Development of a mathematical model to simulate a natural gas compression system and its anti-surge control to improve performance: A case study to reduce the energy consumption, and the environmental impact

Abstract

Compression systems are extensively used in the petrochemical industry. They are very intensive energy consumers, and simulation and analysis of this process are vital for their better maintenance and limiting their energy consumption. Here we follow an industrial case study to model and simulate a compression loop of the petrochemical industry and show potentials for energy savings and environmental improvements In this paper we introduce a modular quasi-one-dimensional model to simulate a two-step seven-stage compressor and all components of the compression loop, including the surge control system. For each component, including pipes, separation drums, heat exchangers, and compressors, a thermodynamic model based on the mass, momentum, and energy conservation laws is obtained, then each component of the system can be presented as an independent module. By stacking all modules together, the entire compression system is modeled. Finally, a numerical simulation is performed for many different scenarios to study the behavior of the surge phenomenon, the surge control system, and especially the effects of the intentional anti-surge valve openness for extra surge margin, which results in huge energy loss and environmental impacts. This simulation shows that removing the intentional openness of the anti-surge valves will reduce about 15.8% of the CO2 emissions, and the power consumption required to run the turbine may be reduced up to 1.8 MW.

Keywords

• Anti-surge control system
• Surge control line
• Wasted cost
• Compressor map
• Emission production