JP6372126B2 - Heat transport equipment - Google Patents

Description

  The present invention relates to a heat transport device.

  Conventionally, it is a chemical heat storage system using ammonia, a heat exchange type heat storage reactor in which a metal chloride type chemical heat storage material is enclosed, a heat exchange type adsorber in which an adsorbent is enclosed as an ammonia buffer, and two of them. A heat transport device characterized by a configuration in which a reactor is connected by ammonia piping is known (Patent Document 1). In this heat transport device, heat storage is possible by supplying exhaust heat to the reactor while adjusting the temperature of the adsorber to a constant temperature, and maintaining the heat storage state by closing the valve in the ammonia piping. Can do. Further, by opening the valve at an arbitrary timing, the stored heat can be radiated and effectively used as a heat source.

JP 2012-172900 A

  In the heat transport device described in Patent Document 1, it is possible to start under freezing, and to store and dissipate heat from a low temperature to a medium temperature (about 80 ° C to 300 ° C). However, the construction of a chemical heat storage system capable of raising the temperature to a temperature higher than the exhaust heat (heat storage) temperature has become a problem. Cannot be realized in principle.

  This invention is made | formed in view of the above, and makes it a subject to achieve the following objectives.

  That is, an object of the present invention is to provide a heat transport device having a large temperature rise width and excellent heat transport properties.

  The heat transport device according to the present invention stores an adsorbent or heat storage material that stores heat when ammonia is desorbed and dissipates heat when ammonia is adsorbed, and exchanges heat with the adsorbent or heat storage material. Two or more reactors having a heat medium flow path through which a heat medium that circulates, wherein at least one of the two or more reactors stores heat when ammonia is desorbed and physically adsorbs ammonia. A reactor containing an adsorbent containing a physical adsorbent that dissipates heat when adsorbed by an ammonia, an ammonia pipe connecting the two or more reactors and flowing ammonia between the two or more reactors; A temperature adjusting mechanism capable of switching a plurality of types of heat media having different temperatures to be supplied to a heat medium flow path of a reactor in which an adsorbent containing the physical adsorbent is housed, and between the two or more reactors Ammonia pressure generated in For transporting heat by transporting from one to the other of ammonia by utilizing the difference.

  In the heat transport device according to the present invention, heat is transported between two or more reactors along with transport of ammonia vapor having a high vapor pressure, so that pressure loss due to the flow of ammonia vapor in the pipe is suppressed, and as a result, , Heat transportability is improved. That is, according to the heat transport apparatus of the present invention, the heat given to one reactor can be efficiently transported to the other reactor.

  Further, in the heat transport device of the present invention, a plurality of types of heat medium having different temperatures are switched and supplied to the heat medium flow path of the reactor in which the adsorbent containing the physical adsorbent is accommodated by the temperature adjustment mechanism, Since the temperature of the heat medium flow path of the reactor containing the adsorbent containing the physical adsorbent is increased, the temperature rise range can be improved.

  Thus, according to the heat transport apparatus of the present invention, it is possible to provide a heat transport apparatus having a large temperature rise width and excellent heat transportability.

  The heat transport device of the present invention supplies a heat medium having a low temperature among the plurality of types of heat medium when ammonia is adsorbed to the adsorbent of the reactor containing the adsorbent containing the physical adsorbent. The temperature adjustment mechanism is controlled so that when ammonia is desorbed from the adsorbent of the reactor containing the adsorbent containing the physical adsorbent, the heat of the plurality of types of heat medium is high. The apparatus may further include a controller that controls the temperature adjustment mechanism to supply the medium. In this way, the temperature of other reactors is increased by increasing the ammonia operating pressure by heating when ammonia is desorbed from the adsorbent of the reactor containing the adsorbent containing the physical adsorbent. It is possible to improve the speed and the temperature increase range.

  In the heat transport apparatus of the present invention, the heat medium flow path of the reactor in which the adsorbent containing the physical adsorbent is accommodated condenses the supplied heat medium and holds the condensed heat medium Can be provided. As a result, the reactor containing the adsorbent containing the physical adsorbent can be subjected to latent heat cooling below the temperature of the heat medium having a low temperature, and the operation of the reactor containing the adsorbent containing the physical adsorbent is enabled. By reducing the ammonia pressure, the reactor can quickly store heat even with a lower temperature heat source.

  The heat medium holding mechanism can hold the heat medium by utilizing the surface tension of the condensed heat medium.

  The heat medium holding mechanism can hold the condensed heat medium using gravity.

  The temperature adjusting mechanism may supply a low boiling point refrigerant as a heat medium having a high temperature among the plurality of types of heat medium.

  Said temperature control mechanism can supply methanol, ethanol, or water as said low boiling-point refrigerant | coolant.

  The heat transport apparatus of the present invention can further include a condenser capable of recovering the low-boiling-point refrigerant supplied to the heat medium flow path of the reactor in which the adsorbent containing the physical adsorbent is stored. .

  The heat transport device of the present invention further includes an evaporator for evaporating the low boiling point refrigerant, and the temperature adjusting mechanism stores the low boiling point refrigerant supplied from the evaporator in an adsorbent containing the physical adsorbent. It can be made to supply to the heat carrier flow path of the made reactor.

  The temperature adjusting mechanism can supply air as a heat medium having a low temperature among the plurality of types of heat medium.

  In the heat transport device of the present invention, a valve is provided in the ammonia pipe, and the difference in ammonia pressure can be adjusted by opening and closing the valve. Thereby, since the difference in ammonia pressure can be more effectively maintained, the heat transportability can be further improved. That is, by closing the valve, the difference in ammonia pressure can be maintained for a long time, and by opening the valve, ammonia can be transported and the stored heat can be used efficiently.

  The two or more reactors are arranged between two or more reaction chambers in which the adsorbent or heat storage material is stored and at least the reaction chamber, and heat exchanges between the adsorbent or heat storage material. A heat medium flow path through which the medium flows. This enables efficient heat exchange between the heat medium and the adsorbent or heat storage material, improving the contact thermal resistance at the contact surface (heat transfer surface) between the reaction chamber wall and the adsorbent or heat storage material. Is done.

  Here, the two or more reactors may have two or more reaction chambers and two or more heat medium channels, and the reaction chambers and the heat medium channels may be alternately arranged. More preferred.

