第41卷第2期燃料化學(xué)學(xué)報(bào)Vol 41 No. 22013年2月Journal of Fuel Chemistry and TechnologyFeb,2013文章編號(hào):0253-2409(2013)02025205MgO脫除HCN的動(dòng)力學(xué)研究王新民,陳二強(qiáng)2,譚厚章,王學(xué)斌!,司紀(jì)朋',張利孟(1.西安交通大學(xué)能源與動(dòng)力工程學(xué)院熱流科學(xué)與工程教育部重點(diǎn)實(shí)驗(yàn)室,陜西西安7100492河南電力試驗(yàn)研究院,河南鄭州450052)摘要:研究了MgO在不同溫度下對(duì)HCN的脫除作用并用XRD對(duì)反應(yīng)后固相產(chǎn)物進(jìn)行分析。研究了溫度、MgO質(zhì)量分?jǐn)?shù)HCN初始體積分?jǐn)?shù)和停留時(shí)間等因素對(duì)HCN脫除效率的影響,并求出MgO與HCN反應(yīng)的動(dòng)力學(xué)參數(shù)。結(jié)果表明673K時(shí),MgO已經(jīng)開(kāi)始與HCN發(fā)生反應(yīng),當(dāng)溫度高于873K時(shí),HCN中氣態(tài)“N已轉(zhuǎn)化到固相產(chǎn)物MgCN2中;HCN脫除效率隨溫度、MgO質(zhì)量分?jǐn)?shù)和停留時(shí)間的增加呈線性增加但隨HCN初始體積分?jǐn)?shù)增加呈負(fù)冪函數(shù)的規(guī)律下降MgO與HCN的反應(yīng)級(jí)數(shù)a為0.72,表觀活化能E為32.2kJ/mol關(guān)鍵詞:HCN脫除;MgO;脫除效率中圖分類號(hào):TK16文獻(xiàn)標(biāo)識(shí)碼:ADynamic investigations on the removal of hydrogen cyanide using magnesium oxideWANG Xin-min, CHEN Er-qiang, TAN Hou-zhang, WANG Xue-bin, SI Ji-peng, ZHANG Li-meng(1. Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of EducationSchool of Energy and Power Engineering, Xi an Jiaotong University, Xi an 710049, China;2. Henan Electric Power Research Institute, Zhengzhou 450052, China)Abstract The removal of hydrogen cyanide( HCN)using magnesium oxide( MgO)at various temperatures wasinvestigated in the presented paper. The solid products were analysed by X-Ray Diffraction. The effects oftemperature, mass fraction of MgO, initial volume fraction of HCN and residence time were discussed. Thekinetic parameters of the reaction between HCN and Mgo were obtained. Results show that Mgo remarkablyreacts with HCN through transforming the nitrogen in HCN into the solid product MgCN2 from 873 K. Theremoval efficiency of HCN increases with the increase of temperature, mass fraction of MgO and residual time inlinear relation; but decreases with the initial volume fraction of HCN in negative power function relationshipThe reaction order and apparent activation energy of the reaction between HCn and mgo are 0. 72 and32 2 k/ mol respectivelyKey words: removal of hydrogen cyanide magnesium oxide; removal efficiencyHCN主要存在于煤的煉焦、液化及氣化等相關(guān)容易造成烴類合成工藝過(guò)程中毒,其中,一個(gè)很重要化工工藝過(guò)程中。