JP7763145B2 - Steam rice cooker and method for producing cooked rice - Google Patents

Description

Article 30, paragraph 2 of the Patent Act applies. Nakanishi Manufacturing Co., Ltd. disclosed the "steam rice cooking device and cooked rice manufacturing method" created by Takashi Ohno and others to Mitsuwa Co., Ltd. and Kawamura Burner Manufacturing Co., Ltd. during a rice cooking test conducted at the Rice Factory, Production Division of Mitsuwa Co., Ltd.

The present invention relates to a steam rice cooker and a method for producing cooked rice used in large quantities for school lunches, employee cafeterias, and other purposes.

One such device, described in Patent Document 1, is a steam rice cooker used in fields where large quantities of rice are cooked, such as in the lunch delivery business, food service companies, and the restaurant industry. The rice is soaked in water stored in the primary soaking section for a predetermined period of time, and after the primary soaking, it is stacked on the conveying surface of a mesh conveyor through which steam can pass. While the rice is being conveyed, steam is supplied from below the mesh conveyor to perform the primary steaming. After this primary steaming, the rice is placed in water at 89-95°C stored in a heated water tank in the secondary soaking section, where it is conveyed while undergoing the secondary soaking. The rice is then continuously transferred onto the conveyor, where steam is supplied for the secondary steaming.

Japanese Patent Application Publication No. 9-238837

The system described in Patent Document 1 is equipped with a hole puncher that punches holes in the polished rice stacked on the conveying surface of a mesh conveyor during the primary steaming process, and opens steam passage holes from above for the polished rice being transported by the mesh conveyor during the primary steaming process. The steam blown out from below the mesh conveyor is then made to pass easily through the steam passage holes through the stacked polished rice, thereby carrying out the primary steaming process.

However, during the primary steaming process, the white rice stacked on the transport surface of the mesh conveyor is not sticky and therefore easily crumbles. Even if multiple steam passage holes are drilled using a hole puncher, the rice still crumbles during transport, posing the problem of not being able to reliably perform the primary steaming of the white rice stacked on the transport surface of the mesh conveyor.

The present invention aims to provide a steam rice cooker and a method for producing cooked rice that can produce delicious rice through steam cooking.

In order to achieve the above object, the steam rice cooker of the present invention comprises:
a primary soaking unit having a primary soaking tank that stores soaking water for soaking the polished rice;
a primary steaming section that has a primary steaming conveyor that stacks the polished rice soaked in the soaking water in the primary soaking section on a conveying surface and conveys the polished rice downstream in the conveying direction, and supplies steam to the polished rice stacked on the conveying surface of the primary steaming conveyor;
a secondary soaking section that soaks the polished rice transported from the primary steaming section in soaking water stored in a secondary soaking tank while transporting the polished rice downstream in the transport direction;
The apparatus has a secondary steaming conveyor that stacks the polished rice soaked in the soaking water in the secondary soaking section on a conveying surface and conveys the polished rice downstream in the conveying direction, and a secondary steaming section that supplies steam to the polished rice stacked on the conveying surface of the secondary steaming conveyor to complete gelatinization of the polished rice that has been secondarily soaked,
On the upstream side of the primary steaming section in the direction of conveyance of white rice,
a polished rice supply opening for supplying the polished rice soaked in the primary soaking section in a stacked manner onto the conveying surface of the primary steaming conveyor;
a ridge forming plate that is provided in the polished rice supply opening and has at least a portion of its lower end formed into a mountain shape, thereby forming a vertically recessed valley portion at the top of a cross section in a direction perpendicular to the conveying direction of the polished rice supplied from the polished rice supply opening;
and
The steam is supplied from a first steam supply unit located below the conveying surface of the primary steaming conveyor, and is passed along the conveying surface of the primary steaming conveyor toward the polished rice, and the steam is caused to flow between the polished rice grains stacked on the conveying surface of the primary steaming conveyor, and the steam passes through the stacked polished rice while coming into contact with the polished rice, and is then released into the atmosphere from the valleys.

Further, the method for producing cooked rice of the present invention is
a first soaking step in which polished rice is soaked in soaking water for a predetermined time;
a primary steaming step in which the polished rice that has been subjected to the primary soaking step is stacked on a conveying surface of a conveyor and brought into contact with steam while being conveyed;
a second soaking step in which the polished rice that has been subjected to the first steaming step is placed in soaking water at a predetermined temperature and soaked for a predetermined time while being transported by a conveyor;
a secondary steaming step in which the polished rice that has been subjected to the secondary soaking step is stacked on a conveying surface of a conveyor and conveyed while being exposed to steam to complete gelatinization of the polished rice;
Including,
In the first steaming step,
The polished rice stacked on the conveying surface of the conveyor is shaped into a plurality of ridges that form valleys that are recessed in the vertical direction at the top of a cross section in a direction perpendicular to the conveying direction,
Steam is supplied from a first steam supply unit located below the conveying surface of the conveyor, and passed through the conveyor; the supplied steam flows between the polished rice grains stacked on the conveying surface of the conveyor; the steam passes through the stacked polished rice grains while coming into contact with the polished rice grains, and is released into the atmosphere from the valleys.