  At least one of the two or more reactors stores a heat storage material including a chemical heat storage material that stores heat when ammonia is desorbed and releases heat when ammonia is immobilized by a coordination reaction. It is. Thereby, since the heat storage density in the reactor in which the heat storage material containing a chemical heat storage material is accommodated can be further improved, the heat storage density in the entire heat transport device can be further improved.

  Also, a chemical heat storage material having a large amount of heat required for immobilization and desorption of ammonia compared to a physical adsorbent, and a property of a small amount of heat required for adsorption and desorption of ammonia compared to a chemical heat storage material A physical adsorbent. For this reason, a large heat output can be obtained with a small heat input by utilizing the difference in the amount of heat required for the adsorption and desorption of ammonia.

  In the heat transport device, the chemical heat storage material is a metal halide. Thereby, since the heat storage density in the reactor in which the heat storage material containing a chemical heat storage material is accommodated can be further improved, the heat storage density in the entire heat transport device can be further improved.

  In the above heat transport apparatus, the metal halide comprises an alkali metal chloride, bromide, iodide, alkaline earth metal chloride, bromide, iodide, and transition metal chloride, bromide, iodide. At least one selected from the group. Thereby, since the heat storage density in the reactor in which the heat storage material containing a chemical heat storage material is accommodated can be further improved, the heat storage density in the entire heat transport device can be further improved.

  In the above heat transport apparatus, the physical adsorbent is at least one selected from the group consisting of activated carbon, mesoporous silica, zeolite, silica gel, and clay mineral. Thereby, in the reactor in which the adsorbent containing the physical adsorbent is accommodated, the amount of heat required for adsorption and desorption of ammonia can be further reduced, so that the controllability of heat transport in the entire heat transport apparatus is further improved be able to.

  In the heat transport apparatus, a pressure adjusting means is further provided in the ammonia pipe. Thereby, since the difference of ammonia pressure can be produced more effectively, heat transportability can be improved more.

  ADVANTAGE OF THE INVENTION According to this invention, the heat transport apparatus excellent in heat transport property which enlarged the temperature rising range can be provided.

It is the figure which showed typically the NH3 storage and transport device which concerns on 1st Embodiment of this invention. It is the figure which showed typically the 1st heat exchange type reactor and 2nd heat exchange type reactor which concern on embodiment of this invention. It is the figure which showed typically the reactor which concerns on another embodiment of this invention. It is the figure which showed typically the reactor which concerns on another embodiment of this invention. It is a figure which shows the liquid holding | maintenance mechanism of a 1st heat exchange type | mold reactor. It is a figure for demonstrating the thermal radiation mode. It is a figure which shows a mode that a heat medium is hold | maintained in the liquid holding | maintenance mechanism of a 1st heat exchange type | mold reactor. It is a figure for demonstrating heat storage mode. It is a figure which shows a mode that latent heat cooling is performed by the liquid holding | maintenance mechanism of a 1st heat exchange type | mold reactor. It is a graph showing the relationship between ammonia pressure and ammonia adsorption amount which shows the temperature dependence in the physical adsorption material of a 1st heat exchange type | mold reactor. 4 is a graph showing the relationship between ammonia pressure and equilibrium temperature in the chemical heat storage material of the second heat exchange reactor 30. It is a flowchart which shows the thermal radiation thermal storage cycle control routine of 1st Embodiment of this invention. It is the figure which showed typically the NH3 storage / transport device which concerns on 2nd Embodiment of this invention. It is the figure which showed typically the 1st heat exchange type reactor and 2nd heat exchange type reactor which concern on another embodiment of this invention.

  Hereinafter, in the embodiment of the present invention, a case where the heat transport apparatus of the present invention is applied to an NH3 storage / transport device will be described as an example.

(First embodiment)
A first embodiment of the NH3 storage / transport device of the present invention will be described with reference to FIGS. In this embodiment, activated carbon is used as a physical adsorbent for the first heat exchange reactor as the adsorber, and magnesium chloride (MgCl ₂ ) is used as the chemical heat storage material for the second heat exchange reactor as the heat storage reactor. An NH3 accumulation / transport device using steam (water) and outside air as the heat medium used and supplied to the heat medium flow path of the first heat exchange reactor will be described in detail as an example.

  As shown in FIG. 1, the NH 3 storage / transport device 100 of the present embodiment includes an evaporator 10, a first heat exchange reactor 20 having a physical adsorbent, and a second heat exchange having a chemical heat storage material. A reactor 40, a condenser 40 that condenses the fluid (water vapor) discharged from the first heat exchange reactor 20, and a water tank 41 that stores the water supplied from the condenser 40. Yes.

  The water vapor is meant to include water in a gaseous state and water condensed into fine water droplets in the air.

  The evaporator 10 is connected to the first heat exchange reactor 20 so as to be able to supply water vapor, which is a fluid generated by vaporizing water using the exhaust heat from the exhaust heat source. Specifically, the evaporator 10 is connected to the other end of a flow pipe 11 having one end connected to the three-way valve V1, and the evaporator 10 has one end connected to the flow pipe 11 and the three-way valve V1. The first heat exchange reactor 20 is communicated with the flow pipe 12 thus formed. The evaporator 10 is connected to the second heat exchange type reactor 30. Specifically, the evaporator 10 is communicated with the second heat exchange type reactor 30 through the circulation pipe 14 having the valve V5.

  The three-way valve V <b> 1 switches the water vapor supplied from the evaporator 10 and the outside air supplied from the circulation pipe 15 as a temperature adjustment mechanism, and supplies the water to the first heat exchange reactor 20.

  The condenser 40 is connected so as to be able to supply water vapor from the first heat exchange reactor 20, and condenses the water vapor supplied from the first heat exchange reactor 20. Specifically, one end of a distribution pipe 45 having a valve V4 is connected to the condenser 40. The condenser 40 is communicated with the first heat exchange type reactor 20 through the circulation pipe 45, and the water vapor discharged from the first heat exchange type reactor 20 through the circulation pipe 45 is collected in the condenser 40. It has come to be.

  Further, one end of a circulation pipe 43 is connected to the condenser 40, and the condenser 40 is communicated with the water tank 41 by the circulation pipe 43. One end of a distribution pipe 44 having a pump P is connected to the water tank 41, and the water tank 41 is communicated with the evaporator 10 through the distribution pipe 44. The water that is condensed and liquefied by the water vapor in the condenser 40 is stored in the water tank 41, and the water stored in the water tank 41 is supplied to the evaporator 10 through the distribution pipe 44 by driving the pump P.

