JP4121682B2 - Method and apparatus for solvent separation and concentration of solution - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to separation and concentration of an aqueous solution, and more particularly, to a solvent separation and concentration method and apparatus for a solution that enables final concentration and volume reduction in order to improve water and energy saving in a wastewater treatment process of industrial waste liquid.
[0002]
[Prior art]
Conventionally, as a wastewater treatment method for industrial waste liquid, the microbial treatment of FIG. 2 is used as a main treatment method for waste liquid with a high organic content, and the incineration treatment of FIG. 3 is used for waste liquid with a high inorganic content. Further, for example, the method shown in FIG. 4 has been used for the concentration of the waste liquid, particularly the concentration of the waste water.
[0003]
FIG. 2 shows a wastewater treatment method by microbial decomposition of organic waste liquid. The stock solution 50 is stored in the microbial decomposition tank 51, and if the stored supernatant solution is confirmed to have a component concentration equal to or lower than an allowable value, it is discharged to the outside and the external drainage 53 is performed. The remaining sludge deposit 52 is subjected to a combustion process of combustion 54 or is effectively used 55 as fertilizer, waste solid fuel (RDF) or the like.
[0004]
FIG. 3 shows a direct combustion treatment method of waste liquid in which the raw waste liquid 56 is combusted in the direct combustion furnace 57. As a matter of course, since it contains a large amount of water, a large amount of fuel is required. The water becomes water vapor and is released into the atmosphere as combustion gas 58, and the remaining solid material 59 becomes ash and is finally disposed of.
[0005]
In the method shown in FIG. 4, in order to reduce the fuel of the direct combustion treatment method, the waste liquid concentration is raised to some extent by heating the raw waste liquid to the atmosphere with a vacuum pump or the like while heating the raw waste liquid. This is a vacuum concentration combustion treatment method for burning.
That is, the raw waste liquid 60 is discharged into the atmosphere by evaporating moisture generated by heating in the concentration tank 61 by the vacuum pump 62, and the high-concentration waste liquid is incinerated in the incinerator 63 to discharge solid matter (ash) 64 and combustion gas. 65 atmospheric release is possible.
In the above case, when the concentration treatment plant and the combustion treatment plant are separated from each other, the transportation cost is reduced to some extent by the concentration and volume reduction.
[0006]
The wastewater treatment methods for industrial waste liquids shown in FIGS. 3 and 4 are energy savings such as a large amount of fuel consumption, generation of exhaust gas and carbon dioxide, generation of transportation costs (mainly fuel costs), and release of treated wastewater. It has caused undesirable results from a water and environmental perspective.
[0007]
Incidentally, in addition to the concentration method shown in FIG. 4, there are a freeze concentration method and a vapor recompression concentration method used in the food industry.
FIG. 5 shows a freeze-concentration method conventionally used for concentrating juice. The water in the stock solution 66 is freeze-removed by a freeze concentration device 67 so that the concentrated residual liquid is used as the concentrated juice 68, and the freeze-removed water is treated as the drainage 69.
In this case, since quality change due to evaporation by heating can be avoided, it has been used in the field of coffee, beer and the like as a concentration method with little fragrance dissipation and almost no component change and no heating.
In the case of freeze concentration, there is a problem that as the concentration progresses, the freezing temperature decreases and the solution viscosity also increases, making it difficult to separate the concentrate from the ice crystals and to recover the concentrate attached to the ice crystals.
[0008]
FIG. 6 shows a vapor recompression concentration method using a wort boiling pot of beer. This is an improvement of the conventional method of boiling and concentrating wort in which water vapor containing odors generated from wort by direct heating in a conventional boiling pot is released into the atmosphere. The wort boiling pot 70 functions as a concentrating kettle. The steam generated is compressed and heated through the steam compressor 71, and the heated high-pressure and high-temperature steam is reused as the heating steam for the wort boiling pot 70 through the heater 74. The amount of input energy is greatly reduced compared to the kettle.
The steam supplied to the heater 74 is gradually condensed inside, and the whole amount of the supplied steam is condensed and discharged to the outside as drainage 73. The vapor recompression concentration method is said to reduce the energy required for heating to about 1/4 compared with the conventional method, and further has the advantage that the problem of environmental pollution due to the odor of the conventional method is eliminated.
