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1 Process Control and Data Acquisition Systems CM4120 Chemical Plant Operations January 2006.

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Presentation on theme: "1 Process Control and Data Acquisition Systems CM4120 Chemical Plant Operations January 2006."— Presentation transcript:

1 1 Process Control and Data Acquisition Systems CM4120 Chemical Plant Operations January 2006

2 2 Outline n Types of Control Systems n Control System Architecture for the PSCC n Process Instrumentation Connections to Control System n Data Acquisition System n Data Retrieval

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

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

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

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

7 7 PSCC Control System Architecture PSCC uses: n Field instrumentation for measurement and final control n DCS for process control and data acquisition n Uses OSIsoft PI for data archival, retrieval, process management n Windows networking and TCP/IP for communications

8 8 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 DeltaV ProPlus Station Pilot Plants – valves, xmitters Network PI Server PSCCRouter PSCC_DeltaV Redundant Hub Professional WorkStations MD Controller and I/O Cards

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

10 10 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 DeltaV System – How it works ProPlus station stores configuration and archives data, displays information Operator stations archive data, display information Operator WorkStations PSCC_DeltaV Redundant Hub ProPlus Station MD Controller

11 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 12 MD Controller I/O – How it works MD Controller and I/O Cards Plant Area – valves, xmitters 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 13 Process Instrumentation n Input devices used to see whats going on in the process n Output devices control the process n Wiring systems used to connect instrumentation to the DCS

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

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

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

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

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

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

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

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

22 22 PI – Plant Information System n Data Historian system is required part of process management system n Long-term data storage/ retrieval system n Access to real-time snapshot data n Optimizes use of hard drive storage space and permits quick recall of archived data n Includes data retrieval client software tools n 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

23 23 PI is a process data historization and data retrieval system PI server (mtu-PI) is isolated from 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 – Plant Information System PI Server PI-to-PI Interface PSCC_DeltaVhub Operator Stations -Excel - PIPC - ProcessBook DeltaV PI Server to MTUs network

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

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