JP4598071B2 - Efficient conversion of heat to useful energy - Google Patents

Description

  The present invention relates to a system, method and apparatus configured to perform a thermodynamic cycle by countercurrent heat exchange. In particular, the present invention relates to heating a multi-component stream with a heat source stream to generate electricity at one or more points in a thermodynamic cycle.

  Some conventional heat transfer systems can convert normally wasted heat into useful energy. An example of a conventional heat transfer system is to convert thermal energy from geothermal hot water or industrial waste heat sources into electricity using countercurrent heat exchange technology. For example, heat from a relatively hot liquid (eg, brine) from a geothermal hole can be used to heat a multi-component fluid (fluid stream) using one or more heat exchangers in a closed system. is there. A multi-component fluid is heated from a low energy, low temperature fluid state to a relatively high pressure gas (working stream). The high pressure gas or working stream can then pass through one or more turbines to rotate the one or more turbines to generate electricity.

  Thus, conventional heat transfer systems operate on the general counter-current heat exchange principle that heats a multi-component working fluid over various temperature ranges from relatively low temperatures to relatively high temperatures. The conventional fluid stream of such a system consists of various fluid components, each having a different boiling point. Thus, one component of the fluid stream may become a gas at some temperature and another fluid stream component may remain in a relatively hot liquid state at the same temperature. This may be useful for separating different components at different points in the closed system. Nevertheless, it is possible to raise all or nearly all of the fluid stream to a temperature at which all components of the fluid stream collectively constitute a “working stream”, ie, a high pressure gas.

  In order to heat the fluid between the fluid stream and the working stream, the heat transfer system mainly comprises a device configured to cool the working stream to a lower temperature or to heat the fluid stream to a higher temperature. For example, the fluid stream passes through one or more heat exchangers that couple the fluid stream to the heat source stream, and then passes through one or more turbines, such that the fluid stream is hot. In contrast, the working flow that has already passed through the turbine is commonly referred to as the consumption flow. Since the consumption stream is relatively hotter than the fluid stream in one or more stages of the system, it is cooled by transferring heat to the fluid stream in the heat exchanger.

  In order to obtain the temperature required for expansion in the turbine, the countercurrent heat exchange system heats the fluid stream from a lower temperature point to a higher temperature point. This creates several system variables that a conventional heat exchange system needs to consider. For example, if the optimum expansion temperature of a multi-component stream at ambient temperature is a very hot steam working stream, a very hot heat source is utilized, usually much hotter than the desired temperature of the working stream. Alternatively, if the heat source is only slightly higher than the final desired temperature of the multi-component flow, the fluid flow must be warmer than the ambient temperature so that the multi-component flow can be heated to the desired working flow temperature. It may become.

At least in part, due to differences in the starting temperature of the fluid flow, the temperature of the heat source, the desired temperature of the working flow, and the efficiency of the system, the heat source brine is typically discarded at a much higher temperature than the desired temperature. . For example, in some exemplary systems where a conventional heat transfer system passes brine through one or more heat exchangers, the brine is from an average temperature of about 315.6 ° C. (about 600 ° F.) to about 76 ° C. Cool to a throw-away temperature of .7-93.3 ° C. (about 170-200 ° F.). Although about 93.3 ° C. (200 ° F.) is still relatively hot for effective heat transfer to conventional fluid streams, conventional fluid streams are about 76.7-93.3 ° C. (
A similar temperature of about 170-200 ° F. is considered to be relatively cold or mild. Specifically, the coldest points of conventional fluid streams are usually too warm to be efficiently heated by the cold portion of the brine (ie, the cold tail). Thus, by discarding about 76.7-93.3 ° C. (about 170-200 ° F.) brine, conventional thermal systems tend to be more efficient.

  One possible solution is to temperatures well below about 87.8-93.3 ° C. (190-200 ° F.) so that the fluid stream can be efficiently heated using cold tail heat. Cooling the fluid stream. In principle, this solution involves the use of a distillation condensation subsystem (DCSS) in conjunction with the heat transfer system described above. Unfortunately, the use of DCSS can efficiently cool the consumption stream, but the temperature at which conventional DCSS cools the normal consumption stream is usually too low to be utilized efficiently. That is, the conventional DCSS cools the consumption flow to such a low temperature that it cannot be efficiently raised to a sufficiently high temperature as the working flow later.

