JP2011185570A - Exhaust heat recovery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust heat recovery device capable of suppressing reduction in recovery heat quantity along with passage of time. <P>SOLUTION: The exhaust heat recovery device includes: a heating medium circulation passage 2 circulating a heating medium C via an exhaust heat generating device G, a heat recovery part R and an atmosphere opening type heating medium storage tank 1; and a heating medium circulation means 3 circulating the heating medium C through the heating medium circulation passage 2 to recover exhaust heat generated in the exhaust heat generating device G by the heat recovery part R via the heating medium C. The heating medium C includes water W and a freezing-point depressant for depressing the freezing point of the heating medium C. The exhaust heat recovery device further includes: a heating medium supply state control means A controlling the supply state of the heating medium C supplied to the heat recovery part R; a recovery heat quantity measuring means M measuring recovery heat quantity recovered from the heating medium C by the heat recovery part R; and a control means 7 controlling the operation of the heating medium supply state control means A so that the recovery heat quantity becomes target heat quantity based on the measurement information by the recovery heat quantity measuring means M. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention includes a heat medium circulating path through which a heat medium is circulated through an exhaust heat generator, a heat recovery unit, an open air type heat medium storage tank, and exhaust heat generated by the exhaust heat generator. A heat medium circulating means for circulating the heat medium through the heat medium circulation path is provided in order to recover the heat medium through the heat medium in the recovery unit, and the heat medium is used for lowering the freezing point of water and the heat medium. The present invention relates to an exhaust heat recovery apparatus including a freezing point depressant.

Such an exhaust heat recovery device recovers and uses exhaust heat generated in the exhaust heat generation device in a heat recovery unit, and examples of the exhaust heat generation device include an engine that drives a generator. For example, the heat recovery unit is configured to heat the hot water in the hot water storage tank by the recovered exhaust heat.
And in order to prevent freezing of the heat medium in a heat-medium circulation path, what contains the freezing point depressant for lowering the freezing point of water and a heat medium is used for a heat medium (for example, refer patent document 1). .)
Incidentally, ethylene glycol is used as an example of a freezing point depressant.

In such an exhaust heat recovery device, conventionally, when the storage amount of the heat medium in the heat medium storage tank becomes the lower limit, the heat medium storage tank is replenished with water until the storage amount reaches the upper limit.
Although not clearly described in Patent Document 1, the flow rate of the heat medium flowing through the heat medium circulation path is adjusted to maintain the temperature of the heat medium sent from the exhaust heat generator at a predetermined temperature. Was configured to be.

JP 2004-263940 A

By the way, since the heat medium storage tank is open to the atmosphere, the components of the heat medium evaporate in the heat medium storage tank, but since the vapor pressure is different between water and the freezing point depressant, water and the freezing point depressant are heated. The degree of evaporation in the medium storage tank is different. Moreover, the specific heat is different between water and the freezing point depressant.
For example, when ethylene glycol is used as the freezing point depressant, water and the freezing point depressant have higher vapor pressure and higher specific heat.
And, for example, when water and the freezing point depressant have higher vapor pressure and higher specific heat, water is more likely to evaporate in the heat medium storage tank. The concentration of the freezing point depressant in the medium increases and the specific heat of the heat medium decreases.
Incidentally, when the specific heat of the heat medium is reduced, even if the temperature of the heat medium flowing through the heat medium circulation path is the same, the amount of heat carried by the heat medium flowing through the heat medium circulation path decreases.

However, the temperature of the heat medium sent from the exhaust heat generation device is such that water is replenished until the upper limit is reached when the amount of heat medium stored in the heat medium storage tank reaches the lower limit, as in a conventional exhaust heat recovery apparatus. In the configuration in which the flow rate of the heating medium is adjusted so as to be constant, as the concentration of the freezing point depressant in the heating medium increases and the specific heat of the heating medium decreases with time, the heat recovery unit removes the heating medium from the heating medium. There was room for improvement because the amount of recovered heat was reduced.
Further, when the amount of heat recovered at the heat recovery unit is reduced, there is a risk that the temperature of the exhaust heat generator rises excessively.

