巴西专利BR112012024146B1 working fluid circuit for lost heat recovery and method of recovering lost heat in a working fluid c

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专利摘要:
HEAT ENGINES WITH CASCADE CYCLES The cascade thermodynamic energy conversion cycles use multiple energy turbines from a working fluid circuit for the conversion of thermal waste energy, with each of the turbine inlet temperatures optimized for operation in a temperature spectrum to use a greater amount of thermal energy from each cycle. Various attached arrangements of stoves are also disclosed, and fluid mass management systems work integrated with cascade cycles.
公开号:BR112012024146B1
申请号:R112012024146-0
申请日:2011-03-22
公开日:2020-12-22
发明作者:Timothy James Held
申请人:Echogen Power Systems, Inc.；
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REFERENCE TO RELATED PATENT APPLICATIONS
This patent application claims priority for provisional US patent application no. serial number 61 / 316,507 filed on March 23, 2010 and provisional US patent application no. serial number 61 / 417,775 filed on November 29, 2010. Priority patent applications are hereby incorporated by reference in their entirety into the present patent application. FUNDAMENTALS
Heat is often created as a by-product of industrial processes where streams of liquids, solids or gases that contain heat must be discharged into the environment or otherwise removed from the process in an effort to maintain operating temperatures for industrial process equipment. Sometimes the industrial process can use heat exchangers to capture heat and recycle it back into the process using other process streams. Other times it is not feasible to capture and recycle this heat, since it is either very low in temperature or there is no readily available means to use it directly as heat. This type of heat is generally called "lost" heat and is typically discharged directly into the environment by, for example, a chimney, or indirectly through a cooling medium, such as water. In other configurations, such heat is readily available from renewable sources of thermal energy, such as heat from the sun (which can be concentrated or otherwise manipulated) or geothermal sources. These and other sources of thermal energy are intended to be covered by the definition of "lost heat", as that term is used here.
Lost heat can be used by turbine-generator systems that use thermodynamic methods, such as the Rankine cycle, to convert heat into work. Typically, this method is based on steam, where the lost heat is used to produce steam in a boiler to drive a turbine. However, at least one of the main shortcomings of a steam-based Rankine cycle is its high temperature requirement, which is not always practical, since it usually requires heat vapor lost at relatively high temperature (316oC or more) or very high total heat content. Likewise, the complexity of boiling water at multiple pressures / temperatures to capture heat at multiple temperature levels as the heat source stream is cooled is costly in both equipment cost and operating labor. In addition, the steam-based Rankine cycle is not a realistic option for low flow rate and / or low temperature currents.
The organic Rankine cycle (ORC) addresses the shortcomings of steam-based Rankine cycles by replacing water with a fluid with a lower boiling point, such as a light hydrocarbon such as propane or butane, or an HCFC fluid (for example, R245fa). However, boiling heat transfer restrictions remain, and new issues such as thermal instability, toxicity or flammability of the fluid are added.
To address these deficiencies, supercritical CO2 energy cycles have been used. The supercritical state of CO2 provides improved thermal coupling with multiple heat sources. For example, when using a supercritical fluid, the gradual temperature transition of a process heat exchanger can be more easily adapted. However, supercritical single-cycle CO2 energy cycles operate at a limited pressure ratio, thereby limiting the amount of temperature reduction, that is, energy extraction, through the power conversion device (typically a turbine or expander positive displacement). The pressure ratio is limited mainly due to the high vapor pressure of the fluid at typically available condensing temperatures (eg ambient). As a result, the maximum output power that can be achieved from a single expansion stage is limited, and the expanded fluid retains a significant amount of potentially usable energy. Although a portion of this residual energy can be recovered within the cycle by using a heat exchanger as a stove and therefore preheating the fluid between the pump and the lost heat exchanger, this approach limits the amount of heat that can be extracted of the heat source lost in a single cycle.
Consequently, there is a need in the art for a system that can efficiently and effectively produce power from not only lost heat, but also from a wide range of thermal sources. SUMMARY
The present invention belongs to the general field of thermodynamics and energy conversion, and is more specifically applicable to the conversion of thermal energy into work. The present invention improves the efficiency of a supercritical cycle of CO2 energy by "cascading" the residual energy back to a higher pressure fluid source, and expanding this fluid through an additional power conversion device. In addition, the unique characteristics of the CO2 cycle require active management of the relationship between suction pressure and temperature of the main pump to provide optimum cycle efficiency. The present invention includes equipment and control strategies that allow superior performance to be achieved with the cascade CO2 cycle described here.
Modalities of the invention can provide a working fluid circuit for recovering lost heat. The working fluid circuit can include a pump that works to route a working fluid to a lost heat exchanger fluidly coupled to the pump, a first expansion device fluidly coupled to the lost heat exchanger and configured to receive the working fluid from the lost heat exchanger, and a first stove fluidly coupled to the first expansion device and configured to receive the working fluid from the first expansion device and transfer heat from the working fluid to a downstream portion of the working fluid. The working fluid circuit may further include a second expansion device fluidly coupled to the pump downstream of the pump and configured to receive the downstream portion of the working fluid, a second recuperator fluidly coupled to the second expansion device and configured to receive the downstream portion of the working fluid from the second expansion device, and a mass management system that has a first fluidly coupled associated system upstream of the first expansion device and a second associated coupled system fluid upstream of the pump, the mass management system having a mass control tank configured to selectively receive working fluid from the working fluid circuit via the first associated system and to selectively introduce working fluid into the fluid circuit through the second associated system.
