【摘要】：目前,我國(guó)燃煤主要污染物排放標(biāo)準(zhǔn)日趨嚴(yán)格,近年來(lái)國(guó)家大力推進(jìn)實(shí)施超低排放控制技術(shù),致使主要污染物末端治理工藝更加復(fù)雜。燃煤煙氣中汞含量少、濃度低,到目前為止我國(guó)尚沒(méi)有商業(yè)化并廣泛投入應(yīng)用的燃煤電站經(jīng)濟(jì)、高效的脫汞技術(shù)。大氣污染控制已經(jīng)上升為國(guó)家戰(zhàn)略,針對(duì)燃煤煙氣中控制汞排放技術(shù),要從源頭和過(guò)程排放控制相結(jié)合出發(fā),實(shí)現(xiàn)經(jīng)濟(jì)、高效、協(xié)同控制。研究表明,煤熱解脫汞工藝是燃燒前期脫汞的可行方案。燃燒前熱處理生成的煙氣中的汞濃度會(huì)大大提高,而且煙氣處理量大大減少。同時(shí),在燃燒前熱處理過(guò)程中,對(duì)煤中的S也能得到一定程度上的脫除,實(shí)現(xiàn)協(xié)同控制。另一方面,前期研究發(fā)現(xiàn),高硫煤中硫、汞賦存形態(tài)存在正相關(guān)關(guān)系,并且脫汞技術(shù)中中硫、汞存在相關(guān)關(guān)系。煤中汞在熱解或燃燒過(guò)程中的主要形態(tài)為Hg0,同時(shí),煤熱解過(guò)程中含硫的主要形式為H2S,而煤燃燒后的煙氣中硫元素的絕大部分存在形式為S02。H23與S02在適當(dāng)條件下發(fā)生化學(xué)反應(yīng)產(chǎn)生硫單質(zhì),單質(zhì)硫與汞蒸氣發(fā)生反應(yīng)生成穩(wěn)定的化合物HgS,從而實(shí)現(xiàn)脫除汞的目的。基于此,山東大學(xué)提出高硫煤熱解、燃燒過(guò)程中硫、汞協(xié)同脫除的方法。首先通過(guò)控制煤中硫元素的熱解和燃燒產(chǎn)物H2S、02、S02之間發(fā)生化學(xué)變化形成硫單質(zhì),然后硫單質(zhì)與熱解出的Hg反應(yīng)生成穩(wěn)定的化合物HgS,最后從熱解氣中排出,實(shí)現(xiàn)煤中硫、汞元素在燃燒前期的協(xié)同脫除。本文搭建了單質(zhì)硫與汞蒸氣(S-Hg)反應(yīng)試驗(yàn)系統(tǒng)和模擬氣體H2S-S02-Hg聯(lián)合反應(yīng)試驗(yàn)系統(tǒng)。首先試驗(yàn)研究了非催化與催化條件下S、Hg反應(yīng)特征和溫度、氣氛種類對(duì)該反應(yīng)進(jìn)行程度的影響。研究發(fā)現(xiàn)S與Hg在常溫下即可發(fā)生反應(yīng),但受到溫度的限制,汞的脫除效率較低。當(dāng)溫度升高時(shí),S與Hg的反應(yīng)速度增大。催化條件下,反應(yīng)溫度為100℃時(shí),汞的脫除率為76.8%。添加鋁基催化劑可以顯著地促進(jìn)S-Hg反應(yīng)的進(jìn)行,大幅提升汞的脫除率。在非催化條件下,氧氣能夠提升氣相單質(zhì)汞的脫除效果,但提升比例不大。催化條件下隨著氧氣體積分?jǐn)?shù)的增加S-Hg反應(yīng)效率顯著提升。C02氣體對(duì)S-Hg反應(yīng)沒(méi)有影響。S02作為硫化氫與二氧化硫歸中反應(yīng)重要的反應(yīng)物對(duì)S-Hg反應(yīng)作用甚微,在實(shí)際中不作為主要影響因素來(lái)考慮。其次試驗(yàn)研究了非催化條件下H2S-S02-Hg聯(lián)合反應(yīng)的脫汞效果和催化條件下H2S-S02-Hg聯(lián)合反應(yīng)特征及多因素對(duì)該反應(yīng)進(jìn)行程度的影響。研究發(fā)現(xiàn),非催化條件下聯(lián)合反應(yīng)中單質(zhì)汞脫除率整體較低,脫汞效果差,在實(shí)際生產(chǎn)中不宜應(yīng)用。催化條件下反應(yīng)溫度為200℃時(shí),汞的脫除效率為82%,H2S-SO2反應(yīng)率達(dá)到80%,溫度過(guò)高并不會(huì)提升聯(lián)合反應(yīng)的進(jìn)行程度。反應(yīng)時(shí)間延長(zhǎng),聯(lián)合反應(yīng)更加充分,但反應(yīng)時(shí)間延長(zhǎng)至3s時(shí),聯(lián)合反應(yīng)效率提升不明顯。聯(lián)合反應(yīng)H2S-S02反應(yīng)率受摩爾比的影響比較大,汞的脫除效率也受到影響,但變化程度沒(méi)有H2S-S02反應(yīng)大。摩爾比為2時(shí),聯(lián)合反應(yīng)效率最高。C02對(duì)聯(lián)合反應(yīng)不存在影響。隨著模擬氣氛中02濃度的提升,汞的去除效率呈現(xiàn)上升趨向,H2S-S02反應(yīng)率呈下降趨勢(shì),在實(shí)際應(yīng)用中要綜合考慮氧氣的體積分?jǐn)?shù)對(duì)兩個(gè)分反應(yīng)的影響。隨著聯(lián)合反應(yīng)入口單質(zhì)汞濃度的提升,聯(lián)合反應(yīng)汞的脫除能力下降。
[Abstract]:At present, the emission standard of coal-fired main pollutants in China is becoming more and more strict, and in recent years, the state has vigorously promoted the implementation of the ultra-low emission control technology, leading to the more complicated end-treatment process of the main pollutants. The mercury content in the coal-fired flue gas is low, the concentration is low, so far, the