The present invention relates to superheated steam sterilization apparatus for grains and, more particularly, to a superheated steam sterilization apparatus configured to sterilize brown rice obtained by hulling paddy at a stage prior to packing into a bag so that brown rice can be distributed in the hulled state without being contaminated with insect pests.
Hitherto, grain sterilizing methods and apparatus of the type described above are publicly known and disclosed, for example, in Patent Literature 1. PTL 1 describes a sterilization apparatus (e.g. an ultraviolet sterilization lamp) which is attached to the discharge side of a hulling machine or a rice polishing machine. Brown rice or polished rice is sterilized by ultraviolet light from the ultraviolet sterilization lamp at a stage prior to packing into a bag. Accordingly, the eggs of insect pests cannot be hatched, and the whole rice grains are protected from being contaminated with insect pests. However, the sterilization apparatus described in PTL 1 is a simple apparatus attached to the discharge side of a hulling machine or a rice polishing machine and inferior in sterilization capability and therefore cannot be said to provide a sufficient sterilization effect.
There is known another sterilization method in which superheated steam (dry superheated air) obtained by superheating steam to 100° C. or more is used as a heating medium to sterilize grains. Such techniques are disclosed, for example, in Patent Literature 2 and Patent Literature 3.
PTL 2 describes a sterilization apparatus configured to blow superheated steam into a rotary valve. With this structure, a sufficient sterilization effect can be obtained despite a simple apparatus. However, the sterilization apparatus is not practical to treat a large amount of grains because the apparatus is configured such that grains are purposely supplied into a rotary valve so as to be sterilized with superheated steam.
PTL 3 describes a sterilization apparatus in which an agitating device is horizontally installed in a horizontal cylindrical container, and multiple common nozzles used for both superheated steam and saturated steam are provided at the upper end of the horizontal cylindrical container. The sterilization apparatus has the advantage of being surely applicable to various objects to be sterilized by effectively using latent heat. However, partition plates surrounding each common nozzle are formed in the shape of oblong plates having short vertical sides; therefore, the partition plates cannot reach the area where the agitating device is disposed. Consequently, the agitating device is placed in an open state (see FIG. 3 of PTL 3), so that the action and effect of the partition plates can hardly be exerted on the above-described area. As a result, there may occur uneven application of superheated steam in the area where the agitating device is disposed.
Regarding the maintainability of the sterilization apparatus described in PTL 3, it is only mentioned in paragraph [0013] of PTL 3 that “A drain pipe is preferably provided via an opening-closing valve at any position of the lowermost portion having a semicircular cross-section of the lower part of the horizontal cylindrical container 5”. In other words, when the interior of the horizontal cylindrical container is cleaned, or when there is a failure in the agitating device horizontally installed in the horizontal cylindrical container, a plate member covering the upper side of the horizontal cylindrical container needs to be removed to open the container. For this reason, the sterilization apparatus cannot necessarily be said to have excellent maintainability.
PTL 1: Japanese Patent Application Laid-Open Publication No. S62-58951
PTL 2: Japanese Patent Application Laid-Open Publication No. H10-211103
PTL 3: Japanese Patent Application Laid-Open Publication No. H8-89222
In view of the above-described circumstances, it is desirable to provide a superheated steam sterilization apparatus capable of continuously sterilizing a large amount of grain and of eliminating uneven application of superheated steam even if a large amount of grain is loaded thereinto.
It is also desirable to provide a superheated steam sterilization apparatus capable of continuously sterilizing a large amount of grain and superior in maintainability.
The present invention has been made to solve at least a part of the above-described problems and can be realized, for example, in the following aspects.
A first aspect of the present invention provides a superheated steam sterilization apparatus. The superheated steam sterilization apparatus includes: a horizontal cylindrical part including one end formed with a supply port for supplying an object to be sterilized and an opposite end formed with a discharge port for discharging a sterilized object; a rotating shaft part rotatably disposed in the horizontal cylindrical part, and including a helical screw configured to transfer the supplied object to be sterilized and an agitating member including a plurality of agitating blades configured to agitate the object to be sterilized; a plurality of superheated steam nozzles disposed above the horizontal cylindrical part; a superheated steam box disposed on the horizontal cylindrical part, divided into a plurality of sections along an axial direction, and configured to temporarily store superheated steam supplied from the superheated steam nozzles; and a steam outlet for applying the superheated steam stored in the superheated steam box to the object to be sterilized which is transferred and agitated in the horizontal cylindrical part.
