JPS5812042B2 - Steam condenser in vacuum equipment - Google Patents

Description

[Detailed description of the invention] Vapor condenser (vapor condenser,
A vapor trap (also called a vapor trap or cold trap) is a device that condenses and traps water and other solvent vapors generated during processing from objects to be processed in a vacuum chamber or on a low-temperature surface provided in the vacuum chamber or a vacuum chamber connected to the vacuum chamber. In order to maintain the vacuum pressure in the vacuum chamber at a desired value, it constitutes the main parts of vacuum equipment such as vacuum freeze-drying equipment, vacuum drying equipment, vacuum concentration, vacuum distillation, vacuum cooling, and solvent removal. It is widely used.

The purpose of the present invention is to improve the conventional defects of the steam condenser in this vacuum device, (1) stabilize the operation and facilitate maintenance, and (2) improve the control accuracy of vacuum pressure by controlling its temperature. , (3) To overall achieve the various points of improving economic efficiency by reducing the equipment cost, occupied area, and operating energy of the device.

The features of the present invention are, firstly, that the conventional vapor condenser is a "refrigerant direct cooling type" in which vapor is condensed in the refrigerant evaporator itself (dry type or flooded type), or it is installed outside the vacuum chamber. In the heat exchanger, the heat medium liquid cooled by the refrigerant evaporator is circulated through the heat medium liquid pipes or heat medium liquid circulation plate in the vacuum chamber, and the vapor is condensed on the heat medium liquid pipe (or plate). In contrast, the steam condenser of the present invention is a heat exchanger body for a refrigerant and a heat medium liquid.

Second, regardless of whether a conventional refrigerant/thermal liquid heat exchanger is a double-pipe or shell-tube method, the medium that directly cools the outer metal plate of the heat exchanger (in the case of a double-pipe In the outer tube,
In the case of a shell tube, the medium inside the shell is either a refrigerant or a heat transfer liquid, and the structure is such that almost no heat transfer between the other medium and the outer surface plate occurs without passing through the other medium. On the other hand, in the heat exchanger used in the present invention, the heat exchanger can be heated directly or by direct metal contact from either side of the refrigerant or heat medium, and without passing through the other medium. The outer surface can be cooled.

A steam condenser in a vacuum device is a heat exchanger between a low-temperature medium (first medium) and vacuum steam (low-pressure steam) (second medium) when viewed from the viewpoint of heat transfer engineering.

A vapor condenser in a conventional vacuum device is a boundary metal wall between the cryogenic medium and the vacuum vapor, whether the cryogenic medium is a refrigerant or a heating medium that has already been cooled in a separate heat exchanger with the refrigerant. It is a heat exchanger via a metal plate (fin) that is in close contact with a boundary metal wall.

On the other hand, the vacuum steam condenser of the present invention has three components: a refrigerant (first medium), a heating medium liquid (second medium), and vacuum steam (third medium).
Characterize it as a "pressure-medium heat exchanger" in which there is direct heat exchange between any two media through a boundary metal wall or a metal plate in close contact with the boundary metal wall. Hereinafter, the details of the present invention will be explained in detail with reference to the drawings, and embodiments will be compared 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. The trap 101 shown in Fig. 1 is a normal type that is often used, and is a refrigerant dry evaporator that directly cools the refrigerant.
The trap 102 shown in the figure is an "indirect heat medium type" that is used in some cases, and the trap 102 is an "indirect heat medium type" that circulates a heat medium liquid that has already been cooled by a refrigerant in an external heat exchanger 7.

FIG. 3 shows an embodiment of the present invention, in which the trap 103
is a "three-body heat exchange type" in which both the refrigerant and heat transfer fluid circulate inside.

In Figures 1 to 3, vacuum drying chamber (cum-freezing chamber) 1
, the vacuum trap chamber 2, the main pipe 3a connecting the vacuum trap chamber 2, the main valve 3, the evacuation system 4, and other vacuum systems (outline of the vacuum chamber, equipment, and piping) are all indicated by "thin lines".

Refrigeration equipment (including all compressors, oil separators, condensers, intercoolers in the case of two-stage compression, etc.)

In some cases, there is a case of dual freezing) 11. The sub-refrigeration device 12, and the refrigerant evaporator 7a of the heat exchanger 7, the refrigerant evaporator 8a of the side heat exchanger 8, the refrigerant evaporator of the refrigerant direct cooling type trap 101, and the refrigerant evaporator of the trap 103 of the present invention, and a refrigerant line, a refrigerant valve 13, and a refrigerant expansion valve 14 (indicated by a triangle)
The refrigeration refrigerant circulation systems such as the above are all shown with broken lines.

