Superheated steam generation device

Abstract

To provide a superheated steam generation device of a simple structure, used for sterilization, drying, roasting, etc. of food and furnishings.SOLUTION: A superheated steam generation device composed of: a long cylindrical body with one end closed and the other end open; a burner that is attached to the one closed end of the cylinder, and supplies fuel and air; a refractory heat-storage molded body installed at a position ahead of the burner in the cylindrical body; and an injection nozzle that is provided on a wall near a closed part in the cylinder, and injects mixture mist of pressurized water and pressurized air. As the refractory heat-storage molded body, one made of porous ceramic is preferable. Alternatively, it may be composed of a refractory basket-like container, and refractory heat-storage granular materials, such as silicon nitride ceramic balls, filled in the container.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a superheated steam generator, and more particularly to a superheated steam generator having a simple structure used for sterilization, drying, roasting, etc. of foods, feeds, and the like.

Background Art

[0002] Conventionally, in order to prevent food from spoiling or for processing, hot dry air has been applied to food for drying or roasting, and high-temperature superheated steam has been irradiated onto food for sterilization.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, there has been no device with a simple structure that can perform drying and heat treatment with superheated steam.

Means for Solving the Problems

[0005] The present invention solves such conventional problems and is a superheated steam generator having the following configuration. 〔1〕A long cylindrical body having one end closed and the other end open, A burner for supplying fuel and air attached to the closed one end of the cylindrical body, A porous ceramic refractory heat storage molded body installed at the tip position of the burner inside the cylindrical body, A superheated steam generator comprising an injection nozzle provided on the wall near the closing portion inside the cylinder for injecting a mist of a mixture of pressurized water and pressurized air. 〔2〕A long cylinder with one end closed and the other end open, A burner for supplying fuel and air attached to the closed end of the cylinder, A refractory heat storage molded body composed of a refractory cage-shaped container installed at the tip position of the burner inside the cylinder and a large number of refractory heat storage granules filled in the container, A superheated steam generator comprising an injection nozzle provided on the wall near the closing portion inside the cylinder for injecting a mist of a mixture of pressurized water and pressurized air. 〔3〕The superheated steam generator according to 〔2〕 above, characterized in that the refractory cage-shaped container is a container made of heat-resistant metal cage-shaped or heat-resistant ceramic fiber, and the refractory heat storage granules are heat-resistant metal balls or heat-resistant ceramic balls. 〔4〕The superheated steam generator according to any one of 〔1〕 to 〔3〕 above, characterized in that the long cylinder is inserted into a long large cylinder having a larger inner diameter than that.

Advantages of the Invention

[0006] According to the present invention, high-temperature superheated steam can be generated with a simple structure, and drying, roasting, and sterilization treatment of foods and the like can be performed.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0008] One embodiment of the present invention will be described with reference to the drawings. First, FIG. 1 is a cross-sectional explanatory diagram of the main part of the superheated steam generator of the embodiment of the present invention, which includes a long cylindrical body (1) with one end closed, a burner (2) for supplying fuel and air attached to the closed end of the cylindrical body (1), a refractory heat storage molded body (3) installed at the tip of the burner inside the cylinder, and an injection nozzle (4) provided on the wall near the closed part of the cylinder for injecting a mixture mist of pressurized water and pressurized air. The long cylindrical body (1) with one end closed and the other end open used in the superheated steam generator of the present invention is a cylindrical body such as a cylinder or a square cylinder made of a heat-resistant metal such as stainless steel (for example, SUS310S (25Cr - 20Ni)). The refractory heat storage molded body (3) installed inside this long cylindrical body is composed of ceramics such as silicon nitride, alumina, zirconia, cordierite, and silicon carbide, and is heated to a high temperature of 1,000 °C or more in contact with the flame of the burner and maintains the high temperature. In the present invention, a mixture mist of pressurized water and pressurized air is injected from an injection nozzle provided on the wall near the closed part of the cylindrical body (1) toward the surface of the refractory heat storage molded body (3) that maintains the high temperature. Then, the mixture mist of pressurized water and pressurized air hitting the surface of the high-temperature refractory heat storage molded body (3) is instantaneously heated to become high-temperature superheated steam and is ejected in the opening direction of the long cylindrical body.

