[Haichuan Experience Sharing] Analyzing the impacts of water wall overheating and corresponding measures to ensure the safe and efficient operation of boilers

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During the daily operation of boilers, the issue of excessive temperature in the water wall poses a significant challenge that must be overcome. This article will explore in depth the impacts of excessive temperature in the water wall, as well as how to take scientific and effective measures to prevent it, thereby ensuring the safe and efficient operation of the boiler. I. Over-temperature of water wall: Definition and current status. As one of the key components of coal-fired boilers, the water wall serves multiple functions, including absorbing heat from the furnace, protecting the furnace structure, and preventing slag formation. It transfers the high temperature heat inside the furnace to steam through a water circulation mechanism, thereby achieving energy conversion. However, during actual operation, due to various factors such as fuel quality, combustion adjustment, and water circulation efficiency, the water wall often faces the severe challenge of overheating. Over-temperature refers to the situation where the temperature of the water wall exceeds the designed value; this not only affects the operational efficiency of the boiler but also poses a serious threat to its safe operation. II. Effects of excessive temperature on the water wall: A multi-dimensional analysis 1. Thinning of the tube wall and reduced pressure-bearing capacity Excessive temperature causes creep in the material forming the water wall tubes; over time, the thickness of these tubes gradually decreases, leading to a significant reduction in their pressure-bearing capacity. This change acts like a chronic poison, silently eroding the safety safeguards of the boiler. 2. Thermal stress increases, raising the risk of tube rupture. Overheating exacerbates the temperature difference inside and outside the tube wall, generating significant thermal stress. When thermal stress exceeds the material’s tolerance limit, tube rupture accidents are imminent, causing not only equipment damage but also potential casualties, with consequences that are unimaginable. 3. Increased slag formation in the furnace, along with accelerated wear and corrosion. Over-temperature conditions further exacerbate slag formation within the furnace; this slag not only hinders the proper transfer of heat but also increases the wear and corrosion of the water wall, thereby reducing the equipment’s service life. 4. It affects boiler efficiency and increases operating costs. Overheating of the water wall reduces heat transfer efficiency, leading to a decrease in the overall efficiency of the boiler, increased fuel consumption, and rising operating costs. For modern industries striving for high efficiency and energy conservation, this is undoubtedly a heavy burden. III. Analysis of the reasons for overheating of the water wall 1. Unstable fuel quality: Quality factors such as the chemical composition, particle size distribution, and calorific value of coal directly affect the stability and efficiency of the combustion process. Coal with a high sulfur content and high ash content tends to cause incomplete combustion, leading to greater temperature variations inside the furnace, which in turn exacerbates overheating of the water wall. 2. Improper combustion adjustment – uneven air distribution, inadequate control of coal powder particle size, or unreasonable burner arrangement can all lead to the flame scouring the water-cooled wall, resulting in localized overheating. 3. Low water circulation efficiency: Issues such as pipe blockages and pump failures lead to poor water circulation within the water wall, hindering heat transfer and serving as another major cause of overheating. 4. Challenges of deep peak shaving During deep peak shaving, the rapid drop in furnace temperature, combined with the relative lag in the rate of temperature decline of the water wall, creates a significant temperature gradient, making certain areas of the water wall more prone to overheating.