JPS61211673A - Cryogenic absorption type refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a low-temperature absorption refrigerator that uses ammonia as a refrigerant and an ammonia aqueous solution as an absorption liquid.

Conventional technology Many types of combinations of refrigerant and absorbent have been proposed for absorption refrigerators to obtain low temperatures below 0°C. The ammonia-water combination (hereinafter referred to as an ammonia absorption type ) will be explained as an example.

FIG. 6 shows a system diagram, equipment configuration, and equipment type of a conventional ammonia absorption refrigerator. The principle of refrigeration in this case has been known for a long time, and a particularly detailed explanation is not considered necessary, but a basic explanation will be given just in case.

First, cold heat (low m) 49 is generated in the evaporator 5o. The ammonia evaporation side of the evaporator 50 is at low pressure (the pressure varies depending on the degree of low temperature desired to be obtained. For example, when the ammonia evaporation temperature is -30°C, ~1.21kof/aIa
bs), evaporation of ammonia occurs, and the latent heat for the ife is released into the fluid to be cooled (prine or fluorocarbons such as calcium chloride or polyethylene glycol solution, or the process fluid itself that requires refrigeration). It takes away the heat brought in and makes it lower temperature. , In order to maintain a low pressure in the W&generator 5G and continue evaporating ammonia, the generated ammonia vapor 51 must be immediately discharged to the outside! I
? This is done by absorbing the ammonia vapor 51 into water (actually an ammonia aqueous solution with a dilute ammonia concentration, hereinafter referred to as a weak solution) in the absorber 52. Absorption heat is generated when ammonia is absorbed, and the temperature of the solution rises. However, if the solution temperature rises too much, the absorption capacity decreases, so in the absorption vessel 52, the solution is cooled with cooling water 53. Ammonia vapor 51
need to be absorbed.

In order to maintain the function of the absorber 52 at a constant level, while constantly supplying the weak solution 54 to the absorber 52, an aqueous solution (hereinafter referred to as a strong solution) 55 that has absorbed ammonia and has a high ammonia concentration is taken out. There is a need.

In order to operate the cold "a" machine in a closed cycle, the absorber 5
It is necessary to recover a nearly pure ammonia solution 56 from the strong solution 55 extracted from 2 and supply it to the evaporator 50. A rectification column 57 is generally used as a means for doing this. The regenerator 58 uses this ammonia'F8 distillation column 5.
It has the role of a reboiler (reboiler). Almost pure ammonia vapor 56 emerging from the top of the rectification column 5I is converted into cold F! in a condenser 59. 1 is cooled by water 60 and condensed. In order to condense with the cooling water 60 at a temperature obtained under the conditions under which the refrigerator is operated, the operating pressure on the regenerator 58 - rectification column 57 - condenser 59 side is slightly high (for example, the ammonia condensation temperature is set to 40 ° C. In this case, it is necessary to set it to ~15.9 kgf/c111 abs). The boiling point of the solution in the regenerator is determined in accordance with this operating pressure and the concentration of the solution in the regenerator, and the temperature required for the heat source of the regenerator 58 is also determined.

A part of the substantially pure ammonia liquid 56 condensed in the condenser 59 is refluxed 56a to the rectification column 57, but most of it flows into the evaporator 50 via the expansion valve 61 and is evaporated.

The bottom liquid 62 of the rectification column 57 is sent to the regenerator 58 as a weak solution 54.
It is extracted from the absorber 52 and sent to the absorber 52 after exchanging heat with the strong solution 55 coming from the absorber 52 to the 11 distillation column 57. The above is the basic cycle, and tanks such as the liquid receiver 63 and the strong solution tank 64, and additional heat exchangers may be added in order to control operation and improve efficiency. 65 is a pressure reducing valve, 6
6 is a strong solution pump, 67 is a reflux pump, 68 is a blowdown, and 69 is a waste heat.

Problems to be Solved by the Invention Conventionally, compression refrigerators using fluorocarbons or the like as a refrigerant have been overwhelmingly used for refrigeration to obtain low temperatures below 0°C. but,
Absorption refrigerators that use solar heat, geothermal heat, or waste heat or surplus heat from various processes are highly energy-saving, so it is thought that they will become very popular in the future, but in order to do so, the following three points need to be improved.

