JP2844295B2 - Vacuum concentrator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to, for example, fruit juices, enzymes,
By heating and evaporating the stock solution at a relatively low temperature, which is used to concentrate natural pigments, natural flavors, natural seasonings, yeast extracts, protein solutions, organic acids, nucleic acids, pharmaceuticals, etc., and to recover solvents from low-boiling solutions The present invention relates to a vacuum concentrator for concentrating, and more particularly, to a vacuum concentrator capable of obtaining extremely high thermal efficiency by combining with a heat pump.

[0002]

2. Description of the Related Art As a concentrating device for concentrating a stock solution at a relatively low temperature, a concentrating device using hot water heating has been conventionally used. However, a concentrating device using hot water heating has a drawback in that, since saturated steam is usually used as a heating source, the device takes a long time to start up, and it takes a long time to change the temperature setting. A vacuum concentrator using reduced pressure steam heating was developed to shorten the start-up time of the device. This apparatus generates saturated steam under a reduced pressure of 150 to 1100 Torr, and indirectly heats the stock solution by the latent heat of the steam.

[0003] The above-mentioned conventional vacuum concentrator has a short startup time, is easy to change the set temperature, and has high stability without abnormal temperature rise. However, a vacuum pump or an ejector is used to suck steam. Therefore, loss of steam is large, and maintenance work requires a great deal of labor because there are many system components. Further, since it is difficult to set the steam pressure to 150 Torr or less, the temperature of the heated steam is set at 60 Torr.
℃ or less, heat-sensitive juice, enzymes, natural pigments, natural flavors, natural seasonings, yeast extracts, protein solutions, organic acids, nucleic acids, can not be used for heat-concentrating applications, etc., There are many drawbacks such as the accuracy of adjusting the set temperature is relatively rough at ± 1 to 3 ° C.

In order to improve these drawbacks, a vacuum concentrator which can be used at a heating temperature of 60 ° C. or less by combining a heat pump and a vacuum evaporator has recently been proposed. This device is described in Japanese Patent Application Laid-Open No. 5-57101,
Developed for evaporating and condensing photographic processing waste liquid, etc., a coil-shaped condenser of a heat pump is placed in a condenser of a vacuum concentrator maintained at a reduced pressure by an ejector, and the waste liquid is reduced under reduced pressure. The water that has been heated and evaporated is cooled and condensed by a coil evaporator of a heat pump in a cooling chamber provided around the concentrating pot, and is taken out of the system as a drain.

[0005]

However, the above-mentioned Japanese Patent Application Laid-Open
In the known vacuum concentrator described in Japanese Patent No. 57101, a coiled condenser of a heat pump serving as a heating source is disposed in a vacuum pot and the waste liquid is directly heated. When it is concentrated, it has a drawback that it adheres to the surface of the coil-shaped condenser and is burnt, and that heat transfer is hindered and heat exchange efficiency is reduced. Also, the heat transfer to the undiluted solution is by natural convection, so the heat transfer efficiency is poor,
Particularly, in the case of an undiluted solution having a high viscosity, the solution is partially heated, so that the quality may be deteriorated, and there is a risk of causing burning. Furthermore, direct heating in this manner increases the entrainment of droplets, lowers the product yield, and in the case of a stock solution, which is likely to produce bubbles, tends to cause bumping and the like. As a result, the quality is reduced due to uneven heating, and the stock solution is reduced. The outflow can cause a significant decrease in yield.

Further, since this known vacuum concentrator employs a vacuum generation method using an ejector, the degree of vacuum becomes unstable due to a change in the temperature of the circulating cooling water, causing a variation in quality and the generation of condensed water. Due to the use, the entrained droplets may contaminate the circulating water and the ejector pump and cause a failure thereof. Further, this known vacuum concentrator uses a condenser of a heat pump as a heating source. However, since the latent heat of vaporization of Freon usually used as a heating medium is relatively low, (for example, Freon 22 at 35 ° C.). Has a latent heat of vaporization of 41 kcal / kg and a latent heat of vaporization of water of 577 kcal / kg).