According to the first aspect, a large amount of object (grain) to be sterilized can be continuously sterilized by the horizontal cylindrical part and the rotating shaft part. In addition, superheated steam from the superheated steam nozzles can be temporarily stored in the superheated steam box and then applied to the object to be sterilized from the steam outlet set to an appropriate degree of opening. Therefore, the object to be sterilized can be sterilized by superheated steam applied over a widened area (the steam outlet has an opening area larger than that of the superheated steam nozzle having a small nozzle diameter). Accordingly, superheated steam is applied not locally but to a wide area even when a large amount of object (grain) to be sterilized is loaded. Consequently, it is possible to eliminate uneven application of superheated steam to the object to be sterilized.
According to a second aspect of the present invention, in the first aspect, the superheated steam sterilization apparatus further includes an opening-closing shutter provided at the steam outlet. The opening-closing shutter is configured to adjust the amount of the superheated steam to be applied by adjusting the opening area of the steam outlet.
According to the second aspect, if the degree of opening of the opening-closing shutter is set to fully open, it is also possible to sterilize grains containing a large number of bacteria (e.g. grains that seem to have a large number of bacteria grown thereon, for example, brown rice having been stored for a long period of time in a state of being mixed with paddy and chaff). On the other hand, if the degree of opening of the opening-closing shutter is set to half-open, it is also possible to sterilize grains containing a small number of bacteria (e.g. polished and sorted grains obtained by completely removing paddy and chaff from brown rice) in an energy-conserving manner with a reduced supply of the superheated steam.
According to a third aspect of the present invention, in the first or second aspect, the superheated steam sterilization apparatus further includes a cooling part connected to the discharge port of the horizontal cylindrical part for discharging the sterilized object. The cooling part includes a horizontally disposed screen tube, a helical screw and an agitating member which are disposed in the screen tube, and a suction fan configured to send cooling air into the screen tube.
According to the third aspect, the cooling part is connected to the discharge port of the horizontal cylindrical part for discharging the sterilized object. Therefore, in the cooling part, the sterilized object, which has been sterilized by the superheated steam, is supplied into the screen tube. In addition, the cooling part carries out agitating with the agitating member while taking the outside air into the screen tube from an outside air inlet by driving the suction fan. Thus, effective cooling processing is performed. Meanwhile, foreign substances, gravel, etc. caught between the grains of the object to be sterilized drop through meshes of the screen tube. Therefore, these foreign substances and gravel can be discharged to the outside of the machine.
A fourth aspect of the present invention provides a superheated steam sterilization apparatus. The superheated steam sterilization apparatus includes: a horizontal cylindrical part including one end formed with a supply port for supplying an object to be sterilized and an opposite end formed with a discharge port for discharging a sterilized object; a rotating shaft part rotatably disposed in the horizontal cylindrical part, and configured to transfer the supplied object to be sterilized while agitating the object to be sterilized; a superheated steam nozzle disposed above the horizontal cylindrical part; a superheated steam box disposed between the superheated steam nozzle and the horizontal cylindrical part, and configured to temporarily store superheated steam supplied from the superheated steam nozzle; and a steam outlet for applying the superheated steam stored in the superheated steam box to the object to be sterilized which is transferred and agitated in the horizontal cylindrical part.
The forth aspect offers advantages similar to those of the first aspect.
