Consistency is not the strong suit of humans. That's why written records and instructions are so important, and why their digital and automated counterparts are so crucial, especially in maintaining, optimizing and ensuring quality in process operations.
The folks at ExxonMobil's Downstream Central Engineering Office know this lesson well: They support global deployments of automated procedures using Honeywell Process Solutions' Procedural Operations software—or "Proc Ops"—across multiple business units. At its refineries and chemical plants, automated procedures deliver consistent procedure execution with reduced console operator workload, and can help improve business performance by reducing transition losses and increasing the amount of time units spend at optimum feed rate.
"Proc Ops is an integrated set of functions embedded in Honeywell's Experion PKS control system to facilitate execution of operating procedures. It can work in tandem with existing TDC 3000 hardware and software," said Rose Thomas, senior engineering associate in the downstream office at ExxonMobil Research and Engineering Co. "Proc Ops helps our operating teams execute procedures consistently and efficiently, allows manual and automated steps to be combined into semi-automatic steps for console operators, and facilitates development of effective operator interfaces to start, monitor and end procedure execution. It also reduces application development and sustainment efforts because its modularity facilitates development of structured automated procedures, such as sequential control modules (SCMs) and recipe control modules (RCMs). And its graphical block models are easier than programming with TDC 3000 CL code."
Thomas presented "Automated Procedures Using Procedural Operations" this week at the 2015 Honeywell User Group Americas meeting in San Antonio, Texas.
Pick procedures, gain benefits
To decide which process applications and procedures to automate, Thomas reported that potential users must weigh several factors, including frequency of execution (from several years to every shift); degree of console interaction from in the field to the console itself; number of steps (from few to many); parallel activities (from few to many); consequence of error (from small to great); and fidelity of procedure documents (from guidelines to specific details).
"Experienced operators have the knowledge they need in their heads, so existing procedures become more like guidelines," explained Thomas. "When we talk to our sites, we can improve our procedures and quality by getting to their level of detail, and we can retain that veteran knowledge in our procedures."
While incorrect execution of procedures can potentially cause operational incidents and inefficiencies, Thomas reported that automated procedures facilitate consistency by addressing differences among operators and/or shifts, and by standardizing responses to abnormal situations, which often aren't included in written procedure documentation.
Retention of procedure execution know-how also is facilitated by establishing processes for effective knowledge capture, retention and transfer based on best operational and procedural practices. Further, procedures themselves can be improved by establishing the best, validated site for comparison to future executions, and by leveraging a proven, assured, structured platform to manage and implement procedural improvements.
Thomas added that ExxonMobil's refineries and chemical plants gain several primary benefits from adopting automated Proc Ops, including better margins in its grade transitions and feed-rate changes, reduced workloads for console operators and other staff, improved ability to address abnormal situations during execution, and reduced variability in procedure execution performance.
Consistency yields profitability
"Before automated procedure implementation, our sites had margin loss due to product downgrades during grade transitions, limited repeatability of each grade transition and units away from optimum feed rate longer than necessary," added Thomas. "After adding automated procedures, they reduced automatic feed rates, effectively managed parallel and time-sensitive process actions and increased service factors for multivariable advanced control applications."
On the workload side, ExxonMobil's console operators are typically responsible for about seven units, such as reactors or distillation applications, and handle about two or three grade transitions per week on each unit. "Before automating procedures, executing grade transitions was a large part of the operators' workload. It was difficult to convey current procedure status during shift handover, and there were many process alarms and operator changes to maintain levels," explained Thomas. "After automating procedures, operator workload related to grade transition execution was reduced, and they could redirect their focus to higher-value tasks. They also improved shift handover with an interactive operator interface that explicitly displays current procedure status. And they reduced process alarms and operator changes to maintain levels."
Likewise, before automating procedures, ExxonMobil's operators had to manually detect abnormal conditions during execution and make corrective responses. However, their responses to abnormal situations often weren't fully documented in their procedures, so they had to rely on operators' training and experience, which reduced the likelihood of timely corrective response in stressful or high-workload situations. "After automated procedures were adopted, operators could automatically detect abnormal conditions and automatically interrupt procedure steps," added Thomas. "They can also automatically implement corrective actions or hand-off to other operators, and confirm their corrective actions are completed, allowing them to proceed."
Automated Proc Ops has even helped ExxonMobil handle abnormal situations during automatic feed-rate reductions. "The main focus used to be handling rate reduction activities in response to alarm floods," said Thomas. "Automated procedures let operators be available to other units in the scope of their consoles and focus on handling rate reduction impacts in other units. Automated procedures mean units can continue running at reduced feed rates, and they give us more ramp options for feed-rate reductions."
Finally, before automated procedures, each ExxonMobil site wrote and updated many procedures independently. There was limited sharing of best practices and application designs, so procedure execution performance varied among sites. "Automated procedures have reduced variability in our procedure execution performance, and we now have common, high-level application design, which facilitates application sustainment and the capture of long-term benefits across multiple sites."