  Thus, an advantage in the art is gained by systems and devices that allow for the efficient use of low temperature tails. In particular, an advantage in the art is gained by a heat transfer system that efficiently uses DCSS so that the fluid flow can still be raised to an efficient working flow temperature.

  The present invention solves one or more of the problems described above in the prior art by a system and apparatus configured to efficiently use more waste heat than is possible in conventional heat transfer systems. In particular, the present invention allows the use of a “cold tail” of the brine heat source of the heat transfer system by efficiently incorporating DCSS, at least in part, with additional heat exchange devices.

  For example, in one embodiment of the invention, the DCSS is coupled to a countercurrent heat exchange system. The DCSS is used, at least in part, to cool the spent working stream after it has passed through one or more turbines. However, since the fluid flow supplied by the DCSS is relatively cold, one or more heat exchange devices are added to raise the temperature of the fluid flow to a useful temperature range. Subsequently, in this temperature range, the fluid stream is coupled to a cold tail as low as about 65.6-93.3 ° C. (150-200 ° F.) via an additional heat exchanger, and still ultimately It is possible to reach an appropriate working flow temperature.

  Therefore, the heat transfer system according to the present invention can convert a large amount of heat from the heat source into useful energy, and can perform the conversion with significantly higher energy efficiency than the conventional heat transfer system. .

  The present invention relates to systems and devices configured to efficiently use more waste heat than is possible in conventional heat transfer systems. In particular, the present invention allows the use of a “cold tail” of the brine heat source of the heat transfer system by efficiently incorporating DCSS, at least in part, with additional heat exchange devices.

For example, FIG. 1 shows an embodiment of the present invention. In this embodiment, the heat transfer system 100 includes a power subsystem 101, which is coupled to a cooling system such as a distillation condensation subsystem (DCSS) 103. The power subsystem 101 is generally considered to heat the multi-component flow to a point where the fluid multi-component flow becomes at least partially a steam working flow. In contrast, DCSS 103 generally cools the expanded consumer stream to a cooled fluid stream, and heats the fluid stream appropriately for later use as a multi-component stream in power subsystem 101. Conceivable. FIG. 1 also shows the direction of the multi-component flow (both fluid and heat source flow) through the heat transfer system 100 as the fluid is condensed and heated by the system heat exchanger.

  Accordingly, in the following description, the flow of the heat source stream (eg, brine) as it flows through the heat transfer system 100 (and system 200) is then distinguished and independent from the heat source stream, and the power subsystem 101 and DCSS 103 are The flow of the consumption flow and the intermediate fluid flow to be communicated will be outlined. With respect to heat source streams, it is understood that there can be many types of heat source streams that can be implemented in accordance with the present invention. For example, a heat source stream suitable for use according to the present invention can include any suitable hot liquid or vapor such as a naturally produced or synthetically produced liquid, stream, oil, or mixtures thereof. is there. Thus, embodiments of the system described herein are particularly useful for converting heat from geothermal fluids such as “brine” into electrical power, and for converting waste heat from other synthetic fluids in a factory environment into electrical power. Can be useful.

  Refer to FIG. 1 again. The heat source stream enters the heat transfer system 100 at point 50 (about 121.1 ° C. to about 426.7 ° C. (250 ° F. to 800 ° F.)), and the heat source is divided into two streams 51, 151. These two streams are used to add heat to the working stream just before it reaches the turbine or other expansion component. For example, as stream 51 passes through heat exchanger 304, heat is transferred to the working stream at point 30 immediately before the working stream reaches into first turbine 501. As described herein, flow splitting can be done by any suitable means, such as a conventional splitting component that splits a multi-component flow into two separate streams.

  After the working stream passes through the first turbine, it is somewhat cooled to point 32. Thus, the flow 151 exchanges the working flow from point 32 to point 35 with the working flow adjacent to the second turbine 502 so that the working flow can be heated immediately before it enters the second turbine 502. Heat as it passes through the vessel 305. As used herein, a “heat exchanger” may be any conventional type of heat exchanger, such as a conventional shell and tube or flat plate heat exchanger, or variations or combinations thereof. Thus, a certain amount of heat is transferred by the heat exchanger 305 and the heat source stream at point 151 is cooled to the parameter at point 150.