As explained above, the steam rice cooker and cooked rice manufacturing method of the present invention make it possible to produce delicious rice through steam cooking.

1 is a front view showing the overall configuration of a steam rice cooker according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of a front-end process section of the steam rice cooker. FIG. 2 is a block diagram showing the configuration of the primary immersion unit of the steam rice cooker. FIG. 2 is an enlarged perspective view showing the configuration of a ridge forming plate and its surroundings of the steam rice cooker. FIG. 2 is a perspective view showing the polygonal drum and its surrounding structure of the steam rice cooker. FIG. 4 is an enlarged perspective view showing the configuration of a plurality of vent holes in the first steam concentrating plate and openings in the second steam concentrating plate of the steam rice cooker. FIG. 2 is an enlarged perspective view showing the configuration of a first steam supply unit of the steam rice cooker. FIG. 3 is an enlarged plan view showing a connection portion between the chain and the net of the steam rice cooker. FIG. 2 is an enlarged perspective view showing a first superheated steam supply unit, a second steam supply unit, and a second superheated steam supply unit of the secondary steaming unit of the steam rice cooker. FIG. 2 is a block diagram showing the outlet section of the steam rice cooker. FIG. 1 is a step diagram showing a method for producing cooked rice. 10 is a cross-sectional view showing an outline of steam passing through a plurality of vent holes in the first steam concentrating plate and openings in the second steam concentrating plate from the start of the primary steaming step until a predetermined time. FIG. FIG. 10 is a cross-sectional view showing an overview of steam passing through the multiple vent holes of the first steam concentrating plate and the openings of the second steam concentrating plate after a predetermined time has elapsed since the start of the primary steaming step.

The first invention is
a primary soaking unit having a primary soaking tank that stores soaking water for soaking the polished rice;
a primary steaming section that has a primary steaming conveyor that stacks the polished rice soaked in the soaking water in the primary soaking section on a conveying surface and conveys the polished rice downstream in the conveying direction, and supplies steam to the polished rice stacked on the conveying surface of the primary steaming conveyor;
a secondary soaking section that soaks the polished rice transported from the primary steaming section in soaking water stored in a secondary soaking tank while transporting the polished rice downstream in the transport direction;
The apparatus has a secondary steaming conveyor that stacks the polished rice soaked in the soaking water in the secondary soaking section on a conveying surface and conveys the polished rice downstream in the conveying direction, and a secondary steaming section that supplies steam to the polished rice stacked on the conveying surface of the secondary steaming conveyor to complete gelatinization of the polished rice that has been secondarily soaked,
On the upstream side of the primary steaming section in the direction of conveyance of white rice,
a polished rice supply opening for supplying the polished rice soaked in the primary soaking section in a stacked manner onto the conveying surface of the primary steaming conveyor;
a ridge forming plate that is provided in the polished rice supply opening and has at least a portion of its lower end formed into a mountain shape, thereby forming a vertically recessed valley portion at the top of a cross section in a direction perpendicular to the conveying direction of the polished rice supplied from the polished rice supply opening;
and
This steam rice cooker is characterized by being configured such that steam is supplied from a first steam supply unit located below the conveying surface of the primary steaming conveyor, and is passed along the conveying surface of the primary steaming conveyor toward the polished rice, and steam is caused to flow between the polished rice grains stacked on the conveying surface of the primary steaming conveyor, and the steam passes through the stacked polished rice while coming into contact with the polished rice, and is then released into the atmosphere from the valleys.

This allows steam to flow smoothly between the rice grains stacked on the conveying surface of the primary steaming conveyor, passing through the stacked rice grains and dissipating into the atmosphere through the valleys. This allows the steam to come into effective contact with the rice grains, promoting gelatinization of the rice.

In particular, if valleys are not formed, steam does not flow smoothly between the grains of rice, and the rice may end up stacked on the conveying surface of the primary steaming conveyor to a thickness that makes it difficult for steam to pass through the rice and dissipate into the atmosphere. In such cases, by forming valleys, the steam that flows between the grains of rice can be dissipated into the atmosphere through the valleys. This ensures that primary steaming is carried out and delicious rice can be produced more reliably.

A second invention is the first invention,
This steam rice cooking device is characterized in that the first steam supply section of the primary steaming section is equipped with a steam supply opening for concentrating the flow of steam extending in the conveying direction so as to follow the valleys of the white rice.

This allows steam to be concentrated from the steam supply opening into the valleys between the rice grains, allowing more steam to flow between the grains.

A third invention is the second invention,
The first steaming section is
a water tank having a steam supply pipe disposed therein for generating steam;
a first steam concentrating plate that covers the water tank and has a vent hole through which steam generated in the water tank passes;
a second steam concentrating plate disposed above the first steam concentrating plate at a distance, the second steam concentrating plate having openings through which the steam passing through the vent holes further passes, the width of the passing steam being narrower than the width of the steam passing through the vent holes;
and
The steam rice cooker is characterized in that the steam supply opening is constituted by a vent hole provided in the first steam concentrating plate and an opening provided in the second steam concentrating plate.