Modalities of the invention can also provide another working fluid circuit for recovering lost heat. The other working fluid circuit may include a pump configured to route a working fluid to a lost heat exchanger fluidly coupled to the pump, the working fluid being separated into a first portion and a separate portion, where the first portion passes through the lost heat exchanger. The working fluid circuit may also include a first stove configured to receive the separate portion of the working fluid and increase its temperature, a first expansion device fluidly coupled to the lost fluid changer and configured to receive the first portion of the working fluid. working fluid from the lost heat exchanger, a second recuperator fluidly coupled to the first expansion device and configured to receive the first portion of the working fluid from the first expansion device, the second recuperator also configured to receive the separate portion of the working fluid after the first stove and further increasing the temperature of the separate portion, and a second expansion device configured to receive the separate portion of the working fluid from the second stove. The working fluid circuit may further include a mass management system that has a first associated system fluidly coupled upstream of the first expansion device and a second associated system fluidly coupled upstream of the pump, the management system of mass having a mass control tank configured to selectively receive working fluid from the working fluid circuit via the first associated system and to selectively introduce working fluid into the working fluid circuit via the second associated system.
Modalities of the invention can also provide a method of recovering lost heat in a working fluid circuit. The method may include pumping a first portion of a working fluid with a pump to a lost heat exchanger fluidly coupled to the pump, pumping a separate portion of the working fluid with the pump through a first stove, and transferring of thermal energy from the first stove to the separate portion of the working fluid. The method may also include expanding the first portion of the working fluid in a first expansion device fluidly coupled to the lost heat exchanger, and transferring thermal energy from the first portion of the working fluid to the separate portion of the working fluid in a second stove fluidly coupled to the first expansion device, the second stove being configured to receive the separate portion of the working fluid after the first stove. The method may further include expanding the separate portion of the working fluid into a second expansion device configured to receive the separate portion from the second stove, recombining the first portion and the separate portion of the working fluid to pass through the first stove, and control of an amount of working fluid mass in the working fluid circuit with a mass management system that has a mass control tank fluidly coupled to a first associated system and a second associated system, the first associated system being fluidly coupled upstream of the first expansion device and the second associated system being fluidly coupled upstream of the pump. BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is best understood from the detailed description below when dealing with the attached figures. It is emphasized that, according to industry standard practice, several devices are not designed to scale. In fact, the dimensions of the various devices can be arbitrarily increased or reduced for clarity of discussion.
Figure 1 is a schematic drawing of a simple thermodynamic cycle for recovering lost heat.
Figure 2 is a schematic drawing of a modality of a thermodynamic cycle in a cascade of lost heat recovery, according to one or more specified modalities.
Figure 3 is a schematic drawing of another thermodynamic cascade cycle of lost heat recovery, according to one or more specified modalities.
Figure 4 is a schematic drawing of another thermodynamic cascade cycle of lost heat recovery, according to one or more specified modalities.
Figure 5 is a schematic drawing of another thermodynamic cascade of lost heat recovery, according to one or more specified modalities.
Figure 6 is a schematic drawing of a mass management system (MMS) that can be used in connection with the specified lost heat recovery cascade thermodynamic cycles, according to one or more specified modalities.
Figure 7 is a schematic drawing of another mass management system (MMS) that can be used in connection with the specified lost heat recovery cascade thermodynamic cycles, according to one or more specified modalities.
Figures 8 and 9 schematically illustrate different arrangements of the system for cooling input of a separate fluid stream (for example, air) using the working fluid that can be used in the exemplary thermal engine cycles specified here.
Figure 10 illustrates an exemplary lost heat recovery system that includes a mass management system, according to one or more specified modalities. DETAILED DESCRIPTION
It should be understood that the specification below describes several exemplary modalities for implementing different devices, structures, or functions of the invention. Exemplary modalities of components, arrangements, and configurations are described below to simplify the present description; however, these exemplary embodiments are provided as examples only and are not intended to limit the scope of the invention. In addition, the present specification may repeat numerals and / or letters in the various exemplary modalities and throughout the figures provided in this document. This repetition is intended for simplicity and clarity and does not in itself impose a relationship between the various exemplary modalities and / or configurations discussed in the various figures. In addition, the formation of a first device on or in a second device in the description that follows may include modalities in which the first and second devices are formed in direct contact, and can also include modalities in which additional devices can be formed which they interpose between the first and second devices, so that the first and second devices may not be in direct contact. Finally, the exemplary embodiments presented below can be combined in any combination of ways, that is, any element of an exemplary embodiment can be used in any other exemplary embodiment, without departing from the scope of the invention.
