Case Study · Ethanol
DDGS Rotary Dryer High Emissivity Coating: 7% Better Gas Yield and 5-Month ROI at a Midwest Ethanol Plant
| Industry | Ethanol |
|---|---|
| Asset | DDGS rotary dryers (A and B) and RTO |
| Customer or location | Midwest ethanol plant |
| Products used | Emisshield on burner tiles, combustion chamber, upper and lower transitions, dryer doors |
| Headline metric | Gas yield +7.6% (system) |
| Secondary metric | ROI 5 months |
| Also measured | VOC −20% |
An ethanol plant producing DDGS had excessive dryer fuel use and VOC emissions. Emisshield was applied to the burner tiles, combustion chamber, upper and lower transitions, and the hot face of the dryer doors. Measured before and after, natural gas yield improved 7.6% across the RTO and both dryers, with 15.1% on the RTO and 7.9% on Dryer A; ROI was reached in 5 months and VOC emissions fell 20%.
01
What was the challenge?
Fuel per gallon and VOC emissions were both above target on the drying system.
02
What was applied?
Emisshield on the combustion-facing surfaces of the dryer system. Gas consumption and yield were recorded pre- and post-coating for the RTO, Dryer A, Dryer B, and the combined system.
03
What were the results?
| Unit | Gas yield before (BTU/gal) | Gas yield after (BTU/gal) | Improvement |
|---|---|---|---|
| RTO | 953.69 | 809.50 | 15.1% |
| Dryer A | 4,999.95 | 4,604.48 | 7.9% |
| Dryer B | 4,199.53 | 3,987.26 | 5.1% |
| RTO + Dryer A + Dryer B | 10,166.79 | 9,389.75 | 7.6% |
| Unit | Gas consumption before (MMBtu/day) | After | Change |
|---|---|---|---|
| RTO | 198.06 | 184.25 | −7.0% |
| Dryer A | 1,059.48 | 1,049.47 | −0.9% |
| Dryer B | 890.42 | 907.04 | +1.9% |
| System | 2,147.96 | 2,140.77 | −0.3% |
| Temperature | Before | After |
|---|---|---|
| RTO temperature | 1,629.7°F | 1,637.9°F |
| RTO outlet | 374.3°F | 372.4°F |
| Dryer A inlet | 993.4°F | 900.6°F (−9.4%) |
| Dryer B inlet | 889.2°F | 870.6°F (−2.1%) |
Yield improved on all units while consumption held roughly flat, meaning more gallons dried per MMBtu. Combustion chamber temperatures rose, shell temperatures fell, and cross-zone temperature control improved.
04
Why did it work?
Coated combustion surfaces re-radiate burner energy into the drying air stream rather than the shell, so the dryer reaches the same drying duty on less gas per gallon and burns more completely, which lowers VOCs. See Energy Savings.
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