本文選題：液化天然氣　切入點(diǎn)：冷能　出處：《華南理工大學(xué)》2015年碩士論文

【摘要】：隨著我國能源供需矛盾日益緊張,LNG進(jìn)口量逐年增大,合理利用LNG冷能顯得愈加重要。然而,目前我國的LNG冷能利用項(xiàng)目中仍存在著一些技術(shù)癥結(jié)阻礙產(chǎn)業(yè)發(fā)展。LNG接收站輸氣負(fù)荷會由于下游用戶的用氣波動而頻繁變化,夜間用氣低谷時(shí)LNG的氣化量很少,甚至停止氣化,致使LNG冷能利用裝置冷量中斷而不能連續(xù)穩(wěn)定運(yùn)行。本文以LNG冷能空分裝置為研究對象,探尋LNG接收站輸氣負(fù)荷波動與冷能空分系統(tǒng)的適配性方案。本研究可解決LNG輸氣負(fù)荷與空分裝置冷能需求在時(shí)間上不同步問題,為LNG冷能空分裝置的連續(xù)穩(wěn)定運(yùn)行提供指導(dǎo),同時(shí)可為國內(nèi)其它冷能利用項(xiàng)目的建設(shè)提供有力的理論依據(jù)和技術(shù)支撐,促進(jìn)我國LNG冷能利用產(chǎn)業(yè)發(fā)展。應(yīng)用Aspen Plus化工流程模擬軟件,建立LNG冷能空分工藝模型,首先對冷能空分裝置的冷能需求、火用效率、多工況運(yùn)行特點(diǎn)進(jìn)行研究,然后探尋LNG輸氣負(fù)荷與冷能空分裝置的適配性方案。LNG冷能空分裝置正常工況下需要55.3t/h的LNG提供氣化冷量,該流程液體產(chǎn)品單位能耗為0.41k Wh/m3,相比于傳統(tǒng)流程約1.00k Wh/m3的單位能耗降低了約60%,節(jié)能優(yōu)勢明顯。LNG冷能空分裝置總體火用效率為38.1%,其中制冷系統(tǒng)火用損失最大,但與傳統(tǒng)空分制冷系統(tǒng)相比有大幅度降低。當(dāng)LNG冷能在一定范圍內(nèi)波動時(shí),可以采用降低空分裝置負(fù)荷率、改變產(chǎn)品分布等操作方式應(yīng)對。而當(dāng)LNG冷能供應(yīng)出現(xiàn)中斷時(shí),針對冷能空分裝置因此頻繁停車的問題,提出了基于外置冷箱液氮冷媒回流供冷的方案,維持冷能空分裝置連續(xù)運(yùn)行。通過計(jì)算,LNG冷能供應(yīng)中斷時(shí),采取該適配性方案需要消耗14.62t/h的儲罐液氮,且該方案下的單位能耗為0.63k Wh/m3,相比于冷能供應(yīng)正常工況下約0.41k Wh/m3的單位能耗有所升高。此外,對該方案進(jìn)行經(jīng)濟(jì)效益分析可知,若LNG冷能供應(yīng)中斷時(shí)間在12個(gè)小時(shí)以內(nèi),采取液氮冷媒回流供冷方案更加合適,相較于直接停車收益情況有明顯改善。
[Abstract]:With the increasing shortage of energy supply and demand in China, the rational utilization of LNG cold energy is becoming more and more important. At present, there are still some technical sticking points in the cold energy utilization project of LNG in China. The gas transmission load of the LNG receiving station will change frequently because of the fluctuation of the gas consumption of the downstream users, and the gasification capacity of the LNG will be little or even stopped at the low point of the night gas consumption. As a result, the cold energy of LNG is interrupted by the cooling rate of the device and can not run continuously and stably. In this paper, the cold energy air separation unit of LNG is taken as the research object. In order to find out the suitable scheme of gas load fluctuation and cold energy air separation system of LNG receiving station, this study can solve the problem that LNG gas transmission load and cold energy demand of air separation unit are out of sync in time, and provide guidance for the continuous and stable operation of LNG cold energy air separation unit. At the same time, it can provide strong theoretical basis and technical support for the construction of other cold energy utilization projects in China, and promote the development of LNG cold energy utilization industry in China. Using Aspen Plus chemical process simulation software, the LNG cold energy air separation process model is established. First of all, the cold energy demand, exergy efficiency and multi-condition operation characteristics of the cold energy air separation unit are studied. Then the suitable scheme of LNG gas transmission load and cold energy air separation unit is explored. Under normal condition, the LNG of 55.3t/h is needed to provide gasification cooling capacity. The unit energy consumption of liquid product in this process is 0.41k / m3. Compared with the traditional process, the unit energy consumption of 1.00k Wh/m3 is reduced by about 60. The energy saving advantage is obvious. The overall exergy efficiency of the cold energy air separation unit is 38.1, among which the exergy loss of the refrigeration system is the biggest. When the cooling energy of LNG fluctuates within a certain range, it can be handled by reducing the load rate of the air separation unit and changing the product distribution. When the cold energy supply of LNG is interrupted, In order to solve the problem of frequent shutdown of cold energy air separation unit, a scheme of reflux cooling with liquid nitrogen refrigerant is proposed to maintain the continuous operation of cold energy air separation unit. When the cold energy supply of LNG is interrupted, It needs to consume liquid nitrogen with 14.62t/h, and the unit energy consumption of this scheme is 0.63 k / m ~ (3), which is higher than that of 0.41 k / m ~ (3) when the cold energy supply is normal. In addition, the economic benefits of this scheme are analyzed. If the cold energy supply of LNG is interrupted for less than 12 hours, it is more appropriate to adopt the liquid nitrogen refrigerant reflux cooling scheme, which is better than the direct parking profit.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ116.11

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