Patent Grant
12031468
Not Applicable.
Exhaust gases from a variety of processes and/or combustion of a variety of fuels typically include one or more harmful substances such as carbon monoxide and/or nitrogen oxide. For example, combustion of natural gas or other fossil fuels in power plants generates a hot exhaust gas stream including carbon monoxide, nitrogen oxides, and/or other exhaust gases. Chemical production, hydrocarbon cracking, steel production, and other processes similarly generate a hot exhaust gas stream including harmful substances. Typically, an exhaust gas stream is treated with one or more catalysts (e.g., in a catalyst bed) to mitigate carbon monoxide, nitrogen dioxide, and/or other substances. For example, catalysts can be used to convert nitrogen dioxide and/or carbon monoxide to one or more of water, diatomic nitrogen, carbon dioxide, and/or other less harmful compounds. To treat nitrogen oxides using a catalyst, typically a reactant is used such as anhydrous ammonia or an aqueous solution of ammonia that is introduced upstream of a selective catalytic reaction (SCR) catalyst.
Each catalyst and/or reactant has an operating temperature range that optimizes the desired reaction to mitigate components of the exhaust gas. Additionally, the catalyst or reactant itself and/or the housing (e.g., SCR) or material containing the catalyst and/or reactant can be damaged if the temperature of the exhaust gas exceeds the mechanical/chemical design limits for the catalyst or housing. Therefore, it is sometimes advantageous to controllably reduce the temperature of the exhaust gas prior to passing the exhaust gas into the catalyst materials such that the exhaust gas is within a temperature range for optimum treatment of certain components within the exhaust gas.
Many existing exhaust gas cooling systems and exhaust treatment systems suffer from poor performance, lifespan, efficiency and the like due to the limitations of cooling systems and the requirements of the exhaust treatment systems described above.
The cooling system described in the present disclosure provides several advantages over the typical gas turbine exhaust gas treatment system. Through use of disclosed system to cool gas turbine exhaust gas, the turbine exhaust gas temperature is controllable to be within the range for treatment with one or more catalysts (e.g., catalyst treatment of carbon monoxide, selective catalytic reduction, SCR, treatment of nitrogen oxides, etc.). Cooling the turbine exhaust allows for the removal of the typical equipment used in treatment, such as forced draft fans, induced draft fans and direct water injection. Exhaust fans are typically energy inefficient and water injection, which has the costs associated with a certain degree of chemical treatment, can lead to formation of undesirable aerosols, premature corrosion of components, and poor performance of the emission catalyst. Preprocessing the turbine exhaust gas to lower the temperature using a system of the type described herein is more energy efficient than using forced draft or induced draft fans generally due to the power consumption associated with moving air (e.g., with a blower, fan, compressor or the like) in comparison to the lesser energy consumption of circulating a liquid (e.g., with a pump). The disclosed system also forgoes the use of direct injection of water into the exhaust and thus removes the potential negative effects of water injection described above. The use of a working fluid as described herein to cool turbine exhaust gas prior to catalytic treatment also allows for greater control over the temperature of the turbine exhaust gas at one or more positions. For example, a working fluid can be used to control the turbine exhaust gas temperature prior to treatment for carbon monoxide at a first location and within a first temperature range, and the temperature of the turbine exhaust gas can be controlled at a second location prior to treatment for nitrous oxides and within a second, different temperature range. Controllability allows for the optimum temperature for different catalytic reactions.
Thus, the controllability provided by the use of a working fluid to cool turbine exhaust gas allows for a decrease in energy consumption in comparison to the use of other techniques (e.g., forced induction fans), and the use of controllable cooling by a working fluid allows for optimization of the catalytic reactions used to treat the turbine exhaust gas. These advantages of the presently described turbine exhaust gas treatment system allow for these and/or other benefits. Use of a working fluid to cool turbine exhaust gas also provides an advantage in that the heat of the turbine exhaust gas can be removed and captured by the working fluid. The energy removed from the turbine exhaust gas can be recovered directly by a mechanical connection to a device such as a pump (e.g., the pump being driven by the working fluid), indirectly using expansion through a suitable device connected to an electrical generator (e.g., the working fluid driving an energy recovery turbine coupled to a generator), or the heat recovered by the working fluid can be used to heat up a separate process fluid (e.g., using a heat exchanger to transfer heat from the working fluid to the separate process fluid).