In addition, some terms are used throughout the description and claims below to refer to specific components. As one skilled in the art will understand, different entities may refer to the same component by different names and, therefore, the naming convention for the elements described here is not intended to limit the scope of the invention, unless otherwise specifically defined in this document. In addition, the naming convention used here is not intended to distinguish between components that differ in name, but not in function. In addition, in the following discussion and in the claims, the terms "which include" and "which comprise" are used in an unlimited manner and, therefore, should be interpreted to mean "which include, but are not limited to". All numerical values in this specification can be exact or approximate values unless otherwise specifically mentioned. Consequently, various embodiments of the invention may depart from the numbers, values, and ranges specified here without departing from the intended scope. In addition, as used in the claims or specification, the term "or" is intended to encompass both exclusive and inclusive cases, that is, "A or B" is intended to be synonymous with "at least one of A and B ", unless otherwise expressly specified here.
The specification is made with reference to several modalities as schematically represented by the attached figures. It should be noted that representative operating temperatures, pressures and flow rates are given as examples only and do not limit the scope of the invention in any way.
Figure 1 illustrates a "simple" thermodynamic cycle recovered baseline where a working fluid, such as supercritical CO2, is pumped through a working fluid circuit in thermal communication with a WHX lost heat exchanger. A PT power turbine is fluidly coupled to the WHX lost heat exchanger downstream. The working fluid is subsequently expanded in the PT power turbine for the purpose of generating power or work. It will be understood that the PT power turbine can include any type of expansion device without departing from the scope of the invention. The working fluid is cooled in an RC1 stove and returned to a low temperature state in a condenser C. The working fluid is then routed to a pump P to start the fluid circuit again. Depending on the temperature achievable at the suction inlet of pump P, and based on the available cooling supply temperature and the performance of condenser C, the suction pressure on pump P can be either subcritical or supercritical. As will be described in more detail below, a "mass management system" can also be included in each of the specified working fluid circuits to add or remove working fluid (ie, mass) from the system and thus make the system more efficient by increasing the total pressure ratio of the system to the maximum possible while maintaining the pump suction pressure at an acceptable level.
Figure 2 schematically illustrates an exemplary "cascade" cycle in which the residual energy following the first stage PT1 power turbine (ie state 51) is used to preheat additional working fluid at high pressure , or a downstream portion of the working fluid, to a temperature within approximately 5 to 10oC of the fluid in state 51. The downstream portion of the working fluid can subsequently be expanded through a second PT2 power turbine (or second stage) adapted to trigger a work production device. In one embodiment, the work production device can be an electric generator coupled by a gearbox or directly driving a high speed alternator. It is also possible to connect the PT2 output to the work production device, or generator, being driven by PT1. In other embodiments, the first and second stage PT1 and PT2 power turbines can be integrated into a single piece of turbomachinery, such as a multi-stage turbine that uses separate blades / disks on a common axis, or as separate stages of a radial turbine that drives a main gear that uses separate pinions for each radial turbine.
The remainder of the cycle in Figure 2 can be substantially similar to the recovered form of the cycle shown in Figure 1, with the exception that the discharges from both RC1 and RC2 stoves can be combined to enter capacitor C. That is, the discharge from the second PT2 power turbine, it can pass through a second RC2 stove in order to reduce the temperature of the separate working fluid portion before being recombined with the remaining working fluid portion that precedes condenser C. Pump P provides fluid pressure to flow the working fluid through the cycle's working fluid circuit.
Each of the RC1, RC2 and C capacitors specified in Figure 2, and those specified below in Figures 3-5, may, in at least one embodiment, include or use one or more printed circuit heat exchanger panels. Such heat exchangers and / or panels are known in the art, and are described in US Patent Nos. 6,921,518; 7,022,294; and 7,033,553, the contents of which are hereby incorporated by reference to the extent consistent with the present invention.
When using multiple PT1, PT2 turbines at similar pressure ratios, a larger fraction of the heat source available from the WHX lost heat exchanger is used and residual heat from the PT1, PT2 turbines is recovered. Consequently, additional heat is extracted from the heat source lost through multiple temperature expansions. As can be understood, the use of multiple PT1, PT2 turbines at similar pressure ratios uses a wider spectrum of the available heat source and the residual heat from each PT1, PT2 turbine can be recovered and combined with any residual waste heat.
