Simulation And Energy Saving Research Of SSOT Device

SSOT is single-stage hydrocracking through a fixed catalyst bed. The reaction ofthe process is under high temperature and pressure, which partly leads to the highenergy-consumption of the device; the rationality of the heat exchanger network andthe process affects the energy consumption and the economy of the device. Therefore,the heat exchanger networks optimization by pinch technology and attempt of processaltering can provide reference for the future process optimization and energy saving, ithas great significance and realistic meaning.Firstly, according to the actual production data of a SSOT device, the processmodel was established based on material and energy balance, then it was calculated.The mathematical models of the main operating units were established, includingreactor, distillation tower, absorption tower and heat exchangers. As to the differentsections of the process, we selected the GRASON and PENG-ROB state equation forthe models’ calculation and applied the sequential modular approach to simulate thewhole process. Then the process model was solved, and the simulated results werecompared to the production data, which showed that the average relative errors werewithin5%. The simulation results were in agreement with the practical data. Themodel had a high precision and could provide reference for the future processoptimization and energy saving.Secondly,20streams’ physical properties data were extracted as the basis data forenergy saving. The energy target was calculated with pinch technology and the MERnetwork was designed. Then an energy-saving scheme was proposed based on theMER network. After simulating the sheme the energy consumption was analyzed, thecold utilities could save the amount of35.50%, while the hot utilities35.48%. Thenunder the premise that the original device was changed as less as possible, we analyzedthe existing heat network; proposed an energy scheme, which could eliminate someheat exchangers that were against the pinch rules. After simulating the sheme theenergy consumption was analyzed, the cold utilities could save the amount of20.85%;while the hot utilities30.70%.Lastly, for the shortcutting of the cold-high separation process of the existingSSOT device, the gas-liquid separation process was transformed into hot-high separation process that could save more energy. Under the premise that thetransformation had no impact on the follow-up gas-liquid separation systerm, theprocess operation parameters of the added equipments were determined. The energyconsumption of the devive after process altering was obtained, the cold utilites couldsave the amount of30.74%; while the hot utilities27.48%.