# How to Calculate Boiler Efficiency

October 7, 2020

Fuel combustion produces heat which is transferred to the heat conducting medium in the boiler, and the effect of heat transfer is called boiler efficiency. The thermal efficiency of boiler refers to the ratio of the heat output of boiler to the heat input. The heat input mainly comes from the heat released by the fuel combustion, and sometimes includes the heat generated by external heating fuel and preheating air. Heat output is the amount of heat that is effectively utilized to produce steam. Boiler thermal efficiency is one of the important indexes reflecting boiler energy efficiency. The thermal efficiency of gas fired boiler of ZOZEN Boiler can reach more than 98%. Biomass boiler can reach more than 88%, environmental protection coal boiler can reach more than 82%, and gas heat conduction oil boiler can reach more than 95%.

The ratio of the heat used by the boiler to the total heat released by the fuel to calculate the thermal efficiency is called the direct measurement. Thermal efficiency = effective heat utilization/all heat released by fuel *100%= boiler evaporation * (steam enthalpy – feed water enthalpy)/fuel consumption * fuel low calorific value *100%. This formula does not take into account the influence of steam humidity and gas consumption of blowdown magnitude, so it is only applicable for estimation reference.

Factors Affecting Gas fired Boiler Efficiency

1. Incomplete combustion of gas: Under the condition of good combustion, the heat loss of gas incomplete combustion of gas boiler is small. But under the condition of bad combustion, the heat loss rate of incomplete combustion is very high. During the commissioning of the gas boiler, the commissioning personnel should conduct careful commissioning and testing of various working conditions, so as to achieve the best combustion state of the gas boiler and maintain its high combustion efficiency.
2. Heat loss of smoke exhaust: Heat loss of smoke exhaust is the most important heat loss of gas-fired boiler. High temperature of smoke exhaust leads to lower thermal efficiency of boiler. Therefore, there is a lot of latent heat in the flue gas discharged from the gas boiler, and this part of heat loss can be recovered by contact heat exchange equipment.
3. Heat dissipation loss: heat dissipation loss of boiler room mainly includes heat dissipation loss of boiler and heat dissipation loss of other thermal equipment, soda water pipes, smoke pipes and air ducts within the scope of boiler room. Under normal circumstances, as long as reasonable heat preservation measures, other heat dissipation losses in addition to the boiler heat dissipation loss on the boiler room energy utilization can be ignored.
4. Rehydration heat loss and condensation water heat loss: for gas-fired hot water boilers, the system rehydration will also cause heat loss due to heat network leakage.
5. Heat loss of boiler sewage: for gas-fired hot water boiler, the heat loss of sewage can be ignored due to the small amount of sewage and large water capacity of the system. Due to the high fuel quality and high price of gas steam boiler, enough attention must be paid to the heat loss of sewage discharge.

Wuxi ZOZEN Boiler was established in 1988, has over 30 years of industrial Boiler manufacturing experience, the fuel and gas Boiler, circulating fluidized bed Boiler, the main production chain grate Boiler, biomass Boiler, heat conduction oil Boiler and other 400 kinds of industrial Boiler equipment, widely used in various industries, chemical industry, oil processing and coking, paper making, agricultural food processing, etc.), electricity, thermal field of industry, construction and other industries. The company has a mature pre-sale, sale, after-sales service system, to provide customers with the best quality guarantee.