JPH06181726A - Closed type steam heat treatment method and device therefor - Google Patents

Abstract

PURPOSE:To provide a closed type steam heat treatment method capable of performing energy saving and a sure heat treatment by quickly and homogeneously filling with steam, a can containing an article to be heated and to provide the device used therefor. CONSTITUTION:Saturated steam lowered in its pressure and temperature is charged in the upper part of a steam can 1 with prescribed portions to form a high temperature steam layer (a) on one surface of the upper part of the steam can 1, and further the steam is continuously supplied into the steam can to thicken the high temperature steam layer (a) for the successive descent of the bottom of the layer. With the descent of the bottom of the high temperature steam layer, air existing in the steam can 1 is discharged from the discharging port 3a of the bottom in the steam can 1 to replace the air in the can 1 with saturated steam lowered in its pressure and temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an invention of a closed steam heat treatment method and apparatus for heating and sterilizing foods such as canned foods and bottled foods with steam.

[0002]

2. Description of the Related Art Conventionally, in order to sterilize food stored in canned foods, bottled foods, resin packs, etc., it has been widely practiced to heat and sterilize foods with steam in a closed steaming can. In the closed-type steam heat treatment as described above, a food product to be heated is stored in a steam can whose airtightness is maintained, and high-pressure steam is blown from a discharge port of a steam discharge pipe arranged at the bottom of the steam can. The food is sterilized by placing it in the upward flow of the discharged steam for a predetermined time.

[0003]

However, in the conventional closed-type steam heat treatment as described above, high-pressure steam is discharged from the bottom of the steaming can to heat the food in the ascending flow of the steam. Therefore, when the steam flow rises while touching the food, the steam flow is greatly disturbed and irregularly mixes with the room temperature air existing in the can, resulting in large irregularities in the flow in the can. For this reason, a thin film air layer remains on the surface of a part of the food stored in the can, resulting in a problem that a part that does not rise to a predetermined temperature and a part that overheats coexist in a predetermined time. As a result, sterilization of foods may be incomplete, extra heating time may be required, and the quality of some foods may be damaged by overheating.

An object of the present invention is to provide a closed steam heat treatment method and apparatus capable of performing energy saving and reliable heat treatment by filling a can containing a substance to be heated with steam in a short time and evenly. To do.

[0005]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides the following means. The closed-type steam heat treatment method according to the present invention, after decompressing and lowering the temperature of saturated steam, slowly discharging a predetermined amount into the upper part of the steaming can containing the object to be heated, so that the high temperature steam is spread over the entire upper part of the steaming can By forming a layer and further continuing to discharge the saturated vapor, the high temperature vapor layer is thickened in the vaporization can and the bottom surface of the layer is sequentially lowered, and the vaporization inside the vaporization can is accompanied by the lowering of the high temperature vapor layer. The existing normal-temperature air is naturally discharged from the outlet at the bottom of the steaming can to the atmosphere outside the steaming can, and the atmosphere inside the steaming can is decompressed.
It is filled with dehumidified high temperature steam. The hermetic heat treatment apparatus of the present invention constitutes a steam can for containing an object to be heated, arranges a steam discharge pipe in the upper part of the steam can, and directs steam upward along the steam discharge pipe. A large number of discharge holes for discharging are provided, a steam supply pipe equipped with a pressure reducing valve is connected to the steam discharge pipe, and a primary port of a discharge pipe for communicating with the atmosphere outside the steam can is arranged at the bottom of the steam can. It will be. Further, in the above apparatus, the discharge hole provided in the steam discharge pipe is set at 60 degrees from the horizontal
It is advisable to open the holes at an upward angle of about 80 degrees.

[0006]

According to the closed-type steam heat treatment method of the first aspect, when the saturated and depressurized and dehumidified saturated steam is gently discharged into the upper part of the steaming container by a predetermined amount, the steam is against the air existing in the steaming can. Due to the specific gravity, a high temperature vapor layer is formed by gradually accumulating on the entire upper surface in the steam can. By continuously supplying decompressed and depleted saturated steam, the temperature in the high temperature steam layer is maintained at a predetermined temperature, the thickness of the steam layer accumulated in the upper part of the steam can increases, and the bottom surface of the layer gradually increases. Begins to descend. Therefore, the object to be heated housed in the steam can is gradually covered with the thickened high temperature steam layer from above, and heating is started. At this time, the room temperature air existing around the object to be heated is pushed down without remaining due to the gentle fall of the high temperature steam layer, and the object to be heated is directly covered with the high temperature steam. As the high-temperature steam layer thickens and the bottom of the same layer descends, the air existing in the steam can is pushed down and discharged to the outside through the discharge port at the bottom of the steam can. The interior is filled with a high temperature vapor layer that increases in thickness from the top to the bottom as described above.