This allows steam to be reliably supplied to the valleys with a simple configuration, more reliably dissipating the steam flowing between the rice grains into the atmosphere from the valleys.

The fourth invention is
a first soaking step in which polished rice is soaked in soaking water for a predetermined time;
a primary steaming step in which the polished rice that has been subjected to the primary soaking step is stacked on a conveying surface of a conveyor and brought into contact with steam while being conveyed;
a second soaking step in which the polished rice that has been subjected to the first steaming step is placed in soaking water at a predetermined temperature and soaked for a predetermined time while being transported by a conveyor;
a secondary steaming step in which the polished rice that has been subjected to the secondary soaking step is stacked on a conveying surface of a conveyor and conveyed while being exposed to steam to complete gelatinization of the polished rice;
Including,
In the first steaming step,
The polished rice stacked on the conveying surface of the conveyor is shaped into a plurality of ridges that form valleys that are recessed in the vertical direction at the top of a cross section in a direction perpendicular to the conveying direction,
This method for producing cooked rice is characterized in that steam is supplied from a first steam supply unit located below the conveying surface of the conveyor, the steam is passed through the conveyor, the supplied steam is allowed to flow between the polished rice grains stacked on the conveying surface of the conveyor, the steam is allowed to pass through the stacked polished rice grains while coming into contact with the polished rice, and the steam is released into the atmosphere from the valleys.

This allows steam to flow smoothly between the rice grains stacked on the conveyor's transport surface, passing through the rice grains and dissipating into the atmosphere through the valleys. This allows the steam to come into effective contact with the rice grains, promoting gelatinization of the rice.

In particular, if valleys are not formed, steam does not flow smoothly between the grains of rice, and the rice may end up stacked on the conveyor's transport surface to a thickness that makes it difficult for steam to pass through the rice and dissipate into the atmosphere. In such cases, by forming valleys, the steam that flows between the grains of rice can be dissipated into the atmosphere through the valleys. This ensures that the primary steaming step is carried out, making it possible to more reliably produce delicious rice.

A fifth aspect of the present invention is the fourth aspect of the present invention,
This is a method for producing cooked rice, characterized in that in the primary steaming step, steam from a first steam supply section is supplied from a steam supply opening extending along the valley portion.

This allows steam to be concentrated in the valleys between the grains of rice, allowing more steam to flow between the grains of rice.

(Embodiment 1)
(Overview of steam rice cooker)
First, the basic configuration of a steam rice cooker 1 according to a first embodiment of the present invention will be described with reference to the drawings.

As shown in FIGS. 1 to 3 and 10, the steam rice cooker 1 includes:
a front-end process section 10 that supplies stored white rice R (shown by dotted hatching in each drawing), washes the rice, and causes it to flow downstream;
a primary soaking section 20 in which the polished rice R washed in the pre-processing section 10 is soaked in primary soaking water W1 stored in a primary soaking tank 21 for a predetermined time;
The polished rice R soaked for a predetermined time in the primary soaking unit 20 is stored in a rice storage tank 33, and the polished rice R is stacked and supplied to a primary steaming conveyor (conveyor) 41 in a ridge forming unit 30.
a primary steaming section 40 that stacks and conveys the polished rice R supplied from the ridge forming section 30 on a conveying surface 41 a of a primary steaming conveyor 41, and supplies steam V to the polished rice R from a first steam supplying section 50 provided between the outward and return paths of the primary steaming conveyor 41;
a secondary soaking section 60 in which the white rice R steamed in the primary steaming section 40 flows into secondary soaking water W2 at a predetermined temperature stored in a secondary soaking tank 61, and is soaked for a predetermined time while being transported downstream;
a secondary steaming section 70 in which the polished rice R soaked in the secondary soaking section 60 is stacked and conveyed on a conveying surface 71a of a secondary steaming conveyor (conveyor) 71, and superheated steam V1, V3 and steam V2 are supplied from between the outbound and inbound paths of the secondary steaming conveyor 71 to complete the gelatinization (gelatinization) of the polished rice R;
a take-out section 115 that takes out the cooked rice R', which is white rice that has been gelatinized in the secondary steaming section 70, into a take-out container 117;
It is equipped with:

(Front process section)
As shown in FIG. 2, the front-end process section 10 includes:
A rice silo 11 that stores white rice R to be cooked by the steam rice cooking device 1 and outputs only the required amount of rice by a rice output device 12 located at the bottom;
The rice washer 14 uses air drawn by a blower 13 to transport the white rice R discharged from the rice silo 11 through a rice distribution pipe 16 in the previous process, and supplies clean water, i.e., rice washing water, to the delivered white rice R, stirring it to wash the white rice R.
a front-end pump 15 that uses the discharged clean water to move the white rice R washed by the rice washer 14 downstream through a front-end rice conveying pipe 17;
The rice washer 14 is provided with, for example, a spiral screw 14a inside.

