CA2415282A1 - Ammonia absorption type water chilling/heating device - Google Patents

Abstract

An ammonia absorption type water chilling/heating device comprising a generator (22) for generating high pressure ammonia gas (21) from an aqueous ammonia solution (11) by a heat source, a rectifier (28) for gas-liquid separation to provide the ammonia gas (21) and a dilute ammonia solution (9), a condenser (23) for condensing the ammonia gas (21) after separation, an evaporator (24) utilizing the cooling action produced when an ammonia solution (94) after condensation is vaporized, and an absorber (25) for causing the aqueous ammonia solution to absorb the ammonia gas (21) after vaporization, these parts being successively arranged from top so that the dilute ammonia solution (9) may move by gravity. Such arrangement allows omission of a rectifying tower and connection piping, and reduces the size of the evaporator and absorber, thus making it possible to further reduce the size of the entire device and to cope with a variety of heat sources.

Description

t TECHNICAL FIELD
The present invention relates to an ammonia absorption type water chilling/heating device which takes advantage of a variety of exhaust heats such as the gas turbine exhaust heat, reciprocating heat engine exhaust heat, fuel cell exhaust heat, solar electric power generation exhaust heat, and excess steam of a boiler, as well as geothermal power and hot dry rock, and which is applied to a small-scale apparatus having a refrigerating capacity of the order of not higher than several hundred kW.
BACKGROUND ART
Conventionally, an ammonia gas generating and rectifying unit in an ammonia absorption type water chilling/heating device in steam boiling mode is constituted as shown in Figure 9. In Figure 9, a concentrated ammonia aqueous solution 11 is fed into a liquid-filling-up type generator 10, through a feed opening 20 for concentrated ammonia aqueous solution arranged at an end portion of the generator, by use of a pump not shown in the figure; a number of heat exchangers 12 are arranged in the ammonia aqueous solution 11, a heat source such as steam and hot water is fed through a heat source feed opening 13, and thereby vaporized ammonia gas 21 is generated from the ammonia aqueous solution 11. The ammonia gas 21 and a simultaneously generated, small amount of water vapor go up into a rectifying tower 16 arranged to be upright in the central portion of the generator 10.
A plurality of shelves or a plurality of spiral shelves 17 each with a central opening are arranged in the interior of a rectifying tower 16, where the coming up ammonia gas 21 and moisture are separated by gravitation and density difference, and the ammonia gas 21 thus rectified is delivered via an outlet 39 for ammonia gas into a condenser not shown in the figure. The dilute ammonia solution containing a trace amount of ammonia liquefied in the shelves 17 flows down into a liquid pool 18 and is delivered to an opening 15 for discharging dilute ammonia solution via a drain pipe 19, and is transferred as a dilute ammonia solution to an absorption liquid pump and the like.
There have been found the following problems in the conventional ammonia absorption type water chilling/heating devices as described above which uses an ammonia gas generator and a rectifier.
(1) The rectifying tower 16 is arranged at an outlet of the generator 10, and the gas-liquid separation is performed only by use of the gravitation and density difference available when the ammonia gas 21 going up by heating passes through the shelves 17 arranged in the interior of the rectifying tower 16, so that the height of the generator 10 and that of the rectifying tower 16 are great.
(2) There is a severe constraint in the temperature range of the heat source fed to the generator 10; when the temperature range deviates from the design point, the performance is drastically degraded, and hence it has been difficult to take advantage of various types of exhaust heat. Consequently, broad and rapid response have been impossible to the variations in feed rate of heat flow and temperature.

(3) A liquid-filling-up type generator 10 has a large volume, so that the reserved amount of liquid is large, and accordingly the start-up time and the response time to the heat load variation are elongated.

(4) In a conventional absorption type water chilling/heating device, the pressure vessels for an absorber, an evaporator, a condenser, etc. are transversely mounted, and these vessels are connected with pipes and valves in a complex manner, and accordingly there have been problems that the device as a whole becomes large in scale, there are a few components common to these vessels, in addition there are caused fluidic losses in pipes and valves, and furthermore the pipes are exposed outside the device body.

(5) The dilute ammonia solution obtained from the opening 15 for discharging dilute ammonia solution passes through a liquid preheater for liquid not shown in figure, subsequently is fed into the absorber via a pressure reducing valve; the ammonia solution entering the condenser is supercooled at the outlet of the evaporator by the cooling effect of the ammonia gas, and the absorber is imposed so large a heat load that it is large in scale.

(6) The dilute ammonia solution is depressurized at the upper side of the absorber, and subsequently absorbs the ammonia gas, while coming down in a shower-like manner, on the droplet surface; the droplet size is large and accordingly the gas absorption surface area is small so that the absorber is large in scale.
A first object of the present invention is the overall size reduction of the device through omission of the rectifying tower and the connecting pipes and through size reduction of the generator, absorber, and the like, and the provision of an ammonia absorption type water chilling/heating device which can adapt to a variety of heat sources.
A second object of the present invention is to provide a device which can achieve the effects of being adaptable to a variety of temperature ranges and a variety of fluid flow ranges of the heat source fluid; being responsive to the sharp time variation of the heat source load; and being responsive to the time variation of the cooling load, and other effects; through feeding a nonazeotropic mixture solvent (ammonia aqueous solution) to the inner wall surface of a heat exchanger pipe by using a heat exchanger pipe, where only a low boiling point fluid (ammonia) is vaporized to move into the central part of the heat exchanger pipe, and a high boiling point fluid (water) moves along the inner wall surface of the pipe, owing to the centrifugal force and surface tension.