In another embodiment of the disclosure, in a gas turbine exhaust gas treatment system described herein, a first heat exchanger is positioned in the flow path of exhaust gas from a gas turbine and in front of a catalytic converter such as a Selective Catalytic Reducer (SCR). The first heat exchanger is operable to control the turbine exhaust gas temperature and cool the turbine exhaust gas temperature to be within the range for treatment with one or more catalysts of the SCR. The working fluid cycled through the first heat exchanger cools the turbine exhaust gas and allows for greater control over the temperature of the turbine exhaust gas prior to catalytic treatment as the exhaust gas flows through the SCR.
The working fluid heated by the turbine exhaust gas passing through the first heat exchanger is delivered from the first heat exchanger to a system for distributing the heat of the working fluid, for example district heating or heat networks for general use.
On exiting the district heating, the working fluid is then delivered through a pump to a second heat exchanger positioned in the flow path of the turbine exhaust gas exiting the SCR. The second heat exchanger recovers some final residual heat from the turbine exhaust gas exiting the SCR and further cools the exhaust gas and then directs the working fluid back to the first heat exchanger.
Other benefits and features of the cooling system of the present disclosure will be apparent in view of the disclosed hereinafter.
Corresponding reference characters and symbols indicate corresponding parts throughout the several views of the drawings.
The following detailed description illustrates the disclosed turbine exhaust gas treatment system and associated methods by way of example and not by way of limitation. The description enables one of ordinary skill in the relevant art to which this disclosure pertains to make and use the turbine exhaust gas treatment system. This detailed description describes several embodiments, adaptations, variations, alternatives, and uses of the turbine exhaust gas treatment system, including what is presently believed to be the best mode of implementing the claimed turbine exhaust gas treatment system and associated methods. Additionally, it is to be understood that the disclosed turbine exhaust gas treatment system is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The disclosure is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
Referring generally to
The exhaust gas treatment system cools high temperature turbine exhaust gases to optimum temperature ranges to promote the desired chemical reactions that take place to treat exhaust components while simultaneously protecting the catalyst systems from suffering mechanical damage due to overheating. This is achieved without use of large forced draft fans or induced draft fans. No additional atmosphere or other gases need be added to the turbine exhaust gas, for the purpose of cooling the turbine exhaust gasses, before the turbine exhaust gas is treated with one or more catalytic processes. In some embodiments, additional atmosphere or other gases are added indirectly to the turbine exhaust gases, but this is not to cool the turbine exhaust gases but is rather to facilitate the treatment of the turbine exhaust gases. For example, when treating nitrogen oxides of the turbine exhaust gas stream ammonia can be used. In such a case, the ammonia can be aqueous such that the ammonia is mixed with atmospheric air in a mixing tank where the aqueous ammonia is flashed into and diluted with the atmosphere in the mixing tank prior to injection into the turbine exhaust gas.
A heat transfer coil upstream of the catalyst system(s) is used to treat the turbine exhaust gas to reduce the hot gas temperature to targeted ranges for safer and more efficient catalyst operation. The recovered heat removed from the hot turbine exhaust gas is dissipated to ambient via air and/or water-cooled heat exchangers. Alternatively, the removed heat can be used to heat up external process streams (e.g., using a heat exchanger), recovered by mechanical application (e.g. the removed heat can drive a pump), or the removed heat can be recovered through direct expansion of the thermal working fluid using a device connected to an electrical generator (e.g., the thermal fluid can be expanded to drive a turbine which in turn drives an electrical generator). Additional heat transfer coils can be positioned within the gas stream to allow different turbine exhaust gas temperatures to be achieved at different points within the turbine exhaust gas stream.
This temperature control allows for improved treatment of the turbine exhaust gas. For example, typically the targeted optimum temperature range for the carbon monoxide treating catalysts does not overlap with the optimum temperature range for the nitrogen oxides treatment reactions. The temperatures for treating carbon monoxide are higher than the temperatures for treating nitrogen oxides. As a result, the carbon monoxide treatment catalyst can operate in a hotter temperature range, below an upper limit, than the SCR catalyst. The use of multiple cooling coils (e.g., heat exchangers) allows for the temperature of the turbine exhaust gas stream to be controlled to improve the effectiveness of the catalytic treatment.
