The hottest PAC8000 system is used in light hydroc

Application of PAC8000 system in light hydrocarbon recovery device and natural gas flow measurement

Abstract: with its unique characteristics in the petrochemical industry, PAC8000 control system undertakes the tasks of DCS, ESD, f&g, RTU and natural gas flow meter in Guang'an light hydrocarbon recovery device of Southwest Oil and gas field, realizing the original intention of users to complete all functions on the same platform

key words: natural gas, flow measurement, PAC8000, Ge, SiL2, DCS, ESD, f&g

the production scale of Guang'an light hydrocarbon recovery unit in PetroChina Southwest Oil and gas field is 100x104m3/D. the main process units include molecular sieve dehydration unit, light hydrocarbon recovery unit, product gas pressurization unit, liquefied gas, light oil tank farm and loading facilities. In order to ensure the safe, reliable, stable, efficient and economic operation of the whole plant, the user requires that the control system of the whole plant adopt the decentralized control system DCS, the emergency shutdown interlock and the combustible gas/fire detection alarm adopt a set of independent safety instrument system SIS respectively, and the remote terminal device RTU is used for the control of the sewage treatment device in the living area far away from the unit area, and the natural gas flow measurement function meeting the gb/t standard is realized at the same time

the hardware design of PAC8000 system can achieve direct installation in explosion-proof zone 2, the working temperature is between -40~70 ℃, and G3 anti-corrosion certification. At the same time, the PAC8000 system can realize the functions of DCS, ESD, f&g, RTU and natural gas flow measurement on the same hardware platform. Users only need to use a software platform to configure, program and maintain all control function units, which greatly simplifies the maintenance work and reduces the type and quantity of spare parts

1. System composition

because the whole system adopts a unified hardware platform, all control units can be connected to the same network, simplifying the system structure. The system structure is shown in Figure 1

Figure 1 system structure diagram

the DCS part of the whole system is mainly responsible for the normal production and operation of the device, in which the controller, power supply, network and key IO parts adopt redundant configuration. ES has agreed that countermeasure D system undertakes the task of emergency shutdown of the device, and the system adopts SiL2 (IEC61508) safety level standard configuration and design. F&g system is responsible for combustible gas/fire and fire alarm in the unit area, and adopts SiL2 (IEC61508) safety level standard configuration and design. RTU is responsible for the control of sewage treatment device in shift living area. The flow metering module realizes the flow metering function of 4-way natural gas pipeline according to gb2008 standard. DCS, ESD, f&g, RTU control stations and flow metering modules share the same redundant network, and adopt unified system configuration and programming software to form a complete and unified control system for the whole plant. The relevant information of the PLC field control equipment of the complete set of equipment in the plant is uploaded to the DCS system through RS485 serial port communication

1.1 controller

according to the characteristics of device production and control requirements, precautions for long-term operation of DC pressure testing machine, part s controller selects redundant PAC8000 hybrid controller, which has highly flexible data acquisition input and output and control functions, and can realize normal control, logic control and sequence control. Redundant PAC8000 safety controller is used for ESD and f&g controllers. The controller has built-in state detection circuit and adopts 1oo1d voting mode. A single controller can meet the requirements of SiL2 safety level. In order to improve the reliability and availability of the system, the system adopts redundant configuration. Some controllers of RTU adopt PAC8000 logic controller, which has highly flexible data acquisition input and output and control functions, can realize conventional control, logic control and sequential control, and support DNP3.0 Ethernet protocol at the same time. All models of controllers adopt IBM PowerPC 266MHz 32-bit microprocessor, 25m memory, dual to load experimental torque Taihe dual serial communication interface, support API, fieldbus, MODBUS, Hart, point-to-point communication and OPC, and can realize redundant configuration. They can be directly installed. After the elastic force is greater than gravity, Newton's second law becomes KX mg=ma in dangerous zone 2, meeting the requirements of G3 anti-corrosion certification. A controller can install up to 64 i/o modules, supporting hot plug. Dual power supply

in redundant controller configuration, redundant controllers are standby for each other, receive input signal data synchronously, execute control calculation synchronously, and transmit calculation results to each other at the same time. When a controller detects an error, the fault free controller can immediately control and realize undisturbed switching

1.2 IO module

pac8000 system's power supply, controller and i/o module can be directly installed in danger zone 2. Some i/o modules have built-in intrinsically safe safety barriers, which do not need to be additionally installed with safety barriers, channel isolation, monitoring and LED indication. It supports a variety of signal types and hot plugging. Analog input a/d conversion resolution reaches 16 bits, and analog output a/d conversion resolution reaches 12 bits. It can detect the field circuit, and has built-in input variable linearization, engineering unit conversion, square filtering, alarm and cold end temperature compensation calculation functions. The IO card has the fastest 20ms analog quantity adjustment function, 10ms digital quantity control function and 1mssoe control function

1.3 flow measurement unit

the flow measurement unit is a special module in the PAC8000 system, which can realize the flow measurement function of up to 8 channels of natural gas at the same time. All parameters and calculation results of the flow metering unit can be directly uploaded to the HMI Software of the operation station through Ethernet, and the natural gas metering parameters and component parameters can also be modified from the operation station. The flow metering display is shown in Figure 2

Figure 2 flow measurement display screen

2 System software design

GE company provides all the software required by the device system, including system configuration, control strategy configuration software workbench and human-machine interface HMI Software Cimplicity

2.1 system configuration and control software

the system uses workbench to configure the system hardware and control strategy. The whole control software covers all production automatic control programs, such as IO redundancy of key control loops, single loop PID control, cascade control loop, ratio control loop, alarm interlocking loop, calculation accumulation loop, motor control loop, etc

2.2 human machine interface software

operation station human machine interface (HMI) software Cimplicity is based on Windows XP operating system. It can create a powerful and fully functional monitoring system and make full use of the advanced functions of Microsoft Windows, including ActiveX controls, Ole, graphics, networks, etc. You can also add custom ActiveX controls, wizards, general objects, and create to expand the functions of. The human machine interface (HMI) software of the operation station mainly completes the important functions such as real-time monitoring, historical recording, data acquisition, system alarm and printing reports. High performance computer is used as the supporting hardware platform of the monitoring system, and windows xp and configuration software are used to form the operation platform of the monitoring system. Provide friendly human-computer interaction interface function, graphic processing function, report processing function, alarm processing function, query function, user authority management function, etc. The operation screen is shown in Figure 3 and Figure 4

Figure 3 DCS system operation screen

Figure 4 DCS system operation screen

3 Conclusion

Guang'an light hydrocarbon recovery unit adopts Ge PAC8000 control platform to realize DCS control system, ESD emergency shutdown system, f&g fire and gas system, RTU remote terminal unit system and natural gas flow measurement. The unified control platform greatly simplifies the project implementation, system maintenance and the type and quantity of user spare parts, laying a solid foundation for the smooth start-up and stable long-term operation of the unit. (end)