JPS6015866B2 - vacuum dryer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized in that a material to be dried is charged into a vacuum chamber, cooled by a refrigeration device, and from that state, a vapor condenser is provided in the vacuum chamber or another vacuum chamber suitable for the drying process. This invention relates to improvements to the steam condenser in a vacuum drying apparatus for drying objects to be dried by condensing and collecting steam generated from the objects to be dried and maintaining the vacuum pressure in the vacuum chamber at a desired value. It is.

An object of the present invention is to equip the above-mentioned vacuum drying apparatus to perform heat exchange between a heating medium liquid flowing to a shelf provided in the vacuum chamber of the vacuum drying apparatus and a medium evaporator of the refrigeration apparatus for cooling the shelf. The purpose of the present invention is to equip the vacuum drying apparatus with a heat exchanger that occupies substantially no space for the equipment.

In order to achieve this object, the vacuum drying apparatus according to the present invention has a steam condenser for collecting steam, which is installed in the vacuum chamber (trap chamber) in the vacuum drying apparatus of the subordinate type. The "direct soot type" condenses vapor in the cold soot evaporator (dry type or droplet type), or the hot soot liquid cooled by the refrigerant evaporator is evacuated using a heat exchanger installed outside the vacuum chamber. It circulates through the indoor heating medium liquid pipes and heating medium circulation plate, and condenses steam on the outer periphery of the heating medium liquid and the heating medium circulation plate.
In contrast, in the present invention, the steam condenser installed in the vacuum chamber (trap chamber) performs heat exchange between the liner medium and the heat medium liquid. The vacuum chamber is configured with a heat exchanger main body that performs heat exchange between the refrigerant and the heat medium liquid, thereby making it possible to completely omit the space occupied by the heat exchanger provided outside the vacuum chamber to perform heat exchange between the refrigerant and the heat medium liquid. It is characterized by certain points.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described below with reference to the drawings and in comparison with conventional systems.

Figures 1, 2, and 3 are schematic explanatory diagrams showing a vapor condenser (hereinafter simply referred to as a trap) used in vacuum freeze-drying equipment for pharmaceuticals and other products, together with the basic configuration of the entire equipment. Figure 1 shows the most commonly used normal type, in which the trap 101 is a cold soot dry type evaporator, and Figure 2 shows the type used in some cases, in which the trap 102 is a cold soot dry type evaporator. This type is an "indirect heating medium type" in which the hot soot liquid that has already been cooled by the soot in the external heat exchanger 7 is circulated.

FIG. 3 shows an embodiment of the present invention, in which the trap 103
The system functions as a heat exchanger in which both the cooling fluid and the heating fluid circulate inside, thereby reducing the heat exchange between the refrigerant and the heating fluid, and as a steam condenser that condenses and collects steam. It has both functions. In FIGS. 1, 2, and 3,
Vacuum chamber (drying chamber and freezing chamber) 1, vacuum chamber (trap chamber) 2
, the main pipe 3a connecting these, the main valve 3, the vacuum system such as the evacuation system 4 (outline of the vacuum chamber, equipment and piping) are all shown with "pongee lines".

Refrigeration equipment (including all components such as a compressor, oil separator, condenser, and intercooler in the case of two-stage compression, and may be binary refrigeration) 1 1, a sub-refrigeration equipment 12, and a heat exchanger 7, The auxiliary heat exchanger 8, the trap 103 of the present invention, the evaporator 7a, the cold soot line 7b, the cold soot valve 13, the refrigerant expansion valve 14 (triangular), etc. are all included in the cold soot circulation system. Indicated by a "dashed line".

Heat plate (supplies the latent heat necessary for drying the object to be processed; in the examples shown in Figures 1 to 3, it also serves as a plate that supplies the cold heat necessary for preliminary freezing of the object to be processed) 5. Heat medium liquid heating Vessel 6,
The hot soot liquid system equipment and system paths of the heat exchanger 7, the enemy heat exchanger 8, the trap 103 of the present invention, the heat medium pump 9 for the hot plate, and the hot soot pump 10 for the trap are all indicated by "thick lines". It is shown.

In addition, 15 is a gate valve installed in the hot soot liquid circulation system,
The actual order of piping lines, various valves, and equipment arrangement in each system is not necessarily as shown in the diagram, and the diagram is simplified for convenience of explanation.