In one or more modes, the arrangement of the RC1, RC2 stoves in any of the modes specified here can be optimized in conjunction with the WHX lost heat exchanger to maximize the power output of the multiple temperature expansion stages. Likewise, both sides of each RC1, RC2 stove can be balanced, for example, by adjusting the heat capacity rates and selective fusion of the different flows in the working fluid circuits through the lost heat exchangers and stoves; C = m ^ cp, where C is the heat capacity rate, m is the mass flow rate of the working fluid, and cp is the pressure specific heat constant. As understood by those skilled in the art, the balance on each side of the RC1, RC2 stoves provides a better overall cycle performance by improving the efficiency of the RC1, RC2 stoves for a given available heat exchanger surface area.
The WHX lost heat exchanger (s) used in the various modalities specified here can be any type of lost heat exchanger device or operating means for transferring thermal energy from a lost heat source or other heat source for the working fluid. In at least one embodiment, the WHX lost heat exchanger may include a printed circuit heat exchanger.
Figure 3 is similar to Figure 2, but with one main exception. In Figure 3, the second PT2 power turbine can be coupled to pump P either directly or through a gearbox. The motor that drives the P pump can also be used to supply power during system startup, and can provide a fraction of the drive load for the P pump under certain conditions. In other cases, however, it is possible to use the motor as a generator, especially if the second PT2 power turbine is capable of producing more power than the pump P needs for system operation.
Figure 4 is a variation of the system in Figure 3, whereby the motor-driven pump P is replaced by or connected in operating mode to a high-speed TP direct-drive turbine pump. As illustrated, a small SP "start pump" or other pumping device can be used when starting the system, but as soon as the TP turbine pump generates enough power to "start up" in steady state operation, the SP start pump can be turned off. Additional control valves CV1 and CV2 can be included to facilitate the operation of the TP turbine pump under varying load conditions. Additional control valves CV1, CV2 can also be used to bring heat into the TP turbine before the PT main power turbine is started. For example, at the start of the system, the shut-off valve SOV1 can be closed and the first CV1 control valve opened so that the heated working fluid discharged from the lost heat exchanger WHX can be directed to the TP turbine pump in order to drive the P system pump until it reaches steady state operation. When operating in steady state, the CV1 control valve can be closed and the SOV1 shut-off valve simultaneously opened in order to route heated working fluid from the WHX lost heat exchanger to the PT power turbine.
Figure 5 illustrates schematically an exemplary modality of a double cascade cycle that can be implemented in a thermal motor cycle. Following pump P, the working fluid can be separated at point 502 in a first portion m1 and a separate portion m2. The first m1 portion can be routed to the WHX lost heat exchanger and subsequently expanded into the PT1 first stage power turbine. Residual energy in the exhaust working fluid m1 following the first stage power turbine PT1 (eg state 5) can be used to preheat the separate portion m2 on a second stove (Recup2) after the separate portion m2 has passed previously through a first stove (Recup1) to increase its temperature. In one embodiment, the second stove (Recup2) can be configured to preheat the separated portion m2 to a temperature within approximately 5 to 10oC of the exhaust working fluid m1 in state 5. The separated portion m2 in state 45 can be substantially expanded through a second stage PT2 power turbine and then recombined with the first portion m1 at point 504. The recombined working fluid m1 + m2 can then be routed to a mesh that includes a first stove (Recup1), a condenser ( for example, state 6), and a working fluid pump P (for example, state 1).
In all fluid circuit modalities specified here, and any equivalents thereof, an optional bypass loop may be included by which all or part of the working fluid can be routed through the bypass loop and not into one or more of the RC1, RC2 stoves. By providing this flexibility to the system, the operator or control system can monitor and control the operation according to the amount of heat available in one or more locations within the system, and thus maximize efficiency.
As briefly mentioned above, the working fluid circulated in each of the exemplary cycles described here can be carbon dioxide. Carbon dioxide is a neutral, greenhouse-friendly working fluid that offers benefits such as non-toxicity, non-flammability, easy availability, low price, and no need for recycling. It should be noted that the use of the term "carbon dioxide" is not intended to be limited to a carbon dioxide of any specific type, purity, or quality. For example, industrial grade carbon dioxide can be used in at least one modality.
In other embodiments, the working fluid circulated in each of the exemplary cycles described here can be a binary, ternary, or other combination working fluid. The combination of the working fluid can be selected for the unique attributes possessed by the combination of fluid within a heat recovery system, as described here. For example, such a fluid combination includes a mixture of liquid absorbent and carbon dioxide that allows the combined fluid to be pumped into a liquid state for high pressure with less energy input than is needed to compress CO2. In another embodiment, the working fluid may be a combination of carbon dioxide or supercritical carbon dioxide and one or more other miscible fluids or chemical compounds. In still other embodiments, the working fluid may be a combination of carbon dioxide and propane, or carbon dioxide and ammonia, without departing from the scope of the invention.
In the exemplary fluid cycles described here, the working fluid can be in a supercritical state in some portions of the system (the "high pressure side"), and in a subcritical state in other portions of the system (the "low pressure state" ). In other embodiments, the entire fluid cycle can function so that the working fluid is in a supercritical or subcritical state for the duration of the cycle.
