摘要
我国工业锅炉年耗煤4亿t,每年向大气排放600万t SO_2、800万t烟尘,是我国大气污染的重要来源。开展燃煤工业锅炉大气污染物排放特征和节能减排研究,对我国未来大气污染控制和能源、环境与社会发展的综合决策具有重要意义。
现场测试结果表明,燃煤工业锅炉气态污染物TSP、SO_2、NO_X、CO的排放水平分别为283～350 mg/m~3、914.6～1245.7 mg/m~3、64.2～136.6mg/m~3、109.9～890 mg/m~3。TSP、SO_2、NO_X、CO的排放因子分别为3.849～20.38 g/kg、16.83～54.01 g/kg、1.441～3.791 g/kg、1.509～52.56 g/kg。测试锅炉二价汞、元素汞和颗粒汞的排放水平分别为0.3～5.7μg/m~3、1.5～3.8μg/m~3、0.008～0.023μg/m~3。湿式除尘脱硫设施对TSP和SO_2、的去除效率分别为54.2～73.8%、13.0～32.6%,去除效率低,燃煤工业锅炉污染物超标严重。
沈阳工程技术处采暖期内单位面积耗标煤量为33.5kg/m~2,而沈阳市内仅为30 kg/m~2,通过能耗对比,发现燃煤工业锅炉节能潜力较大。通过分层燃烧技术改造、减少锅炉内部阻力两项节能技术措施和湿式除尘废水回用和旋流板塔双碱法脱硫两项减排技术措施的实施,节煤900 t,节电20万kWh,TSP排放浓度从348mg/m~3降低到176mg/m~3,SO_2排放浓度从1274mg/m~3降低到815mg/m~3,提高了锅炉运行效率,减少污染物排放。
通过提高锅炉操作技能和管理水平、强化用煤管理、强化水质管理、及时调整锅炉燃烧、强化除尘脱硫装置、及时清除受热面积灰等管理措施,进一步提高了锅炉效率,节煤200 t,降低了燃煤消耗和污染物排放。
通过经济效益和环境效益两方面对沈阳工程技术处燃煤工业锅炉采取措施后节能减排效益进行了分析。经济效益中节能项目需要投资49万元,节能效益为76.8万元,投资回收期为0.638年。环境治理项目需要投资216万元,环境效益为40万元,投资回收期为5.4年。以沈阳市为例进行了外延分析,计算表明,如果采取节能措施,沈阳市每年可以节约燃煤32.67万t,显著降低运行成本,减少污染物排放。
Industrial boilers, which consume 400 million tons of coal and emit 6 million tons of SO_2 and 8 million tons of PM annually, are one of the most important sources of air pollution in China. Study on air pollutant emissions and energy saving measures of coal-fired industrial boilers are of great significance to the policy-making of air pollution control and the development of energy, environment and society. Field tests showed that the emission concentrations of TSP, SO_2, NO_x, and CO from coal-fired industrial boilers were 283-350 mg/m~3, 914.6-1245.7 mg/m~3, 64.2-136.6 mg/m~3, and 109.9-890 mg/m~3, respectively. The emission factors of TSP, SO_2, NO_x, and CO were 3.849～20.3 8g/kg, 16.83～54.01 g/kg, 1.441～3.791 g/kg, and 1.509~52.56 g/kg, respectively. The emission concentrations of Hg~(2+), Hg0 and Hgp for the tested boilers were 0.3-5.7μg/m~3, 1.5-3.8μg/m~3, and 0.008-0.023μg/m~3, respectively. The removal efficiencies of wet scrubber for TSP and SO_2 were respectively 54.2-73.8% and 13-32.6%. Due to the low removal efficiencies, the air pollution from coal-fired industrial boilers was serious.
The coal consumption rate of Shenyang Department of Engineering and Technology during the heating season was 33.5 kg/m2, higher than that of Shenyang city (30 kg/m2). There was large energy saving potential from coal-fired industrial boilers. Through the boiler arch reconstruction, layered combustion technology, internal resistance reduction, wastewater reuse and swirling plate double alkali desulfurization, 900 tons of coal and 2×105 kWh of electricity were saved, and the emission concentrations of TSP and SO_2 were reduced from348 mg/m~3 to 176 mg/m~3 and from 1274 mg/m~3 to 815 mg/m~3 respectively
The measures including improvement of operation skills and management, enhancement of coal use management, enhancement of water quality management, adjustment of combustion, clearing the heating surface dust, heat loss reduction, and pollution emission control were implemented to improve the boiler’s efficiency and save 200 tons of coal. The pollutant emissions were also reduced. The economic and environmental benefits of measures taken by Shenyang Department of Engineering and Technology were analyzed to indicate the energy saving and pollution reduction of coal-fired industrial boilers. The economic investment of energy efficiency projects was 0.49 million RMB, the benefit of energy saving was 0.768 thousand RMB per year, and the investment recovery period was 0.638 year. The environmental investment was 2.16 million RMB in the project, the environmental benefit was 0.4 million RMB per year, and the payback period was 5.4 years. The extension analysis indicated that with these energy-saving measures, annually 0.3267 million tons of coal would be saved in Shenyang, both the operating costs and pollutant emissions would be significantly reduced.
引文
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