  This invention is made | formed in view of this situation, The objective is to provide the waste heat recovery apparatus which can suppress the reduction | decrease in the amount of recovered heat with time passage.

The exhaust heat recovery device of the present invention is generated by an exhaust heat generation device, a heat recovery unit, a heat medium circulation path for circulating a heat medium via an air release type heat medium storage tank, and the exhaust heat generation device. A heat medium circulating means for circulating the heat medium through the heat medium circulation path is provided in order to recover the exhaust heat through the heat medium in the heat recovery unit, and the heat medium is a freezing point of water and the heat medium. A freezing point depressant for lowering
The first characteristic configuration is a heat medium supply state adjusting means capable of adjusting a supply state of the heat medium supplied to the heat recovery unit, and
Recovered heat amount measuring means for measuring the recovered heat amount recovered from the heat medium in the heat recovery unit,
Control means for controlling the operation of the heating medium supply state adjusting means so that the recovered heat quantity becomes a target heat quantity based on the measurement information of the recovered heat quantity measuring means is provided.

According to the above characteristic configuration, the supply state of the heat medium supplied to the heat recovery unit is adjusted by the heat medium supply state adjusting unit so that the recovered heat amount recovered from the heat medium in the heat recovery unit becomes the target heat amount. The
In other words, because the vapor pressures are different, the degree of evaporation in the heat medium storage tank differs between water and the freezing point depressant, and even if the specific heat differs between water and the freezing point depressant, the heat medium supplied to the heat recovery unit By adjusting the supply state, the amount of heat recovered in the heat recovery unit is adjusted so as to become the target amount of heat, so that a decrease in the amount of recovered heat with time can be suppressed.
In addition, since it is possible to suppress a decrease in the amount of recovered heat in the heat recovery section, it is possible to prevent an excessive increase in temperature of the exhaust heat generator.

In addition to the first feature configuration, the second feature configuration is
The heating medium supply state adjusting means is constituted by a heating medium flow rate adjusting means capable of adjusting the flow rate of the heating medium flowing through the heating medium circulation path.

According to the above characteristic configuration, the flow rate of the heat medium flowing through the heat medium circulation path is recovered by the heat medium flow rate adjusting unit so that the recovered heat amount becomes the target heat amount based on the measurement information of the recovered heat amount measuring unit. It is adjusted as the supply state of the heat medium to the part.
That is, even if the specific heat of the heat medium decreases, increasing the flow rate of the heat medium flowing through the heat medium circuit can increase the amount of heat carried by the heat medium flowing through the heat medium circuit. Therefore, heat recovery is achieved by increasing the flow rate of the heat medium flowing through the heat medium circulation path even if the specific heat of the heat medium decreases due to changes in the concentration of the freezing point depressant in the heat medium over time. The amount of heat recovered at the section can be adjusted to the target heat amount.
And since the change in the flow rate of the heat medium flowing through the heat medium circulation path is immediately reflected in the change in the amount of recovered heat in the heat recovery unit, even if the amount of recovered heat in the heat recovery unit starts to decrease from the target heat amount, By increasing the flow rate of the heat medium flowing through the heat medium circulation path, the recovered heat amount can be quickly adjusted to the target heat amount.
Therefore, it has become possible to more accurately suppress a decrease in the amount of recovered heat with time.

In addition to the first or second feature configuration, the third feature configuration is
The heating medium supply state adjusting means is constituted by a heating medium component replenishment intermittent means capable of intermittently supplying water or a freezing point depressant to the heat medium storage tank.