A third object of the present invention is to provide a device in which the separation into the dilute ammonia solution and the ammonia gas can be performed without fail; and subsequently to the separation, the dilute ammonia solution exchanges its heat, when the solution passes through the liquid preheater, effectively with the concentrated ammonia aqueous solution passing through the interior of the solution pipe so that the heat is transferred to the cooler of the evaporator.
A fourth object of the present invention is to provide a device in which the absorber can be reduced in scale, even when the evaporator does not work to a full extent, by allowing the ammonia aqueous solution to come down in excess into the absorber; and in addition, when the evaporator works to a full extent, the absorber can be reduced in size, by allowing the dilute solution to be subjected to the heat exchange through the heat exchanger.
A fifth object of the present invention is to provide a device in which the absorption of the ammonia gas can be promoted as a result of upgrading the cooling effect through heat exchange with the cooling water passing through the cooling pipe, by spraying the dilute ammonia solution, subjected to the heat exchange by means of the heat exchanger in the evaporator, to the cooling pipe of the absorber.
A sixth object of the present invention is to provide a device in which the ammonia gas and the ammonia solution can be transferred to the absorber, while both being stirred vigorously to be mixed together and for the ammonia gas to be absorbed, through making the droplet size as small as possible by spraying under a high pressure, without reducing the pressure, when the dilute ammonia solution is sprayed by means of a sprinkler.
A seventh object of the present invention is to provide a unit in which the circulation is performed without using an instrument such as a pump, but by sucking up to spray the ammonia aqueous solution in the absorber under favor of the negative pressure generated when the dilute ammonia solution is sprayed by means of a sprinkler.
An eighth object of the present invention is to provide a device in which the safety against the break and leak of the solution pipe can be improved by placing the solution pipe in the center of the device body which pipe is used for 5 compressive transfer of the concentrated ammonia aqueous solution and is subjected to the highest pressure.
The other objects and effects of the present invention will be made clear by describing the best mode for carrying out the present invention with reference to the specification and drawings.
DISCLOSURE OF THE INVENTION
The present invention is an ammonia absorption type water chilling/heating device characterized in that: the device is constructed by arranging successively from the top the following components: a generator 22 which generates a high pressure ammonia gas 21 from an ammonia aqueous solution 11 under favor of the heat source, a rectifier 28 which performs the gas-liquid separation into the ammonia gas 21 and a dilute ammonia solution 9, a condenser 23 which condenses the high pressure ammonia gas 21 having been subjected to the gas-liquid separation, an evaporator 24 which takes advantage of the cooling action produced when a high pressure ammonia solution 94 is vaporized under reduced pressure subsequently to the condensation, and an absorber 25 which makes the dilute ammonia solution 9 absorb the ammonia gas 21 having been vaporized; and by arranging a solution pipe 30, for compressive transfer of the ammonia aqueous solution 11 from the absorber 25 to the generator 22, in the interior of these components.
Additionally, the present invention can reduce the device in scale as a whole, by omitting the connection piping connecting the five processes through the following arrangement: a generator outer cylinder constituting the generator, a rectifier outer cylinder constituting the rectifier, a condenser outer cylinder constituting the condenser, an evaporator outer cylinder constituting the evaporator, and an absorber outer cylinder constituting the absorber are successively and vertically superposed and fixed to form a stacked structure;
the solution pipe, for compressive transfer of the ammonia aqueous solution from the absorber to the generator, is arranged in the central parts of these components; and a top cover 41 is placed on the top of the outer cylinder for use in the generator. Additionally, common components grow in number, and accordingly can be supplied inexpensively owing to the mass productivity.
Furthermore, there is no need to make the thermal insulation work for the pipes and valves, and the fluidic loss can also be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an explanatory diagram showing an overall view of a first Example of the ammonia absorption type water chilling/heating device according to the present invention;
Figure 2 is a sectional view showing the specific examples for a generator 22 and a rectifier 28 in Figure 1;
Figure 3 is a sectional view showing the specific examples for a rectifier 28 and a condenser 23 in Figure 1;
Figure 4 is a sectional view showing the specific examples for an evaporator 24 and a supercooler 95 in Figure 1;
Figure 5 is a sectional view showing the specific examples for an absorber 25 and liquid pool 29 in Figure 1;
Figure 6 is a sectional view showing one example of a heat exchanger pipe 27 in Figure 2;
Figure 7 is a sectional view showing another example of the generator 22 according to the present invention;
Figure 8 shows an example of a diffusion nozzle 44 in Figure 7, (a) being a front view and (b) a sectional view;