A. It should be possible to drive with a heat source as low as possible without reducing thermal efficiency.

B. Lower equipment costs without reducing thermal efficiency.

C.IIa Improving thermal efficiency without increasing cost.

To achieve this, (a) the equipment configuration and arrangement must be as simple as possible and the piping must be minimized, and (b) a heat exchange method that provides a high heat transfer coefficient even if the temperature difference between each heat exchanger is designed to be small. It is important that (c) the heat exchange method maximizes the effective temperature difference without causing mixing on the solution side within the heat exchanger. When looking at the conventional example shown in FIG. 6 from this perspective, it is clear that it does not meet the above requirements.

Means for Solving the Problems In order to solve the above problems, the low temperature absorption refrigerator of the present invention uses ammonia as a refrigerant and an ammonia aqueous solution as an absorption liquid.・In addition to providing a tube-type evaporator, a vertical shell-and-tube type absorber is provided directly below this evaporator, and the M generator has an upper liquid chamber that receives ammonia liquid and ammonia from this upper liquid chamber. The absorber has a heat exchanger tube that forms a falling liquid film in the tube with liquid, and an introduction part for the fluid to be frozen is formed on the shell side, and the absorber has an upper liquid chamber that receives the absorbed liquid, and a heat transfer tube that forms a falling liquid film in the tube. It has a heat transfer tube that forms a falling liquid film in the tube with the absorption liquid and receives ammonia vapor from the evaporator and the evaporation residual liquid, and a cooling water channel that passes cooling water upward from the lower part on the shell side, and A rectification column is installed in parallel with the rectification column, and a shell-and-tube type regenerator is installed directly below the rectification column. It also has a heat transfer tube forming a heat source fluid path on the shell side, a weak solution supply path that supplies a weak solution from the lower part of the regenerator to the upper liquid chamber of the absorber, and a weak solution supply path that supplies a weak solution from the lower part of the absorber to the upper liquid chamber of the absorber. A thermal circulation device is provided between the strong solution supply line that supplies the strong solution to the distillation column, and a horizontal shell-and-tube type heat exchanger is provided at a position higher than the top of the precision column and between the rectification column and the evaporator. A condenser is provided, and this condenser has a heat exchanger tube that allows the chilled water to flow laterally, and also forms an introduction path for purified ammonia vapor coming out of the rectification column on the shell side, A portion of the ammonia liquid is refluxed to the rectification column, and the remainder is introduced into the upper liquid chamber of the evaporator.

According to the structure of the present invention, the ammonia liquid introduced into the heat transfer tube of the vertical shell-and-tube evaporator evaporates while flowing down while forming a falling liquid film in the heat transfer tube, and the ammonia liquid is evaporated on the shell side. Cool the introduced fluid to be frozen 1! do. The absorption liquid (weak solution) introduced into the heat transfer tube of the vertical shell-and-tube absorber placed directly below the evaporator forms a falling liquid film within the heat transfer tube and flows down roughly. The absorption liquid formed into a liquid film can receive the ammonia vapor and the evaporation residual liquid from the evaporator and absorb the ammonia vapor.

The absorbed heat generated at this time can be disposed of in the cooled water passed upward from the lower part of the shell side, and the strong solution extracted from the lower part of the absorber is pressurized by a strong solution pump and then passed through a heat recovery device to a rectification column. supplied to The bottom liquid of the rectification column is introduced into the heat exchanger tube of the regenerator to form a falling film, and is mixed with ammonia and steam by receiving heat from the heat source fluid introduced into the shell side of the regenerator. Steam is generated, and this mixed steam rises in the heat exchanger tube of the regenerator, facing the solution, and is introduced into the lower part of the rectification column. In addition, the weak solution accumulated in the lower liquid chamber of the regenerator is sent to the upper liquid chamber of the absorber via the heat recovery device. The purified ammonia vapor coming out of the rectification column No. 4 is introduced into the shell side of the horizontal shell-and-tube condenser, where it is condensed by cooling water flowing through the heat transfer tubes of the condenser, and the condensed ammonia liquid is A portion is returned to the rectification column 4 by gravity, and the remaining portion is introduced into the upper liquid chamber of the evaporator.