According to the above characteristic configuration, water or a freezing point depressant is replenished to the heat medium storage tank by the heat medium component replenishment intermittent means so that the recovered heat quantity becomes the target heat quantity based on the measurement information of the recovered heat quantity measuring means. By being interrupted, the concentration of the freezing point depressant in the heat medium is adjusted as the supply state of the heat medium to the heat recovery unit.
That is, because the vapor pressure is different, the degree of evaporation in the heat medium storage tank differs between water and the freezing point depressant, and even if the specific heat differs between water and the freezing point depressant, By replenishing the heat medium storage tank with the more easily evaporated, the specific heat of the heat medium can be adjusted by adjusting the concentration of the freezing point depressant in the heat medium so that the recovered heat amount becomes the target heat amount. .
For example, when water and the freezing point depressant have higher vapor pressure and higher specific heat, water tends to evaporate and the concentration of the freezing point depressant in the heat medium tends to be higher. By intermittently replenishing water to the heat medium storage tank by the replenishment intermittent means, the concentration of the freezing point depressant in the heat medium can be adjusted so that the recovered heat amount becomes the target heat amount.
Conversely, with water and the freezing point depressant, if the freezing point depressant has a higher vapor pressure and a higher specific heat, the freezing point depressant tends to evaporate and the concentration of the freezing point depressant in the heating medium tends to be lower. However, it is possible to adjust the concentration of the freezing point depressant in the heating medium so that the recovered heat amount becomes the target concentration by intermittently supplying the freezing point depressant to the heating medium storage tank by the heating medium component replenishment intermittent means. It can be done.

Then, by adjusting the concentration of the freezing point depressant in the heat medium, the amount of heat recovered in the heat recovery unit is set to the target heat amount while maintaining the flow rate of the heat medium flowing through the heat medium circuit at a low level. Therefore, it is possible to suppress an increase in driving energy of the heat medium circulating means.
Accordingly, it is possible to suppress a decrease in the amount of recovered heat with the passage of time while suppressing a decrease in energy efficiency of the exhaust heat recovery apparatus.

The fourth feature configuration is in addition to any one of the first to third feature configurations,
The exhaust heat generator is an engine that drives a generator.

According to the above characteristic configuration, electric power is output from the generator, and exhaust heat of the engine is recovered by the heat recovery unit.
And when exhaust heat of an engine is collect | recovered by a heat recovery part, the fall of the collect | recovered heat amount accompanying time passage can be suppressed.
That is, in the cogeneration system, it is possible to suppress a decrease in the amount of recovered heat with the passage of time, thereby preventing an excessive increase in temperature of the engine that drives the generator.

Block diagram showing the configuration of the cogeneration system The figure which shows the relationship between the flow volume of the heat medium in a heat medium circuit, the density | concentration of the ethylene glycol in a heat medium, and the amount of recovering heat

Hereinafter, based on the drawings, an embodiment when the exhaust heat recovery apparatus according to the present invention is applied to a cogeneration system will be described.
As shown in FIG. 1, the cogeneration system includes a heat medium generator 2, a heat recovery unit R, a heat medium circulation path 2 that circulates the heat medium C via an air release type heat medium storage tank 1, an exhaust A heat medium circulating pump 3 as a heat medium circulating means for circulating the heat medium C through the heat medium circulation path 2 in order to recover the exhaust heat generated in the heat generating device G through the heat medium C in the heat recovery section R. And an operation control unit 4 that controls the operation of the cogeneration system.
And the heat medium C contains the freezing point depressant for lowering the freezing point of the water W and the heat medium C, and ethylene glycol is applied as the freezing point depressant in this embodiment.
In this embodiment, the exhaust heat generator G is the engine 6 that drives the generator 5.

  In the present invention, the heat medium supply state adjusting means A capable of adjusting the supply state of the heat medium C supplied to the heat recovery unit R, and the recovered heat amount for measuring the recovered heat amount recovered from the heat medium C in the heat recovery unit R Based on the measurement information of the measuring means M and the recovered heat quantity measuring means M, there is provided a control means 7 for controlling the operation of the heat medium supply state adjusting means A so that the recovered heat quantity becomes the target heat quantity. 7 is configured by the operation control unit 4. In this example, the heat medium supply state adjusting means A includes the heat medium circulation pump 3 that is the heat medium flow rate adjusting means V and the water supply intermittent valve 16 that is the heat medium component supply intermittent means.

A description of each part of the cogeneration system is added.
On the output side of the generator 5, an inverter 8 for grid connection is provided, and the inverter 8 is set so that the output power of the generator 5 has the same voltage and the same frequency as the received power received from the commercial system 9. It is configured.
The commercial system 9 is electrically connected to a power load 11 such as a television, a refrigerator, or a washing machine via a received power supply line 10.
The inverter 8 is electrically connected to the received power supply line 10 via the generated power supply line 12 so that the generated power of the generator 5 is supplied to the power load 11 via the inverter 8 and the generated power supply line 12. It is configured.

