JPH03172161A - Continuous heater for food material having fluidity - Google Patents

Abstract

PURPOSE:To uniformly heat a food material conveyed in a pipe line by arranging hollow cylindrical electrode units and a spacer pipe unit therebetween in a series form in a space between an insulating pipe on the upstream side and an insulating pipe unit on the downstream side for forming part of the pipe line. CONSTITUTION:At least the inner peripheral surfaces of an insulating pipe unit 3 on the upstream side and an insulating pipe unit 4 on the downstream side forming part of a pipe line 2 for conveying a food material 1 having fluidity are electrical insulating surfaces. The first hollow cylindrical electrode unit 5, a hollow cylindrical spacer pipe unit 6 and the second hollow cylindrical electrode unit 7 are arranged between the insulating pipe units 3 and 4 in the aforementioned order so as to be mutually adjacent. The inside diameters of the pipe units 3, 4 and 6 and the electrode units 5 and 7 are the same so as to prevent stepped parts from occurring in the inner peripheral surface parts thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to food materials that have enough fluidity to be conveyed in pipes, such as liquid food materials, solid-liquid mixed food materials, or gel food materials. , relates to a device that continuously heats while being transported in a pipe for processing such as cooking or sterilization.

Conventional Technology One method of heating fluid food materials for processing such as cooking or sterilization is to apply pressure to the fluid food materials using a pump or the like and transport them through a pipe.
There is a method of continuously heating the pipe. In this method of continuous heating while conveying the food material inside the pipe, the food material heated inside the pipe can be continuously filled into the container as it is, making the process from heating to filling completely continuous. Can be done.

Conventionally, as a specific method for heating the food material conveyed inside the vibrator, a method has been applied in which the outside of the pipe is heated using hot water, steam, electric heat, etc.
These methods have problems in that they require a long time for treatment and sterilization, resulting in low treatment efficiency and low energy efficiency.

On the other hand, recently, a method of applying so-called Joule heating, in which electricity is directly applied to food materials and heat is generated due to the electrical resistance of the food materials, has been used. According to such Joule heating, the food material is directly heated by electricity, so it has the advantage of high energy efficiency and high processing efficiency.

Conventionally, an example of applying Joule heating to continuous heating of fluid food materials is published in the American periodical rFOOD ENGI.
NEERING, IslIuxry 1988j p
99 to p101. In this heating system, an electrode is disposed at the center of the cross section of a conduit through which fluid food materials are conveyed, and the electrode has a hollow interior and is air-cooled.

Problems to be Solved by the Invention In the fluid food material heating system using Joule heating described in the above-mentioned US publication, the electrode is placed at the center of the cross section of the conduit through which the food material is conveyed.
In addition to the problem of the flow of food materials being obstructed by the electrodes and putting an unnecessary load on the pump that pumps the food materials, in the case of solid-liquid mixed food materials, the electrodes may become clogged with solids or destroyed. There are some problems that may occur. If solid matter in food materials gets stuck between the electrodes,
There is also the problem that the solid material is overheated and a large difference occurs between the heating conditions of the liquid component and the solid material.

Furthermore, in the heating system described above, since the current flows through the central part of the pipe (near the axis position), sufficient heating is not performed near the inner wall of the pipe, where heat radiation is large, and the central part of the pipe and the vicinity of the inner wall are There is also the problem that temperature differences tend to occur and uniform heating may not be possible. Also, in connection with this, even if you try to fine-tune the heating temperature by dividing the electrode pairs into multiple parts and using a weak current, the current will only flow in the center of the pipe, so the temperature will be fine and uniform. There is a problem that makes adjustment difficult. In particular, in practical equipment, it is necessary to increase the inner diameter of the pipe in order to increase the throughput, but in this case, the difference between the current flowing in the center of the pipe and the current flowing near the inner wall of the pipe becomes even more significant. Heating tends to become uneven.