A heating plate (supplies the latent heat necessary for drying the object to be treated, and in the examples shown in FIGS. 1 to 3 also serves as a plate that supplies cold heat necessary for preliminary freezing of the object to be treated) 5, a heat medium liquid heater 6 , the heat medium liquid line 7b of the heat exchanger 7 mentioned above, the heat medium liquid system 8b of the side heat exchanger 8, the heat medium liquid line path of the indirect heat medium type trap 102, and the heat medium liquid of the trap 103 of the present invention. The yarn path, the heat medium liquid system equipment such as the hot plate heat medium pump 9 and the trap heat medium pump 10, and the yarn path are all indicated by "thick lines".

In addition, in Figures 1 to 3, 15 is a gate valve installed in the circulation system of the heat medium liquid, but the actual order of the piping system lines, various valves, and equipment arrangement in the yarn path of each group is The figures are not necessarily as shown, and the figures are simplified for ease of explanation.

4 and 5 show one example of the vacuum trap chamber 2 and trap 103 of the apparatus of the present invention shown in FIG. Figure 5 is a schematic explanatory diagram of the cross section (C-C cross section in Figure 4), and the "fine broken line" inside the plate in Figure 4 is the flow path for refrigerant R [refrigerant pipe indicated by reference numeral 26 in Figure 6]. The "rough broken line" is the boundary of the flow path of the heat transfer liquid in the plate (corresponds to the partition wall indicated by the reference numeral 27 in Fig. 6), and an example of the cross section of this plate is shown in Fig. 6. be.

FIGS. 7 and 8 are diagrams showing examples of small-sized traps.

In any of the cases shown in FIGS. 6, 7, and 8, the refrigerant pipe 26
is in close contact with a trap (vapor condensation plate) 103 by welding, crimping, or the like, and the trap (vapor condensation plate) 103 serves as a heat transfer fin for the refrigerant R.

The refrigerant R and the heat medium liquid B exchange heat through the trap 103 which is a refrigerant pipe wall and a fin plate, and the heat medium liquid B and the vapor V are exchanged through a trap (vapor condensation plate) which is a heat medium liquid wall.
103, and the refrigerant R and vapor V are transferred to a trap (steam condensation plate) which is a fin of the refrigerant pipe 26.
103 for heat exchange.

Thus, heat exchange between any of the three pressure media (refrigerant R2, heating medium liquid B, steam V) is performed by the boundary metal wall or the same fin plate.

28 is an outer wall of the trap room.

The first effect of this invention is to improve the operational stability of the refrigeration equipment for trap cooling and to achieve accurate control of the vacuum pressure by accurately controlling the trap temperature. This can be achieved without consuming energy.

This effect applies not only to vacuum freeze-drying but also to all the devices listed above.

In all of the previous processes, a large amount of steam from the object to be treated is treated at the beginning of the process, and the steam condensation load on the trap is almost eliminated from the latter stage to the end point.

In the case of the "refrigerant direct cooling type" shown in FIG. 1, as is well known, it is difficult to always maintain the refrigerant circulation cycle at optimum conditions in response to wide load fluctuations.

Furthermore, the trap temperature cannot be accurately controlled with varying loads.

In freeze drying, which requires temperatures as low as -60°C under high load, accidents are likely to occur in the latter stages due to problems 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 addition, in vacuum cooling, which requires a trap at around 0°C, there is a compression process, a high-pressure high-temperature gas flow path, a condensation process, a high-pressure medium-temperature liquid flow, and a high-pressure high-temperature gas flow path, which can easily cause freezing accidents such as vegetables due to early overload and late excessive cooling. A complex cycle involving adiabatic expansion process, low-pressure low-temperature gas-liquid mixed flow, low-pressure gas flow path, wide pressure temperature fluctuations and phase transformation, and circulation of refrigeration oil whose viscosity changes significantly depending on temperature. Naturally, it is difficult to adapt to large load fluctuations.

On the other hand, the "indirect heating medium type" shown in FIG. 2 is used in some cases.

In this case, load fluctuations can be alleviated by adding a load to the heat medium circulation system to alleviate the excessively low load, and the trap temperature can also be controlled to the desired value. Shortcomings can be resolved.

