Lack of manpower is often cited as the most pressing barrier to the adoption of multiunit or refinery-wide optimization, as more and more workers retire out of industry and plants scramble to hire and train a new workforce to take their places.
Partha Kesavan, global manager of advanced process control and optimization for LyondellBasell, added that company culture can also be problematic.
"There needs to be across-the-board buy-in from all levels of a company's workers, from management and front-line workers alike," Kesavan said. "Sometimes we need to [overcome the limitations] of company culture."
Robert Confair, process control engineer with LyondellBasell, said the "whole point of moving forward" is to break down some of the barriers between groups and bring them together.
"Success or failure is dictated by improving the overall culture, getting better communication and having the teams working together," he said. "I think that's the real key part of any plant optimization. You need management support, and corporate, operations, planning, engineers, etc., all need to be involved and tied to the whole process. Make sure your end users have a say in how the process is going, and make sure the whole process is developed together so everyone has a little bit of ownership."
"Going forward, as these technologies come together, a mixed skillset is going to be very important for seeing these technologies implemented and sustained," said Yugender Chikkula, manager of technology for Motiva Enterprises LLC.
Changes and the future
Economics are consistently changing and so are the feedstocks in plants. But how often are advanced process control (APC) targets currently changed based on planning or plant-wide optimization?
An informal poll conducted at the 2021 AFPM Summit indicated that a vast majority of crews changed these targets weekly. Chikkula said that Motiva makes these changes on a weekly or sometimes biweekly basis.
Confair said the LyondellBasell refinery has been undergoing some changes because it recently implemented a G-DOT process.
"Traditionally, we were at weekly updates, pass down, localized APC and localized programs that had to hit their own individualized optimizations," Confair said. "It was a very interim process, so there would be corrections throughout the week now and then, but the targets themselves had to have a lot of extra cushion."
With the implementation of more of a closed-loop, unified approach, planning personnel is able to see the targets more in real time, Confair added.
"They are able to see information and get feedback that helps coordinate what they're doing, and operations has tools that actually free them up," he said. "We're seeing resources become more available to work on other aspects, rather than having to constantly tweak the optimization of the plant. By going forward with the plans and these packages, we're actually seeing people freed up, not tied up in trying to do regular optimization as much."
That "freeing up," Confair said, gives crews the ability to focus on more maintenance issues for those types of items "and to continue trying to optimize on a more frequent basis while still using the weekly updates and target changes."
As opportunities and market conditions change, or when weather conditions or similar phenomena occur, crews can get more updates, Confair said.
"But the process itself is going to correct, and drive toward a quicker optimum. All groups involved can see what the plant is going to do," he said.
Patrick Robinson, process controls and modeling team lead with Phillips 66, said linear programming (LP) solves problems minute- by-minute, maximizing efficiency while minimizing costs.
"We're doing the same kind of problem, just at a different frequency," he said. "The LP is solving a much more complex problem; there are 30,000 variables, compared to an APC that has maybe 100 variables."
Robinson said, in his opinion, that LP "is the future."
"There's a lot of overlap now between the planning and the APC, and a lot of [potential] can be tapped by the LP model engineer and the APC engineer getting together and realizing they've got a lot in common," Robinson said.