[0009]
The concentration methods shown in FIGS. 5 and 6 are well known to be applicable to the concentration of waste liquid, but have not yet been used due to facilities, equipment costs, operability, etc. It is.
However, recent water shortages and river, lake, and groundwater contamination indicate that freshwater conservation measures are in a critical phase. On the other hand, there is no waiting for energy-saving measures to prevent global warming. With regard to the wastewater drainage treatment method, the conventional simple combustion treatment causes waste of energy and water resources and air pollution, so that immediate measures are desired.
[0010]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a solvent separation and concentration method for a solution and an apparatus thereof that enable final concentration and volume reduction in order to improve water and energy savings. .
[0011]
[Means for Solving the Problems]
The feature of the present invention considered as a means for solving the problem is that a vapor recompression concentrating device is disposed after the freeze concentrating device. What is important is this arrangement order, and the expected effect cannot be obtained in the configuration in which the freeze concentration apparatus is arranged after the vapor recompression concentration apparatus. That is, freeze concentration is performed with a low-concentration aqueous solution having a lower waste liquid concentration, and vapor recompression concentration is performed on the concentrated aqueous solution having a high concentration by freeze concentration.
[0012]
Therefore, the solvent separation and concentration method of the solution of the present invention includes:
In the solvent separation and concentration method for solutions such as industrial waste liquid,
Steam recompression, in which the first stage of solvent concentration is performed by freeze concentration in which water is freeze-concentrated from a low-concentration aqueous solution such as industrial waste liquid, and the water is vaporized and separated from the high-concentration aqueous solution obtained by the freeze-concentration by heating. Concentrate in the second stage by concentration, and perform final concentration and volume reduction. The frozen ice obtained by freeze-concentration is used for cold heat by heat exchange with a load via an ice accumulator, and the steam recompression The steam heat obtained by the concentration is used as a heating source for the high-concentration aqueous solution.
[0013]
The invention described in claim 1 is a low concentration aqueous solution containing a large amount of water in order to remove water contained in a solution such as wastewater as much as possible by concentration treatment in a solvent separation and concentration method for a solution such as industrial waste liquid. Concentrate the first stage by freeze concentration, and then concentrate the concentrated aqueous solution that has become high concentration by the above-mentioned concentration by vapor recompression and concentrate to the final concentrate. The volume was reduced.
In freezing and concentrating, the surface of frozen ice is frozen before freezing and separation, as described later, and the use of cold heat by the latent heat and sensible heat of frozen ice through an ice reservoir that stores frozen ice obtained by freezing separation. The de-iced water that has been thawed after washing with clean water can be used as industrial water or medium water,
Further, the condensed water obtained in the vapor recompression concentration removes harmful components by adsorption, as described later, and enables effective use as industrial water or intermediate water.
[0014]
The freeze concentration according to claim 1 is characterized in that the purity of the deicing water can be improved by washing the ice surface immediately before the freeze separation with the deicing water.
[0015]
According to the second aspect of the present invention, in the deicing after the icing to the heat transfer surface of the ice making heat exchanger in the freezing and concentrating ice making chamber, a deicing step is performed immediately before the deicing. The ice surface was washed to clean the deicing water.
By carrying out the above purification, harmful components are removed from the surface of the frozen ice, and the frozen ice that has been removed and cleaned can be effectively used as industrial water or medium water as described above.
[0016]
Further, in the vapor recompression concentration according to claim 1, the condensate is cooled by heat exchange with the high concentration aqueous solution obtained by the first stage concentration, and the efficiency of odor and specific components via the adsorbent. It is characterized in that it can be removed.
[0017]
In the third aspect of the invention, since the condensate in vapor recompression concentration contains harmful specific components and odors, it is condensed by heat exchange with a low-temperature high-concentration aqueous solution after completion of the first-stage concentration. The liquid temperature of the liquid is lowered so that it can be adsorbed by the adsorbent, and the specific components and odors are removed. By the removal, the water can be used as industrial water or middle water.
