Turbine / ultrasonic metering system is a skid-mounted metering
system for custody transfer metering in the metering station of long distance gas pipeline. The system
integrates the functions of filtering (or the filtering part is
separated), metering, flow ratios, on-line calibration, system
venting, leak alarm and automatic switching, having the characteristics of high metering accuracy, good safety
performance, continuous stable metering and high explosion proof
requirement.
This system is composed of some subsystems, such as filtering
system, metering system, flow ratios system, gas chromatograph analysis system, on-line calibration
system, venting system, gas leak alarm system and etc. The accuracy
of the filtering system is much more strict comparing to in other
situations,besides gas turbine flowmeter or gas ultrasonic
flowmeter, straight pipe meeting the requirement and suitable flow
computer for temperature and pressure compensation calculation are
used in the metering system. On-line type gas chromatograph detects
the gas components. Two or more flowmeters series to achieve
intercomparison,what is flow ratios. According to processing
requirement ,on-line calibration system reserves on-line
calibration port in the system. Gas leak alarm system can be
interlocked with the main valve and venting system. When the
leakage occurs in the operation field, the station control system
will command the main valve to close and open the venting system to
carry on the emergency venting.
High requirements for the flowmeter, straight pipe, gas analyzer
and flow-straightening vane in the system.And, the upstream and downstream shut-off valve of
the flowmeter are critical, requiring zero leakage.Technical level
of the manufacturer and installation accuracy affect the accuracy
of the metering system directly. The above mentioned rules are the
basic requirements to ensure the accuracy of the metering system.
System Characteristics
- Using gas turbine flowmeter or multi-path gas ultrasonic flowmeter
as the mainstream gas flowmeter
- The accuracy of the meter is better than ±0.5%,while the accuracy of the metering system is
better than ±1%
- Adopting the plate or tube flow-straightening vane
- Finish machining of the straight pipe inner boring
- Zero leakage in the metering system
- Transmission,remote control, automatic switching and flow
centralized management can be realized
