Patent Application
20230258327
This invention relates to pumps for pumping fluids.
There is a need to increase the production of electrical power without increasing the adverse effects of power generation on the environment. One approach to this challenge is to increase the operating efficiency of existing and future power plants. It is estimated that power plants burning fossil fuels operate at an efficiency of about 33%, leaving much room for improvement. Even nuclear power plants, which operate at an estimated 34% efficiency, could benefit from an increase in plant operating efficiency.
In one embodiment the invention concerns a pump for injecting liquid water into a control volume. In an example embodiment the pump comprises a liquid water reservoir. A water conduit provides fluid communication between the liquid water reservoir and the control volume. An exhaust valve is positioned within the water conduit for controlling flow of the liquid water from the liquid water reservoir into the control volume. The example pump further comprises a steam reservoir and a steam conduit providing fluid communication between the steam reservoir and the water conduit. A steam injector valve is positioned in the steam conduit for controlling flow of the steam from the steam reservoir into the water conduit. Opening the steam injector valve injects steam into the water conduit, the steam condenses on a water-steam interface thereby creating a partial vacuum within the water conduit. The liquid water from the liquid water reservoir accelerates into the partial vacuum creating a pressure and momentum pulse within the water conduit. The exhaust valve opens to permit a burst of the liquid water to be injected into the control volume.
In an example embodiment the control volume contains a high internal pressure, and the exhaust valve opens when the pressure and momentum pulse exceeds the high internal pressure within the control volume thereby permitting a burst of the liquid water to be injected therein. In a specific example the exhaust valve comprises a check valve which could be a remotely controlled valve. By way of further example the exhaust valve may be positioned proximate to an interface between the water conduit and the control volume. In another example the steam injector valve may be positioned proximate to the exhaust valve. An example embodiment may comprise a plurality of the steam injector valves positioned proximate to the exhaust valve. In a specific example embodiment the plurality of the steam injector valves are positioned in spaced relation around a perimeter of the water conduit. Another example embodiment may comprise a plurality of the steam injector valves positioned in spaced relation lengthwise along the water conduit. By way of example, at least one steam injector valve of the plurality is positioned proximate to the exhaust valve.
An example pump according to the invention may further comprise a cooling water reservoir and a cooling water conduit providing fluid communication between the cooling water reservoir and the water conduit. A cooling water injector valve is positioned within the cooling water conduit for controlling flow of cooling water from the cooling water reservoir into the water conduit. Opening the cooling water injector valve permits the cooling water to enter the water conduit, thereby increasing a rate of condensation of the steam within the water conduit.
In a specific example embodiment the cooling water injector valve is positioned proximate to an interface between the cooling water conduit and the water conduit. By way of further example the cooling water injector valve may be positioned proximate to the steam injector valve. An example embodiment may comprise a plurality of the cooling water injector valves positioned proximate to the steam injector valve. By way of further example the plurality of the cooling water injector valves may be positioned in spaced relation around a perimeter of the water conduit. In another example a plurality of the cooling water injector valves may be positioned in spaced relation lengthwise along the water conduit. In a specific example at least one of the cooling water injector valves of the plurality is positioned proximate to the steam injector valve.
An example embodiment may further comprise a coolant pump positioned between the cooling water reservoir and the cooling water conduit for pumping the cooling water from the cooling water reservoir into the water conduit. By way of example the cooling water reservoir may comprise the liquid water reservoir. An example embodiment of a pump according to the invention may further comprise the control volume. In an example embodiment the control volume may comprise a steam boiler. In another example the control volume may comprise a plenum in fluid communication with the steam boiler. By way of further example the steam boiler may comprise the steam reservoir.
A further example embodiment may comprise a flow conditioning element positioned within the water conduit. In a specific example the flow conditioning element may comprise a vortex generator comprising at least one vane.
An example pump according to the invention may further comprise a control system. The control system may selected from the group including a programmable controller, an analog controller, a mechanical controller or a simple periodic wave form controller. By way of example the pump may further comprise a programmable controller and at least one sensor positioned within the water conduit. The at least one sensor is adapted to measure a physical parameter within the water conduit and transmit a signal indicative of the physical parameter to the programmable controller. By way of example the programmable controller is in communication with the steam injector valve for controlling opening and closing thereof, and the programmable controller may also be in communication with the exhaust valve for controlling opening and closing thereof. In an example embodiment the physical parameter may comprise pressure, temperature, flow rate, or void fraction, or a combination thereof within the water conduit.
The invention also encompasses a method of injecting liquid water into a control volume. In an example embodiment the method comprises:
By way of example, the method according to the invention may further comprise forming turbulent flow of the liquid water at the steam-water interface as well as cooling the steam proximate to the steam-water interface. In an example embodiment the cooling may comprise injecting cooling water into the partial vacuum region.
