本文選題：模擬煙氣 + 單質(zhì)汞　； 參考：《湖南大學》2014年碩士論文

【摘要】：汞是一種對人類健康和生態(tài)系統(tǒng)有劇毒的污染物。無論是發(fā)達國家還是發(fā)展中國家，都面臨著嚴重的汞污染問題，其中煤燃燒是大氣汞污染最主要的來源之一。我國是全球最大的汞排放國，而燃煤電廠是我國最重要的汞排放源，因此，開發(fā)行之有效的方法來降低燃煤電廠的汞排放量顯得尤為迫切。當前，活性炭噴射技術(shù)(ACI)被認為是最有效的燃煤電廠汞排放控制技術(shù)。然而，活性炭作為汞吸附劑的應用受到以下兩個方面的限制：一方面，ACI技術(shù)需要消耗大量的活性炭導致高成本；另一方面，活性炭吸附劑的應用存在潛在的二次污染問題。這樣不僅浪費了資源還帶來了新的環(huán)境問題，因此，開發(fā)高效的、無二次污染的吸附劑對于ACI技術(shù)來講非常關鍵。本文制備了一系列的改性活性炭，對其汞脫除性能進行了評估，，并深入探討了改性活性炭的汞脫除機理，以期獲得高效穩(wěn)定的汞吸附劑。 首先考察了多種原始活性炭對模擬煙氣中氣態(tài)汞的吸附性能，并詳細考察了活性炭顆粒大小和反應溫度等因素對活性炭吸附性能的影響。實驗結(jié)果表明，木質(zhì)活性炭對氣態(tài)汞具有較好的脫除效果，反應溫度越低越有利于反應的進行。適宜的活性炭顆粒大小(0.15d0.25mm)能達到最佳的除汞效果，過大或者過小的粒徑都對反應不利。 然后對活性炭進行Na2S、CeCl3浸漬改性以及高溫滲硫改性，復合改性活性炭是先通過Na2S或CeCl3溶液浸漬活性炭再通過高溫滲硫制得。運用比表面積, X射線衍射，掃描電子顯微鏡和X射線光電子能譜對樣品的物理化學性質(zhì)進行表征。對Na2S改性活性炭中負載量的研究結(jié)果表明，Na2S/AC的最佳負載量為5%。此外，研究了高溫滲硫過程中滲硫溫度以及硫炭比對S改性活性炭脫汞性能的影響，結(jié)果顯示600℃滲硫活性炭表現(xiàn)出了最佳的脫汞性能；硫炭比從2:1降至1:2時，滲硫活性炭的硫含量以及脫汞性能只微弱下降。復合硫化改性活性炭Na2S-S/AC的汞飽和吸附量最大，為3282μg-Hg/g-C，約是單質(zhì)硫改性活性炭的1.5倍。實驗考察了不同煙氣組分對Na2S-S/AC的影響，結(jié)果顯示，當氧氣含量提高至9%時，使Na2S-S/AC的脫汞效率提高了25%，NO和SO2對脫汞效率無顯著影響，而H2O(8%)的存在，導致Na2S-S/AC脫汞效率降低了24%。將復合改性活性炭CeCl3-S/AC與CeCl3/AC對Hg0以及總汞的脫除性能做對比，結(jié)果表明CeCl3-S/AC對Hg0以及Hg2+的吸附性能均好于CeCl3/AC。
[Abstract]:Mercury is a highly toxic pollutant to human health and ecosystem. Both developed and developing countries are faced with serious mercury pollution, among which coal combustion is one of the most important sources of atmospheric mercury pollution. China is the largest emitter of mercury in the world, and coal-fired power plant is the most important source of mercury emission in China. Therefore, it is urgent to develop effective methods to reduce mercury emissions from coal-fired power plants. At present, activated carbon injection technology (ACI) is considered to be the most effective mercury emission control technology in coal-fired power plants. However, the application of activated carbon as a mercury adsorbent is limited by the following two aspects: on the one hand, ACI technology needs to consume a large amount of activated carbon, which leads to high cost; on the other hand, the application of activated carbon adsorbent has potential secondary pollution problem. This not only wastes resources, but also brings new environmental problems. Therefore, the development of efficient, non-secondary pollution-free adsorbent is very important for ACI technology. In this paper, a series of modified activated carbon were prepared, their mercury removal properties were evaluated, and the mercury removal mechanism of modified activated carbon was discussed in order to obtain high efficient and stable mercury adsorbent. The adsorption properties of gaseous mercury in simulated flue gas by various kinds of raw activated carbon were investigated, and the effects of particle size and reaction temperature on the adsorption properties of activated carbon were investigated in detail. The experimental results show that wood activated carbon has a better removal effect on gaseous mercury, and the lower the reaction temperature is, the more favorable the reaction is. The optimum particle size of activated carbon is 0.15d0.25mm), and too large or too small particle size is unfavorable to the reaction. Then the activated carbon was modified by Na2S- CeCl3 impregnation and high temperature sulphurizing. The composite modified activated carbon was prepared by impregnating activated carbon with Na2S or CeCl3 solution and then by sulfurizing at high temperature. The physical and chemical properties of the samples were characterized by specific surface area, X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The results of study on the loading amount of Na2S modified activated carbon show that the optimum loading amount of Na2S / AC is 5%. In addition, the effects of sulfurizing temperature and the ratio of sulfur to carbon on the removal of mercury from S modified activated carbon during high temperature sulphurizing were studied. The results showed that the desulfurized activated carbon at 600 鈩

本文編號：2038895