In addition, there is an advantage that the heat exchanger 7 between the refrigerant and the heat medium liquid used for the low-temperature trap can be used for cold control of the temperature of parts other than the trap during the trap cooling process or in the steps before and after the trap cooling process. .

However, although "indirect heating medium type" traps are widely used at temperatures around 0°C, they are rarely used at temperatures of -50 to -60°C.

This is because due to the first and second cooling losses, excessive refrigeration equipment and excessive energy consumption are forced, resulting in economic disadvantage.

The first cold loss is between the refrigerant evaporator (tube or plate) surface and the heat transfer liquid, the heat transfer liquid and the heat transfer trap (tube or plate).
This is the temperature loss due to two film heat transfers on the surface.

The "indirect heating medium type" has the same trap temperature as the "refrigerant direct cooling 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 heat transfer liquid from the heat exchanger to the trap.

The cold heat in the refrigerant evaporator is latent heat of evaporation, and a large amount of cold heat can be returned per kg, but the cold heat in the heat medium liquid is sensible heat, and in the case of a trap that must be isothermal, a large flow rate is required, so Heat 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 medium type'' cannot be used as a substitute for the ``refrigerant direct cooling type'' while eliminating its drawbacks.

By the way, in the case of the device shown in FIG. 3 according to the present invention, firstly, load fluctuations in the trap can be easily alleviated by adjusting the load in the heat medium liquid flow path, and the trap temperature can be controlled accurately compared to the case in FIG. 2. is similar to, and secondly, the second
There are no two cooling losses in the "indirect heating medium type" shown in the figure, and "
The same trap temperature can be achieved with almost the same refrigeration equipment and energy consumption as in the case of the "refrigerant direct cooling type".

The refrigerant evaporator and the trap (tube or plate) surface adhere to each other through metal heat transfer, and heat transfer via the heat transfer medium is also added to this, so there is almost no temperature loss, and when a vapor condensation load is applied, they remain in the same position. Since there is a refrigerant evaporator, there is no need to worry about temperature differences between the entrance and exit of the trap heat medium even if the circulation of the heat medium is made sufficiently small.

In the case of a refrigerant direct cooling type (especially a dry evaporator), even if the refrigerant is sufficiently wet at the inlet, unless almost all the refrigerant has evaporated and become highly dry at the outlet, the compressor will This will cause liquid backlash to the area.

Therefore, even if there is no temperature difference between the refrigerant at the entrance and exit, the trap surface temperature will differ due to the difference in heat transfer between the refrigerant and the trap surface depending on the degree of dryness.

The refrigerant flows through the outer cylinder through a trap that also serves as a heat exchanger.
Even if the heat transfer liquid flows through a double pipe in the inner cylinder, the temperature loss mentioned above can be avoided, but the trap surface temperature will be uneven due to the dryness of the refrigerant, and the expansion valve forced to make delicate adjustments.

However, since the trap of the present invention is a "tribody heat exchanger" and there is direct heat transfer between the heat transfer liquid and the trap surface, this point is also significantly alleviated.

Near the outlet where the refrigerant becomes dry, the cooled heat transfer liquid cools the trap 103.

The flow rate of the heat medium liquid is sufficient to alleviate the unevenness of trap temperature that is inevitable in the "refrigerant direct cooling type", and the heat input loss due to the circulation pump is also small.

In addition, the "three-body heat exchanger type" trap according to the present invention naturally performs heat exchange between refrigerant and heat medium for cooling and heating control of other parts of the device, both during trap cooling and in the processes before and after the trap cooling. In this respect, it is superior to the ordinary indirect heating medium trap shown in FIG. 2.

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 for pharmaceutical products, the apparatus usually has the configuration shown in FIG. The heat medium liquid is cooled and circulated to the hot plate 5 by the hot plate heat medium pump 9, and the hot plate 5 and the object to be dried on the hot plate are cooled from room temperature to 145°C to 150°C. freezes.

This first step consists of the “indirect heating medium type” and the third type shown in Figure 2.
The same applies to the "three-body heat exchange type" according to the present invention shown in the figure, but in the case of the present invention (the "three-body heat exchange type" shown in FIG. 3), the heat exchanger 7 The function is performed by trap 103.

The vapor condensation plate of the trap 103 functions as a heat transfer fin between the refrigerant and the heat medium during the first step of functioning as a heat exchanger between the refrigerant and the heat medium, and since the trap chamber can be kept in a vacuum state, no external The heat input loss is smaller than that of the conventional heat exchanger 7.

