Submerged condenser for steam power plant

Abstract

In a power plant which produces electricity by boiling water with heat generated from a nuclear or fossil fuel source, and uses the steam to drive a generator to produce electricity, the spent steam is condensed in the vacuum produced by a column that is disposed beneath the surface of an adjacent sea or other large body of water. The distilled condensate is pumped back to the boiler providing a closed-loop condensing system. The system improves the Carnot efficiency of the plant by exhausting the steam to a lower pressure than previous condensers which operate at near atmospheric pressure.

Description

FIELD OF THE INVENTION

This invention relates to a closed-loop water supply for a boiler operated power plant and more particularly, to a condenser for the spent steam from the turbine of the power plant, which employs a water submerged condenser to produce a vacuum area in which the spent steam is condensed.

BACKGROUND OF THE INVENTION

Boiler operated power plants may use water that is heated by a nuclear or fossil fuel source. The water is preferably relatively pure and free of dissolved gases to minimize the accumulation of deposits in the system, thereby reducing maintenance. In conventional power-generating plants, the spent steam from the generator is cooled before being reintroduced into the boiler. Large power plants typically use cooling towers to cool the turbine output spent steam. These constitute large concrete chimneys. A typical chimney may be about 160 meters high and 130 meters in diameter at the base.

The cooling water output of the cooling tower, at approximately 40° C., is passed through a heat exchanger to cool and condense the spent steam from the turbine. Due to practical constraints this results in a condensation of the steam at a temperature in excess of 66° C. Since the Carnot efficiency of the plant is inherently a function of the temperature difference between the steam introduced into the turbine (approximately 300° C.) and the exhaust temperature, it would be extremely advantageous if the steam could be condensed at lower pressures and temperatures, such as 35° C. It would also be advantageous to provide a condenser which does not use pumps to move the steam into the condenser or to force water through the heat exchanger in that up to 5% of a plant's total electrical capacity is used merely to pump cooling water.

SUMMARY OF THE INVENTION

The present invention is accordingly directed toward a condenser for the spent steam from a turbine of an electric power plant. It condenses the steam at a much lower temperature than conventional cooling towers, thus improving the Carnot efficiency of the plant. Moreover, the system of the present invention does not require either pumps to move the steam into the condenser, or to force water around the heat exchanger.

In the present invention, condensation of the steam occurs at the near-vacuum space in a chamber above a column; i.e. a column of water having a vertical height which equals or approximates the maximum water column height that can be supported by pressure. The column is closed at the top and exposed to gas pressure at its bottom, so as to produce a near-vacuum volume at its top in the chamber. In the Torricelli column case this pressure is approximately atmospheric. The column and its vacuum chamber are submerged in a body of water adjacent to the power plant so as to cool the chamber. Spent steam from the turbine of the power plant is introduced into this vacuum chamber. The water droplets condense and settle by gravity on the top of the column, pushing the column water downwardly. This results in a reservoir of water at the bottom of the column, which is then pumped back into the boiler.

In the preferred embodiment of the invention, the entire column, including the vacuum chamber at the top of the column, is sunk in a large body of water adjacent to the power plant, such as an ocean or a lake or river. Because of their large water requirements, steam power plants are typically located adjacent to such bodies of water. The body of water provides a practically infinite heat sink for the condensation.

In one embodiment of the invention, which will be subsequently described in detail, a power plant may be broken up into a number of parallel systems, each comprising a boiler, a turbine, a condenser for the spent turbine steam, and a generator. In addition, the spent steam could be used by cooling tower(s), while at least one is cooled by the condenser. Also the boiler can be a single unit that feeds multiple independent turbines.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, advantages and applications in the present invention will be made apparent by the following detailed description of preferred embodiments of the invention. The description makes reference to the accompanying drawings in which:

FIG. 1 is a schematic diagram of a preferred embodiment of the invention; and

FIG. 2 is a schematic diagram of a variation of the invention employing several parallel systems.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, the present invention may be used with power plants that employ steam to generate electricity through a turbine. The heat source for boiling water to produce the steam, generally indicated at 10, may be a nuclear reactor, a fossil fuel burner, or the like. A boiler 12 receives water from a conduit 14 and the water is heated to produce live steam which is fed to a conventional turbine 16. The output shaft of the turbine 16 is connected to an electrical generator 18 which produces the electrical output of the system on line 20.

The thermodynamic efficiency of the turbine 16 is a direct function of the difference between steam temperature or pressure at its input from the boiler and the temperature or pressure of the spent steam at line 22, at the output of the turbine. In conventional prior art power generation systems, the spent steam is condensed in a heat exchanger connected to a cooling tower. The steam condenses to water. It is then recirculated to the boiler 12.

