鄭 斌,劉永啟,劉瑞祥,陳 帥,毛明明,孟 建

(山東理工大學(xué)交通與車輛工程學(xué)院,山東淄博 255049)

煤礦乏風(fēng)預(yù)熱催化氧化裝置的起動(dòng)性能

鄭 斌,劉永啟,劉瑞祥,陳 帥,毛明明,孟 建

(山東理工大學(xué)交通與車輛工程學(xué)院,山東淄博 255049)

搭建了煤礦乏風(fēng)預(yù)熱催化氧化實(shí)驗(yàn)裝置,試驗(yàn)研究了當(dāng)量加熱功率、流量比例系數(shù)、進(jìn)氣甲烷體積分?jǐn)?shù)對其起動(dòng)性能的影響規(guī)律。結(jié)果表明:隨著當(dāng)量加熱功率的增加,起動(dòng)時(shí)間和起動(dòng)能耗量均減少;隨著流量比例系數(shù)的增加,起動(dòng)時(shí)間和起動(dòng)能耗量均明顯增加;進(jìn)氣甲烷體積分?jǐn)?shù)變化對升溫曲線的影響不大,隨著進(jìn)氣甲烷體積分?jǐn)?shù)的增加,起動(dòng)時(shí)間僅略微減少。當(dāng)流量比例系數(shù)為0.35～0.40、當(dāng)量加熱功率為18～20 kW時(shí),起動(dòng)時(shí)間、起動(dòng)耗能量和氧化床入口溫度的平均增加速率均較小,裝置起動(dòng)性能良好。

預(yù)熱催化氧化裝置;煤礦乏風(fēng);起動(dòng)時(shí)間;起動(dòng)耗能量

煤礦瓦斯的主要成分為甲烷,是氣體能源,也是煤礦生產(chǎn)中最大安全隱患,通常采用大量通風(fēng)將其排放到大氣當(dāng)中(稱為煤礦乏風(fēng)),中國因采煤每年排放大量的甲烷[1-3],開展煤礦乏風(fēng)利用技術(shù)研究,對有效利用現(xiàn)有資源和減少溫室氣體排放均具有非常重要的意義[4-7]。煤礦乏風(fēng)中的甲烷含量很低,一般在0.10%～0.75%之間波動(dòng),利用難度大,目前有效處理煤礦乏風(fēng)的方式是逆流氧化技術(shù),包括熱逆流氧化和催化逆流氧化。在熱逆流氧化方面,山東理工大學(xué)[8-13]、Krzysztof[14]、大連理工大學(xué)[15]、中國礦業(yè)大學(xué)等[16-19]在氧化性能、阻力性能、混合性能和流動(dòng)分布等方面開展了系統(tǒng)的研究,為熱逆流氧化技術(shù)的應(yīng)用提供了有力支持;在催化逆流氧化方面,Juan Yin[20]、Shi Su[21]、蒲舸[22]研究了甲烷體積分?jǐn)?shù)、流量等因素對其氧化性能的影響規(guī)律。由于逆流氧化技術(shù)需要周期性改變流動(dòng)方向以實(shí)現(xiàn)可靠的熱反饋,導(dǎo)致其存在換向工作可靠性要求高、氧化床溫度場周期性波動(dòng)、裝置體積大、風(fēng)機(jī)耗能高等問題。

山東理工大學(xué)提出了一種利用氧化后乏風(fēng)排氣經(jīng)換熱器預(yù)熱未反應(yīng)乏風(fēng)、預(yù)熱乏風(fēng)經(jīng)催化劑完成氧化反應(yīng)的煤礦乏風(fēng)預(yù)熱催化氧化技術(shù)[23],該技術(shù)避免了逆流氧化技術(shù)的換向,使氧化溫度場更為穩(wěn)定可靠,而且熱量回收率高、結(jié)構(gòu)緊湊、流動(dòng)阻力小。氧化裝置低能耗、少用時(shí)、安全穩(wěn)定的順利起動(dòng),是實(shí)現(xiàn)裝置穩(wěn)定運(yùn)行的基本前提,筆者利用自行研制的煤礦乏風(fēng)預(yù)熱催化氧化實(shí)驗(yàn)裝置,試驗(yàn)研究了當(dāng)量加熱功率、流量比例系數(shù)、進(jìn)氣甲烷濃度等因素對其起動(dòng)性能的影響規(guī)律。