According to the hermetic heat treatment apparatus of the second aspect, the steam supply pipe is connected to the steam discharge pipe disposed in the upper portion of the steam can. The steam supplied from the steam supply pipe passes through the pressure reducing valve to be decompressed and cooled, and then supplied to the steam discharge pipe. A large number of discharge holes are formed along the steam discharge pipe, and the reduced pressure steam is discharged upward from the discharge holes. The steam discharged upward from the discharge hole of the steam discharge pipe gently spreads over the entire upper surface inside the steam can to form a high-pressure steam layer as described above, and then gradually thickens toward the bottom of the can. To descend.
Along with this, the air existing in the can is discharged to the outside of the can from the primary opening of the discharge pipe provided at the bottom of the can, and the inside of the can is filled with the thickened high-pressure vapor layer.

[0008]

As described above, according to the present invention, the saturated vapor which has been decompressed and reduced in temperature is continuously discharged into the upper portion of the steaming can by a predetermined amount to form a high temperature vapor layer in the upper portion of the steaming can. By increasing the thickness of the high-temperature vapor layer and gradually lowering it toward the bottom of the can, the heated object contained in the can is directly filled in the high-temperature vapor layer, which has a uniform temperature distribution, without residual air. At the same time, a method of naturally discharging the air existing in the steam can from the discharge port at the bottom of the can is taken. Therefore, it is possible to significantly reduce the time required to fill the steaming can with steam to obtain a predetermined temperature, and to uniformly heat the object to be heated housed in the can evenly and sterilize it reliably. be able to. According to this, the time required for heat sterilization can be significantly shortened, the energy saving effect is higher than the conventional one, and the efficiency of sterilization treatment can be significantly improved. In the closed heat treatment apparatus according to claim 2, the high-pressure vapor layer is formed on the entire upper surface of the can by gradually discharging the reduced pressure steam upward from the discharge hole of the steam discharge pipe arranged in the upper portion of the can. It is formed without turbulence, and by descending toward the bottom of the can while increasing the pressure of this high temperature steam layer, the object to be heated contained in the can is filled in the high temperature steam layer with a uniform temperature distribution, and at the same time It is possible to quickly discharge the room temperature air in the can from the primary opening of the discharge pipe provided at the bottom of the can, and thereby to achieve the above-mentioned effect. Further, in the above-mentioned closed heat treatment apparatus, by opening the angle of the discharge hole of the steam discharge can at an upward angle of about 60 to 80 degrees with respect to the horizontal, the steam discharged from the discharge hole is directed obliquely upward. It is discharged and smoothly flows along the ceiling surface in the can without being disturbed, whereby a uniform high-temperature vapor layer can be formed on the entire upper surface of the can.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 show a closed steam heat treatment apparatus embodying the present invention. This closed-type steam heat treatment apparatus includes a steaming can 1 for storing foods such as canned foods and bottled foods to be heated, and steam supplied from a steam supply pipe 5 to the upper part of the steaming can 1 to the upper part of the can. A steam discharge pipe 2 for discharging is arranged, and a primary outlet 3a of a discharge pipe inserted into the can from the ceiling surface of the steam can 1 is arranged at the bottom of the can.

The steam can 1 is an airtight chamber that accommodates an object to be heated in and out, and a rectangular box-shaped body is formed by using a steel plate, and an accommodation space is formed therein. Also, on one side of the steaming can 1, there are two entrances / exits 9a for putting in / out the object to be heated.
And the airtight doors 9b are installed at the doorways 9a.
It is configured so that it can be opened and closed freely. A floor surface 1a is formed on the bottom surface of the steam can 1 by a mesh plate, whereby water drops that condense and flow in the steam can 1 pass through the floor surface 1a on which the object to be heated is placed. It is configured to be dropped on the bottom surface of the steam can 1. The water dropped on the bottom of the steam can 1 is collected in a drainage pipe 7 provided on the bottom of the steam can 1 and drained.