The present invention solves the above-mentioned drawbacks of the known vacuum concentrator and can be used at a heating temperature of 60 ° C. or lower, has a high heating efficiency, does not require the use of steam and cooling water, and is stable. Excellent operability and operability, as well as product quality,
It is an object of the present invention to provide a vacuum concentrator having a high yield and a high output per unit time.

[0008]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a heat exchanger for indirectly heating a stock solution by a reduced pressure steam generated by a reduced pressure steam generator using a heat pump as a heating source, It has been found that the above-mentioned object can be achieved by separating the concentrated solution from a vacuum concentrator that boils at a low temperature under reduced pressure and forcibly circulating the solution by a circulation pump between the two.

That is, the vacuum concentrator according to the present invention
(A) In a circulation line connecting a compressor, a heat exchange coil, a condenser, an expansion valve, a heat exchanger for a vapor condenser, and an evaporator, a branch is made from between the condenser and the expansion valve and through another expansion valve. A heat pump configured to be capable of switching between a heating cycle and a refrigeration cycle by providing a bypass pipe line leading to the heat exchange coil and providing an electromagnetic valve for switching a flow path for supplying refrigerant to the two expansion valves; b) a reduced-pressure steam generator for generating reduced-pressure steam of a liquid heat medium under reduced pressure by indirect heat exchange with a heat exchange coil serving as a heating source in the refrigeration cycle of the heat pump; (c) generated by the reduced-pressure steam generator A stock solution heating heat exchanger for latent heat of the stock solution by indirect heat exchange with reduced pressure steam, and (d) a stock solution at a low temperature under reduced pressure. A vacuum evaporator comprising a stock solution concentrating unit for concentrating and concentrating and a vapor condenser for cooling and concentrating the steam generated in the stock solution concentrating unit by indirect heat exchange with a heat exchanger serving as a cold heat source in the refrigeration cycle of the heat pump. A circulation pipe is provided for forcibly circulating the undiluted solution by a circulating pump between the undiluted solution concentration section of the vacuum evaporator and the undiluted solution heat exchanger.

The reduced-pressure steam generator and the stock solution heating heat exchanger may be constructed separately and connected to each other by a pipe. However, the reduced-pressure steam generator and the stock solution heating heat exchanger are connected to each other. They may be integrated into one vacuum vessel. When starting the vacuum concentrator, it is necessary to first lower the temperature of the liquid heat medium supplied to the reduced-pressure steam generator from the operating temperature. Therefore, at the time of start-up of the apparatus, there is provided a set temperature control mechanism for the liquid heat medium that sets the temperature of the liquid heat medium introduced into the reduced pressure steam generator to the set temperature by indirect heat exchange with a cold heat source in the heat cycle of the heat pump. .

In addition, the set temperature adjusting mechanism for the liquid heat medium is not provided separately in the reduced-pressure steam generator, but is provided with a condenser serving as a heating source in a refrigeration cycle of the heat pump and a pipeline of the heat pump. By switching, the function can be exhibited by also using the evaporator serving as a cold heat source in the heating cycle.

The vacuum evaporator is a cyclone type having a stock solution concentrating unit in the lower half and a vapor condenser in the upper part, and the stock solution heated by the stock solution heating exchanger is tangential to the inner surface of the can from the cylindrical side wall of the evaporator. It is injected by a stock solution supply nozzle in the direction. A liquid circulation pump is attached to the bottom of the evaporator via a conduit so that the stock solution is forcibly circulated between the stock solution heating exchanger and the vacuum evaporator.