  Streams 150 (original flow 151) and 152 (original flow 51) are then combined at point 153 before entering heat exchanger 303. The combined flow at point 153 is some amount cooler than the flow at point 50. Mixing, or combining, any working flow, intermediate flow, consumption flow or other fluid flow may be performed by any suitable mixing device for combining multiple flows to form a single flow.

  At point 153 through the heat exchanger, the combined heat source stream is still relatively hot so that a significant amount of heat can still be transferred to the working stream. Thus, passing the combined stream of points 153 through the heat exchanger 303 transfers heat from the heat source stream to the working stream and heats the working stream from points 66 to 67. The heat source stream has a somewhat cooler parameter at point 53 but is still relatively hot and passes through heat exchanger 301. This heats the working stream from points 161 to 61 and further cools the heat source stream from points 53 to 54.

In one embodiment, at point 54, these parameters of the heat source flow are approximately 76.7-93.3 ° C. (partially depending on the associated heat source and other operating conditions for the system 101).
Associated with a temperature range of about 170-200 ° F. In another embodiment, the heat source flow parameter at point 54 is associated with a temperature range of about 54.4-121.1 ° C. (about 130-250 ° F.). At point 54, the heat source stream is normally discarded because it is in the state of a conventional "cold tail" parameter. However, as will be more fully understood from the following description, the system 100 can efficiently use this low temperature tail so that the heat source stream goes from point 54 to point 55 through heat exchanger 405. . Since the heat exchanger 405 transfers heat from the low temperature tail, the heat exchanger 405 is referred to as a “residual heat exchanger”.

  Although the heat source flow path has been described, in the following description, the fluid flow of the system 100 is heated and cooled at various stages through the power subsystem 101 from point 60 to point 36, and then from the point 38 to point 29, DCSS. 3 shows the flow path and changes of the fluid flow of the system 100 as it passes through 103. For illustrative purposes, in one embodiment, the fluid stream comprises a water-ammonia mixture having a boiling point of about 91.1 ° C. (about 196 ° F.) and a dew point of about 170.0 ° C. (338 ° F.). Thus, as will be understood from the description herein, the fluid stream is at or near the boiling point at point 60, at or near the dew point at point 30, and at or near liquid form at points 18 and 102. It is in. Since the working fluid consists of a mixture of components rather than a single pure substance, there is a difference between boiling point, dew point and liquid form.

Referring to FIG. 1, at point 60, the heat transfer system 100 divides the working stream into two multicomponent streams at points 161 and 162. The operating stream at point 161 is heated to the parameter at point 61 by the heat source stream in heat exchanger 301, and the operating stream at point 162 is heated to the parameter at point 62 by consumption stream 36 in heat exchanger 302. After passing through the associated heat exchanger, the working streams at points 61 and 62 are then combined into a working stream having the parameters of point 66. Since part of the working stream at point 60 is heated by the heat source stream and another part of the working stream is heated by the consumption stream, the power subsystem 101 can efficiently use several heat sources. .

  The working stream at point 66 is heated to the parameters at point 67 by the heat source stream from point 153 via heat exchanger 303. In one embodiment, at point 67, the working stream begins to be converted to superheated steam. Thereafter, the working stream is heated by the heat source stream at point 51 so that the working stream is heated from point 67 to point 30 via heat exchanger 304. This optimizes the conventional working flow so that it can pass through the turbine 501 in the desired high energy state. In one embodiment, this desired high energy state is superheated steam.

  As the working flow passes through the turbine 501 from points 30 to 32, the working flow loses a certain amount of energy and is at least "partially consumed" in the form of pressure and temperature loss. The partial consumption stream at point 32 is heated through heat exchanger 305 to obtain the parameters at point 35. Thus, the system 100 finds additional increased energy gain by continuing to split the heat source stream at point 50 and repeatedly heating the subsequent partially consumed working stream, such as through a further number of heat exchangers and turbines. It is allowed to get. Accordingly, the use of one or two turbines in this disclosure is merely an illustration of one suitable embodiment.