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 shows the equipment configuration, equipment arrangement, and equipment type of a low-temperature absorption refrigerator according to the present invention.

First, the evaporator 1 is a vertical shell-and-tube heat exchanger, and is equipped with a liquid separator 5 that supplies ammonia liquid 3 to the upper liquid π2 and forms a liquid film inside the heat transfer tube 4. It is attached to the top end of the pipe. The ammonia liquid 3 flows down the inner surface of the heat transfer tube 4 as a liquid film and evaporates at a low temperature while taking heat from the fluid 6 outside the tube. Evaporated ammonia vapor 7 is
It flows downward through the center of the heat transfer tube 4 in parallel with the liquid and flows out from the lower end of the tube. The flow rate of the ammonia liquid 3 flowing down as a liquid film decreases as evaporation progresses, and the thickness of the liquid film gradually becomes thinner. In order to avoid poor wetting of the heat transfer surface due to breakage of the liquid film at the lower part of the tube, the heat transfer tube 4 in this case is a tube with a porous inner surface, or Use a tube with many thin grooves, a tube with many pleats that form grooves in the longitudinal direction of the tube, etc. As the fluid 6 for carrying out cold heat to the outside, an ethylene glycol solution, a calcium chloride solution, or the like is not used, but fluorocarbon, which is optimal for the low temperature conditions to be generated, is used. In FIG. 1, Freon R-12 is used. The fluorocarbon vapor 6A that has taken heat from the process (cooled the process) and evaporated at the point of use flows into the shell side of the evaporator 1, condenses on the outer surface of the heat transfer tube 4 which is at a low temperature, and releases latent heat of condensation. Add to ammonia solution 3 in the tube. Freon is clean and does not contaminate heat transfer surfaces, but its low thermal conductivity reduces the condensation heat transfer coefficient. Therefore, the outer surface of the heat transfer tube 4 needs to have a shape that promotes condensation heat transfer of the fluorocarbon. A heat transfer surface shape having such an effect is preferably a shape with a large number of vertical pleats. The double-sided pleated heat transfer tube 4 shown in FIG. 2 is optimal as the heat transfer tube 4 that prevents the liquid film of the ammonia liquid 3 on the inner surface of the tube from drifting and promotes condensation heat transfer of fluorocarbons on the outer surface of the tube. Here, 6B indicates a Freon condensate, and 3a indicates a falling ammonia liquid film.

The features of the evaporator 1 according to the present invention will be explained by comparing it with the conventional evaporator 50 shown in FIG. 6. It is clear from FIG. brine, etc.). In this case, there are disadvantages such as the contamination coefficient on the brine side in the pipe becomes large, and when the 311 degree difference is made small, the boiling heat transfer coefficient of the ammonia on the shell side becomes small.

Additionally, an ammonia liquid 56 generally flows into the evaporator 50 and covers the evaporator 50.
Although it is almost pure rectified, it still contains some J3 water (e.g. about 0.1%).
In order to prevent this moisture from accumulating in the evaporator 50 and increasing the evaporation temperature, it is necessary to remove the remaining moisture from the evaporator 50 together with the ammonia liquid 56. In the evaporator 5o according to the conventional method, since the liquid evaporated on the shell side is intensively mixed, the moisture in the ammonia liquid 56 in the evaporator 50 is almost uniform, so that the influence of moisture on the evaporation temperature is reduced. For this, ammonia solution 56 with low water concentration is used.
However, in order to remove a certain amount of water, the flow rate of the ammonia solution 56 that is blown becomes large.

This means that of the ammonia liquid 56 that has been rectified by consuming thermal energy, the proportion of 6 that is not used for evaporation (refrigeration) increases, which increases the thermal efficiency of the absorption refrigerator. resulting in a decrease in On the other hand, in the case of the evaporator 1 used in the absorption refrigerator of the present invention, the ammonia liquid 3 that has flowed in is evaporated while flowing down as a liquid film inside the heat transfer tube 4.

