Daily Question (January 13)

Air leakage from the air preheater increases the power consumption of the supply and exhaust fans; in severe cases, due to limited fan output, the boiler is forced to operate at reduced capacity. Air leakage increases the heat loss due to smoke exhaust, reducing the thermal efficiency of the boiler. Air leakage also reduces the temperature of the hot air, leading to corrosion and ash deposition in the lower temperature sections of the heated surfaces. For air leakage in the high-temperature section of tubular air preheaters with a two-stage cross arrangement of air preheaters and economizers, it also leads to an increase in flue gas volume, thereby accelerating wear on the low-temperature economizers

Air leakage from the air preheater increases the power consumption of the supply and exhaust fans; in severe cases, due to limited fan output, the boiler is forced to operate at reduced capacity. Air leakage increases the heat loss due to smoke exhaust, reducing the thermal efficiency of the boiler. Air leakage also reduces the temperature of the hot air, leading to corrosion and ash deposition in the lower temperature sections of the heated surfaces. For air leakage in the high-temperature section of a tubular air preheater with a two-stage cross arrangement of air preheaters and economizers, it also leads to an increase in flue gas volume, thereby accelerating wear on the low-temperature economizer.

A high air leakage rate in air preheaters is a fatal flaw of such equipment. Air leakage from the air preheater can cause changes in the thermal conditions of the boiler. The main mechanism by which excessive air leakage leads to overheating in the primary superheater is as follows: as the load increases, the pressure difference between the air side and the flue gas side rises, resulting in an increase in air leakage. This results in insufficient air flow entering the furnace, causing the flame to lengthen and shift backward, thereby deteriorating the combustion conditions. Changes occur in radiation and convection heat transfer; the heat absorption by the water wall decreases, while the heat transfer in the convection section of the superheater increases, leading to an increase in the temperature of the steam in the primary superheater. In addition, the other two hazards of excessive air leakage are as follows: ① It affects the economic efficiency of boiler operation. On the one hand, it increases the heat loss due to smoke exhaust, thereby reducing the thermal efficiency of the boiler ； On the other hand, it increases the power consumption of the fan. Through calculation, for every increase of 0.1 in the air leakage coefficient. 0.2 will reduce the net efficiency of the boiler by 0.2% to 0.5%. ②Accelerates corrosion at the cold end of the air preheater. The introduction of air into the flue gas causes a false decrease in the flue gas temperature, and this drop in temperature in turn leads to a reduction in the wall temperature of the cold-side heating surfaces, accelerating the process of low-temperature corrosion.

Air leakage from the air preheater increases the power consumption of the supply and exhaust fans; in severe cases, due to limited fan output, the boiler is forced to operate at reduced capacity. Air leakage increases the heat loss due to smoke exhaust, reducing the thermal efficiency of the boiler. Air leakage also reduces the temperature of the hot air, leading to corrosion and ash deposition in the lower temperature sections of the heated surfaces. For air leakage in the high-temperature section of a tubular air preheater with a two-stage cross arrangement of air preheaters and economizers, it also leads to an increase in flue gas volume, thereby accelerating wear on the low-temperature economizer.

Air leakage from the air preheater increases the power consumption of the supply and exhaust fans; in severe cases, due to limited fan output, the boiler is forced to operate at reduced capacity. Air leakage increases the heat loss due to smoke exhaust, reducing the thermal efficiency of the boiler. Air leakage also reduces the temperature of the hot air, leading to corrosion and ash deposition in the lower temperature sections of the heated surfaces. For air leakage in the high-temperature section of a tubular air preheater with a two-stage cross arrangement of air preheaters and economizers, it also leads to an increase in flue gas volume, thereby accelerating wear on the low-temperature economizer.

Air leakage from the air preheater increases the power consumption of the supply and exhaust fans; in severe cases, due to limited fan output, the boiler is forced to operate at reduced capacity. Air leakage increases the heat loss due to smoke exhaust, reducing the thermal efficiency of the boiler. Air leakage also reduces the temperature of the hot air, leading to corrosion and ash deposition in the lower temperature sections of the heated surfaces. For air leakage in the high-temperature section of a tubular air preheater with a two-stage cross arrangement of air preheaters and economizers, it also leads to an increase in flue gas volume, thereby accelerating wear on the low-temperature economizer.

Air leakage from the air preheater increases the power consumption of the supply and exhaust fans; in severe cases, due to limited fan output, the boiler is forced to operate at reduced capacity. Air leakage increases the heat loss due to smoke exhaust, reducing the thermal efficiency of the boiler. Air leakage also reduces the temperature of the hot air, leading to corrosion and ash deposition in the lower temperature sections of the heated surfaces. For air leakage in the high-temperature section of a tubular air preheater with a two-stage cross arrangement of air preheaters and economizers, it also leads to an increase in flue gas volume, thereby accelerating wear on the low-temperature economizer.

When the tubes of the air preheater wear out and cause air leakage, it creates a direct short circuit between the forced air and the exhaust air; with positive pressure on one side and negative pressure on the other, this results in a significant amount of exhaust air being diverted uselessly. Thus causing positive-pressure combustion in the boiler.

Air leakage from the air preheater increases the power consumption of the supply and exhaust fans; in severe cases, due to limited fan output, the boiler is forced to operate at reduced capacity. Air leakage increases the heat loss due to smoke exhaust, reducing the thermal efficiency of the boiler. Air leakage also reduces the temperature of the hot air, leading to corrosion and ash deposition in the lower temperature sections of the heated surfaces. For air leakage in the high-temperature section of a tubular air preheater with a two-stage cross arrangement of air preheaters and economizers, it also leads to an increase in flue gas volume, thereby accelerating wear on the low-temperature economizer.

Air leakage from the air preheater increases the power consumption of the supply and exhaust fans; in severe cases, due to limited fan output, the boiler is forced to operate at reduced capacity. Air leakage increases the heat loss due to smoke exhaust, reducing the thermal efficiency of the boiler. Air leakage also reduces the temperature of the hot air, leading to corrosion and ash deposition in the lower temperature sections of the heated surfaces. For air leakage in the high-temperature section of a tubular air preheater with a two-stage cross arrangement of air preheaters and economizers, it also leads to an increase in flue gas volume, thereby accelerating wear on the low-temperature economizer.