Although not shown, the received power supply line 10 is provided with load power measuring means for measuring the power consumed by the power load 11 (load power). The load power measuring means is connected to the received power supply line 10. It is also configured to detect whether or not a reverse power flow occurs in the current flowing through.
The electric power supplied from the generator 5 to the received power supply line 10 is controlled by the inverter 8 so that a reverse power flow does not occur, and the surplus power of the output power is recovered by replacing the surplus power with heat. 13 to be consumed. Although detailed explanation and illustration are omitted, the electric heater 13 is configured to be capable of adjusting power consumption, and is configured to adjust the power consumption of the electric heater 13 according to the amount of surplus power of the output power. ing.

In this embodiment, a gas engine using gas fuel (for example, natural gas) as fuel is used as the engine 6. The heat medium circulation path 2 is provided to allow the heat medium C to flow as engine cooling water through an engine cooling unit 6j (so-called engine jacket) that cools the engine 6, and the heat medium circulation pump 3 includes a heat medium storage tank. The heat medium C sucked from 1 is provided at a portion downstream of the heat medium storage tank 1 in the heat medium circulation path 2 so as to be discharged toward the engine cooling unit 6j.
The exhaust gas E of the engine 6 is exhausted through the exhaust gas passage 14, and the heat recovery section R is configured to recover the exhaust heat from the exhaust gas E flowing through the exhaust gas passage 14.

The replenishment water channel 15 that replenishes the heat medium storage tank 1 with water W is provided with a water replenishment intermittent valve 16 as a heat medium component replenishment intermittent means that can intermittently replenish water W to the heat medium storage tank 1. .
Further, the storage tank 1 includes a lower limit water level sensor 17 that detects that the storage height of the heating medium C in the storage tank 1 (hereinafter sometimes referred to as a water level) is lower than the lower limit water level, and the storage tank. An upper limit water level sensor 18 for detecting that the water level of 1 is higher than the upper limit water level is provided.

  The heat recovery unit R includes a hot water storage tank 20 that stores hot water H in a state where temperature stratification is formed, a hot water circulation path 21 connected to the bottom and top of the hot water storage tank 20, and the hot water storage tank 20 through the hot water circulation path 21. The hot water circulating pump 22 for circulating the hot water H in the inside, the heat medium C flowing through the heating medium circulation path 2 and the hot water H flowing through the hot water circulation path 21 are subjected to heat exchange and discharged from the heating medium C to the hot water H. The heat exchanger 23 for recovering heat and the exhaust gas E flowing through the exhaust gas passage 14 and the hot water H flowing through the hot water circulation passage 21 are heat-exchanged to recover the exhaust heat from the exhaust gas E to the hot water H. An exhaust gas heat exchanger 24 and the like are provided.

The hot water circulation pump 22 is provided in the hot water circulation path 21 so that the hot water H sucked from the bottom of the hot water storage tank 20 is returned to the top of the hot water storage tank 20, and the hot water circulation pump 22 in the hot water circulation path 21 is provided. Further, the exhaust gas heat exchanger 24 and the heat medium heat exchanger 23 are arranged in order from the upstream side in the hot water flow direction in the downstream side portion. In the heat medium circulation path 2, the heat exchanger 23 for the heat medium is provided in a portion where the heat medium C discharged from the engine cooling unit 6j reaches the heat medium storage tank 1, and is sent from the engine cooling unit 6j. The exhaust heat is recovered from the heat medium C before flowing into the heat medium storage tank 1.
The electric heater 13 is provided downstream of the heat medium heat exchanger 23 in the hot water circulation path 21 so as to heat the hot water H flowing through the hot water circulation path 21.
Then, the hot water H taken out from the bottom of the hot water storage tank 20 is heated by the heat recovered from the exhaust gas E by the exhaust gas heat exchanger 24, and subsequently recovered from the heat medium C by the heat medium heat exchanger 23. The hot water H is stored in a state where a temperature stratification is formed in the hot water storage tank 20 by heating with heat and further returning to the top of the hot water storage tank 20 by heating with the electric heater 13 that consumes surplus power of the generator 5. It is configured as follows.

