JP5086947B2 - Type 2 absorption heat pump system - Google Patents

Description

  The present invention relates to a steam generation technique using an exhaust heat pump, and more specifically, an evaporator that heats a refrigerant liquid to generate refrigerant vapor, and an absorption solution that absorbs the refrigerant vapor generated in the evaporator. An absorber that heats the medium to be heated with absorption heat, a diluted solution that has absorbed the refrigerant vapor generated in the evaporator and has a reduced concentration, and the diluted solution is heated. A regenerator for evaporating a refrigerant to produce a concentrated solution having a higher concentration than the dilute solution; a condenser for introducing a refrigerant vapor evaporated in the regenerator and condensing to produce a refrigerant liquid to be supplied to the evaporator; And a second type absorption heat pump system in which the temperature of the medium to be heated is higher than the temperature of a heating heat source for obtaining a concentrated solution in the regenerator.

  It has been widely practiced to generate electricity with a prime mover such as a gas engine or a diesel engine and obtain steam by the exhaust heat. As a utilization form of such exhaust heat, conventionally, exhaust gas generated from a prime mover has been guided to a steam boiler to obtain steam and utilize the exhaust heat. Recently, there is a lot of research to obtain steam by using a second-type absorption heat pump as it is or after exchanging heat with exhaust gas as jacket water (an example of a heating medium as a heating heat source). (Non-Patent Document 1).

FIG. 3 shows the configuration of the second-type absorption heat pump, and FIG. 4 shows a lithium bromide-water Duling diagram.
The circled numbers on the Dueling diagram of FIG. 4 correspond to the numbers on the system of FIG.
As shown in FIG. 3, the second type heat pump includes an evaporator 1 that heats the refrigerant liquid and generates refrigerant vapor, and an absorption solution that absorbs the refrigerant vapor generated in the evaporator 1 by the absorbing solution. An absorber 2 for heating the heating medium and a diluted solution having a reduced concentration by absorbing the refrigerant vapor generated in the evaporator 1 are introduced, and the diluted solution is heated so that the refrigerant in the diluted solution is reduced. A regenerator 3 that generates a concentrated solution having a higher concentration than the dilute solution by evaporation, and a condenser that generates a refrigerant liquid that is introduced and condensed by the refrigerant vapor evaporated in the regenerator 3 to be supplied to the evaporator 1 4.

  In FIG. 3, the pressure P′H of the evaporator 1 and the absorber 2 is higher than the pressure P′L of the regenerator 3 and the condenser 4. This is the opposite of the absorption refrigerator. The principle will be briefly described. In the regenerator 3, water as a refrigerant is separated by jacket water as a heating heat source and condensed in the condenser 4. The condensed water is pressurized and sent to the evaporator 1, and is evaporated with the jacket water after heat is used in the regenerator 3. The evaporated water is absorbed in the LIBr concentrated solution, which is the solution sent from the regenerator 3 in the absorber 2, and the temperature rises due to the heat of absorption. If the heat is recovered from the absorber 2 to the medium to be heated, a heat output at a temperature higher than that of the jacket water can be obtained, whereby steam can be obtained. The solution that has absorbed the vapor by the absorber 2 is returned to the regenerator 3 after decompression and the cycle is repeated.

Now, the rough temperature of each part is shown on the Dueling diagram shown in FIG. 4. The temperature of the regenerator 3 and the evaporator 1 is determined by the jacket water temperature Tj, and the temperature of the condenser 4 is the temperature of the cooling water Tc. It depends on.
If the temperature of the regenerator 3 and the evaporator 1 is 85 ° C. and the temperature of the condenser 4 is 35 ° C., the maximum temperature Td obtained by the absorber 2 is about 142 ° C. as shown in FIG. Steam with a pressure of about 0.3 MPa (saturation temperature of 133.54 ° C.) can be taken out.

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However, it is difficult to take out steam having a demand of 0.4 MPa (saturation temperature 143.62 ° C.) or more.
In order to take out this level of vapor, the temperature of the absorber 2 must be 150 ° C. or higher.
As a technique for this purpose, there is a method of increasing the jacket water temperature (in the example shown in FIG. 5, the temperature is increased to 90 ° C.). There is also a method in which the absorption heat pump is double connected and the second absorption heat pump is heated with the heat raised by the first absorption heat pump. However, the former is often constrained by the design conditions on the engine side, and in the latter, COP is multiplied by COP of each cycle, and is significantly reduced.