煤在煉焦過(guò)程中生成的HCN會(huì)的毒性物質(zhì)就是HCN2。一起進(jìn)入煤氣中,HCN具有很強(qiáng)的腐蝕性和毒性,目前,世界各國(guó)脫除廢氣中的HCN主要有三在煤氣的后續(xù)生產(chǎn)過(guò)程中對(duì)生產(chǎn)設(shè)備、管道產(chǎn)生極種方法,吸收法、吸附法和燃燒法。燃燒法又分為直強(qiáng)的腐蝕,引起合成氣化學(xué)反應(yīng)催化劑中毒失活,嚴(yán)接燃燒法與催化燃燒法3-5。吸收法應(yīng)用最為廣重影響最終產(chǎn)品的收率和質(zhì)量;HCN同時(shí)也是泛,但要增加換熱設(shè)備的投資,又導(dǎo)致氣體物理顯熱燃煤過(guò)程中№o,生成最主要的前驅(qū)物。在聚丙烯損失。吸附法中,活性炭具有很高的吸附能力,但其腈碳纖維等新型碳纖維材料的生產(chǎn)工藝中腈類分子吸附容量有限,需要頻繁更換。中的N也主要以HCN的形式析出。近年來(lái),研究因此,研究HCN的脫除機(jī)理,開(kāi)發(fā)高效的HCN者越來(lái)越關(guān)注整體煤氣化聯(lián)合發(fā)電(lGCC)技術(shù)的脫除工藝,對(duì)控制煤加工、燃燒過(guò)程污染物排放和促發(fā)展,若氣化煤氣中的HCN在進(jìn)入燃?xì)廨啓C(jī)前不進(jìn)化工行業(yè)的綠色可持續(xù)發(fā)展意義重大能有效去除的話,則很容易在燃燒的高溫環(huán)境下轉(zhuǎn)王聰玲等6進(jìn)行了高溫下CaO脫除HCN的實(shí)化為氮氧化物,增加燃?xì)廨啓C(jī)的污染物排放。在大驗(yàn),研究了CaO脫除HCN的機(jī)理,并研究了溫度、量的合成烴類工業(yè)過(guò)程中,合成氣中的痕量元素很體積空速、HCN初始濃度對(duì)脫除HCN的影響。寧中國(guó)煤化工收稿日期:20120731;修回日期:20120923。CNMHG基金項(xiàng)目:國(guó)家自然科學(xué)基金(50976086)。聯(lián)系作者:王新民(1986),男,陜西寶雞人,碩土,研究方向?yàn)闈崈羧紵c污染防治;E-mai: wanger.86@su.xju.edu.c。第2期王新民等:MgO脫除HCN的動(dòng)力學(xué)研究253平等用NaOH和磺化酞菁鈷( CoPcS)浸漬對(duì)活性路氬氣與熱解所得HCN混合,起到稀釋作用,可以炭進(jìn)行改性處理,研究了改性處理活性炭對(duì)HCN通過(guò)調(diào)節(jié)兩路氣體流量獲得所需體積分?jǐn)?shù)的HCN的吸附作用,并研究了活性炭改性制備的最佳條件。實(shí)驗(yàn)用MgO為分析純,粒徑0.09~0.224mmMykda等研究了尿素浸漬處理和高溫處理活性將一定質(zhì)量MgO和SO2加入到石英管反應(yīng)器中,炭后對(duì)HCN的吸附,并對(duì)改性后活性炭表面進(jìn)行一定溫度下,在加熱爐B中與HCN進(jìn)行反應(yīng)。實(shí)了分析。但是對(duì)金屬氧化物脫除HCN的動(dòng)力學(xué)研驗(yàn)前進(jìn)行空載SO2實(shí)驗(yàn)發(fā)現(xiàn),SO2對(duì)HCN沒(méi)有脫究報(bào)道較少除作用,故可以用來(lái)稀釋MgO。本實(shí)驗(yàn)在石英管反應(yīng)器中,研究了MgO對(duì)稀釋后一定濃度的HCN進(jìn)入加熱爐B中,與HCN的脫除作用,并分析了溫度、MgO濃度、 HCN MgO進(jìn)行反應(yīng),加熱爐B的溫度由溫控儀B控制初始濃度、停留時(shí)間等因素對(duì)MgO脫除HCN效率反應(yīng)后氣體進(jìn)入U(xiǎn)型干燥管經(jīng)干燥后進(jìn)入煙氣分的影響,并求取MgO與HCN反應(yīng)的動(dòng)力學(xué)參數(shù)析儀測(cè)量各氣體濃度。U型干燥管中放有無(wú)水(反應(yīng)級(jí)數(shù)a和表觀活化能E)。caCl2和脫脂棉,實(shí)驗(yàn)發(fā)現(xiàn),無(wú)水CaCl2和脫脂棉對(duì)1實(shí)驗(yàn)部分HCN沒(méi)有脫除作用,可以用于干燥。取反應(yīng)后固相圖1為實(shí)驗(yàn)系統(tǒng)示意圖,高純氬氣(純度產(chǎn)物進(jìn)行XRD分析。99.999%)分為兩路,分別經(jīng)過(guò)流量計(jì)A、B,一路氬用芬蘭進(jìn)口的 GASMET FT-IR Dx4000便攜式氣進(jìn)入錐形瓶,攜帶吡啶,進(jìn)入加熱爐A中在姻氣分析儀在線測(cè)量 HCN CO等氣體濃度,測(cè)量精1273K下恒溫?zé)峤?