In the heat medium circulation path 2, a heat medium flow sensor 25 for detecting the flow rate of the heat medium C flowing through the heat medium circulation path 2, and a heat medium supplied to the heat exchanger for heat medium 23 from the engine cooling unit 6j. Heat medium return temperature sensor 26 that detects the temperature of C, and heat medium return temperature that detects the temperature of the heat medium C that returns from the heat medium heat exchanger 23 to the engine cooling unit 6j after passing through the heat medium storage tank 1 A sensor 27 is provided.
That is, from the heat medium C flowing through the heat medium circulation path 2 in the heat medium heat exchanger 23 based on the detection information of the heat medium flow rate sensor 25, the heat medium return temperature sensor 26, and the heat medium return temperature sensor 27. The amount of recovered heat recovered in the hot water H flowing through the hot water circulation path 21 can be obtained, and the recovered heat amount measuring means M is obtained by the heat medium flow rate sensor 25, the heat medium return temperature sensor 26, and the heat medium return temperature sensor 27. Will be configured.

A hot water supply passage 29 is connected to the top of the hot water storage tank 20 to extract hot water H in the hot water storage tank 20 and supply it to a heat load 28 such as a hot water supply destination. Hot water is extracted from the hot water supply passage 29 to the bottom of the hot water storage tank 20. Accordingly, a water supply passage 30 for supplying water to the hot water storage tank 20 is connected.
Although not shown in the figure, the hot water supply passage 29 is provided with an auxiliary heater such as a gas combustion type so as to compensate for the heat quantity that is insufficient with the heat quantity supplied by the hot water in the hot water storage tank 20 to the heat load 28.
Also, a load calorie measuring means for measuring the amount of heat consumed by the heat load 28 (load calorie) is provided.

The control operation of the operation control unit 4 will be described.
The operation control unit 4 is configured using a microcomputer, and is configured to control the operation of the cogeneration system by executing a predetermined program.
First, a control operation for controlling the engine 6 will be described.
Based on the measurement information of the load power consumed by the power load 11 and the measurement information of the load heat amount consumed by the thermal load 28, the operation control unit 4 performs the past time-series load power data and time-series data. It is configured to manage load heat quantity data and obtain time-series predicted load power data and time-series predicted load heat quantity data of an operation cycle such as one day based on the management data.
Then, the operation control unit 4 operates the operation plan of the generator 5 in the operation cycle so that the operation merit such as the energy reduction amount becomes high based on the time-series predicted load power data and the time-series predicted load heat amount data. And the planned operation for controlling the operation of the engine 6 to operate the generator 5 in the operation plan is executed. Incidentally, as an operation plan for the generator 5, for example, it is assumed that the output power of the generator 5 follows the time-series predicted load power data, and the operation time zone of the generator 5 in the operation cycle is determined.

Next, a control operation for controlling the operation of the heat medium supply state adjusting means A will be described.
In this embodiment, the heating medium supply state adjusting means A is constituted by a heating medium flow rate adjusting means V that can adjust the flow rate of the heating medium C flowing through the heating medium circulation path 2.
In this embodiment, the rotation speed of the heat medium circulation pump 3 is configured to be adjustable, and the flow rate of the heat medium C flowing through the heat medium circulation path 2 by adjusting the rotation speed of the heat medium circulation pump 3. The heat medium circulation pump 3 is configured to function as the heat medium flow rate adjusting means V.
Further, in this embodiment, the heat medium supply state adjusting means A is also configured to be a water replenishment intermittent valve 16 that is a heat medium component replenishment intermittent means that can intermittently replenish water W to the heat medium storage tank 1. Yes.

  The target heat amount is set in advance and stored in the memory of the operation control unit 4. In addition, when adjusting the flow rate of the heat medium C flowing through the heat medium circulation path 2 by the heat medium circulation pump 3, the upper limit flow rate and the adjustment flow rate during dilution less than the upper limit flow rate are set in advance to control the operation. It is stored in the memory of unit 4.