[0013]

Since the vacuum concentrator of the present invention is configured as described above, the undiluted solution is forcibly circulated in the undiluted solution heat exchanger in the reduced-pressure steam generator in the refrigerating cycle of the heat pump. It is indirectly heated by the reduced pressure steam generated by being heated by the heating source. Then, the heated undiluted solution is introduced into a vacuum evaporator, and boiled under reduced pressure at a low temperature to be concentrated. At this time, the generated steam is condensed by heat exchange with a cold heat source in a refrigeration cycle of a heat pump in a vapor condenser above the vacuum evaporator, and is taken out of the system as a drain.

[0014]

【Example】

(Embodiment 1) An embodiment of the present invention will be described with reference to FIG.
The vacuum concentrator according to the present embodiment includes a vacuum evaporator 1, a reduced-pressure steam generator 20, and a heat pump 30, and the heat exchanger 7 for heating a stock solution is integrated into the reduced-pressure steam generator 20. The vacuum evaporator 1 comprises a closed cyclone-type can body provided with a stock solution concentrator 2 at the lower part and a vapor condenser 3 at the upper part. Reference numeral 4 denotes a liquid circulation pump which is a heat exchanger 7 for heating a raw liquid provided in a circulation line 15-a reduced-pressure steam generator 20-a circulation line 16-a liquid amount adjusting valve 8--for a raw liquid extracted from the raw liquid concentrating unit 2. It is circulated through the undiluted solution supply nozzle 9 to the vacuum evaporator 1.

Reference numeral 5 denotes a stock solution supply tank,
The stock solution is supplied to the circulation line 15 via the flow control valve 19. Reference numeral 6 denotes a pump for taking out a concentrated liquid, which is a pump for taking out the product concentrated from the circulation line 15 through the concentrated liquid taking-out line 14. The liquid amount control valve 8 is for controlling the amount of evaporation in the vacuum evaporator 1, and is used to balance the amount of evaporation of the stock solution in the vacuum evaporator 1 with the cooling and condensing power in the vapor condenser 3. The opening of the valve is automatically adjusted according to the inlet temperature of the heat exchanger 38 for the vapor condenser.

Reference numeral 10 denotes a level sensor for measuring the level of the stock solution in the evaporator 1. The liquid amount control valve 19 automatically adjusts the amount of the stock solution introduced into the evaporator 1 in conjunction with the level sensor 10. The stock solution supply nozzle 9 injects and feeds the stock solution tangentially to the inner surface of the side wall of the evaporator 1. A drain tank 11 receives the condensed liquid condensed by the vapor condenser 3 through a pipe 17. Reference numeral 12 denotes a vacuum pump, and lines 17 and 1
This is for making the inside of the vacuum evaporator vacuum through the process 8.

The reduced-pressure steam generator 20 comprises a sealed can body provided with a reduced-pressure steam generator 21 at the lower part and a heat exchange part 22 containing the heat exchanger 7 for heating the undiluted solution at the upper part, and a liquid at the lower part. A water supply pipe 23 for supplying water as a heat medium is connected to a pipe 24 connected to a vacuum pump 25 for pressure adjustment at an upper part thereof. Reference numeral 26 denotes a pressure gate valve which is automatically closed when the pressure of the reduced-pressure steam generator 20 reaches a set pressure.

