JPH0481097B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to a high-temperature chemical heat pump system based on the hydrogenation and dehydrogenation reaction of an organic compound and a hydrogen storage alloy. Concerning high-temperature chemical heat pump systems with improved heat transfer and operating characteristics at 250-400℃.

(Prior Art) A heat pump is a type of energy-saving equipment that pumps heat from a low-grade (low-temperature) heat source and obtains high-grade (high-temperature) heat with a small amount of power.
There are two types of heat pumps: a power-driven compression type that requires a compressor, and a heat-driven absorption type that requires cooling water. These are mainly used for heating and cooling homes and buildings.

In recent years, as demand for industrial heat pumps has increased, large-sized devices capable of producing high-temperature output have become commercially available. However, the target temperature for pumping is 80°C or lower, and the upper limit of the pumping temperature is around 180°C. At temperatures higher than this, the refrigerant and absorption liquid tend to decompose and corrode, and it is also mechanically demanding, making it difficult to put it into practical use. Heat pumps that use chemical reactions for absorption and heat generation are called chemical heat pumps. For inorganic compounds, heat pumps that utilize hydrogen absorption and release from hydrogen-absorbing alloys have reached the stage of practical use, but they suffer from poor heat transfer properties because the reaction is a gas-solid reaction, and the pulverization of solids during repeated reaction operations. There are various problems such as the progress of the process and the need for complicated valve operations. For organic compounds, there are no heat pumps that can handle heat above 100℃.

Heat storage is generally stored in the form of hot water, but the heat storage temperature is low. Other methods being studied include chemical heat storage that utilizes chemical reactions and methods that utilize heat of fusion. However, there are few fluid-based ones that can store heat of 200°C or more and none that have been put to practical use in industry.

(Problems to be solved by the invention) As mentioned above, conventional heat pumps cannot utilize high-temperature heat, and have problems with operability such as heat transfer characteristics and pulverization of solids. Those with a systematic heat storage function have not been put to practical use in industry.

The problem that this invention aims to solve is that it can utilize high-temperature heat that cannot be achieved with conventional heat pumps, has a heat storage function, and is a fluid system as a whole, making it a highly operable system for industrial waste disposal. The goal is to recover heat over a wide range of areas and use energy effectively.

(Means for Solving the Problems) As a result of intensive research to solve the above problems, the present inventors have discovered that the hydrogenation/dehydrogenation reactions of organic compounds that proceed in the presence of a catalyst can be used to generate heat from heat pumps. It is used for the heat absorption function, and the reaction of absorption and release of hydrogen by the hydrogen storage alloy is used in place of a compressor to configure a heat pump, and the liquid organic compound involved in the reaction is used as a dispersant for the hydrogen storage alloy. Therefore, the present invention has been achieved by providing a high-temperature chemical heat pump system characterized in that the reaction between the alloy and hydrogen is carried out in a fluidized state.

In other words, in this invention, the chemical heat pump system uses a reaction type or an endothermic reactor for carrying out a gas phase or liquid phase dehydrogenation reaction of the reversible reaction, an exothermic reactor for carrying out the gas phase or liquid phase hydrogenation reaction of the reversible reaction, and the reversible reaction disposed between them; It is equipped with a hydrogen absorber that absorbs hydrogen at low pressure using a slurry of a hydrogen storage alloy using a mixture of organic compounds as a dispersant, and a hydrogen release device that releases hydrogen at high pressure using a slurry of the hydrogen storage alloy. A heat exchanger is installed between the reactors, and the outflow gas or liquid from the endothermic reactor is sent to the hydrogen absorber via the heat exchanger and condenser to liquefy organic compounds and absorb hydrogen gas, and the slurry in the hydrogen absorber is transferred to the compressor and The slurry from the hydrogen ejector is sent to the inlet of the hydrogen ejector via a heat exchanger, and after the hydrogen is released, the slurry from the hydrogen ejector is returned to the hydrogen absorber via the heat exchanger, and the gas or liquid effluent after hydrogen release is filtered to separate solids if it is a liquid. After separation, it is sent to the exothermic reactor inlet via a heat exchanger,
High-temperature chemical production by hydrogenation and dehydrogenation reactions of organic compounds and hydrogen-absorbing alloys, characterized in that the gas or liquid discharged from the outlet of the reactor is returned to the endothermic reactor via a heat exchanger and the reaction of the above reaction formula is repeated. It is a heat pump system.

