Improving Measurement and Final Control in Refinery Blending

by | Jun 30, 2015 | Downstream Hydrocarbons, Energy & Emissions, Industry, Measurement Instrumentation


As global refiners strive to meet ever-tightening regulations, the performance of measurement and final control devices can have a big impact in meeting this challenge.

The third Refinery Blending Series webinar recording, Improving measurement and control in blending operations Improving measurement and control in blending operations is now available.

Emerson's Julie Valentine

Emerson's John Ward

Emerson’s Julie Valentine and John Ward review the current business climate and its impact on blending operations. They share how regulations, such as the U.S. Environmental Protection Agency’s Tier 3 regulations, affect the importance of measurement and final control element performance and how to justify improvements.

They close the presentation portion of the webinar with some case studies where measurement improvements and tighter control valve performance increased profitability and reduced maintenance costs.

Regional and seasonal variations cause many refiners to have more than 50 blend recipes and perform over 1000 blend operations per year. These blends may range from 10,000 barrels to more than 200,000 barrels.

Common-Blend-ModelsThe difference in blending optimally versus sub-optimally can be as much as $0.75 to $1.50 (USD) per barrel. Julie notes that flow measurement is important for ratio (ramping and pacing) control as well as feedback for the blend property controls and blend optimizer.

By improving the accuracy of the flow measurements, the ratio-based controls can operate closer to optimum. Variability can also be reduced which allows targets to operate closer to specification—for instance moving targets from 7ppm to 9ppm sulfur without missing the specification and causing reblending operations.

Julie cites an example where a 0.3% error in flow measurement caused less optimal blending ratios costing $0.65/barrel or $400,000 / year for a 100,000 barrel/day refinery. One way to improve flow measurement is to replace turbine meters with more accurate Coriolis flow and density meters.

Coriolis meters also have the advantage of no moving parts, being independent of changing fluid properties, and providing multivariable measurements including mass flow, volumetric flow and density. They also tolerate two phase liquid and gas flow and verify ongoing measurement accuracy through Smart Meter Verification.

John highlights the importance of control valve performance in blend control. Digital Valve Controllers provide accurate flow control and provide ongoing diagnostics for cavitation, vibration, actuator air supply, calibration and mechanical failure.

He describes the role of overfill prevention systems for safe operations and continuous pump monitoring for condition-based maintenance and improved turnaround planning.

You’ll want to view the webinar recording to see how one refiner saved $200,000 per year in improved blending efficiency by switching from turbine meters to Coriolis meters for flow measurement and reduced annual maintenance costs by $30,000. At another refinery, this switch along with added digital valve controllers reduced blend stock rework by 40%.

A final case study included a refinery who lost their license to blend directly into the pipeline due to out-of-spec blends. Mechanical flow meters caused this inaccuracy and were replaced with Coriolis meters. Regaining the license to blend into the pipeline saved $300,000 annually and allowed reallocation of tankage.

The next webinar will be July 9 on the topic of using online analyzers to blend right the first time with Didier Lambert, the Chairman, CEO and founder of Topnir System Company.

You can also connect with other refining experts and see the answer to one of the questions asked during the webinar, Is there a specific level of vapor that the Coriolis meters can handle? in the Refining group in the Emerson Exchange 365 community.

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The opinions expressed here are the personal opinions of the authors. Content published here is not read or approved by Emerson before it is posted and does not necessarily represent the views and opinions of Emerson.

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