(Primary immersion part)
As shown in FIG. 3, the primary immersion section 20 includes:
a primary soaking tank 21 that stores a predetermined amount of clean water, i.e., primary soaking water W1, and soaks the polished rice R washed by the rice washer 14 for a predetermined time;
A valve 22 is provided at the bottom of the primary soaking tank 21, and when opened, causes the white rice R that has been soaked for a predetermined time to flow into the primary soaking rice conveying pipe 23 together with the primary soaking water W1.
A primary submerged pump 24, which opens the valve 22 to allow the rice R flowing into the primary submerged rice transport pipe 23 to flow downstream by the discharged fresh water;
The configuration of the valve 22 is not particularly limited, and it may be opened and closed manually or automatically.

(ridge forming part)
As shown enlarged in FIGS. 1 and 4, the ridge forming portion 30 is
a receiving conveyor 31 that receives the polished rice R that has been soaked in the primary soaking section 20 and flowed through the primary soaking rice conveying pipe 23, and conveys the polished rice R downstream while separating the primary soaking water W1 from the polished rice R;
a rice storage tank 33 in which the polished rice R transported by the receiving conveyor 31 is dropped and stored;
a polished rice supply opening 34 provided at the bottom of the rice storage tank 33 and configured to supply polished rice R stored in the rice storage tank 33 to a conveying surface 41 a of a primary steaming conveyor 41 of the primary steaming section 40;
a ridge forming plate 35 that is provided in the polished rice supply opening 34 so as to be movable up and down by a drive mechanism 36, and that adjusts the amount of polished rice R that is stacked and supplied from the polished rice supply opening 34 to the primary steaming conveyor 41, and that forms peaks RM and valleys RV on top of the polished rice R that has been stacked and supplied;
(See FIG. 12).

The ridge-forming plate 35 is made, for example, from a stainless steel plate that has been cut and bent using a press or other process, and has multiple pointed valley-forming portions 35a that protrude downward and multiple ridge-forming portions 35b that are recessed upward. The inclination angle of the valley-forming portions 35a from the horizontal is preferably 5 to 40 degrees.

The drive mechanism 36 is configured to allow fine adjustment of the lower edge of the ridge forming plate 35 to an optimal vertical position, for example, using a handle 36a and a transmission mechanism 36b. The depth and width of the valley forming portions 35a and peak forming portions 35b on the ridge forming plate 35 can be set based on the width of the primary steaming conveyor 41, the feed speed, the stack height of the white rice R, etc. The number of ridges (raised portions, shown by imaginary lines in Figure 4) of the white rice R formed may be four, as in this embodiment, but the number is not particularly limited and can be any number greater than two.

As shown in Figure 1, the receiving conveyor 31, which is installed above the open-topped rice storage tank 33, is configured to rise from the upstream side to the downstream side. As a result, the white rice R discharged onto the receiving conveyor 31 from the discharge outlet 32 located upstream of the receiving conveyor 31 is transported and rises, and the primary soaking water W1 discharged onto the receiving conveyor 31 together with the white rice R flows toward the upstream side of the receiving conveyor 31 and is drained through the drain pipe 31a.

(Primary steaming section)
As shown in FIGS. 1, 4, and 5, the primary steaming section 40 includes:
a primary steaming conveyor 41 that stacks and conveys the polished rice R supplied from the ridge forming unit 30 on a conveying surface 41a (not shown in FIG. 5) while primarily steaming the polished rice R with steam;
a first steam supply unit 50 that is provided between the outward and return paths of the primary steaming conveyor 41 and supplies steam V to the polished rice R that is stacked and conveyed on the conveying surface 41 a of the primary steaming conveyor 41;
removable partition plates 48 (omitted in FIG. 4 and shown by imaginary lines in FIG. 5 ) that prevent the white rice R, which is stacked and transported on the transport surface 41 a of the primary steaming conveyor 41, from falling onto the floor of the facility from both sides of the primary steaming conveyor 41, which are in directions perpendicular to the transport direction;
It is equipped with:

Although not shown in detail, the partition plates 48 on both sides of the width are covered from above with lid members 49 (shown only in Figure 1) with handles to prevent steam V from escaping as much as possible. The partition plates 48 are made of plate members that have been embossed to create an uneven surface to prevent polished rice R from adhering, for example.

As shown in FIGS. 1 and 5, the primary steaming conveyor 41 includes:
A driven drum (drum) 45 having sprockets 45a, 45b coaxially attached to both ends thereof on the upstream side thereof;
Downstream of the drum 46, sprockets 46a and 46b are coaxially attached to both ends of the drum 46, which is rotated by a drive motor 46c.
A driven drum (drum) 47 that rotates below the polygonal drum 46;
It is equipped with:

The driven drum 45, polygonal drum 46, and driven drum 47 circulate an endless net 42 (shown in Figure 8). The net 42 is made of, for example, a flexible stainless steel net that is smaller than the grains of white rice R and has mesh or through-holes that allow steam to pass through.

Sprockets 45a, 45b, 46a, and 46b attached to both ends of the driven drum 45 and polygonal drum 46 drive endless chains 43 and 44, each made up of multiple links, in a circular motion.

