US 20150369084A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2015/0369084 A1 Levin (43) Pub. Date: Dec. 24, 2015
(54) SYSTEM FOR PREHEATING BOLER (52) U.S. Cl. FEEDWATER AND COOLING CONDENSER CPC. F0IK 7/40 (2013.01); F0IK 7/38 (2013.01); WATER F0IK 9/003 (2013.01), F22D 1/16 (2013.01) Applicant: Joel M. Levin, Wynnewood, PA (US) (71) (57) ABSTRACT (72) Inventor: Joel M. Levin, Wynnewood, PA (US) A system for pre-heating boiler feedwater and cooling con (21) Appl. No.: 14/749,226 denser water includes a boiler, a turbine, a turbine condenser, a heat pump, a first heat exchanger, a second heat exchanger, (22) Filed: Jun. 24, 2015 and an expansion valve. A water stream is heated by the boiler into a high pressure steam. The high pressure steam passes Related U.S. Application Data through the turbine and into the turbine condenser, converting (60) Provisional application No. 62/016,500, filed on Jun. the steam into condensate. The condensate is passed through 24, 2014. a heat receiving side of the first heat exchanger. A refrigerant stream is pressurized by the heat pump and is thereby heated. Publication Classification The refrigerant stream passes through a heat dissipating side of the first heat exchanger, heating the condensate. The refrig (51) Int. C. erant stream is then depressurized and cooled, and passes FOIK 7/40 (2006.01) through a heat receiving side of the second heat exchanger. A FOIK 9/00 (2006.01) condenser water stream passes through a heat dissipating side F22D L/6 (2006.01) of the second heat exchanger, cooling and entering the turbine FOIK 7/38 (2006.01) condenser. AN PREHEATED BOILERFEED WATER 10 BOILER
HIGH PRESSURE STEAM
CDWSIDESTREAM
TURBINE WARM CDW COOLING TOWER
LOWER PRESSURE STEAM
COOLER CDW
CONDENSATE TUREINE COLD CDW CONDENSER
CONDENSER
PREHEATHEAT WATER HEAT EXCHANGER LIQUID REFRIGERANT EXCHANGER (EVAPORATOR)
REFRIGERANT WAPOR - Patent Application Publication Dec. 24, 2015 Sheet 1 of 3 US 2015/0369084 A1
PREHEATED BOILER FEED WATER 10 BOILER
HIGH PRESSURE STEAM
CDW SIDESTREAM
TURBINE WARM CDW COOLING TOWER
LOWER PRESSURE STEAM
COOLER CDW
CONDENSATE TURBINE COLD CDW CONDENSER
2O CONDENSER
PREHEAT HEAT WATER HEAT EXCHANGER LIQUID REFRIGERANT EXCHANGER (EVAPORATOR) Patent Application Publication Dec. 24, 2015 Sheet 2 of 3 US 2015/0369084 A1
PREHEATED BOILER FEED WATER 10 BOILER
HIGH PRESSURE STEAM
WARM CDW TO RIVER
TURBINE
LOWER PRESSURE STEAM COOL CONDESER WATER FROM RIVER
CONDENSATE TURBINE CONDENSER
CONDENSER PREHEAT HEAT WATER HEAT EXCHANGER LIQUID REFRIGERANT EXCHANGER (EVAPORATOR)
HOT REFRIGERANT WAPOR REFRIGERANT WAPOR
HEAT PUMP 22
FIG.2 Patent Application Publication Dec. 24, 2015 Sheet 3 of 3 US 2015/0369084 A1
10 HIGH PRESSURE STEAM BOILER FEED WATER BOILER
26 TURBINE
LOWER PRESSURE STEAM TURBINE CONDENSATE FIG.3 CONDENSER (PRIOR ART) WARM CDW TO RIVER
COOL CONDESER WATER FROM RIVER
10 HIGH PRESSURE STEAM BOILER FEED WATER BOILER
26 TURBINE 14
LOWER PRESSURE STEAM TURBINE CONDENSATE CONDENSER
COOL CONDENSER WATER WARM CONDENSER WATER FIG.4 (PRIOR ART) COOLING TOWER
16 US 2015/0369084 A1 Dec. 24, 2015
SYSTEM FOR PREHEATING BOLER receiving side of the first heat exchanger, a refrigerant stream FEEDWATER AND COOLING CONDENSER is pressurized and thereby heated by the heat pump, passes WATER through a heat dissipating side of the first heat exchanger heating the condensate, passes through the expansion valve, CROSS-REFERENCE TO RELATED thereby depressurizing and cooling, and passes through a heat APPLICATION receiving side of the second heat exchanger, and a condenser 0001. This application claims the benefit of priority of water stream passes through a heat dissipating side of the U.S. provisional application No. 62/016,500, filed Jun. 24. second heat exchanger, cooling and entering the turbine con 2014, the contents of which are herein incorporated by refer denser. 0008. These and other features, aspects and advantages of CCC. the present invention will become better understood with BACKGROUND OF THE INVENTION reference to the following drawings, description and claims. 0002 The present invention relates to power plants and, BRIEF DESCRIPTION OF THE DRAWINGS more particularly, to a system for preheating boiler feedwater and cooling condenser water. 