On the other hand, if these are difficult, the cooling water temperature may be lowered to lower the condensation pressure. In this case, the condenser temperature needs to be lowered to about 30 ° C. For this purpose, if the temperature difference Δt between the temperature of the condenser 4 and the temperature of the cooling water is 5 ° C., cooling water of about 25 ° C. is required. However, when using a cooling tower that exchanges heat with the atmosphere, this temperature is often exceeded during the summer peak. For example, the month average daytime maximum temperature in August in Osaka Prefecture is 32 ° C., the average temperature is 26 ° C., and the month average daytime minimum temperature is about 22 ° C. Therefore, it is impossible to use the cooling water obtained by the cooling tower as the cooling water (low-temperature cooling medium) of the second type absorption heat pump in consideration of the year-round operation.
This invention is made | formed in view of said subject, The objective is to obtain the 2nd type absorption heat pump system which can ensure the stable driving | running state over the whole year.

An evaporator that heats the refrigerant liquid according to the present invention to achieve the above object and generates refrigerant vapor;
An absorber that heats the medium to be heated with absorption heat when the absorbing solution absorbs the refrigerant vapor generated in the evaporator;
By introducing a dilute solution having a low concentration by absorbing the refrigerant vapor generated in the evaporator, and heating the dilute solution, the refrigerant in the dilute solution is evaporated to have a higher concentration than the dilute solution. A regenerator for producing a concentrated solution;
A refrigerant vapor that is introduced and condensed in the regenerator to generate a refrigerant liquid to be supplied to the evaporator,
The first characteristic configuration of the second type absorption heat pump system in which the temperature of the heated medium obtains a heat output higher than the temperature of a heating heat source for obtaining a concentrated solution in the regenerator,
The cooling medium of the condenser circulates, and includes an atmosphere side heat exchanger that can exchange heat with the atmosphere, and a ground side heat exchanger that can exchange heat with the ground,
When the atmospheric temperature is lower than the required cooling medium temperature, which is the temperature of the cooling medium determined according to the temperature required for the heated medium, the cooling medium is transferred to the atmosphere-side heat exchanger in the ground at a temperature lower than the atmospheric temperature. And a first coolant circulation control means for radiating the cooling medium via the underground heat exchanger when the atmospheric temperature is higher than the required cooling medium temperature.

  First, the operation state on the heat pump side will be described with reference to the Dueling diagram shown in FIG. 2. By reducing the temperature of the cooling medium introduced into the condenser 4, the pressure PL of the condenser 4 and the regenerator 3 is reduced. (In the example shown in the figure, an example in which the condensation temperature Tc of the refrigerant in the condenser is lowered from 35 ° C. to 30 ° C. is shown), and the temperature of the heat output that can be obtained by the absorber 2 Td can be increased (in the example shown, an example in which the temperature is increased from 142 ° C. to 154 ° C. is shown), and as a result, the target steam around 140 ° C. is obtained by using a heated medium. Can do. In this case, the temperature of the cooling medium introduced into the condenser needs to be 25 ° C. or lower.

  Now, it is a technique according to the present application for obtaining such a cooling medium temperature (maximum 25 ° C.). In the present application, the first cooling medium circulation control means is provided, and is determined according to the temperature required for the heated medium. In a situation where the atmospheric temperature is lower than the required cooling medium temperature (25 ° C. in the example described above), which is the temperature of the cooling medium, the cooling medium is radiated through the atmosphere-side heat exchanger, and the atmospheric temperature is increased from the required cooling medium temperature. In a situation where the temperature is high, the cooling medium is dissipated through the underground heat exchanger.

  As is well known, the underground temperature is close to the annual average temperature, and is generally about 15 to 20 ° C. On the other hand, the atmospheric temperature is often 25 ° C. or lower except on summer days, but may be higher than 25 ° C. on summer days.