The steam supply pipe 5 supplies steam sent from a boiler (not shown) to the steam discharge pipe 2.
A pressure reducing valve 4 is provided in the middle portion. The pressure reducing valve 4 is an automatic pressure reducing valve whose operation is controlled by a control unit (not shown), and the steam supplied through the steam supply pipe 5 is reduced to a predetermined pressure by passing through the pressure reducing valve 4. At the same time, the temperature is reduced.

A steam discharge pipe 2 provided in the upper part of the steam can 1.
Are piped along the opposite long sides in the upper part of the steam can 1, and both ends of these steam discharge pipes 2 are closed and
The intermediate portions of are connected to each other by a connecting pipe 2a, and the steam supply pipe 5 is connected to the connecting pipe 2a. Further, along the both steam discharge pipes 2, a large number of discharge holes 8 for discharging the steam supplied from a steam supply pipe 5 described later are opened. The discharge holes 8 are opened in parallel in two rows along the steam discharge pipe 2, and each discharge hole 2 is opened at an upward angle of about 60 to 80 degrees with reference to the horizontal as shown in FIG. is there. As a result, the steam discharged from the discharge hole 2 is discharged obliquely upward and smoothly flows along the ceiling surface in the can without being disturbed, and a uniform high-temperature steam layer is formed on the entire upper surface of the can. can do. The above-mentioned discharge holes 8 may be opened in parallel along the steam discharge pipe 2 or may be opened in a staggered manner along the steam discharge pipe 2.

The discharge pipe 3 is vertically inserted from above along the four corners of the steam can 1, and the primary port 3a provided at the lower end is located at the bottom of the can. Further, the upper end openings of the discharge pipes 3 facing each other through the short sides are gathered into one via the gathering pipe 3b. A temperature sensor 6 is installed near the primary port 3a of the discharge pipe 3 described above. The temperature sensor 6 is the primary port 3a
The temperature of steam discharged from the temperature sensor is detected, and the temperature data is output to a control unit (not shown). Based on the temperature data detected by the temperature sensor 6, the control unit controls the temperature of the pressure reducing valve. It is configured to maintain the temperature of the steam inside the steam can 1 at a set temperature by adjusting the opening degree to increase or decrease the supply amount of steam.

Next, a heat treatment method performed by using the closed steam heat treatment apparatus having the above-mentioned structure will be described. For example, when sterilizing processed foods such as canned foods and bottled foods, foods to be heat-treated are arranged in a multi-stage using a carrier,
The carrier is housed in the steam can 1 as shown in FIG. Steam sent from a boiler (not shown) is supplied into the steam can 1 via the steam supply pipe 5. The steam supplied through the steam supply pipe 5 is depressurized to a predetermined pressure when passing through the pressure reducing valve 4, and at the same time, the temperature is decreased, and the steam is sent into the steam discharge pipe 2 in a saturated state. The pressure reducing valve 4 is a control unit (not shown) as described later.
The degree of valve opening is automatically controlled by the operation control from (1) to (3), whereby the depressurized amount of steam and the steam supply amount to the steamer 1 are adjusted.

The steam supplied to the steam discharge pipe 2 is gently discharged upward from the discharge holes 8 formed in a large number along the pipe 2. The steam discharged obliquely upward from the discharge holes 8 gradually accumulates on the entire upper surface in the steam can 1 due to the specific gravity with respect to the room temperature air existing in the steam can 1, and forms a high temperature steam layer a. Then, if the pressure is reduced and the temperature is continuously supplied from the discharge hole 8 of the saturated steam vapor discharge pipe 2, the temperature in the high temperature steam layer a accumulated in the upper part of the can is maintained at a predetermined temperature or higher, and at the same time, the vapor Due to the accumulation, the thickness of the vapor layer a increases and the bottom surface of the layer a gradually descends. As a result, the food stored in the steam can 1 is gradually covered from above by the thickened high temperature steam layer a, and heating is started. At this time, the room temperature air existing so as to come into contact with the food is pushed down without remaining by the gentle fall of the high temperature steam layer a, and all the food is directly covered with the high temperature steam. This heats the food uniformly and effectively. As described above, as the temperature of the high temperature vapor layer a increases and the bottom of the layer a descends, the room temperature air existing in the steam can 1 is pushed down, and the exhaust gas located at the bottom of the four corners of the can is discharged. It is gradually discharged out of the can through the primary opening 3a of the pipe 3. Then, finally, the room temperature air is completely discharged from the inside of the steam can 1, and the inside of the can is filled with the high temperature steam layer a which gradually drops from the top to the bottom instead of the room temperature air.