The polygonal drum 46 rotates in synchronization with the sprockets 46a and 46b at both ends. For example, as shown in an enlarged partial view in Figure 8, the chains 43 and 44 are double-pitch chains with a pitch length L2 that is longer than normal.

As shown in Figure 5, the cross section of the polygonal drum 46 in a direction perpendicular to the axial direction is a polygon, for example a regular heptagon, and the length L1 of one side of the polygon is approximately equal to the pitch length L2 (shown in Figure 8) of the chains 43, 44. The cross-sectional shape may also be a regular pentagon, regular octagon, etc.

A net non-contact section 46d with a circular cross section perpendicular to the axial direction is provided between the polygonal drum 46 and the sprockets 46a, 46b at both ends. When the net 42 is driven in a circular motion, there are sections where the net 42 located on the polygonal drum 46 is driven in contact with the polygonal drum, and sections where the net 42 located on the net non-contact section 46d does not come into contact with the drum.

Furthermore, as shown in Figure 8, the widthwise ends of the net 42 are connected to the chains 43, 44 by connecting members 42a via ears 43a, 44a on the chains 43, 44. The ears 43a, 44a are located on the underside of the net 42 of the chains 43, 44, and are connected by inserting connecting members 42a, such as rivets, through the top of the net 42 and crimping them. As a result, when the chains 43, 44 are driven, the net 42 is also driven simultaneously. The chains 43, 44 suppress slippage and meandering when the net 42 is driven by the polygonal drum 46, achieving a stable conveying speed and eliminating the need for meandering adjustments.

(First steam supply unit)
As shown in FIGS. 5 to 7, the first steam supply unit 50 includes:
a water tank 51 having an open top for storing fresh water 51a;
a steam supply pipe 52 that allows steam supplied from a boiler installed in the facility to flow through a steam pipe 53 and dissipates the steam in fresh water 51a stored in a water tank 51;
a first steam concentrating plate 54 having a plurality of vent holes (steam supply openings) 54 a attached to close the open top of the water tank 51;
a second steam concentrating plate 55 provided between the first steam concentrating plate 54 and the outward path of the primary steam conveyor 41, the second steam concentrating plate 55 having openings (steam supply openings) 55 a for guiding the flow of steam V passing through a plurality of vent holes 54 a of the first steam concentrating plate 54;
It has.

As shown enlarged in Figure 7, for example, steam emitted from the steam supply pipe 52, which is made of a sparge pipe (silencer), heats the fresh water 51a stored in the water tank 51, thereby generating steam V with higher humidity than if steam were emitted directly from the steam supply pipe 52. This promotes gelatinization of the white rice R that is stacked and transported on the transport surface 41a of the primary steaming conveyor 41.

As shown enlarged in Figure 6, the multiple ventilation holes 54a on the first steam concentrating plate 54 are spaced closely together, for example, with a width centered at a position that divides the width of the primary steaming conveyor 41 into approximately four equal parts in the width direction perpendicular to the conveying direction, and with the length extending in the conveying direction. For example, the first steam concentrating plate 54 is made of a thin plate of SUS304 with a thickness of 1 mm, and the multiple ventilation holes 54a are punched in predetermined areas.

The second steam concentrating plate 55 has an opening 55a extending in the conveying direction through which steam V passes through the multiple ventilation holes 54a in the first steam concentrating plate 54, and the length of this opening 55a in the width direction perpendicular to the conveying direction is narrower than the width of the specified area in the first steam concentrating plate 54 where the multiple ventilation holes 54a are provided, in the direction perpendicular to the conveying direction.

The steam supply opening is made up of multiple ventilation holes 54a and openings 55a. The steam supply openings 54a and 55a are configured to extend along the valleys RV formed by the ridge forming unit 30 on top of the polished rice R stacked in the primary steaming step S20, which will be described later.

(Secondary immersion part)
As shown in FIG. 1, the secondary immersion section 60 includes:
a secondary soaking tank 61 for storing secondary soaking water W2 at a predetermined temperature supplied from a water heater provided in the facility where the steam rice cooker 1 is installed;
an endless scraper conveyor (conveyor) 62 provided in the secondary soaking tank 61, which conveys the polished rice R introduced into the secondary soaking tank 61 downstream in the secondary soaking water W2 by a conveying plate 68 that circulates in an upright position;
The conveying plate 68 is made of, for example, a plate member that has been embossed to have an uneven surface so that the polished rice R does not easily adhere to it.

Although detailed explanations are omitted, the scraper conveyor 62 has a pair of rotating shafts 65, 67 and a drive shaft 66. The base ends of numerous conveying plates 68 are connected to a pair of widthwise chains 63, 64 that are hung on these sprockets 65a, 65b, 66a, 66b, 67a, 67b. By rotating the drive shaft 66 at a predetermined speed, the conveying plates 68 move at the same speed, pushing and conveying the white rice R immersed in the secondary soaking water W2.