As shown in
Pump 10 further includes a steam reservoir 24 and a steam conduit 26 which provides fluid communication between the steam reservoir 24 and the water conduit 18. A steam injector valve 28 is positioned in the steam conduit 26 for controlling flow of steam 30 from the steam reservoir 24 into the water conduit 18. Steam conduit 26 is connected to water conduit 18 at a point 23 between water reservoir 16 and the exhaust valve 20. It is considered advantageous to position the connection point 23 and the steam injector valve 28 proximate to the exhaust valve 20. However, placement can be optimized as common practice.
Operation of pump 10 proceeds by opening the steam injector valve 28, thereby injecting steam 30 into the water conduit 18 which pushes water in conduit 18 in the backward direction towards reservoir 16. The steam 30 condenses on a water-steam interface 32 created upon steam injection. The condensing steam creates a region of partial vacuum 34 within the water conduit 18. The liquid water 12 from the liquid water reservoir 16 then moves in the forward direction toward the control volume 14, and accelerates into the partial vacuum creating a pressure and momentum pulse within the water conduit 18. The pressure and momentum pulse, commonly known as the “steam hammer effect”, is described by the Joukowsky equation, which equates the change in pressure to the product of the density of the fluid, the speed of sound in the fluid, and the change in fluid velocity. In its simplest form, the energy of this “steam hammer” may be harnessed by judiciously opening steam injector valve 28, thereby creating a steam bubble that condenses and collapses in a favorable way to cause a localized pressure build up greater than the pressure in control volume 14. The exhaust valve 20 permits a burst of the accelerating liquid water 12 to be injected into the control volume 14 because of the higher local pressure than in the control volume 14, and because of the kinetic energy of the water mass and associated velocity inside conduit 18 in the direction of the exhaust valve 20.
In an example application of pump 10, if the control volume 14 contains a high internal pressure (as in a steam boiler), the exhaust valve 20 may advantageously comprise a check valve which opens when the pressure and momentum pulse within water conduit 18 near check valve 20 exceeds the high internal pressure within the control volume 14 (steam boiler) thereby permitting a burst of the liquid water to be injected therein. As the kinetic energy is converted to pressure and flow, the pressure will decrease resulting in back flow water hammer within the water conduit 18 which would otherwise occur when the exhaust valve 20 closes abruptly once the pressure in the control volume 14 and the water conduit 18 equalizes. The back flow water hammer effect is mitigated, for example, by the use of “nozzle check” valves, commercially available from Crane ChemPharma & Energy of The Woodlands, Texas, under the brand “NOZ-CHEK®” as well as other vendors with similar designs.
In an example application wherein the control volume 14 is at a relatively low pressure, for example, atmospheric, the exhaust valve 20 may comprises a remotely controlled valve. In this application, pump 10 may further comprise a control system 35, for example, a programmable controller 36, such as an Allen Bradley Programmable Logic Controller marketed by Rockwell Automation of Milwaukee, Wisconsin, and optionally one or more sensors 38 positioned within the water conduit. Analog controllers, mechanical controllers or simple periodic wave form controllers could also comprise a practical control system. Sensors 38 may be adapted to measure various physical parameters, such as temperature, flow rate and void fraction (the fraction of the channel volume or channel cross sectional area that is occupied by the gas phase) within the water conduit 18 and transmit a signal indicative of the physical parameters to the programmable controller 36. In this example the physical parameter is advantageously pressure. The programmable controller 36 is in communication with both the steam injector valve 28 and the exhaust valve 20 for controlling and thus coordinating the opening and closing of both valves to effect pumping of water from the liquid water reservoir 16 to the control volume 14, which, for example, could comprise the ambient, or higher pressure if required. It is also understood that analog controllers, mechanical controllers or simple periodic wave form controllers could also be used to control both the steam injector valve 28 and the exhaust valve 20 through mechanical or electromechanical devices, linkages and mechanisms.
Performance of pump 10 may be adjusted by the positioning and number of steam injector valves 28 on the water conduit 18. As noted, it is advantageous to position at least one steam injector valve 28 proximate to the exhaust valve 20. This position of the steam injector valve 28 allows the region of partial vacuum 34 to be created between most of the liquid water 12 within the water conduit 18 and the exhaust valve 20 for maximum injection of liquid water into the control volume 14. By way of further example, pump 10 may comprise a plurality of the steam injector valves 28 positioned proximate to the exhaust valve 20. In this example, as shown in
As further shown in
Further performance enhancements may be achieved using a plurality of the cooling water injector valves 46 positioned proximate to the steam injector valve 28, as shown by way of example in
In an example embodiment shown in
Performance of pump 10 may also be enhanced using flow conditioning elements within the water conduit 18. As shown in
The invention further encompasses a method of injecting liquid water into a control volume. As shown with reference to
Additional steps may include: forming turbulent flow of the liquid water at the steam-water interface (66); cooling the steam proximate to the steam-water interface (68) by, for example, injecting cooling water into the partial vacuum region.
