JP6417826B2 - Concentration system and concentration method - Google Patents

Description

  The present invention relates to a concentration system and a concentration method for concentrating a solution containing a component that is altered or denatured by heating at a high temperature, such as a food-related solution such as fruit juice, liquid sugar, and honey.

  In the production of foods and beverages, for example, a concentration step of a solution (suspension) containing sugar or other specific components such as fruit juice, liquid sugar, and honey may be required. This concentration process is performed as a pretreatment for drying and pulverizing the components, or for the purpose of reducing the transportation cost of the suspension and reducing the storage space, etc. The processing is extremely important.

  Concentration using a reverse osmosis membrane device (for example, Patent Document 1), multi-effect can distillation, freeze concentration, etc. is used as a technique for concentrating a biological solution containing a specific component in the food process as described above. The concentration that was known is known. It is also known to concentrate using a vacuum evaporator (for example, Patent Document 2 and Patent Document 3).

JP2013-63076A Japanese National Patent Publication No. 8-506733 JP 2009-62301 A

  Concentration using a reverse osmosis membrane device is a spiral module in which a reverse osmosis membrane, such as a flat cellulose acetate membrane or a synthetic polymer membrane, is wound in a laver winding shape to ensure a large filtration membrane area per unit volume. It is common to use. In this spiral module, an extremely thin spacer is sandwiched between the membrane surfaces wound in a laver form. In the reverse osmosis membrane apparatus as described above, the liquid to be treated flows through the gap between the extremely thin spacers, the filtrate permeates to the back side of the membrane, and the solution components are concentrated on the membrane surface. When the component of the liquid to be treated is concentrated on the membrane surface, the osmotic pressure increases. Therefore, it is necessary to use a high-pressure pump that can apply a filtration pressure exceeding the osmotic pressure. Moreover, in order to suppress as much as possible that a solution component concentrates on a film surface and prevents filtration, it is necessary to make the film surface flow rate of a to-be-processed liquid high. That is, an expensive liquid pump with high output and high energy cost are required. Furthermore, solutions such as fruit juice, sugar solution, and honey have a high viscosity due to concentration of components, and it is not easy to pass a very thin liquid to be processed to the reverse osmosis membrane module. For this reason, there is a limit to the concentration rate, and there is a problem that only about 40 to 50% can be concentrated.

  Further, in the concentration using multi-effect can distillation, several stages of distillation cans are arranged and heated and distilled. Distillation is repeated while the amount of heat necessary for distillation is given in the first stage and the amount of heat given in the first stage is recovered without additional heating in the latter stage, so that it is possible to distill economically. However, since the amount of heat required for the last-stage distillation is also heated in the first stage, it is necessary to heat at a very high temperature with superheated steam exceeding 100 ° C. in the first stage. On the other hand, organic components derived from living organisms that are concentrated in a food process include those that are easily altered by heating. In addition, it contains a lot of volatile components that easily lose evaporation due to high-temperature heating. Therefore, some fruit juices, sugar solutions, and honey have a problem that high-temperature concentration by multi-effect can distillation may not be suitable.

  Further, in the freeze concentration, for example, the liquid to be treated is frozen at a temperature of about −15 ° C., and the generated sherbet-like (slurry) frozen material is maintained at a temperature of about −5 ° C. to grow ice crystals. Thereafter, only ice crystals are separated by centrifugal separation or squeezing filtration, and the separated liquid is further concentrated by repeating the steps of freeze-recrystallization and separation. This concentration technology can be applied to pre-concentration of freeze-dried instant coffee and high-quality fruit juice concentration, but there are problems such as low concentration efficiency, difficulty in mass concentration, and low concentration limit concentration of around 40%. There is.

  By the way, the vacuum evaporator has good concentration efficiency, but because the equipment used in the production line is made of metal, it is highly applicable to so-called corrosive liquids containing acids and salts such as fruit juice, liquid sugar, and honey. I can not say. Further, if the heating area and the evaporation area are increased, the evaporation efficiency can be secured, but there are problems that the equipment scale is large and expensive due to heavy equipment.

  Thus, conventionally, the target component concentration is low, and it is easy to concentrate to a high concentration even if the liquid viscosity increases due to concentration, while reducing heat deterioration and loss of volatile components as much as possible for a relatively large amount of liquid to be treated. There was no such system.

  The present invention has been made in view of the above problems, and concentrates without altering or denaturing a solution that is altered or denatured by heating at a high temperature, such as food-related solutions such as fruit juice, liquid sugar, and honey. The purpose is to provide a system. Another object of the present invention is to provide a concentration method using such a concentration system.