The concentration of the contained moisture increases as it goes down the tube, but since there is no vertical mixing of the evaporating ammonia solution 3, the rise in evaporation temperature due to the influence of moisture is limited to near the bottom end of the tube. It turns out. Furthermore, a small amount of liquid that has reached the designed moisture concentration (evaporation temperature) drips from the lower end of the tube without being evaporated, and the minimum amount of liquid is automatically blown out.

That is, in the case of the present invention, since the blowing is performed when the water content is at its highest level, only a small amount of blowing is required, and the influence on the thermal efficiency of the refrigerator is small, and the influence on the average evaporation temperature is also small. In addition, in terms of heat transfer performance, since it is a combination of CFC condensation and ammonia falling liquid film evaporation, the fouling coefficient is small, and the overall heat transfer coefficient is almost constant regardless of the size of the design difference of 11 degrees. Due to the effect of double-sided heat exchanger tubes, high performance can be achieved.

Next, the absorber 8 is also a vertical shell-and-tube type heat exchanger, and as shown in FIG. are arranged in a connected manner. A weak solution 13 is sent to the upper liquid chamber 9 of the absorber 8 from the lower liquid chamber 26 of the regenerator 21 using the pressure difference, and the weak solution 13 is sent from the lower liquid chamber 10 of the absorber 8 to the strong solution pump 1.
1 exchanges heat with the strong solution 12 sent to the rectification column 20 by the heat recovery device 28, and is supplied in a lowered temperature state.

This weak solution 13 is turned into a liquid film flowing down the inside of the heat exchanger tube 14 by a liquid separator 15 attached to the upper end of the heat exchanger tube 14 .

On the other hand, the ammonia vapor 7 and a small amount of blowdown liquid (ammonia liquid containing slightly more water) flowing out from the lower part of the evaporator 1 flow directly into the upper part of the absorber 8, and the blowdown liquid is mixed with the weak solution 13. The ammonia vapor 7 is gradually absorbed by the weak solution 13 while flowing downward in parallel with the weak solution 13 flowing down as a liquid film through the center of the heat transfer tube 14, and is completely absorbed by the time it reaches the lower end of the heat transfer tube 14. . Since the blowdown liquid flow rate is small compared to the ammonia vapor flow rate, even if it is mixed with the weak solution 13 in the upper liquid chamber 9,
There are no performance problems at all. When the ammonia vapor 7 is absorbed by the weak solution 13, absorption heat is generated and the solution temperature tries to rise, but as the temperature of the solution rises, the absorption capacity decreases, so it is cooled to the shell side. Cool UJ-'J through 16 ml of water.

Ru. The weak solution 13 flows down inside the pipe and generates ammonia vapor 7.
, the ammonia concentration in the solution increases and the composition becomes a strong solution 12 at the lower end of the tube. In order to ensure that the solution near the bottom end of the tube, which has a composition similar to that of the strong solution 12, still has sufficient ammonia absorption capacity, it is necessary to perform further cooling.

That is, in the absorber 8, it is important to lower the solution temperature as it goes downward, so 1 G of cold l, II water is passed through the shell side.
It is important that the flow is opposite to the solution in the tube, from the bottom to the top.

In the absorption of ammonia vapor by the falling liquid film in the heat transfer tube 14, what is important for improving performance is to give turbulence to the liquid film flow. Since the absorption is of almost pure ammonia vapor 7, there is almost no mass transfer resistance on the gas phase side.

The liquid film is formed by an ammonia aqueous solution, which does not have a high viscosity and high thermal conductivity, so heat transfer in the liquid film is quite large. However, the mass transfer resistance on the liquid phase side during the process in which ammonia 3 absorbed on the surface of the liquid film diffuses throughout the liquid film is quite large, and the concentration near the liquid film surface is quite large compared to the average concentration over the entire thickness of the liquid film. The ammonia concentration at the ammonia becomes considerably high, reducing the absorption performance. Therefore, it is most desirable to use a corrugated tube shown in FIG. 3 as the heat transfer tube 14 in order to improve absorption performance by imparting disturbance to the liquid film.