4 and 5 show the vacuum chamber (trap chamber) 2 of the apparatus of the present invention shown in FIG. 3 and the trap 103 provided in the vacuum chamber 2.
Figure 4 is an example of the vertical cross section (A-A' in Figure 5).
FIG. 5 is a schematic explanatory diagram of a cross section (C-C' section in FIG. 4).

In FIG. 4, the "fine broken line" inside the trap 103 indicates the flow of refrigerant R [corresponds to the cold soot pipe indicated by the reference numeral 26 in FIG. 6].
The "rough broken line" is the boundary of the heat transfer liquid flow path in the trap 103 (corresponds to the partition wall indicated by the reference numeral 27 in FIG. 6), and FIG. 6 shows an example of the cross section of this trap 103. It is. In this embodiment, the medium pipe 26 installed in the trap 103 is formed into a hollow flat plate so as to constitute a vapor condensation surface of the trap 103, as shown in FIG. The condensation plate 103a, which is the outer circumferential wall of 103, is brought into close contact with the condensation plate 103a by means of welding, pressure bonding, etc., so that the condensation plate 103a functions as a heat transfer fin for the cold soot R. tube 26
heat exchange between the refrigerant R in the trap 103 and the hot soot liquid B in the flow path b formed by the partition wall 27 in the trap 103, and the hot soot liquid B in the flow path b and the steam V on the outer periphery of the trap 103. Heat exchange between the cold soot R in the cold zero soot pipe 26 and the steam V on the outer periphery of the trap 103 is now performed by effectively utilizing the condensation plate 103a, which is a fin plate. ing.

In addition, in FIG. 4 and FIG. 5, 23 is a steam inlet of the vacuum chamber (trap chamber) 2 that communicates with the vacuum chamber (drying chamber);
22 is a vacuum port connected to the vacuum pump 4, 24 is a water drain valve, 25 is a jacket heater provided at the bottom of the vacuum chamber (trap chamber) 2 and uses heat medium liquid, hot water, steam, etc., and 21 is a vacuum port connected to the vacuum port 22. This is a shield plate installed to prevent steam from being drawn directly.

In the case of a vacuum dryer in which the trap 101 shown in Fig. 1 is of the "cold soot direct type", it is necessary to always maintain the media circulation cycle at the optimum condition even in the face of large and medium load fluctuations, as is well known. It is difficult.

Furthermore, the trap temperature cannot be accurately controlled with varying loads. Freeze drying, which requires a low temperature of about -60q0 during high load, is prone to problems and accidents such as solidification of the refrigerating machine oil due to excessive cooling, liquid compression, and carbonization of the refrigerating machine oil due to excessive compression in the latter stage. Vacuum cooling, which requires a trap of around 30°F, can easily lead to freezing accidents of vegetables due to overload in the early stage and excessive cooling in the latter stage.
. Compression process, high-pressure and high-temperature gas flow path, condensation process, high-pressure and medium-temperature liquid flow path, adiabatic process, low-pressure and low-temperature gas-liquid merging, low-pressure gas separation and large-scale pressure-temperature fluctuations and phase transformation, as well as temperature Naturally, it is difficult to adapt a complex cycle involving the circulation of refrigerating machine oil whose viscosity changes significantly due to large to medium load fluctuations. On the other hand, the trap 102 in FIG.
In the case of a vacuum dryer that is an "indirect hot soot type," load fluctuations can be alleviated by adding a load to the hot soot circulation system to alleviate excessively low loads, and the trap 102 temperature can also be maintained at the desired value. The disadvantages of the ``refrigerant direct type'' can be solved.

In addition, the heat exchanger 7 between cold soot and heat medium used for the low-temperature trap can be used to control the temperature of parts other than the trap during the cooling process of the trap 102, or in the processes before and after the cooling process. produce benefits.

However, although the "indirect heating medium type" trap 102 is widely used for temperatures around 0°C, it is rarely used for temperatures between 150 and 6000°C.

This is because, due to the following two cooling losses, excessive refrigeration equipment and excessive energy consumption are forced, resulting in economic disadvantage. The first cold loss is caused by the refrigerant evaporator (tube or plate)
This is the temperature loss due to two film heat transfers: between the surface and the heat transfer liquid, and between the heat transfer liquid and the hot soot trap (tube or plate) surface.

