Natural Gas Flow and Quantity Measuring Unit which forms a part of the Gas Measuring Station

 

Natural gas flow and quantity measuring unit  forms a part of the Gas Measuring Station and can be placed into the single shelter or into several cabinets. It has been designed to measure and record  both volumetric flow and volume of the natural gas modified to the standard conditions, as well as its qualitative parameters including gas composition, density, humidity, calorific value and Wobbe index.

The Flow Measuring Unit consists of:

• Flow meters with pipeline sections installed on the pipeline assembly.
• Pressure and Temperature Sensors;
• Analytical assembly equipped with analytical equipment – instruments to measure Qualitative gas parameters.
• Automatic Control System that controls Gas Measuring Station .
• Analytical Shelter equipped with life support systems;
• Stop Valve kit with electric drive.

The Pipeline Assembly  includes:

• Flow meters (basic and stand-by). They can be either quick-changed restriction or an Ultrasonic Flow meters.
• Pipes of operating and stand-by measuring pipelines with a pipeline sections installed downstream and upstream the meter.
• Pipeline Stop Valve kit with electric or electropneumatic drive.
• Auxiliary devices (Flow straighteners, sampling probes, measuring instruments etc ).
• Shelter or cabinet for placement of flow meters with pipeline sections, as well as for sensors and transducers that form a measuring unit.

  As a basic meter of the system is applied an Ultrasonic flow meter Flowsic600, configured with a pipeline sections.  
To measure the volumetric flow and gas volume modified to the standard conditions are used flow computers “SuperFlow-21B”, Floboss 107, Floboss 600 and others, equipped with pressure and temperature transducers.
Each pipeline has a stand-by system consisting of 2 sets of pressure and temperature transducers  connected in a cross manner to the flow computers.

Analytical Assembly includes:

• Analitical cabinet  for placement of analytical instruments to measure qualitative parameters of the natural gas, that form a package of the Gas Measuring Station.
• Process Gas Chromatograph PGC 90.50  Chromatograph provides a measurements of the gas composition, calorific value and Wobbe index in   accordance with GOST 31371.7—2008 and ГОСТ 31369—2008.
• Sampling system, sampling conditioning system and the sampling line are designed in accordance with GOST 31370—2008.
• Dew point analyzer on moisture and hydrocarbons. There are 2 analyzers to measure the dew point – Analyzer “Kong Prima” or a Process Laser Analyzer SS2200.  Moisture Analyzer SS2200 can also measure a traces of H2S in the natural gas due to its  dual-channel design.
•  Analzyer to measure sulphourous compounds designed on the basis of chromatograph  РGC 90.50.  The instrument has an Electro=Chemical detector that allows to measure H2S and mercaptans  at the range from 1 to 100.000ppmv
•  Gas density gage  “Solartron”

Automatic Control System provides an automated  acquisition, processing, displaying and registration of  flow and quality gas data, and ensures a safe performance of the whole Gas Measuring Station.

Automatic Control System has a multilevel hierarchical structure and provides a following functions: 

• Automatic measurement of quantity and quality of the natural gas modified to a standard conditions.
• Automatic measurement of gas composition, calorific value, gas density at the normal conditions, and  further data communication to the flow computers.
• Automatic measurement of water and hydrocarbons’  dew point temperature
• Measurement of sulfurous compounds in gas
• Generation of the gas flow and quality report and its further communication to the upper control level.;
• Stop Valves remote control, automatic process control;
• Automatic self-diagnosis of the instrumentation;
• Automation control of  Emergency and life-support systems installed in the analytical shelter.

Program-technical complex of Automatic Control System is integrated in the operator’s room, and consists of:

• Cabinet for flow computers that includes programmed logic check of ACS with input-output modules, matching units and flow computers, interface units of the moisture analyzers;
• Cabinet of Emergency system equipped with  auxiliary devices of the automated fire alarm system and gas contamination control system.
  
• Cable Distribution Cabinet with automatic circuit breaker, protective cutout device, static protection device.
  Hardware bay with mounted process computer, workstation (basic and stand-by) and uninterruptible power supply with a set of rechargeable batteries.