  The first heat exchange reactor 20 is connected to the second heat exchange reactor 30 via an ammonia pipe 42 having a valve V4.

  FIG. 2 is a diagram schematically showing the configuration of the first heat exchange reactor 20 and the second heat exchange reactor 30. FIG. 3 is a diagram schematically showing the first heat exchange reactor 20 in FIG.

  As shown in FIG. 3, the first heat exchange reactor 20 includes a housing 22, a plurality of heat medium channels 26 provided in the housing 22, and a plurality of reaction chambers provided in the housing 22. 24 and a laminated body 25 housed in each reaction chamber 24 and containing an adsorbent.

  In the housing 22, the reaction chambers 24 and the heat medium flow paths 26 are alternately arranged, and the two heat medium flow paths 26 are arranged on the outermost side. The reaction chamber 24 and the heat medium flow path 26 are separated from each other with a partition wall therebetween. With these configurations, heat exchange can be performed between the heat medium M1 supplied from the outside and the adsorbent molded body in the reaction chamber 24. In this embodiment, the reaction chamber 24 and the heat medium flow path 26 are each a prismatic space having a flat rectangular opening end. In this embodiment, in the first heat exchange reactor 20, the opening direction of the reaction chamber 24 (ammonia flow direction) and the opening direction of the heat medium flow channel 26 (heat medium flow direction) are orthogonal in a side view. It is configured as a cross-flow type heat exchange reactor.

  As in the example of the first heat exchange reactor 20, the reactor in the present invention has two or more reaction chambers containing the adsorbent, and the heat medium flow path is at least between the reaction chambers. It is preferable that the configuration is an arrangement in which two or more reaction chambers and two or more heat medium flow paths are provided, and the reaction chambers and the heat medium flow paths are alternately arranged. preferable.

  There are no particular limitations on the number of reaction chambers 24 and heat medium flow paths 26 in the first heat exchange reactor 20, and the amount of heat input to and output from the first heat exchange reactor 20 and the adsorbent molded body It can be set as appropriate in consideration of the area of the heat transfer surface (contact area with the reaction chamber wall).

  Moreover, as a material of the housing | casing 22, the material with high heat conductivity, such as a metal (for example, stainless steel, aluminum, aluminum alloy etc.), and ammonia corrosion resistance is suitable.

  As shown in FIG. 3, the laminated body 25 has two adsorbent molded bodies (adsorbent molded body 21A and adsorbent molded body 21B) that store heat when ammonia is desorbed and dissipate heat when ammonia is adsorbed. Hereinafter, these are collectively referred to as “adsorbent molded bodies 21A and 21B”) and a support 23 sandwiched between the adsorbent molded bodies 21A and 21B. In FIG. 3, the adsorbent molded body 21 </ b> A, the support body 23, and the adsorbent molded body 21 </ b> B are illustrated separately in order to make the configuration of the laminated body 25 easier to see.

  However, the configuration of the laminated body in the present invention may be a configuration having at least a three-layer configuration of such an adsorbent molded body / support / adsorbent molded body. Other configurations in which the molded material and the support are alternately arranged and the outermost layer is an adsorbent molded product (for example, an adsorbent molded product / support / adsorbent molded product / support / adsorbent molded product) 5 layers structure, etc.).

  The adsorbent molded bodies 21A and 21B each include an adsorbent that stores heat when ammonia is desorbed by an endothermic reaction and dissipates heat when ammonia is adsorbed by an exothermic reaction.

  In the present invention, the adsorbent housed in the reactor is not limited to the adsorbent molded body (for example, the adsorbent molded bodies 21A and 21B), and a powder adsorbent may be used. From the viewpoint of further improving the efficiency of heat exchange in the vessel, an adsorbent molded body is preferable.

  The adsorbent of the first heat exchange reactor 20 is a physical adsorbent that adsorbs ammonia by physical adsorption. On the other hand, the heat storage material of the second heat exchange reactor 30 is a chemical heat storage material that adsorbs ammonia by a coordination reaction. Note that the heat storage material of the second heat exchange reactor 30 may be a physical adsorbent that adsorbs ammonia by physical adsorption.

  Details of the preferred form of the adsorbent in the present invention will be described later.

As the support 23, it is preferable to use a support that can circulate ammonia gas in a direction along the surface of the support 23 (for example, a direction of a white arrow in FIG. 3). Thereby, since the flow path of ammonia vapor can be secured between the two adsorbent molded bodies, the ammonia gas (NH ₃ ) supplied from the ammonia pipe 42 can be used in a wide range of the adsorbent molded bodies 21A and 21B. Can supply. Furthermore, ammonia adsorbed in a wide range of the adsorbent molded bodies 21A and 21B can be discharged toward the ammonia pipe 42 via the support 23.

  Specifically, it is preferable to use a corrugated plate or a porous plate as the support 23.

  When a porous plate is used as the support 23, ammonia passes through the porous plate.

  When a corrugated plate is used as the support 23, the ammonia gas passes through a gap formed between the corrugated plate and the adsorbent molded body.

  FIG. 4 conceptually shows the first heat exchange reactor 20 and the stacked body 25 accommodated in the first heat exchange reactor 20 particularly when a corrugated plate is used as the support 23. It is a figure. The configuration other than the corrugated plate as the support 23 is the same as that shown in FIG.

  When a corrugated plate is used as the support 23, ammonia passes through a gap generated between the corrugated plate and the adsorbent molded bodies 21A and 21B in the laminate 25 (in the direction of the white arrow in FIG. 4). .

  In addition, as shown in FIG. 2, the first heat exchange reactor 20 and the ammonia pipe 42 are configured so that the plurality of reaction chambers 24 and the ammonia pipe 42 in the first heat exchange reactor 20 are in an airtight state. They are connected via a header member 28 (for example, a manifold) that communicates. Thereby, ammonia can be circulated between the plurality of reaction chambers 24 and the ammonia pipe 42 in an airtight state.

  In FIG. 2, in order to make the configuration of the first heat exchange reactor 20 and the second heat exchange reactor 30 easier to see, the header member 28, the following header member 29A, the following header member 29B, and the following header The member 38, the following header member 39 </ b> A, the following header member 39 </ b> B, the following distribution pipe 12, the following distribution pipe 45, the following distribution pipe 14, and the following heat medium pipe 37 </ b> B are represented by two-dot chain lines (the same applies to FIG. 14 described later). Is).