In some embodiments of the turbine exhaust gas treatment system, the system uses supercritical carbon dioxide as the working fluid. This provides some specific advantages in that supercritical carbon dioxide has a high fluid density making it easy to pump around a closed cooling loop and a high heat capacity such that the system can use a lower amount of fluid passing through the heat exchanger coil for the same temperature reduction of hot turbine exhaust gas. Other suitable heat transfer working fluids including, but not limited to, thermal oils and/or water can be utilized in other embodiments of the turbine exhaust gas treatment system. The system uses cooling loops to cool the turbine exhaust gas stream to be treated. It should be understood that “cooling loop” used herein refers to the equipment used in a refrigeration cycle to provide a cooled working fluid to a heat exchanger to cool the turbine exhaust gas or any other gas to be treated. For example, the cooling loop can include piping, conduits, or the like to contain and allow for the transfer of working fluid; a condenser; a pump; an expansion nozzle; an evaporator; and/or other components (e.g., a shared or dedicated mass inventory system) to provide for a refrigeration cycle for cooling the turbine exhaust gas to be treated. The piping, conduits, or the like provide for fluid communication of the working fluid between the other components of the cooling loop.
Referring now to
The turbine exhaust gas passing through the turbine exhaust gas discharge structure 102 passes over/through a catalytic turbine exhaust gas treatment device 104. The catalytic turbine exhaust gas treatment device 104 is positioned at least partially within the turbine exhaust gas discharge structure 102 such that turbine exhaust gas comes into contact with the catalytic exhaust gas treatment device 104. The catalytic exhaust gas treatment device 104 is adapted and configured to treat at least one component of the turbine exhaust gas through a catalytic reaction between a catalyst contained within the catalytic exhaust gas treatment device 104 and the at least one component of the turbine exhaust gas. For example, the catalytic exhaust gas treatment device 104 contains any suitable agent to react with carbon monoxide to form carbon dioxide. For example, carbon monoxide can be treated using platinum, rhodium, palladium, oxidizers generally, or any other suitable catalyst(s).
The system 100 can further include a second catalytic turbine exhaust gas treatment device 106 positioned within the turbine exhaust gas discharge structure 102 and downstream of the first catalytic turbine exhaust gas treatment device 104. The second catalytic turbine exhaust gas treatment device 106 is adapted and configured to treat at least one component of the turbine exhaust gas through a catalytic reaction between a catalyst contained within the second catalytic turbine exhaust gas treatment device 106 and the at least one component of the turbine exhaust gas. For example, the second catalytic exhaust gas treatment device 106 contains any suitable agent to react with nitrogen oxides to form one or more of water, diatomic nitrogen, or other compounds. The agent can be or include a reactant such as anhydrous ammonia, an aqueous solution of ammonia, or the like.
In some embodiments, the first catalytic turbine exhaust gas treatment device 104 is adapted and configured to treat both carbon monoxide and nitrogen oxides within the turbine exhaust gas. The first catalytic turbine exhaust gas treatment device 104 can treat both carbon monoxide and nitrogen oxides using multiple catalysts or a single catalyst. For example, in the case of a single catalyst, the first catalytic turbine exhaust gas treatment device 104 can include iron and cobalt impregnated over activated semi-coke. The catalyst is fed with carbon monoxide (e.g., from the turbine exhaust gas) to absorb or otherwise remove nitrogen oxides from the turbine exhaust gas. Other single catalysts can be used to treat both carbon monoxide and nitrogen oxide such as a barium-promoted copper chromite catalyst or any other suitable catalyst.
In order to reduce the temperature of the turbine exhaust gas to within a range suitable for treatment with the catalytic exhaust gas treatment device 104, the system includes a first heat exchanger 108. The first heat exchanger 108 is positioned at least partially within the turbine exhaust gas discharge structure 102 and upstream of the catalytic turbine exhaust gas treatment device 104. The first heat exchanger 108 is adapted and configured to remove heat from turbine exhaust gas passing through the turbine exhaust gas discharge structure 102 by transferring heat to a working fluid (e.g., carbon dioxide) passing through and within the first heat exchanger 108. The working fluid passes through a cooling loop to continuously (e.g., on demand) provide cooling to the turbine exhaust gas during operation of the system 100 for treating turbine exhaust gas. It should also be understood that the turbine exhaust gas can be cooled for a purpose other than improving the treatment of the turbine exhaust gas (e.g., for the reduction in carbon monoxide and/or nitrogen oxides). For example, the turbine exhaust gas can be cooled to maintain the turbine exhaust gas within a specific temperature range irrespective of a temperature range for treating the turbine exhaust gas. This can allow for processing of the turbine exhaust gas into other products or other uses of the turbine exhaust gas.
