Sand filter systems are crucial to the proper functionality, effectiveness, and efficiency of an off-shore oil platform, platforms which are held to increasingly higher standards and subject to rising requirements and specifications. The injection water, a critical component of the filtering system, must be processed through sand filters which need to function properly, be cleaned regularly (and correctly), and have sufficient alarm handling response in place for valve or system failures.
Sand Filter System Automation Project Goals
Quantum Solutions Inc (QSI) was entrusted with the responsibility of automating a sand filter system for an off-shore oil platform. This included integration of all sand filter devices into a centralized control system and programming an automated sequence to replace the existing manual process. Full sand filter integration and automation was the primary project goal. However, the oil platform aimed to eventually integrate all the processes for the platform into PLC Control on a centralized HMI system. This would ultimately increase overall system and process visibility, improve control, and enhance operator or technician effectiveness, while minimizing downtime.
Reasons for System Automation
Manual processes are tedious, error prone, and have a high level of operator variability. To overcome many of these challenges, most companies turn to control system integration and automation. Automated processes provide many benefits such as increased visibility, reduced downtime, and increased productivity.
Offshore-oil platforms have many unique processes in action across the platform, and many challenges arise when these processes are performed manually or not automated properly. Some of the challenges of a manual sand filter system include:
- Inconsistent operation among different operator shifts
- Poor visibility into previous backwashes, including when it was performed, and whether the tanks had been properly backwashed and prepared for service
- Little to no alarming or alarm handling to divert to another filter in the event of valve failure, causing downtime and damage to other equipment
- Poor system visibility control. Technicians use pushbuttons and outdated analog display devices on a large control panel to monitor and control the process.
- Require constant operator interaction, device troubleshooting and training for maintenance staff
- Needlessly lengthy backwash cycle. The process requires many steps, and the busy operator often cannot complete the process in a full shift.
The Solution: Design
To automate the system and reach the project goals, a new control panel to manage the system was designed and engineered, including: full electrical design, CAD drawings, I/O communications, I/O checkout and scaling, PLC and HMI development, procurement of the controls hardware, and on-site commissioning of the system. The integration process included:
- Integrate all individual devices into a new control system
- Deploy 3-monitor server/client HMI system
- HMI graphics for improved visibility, control, and alarming
- Detailed sequence of operations based on full review with operators
- Alarm and alarm handling planning for all devices in the system
The Solution: Development
Four programmed modes were created to allow for improved performance and availability of the sand filters. In each mode, the PLC system checks for different permissive interlocks and runs the required sequence to achieve the desired control and ensure proper cleaning. These four modes were:
- In Service: In Service mode indicates that the filter is in the production process and water is being passed through the tank/filter. This mode means that the sand filter is in production and running without errors.
- Out of Service: Out of Service mode indicates that the filter is not available for production and/or taken down for service, repair, or other maintenance. This filter is not available for in service mode or automatic switchover until repairs are completed and the filter is placed back in standby.
- Standby: Standby mode indicates that the filter is operational and available to go into one of the other three modes of operation. During Standby mode, all valves are closed, and the operator is able to switch modes. In the event of an alarm on the in-service filter, the system automatically switches to the next available standby filter to avoid downtime.
- Backwash: Backwash mode indicates that the tank/filter is in the process of being cleaned and water is being passed backwards through the filter. Prior to starting this mode, the PLC will check to ensure that all permissive conditions are met. Following the Backwash mode, the system automatically switches to Standby mode, as it is now ready for in service production mode.
The Solution: Alarms and Alarm Management
The manual sand filter system did not have an alarm system or an easy method to detect when issues arise, or malfunctions are happening with the opening or closing of valves. These valve failures either resulted in improper filtering of the water or caused pumps to overheat while running against a closed valve. Both situations were difficult to troubleshoot and led to extensive delays.
However, after automation was implemented, all devices were programmed with alarming and alarm handling based on severity of the alarm. All alarms sound the horn and display a flashing indicator and description on the HMI screen. The appropriate and proper level of response is then activated in a timely manner because of the early detection, warning, and alert.
As a precaution, the automatic functioning will not change unless there is one of two Critical Alarms: Inlet Valve is Open or Outlet Valve is Open. When either of these critical alarms occur during the backwash mode, the system automatically will pause the backwash process and stop the supply pump to the tank, or automatically switch to another available sand filter if the alarm occurred during in-service production mode. This will minimize errors and result in less downtime for maintenance.
The Solution: Onsite Commissioning
Downtime was minimized and a rapid return to full and complete operations was achieved through onsite testing of PLC sequence and a multiple-day training program for each operator team.
Following the design, development, and implementation of the automation system by QSI engineers for Beta Offshore platforms, the automated sand filter system has increased overall productivity and operator efficiency for the off-shore oil company. This was achieved through integration into a PLC and one-stop access to control and information on a single, centralized HMI system. No longer did operators have to manually control every device; instead, processes were sequenced automatically to allow for increased visibility and consistency. Training for operators and technicians was improved, leading to greater effectiveness and minimizing errors.
Quantum Solutions can design a system for your facility that will increase your efficiency and productivity. Contact us today to get started upgrading your facility!