  Further, as shown in FIG. 2, the first heat exchange reactor 20 is connected to the flow pipe 12 via a header member 29A (for example, a manifold) and a header member 29B (for example, a manifold). It is connected to the distribution pipe 45 via The plurality of heat medium flow paths 26 in the first heat exchange type reactor 20 are communicated with the circulation pipe 12 in an airtight state by the header member 29A, and communicated with the circulation pipe 45 in an airtight state by the header member 29B. Has been. Accordingly, the heat medium M1 can be circulated between the heat medium flow path 26 in the first heat exchange type reactor 20, the evaporator 10 and the condenser 40 through the distribution pipe 12 and the distribution pipe 45. ing.

  As the heat medium M1, a fluid usually used as a heat medium such as alcohol such as ethanol and methanol, water, oils, and a mixture thereof can be used, and a low boiling point refrigerant such as ethanol, methanol, and water can be used. preferable. In the present embodiment, a case where water is used as the heat medium M1 will be described as an example.

  As shown in FIG. 2, the ammonia pipe 42 is provided with a valve V4 (valve), and the difference in ammonia pressure can be adjusted by opening and closing the valve V4. Thereby, the difference between the ammonia pressure on the first heat exchange reactor 20 side and the ammonia pressure on the second heat exchange reactor 30 side can be more effectively maintained. That is, the difference in ammonia pressure can be maintained for a long time by maintaining the valve V4 in the closed state, and then the one heat exchange reactor side to the other heat exchange reactor side by opening the valve V4. Can transport ammonia. In this way, the heat stored on one heat exchange reactor side can be efficiently utilized on the other heat exchange reactor side.

  As shown in FIG. 2, the second heat exchange reactor 30 is also housed in a housing 32, a plurality of reaction chambers 34, and each reaction chamber 34, similarly to the first heat exchange reactor 20. The heat exchanger is provided with a stacked body 35 and a plurality of heat medium flow paths 36. The configuration of the stacked body 35 and the configuration in the second heat exchange reactor 30 are the same as the configuration of the stack 25 and the configuration in the first heat exchange reactor 20, respectively.

  The second heat exchange type reactor 30 is connected to the distribution pipe 14 via the header member 39A, and is connected to the heat medium pipe 37B via the header member 39B. The plurality of heat medium flow paths 36 in the first heat exchange type reactor 30 are communicated with the circulation pipe 14 in an airtight state by the header member 39A, and are connected to the heat medium pipe 37B in an airtight state by the header member 39B. It is communicated. Thereby, the heat medium flow path 36 in the second heat exchange reactor 30 and the outside of the NH 3 accumulation / transport device 100 (hereinafter simply referred to as “external” or “external”) through the distribution pipe 14 and the heat medium pipe 37B. The heat medium M2 can be circulated with the other.

  As the heat medium M2, a fluid usually used as a heat medium, such as alcohol such as ethanol, water, oils, a mixture thereof, or the like can be used. In the present embodiment, a case where water is used as the heat medium M2 will be described as an example. Further, the distribution path of the heat medium M1 and the distribution path of the heat medium M2 are independent of each other.

  The NH3 storage / transport device 100 also measures ammonia supply means (not shown) for supplying ammonia into the apparatus, exhaust means (not shown) for exhausting the inside of the apparatus, and ammonia pressure in the apparatus. A pressure measuring means (not shown) or the like may be connected.

  As shown in FIG. 5A, the heat medium flow path 26 of the first heat exchange type reactor 20 condenses the heat medium M1 supplied from the evaporator 10 to hold the liquid, which is a liquid holding mechanism 26A. have. As the liquid holding mechanism 26A, for example, a liquid holding mechanism (dimple / porous body) using the surface tension of the condensed liquid is used. As shown in FIG. 5B, a liquid holding mechanism (pocket) using gravity may be used as the liquid holding mechanism 26A.

  Next, an example of heat transport performed between the first heat exchange reactor 20 and the second heat exchange reactor 30 will be described.

(Heat release mode)
First, the heat supplied to the first heat exchange reactor 20 is transported to the second heat exchange reactor 30 and the transported heat is radiated from the second heat exchange reactor 30 to the outside. An example of usage will be described. In this example, the first heat exchange type reactor 20 is a heat input side reactor, and the second heat exchange type reactor 30 is a heat output side reactor.

  In this example, first, as an initial state, ammonia is collected on the first heat exchange reactor 20 side, the ammonia is adsorbed on the adsorbent in the first heat exchange reactor 20, and then the valve V4 is closed. . An example of a specific method for setting the initial state is the same as the “reproduction” method described later.

  Then, as shown in FIG. 6, heat is supplied to the first heat exchange reactor 20 by circulating the high-temperature heat medium M1 supplied from the evaporator 10 through the three-way valve V1.

  In the second heat exchange type reactor 30, a heat medium M2 for releasing heat toward an external heat utilization target is circulated.

  In this state, the ammonia pressure on the first heat exchange reactor 20 side is higher than the ammonia pressure on the second heat exchange reactor 30 side. By keeping the valve V4 closed, the difference in ammonia pressure between the first heat exchange reactor 20 side and the second heat exchange reactor 30 side can be maintained for a long time.

  Next, when the valve V4 is opened, ammonia is transported from the first heat exchange reactor 20 having a high ammonia pressure toward the second heat exchange reactor 30 having a relatively low ammonia pressure. At this time, in the first heat exchange reactor 20, ammonia is desorbed from the adsorbent in the first heat exchange reactor 20 by an endothermic reaction. The endothermic reaction is maintained by maintaining the flow of the high-temperature heat medium M1 to the first heat exchange reactor 20 (that is, maintaining the supply of heat to the first heat exchange reactor 20). Done).

  Further, in the heat medium flow path 26 of the first heat exchange type reactor 20, as shown in FIG. 7, the supplied heat medium M1 is condensed and held by the liquid holding mechanism 26A.

  The ammonia that has reached the second heat exchange reactor 30 by the transport of the ammonia is adsorbed on the heat storage material in the reaction chamber 34 of the second heat exchange reactor 30 by an exothermic reaction. The heat medium M2 is heated by this exothermic reaction, and the heated heat medium M2 is radiated toward an external heating target.

