Power plants – Combustion products used as motive fluid
Reexamination Certificate
2000-09-05
2001-10-09
Thorpe, Timothy S. (Department: 3746)
Power plants
Combustion products used as motive fluid
C060S039410
Reexamination Certificate
active
06298654
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
N/A
BACKGROUND OF THE INVENTION
The trend in power generation gas turbine technology for several decades has been to build turbines of increasing size. The application of these large units in combined cycles lead to 500 MW plants (60 Hz) of two 130 MW gas turbines plus a condensing steam turbine with the associated heat recovery steam generators. The permitting and erection time of these plants is much shorter than those of the usual 2×1000 MW coal fired steam plants (let alone the time required to build a nuclear plant). Nevertheless, with respect to gas turbine unit size, governmental action and economic conditions have created a new situation during the last few years. Under the federal PURPA Law, producers of electricity may sell power back to the utility network when a local surplus of power occurs. This possibility, in principle, extends down to unit sizes characteristic of the needs of individual households (15 kW or less), but these units will be disregarded as subjects of the present invention, for two reasons. First, producing such small units economically in large quantities would necessitate large investments into the setting up of large production facilities similar to automobile engines, which is an industry different from the present gas turbine industry. Second, one of the main advantages of the present invention is extremely low NO
x
emission, but there are no NO
x
regulations for such small units. This situation removes the main incentive to apply the present invention to household units. Therefore, the present invention is focused on the mid-sized units in the 1-4 MW range. Such units would be of interest to hospitals, shopping centers, military bases, etc., where heat and electricity can be economically generated in “retail” quantities by the consumer itself, the heat energy being a low cost by-product of power generation. Using the backsale provision of PURPA, the small energy producer can pick the most economical combination of heat and power generation, in accordance with his own changing requirements.
In addition to the opportunities created by the backsale provision of the PURPA law, the ongoing deregulation of electric energy prices is expected to create even greater opportunities for small generating units due to the influence of competition in an emerging free market.
SUMMARY OF THE INVENTION
Under the above-described conditions, a competitive, middle range (1-4 MW) gas turbine system is provided that addresses several characteristics. The system achieves low emissions, especially of NO
x
, due to the residential environment. NO
x
reductions in the single digits are possible with an appropriate combustor or burner. The system is also highly efficient to be price competitive with the network. The system may also be used with the least expensive fuel, namely coal. Also, the system may reduce or eliminate the most influential contributor to global warming, the emission of CO
2
.
In particular, the system provides an ambient pressure gas-turbine (APG). The system includes a combustor that burns a gaseous, liquid, or solid fuel in air or another working fluid at ambient pressure. A first heat exchanger upstream of the combustor heats the working fluid to the combustor inlet temperature. A turbine downstream from the combustor expands the combustion gases from the combustor. The combustion gases are directed to the first heat exchanger for heat exchange with the working fluid and then to a compressor operative to compress the combustion gases. A second heat exchanger between the first heat exchanger and the compressor further cools the combustion gases to the compressor inlet temperature.
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David Gordon Wilson,The Design of High Efficiency Turbomachinery and Gas Turbines, Chapter 3: Gas-Turbine Power Cycles, Section 3.10: “The inverted Brayton cycle”, MIT Press 1984, pp. 135-139.
Beer Janos M.
Vermes Geza
Gartenberg Ehud
Thorpe Timothy S.
Weingarten, Schurgin Gagnebin & Hayes LLP
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