The "indirect heat soot type" has the same trap temperature as the "direct refrigerant type".
In order to achieve this, the evaporation temperature must be lower by this temperature loss. The second loss is the heat input loss to the heat transfer liquid due to the circulation pump that circulates the hot soot liquid from the heat exchanger to the trap.

The cold heat in the soot evaporator is latent heat of vaporization, and a large amount of cold heat can be obtained per k9, but the cold heat in the heat transfer liquid is sensible heat, and in the case of a trap that must be isothermal, a large flow rate is required. Therefore, heat input loss is large. In order to cover these two types of cooling and heat losses, excessive equipment and excessive energy consumption are required.

Because of this burden, the ``indirect heating soot type'' cannot replace the ``cold soot direct cooling type'' while eliminating its shortcomings. By the way, in the case of the vacuum drying apparatus shown in FIG. 3 according to the present invention,
First, load fluctuations in the trap 103 can be easily alleviated by adjusting the load in the heat medium liquid flow path b, and the temperature of the trap 103 can be accurately controlled, which is the same as in the case shown in FIG. There are no two cooling losses in the "indirect soot cooling type" shown in Figure 2, and the same trub temperature can be achieved with almost the same refrigeration equipment and energy consumption as in the "direct soot cooling type".

Furthermore, since the cold soot evaporator is located at the same location as the steam condensation load is applied, there is no need to worry about temperature differences between the entrance and exit of the trap heat transfer liquid even if the heat transfer liquid circulation is sufficiently reduced.

In the case of a refrigerant direct cooling type (especially a dry evaporator), even if the refrigerant is sufficiently moist at the inlet, at the outlet, almost all of the cooled air will evaporate and become highly dry. Otherwise, liquid will back up into the compressor. For this reason, even if there is no difference in temperature at the entrance and exit, the trap surface temperature will differ due to the difference in heat transfer between the soot and the trap surface depending on the degree of dryness. but,
In the trap 103 of the present invention, since the cooled heat medium liquid cools the vicinity of the exit where the cold butterflies are in a dry state, there is no need to worry about temperature differences between the entrance and exit. In addition, the flow rate of hot soot liquid is "cold soot direct cooling type".
It is sufficient to alleviate the non-uniformity of the trap temperature that can be avoided, and the heat input loss due to the circulation pump is also small. Moreover, the trap 103 according to the present invention naturally has a trap 1
03 During cooling, as well as in the processes before and after that, it can function as a heat exchanger between the refrigerant and the hot soot liquid for cooling and heating control of other parts of the bag counterfeit. This is superior to the conventional indirect heating medium trap shown in the figure.

This point will be explained using an example of a vacuum freeze-drying device, which is a typical application of a vacuum steam condenser.

In the case of freeze-drying, which requires particularly strict conditions such as those for pharmaceutical products, the equipment usually has the configuration shown in Fig. 1. In the first step of preliminary freezing, the cold soot in the freezing equipment 11 is circulated to the heat exchanger 7, and the hot soot is The liquid is cooled and circulated to the hot plate 5 by the circulation pump 9, and the hot plate 5 and the material to be dried on the hot plate are heated from room temperature to -46°C.
0, the object is cooled to -50°C and freezes. This first step is the same in the cases of FIGS. 2 and 3, but in the case of the present invention (FIG. 3), the function of the heat exchanger 7 is
03. In the first step where the vapor condensation plate 103a of the trap 103 functions as a heat exchanger between the refrigerant and the heat medium, it functions as a good heat fin between the refrigerant and the hot soot liquid, and keeps the vacuum chamber (Trub chamber) 2 in a vacuum state. Therefore, the heat input loss from the outside is smaller than that of the conventional heat exchanger 7.
Therefore, it is no inferior to the conventional heat exchanger 7. When switching to vacuum freeze-drying in the second process, in the normal type (Fig.
The load on the refrigeration equipment and cold soot system was -4.
10 room temperature traps at once from 5q0 to 150oo temperature
1 Sudden change in cooling load. Moreover, within a short period of time, usually around 20 minutes, when the temperature of the hot plate, which is no longer being cooled, increases due to heat input from the outside, the trap will reach -50 oo~
The load at the time of switching between the first and second steps and the switching of the medium flow path are one of the causes of common malfunctions and accidents. In the case of Fig. 2, the heat exchanger 7 is taken over for trap cooling, so there is no sudden change in the soot flow path.
The only thing to do is to switch the heat sink flow path. However, the temperature of the trap 102 and the heat exchanger 7 after switching is both the mixing temperature (-25
(0, 30°C), and rapid fluctuations in the load on the refrigeration equipment and evaporation temperature occur. Since the heat capacity of both the trap 102 and the heat exchanger 7 is large, the heat capacity of the trap 102 and the heat exchanger 7 is large, so this
It is difficult to cool down to 5yo in about 20 minutes. This difficulty can be solved if the positions of the heat exchanger 7 and the trap circulation pump 10 are interchanged in FIG. 2, and the trap is cooled together with the hot plate 5 and the heat exchanger 7 during preliminary freezing.
However, the cooling rate during pre-freezing is delayed due to the addition of the trap 102. To prevent this, the refrigeration equipment would have to be too large. However, in the case of the present invention, when switching from the first process to the second process (from cooling the hot plate 5 to cooling the trap 103), not only the cold soot flow path remains unchanged, but also the heat transfer liquid flow path must be changed. The load temperature also remains unchanged.