  As described above, accompanying the transport of ammonia from the first heat exchange reactor 20 to the second heat exchange reactor 30, the heat supplied to the first heat exchange reactor 20 is changed to the first heat exchange reactor 20. 2 is transferred to the heat exchange reactor 30 side and is radiated from the second heat exchange reactor 30.

(Heat storage mode)
When the above heat radiation is continued and ammonia in the first heat exchange reactor 20 is reduced, the ammonia in the system is collected again on the first heat exchange reactor 20 side, and the first heat exchange reactor 20 is collected. By adsorbing ammonia to the adsorbent molded bodies 21A and 21B in the mold reactor 20, it is regenerated to the initial state.

  As an example of a specific method of regeneration, with the valve V4 opened, as shown in FIG. 8, outside air is supplied to the first heat exchange reactor 20 through the three-way valve V1, The heat medium M2 maintained at a high temperature (for example, 160 ° C.) is circulated through the heat medium flow path 36 in the heat exchange type reactor 30.

  Thereby, ammonia is desorbed from the second heat exchange reactor 30 by an endothermic reaction, and ammonia is transported from the second heat exchange reactor 30 side to the first heat exchange reactor 20 side. .

  The ammonia that has reached the first heat exchange reactor 20 is adsorbed by the exothermic moldings 21A and 21B in the reaction chamber 24 of the first heat exchange reactor 20 by an exothermic reaction. At this time, in the heat medium flow path 26 of the first heat exchange reactor 20, as shown in FIG. 9, the condensed heat medium M1 held by the liquid holding mechanism 26A is cooled by the outside air, and latent heat is generated. By cooling, the first heat exchange reactor 20 is cooled below the ambient temperature.

  This exothermic reaction is maintained, for example, by maintaining the supply of outside air to the first heat exchange reactor 20.

  In the NH3 storage / transport device 100, the above heat dissipation mode and heat storage mode can be repeated.

  As described in the above embodiments, the NH3 storage / transport device 100 of the present invention transports ammonia from one to the other by utilizing the difference in ammonia pressure generated between two or more reactors. It is a device that transports heat.

FIG. 10 is a graph showing the temperature dependence of the physical adsorbent (for example, activated carbon) of the first heat exchange reactor 20 and showing the relationship between the ammonia (NH ₃ ) pressure and the ammonia adsorption amount. In FIG. 10, point A represents the maximum pressure (250 kPa) required for ammonia regeneration in the heat storage mode, and point B represents the minimum pressure 900 kPa at which ammonia can be supplied in the heat release mode.

FIG. 11 is a graph showing the relationship between the ammonia (NH ₃ ) pressure and the equilibrium temperature in the chemical heat storage material (for example, MgCl ₂ ) of the second heat exchange reactor 30.

  The temperature of the first heat exchange reactor 20 can be increased by the heat medium M1 (water vapor) supplied from the evaporator 10 that is higher than the outside air temperature. Since it is steam heating, rapid heating is possible compared to sensible heat heating. In the first heat exchange reactor 20, the operating pressure is determined by the NH3 relative pressure, and in the second heat exchange reactor 30, the temperature increase upper limit temperature is determined by the NH3 operating pressure. Therefore, the operating pressure increases by increasing the temperature of the first heat exchange reactor 20 (see FIG. 10 above), and the temperature of the heat storage reactor can be increased (see FIG. 11 above).

  In this way, the first heat exchange reaction is performed when the second heat exchange reactor 30 is radiated (when ammonia is supplied from the first heat exchange reactor 20 to the second heat exchange reactor 30). By heating the reactor 20 with the high-temperature steam generated by the evaporator 10 and increasing the ammonia operating pressure, it is possible to improve the temperature increase rate and temperature increase range of the second heat exchange reactor. .

  Further, since the condensate generated during the steam heating can be held in the liquid holding mechanism 26A of the heat medium flow path 26 inside the first heat exchange reactor 20, the second heat exchange reactor can be used. By supplying the outside air to the heat medium passage 26 of the second heat exchange reactor 20 during the heat storage, it becomes possible to cool the latent heat below the outside air temperature. The regeneration temperature of the second heat exchange reactor 30 can be lowered by lowering the operating pressure of ammonia, and the first heat exchange reactor 20 cooled below the ambient temperature by latent heat cooling. Thus, it is possible to store heat at a lower temperature. Further, the heat storage of the second heat exchange reactor 30 can be performed quickly even with a lower temperature heat source.

  As described above, it is possible to construct an NH 3 storage / transport device that can be heated to a temperature higher than the heat storage temperature.

(Adsorbent, heat storage material)
Next, preferable ranges of the adsorbent and the heat storage material accommodated in the first and second heat exchange reactors in the present invention will be described.

  The heat storage material accommodated in the second heat exchange reactor preferably includes a chemical heat storage material that immobilizes ammonia by a coordination reaction.

  Since the heat storage density in the second heat exchange reactor can be further increased by using the heat storage material including the chemical heat storage material, the heat storage density of the entire heat transport apparatus can be further increased. Moreover, since the chemical heat storage material has a large difference in the heat storage temperature depending on the type compared to the physical adsorption material, the chemical heat storage material can be used by using the second heat exchange reactor in which the heat storage material including the chemical heat storage material is stored. By selecting the type of material, the range of selection of operating conditions such as operating temperature and operating ammonia pressure of the heat transport device can be expanded. Therefore, the working ammonia pressure and the working temperature can be selected from a wide range according to the heat utilization target.

  On the other hand, in the first heat exchange type reactor, the amount of heat required for adsorption and desorption of ammonia can be further reduced in the reactor by using an adsorbent containing a physical adsorbent. As a result, the controllability of heat transport is further improved.

  Thus, by selecting the combination of the adsorbent in the first heat exchange reactor and the heat storage material in the second heat exchange reactor, a large amount of heat can be obtained with a small heat input due to the difference in the amount of reaction heat between the reactors. Output can be obtained.

  In the configuration in which the first heat exchange type reactor including the physical adsorbent and the second heat exchange type reactor including the chemical adsorbent are combined, the entire apparatus includes the second heat exchange including the chemical heat storage material. A higher heat storage density can be obtained by the mold reactor, and the adsorption and desorption of ammonia can be more easily controlled by the first heat exchange reactor containing the physical adsorbent.