Therefore, in the present application, in a normal state, the heat of the cooling medium is radiated to the atmosphere via the atmosphere-side heat exchanger, and when the atmospheric temperature becomes higher than the required cooling medium temperature, the temperature is maintained below this temperature. The heat of the cooling medium is released into the ground.
As a result, while installing a common atmosphere side heat exchanger, for example, by adopting a configuration that radiates heat to the ground only on high temperature days such as midsummer days, even if a relatively small underground heat exchanger is adopted, A stable operation state can be secured throughout the year.

And, in this application, the air side is mainly used for obtaining cold heat, and the ground side is used only when the air side cannot be operated satisfactorily. A system that can be operated satisfactorily throughout the year while being used can be easily obtained.
In the second feature configuration of the second type absorption heat pump system according to the present invention, in addition to the first feature configuration, the cooling medium circulates between the atmosphere side heat exchanger and the underground side heat exchanger. The atmospheric temperature is lower than the underground temperature, the cooling medium circulates between the atmospheric heat exchanger and the underground heat exchanger, and cools from the atmosphere side to the underground side. A second cooling medium circulation control unit that circulates the cooling medium between the atmosphere-side heat exchanger and the underground-side heat exchanger in a state where the underground cooling is possible.

According to the second characteristic configuration, the atmospheric temperature is lower than the underground temperature by the action of the second coolant circulation control means, and the gap between the atmospheric heat exchanger and the underground heat exchanger is The cooling medium is circulated between the atmosphere-side heat exchanger and the underground-side heat exchanger in a ground-coolable state in which the cooling medium circulates and can transfer cold heat from the atmosphere side to the underground side. .
That is, the second cooling medium circulating means, when the atmospheric temperature (atmospheric wet bulb temperature) is lower than the underground temperature, by reducing the increased underground temperature to recover, A small-scale underground heat exchanger can be used effectively, leading to further cost reduction.

  In the third characteristic configuration of the second type absorption heat pump system according to the present invention, in addition to the first or second characteristic configuration, the solution in the regenerator is in a crystal generation state in which crystals are generated in the solution. It is in the point provided with the crystal generation state suppression means to suppress.

According to the third characteristic configuration, the generation of crystals in the regenerator can be suppressed, and a good operation state can be maintained.
More specifically, like the fifth feature configuration of the present application,
When the refrigerant is water and the absorbing solution is an aqueous lithium bromide solution,
The crystal generation state suppressing means is
Measure the pressure of the regenerator or measure the temperature of the condenser to calculate the condensing pressure that is the pressure of the regenerator,
Control is made to maintain the regenerator temperature below the crystal onset temperature determined as a function of the regenerator pressure.

When cooling the condenser using a low-temperature cooling medium as in the present application, it should be noted that if the cooling is excessive, the LiBr crystal line (see FIG. 2) is reached, and the solution is crystallized. It is to become.
Therefore, the lower right position (indicated by the number 3 with a numbered circle) of the cycle shown in FIG. 2 described above (indicated by a thick solid line in the figure) is always at the upper left of the crystal line (indicated by a thick one-dot chain line in the figure). Control to come. In this control, if the pressure of the regenerator 3 is known, the temperature of the crystal line is known. Therefore, if the temperature at the position indicated by the circled number 3 is likely to be higher than the temperature of the crystal line at that pressure, the temperature rises. Is suppressed. Regarding this suppression, for example, the temperature of the cooling medium supplied to the condenser is increased or the amount of the cooling medium is decreased to increase the pressure of the condenser and the regenerator, thereby suppressing the increase in the regenerator temperature. Can do. In this way, a good operating state can be maintained.
Here, the pressure of the regenerator may be measured directly, but since the pressure of the regenerator is equal to the condensing pressure of the condenser, it can be obtained indirectly by measuring the temperature of the condenser. A suppression means can be realized.

  The fourth characteristic configuration of the second type absorption heat pump system according to the present invention includes, in addition to the first to third characteristic configurations, the heating medium of the regenerator after the heating of the dilute solution in the regenerator, The heating medium before being introduced into the regenerator is warm water in the range of 80 ° C. to 95 ° C., which is sent to the evaporator and used to heat the evaporation of the refrigerant in the evaporator.

Once the heat is recovered, the heat stored in the hot water in the range of 80 ° C. to 95 ° C., which has not been conventionally used and often discarded, can be efficiently recovered and used.
From the above, it is possible to satisfactorily extract about 0.4 MPa of steam with a hot water driven second type absorption heat pump at 80 to 95 ° C. while suppressing costs.