As described above, even after the inside of the steam can 1 is filled with the high temperature steam, the steam discharge pipe 2 is provided to maintain the steam temperature in the can.
The saturated and depressurized saturated steam is supplied from the steam generator, and along with this, the steam is discharged from the primary port 3a of the discharge pipe 3 located at the bottom of the can. In this state, the temperature of the steam discharged from the primary port 3a is detected by the temperature sensor 6, and the detected temperature data is output to the control unit (not shown). The control unit captures the temperature data of the exhaust steam sent from the temperature sensor 6 as the temperature inside the steam can 1, and compares the value with a preset temperature. When the temperature data detected by the temperature sensor 6 is lower than the set temperature, the control unit opens the pressure reducing valve 4 by a required amount to increase the supply amount of steam, and when the temperature data is higher than the set temperature, The pressure reducing valve 4 is closed by a required amount to reduce the supply amount of steam, and thereby the temperature inside the can is controlled to be maintained at the set temperature.

By carrying out the heat treatment as described above, the food contained in the steam can 1 can be directly filled in the high temperature vapor layer a having a uniform temperature distribution without the presence of residual air. Therefore, it is possible to uniformly heat the food in the can and sterilize it reliably in a short time, and it is possible to significantly reduce the time required for heat sterilization. For example, when milk was actually sterilized based on the above-mentioned example, the time required for sterilization could be shortened from 40 minutes in the past to 15 to 16 minutes. Furthermore, since the exhaust pipe 3 is naturally exhausted simultaneously with the discharge of the reduced pressure steam, the inside of the steam can 1 is not pressurized. As a result, the structure of the device can be greatly simplified as compared with that requiring a pressure vessel, and the device can be easily installed.

In addition to the sterilization of food, the closed heating method and apparatus of the present invention can be used as a food heater, steamer, sterilization of cultivation base in mushroom cultivation, and further steam curing of PC concrete. It is possible to

[Brief description of drawings]

FIG. 1 is a perspective view showing a closed steam heat treatment apparatus according to the present invention.

FIG. 2 is a perspective view showing the inside of the apparatus.

FIG. 3 is a vertical cross-sectional view showing a steam discharge can portion.

FIG. 4 is a vertical sectional view of the device.

[Explanation of symbols]

 a ... High temperature steam layer 1 ... Steam can 2 ... Steam discharge pipe 3 ... Discharge pipe 3a ... Primary port 4 ... Pressure reducing valve 5 ... Steam supply pipe 8 ... Discharge Hole

Claims (3)

[Claims] 1. A high-temperature vapor layer is formed on the entire upper surface of the steaming can by gradually depressurizing and reducing the temperature of the saturated steam, and then slowly discharging a predetermined amount of the saturated steam into the upper part of the steaming can. Further, by continuing to discharge the saturated steam, the high temperature vapor layer is thickened in the vaporization vessel and the bottom surface of the layer is gradually lowered. As the high temperature vapor layer descends, the normal temperature air existing in the vaporization vessel is removed. A closed steam heat treatment method in which the atmosphere inside the steaming can is naturally discharged from the outlet at the bottom of the steaming can, and the atmosphere inside the steaming can is filled with decompressed and decompressed high temperature steam. 2. A steaming can for containing an object to be heated, a steam discharging pipe is arranged in an upper part of the steaming can, and a discharging hole for discharging steam upward along the steam discharging pipe. A closed type steam in which a large number of holes are bored, a steam supply pipe equipped with a pressure reducing valve is connected to the steam discharge pipe, and a primary outlet of a discharge pipe communicating with the atmosphere outside the steam can is arranged at the bottom of the steam can. Heat treatment equipment. 3. The closed steam heat treatment apparatus according to claim 2, wherein the discharge hole provided in the steam discharge pipe is opened at an upward angle of about 60 to 80 degrees with respect to the horizontal.