The use of the term "working fluid" is not intended to limit the state or phase of the substance in which the working fluid is found. In other words, the working fluid can be in a fluid phase, a gas phase, a supercritical phase, a subcritical state, or any other phase or state at any one or more points within the fluid cycle. For example, in one embodiment the pressure at the pump inlet P exceeds the vapor pressure of the working fluid by a sufficient margin to prevent vaporization of the fluid in the local regions of low pressure and / or high speed. This is especially important with high-speed pumps such as the turbopumps used in the various modes specified here. Consequently, a traditional passive system, such as one that uses a compensation tank that only provides the incremental pressure of gravity in relation to the pressure of the fluid vapor, is insufficient for the modalities specified here.
The use of carbon dioxide in power cycles requires special attention to minimize the suction pressure of the P pump due to several factors. One factor is the critical temperature close to the carbon dioxide environment that requires the suction pressure of the pump P to be controlled both above and below the critical pressure (for example, subcritical and supercritical functioning). Another factor to consider is the relatively high compressibility of carbon dioxide which makes the volumetric and overall efficiency of the pump more sensitive to the suction pressure tolerance compared to other working fluids. At least one more factor is the low global pressure ratio of carbon dioxide that makes cycle efficiency more sensitive to suction pressure tolerance.
In order to minimize the suction pressure of the P pump, among other benefits, modalities of the specification may also include the incorporation and use of a mass management system ("MMS") in connection with or integrated with the described thermodynamic fluid cycles . The MMS can be configured to control the inlet pressure at the P pump by adding mass to the system and / or removing mass from the system, and this in turn makes the system more efficient by increasing the overall pressure ratio of the system to the as much as possible. In at least one modality, the MMS works with the system in a semi-passable way. For example, the MMS can use sensors to monitor pressures and temperatures within the high pressure side (from the P pump outlet to the PT1 turbine inlet) and the low pressure side (from the PT1 turbine outlet to the P pump inlet). ) of the system. The MMS can also include valves, tank heaters, pumps, or other equipment to facilitate the movement of the working fluid into and out of the system and a mass control tank for working fluid storage.
Referring to Figure 10, an exemplary embodiment of a lost heat recovery system is illustrated that includes an MMS 100 with a plurality of valves 14, 15, 16, 17, 18, 21, 22, and 23, a control tank mass 7, and a control system 108. The MMS 100 is connected in operating mode to the heat recovery system at the valves or end points 14, 15, 16, 17, 18, 21, 22, and 23. In In one embodiment, the MMS is adapted to remove denser and higher pressure working fluid (in relation to pressure, temperature, and density on the low pressure side of the system) from the thermodynamic cycle via valve 16. The MMS 100 can supply working fluid into the lost heat recovery system via valve 15. The MMS automatically pressurizes the mass control tank 7 by opening the valve 14 until the pressure inside the mass control tank 7 is sufficient to inject fluid through the v valve 15. By controlling the operation of valves 14, 15, 16, the MMS 100 adds or removes grease (ie working fluid) to / from the lost heat recovery system without the need for a pump, thereby reducing cost , complexity and system maintenance.
In the illustrated embodiment, the MMS 100 includes a mass control tank 7 that can be loaded with working fluid. Tank 7 can be in fluid communication with valves 14, 16 so that opening one or both of the valves 14, 16 will provide working fluid to the top of the mass control tank 7. The mass control tank 7 may also be in fluid communication with valve 15 so that opening of valve 15 will remove fluid from the bottom of the mass control tank 7 to be injected into the adjacent lost heat recovery system and preceding the pump 9. Inside the tank mass control 7 the working fluid can be in liquid phase, gas phase, or both, or in a supercritical state; if the working fluid is in both the liquid and gaseous phases, a phase division can separate the two phases whereby the denser working fluid is deposited on the bottom of the mass control tank 7. Consequently, the The work contained in the mass control tank 7 will tend to stratify with the higher density working fluid at the bottom of the tank 7 and the lower density working fluid at the top of the tank 7. In this way, valve 15 will be able to to supply the lost heat recovery system with the densest working fluid from inside the mass control tank 7.
A first set of sensors 102 can be positioned at the suction inlet of pump 9 and be configured to measure and record the temperature, pressure, and mass flow rate of the working fluid at that point in the system. A second set of sensors 104 can be positioned at or adjacent to the pump outlet 9 and configured to measure and record the temperature, pressure, and mass flow rate of the working fluid at that point in the system. A third set of sensors 106 can communicate with the mass control tank 7 and be configured to measure and record the temperature and pressure of the working fluid inside the tank 7. Each set of sensors 102, 104, 106 can be in communication (wired and / or wireless) with a control system 108 which is also in communication with each of the valves 14, 15, 16 by means of actuators, servos, or other devices capable of manipulating the general arrangement (ie , open / closed) of each valve 14, 15, 16. Consequently, control system 108 can receive measurement communications from each set of sensors 102, 104, 106 and adjust each valve 14, 15, 16 for the purpose of maximize the operation of the lost heat recovery system. In addition, the first set of sensors 102 can correspond to location 1 in Figures 1-5, and the second set of sensors 104 can correspond to location 2 in Figures 1-5.
Exemplary MMS 100 may also include points 18 and 19 used to remove and / or introduce working fluid from / into the lost heat recovery system. Point 17 can be used to flow the working fluid from the MMS 100, and other illustrated equipment is used in a variety of operating conditions such as starting, loading, and shutting down the lost heat recovery system. A more detailed description of the other illustrated equipment can be found in copending US patent application no. serial 12 / 631.379 entitled "Thermal Engine and Heat Systems and Methods in Electricity", deposited on December 4, 2009, the content of which is incorporated by reference to the extent consistent with the present invention.