[0009] Note that the mixture mist of water and air is different from mere pressurized water. Since the particle size of the water particles is very fine, 15 - 30 μm, it does not condense even when hitting the surface of the refractory heat storage molded body (3) and instantaneously vaporizes to become superheated steam.

[0010] Note that, unlike simple pressurized water, the mixture mist of water and air has extremely fine water particle diameters of 15 to 30 μm. Therefore, even when it hits the surface of the refractory heat storage molded body (3), it does not condense and instantly vaporizes into superheated steam. At this time, when water becomes superheated steam at 400°C, its volume expands by more than 2,500 times. Thus, a mixed gas containing carbon dioxide gas, water vapor, and nitrogen gas generated by the reaction of the fuel gas from the burner 4 with air is produced inside the cylindrical body (1). However, due to the huge expansion of the mist water, the mixed gas ejected from the cylindrical body (1) has a superheated steam content rate of 80% or more. Therefore, this mixed gas (superheated steam-containing gas) is an oxygen-free gas and does not oxidize the food ingredients of the object to be heat-treated. That is, sterilization, roasting, etc. can be performed without oxidizing the food ingredients. The refractory heat storage molded body (3) is preferably made of ceramics such as alumina, zirconia, and silicon carbide. The molded body is preferably porous because it has a large surface area, and particularly preferably a continuously porous one. Also, it may be a molded body provided with a large number of through holes in various places.

[0011] Furthermore, the refractory heat storage molded body (3) may be composed of a refractory cage-shaped container (made of punching metal) 3a filled with ceramic balls 3b as shown in FIGS. 3 and 4. In that case, silicon nitride ceramic balls are preferable as the ceramic balls 3b, and heat-resistant stainless steel, iron, titanium, tungsten, etc. are preferable as the punching metal. As the punching metal, a metal material having a low coefficient of thermal expansion is preferable. For example, an Invar alloy composed of Fe-36Ni or a Kovar alloy composed of Fe29Ni-17Co can be mentioned. In particular, the HRA929 alloy, which is less likely to warp or distort, is one of the preferable materials. As the refractory cage-shaped container, a heat-resistant metal (for example, SUS310S (25Cr-20Ni) (heat-resistant temperature 1035°C) or a titanium-made one) is preferable. Instead of the cage-shaped container, a box-shaped body provided with a large number of through holes in the wall may be adopted. In that case, the box-shaped body may be made of ceramic or ceramic fiber. As the refractory heat storage granular material to be filled, it is preferable to use heat-resistant ceramic balls such as silicon nitride, alumina, zirconia, silicon carbide, and cordierite.

[0012] It is preferable to provide a gap between the inner wall surface of the long cylindrical body and the outer surface of the refractory heat storage formed body, and it is desirable to provide a gap of 40 to 60% of the cross-sectional area of the cylindrical body trunk portion. By providing this gap, it is possible to facilitate the passage of high-temperature gas containing a large amount of superheated steam generated in the vicinity of the refractory heat storage formed body. This gap is preferably provided on the left and right, or on the left, right, top, and bottom.

[0013] Furthermore, as shown in FIG. 2, it is also preferable to cover the long cylindrical body (1) with a long large cylindrical body (1A) having a larger inner diameter than that (the long cylindrical body is inserted into a long large cylindrical body having a larger inner diameter than that). The long large cylindrical body (1A) serves to not directly transmit the surface temperature of the long cylindrical body (1) to the outside, and so to speak, it has a heat insulation effect. Furthermore, if air is pumped into the gap between the long large cylindrical body (1A) and the long cylindrical body (1), the superheated steam generated in the long cylindrical body (1) can be accelerated and discharged from the outlet. Note that this gap may be filled with a heat insulating material such as ceramic wool.