Therefore, it is not inferior in any way to the conventional heat exchanger 7.

When switching to vacuum freeze-drying in the second step, in the normal type ("refrigerant direct cooling type" shown in Fig. 1), the refrigerant in the refrigeration device 11 must be suddenly switched to the trap 101, and the refrigerant in the refrigeration device The load on the refrigerant system suddenly changes from -5°C to -50°C to a large load for cooling the trap 101 at room temperature.

Moreover, the trap 101 must be cooled to -50°C to -55°C within a short period of time, usually about 20 minutes, before the temperature of the hot plate 5, which is no longer cooled, rises due to heat input from the outside. ~ The switching of the load and refrigerant flow path during the switching of the second process is one of the causes of regular malfunctions and accidents.

In the case of FIG. 2, since the heat exchanger 7 is taken over to cool the trap 102, there is no sudden change in the refrigerant flow path, but only a change in the heat medium flow path.

However, the temperature of the trap 102 and the heat exchanger 7 after switching is the mixed temperature of both (-25° C. to -30° C.), causing a sudden change in the load of the refrigeration system and the evaporation temperature.

Since both the trap 102 and the heat exchanger 7 have large heat capacities, it is difficult to cool them from -50°C to -55°C in about 20 minutes.

This difficulty can be solved by changing the positions of the heat exchanger 7 and trap heat medium pump 10 in FIG.
, the problem can be solved if the trap 102 is cooled together with the heat exchanger 7.

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 refrigerant flow path remains unchanged, but also the load changes even when the heat medium liquid flow path is changed. The temperature also remains unchanged.

The room-temperature heat medium liquid to be mixed with the heat medium liquid thread of the trap 103 requires only the trap heat medium pump 10 and the valve, and the new piping can be made sufficiently short, and the trap heat medium pump 10 and other parts are relatively small compared to the heat capacity of the trap 103. The heat capacity of is sufficiently small.

Taking over the load temperature of the first process bed from -45℃ to -50℃,
It is only necessary to additionally cool this to -50°C to -55°C, and the heat capacity for cooling the trap 103 is the same as that of the conventional heat exchanger 7 and the trap in the case of the "indirect heat medium type" shown in Fig. 2. Only the trap 103 is smaller than the sum of the heat exchanger 7 and the heat exchanger 7.

Therefore, compared to the case of the "indirect heating medium type", even if the trap 103 is cooled together with the preliminary freezing cooling of the heating plate 5, the cooling rate of the heating plate 5 does not deteriorate, and additional cooling of the trap after preliminary freezing is also easy. be.

After entering the second step of vacuum freeze-drying, in the normal type, the temperature of the hot plate 5 is controlled by cold (about 0℃ to -30℃).
In order to do this, a sub-refrigeration device 12 and a side heat exchanger 8 are usually required.

However, in the case of the conventional "indirect heat medium type" shown in Fig. 2 and the "three-body heat exchange type" according to the present invention shown in Fig. 3, the heat medium system valve is installed between the trap circulation system and the hot plate circulation system. The sub-refrigeration device 12 and the side heat exchanger 8 are unnecessary by adjusting the amount of water to produce appropriate mixing.

The capacity of the refrigeration system 11, which is prepared for a larger steam condensation load due to the higher temperature of the hot plate 5, is naturally excessive for trap cooling when the hot plate 5 is controlled to cool. Does not occur.

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.

The above comparison of the "refrigerant direct cooling type" in FIG. 1 and the "indirect heating medium type" in FIG. 2 with the "three-body heat exchange type" according to the present invention shown in FIG. 3 is only an example. , the trap 103 in the embodiment of the present invention also serves as the heat exchanger 7 in the conventional system shown in FIGS. 1 and 2, and in comparison with the conventional system shown in FIG. Since the device 12 is not required, it is advantageous in terms of equipment cost and installation area.

In addition, if the requirements for the capacity balance of the device are special or under other circumstances, the entire capacity of the heat exchanger 7 and side heat exchanger 8 may not be transferred to the trap 103, but a portion may be transferred to another external heat exchanger. It is also possible to use a container or provide a separate refrigeration device in addition to the refrigeration device 11.