[0018]
An apparatus for separating and concentrating a solvent of a solution using the invention according to claim 1, claim 2, and claim 3,
In industrial wastewater wastewater treatment equipment,
A circulating water tank that stores a low-concentration aqueous solution and circulates the concentrated liquid until a high-concentration aqueous solution is obtained by concentration in the first stage, an ice-making chamber that receives and supplies the low-concentration aqueous solution from the circulating water tank, and freezes in the ice-making chamber A freezing and concentrating apparatus mainly comprising a refrigerator for supplying cold and deicing heat, and an ice accumulator for storing frozen ice separated from frozen ice and supplying cold and deicing water to the outside,
A condenser that heats and evaporates the first-stage concentrated high-concentration aqueous solution stored in the circulating water tank, a vapor compressor that compresses the vapor evaporated from the condenser, a condenser that condenses the compressed vapor and a condenser It is characterized by comprising a vapor recompressing and concentrating apparatus having as main components a heater that heats and an adsorber that adsorbs odors and specific components from condensed water.
[0019]
When the concentration proceeds and the concentration of the aqueous solution in the circulating water tank reaches a predetermined concentration, the circulation of the aqueous solution and the supply of cold heat are stopped and the freezing is terminated. In this case, the ice surface during ice making is considerably dirty because it is always in contact with the spray water of the raw waste liquid, but the purity inside the ice is quite high. In order to improve the purity of the deicing water, at the end of the freezing, clean deicing water is sprayed on the frozen surface immediately before deicing, the ice surface is washed, and the washing water is returned to the circulating water tank. After that, the operation of the refrigerator is switched to the deicing operation, freezing and separation are performed to open a passage to the ice accumulator, and the frozen ice separated by freezing flows into the ice accumulator through the passage.
Thus, the deicing water purity in the ice storage tank is improved and ideal clean ice can be obtained.
[0020]
The condensate obtained by the vapor recompressing and concentrating apparatus may contain a harmful medium having a lower boiling point than water, and may contain an odor component in some cases. For this reason, the harmful components are removed by passing through the adsorbent immediately before extracting condensed water from the condensate. In the conventional method, the condensed water is discharged to the outside as it is. In general, the lower the condensed water solution temperature, the greater the adsorption effect of the adsorbent. From the viewpoint of adsorption effect and energy saving, the high-concentration aqueous solution from the freeze concentrator to the vapor recompression concentrator is lifted through a heat exchanger. It is desirable to lower the temperature of the condensate before the adsorption treatment to be taken out while heating.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative positions, and the like of the components described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention unless otherwise specified. Absent.
FIG. 1 is a diagram showing a schematic configuration of a solvent separation and concentration apparatus for a solution of the present invention.
[0022]
As shown in FIG. 1, the solvent separation and concentration apparatus for a solution of the present invention includes a freeze concentration apparatus 10 and a vapor recompression concentration apparatus 20. The raw waste liquid 10 a is allowed to flow into the freeze concentration apparatus to perform first-stage concentration, Subsequently, the condensed water 26 is taken out by concentrating the second stage with the vapor recompression concentrator 20.
[0023]
The freeze concentration apparatus 10 includes a circulating water tank 11, an ice making machine 12, a refrigerator 13, and an ice accumulator 14.
The low-concentration aqueous solution containing the raw waste liquid 10a stored in the circulating water tank 11 is circulated through the ice making machine 12 through the built-in watering nozzle 12c and is frozen in the ice making heat exchanger 13a built in the ice making machine 12. The apparatus is supplied with cold brine / warm brine from the machine 13 for freeze concentration, the frozen ice is stored in the ice accumulator 14, and the concentrated water is returned to the circulating water tank 11.
[0024]
The ice making machine 12 has a sprinkling nozzle 12c on the upper bottom, a flat ice making heat exchanger 13a in the bottom, and an ice making chamber 12a having an inclined wire mesh 12d on the lower bottom, and the inclined wire mesh 12d on the upper side. Consists of a temporary storage tank 12f at the bottom,
The ice making heat exchanger 13a is configured such that cold brine is supplied from a separately provided refrigerator 13 during ice making, warm brine is supplied during ice melting, and ice melting water is supplied from the ice accumulator 14.
An ice take-off opening / closing door 12e is provided at the lower part of the ice making chamber 12a, and frozen ice that has fallen on the inclined wire mesh 12d is transferred to the ice accumulator 14 through the opening / closing door 12e when the ice is removed after the icing surface is cleaned. Inflow ice is stored.
The water spray nozzle 12c sprays a low-concentration aqueous solution from the circulating water tank 11 on the heat transfer surface of the ice making heat exchanger 13a during ice making to form a thin plate-like ice. Ice water is sprayed on the freezing surface to clean and drain the frozen surface. The ice take-off door 12e is placed in a closed state so that the washing water does not flow into the ice accumulator 14 during washing.
