Sulfur Recovery Daily Question 2019.1.13
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What is boiler scaling? What are the hazards of scaling on boilers? Answer: When the boiler feed water is of poor quality, especially when it contains hard substances that have not been properly treated, solid deposits with very poor thermal conductivity form on the heating surfaces where the boiler comes into contact with water. This phenomenon is known as scaling, and these solid deposits are called scale. Since the thermal conductivity of scale is several hundred times lower than that of metal, its formation poses a significant threat to the operation of boilers. For example: it can cause localized overheating of the metal, leading to deformation and subsequent issues such as bulging or tube rupture, which affect the safe operation of the boiler ； Block pipes and disrupt the water circulation ； It affects heat transfer, reduces the boiler’s evaporation capacity, and wastes fuel ； It causes under-scale corrosion and shortens the service life of the boiler.
The deposition of salt on heated surfaces is called scaling. Strictly speaking, scale is further divided into water scale and salt scale. The so-called scale refers to deposits that precipitate directly from solutions and adhere to metal surfaces, such as the scaling inside the heating surfaces of boilers ； Salt scale refers to the salts contained in boiler steam, which precipitate and form solid deposits in thermal equipment, such as inside superheater tubes and in the flow-related parts of turbines. The main hazards of scaling on the boiler’s heating surfaces are: (1) Due to the high thermal resistance of the scale, the heat transfer efficiency of the heating surfaces is reduced, which leads to an increase in the boiler’s exhaust temperature and a decrease in its thermal efficiency. (2) It raises the temperature of the metal wall of the heated surface; in severe cases, it can cause bulging, deformation of the pressure-bearing components, and tube explosion due to overheating. (3) Scaling inside the pipes reduces the effective flow cross-sectional area, increases the flow resistance of the fluid, and hinders the proper operation of the water circulation. Some of the detached scale deposits can also cause local blockages or poor flow. (4) These three hazards ultimately lead to a decrease in the boiler’s output, a shortened service life, and a significant deterioration in its economic efficiency.
When the boiler feed water is of poor quality, especially when it contains hard substances that have not been properly treated, solid deposits with very poor thermal conductivity form on the heating surfaces where the boiler comes into contact with water. This phenomenon is known as scaling, and such deposits are what are called scale. The hazard is: blockage of pipes and disruption of water circulation. It affects heat transfer, reduces steam production, and wastes fuel. Underscale corrosion occurs, shortening the boiler’s service life.
When the boiler feed water is of poor quality, especially when it contains hard substances that have not been properly treated, solid deposits with very poor thermal conductivity form on the heating surfaces where the boiler comes into contact with water. This phenomenon is known as scaling, and such deposits are what are called scale. The hazard is: blockage of pipes and disruption of water circulation. It affects heat transfer, reduces steam production, and wastes fuel. Underscale corrosion occurs, shortening the boiler’s service life.
The deposition of salt on heated surfaces is called scaling. Strictly speaking, scale is further divided into water scale and salt scale. The so-called scale refers to deposits that precipitate directly from solutions and adhere to metal surfaces, such as the scaling inside the heating surfaces of boilers ； Salt scale refers to the salts contained in boiler steam, which precipitate and form solid deposits in thermal equipment, such as inside superheater tubes and in the flow-related parts of turbines. The main hazards of scaling on the boiler’s heating surfaces are: (1) Due to the high thermal resistance of the scale, the heat transfer efficiency of the heating surfaces is reduced, which leads to an increase in the boiler’s exhaust temperature and a decrease in its thermal efficiency. (2) It raises the temperature of the metal wall of the heated surface; in severe cases, it can cause bulging, deformation of the pressure-bearing components, and tube explosion due to overheating. (3) Scaling inside the pipes reduces the effective flow cross-sectional area, increases the flow resistance of the fluid, and hinders the proper operation of the water circulation. Some of the detached scale deposits can also cause local blockages or poor flow. (4) These three hazards ultimately lead to a decrease in the boiler’s output, a shortened service life, and a significant deterioration in its economic efficiency.
When the boiler feed water is of poor quality, especially when it contains hard substances that have not been properly treated, hard solid deposits with poor thermal conductivity form on the heating surfaces where the boiler comes into contact with water. This phenomenon is known as scaling, and these solid deposits are called scale. Since the thermal conductivity of scale is several hundred times lower than that of metal, its formation poses a significant threat to the operation of boilers. For example: it can cause localized overheating of the metal, leading to deformation and subsequent issues such as bulging or tube rupture, which affect the safe operation of the boiler ； Block pipes and disrupt the water circulation ； It affects heat transfer, reduces the boiler’s evaporation capacity, and wastes fuel ； It causes under-scale corrosion and shortens the service life of the boiler.
When the boiler feed water is of poor quality, especially when it contains hard substances that have not been properly treated, solid deposits with very poor thermal conductivity form on the heating surfaces where the boiler comes into contact with water. This phenomenon is known as scaling, and such deposits are what are called scale. The hazard is: blockage of pipes and disruption of water circulation. It affects heat transfer, reduces steam production, and wastes fuel. Underscale corrosion occurs, shortening the boiler’s service life.
This leads to a decrease in the boiler’s output, a shortened service life, and a significant deterioration in its economic efficiency
Calcium and magnesium ions in water form calcium carbonate and magnesium carbonate, which adhere to the inner walls of pipes, causing scaling. Hazards of scaling: under-scale corrosion ； Barrier heat transfer ； In severe cases, tube rupture occurs.
The deposition of salt on heated surfaces is called scaling. Strictly speaking, scale is further divided into water scale and salt scale. The so-called scale refers to deposits that precipitate directly from solutions and adhere to metal surfaces, such as the scaling inside the heating surfaces of boilers ； Salt scale refers to the salts contained in boiler steam, which precipitate and form solid deposits in thermal equipment, such as inside superheater tubes and in the flow-related parts of turbines. The main hazards of scaling on the boiler’s heating surfaces are: (1) Due to the high thermal resistance of the scale, the heat transfer efficiency of the heating surfaces is reduced, which leads to an increase in the boiler’s exhaust temperature and a decrease in its thermal efficiency. (2) It raises the temperature of the metal wall of the heated surface; in severe cases, it can cause bulging, deformation of the pressure-bearing components, and tube explosion due to overheating. (3) Scaling inside the pipes reduces the effective flow cross-sectional area, increases the flow resistance of the fluid, and hinders the proper operation of the water circulation. Some of the detached scale deposits can also cause local blockages or poor flow. (4) These three hazards ultimately lead to a decrease in the boiler’s output, a shortened service life, and a significant deterioration in its economic efficiency.
Deposition of Ca and Mg ions affects heat transfer, leading to localized high temperatures