Ethylene-Derived Process Design and Integration:Case Studies of Ethylene Oxide and Styrene Monomer
換熱器網路 ； 本質安全設計 ； 爆炸界線 ； 乙二醇 ； 環氧乙烷 ； 苯乙烯 ； heat exchanger network ； inherent safe designs ； explosion limits ； ethylene oxide ； styrene
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熱能整合自能源危機開始受到重視，而能源價格飆漲後，如何有效地增加製程上的能源使用效率，在程序設計中成為一個重要的課題。 「環氧乙烷」和「苯乙烯」都是最重要的石化基本原料－乙烯的衍生物。「環氧乙烷」用於製造乙二醇 (主要是用於抗凍劑)。它也常用於製造環氧乙烷的衍生物，包括高分子量或低分子量聚合體做為許多用途，例如，清潔劑的添加劑。苯乙烯用以製造苯乙烯聚合體，它的用途很廣泛，是作為合成多種塑膠產業和橡膠產業重要的中間原料。在本質安全設計中，因環氧乙烷有很廣範圍的爆炸界線3-80%，吾人需注意反應器的設計。另外，值得一提的是苯乙烯單體在高溫時會自發性的聚合，因此吾人需將產物溫度維持在低於125℃。 本論文針對兩個製程進行研究：「環氧乙烷程序」與「苯乙烯單體製程」。環氧乙烷製程屬於化學程序中重要的氧化反應；苯乙烯製程則包含了化學反應的兩個重要反應，即乙烯的烷化反應 (為放熱反應，可用來製造蒸汽) 與乙苯的脫氫反應 (為吸熱反應，需用到蒸汽)，兩個製造單元之間理應有熱能整合的設計。論文中主要使用兩套程序軟體：首先AspenPlus進行製程設計與模擬，其次使用SuperTarget進行狹點分析和換熱器網路合成。觀察兩個個案的研究結果在公用設施的需求量上皆比原始設計為少，所以能夠有效的降低成本與節省能源。在兩個個案研究中環氧乙烷製程 (ΔTmin＝10℃) 和原始設計比較，在熱公用設施節省34％而冷公用設施節省25%；苯乙烯製程 (ΔTmin＝10℃) 的乙烯烷化反應部份和原始設計比較，在熱公用設施節省70％而冷公用設施節省63%；乙苯脫氫部份和原始設計比較，在熱公用設施節省30％而冷公用設施節省3%；苯乙烯單體整個製程中選取合適的冷/熱物流進行熱能整合和原始設計比較 (ΔTmin＝10℃)，在熱公用設施節省65％但冷公用設施沒有。
Since energy crisis, heat integration has become one of the important issues in the process systems engineering. Due to the price of energy is constantly rising, how to increase the efficient use of energy in the process has also become of great importance in the field of process design. Ethylene oxide and styrene are both derived from the most basic and important building block of petrochemicals, i.e., ethylene. Ethylene oxide is a chemical used to make ethylene glycol, which is the primary ingredient in antifreeze. It is also used in the manufacture of ethylene-oxide derivatives (EOD), including both of the low molecular and high molecular polymers for use in many applications such as detergent additives. Styrene is the monomer used to make polystyrene, which has a multitude of uses, and has been an important intermediate chemical in the plastics industries and rubber industries. In terms of inherent safe designs, since ethylene oxide has a very wide range of explosion limits－3-80%, we have to pay attention to the design of reactors. It is also worth mentioning that the styrene product can spontaneously polymerize at higher temperature, it is necessary to maintain the product temperature below 125℃. In this thesis, we have carried out two case studies: one is “ethylene oxide process”, and the other is “styrene monomer process”. Ethylene-oxide process belongs to an important category as oxidation in the chemical industries. Like most ethyl benzene/styrene facilities, there is significant heat integration between the two plants. The ethyl benzene reaction is exothermic, so steam is produced, and the styrene reaction is endothermic, so energy is used in the form of steam. Both of the two cases were simulated first by using AspenPlus. Then, heat- exchanger network designs were synthesized and analyzed by using SuperTarget. Significant utility savings were achieved for both of the two case studies. The hot utility savings is 34% and cold utility savings is 25%, as compared with the base-case design, for the ethylene-oxide process with a minimum approach temperature of 10℃. While the hot utility savings is 70% and cold utility savings is 63%, as compared with the base-case design, for the alkylation reaction (exothermic) of the styrene process with a minimum approach temperature of 10℃, the hot utility savings is 30% and cold utility savings is 3%, as compared with the base-case design, for the dehydrogenation reaction (endothermic) of the styrene process with the same minimum approach temperature. Finally, if we take appropriate cold/hot streams for heat integration from the whole styrene process, we found the hot utility savings is 65% but no cold utility savings with a minimum approach temperature of 10℃.
工程學 > 工程學總論
工程學 > 化學工業