Flow Forum Q&A Series: The business case for BTU control in fired heaters via energy flow

Flow Control‘s inaugural Flow Forum conference will take place May 7-8 at the Westin O’Hare in Chicago. During the event, Tom O’Banion and Thomas Langel will discuss the business case for BTU control in fired heaters via energy flow. O’Banion, who currently serves as director of innovation for Emerson Automation Solutions, and Langel, a business development manager for Emerson, recently sat down with Flow Control to answer a few questions about some of the key points of discussion they’ll cover during their Flow Forum presentation.

What is the traditional control technique for fired-heater fuel control, and why is this technique less than optimal in certain application scenarios?

The traditional method is referred to as pressure control. It’s typically comprised of a dP/orifice flowmeter downstream of a pressure regulator. It is less than optimal since the variation in energy content of the gas varies much more by volume than by mass. Therefore, with pressure control it is typical for refiners and others to run as high as 5 to 6 percent excess air in order to better handle periodic swings in fuel gas composition.

Why are mass-based Coriolis measurement systems better suited than traditional methods for fired-heater fuel control in refining and petrochemical applications?

Measuring the gas by mass reduces the variation of energy flow by up to 80 percent, thereby improving thermal efficiency (reduced excess air). Coriolis is highly accurate on gas, since the technology is largely independent of gas properties, density, viscosity and flow profile effects.

Can you share one (or two) real-world examples of how Coriolis technology has enabled performance improvement in BTU control?

BTU variations at MarkWest condensate plant caused variable heater operation and prevented use of plant recycle tailgases/offgases. After installation of Micro Motion Coriolis meters, the plant was able to use plant recycle gases and eliminate the import of natural gas. The total cost savings in this case was estimated at 200,000 USD/year.

What is the status of API RP556, and what impact does RP556 figure to have on the control of fired heater systems going forward?

Currently API RP556 is in draft phase, with the goal of completion by 2019. Upon completion, it will be circulated for comments, voting, and legal review. The goal is to have it published by 2022. An addendum has been drafted that cites the advantages of Coriolis flowmeter technology as the preferred method. This addendum revolves abound the ability of Coriolis meters to operate at lower levels of excess air, and thus improve thermal efficiency. Upon (or prior) to release, the existence of the recommended practice should make technology conversion to Coriolis more likely.