Following is the operation of the example MMS 100.
When the working fluid, such as CO2, in the mass storage tank 7 is at fluid vapor pressure for a given ambient temperature, and the pressure on the low pressure side in the lost heat recovery system is above the pressure of steam, the pressure in the mass control tank 7 should be increased to allow the addition of mass to the lost heat recovery system. This can be controlled by opening valve 14 which in this way allows working fluid at higher pressure, higher temperature, lower density, such as supercritical CO2, to flow into the mass control tank 7. Valve 15 can be opened to allow higher density liquid working fluid at the bottom of the mass control tank 7 to flow into the lost heat recovery system and thereby increase the suction pressure of the pump 9.
The description of the preceding MMS 100 can also be applicable as a supplement to the various cascade thermodynamic cycles specified here, and shown generally in Figures 1-5. For example, with reference now to Figures 6 and 7, Figure 7 schematically illustrates a mass management system 700 substantially similar to the MMS 100 shown in Figure 10, and Figure 6 schematically illustrates another example mass management system 600. Points A, B, and C of the associated system as shown in Figures 6, 7 and 10 (only points A and C shown in Figure 6) correspond to points A, B, and C of the associated system shown in Figures 1-5. Consequently, each of the MMS 600 and 700 can be fluidly coupled to the cascade cycle of Figures 1-5 at points A, B, and C of the corresponding associated system (if any). The MMS 600 stores a working fluid at low temperature (sub-environment) and therefore low pressure, and the MMS 700 stores a working fluid at or near room temperature. As discussed above, the working fluid can be CO2, but it can also be another working fluid without departing from the scope of the invention. Where a working fluid P pump is indicated for each of the cascade cycles described in Figures 1-5, working fluid is supplied when needed from a mass control tank T (Figures 6 and 7) for a pump inlet P. In operation, the MMS 700 works to selectively add working fluid to the main mesh of the cascade cycle by pressurizing the working mass control tank T and then opening a valve at the bottom of the control tank. mass T to flow into the rest of the cycle through the interface or C of the associated system. For example, the mass control tank T in Figure 7 can be pressurized by opening the valve at or adjacent to interface A, and liquid can be released from the mass control tank T by opening the valve at or adjacent to interface C. This process raises the inlet pressure of the system pump to pump P in Figures 1-5. To extract fluid from the main system mesh, and to lower the inlet pressure of the system pump, the valve at interface B (Figure 7) must be opened, thus allowing cold pressurized fluid to enter the mass control tank T.
In the modality of Figure 6, the MMS 600 uses only two associated systems or interface points A and C. The valve-controlled interface A is not used during the control phase, and is provided only to pressurize the main fluid mesh with steam. so that the temperature of the main fluid mesh remains above a minimum limit during filling. In operation, when the suction pressure of pump P shown in Figures 1-5 needs to be increased, working fluid is selectively added to the main mesh of the system by pumping it into that with a transfer pump 602 established at or near interface C . When the suction pressure of pump P needs to be decreased, liquid is selectively drawn from the system at interface C and expanded through one or more valves downwards to the relatively low storage pressure. Under many conditions, the expanded fluid will have two phases (that is, gaseous + liquid). To prevent the pressure in the mass control tank T from exceeding its normal operating limits, a small steam compression refrigeration cycle (VC steam compressor) is provided to lower the fluid temperature and sufficiently condense the steam to maintain the pressure of the mass control tank T in its design condition. The vapor compression refrigeration cycle can be integrated with the CO2 storage tank system, or it can be an isolated vapor compression cycle with an independent refrigeration mesh.
Although not required in all applications, the MMS 700 can also include a transfer pump 704, substantially similar to transfer pump 602 in Figure 6. Transfer pump 704 can be configured to remove working fluid from tank T and inject it. it in the working fluid circuit.
All of the various controls described or changes in the working fluid environment and conditions throughout the cascade cycle, including temperature, pressure, direction and flow rate, and the functioning of components such as pumps and turbines, can be monitored and / or controlled control system 108, as generally described above with reference to Figures 6, 7, and 10. In one embodiment, control system 108 may include one or more proportional-integral-derivative controllers (PID) as control loop feedback. In another embodiment, control system 108 can be any microprocessor-based system capable of storing a control program and executing the control program to receive sensor inputs and generate control signals according to a predetermined algorithm or table. For example, the controller can be a microprocessor-based computer that runs a software control program stored in a computer-readable medium. The software program can be configured to receive sensor inputs from different pressure, temperature, flow rate sensors, etc. positioned throughout the system and generate control signals from those, where the control signals are configured to optimize and / or selectively control the operation of the system.