An embodiment of the structure of the trap 103 and the vacuum trap chamber 2 of the present invention has already been described with respect to the trap (steam condensation plate) 103 with reference to FIG. Steam inlet 2 connected to 1
As shown in FIG. 5, the steam flowing in from 3 condenses in a plurality of traps (steam condensing plates) 103 arranged in parallel on the left and right, descends while reducing the flow rate, and then flows into one of the plurality of traps 103 arranged in parallel on the left and right. It condenses on the back surface of the trap 103 located at the left and right ends, reaches the equilibrium vapor pressure of the trap temperature from the vacuum outlet 22, and reaches the vacuum exhaust thread while excluding non-condensable gases such as air.

In FIGS. 4 and 5, reference numeral 21 indicates a blocking plate, which prevents steam from reaching the vacuum outlet 22 directly.

The trap of the present invention is also effective in removing ice when steam freezes in the trap.

After all the steps are completed, when the heating medium is switched again to circulate through the flow path including the heating plate 5 and the heat medium liquid line path of the trap 103 (if it is insufficient, use the heater 6), the trap 1
The refrigerant in the refrigerant evaporator 03 is collected by the refrigeration device, and the temperature of the trap 103 is raised to 0° C. or higher, and the ice slides or peels off from the trap 103 plate and falls to the bottom.

Therefore, if a jacket heater 25 using a heat transfer liquid, hot water, steam, etc. is provided at the bottom, the ice can be quickly melted and removed without pouring water or blowing in steam from the outside.

24 is a water drain valve. The type of trap 103 of the present invention is not limited to the example shown in FIGS. 4 and 5.

For example, FIG. 6 is a separate case, and only a part of the surface (the inside of the cylinder in the figure) of the heat exchanger (cylindrical in the figure) between the refrigerant and the heat transfer liquid is used as a vapor condensation surface.

This is advantageous for small-volume traps, in which case load-balanced heaters can also be provided around the heat exchanger.

Note that the vacuum trap chamber 2 may be provided inside the vacuum drying chamber 1 without being separated from the vacuum drying chamber 1 by the main valve 3.

In the case of a freeze-drying device, if the trap is inside the vacuum drying chamber 1, when the trap functions as a heat exchanger for the refrigerant/heat medium liquid in the preliminary freezing process, the vacuum drying chamber 1 is evacuated to prevent heat input loss. It is not possible.

However, since the trap 103 according to the present invention cools the same indoor air as the hot plate 5 and the vacuum drying chamber 1 is thermally insulated, there is no large heat input loss.

[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 longitudinal schematic explanatory view of the trap chamber and the trap of the device of the present invention, FIG. 5 is a cross-sectional schematic explanatory diagram of the same as above, FIG. FIG. 8 shows another embodiment of the trap chamber and trap of the apparatus of the present invention, FIG. 7 is a longitudinal side view, and FIG. 8 is a longitudinal front view. Explanation of drawing symbols, 1...Vacuum drying chamber (also freezing chamber) 2...Vacuum trap chamber, 3...Main valve, 3a...Main pipe, 4... Vacuum exhaust system,
5... Heat plate (plate) 6... Heat medium liquid heater, 7... Heat exchanger, 8... Side heat exchanger, 7a. ...Refrigerant evaporator, 7b...
・Heating medium liquid thread, 8a... Refrigerant evaporator, 8b...
...Heating medium liquid thread. 9... Heat medium pump for hot plate, 10...
Trap heat medium pump, 11... Refrigeration device, 1
2... Sub-refrigeration device, 13... Refrigerant valve,
14... Refrigerant expansion valve, 15... Gate valve, 21... Shutoff plate, 22... Vacuum outlet, 23... Steam Inlet, 24... Drain valve, 25... Heater, 26... Refrigerant pipe, 27... Partition wall, 28... Trap Outdoor wall, 101, 102° 103... Trap, B... Heat medium liquid, R... Refrigerant, ■.
·····vapor.

Claims (1)

[Claims] 1 A heat exchanger between a refrigerant evaporator and a heat medium liquid in a refrigeration system,
All or part of the outer surface of the heat exchanger is provided at a position facing the vacuum space, and the heat exchanger is provided such that the outer surface metal plate facing the vacuum space is not exposed to either the refrigerant or heat transfer liquid side. , vapor in a vacuum device that also functions as a heat exchanger, which has a structure in which it is cooled directly or through direct metal contact without going through the other medium, and whose outer surface on the side of the vacuum space serves as a condensation and collection surface for the vacuum vapor. Condenser.