Improving Boiler Economy: 7 Major Factors of High Exhaust Gas Temperature In-depth Analysis

August 04, 2023

The exhaust gas temperature of a boiler has a significant impact on the economics of its operation. In fact, every time the exhaust gas temperature increases by 10°C, the corresponding exhaust gas loss will increase by 0.5-0.8%.

There are various reasons for the rise of the exhaust gas temperature, including but not limited to air leakage, the operation status of the pulverizing system, the accumulation of dust in the heating area, and the atmospheric temperature of the surrounding environment. At the same time, the quality of the coal entering the furnace and the measurement error of the temperature measuring point are also important factors. Next, we will discuss the above seven influencing factors in depth to provide a more professional perspective and analysis.

1. Air Leakage Analysis

Air leakage, including furnace air leakage and flue air leakage, is one of the leading factors causing the rise of exhaust gas temperature. Its occurrence is closely related to operation management, equipment maintenance and equipment structural design.

Furnace air leakage mainly refers to air leakage at the furnace top seal, fire viewing hole, manhole door and furnace bottom sealing water tank;

Air leakage from the flue refers to air leakage from the flue at the front and rear of the oxygen meter.

2. Ash analysis of heated area

Dust in the heating area of the boiler will reduce the heat transfer coefficient of the heating surface, reduce the heat absorption of the boiler, reduce the heat release of the flue gas, and increase the smoke temperature at the inlet of the air preheater, resulting in an increase in the exhaust gas temperature; The reduction of the heat transfer area of the preheater will also reduce the heat release of the flue gas and increase the temperature of the exhaust gas.

3.Ambient air temperature analysis

The ambient air temperature during actual operation is higher than the design, the inlet air temperature of the air preheater is high, the heat transfer temperature difference of the air preheater is small, the heat release of the flue gas is small, and the exhaust gas temperature is correspondingly increased, which belongs to the objective environment factor.

4. The temperature of the feed water is too high

The heat transfer temperature difference between the smoke temperature and the water temperature is small, which increases the exhaust gas temperature accordingly.

5. Boiler structure analysis

Unreasonable boiler design, or inadequate thermal insulation measures, may also lead to an increase in exhaust gas temperature.

6. Incomplete combustion

If the mixture of fuel and air is insufficient, or the supply of oxygen is insufficient, it will lead to incomplete combustion, and the heat generated will not be fully utilized, which will increase the exhaust gas temperature.

7. The quality of the fuel into the furnace

The difference in the quality of the fuel entering the furnace and the temperature measurement error may affect the combustion efficiency, which will lead to an increase in the exhaust gas temperature.


The above is EPCB's detailed analysis of the seven key factors of boiler exhaust gas temperature rise. Among these factors, we can improve through effective operation management and maintenance, such as air leakage, dust accumulation on the heating surface of the furnace, and some environmental factors that we cannot directly control but need to adapt to as much as possible, such as ambient air temperature and feed water temperature.

At the same time, we also need to pay attention to the design of the boiler itself, including the structure of the boiler and thermal insulation measures, etc., which may affect the exhaust gas temperature. In addition, we also need to pay attention to the mixing and combustion conditions of fuel and air to ensure the full use of heat.

Hope this in-depth analysis can help you better understand and manage the operation of boilers, so as to improve economic benefits, reduce exhaust loss, and achieve higher energy efficiency and environmental protection standards. These factors will form the basis for optimizing and improving your boiler's operation, so by mastering and understanding them, you will be able to operate more efficiently and economically.

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