JPS61114706A - Method and apparatus for removing foam generated during freeze concentration - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for freezing and concentrating fruit and vegetable juices, particularly to a method for freezing and concentrating fruit and vegetable juices. In particular, the present invention relates to an apparatus and method for eliminating foam formed within freeze concentrators and improving product handling.

BACKGROUND OF THE INVENTION Separating degraded or suspended salts from liquid substances by purifying drinking water from seawater or salt water, or by concentrating fruit juices such as orange and grape juice, vegetable juices such as tomato juice, and coffee. Various freezing methods have been developed. For example, U.S. Pat. No. 3,51,924, U.S. Pat.
No. 664°145 and No. 4,091,635 may be mentioned.

When a shell-and-tube rigid heat exchanger cooler is used to produce a frozen concentrate, or a concentrate to be concentrated, the concentrate to be concentrated is generally precooled and then fed to the top of the cooling tube. be done. While flowing vertically through the vertical cooling pipe, the raw liquid exchanges heat with the refrigerant circulating in the body side of the heat exchange cooler, and is further cooled. As the refrigerant, a refrigerant such as ammonia or Freon (registered trademark) is generally used. Ice crystals are formed as the lagoon of the stock solution decreases. The mixture of cooled stock solution and ice flows from the condenser tube into an ice tank where the ice is separated as a slurry suspended above the concentrated stock solution. Then, the ice is recycled to the heat exchange cooler, while the ice slurry is kneaded and washed to recover the concentrate contained in the ice, as in Fruit H.

When producing drinking water, ice must of course be melted after being washed. Concentrated stock solutions, such as fruit juice, in the ice storage tank can be aspirated and bottled.

When attempting to freeze concentrate fruit and vegetable juices, it is generally desirable to first press the fresh fruits and vegetables. The vegetables obtained by pressing certain fruits and vegetables can then preferably be filtered to separate out insoluble components such as pulp, thus obtaining so-called serums. After freezing and concentrating this serum, it is remixed with the fruit pulp to complete the production of concentrated fruit juice.

It is known that during freeze concentration of fruit juice and its serum, a large amount of foam is generated, especially in the ice storage tank, and remains on top of the ice slurry. This foam interferes with the device's ability to deliver the ice slurry, which is the frozen forming component of the ice crystals, and to separate the ice crystals from the concentrated fruit juice. Due to the constant supply of ice slurry into the ice tank, the expansive nature of the foam, and the overall swirling motion, the foam continually rises and expands. If this foam is removed from within the freezing device, a significant portion of the aromatic components of the fruit juice will be lost. As a result, the quality of the fruit juice deteriorates.

From the above discussion, it is clear that freeze-concentration would be greatly improved if devices and methods were developed that could reduce or eliminate the foam formed in freeze-concentrate fruit juices.

According to one embodiment of the invention, ice crystals containing a foam-prone concentrate are provided in an ice storage tank, the ice crystals are separated as a slurry layer floating above the concentrate, and the ice crystals are separated as a slurry layer floating on top of the slurry layer. A method can be provided that includes the step of heating the bubbles to extinguish them.

Heating the foam causes it to collapse and form water droplets that fall into the ice slurry. Since the bubbles tend to rise and are close to the heating means, it is easy to heat the bubbles and cancel them.

This method is adopted as part of the freeze-concentration process, in which the stock solution is continuously fed into a heat exchange cooler, which is cooled to form ice crystals containing the stock solution, and the ice crystals are transferred to an ice storage tank. can be supplied to The raw liquid below the ice slurry in the ice storage tank is continuously recycled to the freezing heat exchange cold member. The ice slurry is continuously discharged from the ice storage tank to keep the amount in the ice storage tank approximately constant.

Heating of the foam can be accomplished by providing one or more electrical resistance wires positioned in a grid or spiral above the foam. Alternatively, the foam can be heated by circulating a warm liquid through a tubular grid or spiral located above the foam.

Furthermore, it is also suitable to provide a heating lamp above the bubble.

The ice storage tank can be provided with a lid to form a closed system. The lid may be provided with means for heating the top of the foam.

According to a second embodiment of the invention, there is provided an ice storage tank for ice crystals containing a foam-prone concentrate, in which the ice crystals separate as a slurry layer suspended above the concentrate; A device is obtained comprising said ice storage tank on which foam is generated and heating means for counteracting the foam by heating.

The heating means may be, for example, one or more electrical resistance wires arranged in a grid or spiral pattern above the bubbles, or electrical resistance wires arranged in a grid or spiral pattern above the bubbles to prevent the hot liquid from circulating. It can be configured as one or more tubes or one or more heat lamps attached to heat and irradiate the foam.