  Furthermore, in the above combined configuration, a chemical heat storage material having a large amount of heat required for adsorption and desorption of ammonia compared to a physical adsorbent, and an ammonia adsorption and desorption compared to a chemical heat storage material. And a physical adsorbent having a property of low heat. For this reason, even when a small amount of heat is supplied to the first heat exchange type reactor containing the physical adsorbent using the difference in the amount of reaction heat between the reactors, the second containing the chemical heat storage material. A larger amount of heat can be dissipated on the heat exchange type reactor side.

For example, the amount of heat required for immobilization and desorption of 1 mol of ammonia is 40 kJ / mol for a chemical heat storage material (for example, LiCl, MgCl ₂ , CaCl ₂ , SrCl ₂ , BaCl ₂ , MnCl ₂ , CoCl ₂ , NiCl ₂ , etc.). While it is ˜60 kJ / mol, it is 20 kJ / mol to 30 kJ / mol for a physical adsorbent (for example, activated carbon, mesoporous silica, zeolite, silica gel, clay mineral, etc.).

-Chemical heat storage material-
Next, the preferable form of the said chemical heat storage material is demonstrated in detail.

The chemical heat storage material is preferably a metal halide from the viewpoint of increasing the heat storage density in the reactor, and alkali metal chloride, bromide, iodide, alkaline earth metal chloride, bromide, iodide, Alternatively, transition metal chlorides, bromides, and iodides are more preferable, and LiCl, MgCl ₂ , CaCl ₂ , SrCl ₂ , BaCl ₂ , MnCl ₂ , CoCl ₂ , or NiCl ₂ are particularly preferable.

  The said metal halide may be used individually by 1 type, and may use 2 or more types together.

  When the heat storage material in this invention contains the said chemical heat storage material, this chemical heat storage material may be contained in the heat storage material 1 type, and may be contained 2 or more types.

  When the heat storage material in this invention contains the said chemical heat storage material, this heat storage material may contain other components other than the said chemical heat storage material.

  Examples of other components include binder components such as alumina and silica, and heat conduction aids such as carbon fibers.

  However, when the heat storage material in the present invention includes the chemical heat storage material, from the viewpoint of further improving the heat storage density, the content of the chemical heat storage material in the heat storage material is preferably 60% by mass or more, and 80% by mass. The above is more preferable.

  Moreover, when shape | molding the thermal storage material containing a chemical thermal storage material in a thermal storage material molded object, there is no limitation in particular about the shaping | molding method, For example, thermal storage material containing a chemical thermal storage material (and other components, such as a binder as needed) A method of molding (or slurry containing the heat storage material) by a known molding means such as pressure molding or extrusion molding may be used.

  Examples of the molding pressure include 20 MPa to 100 MPa, and 20 MPa to 40 MPa is preferable.

−Physical adsorption material−
Next, the preferable form of the said physical adsorption material is demonstrated in detail.

  A porous body can be used as the physical adsorbent.

  The porous body is preferably a porous body having pores of 10 nm or less from the viewpoint of further improving the reactivity of adsorption and desorption of ammonia by physical adsorption.

  The lower limit of the pore size is preferably 0.5 nm from the viewpoint of production suitability and the like.

  From the same viewpoint, the porous body is preferably a porous body that is a primary particle aggregate obtained by aggregating primary particles having an average primary particle diameter of 50 μm or less.

  The lower limit of the average primary particle diameter is preferably 1 μm from the viewpoint of production suitability and the like.

  Specific examples of the porous body include activated carbon, mesoporous silica, zeolite, silica gel, clay mineral and the like.

The activated carbon is preferably activated carbon having a specific surface area of 800 m ² / g or more and 2500 m ² / g or less (more preferably 1800 m ² / g or more and 2500 m ² / g or less) by the BET method.

  The clay mineral may be an uncrosslinked clay mineral or a crosslinked clay mineral (crosslinked clay mineral). Examples of the clay mineral include sepiolite.

  When the adsorbent in the present invention includes a physical adsorbent (preferably the porous body), the adsorbent may include the physical adsorbent (preferably the porous body) alone or in combination of two or more. May be included.

  In the present invention, the type of the physical adsorbent (preferably the porous body) can be appropriately selected according to the operating ammonia pressure and the operating temperature.

  From the viewpoint of further improving the reactivity of adsorption and desorption of ammonia by physical adsorption, the physical adsorbent preferably contains at least activated carbon.

  In the case where the adsorbent in the present invention contains a physical adsorbent, the content of the physical adsorbent in the adsorbent is 80% by volume or more from the viewpoint of maintaining higher ammonia adsorption and desorption reactivity. It is preferably 90% by volume or more.

  Moreover, when using the adsorption material containing the physical adsorption material in this invention as a molded object (adsorbent molded object), it is preferable that this adsorption material contains a binder in addition to the said physical adsorption material. When the adsorbent contains a binder, the shape of the adsorbent molded body is more effectively maintained, so that the reactivity of adsorption and desorption of ammonia by physical adsorption is further improved.

  The binder is preferably at least one water-soluble binder.

  Examples of the water-soluble binder include polyvinyl alcohol and trimethyl cellulose.

  When the adsorbent in the present invention contains a physical adsorbent and a binder, the content of the binder in the adsorbent is 5% by volume or more from the viewpoint of more effectively maintaining the shape of the adsorbent molded body. Is preferable, and it is more preferable that it is 10 volume% or more.

  When the adsorbent in the present invention contains a physical adsorbent and a binder, the adsorbent may contain other components other than the physical adsorbent and the binder as necessary.

  Examples of other components include heat conduction auxiliary materials such as carbon fibers.

  In addition, when an adsorbent containing a physical adsorbent is formed into an adsorbent molded body, the molding method is not particularly limited. For example, an adsorbent containing a physical adsorbent (and other components such as a binder as required) is used. Examples thereof include a method of molding (or slurry containing the adsorbent) by known molding means such as pressure molding and extrusion molding.

  Examples of the molding pressure include 20 MPa to 100 MPa, and 20 MPa to 40 MPa is preferable.

(Preferred form of reaction chamber)
Next, reaction chambers in the first and second heat exchange reactors (for example, the reaction chamber 24 in the first heat exchange reactor 20 and the reaction chambers in the second heat exchange reactor 30). The preferred embodiment 34) will be described by taking the reaction chamber 24 in the first heat exchange reactor 20 as an example.

  The reaction chamber 24 in the first heat exchange reactor 20 preferably has an inner wall having a contact portion with the adsorbent molded bodies 21A and 21B. More preferably, the inner wall of the reaction chamber 24 is in contact with one main surface of the adsorbent moldings 21A and 21B (that is, the adsorbent molding is the inner wall of the reaction chamber and the surface of the support). And is sandwiched between the two).

