JPS59132903A - Concentrating crystallization method - Google Patents

Abstract

PURPOSE:To attain low temp. evaporation, continuous operation, energy conservation and simplification of equipment, by a method wherein waste heat is recovered by a heat pump cycle using the cycle of a freezer to be utilized as the heating source of solvent evaporation and a low temp. cooling liquid medium is further used as the cold heat source of a cooling process. CONSTITUTION:A liquid to be concentrated is heated and concentrated in a heater 2 by the latent heat of condensation of the hydraulic fluid from a heat pump. Further, the liquefied hydraulic fluid is heated and evaporated in a cooling medium evaporator 9 by the steam from the liquid to be concentrated generated from an evaporation boiler 3 to form a heat pump cycle. In addition, a part of the hydraulic fluid liquefied in the aforementioned cycle is guided to a cooling crystallization process to cool the concentrate in a cooler 25 and the dissolved component therein is crystallized while the evaporated hydraulic fluid is returned to the aforementioned heat pump cycle. As a result, heated steam required in evaporative concn. and low temp. cooling water in the cooling crystallization process become unnecessary and equipment for producing low temp. cooling water is also not necessitated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a layer line crystallization method for crystallizing crystals from various crystalline solutions.

The crystallization method is generally carried out by the following operations.

(1) The solvent in the solution is evaporated and the solution is raised to a saturation concentration or higher to precipitate crystals.

(2) Cool the solution) to lower the solubility and crystallize to a supersaturated state.

(3) The solvent in the solution is evaporated to a concentration close to saturation, and the solution is further cooled to reduce solubility and become supersaturated, thereby producing crystals.

Among these methods, method (2) is suitable for solutions with high solubility; in H solution, crystals cannot be crystallized when the concentration is low and the yield is poor, so it is suitable for solutions with low solubility. However, a large amount of low-temperature cooling water is required, especially when the solution temperature is low and the melting time is high)
In the case of a liquid solution, it is necessary to keep it at a very low temperature to increase the yield, but there is the problem of freezing.

Method (1) is used for general solutions (solutions with higher solubility as the temperature increases), and when operated at a high evaporation temperature, the degree of blackness is high (saturation), and a large amount of evaporation is required to crystallize the crystals. For this reason, the amount of heating steam is large, resulting in wasted energy. Furthermore, it is not suitable for solutions that are highly sensitive to heat and easily deteriorate. Therefore, by operating at a low evaporation temperature, the saturation concentration will be lower, the amount of evaporation will be less, and the amount of heating steam will be reduced, which will increase the recovery rate of crystals. Quite necessary.

Method (3) is a combination of method (1) and method (2). In this case, as in method (1), by operating at a low temperature, the amount of evaporation up to the saturated concentration can be reduced, and furthermore, since no evaporation operation is performed after the saturated concentration is reached, the amount of heating steam can be reduced. It is also ideal for solutions that are highly heat sensitive. In this method, concentration and cooling are performed in separate settings (iii
' is often processed in batch mode, which is inefficient (2
), low-temperature water and cooling equipment were required.

The present invention eliminates the above-mentioned drawbacks of the conventional methods and provides a crystal recovery rate that consumes the least amount of energy, is most suitable for solutions of heat-sensitive substances, and provides a continuous and efficient concentration method. The purpose is to provide a method for displaying items.

The present invention comprises a heating concentration step in which heating and concentration are repeated while circulating the liquid to be concentrated, and a cooling crystallization step in which cooling is repeated while circulating the concentrated liquid concentrated in the heating and concentration step, The concentration step and the cooling crystallization step are carried out simultaneously; the working fluid is circulated and operated, and the heating in the heating concentration step is performed by the latent heat of condensation of the working fluid in the pump cycle, and the operation during the cycle of the working original is performed. (1) Cooling in the cooling crystallization step is performed using the cold energy of the original material; heating evaporation of the refrigerant in the heat pump cycle is performed using vapor from the liquid to be concentrated obtained in the heating concentration step) layer line crystallization It's a method.

The present invention incorporates a heat pump cycle that utilizes a refrigerator cycle suitable for heat recovery at low temperatures into this concentration crystallizer, heats and concentrates the liquid to be concentrated using the latent heat of condensation of the working fluid of the heat pump, and further A heat pump cycle is formed by heating and evaporating the liquefied working fluid by the vapor from the liquid to be concentrated generated in the heating concentration step.
), there is no need for heated steam required for evaporation and concentration, and a part of the liquefied working fluid during the cycle is sent to the cooling crystallization process, and the liquefied working fluid removes the concentrated water from the heating and concentration process. By cooling the liquid and crystallizing the dissolved components, the cooled product and the working fluid that evaporated in the output process are returned to the beat pump cycle, thereby reducing the use of low-temperature cooling water in the cooling and crystallization process. This also eliminates the need for low-temperature cooling water production equipment. Furthermore, the same heat pump cycle is used for the heating concentration process and the cooling crystallization process.
), the performance of the equipment is always stable, equipment costs are low, and energy consumption in this process is also reduced.