In addition, in the heating system described above, the electrode area cannot be increased due to the structure in which the electrode is placed in the center of the conduit, which tends to cause uneven energization and the electrode area per unit area. There is a problem that the electrodes are damaged quickly because the amount of current is large. Furthermore, since the electrode area is small, it is easy for the electrode to overheat, but since the electrode is located in the center of the pipe, it is difficult to dissipate heat. Therefore, in the above-mentioned system, the electrode is made hollow and air-cooled from inside. However, such a configuration not only makes the structure extremely complicated, but also makes it difficult to clean the electrodes sufficiently, making them susceptible to microbial contamination. can be said to be undesirable.

The present invention has been made against the background of the above circumstances, and includes an apparatus that continuously heats a fluid food material by Joule heating in the pipe while transporting the food material in the pipe. Food materials can be heated continuously and evenly without creating flow resistance and increasing the load on the pressure pump, or clogging the pipes and destroying the solids in the food materials. It is an object of the present invention to provide a continuous heating device that can easily finely adjust the heating temperature, has a simple structure, and has high electrode durability.

Means for Solving the Problems This invention basically provides an apparatus for continuously heating a fluid food material by Joule heating in the pipe while continuously transporting the food material in the pipe. At least a part of the conduit is formed by an upstream insulating tube body and a downstream insulating tube body, each of which has at least an electrically insulating inner surface, and between the upstream insulating tube body and the downstream insulating tube body. , a first electrode body having a hollow cylindrical shape, a spacer tube having a hollow cylindrical shape and having at least an electrically insulating inner surface, and a second electrode body having a hollow cylindrical shape are arranged in series. , and each of the adjacent tube bodies and each of the electrode bodies are in contact with each other with substantially no step between the inner circumferential surface of the tube body and the inner circumferential surface of the electrode body. It is.

Here, the length direction of the pipe (the direction in which food materials are conveyed)
It is appropriate that the width of each electrode body is within the range of 1/4 to 2 times the inner diameter of the pipe. Further, the spacer tube can have a bent shape.

Function: In the continuous heating device of the present invention, fluid food material is continuously conveyed through the pipe.

Fluid food materials generally have conductivity, so
If an AC voltage is applied between the first electrode body and the second electrode body disposed in the middle of the conduit, the first electrode body and the second electrode body
An alternating current flows through the food material between the food material and the electrode body, and the food material generates heat due to its electrical resistance and is heated to a predetermined temperature.

Here, each electrode body is made into a hollow cylindrical shape, and the electrode body and the spacer tube between the electrode bodies are connected to the upstream insulating tube and the downstream insulating tube that form part of the conduit. They are arranged in series with the body. Therefore, each electrode body and spacer tube also constitute a part of the conduit. Moreover, each tube (upstream insulating tube, downstream insulating tube, and spacer tube) and each electrode body have substantially no level difference between the inner circumferential surface of the tube and the inner circumferential surface of the electrode. We are taking care to ensure that this does not occur. Therefore, the flow of the food material being conveyed in the pipe is not obstructed by the electrode body, so no extra load is applied to the pressure pump for conveying the food material. Solid matter in the liquid mixed food material will not clog or break near the electrode body. In addition, since the electrode body surrounds the entire food material being transported, current flows throughout the food material and the food material can be heated uniformly. In addition, since even a weak current can be applied uniformly, it is suitable for finely adjusting the heating temperature.

Furthermore, since increasing the inner peripheral surface area of the electrode body does not impede the flow of food materials, the inner peripheral surface area of the electrode body can be increased arbitrarily, which makes it possible to conduct electricity with a stable current. can. In addition, by increasing the area of the electrode body in this way, the amount of current per unit electrode area can be reduced, and because the heat dissipation of the electrode body itself is easy, overheating of the electrode body itself can be prevented. Damage to the electrode can be minimized, and elution of electrode body metal into food materials can also be minimized.

Furthermore, since each electrode body and spacer tube body only need to be arranged in series in the middle of the conduit, installation of the electrode body and spacer tube body is easy and the structure is simple. The electrode body is easy to clean and does not breed microorganisms, making it ideal for heating for sterilization.

