| Environmental policies and market forces are increasing the pressure for change in the refining industry. Hydrogen demand increases to remove more sulfur in oil products. Simultaneously, to meet the aromatics limits, refineries are reducing the operation load of naphtha reforming, with the result that less hydrogen is being generated. Until 2000, Reforming processes were already unable to supply the sufficient hydrogen to meet the need of hydrotreater and hydrocracker, and about 50%~70% refinery is lack of hydrogen all over the world. To rebalance supply with demand of hydrogen in refineries, a novel approach to the mass integration was investigated more systematically in this thesis which consists of five parts of contents as follows:1. The art-of-state of mass integration was completely reviewed covering through the research scheme to application of integration technology. It was pointed out that mass integration will play a key role in the efficient utilization of resources and waste minimization.2. The units which constitute the hydrogen networks in ZRCC are introduced, including the processes, models and operating data of hydrotreater, hydrocracker, reforming, hydrogen plant and pressure swing adsorption. More attention was paid to hydrotreater flowsheet, for example, the influence of operating condition to reaction; the demand of make-up hydrogen, recycle hydrogen; the purity and usage of high pressure purge, low pressure purge, H2S removed gas and fuel gas produced by hydrotreaters.3. The hydrogen networks is modeled and optimized by the superstructure method. The procedures were described as following, grouping all the hydrogen units into Hydrogen Sources and Hydrogen Sinks, finding and drawing all possible connects between them to build up a superstructure network graph, finally formulating the optimization objective and process constraints. The optimization problem was solved by SQP algorithm. The result obtained is compared with the present hydrogen networks, and shows that the total cost can be reduced by 70.23 million per year.4. The new design scheme for hydrogen purification was proposed on the basis of process integration approach. The widely used PSA, Membrane separation and Cryogenic separation are combined into a superstructure model, which can take advantages of eachone of them. The model of purification units includes flow-sheet expression, investmentcost and operating cost. Result shows that the whole cost can be reduced by 49.37 million per year further if increasing an additional capacity of 12kNm3/h for Membrane separation.5. A sensitivity analysis was carried out for O-H networks which combine the hydrogen sub-networks and oil sub-networks according to the trade-off scheme. The Oil Networks include process, oil allocation and price of crude oil and products. Firstly, the unit which is sensitive to both Oil networks and Hydrogen networks is identified; Secondly, the sensitivity around the operating point of Oil networks and Hydrogen networks to the variations of reaction parameters of units is calculated. Then the optimal point, which can give a maximum overall profit, can be found. Taking hydrocracker and PSA unit as examples, the result shows that refinery can gain an additional profit by more than 5.88million per year if reducing the purity of PSA hydrogen from 99% to 98%, and increasing the purity of make-up hydrogen of hydrocracker from 94% to 97%.
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