Cooled working fluid passes through the first heat exchanger 108 and leaves the first heat exchanger 108 with additional heat. The working fluid leaving the first heat exchanger enters a second heat exchanger 110 positioned downstream of the first heat exchanger 108. The second heat exchanger 110 is adapted and configured to remove heat from the working fluid gained at the first heat exchanger 108. The second heat exchanger 110 can be a condenser that facilitates a phase change of the working fluid from a gas or partial gas exiting the first heat exchanger 108 to at least partially a liquid exiting the second heat exchanger 110. This can facilitate pumping of the working fluid. Alternatively, the second heat exchanger 110 simply removes heat from the working fluid.
In some embodiments, the second heat exchanger 110 is an air-cooled heat exchanger, and in other embodiments the second heat exchanger 110 is a water-cooled heat exchanger. The second heat exchanger 110 can include a fan passing air over the second heat exchanger 110. The second heat exchanger 110 can transfer heat to the atmosphere. In some embodiments, the second heat exchanger 110 can be or include a cooling tower or evaporative cooler.
The working fluid (e.g., carbon dioxide) leaving the second heat exchanger 110 is received at a pump 112 positioned downstream of the second heat exchanger 110. The pump 112 is adapted and configured to drive the working fluid through the cooling loop. The pump 112 can be driven by an electric motor such as a variable frequency drive motor. The pump 112 is adapted and configured to pump supercritical carbon dioxide (or any other applicable fluid). In alternative embodiments (described later with reference to other Figures herein), the working fluid can change phases within the cooling loop and the pump 112 can be adapted and configured to pump a mixed phase working fluid. The pump 112 can compress the working fluid or can simply pump the working fluid.
The pump 112 drives the carbon dioxide working fluid through the cooling loop to an expansion nozzle 114. The expansion nozzle 114 is positioned downstream of the pump 112 and upstream of the first heat exchanger 108. The expansion nozzle 114 is adapted and configured to expand the supercritical carbon dioxide working fluid to reduce the temperature of the working fluid prior to the working fluid entering the first heat exchanger 108. The expansion nozzle 114 can be adapted and configured to change the phase of at least a portion of the working fluid. Alternatively, the expansion nozzle 114 expands the working fluid without the working fluid changing phase. The use of the expansion nozzle 114 reduces the temperature of the working fluid such that a lesser amount of working fluid is needed to achieve a targeted gas temperature at the inlet of the catalytic exhaust gas treatment device 104 (in comparison to a system without an expansion nozzle 114). The reduced temperature allows for use of less working fluid.
The system 100 includes a bypass loop which can include a bypass nozzle 116. The bypass loop (which can include a bypass nozzle 116) is adapted and configured to controllably and selectively permit the working fluid to bypass the expansion nozzle 114. The expansion nozzle 114 can be bypassed using the bypass 116 if sufficient cooling is being provided by the second heat exchanger 110 removing heat from the working fluid. For example, the ambient temperature can be sufficiently low that the second heat exchanger 110 provides sufficient cooling of the turbine exhaust gas. Bypassing the expansion nozzle 114 allows the system 100 to avoid or reduce the pressure drop associated with use of the expansion nozzle 114. Bypassing the expansion nozzle 114 and forgoing the associated pressure drop increases efficiency as the energy required to pump the working fluid is reduced when the pressure is maintained.