[0014] Next, a powder heat treatment apparatus incorporating the apparatus of the present invention will be described. The apparatus shown in FIG. 3 is a sterilization and roasting apparatus for flaky foodstuffs. In FIG. 3, a cylindrical drum (10) into which foodstuff flakes, which are objects to be heat-treated, are supplied is horizontally installed, and a large number of ceramic balls (11) are accommodated therein. The ceramic balls (11) are made of silicon nitride or alumina ceramic.

[0015] Above the cylindrical drum (10), an upper hollow chamber 20 formed in a box-cylindrical shape is arranged. The lower end thereof communicates with the drum (10), and an outlet (21) for taking out the heat-treated fine food pieces is provided protruding from the upper end of one side surface thereof. At the peripheral surface near the bottom of the cylindrical drum (10), the tip of the superheated steam-containing gas supply port (9) from the superheated steam generator of the present invention arranged along the tangential direction of the circumference of the drum (10) is open. Also, between this superheated steam gas supply port (9) and the upper hollow chamber (20), a food supply passage (30) for supplying the fine food pieces into the hollow chamber (20) is erected with its tip opening to the peripheral surface of the drum (10), and above it, a rotary feeder (31) for quantitatively supplying the fine food pieces is provided.

[0016] Using the apparatus shown in FIG. 3 above, when superheated steam is fed into the cylindrical drum (10) from the superheated steam supply port (9) of the superheated steam generator of the apparatus of the embodiment of the present invention, and fine food pieces are supplied from the food supply passage (30), the fine food pieces in the cylindrical drum (10) come into contact with the ceramic balls and are diffused while coming into contact with the superheated steam-containing gas and are heat-treated. Then, the heat-treated fine food pieces with reduced specific gravity rise in the upper hollow chamber (20) and are taken out to the outside from the outlet (21). Note that as the fine food pieces, okara, bran, rice flour, rice bran, buckwheat, fish meal, sawdust for mushroom cultivation, etc. are adopted.

Example

[0017] Next, an example of the present invention will be described. Example 1; The superheated steam generator of the present invention shown in FIG. 1 was used. That is, a flame is irradiated from a burner (2) for supplying fuel and air, which is attached to one closed end of a cylindrical body (1) of a superheated steam-containing gas generator shown in FIG. 1, to a refractory heat storage molded body (3) installed at a position in front of the burner inside the cylindrical body to heat it to a high temperature. Then, a mixture mist of pressurized water and pressurized air is injected from an injection nozzle (4) provided on the wall near the closed portion inside the cylindrical body onto the refractory heat storage molded body (3) heated to the high temperature. As a result, a gas at 800 °C containing 80% or more of water vapor gas (H 2 2O) spouted vigorously from the opening of the long cylindrical body (1).

[0018] The long cylindrical body (1) used in this example, with one end closed and the other end open, was made of stainless steel (SUS310S). First, a long cylindrical body (1) with one end closed and the other end open was made of stainless steel; SUS310S with a thickness of 2 mm. Its size was a body diameter of 101.6 mm and a total length of 770 mm. A burner (2) was attached to one end of the cylindrical body (1), and an injection nozzle (4) was also attached. Furthermore, a refractory heat storage molded body (3) made by filling a cage-shaped container made of stainless steel; SUS310S with a large number of silicon nitride ceramic balls was arranged at a position in front of the burner (2) inside the cylindrical body (1). As the refractory heat storage molded body (3), a punched metal cage with a height of 60 mm × width of 60 mm × length of 80 mm made using a plate with holes with a diameter of 5 mm drilled at 0.9 holes / 10 mm in a SUS310S plate with a thickness of 3 mm was filled with silicon nitride ceramic balls with a diameter of 10 mm. 2 As the refractory heat storage molded body of the present invention, silicon nitride ceramic is very suitable, has strong thermal shock resistance, and can be used stably for a long time without cracking even when a mixture mist of pressurized air (0.3 MPa) and pressurized water is directly injected onto the high-temperature silicon nitride ceramic. The cage-shaped refractory heat storage molded body made of heat-resistant metal was arranged at a position 200 mm away from the burner (2) inside the cylindrical body (1) at its rear end. ​And a gap of 40 to 60% of the cross-sectional area of the cylindrical body portion was provided between the inner wall surface of the long cylindrical body and the outer surface of the refractory heat storage molded body.