A further embodiment of the invention comprises a method of projecting liquid water from a conduit having one end in fluid communication with a liquid water reservoir, and an opposite end closed by a valve. As shown in
Additional steps may include: forming turbulent flow of the liquid water at the steam-water interface (78); cooling the steam proximate to the steam-water interface (80) by, for example, injecting cooling water into the partial vacuum region.
When it is desired to inject liquid water 12 into boiler 88, the steam injector valve 28 is opened and injects steam 30 into the water conduit 18. It is advantageous if the temperature of the steam is 20° C. (36° F.) higher than the temperature of the water in the water conduit 18. Further advantage may be secured of the length to diameter ratio of water conduit 18 is greater than 24, as this is expected to promote a vigorous condensing water hammer. The steam 30 condenses on the water-steam interface created by the injected steam, thereby creating the region of partial vacuum within the water conduit 18. The liquid water from the water reservoir 16 accelerates into the partial vacuum creating a pressure and momentum pulse within the water conduit 18. The exhaust valve 20 opens, permitting a burst of the liquid water 12 to be injected into the steam boiler 88 by the water conduit 18. In an example embodiment, exhaust valve 20 may comprise a check valve which opens automatically when the magnitude of the local pressure and momentum pulse exceeds the pressure within the steam boiler 88. Back flow water hammer within the water conduit 18, which would otherwise occur when the exhaust valve 20 closes abruptly, is mitigated by the use of a “nozzle check” valve as described above.
In another example embodiment, the exhaust valve 20 may comprise a remotely controlled valve. In this example facility 82 further comprises the control system 35, for example, the programmable controller 36 and one or more sensors 38 positioned within the water conduit 18. In this example the sensor 38 is adapted to measure pressure within the water conduit 18 and transmit an electrical signal indicative of the pressure to the programmable controller 36. The programmable controller 36 is in communication with both the steam injector valve 28 and the exhaust valve 20 for controlling the timing and duration of the opening and closing of both the exhaust valve 20 and the steam injector valve 28. It is also understood that the control system 35 could comprise analog controllers, mechanical controllers or simple periodic wave form controllers to control both the steam injector valve 28 and the exhaust valve 20 through mechanical or electromechanical devices, linkages and mechanisms.
Detailed design concerning the number and placement of the steam injector valves 28 in the water conduit 18 of pump 10 used in the facility 82 is as described above for the pump 10. Design and operation of the cooling water system comprising the cooling water reservoir 42, cooling water conduit 44 and cooling water spray injector valves 46 is also as described above. In the example embodiment of
It is expected that example pumps 10 according to the invention will have many beneficial uses. Because pump 10 can use the boiler pressure steam to feed water to the boiler at an even greater pressure, it does not need multiple stages to pump from condensate and is expected to obviate the use of condensate booster and feedwater pumps. Furthermore, it does not use “House” electrical energy to pump the water. Thus, it increases the electrical output of the power station. Additionally, steam energy is not wasted in the condenser because much of the driving steam energy is returned to the boiler. It is expected that much of the warmer water stream extracted from the turbine could be pumped using pumps according to the invention if the steam in the water stream is separated from the water stream and steam jet ejectors are used to lower tank pressure. In this way, boiler energy is not wasted through condensation because the condenser is bypassed. This is expected to lower the heat load on the condenser, lower the condenser’s overall cooling temperature and increase generator efficiency. If the steam pump and steam ejector is optimized, it could completely bypass the condenser. Use of pump 10 is expected to increase thermal efficiency from the current 34% to over 90% in nuclear power plants for example. This has great potential advantage because much less fuel would be required at higher thermal efficiencies. Lower fuel cost also reduces the nuclear waste stream. Use of example pumps 10 according to the invention may radically disrupt the tradition “Rankine” cycle used for electrical generation plants. The Rankine cycle requires all turbine output to be condensed (and thus wastes energy) because centrifugal water pumps must pump water, not a mix of water and steam. It is expected that the same approach might be used to reduce fossil fueled burn rate and thus reduce production of CO2 of current legacy power plant thermal generation. It is estimated that power plants 82 shown by way of example using pumps 10 with optimal configuration according to the invention may have global impact by reducing electrical production costs and CO2 emissions up to 65%.