If the width of the electrode body is set to 1/4 to 2 times the inner diameter of the conduit, a more stable current can be passed through the food material, and temperature unevenness can be more reliably prevented. . Here, the width of the electrode body is 1/4 of the inner diameter of the conduit.
If it is less than that, the contact area between the electrode body and the food material is small, so it may be difficult to flow a stable current.

On the other hand, since the contact interface between the electrode body and the food material is most likely to be heated, if the width of the electrode body exceeds twice the inner diameter of the conduit, the part that was in contact with the electrode body and the part that was not in contact with it will be separated. Temperature differences tend to occur. Therefore, the width of the electrode body is preferably within a range of 174 to 2 times the inner diameter of the conduit.

Furthermore, by forming the spacer tube between the electrodes into a bent shape, uneven heating and temperature unevenness of the food material can be more reliably prevented and uniform heating can be achieved. In other words, even if the inner diameter of the pipe is very large and causes uneven current distribution between the inner circumference and the center of the pipe, if the spacer pipe between the electrode bodies is bent [11+], the electrode body Since the food material also flows in a curved manner between the electrodes, the influence of uneven current distribution is reduced while the food material flows from the position of one electrode body to the position of the other electrode body, and heating unevenness and temperature unevenness are reduced. will be resolved. Furthermore, by bending the spacer tube, the food material can be stirred at that portion, which also contributes to eliminating uneven heating and temperature.

Embodiment FIG. 1 shows the basic structure of an example of the continuous heating device of the present invention.

In FIG. 1, both an upstream insulating tube 3 and a downstream insulating tube 4, which constitute a part of a conduit 2 through which a fluid food material, for example, a solid-liquid mixed food material 1, is conveyed are at least It is sufficient if the inner peripheral surface is made of an electrically insulating material, but generally the whole may be made of an electrically insulating material such as synthetic resin. These upstream insulating tubes 3 and downstream insulating tubes 4 are arranged at a predetermined interval, and between these insulating tubes 3.4 is a hollow cylindrical first electrode. body 5
A spacer tube body 6, which also has a hollow space shape, and a second electrode body 7, which also has a hollow cylindrical shape, are arranged in this order so as to be in contact with each other. The first electrode body 5 and the second electrode body 7 may be made of gold scrap with good conductivity, and may be made of aluminum, aluminum containing metal, titanium or titanium alloy, platinum, iron, etc. , corrosion resistance and hydrogen gas generation during energization! From the viewpoint of preventing electrical damage, it is desirable to use titanium or a titanium alloy. On the other hand, the spacer tube 6 only needs to be made of an electrically insulating material at least on its inner surface, but it is usually made of fluorocarbon resin, known as Teflon (trade name), which has low frictional resistance and is less likely to seize at high temperatures. The entire structure may be made of insulating resin.

These upstream insulating tube body 3, first electrode 5, spacer tube body 6, second electrode body 7, and downstream insulating tube body 4 are all made to have the same inner diameter and the same axis line. They are arranged in series with the center at the center, so that there is no step between them on the inner circumferential surface.

Here, as already mentioned, the width W of each electrode body 5.7 is the inner diameter of the conduit 2, that is, the width W of each tube body 3, 4.6 and the electrode body 5.7.
For the inner diameter R of No. 7, it is desirable to set it so that R/4≦W≦2R.

FIGS. 2 and 3 each show the basic structure of another example of the continuous heating device of the present invention.

In the examples shown in FIGS. 2 and 3, the spacer tube body 6 is bent, and other points are the same as the example shown in FIG. 1. In this case, as shown in FIGS. 2 and 3, the pipe center line Q of the spacer tube 6 is relative to the axis P connecting the center of the electrode body 5 and the center of the electrode body 7. There will be a relative displacement. Therefore, as already mentioned, even if the current distribution is uneven, the food material conveyed within the spacer tube 6 will flow across the current distribution, and the bending of the flow path will cause the food material to flow across the current distribution. tu+
+g also provides stirring, and as a result, it is possible to minimize the occurrence of uneven heating.