A fifth aspect of the present invention provides a superheated steam sterilization apparatus. The superheated steam sterilization apparatus includes: a horizontal cylindrical part including one end formed with a supply port for supplying an object to be sterilized and an opposite end formed with a discharge port for discharging a sterilized object; a rotating shaft part rotatably disposed in the horizontal cylindrical part, and including a helical screw configured to transfer the supplied object to be sterilized and an agitating member including a plurality of agitating blades configured to agitate the object to be sterilized; a plurality of superheated steam nozzles disposed above the horizontal cylindrical part; a superheated steam box disposed on the horizontal cylindrical part, divided into a plurality of sections along an axial direction, and configured to temporarily store superheated steam supplied from the superheated steam nozzles; and a steam outlet for applying the superheated steam stored in the superheated steam box to the object to be sterilized which is transferred and agitated in the horizontal cylindrical part. The horizontal cylindrical part is formed to be splittable into a base portion arcuately covering most part of the rotating shaft part and a maintenance cover portion removable from the base portion and arcuately covering a part of the rotating shaft part.
The fifth aspect offers advantages similar to those of the first aspect. Moreover, when the interior of the horizontal cylindrical part is cleaned, or when the helical screw and the agitating member are repaired, the interior of the horizontal cylindrical part can be opened simply by removing the maintenance cover portion, which is exclusively used for maintenance, from the base portion, and thus the rotating shaft part is exposed. Accordingly, very excellent maintainability is obtained.
According to a sixth aspect of the present invention, in the fifth aspect, the base portion of the horizontal cylindrical part is formed in the shape of a circular are as viewed in a cross section. The circular are has a central angle exceeding 180° and extending from the uppermost point of a circle formed by the outline of the horizontal cylindrical part to the lowermost point of the circle and further extending upward from the lowermost point so that the base portion receives drain water generated from the superheated steam after sterilization.
According to the sixth aspect, the base portion is not in the shape of a semicircle having a central angle of 180° and extending from the uppermost point to the lowermost point of the circle, but in the shape of the circular arc having the central angle exceeding 180° and further extending upward from the lowermost point. Therefore, there is no fear that drain water produced in the cylindrical part may drop when the horizontal cylindrical part is disassembled. In other words, drain water is surely received by the circular arc-shaped portion, so that there is no fear of drain water dropping or spilling out over the floor when the apparatus is disassembled or cleaned.
According to a seventh aspect of the present invention, in the fifth or sixth aspect, the maintenance cover portion of the horizontal cylindrical part includes a plurality of handles for holding the maintenance cover portion at the time of maintenance.
According to the seventh aspect, the operator can remove and attach the maintenance cover portion by holding the handles at the time of maintenance. Accordingly, it is easy to remove and attach the maintenance cover portion, and operability is also improved.
An eighth aspect of the present invention provides a superheated steam sterilization apparatus. The superheated steam sterilization apparatus includes: a horizontal cylindrical part including one end formed with a supply port for supplying an object to be sterilized and an opposite end formed with a discharge port for discharging a sterilized object; a rotating shaft part rotatably disposed in the horizontal cylindrical part, and configured to transfer the supplied object to be sterilized while agitating the object to be sterilized; a superheated steam nozzle disposed above the horizontal cylindrical part; a superheated steam box disposed between the superheated steam nozzle and the horizontal cylindrical part, and configured to temporarily store superheated steam supplied from the superheated steam nozzle; and a steam outlet for applying the superheated steam stored in the superheated steam box to the object to be sterilized which is transferred and agitated in the horizontal cylindrical part. The horizontal cylindrical part is formed to be splittable into a base portion partially covering the rotating shaft part and a maintenance cover portion removable from the base portion and partially covering the rotating shaft part.
According to a ninth aspect of the present invention, the base portion of the horizontal cylindrical part has, as viewed in a cross section, a lowermost portion of the horizontal cylindrical part and a portion extending upward from the lowermost portion.
The eighth and ninth aspects offer advantages similar to those of the fifth and sixth aspects.
A preferred embodiment of the present invention will be explained below with reference to the drawings.
As shown in
The horizontal cylindrical part 3 includes a grain supply port 11 formed in an upper portion thereof at one end side in the axial direction. The cylindrical part 3 includes a grain discharge port 12 formed in a lower portion thereof at the other end side in the axial direction. A raw grain supply chute 13 is connected to the supply port 11, and a grain discharge chute 14 is connected to the discharge port 12. The discharge chute 14 communicates with a grain cooling part 20 in a subsequent step through a rotary valve or the like.