  That is, it is preferable that the adsorbent molded bodies 21A and 21B are in contact with the inner wall of the reaction chamber 24 and the surface of the support 23, respectively.

  According to the configuration in which the inner wall of the reaction chamber 24 has a contact portion with the adsorbent molded bodies 21A and 21B, the first heat exchange reactor and the adsorbent molded body are passed through the inner wall of the reaction chamber 24. Heat exchange can be performed more effectively. In general, when the adsorbent molded body is repeatedly used, the adsorbent molded body repeatedly expands and contracts due to adsorption and desorption of ammonia, and the adsorbent molded body may be cracked (including cracks) or pulverized. However, according to the said structure, the crack (a crack is included) and pulverization of an adsorbent molded object at the time of this repeated use can be suppressed more effectively.

  The preferable form of the reaction chamber 34 in the second heat exchange reactor 30 is the same as that of the reaction chamber 24 in the first heat exchange reactor 20.

  The control device 90 is a control unit that performs overall control of the NH3 storage / transport device 100, and is electrically connected to the three-way valve V1, the valves V3 to V5, the pump P, an external heat source, and the like. It is configured to control the use of heat by controlling valves, pumps, heat sources and heat exchange.

  Next, in the control routine by the control device 90 which is a control unit for controlling the NH 3 accumulation / transport device of the present embodiment, the second heat exchange reaction is performed by supplying water vapor to the first heat exchange reactor 20. The heat dissipation heat storage cycle control routine for storing heat after radiating heat from the vessel 30 will be mainly described with reference to FIG.

  When the control device 90 is turned on by turning on the start switch of the NH3 storage / transport device of the present embodiment, the system is started, and when heat dissipation from the second heat exchange reactor 30 is requested, heat dissipation is performed. A heat storage cycle control routine is executed.

  When this routine is executed, first, in step 100, the valve V3 attached to the distribution pipe 45 is opened, and the operation of the pump P is started.

  In step 102, the three-way valve V1 is switched so that the flow pipe 11 connected to the evaporator 10 communicates with the flow pipe 12 connected to the first heat exchange reactor 20. Heating of the first heat exchange reactor 20 is started.

  In Step 104, the valve V 4 attached to the ammonia pipe 42 is opened, and ammonia is transported from the first heat exchange reactor 20 to the second heat exchange reactor 30. At this time, ammonia is adsorbed to the heat storage material of the second heat exchange type reactor 30, and the generated heat of adsorption is dissipated through the heat medium M2.

In the next step 106, the elapsed time after the transition to step 100 is whether the situation is less than the predetermined time (timer) Q ¹ is determined, when it is determined that not yet time Q ¹ is passed Since the adsorbent of the first heat exchange reactor 20 is in a state where ammonia can be desorbed, steps 100 to 104 are continued. On the other hand, when it is determined that the time Q ¹ is passed, in order to switch to the heat storage mode, the process proceeds to step 108.

  In step 108, the valve V3 attached to the flow pipe 45 is closed, the valve V5 attached to the flow pipe 14 is opened, and heating of the second heat exchange reactor 30 is started.

  In step 110, the three-way valve V1 is switched so that the circulation pipe 15 for supplying outside air communicates with the circulation pipe 12 connected to the first heat exchange reactor 20, and the first heat is supplied. Cooling of the exchange reactor 20 is started. Thereby, ammonia is transported from the second heat exchange reactor 30 to the first heat exchange reactor 20. At this time, ammonia is desorbed from the heat storage material of the second heat exchange reactor 30, and the heat of the heat medium M2 is stored.

In the next step 112, the elapsed time after the transition to step 108 it is determined whether a situation does not reach the predetermined time (timer) Q ^2, when it is determined that not yet time Q ² has elapsed In order to regenerate the heat storage material by further desorbing the ammonia adsorbed on the heat storage material of the second heat exchange reactor 30, steps 108 and 110 are continued. On the other hand, when it is determined that the elapsed time Q ² is, the process proceeds to the next step 114, closing the valve V3 which is attached to the valve V4 and circulation pipe 14 is attached to an ammonia pipe 42, the operation of the pump P Stop and end this routine. Thereby, the pressure difference between the first heat exchange reactor 20 and the second heat exchange reactor 30 is maintained.

  As described above, according to the NH3 storage / transport device of the first embodiment, when ammonia is desorbed from the adsorbent of the first heat exchange reactor in which the adsorbent including the physical adsorbent is accommodated. By increasing the ammonia operating pressure by supplying water vapor from the evaporator and heating it, it is possible to improve the temperature increase rate and temperature increase range of the second heat exchange reactor.

(Second Embodiment)
A second embodiment of the NH 3 storage / transport device of the present invention will be described with reference to FIG. This embodiment has a system configuration in which water vapor supplied from the evaporator to the first heat exchange reactor is exhausted without being recovered.

  In the second embodiment of the NH3 storage / transport device, the same reference numerals are assigned to the same components as those in the first embodiment, and the detailed description thereof is omitted.

  As shown in FIG. 13, the NH 3 storage / transport device 200 of the present embodiment includes an evaporator 10, a first heat exchange reactor 20 having a physical adsorbent, and a second heat exchange having a chemical heat storage material. A mold reactor 30 and a water tank 41 for storing the water supplied from the condenser 40 are provided.

  The water vapor discharged from the heat medium flow path 26 of the first heat exchange reactor 20 is exhausted.

  In addition, about the other structure and effect | action of NH3 storage / transport device which concern on 2nd Embodiment, since it is the same as that of 1st Embodiment, description is abbreviate | omitted.

  Although the NH3 storage / transport device according to the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

  For example, a pressure adjusting mechanism may be further provided in the ammonia pipe.

  FIG. 14 is a diagram schematically showing a first heat exchange reactor 20, a second heat exchange reactor 30, and an ammonia pipe 42 according to another embodiment of the present invention.

  As shown in FIG. 14, pressure adjustment means 320 is provided in the ammonia pipe 42. Other configurations are the same as those of the NH3 storage / transport device 100 described above.

  As the pressure adjusting means 320, means having a function of further increasing the difference in ammonia pressure between the first heat exchange reactor 20 and the second heat exchange reactor 30 by external force can be used. Specifically, known means such as a pressure pump and a compressor (compressor, etc.) can be used.

