Case Study: Advanced process control benefits in an ethanol plant

Hankinson Renewable Energy, one of the U.S. Midwest’s largest ethanol plants, after suffering through a drought during much of 2012, was challenged with high prices or feedstock unavailability since much of the corn crop was lost.

Located in Hankinson, ND, the Hankinson plant was designed by ICM Inc., of Colwich, KS. ICM also supplies licenses for more than 100 plants in the U.S.

CHALLENGE

ICM Inc. supplies process licenses for grain ethanol plants that use advanced process control (APC), which are identified by generation:

• 1st Generation plants use corn or grain sorghum as feedstock
• Generation 1.5 plants use add-on kernel husk as feedstock
• 2nd Generation plants use multi-cellulose materials as feedstock

The advantages of APC technology could help to make huge improvements at the Hankinson plant.

SOLUTION

The plant adopted Honeywell’s Multivariable Controller multivariable control software, Online Modeller automatic step testing and identification software tools, and Honeywell Forge APC operator interfaces.

Project steps included:

• Kick off and pre-testing
• Preliminary design
• Step testing and model identification
• Commissioning
• As-built documentation

RESULTS

The Hankinson plant saw control improvements in the following areas.

Thermal Oxidizers/HRSGs:

• Gas/steam ratio of TO1 reduced 1 percent
• Gas/steam ratio of TO2 reduced 5.6 percent

Dryers

• Product moisture increased 0.67 percent, variability reduced 20 percent
• Gas usage reduced 4.45 percent, production increased 6.38 percent

Centrifuges:

• Amps variability reduced 56 percent
• Centrate variability reduced 31 percent

From an economic benefit perspective, the Hankinson plant experienced the following:

• Natural Gas Cost Reduction $116,055*
• Selling more water as DDGS $675,248
• Total value of control improvement of $791,303 a
• Payback period of eight months.

(*Gas usage reduction in spite of 6.38 percent production rate increase.)

The Hankinson Honeywell Forge Advanced Process Control (APC) project was intended to improve control and reduce variability, lower energy usage, and increase dried distiller’s grain with solubles (DDGS) moisture closer to spec limit.

The Hankinson plant is at the generation 1.5 stage, which means it can use add-ons like kernel husks as additional feedstock.

This case study article was contributed by Honeywell. Click here to read or share, along with other case studies. To learn more about how Honeywell’s Asset Management solutions support operational excellence, visit www.honeywellprocess.com/software.