In this case, the depth I of the grooves on the inner surface of the Korgu 1 tube is 11 to 3IllI11, and the pitch P of the grooves is 5Ill1.
m~20au+ is optimal. Furthermore, when a corrugated pipe is not used, it is very effective to insert a twisted plate 14b shown in FIG. 1 into the smooth pipe 14a as shown in FIG. It is.

On the shell side, a method is generally adopted in which a large number of circular baffles are used to increase the flow rate of the cold N1 water 16 so that the flow is substantially perpendicular to the heat transfer tubes 14, thereby increasing the membrane heat transfer coefficient. However, in this case, depending on the quality of the cooling water 16,
Since dirt caused by 1 G of cooling water accumulates on the outer surface of the heat transfer tube 14, a considerably large dirt coefficient must be expected in the design. Since it is difficult to adopt such a method, chemical cleaning has no choice but to be used, which increases maintenance costs. In the present invention, this shell side is made into a solid-liquid fluidized bed,
This method provides a high heat transfer coefficient even if the cooling water flow rate is low, and prevents dirt from accumulating in the cooling water 16. Immediately above the lower cooling water inlet on the shell side, a baffle 18 for supporting particles is provided with a number of holes to prevent particles from passing through. Above this, particles whose density and particle size are selected in accordance with the designed flow rate are filled to about ⅓ of the length of the tube plate space 11.

When cooling water 16 is passed through, this particle layer 17 expands and spreads over the entire shell side, forming a fluidized bed. The particles float while vibrating gently and also come into contact with the surface of the heat exchanger tube 14. Therefore, the heat transfer coefficient is large even at low flow rates, and dirt does not accumulate. In order to prevent particles from flowing out, a baffle 19 for preventing particles from flowing out is provided immediately below one upper cooling water outlet, which has a number of holes through which particles do not pass. In some cases, it may be effective to provide a liquid cyclone in the middle of the cooling water outlet piping to collect outflow particles and return them to the absorber shell. The particles used are sand, glass, steel balls,
Anything that has some strength, such as lead particles, can be used. A suitable particle size is 0.51R1 to 51R, and one that provides a good fluidity is selected depending on each specific design condition.

The absorber 8 of the absorption refrigerator of the present invention explained above will be compared with the conventional absorber 52 shown in FIG. In the conventional type, the melt melts weakly from the upper part of the shell side of the horizontal shell-and-tube heat exchanger)l! 54 and ammonia vapor 51 are allowed to flow in, and the ammonia vapor 51 is absorbed by the weak solution 54 that drips down from the top of the tube bundle on the shell side while wetting the tube bundle, and the absorbed heat is removed by cooling water 53 passed through the tubes. It is. The disadvantages of the conventional method are (a) difficulty in dispersing the weak solution 54 so as to uniformly wet the outer surface of the heat exchanger tubes over the entire tube bundle, and (b) the weak solution 54 flowing down and the cooling water 53 inside the tubes. It is difficult to make the flow into a counterflow,
(c) A trace amount of non-1I2tIA gas in the ammonia vapor flowing into the absorber 52 (a trace amount of air mixed in when filling the refrigerant and absorption liquid, moisture of metal constituting the equipment during operation)
'l! Il! It is necessary to vent these to prevent the hydrogen (e.g., generated by II conversion, etc.) from adversely affecting the absorption performance, but the conventional absorption i! In s52, mixing of gas on the a-shell side, which is difficult to vent in a state where the non-condensable gas is concentrated, tends to occur.

Non-condensable gases tend to mix and accumulate throughout, adversely affecting the overall absorption performance, and in order to prevent this adverse effect, it is necessary to vent a large amount of gas.