[0018] 30 is a heat pump, heating Sai
And a refrigeration cycle.
You. That is, in the heating cycle, the bypass line 57
The provided discharge gas solenoid valve 43 is turned on, and the discharge gas solenoid valve 42
Off; liquid solenoid valve 49 on; liquid solenoid valve 48 off;
The suction gas solenoid valve 45 provided in the bypass passage 56 is turned on,
Turn off the solenoid valve 50, and set the compressor 31-oil separator
Letter 32-Discharge gas solenoid valve 43-Subcondenser 34-
Receiver tank 35-Filter dryer 36-Liquid solenoid valve
49—expansion valve 47 provided in bypass line 58—for heat exchange rubber
Coil 33-liquid solenoid valve 45-sub-condenser 39-space
Of the accumulator 40-filter 41-compressor 31
Configure the circuit. In this closed circuit, the sub-capacitor 34
Is a refrigerant that has been compressed by the compressor 31 and has become high temperature.
Therefore, the air is cooled by the blower 51. this
The generated heating air is used as a heat source for other heat consuming equipment and heating
Can be used for Also, the pressure or temperature in the system
Turns on the blower 52 for air cooling of the sub-condenser 39-
Adjust by turning off. On the other hand, the expansion valve 47 insulates
The expanded and liquefied refrigerant is subjected to heat exchange with the reduced-pressure steam generator 20.
The liquid in the vacuum steam generator 20 in the replacement coil 33
Absorbs heat from the heat medium and evaporates. Therefore, reduced pressure steam
The refrigerant in the heat exchange coil 33 of the creature 20 generates vacuum steam.
Set the temperature of the liquid heating medium in the creature 20 by indirect heat exchange.
Functions as a cold heat source for cooling to

In the refrigeration sigle, the discharge gas solenoid valve 42
On, discharge gas solenoid valve 43 off; liquid solenoid valve 48 on
The liquid solenoid valve 49 is turned off; the liquid solenoid valve 50 is turned on,
The solenoid valve 45 is turned off, and the compressor 31
Pallet 32-Discharge gas solenoid valve 42-Heat exchange coil 33
-Liquid solenoid valve 50-sub-condenser 34-receiver tank
35-filter dryer 36-liquid solenoid valve 48-expansion valve 4
6-Heat exchanger for vapor condenser 38-Sub evaporator
Data 39 (sharing the sub-condenser 39 of the heating cycle
-Accumulator 40-filter 41-compressor
A closed circuit is formed during the concentration operation of the fuel cell 31. This frozen rhino
Sub-condenser 34, sub-evaporator 39
To the blowers 51 and 52 and the bypass pipe 55
The provided intake gas solenoid valve 44 is controlled by the pressure (temperature) in the system.
On-off control to maintain the pressure of discharge 1 constant.
You. In this closed circuit, the heat exchanger of the vapor condenser 3
38 is adiabatically expanded by the expansion valve 46.
And the temperature drops, and the solution is concentrated in the concentrate concentrate 2 of the vacuum evaporator 1.
To cool and condense the steam generated by indirect heat exchange
Functions as a heat source. On the other hand, heat exchange of the reduced-pressure steam generator 20
The refrigerant flowing through the replacement coil 33 is supplied to the compressor 31.
Therefore, it is compressed and becomes high temperature, and the inside of the vacuum steam generator 20 is
As a heating source to heat a liquid heat medium by indirect heat exchange
Function. 37 is a discharge side pressure gauge, 53 is a pressure switch,
54 is a suction side pressure gauge, and 59 is a bypass line. Note that Freon 22 is used as the refrigerant.

(Embodiment 2) As shown in FIG. 2, in the vacuum concentrator according to this embodiment, a reduced-pressure steam generator 20 and a heat exchanger 7 for heating a stock solution are separately provided. The reduced-pressure steam generated by the reduced-pressure steam generator 20 is introduced into the upper portion of the stock solution heating heat exchanger 7 by the communication pipe 29, and the stock solution flowing through the stock solution heating coil 27 provided in the heat exchanger 7 is removed. After the latent heat, the water is drained and returned to the reduced-pressure steam generator 20 through the pipe 28 from below the heat exchanger 7.

Next, a method of operating the vacuum concentrator configured as described above will be described with reference to the first embodiment. <Adjustment of Pressure in Vacuum Generator at Startup> First, the refrigerant circuit of the heat pump 30 is set to a heating cycle operation. For this purpose, the discharge gas solenoid valve 43, the suction gas solenoid valve 4
5, the liquid solenoid valve 49 and the blower 51 are turned on, and the compressor 31-oil separator 32-discharge gas solenoid valve 43-
Sub-condenser 34-Receiver tank 35-Filter dryer 36-Liquid solenoid valve 49-Expansion valve 47-Heat exchange coil 33-Suction gas solenoid valve 45-Sub-condenser 39 (Shares sub-evaporator 39 in the refrigeration cycle)
-Accumulator 40-Filter 41-Compressor 3
1 is formed.

