JP2013181397A - Binary power generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable stable power generation by maintaining an overheated state of a working medium even if a temperature of a heat source drops suddenly in a binary power generator.SOLUTION: A binary power generator 1 comprises an evaporator 2 for evaporating a working medium T with hot water S supplied from a heat source S, and an expander 3 for generating rotational driving force by expanding the steam of the working medium T produced by the evaporator 2. The binary power generator drives an electric generator using the rotational driving force. A heat buffer means 20 for restraining the temperature fluctuation of the hot water S introduced into the evaporator 2 is provided on an input side of the evaporator 2.

Description

  The present invention relates to a binary power generator.

Conventionally, heat is transferred from a low-temperature heat source (hot water) that does not have enough heat to rotate the steam turbine to a low-boiling working medium heat cycle, and the working medium is stored in a circulation cycle having these two heat cycles. There is a binary power generation device as a power generation device that performs power generation.
As a document disclosing the basic configuration of the binary power generation apparatus, for example, there is Patent Document 1. Patent Document 1 discloses an evaporator that evaporates a refrigerant by heat exchange with a high temperature medium, a turbine generator that is driven by the refrigerant supplied from the evaporator, and a refrigerant that is discharged from the turbine generator is a cold medium. A condenser for condensing the refrigerant by heat exchange, and a pump for supplying the refrigerant condensed by the condenser to the evaporator, and the evaporator, the turbine generator, the condenser and the pump are contained therein. Discloses a binary power generation device connected by a closed cycle line in which is enclosed.

  As a technique for effectively using heat generated in the condenser of the binary power generation apparatus (exhaust heat from the binary power generation apparatus), a technique disclosed in Patent Document 2 has been developed. Patent Document 2 discloses a first evaporator capable of evaporating a working medium, an expander that expands the evaporated working medium, a first condenser that condenses the working medium from the expander, and a first A Rankine cycle comprising a pump for sending a working medium from a condenser to the first evaporator, and a generator is connected to the expander so that expansion work of the working medium can be taken out as electric power. In the combined heat and power system that can use heat radiation in the first condenser as a heat source, a compressor that compresses the working medium evaporated by the second evaporator, and a second that condenses the working medium from the compressor A heat pump cycle for returning the working medium from the condenser and the second condenser to the second evaporator through a throttling mechanism, and the working mediums of the first condenser and the second evaporator The heat exchange configuration Binary power generation apparatus is disclosed a.

JP 2004-286024 A JP 2006-292273 A

However, in a conventional binary power generation apparatus using a low-temperature heat source such as Patent Document 1, if the temperature of the heat source (hot water) is drastically decreased, the power generation amount of the binary power generation apparatus may be reduced. Absent. That is, it is conceivable that the temperature of the heat source varies depending on the season, time, environment, etc., and the power generation amount of the binary power generation device becomes unstable.
For example, in the case of a heat source such as a hot spring, the temperature of hot water from the hot spring decreases due to a change in geothermal heat, and heat exchange with the working medium becomes difficult. Further, in the case of a heat source such as factory exhaust heat, the hot water generated after being used for cooling or the like is not subjected to strict temperature control of the heat source, and it may be difficult to exchange heat with the working medium. Therefore, the amount of power generated by the binary power generator may be reduced due to fluctuations in these conditions.

Further, when the temperature of the heat source is suddenly lowered, the temperature of the working medium passing through the evaporator is also lowered, which causes a problem that the working medium becomes a gas-liquid two-phase flow at the outlet of the evaporator. In the case of a gas-liquid two-phase flow, a problem arises that a liquid working medium enters the expander, the liquid working medium is mixed with oil, and the oil cannot be returned from the oil recovery unit.
The above-described combined heat and power system disclosed in Patent Document 2 is intended to always achieve desired hot water supply and heating regardless of variations in seasons, times, etc., and discloses means for solving the above-described problems. It is not supposed to be.