The room-temperature hot soot liquid mixed with the heat medium liquid in the trap 103 can be mixed with the trap circulation pump 10 and the valve, and the new piping can be made sufficiently short, so that the trough is small compared to the heat capacity of the trap 103. The heat capacity of the circulation pump 10 and others is sufficiently small.
Taking over the load temperature at the end of the first process from -45℃ to -50:00,
It is only necessary to additionally cool this to -50)C to -55℃, and the heat capacity of the trap cooling system is the same as that of the heat exchanger 7 and trap 102 of the conventional "indirect heat soot type" shown in Fig. 2.
Trap 1, which is smaller than the sum of
Only 03. Therefore, the "indirect heat soot type" in Figure 2
Compared to the case of , trap 1 is
03 does not deteriorate the cooling rate of the hot plate 5, and additional cooling of the trap 103 after preliminary freezing is also easy. After entering the second step, the vacuum freeze-drying process, in the normal vacuum drying apparatus shown in Fig. 1, the temperature of the hot plate 5 is controlled by cold (from 0°C to about 130°C). , normally a sub-refrigerator 12 and a heat exchanger 8 are required.

However, in the case of the vacuum drying equipment shown in Figures 2 and 3,
By adjusting the hot soot system valve between the trap circulation system and the hot plate circulation system, the sub-refrigeration system 1 is
2 and the auxiliary heat exchanger 8 are unnecessary. Refrigeration equipment 11 provided for larger steam condensation loads due to higher hot plate 5 temperatures
The capacity of is naturally excessive for trap cooling when the hot plate 5 is subjected to cooling control, and mixing does not cause insufficient capacity of the refrigeration system. Excessive cooling of the trap in the late stage of freeze-drying is also achieved by moderate mixing, and the temperature drop from the desired value of the hot plate 5 due to mixing is covered by the heater 6. As explained above, the vacuum drying apparatus according to the present invention is different from the conventional vacuum drying apparatus shown in FIGS. Since it also serves as the heat exchanger 7 for the heat exchanger 7, the space occupied by the heat exchanger 7 can be completely omitted, which provides the benefit of reducing equipment costs and installation area. The benefits that can be achieved by achieving stable operation of the refrigeration equipment for trap cooling and accurate control of the vacuum pressure through accurate control of the trap temperature will reduce the energy consumption of excessive equipment and refrigeration equipment. can get. In addition, trap 1 in the present invention
03 is also effective in removing ice when the steam is frozen and collected in the trap 103.