The operation control unit 4 first adjusts the flow rate of the heat medium circulating pump 3 so as to adjust the flow rate of the heat medium C so that the recovered heat amount measured by the recovered heat amount measuring means M becomes the target heat amount. Execute recovered heat control.
During the execution of the recovery heat amount control by this flow rate adjustment, with the passage of time, the concentration of ethylene glycol in the heating medium C increases, the specific heat of the heating medium C decreases, and the amount of heat carried by the heating medium per unit flow rate. Therefore, the flow rate of the heat medium C adjusted by the heat medium circulation pump 3 so that the recovered heat amount becomes the target heat amount increases with time.

  Then, the operation control unit 4 monitors the flow rate of the heat medium C detected by the heat medium flow sensor 25 during execution of the recovered heat amount control by adjusting the flow rate, and when the detected flow rate becomes equal to or higher than the upper limit flow rate, The rotational speed of the heat medium circulating pump 3 is decreased and adjusted so that the flow rate of the heat medium C detected by the flow rate sensor 25 becomes the adjustment flow rate at the time of dilution, and the water replenishment intermittent valve 16 is opened, and the recovered heat amount measuring means When the recovered heat amount measured by M reaches the target heat amount, the recovered heat amount control is executed by adjusting the concentration to close the water supply intermittent valve 16.

The operation controller 4 returns to the recovered heat amount control by the flow rate adjustment after executing the recovered heat amount control by the concentration adjustment, and thereafter repeatedly executes the recovered heat amount control by the flow rate adjustment and the recovered heat amount control by the concentration adjustment.
However, when the lower limit water level is detected by the lower limit water level sensor 17 during the execution of the recovered heat amount control by adjusting the flow rate, the operation control unit 4 does not supply the water supply intermittent valve 16 until the upper limit water level is detected by the upper limit water level sensor 18. The recovered heat amount control by adjusting the flow rate is executed while opening the valve and replenishing the heat medium storage tank 1 with water W.

Hereinafter, explanation will be given on how to set the target heat amount, the upper limit flow rate, and the adjustment flow rate during dilution.
The heat medium C is prepared so that the concentration of ethylene glycol becomes a set initial concentration (for example, 25%) at which the freezing of the heat medium C can be sufficiently suppressed, and the heat medium C thus prepared is used as an engine cooling unit. 6j, the heat exchanger 23 for the heat medium, and the heat medium circulation path 2 formed by the heat medium circulation path 2 so as to cover the heat medium storage tank 1, and are stored in the heat medium storage tank 1 at the upper limit water level. The

By the way, when comparing the vapor pressure of water and ethylene glycol, water is 23 hPa (20 ° C.), whereas ethylene glycol is 16 Pa (25 ° C.), and the vapor pressure of water is considerably larger than that of ethylene glycol. . Therefore, in the heat medium C containing water and ethylene glycol, water is much easier to evaporate than ethylene glycol.
In the heat medium storage tank 1 that is open to the atmosphere, assuming that water evaporates but ethylene glycol hardly evaporates, the amount of water evaporation increases with time, and the heat existing in the heat medium circulation path is increased. The concentration of ethylene glycol in the medium C increases.
Therefore, when the water supply intermittent valve 16 is opened and water is supplied to the heat medium storage tank 1 through the supply water path 15, the concentration of ethylene glycol in the heat medium C existing in the heat medium circulation path can be lowered.

Further, comparing the specific heat of water and ethylene glycol, at 20 ° C., the specific heat of ethylene glycol is 2348.37 J / kg · K (0.561 cal / g · ° C.), and the specific heat of water is 4186.05 J / kg · K (1 cal / g · ° C.) The specific heat of ethylene glycol is smaller than that of water.
That is, as the time passes, the concentration of ethylene glycol in the heating medium C existing in the heating medium circulation path increases, and the specific heat of the heating medium C decreases accordingly. In order to recover the amount of heat, it is necessary to increase the flow rate of the heat medium C flowing through the heat medium circuit 2.
In addition, when the heat medium C is diluted by reducing the concentration of ethylene glycol by replenishing the heat medium storage tank 1 with water W, the specific heat of the heat medium C increases. In collecting the amount of heat, the flow rate of the heat medium C flowing through the heat medium circuit 2 can be reduced.

