How to set up combustible gas detection points in natural gas compressor rooms

Whether it is a centrifugal compressor or a reciprocating compressor, the inlet and outlet pipelines of the natural gas compressor will be restricted to a certain area. Specifically, the inlet and outlet pipelines of the centrifugal compressor will be distributed in two areas with the inlet and outlet flanges of the compressor as the boundary points, and the distribution area of ​​the release source (such as flanges, connecting joints, etc.) will generally be controlled within a circular range with a radius of 5m. For reciprocating compressors, the release source range may be more concentrated. It should be noted here that the distribution range of the release source of the reciprocating compressor should also consider the existence of the release source of the inlet and interstage liquid separation tank process system.

Based on the analysis results of the combustible gas leakage status and the above description of the distribution of release sources, various models of leakage of each release source in the natural gas compressor room can be easily established, and it can be clearly seen that these models will have a common intersection area. This area can be understood as the common impact point of combustible gas leakage in the natural gas compressor room, and this common impact point can be determined as the combustible gas detection point.

The common impact point can be determined by outlining a cone with the center point of the top exhaust port of the compressor room and the circular area of ​​the release source distribution. When the radius of the bottom surface of the cone is less than or equal to 5m, the combustible gas detector should be installed 2m away from the bottom surface of the cone axis. When the radius of the bottom surface of the cone exceeds 5m, it can be covered by multiple circular areas with a radius of 5m, and multiple cones can be formed with the center point of the top exhaust port. In fact, it is impossible for any compressor room to have more than two circular areas (two cones) with a radius of 5m in one release source area, which suggests that the area can be detected by two detection points.

The setting of combustible gas detectors in natural gas compressor rooms should also fully consider the situation where the release source at the edge of the detection area sprays outside the area and other situations that are not conducive to detection. However, in any case, regardless of the leakage rate, the released combustible gas will migrate and diffuse to the exhaust port under the action of the top mechanical exhaust, but the combustible gas concentration in this part may be very low. Therefore, a combustible gas detector can be set 0.51.0m below the exhaust port, but the alarm concentration setting must be lowered, which can be set to 10% LEL.