  As described above, in addition to the valve V4, the pressure adjusting means 320 is provided as an auxiliary, and the pressure adjusting means 320 is operated, whereby ammonia can be transported (that is, heat can be transported more effectively).

  In FIG. 14, the pressure adjusting means 320 is provided on the first heat exchange reactor 20 side with respect to the valve V4. However, the pressure adjusting means is particularly limited as long as the pressure adjusting means is provided in at least one location of the ammonia pipe. There is no. For example, the pressure adjusting means 320 may be provided on the second heat exchange reactor 30 side with respect to the valve V4.

  Moreover, although the case where the heat transport apparatus according to the present invention is applied to an NH3 storage / transport device has been described as an example, the present invention is not limited to this, and is applied to a heat transport apparatus other than the NH3 storage / transport device. Also good.

  In the NH3 storage / transport devices 100 and 200 according to the above-described embodiment, only two reactors (the first heat exchange reactor 20 and the second heat exchange reactor 30) are connected by the ammonia pipe 42. Although configured, the NH 3 storage / transport devices 100 and 200 may include other reactors. That is, at least one of the other reactors other than the second heat exchange reactor 30 may be further connected to the first heat exchange reactor 20 by an ammonia pipe. At this time, the first heat exchange reactor 20 and two or more reactors may be connected by one ammonia pipe having a branch, or the first heat exchange reactor 20 and the two reactors. The above reactors may be connected independently by two or more ammonia pipes having no branch. Moreover, the 1st heat exchange type | mold reactor 20 and three or more reactors may be connected by one or more ammonia piping which has a branch, and one or more ammonia piping which does not have a branch.

  As other reactors, for example, similarly to the first heat exchange reactor 20 and the second heat exchange reactor 30, heat is stored when ammonia is desorbed and heat is released when ammonia is adsorbed. A reactor containing an adsorbent or a heat storage material can be used.

  Further, in the NH3 storage / transport devices 100 and 200 according to the above embodiment, each heat exchange reactor and the ammonia pipe are connected via a header member, but each heat exchange reactor and the ammonia pipe are connected. You may connect directly in an airtight state without going through a header member. Further, a heat exchange reactor integrated with the header member may be used, and the heat exchange reactor and the ammonia pipe may be connected in an airtight state.

  Moreover, in NH3 accumulation | storage / transport device 100,200 which concerns on the said embodiment, although valve | bulb V4 (valve) is provided in ammonia piping 42, this valve | bulb V4 may be abbreviate | omitted. Even when the valve V4 is omitted, heat is supplied to at least one of the first heat exchange reactor 20 and the second heat exchange reactor 30 and the first heat exchange reactor 20 side and the first heat exchange reactor 20 side. A difference in ammonia pressure can be produced between the two heat exchange reactors 30 and ammonia and heat can be transported by this difference in ammonia pressure.

DESCRIPTION OF SYMBOLS 10 Evaporator 11 Distribution pipe 12 Distribution pipe 15 Distribution pipe 20 1st heat exchange type reactor 21A, 21B Adsorbent molded object 26, 36 Heat-medium flow path 26A Liquid holding mechanism 30 2nd heat exchange type reactor 40 Condensation Unit 41 Water tank 42 Ammonia pipe 90 Controller 100, 200 NH3 storage / transport device 320 Pressure adjusting means M1, M2 Heat medium V1 Three-way valve V3, V4 Valve V4 Valve

Claims (10)

A heat medium flow in which an adsorbent or a heat storage material that stores heat when ammonia is desorbed and dissipates heat when ammonia is adsorbed, and a heat medium that exchanges heat with the adsorbent or the heat storage material circulates. Two or more reactors having a path, wherein at least one of the two or more reactors stores heat when ammonia is desorbed and dissipates heat when ammonia is adsorbed by physical adsorption. A reactor containing an adsorbent containing the adsorbent, and
An ammonia pipe that connects the two or more reactors and circulates ammonia between the two or more reactors;
A three-way valve capable of switching between two types of heat media having different temperatures to be supplied to a heat medium flow path of a reactor containing the adsorbent containing the physical adsorbent, wherein the adsorbent containing the physical adsorbent A distribution pipe having one end connected to the heat medium flow path of the stored reactor, a flow path pipe to which a high temperature heat medium is supplied from one end side, and a low temperature heat medium to be supplied from one end side A three-way valve connected to the flow pipe ;
When ammonia is adsorbed to the adsorbent of the reactor containing the adsorbent containing the physical adsorbent, the three-way valve is controlled to supply a heat medium having a low temperature, and the physical adsorbent A control unit that controls the three-way valve so as to supply the heat medium having a high temperature when ammonia is desorbed from the adsorbent of the reactor in which the adsorbent is contained ,
A heat transport device for transporting heat by transporting ammonia from one side to the other by utilizing a difference in ammonia pressure generated between the two or more reactors. The physical adsorbent reactor heat medium channel of the adsorbent is housed comprising condenses the supplied heat medium, the heat according to claim 1, further comprising a heat medium holding mechanism for holding the condensed heat medium Transport equipment. The heat transport device according to claim 2, wherein the heat medium holding mechanism holds the heat medium using a surface tension of the condensed heat medium. The heat transport device according to claim 2 , wherein the heat medium holding mechanism holds the condensed heat medium using gravity. The 3-way valve, as the temperature is high thermal medium, according to claim 1 heat transport device of any one of claims 4 to supply the low-boiling refrigerant. The heat transport apparatus according to claim 5 , wherein the three-way valve supplies methanol, ethanol, or water as the low boiling point refrigerant. The heat transport apparatus according to claim 5 or 6 , further comprising a condenser capable of recovering the low-boiling-point refrigerant supplied to a heat medium flow path of a reactor in which the adsorbent containing the physical adsorbent is stored. An evaporator for evaporating the low boiling point refrigerant;
The 3-way valve, the said low-boiling refrigerant supplied from the evaporator, any of the physical adsorption according to supply material to the heat medium flow path of the reactor in which the adsorbent is housed including claims 5 to claim 7 The heat transport device according to claim 1. The 3-way valve, as the temperature is low heat medium, according to claim 1 heat transport device of any one of claims 8 supplies air. The heat transport apparatus according to any one of claims 1 to 9 , wherein a valve is provided in the ammonia pipe, and a difference in ammonia pressure is adjusted by opening and closing the valve.