  Hereinafter, the second kind absorption heat pump system 100 of this application is explained based on a drawing. FIG. 1 is a diagram illustrating a configuration of a second type absorption heat pump system 100 according to the present application, and FIG. 2 is a Düring diagram corresponding to an operating state of the second type absorption heat pump system 100.

The second type absorption heat pump system 100 according to the present application includes an absorption heat pump 5 including an evaporator 1, an absorber 2, a regenerator 3, and a condenser 4, and a condensing heat recovered by the condenser 4 as a cooling medium (specifically Is a cooling tower 6 having an atmosphere side heat exchanger 6a for releasing to the atmosphere via the cooling water c0, and a ground side heat exchange for releasing the condensation heat to the ground 7 via the cooling medium c0. And a control device 8 for determining the circulation path L (L1, L2) of the cooling medium c0 as main equipment.
Hereinafter, it demonstrates in order.

Second-type absorption heat pump This second-type absorption heat pump 5 includes an evaporator 1 that heats a refrigerant liquid w (a refrigerant c in a liquid state) to generate refrigerant vapor v, and an absorption solution d that is generated in the evaporator 1. An absorber 2 that heats the medium h to be heated with absorption heat when absorbing the generated refrigerant vapor v, and a dilute solution d1 that has absorbed the refrigerant vapor v generated in the evaporator 1 and has a reduced concentration, By heating the diluted solution d1, the refrigerant in the diluted solution is evaporated to generate a concentrated solution d2 having a higher concentration than the diluted solution, and the refrigerant vapor v evaporated in the regenerator 3 is And a condenser 4 that generates a refrigerant liquid w that is introduced, condensed, and supplied to the evaporator 1. Specifically, the refrigerant c is water, and the absorbing solution d is a lithium bromide aqueous solution.

  The heat source and heat output of the second type heat pump 5 according to the present application will be described. As shown in FIG. 1, hot water as a heating heat source (sometimes referred to as a low temperature heat source) that is jacket water for the engine 9 or the like flows. A flow path 10 is provided from the regenerator 3 to the evaporator 1. Therefore, the heat retained by the hot water is used for regeneration of the absorbing solution d in the regenerator 3 (regeneration from a dilute solution to a concentrated solution) and for the evaporation of the refrigerant c in the evaporator 1. As a result, the low temperature heat is recovered from the hot water that is the low temperature heat source. Specifically, the jacket water undergoes heat recovery on the high temperature side (higher than 95 ° C.), and is 80 ° C. to 95 ° C. when introduced into the regenerator 3 according to the present application.

  On the other hand, the condenser 4 is provided with a condensation heat exchanger 4a into which cooling water as the cooling medium c0 cooled in the cooling tower 6 or cooled in the ground is introduced. Therefore, the refrigerant vapor v led to the condenser 4 is condensed by the cold heat held by the cooling water. In other words, the temperature of the refrigerant vapor v is recovered in the condenser 4, and when it is sent to the cooling tower 6, it is discharged to the atmosphere via the atmosphere-side heat exchanger 6 a, and when it is sent to the ground 7, It is discharged into the ground through the heat exchanger 7a. Here, the underground heat exchanger 7a is a U-shaped tube buried in the ground in the illustrated example. However, the underground heat exchanger may have other forms such as a slinky.

  Then, the absorbing solution d is regenerated by the regenerator 3 (regenerated by the heat obtained from the low-temperature heat source to become the concentrated solution d2 from the dilute solution d1) and the absorber 2 (absorbs the refrigerant and becomes the diluted solution d1 from the concentrated solution d2). The refrigerant c is circulated through the regenerator 3, the condenser 4, the evaporator 1 and the absorber 2 with a phase change.

  Therefore, in the absorber 2, the concentrated solution d <b> 2 sent from the regenerator 3 is separately evaporated in the evaporator 1 and absorbs the refrigerant vapor v sent to the absorber 2. The heat generated at the time of absorption can be recovered by the medium to be heated h through the heat exchanger 2a provided in the absorber 2 to obtain a heat output. The temperature of the heated medium h can be higher than the temperature of the low-temperature heat source.