1 實(shí)驗(yàn)裝置與實(shí)驗(yàn)方法

煤礦乏風(fēng)預(yù)熱催化氧化試驗(yàn)臺(tái)如圖1所示,試驗(yàn)臺(tái)處理能力為1 000 m3/h(標(biāo)況),試驗(yàn)臺(tái)由催化氧化反應(yīng)室、預(yù)熱器、進(jìn)氣導(dǎo)流系統(tǒng)、加熱起動(dòng)系統(tǒng)、風(fēng)機(jī)和數(shù)據(jù)采集系統(tǒng)組成。催化氧化反應(yīng)室內(nèi)由蜂窩陶瓷式催化劑構(gòu)成催化氧化床,催化劑采用堇青石蜂窩陶瓷作為第1載體,γ-Al2O3為第2載體,以貴金屬Pd為主要活性組分,開孔密度為200目;預(yù)熱器采用間壁式氣-氣板式換熱器,內(nèi)部采用雙向波紋板以強(qiáng)化傳熱;進(jìn)氣導(dǎo)流系統(tǒng)由多塊導(dǎo)流板組成,以保證進(jìn)氣均勻;加熱起動(dòng)系統(tǒng)采用電加熱方式;數(shù)據(jù)采集系統(tǒng)為自行設(shè)計(jì)的PLC控制柜,實(shí)現(xiàn)對進(jìn)氣流量、進(jìn)氣甲烷體積分?jǐn)?shù)、溫度等參數(shù)的實(shí)時(shí)采集與存儲(chǔ)。

進(jìn)氣流量利用孔板流量計(jì)進(jìn)行測量,流量計(jì)具有溫壓自補(bǔ)償功能,測量范圍100～1 200 m3/h(標(biāo)況),誤差0.5%;進(jìn)氣甲烷濃度測量采用德國rbr測量技術(shù)公司的J2KN型多功能煙氣分析儀,CH4測量范圍0～4%,誤差0.001%;溫度測量采用標(biāo)準(zhǔn)K型熱電偶,熱電偶T1～T5布置在催化劑陶瓷的進(jìn)氣面,布置情況如圖2所示。模擬煤礦乏風(fēng)由天然氣和空氣配制而成,天然氣中CH4的純度為99.9%。

圖1 煤礦乏風(fēng)預(yù)熱催化氧化試驗(yàn)臺(tái)Fig.1 VAM preheating catalytic oxidation reactor

圖2 熱電偶布置示意Fig.2 Experimental arrangement of thermocouples

煤礦乏風(fēng)預(yù)熱催化氧化試驗(yàn)臺(tái)工作原理為:常溫的新鮮乏風(fēng)流經(jīng)預(yù)熱器、進(jìn)氣導(dǎo)流系統(tǒng)并由電加熱器加熱后進(jìn)入反應(yīng)室,在催化氧化床內(nèi)被氧化,氧化反應(yīng)放出的熱量一部分進(jìn)入陶瓷氧化床蓄熱,一部分由排氣攜帶在預(yù)熱器內(nèi)將熱量傳遞給新鮮乏風(fēng),降溫后的排氣最終排入到大氣中。

實(shí)驗(yàn)利用氧化床入口溫度變化、起動(dòng)時(shí)間和起動(dòng)能耗量來評價(jià)其起動(dòng)性能,其中氧化床入口溫度為催化劑陶瓷進(jìn)氣面5個(gè)溫度測量值的平均值,起動(dòng)時(shí)間為氧化床入口溫度達(dá)到475℃(前期大量實(shí)驗(yàn)結(jié)果表明:當(dāng)氧化床入口溫度達(dá)到475℃時(shí),煤礦乏風(fēng)即可實(shí)現(xiàn)催化氧化反應(yīng))所需的時(shí)長。主要實(shí)驗(yàn)條件為當(dāng)量加熱功率、流量比例系數(shù)和進(jìn)氣甲烷體積分?jǐn)?shù),其中:當(dāng)量加熱功率為每1 000 m3/h(標(biāo)況)乏風(fēng)設(shè)計(jì)處理量所需的加熱功率值,流量比例系數(shù)為起動(dòng)風(fēng)量與正常運(yùn)行乏風(fēng)設(shè)計(jì)處理量的比值。主要實(shí)驗(yàn)條件變化范圍為:當(dāng)量加熱功率為16～20 kW;流量比例系數(shù)為0.35～0.45;進(jìn)氣甲烷體積分?jǐn)?shù)0～0.3%。