0009 FIG. 1 is a schematic view of an embodiment of the 0003. A steam turbine is a device that extracts thermal present invention; energy from pressurized steam and uses it to do mechanical 0010 FIG. 2 is a schematic view of an embodiment of the work on a rotating output shaft. The pressurized Steam passes present invention; through the turbine and exits at a lower pressure. A condenser 0011 FIG. 3 is a schematic prior art view; and lowers the temperature of the steam and condenses into con 0012 FIG. 4 is a schematic prior art view. densate in order to maximize the energy extracted from the steam. The condensate provides feed water that must be pre DETAILED DESCRIPTION OF THE INVENTION heated and returned to the boilers. The condensers are heat 0013 The following detailed description is of the best exchangers which convert Steam from its gaseous state to its currently contemplated modes of carrying out exemplary liquid State (condensate) at a pressure below atmospheric embodiments of the invention. The description is not to be pressure by using cooling water. taken in a limiting sense, but is made merely for the purpose 0004 Currently, the electric output from condensing of illustrating the general principles of the invention, since the steam turbine plants must be reduced (derated) when the scope of the invention is best defined by the appended claims. weather is hot and humid because of the limitations of their 0014. The present invention includes the use of an indus waste heat dissipation (cooling) systems. If cooling towers trial heat pump for condensing steam turbines, which reduces are used, the amount of heat that can be dissipated through cooling water requirements, fuel consumption, carbon emis evaporation is limited by the wet bulb temperature of the sions and derating losses. The industrial heat pump of the ambient air which limits the amount of heat that can be present invention preheats boiler feedwater five times more dissipated by the cooling tower. In systems that use cooling efficiently than a steam boiler. Therefore, fuel consumption is water from nearby bodies of water, the amount of heat that can reduced because the fuel previously required to preheat the be dissipated is reduced in hot and humid weather because the feedwater is no longer needed. By reducing fuel consump temperature of the source water becomes too warm and/or tion, the industrial heat pump reduces carbon emissions. because the thermal pollution of the warmer discharge water 0015. Further, the industrial heat pump generates breaches an environmentally acceptable level. mechanical cooling as an intrinsic part of its normal operating 0005. As can be seen, there is a need for a system to cycle. The heat pump extracts waste heat from the condenser optimize the efficiency of preheating boiler feedwater and water thereby cooling the condenser water. By providing minimizing the amount of cooling condenser water required. additional cooling while reducing fuel input, the industrial heat pump reduces the plant requirement for cooling water SUMMARY OF THE INVENTION and thereby also reduces the thermal pollution of the environ 0006. In one aspect of the present invention, a system for ment caused by the operation of the plant. The present inven pre-heating condensate comprises: a boiler; a turbine; a tur tion reduces the heat rate (BTUs per exported kWh) of a bine condenser, a heat pump; and a first heat exchanger, condensing turbine by approximately 2.5% and reducing the wherein a first fluid is heated by the boiler into a high pressure cooling water requirements by approximately 5%. steam, wherein the high pressure steam passes through the 0016. The condenser water that removes the latent heat turbine and into the turbine condenser and is converted into a from a condensing steam turbine provides an ideal low tem condensate, wherein the condensate is passed through a heat perature heat Source for an industrial heat pump. By extract receiving side of the first heat exchanger, and a second fluid is ing heat from this condenser water, the industrial heat pump pressurized and thereby heated by the heat pump and passes lowers the condenser water temperature, thereby reducing the through a heat dissipating side of the first heat exchanger, amount of cooling water that must be evaporated (or circu thereby heating the condensate. lated once-through) to dissipate the condenser water heat. 0007. In another aspect of the present invention, a system Because the industrial heat pump is a closed loop device, the for pre-heating condensate comprises: a boiler; a turbine; a cooling effect described above will remain the same regard turbine condenser, a heat pump; a first heat exchanger, a less of ambient temperature and humidity conditions. There second heat exchanger, and an expansion valve, wherein a fore, the frequency, depth and duration of derating events will water stream is heated by the boiler into a high pressure be reduced and/or eliminated. steam, wherein the high pressure steam passes through the 0017. In certain embodiments, the present invention may turbine and into the turbine condenser and is converted into a use an industrial pump sized to satisfy the boiler feedwater condensate, wherein the condensate is passed through a heat preheat load. Such that no excess heat is produced. Conse US 2015/0369084 A1 Dec. 24, 2015