(Secondary steaming section)
As shown in FIGS. 1 and 9, the secondary steaming section 70 includes:
a secondary steaming conveyor 71 that stacks and conveys the polished rice R conveyed from the secondary soaking tank 61 of the secondary soaking section 60 on a conveying surface 71a, and secondarily steams the polished rice R with superheated steam V1, V3 and steam V2;
a first loosening blade 79 for loosening the polished rice R that is stacked and transported on the transport surface 71 a of the secondary steaming conveyor 71;
a first superheated steam supply unit 90 that is provided between the outward path and the return path of the secondary steaming conveyor 71 and that supplies superheated steam V1 to the polished rice R that is stacked and conveyed on the conveying surface 71 a of the secondary steaming conveyor 71;
a second steam supply unit 100 that is provided between the outward path and the return path of the secondary steaming conveyor 71 and that supplies steam V2 to the polished rice R that is stacked and conveyed on the conveying surface 71 a of the secondary steaming conveyor 71 downstream of the first superheated steam supply unit 90;
a second superheated steam supply unit 110 that is provided between the outward path and the return path of the secondary steaming conveyor 71 and that supplies superheated steam V3 to the polished rice R that is stacked and conveyed on the conveying surface 71 a of the secondary steaming conveyor 71 downstream of the second steam supply unit 100;
a removable partition plate 78 that prevents the white rice R, which is stacked and transported on the transport surface 71 a of the secondary steaming conveyor 71, from falling onto the floor of the facility from both sides of the secondary steaming conveyor 71 in directions perpendicular to the transport direction;
a second loosening blade 80 for loosening the steam-cooked white rice R' that is stacked and conveyed on the conveying surface 71a of the secondary steaming conveyor 71;
Although not shown in detail, the area surrounded by the partition plate 78 is covered with a lid member 81 having a handle.

As shown in FIGS. 1, 9, and 10, the secondary steaming conveyor 71 is
A driven drum (drum) 75 having sprockets 75a and 75b coaxially attached to both ends thereof on the upstream side thereof;
Downstream of the drum 76, sprockets 76a and 76b are coaxially attached to both ends of the drum 76, which is rotated by a drive motor 76c.
A driven drum (drum) 77 that rotates below the polygonal drum 76;
an endless net 72 driven in a circular manner by a driven drum 75, a polygonal drum 76, and a driven drum 77;
an endless chain 73, 74 made up of a plurality of links that are driven in a circular manner by sprockets 75a, 75b, 76a, 76b attached to both ends of a driven drum 75 and a polygonal drum 76;
The polygonal drum 76 rotates in synchronization with sprockets 76a and 76b at both ends.

Although not shown in detail, as shown simply in Figure 10, the secondary steaming conveyor 71 also has a polygonal drum 76, such as a regular heptagon, in cross section perpendicular to the axial direction, similar to the polygonal drum 46 shown in Figure 5, and the length L1 of one side of the polygon is configured to be approximately equal to the pitch length L2 of the chains 73, 74. Furthermore, between the polygonal drum 76 and the sprockets 76a, 76b at both ends, there is provided a net non-contact section 76d, which has a circular cross section perpendicular to the axial direction.

Also, as shown in parentheses in Figure 8, in the secondary steaming conveyor 71, the net 72 is connected to the chains 73, 74 by connecting members 72a via ears 73a, 74a provided on the chains 73, 74.

As shown in Figure 1, the first loosening blade 79, which has multiple rod-shaped blades 79a, is configured to loosen the white rice R scraped by the scraper conveyor 62 from the secondary soaking water W2 stored in the secondary soaking tank 61 of the secondary soaking section 60 while stacking and transporting it on the conveying surface 71a of the secondary steaming conveyor 71.

(First superheated steam supply section)
As shown in FIGS. 1 and 9, the first superheated steam supply unit 90 provided between the outward path and the return path of the secondary steam conveyor 71 is
a first superheated steam supply box 91 having an open top and provided between the outward and return paths of the secondary steaming conveyor 71;
a steam supply pipe 92 that dissipates steam supplied from a boiler installed in the facility via a steam pipe 94 downward;
a heater 93 for heating steam supplied from a steam supply pipe 92 to generate superheated steam V1;
It is equipped with:

(Second steam supply section)
As shown in FIGS. 1 and 9, the second steam supply unit 100 provided downstream of the first superheated steam supply unit 90 between the forward and return paths of the secondary steam conveyor 71 is
a water tank 101 having an open top for storing fresh water 101a;
a steam supply pipe 102 that supplies steam from a boiler installed in the facility through a steam pipe 103 and dissipates it in fresh water 101a stored in a water tank 101;
It has.

The steam emitted from the steam supply pipe 102 heats the fresh water 101a stored in the water tank 101, generating more humid steam V2. This promotes gelatinization of the polished rice R stacked on the conveying surface 71a of the secondary steaming conveyor 71.