Each MMS 600, 700 can be coupled in communication mode to such control system 108 so that the control of the various valves and other equipment is automated or semi-automated and reacts to system performance data obtained through the various sensors located throughout the system, and also react to the environment and environmental conditions. This means that the controller 108 can be in communication with each of the components of the MMS 600, 700 and be configured to control the functioning of the one to carry out the system function more efficiently. For example, control system 108 can be in communication (via wires, RF signal, etc.) with each of the valves, pumps, sensors, etc. in the system and configured to control the functioning of each component according to a control software, algorithm, or other predetermined control mechanism. This can prove to be advantageous for controlling temperature and pressure of the working fluid at the inlet of the pump P, to actively increase the suction pressure of the pump P by decreasing the compressibility of the working fluid. Doing so can prevent damage to the P pump as well as increase the total pressure ratio of the cascade cycle, thereby improving efficiency and output power.
In one or more embodiments, it can prove advantageous to keep the suction pressure of pump P above the boiling pressure of the working fluid at the inlet of the pump P. A method of controlling the working fluid pressure on the low pressure side of the working fluid circuit consists of controlling the temperature of the working fluid in the mass control tank T. This can be accomplished by maintaining the temperature of the mass control tank T at a higher level than the temperature at the pump inlet P To accomplish this, the MMS 600, 700 can include the use of a heater and / or a coil 702 inside the tank T (Figure 7). The heater / coil 702 can be configured to add or remove heat from the fluid / vapor inside the T tank. In one embodiment, the temperature of the mass control tank T can be controlled using direct electric heat. In other embodiments, however, the temperature of the mass control tank T can be controlled using other devices, such as a heat exchanger coil with pump discharge fluid (which is at a higher temperature than the inlet of the pump). pump), a heat exchanger coil with cooling water spent from the chiller / condenser (also at a higher temperature than the pump inlet), or combinations thereof, but not limited to them.
Referring now to Figures 8 and 9, refrigeration systems 800 and 900, respectively, can also be used in connection with any of the cycles described above for the purpose of providing refrigeration to other areas of an industrial process that include pre-cooling of the inlet air from a gas turbine or other atmospheric air engines, but not limited to these, in order to provide greater engine output power. Points B and D or C and D of the associated system in Figures 8 and 9 can correspond to points B, C, and D of the associated system in Figures 1-5. Consequently, each of the cooling systems 800, 900 can be fluidly coupled to the cascading cycles of Figures 1-5 at the corresponding points B, C, and / or D of the associated system (when applicable). In the cooling system 900 of Figure 9, a portion of the working fluid can be extracted from the C-working fluid circuit of the associated system. The pressure of that portion of fluid is reduced by means of an expansion device 902, which can be a valve, orifice, or fluid expander such as a positive displacement turbine or expander. This expansion process decreases the temperature of the working fluid. Heat is then added to the working fluid in an evaporator 904 heat exchanger, which reduces the temperature of a process fluid (for example, air, as shown in Figures 8 and 9). The fluid pressure is then increased by using an 802 compressor, where it is reintroduced into the D working fluid circuit of the associated system.
The 802 compressor shown in Figures 8 and 9 can be either engine driven or turbine driven from a dedicated turbine or an additional wheel added to a main system turbine. In other embodiments, compressor 802 may be integrated with the main working fluid circuit. In other embodiments, compressor 802 may take the form of a fluid ejector, with driving fluid supplied from point A of the associated system, and discharging to point D of the associated system, upstream of condenser C. In the cooling system 800 of Figure 8, compressor 802 may be in the form of a fluid ejector, with driving fluid supplied from point A of the associated system (not shown, but corresponding to point A in Figures 1-5), and discharging to the point D of the associated system. In another embodiment, the working fluid is extracted from point B of the associated system shown in Figures 1-5 and pre-cooled by a heat exchanger 804 before expansion in an expansion device 806, similar to the expansion device 902 described above . In one embodiment, the 804 heat exchanger may include a water, air, water-CO2, or air-CO2 heat exchanger. As will be understood, the addition of the heat exchanger 804 can provide additional cooling capacity over the cooling system 900 shown in Figure 9.
Each of the described cascade cycles can be implemented in a variety of physical modalities, which include fixed or integrated installations or as a self-contained device such as a portable lost heat engine, or "skid" where the working fluid circuit and related components such as turbines, recuperators, condensers, pumps, valves, working fluid supply and control systems and electrical and mechanical controls are consolidated as a single unit, but not limited to them, as further specified and described in the orders related patents.
The terms "upstream" and "downstream" as used herein are intended to more clearly describe various embodiments and configurations of the invention. For example, "upstream" generally means in the direction or against the direction of flow of the working fluid during normal operation, and "downstream" generally means with or in the direction of the flow of the working fluid during normal operation.
The aforementioned outlined features of several modalities so that those skilled in the art can better understand the present invention. Those skilled in the art should understand that they can easily use the present specification as a basis for designing or modifying other processes and structures to carry out the same purposes and / or achieve the same advantages as the modalities introduced here. Those skilled in the art should also note that such equivalent constructions do not differ from the spirit and scope of the present invention, and that they can make various changes, substitutions and changes without departing from the spirit and scope of the present invention.