The absorber 8 according to the present invention includes (a) all heat transfer tubes 14 for absorbing liquid;
(b) It is easy to make the rising solution and the external cooling water 16 flow in opposite directions;
(c) As the smallest non-condensable gas in the ammonia vapor 7 flowing into the absorber 8 flows downward in the pipe in parallel with the absorption liquid, only the ammonia vapor 7 is selectively absorbed.
The concentration of non-condensable gas gradually increases, and its partial pressure is highest at the lower end of the tube. Therefore, the influence of non-condensable gas on absorption performance is limited to the lower end of the tube, and to prevent this influence, venting should be performed through a nozzle installed on the wall above the solution level in the lower liquid chamber 1o of the absorber 8. Therefore, the effect can be increased by venting a relatively small amount of gas. Other features include improved absorption performance through the use of special heat transfer tubes, and a solid-liquid fluidized bed on the shell side that maintains a high heat transfer coefficient even under conditions of low cold U1 water flow rate and reduces fouling. I have already mentioned the point of maintaining the color. Further, as described above, the absorber 8 is disposed directly below the evaporator 1 to automatically receive the blowdown liquid dripping from the lower end of the evaporator/heat transfer tube 4 along with the ammonia vapor 7.

Next, regarding the III distillation column 20, no fundamental technical improvement is made in the present invention. Conventionally, this is carried out using a tray column such as a bubble bell or a perforated plate column used in a general rectification column 2G, or a packed column such as a Raschig ring or a bell saddle column. However, the regenerator 21, which corresponds to a reboiler attached to a general ill distillation column, is placed directly below the rectification column 20, receives the solution flowing down from the recovery section 22 of the m distillation column 2G into the upper liquid chamber 23, and vertically Heat transfer! ! A liquid film is formed in the tube 24 and allowed to flow down. The heat source fluid 25 is passed to the shell side. FIG. 1 shows the case where the heat source fluid 25 is steam (steam or other organic and inorganic process fluid steam). As the solution flows down the liquid film, it receives heat and evaporates. The composition of the vapor generated by evaporation is mainly ammonia mixed with 10 to 20% water vapor, but this mixed vapor reverses from the point where it is generated and travels opposite the solution flowing down in a liquid film. It ascends through the center of the heat transfer tube 24 and passes through the upper liquid chamber 23 from the upper end of the heat transfer tube 24 to the recovery section 22 of the rectification column 20.
flows down to

The regenerator 58 as a prior art is a horizontal shell and
Place the solution on the P side of the tube heat exchanger.

This is a so-called flooded type in which a heat source fluid is introduced into the tube to heat and evaporate the solution. When the temperature difference between the solution and the heat source fluid is large, boiling will occur and the heat transfer coefficient will be large, but if it is necessary to design with a small temperature difference, such as in the case of waste heat utilization, Since the thermal coefficient is extremely reduced, the heat transfer area increases significantly.

Furthermore, since the solution on the shell side is easy to mix, the vapor generated has a composition that is almost in equilibrium with the concentration of the regenerated outlet liquid, so the water partial pressure inevitably becomes high.

On the other hand, in the regenerator 21 of the absorption refrigerator of the present invention, there is almost no mixing of the solution flowing down as a liquid film, so the generated vapor composition varies from one in equilibrium with the regenerator inlet liquid to the recycled product outlet (lower liquid Heat transfer 1!24 changes sequentially from the upper end until it reaches equilibrium with the liquid, so the water partial pressure becomes small on average. In addition, since this steam rises in the heat transfer tube 24 in opposition to the solution, the steam entering the recovery section 22 of the 18 fff column 20 has a composition that is almost in equilibrium with the solution in the regenerative population (upper liquid chamber). Therefore, the water partial pressure is considerably lower than that of the conventional technology. For this reason, the rectification tower 20
This is advantageous in terms of performance design, and the amount of water evaporated in the regenerator 21 is reduced, making it possible to reduce the amount of heat required in the regenerator 21. Furthermore, since it is a falling liquid film method, a high heat transfer coefficient can be obtained regardless of the temperature difference.

27 indicates condensed water.

In addition, by using the corrugated tube explained in the section of the absorber 8 as the heat transfer tube 24, or by inserting the twisted plate 14b or the spiral wire 14c into the smooth tube 14a, the liquid film is further disturbed and the performance is improved. can be raised.

Further, when the heat source fluid 25 is a high-temperature liquid, the shell side is made to be the initial layer of solid-liquid flow described in the case of the absorber 8.