(Second superheated steam supply section)
As shown in FIGS. 1 and 9, the second superheated steam supply unit 110 provided downstream of the second steam supply unit 100 between the forward and return paths of the secondary steam conveyor 71 is
a second superheated steam supply box 111 having an open top and provided between the outward and return paths of the secondary steaming conveyor 71;
a steam supply pipe 112 that dissipates steam downward, the steam being supplied from a boiler installed in the facility via a steam pipe 114;
a heater 113 for heating the steam supplied from the steam supply pipe 112 to generate superheated steam V3;
It is equipped with:

(Removal section)
Although detailed explanation will be omitted, as shown in Figure 10, the removal section 115 is equipped with a removal conveyor 116 that transports rice R' that has been loosened by a second loosening blade 80 having multiple rod-shaped blades 80a of the secondary steaming section 70 and stores it in a removal container 117.

(Outline of the method for producing cooked rice)
Next, a method for producing cooked rice using the steam rice cooker 1 will be described.

As shown in FIG. 11, the method for producing cooked rice is as follows:
A pre-process step S1 in which a predetermined amount of stored white rice R is discharged and sent, washed, and sent downstream;
a first soaking step S10 in which the polished rice R washed in the previous step S1 is soaked in the first soaking water W1 for a predetermined time;
a primary steaming step S20 in which the polished rice R soaked for a predetermined time in the primary soaking step S10 is stored, stacked and supplied onto the conveying surface 41a of the primary steaming conveyor 41, and steam V is supplied for a predetermined time to contact the polished rice R while being conveyed by the primary steaming conveyor 41;
a secondary soaking step S30 in which the polished rice R to which the steam V has been supplied for a predetermined time in the primary steaming step S20 is soaked for a predetermined time while being transported in secondary soaking water W2;
a secondary steaming step S40 in which the polished rice R soaked for a predetermined time in the secondary soaking step S30 is stacked and conveyed on the conveying surface 71a of the secondary steaming conveyor 71, and superheated steam V1, V3 and steam V2 are supplied for a predetermined time to contact the polished rice R and complete the gelatinization of the polished rice R;
A take-out step S50 of taking out the cooked rice R', which is the white rice that has been gelatinized in the secondary steaming step S40, into a take-out container 117;
It is equipped with:

Furthermore, the secondary steaming step S40 is
a first superheated steam supply step S41 in which superheated steam V1 is supplied to the polished rice R that is stacked and transported on the transport surface 71 a of the secondary steaming conveyor 71;
After the first superheated steam supplying step S41, a steam supplying step S42 is performed in which steam V2 is supplied to the polished rice R that is stacked and conveyed on the conveying surface 71a of the secondary steaming conveyor 71.
After the steam supplying step S42, a second superheated steam supplying step S43 is performed in which superheated steam V3 is supplied to the polished rice R that is stacked and conveyed on the conveying surface 71 a of the secondary steaming conveyor 71.
It is equipped with:

(Pre-process step)
The first pre-process step S1 will be described.

First, as shown in Figure 2, white rice R to be steam cooked in the steam rice cooker 1 of the present invention is discharged from the rice silo 11 by the rice discharge device 12. The discharged white rice R is transported by air sucked in by the blower 13 and sent to the rice washer 14 downstream through the upstream rice distribution pipe 16.

The white rice R sent to the rice washer 14 is washed by stirring it with the washing water supplied inside the rice washer 14 using the screw 14a. The washed white rice R is sent to the pre-process rice delivery pipe 17 together with the washing water, and is sent downstream together with the clean water discharged by the pre-process pump 15.

(First immersion step)
The primary immersion step S10, which follows the pre-process step S1, will now be described.

As shown in Figure 3, the white rice R sent together with the rice-washing water in the previous process step S1 is sent to the primary soaking tank 21.

The polished rice R sent to the primary soaking tank 21 is then dropped into the primary soaking water W1 stored in the primary soaking tank 21. The polished rice R dropped into the primary soaking water W1 stored in the primary soaking tank 21 is soaked for a predetermined time, for example, approximately 60 minutes.

After soaking for a predetermined time, the valve 22 at the bottom of the primary soaking tank 21 is opened, and the white rice R and primary soaking water W1 are sent by gravity to the primary soaking rice delivery pipe 23.

As shown in Figure 3, by opening the valve 22 at the bottom of the primary soaking tank 21, the white rice R and primary soaking water W1 are sent by gravity to the primary soaking rice feed pipe 23. The rice is then sent downstream by the force of the fresh water discharged by the primary soaking pump 24.

(First steaming step)
The primary steaming step S20, which follows the primary soaking step S10, will now be described.

As shown in Figures 1 and 4, polished rice R sent downstream by the primary submerged rice sending pipe 23 falls from the discharge outlet 32 onto the conveying surface of the receiving conveyor 31 located above the rice storage tank 33.

The receiving conveyor 31 transports the white rice R toward the upwardly inclined downstream side, and at the lower, upstream side of the receiving conveyor 31, the primary soaking water W1 and clean water that have flowed onto the conveying surface of the receiving conveyor 31 along with the white rice R are separated from the white rice R and drained into the drain pipe 31a.