权利要求:
Claims (12)
[0001]
1. Working fluid circuit for recovering lost heat, characterized by comprising: a pump (P) that works to route a working fluid within the working fluid circuit to a fluid-coupled lost heat exchanger (WHX) the bomb; a first expansion device (PT1) fluidly coupled to the lost heat exchanger and configured to receive the working fluid from the lost heat exchanger; a first stove (RC1) fluidly coupled to the first expansion device and configured to receive the working fluid from the first expansion device and transfer heat from the working fluid to a downstream portion of the working fluid; a second expansion device (PT2) fluidly coupled to the pump downstream of the pump and configured to receive the downstream portion of the working fluid; a second fireplace (RC2) fluidly coupled to the second expansion device and configured to receive the downstream portion of the working fluid from the second expansion device; a condenser (C) fluidly coupled to the first stove and the second stove, in which the discharges of working fluid from both the first stove and the second stove are combined before entering the condenser; and a mass management system (100) that has a first associated system (A) fluidly coupled upstream of the first expansion device and a second associated system (C) fluidly coupled upstream of the pump, the mass management having a mass control tank (7) configured to selectively receive the working fluid from the working fluid circuit via the first associated system and to selectively introduce the working fluid into the working fluid circuit through of the second associated system.
[0002]
2. Working fluid circuit, according to claim 1, characterized by the fact that the second expansion device (PT2) is configured to drive the pump (P).
[0003]
Working fluid circuit according to claim 2, characterized in that it also comprises a starting pump (SP) fluidly coupled to a side downstream of the condenser (C) and to a side downstream of the pump (P ).
[0004]
4. Working fluid circuit according to claim 1, characterized in that the working fluid comprises carbon dioxide.
[0005]
5. Working fluid circuit according to claim 4, characterized in that the working fluid is in a supercritical state through a portion of the working fluid circuit.
[0006]
6. Working fluid circuit, according to claim 1, characterized in that the first and second expansion devices (PT1, PT2) are power turbines.
[0007]
7. Work fluid circuit according to claim 1, characterized in that the mass management system (100) comprises a system controller (108) configured to detect at least one of a temperature and pressure in the control circuit. working fluid and, in response, generate control signals for at least one of a plurality of selectively driven valves (14, 15, 16) and / or pumps (9) in the working fluid circuit, the mass management being configured to maintain a pressure at a pump inlet between a low pressure level greater than a saturation pressure of the working fluid and a high pressure level greater than the low pressure level.
[0008]
8. Method of recovering heat lost in a working fluid circuit, characterized by comprising: pumping a working fluid into the working fluid circuit by a pump (P), the working fluid being separated into a first portion and a separate portion downstream of the pump, where the first portion of the working fluid within the working fluid circuit is pumped to a lost heat exchanger (WHX) fluidly coupled to the pump and the separate portion of the working fluid is pumped through a first stove (RC1); transferring thermal energy from the first stove to the separate portion of the working fluid; expanding the first portion of the working fluid in a first expansion device (PT1) fluidly coupled to the lost heat exchanger; transferring thermal energy from the first working fluid portion to the separate working fluid portion in a second stove (RC2) fluidly coupled to the first expansion device, the second stove being configured to receive the separate working fluid portion after the first stove; expanding the separate portion of the working fluid in a second expansion device (PT2) configured to receive the separate portion from the second stove; recombining the first portion and the separate portion of the working fluid to pass through the first stove and a condenser (C), the condenser being fluidly coupled to the first stove; and controlling a mass amount of working fluid in the working fluid circuit with a mass management system (100) that has a mass control tank (7) fluidly coupled to a first associated system (B) and to a second associated system (C), the first associated system being fluidly coupled upstream of the first expansion device and the second associated system being fluidly coupled upstream of the pump.
[0009]
Method according to claim 8, further comprising: receiving the working fluid from the working fluid circuit into the mass control tank (7) via the first associated system (B); and introducing the working fluid into the working fluid circuit via the second associated system (C).
[0010]
Method according to claim 9, characterized in that it further comprises controlling with a control system (108) a flow of working fluid to the working fluid circuit and to the pump (P), the control system being configured to maintain a pressure at a pump inlet between a low pressure level greater than a saturation pressure of the working fluid and a high pressure level greater than the low pressure level.
[0011]
11. Method according to claim 8, characterized in that the working fluid comprises 15 carbon dioxide.
[0012]
12. Method according to claim 11, characterized in that the working fluid is in a supercritical state through a portion of the working fluid circuit.

类似技术:

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同族专利:

公开号 | 公开日

CA2794150C|2018-03-20|

BR112012024146A2|2017-07-18|

WO2011119650A3|2012-01-12|

CA2794150A1|2011-09-29|

EP2550436A4|2016-04-20|

EP2550436A2|2013-01-30|

WO2011119650A2|2011-09-29|

EP2550436B1|2019-08-07|

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法律状态:
2019-01-08| B06F| Objections, documents and/or translations needed after an examination request according art. 34 industrial property law|

2019-10-29| B06U| Preliminary requirement: requests with searches performed by other patent offices: suspension of the patent application procedure|

2020-10-06| B09A| Decision: intention to grant|

2020-12-22| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 22/03/2011, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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US31650710P| true| 2010-03-23|2010-03-23|

US61/316,507|2010-03-23|

US41777510P| true| 2010-11-29|2010-11-29|

US61/417,775|2010-11-29|

PCT/US2011/029486|WO2011119650A2|2010-03-23|2011-03-22|Heat engines with cascade cycles|

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