[0019] Therefore, 2 m / h of LPG as fuel and 8.6 m / h of air were injected from the burner 2. 3 / h, and a mixture mist of pressurized air (0.3 MPa) and pressurized water (water droplet diameter 20 μm) (pressurized air: water = 500: 1) at 150 ml / min was injected from the injection nozzle toward the refractory heat storage molded body (3) heated to 1000 °C. 3 As a result, superheated steam at 800 °C containing 80% or more of water vapor gas (H O) was ejected from the opening at the other end of the cylindrical body (1) at 5.9 m / min. 2 / min. 3

[0020] Example 2; Rice bran was heat-treated using the sterilization and roasting apparatus for flaky foodstuffs shown in Fig. 3 incorporating the superheated steam generator shown in 1 above. That is, superheated steam at 400 °C was fed into the cylindrical drum (10) from the superheated steam supply port (9) shown in Fig. 3, and rice bran was supplied from the foodstuff supply passage (30). The rice bran was brought into contact with the superheated steam for 5 seconds while being brought into contact with and stirred with ceramic balls in the cylindrical drum (10). Then, the heat-treated rice bran with a reduced specific gravity was taken out from the outlet (21) of the upper hollow chamber (20). As a result, the rice bran, which had a moisture content of 12.15%, a general viable count of 2.5 × 105 cells, and a non-measurable large number of coliform bacteria before the treatment, became roasted rice bran with a moisture content of 1.18%, a general viable count of 1.0 × 102 cells, and a negative coliform count after being irradiated and contacted with the above 400 °C superheated steam for 5 seconds.

Explanation of Reference Numerals

[0021] 1; Long cylindrical body 1A; Outer cylinder 1B; Gas inlet 2; Burner 3; Refractory heat storage molded body 3a; Basket-shaped container 3b; Ceramic ball 4; Injection nozzle 9; Superheated steam-containing gas supply port (opening of a long cylindrical body) 10; Cylindrical drum 11; Ceramic ball 20; Upper hollow chamber 21; Outlet 30; Fine food material supply passage 31; Rotary feeder

Claims

1. A long cylindrical body (1) having one end closed and the other end open; a burner (2) for supplying fuel and air, the burner being attached to one closed end of the cylinder; A porous ceramic refractory heat storage molded body (3) is installed in front of the burner inside the cylinder; a spray nozzle (4) provided on the wall near the closed portion of the cylindrical body for spraying a mixture mist of pressurized water and pressurized air.

2. A long cylindrical body (1) having one end closed and the other end open; a burner (2) for supplying fuel and air, the burner being attached to one closed end of the cylinder; a refractory heat storage molding (3) consisting of a refractory basket-shaped container (3a) installed in front of the burner in the cylinder and a large number of refractory heat storage granules (3b) filled in the container; a spray nozzle (4) provided on the wall near the closed portion of the cylindrical body for spraying a mixture mist of pressurized water and pressurized air.

3. 3. The superheated steam generator according to claim 2, wherein the refractory basket-shaped container is a heat-resistant metal basket-shaped container or a heat-resistant ceramic fiber container, and the refractory heat storage granules are heat-resistant metal balls or heat-resistant ceramic balls.

4. 4. The superheated steam generator according to claim 1, wherein the long cylindrical body is inserted into a long large cylindrical body (1A) having an inner diameter larger than that of the long cylindrical body.

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