The rotating shaft part 6 is supported by a bearing 15a at one end side in the axial direction thereof. The other end side in the axial direction of the rotating shaft part 6 is supported by a bearing 15b. In addition, a drive pulley 16 that rotates the rotating shaft part 6 is installed at the other end side of the rotating shaft part 6. A rotational force of a drive motor 17 is transmitted to the drive pulley 16 through a motor pulley 18 and a belt 19.
The superheated steam sterilization apparatus 1 further includes a grain cooling part 20 in a stage following the superheated sterilization part 10. The grain cooling part 20 includes, as shown in
A drive pulley 33 that rotates the rotating shaft 23 is installed at one end side of the rotating shaft 23. A rotational force of a drive motor 34 is transmitted to the drive pulley 33 through a motor pulley 35 and a belt 36. In the grain cooling part 20, grains superheated-sterilized in the superheated sterilization part 10 are supplied into the screen tube 22 to cool down the heated grains. The grain cooling part 20 performs agitating with the agitating member 26 while taking the outside air into the screen tube 22 from an outside air inlet 38 by driving the suction fan 28. Consequently, heat accumulated between the grains is taken away therefrom, and thus cooling is performed. In addition, foreign substances, gravel, etc. caught between the grains drop through the meshes of the screen tube 22. Accordingly, it is also possible to separate foreign substances, gravel, etc. from the grains and to discharge the separated substances to the outside of the machine. A foreign substance collecting trough 37 is installed underneath the screen tube 22. The foreign substance collecting trough 37 collects foreign substances, gravel, etc. separated from the grains and discharges the collected substances to the outside of the machine.
Referring to
The sidewall 41a has an inspection opening 46 formed therein so that the operator can adjust the opening-closing shutter 43. In addition, the sidewall 41a is provided with an inspection lid 47 for closing the inspection opening 46 (see
Next, the maintenance structure of the horizontal cylindrical part 3 will be explained in detail with reference to
Referring to
In addition, the maintenance cover portion 3b is provided with handles 51a and 51b for removal. Therefore, when maintenance is performed, the operator can remove fixing nuts 52a to 52b while holding the handles 51a and 51b, thereby enabling the maintenance cover portion 3b to be removed easily. Accordingly, removal operability is also improved (see
The following is an explanation of the operation of the superheated steam sterilization apparatus configured as stated above. First, the inspection lid 47 shown in
Next, grains are supplied from the supply chute 13 (see
If superheated steam is applied to grains directly from the superheated steam nozzle 7, the grains are sterilized only locally (at points) because superheated steam is applied from the superheated steam nozzle 7 having a small nozzle diameter. In contrast to this, when superheated steam supplied from the superheated steam nozzle 7 is temporarily stored in the superheated steam box 8 and thereafter applied from the steam outlet 9 set to an appropriate degree of opening, the grains are sterilized over a wide surface area (the steam outlet 9 has an opening area larger than that of the superheated steam nozzle 7 having a small nozzle diameter). Accordingly, it is possible to eliminate uneven application of superheated steam.
In addition, the degree of opening of the steam outlet 9 of each of the superheated steam boxes 8a to 8d can be adjusted by the opening-closing shutter 43. Therefore, if the degree of opening of the steam outlet 9 is set to fully open, it is also possible to sterilize grains containing a large number of bacteria (e.g. grains that seem to have a large number of bacteria grown thereon, for example, brown rice having been stored for a long period of time in a state of being mixed with paddy and chaff; chaff cannot be said to be germ-free but contains some microorganisms and bacteria). On the other hand, if the degree of opening is set to half-open, it is also possible to sterilize grains containing a small number of bacteria (e.g. polished and sorted grains obtained by completely removing paddy and chaff from brown rice; and relatively clean grains from which chaff has been removed) in an energy-conserving manner with a reduced supply of superheated steam.