Figure 9 is an explanatory diagram for an ammonia gas generating and rectifying unit in a conventional ammonia absorption type water chilling/heating device;
Figure 10 is an explanatory diagram showing an overall view of a second Example of the ammonia absorption type water chilling/heating device according to the present invention;
Figure 11 is a sectional view of the relevant part showing the specific example for the generator 22 in Figure 10;
Figure 12 is a sectional view showing one example of the heat exchanger pipe 27 in Figure 10;
Figure 13 is a sectional view of the relevant part showing the specific examples for the rectifier 28 and condenser 23 in Figure 10;
Figure 14 is a plan view showing the specific examples of a cooling pipe 32, refrigerating pipe 34, and cooling pipe 37 in Figure 10;
Figure 15 is a sectional view of the relevant part showing another specific example of the generator 22 in Figure 10;
Figure 16 is a plan view of the heat exchanger pipe 27 in Figure 15; and Figure 17 is a sectional view showing a unit in which the circulation of the ammonia aqueous solution in the absorber 25 in Figure 10 is performed under favor of the negative pressure generated by a sprinkler 36.
Description will be made below of a first Example of the present invention on the basis of Figures 1 to 8.
In Figure 1, a generator 22, a rectifier 28, a condenser 23, an evaporator 24, an absorber 25 and a liquid pool 29 are all of the cylindrical shapes with the same diameters; these components are successively disposed in the described order, from top to bottom, in a stacked structure so that these components work as an ammonia absorption type water chilling/heating device while an ammonia aqueous solution 11 falls freely by gravitation.
More specifically, a liquid pool 29 equipped with a pump 38 is arranged at the lowermost end, and a solution pipe 30 connected to the discharge opening of the pump 38, which pipe is used for pumping to transfer the concentrated ammonia aqueous solution 11, is made to extend straightforwardly up to the generator 22 arranged on the top floor. In the generator 22, the solution pipe 30 is connected, via a heat source flow 26 and a heat exchanger pipe 27, to the rectifier 28. In the condenser 23, the dilute ammonia solution 9 is introduced into a liquid preheater 31, while the ammonia gas 21, on contact with a cooling pipe 32, turns into the concentrated ammonia solution 94. The ammonia solution 94 is sprayed into the evaporator 24, via an expansion valve 33.
Incidentally, the pump 38 may be arranged either inside or outside the liquid pool 29.
In the evaporator 24, the dilute solution containing a trace amount of ammonia is transferred, via the liquid preheater 31, to a sprinkler 36 to be sprayed under a high pressure.
The ammonia gas 21, having been expanded and vaporized by the expansion valve 33, cools the brine present in the interior of a refrigerating pipe 34 installed in the evaporator 24, and subsequently comes up again to cool a supercooler 95, resulting in cooling the ammonia solution 94 in the condenser 23 to a temperature not higher than the boiling point, and furthermore the ammonia gas 21 is mixed with and absorbed in the sprayed dilute ammonia solution 9, which solution, in the absorber 25, makes the solution pipe 30 work as an absorption heat recovery device 96, and releases the absorption heat on contact with the cooling pipe 37, and is again made to return to the liquid pool 29.
More detailed description will be made of the specific configuration of the generator 22 on the basis of Figure 2.
A top cover 41 is placed on the top end of a generator round outer i cylinder 40 constituting the generator 22, and is fixed to the generator outer cylinder 40 with screws through the flanges 48. The lower end of the generator outer cylinder 40 is fixed to the condenser outer cylinder 67 of the condenser 23 with screws through the flanges 48 with the partion plate 49 and the bottom plate 51 therebetween.
In the central part of the top cover 41, a heat source feed pipe 42 is arranged, 'and the top end of the pipe is the heat source feed opening 13, and a discharge opening 14 is arranged on a side portion of the top cover 41.
A round inner cylinder 43 is housed in the interior of the generator outer cylinder 40, with a heat insulating material 72 interposing therebetween except for the top clearance; in the interior of the inner cylinder 43, a number of heat exchanger pipes 27 are arranged in such a way that the pipes are supported by the top and bottom plates of the inner cylinder 43, and are arranged vertically with clearances between the pipes. Incidentally, the inner cylinder 43 is partitioned into several compartments with supporting plates 46 having holes and arranged radially; in every compartment, several hundred of thin heat exchanger pipes 27 are housed, and hence, in total, one thousand thin heat exchanger pipes 27 or more are arranged. However, for the convenience of drawing, the diameter of a heat exchanger pipe 27 is enlarged in relation to the diameter of the inner cylinder 43, and the number of the pipes is diminished.
The top ends of the heat exchanger pipes 27 protrude from the upper side of the top plate of the inner cylinder 43, and every protrusion is equipped with a diffusion nozzle 44 as shown in Figure 6; a cover 54 is placed in the portion where the diffusion nozzles 44 are arranged for the purpose of forming a liquid pool chamber 55. Additionally, the bottom end of a heat exchanger pipe 27 has an opening in the bottom plate of the inner cylinder 43.
The diffusion nozzle 44 is also referred to as a swirler, and wicks or grooves are formed on the inner wall of the heat exchanger pipe 27, so that the ammonia aqueous solution 11 is sprayed into the heat exchanger pipe 27 through the diffusion nozzle 44, and can be stably deposited on the wall surface.
The heat source is fed into the interior of the inner cylinder 43, housing the. heat exchanger pipes 27, from the lower end of the heat source feed pipe 42;
5 the heat source passes through the clearances between the heat exchanger pipes 27 and a number of holes provided on the supporting plate 46 having holes, then moves from the discharge opening 47 arranged in an upper portion of the inner cylinder 43 by passing through the clearance in contact with the generator outer cylinder 40, and reaches the discharge opening 14 in a communicatively 10 connected manner.
A blowoff section 56 is formed in the central part of the partition plate 49, and the solution pipe 30 is communicatively connected and fixed to the bottom side of the blowoff section 56; the blowoff section 56 is communicatively connected to the liquid pool chamber 55 via a communicative connection hole 57 and a plurality of liquid delivering pipes 53 arranged around the heat source feed pipe 42.