Furthermore, when the heat source fluid 25 is a high-humidity gas, the heat transfer tube 24 is a fin 1-b with fins attached to the outside of the tube.
Provide appropriate partition plates to improve the side gas flow pattern. The weak solution 13, which is the regeneration liquid that has flowed down to the lower liquid chamber 2G of the regenerator 21, is cooled by exchanging heat with the strong solution 12 in the heat recovery device 28, using the pressure difference between it and the absorber 8.
It is sent to the absorber 8 via the pressure reducing valve 29.

Purified ammonia vapor 33 exiting from the top of the concentration section 30 of the rectification column 20 enters the shell side of the condenser 31 and passes through the heat exchanger tube 32.
It is cooled and condensed by the cold water 35 flowing inside. Condenser 3
1 is placed at a position slightly higher than the rectification column plate, and the condensed ammonia liquid 3 is refluxed 34 to the top of the rectification column.
The system is simplified by using vertical force without using a pump. A small amount of ammonia solution 3 is held at the bottom of the body side of the condenser 31 so as to allow the composition of the working solution in the system to change due to changes in the operating shaft. The amount of ammonia liquid in the condenser 31 changes in response to changes in the average solution composition. The condensed ammonia liquid 3 flows into the evaporator 1 via the expansion valve 36 in accordance with the load, absorbs heat from the fluid to be frozen as latent heat of evaporation, and evaporates at a low temperature.

The condenser 31 is a horizontal shell-and-tube type, and is placed between the evaporator 1 and the rectification column 20, with an ammonia vapor inlet on the rectification column 20 side and an ammonia condensate outlet on the evaporator 1 side. Because of this, the installation height of the entire device does not become excessively high, fluid flow is extremely smooth, and piping length is minimized. In this case, the heat exchanger tube 32 is
- By using tubes, the condenser 31 can be made more compact.

Effects of the Invention According to the configuration of the present invention described above, the equipment configuration and its arrangement can be simplified, the number of piping can be minimized, and the heat exchange method provides a high heat transfer coefficient even if the temperature difference between each heat exchanger is designed to be small. Furthermore, it is possible to create a heat exchange system that maximizes the effective temperature difference without causing mixing on the solution side within the heat exchanger. As a result, it is possible to drive with a heat source as low as possible without reducing thermal efficiency, and it is also possible to reduce equipment costs without reducing thermal efficiency, and furthermore to prevent equipment costs from increasing. Thermal efficiency can be improved without causing damage.

[Brief explanation of the drawing]

1 to 5 show one embodiment of the present invention, in which FIG. 1 is a partially cutaway front view, FIG. 2 is an explanatory view of the main part, and FIGS.
The figure is a sectional view showing a modified example of the heat exchanger tube, and FIG. 6 is an explanatory view of a conventional example. DESCRIPTION OF SYMBOLS 1... Evaporator, 2... Upper liquid chamber, 3... Ammonia liquid, 3a... Ammonia liquid flow 1; Liquid film, 4... Heat exchanger tube, 6... Fluid, OA...・Freon vapor, 7...
Ammonia vapor, E3...absorber, 9...upper part'a
Chamber, 11...Strong solution pump, 13...Weak solution, 14
...Heat transfer tube, 14a...Smooth tube, 14b...Twisted plate, 14c...Wire rod, 1G...Cooling water, 17...
- Particle layer, 20... Rectification column, 21... Regenerator, 22
... recovery section, 24 ... heat transfer tube, 25 ... heat source fluid, 28 ... heat recovery device, 29 ... pressure reducing valve, 31 ...
Condenser, 32... Heat exchanger tube, 33... Ammonia vapor, 34... Reflux, 35... Cold 7Jl water, 3G...
Expansion valve representative Yahiro MorimotoFigure 2Figure 3Figure 4Figure 5

Claims (1)