After the completion of the entire process, when switching is made again so that the hot soot circulates in the flow path including the hot plate 5 and the trap 103 (if the amount of heat is insufficient, the heater 6 is used), the cold soot in the trap 103 is removed from the refrigeration system. 11, and at the same time, trap 103 becomes 0.
When the temperature rises above 0.degree. C., the ice slides off or peels off from the outer surface of the condensation plate 103a and falls to the bottom of the vacuum chamber 2. Therefore, if a jacket heater 25 for heat transfer liquid, overflowing water, steam, etc. is provided at the bottom, frozen ice can be quickly removed without pouring water or blowing steam in from the outside, and is discharged from the drain valve 24. become able to. Note that the configuration of the trap 103 in the present invention is similar to that of the fourth trap 103.
The present invention is not limited to the embodiments shown in FIGS. 6 to 6.

For example, the cold soot pipe 26 in the example shown in FIG.
The trap 103 may be arranged at the center of the flow path b of the heat transfer liquid B to form a double pipe with the rare flow path b, or as shown in FIGS. 7 and 8. The outer wall of the trub 103 is formed into a cylindrical double tube corresponding to the inner diameter of the cylindrical outer wall 28 forming the vacuum chamber 2, and the inner circumferential surface of the trub 103 corresponds to the inner diameter of the cylindrical outer wall 28 forming the vacuum chamber 2. A refrigerant pipe 26 is inserted into the inner cavity of the trap 103, which is formed by double pipes, arranged in the inner cavity of the vacuum chamber 2 so as to form a peripheral wall, and a liner medium R is introduced into the inner cavity. The inner part of the trap 103, which is formed into a serpentine tube shape by the cold soot pipe 26, is formed in the flow path b of the heat transfer liquid,
By circulating the heat transfer liquid B therein, the inner circumferential surface of the trap 103, which becomes the inner circumferential wall of the vacuum chamber 2, becomes the condensation plate 10.
It may be configured as appropriate, such as 3a. In addition, if the requirements for the capacity balance of the device are special, the heat exchanger incorporated in the trap 103 does not substitute all of the capacity of the heat exchanger 7 and the Liu heat exchanger 8 in the conventional means, It is also possible to cover part of the heat exchange capacity with another external heat exchanger, or to provide a separate refrigeration device in addition to the refrigeration device 11. Further, the vacuum chamber (trap chamber) 2 in which the trap 103 is provided is connected to the main valve 3.
This is not limited to the case where the vacuum chamber 2 is separated from the vacuum chamber (drying chamber) 1 by the vacuum chamber (drying chamber) 1, but may also be the vacuum chamber (drying chamber) 1.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram of a conventional device, Fig. 2 is a schematic explanatory diagram of another conventional device, Fig. 3 is a schematic explanatory diagram of the present invention device, and Fig. 4 is a schematic explanatory diagram of a conventional device.
The figure is a schematic cross-sectional view of the vacuum chamber (trap chamber) and trap of the device of the present invention, FIG. 5 is a schematic cross-sectional view of the same as above, and FIG.
FIGS. 7 and 8 show another embodiment of the trap chamber and trap of the apparatus of the present invention, with FIG. 7 being a longitudinal sectional side view and FIG. 8 being a longitudinal sectional front view. Explanation of drawing symbols, 1... Vacuum chamber (drying chamber), 2
...Vacuum chamber (trap chamber), 3...Main valve,
3a... Main pipe, 4... Vacuum exhaust system (vacuum pump), 5... Plate (hot plate), 6... Heat medium liquid heater, 7...・Heat exchanger, 8...Sub-heat exchanger, 9...Circulation pump, 10...
・Circulation pump for truck, 11...refrigeration equipment,
12...Sub-refrigeration device, 13...Refrigerating valve, 1
4... Refrigerant expansion valve, 15... Gate valve, 21...
...Break plate, 221...Cut, 23...
...Steam inlet, 24...Drain valve, 25...
・Heater, 26...Cold soot pipe, 27...
・Partition wall, 28...Outer wall of vacuum chamber 2, 1101,1
02,103...Steam condenser (trap), B
...Heating medium liquid, R...Refrigerant. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Completed Figure 8

Claims (1)

[Claims] 1. A heat exchanger installed in a vacuum drying device is installed on the outer surface of the vacuum drying device so as to exchange heat between the refrigerant evaporator of the refrigeration device and the heat transfer liquid flowing to the shelf provided in the vacuum chamber to cool the shelf. 1. A vacuum drying device characterized in that all or part of the surface is formed as a vapor condensation and collection surface, and the device is installed in a vacuum chamber for collecting vapor.