quently there is no need for an external thermal load to absorb side of the preheat exchanger, thereby warming the conden the excess heat as there would be if the heat pump were sate. The hot refrigerant vapor is thereby cooled and con designed to cool the entire condenser water load. The present denses into a liquid refrigerant. The liquid refrigerant runs invention may utilize all of the heating and cooling output from the preheat heat exchanger through the expansion valve energy of the industrial heat pump within the turbine system. 24, thereby transferring from high pressure to low pressure, All of the heat may be used to preheat boiler feedwater, and all and cooling. The cooled refrigerant liquid runs through the of the output cooling energy may be used to reduce the tem heat receiving side of the condenser water heat exchanger 18, perature of the cooling water, thereby reducing the flow thereby cooling the condenser water and turning into a refrig requirements. Using the present invention, the parasitic load erant vapor. The refrigerant vapor is then pumped through the is only 3% of the plants electric output, and the fuel energy heat pump. saved by the enhanced heating efficiency is far greater than 0022. In certain embodiments, the refrigerant cycle C of the electric energy lost by the reduced electric output. the present invention may be used with an extraction steam 0018 Referring to FIGS. 1 through 4, the present inven turbine without a condensate return. An extraction turbine tion includes a turbine system A, a condenser water cycle B. taps off steam from the turbine casing at intermediate pres and a refrigerant cycle C. The turbine system A includes a Sures and uses this steam to satisfy other thermal loads. In boiler 10, a turbine 12 and a turbine condenser 14. Water and Some extraction turbine plants the steam condensate from the vapor run through the turbine system A. Feedwater is heated exported Steam is not returned to the boiler, and in this case by the boiler 10 into a high pressure steam. The high pressure the lost condensate must be replaced with makeup water that steam passes through the turbine 12 and exits as a lower is cooler than the turbine condensate. For example, if the pressure steam. The lower pressure steam enters the turbine temperature of the incoming makeup water is in the typical condenser 14 and is condensed into a condensate liquid. The range of 60°F., the heat pump contributes a higher percentage condensate liquid may be pumped through a heat receiving of the heating load because it may raise the temperature of the side of a preheat heat exchanger 20 by a pump 26. The incoming water by 120° F (from 60° F. to 180°F) in addition preheated condensate liquid is now preheated boiler feedwa to raising the temperature of the steam condensate from the ter, which is delivered to the boner 10. turbine from 100° F. to 180° F. In this case the fuel savings 0019. The turbine condenser 14 of the turbine system A would be even greater because the more efficient industrial receives cool water and discharges warm water via a con heat pump would be handling a larger percentage of the denser water cycle B. As illustrated in FIG. 2, cool water may heating load. be extracted from a body of water, such as a river. The cool 0023. When applied to an extraction steam turbine in water may be diverted into a first stream and a second stream. which the condensate from the exported Steam is not returned, The first stream may run through a condenser water heat the makeup water is cooler than the condensate. Therefore, exchanger 18 on the heat dissipating side, thereby lowering the energy required to preheat a given mass of makeup water the temperature of the water to a cold water. The cold water to 180 Deg. F is greater than the energy required to heat the then meets with the second stream of cool river water and runs same quantity of condenser water. Therefore, the size of the through the turbine condenser 14. The cold water lowers the industrial heat pump is increased to enable it to preheat both temperature of the cool river water. In alternate embodiments, the condensate and the makeup water. Therefore, the cooling the present invention may include a single stream that runs capacity of the industrial heat pump is also increased. As the through the heat dissipating side of the heat exchanger 18 and amount of exported Steam increases, the amount of conden then into the turbine condenser. Warm water may be dis sate decreases. Consequently the amount of condenser water charged from the turbine condenser into a body of water, such cooling also decreases while the cooling capacity of the heat as a river, or may be directed to the condenser water heat pump increases. This effect can be extended to the point exchanger 18 on the heat dissipating side. where the cooling capacity of the industrial heat pump is 0020. As illustrated in FIG. 1, the condenser water cycle B sufficient to provide 100% of the cooling required to remove may utilize a cooling tower 16. In Such embodiments, warm the heat from the condenser water. In this case we would have water discharged