Energy flow analysis and distribution optimization of distributed energy system for a multi-purpose station of oilfield

In order to realize the cascade utilization of natural gas in the multi-purpose station of oilfield and improve the recovery of waste heat from the oilfield wastewater, an energy consumption model that combines natural gas power generation and the waste heat recovery of flue gas and wastewater was proposed for the problems of low waste heat recovery of the wastewater in a multipurpose station and the irreversible energy loss in the gas gathering system of Shengli Oilfield. Meanwhile, a distributed energy system was built for the multi-purpose station based on waste heat recovery of natural gas power generation. Besides, an energy flow model of a gas internal combustion engine was established. With the model, the thermodynamic simulation was carried out by changing the generation power of internal combustion engine and the outlet temperature of crude oil, and its influence on heat supply and heat pump COP was analyzed with the system efficiency method, to determinethe appropriate operating parameters of the internal combustion engine. Further, energy flow analysis was carried out for the whole distributed energy system with the pinch analysis method based on the energy flow model of class-I absorption heat pump for secondary combustion of flue gas. On this basis, the weak points of system energy consumption were determined and optimized. Finally, the optimization results were evaluated through exergy analysis, and the reasonability of energy flow analysis optimization was verified with the pinch technology. According to the optimization results, the reasonable range of the pinch-point temperature difference of the distributed energy system of the multi-purpose station is 10-12 K, and the energy saving potential reaches 29.2%. Generally, the research results could provide a good theoretical guidance for the energy saving and consumption reduction of multi-purpose stations as well as the efficiency maximization of energy utilization.