本文選題：纖維素裂解　切入點(diǎn)：油中甲醇含量　出處：《西南交通大學(xué)》2017年碩士論文

【摘要】：變壓器油紙絕緣系統(tǒng)中,絕緣紙的機(jī)械強(qiáng)度取決于纖維素鏈的平均長(zhǎng)度,聚合度DP作為反映纖維素分子B-D-吡喃葡萄糖環(huán)數(shù)量的參數(shù)是評(píng)估絕緣紙老化程度最直接的測(cè)量手段。而在變壓器實(shí)際運(yùn)行中,聚合度不具備直接測(cè)量的條件,一般通過(guò)分析研究絕緣紙組分老化降解的油溶性特征產(chǎn)物來(lái)間接反映變壓器內(nèi)絕緣的老化狀態(tài)。因?yàn)閭鹘y(tǒng)的基于油中氣體含量和油中糠醛含量的絕緣狀態(tài)評(píng)估方法或多或少的存在一些缺陷,且隨著檢測(cè)技術(shù)和儀器的不斷進(jìn)步與成熟,尋找更為準(zhǔn)確有效的老化產(chǎn)物作為油紙絕緣狀態(tài)評(píng)估的參數(shù)指標(biāo)更具實(shí)際意義。本文研究了油紙絕緣老化產(chǎn)物甲醇與絕緣紙纖維素裂解之間的特性關(guān)系,在實(shí)驗(yàn)室中設(shè)計(jì)了不同溫度和初始水分含量下的油紙絕緣系統(tǒng)老化試驗(yàn),引入了化學(xué)分析中先進(jìn)的頂空進(jìn)樣氣相色譜-質(zhì)譜聯(lián)用法對(duì)老化后的油中甲醇含量進(jìn)行測(cè)量。以絕緣紙聚合度為參量建立老化動(dòng)力學(xué)模型,引入Mark-Houwink方程,得到不同老化條件下纖維素的裂解速率,分別提取纖維素裂解及甲醇生成過(guò)程中相應(yīng)的特征參數(shù),進(jìn)行Arrhenius參數(shù)擬合分析。結(jié)果表明:老化溫度的升高可以提高甲醇的生成速率與纖維素分子鏈的裂解速率,但對(duì)老化產(chǎn)物向生成甲醇方向發(fā)展的影響無(wú)明顯規(guī)律可循;水分和氧氣的存在催化了纖維素裂解產(chǎn)物向生成甲醇的方向轉(zhuǎn)變,纖維素水解的中間產(chǎn)物產(chǎn)生甲醇的幾率較小,甲醇主要來(lái)自于纖維素氧解的中間產(chǎn)物,且氧解中間產(chǎn)物進(jìn)一步反應(yīng)生成甲醇需要水的協(xié)同作用,在此基礎(chǔ)上,設(shè)計(jì)中間產(chǎn)物的老化試驗(yàn),對(duì)該結(jié)論提供了一定的證明。在纖維素裂解產(chǎn)生甲醇特性研究的基礎(chǔ)上,通過(guò)建立甲醇與聚合度的關(guān)系模型,對(duì)實(shí)驗(yàn)室條件下的油紙絕緣系統(tǒng)進(jìn)行壽命預(yù)測(cè),結(jié)果表明絕緣紙中水分含量每增加0.5%,絕緣的壽命減半;老化溫度每上升8-10℃,絕緣紙壽命減半;與眾多研究相吻合。試驗(yàn)研究了甲醇在油紙系統(tǒng)中的穩(wěn)態(tài)分布情況,結(jié)果顯示正常的老化溫度下,纖維素裂解產(chǎn)生的甲醇很大一部分存在于絕緣紙中。研究為基于油中甲醇含量的變壓器狀態(tài)評(píng)估體系的建立提供了 一定的參考。
[Abstract]:In transformer oil-paper insulation system, the mechanical strength of insulator paper depends on the average length of cellulose chain. The degree of polymerization DP is the most direct measurement method to evaluate the aging degree of insulator paper as the parameter reflecting the number of cellulose molecule B-D- glucose ring.However, in the actual operation of transformer, polymerization degree does not have the condition of direct measurement. Generally, the aging state of insulation in transformer is indirectly reflected by analyzing and studying the oil-soluble characteristic products of aging degradation of insulator paper components.Because the traditional methods based on gas content in oil and furfural content in oil have some defects, and with the development and maturity of detection technology and instruments,It is of practical significance to find more accurate and effective aging products as parameter indexes for evaluation of oil-paper insulation status.In this paper, the characteristic relationship between methanol, the aging product of oil-paper insulation, and cellulose cracking of insulator paper was studied. The aging test of oil-paper insulation system was designed at different temperature and initial moisture content in laboratory.The advanced headspace injection gas chromatography-mass spectrometry (GC / MS) method was used to determine the methanol content in aged oil.The aging kinetic model was established with the polymerization degree of insulator paper as a parameter. The Mark-Houwink equation was introduced to obtain the decomposition rate of cellulose under different aging conditions, and the corresponding characteristic parameters in the process of cellulose cracking and methanol generation were extracted respectively.Arrhenius parameter fitting analysis was carried out.The results show that the increase of aging temperature can increase the rate of methanol formation and the cleavage rate of cellulose molecular chain, but the effect of aging products on the direction of methanol formation is not obvious.The presence of water and oxygen catalyzes the conversion of cellulose pyrolysis products to methanol. The probability of methanol production from the intermediate products of cellulose hydrolysis is relatively small, and methanol is mainly derived from the intermediate products of cellulose oxylysis.On the basis of this, the aging test of the intermediate product was designed to prove this conclusion.On the basis of the study on the characteristics of methanol produced by cellulose cracking, the life of oil-paper insulation system under laboratory conditions was predicted by establishing the relationship model between methanol and polymerization degree.The results show that with the increase of moisture content in insulator paper, the insulation life is halved, and the aging temperature increases from 8 鈩，

本文編號(hào)：1730005