Therefore, in view of the above problems, the present invention has an object to provide a binary power generation device that can maintain a superheated state of a working medium even when the temperature of a heat source rapidly decreases and can perform stable power generation. And

In order to achieve the above-mentioned object, the following technical means were taken in the binary power generation apparatus of the present invention.
A binary power generation apparatus according to the present invention includes an evaporator that evaporates a working medium with hot water supplied from a heat source, and an expander that expands steam of the working medium generated by the evaporator to generate a rotational driving force. In the binary power generation apparatus that drives the generator using the rotational driving force, a thermal buffer means for suppressing temperature fluctuations of the hot water introduced into the evaporator is provided on the inlet side of the evaporator. It is characterized by that.

Preferably, the heat buffer means suppresses temperature fluctuations of the hot water introduced into the evaporator so that the overheating state of the working medium can be maintained even when the temperature of the hot water supplied from the heat source changes. It should be configured.
Preferably, the thermal buffer means is a storage tank that secures a capacity capable of storing hot water before being introduced into the evaporator.

Preferably, in the storage tank, hot water is introduced into the storage tank, and an inlet that forms a flow of warm water along the inner side of the side wall constituting the storage tank, and hot water from the central portion of the storage tank to the outside. It is preferable that an outflow port for discharging is provided.
Preferably, a heat storage material is provided inside the thermal buffer means.

  According to the binary power generation device of the present invention, even if the temperature of the heat source rapidly decreases, the overheating state of the working medium can be maintained and stable power generation can be performed.

It is the figure which showed the binary electric power generating apparatus of 1st Embodiment. It is the figure which showed the structure of the storage tank (thermal buffer means), and the flow of warm water inside. It is the figure which showed the temperature change of the warm water by the side of the storage tank at the time of using the storage tank shown in FIG. It is the figure which showed the binary electric power generating apparatus of 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
The binary power generator 1 of the present invention exchanges heat between a low-temperature heat source S that does not have enough heat to rotate a steam turbine and a circulation cycle that encloses a low-boiling working medium T, and evaporates by this heat exchange. Electric power is generated using the working medium T.

  As shown in FIG. 1, the binary power generator 1 of the present invention evaporates the working medium T into steam by exchanging heat with an external low-temperature heat source S (hereinafter also referred to as hot water S). An evaporator 2, an expander 3 that generates a rotational driving force by expanding the working medium T that has been vaporized by the evaporator 2, and a generator that generates power by the rotational driving force generated by the expander 3 (see FIG. Not shown). Further, an oil recovery unit 4 that recovers the lubricating oil used in the expander 3 and a condenser 5 that condenses the vapor working medium T, which has been used in the expander 3 and has become a low pressure, into a liquid working medium T. And.

  These evaporator 2, expander 3, oil collector 4, and condenser 5 are sequentially connected by a closed loop circulation pipe 6 that circulates the working medium T, and this circulation pipe 6 includes an evaporator 2 → The working medium T (low-boiling organic medium such as pentane, hexane, or alternative chlorofluorocarbon (R245fa)) that has become liquid via the expander 3 → oil recovery device 4 → condenser 5 is again sent to the evaporator 2 A working medium pump 7 is provided.

In the binary power generation device 1 having such a configuration, the liquid working medium T is evaporated by the heat of the hot water S, and the expander 3 is driven using the working medium T that has become steam to generate electric power. Specifically, the evaporator 2 collects heat from the hot water S and exchanges heat via the collected heat, thereby evaporating the liquid working medium T and generating the steam working medium T.
A storage tank 20 (thermal buffer means), which will be described later, is provided on the entry side of the evaporator 2, and hot water S passing through the storage tank 20 is sent to the evaporator 2. The hot water S sent to the evaporator 2 exchanges heat with the liquid working medium T flowing in the circulation pipe 6 to generate the liquid working medium T in the vapor working medium T. The hot water S after the heat exchange is discarded to the outside.

At this time, the working medium T reliably vaporized by the evaporator 2 is sent to the expander 3 through the circulation pipe 6.
In the expander 3, the working medium T vaporized in the evaporator 2 expands, and the rotor and the screw rotate using the pressure difference (high pressure → low pressure) between the working medium T before and after the expansion to generate a rotational driving force. I am letting. The generator connected to the expander 3 generates power using this rotational driving force.

