本文選題：雙室型乏風(fēng)預(yù)熱催化氧化　切入點(diǎn)：導(dǎo)流分配　出處：《山東理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：煤礦乏風(fēng)瓦斯中蘊(yùn)含著巨大的潛在能源,但由于其甲烷濃度極低的特點(diǎn),通常難以利用而被直接排空。據(jù)統(tǒng)計(jì),目前我國每年通過煤礦向大氣中排放的瓦斯已經(jīng)超過250億m3,造成了嚴(yán)重的環(huán)境污染和能源浪費(fèi),由此可見實(shí)現(xiàn)煤礦乏風(fēng)瓦斯的有效利用具有非常重大的現(xiàn)實(shí)意義。本文基于此現(xiàn)狀,設(shè)計(jì)搭建了雙室型煤礦乏風(fēng)預(yù)熱催化氧化試驗(yàn)裝置,對其結(jié)構(gòu)原理、系統(tǒng)組成及操作過程進(jìn)行了詳細(xì)介紹,并基于試驗(yàn)裝置進(jìn)行了一系列模擬及試驗(yàn)研究。利用數(shù)值模擬的方法對氧化床入口的導(dǎo)流分配系統(tǒng)進(jìn)行了設(shè)計(jì),通過加裝導(dǎo)流板、優(yōu)化結(jié)構(gòu)參數(shù)改善了氧化床入口的流動(dòng)均勻性。結(jié)果表明,當(dāng)導(dǎo)流板的圓角半徑為140mm、數(shù)量為3塊、相對距離在0.3~0.4之間時(shí)導(dǎo)流效果較好,最優(yōu)方案的流動(dòng)不均勻性系數(shù)降至0.2以下。通過加熱啟動(dòng)實(shí)驗(yàn)對氧化床的穩(wěn)定性進(jìn)行了研究,結(jié)果表明:反應(yīng)室良好的對稱性為氧化床的穩(wěn)定運(yùn)行提供了條件;陶瓷散熱損失的存在使氧化床軸向溫度呈現(xiàn)逐漸降低的狀態(tài),溫度高于700℃時(shí)散熱量較大;加熱啟動(dòng)初期熱漂移現(xiàn)象較明顯,溫度不均勻系數(shù)較高,系統(tǒng)穩(wěn)定后溫度不均勻系數(shù)低于0.05;升溫工況比降溫工況的穩(wěn)定時(shí)間短,保持升溫工況更容易實(shí)現(xiàn)氧化床的穩(wěn)定。在保持電加熱開啟的狀態(tài)下實(shí)驗(yàn)研究了空速、氧化床入口溫度和甲烷濃度對氧化過程的影響,結(jié)果表明:甲烷的催化氧化主要集中在第一層催化陶瓷中,空速的增大使主要反應(yīng)區(qū)域增大,空速由3800 h-1增至7100 h-1時(shí),有效反應(yīng)長度增加了約31%,空速大于7100 h-1時(shí),有效反應(yīng)長度增大的速率加快,轉(zhuǎn)化率略有下降;氧化床入口溫度的升高使主要反應(yīng)區(qū)域減小,溫度由422℃升高至485℃時(shí),有效反應(yīng)長度減小了約53%,轉(zhuǎn)化率上升,溫度高于485℃后影響的作用逐漸減弱;甲烷濃度的增加對氧化過程的影響較小,有效反應(yīng)長度略有減小,轉(zhuǎn)化率略有上升。通過總結(jié)實(shí)驗(yàn)數(shù)據(jù),得到了有效反應(yīng)長度的經(jīng)驗(yàn)公式。對裝置自維持運(yùn)行狀態(tài)下的熱平衡進(jìn)行了研究,計(jì)算分析了不同甲烷濃度和空速下的熱平衡情況,結(jié)果表明:甲烷濃度越高時(shí),系統(tǒng)的富余熱量越多,散熱損失所占的比重越大,濃度高于1.05%時(shí),高于排氣損失占據(jù)主導(dǎo)地位;空速越大時(shí),實(shí)現(xiàn)自維持所需的濃度越高,系統(tǒng)的排氣損失占得比重越大,空速大于7000 h-1時(shí),高于散熱損失開始占據(jù)主導(dǎo)地位。因此應(yīng)針對高甲烷濃度工況著重控制散熱損失,針對高空速?zèng)r著重控制排氣損失,對預(yù)熱器和保溫層進(jìn)行合理設(shè)計(jì),以增大能量的富余、提高余熱資源的利用率。
[Abstract]:Coal mine exhaust gas contains huge potential energy, but because of its extremely low methane concentration, it is usually difficult to use and is directly emptied. At present, China has discharged more than 25 billion m3 of gas into the atmosphere each year through coal mines, which has caused serious environmental pollution and energy waste. Therefore, it is of great practical significance to realize the effective utilization of the exhausted air gas in coal mine. Based on the present situation, this paper designs and builds a two-chamber test device for catalytic oxidation of coal mine exhaust air preheating, and gives the structure principle of the device. The composition and operation process of the system are introduced in detail, and a series of simulation and experimental research are carried out based on the test device. The flow diversion distribution system at the entrance of the oxidation bed is designed by numerical simulation, and the flow guide plate is added to the system. The flow uniformity at the inlet of the oxidation bed is improved by optimizing the structural parameters. The results show that when the radius of the guide plate is 140 mm, the number of the plate is 3, the relative distance is between 0.3 and 0.4, the flow diversion effect is better. The flow inhomogeneity coefficient of the optimal scheme is reduced to less than 0.2. The stability of the oxidation bed is studied by heating start-up experiment. The results show that the good symmetry of the reaction chamber provides the conditions for the stable operation of the oxidation bed. Due to the existence of ceramic heat loss, the axial temperature of the oxidation bed decreases gradually, and when the temperature is higher than 700 鈩，

本文編號：1612581