基于半干法NGD脱硫技术的SO2超低排放试验研究
Experimental study on sulfur dioxide ultra-low emission base on semi-dry NGD desulfurization technology
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摘要: 随着环保形势的日益严峻,国家对中小型燃煤工业锅炉的烟气污染物治理也提出了超低排放 要求。 采用半干法烟气脱硫技术是解决中小型燃煤锅炉尾部烟气SO2 污染问题并实现超低排放的有 效途径之一。 作为一种新型半干法烟气脱硫技术,NGD脱硫采用锅炉自生高钙粉煤灰作为脱硫剂, 有效降低了脱硫剂运行成本。 为验证该技术的SO2 超低排放效果和脱硫剂使用经济性,以神东某锅 炉房配套40t/h煤粉锅炉NGD脱硫装置为研究对象开展工业试验,同时考察了装置运行稳定性以及 关键因素对脱硫效果的影响。 试验结果表明,NGD反应器进出差压平均值约1100Pa,未出现曲线急 剧上升或下降的现象,说明装置总体运行稳定性较好。 外加适量Ca(OH)2 后,NGD脱硫装置的SO2 平均排放浓度(9% O2)小于35mg/Nm3,达到超低排放效果。 计算得到外加Ca(OH)2 与反应器入口 SO2 的钙硫摩尔比 n(Ca/S)=0．9,由于主要利用锅炉自生粉煤灰中的活性钙,外加Ca(OH)2 量低于 同类半干法烟气脱硫技术。 研究发现,装置脱硫效率随增湿水量的增加而升高;在测试工况下,锅炉 自生粉煤灰掺混少量Ca(OH)2 后,脱硫率由70%提高到90%以上。Abstract: With the increasingly serious environmental protection situation,ultra-low emission requirements for the treatment of flue gas pollutants from medium and small coal-fired industrial boilers has been put forward by our state.It is one of the effective ways to solve SO_2 pollution in tail flue gas of medium and small coal-fired boilers and achieve ultra-low emission by using Semi-dry flue gas desulfurization( FGD) technology.As a new semi-dry flue gas desulfurization technology,the NGD desulfurization uses high calcium fly ash from boiler as desulfurizer,which effectively reduces the operation cost of desulfurizer.In order to verify the super-low SO_2 emission effect of the technology and the economic use of desulfurizer,a 40 t/h pulverized coal fired boiler NGD desulfurization unit in a Shendong boiler house was taken as the research object to carry out industrial tests,and the operation stability of the device and the influence of key factors on the desulfurization effect were investigated.The experimental results show that the average in and out of the pressure differenceof NGD reactor is about 1 100 Pa,and there is no sharp rise or decrease of curve,which indicates that the overall operation stability of the device is good.After an appropriate amount of calcium hydroxide being added,the average SO_2 emission concentration( 9% O_2) of the NGD desulfurization unit is tested to be less than 35 mg/Nm~3,which achieves ultra-low emission effect.The Ca/S molar ratio n( Ca ∶ S) of the added Ca( OH)_2 and SO_2 at the inlet of the reactor is calculated to be 0.9.As the active calcium is mainly used in the autogenous fly ash of the boiler,the consumption of added Ca( OH)_2 is lower than that of the similar semi dry flue gas desulfurization technology.It is found that the desulfurization efficiency of the plant increases with the increase of the amount of humidified water.Under the test conditions,the desulfurization rate increased from 70% to more than 90% when the sef-generated boiler fly ash mixed with a small amount of Ca( OH)_2.
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