The vapor of the low-pressure working medium T used for power generation by the generator is sent to the condenser 5 through the circulation pipe 6 on the outlet side of the expander 3. In the condenser 5, the steam of the working medium T sent from the expander 3 is heat-exchanged with the cooling water W and condensed into the liquid working medium T. Further, the lubricating oil used in the expander 3 is recovered by the oil recovery device 4 connected to the outlet side of the expander 3.
The working medium T that has become liquid in the condenser 5 is sent to the working medium pump 7. The liquid working medium T is pressurized by the working medium pump 7 and is pumped again to the evaporator 2 through the circulation pipe 6. In this manner, the working medium T circulates through the circulation pipe 6 formed in the closed loop shape in the order of the working medium pump 7 → the evaporator 2 → the expander 3 → the condenser 5 → the working medium pump 7. Power is generated by the connected generator.

The binary power generator 1 of the first embodiment shown in FIG. 1 is characterized by having a storage tank 20 (thermal buffer means). Therefore, hereinafter, the description will be focused on the storage tank 20. The configurations of the evaporator 2, the expander 3, the oil collector 4, the condenser 5, and the working medium pump 7 are substantially the same as those used in the conventional binary power generator 1.
Although various things can be considered as the heat source S used for the binary power generator 1, the heat source S in the present embodiment takes into consideration the hot water S obtained from a hot spring source or the like, or hot water S such as factory waste water. There is no guarantee that the temperature of these hot waters S is always constant, and the temperature varies over a span of several days to several seconds. Particularly problematic is the situation where the temperature of the hot water S decreases within a few seconds, and there is a risk that the power generation amount of the binary power generator 1 will be significantly reduced by such a rapid temperature fluctuation.

  Therefore, as shown in FIG. 1, a storage tank 20 (thermal buffer means) that suppresses temperature fluctuations of the hot water S introduced into the evaporator 2 is provided on the inlet side of the evaporator 2 of the binary power generation device 1 of the present embodiment. Is provided. Specifically, it is a water storage tank that secures a capacity capable of storing hot water S before introduction in the evaporator 2. A first thermometer 8 that measures the temperature of the hot water S is disposed on the inlet 21 side of the storage tank 20. On the outlet 22 side of the storage tank 20, there are a hot water pump 11 that adjusts the flow rate of the hot water S, a flow meter 10 that measures the flow rate of the hot water S, and a second thermometer 9 that measures the outflow temperature of the hot water S. They are deployed in order.

  For example, the hot water S whose temperature has dropped rapidly due to a change in geothermal heat flows into the storage tank 20 from the inlet 21 formed in the storage tank 20. The inflowing hot water S flows along the inner wall of the storage tank 20 to agitate the hot water S. At that time, the temperature drop of the hot water S is alleviated depending on the storage time. The hot water S in which the temperature drop has been alleviated is supplied to the evaporator 2 of the binary power generator 1. The hot water S that is maintained in the amount of heat while the temperature drop is mitigated can reliably evaporate the liquid working medium T flowing in the evaporator 2. The hot water S used for the evaporator 2 is discarded to the outside.

In the storage tank 20, it is effective to increase the residence time of the hot water S by increasing the tank capacity in order to reliably relieve the rapid temperature drop of the hot water S supplied from the heat source S. In order to make the flow rate of the hot water supplied to the evaporator 2 constant, the hot water S flowing out from the storage tank 20 may be measured with the flow meter 10 and the flow rate adjusted with the hot water pump 11.
Such a storage tank 20 is introduced into the evaporator 2 in order to maintain the overheated state of the working medium T even when the temperature of the hot water S supplied from the external heat source S is suddenly changed. It can be said that it is comprised so that the temperature fluctuation of the warm water S performed may be suppressed.

  For example, in the binary power generation device 1 shown in FIG. 1, it is assumed that the temperature Tw0 of the hot water S supplied from the heat source S rapidly decreases at ΔT (° C./sec). The pressure of the working medium T after the warm water S that has caused the temperature drop of ΔT is supplied to the evaporator 2 and exits the evaporator 2 falls below a predetermined level, or the working medium T becomes a gas-liquid two-phase flow. Suppose that a situation occurs in which the amount of power generation decreases. The storage tank 20 of the present embodiment stores a large volume of hot water S in the tank, so that even if the hot water S supplied from the heat source S changes by ΔT, the storage tank 20 exits, that is, the evaporator 2 The change in the incoming hot water temperature Tw1 is a moderate value ΔT ′ (<ΔT, for example, ΔT ′ = 0.1 · ΔT to 0.01 · ΔT). If the temperature drop of the hot water S on the inlet side of the evaporator 2 is a temperature drop amount of ΔT ′ (° C./sec), the working medium T can be reliably vaporized in the evaporator 2. Therefore, it is possible to reliably avoid a decrease in the amount of power generated by the binary power generator 1.