Then, the discharge gas solenoid valve 43, the suction gas solenoid valve 45, and the liquid solenoid valve 49 are turned on, and the blower 52 of the sub-condenser 39 is turned on and off to control heat exchange in the reduced-pressure steam generator 20. The coil 33 is cooled to cool the temperature of the water in the reduced-pressure steam generating section 21, and the pressure of the heat exchanging section 22 is adjusted to a temperature necessary for concentration by the pressure adjusting vacuum pump 25.
Adjust with.

<Concentration Operation> When the pressure in the reduced-pressure steam generator 20 reaches a predetermined pressure, the refrigerant circuit of the heat pump 30 is switched to a refrigeration cycle. For this purpose, the discharge gas solenoid valve 42 and the liquid solenoid valves 48 and 50 are turned on, and the blower 51 of the sub-condenser 34 and the sub-evaporator 39 are turned on.
By operating the blower 52 and the suction gas solenoid valve 44 on and off with the pressure or temperature in the system, the heat exchange coil 33 in the reduced-pressure steam generator 20 is heated, and the water in the reduced-pressure steam generator 21 is heated. Is heated and boiled at a low temperature to generate reduced-pressure steam.

The degree of vacuum in the vacuum evaporator 1 is controlled by a vacuum pump 12
After setting the pressure to the set pressure, the stock solution is supplied from the stock solution supply tank 5 to the stock solution heating heat exchanger 7 in the reduced-pressure steam generator 20 via the stock solution supply line 13 and the circulation can passage 15. The stock solution in the heat exchanger 7 is indirectly latent-heated by the reduced pressure steam generated by being heated by the heat exchange coil 33 of the heat pump 30. The heated stock solution is supplied to the stock solution concentrating unit 2 of the vacuum evaporator 1 via the circulation line 16. The level of the undiluted solution in the undiluted solution concentrating unit 2 is measured by the level sensor 10, and the result is fed back to the liquid amount control valve 19 to adjust the flow rate of the newly supplied liquid. The stock solution in the stock solution concentrating unit 2 boils at a low temperature in accordance with the degree of vacuum in the vacuum evaporator 1 and evaporates and concentrates water. The evaporation amount is controlled by the inlet temperature of the heat exchanger 38 of the vapor condenser 3. The adjustment is performed by adjusting the opening of the liquid amount control valve 8.

The generated steam is supplied to the heat exchanger 3 to which the heat of the heat pump 30 is supplied in the vapor condenser 3.
8 indirectly cooled. The condensed water that has been cooled and condensed is stored in the drain tank 11 via a pipe 17 and discharged out of the system via an on-off valve. On the other hand, the concentrate, which is a product, is taken out by the concentrate take-out pump 6 via the concentrate take-out line 14 branched from the circulation line 15 downstream of the circulation pump 4.

<Operation Example> First, the heat pump 30 is set to a heating cycle, the heat pump 30 is started, and the water in the reduced-pressure steam generator 20 is cooled to about 30 ° C. Next, the vacuum pump 25 is started to adjust the pressure in the reduced-pressure steam generator 20 to 40 Torr, and the pressure regulating valve 26 is closed. Next, the heat pump 30 is switched to a refrigeration cycle, and the water in the reduced-pressure steam generator 21 is heated by the heat exchange coil 33. This heating produces a reduced pressure steam of about 45 ° C.
On the other hand, the pressure in the vacuum evaporator 1 is set to 10 Torr by the vacuum pump 12. When the pressure in the evaporator 1 reaches the set pressure, the stock solution circulating pump 4 is started to send the stock solution to the stock solution heating heat exchanger 7 to start the concentration operation.