  In order to solve the above-mentioned problems, firstly, the present invention obtains a secondary concentrated liquid by further concentrating the primary concentrated liquid concentrated by the reverse osmotic membrane, and a reverse osmotic membrane apparatus that primarily concentrates the liquid to be treated. A concentrating system comprising a membrane distillation apparatus, the membrane distillation apparatus comprising a raw water part and a condensing part across a hydrophobic porous membrane, maintaining the condensing part in a reduced pressure state, and in the condensing part The primary concentrated liquid is provided with a cooling means, and the heated primary concentrated liquid is introduced into the raw water portion of the membrane distillation apparatus, and the primary concentrated liquid is concentrated by passing the vapor of the primary concentrated liquid through the hydrophobic porous membrane. And providing a secondary concentrated liquid (Invention 1). Here, food-related solutions such as fruit juice, liquid sugar, and honey are suitable as the liquid to be treated (Invention 2).

  According to the inventions (Inventions 1 and 2), the liquid to be treated having a low initial concentration of a target component of about several percent is first concentrated to about 40 to 50% (corresponding to a volume reduction, the same applies hereinafter) with a reverse osmosis membrane. The primary concentrated liquid having increased viscosity can be further subjected to membrane distillation to be concentrated to a high concentration (target concentration) of about 70 to 80%. In addition, concentration by reverse osmosis membrane does not require heating, and membrane distillation does not require heating to 100 ° C. or higher, preferably 90 ° C. or higher. Therefore, the purpose of sugar content in food-related solutions such as fruit juice, liquid sugar, and honey The concentrated component to be concentrated can be concentrated with greatly reduced heat deterioration and loss of volatile components. Furthermore, even a large amount of non-treatment liquid can be processed efficiently, the system configuration is simple, and operation management is easy.

  In the said invention (invention 1 and 2), it is preferable to provide the heating means which heats the said primary concentrated liquid introduce | transduced into the said raw | natural water part of the said membrane distillation apparatus using waste heat (invention 3).

  According to this invention (invention 3), it is possible to effectively use heat energy by utilizing waste heat as a heat source of the heating means, and further energy saving and cost saving can be achieved. It is also effective for industrial revitalization.

  Second, the present invention includes a primary concentration step of concentrating a liquid to be treated by a reverse osmosis membrane device, and a secondary concentration step of further concentrating the primary concentrate obtained in the primary concentration step by a membrane distillation device. The membrane distillation apparatus includes a raw water part and a condensing part across a hydrophobic porous membrane, maintains the condensing part in a reduced pressure state, and includes a cooling means in the condensing part And the secondary concentration step introduces the heated primary concentrate into the raw water part of the membrane distillation apparatus, and allows the vapor of the primary concentrate to permeate the hydrophobic porous membrane. A concentration method is characterized in that a concentrated solution is concentrated to produce a secondary concentrated solution (Invention 4).

  According to this invention (Invention 4), the liquid to be treated having a low initial concentration of the target component of about several percent is first concentrated to about 40 to 50% (equivalent to volume concentration, the same applies hereinafter) with a reverse osmosis membrane, The liquid having increased viscosity can be further subjected to membrane distillation to be concentrated to a high concentration (target concentration) of about 70 to 80%. As a result, the target component can be concentrated with greatly reduced alteration due to heat and loss of volatile components. Furthermore, even a large amount of non-treatment liquid can be processed efficiently.

  In the concentration system of the present invention, the liquid to be treated is first concentrated with a reverse osmosis membrane, and the primary concentrated solution with increased viscosity is further concentrated by membrane distillation. Even a large amount of non-processed liquid can be efficiently concentrated to a high concentration (target concentration) even if the liquid to be processed is low. Moreover, the concentration by the reverse osmosis membrane does not require heating, the membrane distillation does not require heating to 100 ° C. or higher, preferably 90 ° C. or higher, and the liquid to be treated can be concentrated without being exposed to a high temperature. It is possible to drastically reduce the deterioration of components intended for food-related solutions such as liquid sugar and honey, and loss of volatile components.

It is the schematic which shows the concentration system which concerns on one Embodiment of this invention. It is the schematic which shows an example of a membrane distillation apparatus. 2 is a schematic view showing a concentration system of Comparative Example 1. FIG. 6 is a schematic diagram showing a concentration system of Comparative Example 2. FIG. It is the schematic which shows the concentration system of the comparative example 3.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Hereinafter, the present invention will be described in detail.
FIG. 1 is a schematic view showing a concentration system according to the present embodiment. In FIG. 1, the concentration system 1 of the liquid W to be treated has a reverse osmosis membrane device 3 as a primary concentration means and a membrane distillation device 4 as a secondary concentration means in the middle of a raw water line 2, and a reverse osmosis membrane device. A heat exchanger 5 serving as a heating means is disposed between 3 and the membrane distillation apparatus 4.

