Engineering and Commissioning of the Process Control System PCS7 for an Oil Tank Farm

 

Project description

HIT has been assigned the task of planning, programming and on-site commissioning of the Siemens PCS7 process control system for a tank farm. Particular challenges were the redundant structure of the central control and of the bus systems, the connection of overall 255 motor valves by Profibus-DP as well as the connection of several external plant components such as the central power station. The system can be operated in a central control room via two operator stations (OS) with two monitors each. In addition, the control room of the power station contains two more OS’s with two monitors each. The OS’s are connected as client computers to a redundant pair of servers where the data is stored centrally. The entire engineering, programming and related construction of switch cabinets was completed by HIT. Special attention was given to the connection of signals in potentially explosive areas. The subsequent commissioning on site was performed by HIT’s employees.

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Oil tank farm (aerial view 2016)

 

Control system

The plant is controlled by the Siemens PCS7 process control system. A highly available AS410-5H control system and a redundant Profibus-DP have been installed to ensure the decentralised communication with the field. The fieldbus is primarily built as a redundant glass fiber ring due to the dimensions of the tank farm. Moreover, Profibus-PA is used to communicate with the field devices within potentially explosive areas. The process control system integrates the communication to external plant components such as generator station, fire pumps and tank heaters. For this purpose, Modbus-RTU communication protocols and S7 connection via Ethernet are used.

Safety functions

The control system integrates the safety related monitoring and shutdown functions: emergency-stop circuits, fire alarm, overfill protection, gas monitoring. All safety functions have been configured with the »Safety Matrix« programming tool. Thus the operator can comfortably monitor and handle the safety functions. By using the »Safety Matrix« a safety program can be created according to the rules of a cause & effect matrix.

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Cause & effect matrix
 

 

 

 

 

 

 

 

 

 

 

 

 

Route control

The transport paths consist of loading arms, pipelines, valves, pumps and tanks. The Siemens »Route Control« tool, which is integrated in the process control system, is used to control the transport paths. The SIMATIC Route Control is a program package by SIMATIC PCS 7 to automate the transport of material within plants. A material transport can be requested by indicating the source and destination. In addition, up to 10 intermediate points can be defined to be passed during the flow of material. The route control will find a way among the segments that form the route network. It also controls the automated material transport, for example by opening or closing valves and activating pumps. Up to 10 material transports can be started simultaneously.

Visualisation

The visualisation via operator stations (OS) is an integrated part of the PCS7 process control system and allows an overview of the whole plant at a single glance. Current states of electrical equipment such as motor-operated valves and pumps or process parameters like fill levels and pressures are displayed with the help of standardised faceplates. The faceplates allow the monitoring and operation of the respective electrical equipment and measuring point. Important information is collected, processed, archived and displayed by the process control system. The archived data includes among others the alarm and status messages, operating messages and the measured data.

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Visualisation of fill level measurement

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Visualisation of compressor station

Why HIT?

HIT successfully completed this project. A clearly arranged and improved user interface has been designed to support the operators on site. An explicit software structure has been developed. The installed equipment has shown its reliability from the beginning. These attributes increase the fail safety and the productivity of the plant.

 

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