The above is the description regarding the configuration and operation of the second type absorption heat pump 5, but hereinafter, the cooling and cooling of the cooling water used to recover the condensation heat in the condenser 4 will be described.
As described above, the condensation heat exchanger 4a provided in the condenser 4 and the atmospheric heat exchanger 6a provided in the cooling tower 6 or the ground side of the condensation heat exchanger 4a and the underground 7 Cooling water is circulated between the heat exchanger 7a.

The first circulation path indicated by L1 in FIG. 1 is a circulation path (indicated by a broken line arrow) that is used in an atmosphere-side release circulation state that releases condensation heat to the atmosphere side, and the second circulation path indicated by L2 in FIG. 1 is condensed. It is a circulation path (indicated by a solid line arrow) used in a ground side discharge circulation state for releasing heat to the ground side.
Furthermore, the second type absorption heat pump system 100 according to the present application is capable of forming a third circulation path that circulates between the atmosphere-side heat exchanger 6a and the underground-side heat exchanger 7a, although illustration is omitted. In the state where this third circulation path is formed, the underground temperature can be lowered by circulating the cooling water generated in the cooling tower 6 in the ground while the atmospheric temperature is lower than the underground temperature. As for the circulation of the cooling water between the atmosphere side heat exchanger 6a and the underground side heat exchanger 7a, the circuit of FIG. 1 may be used as it is when the heat pump is stopped, or in the vicinity of the underground side heat exchanger 7a. You may cope with it by providing the tube for cooling (for example, double U tube).

The above is the description of the cooling water circulation system of the condenser 4. Hereinafter, the usage mode of these circulation paths will be described.
As shown in FIG. 1, the second type absorption heat pump system 100 includes a control device 8, and the control device 8 includes a first cooling medium circulation control unit 8 a, a second cooling medium circulation control unit 8 b, and It is comprised so that the crystal generation state suppression means 8c may be comprised.
The first cooling medium circulation control means 8a radiates the cooling medium via the atmosphere-side heat exchanger 6a when the atmospheric temperature is lower than the required cooling medium temperature, which is the temperature of the cooling medium determined according to the temperature required for the heated medium. When the atmospheric temperature is higher than the required cooling medium temperature, the cooling medium is radiated through the underground heat exchanger 7a.

Here, the required cooling medium temperature is the temperature of the cooling medium c0 determined according to the temperature required for the heated medium h. For example, as shown in FIG. 2, the temperature Td required for the heated medium h is 154 ° C. In some cases, the condenser temperature Tc is about 30 ° C., and the temperature required for the cooling medium is 25 ° C.
Then, the first cooling medium circulation control means 8a circulates the cooling medium c0 through the first circulation path L1 when the atmospheric temperature is lower than the required cooling medium temperature, and the condensation heat passes through the atmospheric heat exchanger 6a. Dissipate heat. On the other hand, when the atmospheric temperature is higher than the required cooling medium temperature, the cooling medium c0 is circulated through the second circulation path L2, and the condensed heat is dissipated through the underground heat exchanger 7a.
As a result, the second type absorption heat pump system can be operated satisfactorily while maintaining the temperature of the cooling medium c0 below the required cooling medium temperature.

  Further, the second cooling medium circulation control means 8b is configured to cause the atmospheric temperature to fall below the ground temperature and to circulate the cooling medium between the atmospheric heat exchanger 6a and the underground heat exchanger 7a. In the ground-coolable state where cold heat can be transferred from the ground to the ground side, the cooling medium is circulated between the atmosphere-side heat exchanger 6a and the ground-side heat exchanger 7a. That is, a 3rd circulation path is formed, a cooling medium is circulated between both the heat exchangers 6a and 7a, and the inside is cooled with the cold heat which air | atmosphere has. Here, the atmospheric temperature is specifically the atmospheric wet bulb temperature because the atmospheric heat exchanger 6a provided in the cooling tower 6 is used. Thus, in the situation where the underground can be cooled from the atmosphere side, the underground side heat exchanger 7a can be downsized by cooling the underground.

