Manufacturing Savvy

18 Years Later They are Still Winning Awards

Eastman Chemical Co., based in Kingsport Tenn, has just received 6 awards for their energy efficiency programs from the American Chemistry Council. That makes 18 years straight.

Combined, the winning projects save over 386,000 MMBTUs and 37,000 tons of greenhouse gas emissions annually. That’s enough energy to power 10,000 homes and eliminate greenhouse gas emissions from over 6,000 cars.

In the past ten years the company has reduced greenhouse gas intensity 27%.

And in the past 15 years energy intensity has been reduced by 38%. For 2010, energy intensity was further reduced 6%, with energy savings of 3M MMBTUs and 275,000 fewer tons of greenhouse gas emissions.

Kingsport, Tennessee site received five awards:

Recovery of steam leak-off.
Six Sigma techniques were used to recover 15 psi steam leak-off from shaft seals on turbo generators in a powerhouse. New construction and use of an abandoned recovery system resulted in the recovery of the 15 psi steam for an annual energy savings of 44,391 MMBTU and an annual reduction in greenhouse gas emissions of 4,661 tons annually.

Improvements in boiler feed water exchanger.
The boiler feed water stage heaters at a powerhouse were found to be operating at reduced efficiency due to material wear in the heat exchangers, resulting in the boiler feed water bypassing the stageheater. A monitoring program compared temperatures of the boiler feedwater exiting the stageheater with an entitlement value. As a result, the stageheaters were returned to optimum efficiency and the temperature of the boiler feed water was increased. This affected a decrease in the heat input required during steam generation and an increase in topping power from the generators leading to an annual energy savings of 180,456 MMBTU and an annual greenhouse gas emissions reduction of 17,330 tons.

Improvements in distillation columns.
The combined use of a new distillation column and the replacement of an existing column with a new, more efficient design led to lower reflux rates, improved control, and greater energy efficiency while maintaining production. The new column that incorporated energy efficiency improvements was started up when the existing column was shut down to replace sieve trays with high-efficiency distillation trays and optimize tray spacing for greater efficiency. This resulted in annual energy savings of 44,150 MMBTU and an annual greenhouse gas emissions reduction of 4,635 tons.

Reduced ester still heat usage.
An ester still was previously heated with 600 psig steam that was modulated through a valve to a lower pressure. Experiments with the still revealed that the column could be heated from an existing 100 psig steam header with decreased energy use and increased controllability. The heater was repiped to take the steam from this header and drain to a lower pressure condensate header. This resulted in annual energy savings of 81,000 MMBTUs and an annual greenhouse gas emissions reduction of 8,500 tons.

Reduction of natural gas usage in three heat transfer material furnaces used to provide heat for DMT (Dimethyl Terephthalate) production.
A new control strategy was implemented that automatically shifts load from less efficient furnaces to more efficient furnaces so that the overall heat duty required is provided at maximum efficiency, reducing natural gas consumption. When compared to 2008, natural gas consumption was reduced by 80 scf per MMBTU of heat delivered to the process, with a savings of 35,393 kscf in 2010 or 6.3% of the total gas usage. This converts to an annual savings of 36,455 MMBTUs and 1922 tons of green house gas.

Longview, Texas site received one award:

Improvement of steam turbine discharge.
As two large steam turbines discharge into an existing 160 psig steam system and their compressors foul, their steam load increases to maintain operating horsepower. The ability of the existing 20 inch diameter steam lines to export additional steam was limited, causing higher discharge pressure and incremental operating cost increases over the five years between plant shutdowns. Adding an additional steam line to maintain a constant 175 psig steam discharge pressure resulted in lower 1,500 psig steam demand, an annual savings of 34,000 MMBTUs and 2,250 tons of greenhouse gas emissions.

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