This high-temperature chemical heat pump system consists of a heat pump system (hereinafter referred to as an organic compound system) and a compression system (hereinafter referred to as a hydrogen storage alloy system).

In the case of organic compounds, the above reaction formula (1): ΔH=49.5 Kcal/mol or the above reaction formula (2): ΔH=28.1 Kcal/mol is used as a reversible organic chemical reaction. That is,
This is a case where the dehydrogenation reaction of cyclohexane or tetrahydroquinoline is used in an endothermic system, and the hydrogenation reaction of their products benzene or quinoline is used in an exothermic system. In addition, in order to raise the temperature using these reversible reactions, it is necessary to perform the hydrogenation reaction under pressure.

FIG. 3 shows the relationship between equilibrium composition and reaction temperature with pressure as a parameter for the benzene-cyclohexane system. In Figure 9, when hydrogen is added in an amount 10 times the stoichiometric ratio to benzene, the pressure
This shows that when a gas with a composition (benzene/(benzene + cyclohexane) = 0.05) is reacted at 250°C under a reduced pressure of 0.03 MPa (0.31 Kg/cm ² ), an endothermic dehydrogenation reaction of cyclohexane proceeds and the composition becomes 0.7. The pressure is 2.0MPa (20.39Kg/cm ² )
This shows that when a gas with a composition of 0.7 is reacted at 367°C under a pressure of , an exothermic hydrogenation reaction of benzene proceeds and the composition becomes 0.05. By repeating this process, the temperature can be raised from 250°C to 367°C. However, this requires compression work from 0.03 MPa to 2.0 MPa.

Next, the hydrogen storage alloy system will be described. The reaction system is pressurized using a hydrogen storage alloy in which an organic compound represented by the reaction formula (1) or (2), i.e., a benzene-cyclohexane system or a quinoline-tetrahydroquinoline system is dispersed in a slurry form as a dispersant. Used as a reversible reaction of absorption and release of hydrogen. The reactions that can be used are shown below.

ZrMn ₂ +1.73H ₂ ZrMn ₂ H _3.46 ΔH = −9.3Kcal/molH ₂ (3) LaNi ₅ +3H ₂ LaNi ₅ H _6.0 ΔH = −7.2Kcal/molH ₂ (4) V+H ₂ VH ₂ ΔH = −9.6Kcal/ molH ₂ (5) TiCo _0.5 Fe _0.5 +0.6H ₂ TiCo _0.5 Fe _0.5 H _1.2 ΔH = -10.1Kcal/molH ₂ (6) These reactions are inert to the organic compounds used and the required It is necessary to have a hydrogen decomposition pressure of .

In this invention, the hydrogen storage alloy has the formula
At least one substance selected from the group consisting of substances represented by ZrMn ₂ , LaNi ₅ , V and TiCo _0.5 Fe _0.5 is preferable, especially LaNi ₅ and ZrMn ₂
is preferred.

The heat pump system of the present invention will be explained in more detail with reference to FIG. 1 showing its flowchart and FIG. 2 showing its cycle diagram. Figure 1 shows the case where cyclohexane-benzene is used as the organic compound and the various hydrogen storage alloys mentioned above are used as the hydrogen storage alloy system, and Figure 2 shows the hydrogen storage alloy used in the heat pump system shown in Figure 2. An example is shown in which ZrMn ₂ is used as the material.

As shown in FIG. 1, the heat pump system of the present invention includes a hydrogen absorption reactor, which constitutes a hydrogen storage alloy-based reactor, between an endothermic reactor 1 and an exothermic reactor 2, which constitute an organic compound-based reactor. A hydrogen emitting device 3 and a hydrogen emitting device 4 are arranged, and heat exchangers 5, 6,
7, 8 and others are arranged.

