| At present, the production of clean gasoline is one of the main tasks of the refiners, namely the requirements of high octane number, low vapor steam pressure, low sulfur, low aromatic, low olefins. The isomerization reactions of C5/C6 paraffin(light naphtha) which are taking place in a hydrogen atmosphere, over the strong acid catalyst that contains noble metal platinum, convert straight chain alkanes into their branched isomer, which is called the isomerate product. The isomerate product is low sulfur,non-aromaticity, non-olefin, and the maximum RON is 92,what is more it is significantly helpful to increase the antiknock index as a result of the small difference between RON and MON which is only 1 to 2. Meanwhile it can help to adjusting the front-end octane number of gasoline, and make the gasoline octane number distribution more reasonable, so as to improve the engine starting performance. It is the ideal components of clean gasoline. So that the C5/C6 paraffin isomerization technology becomes a good choice for the refiners. In this paper it takes the technological process of a large oil refinery isomerate product as basis to discuss the selection of technology, process principle, the main reaction factors, process flow, operating conditions, material balance and equipments, etc..First, the properties of product in C5/C6 paraffin isomerization unit were studied. When C5/C6 paraffin isomenzation unit product was blended into the gasoline,the gasoline indexes were not affected except RON, so product RON became the main indicators of the isomerization unit. According to the composition of the gasoline pool, the type, the quantity and the standard of the product of gasoline, the RON of the product was determined to be 85. Then the main flow process of C5/C6 paraffin isomerization was studied. According to the properties of the feed and the product requirements, the process of C5/C6 paraffin isomerization unit was determined including prefractionation section, feed treatment section, H2 treatment section, isomerazation reaction section, stabilizer section and caustic scrubber section. Finally, HYSYS simulation software was applied to simulate and optimize the prefractionation section and the steam system in C5/C6 paraffin isomerization unit. The best operating conditions of Deisopentanizer were determined:the theoretical plate number was 40, top temperature was 67.4 ?; the bottom temperature was 85.1?; the reflux ratio was 8.18. With prefractionation section the investment could be save by 14401400 yuan. The whole process of C5/C6 paraffin isomerization process is simulated, and the isomerization reaction is simulated by HYSYS. The operating conditions of the main equipments in the process flow of C5/C6 paraffin isomerization are finally determined. By the study of the steam system optimization it was indicated that step by step flashing system could save operating cost by 3540000 yuan per year, cross stage flashing system can save operating cost by 3320000 yuan per year. Step by step flashing system equipment investment was higher than cross stage flashing system by 151800 yuan, but the operating cost was 22 million yuan per year lower. Step by step flashing system had a better economic performance, and step by step flashing system should be applied. The process of C5/C6 isomerization process studied in this paper, meet the requirements of the product, the process is reasonable, the energy consumption is lower than the similar process technology, and the waste emissions meet the national standard requirements.. |
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