The operating conditions and the results are as follows. Raw material: orange juice Stock solution composition: water 87.5 wt% Stock solution preparation amount: 151.8 kg Stock solution inlet temperature (in stock solution supply line 13) 15 ° C Stock solution heating temperature (in stock solution heating heat exchanger 7) 34 ° C Evaporation temperature ( Vacuum evaporator 1) 15-20
℃ Operating vacuum (in vacuum evaporator 1) 10-15
Torr Heat source temperature (heat exchange coil 33) Approx. 45 ° C. After operating for 2 hours under these conditions, the concentrated liquid (water content of 62.5%) was obtained.
50.5 kg). As a result of a panel test, it was evaluated that the color and flavor of the obtained product were not different from those of the stock solution.

[0028]

The vacuum concentrator according to the present invention separates a heat exchanger for indirectly heating the stock solution by reduced pressure steam and a vacuum concentrator for boiling the heated stock solution under reduced pressure at a low temperature. Since the undiluted solution is forcibly circulated by the circulation pump, the undiluted solution is not concentrated in the heat exchanger for heating the undiluted solution, so that the concentrate hardly adheres to the heating surface. As a result, non-uniform heating, local overheating, bumping, etc. do not occur, and there is no risk of burning of the concentrate and deterioration of product quality.

Since the reduced-pressure steam for heating the undiluted solution is heated by the heating source in the refrigeration cycle of the heat pump having good heat response in the reduced-pressure steam generator, the rising time can be short and the set temperature can be changed. Easy. In addition, since it is possible to adjust the heating temperature and pressure in small amounts, and because there is little variation in the set temperature and pressure,
Stable operation becomes possible. Since the undiluted solution is heated indirectly by the reduced-pressure steam while being forcibly circulated in the heat exchanger, the heat efficiency is extremely high, and since the undiluted solution is uniformly heated, no seizure or deterioration occurs. In addition, since the processing time is short, it is possible to increase the production efficiency and to avoid the deterioration in quality due to long-time heating.

Since the undiluted solution flowing in the pipe-shaped heat exchanger is indirectly heated by the latent heat of the depressurized steam, the undiluted solution is directly heated by installing a condenser of a heat pump in the evaporator. The amount of heat transfer is much higher than in the case where the heating is performed, and efficient heating can be performed. That is, CFC 2 which is usually used as a heat medium of a heat pump is used.
2 and steam at 35 ° C., the former was 41 kcal / kg and the latter was 577 kcal / kg.
/ Kg and a difference of 10 times or more, the heating efficiency per unit flow rate is 7 to 12 times as much as the actual value, and the method using the reduced pressure steam of the present invention is superior.

The undiluted solution heated by the undiluted solution heat exchanger is injected into the tangential direction of the inner surface of the can from the side wall of the cyclone-type evaporator by the undiluted solution supply nozzle. Efficiency can be improved.
The heated undiluted solution is introduced into a vacuum evaporator and is boiled at a low temperature under reduced pressure to be concentrated.
It can be concentrated at any set temperature in the range of 0 to 110 ° C., and the set temperature can be easily changed. Furthermore, since heating is not performed in the evaporator, reduction in product yield due to seizure, bumping, and entrainment of generated steam can be avoided.

Since the vapor condenser attached to the vacuum concentrator is cooled by the cold heat source in the refrigeration cycle of the heat pump having good heat response, it is possible to adjust the minute amount of the cooling temperature and to reduce the variation in the set temperature. Therefore, stable operation is possible. Further, it is easy to change the set temperature.