Embodiments of the present invention will be described using the drawings.

In FIG. 1, the liquid to be treated is supplied from the supply liquid port 1 through the circulation line 4 to the heated side of the heating can 2,
Here, it is heated from the heating side by the latent heat of condensation of the refrigerant vapor, and is supplied to the evaporator 3 through the circulation line 5. The heated liquid to be treated is concentrated in the evaporator 3 until the evaporator itself concentrates the solvent to a supersaturated state or a saturated concentration or close to it. Most of the concentrated liquid is transferred to the circulation line 6 where heat is removed to the liquid circulation pump. It is again circulated to the heating can 2 and the evaporating can 3, where it is heated, evaporated, and concentrated in a heating concentration step.

The vapor of the evaporated solvent is sent through the steam pipe 8 to the heating side of the refrigerant evaporator 9, where it imparts heat to the refrigerant liquid, and the refrigerant itself condenses to become a solvent liquid and is discharged from the system through the drain outlet 10. Ru. Further, the non-condensable gas in the system on the side of the liquid to be treated is discharged from the non-condensable gas outlet 11 connected to the extraction device.

On the other hand, the heated refrigerant liquid evaporates into refrigerant gas, passes through the mist separator 12, becomes refrigerant gas, passes through the refrigerant gas line 13, and enters the compressor 14, where it is compressed and pressurized to increase the enthalpy. Then, it becomes a high-temperature refrigerant gas and enters the heating side of the heating can 2 through the refrigerant gas line 15.

Here, heat is radiated to the liquid to be treated, and the liquid itself condenses to become a refrigerant liquid, passes through a refrigerant liquid line 16, is depressurized by an expansion valve 17, and returns to the evaporation side of the refrigerant evaporator 9 again.

In this way, a refrigerator cycle (heat pump cycle) is formed.

Here, 18 is a refrigerant liquid circulation pump that supplies refrigerant liquid to the heat transfer surface, and 19.20 is a refrigerant liquid circulation line. Further, 21 is a heat remover that removes surplus heat within the system.

Next, a part of the concentrated liquid passes through the concentrated liquid line 23 and is extracted by the concentrated liquid extraction pump 22, and is drawn out from the cooled liquid circulation line 23.
9. The concentrated liquid is supplied to the cooled side of the cooler 25 through two cooled liquid circulation lines, where it radiates heat to the coolant liquid on the cooling side and becomes a low-temperature supersaturated solution and passes through the cooled liquid circulation line 30. The liquid then enters the crystallization can 26, where it is crystallized or pre-crystallized. Further, the solution in the crystallization can 26 is extracted through the cooled liquid circulation line 31, and is circulated again to the cooler 25 and the crystallization can 26 by the cooled liquid circulation pump 27, and is cooled in the cooling product discharge process. Perform crystallization and growth.

Since a part of the solution in the crystallization can 26 becomes surplus, heat is removed from the slurry outlet 32 along with the crystals, and the crystals and mother liquor are separated by the separation rock 28, and the crystals are extracted from the crystal outlet 33. Further, the mother liquor passes through the mother liquor line 34 by the mother liquor supply pump 35, and part or all of it is supplied from the mother liquor supply line 36 to the circulation line 4, where it is concentrated again to increase the yield of crystals.

37 is a mother liquor outlet line for extracting the mother liquor.

On the other hand, the refrigerant liquid on the cooling side removes heat from the middle of the refrigerant liquid line 16 next to the expansion valve, passes through the cooling refrigerant liquid line 38, is depressurized to the refrigerant evaporation side pressure at the expansion valve 39, and is cooled by lowering the temperature. is supplied to the cooling side of the vessel 25. Here, it is heated from the side to be cooled and evaporated under a constant pressure and temperature, and after the latent heat of vaporization cools the side to be cooled, it is returned to the evaporation side of the refrigerant evaporator 9 through the cooling refrigerant gas line 40. Ru.

The heating concentration step and the cooling crystallization step described above are carried out simultaneously, and a continuous process is performed instead of a batch process.

In this way, in a heat pump cycle using a refrigerator cycle, 11-heat is recovered and used as a heating source for solvent evaporation, and furthermore, by using a low-temperature refrigerant liquid as a cold heat source in the cooling process, low-temperature evaporation, continuous operation, and savings are achieved. It becomes possible to simplify energy and equipment.

FIG. 2 shows another embodiment, in which a low-temperature refrigerant liquid is used as the cooling refrigerant liquid. This low-temperature refrigerant liquid is transferred to the refrigerant circulation line 2.
0, the refrigerant liquid is sent by the refrigerant circulation pump 18 through the cooling refrigerant liquid line 38' to the cooling side of the cooler 25, where it is heated and evaporated, and passes through the cooling refrigerant gas line 40 again to the refrigerant evaporator 9. Return to the evaporation side. Here, 41 is a control valve that controls the amount of refrigerant liquid.

FIG. 3 shows another embodiment, in which the sensible heat of the refrigerant liquid is used. 42 is a refrigerant liquid level control valve that also serves as an expansion valve, 40'
is a cooling refrigerant gas line.

