Managing a control system migration
Overcoming the inherent risks of a control system upgrade relies heavily on collaborating and sharing information transparently with a systematic, integrated approach.
ANAND SRIVASTAVA, MANISHA DAS and MEGHNA BAHL
Fluor Daniel India
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Since the birth of control systems and their utilisation in processing industries, operators’ interfaces have changed a great deal, but not as much compared to ‘seen’ hardware and ‘unseen’ software. There have been major technological advances which are not visible to non-instrumentation personnel.
For a production team, the priority is production numbers. The team will squeeze the last functional drop from a process control system until a shutdown or revamp takes place.
The past decade has been governed by considerations given to low sulphur containing fuels, hence the oil and gas industry has seen a shift towards clean fuels globally. The major contributors to this shift are new environmental regulations and revised fuel standards defining very low sulphur levels. To meet the regulations, the refining industry has invested heavily in the installation of new units and upgrades, or on the expansion of existing units. In today’s oil prices scenario, the industry’s focus is shifting towards brownfield projects which require relatively low capital expenditure and a high return on investment. This calls for effective migration of process control systems/emergency shutdown systems (PCS/ESD).
No two construction projects are exactly the same and vary in design, size, capacity, utilities, complexity, and so on. When it comes to a brownfield project execution, there are several unique design challenges that are not generally encountered in other brownfield or greenfield expansions.
With such upgrade projects comes a need to collaborate and share information across the entire value chain to drive down costs and increase the accuracy of delivery dates. Owners, operators, contractors, and suppliers working in the petroleum industry must find innovative solutions to minimise complexity and risk in these massive undertakings.
This article outlines:
- The rationale behind control system migration
- Possible challenges
- Execution strategy
- Implementation issues
Why is a control system upgrade needed?
The major reasons behind the decision to upgrade a control system include:
- System failures — unplanned outages and increased downtime, leading to production losses
- Lack of spare part availability
- Incompatibility of advanced interfacing applications with existing systems
- Inefficient operation
- Limited support from original equipment manufacturer
- Lack of skilled resources
What if an upgrade is delayed?
The costs of maintaining an old system will eventually outgrow the cost of migration to a new system.
However, if an upgrade is delayed, the refiner has to bear certain costs associated with the risks of using old systems. These can be production losses, unplanned shutdowns, or higher maintenance costs.
How to perform a control system upgrade
Once a decision is made to execute a revamp, the need for an execution plan arises. Multiple strategies can apply:
- Bring the plant to a shutdown, replace the system and take it back online. Because of extensive downtime, the economics do not work.
- Plan the migration, do the engineering, procurement and in planned shutdown execute the migration. Effective if planned in a pragmatic fashion.
- A piece-wise approach assigns the criticality of units; based on this, replace the set of I/O cards and processors followed by other related items like human machine interface.
A control system upgrade, being the critical part of any expansion project, is strategically scheduled during a planned shutdown. Shutdown means scheduled large scale maintenance activity in which an entire process unit is taken off stream for a period of time for revamp, debottlenecking, and replacement.
The main objectives of shutdown schedules are to make the plant safe to operate until the next outage, improve the efficiency and throughput of the plant by suitable modification, increase reliability/availability of equipment during operation, re-establish plant capacity, face minimum production loss and cost overruns, and complete corrective maintenance.
The baseline activities that are performed in an expansion or revamp project include:
- Site visit to analyse the current condition, physical locations, and surroundings to plan out revamp activities
- Collection of existing data and architecture to understand the existing system and formulate a plan for a revamp
- Validation of existing system design and installation documentation is carried out by the site engineering team in close coordination with the operation and maintenance team prior to a planned shutdown
- Alignment with the system automation supplier over the plan for migration to the new system
- Preparation of a detailed shutdown schedule for complete revamp activities; scheduling of activities is of utmost importance for effective migration to take place without any slippage
- Alignment with owner and system supplier regarding the schedule and shutdown duration requirements
- Replacement and migration of the existing distributed control system (DCS) and ESD, with upgraded systems located in either the existing control room or prefabricated satellite rack room (SRR) by the automation vendor
The following are some activities to be performed by the system automation supplier:
- Site data collection including control room surveys for checking space requirements and making necessary backups
- Software migration and preparation of the database
- Detail engineering by system automation vendor and review of the same by the EPC contractor
- Factory acceptance test (FAT) in the presence of the EPC contractor, the owner, and the project management contractor (PMC) if applicable. FAT is of prime importance as it reduces surprises during construction and commissioning. It is suggested to involve operators in FAT so that logics and graphics can be verified to avoid changes during commissioning
- Site acceptance test in the presence of the EPC contractor, owner, and PMC if applicable to ensure all required hardware is available
- Actual system replaced during shutdown
- Commissioning of the new system
- Start-up assistance, if required by the owner
- Decommissioning of the old system
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