The endothermic reactor 1 was equipped with a stationary phase 9 supporting a normal gas phase dehydrogenation catalyst, and the pressure pl was 0.009 MPa (0.09 MPa).
When an organic gas consisting of a small amount of benzene and a large amount of cyclohexane is passed through ^the stationary phase at a temperature Tl of 250°C, the dehydrogenation reaction of cyclohexane proceeds and 70% of the organic gas becomes benzene. becomes. This endothermic reaction absorbs heat Ql from the outside. The produced gas exits this reactor 1 and passes through line 10.
The organic gas passes through the reactor 1 and reaches the heat exchanger 5, where it exchanges heat with the organic gas that returns to the same reactor 1 via the line 11. It is then liquefied in the condenser 12 and enters the hydrogen absorber 3.

It is preferable to use a Vycor reactor 14 equipped with a porous Vycor glass tube 13 as shown in FIG. 4 as the endothermic reactor 1. For example, if the inner diameter of this tube 13 is 14.4 mm, there is a
A catalyst stationary phase 9 consisting of 11 g of Pt/Al ₂ O ₃ is provided, and when cyclohexane and N ₂ are introduced from the inlet 15a and passed through the stationary phase 9, hydrogen generated by dehydrogenation is selectively transferred from the reaction system to the glass tube 13. Since it is removed through the wall, a reaction rate exceeding the equilibrium value is obtained. Produced gases other than hydrogen exit from the lower outlet 15b.

Now, in FIG. 1, the hydrogen absorber 3 is
It is a slurry made by dispersing a hydrogen storage alloy in an organic compound liquid having almost the same composition as the organic gas liquefied in the condenser 12, that is, a benzene-cyclohexane mixture, and its concentration is determined by the operating conditions of this heat pump system. . Here, the low-pressure hydrogen reacts with ZrMn ₂ in the absorber 3 at 31° C. to form ZrMn ₂ H _3.46 . In addition, as the endothermic reactor 1, a Vycor reactor 1 as shown in FIG.
4, in order to quickly remove permeated hydrogen, the vapor of the organic substance in the hydrogen absorber 3 is passed through the line 16b, the pump 17, and the heat exchanger 8 to the side pipe 18.
The hydrogen gas can be sent to the hydrogen absorber 3 through the heat exchanger 8 through the line 16a together with the hydrogen gas, and the hydrogen gas can be absorbed there.

The slurry solution in the hydrogen absorber 3 is fed through the line 19a.
The hydrogen is then pressurized to 1.1 MPa (11.2 Kg/cm ² ) by the compressor 20, heated by the heat exchanger 6, and then enters the hydrogen emitting device 4. In No. 4, hydrides are separated by heating at 203°C and high pressure hydrogen of 1.1 MPa is generated. At this time, the organic solvent is in a state close to its boiling point, and benzene and cyclohexane are generated along with hydrogen.
This high-pressure reaction gas is heated in a heat exchanger 7 via a line 21 and then led to an exothermic reactor 2 for hydrogenation of benzene. Here, an exothermic reaction proceeds in the presence of the nickel-silica catalyst stationary phase 22. When the reaction temperature is 367℃, benzene in the organic gas is 10%
The reaction proceeds until The generated gas passes through line 11, recovers heat in heat exchangers 7 and 5, recovers power in turbine 23, and then enters endothermic reactor 1 again. The amount of heat generated in the hydrogen absorber 3 is Q _Ml , the amount of heat absorbed in the hydrogen releaser is Q _Mh , and the amount of heat generated in the exothermic reactor is Q _h.
Indicated by Therefore, the temperature of the entire system is 203℃.
This means that heat of 250℃ and 367℃ and 31℃ were generated. Note that the slurry in the hydrogen release device 4 is circulated through the line 19b, the heat exchanger 6, the pressure reducing valve 24, and the hydrogen absorber 3.

A cycle diagram of the heat pump system described above (particularly using ZrMn ₂ ) is shown in FIG. Here, MH ₂ →M+H ₂ represents formula (3), C _B = P _B /P _B + P _C , Th = 640K (367°C), T _l = 523K (250°C), T _Mh =
476K (203℃), T _Ml = 304K (31℃), Ph = 1.1MPa,
P _l =0.009MPa, R ₁ , R ₂ , M ₁ , M ₂
are the temperature and pressure conditions of endothermic reactor 1, exothermic reactor 2, hydrogen absorber 3, and hydrogen desorber 4, respectively.
T _l , P _l ; T _h P _h ; T _Ml , P _Ml = P _l ; T _Mh , P _Mh = P _h .