After the working flow passes through one or more turbines 501, 502, the point 36 consumption flow passes through heat exchanger 302. This cools the consumption stream to a parameter at point 38 and simultaneously heats a portion of the working stream from points 162 to 62 (at least in some cases, the consumption working stream at point 36 may be hot. , Lower pressure than the high pressure working flow at points 162, 62). In conventional systems, the point 38 consumption stream is usually sent to point 60 for recovery reheating. However, in this system 100, the point 38 consumption stream is further cooled using DCSS 103.

  For example, the point 38 consumption stream passes through the heat exchanger 401 such that it is cooled from point 38 to point 16 and then to the 17 parameters. When the consumption stream is cooled from point 38 to point 17 by heat exchanger 401, heat is transferred to a relatively cool intermediate “lean stream” from point 102 to point 5. The lean flow reaches from the relatively cold parameter at point 102 to the relatively hot parameter at point 3 (usually the boiling point) and eventually to the parameter at point 5. In general, a “lean stream” refers to a fluid stream that has less low-boiling components than a high-boiling component (eg, water versus ammonia), and a “concentrated stream” refers to a fluid stream that has more low-boiling components than high-boiling components. In addition, an “intermediate lean” stream is a lower boiling point component (eg, ammonia in an ammonia / water composition) than a “lean” stream or “extremely lean” stream (ie, the amount of ammonia is minimal in the ammonia / water composition). But with less low boiling components than the “concentrated” stream.

  The consumed stream at point 17 is then combined with an extremely lean flow having parameters at point 12 to produce a combined fluid stream (ie, an intermediate lean stream) having parameters at point 18. The combined intermediate lean stream is then cooled in heat exchanger 402 to transfer heat from the intermediate lean stream at point 18 to the refrigerant. Devices 402, 404 may include any suitable heat exchange condenser, such as a water or air cooled heat exchanger.

  The refrigerant can be any number or combination of media sufficient to condense the intermediate lean stream from point 18 to point 1 through heat exchanger 402. Such media can include air, water, chemical coolants, etc., and simply circulates in and out of the system 100 as needed. Thus, the refrigerant is introduced into the system 100 at a relatively low temperature, such as at point 23, heated to points 59, 58 by heat exchangers 402, 404, and then circulates out of the system 100 at a relatively warm temperature at point 24. As the refrigerant circulates in and out of the system, it is possible to maintain a relatively low constant temperature and absorb heat from the multicomponent stream.

After the intermediate lean stream is condensed to the point 1 parameter, the pump 504 increases the pressure of the stream and the intermediate lean stream is increased to the point 2 parameter. Thereafter, the intermediate lean flow with the increased pressure is divided into two parts. As will be explained in more detail later, one part has a parameter of point 8 and is mixed with a concentrated stream having a parameter of point 6. The other part of the pressure-increased intermediate lean stream having the parameter at point 102 is heated by the consumption stream at point 16 in apparatus 401 such that the intermediate lean stream obtains the parameter at point 5.

  At point 5, the intermediate lean stream is primarily separated into vapor and liquid components by device 503 such that the vapor component has a parameter of point 7 and the liquid component has a parameter of point 9. However, it is recognized that neither the vapor component nor the liquid component is purely one component or another component. In any case, the vapor stream is rich in low-boiling components (ie, a “concentrated” stream) and the liquid stream has a large amount of high-boiling components (ie, a “lean” stream). Apparatus 503 can include any suitable separation or distillation apparatus known in the art, such as a gravity separation apparatus (eg, a conventional flash tank).

In one embodiment, the vapor and liquid components of the stream at points 7 and 9 are selectively mixed (or not mixed) to heat (or maintain) the total amount of temperature supplied in the intermediate heat exchanger 403. Separated). For example, the portion of steam at point 7 can be selectively split into one stream at point 6 and another stream at point 15. If the liquid component at point 9 is not hot enough to heat the multi-component stream from point 21 to point 29 by heat exchanger 403, a large portion of the higher temperature vapor component stream from point 15 In addition to the liquid component stream, it is possible to produce a hotter stream having point 10 parameters. Alternatively, if the liquid component at point 9 is hot enough for the heat exchanger 403, it is not necessary to mix with steam at point 15. Such mixing is therefore optional and depends on the relevant operating conditions.

