GB2449130A

GB2449130A - Steam cycle condenser cooled by refrigeration cycle

Info

Publication number: GB2449130A
Application number: GB0710145A
Authority: GB
Inventors: Joseph Francis Brown Jr
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-05-09
Filing date: 2007-05-09
Publication date: 2008-11-12
Anticipated expiration: 2027-05-09
Also published as: GB2449130B; GB0710145D0

Abstract

A conventional steam cycle comprises at least one steam turbine 12 and a condenser 1. The condenser 1 of the steam cycle is cooled by refrigeration cycle. The refrigeration cycle may further comprise a compressor 3 which may be driven directly by the steam turbine(s) 12. The steam turbine(s) 12 also drive(s) electric generator 15.

Description

PATENT APPLICATION

REFRIGERANT COOLED MAIN STEAM CONDENSER SPECIFICATION.

The major intent of this invention is to improve the operational efficiency and the functional design of the modern day electrical power generating station. This invention replaces the main steam condenser once through cooling-water system with a refrigerant-cooling system.

This invention is directed primarily toward new power plant construction. Maintenance, equipment replacement cost and future operating cost savings may make it beneficial to convert existing stations. The main steam condenser refrigerant-cooling system reduces fuel consumption with compatible power generation to that of the condenser once thru cooling-water system. The intent of this invention is not to redesign the conventional steam cycle or the conventional refrigeration cycle but to combine them.

The following drawings will aid in the clarification of this invention: Figure -1 is a schematic diagram, which shows the conventional steam cycle and the conventional refrigerant cycle, crossing at the main steam condenser, where the heat exchange takes place.

Figure -2 is a schematic diagram showing the equipment and flow arrangement of the conventional steam cycle and conventional refrigerant cycle.

I

Figure -3 is a physical schematic building cross-section diagram showing a probable arrangement of equipment and flow pattern for the steam and refrigerant combined cycle.

The combined cycles become known as a binary cycle, each dependent upon the other. (FIGuRE-I) The present day main steam condenser requires very large quantities of cooling water. Main circulating pumps supply the main steam condenser with cooling water from nearby rivers or lakes to condense the main steam. The main steam condenser cooling water enters the cooling system thru a water intake structure designed to prevent marine life from entering the cooling system. This elaborate intake structure is in compliance with environmental requirements. When the heated water from the main steam condenser is returned to the river or lake, it is directed far from the shoreline. This insures proper mixing and not allow hot spots or elevated river or lake temperatures. Many modern day power plants have installed natural draft cooling towers to eliminate the concern for elevated river or lake temperatures. The natural draft cooJing towers may cause an environmental hazard due to possible chlorides contained in their vapor plume. The main steam condenser refrigerant cooling system has many advantages over the present day once thru water-cooling system. It should be noted with a refrigerant-cooling system, the intake structure and need for cooling towers is no longer required. More importantly, the power plant location is no longer dependent upon large bodies of water, which presently govern power plant location. The present once thru cooling-water system is very corrosive, due to electrolysis and water quality. The refrigerant coolant is non-corrosive, reducing maintenance costs and eliminating the need for exotic piping materials. The heat from the present once thru cooling- water system is transfer to the river or lake. The main steam condenser refrigerant-cooling system allows for transfer of heat energy to building services, boiler feed and other utilities requiring heat. The heat energy is not wasted. The uniqueness of this invention is driving the refrigerant compressor with the main steam turbine. The main steam condenser refrigerant cooling system has greater temperature control than that of the present day once thru cooling water system. The refrigerant flow to the main steam condenser can be set at a desired temperature and is controlled by the steam flow to the main steam turbine. The conventional once thru cooling-water system water temperature is subject to river or lake, seasonal temperatures and main circulating pump design. The main steam condenser and the refrigerant evaporator share the same container and become one. This combination also adds to the making of a binary cycle. The steam cycle and the refrigeration cycle remain unchanged with this invention. The installation of the combined conventional systems is as follows. (FIGURE -2 & 3) The refrigerant compressor 3 is located in the main turbine building and is directly connected to the main generator shaft. The main steam turbines drive the generator 15 and the refrigerant compressor. 3 The refrigerant gas is compressed and transferred to the refrigerant condenser, 4 located on the main turbine-building roof. The heat gain by absorption from the condensing steam and the heat of compression caused by the refrigerant compressor 3 is removed by the refrigerant condenser. 4 The air-cooled heat exchangers 4 remove heat and condense the refrigerant gas. The condensed liquid refrigerant is transferred to the refrigerant receiver, 5 located on the main turbine-building roof and is the high pressure refrigerant storage tank. 5 The high megawatt electrical power generating stations, having larger pressure drop thru the refrigerant cooling system, may require a refrigerant booster pump 16. The steam supply to the refrigerant booster pump 16 is a branch line from the main steam turbine supply which synchronizes booster pump flow requirements with that of the refrigerant compressor 3. (FIGURE-3) The condensed liquid refrigerant is transferred to the refrigerant expansion valve, 6 The refrigerant expansion Valve 6 is located at the coolant entrance to the main steam evaporator condenser. 1 Its function is to allow the refrigeçant to change from a hi9h-pressure liquid to a low-pressure liquid, lowering the boiling point of the refrigerant. The low-pressure liquid refrigerant flows thru the condenser tubes, absorbing heat, changing into a gas, in turn condensing the steam. The evaporator condenser I is located under the Main Steam low pressure Turbine 12 and is connected by a steam exhaust trunk 13. The refrigerant inter-cooler 2 is located between the evaporator condenser I and refrigerant compressor 3. The inter-cooler removes excess heat from the refrigerant, gas, prior to entering the compressor. The refrigerant condenser will remove the inter-cooler heat. The main steam boiler 11 heats the feed water changing it into steam. Main steam under pressure is transferred to the main steam turbine, through a piping system. The main steam enters the main steam turbine and is directed onto the turbine blades causing the turbine to rotate. The rotating turbine shaft is connected to the main generator which produces electrical power. The condenser air ejectors 14 also remove air from the evaporator condenser, lowering the internal pressure. The air ejector 14 design is in accordance with system start-up capacity. The main, steam exhaust trunk 13 is located at the base of the main steam turbines and directs the exhaust steam into the evaporator condenser 1. The steam enters the evaporator condenser 1 flowing around the tubes. The coolant flowing through the tubes changes the steam into condensate which collects in the condenser evaporator hotwell. 7 The condenser hotwell 7 is located in the lower portion of the evaporator condenser I and is the storage area for the condensate pump. The main condensate pump 8 takes suction from the hotwell 7 and delivers the condensate to the boiler feedwater heater. 9 The feedwater heater 9 is the storage area for the feedwater pump 10.

