Liquefied natural gas (LNG) is natural gas, predominantly methane, that has been cooled down to liquid form for ease and safety of storage and transport. It takes up about 1/600th the volume of natural gas in the gaseous state.
A complete LNG liquefaction plant includes three systems: process system, instrument control system and utility system. According to the different air sources, it can be changed.
The process system of cryogenic LNG Plant includes:
- Feed gas filtration, separation, pressure regulation and metering unit;
- Feed gas pressurization unit
- Pretreatment unit (including gas deacidification unit, dehydration and heavy hydrocarbon removal unit, mercury and dust removal);
- MR proportioning unit and MR compression cycle unit;
- LNG liquefaction unit (including denitrification unit);
Here, we introduce the instrument control system of LNG plant.
In order to effectively monitor the production process of the complete set of equipment, ensure reliable operation, and facilitate operation and maintenance, the instrument control system of the system mainly includes: distributed control system (DCS), instrument safety system (SIS), fire and combustible gas detection and alarm system (GDS), video monitoring system (CCTV), and high-precision instruments (flowmeters, analyzers, temperature, pressure, flow) that meet the process requirements, etc., providing complete configuration, commissioning, and monitoring functions, including process data Acquisition, closed-loop control, equipment operation status monitoring, alarm chain and service, real-time data processing and display, trend service, graphic display, operation record report service and other functions. When there is an emergency in the production device, or when the GDS system sends out an alarm signal, the SIS will send out a protection interlock signal to protect the on-site equipment, and the GDS system will notify the local fire department at the same time.
All control instruments that must be installed in the hazardous area meet the requirements of the hazardous area level and overall safety, and the design and selection follow the relevant national norms and standards.
In addition, the individual complete equipment control system in the process unit area is controlled by an independent PLC, and its important signals are sent to the DCS in the central control room for display through inter-system communication, and it is connected with the instrument safety system (SIS) by hard wiring.
The instrument control system (process part) consists of the following parts:
★ Distributed Control System (DCS) : DCS is the core and center of the instrument control system, which provides display, operation and control of all process parameters and alarms, and has the ability to communicate with other systems.
★ Instrument Safety System (SIS) : It is a part of system safety, mainly used for instrument safety in emergency situations, according to the predetermined process parking plan, independent of DCS in structure, and higher in safety level than DCS.
★ Uninterruptible power supply (UPS) : As a part of system reliability, it can provide operating power for a certain period of time in case of sudden power failure to ensure process shutdown and emergency treatment.
★ Process measuring instrument : the basic part of system parameterization, which is composed of several measuring instruments and sensors, whose measurement accuracy and precision directly affect the parameterization control of the system.
★ Control valve : the adjustment and execution part of process parameters.
★ On-line analyzer : It is mainly composed of some component analysis instruments, which is a supplement to measuring instruments and provides operation basis for process control.
Contact:
Sichuan Rongteng Automation Equipment Co., Ltd.
Phone/WhatsApp/Wechat : +86 177 8117 4421 +86 138 8076 0589
Website: www.rtgastreat.com Email: info@rtgastreat.com
Address:No. 8, Section 2 of Tengfei Road, Shigao Subdistrict,Tianfu New Area, Meishan city, Sichuan China 620564
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Post time: Nov-26-2023
