Automated gas distribution station

PURPOSE:

Automated gas distribution station is provided for reduction of gas pressure coming from trunk and local distribution pipelines followed by gas supplying into gas system.

Automated gas distribution station main functions: 

• gas purification from condensed moisture and mechanical impurities succeeded by removal of purgings;
• gas heating – up before gas pressure reduction;
• gas pressure reduction in trunk pipeline up to required pressure and maintaining the pressure at given level with accuracy requirement;
• odorizing of gas supplied to a consumer;
• gas consumption commercial records;
• automatic control of Gas distribution station process equipment operation mode automated control with remote issuance of emergency and warning alarm signals to Control Room or Dispatch Center;
• data communication with upper level of automation systems of information.
  

Automated gas distribution station is designed for operation in various climatic conditions. While ordering the station, certain climate conditions for operation of Automated gas distribution station shall be specified in data sheet. 

All process equipment of standard design of Automated gas distribution station and automation equipment are placed in individual packages (modules) with gas-proofed walls. 

Standard Automated gas distribution station package consist of the following: 

• switching over package;
• gas pressure reduction package along with gas purifying package;
• gas consumption accounting system;
• instrument package with two bays (Control Room, Workshop premise);
• automated gas heater;
• limiting values protection, monitoring and control system;
• gas odorizer.

Standard set of Automated gas distribution station package is represented as metal structures installed on heated basements and faced with sandwich panels with non-combustible insulant. Composition and quantity of packages can be different from standard Automated gas distribution station package, if required. In this case Automated gas distribution station configuration and design options and delivery of additional equipment are specified in a data sheet or in a station fabrication contract. 

1. Switching – over package composition:

• bypass line;
• air operated drive ball valves;
• safety valves unit;
• impulse gas preparation unit;
• natural and blowing ventilation system;
• security alarm system;
• gas level monitoring system and fire alarm system;
• instrument sensors and signaling equipment;
• electric lighting;
• electric heating (if required).

2. Pressure reduction package composition: 

• gas purifying unit with two filters (main and spare) and receiver (automated discharge of condensate to drain tank);
• two lines of reduction (main and spare) on the basis of regulator with shutdown device or two regulators installed successively;
• unit of gas reduction for own needs;
• impulse gas preparation unit;
• blowing ventilation system;
• security alarm system;
• gas level monitoring system and fire alarm system;
• instrument sensors, actuating devices, signaling equipment;
• electric lighting.

3. Instrumentation package composition:

• ventilation, conditioning and lightning system;
• cabinets to allocate the equipment of automatic control system, devices, communication systems, servers and commutation switch, cabling and monitoring and protection systems;
• automated workstation (AW) for visualization, remote control and Automated gas distribution station processing control;
• gas supplier and consumer communication system;
• workshop building for maintenance activities;
• electrical equipment (power supply board, uninterruptible power supply, voltage control).

4. Gas metering station consists of: 

• sensing lines located in a separate package or on an outdoor area;
• primary instruments of pressure control, pressure differential, temperature and other process parameters;
• upstream/downstream isolation valves on sensing lines;
• cables providing the data transmission to Automated gas distribution station Control Room;
• in case of allocation of a gas metering station on outdoor area, gas consumption estimator (or corrector) shall be installed in package of gas reduction or in thermally insulated cabin.