A Novel Low-Pressure Release Method Based on Inlet Regulation for Users with Low Demand Scenario

Due to the mismatch between gas production and consumption in the gas delivery system (GDS), reduced customer demand can easily lead to overpressure and gas release. Companies mainly use high-pressure release (HPR) to lower the GDS pressure, which results in significant energy losses for compression and gas separation. This paper (1) proposes a low-pressure release method (LPR) for users’ low-demand scenarios to avoid regulating air separation units, and (2) provides a way for obtaining optimal parameters for LPR when used alone and together with HPR. LPR released low-pressure gas by lowing the compressor inlet guide vane opening (IGA) or the inlet valve opening to reduce the compressor load, outlet pressure, and GDS pressure, and reduce the energy consumption of the compressor. Case studies showed LPR reduced effectively the gas emissions and compressor operating energy. When LPR is used alone, the maximum reduction in gas emissions and compressor operating energy consumption compared with HPR was $\mathrm{6,049}{\mathrm{Nm}}^3$ and $900\mathrm{kW}·\mathrm{h}$, accounting for 62.96% and 2.18%, respectively, and the gas emission rate was reduced from 0.11% to 0.04%. When LPR was used together with HPR, 43.88% oxygen emissions and 0.28% total compressor energy consumption were reduced, and the total conditioning time can be effectively reduced from 42 to 10 min. The method increases the ability of the compressor to regulate the GDS.