In embodiments including a bypass nozzle 116, the bypass is adapted and configured to bypass the expansion nozzle 114 such that the working fluid is expanded by the bypass expansion nozzle 116 instead. The bypass nozzle 116 is adapted and configured to expand the working fluid to a lesser degree than the expansion nozzle 114. Alternatively, the bypass nozzle 116 can expand the working fluid to a greater degree than the expansion nozzle 114 such that the expansion nozzle 114 is bypassed when additional cooling is desired to maintain the exhaust gas temperature within a range suitable for treatment as described herein. In another embodiment, the bypass nozzle 116 can be designed so to minimize or reduce expansion of the fluid passing through the bypass. The bypass valve and the expansion nozzle functionally can be a throttling valve or fixed device, and can be manually or automatically actuated.
The system 100 further includes a mass inventory management system 118. The mass inventory management system 118 is adapted and configured to manage the amount of working fluid within the cooling loop that includes the first heat exchanger 108. The mass inventory management system 118, in order to manage the amount of working fluid in the cooling loop, is adapted and configured to controllably receive working fluid from downstream of the first heat exchanger 108. The mass inventory management system 100 is still further adapted and configured to add or remove working fluid from the cooling loop.
The mass inventory management system 118 controllably removes working fluid from downstream of the first heat exchanger 108 (e.g., using a controllable valve) at a takeoff point 120. Working fluid removed from the cooling loop at the takeoff point 120 passes through a valve to a pump 122. The pump 122 drives the working fluid from the takeoff point 120 to the mass inventory management system 118. The working fluid pumped by the pump 122 passes through a further valve on the way to the mass inventory management system 118.
In the expanded schematic of the inventory management system in
A controllable valve 130 (e.g., the valve can be an open/close discrete valve with a generally fixed flow restriction but also can be an active flow control valve with flow controlling characteristic permitting variable flows) is positioned downstream of the second tank 128 to control the addition of working fluid into the cooling loop. The controllable valve 130 is positioned to discharge working fluid from the mass inventory management system 118 into the cooling loop downstream of the second heat exchanger 110 and upstream of the pump 112. The mass inventory management system 118 is also adapted and configured to controllably receive working fluid from the cooling loop at a second takeoff point 132 positioned downstream of the pump 112 and upstream of the expansion nozzle 114.
Still referring to
Using these sensors and controllable devices (e.g., valves), the system 100 is controlled in operation. The system 100 is primarily controlled based on the turbine exhaust gas temperature entering the catalytic turbine exhaust gas treatment device 104 located within the hot turbine exhaust gas stream and within the turbine exhaust gas discharge structure 102. The system can also or alternatively be controlled based on the turbine exhaust gas temperature entering the second catalytic turbine exhaust gas treatment device 106. The set point temperature for the hot turbine exhaust gas temperature at the catalyst face (e.g., at the entrance to the first and/or second catalytic turbine exhaust gas treatment device) is used to modulate the variable frequency drive motor driving the pump 112. This in turn controls the flow rate of the working fluid around the cooling loop with more flow being provided when the turbine exhaust temperature at the catalyst face is hotter than the set point. In alternative embodiments, the pump 112 is not driven by a variable frequency drive motor and instead a flow control valve is positioned downstream of the pump 112. Such a flow control valve is used to control the flowrate of the working fluid through the cooling loop to in turn control the temperature of the turbine exhaust gas.
In some embodiments, the system 100 is controlled by having a flow rate set by controlling the turbine exhaust gas temperature at the face of the catalytic turbine exhaust gas treatment device 104 with the working fluid passing through the bypass valve 116. When the pump flow rate reaches a predetermined level, the flow can be modulated through the bypass valve 116 so as to control the temperature of the turbine exhaust gases at the face of the catalytic turbine exhaust gas treatment device 104.
In embodiments of the system 100 including a heat exchanger utilizing a fan (e.g., the second heat exchanger 110), the sequencing of the fan ON/OFF within the heat exchanger can be used to optimize or reduce power consumption and/or for further temperature control of the working fluid. For example, on colder days it is possible to turn off the fan(s) as the working fluid temperature can be suitably low enough to achieve the desired turbine exhaust gas temperature at the face of the catalyst. Additionally, in some embodiments one or more heat exchangers can be bypassed, in full or in part, and any corresponding fan can be cycled down. Selectively bypassing one or more ambient air heat exchangers allows for further temperature control of the working fluid prior to entering the heat exchanger 108 located in the hot turbine exhaust gas stream. Bypassing one or more ambient air heat exchangers also allows for a reduction in power consumption by the pump 112 due to a lower total pressure drop for the closed working fluid loop flow path.