Endotherms of Q _l and Q _Mh occur in R ₁ and M ₂ , respectively, and Q _h in R ₂ and M ₁ , respectively.
It is shown that an exotherm of Q and Q _Ml occurs.

Regarding the flow sheet in Figure 1, various alloys,
The thermal efficiency η _H and exergy efficiency η _E of the system at operating conditions are defined as:

η _H = Q _h / (Q _Mh + Q _l ) (7) η _E = Q _h (T _h −To) / T _h /Q _Mh (T _Mh − To) / T
_Mh +Q _l (T _l −To) / T _l (8) The following is an ideal scenario assuming that there is no heat loss in the heat exchanger and reactor, and that the circulating power can be covered by the power recovered by the turbine 23. It is a value. FIG. 5 shows the relationship between thermal efficiency η _H and exergy efficiency η _E with respect to heat extraction temperature when ZrMn ₂ is reacted at a stoichiometric ratio of hydrogen and benzene. 49% when the reaction temperature at high temperature is around 300℃
shows a certain thermal efficiency at 375°C, but beyond that, the equilibrium conversion rate decreases and the thermal efficiency also decreases.
It will be around 40% in the vicinity.

FIG. 6 is an example in which LaNi ₅ is used as the hydrogen storage alloy. It can be seen that as the operating pressure of the high-temperature exothermic reaction is increased, it becomes more advantageous to extract heat at a higher temperature. In addition, overall higher thermal efficiency than the ZrMn ₂ system is obtained (the ratio of hydrogen to benzene is the same as in Figure 5).

Even when reaction formula (2) is used as an organic compound system,
This is almost the same as the case using the reaction formula (1), but the organic compound is in the liquid phase in the endothermic reactor 1 and the exothermic reactor 2 because the boiling points of quinoline and tetrahydroquinoline are high. Accordingly, the effluent from the hydrogen emitter 4 is separated from the hydrogen storage alloy in a suitable filtration device before being sent to the exothermic reactor 2.

(Effects of the Invention) As described above, the present invention is a chemical heat pump system that utilizes a combination of the hydrogenation/dehydrogenation reaction of an organic compound, benzene or quinoline, and the hydrogen absorption/release reaction of a hydrogen storage alloy. 250
Exhaust heat utilization temperature in °C, 250~400℃, normal 300~450℃
For example, it is possible to raise the temperature to around 350°C using process waste heat of around 250°C (exhaust gas sensible heat from large combustion furnaces, solid sensible heat from steel plants, etc.) as a heat source. This is a high-temperature chemical heat pump system.

Moreover, organic compounds and inorganic hydrogen compounds not only serve as heat storage as they are, but also can be transported because they are fluid systems. Furthermore, since the hydrogen storage alloy is reacted in the form of a slurry with the organic compound used, the heat transfer characteristics and operational characteristics are improved. Moreover, the thermal efficiency of this system, especially when using a Vycor type reactor, reaches 40-50%.

At present, there is no high-temperature heat pump having such a configuration and effect, and the present invention is industrially extremely useful as an energy-saving device.

[Brief explanation of the drawing]

Figure 1 is a flowchart of the heat pump system of the present invention, Figure 2 is a cycle diagram of the heat pump system of Figure 1, and Figure 3 is the equilibrium composition and reaction temperature with pressure as a parameter in the heat pump system of the present invention. Graph showing the relationship between
The figure shows a Vycor reactor that can be used as an endothermic reactor in the present invention, and Figure 5 is a graph showing the relationship between thermal efficiency η _H and exergy efficiency η _E with respect to heat extraction temperature when ZrMn ₂ is used in the present invention. , 6th
The figure is a similar graph when LaNi ₅ is used instead of ZrMn ₂ in FIG. 1... Endothermic reactor, 2... Exothermic reactor, 3...
Hydrogen absorber, 4... Hydrogen release device, 5, 6, 7, 8
... Heat exchanger, 9 ... Stationary phase, 10, 11 ... Line, 12 ... Condenser, 13 ... Vycor glass tube, 14 ... Vykor reactor, 15a
...Inlet, 15b...Outlet, 15c...Thermocouple,
16a, 16b...Line, 17...Pump, 1
8...Side pipe, 19a, 19b...Line, 20...
... Compressor, 21 ... Line, 22 ... Stationary phase, 2
3... Turbine, 24... Pressure reducing valve.