In the system of the present invention, the spent steam is fed into a condenser 24. The condenser is preferably submerged in a large body of water, generally indicated at 26, located adjacent to the power plant. Electric generating plants are usually located adjacent to large bodies of water, such as a sea, ocean, lakes, rivers or large reservoirs. The condenser 24 is located at a sufficient depth in the body of water 26 so that it is maintained at a relatively cool temperature, even in warm climates. Locating the condenser below the turbine lowers the steam temperature as seen by the turbine by an additional 1° C. per 200 meters. The condenser 24 is connected by a column 28 to a sump of distilled water 30 at a lower level than the condenser beneath the water level 26. The sump 30 is pressurized to a desired level that could be adjusted to lower, the same, or higher than atmospheric by a pressure or vacuum pump, or, in the special case of a Torricelli column, by a vent 32. The vent 32 extends from the top of the sump to above the water level 26, so as produce atmospheric pressure on the water in the sump 30. The pressure in sump 30 is sufficient to support a water column within the column 28 so that the lower part of the condenser 24 is filled with water and the upper portion is at a near-vacuum condition.

In an alternate embodiment, the sump 30 can be eliminated by directly connecting the bottom of the water column to a water pump. The height of the water is determined by the input pressure of pump 34.

The heat of condensation of the spent steam within the chamber 24 is transferred to the cool water surrounding the condenser. The steam thus normally condenses on top of the water column 28 which is forced downward by gravity, replenishing the sump 30. The distilled water from the chamber 30 is forced by pump 34 to the boiler 12 at a rate commensurate with the condensation rate.

No pump is required to force the spent steam from the turbine into the vacuum area of the top of the condenser 24 and the distilled water that flows down is gravity powered.

The system of FIG. 1 provides a closed-loop cycle for the boiler water. By lowering the pressure at the steam outlet of the turbine relative to prior art systems, the Carnot efficiency of the turbine is substantially improved. The pumping requirements of the system are also minimized relative to prior art structures.

An alternative embodiment of the invention is illustrated in FIG. 2. In this embodiment there are n multiple independent generating systems, each comprising of a separate boiler, turbine, generator and a condenser.

The system generally comprises a plurality of boilers, 50a, 50b, . . . , 50n. Each boiler normally feeds a separate turbine 52, i.e., if the turbine 52a is fed by boiler 50a, turbine 52b is fed by boiler 50b, and turbine 52n is fed by the boiler 50n. Each turbine feeds a generator, 54a, 54b and 54n. The spent steam from each turbine is fed to a column condenser, generally indicated at 56. The output turbine 52a is generally fed to column condenser 56a, the output turbine 52b is generally fed to column condenser 56b, the output turbine 52n is generally fed to column condenser 56n and the outputs from the sumps of each of the column condensers are fed back to their respective boilers. The boiler may also be a single unit that feeds multiple turbines. Each sump is sealed off to retain a desired pressure.

By using separate and independent systems, some units may use traditional condenser cooled via cooling tower or pump water from the body of water. For practical purposes a portion of the column condenser and sump could be under the floor of a large body of water.

Claims

1. A condenser for vapor, comprising:

a condenser chamber disposed in a body of water;

a sump disposed below the condenser chamber filled with condensed vapor;

a gas applied to the volume at the top of the sump to pressurize the sump;

a column of condensed vapor of the maximum height that can be supported by the gas pressure extending between the chamber and the sump to produce a near-vacuum pressure in the chamber volume above the column;

a conduit for feeding vapor at a higher temperature than the body of water surrounding the condenser chamber into the near-vacuum-pressure volume; and

a pump for removing condensed vapor from the sump as the vapor condenses and falls on the column.

2. The condenser of claim 1 in which the vapor is water vapor.

3. The condenser of claim 1 wherein the gas pressure in the sump is provided by a vent connecting the volume above the condensed vapor in the sump to the atmosphere.

4. The condenser of claim 2 wherein the water vapor is spent steam from the turbine of a power plant.

5. The condenser of claim 2 wherein the pump feeds water from the sump to a boiler which is part of the power plant.

6. A condenser for condensing vapor into distillate, comprising:

a condenser chamber disposed within a body of water;

a conduit for feeding vapor into the condenser chamber;

a column of distillate connected to the chamber to produce a near-vacuum pressure above the column within the chamber; and

a pump operative to remove distillate from the bottom of the column.

7. The condenser of claim 6 wherein the vapor is water vapor.

8. The condenser of claim 7 wherein the water vapor is spent steam from the turbine of a power plant.

9. The condenser of claim 8 wherein the pump feeds water to a boiler which is part of the power plant.

10. In a power generating plant disposed adjacent to a large body of water, comprising a boiler for water to produce steam, a turbine powered by the steam and an electric generator for converting the turbine power into electricity, a condenser for the spent vapor from the turbine comprising:

a condenser chamber disposed within the body of water;

a sump disposed below the condenser chamber filled with condensed vapor;

a gas applied to the top of the sump to pressurize the sump;

a column of condensed vapor of the maximum height that can be supported by the gas pressure extending between the chamber and the sump to produce a near-vacuum pressure in the chamber volume above the column;

a conduit for carrying vapor from the turbine exhaust into the near-vacuum volume; and

a pump for feeding water from the sump to the boiler.

11. The plant of claim 10 comprising a plurality of N boilers, powering N turbines respectively, each turbine powering one of N electric generators, and a plurality of condensers operate to receive spent vapor from at least certain of the turbines.

12. The plant of claim 11 including apparatus interconnecting various of the boilers with various of the turbines, and various of the turbines with various of the generators, to provide redundancy for fail-safe operation.

13. The plant of claim 12, including a cooling tower operative to condense the spent vapor from any one of the turbines.