2 實(shí)驗(yàn)結(jié)果與分析

2.1 當(dāng)量加熱功率的影響

圖3為不同當(dāng)量加熱功率時(shí)氧化床入口溫度的升溫變化曲線(流量比例系數(shù)為0.35),由圖可知:在起動(dòng)初期,不同當(dāng)量加熱功率下氧化床入口溫度的增加速率均較快,升溫曲線較陡,各升溫曲線差異較小;隨著加熱時(shí)間的延長,溫度增加速率均下降,升溫曲線逐漸變平緩,當(dāng)量加熱功率越大,增加速率下降越慢,升溫曲線變平緩的趨勢越慢。

圖3 當(dāng)量加熱功率變化對氧化床入口溫度的影響Fig.3 Variations of temperature rise profile at various equivalent heating powers

圖4為當(dāng)量加熱功率變化對起動(dòng)時(shí)間、起動(dòng)能耗量的影響曲線,由圖可知:隨著當(dāng)量加熱功率增加,起動(dòng)時(shí)間和起動(dòng)能耗量均減少。當(dāng)流量比例系數(shù)為0.35、當(dāng)量加熱功率為20 kW時(shí),起動(dòng)時(shí)間為74min,起動(dòng)能耗量為24.7 kW·h,較當(dāng)量加熱功率為16 kW時(shí)的起動(dòng)時(shí)間減少了36.2%,起動(dòng)能耗量減少了20.1%。由此可見,當(dāng)量加熱功率的適度增加可以有效地減少起動(dòng)時(shí)間和起動(dòng)能耗量?；谄饎?dòng)迅速且耗能少的原則,當(dāng)量加熱功率為18～20 kW時(shí),裝置的起動(dòng)性能較好,同時(shí)在該范圍內(nèi),氧化床入口溫度的平均增加速率僅為4.75～6.41℃/min,說明對催化劑陶瓷的熱沖擊也較小,因此最佳當(dāng)量加熱功率為18～20 kW。

2.2 流量比例系數(shù)的影響

圖5為不同流量比例系數(shù)時(shí)氧化床入口溫度的升溫變化曲線(當(dāng)量加熱功率為20 kW),由圖可知:在起動(dòng)初期,不同流量比例系數(shù)下氧化床入口溫度的增加速率均較快,升溫曲線較陡,各升溫曲線差異較小;隨著加熱時(shí)間的延長,溫度增加速率均下降,升溫曲線逐漸變平緩,流量比例系數(shù)越大,增加速率下降越快,升溫曲線變平緩的趨勢越顯著。

圖4 當(dāng)量加熱功率變化對起動(dòng)時(shí)間和起動(dòng)能耗量的影響Fig.4 Variations of starting time consumption and starting power consumption at various equivalentheating powers

圖5 流量比例系數(shù)變化對氧化床入口溫度的影響Fig.5 Variations of temperature rise profile at various flow proportionality coefficients

圖6為流量比例系數(shù)變化對起動(dòng)時(shí)間、起動(dòng)能耗量的影響曲線,由圖可知:隨著流量比例系數(shù)增加,起動(dòng)時(shí)間和起動(dòng)能耗量均明顯增加。當(dāng)量加熱功率為20 kW時(shí),當(dāng)流量比例系數(shù)由0.35增加至0.45,起動(dòng)時(shí)間和起動(dòng)能耗量增加了45.9%;而當(dāng)量加熱功率為18 kW時(shí),起動(dòng)時(shí)間和起動(dòng)能耗量則增加了66.3%。當(dāng)流量比例系數(shù)為0.35～0.40時(shí),起動(dòng)時(shí)間、起動(dòng)能耗量和氧化床入口溫度的平均增加速率均較小,此范圍為最佳流量比例系數(shù)。

2.3 進(jìn)氣甲烷體積分?jǐn)?shù)的影響

圖6 流量比例系數(shù)變化對起動(dòng)時(shí)間和起動(dòng)能耗量的影響Fig.6 Variations of starting time consumption and starting power consumption at various flow proportionality coefficients

圖7 進(jìn)氣甲烷濃度變化對氧化床入口溫度和起動(dòng)時(shí)間的影響Fig.7 Variations of temperature rise profile and starting time consumption at variousmethane concentrations