Since the reduced pressure steam used for heating the undiluted solution is used in a closed system, it is not necessary to supply water during operation.
Other cooling water for condensers is not used at all.
The consumption of water is extremely small, and the operation of the apparatus does not require any energy other than electric power, so that the operation and management of the system are extremely easy. Since the heat exchange section for heating the undiluted solution is in the steam atmosphere of the vacuum steam generator, it has less corrosion and can reduce maintenance costs.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a vacuum concentrator according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a main part of a vacuum concentrator according to another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 vacuum evaporator 2 stock solution concentrating unit 3 vapor condenser 4 stock solution circulation pump 5 stock solution supply tank 6 stock solution take-out pump 7 stock solution heating heat exchanger 8 liquid volume control valve 9 stock solution supply nozzle 10 level sensor 11 drain tank 12 vacuum pump 15 Circulation line 16 Circulation line 20 Decompression steam generator 21 Decompression steam generation unit 22 Heat exchange unit 23 Water supply pipe 24 Pipe line 25 Pressure adjustment vacuum pump 26 Pressure gate valve 27 Stock solution heating coil 30 Heat pump 31 Compressor 33 Heat exchange coil 34 Subcondenser 35 Receiver tank 38 Heat exchanger for vapor condenser 39 Subevaporator 40 Accumulator 42 Discharge gas solenoid valve 43 Discharge gas solenoid valve 44 Intake gas solenoid valve 45 Suction gas solenoid valve 46 Expansion valve 47 Expansion valve 48 Liquid solenoid valve 49 Liquid Solenoid valve 50 Liquid solenoid valve 51 Blower 52 Blower

Continuation of the front page (56) References JP-A-4-338241 (JP, A) JP-A-63-54901 (JP, A) JP-A-5-57101 (JP, A) JP-A-60-147067 (JP) JP-A-4-338949 (JP, A) JP-A-2-57101 (JP, U) JP-A-4-15194 (JP, Y2) European Patent Publication 6612 (EP, A) (58) Search Field (Int.Cl. ⁶ , DB name) B01D 1/28 B01D 1/00 F25B 30/04 510 A23L 2/08

Claims (4)

(57) [Claims] In a circulation line connecting a compressor, a heat exchange coil, a condenser, an expansion valve, a heat exchanger for a vapor condenser, and an evaporator, another expansion valve is branched from between the condenser and the expansion valve. A heat pump configured to be able to switch between a heating cycle and a refrigeration cycle by providing a bypass pipe line that leads to the heat exchange coil through the heat exchange coil, and by providing an electromagnetic valve that switches a flow path that supplies a refrigerant to the two expansion valves. A reduced-pressure steam generator that generates reduced-pressure steam of the liquid heat medium under reduced pressure by indirect heat exchange with a heat exchange coil that acts as a heating source in the refrigeration cycle of the heat pump, and a reduced-pressure steam generated by the reduced-pressure steam generator. A stock solution heating heat exchanger that heats the stock solution by latent heat by indirect heat exchange, and concentrates the stock solution by boiling it at low temperature under reduced pressure A vacuum evaporator comprising a stock solution concentrating unit and a vapor condenser for cooling and condensing the steam generated in the stock solution concentrating unit by indirect heat exchange with a heat exchanger serving as a cold heat source in the refrigeration cycle of the heat pump, A vacuum concentrator comprising a circulation pipe for forcibly circulating a stock solution by a circulation pump between a stock solution concentrating section of the evaporator and the stock solution heating heat exchanger. 2. The vacuum concentrator according to claim 1, wherein the reduced-pressure steam generator and the stock solution heating heat exchanger are integrated into one vacuum vessel. 3. The evaporator according to claim 1, wherein the vacuum evaporator has a cyclone shape, and a stock solution introduction nozzle for tangentially introducing a stock solution heated by a stock solution heating heat exchanger to a cylindrical inner wall of the evaporator. The vacuum concentrator according to claim 1, wherein the vacuum concentrator is attached to a side wall. 4. When the apparatus is started, the temperature of the liquid heat medium introduced into the reduced-pressure steam generator is set to a set temperature by indirect heat exchange with a heat exchange coil serving as a cold heat source in a heating cycle of the heat pump. The vacuum concentrator according to claim 1, further comprising a set temperature adjusting mechanism for the liquid heat medium.