from the turbine condenser 14 may run extraction condensing steam turbine that requires no cooling through a first stream and a second stream. The first stream of water. The condenser water loop would become a closed loop warm water may run through the cooling tower 16, thereby system with a cooling coil. This would be very significant in lowering the temperature of the water into a cooler water. The dry climates where the availability of cooling water is prob second stream of warm water may run through a condenser lematic. water heat exchanger 18 on the heat dissipating side, thereby (0024. In use, the feedwater is boiled by the boiler 10 and lowering the temperature of the water into a cold water. The turned into high pressure steam. The high pressure steam cold water then meets with the cooler water and runs through drives the turbine 12 and passes through the turbine 12 losing the turbine condenser 14. The cold water lowers the tempera pressure. The lower pressure steam is cooled and turned into ture of the cooler water. In certain embodiments, outside a condensate via the turbine condenser 14. The condensate is water, such as cool river water may mix with the warm water pumped through a heat receiving side of the heat exchanger prior to entering the condenser water heat exchanger 18. 20. The hot refrigerant vapor is pumped through the heat 0021. The refrigerant cycle C of the present invention may dissipating side of the heat exchanger 20, thereby heating the include a heat pump 22, and expansion valve 24. Refrigerant water condensate into a preheated boiler feedwater. The two runs through the refrigerant cycle C. Refrigerant may include, fluid streams are separate and may run through the heat but is not limited to, fluorocarbons, such as chlorofluorocar exchanger 20 in opposite directions (counterflow). The hot bons, ammonia, Sulfur dioxide, and non-halogenated hydro refrigerant vapor may raise the temperature of the condensate carbons, such as propane. A hot refrigerant vapor may be from about 100° F. to about 180° F. The preheated boiler pumped by the heat pump 22 into the preheat heat exchanger feedwater may then return to the boiler 10. The refrigerant 20. The hot refrigerant may run through the heat dissipating runs through the expansion valve from high pressure to low US 2015/0369084 A1 Dec. 24, 2015
pressure, thereby significantly decreasing the temperature the turbine and into the turbine condenser and is con and the pressure. The cold refrigerant liquid passes through Verted into a condensate, wherein the condensate is the condenser water heat exchanger 18 on a heat receiving passed through a heat receiving side of the first heat side. Either water from an outside source or warm water from exchanger, and the turbine condenser 14 may pass through the heat dissipat a second fluid is pressurized and thereby heated by the heat ing side of the heat exchanger 18 and is thereby cooled off. pump and passes through a heat dissipating side of the The two fluid streams are separate and may run through the first heat exchanger, thereby heating the condensate. heat exchanger 18 in opposite directions (counterflow). The 2. The system of claim 1, wherein the condensate is heated flow of water is enough to vaporize the entire refrigerant. to about 180° F. while passing through the first heat Regardless of the weather, the condenser water in the heat exchanger, thereby becoming a preheated boiler feedwater. exchanger is cooled which reduces the total amount of cool 3. The system of claim 1, further comprising a pump pump ing water required by the plant. Further, the preheating of the ing the condensate from the turbine condenser to the first heat boiler feedwater using the hot refrigerant vapor reduces the exchanger. amount of fuel needed to run the turbine system. 4. The system of claim 1, wherein the first fluid is water and 0025. A method of making the present invention may the second fluid is a refrigerant. include the following. In order to construct this invention the flow rate of the boiler feedwater pump is determined, and then 5. The system of claim 1, further comprising: the amount of heat required to raise the temperature of the a second heat exchanger, and condensate to 180T is determined. One or more heat pump(s) an expansion valve, wherein with the total heating capacity determined above may be the second fluid passes through the expansion valve, installed near the turbine condenser and boiler feedwater thereby depressurizing and cooling, and passes through pump. A condensate heat exchanger is selected with the a heat receiving side of the second heat exchanger, and capacity to heat all of the pumped boiler feedwater to 180° F. a third fluid passes through a heat dissipating side of the This capacity may be approximately 470 BTUs per export second heat exchanger, cooling and entering the turbine able kWh from the turbine. The amount of