For applications using CO2 (e.g., system 100 shown in
Referring now generally to
Referring now specifically to
The system 200 further differs in that the mass inventory management system 218 includes only a single tank 224. The tank 224 is monitored by a level transmitter (LT) and the amount of thermal oil in the cooling loop is controlled to control the system 200 overall as described with reference to
Referring now to
Referring now to
The third heat exchanger 434 is positioned downstream of the pump 412 and is adapted and configured to remove heat from the working fluid. The third heat exchanger 434 is either air cooled or water cooled. The third heat exchanger 434 can include a fan to pass ambient air over/through the third heat exchanger 434 such that heat is moved from the working fluid to the ambient atmosphere. As explained with regard to
The system 400 also includes a bypass valve 436, which can be manual or actuated, adapted and configured to controllably and selectively permit the working fluid to bypass the third heat exchanger 434. The bypass 436 is controlled based on one or more of the inputs described directly above with respect to the control of the fan of the third heat exchanger 434 and/or other factors as generally described for earlier embodiments. The third heat exchanger 434 can be bypassed or partially bypassed to increase the efficiency of the system 434 through decreased power consumption of the associated fan and/or through a lower total pressure drop in the cooling loop. The third heat exchanger 434 is only bypassed when suitable turbine exhaust gas temperature can be maintained without use of the third heat exchanger 434.
Referring now to
Referring now to
Referring now to
The first heat exchanger 708 and the fourth heat exchanger 738 are arranged in parallel loops such that the working fluid is split, with separate portions of the working fluid passing through the first heat exchanger 708 and the fourth heat exchanger 738. The separate portions of the working fluid converge to form a single flow after exiting the first heat exchanger 708 and the fourth heat exchanger 738. The combined output is received by the second heat exchanger 710. The fourth heat exchanger 738 can be adapted and configured to take off from the working fluid prior to the working fluid reaching the first heat exchanger 708 such that the fourth heat exchanger 738 is fed with priority in order to maintain, with priority, a turbine exhaust gas temperature range within operating parameters of the second catalytic exhaust gas treatment device 706. In other words, the flow of the working fluid can branch upstream of the first heat exchanger 708 and the fourth heat exchanger 738 with a portion of the working fluid being fed to the first heat exchanger 708 and a separate portion of the working fluid being fed to the fourth heat exchanger 738. This allows for separate streams of cooled working fluid to separately supply the two heat exchangers (e.g., in a parallel configuration rather than in a serial configuration where a single stream of working fluid is sequentially heated). The length and configuration of the diverging piping can be adapted and configured to feed the fourth heat exchanger 738 with priority. Alternatively, the exchangers (i.e., 708 and 738) can be in series with the same flow of coolant (e.g., CO2) passing through each exchanger with the flow direction of said fluid being either in parallel to the hot turbine exhaust gas stream or counter current with the turbine exhaust gas stream. In other words, one of either of the two heat exchangers can be fed with priority, the heat exchangers can be fed serially, or the heat exchangers can be fed in parallel.
Advantageously, the use of two heat exchangers independently cooling the turbine exhaust gas prior to different catalytic treatment devices allows for independent control of turbine exhaust gas temperature prior to independent treatment devices. This allows for the turbine exhaust gas temperature to be maintained within a first range for treatment by the first catalytic treatment device 704 (e.g., to treat carbon monoxide). The turbine exhaust gas temperature is independently maintained within a second lower temperature range for treatment by the second catalytic treatment device 706 (e.g., an SCR to treat nitrous oxides).
The fourth heat exchanger 738 and the first heat exchanger 708 can be independently controlled based on the working fluid temperature monitored at the outlet of both the first 708 and fourth heat exchanger 738. Flow of the working fluid to the first 708 and fourth heat exchangers 738 can be controlled via a temperature control valve located in the pipeline dedicated to the coil being controlled (e.g., control valve 740). Two temperature control valves can be used (one per heat exchanger) or a single control valve 740 can be used to control the flowrate of working fluid to the fourth heat exchanger 738 with the remainder of the working fluid being provided to the first heat exchanger 708 positioned downstream of the fourth heat exchanger 738.