A plurality of diffusion nozzles 52 are arranged along the periphery of the partition plate 49, which nozzles generate spiral flow in the rectifier 28 formed by the partition plate 49, a bottom plate 51, and the outer cylinder part associated with the bottom plate 51. A plurality of vertical, gas passage pipes 50 are arranged in the bottom plate 51 of the rectifier 28 in a vertically penetrated manner, and the bottom plate 51 is communicatively connected to the liquid fall opening 58 arranged around the periphery of the solution pipe 30.
Detailed description will be made of the condenser 23 with reference to Figure 3.
As for a condenser outer cylinder 67 of the condenser 23, as described above, the top end of the outer cylinder part of the rectifier 28 is fixed through flanges 48 to the generator outer cylinder 40; and the lower end is fixed through flanges 48 to the evaporator outer cylinder 70 of the evaporator 24, sandwiching between the flanges the outer cylinder part of the partition plate 61 in a supercooler 95.
In the central part of the condenser outer cylinder 67, the solution pipe 30 is arranged vertically, and a number of fins 59 are radially arranged vertically both in the outer and in the inner circumference of the solution pipe 30. The liquid preheater 31 is arranged in such a manner as to .wrap the outer circumference of the fins 59, a heat insulating material 60 is arranged on the inner wall of the liquid preheater 31 in such a way that a small clearance is formed between the heat insulating material and the fins 59.
In the interior of the condenser outer cylinder 67, a plurality of stages of the spirally wound cooling pipe 32 are arranged with mutual clearances between stages under favor of a frame 66 for supporting the cooling pipes, and are connected to the cooling water outlet 65 via a cooling water port 63.
In the partition plate 61 of the lower end of the condenser outer cylinder 67, a plurality of expansion valves 33 are equipped around the outer circumference in such a manner as to face to the evaporator 24, and a number of supercoolers 95 are arranged inside the expansion valves 33, in such a manner as to protrude both to the bottom portion of the condenser 23 and to the top portion of the evaporator 24 and penetrate the partition plate 61.
The pressure is high (for example, from 15 to 16 atm) above the condenser 23 and low below the evaporator 24 (for example, from 3 to 5 atm), and hence the junction portion between the liquid preheater 31 and the partition plate 61 is provided with an intervening high pressure sealing material 62.
Detailed description will be made of the evaporator 24 with reference to Figure 4.
As for the evaporator outer cylinder 70 of the evaporator 24, as described above, the top end of the outer cylinder 70 is fixed through flanges 48 to the condenser outer cylinder 67; and the lower end is fixed through flanges 48 to the absorber outer cylinder 76 of the absorber 25, sandwiching between the flanges the partition plate 71.
In the central part of the evaporator outer cylinder 70, the solution pipe 30 and a heat exchanger 35 around the outer circumference of the pipe 30 are vertically arranged in continuation from the condenser 23. Additionally, in the central part of the partition plate 71, a partition cylinder 97 is vertically placed in an integrated manner, with sufficient clearance in relation to the heat exchanger 35. A sprinkler 36 is arranged in the bottom portion of the heat exchanger 35 of the evaporator 24, and the sprinkler 36 is so arranged that the dilute ammonia solution 9 contained under a high pressure in the heat exchanger 35 is jetted out downward. A nozzle valve adjustment ro.d 69, for use in adjusting the jet amount from the sprinkler 36, protrudes outside the evaporator outer cylinder 70.
Furthermore, an electric liquid level meter 68 is equipped on the inner wall of the heat exchanger 35 in order to detect the liquid level of the dilute ammonia solution 9 pooled between the heat exchanger 35 and the solution pipe 30, and the liquid level is displayed to the outside.
Between the evaporator outer cylinder 70 and a partition cylinder 97, a plurality of stages of the spirally wound refrigerating pipe 34 are arranged with mutual clearances between the stages under favor of a frame 66 for supporting the refrigerating pipes, and both the ends of the refrigerating pipe 34 are connected to the brine port 77; a connection pipe 64 on the outlet side is so connected that the brine is delivered against the load, and a connection pipe on the inlet side is so connected that the brine heated by the load returns.
Incidentally, an ammonia solution 94 is pooled on the partition plate 71, and hence the ammonia solution 94 is discharged through a discharge opening 109 to a location near the sprinkler 36.
Detailed description will be made below of the absorber 25 and the liquid pool 29 with reference to Figure 5.
As for the absorber outer cylinder 76 of the absorber 25, as described x above, the top end of the outer cylinder 76 is fixed through flanges 48 to the evaporator outer cylinder 70; and the lower end is fixed through flanges 48 to the liquid pool outer cylinder 82 of the liquid pool 29.
In the central part of the evaporator outer cylinder 70, the solution pipe 30 is vertically arranged in continuation from the evaporator 24, and the absorption heat recovery device 96, constituted by the radially equipped vertical fins, is arranged around the outer circumference of the solution pipe 30.
In the interior of the absorber outer cylinder 76, a plurality of stages of the spirally wound cooling pipe 37 are arranged with mutual clearances between the stages under favor of a frame 66 for supporting the cooling pipes, both ends of the cooling pipe 37 are connected to the cooling water port 63, and the outlet portion is connected to the cooling pipe 32 of the condenser 23, while the inlet portion is connected to the cooling water inlet 75.
As for the liquid pool 29, the liquid pool outer cylinder 82 is fixed through the flanges 48 to the absorber outer cylinder 76 of the absorber 25, the pump 38 is put on the pedestal 92 placed in the center of the bottom 83, together with a filter 78, and the solution pipe 30 is connected to the pump 38.
Additionally, a liquid discharge pipe 81 in the bottom 83 is connected to the outside via a valve (not shown in the figure).
The pump 38 is connected to a motor $0 emplaced on the outside emplacement 93 via a shaft 79.
A liquid level meter 74 is vertically placed outside the absorber 25 in such a manner as to extend from the evaporator 24 to the liquid pool 29, and the liquid level meter 74 is communicatively connected, at both ends thereof, to the interior of the liquid pool outer cylinder 82 via communicative connection holes 73.
In the next place, description will be made below of the operation of the first Example according to the present invention.

