The Study On Recovery And Utilization Of Low-temperature Waste Heat In Aromatic Hydrocarbon Unit

Energy saving,environmental protection and sustainable development have become the trend of social development today.On the basis of developing excellent technology and applying advanced equipment,how to rationally use limited resources and tap potentials to increase efficiency is an effective means for refining and chemical enterprises to improve their competitiveness.Compared with the international advanced level,the overall energy consumption of China's refining and chemical enterprises still has a lot of room for improvement,and there are many process units of aromatics combined plants,complex processes,and energy consumption accounts for a large proportion of the entire plant,which is the main reason for high energy consumption One is that a large amount of low-temperature waste heat resources in the device are not fully recycled.Therefore,the full and effective recovery of low-temperature waste heat has become an important aspect of energy saving and consumption reduction in aromatics combined plants.The paper analyzes some difficulties in the current low-temperature waste heat recovery and utilization of domestic oil refining enterprises,on the basis of introducing the process characteristics of the aromatics combined plant and the low-temperature heat recovery and utilization technology overview,combined with the specific cases of the two companies,how to efficiently recover low-temperature heat Economic analysis.From the perspective of overall planning,the paper combines pinch technology and Aspen Plus process simulation software to analyze the energy consumption status of the device,select the appropriate waste heat recovery and utilization method,propose an optimization plan,and calculate the heat exchange and heat exchanger selection after optimization and transformation.The key data is to build corresponding facilities,reduce the operational fluctuations caused by experience adjustment,and realize the low-temperature thermal joint utilization between the units of the aromatics combined device and between the aromatics combined device and other device systems,while reducing the quality of the products.Established a low-temperature hot water recovery and utilization system in Enterprise A,and proposed optimization measures such as supplying heat to the bottom reboiler of other installations,utility engineering systems,and the use of lithium bromide refrigeration technology to recover low-temperature heat.The gas consumption is reduced by 406.3kg/h,saving 48t/h of low-pressure steam,and the energy consumption is reduced by about 15% relative to the original design value;B company recovers low-temperature waste heat from the top of the tower to produce low-pressure steam,and the energy-saving economic benefit is 5.5 million per year.