The system 700 includes a mass inventory management system 718 adapted and configured to controllably receive working fluid downstream of the fourth heat exchanger 738 (e.g., using a controllable valve) at a takeoff point 742. Otherwise, the mass inventory system 718 operates as previously described.
Referring now to
Generally, while the use of a fourth heat exchanger is shown only with respect to
Referring generally to
The independent cooling loop 950 comprises at least a second heat exchanger 910 and a pump 912. Similarly, the independent cooling loop 950′ comprises at least a second heat exchanger 910′ and a pump 912′. Each independent cooling loop 950, 950′ likewise includes a heat exchanger (first and fourth heat exchangers 908, 938) positioned within the turbine exhaust gas discharge structure 902. Each independent cooling loop 950, 950′ can include other equipment of the type described herein with respect to any of the embodiments disclosed. For example, each independent cooling loop 950, 950′ can include an expansion nozzle 914, 914′, a bypass nozzle 916, 916′, a mass inventory system 918, 918′, a pump 922, 922′ adapted to take off and supply the mass inventory system, etc. Each independent cooling loop 950, 950′ can also include a third heat exchanger of the type described with respect to
It should also be understood that the system 900 including independent cooling loops 950, 950′ can utilize any of the working fluids described herein (e.g., carbon dioxide, water, thermal fluid/oil, etc.). The independent cooling loops 950, 950′ are independent, with independent mass inventory systems 918, 918′, such that the independent cooling loops 950, 950′ can use different working fluids. For example, the independent cooling loop 950 can use water as the working fluid, while the independent cooling loop 950′ can use carbon dioxide as the working fluid. Any combination of working fluids can be used.
Referring now to
Referring now to
Referring generally to
It should also be understood that the systems described herein include a plurality of catalytic turbine exhaust gas treatment devices. But in alternative embodiments, one or more of the catalytic turbine exhaust gas treatment devices can be substituted with other turbine exhaust gas treatment devices including but not limited to non-catalyst treatment system(s). Non-catalyst treatment systems can comprise a membrane adapted and configured to remove one or more compounds from the turbine exhaust, a urea injection system, or other system. For example, the membrane can be a synthetic membrane made from polymers, cellulose acetate, or ceramic materials. Any suitable material can be used for the membrane, the membrane being adapted and configured to remove carbon monoxide, nitrous oxides, sulfur dioxide, hexane, carbon dioxide, butane, methane, benzene, or other compounds.
Still referring generally to
As in the embodiment of
Working fluid passes through the first heat exchanger 1008 and is heated by the turbine exhaust gas G passing through the first heat exchanger. The heated working fluid then leaves the first heat exchanger 1008 with additional heat and is directed through a first conduit 1010 or other fluid conveying device. The first conduit 1010 extends from the first heat exchanger 1008 to one or more heat exchangers of a district heating (DH) system 1012. The district heating system 1012 comprises a distribution network communicating the flow of working fluid in the cooling loop with heat exchangers of the district heating system and communicating the flow of working fluid from the heat exchangers of the district heating system with the cooling loop. The district heating system 1012 is outside the exhaust gas discharge structure 1002.
The district heating system 1012 or heat network or teleheating system is adapted and configured to distribute heat generated in the centralized location of the gas turbine through a distribution network, for example a network of insulated pipes. The distribution network is adapted and configured to communicate the generated heat to users of the heat, for example residential and/or commercial users to satisfy their heating requirements. The working fluid leaving the first heat exchanger 1008 enters the heat exchanger(s) of the district heating system 1012 positioned downstream of the first heat exchanger 1008. The district heating system 1012 is adapted and configured to remove heat from the working fluid gained at the first heat exchanger 1008.
The working fluid then leaves the district heating system 1012 having been cooled by the district heating and is directed through a second conduit 1014 to a pump 1016. The pump 1016 is positioned downstream from the district heating 1012 and is adapted and configured to receive the cooled working fluid from the second conduit 1014 and drive the working fluid through the cooling loop. The pump 1016 can be driven by an electric motor or other type of drive mechanism.
