JP2554783B2 - Cold heat supply equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cold heat supply equipment.

[0002]

2. Description of the Related Art The method of transporting cold heat in district heat supply is
In practice, it is done exclusively with cold water. in this case,
Even if the sending temperature is 6 ° C and the returning temperature is 13 ° C, only 7 Kcal of cold heat can be sent per 1 kg of cold water, and a very large amount of cold water must be transported for a large cold load (for example, It is necessary to transport about 14300 ton / h of cold water for a heat load of 100 Gcal / h),
The pipe diameter for this is also enormous (as mentioned above, about 1
When transporting 4300ton / h of cold water, the flow velocity is 3m / sec.
Then, the diameter becomes about 1.32 m).

The fact that two such large-diameter pipes are required for going back and forth makes not only the piping equipment cost very high, but also the transportation power cost and the profitability of cold heat transportation is poor. Become. Furthermore, it is unrealistic not only to be economical, but to bury such a large diameter pipe in an urban area.

By the way, in recent years, as a method for solving such a problem, a method of transporting cold heat by ice slurry has been studied. For example, if the weight ratio of ice is 40%, if the sending water is 0 ° C. and the returning water is 13 ° C.,
It became possible to send cold heat of 45 Kcal per 1 kg of ice slurry, and about 1/6.
Fluid transportation of 4 will be sufficient (for example, 100 Gcal /
Approximately 2220 ton / h of ice slurry is required for the heat load of h). If the flow velocity is the same as for water, the pipe diameter is about 1
/2.5 (3 m / sec for 100 Gcal / h)
At a flow rate of about 0.53 m).

It should be noted that, although two to three test results of the flow velocity characteristics of ice slurry have been reported, it is said that the same flow velocity does not make much difference with water. If the flow rate is the same, in the case of ice slurry, the pipe diameter will decrease and the pressure loss will increase, but the effect of reducing the flow rate will be great and the transportation power will also be significantly reduced (for example, in the case above, 1 / 2.5).

[0006]

As described above, according to the ice slurry transportation, the cold heat transportation is significantly increased in density and efficiency, and the piping equipment cost, transportation power cost, etc. can be reduced. In order to make the most of the advantage, there are still the following problems.

[0007] That is, there is a problem in the increase of refrigerating machine power and the ice making technique regarding the transportation of ice slurry for cold heat transportation. Conventionally, the generation of low temperature cold heat that can make ice is
It is performed in a compression refrigerator. According to this compression type refrigerator, 6 to 7 used for cold heat transportation by conventional cold water are used.
The refrigerant evaporating pressure at a low temperature at which ice can be made (for example, -10 ° C. considering the temperature difference in the heat exchanger for ice making) becomes considerably lower than the evaporating pressure of the refrigerant when producing cold water at 0 ° C. Since the compression ratio of the refrigerant gas in is increased, the shaft power of the compressor is significantly increased (for the same cold heat output, the power required for the compressor is about 1.5).
It can be doubled).

[0008] Such an increase in refrigerating machine power not only partially impairs the effectiveness and economic efficiency of the system, but also partially lowers energy saving, which is one of the purposes of such large-scale district heat supply. There is a problem that it will be caused.

It is also known that when an absorption refrigerator is used, the change in thermal efficiency is relatively gradual even if the cold heat output temperature is changed. However, a lithium bromide / water absorption refrigerator, which is often used during cold water production, cannot output low-temperature cold heat capable of making ice.
In addition, a cold heat output of an ice-making temperature by an absorption refrigerator using a refrigerant other than water, such as water / ammonia system, NMP (N-methyl-2-pyrrolidone) / TFE (2.2.2-trifluoroethanol). However, due to safety issues and the like, it is not common for consumer use, and there are problems in the ice making technology as shown below.