獲得后續(xù)實(shí)驗(yàn)所需HCN;另一確度為±1×10°。mass flow meter Ahree directmass flow meter Bconicalmperature controller Atemperature controller Bdrying tubeDX-4000heating furmace B圖1實(shí)驗(yàn)系統(tǒng)示意圖2結(jié)果與討論1073、1273Kv凵中國(guó)煤化工除HCN,取2.1不同溫度下的脫除機(jī)理固相產(chǎn)物進(jìn)行CNMHGMgO0.4g,HCN初始體積分?jǐn)?shù)為(800±10)由圖2可知,溫度為4/3、673K時(shí),反應(yīng)后固相10°,氣體流量1000mL/min。分別在473、673、873、產(chǎn)物中以MgO為主,并未檢測(cè)到有顯著的MgCN2;學(xué)報(bào)第41卷當(dāng)溫度高于873K時(shí),固相產(chǎn)物中出現(xiàn)MgCN2wwso.0.17,反應(yīng)溫度分別為673、73、873、973和1073K。473KHCN脫除效率η=人口HCN濃度出口HCN濃度×10%入口HCN濃度873K研究溫度對(duì)HCN脫除效率的影響見(jiàn)圖4由圖4可知,隨著溫度升高,HCN脫除效率逐漸1073K升高,溫度對(duì)HCN脫除效率影響顯著。1001273K圖2不同溫度下MgO脫除HCN后固相產(chǎn)物XRD譜圖Figure 2 Solid products analysed with XRD atz95生various temperatures of HCN removal by MgO■:MgO;口:MgCN2在1073K下,HCN初始體積分?jǐn)?shù)800×10MgO質(zhì)量分?jǐn)?shù)0.17,氣體流量1000mL/min,用煙氣1100分析儀在線測(cè)量HCN、CO體積分?jǐn)?shù)隨時(shí)間變化趨Temperature T/K勢(shì),見(jiàn)圖3。圖4溫度對(duì)HCN脫除效率的影響Figure 4 Effect of temperature on removal efficiency of HCNinitial volume fraction of HCN800×10°,mass fraction of Mgo 0. 17HCNs歸23Mgo質(zhì)量分?jǐn)?shù)對(duì)HCN脫除效率的影響HCN初始體積分?jǐn)?shù)為800×10°,反應(yīng)溫度873K,氣體流量1000mL/min,改變MgO質(zhì)量分?jǐn)?shù)(SiO2量恒為2g)研究MgO質(zhì)量分?jǐn)?shù)對(duì)HCN脫除效率的影響,具體見(jiàn)圖5。實(shí)驗(yàn)選取HCN脫除效率峰值作為特征值η,根100120據(jù)特征值vp在不同反應(yīng)溫度和初始質(zhì)量分?jǐn)?shù)條件下的差異,求取動(dòng)力學(xué)參數(shù)。圖3 HCN. CO體積分?jǐn)?shù)隨時(shí)間的變化Figure 3 Varying of volume fraction of HCN and CO文獻(xiàn):0的研究結(jié)果表明,HCN的濃度變化可initial volume fraction of Hcn 800x10由下式表示mass fraction of Mgo 0. 17, temperature 1 073K293AEexI由圖3可知穩(wěn)定時(shí)HCN體積分?jǐn)?shù)減少量約604Q0·7·E106,C0體積分?jǐn)?shù)增加量約297×10°,其比值接近式中,k為反應(yīng)速率常數(shù),s;E為活化能kJ/mol;R為理想氣體常數(shù),kJ/(K·mol);a為由圖2和圖3推測(cè)出,當(dāng)溫度高于873K時(shí),HCN濃度項(xiàng)的反應(yīng)級(jí)數(shù),1;B為MgQ濃度項(xiàng)的反應(yīng)MgO和HCN發(fā)生反應(yīng)使其中所含氣態(tài)“N”轉(zhuǎn)化到級(jí)數(shù),1;為t時(shí)刻所通過(guò)料層的厚度,m,其中,假設(shè)固相產(chǎn)物中,轉(zhuǎn)化機(jī)理可能為:剛接觸料層上部處s=0,為料層的孔隙率,1;A為MgO+2HCN-+MgCn2 +CO+H2(1)反應(yīng)器的流通橫截面積m2;Qo為室溫下的氣體流2.2溫度對(duì)HCN脫除效率的影響量,m3/s;T中國(guó)煤化工HCN初始體積分?jǐn)?shù)800×10°,MgO質(zhì)量分?jǐn)?shù)由圖5可CNMHG呈線性關(guān)系,本工況中MgO0.4g、SiO22隨著MgO濃度增加,HCN脫除效率線性升高?？