The pump 1016 drives the working fluid through a third conduit 1018 of the cooling loop. The third conduit 1018 extends from the pump 1016 to the heat transfer coils of a second heat exchanger 1020 and is adapted and configured to direct the working fluid from the pump 1016 to a heat transfer coil of the second heat exchanger 1020. The second heat exchanger 1020 is positioned in the gas turbine exhaust flow path that has passed through the SCR 1006 and is exiting the SCR. Working fluid passing through the second heat exchanger 1020 again gains heat from and cools the flow of gas turbine exhaust exiting the SCR 1006. The second heat exchanger 1020 is adapted and configured to further cool the gas turbine exhaust gas exiting the SCR 1006 and passing through the second heat exchanger 1020 prior to the exhaust gas entering into a further downstream component of the exhaust gas discharge structure 1002. For example, the further downstream component of the exhaust gas discharge structure 1002 could be a second, additional catalytic converter such as a second SCR 1022.
A fourth conduit 1024 extends from the second heat exchanger 1020 to the first heat exchanger 1008 and is adapted and configured to direct the working fluid from the second heat exchanger 1020 to the first heat exchanger 1008. The second heat exchanger 1020 is positioned downstream of the pump 1016 and upstream of the first heat exchanger 1008 and recovers some final residual heat from the turbine exhaust gas exiting the SCR 1006 before then directing the working fluid through the cooling loop back to the first heat exchanger 1008.
As represented in
As in the system 1000 of
As in the system 1000 of
The working fluid that has been cooled by the primary heat exchanger 1102 transferring heat to the district heating loop is directed through the second conduit 1014 to the pump 1016. The pump 1016 receives the cooled working fluid from the primary heat exchanger 1102 and drives the working fluid through the third conduit 1018 of the cooling loop.
The third conduit 1018 extends from the pump 1016 to the heat transfer coils of the second heat exchanger 1020. As described earlier, the second heat exchanger 1020 is positioned in the path of gas turbine exhaust flow that has passed through and is exiting the SCR 1006. The working fluid passing through the second heat exchanger 1020 again gains heat from and cools the flow of gas turbine exhaust exiting the SCR 1006. The exhaust gas then passes through the further downstream component of the exhaust gas discharge structure 1002, for example the second SCR 1022.
In the same manner as previously described, the fourth conduit 1024 extends from the second heat exchanger 1020 to the first heat exchanger 1008 and directs the working fluid from the second heat exchanger back to the first heat exchanger.
The system 1100 of
In
Further advantages of the systems described herein include the following. The systems described herein can eliminate the need for, or reduce the complexity of, flow conditioning devices in the turbine exhaust gas stream, which are often required to ensure good hot turbine exhaust gas flow distribution at the face of the catalyst systems. These flow distribution devices are subject to high turbine exhaust gas temperature and very turbulent turbine exhaust gas flows resulting in a high cost to supply/install due to the requirements of operation. The systems described herein can eliminate or reduce these flow distribution devices as a result of the turbine exhaust gas being more controllably cooled and/or as a result of the elimination of any dilution air. In other words, flow distribution devices are not needed to adequately mix dilution air with the turbine exhaust gas as the described systems do not use dilution air. Further or alternatively, the heat exchangers positioned within the turbine exhaust gas discharge structure can adequately distribute flow of the turbine exhaust gas.
It should also be understood that while the systems described transfer heat from the turbine exhaust gas, to be used for heating applications, the energy may also be used for power generation. The heated working fluid can heat other process fluids through a heat exchanger. The heated working fluid can drive a mechanical device (e.g., a pump). Further, the heated working fluid can be expanded to drive a turbine which in turn drives an electrical generator.
Further, while the invention is not limited to the use of CO2, CO2 specifically, results in lower pumping power required compared to other gases/vapors and provides an inert fluid such that the systems described do not need to consider potential hazardous operation that might be required with other fluids The use of CO2 also eliminates the need for the facility to have to remove the fluid from the system during periods when not in operation while freezing conditions exist or from having to provide costly (capital and operating) heat trace equipment to prevent freezing (e.g. systems using water for medium) or sludging (oil systems). A stack damper typically required to reduce air flow through the gas path during freezing conditions is also not used by the described systems.
As various changes could be made in the above constructions and methods without departing from the broad scope of the disclosure, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
This application is a Continuation-In-Part of U.S. patent application Ser. No. 17/487,887, filed Sep. 28, 2021, claims the benefit of U.S. Provisional Patent Application Ser. No. 63/084,290, filed Sep. 28, 2020, both of which are hereby incorporated herein by reference in their entireties.
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