[0025]
With the above configuration, the raw waste liquid 10 a is cooled by the raw water cooler 11 a that has received the cold supply of the low-temperature high-concentration aqueous solution 20 a from the circulating water tank 11, and is stored in the circulating water tank 11. The stored low-concentration aqueous solution of the raw waste liquid passes through the pump P1 and the valve V3, and is then spread on the flat heat transfer surface of the ice making heat exchanger 13a through the watering nozzle 12c in the ice making chamber 12a. The sprayed raw waste liquid is made into thin plate-like frozen ice on the heat transfer surface by cold brine supplied from the refrigerator 13. The concentrated water is continuously sprayed until a certain ice thickness is reached, and is stored in the temporary storage tank 12f via the lower inclined wire mesh 12d and then flows into the circulating water tank 11.
[0026]
When the thin plate-shaped frozen ice reaches a certain thickness, the circulation of the raw waste liquid is stopped by closing the valve V3 and stopping the operation of the pump P1, and the operation of the refrigerator 13 is switched to the deicing operation to supply cold brine. In addition to terminating the freezing, the valve V4 is opened, the deicing water is introduced from the ice accumulator 14, and sprayed on the icing surface from the watering nozzle 12c to remove the adhered sludge. Brine is supplied and the frozen ice is frozen and separated from the heat transfer surface of the ice making heat exchanger 13a.
The frozen ice that has undergone freeze separation falls from the heat transfer surface and is supplemented by the lower inclined wire mesh 12d. When the supplemented frozen ice reaches a certain amount, the opening / closing door 12e is opened and the ice storage unit 14 is made to flow in and store ice through the opening / closing door.
[0027]
In the ice accumulator 14 for accumulating the frozen ice, a cooler 15 a is provided for supplying the latent heat of the frozen ice to the outside via the de-icing heat exchanger 15. Further, the sensible heat of the ice accumulator 14 is supplied to the outside through the cooler 15b as in the cooler 15a.
Thus, the coolers 15a and 15b can be used not only for air conditioning but also for general processes. In addition, as described above, the deicing water 16 is discharged as a cleaning liquid after externally supplying sensible heat via the cooler 15b, and can be used as industrial water or middle water.
[0028]
The vapor recompressing and concentrating apparatus 20 includes a condenser 21, a vapor compressor 22, a heater 23, a tank for condensate 24, and an adsorber 25.
That is, the low-temperature high-concentration aqueous solution 20a having a higher concentration in the circulating water tank 11 passes through the raw water cooler 11a that cools the raw waste liquid 10a and the condensate cooler 24a that cools the condensate, and then the vapor recompression concentrator. Is sent to the condenser 21. The fed high concentration aqueous solution 20a is heated by the heater 23 inside the condenser 21 and evaporated. The evaporated steam is sent to the steam compressor 22. The steam whose temperature is increased by the steam compressor 22 is sent into the heater 23. The high-concentration aqueous solution 20a evaporates by the heater 23 and condenses inside itself. The relatively high-temperature condensate stored in the tank of the condensate 24 is sent to the condensate cooler 24a by the pump P9, cooled, and then efficiently adsorbs and removes odors and harmful components while passing through the adsorber 25. After that, it is effectively used as industrial water and medium water.
[0029]
This embodiment has the structure and features indicated in the claims, and does not define the device structure such as the ice making structure in the ice making machine and the concentrating structure in the condenser, but is merely an example.
Further, the present invention is effective not only for wastewater treatment of industrial waste liquid but also for solvent separation and concentration of general solutions.
[0030]
【The invention's effect】
The first effect of the present invention is that the freeze concentration device and the vapor recompression concentration device are arranged in series, and the freeze-concentrated waste liquid is further concentrated by the vapor recompression concentration device, thereby concentrating to a much higher concentration than the conventional method. The waste liquid can be sent to the final treatment by combustion. As a result, it is possible to save much energy compared to the conventional method. Compared with the simple heat concentration method, this method comprising the freeze concentration step and the vapor recompression concentration step can reduce the energy required for removing the same amount of water to about 1/4.