[Claims] 1. In a low-temperature absorption refrigerator that uses ammonia as a refrigerant and an ammonia aqueous solution as an absorption liquid, a vertical shell-and-tube evaporator is provided, and a vertical shell-and-tube evaporator is provided directly below the evaporator. A shell-and-tube type absorber is provided, and the evaporator has an upper liquid chamber for receiving ammonia liquid, a heat transfer tube for forming a falling liquid film in the tube with the ammonia liquid from the upper liquid chamber, and a shell-and-tube absorber. An introduction part for the fluid to be frozen is formed on the side, and the absorber has an upper liquid chamber that receives the absorption liquid, and forms a falling liquid film in the pipe with the absorption liquid from the upper liquid chamber, and also absorbs ammonia from the evaporator. In addition to having a heat transfer tube for receiving steam and evaporation residual liquid, a cooling channel is formed on the shell side for passing cooling water upward from the lower part, and a rectification column is provided in parallel with the evaporator, and a rectification column is provided directly below the rectification column. A vertical shell-and-tube regenerator is installed,
The regenerator has a heat transfer tube that forms a falling liquid film in the tube with the bottom liquid of the rectification column, and also forms a heat source fluid path on the shell side,
A heat recovery device is installed between a weak solution supply path that supplies a weak solution from the lower part of the regenerator to the upper liquid chamber of the absorber and a strong solution supply route that supplies a strong solution from the lower part of the absorber to the rectification column. established,
A horizontal shell-and-tube condenser is disposed at a position higher than the rectification column and between the rectification column and the evaporator,
This condenser has a heat exchanger tube that allows cooling water to flow laterally, and also forms an introduction path for purified ammonia vapor coming out of the rectification column on the shell side, and purifies a part of the ammonia liquid produced in the condenser. A low-temperature absorption refrigerator characterized in that it is configured to reflux the liquid to the distillation column and introduce the remainder into the upper liquid chamber of the evaporator. 2. A tube with a porous inner surface as a heat transfer tube for an evaporator;
Alternatively, the method according to claim 1 is characterized in that a tube with a large number of thin grooves in the longitudinal direction or the circumferential direction, or a tube with a large number of pleats forming grooves in the longitudinal direction of the tube is used. Low temperature absorption refrigerator. 3. Using Freon as the fluid to be frozen, this Freon vapor is received in the evaporator shell side and condensed at a low temperature, and this low-temperature Freon liquid is sent to the external process that requires freezing, and the external process is frozen by this Freon evaporation. A low-temperature absorption refrigerator according to claim 1, characterized in that the evaporated fluorocarbon vapor is received again into the evaporator shell side. 4. The low-temperature absorption refrigerator according to claim 1, characterized in that a double-sided pleated tube is used as the heat transfer tube of the evaporator. 5. Low-temperature absorption refrigeration according to claim 1, characterized in that a corrugated tube, a smooth tube with twisted plates inserted, or a smooth tube with a spiral wire inserted is used as the heat transfer tube of the absorber. Machine. 6. The low-temperature absorption refrigerator according to claim 1, wherein the body side of the absorber is a solid-liquid fluidized bed in which sand, glass beads, metal particles, etc. are fluidized with cooling water. 7. Install a liquid cyclone in the cooling water outlet piping of the absorber,
A low-temperature absorption refrigerator according to claim 6, characterized in that the collected particles are extracted from the cyclone and returned to the shell side of the absorber. 8. Above the strong solution level in the lower liquid chamber of the absorber,
A low-temperature absorption refrigerator according to claim 1, characterized in that a seat for a non-condensable gas bleed valve is provided. 9. The low-temperature absorption refrigerator according to claim 1, characterized in that a corrugated tube, a smooth tube with a twisted plate inserted therein, or a smooth tube with a spiral wire inserted therein is used as the heat transfer tube of the regenerator. . 10. Using a high temperature liquid as a heat source fluid in the regenerator,
2. The low-temperature absorption refrigerator according to claim 1, wherein the regenerator body side is a solid-liquid fluid layer in which sand, glass beads, metal particles, etc. are fluidized with high-temperature liquid. 11. Using high temperature gas as the heat source fluid in the regenerator,
2. A low-temperature absorption refrigerator according to claim 1, characterized in that a heat transfer tube with fins on the outer surface is used as the heat transfer tube of the regenerator, and a partition plate is provided to improve gas flow on the shell side. 12. The low-temperature absorption refrigerator according to claim 1, characterized in that a corrugated tube is used as the heat transfer tube of the condenser.