In Figure 5, a concentrated ammonia aqueous solution 11 of the order of from 25 to 50% is fed inside the liquid pool outer cylinder 82 of the liquid pool 29.
The fed ammonia aqueous solution 11 is sucked in and compressively transferred to the solution pipe 30 by the pump 38. Meanwhile, dust and the like are removed with the filter 78.
In Figure 2, the ammonia aqueous solution 11 compressively transferred is delivered, from the top end of the solution pipe 30, to the blowoff section in the generator 22, and furthermore delivered to the liquid pool chamber 55 through the communicative connection hole 57 and via the liquid delivering pipe 53. Then, the solution 11 is fed into the heat exchanger pipes 27 through the diffusion nozzles 44.
In the interior of the generator 22, the heat source fed from the heat source feed opening 13 is fed into the interior of the inner cylinder 43 housing the heat exchanger pipes 27 via the heat source feed pipe 42, where the heat source exchanges heat and is discharged from the discharge opening 14.
Consequently, the ammonia aqueous solution 11, delivered from the liquid pool chamber SS via the diffusion nozzles 44 to the heat exchanger pipes 27, is atomized by the diffusion nozzles 44; the droplets thus atomized hit the inner wall of the heat exchanger pipe 27 owing to the centrifugal force, trapped by the wick on the inner wall owing to the surface tention, and fall down from the lower end as remaining to be liquid. The concentrated ammonia gas 21, which is not deposited to the inner wail, is discharged from the lower end as remaining to be a circular mist flow 45.
More specifically, a nonazeotropic mixture refrigerant (ammonia aqueous solution) is fed to the inner wall surface of the heat exchanger pipe through the diffusion nozzle 44 and the heat exchanger pipe 27 where the circular flow is generated, only the low boiling point fluid (ammonia) is vaporized and advected in the center of the heat exchanger pipe 27, and the high t boiling point liquid (water) is advected along the inner wall of the pipe owing to the centrifugal force and surface tension.
On the basis of the constitution as described above, the following effects can be achieved: the effect of being adaptable to various temperature 5 ranges and various flow ranges of the heat source fluid, the effect of being responsive to the sharp time variation of the heat source load, the effect of being responsive to the time variation of the cooling load, and other effects.
The mixture, composed of the dilute ammonia solution 9, which has been discharged from the heat exchanger pipes 27 of the generator 22 and 10 contains a trace amount of ammonia, with the concentrated (for example, 99.8%), high pressure ammonia gas 21, is transferred to the rectifier 28 through the diffusion nozzles 52 on the partition plate 49. The dilute ammonia solution 9 flows on the bottom plate 51 and falls into the liquid fall opening 58, while the high pressure ammonia gas 21 is exclusively separated, and 15 transferred to the condenser 23 through the gas passage pipes 50 with the circular flow being generated by the centrifugal force produced by the diffusion nozzle 52.
In Figure 3, the dilute ammonia solution 9 having fallen into the liquid fall opening 58 is transferred to the heat exchanger 35 of the evaporator 24, while transferring its heat, when passing through the liquid preheater 31, to the ammonia aqueous solution 11 passing through the interior of the solution pipe 30, through the heat exchange under favor of the fin 59.
The high pressure ammonia gas 21 having passed through the gas passage pipes 50 is condensed into the concentrated ammonia solution 94 by exchanging the heat, when passing through the cooling pipe 32 of the condenser 23, with the cooling water passing through the cooling pipe 32, and is transferred to the expansion valves 33.
In Figure 4, the concentrated ammonia solution 94 is expanded and vaporized by the expansion valve 33 into the ammonia gas 21, which,' when vaporized, cools the refrigerating pipe 34 of the evaporator 24, then again comes up along the partition cylinder 97 and cools the supercooler 95 resulting in cooling the concentrated ammonia solution 94 in the condenser 23 to a temperature not higher than the boiling point, and again comes down along the heat exchanger 35. Meanwhile, the brine in the refrigerating pipe 34 is cooled and a low-temperature heat is delivered to the load.
The dilute ammonia solution 9 delivered from the liquid preheater 31 is stored in the heat exchanger 35, where it is subjected to the heat exchange with the ammonia gas 21 coming down along the heat exchanger 35. The dilute ammonia solution 9, after having been cooled, is sprayed from the sprinkler 36 under a high pressure; the sprayed dilute ammonia solution 9 is vigorously stirred, is mixed with, and absorbs the ammonia gas 21 coming down and the ammonia solution 94 discharged from the discharge opening 109, and then is transferred to the absorber 25.
In Figure S, the dilute ammonia solution 9, having been subjected to the heat exchange by the heat exchanger 35 of the evaporator 24 in the preceding stage, is transferred into the cooling pipe 37 in the absorber 25, while the dilute ammonia solution 9 exchanges heat with the ammonia aqueous solution 11 in the solution pipe 30 through the absorption heat recovery device 96, and furthermore exchanges heat with the cooling water passing through the cooling pipe 37 to enhance the cooling effect, turning into the concentrated ammonia aqueous solution 11 and falling into the liquid pool outer cylinder 82 of the liquid pool 29 and being stored there. Again, the concentrated ammonia aqueous solution 11 is compressively transferred by the pump 38.
The above described Example, as shown in Figure l, takes advantage of the exhaust heat fed through the heat source feed opening 13; when the exhaust heat alone is insufficient in amount, combustion burners 84 for additional heating may be arranged in such a manner as to face onto the heat exchanger pipes 27 within the generator 22 to heat the exhaust heat from the heat source feed opening 13 as shown in Figure 7. Additionally, when no exhaust heat is available, the combustion burners 84 alone may be used as the heat source. On the inlet side of the heat exchanger pipe 27, for example, such diffusion nozzles 44 as shown in Figures 8(a) and 8(b) are equipped to perform gas-liquid separation through forming circular flow by a guide blade 91.
In Figure 7, reference numerals 85, 86, and 87 denote a partition plate, a bottom portion, and an evacuation fan, respectively. Additionally, a hot water supply heat exchanger 88 may be arranged in such a manner as to face onto the heat source feed opening 13 so that the water from a feed water pipe 90 is heated by the hot water supply heat exchanger 88 and is taken out from a warm water outlet 89.
In the next place, description will be made below of a second Example of the present invention on the' basis of Figures 10 to 17.
In Figure 10, a generator 22, a rectifier 28, a condenser 23, an evaporator 24, an absorber 25 and a liquid pool 29 are all of the cylindrical shapes with the same diameters; the second Example is nearly the same as the first Example in that: these components are successively disposed in the described order, from top to bottom, in a stacked structure so that these components work as an ammonia absorption type water chilling/heating device while an ammonia aqueous solution 11 falls freely by gravitation.
Description will be made of the general points in which the second Example is different from the first Example, with reference to Figure 10, and subsequently description will be made of the detailed points in which the second Example is different from the first Example with reference to Figure 11 and the subsequent figures. Description is omitted of those sections which are the same in structure as those of Figure 1.
In Figure 10, spiral corrugate pipes with inner-wall spiral grooves are used for the vertical heat exchanger pipes 27 and the central solution pipe 30 in the generator 22. Additionally, the heat source feed opening 13 of the generator 22 and the discharge opening 14 are arranged respectively at a lower and an upper position on the side face of the generator outer cylinder 40.
The rectifier 28 is constituted with a vertical cylinder plate 100 with holes having a top central opening and a bottom central opening in such a manner as to form a vertical through-hole and the metallic nets 101 vorticosely arranged around the plate 100 with holes.
The condenser 23, evaporator 24, and absorber 25 are, as described later, different in piping configuration from the first Example. Additionally, the cooling water ports 63 are of the horizontal type ,and are interposed between sections in a stacked structure.
The supercooler 95 is different from that in the first Example in that the structure is of the spiral pipe structure; a pair of the supercoolers 95 are disposed in such a manner as to sandwich one of the horizontal cooling water ports 63 and occupy the clearance associated with the upper and lower piping.