Since the ice making technique is intended for transportation, the so-called dynamic type ice making system is targeted, but the problems with typical ones of the conventional ice making systems are shown below. (A) Harvest type This is to evaporate a refrigerant such as CFC inside the plate heat exchanger and freeze the water flowing down like a film on the outer surface by the heat of vaporization. The hot refrigerant is introduced into the inner surface to heat it from the inner side to slightly melt the ice in contact with the heat transfer surface and drop it in a thin plate shape. Further, due to the intermittent operation, the operation rate of the heat exchanger becomes low, and the ice that has fallen off is plate-shaped, so there is a problem that the plate-shaped ice must be crushed for transporting the slurry. (B) Liquid ice method This is not a method of freezing pure ice, but a solution in which a small amount of salts or ethylene glycol is dissolved is cooled by a heat exchanger while providing turbulence by various methods to transfer heat. It makes fine ice particles without adhesion and growth of ice on the surface, which is convenient for obtaining ice particles suitable for slurry transportation. However, in order to obtain such an effect, it is necessary to make the solution concentration such that the freezing point depression cannot be ignored, and since almost no dissolved components are incorporated into the generated ice, when ice is generated to some extent, the remaining Since the solution concentration of the above increases further and the freezing point lowers more, the refrigerant evaporation temperature of the refrigerator must be lowered by an amount commensurate with these, so that there is a problem that the refrigerator power is further increased. . (C) Supercooled ice method This should avoid the drawbacks of the above liquid ice method,
By using pure water with a heat exchanger that cools with a special heat exchange rate, temperature difference, flow velocity condition, and vibration control, without generating ice in the heat exchanger In this method, the outlet temperature of the heat exchanger is set to be lower than the freezing point of about −2 ° C. (supercooling), and after leaving the heat exchanger, a shock is applied to break the supercooling and generate ice particles.

This supercooling control is extremely delicate, and if foreign matter such as rust or a small amount of ice particles that have not been separated are present in the inlet water, freezing will immediately occur in the heat exchanger. The heat transfer tube will be filled with ice and water will not be able to pass through, which may make it impossible to continue the operation. In addition, the sensible heat of just a few degrees of supercooling of water is used for the heat of solidification of water. Therefore, a very large amount of water (for example, about 40 times) has to be circulated as compared with the amount of ice to be generated, and there is a problem that the ice making device is inefficient. (D) Refrigerant direct blowing method In this method, a refrigerant liquid is directly blown into water to generate ice particles in the water due to the latent heat of vaporization of the refrigerant. However, when the refrigerant is other than water, water vapor is included in the refrigerant gas. Not only causes various troubles at various places in the refrigeration cycle such as the compressor, but also causes a problem that the refrigerant is dissolved in the ice slurry side and a large amount of the refrigerant is lost. (E) Direct heat exchange method using non-aqueous solution fluid This is a method in which a non-water-soluble liquid such as cooling oil is cooled to a temperature below the freezing point of water and blown directly into water. However, there is a problem in that the cooling medium evaporation temperature of the refrigerator must be lowered and the power is increased. Moreover, the two fluids (water and non-water-soluble liquid) that are in direct contact with each other are contaminated to some extent, so that problems will inevitably occur if they are operated for a long time.

[0012] Therefore, an object of the present invention is to provide a cold heat supply facility capable of solving these problems.

[0013]

In order to solve the above-mentioned problems, the cold heat supply equipment of the present invention comprises an absorption refrigerator having an evaporator, an absorber, a regenerator and a condenser and using water as a refrigerant. An adjusting tank for temporarily storing the slurry ice produced by this absorption refrigerator and adjusting the slurry concentration, and a slurry transport pipe for carrying the slurry ice stored in the adjusting tank to a predetermined location. And the operating pressure of the evaporator and the absorber in the absorption refrigerator is 2.0 to 4.5 mmHg, and
The refrigerant water introduced into the evaporator is flash-evaporated to reduce the temperature of the refrigerant water to below its freezing point to generate ice particles, and these ice particles are extracted as a slurry and sent to the adjusting tank. is there.

[0014]

