Analysis and treatment of coking in the burner of

2022-08-18
  • Detail

Analysis and treatment of coking in boiler burner

the 1025 t/h subcritical pressure controlled circulating boiler equipped with 300 MW unit of Laicheng Power Plant adopts American combustion engineering company (CE) technology. The furnace adopts the tangential combustion mode of four corners of a single furnace chamber, which is manufactured by Shanghai Boiler Factory Co., Ltd. and equipped with the direct blowing pulverizing system of double inlet and double outlet steel ball mill BBD4062 manufactured by Shenyang Heavy Machinery Factory. Since the first unit was handed over for trial production in 1999, the operation of the first unit has been stable, and two pulverizing systems have been operated with rated load (three pulverizing systems are designed with boiler BMCR load, and two pulverizing systems with rated load), which has met the design requirements, creating a good result of the first unit's continuous safe operation for 123 days. So far, the whole plant has been in safe production for more than 350 days, with no unplanned shutdown

1 coking phenomenon in the operation of burner

for a period of time, due to the need of peak load regulation, the unit has been operating at a low load with an output of 150 MW for a long time. Due to the lack of experience in the operation of double inlet and double outlet pulverizers, under low load conditions, the operation mode of combustion and pulverization system with double inlet and double outlet of 2 pulverizers and 4-layer burners required by the design and manufacturing instructions was still adopted, and there was no abnormal phenomenon at first. However, after a period of time, during operation, it was found that the pressure of pulverized coal pipes numbered a in the first layer and B and B in the third layer gradually increased by 1 ~ 2KPa, and the temperature in front of the burner ram increased from 50 ℃ to about 100 ℃. It is judged that the burner has coking

2 cause analysis of coking in the burner

preliminary analysis shows that coking in the burner is mainly caused by the local accumulation of pulverized coal in the burner caused by the low primary air speed during low load operation of the unit, and the fine pulverized coal makes the ignition point of pulverized coal entering the furnace close to the burner. In order to further find out the cause, a wind speed measurement was carried out on the pulverized coal outlet pipe of coal mills a and B

the measurement results show that there is indeed a problem of low wind speed in powder tubes a, B and B

3 treatment measures

according to the test and analysis, two coal mills with four layers of burners operate under low load for a long time, and the local powder accumulation caused by the low wind speed of the powder pipe is the main reason for the coking of the burners, but the former is equipped with a microcomputer. Therefore, the following different measures are taken under different working conditions

3.1 when the load is above 200 MW

when the load is above 200 MW, keep two coal mills in and out:

(1) when the coal mills a and B or B and C are running, keep the coal mill B with stable load, and use the coal mill a or C to feed the No. 3 roaster of the 280000 ton potential tapping and reconstruction project of Chalco Shanxi new materials company. After 150 days of oven drying adjustment, keep the primary air volume on each side of the coal mill at 40 ~ 42 T/h

(2) during the operation of coal mills a and C, it is necessary to keep coal mill a with stable load, adjust with coal mill C, and keep the primary air volume on each side of the coal mill at 40 ~ 42 T/h

3.2 when the load is reduced to 200 MW, the load will continue to be reduced. When the load drops to 150 ~ 200 MW, two mills are still in operation, but one coal mill is required to operate in half mill. The specific requirements are as follows:

(1) when the coal mills a and B are in operation, the coal mill B must be kept with stable load, and the primary air volume on each side of the coal mill B must be maintained at 40 ~ 42 T/h. Mill a retains the single inlet and single outlet operation of half mill at A2 side, and adjusts it with mill a to keep the primary air volume at one side of the pulverizer at 40 ~ 42 T/h. Pay attention to monitor and check the inlet temperature of the separator on the non operating side, which should be lower than the bypass air temperature and the outlet temperature should be lower than 75 ℃

(2) when pulverizers B and C are running, it is necessary to keep pulverizer B with stable load and keep the primary air volume at each side of pulverizer B at 40 ~ 42 T/h. Mill C retains the single inlet and single outlet operation of half mill at C1 side, and adjusts it with mill C to maintain the primary air at one side of the pulverizer. Now the oral and written guarantees we give are here, with the quantity of 40 ~ 42 T/h. Pay attention to monitor and check the inlet temperature of the separator on the non operating side, which should be lower than the bypass air temperature and the outlet temperature should be lower than 75 ℃

(3) during the operation of coal mills a and C, the coal mill a must be operated with stable load, and the primary air volume on each side of coal mill a must be maintained at 40 ~ 42 T/h. Mill C retains the single inlet and single outlet operation of half mill at C1 side, and adjusts it with mill C to keep the primary air volume at one side of the pulverizer at 40 ~ 42 T/h. Pay attention to monitor and check that the inlet temperature of the separator on the non operating side should be lower than the bypass air temperature, and the outlet temperature should be lower than 75 ℃

3.3 when the load drops below 150 MW, keep a double inlet and double outlet pulverizer in operation

3.4 during low load operation, if the flame detector flickers or does not light, immediately contact the thermal control personnel to check the flame detector, and check the combustion condition of the burner on site. It is the starting sign of the engineering utilization of modern hydraulic technology. Compare it with the combustion condition of other burners, so as to judge the combustion condition. In case of unstable combustion, oil should be used for combustion support

3.5 during low load operation, the outlet temperature of the pulverizer shall be maintained at 75 ℃, and the pressure of the pulverized coal pipe and the changes of other parameters shall be monitored

by taking the above measures, the problems of unstable combustion of the boiler and coking of the burner during low load operation of the unit have been better solved. (shangyuhua, sunxiangfeng)

Copyright © 2011 JIN SHI