燃气锅炉不同工况下热效率实测与节能潜力分析*
Measurement of thermal efficiency and energy saving potential analysis for gas-fired boilers under different operation conditions
摘要：
基于北京市某燃气热水供暖锅炉房整个供暖季的全工况跟踪实测数据，分析了燃气锅炉在不同工况下的热效率及其影响因素、节能潜力。结果表明：供暖季锅炉房集中供热调节方式为分阶段改变流量的质调节和质量-流量调节，锅炉房供水温度为80～103 ℃，回水温度为40～53 ℃，燃气锅炉整个供暖季负荷率为45.3%～95.1%，过量空气系数为1.01～1.22，排烟温度为65.4～151 ℃，锅炉低热值热效率为92.1%～96.8%；锅炉热效率随过量空气系数的增大先增大后减小，过量空气系数为1.10时，锅炉热效率最大；锅炉热效率随负荷率的增大而增大，锅炉负荷率大于84%时，锅炉热效率提高较快，锅炉负荷率每增大1%，锅炉热效率增大0.41%～0.55%；锅炉热效率还随回水温度的降低而增大。对锅炉进行排烟余热利用，将排烟温度降到比回水温度高5～10 ℃时，锅炉系统总热效率可提高到105.2%～107.6%，供暖季锅炉热效率可平均提高4.8%～7.5%，单位容量锅炉（0.7 MW）整个供暖季可节约燃气1.03万～1.38 万m3，并相应减少CO2和NOx等的排放。因此，对于在不同负荷率下排烟温度为65～150 ℃的燃气热水锅炉，节能减排潜力可观。
Abstract：
Based on the measurement data of whole heating season of a heating supply gas-fired boiler station in Beijing, analyses the thermal efficiency, its influencing factors as well as the energy saving potential of gas-fired boilers under different operation conditions. The results show that the centralized heating regulation mode of boiler station in heating season can be classified into quality regulation of changing flow in stages and mass-flow regulation mode. The supply water temperature of the boiler is 80 to 103 ℃, return water temperature is 40 to 53 ℃, load rate of gas-fired boiler in heating season is 45.3% to 95.1%, excess air coefficient is 1.01 to 1.22, exhaust gas temperature is 65.4 to 151 ℃, and thermal efficiency of the boiler with low-caloric value is 92.1% to 96.8%. The thermal efficiency rises first and then decreases with the increase of excess air coefficient. When the excess air coefficient is 1.10, the thermal efficiency of the boiler is the highest. The thermal efficiency increases with the increase of the load rate. When the load rate of the boiler is greater than 84%, the thermal efficiency increases rapidly. When the load rate of the boiler increases by 1%, the thermal efficiency increases by 0.41% to 0.55%. The thermal efficiency increases with the decrease of return water temperature. If the waste heat of exhaust gas is recovered in the boiler and the exhaust gas temperature is reduced to 5 to 10 ℃ higher than the return water temperature, the total thermal efficiency can be improved to 105.2% to 107.6%, and the thermal efficiency in heating season can be improved by 4.8% to 7.5% on average. The boiler with unit capacity (0.7 MW) can save gas of 10 300 to 13 800 m3 during the whole heating season, and also reduce emission of CO2 and NOx. Therefore, the potential of energy saving and emission reduction is considerable for the gas-fired boilers under different load rates when exhaust gas temperature is at 65 to 150 ℃.
Keywords:gas-firedboiler,thermalefficiency,loadrate,excessaircoefficient,exhaustgastemperature,energysavingpotential