As shown in FIG. 2, the flow rate (liter / min) of the heat medium C in the heat medium circuit 2, the ethylene glycol concentration (wt%) in the heat medium C, and the heat exchanger for the heat medium are shown by experiments in advance. 23, a relationship with the recovered heat quantity (W) recovered from the heat medium C into the hot water H is required.
As can be seen from FIG. 2, when the concentration of ethylene glycol in the heating medium C increases with time, the flow rate of the heating medium C needs to be increased in order to keep the recovered heat quantity constant.
It can also be seen that when the flow rate of the heat medium C is constant, the amount of recovered heat increases as the concentration of ethylene glycol in the heat medium C decreases.

And as shown in FIG. 2, the target calorie | heat amount is set to 1200W, for example.
The upper limit flow rate is within a range in which the flow rate of the heat medium circulation pump 3 can be adjusted, and the flow rate at which the recovered heat amount of the target heat amount can be obtained even if the ethylene glycol concentration is considerably higher than the set initial concentration, for example, 6. It is set to 0 liter / min.
Further, the adjustment flow rate at the time of dilution is set to a flow rate at which the target heat amount can be obtained by the heat medium C having an ethylene glycol concentration slightly higher than the set initial concentration (for example, 25%), for example, 4.0 liter / min.

Since the adjustment flow rate at the time of dilution is set as described above, when the recovery heat amount control by concentration adjustment is executed, the heat existing in the heat medium circulation path until the ethylene glycol concentration becomes a concentration close to the set initial concentration. The medium C is diluted.
Then, assuming that ethylene glycol hardly evaporates in the heat medium storage tank 1, and that the amount of ethylene glycol present in the heat medium circulation path is hardly changed, the lower limit water level is detected by the lower limit water level sensor 17, Even if the heat medium storage tank 1 is replenished with water W by performing the recovered heat amount control by adjusting the concentration, the concentration of ethylene glycol in the heat medium C existing in the heat medium circulation path is lower than the set initial concentration. Therefore, the ability to suppress the freezing of the heat medium hardly decreases.

[Another embodiment]
Next, another embodiment will be described.
(A) In the above embodiment, both the configuration in which the heating medium supply state adjusting means A is configured by the heating medium flow rate adjusting means V and the configuration in which the heating medium supply state adjusting means A is configured by the water replenishment intermittent valve 16. However, only one of them may be adopted.
When only the configuration in which the heating medium supply state adjusting unit A is configured by the heating medium flow rate adjusting unit V is adopted, when the flow rate of the heating medium C detected by the heating medium flow rate sensor 25 exceeds the upper limit flow rate, the upper limit water level is set. While performing the control to open the water supply intermittent valve 16 until the upper limit water level is detected by the sensor 18, the recovery heat amount control by the flow rate adjustment is executed.
Alternatively, it is possible to perform a recovery heat amount control by adjusting the flow rate, and to issue an alarm when the flow rate of the heat medium C detected by the heat medium flow rate sensor 25 exceeds the upper limit flow rate. In this case, when an alarm is issued, the water supply intermittent valve 16 is artificially opened to supply water W to the heat medium storage tank 1.
When only the configuration in which the heat medium supply state adjusting means A is constituted by the water replenishment intermittent valve 16 is adopted, the heat medium circulation pump so that the flow rate of the heat medium C in the heat medium circulation path 2 becomes a predetermined flow rate. 3, the concentration of ethylene glycol in the heating medium C is controlled by controlling the opening / closing operation of the water supply intermittent valve 16 so that the recovered heat amount measured by the recovered heat amount measuring means M becomes the target heat amount. Configure to adjust.

(B) Specific examples of the freezing point depressant constituting the heating medium C are not limited to the ethylene glycol exemplified in the above embodiment, and various types can be adopted. For example, propylene glycol, cellosolves, carbitols, lower alcohols and the like can be used.
In addition to water and a freezing point depressant, other components such as a rust inhibitor may be added to the heat medium C.

