In recent years, with the rapid development of iron and steel industry, energy recycling and reducing energy loss has become an important task in the current production and operation of steel companies. With the change of production mode, a large amount of coke oven gas surplus appears, in order to fully digest the coke oven gas surplus, the original method is to mix the coke oven gas directly into the main blast furnace gas network for users. After the actual operation, it is found that, due to the high and coke oven gas mixing amount according to the amount, the change is frequent and the range is large, the fuel calorific value of the furnace is not stable, causing the boiler overpressure, the safety valve frequently jump, not only damage the boiler pressure parts, and the subsequent stable operation of the steam turbine blower, generator has brought adverse effects. In addition, all three blast furnace blowers of Xuangang adopt turbo-blower, and are not equipped with electric towing blower. If the blast furnace gas is interrupted under extreme circumstances, all boilers in line will not be able to provide normal steam for the blower, which seriously threatens the overall production of the company.
Retrofit of burner
The boiler originally had 4 layers of 16 blast furnace gas burners, the first and fourth layers of burners were replaced by coke oven gas burners after the transformation. There were 8 burners in two layers, and the gas pipe, corresponding valve instrument accessories, ignition device, local control box and other accessories were replaced accordingly. The second and third layers of blast furnace gas burners were old.
Modification of heating surface
For coke oven gas calorific value is higher, coke oven gas boiler heating surface need less, the existing boiler heating surface is relatively big, will lead to the following conditions: (1) due to the chamber of a stove or furnace heating surface is too big, lead to a stove or furnace outlet flue gas temperature is reduced, superheater heat decreases, superheater steam temperature is lower than the original, can not reach the rated temperature, especially in low load condition is more serious, need to increase the superheater in the heated area. (2) Due to the large sulfur and water content in coke oven gas, too low exhaust temperature will cause serious low-temperature corrosion to the heating surface of the tail. Therefore, it is necessary to reduce the heating surface of the tail coal economizer and increase the exhaust temperature.
Reconnect the gas line
DN800 main pipe of coke oven gas shall be set up from the main network of the north ring of coke oven gas to boiler No. 5, butterfly valve, blind plate valve and corresponding metering device shall be installed, and branch pipe, four-angle pipeline and regulating valve shall be installed according to the design requirements of burner.
The practical application of converting bf gas boiler to coke oven gas has effectively alleviated the limitation of industrial boilers which use BF gas as the main fuel in the process of production adjustment and realized the effective utilization of coke oven gas. With the increasing competition in the steel market, it is an effective way to reduce cost and increase efficiency for iron and steel enterprises to use gas rationally, reduce external emissions and convert surplus gas into electric energy. The practical application of this technology has a good prospect of promotion.
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