湿法脱硫中间产物亚硫酸钙的氧化特性

发布时间：2018-06-21 14:18

本文选题：湿法脱硫 + CaSO_3　；参考：《华北电力大学(北京)》2017年硕士论文

【摘要】：为满足日益严苛的排放标准,需要进一步研究燃煤电厂SO_2脱除技术。湿法脱硫技术应用广泛,但仍存在一些问题。其中石灰石石膏法的中间产物亚硫酸钙(CaSO_3)氧化不足,则不能形成足够的石膏晶种使石膏晶体迅速增长,将造成石膏脱水困难,是导致设备结垢的原因之一,因此需要选取合适的添加剂促进氧化。本论文采用鼓泡床反应装置,鼓泡反应器容积为2.4L。主要研究了成品CaSO_3的氧化过程、SO_2脱除过程中间产物CaSO_3的氧化特性。其中CaSO_3的氧化实验分别在无添加剂、加入不同种类添加剂条件下进行;SO_2脱除过程中CaSO_3氧化率的实验则模拟石灰石-石膏法脱硫过程,研究SO_2吸收过程中间产物CaSO_3的氧化率等问题。在CaSO_3的氧化实验中,探究了CaSO_3的宏观反应特性,得知亚硫酸根(SO_3~(2-))氧化速率对O_2浓度的反应级数为0.76;初始pH值越低则反应速率越快。加入适当添加剂能明显加快反应进程,二价锰盐、三价铁盐、二价镁盐、二价铜盐和不同类型锅炉飞灰都能加快CaSO_3的氧化速率,其中二价锰盐促进氧化效果最好,适当的浓度下可以将氧化速率提高至二倍左右;三价铁盐促进效果明显,而二价铁盐在一定浓度时会对氧化过程起抑制作用。加入某些物质会对氧化过程起阻碍作用,阻碍氧化的效果硬脂酸钠腐植酸钠硫代硫酸钠,其中腐植酸钠阻止CaSO_3氧化的效果约为硬脂酸钠的6倍;Na_2S2O_3对CaSO_3有很强的阻止氧化效果,当加入质量为0.3g时,氧化速率降为原来的3%左右。不同电厂飞灰对氧化过程都有促进作用,但效果相差不大,用XRF(X射线荧光光谱分析)测得其中物质成分,但催化机理需进一步研究。在模拟石灰石-石膏法脱硫实验中,探究了O_2浓度、MnCl2和Na2S2O_3对脱硫中间产物CaSO_3氧化率的影响。在该实验装置中,O_2浓度大于5%时,脱硫生成的CaSO_3能被全部氧化,O_2浓度为3%时,反应前100min的氧化率约为84.9%;加入MnCl_2可提高CaSO_4在脱硫产物中的比率,加入量大于0.06g/L时,前100min脱硫产生的CaSO_3可被全部氧化;加入量大于0.04g/L时,前100min CaSO_3氧化率约为95.2%。Na_2S2O_3加入浓度为0.05g/L时,反应前100min生成的CaSO_3被氧化的比率约为44.2%,浓度增大为0.15g/L时,反应前100min生成的CaSO_3氧化率降至11.2%,即石灰石浆液吸收的SO_2中接近90%都以CaSO_3的形式存在,极大的阻碍了CaSO_3的氧化过程。
[Abstract]:In order to meet the increasingly stringent emission standards, further research is needed on SOS _ 2 removal technology in coal-fired power plants. Wet desulfurization technology is widely used, but there are still some problems. If calcium sulfite, the intermediate product of limestone gypsum method, is not oxidized enough, the gypsum crystal can not be formed enough to make the gypsum crystal grow rapidly, which will lead to the difficulty of dehydration of gypsum, which is one of the reasons leading to the scaling of the equipment. Therefore, it is necessary to select suitable additives to promote oxidation. In this paper, a bubbling bed reactor was used and the volume of the bubbling reactor was 2.4 L. The oxidation characteristics of caso _ 3, an intermediate product in the process of so _ 2 removal, were studied in this paper. The oxidation experiments of CaSO3 were carried out under the condition of adding different kinds of additives, and the oxidation rate of CaSO3 was simulated by limestone gypsum desulphurization process. The oxidation rate of CaSOS _ 3, an intermediate product of so _ 2 absorption process, was studied. In the oxidation experiment of CaSO3, the macroscopic reaction characteristics of CaSO3 were investigated. It was found that the reaction order of the oxidation rate on the concentration of O _ 2 was 0.76; the lower the initial pH value, the faster the reaction rate. The addition of appropriate additives can obviously speed up the reaction process. The oxidation rate of CaSO3 can be accelerated by the addition of manganese divalent salt, ferric salt, magnesium salt, copper salt and fly ash of different types of boilers, among which the oxidation rate of CaSO3 is the best. The oxidation rate can be increased to about two times at proper concentration, and the effect of trivalent iron salt is obvious, while the divalent iron salt can inhibit the oxidation process at a certain concentration. The effect of sodium stearate sodium humate sodium thiosulfate on the oxidation of CaSO3 is about six times that of sodium stearate, and the effect of sodium humate on preventing the oxidation of CaSO3 is about six times that of sodium stearate, and the effect of sodium stearate sodium humic acid sodium humate sodium thiosulfate on the oxidation of CaSO3 is about six times that of sodium stearate. When the mass was 0.3 g, the oxidation rate decreased to about 3%. The fly ash from different power plants can promote the oxidation process, but the effect is not different. The composition of the fly ash is determined by XRF X ray fluorescence spectrometry, but the catalytic mechanism needs further study. In the simulated Limestone-gypsum desulfurization experiment, the effects of the concentration of O _ 2, MnCl _ 2 and Na _ 2S _ 2O _ 3 on the oxidation rate of CaSO3, an intermediate product of desulfurization, were investigated. In this experimental device, when the concentration of O _ 2O _ 2 is greater than 5 and the number of CaSO3 produced by desulphurization is 3, the oxidation rate of 100min before reaction is about 84.9.The addition of MnCl _ 2 can increase the ratio of CaSO4 in desulphurized products, when the amount of CaSO3 added is more than 0.06g / L, CaSO3 produced by pre-100min desulphurization can be completely oxidized; when the amount of CaSO3 added is greater than 0.04g / L, the oxidation rate of 100min CaSO3 is about 95.2g / L. When the concentration is 0.05g / L, the ratio of CaSO3 produced by 100min before reaction is about 44.2 g / L, and when the concentration increases to 0.15g / L, The oxidation rate of CaSO3 produced by 100min before the reaction decreases to 11.2%, that is, nearly 90% of the SO2 absorbed by limestone slurry exists in the form of CaSO3, which greatly hinders the oxidation process of CaSO3.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ132.32

【参考文献】