FIG. 4 shows the overall configuration of a more specific example of the heating device of the present invention, and FIGS. 5 and 6 show an enlarged cross section of a part thereof.

In FIG. 4, the reference numeral 10 at the left end is a pressurized container that houses food materials such as solid-liquid mixed food materials and has a pump function for conveying the food materials by applying pressure. It is configured to mechanically pressurize the food material with a plunger, or to pressurize the food material with air or an inert gas.

The conduit 2 extending from the lower end of the pressurized container 10 includes a pressure gauge 11, a first earth electrode device [12], and a heating electrode device [12].
3. A second earth electrode device 14 and a cooling device 15 are provided in that order, and the tip of the pipe line 2 is connected to a discharge side container 16.

Here, as shown in detail in FIG. 5, the first earth electrode device 12 includes a hollow cylindrical earth electrode body 17 sandwiched between tube bodies 2A and 2B constituting the conduit 2, and a pair of It is fixed by a flange member 18, 19 and a connecting bolt 20, and a temperature sensor 21 is attached to the ground electrode body 17, the tip of which extends into the inner flow path.
is provided. Therefore, this first ground electrode device 1112 serves as both a ground electrode and a temperature sensor. Note that the tubular body 2B in FIG. 5 is the same as that in FIGS.
This corresponds to the upstream insulating pipe body 3 shown in the figure.

On the other hand, the second earth electrode assembly 1114 may also be configured in the same manner as the first earth electrode assembly ffil2, but the temperature sensor 21 described above can be omitted.

Furthermore, the heating electrode device 13 in FIG. 4 constitutes a main part of the device of the present invention, and in principle it may have the configuration as shown in FIG. 6
As shown in the figure. In FIG. 6, the electrode bodies 5.7 each having a hollow short cylindrical shape are made of titanium, and the spacer tube body 6 sandwiched between these electrode bodies 5.7 has both sides made of an insulating material such as Bakelite. flange-like member 22 of
．． 23 and an intermediate cylindrical body 24 made of an insulating material such as Teflon, which has low frictional resistance and does not easily seize at high temperatures. and 7 langes 22.23
are connected and fixed by connecting bolts 25 on the outer circumferential side with the cylindrical body 24 sandwiched between them, and further between one flange-like member 22 and the upstream insulating tube 3, and between the other flange-like member 23 and the downstream It is connected and fixed to the side insulating tube body 4 by ring pieces 26, 27 and connecting bolts 28, with the electrolytic body 5 or 7 sandwiched between them. Further, terminal bars 29.30 are drawn out from each electrode body 5.7 through seven flange-like members 22.23, and power feeding lead wires 31.32 are connected to these terminal bars 27.30. Here, each member from the upstream insulating tube body 3 to the downstream insulating tube body 4 has the same inner diameter and is arranged around the same axis so that there are no steps on the inner peripheral surface. There is.

The cooling device 15 in FIG. 4 is designed to cool the area around the pipe line 2 with a cooling medium such as air or water, and is designed to cool the area around the pipe line 2 by taking in a cooling medium from a cooling medium population 33. The cooling medium is discharged from the cooling medium discharge port 34.

Furthermore, the discharge side container 16 in FIG. 4 is provided with a food material discharge port 36 through a valve 35 at the lower end, and
Pressure gauge 37, safety valve 38, solenoid valve 39 on top
It is equipped with a pressure control system, and is designed to adjust the pressure and to inject the heated food material into a packaging container or the like from the discharge port 36 at the lower end, or to lead it out to other processes. .

In FIG. 4, a heat retaining device 140 may be provided on the outer periphery of the conduit between the heating electrode device 13 and the second earth electrode device 11i14, as shown by the imaginary line.

The functions of the continuous heating device shown in FIGS. 4, 5, and 6 will be described next.