Additionally,.a selector valve 104 is arranged at the cooling water outlet 65 of the cooling water port 63 in the supercooler 95, and the selection is made as follows: when the cooling water outlet temperature (A) in the absorber 25 is higher than the cooling water outlet temperature (B) in the supercooler 95, the selector valve 104 is connected to the cooling water inlet 75 of the condenser 23, while when the cooling water outlet temperature (A) in the absorber 25 is not higher than the cooling water outlet temperature (B) in the supercooler 95, the selector valve 104 is connected to the cooling water outlet 65 of the condenser 23. Under favor of this selection, even when the temperature of the cooling water fed from the cooling tower 103 is varied largely, quick response to the variation is possible without deteriorating a refrigerating capacity, and accordingly the performance degradation caused by the change of the seasons and the change in the weather can be reduced.
In the second Example, the absorption heat recovery device 96 in the absorber 25 and the heat exchanger 35 in the evaporator 24, both found in the first Example, are eliminated.
Description will be made below of the more specific constitution of the generator 22 with reference to Figures 11 and 12.
The solution pipe 30 in the center of the generator outer cylinder 40 is covered with a protective pipe 98, a branching device 99 is connected to the top of the protective pipe 98, the top portion of the solution pipe 30 has openings in the interior of the protective pipe 98, a plurality of the liquid delivering pipes 53 are radially connected to the branching device 99, and the plurality of the liquid delivering pipes 53 are respectively made to approach the liquid pool chamber 55. The vertical heat exchanger pipes 27, each consisting of a plurality of members, are connected to the liquid pool chamber 55. The heat exchanger pipe 27 is, as shown in Figure 12, constituted with a spiral corrugate pipe with spiral grooves formed on the inner wall thereof and a diffusion nozzle 44 on the top end thereof. Incidentally, the solution pipe 30 is also made of a spiral corrugate pipe with spiral grooves formed on the inner wall thereof.
The heat source feed opening 13 and the discharge opening 14 are respectively connected at a lower position and an upper position on the side wall of the generator outer cylinder 40.
As shown in Figure 13, in the rectifier 28, a cylindrical body is formed with an inner cylinder made of the plate 100 with holes, a fleckless outer cylinder, a top plate, and a bottom plate; the gas passage pipe 50 is formed by arranging a plurality of layers of the metallic nets 101 wound vorticosely, for the purpose of separating the water vapor from the ammonia gas 21, in the interior of the cylindrical body; the top central opening and the bottom central opening of the plate 100 with holes work as the liquid fall opening 58; a gas passage 102 is formed by the path from the small holes in the liquid fall opening 58 through the interior of the gas passage pipes 50 to the periphery of the gas passage pipe, and the gas passage 102 is communicatively connected to the condenser 23.
As shown in Figure 13, in the condenser 23, the liquid preheater 31 is arranged in the central part of the condenser outer cylinder 67, and the spirally wound solution pipe 30 made of a spiral corrugate pipe is housed in the interior 5 of the liquid preheater 31. The cooling pipe 32 is housed between the condenser outer cylinder 67 and the liquid prehetaer 31, the cooling water port 63 is arranged above the cooling pipe 32, and the supercoolers 95 are arranged beneath the cooling pipe 32 sandwiching the cooling water port 63 serving as the partition plate 61. With the cooling water port 63 as a boundary, the 10 generator 22, rectifier 28, condenser 23, etc. belong to the high pressure section above the boundary, and hence the generator outer cylinder 40, condenser outer cylinder 67, etc. are made of stainless steel so as to have sufficient pressure resistance, while the evaporator outer cylinder 70, absorber outer cylinder 76, etc. at the low pressure section are made of synthetic resins.
15 Additionally, the high pressure sealing material 62 is arranged in the joint between the partition plate 61 and liquid preheater 31.
Description will be made below of the structure of the cooling pipe 32 and cooling water port 63 with reference to Figure 14. In the cooling water pool 63, there are formed a feed chamber 105 communicatively connected to the 20 cooling water inlet 75, and a discharge chamber 106 communicatively connected to the cooling water outlet 65. The cooling pipe 32 is formed by winding, around the liquid preheater 31, the spiral corrugate pipes in spirals with different diameters similar to that used for the solution pipe 30, in a such manner as to form a plurality of layers with the prescribed clearances between the layers; more specifically, the spiral cooling pipe 32a having the smallest diameter is arranged around the outer circumference of the liquid preheater 31, the cooling pipe 32b having the second smallest diameter is arranged around the outer circumference of the pipe 32a, similarly and successively the cooling pipes being arranged, and finally, the cooling pipe 32n having the largest diameter is arranged on the outermost portion. The lower ends of these cooling pipes, 32a, 32b, w 32n, are respectively, via vertical pipes 107a, 107b, 107n, made to approach the feed chamber 105, while the top ends of the cooling pipes, 32a, 32b, w 32n, are respectively, via vertical pipes 108a, 108b, w 108n, made to approach the discharge chamber 106. Incidentally, for the convenience of drawing, the diameter of the cooling pipe 32 is enlarged, and the number of the cooling pipes is diminished.
As for the supercooler 95, vorticosely wound spiral corrugate pipes are arranged both on the top side and bottom side of the cooling water port 63 in such a manner as to sandwich thereof; the cooling water is fed into the bottom side supercooler 95, made to pass through the top side supercooler 95, and then discharged.
The expansion valve 33 is arranged to vertically penetrate from the condenser 23 to the evaporator 24.
The piping structures in the refrigerating pipe 34 of the evaporator 24 and the cooling pipe 37 of the absorber 25 are similar to that of the cooling pipe 32 of the condenser 23, described with reference to Figure 14; either the refrigerating pipes 34 or the cooling pipes 37 are formed by winding spiral corrugate pipes in spirals with different diameters to be arranged into a plurality of layers with the prescribed clearances between the layers.
However, the brine port 77 is arranged under the refrigerating pipe 34, so that it is connected to the lower end of the refrigerating pipe 34 via a vertical pipe 108, and the top end of the refrigerating pipe 34 is connected downward to the cooling water port 63 via a vertical pipe 107. As for the cooling pipe 37, similarly the cooling water port 63 is arranged under the cooling pipe 37, so that it is connected to the lower end of the cooling pipe 37 via the vertical pipe 108, and the top end of the cooling pipe 37 is connected downward to the cooling water port 63 via a vertical pipe 107.
The opening degree of the sprinkler 36 arranged at a top portion of the absorber 25 can be adjusted at the lower end of the liquid preheater 31, by means of an external adjustment mechanism (not shown in the figure) similarly to the first Example.
As shown in Figure 17, a suction pipe 110 is provided in such a way that the suction pipe 110 is connected in such a manner as to face onto the jet orifice of the sprinkler 36, and the lower end opening of the suction pipe 110 is submerged in the liquid pool 29. The ammonia aqueous solution 11 in the liquid pool 29 is sucked up, by taking advantage of the negative pressure generated when the dilute ammonia solution 9 is sprayed under a high pressure by means of the sprinkler 36, and is sprayed into the interior of the absorber 25;
in this way, the ammonia solution is circulated without using a mechanical device such as a pump.
Additionally, the pump 38 arranged in the neighborhood of the liquid pool 29 may be placed either inside or outside the liquid pool 29.
Reference numeral 103 denotes a cooling tower for use in circulating the cooling water.
Description will be made below of the operation of the second Example according to the present invention.
In Figure 10, the concentrated ammonia aqueous solution 11 of the order of from 25 to 50% in the liquid pool 29 is compressively transferred to the generator 22 situated in the top end section, through the solution pipe 30, by means of the pump 38; in the generator 22, the concentrated ammonia aqueous solution 11 is transferred to the liquid pool chamber 55 via the branching device 99 and the liquid delivering pipe 53, and then fed into the heat exchanger pipe 27 via the diffusion nozzle 44.
The heat source is fed from the heat source feed opening 13 into the inner cylinder 43 in the generator 22, where the heat source exchanges heat with the heat exchanger pipe 27 and then is discharged from the discharge opening 14.