  In the concentration system 1, the liquid W to be treated is primarily concentrated by the reverse osmosis membrane device 3 to be separated into the primary concentrated solution W1 and the membrane permeate W2, and is secondarily concentrated by the membrane distillation device 4 to be a final product. It isolate | separates into the secondary concentrated liquid W3 and the distilled water W4.

  FIG. 2 shows an example of the membrane distillation apparatus 4. This membrane distillation apparatus 4 is a membrane in which a primary concentrated liquid W1 heated by a heat exchanger 5 using low-temperature waste heat is passed through a hydrophobic porous membrane and its vapor is distilled or concentrated under reduced pressure and low temperature conditions. Use distillation techniques.

  The membrane distillation apparatus 4 is provided with a hydrophobic porous membrane 11, and a raw water chamber 12 and a condensing chamber 13 are provided with the hydrophobic porous membrane 11 interposed therebetween. The raw water chamber 12 is an example of a raw water portion into which the primary concentrated liquid W1 is introduced, and the condensing chamber 13 is an example of a condensing portion that condenses the vapor S that has passed through the hydrophobic porous membrane 11.

  The hydrophobic porous membrane 11 is an example of means for selectively allowing only the vapor of the primary concentrated solution W1 introduced into the raw water chamber 12 to pass through. As the hydrophobic porous membrane 11, a fluororesin porous membrane can be suitably used because of its excellent heat resistance. In this hydrophobic porous membrane 11, only the vapor S of the primary concentrated solution W1 is permeated, it is hardly affected by the osmotic pressure and viscosity of the primary concentrated solution W1 with respect to the membrane permeated vapor amount, has high vapor permeability, and is primarily concentrated. Concentration of the suspended component of the liquid W1 can be performed efficiently.

  A decompression device 14 is connected to the condensation chamber 13, and a cooling unit 15 is provided on the wall surface of the condensation chamber 13. The raw water chamber 12 is decompressed by the decompression device 14 together with the condensing chamber 13 and is maintained in a decompressed state, and the cooling unit 15 is cooled by a cooling means (not shown) to a temperature to condense the vapor S in contact therewith.

  As said to-be-processed liquid W, the food related solution containing sugars, such as fruit juice, liquid sugar, and honey, is suitable. Here, in the liquid W to be treated, the initial concentration of the target concentrated component such as sugar is 10% or less, particularly about 2 to 7%.

  Next, the operation of the concentration system 1 provided with the membrane distillation apparatus 4 as described above will be described.

  First, the liquid W to be treated is primarily concentrated by the reverse osmosis membrane device 3. Here, the liquid W to be treated is concentrated to about 40 to 50% by separating and discharging the membrane permeated water W2, and a primary concentrated liquid W1 having an increased viscosity or the like is obtained. Particularly in food processes, the water temperature may be high, so it is preferable to adjust the temperature to the allowable temperature of the reverse osmosis membrane module in a storage tank or heat exchanger in advance. As the reverse osmosis membrane device 3, modules such as a spiral type, a hollow tube type (tubular type), and a hollow fiber type can be applied. Moreover, as a film | membrane which comprises the reverse osmosis membrane apparatus 3, a cellulose acetate film | membrane and a synthetic polymer film, for example, aromatic polyamide, polysulfone, polyvinyl alcohol, etc. are applicable.

  Then, the primary concentrated liquid W1 is sent to the heat exchanger 5. Here, the primary concentrated solution W1 is heat-exchanged to a predetermined temperature by the heat exchanger 5. The heat exchanger 5 exchanges heat with the primary concentrated liquid W1 by heat of a heat medium heated by a waste heat source such as factory waste heat. Thus, the temperature of the primary concentrated liquid W1 is adjusted to be, for example, less than 100 ° C., preferably about 40 to 90 ° C., particularly about 50 ° C. to 80 ° C., and supplied to the membrane distillation apparatus 4 at the subsequent stage. In this way, waste heat such as factory waste heat can be used to heat the liquid W to be treated to a temperature suitable for concentration in the membrane distillation apparatus 4, and various waste heat can be effectively used.

