The "metering skid" consists of redundant PLC PLC control cabinets, flow meters, control valves, regulating valves, pressure gauge transmitters, flame arresters, bimetal thermometers, and toxic detection gas skid component systems configured and tested.

The trade metering handover of the metering skid system adopts a mass flowmeter, and the control valve adopts a straight stroke pneumatic regulating valve.

The entire metering skid control management system is set up at the project site.

Industrial gas/liquid metering will become more precise, intelligent and automated.

Gas/liquid metering is an important part of ensuring quality and safety. The design of the metering sled is particularly important, and factors affecting the metering accuracy and system stability need to be fully considered. Therefore, the following elements need to be considered when designing:

1. Loop design: Small loops are set for important equipment, and the entire system must have a large loop.

2. Instrument selection: Select a high-precision mass flowmeter (gas accuracy ±0.15%, liquid accuracy ±0.1%).

3. Control mode: According to process requirements, flexibly set flow PID adjustment, pressure PID adjustment and manual mode under special circumstances to ensure stable control flow and pressure.

Logical settings:

In addition to the regular monitoring of pressure and temperature instruments and PLC working status monitoring, there is an additional

1) Adopt two-out-three pressure interlock;

2) Adopt three-out-of-three pressure PID stable adjustment;

3) Adopt a two-out-three emergency stop button interlock to prevent single contact failure and cause parking;4) Linkage with online analyzer data to ensure that the gas composition is qualified and ensure the reliability of gas supply;5) Set flow alarms and pressure alarm interlock.

4. Redundancy settings:

1) The skid power supply adopts dual power supplies;

2) The control system adopts thermal redundancy controller, which can achieve thermal redundancy of CPU

, channel redundancy,

When the main channel fails, it automatically switches to the standby channel to ensure system stability.

5. Electrical cabinet selection: Adopt a positive pressure explosion-proof cabinet, and the pressure inside the cabinet is controlled at 200pa and 600pa. The system controls automatic pressure compensation in the gas path through modules. The electrical cabinet is equipped with a vortex tube cooler to convert instrument air and replenish cold air into the cabinet. The temperature inside the cabinet is controlled at around 25℃. It is also equipped with an insulation layer made of polyurethane material and has a thickness of 20 mm.

The cabinet body is made of stainless steel and has a gas explosion-proof rating Ex db eb ib mb pxb IIC T6 Gb/dust explosion-proof rating Ex ib mb pxb tb IIIC T80℃ Db.

6. Provide TSG supervision and inspection certificate for the entire skid.