Normal Mode

Alyssa and Paul
December 12, 2023
10 min read


In 2014, a widely known midsize refining company undertook a pivotal control system migration, transitioning from TVC 3000 to Experion, both systems managed by Honeywell. This strategic upgrade aimed to optimize operational efficiency in the continuous refining process. Specializing in gas and diesel distribution, with some additional propane and butane, the refineries played a crucial role in the crack spread—determining the financial viability of purchasing crude oil, processing it, and determining the final product prices. This post reviews the effects of the migration, recommendations for creating an ideal crude unit, and the impact these had on the refinery's efficiency, profitability, and safety.


The system post-migration resulted in difficult challenges for the refinery, especially the crude unit, which became highly unstable. After some investigation it was determined that the integrator responsible for the cutover excelled in process control; however, he lacked expertise in advanced process control. The unstable operations created out-of-spec crude material, necessitating reprocessing. Refineries avoid reprocessing as much as possible: it significantly decreases the total product yield, and majorly impacts opportunity cost.


Recognizing the issue, top-level leadership of the refinery sought APCO's expertise, who brought in advanced process controls engineer Paul Emmett to stabilize the crude unit. This collaboration exemplified the comprehensive skillset our company offers—bridging the gap between the limited capabilities offered by process control engineering and the advantages achieved only with advanced process control. The work performed by Paul restored stability within a few short weeks, mitigating financial losses faced by the refining company.

Rebuilding: The Ideal Crude Unit

The success of the project established a thriving relationship between the refinery and APCO, with APCO performing routine advanced controls maintenance for the next few years. This positioned APCO as a key player when in 2017 disaster struck. An accident caused extensive damage to one of the refinery's crude units. Not to let this slow them down, the refinery seized the opportunity, to rebuild and create their ideal crude unit, with APCO there every step of the way to offer advice expertise in controls engineering.

The rebuild proved highly successful, leading to increased efficiency, safety, and reliability. This success prompted the company to reflect on the lessons learned and implement improvements across the entire refinery.

Normal Mode Project

Taking lessons from their previous success in building the ideal crude unit, the refinery worked with APCO to develop the Normal Mode Project: to fully optimize their regular operations across the refinery. From 2018 to 2020, APCO's involvement in the initiative ensured optimal tuning, range, and operator trust in settingsachieved wthorough training sessions. By systematically analyzing factors such as alarms, operator training, and user adoption, the project further improved refinery operations.

Ongoing Success

The collaborative efforts between the refining company and our team were instrumental in continuous growth. Refinery capacity doubled, increasing from 20,000 to 40,000 barrels per day. The partnership between the refining company and our team exemplifies the transformative power of expert collaboration in overcoming challenges, optimizing system controls, improving efficiency, and driving substantial financial growth in the automation and control systems industry.

Financial Impact

Before APCO's began projects with the refinery, the crack spread yielded about $25 per barrel. When the incomplete cutover occurred in 2014, efficiency dropped to $5-$10 per barrel. Through collaborative efforts over the next four years, we not only restored the crack spread but gradually increased it to $25. The improvements in efficiency generated a financial boost, with the refinery's annual revenue growing from $40-50 million in 2014 to an impressive $300 million in 2022.

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