(C) Comparing the characteristics of water and the freezing point depressant, when the water has a higher vapor pressure and higher specific heat as in the above embodiment, the freezing point in the heating medium C is increased with time. Since the concentration of the depressant is increased and the specific heat of the heat medium C is lowered, the heat medium component replenishment intermittent means can freely replenish water to the heat medium storage tank 1, for example, as in the above embodiment. The water replenishment intermittent valve 16 is configured.
Conversely, when the freezing point depressant has a higher vapor pressure and larger specific heat, the concentration of the freezing point depressant in the heating medium C decreases with time and the specific heat of the heating medium C decreases. As the medium component replenishment intermittent means, the replenishment of the freezing point depressant to the heat medium storage tank 1 can be configured to be intermittent.

(D) The specific configuration of the heat medium flow rate adjusting means V is not limited to the case where the heat medium flow rate adjusting means V is configured by the heat medium circulation pump 3 whose rotation speed is adjustable as in the above embodiment. For example, a proportional valve capable of adjusting the flow rate of the heat medium C may be provided in the heat medium circulation path 2, and the heat medium flow rate adjusting means may be configured by this proportional valve.

(E) The specific configuration of the heat recovery unit R is not limited to the configuration illustrated in the above embodiment.
For example, a heat exchanger that exchanges heat between the heat medium C flowing through the heat medium circulation path 2 and a heat medium that is circulated and supplied to a heating terminal such as a floor heating device or a bathroom heating / drying device is provided to You may comprise so that the exhaust heat which generate | occur | produces in the generator G may be collect | recovered directly to the heat medium which circulates and supplies to a heating terminal.

(F) When the present invention is applied to a cogeneration system as in the above embodiment, the specific example of the exhaust heat generator G is limited to the engine 6 that drives the generator 5 illustrated in the above embodiment. For example, a fuel cell or a gas turbine that drives the generator 5 may be used.
In addition to the cogeneration system, the present invention can be applied to various exhaust heat recovery apparatuses including an engine that drives a heat pump, various combustion apparatuses, and the like as an exhaust heat generation apparatus.

  As described above, it is possible to provide an exhaust heat recovery device that can suppress a decrease in the amount of recovered heat over time.

1 Heat medium storage tank 2 Heat medium circulation path 3 Heat medium circulation pump (heat medium circulation means)
5 Generator 6 Engine 7 Control means 16 Water supply intermittent valve (heat medium component supply intermittent means)
A Heat medium supply state adjusting means C Heat medium G Waste heat generator M Recovered heat amount measuring means R Heat recovery section V Heat medium flow rate adjusting means W Water

Claims (4)

A heat medium circulation path that circulates the heat medium via an exhaust heat generator, a heat recovery unit, an open air type heat medium storage tank,
A heat medium circulating means for circulating the heat medium through the heat medium circulation path in order to recover the exhaust heat generated in the exhaust heat generator via the heat medium in the heat recovery unit;
The heat medium is an exhaust heat recovery device that includes water and a freezing point depressant for lowering the freezing point of the heat medium,
A heat medium supply state adjusting means capable of adjusting a supply state of the heat medium supplied to the heat recovery unit;
Recovered heat amount measuring means for measuring the recovered heat amount recovered from the heat medium in the heat recovery unit,
An exhaust heat recovery apparatus provided with control means for controlling the operation of the heating medium supply state adjusting means so that the recovered heat quantity becomes a target heat quantity based on the measurement information of the recovered heat quantity measuring means.   The exhaust heat recovery apparatus according to claim 1, wherein the heat medium supply state adjusting unit includes a heat medium flow rate adjusting unit capable of adjusting a flow rate of the heat medium flowing through the heat medium circulation path.   The exhaust heat recovery according to claim 1 or 2, wherein the heating medium supply state adjusting means is constituted by a heating medium component replenishment intermittent means capable of intermittently supplying water or a freezing point depressant to the heat medium storage tank. apparatus.   The exhaust heat recovery apparatus according to any one of claims 1 to 3, wherein the exhaust heat generation apparatus is an engine that drives a generator.

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