Accordingly, the fed ammonia aqueous solution 11 feeds the nonazeotropic mixture refrigerant (ammonia aqueous solution) to the inner wall surface, with spiral grooves, of the heat exchanger pipe 27 through the diffusion nozzle 44 and the heat exchanger pipe 27 where the circular flow is generated, and only the low boiling point fluid (ammonia) is vaporized and advected in the center of the heat exchanger pipe 27, and the high boiling point liquid (water) is advected along the inner wall of the pipe owing to the centrifugal force and surface tension.
In Figure 13, the high concentration, high pressure ammonia gas 21 discharged from the generator 22 and the dilute ammonia solution 9 are transferred to the rectifier 28. The dilute ammonia solution 9 flows on the top plate of the gas passage pipe 50, falls into the liquid fall opening 58; the high pressure ammonia gas 21 and the water vapor pass through the plate 100 with holes and then pass through the metallic nets 101 in the gas passage pipe 50, and the water vapor becomes water droplets on contact with the metallic nets 101 to fall into the liquid fall opening 58, while only the high pressure ammonia gas 21 is transferred to the condenser 23 via the gas passage 102.
In Figure 10, the dilute ammonia solution 9 having fallen into the liquid fall opening 58 passes through the liquid preheater 31, when exchanging heat with and transferring heat to the concentrated ammonia aqueous solution 11 passing through the interior of the solution pipe 30, and is transferred to the sprinkler 36 in the evaporator 24.
The ammonia gas 21 fed into the condenser 23 passes through the cooling pipe 32 of the condenser 23, when exchanging heat with the cooling water flowing in the cooling pipe 32, and is condensed to become the concentrated ammonia solution 94 of the order of 99.8%, which is collected at the bottom of the condenser 23 and further cooled to a temperature not higher than the boiling point by the supercooler 95.
The ammonia solution 94 is expanded and vaporized by the expansion valve 33 situated between the condenser 23 and the evaporator 24, and becomes the low pressure ammonia gas 21; the low pressure ammonia gas 21 cools the refrigerating pipe 34 of the evaporator 24, again comes up to cool the supercooler 95 to a temperature not higher than the boiling point, and is transferred to the absorber 25 via the partition cylinder 97. Meanwhile, the brine in the refrigerating pipe 34 is cooled and low-temperature heat is delivered to the load. The ammonia solution 94 collected at the bottom of the evaporator 24 is discharged from the discharge opening 109 in the partition cylinder 97 to the neighborhood of the sprinkler 36.
The dilute ammonia solution 9 transferred from the liquid preheater 31 is sprayed from the sprinkler 36 under a high pressure; the sprayed dilute ammonia solution 9 is vigorously stirred, is mixed with, and absorbs the ammonia gas 21 coming down along the partition cylinder 97 in the evaporator 24 and the ammonia solution 94 discharged from the discharge opening 109, and then is transferred to the absorber 25.
In the cooling pipe 37 in the absorber 25, the dilute ammonia solution 9 thus transferred to the absorber 25 exchanges heat with the cooling water passing through the cooling pipe 37 to enhance the cooling effect, and becomes the concentrated ammonia aqueous solution 11, falling into the liquid pool 29 and being stored there. The stored ammonia aqueous solution 11 is sucked up through the suction pipe 110, by taking advantage of the negative pressure generated when the dilute ammonia solution 9 is sprayed under a high pressure by means of the sprinkler 36, and is sprayed into the interior of the absorber 25;
in this way, the ammonia solution is circulated.
Then, the ammonia aqueous solution 11 is again compressively transferred by the pump 38.
In the generator 22 either in the first or in the second Example, the heat exchanger pipe 27 is of the vertical type. Consequently, the Example shown in Figure 2 uses one thousand heat exchanger pipes 27 or more, and the Example shown in Figure 11 also uses two hundred heat exchanger pipes 27 or more.
In this connection, the number of the heat exchanger pipes 27 can be reduced to several tens by forming the heat exchanger pipes 27 in vorticose shapes as shown in Figures 15 and 16. In more detail, the solution pipe 30 is 5 arranged in the central portion of the protective pipe 98, the top end of the solution pipe 30 is connected to the branching device 99, the liquid delivering pipes 53 are horizontally and radially connected to the branching device 99, and furthermore the liquid delivering pipes 53 are arranged along the inside of the generator outer cylinder 40 in such a manner as to vertically point 10 downward. The outer end of the heat exchanger pipe 27 wound vorticosely as a pyrethrum coil is connected to the vertical portion of the liquid delivering pipe 53 via the diffusion nozzle 44, and the inner end is connected to the protective pipe 98. The joints between the heat exchange pipe 27 and the protective pipe 98 are arranged with an interval of 180 degrees, as reference 15 numerals 27a and 27b show, in the vorticose heat exchanger pipe 27. The joint between the inner end of the heat exchanger pipe 27 and the protective pipe 98 is directed from the heat exchanger pipe 27 along the tangential line tangential to the inner wall of the protective pipe 98, so that the jetted ammonia aqueous solution 11 more effectively generates circular flow within the protective pipe 20 98.
In the above described Examples, the pressure vessels which constitute the individual processes of absorption refrigeration cycle the generator 22, namely, the rectifier 28, condenser 23, evaporator 24, absorber 25 and liquid pool 29 are successively disposed vertically in a stacked structure, so that the 25 connection piping connecting the five processes is omitted and the whole devices are reduced in scale. Additionally, the individual stages can be constituted using common components so that the number of the component types is reduced, and accordingly the components can be supplied inexpensively owing to the mass productivity. Furthermore, there is no need to make the thermal insulation work for the pipes and valves, and the fluidic loss can also be reduced.
The safety against the break and leak of the solution pipe 30 is improved, by placing the solution pipe 30, subjected to the highest pressure, in the center of the device body.
INDUSTRIAL APPLICABILITY
As above, the ammonia absorption type water chilling/heating device of the present invention is suitable for the case where are utilized various types of exhaust heats, which have hitherto been discarded uselessly, such as the gas turbine exhaust heat, reciprocating heat engine exhaust heat, fuel cell exhaust heat, solar electric power generation exhaust heat, and excess steam of a boiler, or for the case where are utilized a wide variety of heat sources such as geothermal power and hot dry rock which have hitherto been difficult to utilize effectively. The water chilling/heating device of the present invention is suitable as a water chilling/heating device, having a refrigerating capacity of the order of not higher than several hundred kW, to be used in an establishment, which has a relatively large demand for chilling and heating, such as a condominium, a hospital, a factory, a building, a restaurant, an office, a store, and a sports gym. When a refrigeration load exceeds a single device capacity, a plurality of the devices can be operated in parallel to accommodate a demand up to several times the single device capacity. Additionally, the total weight of the device can be suppressed to be of the order of one ton, and hence the device is transportable, so that the device is suitably installed in a ship and a vehicle equipped with refrigeration facilities.