BTUs depends on condenser. the performance characteristics of the turbine/generator set 6. The system of claim 5, wherein the third fluid is water. (pounds of steam per kWh generated). The condensate heat 7. The system of claim 6, wherein the third fluid is deliv exchanger may be installed in the boiler feedwater line, ered from an outside water source. downstream from the boiler feedwater pump. A second heat 8. The system of claim 7, wherein the outside water source exchanger, the condenser water heat exchanger, may be diverts into a first stream and a second stream, wherein the selected with the capacity to vaporize all liquid refrigerant first stream passes through the heat dissipating side of the produced by the condensate heat exchanger as it absorbs heat second heat exchanger and meets with the second stream, from the condenser water. The cooling capacity (BTUs per cooling the second stream and entering the turbine condenser. hour) of the condenser water heat exchanger may be approxi 9. The system of claim 6, further comprising a cooling mately 400 BTUs per hour per exportable kWh from the tower, wherein a warm water is discharged from the turbine turbine. The exact number may depend on the performance condenser into a first stream and a second stream, wherein the characteristics of the turbine/generator set (pounds of steam first stream passes through the heat dissipating side of the per kWh generated). The refrigeration cycle interfaces with second heat exchanger and the second stream passes through the turbine system and the condenser water cycle via the the cooling tower and meets with the first stream, cooling the condensate heat exchanger and the condenser water heat second stream and entering the turbine condenser. exchanger respectively. 10. A system for pre-heating condensate comprising: 0026. The present invention may be installed in an existing condensing Steam turbine power plant or may improve the a boiler; design of a new condensing steam turbine power plant. The a turbine; present invention reduces fuel consumption, the carbon foot a turbine condenser, print, cooling water requirements, reduce or eliminate derat a heat pump; ing events, and increase power plant profitability. Further, a first heat exchanger; incorporating an industrial heat pump reduces the initial capi a second heat exchanger, and tal costs for new powerplants because the size of the required an expansion valve, wherein cooling water systems could be reduced. a water stream is heated by the boiler into a high pressure 0027. It should be understood, of course, that the forego steam, wherein the high pressure steam passes through ing relates to exemplary embodiments of the invention and the turbine and into the turbine condenser and is con that modifications may be made without departing from the Verted into a condensate, wherein the condensate is spirit and scope of the invention as set forth in the following passed through a heat receiving side of the first heat claims. exchanger, What is claimed is: a refrigerant stream is pressurized and thereby heated by 1. A system for pre-heating condensate comprising: the heat pump, passes through a heat dissipating side of a boiler; the first heat exchanger heating the condensate, passes a turbine; through the expansion valve, thereby depressurizing and a turbine condenser; cooling, and passes through a heat receiving side of the a heat pump; and second heat exchanger, and a first heat exchanger, wherein a condenser water stream passes through a heat dissipating a first fluid is heated by the boiler into a high pressure side of the second heat exchanger, cooling and entering steam, wherein the high pressure steam passes through the turbine condenser. US 2015/0369084 A1 Dec. 24, 2015
11. The system of claim 10, wherein the condensate is heated to about 180° F. while passing through the first heat exchanger, thereby becoming a preheated boiler feedwater. 12. The system of claim 10, further comprising a pump pumping the condensate from the turbine condenser to the first heat exchanger. 13. The system of claim 10, wherein the condenser water is delivered from an outside water source. 14. The system of claim 13, wherein the outside water Source diverts into a first stream and a second stream, wherein the first stream passes through the heat dissipating side of the second heat exchanger and meets with the second stream, cooling the second stream and entering the turbine condenser. 15. The system of claim 10, further comprising a cooling tower, wherein the condenser water stream comprises a warm water discharged from the turbine condenser into a first stream and a second stream, wherein the first stream passes through the heat dissipating side of the second heat exchanger and the second stream passes through the cooling tower and meets with the first stream, cooling the second stream and entering the turbine condenser. k k k k k