27
Water-Conserving
Steam Ammonia Power Cycle—Energy
Concepts Company, 627 Ridgely Avenue, Annapolis, MD
21401-1062; 410-266-6521
Mr.
Donald C. Erickson, Principal Investigator, enerconcep@aol.com
Mrs.
Reta Ward, Business Official, enerconcep@aol.com
DOE
Grant No. DE-FG02-05ER84201
Amount:
$749,989
Fresh water is growing scarcer and costlier.
Power production is the second largest user of fresh water, consuming
about 25 gallons per kilowatt-hour in coal-fired plants. In particular, steam
power plants, which use air-cooling to reduce water usage, suffer large economic
and efficiency penalties, due to the deep vacuum at which steam condensers
operate. This project will develop a
new power cycle (Steam-Ammonia Power Cycle) that markedly reduces water usage
without increasing fuel consumption or cost. The
approach involves a hybrid cycle, in which the vacuum portion of a conventional
steam cycle is replaced with a tandem ammonia Rankine cycle. The
condensing pressure is thereby raised to 150 psig, which makes possible very
compact and economical air-cooled condensers. High
cycle efficiency is achieved by superheating the ammonia vapor. In
Phase I, the new cycle was thermodynamically analyzed in three different
important applications: state-of-art
combined cycle plant (600 MW), mid-size gas turbine bottoming cycle (12 MW), and
reciprocating engine bottoming cycle (2 MW). The
results validated the high cycle efficiency at all size ranges for both the
air-cooled and water-cooled variants of the cycle. In
Phase II, the new cycle will be developed and field-demonstrated at the smallest
scale. Waste heat from an 840 kW
reciprocating engine will be used to generate 130 kW of additional power, with
minimal water consumption. The cycle
is expected to be at least 50% more efficient than any existing reciprocating
engine bottoming cycle, due to the ability of the cycle to use the cylinder
jacket heat as well as the exhaust heat.
Commercial
Applications and other Benefits as described by the awardee:
The improved
power cycle should be applicable to virtually all types of existing
thermoelectric power plants. Due to
the temperature glide of the heat rejection, this new cycle requires 5% less
cooling water than current cycles when it is water cooled, equating to a fresh
water savings of 6.2 billion gallons per day nationwide. Power
plants with this modification also would achieve a reduction in fuel
consumption. The multi-turbine
variant of this cycle would apply to steam-based power plants, including coal
gasification combined cycle plants, while the single-turbine variant would apply
to small-scale plants powered by waste heat.