[0031]
The second effect of the present invention is the utilization of cold energy. The latent heat and sensible heat of the frozen ice separated by the freeze concentrator can be used as a cooling source for air conditioning and cooling. In the conventional simple combustion method, all of the heat of combustion was wasted into the atmosphere, but in the refrigeration concentration method, the energy input to the refrigeration process is four times the value (the performance coefficient value of the refrigerator is 4 or more). Obtaining cold heat is a very important feature.
[0032]
The third effect of the present invention is a water saving effect. Since the purity of the deicing water obtained in the freezing process is considerably high, it can be sufficiently used as middle water, washing water, and industrial water, and the amount of clean water used can be reduced. Furthermore, the condensed water obtained by the vapor recompression concentrator has high purity and can be reused like the deiced water. The water-saving effect that all the water separated from the wastewater can be used is a significant feature compared to the conventional method. In the case of 4-fold concentration, clean water equivalent to 75% of the volume of the raw waste liquid can be used, and the water saving effect is outstanding.
[0033]
The fourth effect of the present invention is contribution to environmental conservation. Air pollution and carbon dioxide reduction effects due to energy conservation and freshwater conservation effects due to the use of separated water can be expected to make an important contribution to future environmental conservation.
[0034]
The fifth effect of the present invention becomes remarkable in the raw waste liquid generating establishment. Conventionally, business sites that generate raw effluents have transported the raw material solution as it is to an intermediate processing company's business site. In addition, processing costs can be drastically reduced, and excellent corporate activities are possible from the viewpoints of water conservation, energy conservation, and environmental conservation.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of a solvent separation and concentration apparatus for a solution of the present invention.
FIG. 2 is a diagram showing a wastewater treatment method by microbial decomposition.
FIG. 3 is a diagram showing a direct combustion treatment method for waste liquid.
FIG. 4 is a view showing a vacuum concentrated combustion treatment method for waste liquid.
FIG. 5 is a diagram showing a juice concentration step showing an example of a freeze concentration method.
FIG. 6 is a diagram showing a concentration step in a wort boiling pot showing an example of a vapor recompression concentration method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Freezing concentration apparatus 11 Circulating water tank 12 Ice making machine 12a Ice making room 13 Freezing machine 13a Ice making heat exchanger 14 Ice storage 15 Ice-free heat exchanger 16 Ice-free water 20 Steam recompression concentration apparatus 21 Condenser 22 Steam compressor 23 Heater 24 Condensate 25 Adsorber 26 Condensed water

Claims (4)

In the solvent separation and concentration method for solutions such as industrial waste liquid,
Steam recompression, in which the first stage of solvent concentration is performed by freeze concentration in which water is frozen and concentrated from a low-concentration aqueous solution such as industrial waste liquid, and then the water is vaporized and separated from the high-concentration aqueous solution obtained by the freeze-concentration by heating. Concentrate the second stage by concentration, perform final concentration / volume reduction, and freeze ice obtained by freeze concentration is used for cold heat by heat exchange with a load via an ice accumulator. A solvent separation and concentration method for a solution, characterized in that steam heat obtained by concentration is used as a heating source for a high-concentration aqueous solution. 2. The solvent separation and concentration method for a solution according to claim 1, wherein in the freeze concentration, the purity of the deicing water can be improved by washing the ice surface immediately before the freeze separation with deicing water. In the vapor recompression concentration, the condensate is allowed to remove odors and specific components through an adsorbent after the temperature is lowered by heat exchange with the high-concentration aqueous solution obtained by the first-stage concentration. The solvent separation and concentration method for a solution according to claim 1, wherein A circulating water tank that stores a low-concentration aqueous solution and circulates the concentrated liquid until a high-concentration aqueous solution is obtained by concentration in the first stage, an ice-making chamber that is supplied with the low-concentration aqueous solution from the circulating water tank and freeze-concentrate, and is frozen in the ice-making chamber A freezing and concentrating device including a freezer that supplies cold heat and deicing heat, and an ice accumulator that stores ice water of frozen ice separated from frozen ice and supplies cold heat and deicing water to the outside,
A condenser that heats and evaporates the first-stage concentrated high-concentration aqueous solution stored in the circulating water tank, a vapor compressor that compresses the vapor evaporated from the condenser, a condenser that condenses the compressed vapor and a condenser A solvent concentrating device for a solution, comprising: a vapor recompressing and concentrating device including a heater for heating the above and an adsorber for adsorbing an odor or a specific component from the condensate.

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