EBICO News

Methods for improving boiler thermal efficiency
Low pressure industrial boilers have already considered the issue of overheating efficiency when designed by manufacturers, and it is unlikely to save energy by changing equipment or flue gas. Therefore, it is best to start energy-saving from the operation of the boiler (not discussing the method of steam condensate recovery here). According to relevant data investigation, the design thermal efficiency of low-pressure industrial boilers in China is generally between 70-90%, and the actual operating thermal efficiency is generally around 60-80%, some even below 50%. Small low-pressure industrial boilers can fully achieve the design thermal efficiency of boiler manufacturers as long as they are operated and maintained properly.
Boiler management and operation should pay attention to the following points:
1、 Monitor the exhaust temperature of the boiler. The maximum heat loss of a boiler is usually the exhaust loss, so it is important to control the exhaust temperature of the boiler. Generally, the exhaust temperature of coal-fired low-pressure industrial boilers (mainly referring to boilers with less than 10 tons and pressure less than 1.6 MPa, the same below) is 150-180 ℃, and the exhaust temperature of oil fired boilers is 210-240 ℃. Therefore, when the exhaust temperature is too high, the cause should be identified and eliminated in a timely manner. The reasons for the high exhaust temperature of coal-fired boilers include: 1. too high negative pressure in the furnace, 2. short circuit of flue gas, 3. too thick smoke scale on the heating pipeline, 4. too thick scale inside the boiler, etc. The reasons for the high exhaust temperature of oil fired boilers include: 1. poor adjustment of air and oil, which prevents the oil from completely burning to the tail of the chimney and causing secondary combustion, 2. too much smoke ash, which needs to be cleaned in time, 3. short circuit of flue gas, 4. too thick scale, etc
2、 Control the boiler discharge rate. The discharge rate of general industrial boilers is controlled at 5-10%. On the premise of ensuring that the boiler water is qualified (mainly total alkalinity and pH value), the lower the boiler discharge rate, the better. The principle of “frequent discharge, less discharge, and even discharge” should be adhered to for discharge.
3、 Maintain the furnace wall and insulation layer of the boiler. The heat loss of boilers is also a relatively large heat loss. Boiler manufacturers have already considered it thoroughly in manufacturing and design, so there is no need for us to make changes. We just need to maintain it well. The temperature of the outer surface of a general boiler should not exceed 50 ℃. If it is too high, the cause should be identified and eliminated in a timely manner. The insulation layer of the boiler should be kept dry regularly. For coal-fired boilers, it is not allowed to operate under positive pressure for a long time, otherwise it is easy to damage the furnace wall and coal gate.
4、 Adjust the ratio of fuel to air flow to ensure that the fuel burns as completely as possible. Generally, small boilers do not have instruments for air volume testing, so adjustments can only be made based on experience. For oil fired boilers, the flame is yellow white during normal combustion, not glaring, the flame is stable, and there is no obvious visible smoke in the chimney; For coal-fired boilers, the flame is light yellow during normal combustion, there is no obvious smoke in the chimney, the coal slag is basically burned, and the coal particles are as uniform as possible.
5、 There should be a complete boiler water treatment system. A comprehensive boiler water treatment and water quality testing can prevent boiler scaling to the greatest extent possible and provide correct guidance for pollutant discharge, which many small boilers have not achieved and enterprises usually do not attach importance to.