The crystal generation state suppressing means 8c functions to suppress the state of the solution in the regenerator 3 from becoming a crystal generation state in which crystals are generated in the solution. More specifically, the crystal generation suppressing means 8c is a condenser that obtains a condensation pressure equal to the regenerator pressure from the measurement result of the measurement mechanism that measures the pressure of the regenerator 3 or the measurement mechanism that measures the temperature of the condenser 4. Pressure deriving means 8d is provided, and the temperature or flow rate of the cooling water supplied to the condenser 4 is controlled so as to maintain the regenerator temperature from the obtained regenerator pressure below the crystal start temperature determined as a function of the regenerator pressure. . At this time, the regenerator temperature is monitored in advance and, for example, the temperature of the cooling water supplied to the condenser 4 is increased while the regenerator temperature is approaching the crystal start temperature in the temperature rising state, or By reducing the amount of water while maintaining the same temperature and increasing the regenerator pressure, the regenerator temperature can be maintained below the crystal start temperature.
By managing the regenerator temperature in this way, the system can be operated and maintained satisfactorily without causing crystallization.

  Throughout the year, a second type absorption heat pump system capable of ensuring a stable operation state could be obtained.

The figure which shows the structure of the 2nd kind absorption heat pump system which concerns on this application Dueling diagram in the operating state of the second type absorption sheet pump according to the present application The figure which shows the structure of the conventional 2nd type absorption heat pump Dueling diagram in the operating state of the conventional second type absorption sheet pump Dueling diagram when the heat source temperature is increased to obtain a high heat output.

Explanation of symbols

1: Evaporator 2: Absorber 3: Regenerator 4: Condenser 4a: Condenser heat exchanger 6: Cooling tower 6a: Atmospheric heat exchanger 7: Underground 7a: Underground heat exchanger 8: Controller 8a : First cooling medium circulation control means 8b: second cooling medium circulation control means 8c: crystal generation state suppression means

Claims (5)

An evaporator that heats the refrigerant liquid to generate refrigerant vapor;
An absorber that heats the medium to be heated with absorption heat when the absorbing solution absorbs the refrigerant vapor generated in the evaporator;
By introducing a dilute solution having a low concentration by absorbing the refrigerant vapor generated in the evaporator, and heating the dilute solution, the refrigerant in the dilute solution is evaporated to have a higher concentration than the dilute solution. A regenerator for producing a concentrated solution;
A refrigerant vapor that is introduced and condensed in the regenerator to generate a refrigerant liquid to be supplied to the evaporator,
A second type absorption heat pump system in which a temperature of the medium to be heated is higher than a temperature of a heating heat source for obtaining a concentrated solution in the regenerator,
The cooling medium of the condenser circulates, and includes an atmosphere side heat exchanger that can exchange heat with the atmosphere, and a ground side heat exchanger that can exchange heat with the ground,
When the atmospheric temperature is lower than the required cooling medium temperature, which is the temperature of the cooling medium determined according to the temperature required for the heated medium, the cooling medium is radiated through the atmospheric heat exchanger, and the required cooling medium temperature A second type absorption heat pump comprising first cooling medium circulation control means for radiating the cooling medium through the underground heat exchanger in the ground at a lower temperature than the atmospheric temperature when the atmospheric temperature is higher system.   Between the atmosphere side heat exchanger and the underground heat exchanger, the cooling medium is configured to be circulated, and the atmospheric temperature is lower than the underground temperature, and the atmosphere side heat exchanger and the underground are The cooling medium is circulated between the side heat exchanger and the cooling medium can be cooled from the atmosphere side to the ground side. The second kind absorption heat pump system according to claim 1 provided with the 2nd cooling medium circulation control means circulated between heat exchangers.   3. The second type absorption heat pump system according to claim 1, further comprising a crystal generation state suppressing unit that suppresses the solution in the regenerator from entering a crystal generation state where crystals are generated in the solution. After heating the dilute solution in the regenerator, the heating medium of the regenerator is sent to the evaporator, and used in the evaporator to generate the refrigerant evaporation.
The second type absorption heat pump system according to any one of claims 1 to 3, wherein the heating medium before introduction of the regenerator is warm water in a range of 80C to 95C. The refrigerant is water and the absorbing solution is an aqueous lithium bromide solution;
The crystal generation state suppressing means is
Measure the pressure of the regenerator, or measure the temperature of the condenser to obtain the pressure of the regenerator which is the condensation pressure,
The second type absorption heat pump system of claim 3, wherein the regenerator temperature is maintained below a crystal start temperature determined as a function of the pressure of the regenerator.

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