With the above structure, water is used as the refrigerant in the absorption refrigerator, and the operating pressure of the evaporator and the absorber is set to a pressure lower than the triple point of water. Can produce ice particles. Moreover, since the produced ice particles are sent to a predetermined location, that is, a demand facility by slurry transportation, the cost of transportation equipment and transportation power can be significantly reduced as compared with the case of sending cold water, for example.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, the cold heat supply equipment of the present invention includes an evaporator 11 for evaporating water as a refrigerant, and an absorbing liquid (for example, LiBr) for evaporating water vapor evaporated by the evaporator 11.
The absorber 12 for absorbing the -ZnCl ₂ aqueous mixture of -CaBr _{2), 2} pieces of playback by absorbing water vapor by heating the diluted absorption solution whose concentration was thinned to separate the refrigerant vapor in the absorber 12 Bowl (double-effect type) 13
And to condense the steam separated by the regenerator 13 2
Individual condensers 14, a refrigerant liquid transfer pipe 15 for transferring condensed water condensed in the condenser 14 into the evaporator 11, and a refrigerant vapor for transferring water vapor evaporated in the evaporator 11 into the absorber 12. A transfer pipe 16, a rare absorption liquid transfer pipe 17 that absorbs water vapor in the absorber 12 and transfers the diluted absorbent having a reduced concentration into the regenerator 13, and the water vapor separated in each regenerator 13 is condensed. Refrigerant vapor transfer pipes 18A respectively transferred to the container 14
18B and a concentrated absorption liquid transfer pipe 19 for transferring the concentrated absorption liquid, in which the water vapor has been separated in the regenerator 13 and has become thicker, between the regenerators 13 and from the regenerator 13 into the absorber 12.
A and 19B, a heat recovery device 20 for applying heat of the concentrated absorption liquid to the rare absorption liquid to recover heat, and a cooling water supply pipe 21 for supplying cooling water to the absorber 12 and the condenser 14.
And an absorption refrigerator 1 having a steam supply pipe 22 for supplying steam to the regenerator 13 as a heat source, and an ice transfer pipe 2 for ice produced in the evaporator 11 of the absorption refrigerator 1.
And a temporary adjustment tank 3 for adjusting the concentration of the slurry while temporarily extracting and storing as a slurry via the slurry, and a slurry transport pipe for carrying the slurry stored in the adjustment tank 3 to a predetermined location, that is, a demand facility 4. It is composed of 5 and. In addition, 6 and 7 are transport pumps which are inserted in the ice transport pipe 2 and the feed pipe 56a of the slurry transport pipe 5, respectively.

Further, in the upper space inside the evaporator 11,
Plastic molding filler (specific surface area 30-300m
² / m ³ ) 11a is arranged. The operating pressure of the evaporator 11 and the absorber 12 in the absorption refrigerator 1 is lower than the vapor pressure at the triple point of water, that is, within the range of 2.0 to 4.5 mmHg, and the evaporator is Refrigerant water introduced into 11 is sprinkled and flash-evaporated.

That is, the refrigerant water sprayed from above the filling material 11a flows down while wetting the surface of the filling material 11a, is adiabatically evaporated, and its temperature drops to a temperature below the freezing point, so that ice in the cooling water. Crystal particles are generated. In this case, the generated ice is not generated on the solid surface such as the heat transfer surface, but is generated in the liquid as the heat is removed from the surface of the water. Can be obtained.

The ice generated in the evaporator 11 is taken out together with the refrigerant water by the transportation pump 6 and temporarily stored in the adjusting tank 3. Here, the concentration is adjusted to the optimum for slurry transportation. Further, by providing this adjusting tank 3, it is possible to cope with load fluctuations, and the absorption refrigerator 1
Can be less than the peak load.

The slurry-like ice stored in the adjusting tank 2 is supplied to the cooling coil 8a of the air conditioner 8 on the demand facility 4 side through the slurry transportation pipe 5 buried underground, where the ice is stored. The refrigerant on the air conditioner 8 side is cooled by the heat of fusion and the sensible heat of water, so that the inside of the demand facility 4 is cooled. An ice storage tank 9 for storing slurry ice is provided on the demand facility 4 side, which makes it unnecessary to adjust the ice slurry transportation capacity to the peak load, which is economical.

Then, the water that has taken away heat from the cooling coil 8a and has been warmed to about 12 to 14 ° C. is returned to the evaporator 11 via the return pipe 5b of the slurry transport pipe 5. By the way, in order to keep the operating pressure of the evaporator and the absorber in the absorption refrigerating machine below the vapor pressure at the triple point of water, the vapor pressure in the temperature range that can be cooled by cooling water is 4.5 mm.
It must be sufficiently smaller than Hg and sufficiently separated from the crystal precipitation conditions (saturation solubility).

[0021] For example, under the meteorological conditions of Japan, the cooling water temperature when using a cooling tower is planned to be 32 ° C as a standard, but it is lower than groundwater, river water, sewage treatment water, seawater, etc. The use of cooling water is also conceivable.

As a reference, FIG. 2 shows vapor pressures at saturated concentrations of various absorbing liquids. It is sufficient to select an absorbing solution or conditions that can draw a cycle diagram sufficiently above these curves. The operating pressure of the evaporator and absorber is as follows:
2.0 mmHg to 4.5 mmHg, preferably 3.0 mmHg
Is.