  Regardless of whether such mixing occurs, the stream at point 10 is generally an “extremely lean” stream, ie, a stream with a relatively small amount of low boiling components. This ultra-lean stream at point 10 passes through the intermediate heat exchanger 403, heating the fluid stream at point 21 and cooling the ultra-lean stream from point 10 to point 11. In some cases, if necessary, the fluid flow at point 11 may be further adjusted to a lower pressure. In any case, the fluid flow at point 11 reaches the parameters at point 12 and is then mixed with the consumption stream at point 17 before passing through the heat exchanger 402.

  Referring back to the flow at point 5, the vapor component at point 7 separated from the liquid component at point 9 differs from the vapor component at points 6 and 15 primarily with respect to the flow velocity. In practice, however, the pressure of the vapor components at points 6, 7, and 15 may be slightly different. In any case, the vapor component (ie, the component at point 7 or component stream 6, 15) is a “concentrated” stream and has a relatively large amount of low boiling components. This “enriched” stream at point 6 is then mixed with a portion of the intermediate lean stream at point 8 to produce a multicomponent stream at point 13. The ratio of the low-boiling point component and the high-boiling point component (for example, the ratio of water and ammonia) in the intermediate flow at point 13 is substantially the same as the working flow used subsequently in the heat transfer process, such as after point 60.

  Next, the intermediate flow at this point 13 is condensed by the above-described refrigerant in the heat exchanger 404 and becomes a condensed flow. Therefore, the fluid flow at point 13 is cooled from the parameter at point 13 to the parameter at point 14. The fluid stream at point 14 is then discharged through pump 505 to provide a high pressure working stream having the parameters at point 21. The working stream at point 21 is then heated to point 29 through heat exchanger 403 such that the intermediate stream is cooled from point 10 to point 11. At point 29, the working stream is heated by the “cold tail” of the heat source stream in heat exchanger 405 such that the heat source stream is cooled from point 54 to 55.

  In view of the above, it will be appreciated that the working stream at point 29 is at a suitable temperature that allows efficient use (ie, heating) of the cold tail in heat exchanger 405. This helps to ensure that the working flow at point 30 passes through turbine 501 at the highest energy available to system 100. Thus, whether the working flow at point 30 reaches the most efficient energy output may depend, in part, on the temperature of the intermediate flow at point 10. For example, if the temperature of the working stream at point 29 is too high, the additional heat transfer from the cold tail from point 54 to 55 is little or not effective. In contrast, if the working stream at point 29 is too cold after passing through DCSS 103, it is impossible for the cold tail from points 54 to 55 to heat the working stream to the desired temperature from point 29 to point 60. is there.

In one embodiment of the present invention, DCSS 103 helps to ensure that the working stream at point 29 is at the proper temperature by allowing variable heat to be applied to the intermediate stream at point 10. As mentioned above, this can be done by variably adding (or not adding) the vapor component 15 to the liquid component 9. In other words, as more steam 15 is added to stream 9, the mixed fluid stream at point 10 becomes hotter and more heat is applied to the working stream at point 21. Thus, allowing separation and mixing of fluid streams in the DCSS 103 allows the system 100 to efficiently use the cold tail (ie, points 54-55) in the working stream. Further, embodiments of the present invention effectively use a low heat source flow for additional power, such as in turbines 501 and 502.

  FIG. 2 shows an alternative heat transfer system 200 that incorporates only a single turbine 502. Specifically, as shown in FIG. 2, the system 100 can be modified to omit the streams 32, 150, 151 and the heat exchanger 305. Thereby, only the working stream at point 30 passes through the turbine 502 to produce a consumption stream 36 which is then processed in the heat exchanger 302 as described above. However, as noted above, the number of turbines that can be used for increased energy gain may be varied within the scope of the present invention.

  In an alternative embodiment of the present invention, heat exchanger 303 may be omitted instead of heat exchanger 304, whether system 100 or system 200. In another alternative embodiment, the heat exchanger 302 may be omitted instead of the heat exchanger 301.

