What can be done to improve the thermal efficiency of gas-fired steam boilers?

What can be done to improve the thermal efficiency of gas-fired steam boilers?

The direct effect of improving the thermal efficiency of gas-fired steam boilers is to reduce the operating input cost of the boiler, so it is very important for users who use the boiler. Zhengzhou Fangkuai Boiler Factory summarized some methods that can effectively improve the thermal efficiency of gas-fired steam boilers, let's take a look.

1. Reduce the exhaust temperature
       At present, the high exhaust gas temperature of industrial boilers in my country is one of the main reasons for the low thermal efficiency of boilers. When the exhaust gas temperature of small boilers drops by 15-20 degrees Celsius, and for large boilers by 15 degrees Celsius, the thermal efficiency of natural gas boilers increases by 1%. Therefore, it is necessary to try to recover the waste heat of the flue gas to lower the exhaust gas temperature, reduce the exhaust heat loss q2, and save fuel.

2. Feed water softening treatment and condensate recovery
       Boiler feed water softening treatment and condensate recovery are also measures to improve boiler thermal efficiency. The raw water contains various impurities and their fouling substances. If the water quality is not well treated, the boiler will foul. The thermal conductivity of scale is very low, so once the heating surface is scaled, the output of the natural gas boiler will decrease due to the increase of thermal resistance, coal consumption will increase, and the thermal efficiency of the boiler will decrease.

3. Keep the boiler running under rated load
       When the natural gas boiler is overloaded, because the amount of fuel must be added, the coal seam must be thickened, the speed of the grate will increase, and the air supply must also be increased to meet the demand for load increase. The thickening of the coal seam and the acceleration of the grate speed will cause the incomplete combustion of the solids to lose their addition. Because of the addition of the air supply, the flue gas stays in the furnace for a short time. Some combustible gases are discharged with the flue gas before they are burnt. The heat loss of gas incomplete combustion increases.

At the same time, when the operation is overloaded, the temperature in the furnace increases due to the thickening of the coal seam, and the temperature of the exhaust gas increases accordingly, which increases the heat loss of the exhaust gas. When the boiler is operating at low load, the amount of coal burned is reduced, and the temperature in the furnace drops, which makes the combustion conditions worse, and the incomplete combustion loses q3 and q4. When the boiler load is only 50%, it is difficult to maintain stable combustion in the furnace because the temperature in the furnace drops significantly. The heat loss is relatively increased during low-load operation, so boiler overload or low-load operation will cause the thermal efficiency of the boiler to decrease.

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