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Process Control and Data Acquisition Systems

Process Control and Data Acquisition Systems. CM4120 Chemical Plant Operations January 2008. Outline. Types of Control Systems Control System Architecture for the PSCC Brief Recap of Process Instrumentation Connections to Control System Data Archival and Retrieval System.

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Process Control and Data Acquisition Systems

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  1. Process Control and Data Acquisition Systems CM4120 Chemical Plant Operations January 2008

  2. Outline • Types of Control Systems • Control System Architecture for the PSCC • Brief Recap of Process Instrumentation Connections to Control System • Data Archival and Retrieval System

  3. Distributed Control System (DCS) Architecture • Used for continuous control of chemical processing • Control functions are distributed throughout redundant, deterministic networked computer architecture • I/O interface and level 1 control functions • advanced control functions • human interface • DCS replaced the mainframe computers of the 1970’s • non-distributed • single point of failure • Added a high level of robustness to control systems • Pre-configured functionality geared toward process industries, but have a relatively high cost

  4. Programmable Logic Controller (PLC) Architecture • Used for control where the devices are primarily discrete • Provide very fast response (< .1 sec) to system changes • Typical applications are packaging, material conveyance, and waste water treatment • Very little, if any pre-configured functionality, but PLC’s are relatively low cost • In chemical processing, often are used along side DCS

  5. Safety Instrumented Systems (SIS) Architecture • An over-ride control system that takes the process to a safe state when predetermined abnormal conditions occur • Also called Emergency Shutdown System (ESD, ESS), Safety Shutdown System (SSD), and Safety Interlock System • Includes the logic control system and all the associated instrumentation including sensors, solenoids, valves, and actuators • Typical applications are burner controls on furnaces and exothermic reactors • Used with, but always physically separated from, process control systems

  6. SCADA – Supervisory Control and Data Acquisition System • Scalable systems that may provide some additional level of control and data acquisition “above” the controller, DCS and/or PLC level • Typically use non-redundant TCP/IP communications and therefore are not considered appropriate for direct process control • Built upon non-proprietary, off-the-shelf hardware • Used in large plants or across several plant sites where data from many sources must be collected into a single location

  7. PSCC Control System Architecture What we have in the PSCC: • Field instrumentation for measurement and final control • DCS for process control and data acquisition • Uses OSIsoft PI for data archival, retrieval, process management • Windows networking and TCP/IP for communications

  8. mtu.edu Network PSCC Router PI Server PSCC_DeltaV Redundant Hub Pilot Plants – valves, xmitters DeltaV ProPlus Station Professional WorkStations MD Controller and I/O Cards Emerson Process Management DeltaV and OSISoft PI in PSCC – System Overview • ProPlus DeltaV server • 4 Operator Workstations • MD controller w/ I/O interface cards • Field instruments and interconnecting wiring systems • PI Server

  9. Emerson Process Management DeltaV and OSISoft PI in PSCC – Networking mtu.edu Network • Business systems need access to data from control systems and production areas • PSCC_DeltaV is a secure Control Network (green) • Plant Network is local network for plant operations (red) • Plant data is available to the outside thru alias “steam.we.mtu.edu” Plant Network Router steam.we.mtu.edu PI Server uolab-pi PSCC_DeltaV Redundant Hub DeltaV ProPlus Station (4) Operator WorkStations MD Controller and I/O Cards

  10. MD Controller PSCC_DeltaV Redundant Hub ProPlus Station Operator WorkStations DeltaV System – How it works • Control network is Windows XP Workgroup – PSCC_DeltaV, uses Windows Networking and TCP/IP protocol • Control system configuration and operations graphics building are done thru ProPlus and/or Professional Workstations • ProPlus station stores configuration and archives data, displays information • Operator stations archive data, display information

  11. DeltaV & MD Controller – How it works • PID control, discrete control, signal conversions, alarming, Fuzzy control, etc. are continuously executed by the MD controller • Field instruments and final control elements are wired individually to the I/O cards in the MD controller • Also, “networked instrumentation” available – Foundation Fieldbus, ASi bus, DeviceNet, etc.

  12. Plant Area – valves, xmitters MD Controller and I/O Cards MD Controller I/O – How it works • I/O cards are specific to device requirements • 4-20 mA input, 4-20 mA output • 24 VDC input, 24 VDC output, etc. • ASi Interface • Foundation Fieldbus Interface

  13. Process Instrumentation • Input devices used to “see” what’s going on in the process • Output devices control the process • Wiring systems used to connect instrumentation to the DCS

  14. Input-type Field Devices – Transmitters Wiring to field junction cabinet Level transmitter RTD or T/C head Wiring from transmitter to temp measuring element Temperature transmitter

  15. 8 pr. Cables to controller cabinet Field Junction Cabinet Single pairs from field devices

  16. MD Controller Cabinet MD controller I/O cards Power-limiting Zener barriers 8 pr. cables from field junction cabinet 2nd I/O chassis

  17. Output-type Field Devices – Transducer 8-pr. cable from field termination cabinet Solenoids for 2-position air-actuated ball valves Air lines to ball valves Current to pneumatic transducers Wire prs. to solenoids Wire prs. to transducers Air lines to control valves

  18. Output-type Field Devices – Regulatory Control Valve Air line from transducer Actuator w/ positioner Control valve Block valves Bypass valve

  19. Output-type Field Devices – Ball Valve w/ Actuator Air line from solenoid Ball valve body Actuator Process line

  20. DeltaV & Foundation Fieldbus (4) mass flows, (4) densities, (4) RTD temps (3) 8-multiplexed RTD temps (2) temp-only transmitters

  21. Data Acquisition and Process Management System OSIsoft PI system including: • ProcessBook • DataLink • Batch Management, SPC, Performance Equations, etc.

  22. PI – Plant Information System to MTU’s network Router steam.we.mtu.edu • PI is a process data historian and data retrieval system • PI server (uolab-pi) is isolated from mtu.edu thru router “steam” • PI data are available anywhere with access to www and PI client software • PIPC is Excel add-in • ProcessBook is graphical tool for viewing process data PI Server PI-to-PI Interface PSCC_DeltaV hub DeltaV PI Server • Operator Stations • -Excel • PIPC • - ProcessBook

  23. PI – Plant Information System • Data Historian system is required part of process management system • Long-term data storage/ retrieval system • Access to real-time snapshot data without risking unauthorized access to control system • Optimizes use of hard drive storage space and permits quick recall of archived data • Includes data retrieval client software tools • OSISoft, Inc. PI system • Import process data into supervisory control or process monitoring applications • Link process control systems with business management systems • Provide data for production and compliance reporting

  24. PI – How it works • A PI “tag” is configured for every piece of data you want to archive • Collected tags are scheduled to retrieve data periodically or upon the occurrence of an event • Data are brought into the archive thru a filtering and compression algorithm • Data are not archived unless they pass the filter and compression tests • When data are retrieved from the archive and presented in a time series, the individual points are extrapolated between the stored data • Tags can also store manually entered (lab) data

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