This project involved complete re-automation and wiring of an existing waste water treatment plant at a large food & beverage factory in Northern Ireland. The addition of automated devices, instrumentation, alarm notifications and remote clients allows the facility to operate with minimal intervention.
The waste water treatment plant was controlled by an old and non-supported PLC and HMI system. HMI screens were basic and abnormal situational awareness was not a factor in the 1990’s. As a result, faults occurred without notice and operator intervention was required throughout the day. The control system did not have a historian or trending package. The process engineers were not able to identify issues and improvement opportunities.
The solution was a complete replacement of the PLC and SCADA. A build of a new motor control center and upgraded field instrumentation. The following components were used for the new Control System:
The result is a modern and reliable control system that safely and efficiently operates the treatment facility. The new system was commissioned piece by piece allowing the plant to operate without downtime. This led to a very successful install and hand-over to the production team.
The SCADA screens are user-friendly and informative. The mimic pages include animated detailed piping and instrumentation drawings with clear leaders and followers. This allows personnel of all departments to understand the process from an operation and engineering point of view. The selection and control pages include information about what the plant is doing and monitoring of critical process values. In theory, the operator only needs the control pages to run the plant and only use the mimic pages for detailed diagnostics and process walk-through.
Abnormal situational awareness animations and alarm prioritization allow the production team to deal with any issues or faults promptly and effectively. All alarms were assessed and were put through a scoring criteria based on international standards. This produced an alarm priority of Low, Medium, High and Urgent. Associated enable logic and time delays were also determined to avoid spurious alarms. Each priority is color coded. Associated devices animate to the allocated priority color when they are in alarm. The alarm banner at the top shows the latest highest priority unacknowledged alarm. As well as the prioritization. Alarms were classified into three tiers for remote notifications via telephone call. Each of the three tiers had a different alarm pipeline. These were designed with the production and management teams to use different actions based on the severity of the alarm. Certain tiers would only contact operators and maintenance, whereas more serious tiers will also notify management and will continue to escalate until remote acknowledgment occurs. Since the system was installed, there have been a number of high priority alarms that occurred while no operators were present. The alarm pipelines were triggered and management were notified, who in turn were able to log in remotely and solve the issue.
Thanks to Ignition’s unlimited historical licensing model, large amounts of process data is logged. This includes information about all the devices, programs as well as all operator interactions. The data is stored in a MySQL database and is visualized via Trends as well as Plant Replay ™. Audit trails are used to record all changes made to process parameters as well as any manual intervention and alarm interactions.
The Plant Replay™ feature by Tamaki Control is used to playback process data using the SCADA screens in the vision client. This is used by managers, operators and engineers for fault diagnostics, process review and optimization. Water treatment is a slow process and being able to increase the replay speed helps to see the process dynamics. The production team are able to trial various operation methods and settings on a number of hours and days. They are then able to review the results using Plant Replay with ease.
With Ignition’s unlimited vision clients licensing model, production and management personnel are able to easily run a vision client on their company computers. This extends out to the existing VPN infrastructure within the company’s secure network. This meant that remote monitoring was available right away. Which coupled with voice notifications, meant that any issues were dealt with swiftly.
The addition of key instrumentation and upgrades of motor control to variable speed drives opened the door for process optimization. Using the new control system, process and automation engineers worked together to improve the process. Making it more energy efficient, stable, safe and consistent.
Waste water treatment plants rely mostly on pumps. Pump control is where most energy can be saved, and where preventative maintenance counts most. As part of this project, all pump controls were reviewed. Energy saving control strategies were implemented. Motor run hours and energy usage are tracked and displayed on the SCADA screens. Special duty/standby functionality was implemented to aid the maintenance team to determine how and when automated change-overs should occur, giving them more control over their equipment.