Figure 1:54 shows another embodiment, in which the cooling refrigerant gas evaporated in the cooler 25 is led to the compressor 14' and compressed, and then transferred to the discharge side of the compressor 14 by the refrigerant gas line 15' or 15''. Alternatively, the concentrate is supplied to the suction side.This allows the concentrate to be cooled to a particularly low temperature in the cooler 25.

The refrigerant liquid may be introduced from before the expansion valve 17 via the cooling refrigerant liquid line 38 . 43 is a mist separator.

The above embodiment is constructed and operates as described above, and has the following effects.

(A) By concentrating at low temperature and crystallizing by cooling after reaching the saturated concentration, (1) Suitable for treating liquids that are easily thermally decomposed.

(2) Since the amount of evaporation is small and the crystals are decoyed with a high recovery rate, less energy is required for heating, the equipment is smaller, and operating time is shorter (B) Waste heat is recovered in combination with a heat pump citral suitable for low temperatures. (1) No heating steam is required, resulting in energy savings. or(
From A), since the energy for heating is small, the power of the heat pump may also be small.

(,C) By operating the cooling crystallization process continuously and using the refrigerant liquid in the heat pump cycle as the cooling heat source, (1) Low-temperature cooling water production equipment is not required.

(2) No energy is required to produce low-temperature cooling water.

(3) Ideal for liquids that do not crystallize at low temperatures.

(4) Continuous operation ensures stable operation.

(5) Because the crystallization and heat recovery systems are separate, mist,
There is no problem with compressing and transporting crystals, etc.

According to the present invention, it is possible to provide a method for producing concentrated products that consumes less energy, can handle heat-sensitive substances, and performs efficient crystallization work continuously rather than in batches, and is extremely effective in practical use. play.

[Brief explanation of the drawing]

1-4 are flow diagrams of embodiments of the present invention. 1. Supply liquid inlet, 2. Each heating, 3. Evaporator, 4.
5.8...Circulation line, 7.Liquid circulation pump, 8.Steam pipe, 9.Refrigerant evaporator, 10.Drain outlet, 11.
・Noncondensable gas outlet, 12.・Mist separator, 13・
・Refrigerant gas line, 14° 14' ・・Compression section, 15.
15', 15''...refrigerant gas line, 1B...
Refrigerant liquid line, J7... Expansion valve, 18... Refrigerant liquid circulation pump, 19.20... Refrigerant liquid circulation line, 21... Heat remover, 22... Concentrated liquid extraction pump, 23.24... Concentration Liquid line, 25... Cooler, 26... Crystallization price, 27...
Cooled liquid circulation pump, 28...Separator, 29°30.3
1. Cooled liquid circulation line, 32. Slurry outlet, 3
3. Crystal outlet, 34. Mother liquor line, 35. Mother liquor supply pump, 36. Mother liquor supply line, 37. Mother liquor outlet line, 38°38'. Cooling refrigerant liquid line, 3. Expansion. Valve, 40.40' ... Cooling refrigerant gas line, 4th. 42...Control valve, 43...Mist separator. Patent Applicant: Ajinomoto Co., Ltd. Ebara Corporation, Representative Patent Attorney 1) Minoru Representative Friend f-Physician Takao Maruyama

Claims (1)

[Claims] 1. A heating concentration step in which heating and concentration are repeated while the liquid to be concentrated is circulated, and a cooling crystallization step in which a cooled product is repeatedly discharged while the concentrated liquid concentrated in the heating and concentration step is circulated. The heating concentrating step and the cooling crystallization step are carried out simultaneously; heating in the heating concentrating step is performed by the latent heat of condensation of the working fluid of a heat pump cycle that operates by circulating the working fluid; Concentration characterized in that the cooling in the cooling product output step is performed by the cold heat of the working fluid during the cycle; and the heating evaporation of the refrigerant in the heat pump cycle is performed by vapor from the liquid to be concentrated obtained in the heating concentration step. How to display items. 2. The method according to claim 1, wherein the cooling of the working fluid is performed using latent heat of vaporization of the working fluid. 3. The method according to claim 1, wherein the cooling of the working fluid by cold heat is performed by sensible heat of the working fluid. 4. A heating concentration step in which heating and concentration are repeated without circulating the liquid to be concentrated, and a cooling crystallization step in which cooling and crystallization are repeated while circulating the concentrated liquid concentrated in the heating and concentration step, The process and the cooling crystallization process are carried out simultaneously; the heat pump cycle operates by circulating the working fluid, and the heat in the heating and concentrating process is generated by the latent heat of condensation of the working fluid, and the operation of the working fluid during the cycle is carried out. Cooling is performed in the cooling crystallization step by the cold heat of the fluid; heating evaporation of the refrigerant in the heat pump cycle is performed by vapor from the liquid to be concentrated obtained in the heating concentration step, and the working fluid evaporated in the cooling crystallization step A method for producing a concentrated product, characterized in that the product is introduced into the heat pump cycle by a compressor.