less than 6%,the combustion efficiency of 2×300MW unit boilers decreased very little,within 3%,which had little effect on the operation of the boiler;When the burning rate is increased to 10%,the combustion efficiency of the 300 MW unit boiler will drop significantly,above 3%,which will have a certain impact on the operation of the boiler.The recommended ratio for mixed burning of wet sludge in 2×300MW units is less than 6%.In the mixed firing field experiment,the pressure and temperature of the main steam and the reheated steam did not fluctuate significantly;the temperature in the circulating fluidized bed furnace was significantly reduced by 10-30 degrees.In order to obtain the prediction of the performance and emissions of the boiler when a higher proportion of sludge is mixed,this paper also carried out a related numerical simulation study,and found that boilers with a mixed burning ratio of more than 30%can no longer operate effectively.Finally,in order to maximize the use of sludge and increase the proportion of mixed combustion,this paper considers the selection of waste heat,the design of the main body of the solar drying chamber,the layout of the ventilation system and the optimization process,etc.,and proposes solar-waste heat combined low-temperature drying The wet sludge solution has unique advantages in thermal power plants. |