It is desirable to have a lid on the ice storage tank to provide a closed system. If desired, the heating means can be supported by the lid by being pushed into the lid or adjacent to the lid and lowered to the underside of the lid.

The apparatus and invention according to the present invention are effective for freezing and concentrating various stock solutions, but in particular, for example, orange juice, grapefruit juice, tomato juice, apple juice, etc.
It is effective in freeze concentrating fruit and vegetable juices such as grape juice and lemon juice or their serums.

The attached drawings will be explained in detail below. Elements that are the same or similar to those illustrated in the accompanying drawings have been designated by the same reference numerals unless otherwise indicated.

Referring to FIG. 1, a multi-tubular falling film heat exchange cooler 20
is generally of the same type as disclosed in Engdahl et al., US Pat. No. 4,286,436. The heat exchange cooler 20 includes a metal vertical cylindrical body 22 and a plurality of metal cooling tubes 24 .

The cooling tubes 24 are held in place by a metal upper tube sheet 26 and a metal lower tube sheet 28.

A conduit 30 communicates with the interior lower space of the fuselage 22 and supplies refrigerant to the interior of the fuselage. This refrigerant is discharged from the inner upper space of the fuselage 22 by a conduit 32.

The refrigerant can be a refrigerant gas such as ammonia, or a Freon gas such as dichlorotetrafluoroethane, or a refrigerant such as an aqueous solution of ethylene glycol or ethanol. Whichever refrigerant is used, the refrigerant must be capable of lowering the temperature of the concentrate flowing downward in the cooling tube to a temperature low enough to form ice crystals.

The upper portion of the heat exchange cooler body 22 extends above the upper tubesheet 26 to form a header 34 . The top of header 34 supports a removable lid 36. The upper outlet end of the conduit 38 communicates with the inside of the header 34 to supply the stock liquid to the top of the cooling pipe of the heat exchange cooler, and acts to cause the stock liquid to flow downwardly along the inner surface of the cooling pipe as a falling film. .

While the falling film of the raw solution flows downward along the inner surface of the cooling tube, it is cooled by exchanging heat with the refrigerant on the body side of the heat exchange cooler. Therefore, as the stock solution cools,
Due to the formation of ice crystals, when the stock solution flows out from the lower end of the cooling tube into the ice storage tank 40, a significant amount of ice is mixed in the stock solution.

The ice storage [40] includes a circular bottom 42 and a vertical cylindrical sidewall 44 connected to the circular bottom 42. It is desirable that the ice storage tank 4o be positioned at the center of the lower side of the heat exchange cooler 2o. A conduit 38 communicates with the lower interior space of the ice tank 40 and serves to recirculate the raw liquid from the bottom of the ice tank to the interior of the header 34 to produce more concentrated water into ice crystals.

A supply conduit 46 communicates with the lower inner space of the ice storage tank 40,
It acts to introduce the raw liquid into the heat exchange cooler. The stock solution to be introduced is cooled in the ice storage tank 40 to near freezing temperature A], and then,
Via conduit 38, the heat exchange cooler is fed. Therefore, the temperature of the stock solution can be rapidly lowered in the heat exchange cooler to generate the desired ice crystals.

The mixture of ice and raw liquid flowing out of the cooling tube 24 of the heat exchanger cooler into the ice storage tank 40 rapidly separates into a lower layer 52 of aqueous solution.
and an ice slurry upper portion 50 floating on top of that layer 52. Further, if the stock solution is a liquid that generates bubbles when stirred, or a liquid that releases gas during the process, a layer of bubbles 54 will be formed on the surface of the ice slurry upper layer 5o. The ice slurry top layer 50 is discharged from the ice storage tank 40 via conduit 56 and is typically fed to a cleaning device for cleaning using water. Wash water can be collected and reused as appropriate.

The undiluted foam 54 that accumulates in the ice storage tank 40 reduces the efficiency of the heat exchange cooler and interferes with its normal performance, as described above. To this end, a bracket 62 is used to attach one or more electric heat lamps 60 to the top of the ice tank 40.

The heat generated by the electric heat lamp 6o installed above the bubbles is irradiated onto the bubbles 1, causing the bubbles to burst and disappear.

Normally, the open type ice storage tank 40 is used only when the oxidation of the components of the stock solution and/or the volatilization of volatile components present in the stock solution are tolerable to a certain extent. However, many stock solutions used in heat exchange coolers are susceptible to oxidation and any appreciable volatilization or modification will result in the loss of their desirable aromatic properties; It is desirable to do this as a closed system.