In addition, you may make it obtain the specific value of temperature fall amount (DELTA) T 'of the warm water S which does not affect the operation | movement of the binary power generator 1 from the track record of actually operating the binary power generator 1. The binary power generation apparatus 1 may be converted into a control model and determined based on the response time of the control model.
By the way, various shapes can be adopted as the shape of the storage tank 20. In FIG. 2, the shape of the storage tank 20 which this inventor employ | adopted is shown.

The storage tank 20 shown in FIG. 2A includes a cylindrical side wall 23 whose axis is oriented in the vertical direction, and an upper wall 24 surface and a bottom wall 25 surface that close the upper and lower openings of the cylindrical side wall. It is configured.
In the storage tank 20, an inflow port 21 through which hot water S from the outside can be introduced is formed on the upper side of the side wall 23 of the storage tank 20 and along the tangential direction of the cylindrical side wall 23. Yes. Therefore, the hot water S introduced from the inflow port 21 forms a flow along the inner side (inner wall) of the side wall 23 of the storage tank 20.

On the other hand, an outlet 22 is formed in the central portion of the upper wall 24 surface of the storage tank 20 through which the hot water S circulating inside flows out from the center of circulation. The outlet 22 is formed so as to face in the vertical direction, and the hot water S flows out upward. The warm water S that has flowed out is guided to the evaporator 2. The outlet 22 may be formed at the center of the bottom wall 25 surface.
The storage tank 20 shown in FIG. 2 (b) has the same shape as that shown in FIG. 2 (a), and is a tank in which the capacity for storing the hot water S before being introduced into the evaporator 2 is secured. is there. The storage tank 20 includes a cylindrical side wall 23 whose axis is oriented in the vertical direction, and an upper wall 24 surface and a bottom wall 25 surface that close the upper opening and the lower opening of the cylindrical side wall 23.

  The storage tank 20 is formed with an inlet 21 through which hot water S from the outside can be introduced, and an outlet 22 through which the hot water S stored inside flows out. The inflow port 21 and the outflow port 22 are formed so as not to face each other in the vertical direction. Specifically, the inflow port 21 into which the hot water S from the outside can be introduced is formed on the upper side of the side wall 23 of the storage tank so as to be directed toward the center (axial center) of the cylindrical side wall 23. Has been. The outflow port 22 is formed on the lower side of the side wall 23 of the storage tank and toward the central portion (axial center) of the cylindrical side wall 23.

  The storage tank 20 shown in FIG. 2 (c) is composed of a cylindrical side wall 23 whose axis is oriented in the horizontal direction, and one side wall 26 surface and the other side wall 27 surface that block the left-right direction of the cylindrical side wall 23. ing. That is, the storage tank 20 shown in FIG. 2C is a barrel-shaped tank 20c placed horizontally. In the storage tank 20, an inflow port 21 through which hot water S from the outside can be introduced is formed at the center of one side wall 26, and an outflow port 22 through which the hot water S stored inside flows out is formed on the other side wall 27. It is formed at the center. In other words, the inflow port 21 and the outflow port 22 are formed on the same straight line.

FIG. 2D shows a pipe that does not have the storage tank 20, and shows a conventional binary power generator 1. With this structure, the hot water S supplied from the heat source S is straightly introduced into the evaporator 2, and the temperature drop of the hot water S directly affects the binary power generator 1.
The graph shown in FIG. 3 shows hot water on the outlet side of the storage tank 20 when the storage tank 20 of FIGS. 2A to 2C is used and when the storage tank 20 is not used (FIG. 2D). This is a result of computer simulation of the temperature change of S, that is, the temperature change of the hot water S on the inlet side of the evaporator 2. The horizontal axis of this graph indicates time (sec), and the vertical axis indicates temperature (° C.).