Next, grains having passed through the area where the superheated steam boxes 8a to 8d are disposed are continuously discharged from the discharge port 12 while being agitating by the agitating member 5. The grains discharged from the discharge port 12 are supplied to the supply port 29 of the grain cooling part 20 through the rotary valve 31 (
When maintenance of the horizontal cylindrical part 3 is performed, first, nuts 52a and 52b are unfastened and removed respectively from a bolt 53a provided to project from a flange portion 3a1 of the base portion 3a of the horizontal cylindrical part 3 and a bolt 53b provided to project from the sidewall 41a of the superheated steam box 8. Thus, the operator can remove the maintenance cover portion 3b by holding the handles 51a and 51b attached thereto (see
As has been stated above, according to this embodiment, the superheated steam sterilization apparatus 1 includes: the horizontal cylindrical part 3 including the one end formed with the supply port 11 for supplying an object to be sterilized and the other end formed with the discharge port 12 for discharging a sterilized object; the rotating shaft part 6 rotatably disposed in the horizontal cylindrical part 3, and including the helical screw 4 configured to transfer the supplied object to be sterilized and the agitating member 5 including the plurality of agitating blades and configured to agitate the object to be sterilized; the plurality of superheated steam nozzles 7 disposed above the horizontal cylindrical part 3; the superheated steam box 8 disposed on the horizontal cylindrical part 3, divided into the plurality of sections along the axial direction, and configured to temporarily store superheated steam supplied from the superheated steam nozzles 7; and the steam outlet 9 for applying the superheated steam stored in the superheated steam box 8 to the object to be sterilized which is transferred and agitated in the horizontal cylindrical part 3. Accordingly, superheated steam from the superheated steam nozzles 7 can be temporarily stored in the superheated steam box 8 and then applied to the object to be sterilized from the steam outlet 9 set to an appropriate degree of opening. Consequently, the object to be sterilized can be sterilized by superheated steam applied over a widened area (the steam outlet 9 has an opening area larger than that of the superheated steam nozzle 7 having a small nozzle diameter). Because superheated steam is applied not locally but to a wide area, it is possible to eliminate uneven application of superheated steam to the object to be sterilized.
In addition, the horizontal cylindrical part 3 is formed to be splittable into the base portion 3a arcuately covering most part of the rotating shaft part 6 and the maintenance cover portion 3b removable from the base portion 3a and arcuately covering a part of the rotating shaft part 6. Accordingly, when the interior of the horizontal cylindrical part 3 is cleaned, or when the helical screw 4 and the agitating member 5 are repaired, the interior of the horizontal cylindrical part 3 can be opened simply by removing the maintenance cover portion 3b, which is exclusively used for maintenance, from the base portion 3a, and thus the rotating shaft part 6 is exposed. Consequently, very excellent maintainability is obtained.
Although some embodiments of the present invention have been described above, the described embodiments of the present invention are for the purpose of facilitating the understanding of the present invention and are not intended to limit the present invention. The present invention may, as a matter of course, be modified and improved without departing from the spirit thereof, and the present invention includes equivalents thereof. In addition, the structural elements described in the claims and the specification can be arbitrarily combined or omitted within a range in which the above-mentioned problems are at least partially solved, or within a range in which at least a part of the above-mentioned advantages is achieved. For example, the number of superheated steam nozzles 7 may be one. In this case, the arrangement may be such that one intermediate chamber is provided between the superheated steam nozzle 7 and the superheated steam boxes 8a to 8d, and that superheated steam introduced into the intermediate chamber from the superheated steam nozzle 7 is further introduced into the superheated steam boxes 8a to 8d through a plurality of holes formed in the intermediate chamber. Further, the superheated steam box 8 may be a single chamber having a plurality of steam outlets 9a to 9d.
The present invention is applicable to the field of superheated steam sterilization apparatus capable of continuously sterilizing a large amount of grain. For example, the present invention is also applicable as a sterilization apparatus (disinfection apparatus) for sterilizing paddy rice seeds (seed rice) against contagious diseases (rice blast, fool seedling disease, etc.) in addition to a sterilization apparatus for sterilizing brown rice obtained by hulling paddy before distribution.
Number | Date | Country | Kind |
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2015166400 | Aug 2015 | JP | national |
2015173884 | Sep 2015 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2016/074325 | 8/22/2016 | WO | 00 |