The air preheater cold-end integrated temperature refers to the sum of the flue gas temperature at the air preheater outlet and the air inlet temperature. The flue gas temperature at the air preheater outlet is what we call the exhaust gas temperature, while the sum of the inlet air temperatures is the weighted average of the temperatures of the cold primary and secondary air at the air preheater inlet. According to empirical data, the weighted average of the temperatures of the cold primary and secondary air at the air preheater inlet is approximately 5°C above the ambient temperature. For simple conversion, this can be calculated as the exhaust gas temperature plus the ambient temperature plus 5°C.
The design value for the cold-end integrated temperature of coal-fired units is generally around 140°C, but most power plants currently control this temperature above 160°C.
High cold-end integrated temperature of the air preheater
Because ambient temperature is uncontrollable, if the cold-end integrated temperature of the air preheater is high, it is primarily due to high exhaust gas temperature. High exhaust gas temperature reduces the economic efficiency of coal-fired units and, for units equipped with bag filters, poses a safety threat. Low cold-end temperature of the air preheater
If the cold-end temperature of a coal-fired unit is kept too low, it can directly lead to low-temperature corrosion, ammonium bisulfate (NHHSO) deposition, and ash blockage. The dew point of NHHSO is approximately 120°C, so the cold-end temperature must be kept above this value. Because increasing exhaust gas temperature reduces unit economics, the primary method for increasing the cold-end temperature of the air preheater is to use a heater or hot air recirculation to heat the cold air. Controlling the sulfur content of the incoming coal can also alleviate air preheater blockage.
The air preheater cold-end integrated temperature refers to the sum of the flue gas temperature at the air preheater outlet and the air inlet temperature. The flue gas temperature at the air preheater outlet is what we call the exhaust gas temperature, while the sum of the inlet air temperatures is the weighted average of the temperatures of the cold primary and secondary air at the air preheater inlet. According to empirical data, the weighted average of the temperatures of the cold primary and secondary air at the air preheater inlet is approximately 5°C above the ambient temperature. For simple conversion, this can be calculated as the exhaust gas temperature plus the ambient temperature plus 5°C.
The design value for the cold-end integrated temperature of coal-fired units is generally around 140°C, but most power plants currently control this temperature above 160°C.
High cold-end integrated temperature of the air preheater
Because ambient temperature is uncontrollable, if the cold-end integrated temperature of the air preheater is high, it is primarily due to high exhaust gas temperature. High exhaust gas temperature reduces the economic efficiency of coal-fired units and, for units equipped with bag filters, poses a safety threat. Low cold-end temperature of the air preheater
If the cold-end temperature of a coal-fired unit is kept too low, it can directly lead to low-temperature corrosion, ammonium bisulfate (NHHSO) deposition, and ash blockage. The dew point of NHHSO is approximately 120°C, so the cold-end temperature must be kept above this value. Because increasing exhaust gas temperature reduces unit economics, the primary method for increasing the cold-end temperature of the air preheater is to use a heater or hot air recirculation to heat the cold air. Controlling the sulfur content of the incoming coal can also alleviate air preheater blockage.