Claims (1)

[Claims] 1. Reaction formula, An endothermic reactor that performs the reversible gas-phase or liquid-phase dehydrogenation reaction represented by , an exothermic reactor that performs the reversible gas-phase or liquid-phase hydrogenation reaction, and the reversible reaction disposed between them. Each of the reactors described above is equipped with a hydrogen absorber that absorbs hydrogen at low pressure using a slurry of a hydrogen storage alloy using a mixed liquid of an organic compound as a dispersant, and a hydrogen release device that releases hydrogen at high pressure using the slurry of the hydrogen storage alloy. , a heat exchanger is provided between the hydrogen absorber and the hydrogen releaser, and the fluid flowing out from the endothermic reactor is sent to the hydrogen absorber via the heat exchanger and the condenser, and the hydrogen gas is absorbed. The slurry is sent through a compressor and a heat exchanger to a hydrogen desorber, where after hydrogen is released, the slurry is returned to the hydrogen absorber through a heat exchanger, and after separating solids from the fluid effluent, the heat exchanger is Hydrogen in an organic compound and a hydrogen storage alloy is characterized in that the hydrogen is sent to an exothermic reactor through a heat exchanger, and the outflow fluid from the exothermic reactor is returned to an endothermic reactor through a heat exchanger to repeat the reaction according to the reaction formula. High-temperature chemical heat pump equipment that uses hydrogenation and dehydrogenation reactions. 2 reaction formula, An endothermic reactor that performs the reversible gas-phase or liquid-phase dehydrogenation reaction represented by , an exothermic reactor that performs the reversible gas-phase or liquid-phase hydrogenation reaction, and the reversible reaction disposed between them. Each of the reactors described above is equipped with a hydrogen absorber that absorbs hydrogen at low pressure using a slurry of a hydrogen storage alloy using a mixed liquid of an organic compound as a dispersant, and a hydrogen release device that releases hydrogen at high pressure using the slurry of the hydrogen storage alloy. , a heat exchanger is provided between the hydrogen absorber and the hydrogen releaser, and the fluid flowing out from the endothermic reactor is sent to the hydrogen absorber via the heat exchanger and the condenser, and the hydrogen gas is absorbed. The slurry is sent through a compressor and a heat exchanger to a hydrogen desorber, where after hydrogen is released, the slurry is returned to the hydrogen absorber through a heat exchanger, and after separating solids from the fluid effluent, the heat exchanger is Hydrogen in an organic compound and a hydrogen storage alloy is characterized in that the hydrogen is sent to an exothermic reactor through a heat exchanger, and the outflow fluid from the exothermic reactor is returned to an endothermic reactor through a heat exchanger to repeat the reaction according to the reaction formula. High-temperature chemical heat pump equipment that uses hydrogenation and dehydrogenation reactions. 3 Hydrogen storage alloys have the formulas ZnMn ₂ , LaNi ₅ , V and
The device according to claim 1 or 2, wherein the device is at least one substance selected from the group consisting of substances represented by TiCo _0.5 and Fe _0.5 . 4. The apparatus according to claim 1, 2 or 3, wherein the endothermic reactor is a Vycor reactor. 5. The endothermic reactor is equipped with a gas phase dehydrogenation fixed catalyst bed,
The temperature is maintained at 200-250℃, the reactor pressure is maintained in the range of reduced pressure to normal pressure by a hydrogen absorber, and the exothermic reactor is equipped with a gas phase hydrogenation fixed catalyst bed, and the temperature is maintained at 250-400℃. The apparatus according to claim 1 or 3, wherein the reactor pressure is maintained in the range of 10 to 20 kg/cm ² by means of a hydrogen emitting device.