First, in the case of the pipe not having the storage tank 20 shown in FIG. 2D, the temperature change of the hot water S introduced into the evaporator 2 is indicated by a two-dot chain line in FIG. As can be seen from this graph, the 90 ° C. hot water S supplied from the heat source S drops 5 ° C. in about several seconds, and then supplied at 85 ° C. Therefore, the temperature drop of the hot water S directly affects the binary power generator 1.
On the other hand, when the storage tank 20 as shown in FIG. 2A is employed as the thermal buffer means under the above situation, the hot water S introduced from the inflow port 21 in the cylindrical side wall is located inside the cylindrical side wall 23 ( Circulates along the inner wall), stays in the storage tank for a certain period of time, and flows out from the outlet 22 at the center of the upper wall 24 surface of the storage tank. As described above, when the hot water S stays in the storage tank 20 for a certain time or longer, as shown by the solid line in FIG. 3, the temperature change of the hot water S at the outlet 22 of the storage tank 20 (a decrease of 5 ° C.). However, it can be seen that the temperature is extended to about 120 seconds, resulting in a gradual temperature change. In particular, the hot water S at the outlet 22 can be maintained at about 90 ° C. for about 10 seconds after the temperature-decreased hot water S flows, and the effect of maintaining the warm water temperature in the initial stage is shown in FIGS. It is larger than the storage tank 20 shown in FIG.

  2B, the hot water S introduced from the inlet 21 above the cylindrical side wall 23 stays in the storage tank 20 for a certain period of time. , And flows out from the outlet 22 below the storage tank 20. As a result, as shown by the dotted line in FIG. 3, the time of the temperature drop (5 ° C. drop) of the hot water S at the outlet 22 becomes about 120 seconds and becomes gentle.

  When the storage tank 20 as shown in FIG. 2C is adopted, the hot water S that has flowed in from the inlet 21 formed on the one side wall 26 of the barrel-shaped tank 20 c that is placed horizontally is placed inside the storage tank 20. It stays and flows out from the outlet 22 of the other side wall 27. As a result, as shown by the alternate long and short dash line in FIG. 3, although the amount of decrease in the initial hot water temperature is slightly large, the temperature decrease at the outlet 22 (reduction of 5 ° C.) is 120 seconds or more, which is very gentle. .

From the above results, in the binary power generation device 1 of the present invention, the rapid change of the hot water S can be mitigated by arranging the storage tank 20 on the entry side of the evaporator 2. The overheated state of the working medium T can be maintained, and stable power generation can be performed.
[Second Embodiment]
Next, a second embodiment of the binary power generator according to the present invention will be described.

  Similarly to the first embodiment, the binary power generation apparatus 1 of the second embodiment also stores the hot water S from the heat source S for a certain period of time, and then supplies the hot water S to the evaporator 2. Have However, the storage tank 20 of the second embodiment is characterized in that a heat storage material 30 is provided in the inside thereof. Other configurations are substantially the same as those in the first embodiment. That is, regarding the binary power generation device 1 of the second embodiment, the configurations of the evaporator 2, the expander 3, the oil recovery device 4, the condenser 5, and the working medium pump 7 are used in the binary power generation device 1 of the first embodiment. Is almost the same as The point which the 1st thermometer 8, the 2nd thermometer 9, the flow meter 10, and the hot water pump 11 is arrange | positioned is also substantially the same as 1st Embodiment.

  As shown in FIG. 4, a storage tank 20 provided with a heat storage material 30 is provided on the entry side of the evaporator 2 of the binary power generation device 1 of the second embodiment. A heat storage material 30 is disposed inside the storage tank 20. The inflow port 21 is formed in the lower part of the storage tank 20 and below the heat storage material 30. The outflow port 22 is an upper part of the storage tank 20 and is formed above the heat storage material 30. Thereby, the hot water S which flowed in from the inflow port 21 passes through the heat storage material 30, so that the heat storage material 30 and the hot water S can exchange heat. The hot water S having a predetermined temperature compensated for the temperature drop of the heat source S by the heat from the heat storage material 30 flows out from the outlet 22 of the storage tank to the evaporator 2.