The main feedwater pump 10 delivers water to the main steam boiler 11 to produce main steam. The binary cycle is continuous.

This refrigerant cooling concept, with slight modification, may be used throughout the plant for systems requiring heat removal, such as the shell and tube heat exchanger in the secondary systems. 5.

Background of the Invention:

Rising energy costs and public concerns inspired this invention.

Utilities pass on much of the increased energy costs to the public.

To improve the efficiency of the power source is to lower consumer costs. The refrigerant-cooling system replacement of the present main steam condenser once thru cooling-water system will reduce these costs. The lower utility costs and the elimination of the cooling towers and hot water returns to the rivers or lakes, will reduce public economic and environmental concerns. 6.

Detailed description of invention:

This invention replaces the main steam condenser cooling-water system with a refrigerant-cooling system. It should be noted that there is no intent of redesigning the steam cycle or refrigeration cycle. The combining of the steam condenser and the refrigerant evaporator, along with the refrigerant compressor being driven by the main steam turbine creates the binary cycle. (FIGURE-1 & 2) The main steam condenser in the modern day power plant is sometimes called the Heart of the steam cycle. The differential pressure between the boiler and the condenser causes steam to flow. The lower the internal condenser pressure, the more steam flow. The refrigerant low normal temperature and high heat transfer rate lowers the main steam condenser internal pressure much below that of the once thru cooling water system. This increased reduction in the condenser pressure makes the steam cycle much more efficient. This invention is directed toward new plant construction but a maintenance economic evaluation may constitute a conversion to an existing plant. The main steam condenser air ejectors remove air from the condenser vessel also lowering the internal pressure. The air ejector system design capacity is essential for system start-up. The conventional refrigerant cycle is very efficient and very reliable. The simplicity of the refrigerant-cooling system will also provide reusable heat for building services and the main steam feed water. The refrigerant cooling system is much more efficient than the water-cooled system, less fuel consumption for the same power generated.

Brief Summa!y of the Invention: This invention has to do with the cooling system for the main steam condenser in the modern-day power plant. This invention replaces the main steam condenser existing once thru cooling water system with a refrigerant cooling system. In order for the steam cycle to function properly the main steam produced by the boiler must have a low-pressure area to discharge into. This area is the main steam condenser. The lower the pressure area the more efficient the system.

When the energy of the steam is spent, after rotating the turbines, it discharges into the main steam condenser. The steam flows around the condenser tubes, as the coolant flows through the tubes, the temperature difference causes the steam to condense. The lower the temperature of the coolant flowing thru the tubes the faster the steam is condensed. The condensing of the increased steam flow lowers the main steam condenser internal pressure. The refrigerant cooling system, improves the efficiency of the steam system, over the main steam condenser water-cooled system, considerably. The refrigerant has a normal temperature much lower than that of water and a much higher heat transfer rate than water. The main steam condenser refrigerant cooling system is controlled whereas the water-cooled condenser system fluctuates, because of seasonal temperature changes of the river or lake water. For example, the modern day power generating station produces less power in the summer months.

