【作者】 黄辉；

【导师】 邱朋华；

【作者基本信息】 哈尔滨工业大学 ， 热能工程， 2010， 硕士

【摘要】 煤炭燃烧是我国氮氧化物（NO_x）、硫氧化物（SO₂）的主要来源之一,其中火电行业NO_x排放量约占全国总NO_x排放量的35%⁴0%。随着全球环境问题的日益严峻,对氮氧化物（NO_x）、硫氧化物（SO₂）等主要大气污染物的排放控制要求变得越来越严格。因此,发展高效的脱硫、脱硝技术及提高现有脱硫、脱硝装置脱除效果已迫在眉急,且联合脱除技术已逐渐成为人们研究的重点。当前对煤灰矿物质催化再燃脱硝过程研究较多,但其分析的重点均只限于矿物质对C与NO异相还原过程的催化,而本文研究了煤灰矿物质对先进再燃脱硫、脱硝过程的催化性能,并重点从矿物质对CH_i、NH_i、CO等与NO的同相还原过程的催化角度揭示了煤灰矿物质影响脱硫、脱硝过程的催化路径及反应机理。为进一步提高先进再燃过程脱硝效果提供有力的理论依据,同时为燃烧法实现联合脱除NO_x和SO₂提供实际的指导意义。本文在两段式一维反应器试验台上进行了NaOH、KOH、FeCl₃和Ca（OH）₂催化先进再燃脱硝过程试验研究及电石渣催化先进再燃脱硫、脱硝过程试验研究。在保证反应温度、再燃比、NH₃/NO摩尔比、停留时间不变的条件下,研究了煤灰矿物质种类、负载量及再燃区初始氧量三因素对先进再燃脱硫、脱硝过程的影响。从矿物质对再燃、SNCR及先进再燃三过程脱硝率的影响角度分析比较了矿物质的催化能力,并揭示了其催化先进再燃脱硝过程的路径。结果发现:矿物质对再燃、先进再燃脱硝过程均表现出不同程度上的催化能力,且对先进再燃脱硝过程的催化效果最明显,各矿物质的催化能力大小依次为:NaOH> KOH> FeCl₃- Ca（OH）₂;矿物质催化先进再燃脱硝过程是通过催化该过程中的SNCR脱硝过程来实现的。通过分析矿物质对再燃、SNCR、先进再燃三过程中几种主要气相物质体积浓度变化的影响发现:NaOH和KOH可以通过抑制反应区NH₃与氧的氧化反应,从而促进NH₃与NO的还原过程,同时通过增加反应区CH₄与CO的浓度,进一步催化CH_i、NH_i、CO等与NO的同相还原过程;而FeCl₃和Ca（OH）₂对上述两方面影响较弱。因而NaOH和KOH对先进再燃脱硝过程的催化效果要强于FeCl₃和Ca（OH）₂。从电石渣对再燃、先进再燃两过程脱硝率、脱硫率的影响角度分析了电石渣对脱硫、脱硝过程的催化性能。结果发现:电石渣能小幅度提高再燃、先进再燃过程脱硫、脱硝效果,但均表现在再燃区初始氧量较低条件下,且电石渣对再燃脱硫、脱硝过程的催化能力要强于先进再燃的脱硫、脱硝过程。通过分析电石渣对再燃、先进再燃过程几种主要气相物质体积浓度变化的影响发现:电石渣和Ca（OH）₂类似,因对反应区气氛影响较弱,所以对脱硫、脱硝效果的催化能力较差。电石渣中的CaO在氧化性或者还原性气氛下会与SO₂反应生成不同的固硫产物,从而达到强化反应过程的脱硫效果。且当Ca/S比大小2.52时,电石渣能提高高氧条件下先进再燃过程脱硫效果。更多还原

