What To Do When Boiler Tube Overheat

Boiler tube refers to steel with two ends open and hollow sections, and its length is relatively large compared to the surrounding area. It can generally be divided into seamless steel pipe and welded steel pipe. Boiler tubes can be used for pipelines, thermal equipment, mechanical industry, petroleum geological exploration, containers, chemical industry and special purposes.

‌Boiler tube overheating‌ refers to the phenomenon that the metal tube wall temperature of the heating surface or the outlet steam temperature exceeds its rated value during the operation of the boiler. This phenomenon may cause unstable boiler operation and even cause safety accidents and other hazards.

Causes of overheating

‌1. Insufficient drainage and exhaust volume at startup: During the boiler startup process, if the drainage and exhaust volume are insufficient and the load increase speed is too fast, the superheater heating surface will be insufficiently cooled, causing the tube wall metal to overheat.

‌2. Improper use of cooling water adjustment: Improper adjustment of cooling water will lead to inaccurate control of the superheater tube wall temperature. If the cooling water is used improperly, the tube wall temperature will be too high.

‌3. Poor quality of steam and water‌: During boiler operation, if the chemical treatment of boiler water is improper or chemical supervision is not strict, it will cause scaling in the superheater tube, affecting the heat transfer effect, thus causing overheating of the tube wall‌.

‌4. Improper combustion control‌: Improper combustion control will lead to problems such as flame upward movement, high flue gas temperature at the furnace outlet, and large thermal load deviation, which will cause overheating of the heating surface‌.

‌5. Insufficient air volume‌: Insufficient air volume will lead to incomplete combustion, secondary combustion in the flue, and then overheating of the heating surface‌.

‌6. ‌Local ash and coking in the flue‌: Local ash and coking in the flue will hinder the flow of flue gas, resulting in local overheating of the heating surface‌.

‌7. Unreasonable design of the heating surface‌: Unreasonable design of the heating surface, such as improper design of tube row spacing, flue gas flow rate, etc., will lead to local overheating‌.

8. Temperature distortion of wall temperature measuring point‌: Temperature distortion of wall temperature measuring point will affect the monitoring and control of tube wall temperature, thus causing overheating‌.

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Hazards of overheating

‌1. Equipment damage: High temperature can cause the performance of metal materials to deteriorate and even cause equipment damage.

‌2. Safety accidents: Long-term overheating will increase the risk of boiler explosion.

‌3. Reduced operating efficiency: Overheating will affect the heat exchange efficiency of the boiler, resulting in increased operating costs.

Preventive measures

‌1. Strictly control the startup and load increase speed of the boiler: During the startup of the boiler, the operation should be strictly carried out in accordance with the temperature increase and pressure increase curve, and the combustion should be reasonably adjusted to control the load increase speed to avoid thermal deviation.

‌2. Reasonable use of cooling water: During operation, the cooling water at each level should be reasonably used to reduce the steam temperature at the front end of the superheater as much as possible, strengthen the heat absorption capacity of the pipe, and avoid overheating of the pipe wall.

‌3. Strengthen water quality management: Regularly check and adjust the water quality to ensure that the boiler water quality meets the requirements and avoid scaling in the pipe.

‌4. Optimize combustion control: By optimizing combustion control, ensure flame stability, avoid flame upward movement and excessive flue gas temperature at the furnace outlet.

‌5. Clean the flue regularly: Clean the ash and coke in the flue regularly, keep the flue unobstructed, and reduce local overheating.

‌6. Improve the design of the heating surface: Adjust the design of the heating surface according to the actual situation to ensure that the flue gas flow rate and the spacing between the tubes are reasonable. ‌

7. Check the wall temperature measurement points regularly: Check the accuracy of the wall temperature measurement points regularly to ensure the authenticity of the monitoring data. ‌

Summary

‌In order to ensure the safe, efficient and stable operation of the boiler, we need to strengthen the daily maintenance of the boiler, improve the boiler combustion technology, and improve the water quality and water flow. Only in this way can we ensure the normal operation of the boiler and ensure production safety.