The main steam condenser refrigerant-cooling system will be much more fuel efficient than the present once thru cooling-water system.

Claims

Patent Claims 1. Increased efficiency and reduced operatinQ costs; The

refrigerant cooled main steam condenser cooling system allows for a greater control of the condenser pressure and coolant temperature. The refrigerant flow to the condenser evaporator is always at the optimum required temperature for condensing the exhaust steam. The conventional once thru cooling water system water temperature is seasonal. The heat transfer rate of the refrigerant coolant is much greater than that of water. The refrigerant normal temperature is much lower than that of the river and lake water. The lower temperature and high heat transfer rate of the refrigerant cooling system creates a lower internal condenser pressure than that of the cooling water system. This lower condenser pressure allows more steam flow, extracting more energy from the steam. The lower condenser internal pressure allows for greater production of electrical power with the same fuel consumption.
2. The present power plant site location is governed by availability of large bodies of water. A massive amount of water is needed in order to keep the temperature-rise thru the condenser within the present once thru cooling system design criteria. The water temperature returned to the river or lake is the limiting factor. The power plant site is usually located along choice shore-line property. The refrigerant cooled main steam condenser binary cycle design criteria is, to condense turbine exhaust steam. The amount of condenser coolant needed is reduced considerably. The binary cycle allows for a remote power plant site location, with lower property costs, reduced taxes.

less public concerns and shorter electrical power transmission lines.

A design comparison will show that a closed main steam condenser binary cycle is very environmentally friendly and also allows for, a much smaller condenser size, shorter piping runs, smaller pipe sizes, no intake structures or cooling towers and no need for exotic materials for piping equipment and instrumentation. The refrigerant cooled main steam condenser binary cycle has a much reduced construction, maintenance and operating cost.

-

. Nuclear power generating stations have two major concerns besides power generation. They are plant security and plant safety.

The main steam condenser binary cycle does not require an intake structure. This eliminates an additional opening in the plant security boundary. A nuclear power generating station has an emergency shutdown system, which incorporates heat removal. The main steam condenser binary cycle is a very efficient and reliable heat removal system. The binary cycle, with piping and instrumentation, can easily be incorporated into the power plant emergency shutdown system.

The condenser-evaporator binary cycle is a closed system. This incorporation may increase nuclear power acceptance.

2. Lower construction and maintenance costs; Plant location is no longer governed by the availability of large bodies of water. The water intake structure and cooling towers are no longer necessary. Remote plant location allows for lower property costs, reduced taxes and less public concern. Personnel access to the plant for construction, security and plant operation will be less congested. The refrigerant coolant temperature and heat transfer rate along with system compactness, allows for a smaller condenser sizes shorter piping runs and smaller pipe sizes. The present once thru cooling water system has equipment and system corrosion problems because of water quality and electrolysis. This problem is eliminated with the refrigerant coolant system because the refrigerant is non-corrosive. Exotic materials are no longer required for equipment, piping systems and instrumentation.

3. Improved plant security and safety: Nuclear power generating stations have two major concerns, besides power generation. They are plant security and plant safety. The main steam condenser refrigerant cooling system does not require a cooling water intake structure. This eliminates an additional opening in the plant security boundary. Nuclear power generating stations have an emergency shutdown system, which incorporates heat removal. The main steam condenser refrigerant cooling system is a very efficient and a very reliable heat removal system. The main steam condenser refrigerant cooling system, with instrumentation, can easily be incorporated into the plant emergency shutdown system. This incorporation may increase nuclear power acceptance. The cooling system for the main steam condenser is now a closed system

AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS

1. The combination main steam condenser and refrigerant evaporator along with the refrigerant compressor being driven by the main steam turbine, creates a binary cycle, that is, the functioning of the steam cycle and the refrigerant cycle are dependent upon each other. The binary cycle allows for precise control of the condenser pressure and coolant temperature, greatly increasing the functional design and operational efficiency of the modern day power generating station.

The amount of refrigerant supplied to evaporator for condensing the main steam is controlled by the amount of steam supplied to the main steam turbine. The refrigerant supply to the evaporator is always the exact quantity needed to condense the main steam and maintain optimum condenser vacuum. The condenser very low vacuum increases steam flow, extracting maximum energy from the steam, with the greatest possible generation of electncal power.

The installation of the binary cycle, into an existing power plant, will require a very close review of shaft balance specifications. The refrigerant compressor attachment to the turbine shaft or generator shaft may not be possible. A separate turbine driven refrigerant compressor may be needed. The refrigerant compressor turbine and main steam turbine must be synchronized in order to maintain the binary cycle effectiveness.