Comparative Evaluation of the Compressor-Ejector Unit’s Designs for Gas Evacuation During Repair of the Main Gas Pipeline

In the process of main gas transportation, repair work is periodically necessary. In some cases, it includes a long length section’s isolation and emptying the internal space of the pipeline. According to established practice, in order to reduce the total duration of repair work, gas from the isolated section is blew out to the atmosphere. This leads to losses of significant volumes of natural gas. In order to save resources, ejectors can be used to pump gas into a parallel gas pipeline. They provide deeper vacuum. Due to the pressure decrease in the isolated section, it is necessary to provide a high efficiency of the pumping unit. A comparison of versions with the gas blowing to the vent stack and evacuation to a parallel gas pipeline by various designs of the compressor-ejector unit is proposed (standalone ejector, ejector with different compressor positions). The unit operating parameters are determined using Schlumberger OLGA. A graph of the change in time of the evacuated volume of gas, reduced to standard conditions, and the pressure for various parameters of the compressor and its location relative to the ejector is plotted.