One closed system is illustrated in FIGS. 2 and 3 as Hc. A circular 'M70 is removably coupled along the top edge of the ice tank 40 to a flange 74 with bolts 72. The circular lid 70 of the ice storage tank has a circular hole formed in the center thereof large enough to accommodate the extension of the lower end of the body 22 of the heat exchange cooler. A ring 78 attached to the body 22 is fixed to the circular lid 70 with bolts 80. With the arrangement described above, the ice storage tank 4o and the heat exchange cooler 2
0 is integrated to form a closed system, which can prevent volatile components and other components in the processing stock solution from volatilizing. However, when processing undiluted solutions that produce foam,
It is necessary to eliminate bubbles in the ice storage tank 40.

To counteract the bubbles 54 in the closed ice storage tower shown in FIGS. 2 and 3, the circular lid 70 is provided with heating means 90.

The heating means 90 is shown diagrammatically in the above figures as a spiral, while in FIG. 4 it is shown as an electrical resistance heating wire 90 embedded within a circular M2O. In FIG. 4, circle 170 is shown as a composite layer having an insulating surface layer 94 supported on a waterproof layer 96 of wood or chipboard.

The heating element 902 can also be embedded within the waterproof layer 96.

A through hole 98 can be provided in the waterproof layer 96 to promote heat transfer with the space under the circular lid. The heat generated by the electric resistance wire 902 bursts the upper surface of the bubbles 54 which are raised in a layered manner, and the amount of bubbles generated within the heat exchange cooler can be controlled.

FIG. 5 shows another embodiment of heating means in a closed system. In the lid 7 shown in FIG. 5, a spiral tube 904 is embedded in a waterproof layer 96 instead of an electrical resistance wire. The heated liquid within the cryotube 904 is circulated to obtain the heat necessary to counteract the bubbles 54. For this purpose, dry water or an aqueous ethylene glycol solution can be used.

Of course, the number of electrical resistance wires 902 or spiral tubes 904 is not limited to a single number, and it is also possible to use a plurality of them, or any combination thereof.

Only a small amount of heat is required to counteract the bubbles 54.

In addition, the temperature of the lid is set to the value necessary to achieve the minimum level of irradiation. This heat increases the heat load on the entire freeze-concentrator, but the disadvantage is that during the freeze-concentrator process, bubbles are removed and
considered to be less important than the possibility of improving the handling of the processing stock solution and associated ice by reducing the
available. Since the heating method of the present invention is simple in operation and control, a minimum amount of heating heat is required.

The above description has been made only to provide a clear understanding of the invention, and is not intended to limit the content of the invention, as modifications will be obvious to those skilled in the art.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view showing a heat exchange cooler according to the present invention, Fig. 2 is a front view of an ice storage tank with a lid provided with a heating means in the lid, a partial vertical cross-section, and a cutaway view thereof. FIG. 2 is a bottom view of the ice storage lid taken along line 3-3, FIG. 4 is a vertical sectional view of the ice storage tank containing electrical resistance heating means, and FIG. 5 is a view of the heating liquid circulating. FIG. 3 is a longitudinal cross-sectional view of an ice storage lid that accommodates a tubular member that can be used. Figure 2 Figure 8 Figure 411! ! 5th v! In

Claims (13)

[Claims] (1) A method of supplying ice crystals containing a foam-prone stock solution into an ice storage tank and extinguishing bubbles generated during the freeze-concentration process in which the ice crystals are separated as a slurry layer floating on top of the stock solution by heating. (2) The method according to claim 1, characterized in that the upper part of the foam is heated. (3) Claim 1, characterized in that the ice storage tank is provided with a lid, and the lid is provided with heating means for heating the upper part of the foam.
The method described in section. (4) The method according to claim 1, wherein the heating means constitutes a pipe through which hot water circulates. (5) A method according to claim 1, characterized in that the heating means constitutes an electrical resistance heating means. (6) A method according to claim 1, characterized in that the heating means constitutes a heating lamp. (7) The method according to claim 1, wherein the stock solution is fruit juice, vegetable juice, or a serum thereof. (8) Continuously supplying the stock solution to a heat exchange cooler and cooling it to form ice crystals containing the stock solution and supplying the same to an ice storage tank; continuously recirculating the raw liquid below the slurry to a heat exchange cooler; and continuously draining the ice slurry from said ice storage tank to maintain a generally constant volume of its contents. A method according to claim 1. (9) An ice storage tank for ice crystals containing a stock solution that is prone to foaming, the ice storage tank separating the ice crystals as a slurry layer floating on top of the stock solution, and heating the foam that forms on top of the slurry. and a heating means for counteracting with. (10) The apparatus according to claim 8, wherein the ice storage tank is provided with a lid, and the lid is provided with heating means for heating the upper part of the foam. (11) The device according to claim 9, wherein the heating means constitutes a pipe through which hot water can be circulated. (12) The device as set forth in claim 9, wherein the heating means constitutes electrical resistance means. (13) The apparatus according to claim 9, wherein the heating means constitutes a heating lamp.