The economic range from the CNG pressure regulating station to the gas filling mother station is within 300 kilometers, generally not exceeding 500 kilometers, with a supply scale of 2000-8000 households. The suitable gas supply volume is 10-5000 Nm³/h; both too large or too small will increase the unit gas cost. This system has a small investment scale for long-distance pipelines, a short construction period, and quick capital recovery, and can serve as a peak-shaving and backup gas source for the pipeline network in the future.

Introduction to CNG Pressure Regulating Station Technology

Low-pressure or medium-pressure natural gas is compressed by a compressor to 20 MPa and stored in specially designed steel cylinders or bundles placed on a trailer with traction mechanisms. The trailer transports compressed natural gas to the supply station, where it enters the CNG pressure regulating equipment through an unloading system. The high-pressure natural gas is reduced to the required pressure for users through a gas pressure reduction skid into the delivery pipeline network. The pressure reduction device in the skid generally has two paths, one active and one standby, with each path using two-stage pressure regulation; the heat required for pressure reduction is provided by water circulation heaters or electric heating systems: CNG imports use general single-path or multi-path imports where each path can be equipped with two or more unloading columns for simultaneous unloading. When the tank truck's pressure is low, it can bypass for easier switching of tank truck usage.

Introduction to CNG Pressure Regulating Station Structure

The compressed natural gas pressure regulating station is divided according to the layout of equipment within the station and its functions into: unloading system (high-pressure hoses, quick-connect fittings, high-pressure valve vent heads, etc.), pressure regulation and heat exchange system (high-pressure emergency shut-off valves, heat exchangers, first and second stage regulators, first and second stage safety valves), measurement system (flow meters), control system (central control console), heating system (gas boilers, hot water pumps, electric heaters, etc.). First, high-pressure natural gas from inside the vehicle enters through the unloading system into the CNG reduction skid heat exchange system and regulation system. The gas undergoes two heating processes and two pressure reductions before being measured by flow meters and odorized before entering the pipeline network. The heating system provides necessary heat during gas pressure reduction while the control system monitors the entire setup.

Pressure Regulation Process

A. Two-stage Pressure Regulation Process: First connect using high-pressure hoses and quick-connect fittings to link with steel tank trucks; compressed natural gas enters through ball valves and high-pressure shut-off valves into a first-stage heat exchanger where it is heated before passing through a first-stage regulator reducing it to 1.0-4.0 MPa. It then goes through a second-stage heat exchanger for further heating before being regulated down to 0.1-0.4 MPa by a second-stage regulator before entering flow meters for measurement; finally odorization occurs before inputting into medium-pressure pipelines. All levels of gas pressures, temperatures, flow rates, water temperatures, key valve controls as well as switching between paths are interlocked controlled by central control console.

B. Three-stage Pressure Regulation Process: First connect using high-pressure hoses and quick-connect fittings with trailer-mounted steel tank trucks; compressed natural gas enters through ball valves and high-pressure shut-off valves into a first-stage heat exchanger where it is heated before passing through a first-stage regulator reducing it to 2.5-4.0 MPa; then after going through a second-stage heat exchanger it gets reduced again by a second-stage regulator down to 1.0-1.6 MPa before entering flow meters for measurement; after that it goes through three stages of regulation down to required downstream pressures followed by odorization before being supplied to end users of natural gas. All levels of pressures in gases at various stages along with temperatures, flow rates as well as key valve controls are interlocked controlled via central control console.