As the heat storage material 30, it is considered to employ a material having a large thermal conductivity and a large heat capacity such as ceramic or metal (an enclosure heat storage material), or a latent heat storage material that stores heat using heat accompanying phase change. It is done. A member in which a liquid medium is sealed can also be used as the heat storage material 30 (liquid heat storage material). Further, in the case of the frame heat storage material, if the heat storage material 30 has a porous or honeycomb structure, the heat exchange efficiency from the heat storage material 30 to the hot water S is improved. From the above viewpoint, for example, an aluminum honeycomb heat storage material is preferable as the heat storage material 30 provided in the storage tank 20.

In order to determine the heat retention amount in the heat storage material 30, in other words, the material and mass of the heat storage material 30, the following may be performed.
For example, when the flow rate of the hot water S from the heat source S is m [kg / min], the specific heat of the hot water S is Cpw [kJ / kg ° C.], and the temperature change is ΔT [° C.], the heat capacity accompanying the temperature change is Q [ kJ / min] = m × Cpw × ΔT.

On the other hand, when the mass of the heat storage material 30 is M [kg], the specific heat of the heat storage material 30 is Cpm [kJ / kg ° C.], and the temperature change is ΔT [° C.], the heat capacity of the heat storage material 30 is Qm [kJ] = M × Cpm × ΔT
If both the heat quantities Q and Qm are in the same state for t minutes, that is, if the temperature holding for t minutes is intended, the following equation holds.

Q × t [kJ] = Qm [kJ] = M × Cpm × ΔT
What is necessary is just to select the material and mass of the thermal storage material 30 so that this type | formula may be satisfy | filled. If it is intended to hold the temperature for 1 minute, t = 1 in the above equation.
In order to make the flow rate of the hot water supplied to the evaporator 2 constant, the hot water S flowing out from the storage tank 20 may be measured with the flow meter 10 and the flow rate adjusted with the hot water pump 11.

Even in the binary power generation apparatus 1 of the second embodiment described above, the rapid change of the hot water S can be alleviated, the overheating state of the working medium T can be maintained, and stable power generation can be performed. .
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive.

For example, although the storage tank 20 of this embodiment is described as a cylindrical shape, any shape may be used as long as the hot water S circulates inside the storage tank 20 and can stir the entire warm water.
Further, in the embodiment disclosed this time, matters that are not explicitly disclosed, for example, operating conditions and operating conditions, various parameters, dimensions, weights, volumes, and the like of a component deviate from a range that a person skilled in the art normally performs. Instead, values that can be easily assumed by those skilled in the art are employed.

DESCRIPTION OF SYMBOLS 1 Binary power generator 2 Evaporator 3 Expander 4 Oil recovery machine 5 Condenser 6 Circulation piping (working medium)
7 Working medium pump 8 First thermometer 9 Second thermometer 10 Flow meter 11 Hot water pump 20 Storage tank (thermal buffer means)
DESCRIPTION OF SYMBOLS 21 Storage tank inflow port 22 Storage tank outflow port 23 Side wall 24 Upper wall 25 Bottom wall 26 One side wall 27 The other side wall 30 Thermal storage material S Heat source (hot water)
T Working medium W Cooling water

Claims (5)

An evaporator that evaporates the working medium with hot water supplied from a heat source; and an expander that expands the vapor of the working medium generated by the evaporator to generate a rotational driving force, and uses the rotational driving force. In the binary power generator that drives the generator,
A binary power generation apparatus characterized in that a heat buffer means for suppressing temperature fluctuations of hot water introduced into the evaporator is provided on the inlet side of the evaporator.   The heat buffer means is configured to suppress temperature fluctuation of the hot water introduced into the evaporator so that the working medium can be maintained in an overheated state even when the temperature of the hot water supplied from the heat source changes. The binary power generator according to claim 1.   The binary power generator according to claim 1 or 2, wherein the thermal buffer means is a storage tank having a capacity capable of storing hot water before being introduced into the evaporator.   The storage tank introduces hot water into the storage tank and forms a flow of hot water along the inner side of the side wall constituting the storage tank, and a flow that causes the warm water to flow out from the center of the storage tank to the outside. The binary power generator according to claim 3, wherein an outlet is provided.   The binary power generator according to any one of claims 1 to 3, wherein a heat storage material is disposed inside the thermal buffer means.

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