1 is a diagram of a heat transfer system according to an embodiment of the invention using two turbines. FIG. 4 is a diagram of a heat transfer system according to another embodiment of the invention that uses one turbine.

Claims (4)

An apparatus for performing a thermodynamic cycle,
An expansion device connected to receive a multi-component gaseous working stream and adapted to convert the energy of the multi-component gaseous working stream into a usable form and producing a precondensed stream When,
A distillation condensing subsystem configured to receive a precondensate stream having a first temperature parameter;
The distillation condensation subsystem is
At least a first condenser configured to condense the pre-condensate stream to produce a condensed stream;
A flow separation device configured to separate a condensed stream into a concentrated and dilute stream for use in generating a liquid working stream, and configured to substantially separate the vapor component of the intermediate stream from the liquid component. Flow separator ,
A pump configured to pressurize the liquid working stream to produce a pressurized working stream having a temperature parameter lower than the temperature parameter of the condensate stream prior to entering the distillation condensation subsystem; and
Providing a first heat exchanger configured to heat the pressurized working stream utilizing the flow from the distillation condensation subsystem;
The distillation condensing subsystem is further configured to optionally recombine the intermediate stream vapor component with the intermediate stream liquid component to obtain a temperature suitable for the intermediate stream;
A residual heat exchanger configured to receive a pressurized working stream from the first heat exchanger and to utilize the cold tail of the external heat source stream to heat the pressurized working stream;
The pressure parameter of the pressurized working stream entering the residual heat exchanger is lower than the temperature parameter of the condensate stream before entering the distillation condensation subsystem. The first heat exchanger, so that the intermediate stream to a suitable temperature for use in low temperature tail to heat the working stream, claim to transfer heat to working stream after passage of the intermediate flow separator device from the intermediate stream 1 The device described in 1. A method for performing a thermodynamic cycle comprising:
A working flow expansion process that expands a multi-component gaseous working stream and converts the energy into a usable form to produce a consumed stream;
A consumption flow cooling step of cooling the consumption flow in the heat exchanger using an intermediate flow composed of a vapor component and a liquid component to generate a precondensed flow;
Dividing the intermediate flow into a substantially vapor component and a substantially liquid component;
The pre-condensate flow condensing step for condensing the pre-condensate flow in the distillation condensing subsystem to generate a condensate flow, the temperature of the pre-condensate flow after the consumption flow cooling step and before the pre-condensate flow condensing step is the first temperature. Being a parameter,
A condensate flow separation step that separates the condensate stream into a concentrated and dilute stream to produce a liquid working stream;
A liquid working flow pressurization step for pressurizing the liquid working flow and generating a pressurized working flow;
Utilizing a flow from the distillation condensation subsystem to heat the pressurized working stream in the first heat exchanger;
Using a low temperature tail of the external heat source stream to heat the pressurized working stream from the first heat exchanger in the residual heat exchanger, and a temperature of the pressurized working stream entering the residual heat exchanger The parameter is lower than the temperature parameter of the pre-condensate stream entering the distillation condensation subsystem;
Optionally changing the temperature of the substantially liquid component of the intermediate stream by the approximately vapor component of the intermediate stream such that the working stream is heated to a temperature suitable for further heating by the low temperature tail . A distillation condensing subsystem configured to transfer heat from a heat source stream so that a cold tail of the heat source stream is efficiently utilized;
One or more configured to transfer heat from the consumer stream to the intermediate stream in the distillation condensing subsystem such that the consumer stream is cooled and the intermediate stream is heated to a substantially vapor component and a substantially liquid component. A heat exchanger,
An intermediate heat exchanger that operably couples the power subsystem to the distillation condensing subsystem to transfer heat from the intermediate flow of the distillation condensing subsystem to the working flow of the power subsystem;
The separator is configured to separate the substantially vapor component from the substantially liquid component so that the intermediate flow is substantially composed of the liquid component, and the intermediate component is optionally made available by the vapor component so that the working stream is brought to an appropriate temperature. A distillation condensing subsystem comprising: a separation device configured to be heated to ;

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