圖7為進(jìn)氣甲烷濃度變化對氧化床入口溫度和起動(dòng)時(shí)間的影響曲線(當(dāng)量加熱功率為20 kW,流量比例系數(shù)0.35),由圖可知:在整個(gè)起動(dòng)過程中,進(jìn)氣甲烷體積分?jǐn)?shù)變化對升溫曲線的影響不大,僅在起動(dòng)末期產(chǎn)生微小的分離現(xiàn)象,當(dāng)進(jìn)氣甲烷體積分?jǐn)?shù)由0增加到0.3%時(shí),起動(dòng)時(shí)間僅減少4.4%。這是因?yàn)橛捎诩淄轶w積分?jǐn)?shù)非常低,同時(shí)僅有微少量的甲烷因?yàn)榕鲎驳仍蛟诮?jīng)過電加熱絲時(shí)發(fā)生氧化放熱,因此進(jìn)氣甲烷體積分?jǐn)?shù)對起動(dòng)性能的影響較小。

3 結(jié) 論

(1)在起動(dòng)初期,不同當(dāng)量加熱功率下各升溫曲線差異較小,隨著加熱時(shí)間的增加,升溫曲線逐漸變平緩,當(dāng)量加熱功率越大,升溫曲線變平緩的趨勢越慢。隨著當(dāng)量加熱功率的增加,起動(dòng)時(shí)間和起動(dòng)能耗量均減少。

(2)起動(dòng)前期,流量比例系數(shù)變化對升溫曲線的影響較小,起動(dòng)中后期,流量比例系數(shù)越大,升溫曲線變平緩的趨勢越顯著,隨著流量比例系數(shù)的增加,起動(dòng)時(shí)間和起動(dòng)能耗量均明顯增加。

(3)在整個(gè)起動(dòng)過程中,進(jìn)氣甲烷體積分?jǐn)?shù)變化對升溫曲線的影響不大,隨著進(jìn)氣甲烷體積分?jǐn)?shù)的增加,起動(dòng)時(shí)間僅略微降低。

(4)當(dāng)流量比例系數(shù)為0.35～0.40、當(dāng)量加熱功率為18～20 kW時(shí),起動(dòng)時(shí)間、起動(dòng)能耗量和氧化床入口溫度的平均增加速率均較小,起動(dòng)性能較好。

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Starting characteristics of ventilation air methane preheating catalytic oxidation reactor

ZHENG Bin,LIU Yong-qi,LIU Rui-xiang,CHEN Shuai,MAOMing-ming,MENG Jian

(School of Traffic and Vehicle Engineering,Shandong University of Technology,Zibo 255049,China)

The ventilation air methane(VAM)preheating catalytic monolithic reactor was built.The effects of the equivalent heating power,the flow proportionality coefficientand themethane concentration on the starting characteristics of preheating catalytic monolithic reactor were studied experimentally.The results show that with the increase of the equivalent heating power,the starting time consumption and starting power consumption decrease.With the increase of the flow proportionality coefficient,the starting time consumption and starting power consumption increase.The variations of temperature rise profile at variousmethane concentrations is little.With the increase of themethane concentration,the starting time consumption decreases hardly.When the flow proportionality coefficient from 0.35 to 0.40 and the equivalent heating power from 18 kW to 20 kW,the starting time consumptions,the starting power consumptions and the average rise ratios of oxidation bed inlet temperature are small,the excellent starting characteristics is exhibited.

preheating catalytic monolithic reactor;ventilation air methane;starting time consumption;starting power consumption

TD712

A

0253-9993(2014)06-1084-05

鄭 斌,劉永啟,劉瑞祥,等.煤礦乏風(fēng)預(yù)熱催化氧化裝置的起動(dòng)性能[J].煤炭學(xué)報(bào),2014,39(6):1084-1088.

10.13225/j.cnki.jccs.2013.1190

Zheng Bin,Liu Yongqi,Liu Ruixiang,et al.Starting characteristics of ventilation air methane preheating catalytic oxidation reactor[J].Journal of China Coal Society,2014,39(6):1084-1088.doi:10.13225/j.cnki.jccs.2013.1190

2013-08-22 責(zé)任編輯:張曉寧

國家高技術(shù)研究發(fā)展計(jì)劃(863)資助項(xiàng)目(2009AA063202);山東省科技發(fā)展計(jì)劃資助項(xiàng)目(2012GGX10417);山東省自然科學(xué)基金資助項(xiàng)目(ZR2011EL017)

鄭 斌(1982—),男,山東淄博人,講師,碩士。Tel:0533-2782616,E-mail:sdutzb@163.com。通訊作者:劉永啟(1965—),男,山東棗莊人,教授,博士。Tel:0533-2782616,E-mail:liuyq65@163.com