Under general cooling water conditions, it is impossible to use an aqueous lithium bromide solution which is most often used in absorption refrigerators that generate cold water, but special cooling water conditions (low-value waste heat, low temperature cooling) The case where water is obtained separately) is also conceivable, and the cold heat supply equipment in the present embodiment is not limited to a specific absorbing liquid, and the device configuration of the absorption chiller is also limited to that shown in FIG. Of course, generally known various modifications can be applied.

As an example, as a condition that is sufficiently safe from the crystal precipitation conditions, the cycle conditions and the performance thereof used in the aqueous solution of the mixture of LiBr-ZnCl ₂ -CaBr ₂ (the weight ratio of the components is 1: 1: 0.13), that is, Coefficient of performance (COP
= Output cold heat amount / driving heat amount) is shown in FIGS.

In the case of the double-effect type shown in FIG. 3, when the cooling water temperature is 32 ° C., it is not possible to make a large difference in concentration, so COP = 1.034, which is slightly low, but as shown in FIG. When using groundwater, river water, sewage treatment water, seawater, etc. as cooling water in the heavy-duty formula, COP = 1.324, which is large compared to the COP of a general absorption chiller for cold water output. There is no difference and it can be used. In addition, the single-effect type shown in FIG. 5, which can be driven by low-temperature steam such as utilization of waste heat for waste incineration and utilization of turbine exhaust, is also very effective in some cases.

The cold heat supply equipment in the above embodiment has the following effects. By setting the operating pressure of the evaporator and the absorber of the absorption chiller to a pressure lower than the triple point of water, ice does not adhere to the heat transfer surface and the energy efficiency is hardly reduced compared to when cold water is output ( At most 1
It is possible to make ice suitable for slurry transportation.

By the cold heat transportation by the ice slurry, the facility cost and transportation power cost of the cold heat transportation, which has been a bottleneck in the past, can be significantly reduced. Since the refrigerant of the absorption chiller is the same as the medium for transporting cold heat, the entire facility becomes a thimble and highly efficient system.

If cold storage with ice is also used, a more efficient system can be obtained.

[0029]

As described above, according to the structure of the present invention, water is used as the refrigerant in the absorption refrigerator, and
Since the operating pressure of the evaporator and the absorber is lower than the triple point of water, the ice particles can be easily produced by flash evaporation at low power, and the produced ice particles can be transported by the slurry in a predetermined manner. Since it is sent to a place, the cost of transportation equipment and transportation power can be significantly reduced as compared with the case of sending cold water, for example.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an entire cold heat supply facility according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between temperature and vapor pressure at saturated concentrations of various absorbing liquids.

FIG. 3 is a Duhring diagram in the refrigeration cycle.

FIG. 4 is a Duhring diagram in the refrigeration cycle.

FIG. 5 is a Duhring diagram in the refrigeration cycle.

[Explanation of symbols]

 1 Absorption Refrigerator 3 Adjustment Tank 4 Demand Facility 5 Slurry Transport Pipe 8 Air Conditioner 9 Ice Storage Tank 11 Evaporator 12 Absorber 13 Regenerator 14 Condenser

Front page continuation (72) Sanae Omori, 5-3 28 Nishikujo, Konohana-ku, Osaka-shi, Osaka Prefecture Hitachi Shipbuilding Co., Ltd. (72) Toru Tanaka 5-28, Nishikujo, Konohana-ku, Osaka, Osaka Hitachi Shipbuilding Co., Ltd.

Claims (1)

(57) [Claims] 1. An absorption refrigerating machine having an evaporator, an absorber, a regenerator and a condenser and using water as a refrigerant, and a slurry ice produced by the absorption refrigerating machine is temporarily stored. Along with the adjusting tank for adjusting the slurry concentration, and the slurry transport pipe for slurry-transporting the slurry ice stored in the adjusting tank to a predetermined location, and operation of the evaporator and the absorber in the absorption refrigerator. The pressure is set to 2.0 to 4.5 mmHg, and the refrigerant water introduced into the evaporator is flash-evaporated to lower the temperature of the refrigerant water below its freezing point to generate ice particles, and the ice particles are slurried. A cold heat supply facility characterized by being extracted as above and sent to the adjusting tank.