Objective  The aim is to solve the low-power problem of differential pressure generators and optimize the process parameters.

Method  Firstly, exergy loss of a turbine expander could reduce 42% of external exergy loss through conventional exergy analysis and advanced exergy analysis, which indicates that improper operating parameters had led to high exergy loss. Secondly, the response surface method was used to analyze and optimize operation parameters. 13 groups of test data were designed with inlet and outlet pressure ratio, inlet temperature and natural gas volume flow rate as factor variables, and generation power and total exergy loss as response values.

Result  Exergy loss was most significantly affected by the interaction between inlet and outlet pressure ratio and natural gas volume flow rate, and the total exergy loss was significantly effected by the interaction between the inlet and outlet pressure ratio and the natural gas vloume flow rate. Based on this, a stratege of parameters optimization was proposed by increasing the inlet and outlet pressure ratio and the natural gas volume flow rate, and reducing the inlet temperature. Adjust the field parameters according to the optimized process parameters: when the inlet and outlet pressure ratio was 1.38, the inlet temperature was 30.7 ℃, the volume flow rate of natural gas was 110×10³ m³/h, the generation power reached 625.3 kW and overall exergy loss decreased by 180.9 kW. The avoidable external exergy loss decreased by 104.4 kW when the turbine exergy efficiency increased to 72.3%. The economic benefit of the device is increased by 1.145 million yuan per year, and the CO₂ emissions were reduced by 1 109.5 t/a.

Conclusion  Advanced exergy analysis and response surface analysis can be popularized for all types of complex natural gas processing processes. Advanced exergy analysis can first quantify exergy improvement potential. If the avoidable external exergy loss ratio is high, response surface method can be applied for further parameters optimization.