  Then, the primary concentrated liquid W1 whose temperature is adjusted and whose viscosity has been increased by the primary concentration is sent to the membrane distillation apparatus 4 and subjected to secondary concentration to separate the distilled water W4 to obtain the secondary concentrated liquid W3.

  Here, the membrane distillation apparatus 4 performs secondary concentration as follows. That is, by maintaining the condensation chamber 13 under reduced pressure, the vapor S that has passed through the holes of the hydrophobic porous membrane 11 is drawn.

  In this case, since the condensing chamber 13 is maintained in a reduced pressure state, not only the function of drawing in the steam S but also the function of lowering the boiling point of the primary concentrated liquid W1. Thereby, the vapor | steam S produced from the primary concentrated liquid W1 becomes remarkable, and the vapor | steam amount which permeate | transmits the hydrophobic porous membrane 11 increases. As a result, the secondary concentrated liquid W3 is obtained in the raw water chamber 12. That is, since much steam S is condensed from the primary concentrate W1 and converted into the secondary concentrate W3, the primary concentrate W1 of the raw water chamber 12 is efficiently concentrated. Therefore, a lot of secondary concentrated liquid W3 is generated from the raw water chamber 12 and recovered from the concentrated liquid recovery line 16.

  On the other hand, the vapor S touches the cooling unit 15 of the condensation chamber 13 and condenses, and water droplets L are generated. As a result, the steam S is condensed in the cooling unit 15, and the distilled water W <b> 4 is discharged from the condensed water discharge line 17.

  In such membrane distillation, the primary concentrated solution W1 is concentrated to obtain the secondary concentrated solution W3, and the flow path width and membrane surface line flow rate of the primary concentrated solution W1 are important. The channel width is a size such as a channel diameter effective for allowing the primary concentrated solution W1 to pass through. On the other hand, the membrane surface line flow velocity is a linear velocity given by a value obtained by dividing the flow rate of the primary concentrate W1 by the effective cross-sectional area in the apparatus, and is apparently the velocity of the primary concentrate W1. Specifically, the average flow velocity of the primary concentrated liquid W1 parallel to the membrane surface of the hydrophobic porous membrane 11 is shown.

  And in this membrane distillation apparatus 4, the flow path width w of the primary concentrate W1 should just be 1 [mm] or more and 30 [mm] or less, for example, More preferably, it is 3 [mm] or more and 20 [mm]. The following. The membrane surface flow velocity V of the primary concentrated liquid W1 is, for example, not less than 0.01 [m / s] and not more than 5 [m / s], more preferably not less than 0.05 [m / s] and not more than 2 [m]. / S].

  In this membrane distillation apparatus 4, the liquid W to be treated is concentrated to a high concentration (target concentration) of about 70 to 80%. Therefore, the membrane distillation apparatus 4 can be concentrated in multiple stages, for example, 2 to 12 stages, preferably 3 to 10 stages, as necessary, until it reaches the desired concentration, and the energy recovery rate can be increased.

  The secondary concentrated solution W3 thus obtained does not require heating in the primary concentration by the reverse osmosis membrane device 3, and is not heated to 100 ° C. or higher, preferably 90 ° C. or higher in the membrane distillation device 4, and the liquid to be treated Since W can be concentrated without being exposed to a high temperature, it is possible to greatly reduce alteration of the target component due to heat and loss of volatile components. Furthermore, even if the liquid W to be processed is large, it can be processed efficiently, the system configuration is simple, and the operation management is easy.

  The membrane permeated water W2 and the distilled water W4 are used as service water, for example, reverse osmosis membranes and modules, washing water for the membrane distillation unit, or dilution water as required, so as to effectively use resources. be able to.

  As mentioned above, although embodiment of this invention has been described, this invention is not restricted to the said embodiment, A various deformation | transformation implementation is possible. For example, as a configuration of the concentration system, the reverse osmosis membrane device 3 and the membrane distillation device 4 may each have a plurality of stages. In this concentration system, the liquid W to be treated is not limited to food process water, but can be applied to concentrate process water in medicine and other industrial fields.

  The following specific examples further illustrate the present invention.

<Example 1>
Using the concentrating system having the configuration shown in FIG. 1, an aqueous sugar solution (liquid W to be treated) having a Brix value (sugar content) of 7% is primarily concentrated by the reverse osmosis membrane device 3 to a Brix value of about 40 to 50%. The primary concentrated liquid W1 was heated at 5 and concentrated at 80 ° C. and 80 kPa in the membrane distillation apparatus 4 to obtain a secondary concentrated liquid W3 having a Brix value of 74%.

