Improving boiler feedwater heating, recovering steam leak-off and reducing ester still heat use are among the ways the one plant has won multiple awards from the American Chemistry Council.
Improving boiler feedwater heating, recovering steam leak-off and reducing
ester still heat use are among the ways the Eastman Chemical Co.’s Kingsport,
Tenn., plant has won multiple Significant Improvement in Manufacturing Awards
from the American Chemistry Council (ACC). In 2011, Eastman’s winning projects
included five at the Kingsport site.
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 an annual energy savings of 44,391 MMBTU and an
annual reduction in greenhouse gas emissions of 4,661 tons annually.
Improvements in Boiler Feedwater Exchange. The
stage heaters at a powerhouse were operating at reduced efficiency due to
material wear in the heat exchangers, resulting in the boiler feedwater
bypassing the heaters. A monitoring program compared temperatures of the
feedwater exiting the stage heater with an entitlement value, which returned
the heaters to optimum efficiency and resulted in an increase in the
feedwater’s temperature. As a result, the heat input required during steam
generation was decreased and topping power from the generators was increased.
These changes led to annual energy savings of 180,456 MMBTU and an annual
greenhouse gas emissions reduction of 17,330 tons.
Improvements in Distillation Columns. Two
changes - adding a new distillation column and replacing an existing column
with a new more efficient design - led to lower reflux rates, tighter control
and greater energy efficiency while maintaining production. The new column was
started up when the existing column was shut down to replace sieve trays with
distillation trays and optimize tray spacing for greater efficiency. The
changes resulted in annual energy savings of 44,150 MMBTU and an annual
greenhouse gas emissions reduction of 4,635 tons.
Reduced Ester Still Heat Use. An ester still
had been heated with 600 psig steam 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
control. The heater was repiped to take the steam from the header and drain it
to a lower pressure condensate header, resulting in annual energy savings of
81,000 MMBTUs and an 8,500-ton reduction in greenhouse gas emissions.
Reduction of Natural Gas Use in Three Heat Transfer Material
Furnaces. The furnaces provide heat for dimethyl terephthalate
production. A new control strategy now automatically shifts the load from less
efficient furnaces to more efficient ones, so the overall heat duty required is
provided at maximum efficiency. 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 percent of total gas used. This converts
to an annual savings of 36,455 MMBTUs and 1,922 tons of greenhouse gas.
Improved Steam Turbine Discharge. At Eastman’s
Longview, Texas, site, the company was recognized with an ACC award for
improving steam-turbine discharge. The company added an additional steam line
to maintain a constant 175 psig steam-discharge pressure, which resulted in lower 1,500 psig steam demand, an
annual savings of 34,000 MMBTUs and 2,250 tons of greenhouse gas emissions.
This is the 18th consecutive year that Eastman has earned the energy awards,
receiving six of the 48 awards presented to 17 ACC member companies.
Recovering Steam Leaks, Boiler Improvements Yield Benefits
August 8, 2011