关键词: 加热炉, 排烟热量损失, 炉体散热损失, 热效率, 过剩空气系数, 燃料组分, 辐射传热系数, 炉外壁温度

Abstract:

Fired heater efficiency can be improved by decreasing the stack heat loss and reducing the setting heat losses. Compare the calculation results of two fired heaters with the same heat duty. When stack temperature is 80 ℃, the stack heat loss accounts for 3% of total heat release. If the proportion of stack heat loss is reduced to 2%, the outlet temperature of flue gas will be close to the dew point temperature of the air, a large amount of water of flue gas will condense, it is impossible to avoid problems such as dew-point corrosion. When the design temperature of the outside casing of fired heater is 80 ℃, the total heat dissipation of the system may be more than 3% of total heat release, with the heat dissipation of waste heat recovery system accounting for more than 1%. When the ambient wind velocity is 2 m/s, the proportion of the heat dissipation will increase by 0.3 percentage points. When the design temperature of the outside casing is 65 ℃, the total heat dissipation of the system may be 2.5% of total heat release, with the heat dissipation of waste heat recovery system accounting for about 1%. When the heat intensity of the fired heater is higher, the outside casing of the fired heater will be smaller, the heat dissipation will be smaller, and the actual operating efficiency of the fired heater will be higher.

Key words: fired heater, stack heat loss, setting heat losses, heat efficiency, excess air coefficient, fuel composition, radiant heat transfer coefficient, furnace outside casing temperature