【Abstract】 In China, the NO_x and SO₂ emitted from the coal combustion contribute significantly to the total emission, and there are 35%⁴0% NO_x from electric power plants. As a result of the environmental problem in the worldwide getting worse and worse, the request of the emission of the main atmosphere pollutants such as NO_x and SO₂ is becoming stricter and stricter. So there need some new technique with a higher NO_x reduction efficiency or SO₂ reduciton efficiency strongly, and it is more cost-efficient to improve the reduction efficiency in the exist equipments for NO_x and SO₂ reduction. There are more and more attention paid to the combining reduction of NO_x and SO₂. At present, there are some studies on the catalysis of mineral matters in the coal ash for NO_x reduction in coal reburing, but only the catalysis for the heterogenous reduction of C-NO is considered. In the text, the catalysis of the mineral matters for the NO_x and SO₂ reduction in the reburning and advanced reburning with pulverized coal is studied, and their catalyses for the homogenous reduction of CHi-NO, NHi-NO and CO-NO are analyzed in order to find out the catalytic paths and reaction mechanism of mineral matters. It can provide a theoretic gist for the improvement of NO_x reduction in the advanced reburning, and it can also supervise the realization of combining reduction of NO_x and SO₂ in the furnace.In the text, all the experiments are carried out on a two staged drop flow reactor. There contains two kinds experiments: one is on the catalyses for NO_x reduction in the advanced reburning of NaOH, KOH, FeCl3 and Ca（OH）₂, and the other is on the catalysis for the combining reduction in the advanced reburning of calcium carbide residue （CCR）. The effects of the category and load of mineral matters and the original fraction of oxgen （OFO） in the reburning zone on the catalysis of NO_x and SO₂ reduction are studied with the same reaction temperature, the smae fuel ratio, the same NH3/NO ratio and the same resident time.Through comparing and analyzing the catalyses for NO_x reduction of mineral matters in the reburning, SNCR process and the advanced reburning get their catalytic capabilities and the catalytic paths. It indicates that: the mineral matters can catalyze the denitrification process of the reburning and advanced reburning in different degrees, and the catalysis for the advanced reburning is more obvious, and the catalytic capabilities of mineral matters are ranked as NaOH> KOH> FeCl₃- Ca（OH）₂; the catalyses for the advanced reburning of mineral matters are realized by their catalyses for the SNCR process contained in the advanced reburning. From the effects on the conversions of some main gas matters in the reburning, SNCR process and advanced reburning by mineral matters, the results can be concluded as following: NaOH and KOH can restrain the oxygenation of NH₃ with oxygen, then promote the reduction of NH₃ with NO, at the same time, they can increase the concentration of CH4 and CO which can catalyze the homogenous reduction of CHi-NO, NHi-NO, CO-NO etc.; however FeCl3 and Ca（OH）₂ have little effects on the two aspects. So NaOH and KOH have a higher catalytic capability on NO_x reduction in the advanced reburning than FeCl3 and Ca（OH）₂.Through comparing and analyzing the catalyses for NO_x reduction and SO₂ reduction of calcium carbide residue （CCR）, it indicates that: calcium carbide residue （CCR） can improve the desulfurization and denitrification process of the reburning and advanced reburning a little, but it works only when the original fraction of oxygen （OFO） in the reburning zone is low, and its catalysis for the reburning is more obvious than the advanced reburning. From the effects on the conversions of some main gas matters in the reburning and advanced reburning by calcium carbide residue （CCR）, the results can be concluded as following: calcium carbide residue （CCR） has a little effect on the NO_x reduction and SO₂ reduction in the reburning and advanced reburning like Ca（OH）₂, due to its few effect on the conversions of the main gas matters in the reaction. The CaO contained in the calcium carbide residue （CCR） can absorb SO₂ in fuel poor or fuel rich in different ways, so it improves the SO₂ reduction. When the Ca/S ratio is larger than 2.52, calcium carbide residue （CCR） can increase the SO₂ reduction efficiency in the advanced reburning when the original fraction of oxygen （OFO） in the reburning zone is high.更多还原