Claims (9)

1. An ammonia absorption type water chilling/heating device, characterized in that: in the device, a generator 22 generating a high pressure ammonia gas 21 from an ammonia aqueous solution 11 by use of heat source, a rectifier 28 performing gas-liquid separation into the ammonia gas 21 and a dilute ammonia solution 9, a condenser 23 condensing the high pressure ammonia gas 21 after the gas-liquid separation, an evaporator 24 utilizing the cooling action generated in the reduced pressure vaporization of a high pressure ammonia solution 94 after condensation, and an absorber 25 making the dilute ammonia solution 9 absorb the ammonia gas 21 after vaporization are successively disposed from the top, and in the interior of these components a solution pipe 30, through which the ammonia aqueous solution 11 is compressively transferred from said absorber 25 to the generator 22, is arranged.

2. The ammonia absorption type water chilling/heating device according to claim 1, characterized in that in the device the generator 22 has a diffusion nozzle 44 at one end thereof, a number of heat exchanger pipes 27 each made of a spiral corrugate pipe having spiral grooves on the inner wall thereof are vertically arranged, and the lower end opening of the heat exchanger pipe 27 is made to face onto the rectifier 28.

3. The ammonia absorption type water chilling/heating device according to claim 1, characterized in that in the generator 22, a plurality of stages of the heat exchanger pipes 27, made of spiral corrugate pipes having the diffusion nozzle 44 at the outer end, wound horizontally and vorticosely are arranged in a stacked structure, the inner ends of these heat exchanger pipes 27 are connected to the protective pipe 98 surrounding the solution pipe 30 placed around the center of said generator 22, and the lower end opening of the protective pipe is made to face onto the rectifier 28.

4. The ammonia absorption type water chilling/heating device according to claim 1, characterized in that a liquid preheater 31 surrounding the spiral solution pipe 30 is arranged under the rectifier 28 and around the center of the condenser 23 so that the solution pipe 30 in the liquid preheater 31 is warmed by the dilute ammonia solution 9 separated by said rectifier 28.

5. The ammonia absorption type water chilling/heating device according to claim 1, characterized in that a supercooler 95, cooling the ammonia solution 94 in the condenser 23 to a temperature not higher than the boiling point by utilizing the low-temperature heat of the low pressure ammonia gas 21 vaporized in the evaporator 24, is arranged between the condenser 23 and evaporator 24 in such a manner as to face onto the condenser 23 and evaporator 24.

6. The ammonia absorption type water chilling/heating device according to claim 5, characterized in that a sprinkler 36 is arranged under the liquid preheater 31 in such a manner as to face onto the top of the absorber, and the dilute ammonia solution 9 sprayed by the sprinkler 36 under a high pressure is made to be vigorously stirred, be mixed with, and absorb the ammonia gas 21 being fed from the evaporator 24 to the absorber 25 and the ammonia solution 94 being fed from the discharge opening 109 of the evaporator 24.

7. The ammonia absorption type water chilling/heating device according to claim 5, characterized in that a sprinkler 36 is arranged under the liquid preheater 31 in such a manner as to face onto the top of the absorber, a suction pipe 110 inserted into the ammonia aqueous solution 11 in the liquid pool 29 is connected in such a manner as to face onto the jet holes of the sprinkler 36, the dilute ammonia solution 9 sprayed by the sprinkler 36 under a high pressure is made to be vigorously stirred, be mixed with, and absorb the ammonia gas 21 being fed from the evaporator 24 to the absorber 25 and the ammonia solution 94 being fed from the discharge opening 109 of the evaporator 24; and simultaneously the ammonia aqueous solution 11 is sucked up through the suction pipe 110 by the negative pressure generated when the dilute ammonia solution 9 is sprayed under a high pressure by the sprinkler 36, to be circulated in the absorber 25.

8. The ammonia absorption type water chilling/heating device according to claim 1, characterized in that the generator outer cylinder 40 constituting the generator 22, the rectifier outer cylinder constituting the rectifier 28, a condenser outer cylinder 67 constituting the condenser 23, an evaporator outer cylinder 70 constituting the evaporator 24, and an absorber outer cylinder 76 constituting the absorber 25 are successively and vertically arranged in a fixed and stacked structure; in the central portions of these components, the solution pipe 30, through which the ammonia aqueous solution 11, while being preheated through heat exchange, is compressively transferred from the absorber 25 to the generator 22, and the liquid preheater 31 are arranged; and a top cover 41 is placed on the top of said generator outer cylinder 40.

9. The ammonia absorption type water chilling/heating device according to claim 1, characterized in that the generator outer cylinder 40 constituting the generator 22, the rectifier outer cylinder constituting the rectifier 28, a cooling water port 63 for use in feeding and discharging the cooling water in the cooling pipe 32 of the condenser 23, the condenser outer cylinder 67 constituting the condenser 23, the supercooler 95 cooling the ammonia solution 94 to a temperature not higher than the boiling point, cooled by the low pressure ammonia gas 21 vaporized in the evaporator 24, and arranged between said condenser 23 and evaporator 24 in such a manner as to face onto the condenser 23 and evaporator 24, the cooling water port 63 for use in feeding and discharging the cooling water for the supercooler 95, the evaporator outer cylinder 70 constituting the evaporator 24, a brine port 77 for use in feeding and discharging the brine for the refrigerating pipe 34 of the evaporator 24, the absorber outer cylinder 76 constituting the absorber 25, and the cooling water port 63 for use in feeding and discharging the cooling water for the cooling pipe 37 of the absorber 25, are successively and vertically arranged in a fixed and stacked structure; in the central portions of these components, the solution pipe 30, through which the ammonia aqueous solution 11, while being preheated through heat exchange, is compressively transferred from the absorber 25 to the generator 22, and the liquid preheater 31 are arranged; and a top cover 41 is placed on the top of said generator outer cylinder 40.