A fluid food material, such as a solid-liquid mixed food material, is poured into the pressurized container 10 from a hopper (not shown) or the like. Then, the food material is pressurized by a plunger or the like (not shown) and is continuously extruded into the pipe 2. The food material is fed through the pipe line 2, with its feeding pressure being monitored by the pressure gauge l1, and the first earth electrode assembly 1112 and the heating electrode assembly 1113.
, the second earth electrode device 14 , and the cooling device 15 before being sent to the discharge side container 16 . During this time, the temperature of the food material before heating is detected by the temperature sensor 21 provided in the first earth electrode device l2. And heating electrode device 1
At step 113, the food material between the electrode bodies 4.5 is energized from the electrode bodies 4.5 and heated by Joule heat generation. Further, leakage current flowing to the food material outside the heating electrode device 13 is grounded by the earth electrode device 12.14, thereby preventing danger from electric shock. The heated food material is kept warm for a predetermined period of time by a heat insulating device 40 as required, then reaches a cooling device 15 where it is rapidly cooled to a predetermined temperature, and then reaches a discharge side container 16.

The above example shows the case where one heating electrode device is provided, but if necessary, if two or three devices are connected and multiple devices are provided, the temperature of the food material can be more finely adjusted. This is possible, and damage to the electrode body is also reduced compared to the case where only l heating electrode devices are provided. In this case as well, it goes without saying that the spacer tubes as described above are provided between the electrode bodies, and it is also necessary to prevent any step from occurring on the inner circumferential surface between them, as described above.

Effects of the Invention As is clear from the above description, the continuous heating system of the present invention continuously heats a fluid food material by Joule heating within the pipe while continuously transporting the food material within the pipe. As the device, the flow of the food material is not obstructed by the electrode body, so there is no extra load on the pump etc. for pumping the food material, and the food material, especially in the solid-liquid mixed food material, is not impeded. Solid matter will not clog or break near the electrode body, and since electricity is applied from the entire outer circumference of the food material flowing in the pipe, there is less risk of uneven heating or temperature, and the weak current It is possible to easily fine-tune the temperature, and furthermore, the area of the electrode body (inner peripheral surface area used for energization) can be arbitrarily increased, so stable energization is possible.
In addition, it is possible to minimize damage to the electrode body and the elution of electrode body metal into food materials, and the structure is simple and easy to install. Since it can be easily cleaned, it is also ideal for heating purposes for sterilization.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the principle of an example of the continuous heating device of the present invention, and FIGS. 2 and 3 are longitudinal sectional views showing the principle of another example of the continuous heating device of the invention, respectively. Fig. 4 is a side view showing the overall configuration of a specific embodiment of the continuous heating device of the present invention, and Fig. 5 is an enlarged view of the first and second earth electrode devices used in the continuous heating device of Fig. 4. FIG. 6 is an enlarged vertical cross-sectional view of the heating electrode device used in the continuous heating device of FIG. 4. DESCRIPTION OF SYMBOLS 1...Food material, 2...Pipe line, 3...Upstream side insulating pipe body, 4...Downstream side insulating pipe body, 5...First
6... Spacer tube body, 7... Second electrode body. Figure 2 Figure 3

Claims (3)

[Claims] (1) In an apparatus that continuously heats a food material having fluidity by Joule heating in the pipe while continuously conveying the same in the pipe, at least a part of the pipe has at least an inner surface electrically heated. a first electrode body formed of an insulating upstream insulating tube body and a downstream insulating tube body, and having a hollow cylindrical shape between the upstream insulating tube body and the downstream insulating tube body; A spacer tube having a hollow cylindrical shape and having at least an electrically insulating inner surface and a second electrode body having a hollow cylindrical shape are arranged in series, and each of the tubes and each of the electrode bodies are adjacent to each other. refers to a continuous heating device for food materials having fluidity, characterized in that the inner circumferential surface of the tubular body and the inner circumferential surface of the electrode body are in contact with each other with virtually no difference in level. (2) The width of each electrode body in the pipe length direction is 1 of the pipe inner diameter.
2. The continuous heating device for food material having fluidity according to claim 1, wherein the heating temperature is within a range of /4 to 2 times. (3) The continuous heating device for fluid food material according to claim 1, wherein the spacer tube is bent.