<Example 2>
Using the concentration system having the configuration shown in FIG. 1, an aqueous honey solution (treatment liquid W) having a Brix value of 8% is primarily concentrated by the reverse osmosis membrane device 3 to a Brix value of about 40 to 50%. The primary concentrated liquid W1 was heated and concentrated at 52 ° C. and 80 kPa in the membrane distillation apparatus 4 to obtain a secondary concentrated liquid W3 having a Brix value of 62%. The secondary concentrated liquid W3 was not burnt and no browning was observed.

<Comparative Example 1>
As shown in FIG. 3, a sugar aqueous solution (treatment liquid W) having a Brix value of 7% was concentrated using a concentration system 20 having a configuration in which reverse osmosis membrane devices 21, 22, and 23 are continuously arranged in three stages. In the reverse osmosis membrane device 22 in the stage, the viscosity of the concentrated liquid became too high, and the concentrated liquid W5 could not be obtained. In FIG. 3, the same components as those in FIG. 1 are denoted by the same reference numerals.

<Comparative example 2>
As shown in FIG. 4, using a concentration system 30 having a configuration in which multiple effect cans 31, 32, 33 are continuously arranged in three stages, a honey dilution liquid (processed liquid W) having a Brix value of 39% is concentrated to a concentrated liquid. Although W6 was produced, since the surface temperature of the heating steam pipe of the first stage multi-effect can 31 was high, the aqueous sugar solution in the vicinity of the heating steam pipe was burnt, browning coloration occurred, and quality deterioration occurred. In FIG. 4, the same components as those in FIG. 1 are denoted by the same reference numerals.

<Comparative Example 3>
As shown in FIG. 5, the concentration system 40 is configured without using the reverse osmosis membrane device 3 in FIG. The device 4 tried to concentrate at 80 ° C. and 80 kPa to concentrate to a Brix value of 35%. However, the amount of distillation per unit time decreased as the liquid viscosity increased, and this would not be possible unless the device was unrealistically large. I was able to assume that there was.

  According to the concentration system and concentration method of the present invention, a solution that is altered or denatured by heating at a high temperature, such as a food-related solution such as fruit juice, liquid sugar, and honey, can be concentrated without being denatured or denatured. It can be widely used as a technology for concentrating food process solutions.

DESCRIPTION OF SYMBOLS 1 ... Concentration system 2 ... Raw water line 3 ... Reverse osmosis membrane apparatus (primary concentration means)
4 ... Membrane distillation device (secondary concentration means)
5 ... Heat exchanger (heating means)
DESCRIPTION OF SYMBOLS 11 ... Hydrophobic porous membrane 12 ... Raw water chamber 13 ... Condensing chamber 14 ... Depressurization device 15 ... Cooling part 16 ... Concentrated liquid recovery line W ... To-be-processed liquid W1 ... Primary concentrated liquid W2 ... Membrane permeated water W3 ... Secondary concentrated liquid W4 ... Distilled water S ... Steam

Claims (3)

A reverse osmosis membrane device that primarily concentrates a liquid to be treated, which is a food-related solution of fruit juice, liquid sugar, or honey ;
A membrane distillation apparatus that further concentrates the primary concentrate concentrated by the reverse osmosis membrane to obtain a secondary concentrate,
The membrane distillation apparatus comprises a raw water part and a condensing part across a hydrophobic porous membrane,
Maintaining the condensing part in a decompressed state, and providing the condensing part with cooling means;
The heated primary concentrated liquid is introduced into the raw water section of the membrane distillation apparatus, and the primary concentrated liquid is concentrated by allowing the vapor of the primary concentrated liquid to permeate the hydrophobic porous membrane. A concentrating system characterized in that The concentration system according to claim 1, further comprising heating means for heating the primary concentrated liquid introduced into the raw water portion of the membrane distillation apparatus using waste heat. A primary concentration step of concentrating a liquid to be treated which is a food-related solution of fruit juice, liquid sugar or honey with a reverse osmosis membrane device;
A secondary concentration step of further concentrating the primary concentrate obtained in the primary concentration step with a membrane distillation apparatus,
The membrane distillation apparatus comprises a raw water part and a condensing part across a hydrophobic porous membrane, maintains the condensing part in a reduced pressure state, and comprises a cooling means in the condensing part,
In the secondary concentration step, the heated primary concentrate is introduced into the raw water part of the membrane distillation apparatus, and the primary concentrated solution is allowed to pass through the hydrophobic porous membrane by passing the vapor of the primary concentrate through the hydrophobic porous membrane. A concentration method comprising producing a secondary concentrate by concentration.

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