梢?jiàn),MgO濃度項(xiàng)的反應(yīng)級(jí)數(shù)B為1。第2期王新民等:MgO脫除HCN的動(dòng)力學(xué)研究255應(yīng)級(jí)數(shù),可以得出HCN濃度項(xiàng)的反應(yīng)級(jí)數(shù)a為0.72。25MgD脫除HCN的表觀活化能的wwo.為0.17,HCN初始體積分?jǐn)?shù)800×10°,氣體流量1000mL/min,在不同溫度下脫除HCN由公式(4)可以推導(dǎo)得出n{T[1-(1-mp)93kA·(1-a)6E1QoR()(5)0080.12由于反應(yīng)過(guò)程中,該公式右側(cè)第一項(xiàng)的各參數(shù)均Concentration of MgO為常量,故以為橫坐標(biāo),mn{T·[1-(1-m)“]1圖5MgO質(zhì)量分?jǐn)?shù)對(duì)HCN脫除效率的影響Figure 5 Effect of mass fraction of MgO為縱坐標(biāo)作圖,對(duì)實(shí)驗(yàn)數(shù)據(jù)進(jìn)行線性擬合,擬合得到on removal efficiency of HCNnitial volume fraction of HCN 800x10, temperature 873 K直線的斜率k即為-B,從而可求得Mgo與HCN24HCN初始體積分?jǐn)?shù)對(duì)HCN脫除效率的影響反應(yīng)的活化能E=-R·k。wwo為0.17,反應(yīng)溫度83K,改變HCN初始體圖7為線性擬合所得圖像,由圖7可知,直線斜積分?jǐn)?shù)(分別為400×10°、500×106、600×106、700率k為-387,活化能E=322kJ/mol106800×106),研究HCN初始體積分?jǐn)?shù)對(duì)HCN脫除效率的影響,具體見(jiàn)圖6。008z6655.01000(1000/K)圖7MgO與HCN反應(yīng)的 Arrhenius曲線Inital concentration of HCN/10Figure 7 Arrhenius curve of MgO reacting with HCN圖6HCN初始體積分?jǐn)?shù)對(duì)HCN脫除效率的影響Figure 6 Effect of initial volume fractionof HcNinitial mass fraction of MgO 0. 17, temperature 873 K由圖6可知,HCN脫除效率隨HCN初始體積分?jǐn)?shù)增加呈負(fù)冪函數(shù)的規(guī)律下降。將B=1帶入公式(3),進(jìn)行推導(dǎo)9得到7p293A·bwMo·8·exp(-000080001000012000140.001600018Qo·T·E圖間對(duì)HCNB險(xiǎn)的影響Figure 8 Ef中國(guó)煤化工 val of hcn將a從0~1取值,當(dāng)其使(1-m)°=initialCNMHG0°,f(1-a)c]的線性度最高時(shí)對(duì)應(yīng)的a值即為反mass fraction of MgO 0. 17, temperature 873K料化學(xué)學(xué)報(bào)第41卷2.6停留時(shí)間對(duì)HCN脫除效率的影響3結(jié)論通過(guò)改變兩路氣體流量,使HCN初始體積分673K時(shí),MgO已經(jīng)開(kāi)始與HCN發(fā)生反應(yīng),當(dāng)數(shù)維持在800×106,總氣體流量分別為600、800、溫度高于873K時(shí),HCN中氣態(tài)“N”已轉(zhuǎn)化到固相1000140 mL/min,MgO質(zhì)量分?jǐn)?shù)為0.17,研究產(chǎn)物MgCN2中停留時(shí)間對(duì)HCN脫除效率的影響,具體見(jiàn)圖8。由HCN脫除效率隨溫度、MgO質(zhì)量分?jǐn)?shù)和停留圖8可知,HCN脫除效率隨停留時(shí)間的延長(zhǎng)而呈線時(shí)間的增加呈線性增加,但隨HCN初始體積分?jǐn)?shù)性升高。增加呈負(fù)冪函數(shù)的規(guī)律下降;MgO與HCN反應(yīng)的反應(yīng)級(jí)數(shù)∝為0.72,表觀活化能E為322kJ/molo參考文獻(xiàn)[1]肖瑞華,白金鋒.煤化學(xué)產(chǎn)品工藝學(xué)[M].北京:冶金工業(yè)出版社,2003( XIAO Rui-hua, BAI Jin-feng. 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