coal-fired power station has not been commercialized and has been widely applied to the economic and high-efficiency mercury-removing technology of the coal-fired power station. The control of air pollution has risen to the national strategy, and the control of the mercury discharge technology in the coal-fired flue gas should be combined with the control of the source and the process to realize the economic, efficient and cooperative control. The study shows that the coal-heat-releasing mercury process is a feasible scheme for mercury removal in the early stage of combustion. The mercury concentration in the flue gas generated by the heat treatment before combustion can be greatly improved, and the treatment capacity of the flue gas is greatly reduced. At the same time, the S in the coal can be removed to a certain extent during the pre-combustion heat treatment process, and the synergistic control can be realized. On the other hand, in the early stage, there is a positive correlation between sulfur and mercury in the high-sulfur coal, and there is a correlation between the sulfur and the mercury in the mercury-removing technology. The main form of the mercury in the process of pyrolysis or combustion is Hg0, at the same time, the main form of sulfur in the coal pyrolysis process is H2S, and most of the sulfur elements in the flue gas after coal combustion is in the form of S02. H23 and S02 generate sulfur simple substance by chemical reaction under the appropriate conditions, The elemental sulfur reacts with the mercury vapor to form a stable compound HgS, thereby achieving the purpose of removing mercury. On the basis of this, Shandong University proposed a method of co-removal of sulfur and mercury in the process of pyrolysis and combustion of high-sulfur coal. firstly, the sulfur element is formed by controlling the chemical change between the pyrolysis of the sulfur element in the coal and the H2S,02 and S02 of the combustion products, The co-removal of the mercury element in the pre-combustion stage. The reaction test system of elemental sulfur and mercury vapor (S-Hg) and simulated gas H2S-S02-Hg are set up in this paper. The reaction characteristics and temperature of S, Hg under non-catalytic and catalytic conditions and the influence of the kind of atmosphere on the reaction were studied. It is found that S and Hg can react at normal temperature, but are limited by temperature, and the removal efficiency of mercury is low. When the temperature is increased, the reaction rate of S and Hg is increased. Under the catalysis condition, the removal rate of mercury was 76.8% when the reaction temperature was 100 鈩，

本文編號(hào)：2480455