After the primary soaking water W1 and clean water have been separated, the polished rice R falls from the downstream side of the receiving conveyor 31 into the rice storage tank 33. The polished rice R that falls into and is stored in the rice storage tank 33 is supplied in layers from the polished rice supply opening 34 at the bottom of the rice storage tank 33 onto the conveying surface 41a of the primary steaming conveyor 41.

The polished rice R supplied in a stack onto the conveying surface 41a of the primary steaming conveyor 41 is stacked in such a way that the cross section perpendicular to the conveying direction of the primary steaming conveyor 41 bulges upward to form a semi-cylindrical cross section. Then, the ridge-forming plate 35, which is provided in the polished rice supply opening 34 and can move up and down, forms peaks RM and valleys RV at the top of the polished rice R stacked so that the cross section is semi-cylindrical, as shown by the imaginary lines in Figure 4 and the bold lines in Figure 12, and the polished rice R is supplied in a stack onto the conveying surface 41a of the primary steaming conveyor 41.

The white rice R is stacked and supplied onto the conveying surface 41a of the primary steaming conveyor 41. As it is transported by the primary steaming conveyor 41, steam V is supplied to it from the opening 55a of the first steam supply unit 50, which is located between the outbound and return paths of the primary steaming conveyor 41.

The steam V supplied from the opening 55a of the first steam supply unit 50 flows between the polished rice R stacked on the conveying surface 41a of the primary steaming conveyor 41, comes into contact with the polished rice R, and supplies heat and moisture to the polished rice R. The polished rice R is then gelatinized, passes through the polished rice R stacked on the conveying surface 41a of the primary steaming conveyor 41, and is released into the atmosphere from above the polished rice R.

Steam V is supplied to the white rice R, which is stacked and transported on the transport surface 41a of the primary steaming conveyor 41, for a predetermined period of time, for example, approximately 10 minutes, and then the rice is dropped from the transport surface 41a of the primary steaming conveyor 41 into the downstream secondary soaking tank 61, as shown in Figure 1.

(Function and effect of ridge forming part)
In the primary steaming step S20, peaks RM and valleys RV are formed by the ridge forming plate 35 on the upper part of the polished rice R stacked on the conveying surface 41a of the primary steaming conveyor 41, forming the rice into a plurality of ridges. The effects of forming the peaks RM and valleys RV will be described below.

As shown in Figure 12, from the start of the primary steaming step S20 until a predetermined time has elapsed, the steam V supplied from the opening 55a into the white rice R passes through the white rice R stacked on the conveying surface 41a in a generally straight line toward the valleys RV, and is dissipated primarily from the bottom of the valleys RV into the atmosphere.

Then, of the white rice R stacked on the conveying surface 41a, the white rice R between the point where it comes into contact with the conveying surface 41a above the multiple air vents 54a in the first steam concentrating plate 54 and the openings 55a in the second steam concentrating plate 55, and the bottom of the valley RV, can be intensively gelatinized and swollen.

Steam V passing through the concentrated gelatinized and swollen white rice R gradually gelatinizes and swells the white rice R adjacent to the area it passes through. The swollen white rice R widens the gaps between the white rice grains R, expanding the areas through which steam V can pass.

As shown in Figure 13, after a predetermined time has elapsed since the start of the primary steaming step S20, steam V can pass through the entire white rice R stacked on the conveying surface 41a in a cross section perpendicular to the conveying direction of the primary steaming conveyor 41.

The steam V that passes through the entire white rice R stacked on the conveying surface 41a spreads throughout the white rice R in the cross section perpendicular to the conveying direction of the primary steaming conveyor 41, and is released into the atmosphere from the entire upper part of the white rice R. This allows the white rice R stacked on the conveying surface 41a to be evenly gelatinized in the cross section perpendicular to the conveying direction of the primary steaming conveyor 41.

Previously, when the thickness of the white rice stacked on the conveying surface of the primary steaming conveyor was thick in the vertical direction from the top edge to the conveying surface, the steam supplied from the steam supply unit would not pass through the white rice and would escape to the side of the primary steaming conveyor, making it impossible to reliably gelatinize the white rice.

In the present invention, the vertical thickness from the bottom of the valley portion RV to the conveying surface 41a of the primary steaming conveyor 41 is set to a thickness L3 that allows steam V to pass through. This allows steam V to pass through the white rice R even if the white rice R stacked on the conveying surface 41a is thick in the vertical direction, and enables gelatinization of the white rice R.

Then, after a predetermined time has elapsed since the start of the primary steaming step S20, steam V passes through the entire white rice R stacked on the conveying surface 41a in a cross section perpendicular to the conveying direction of the primary steaming conveyor 41, enabling the entire white rice R to be gelatinized.

In the steam rice cooker 1 described in this embodiment, for example, the vertical thickness L3 from the bottom of the valley portion RV to the conveying surface 41a of the primary steaming conveyor 41 is approximately 140 mm. This thickness L3 is preferably adjusted according to the variety, quality, moisture content, etc. of the white rice R.

Furthermore, as shown in Figure 13, after a predetermined time has elapsed since the start of the primary steaming step S20, the white rice R stacked on the conveying surface 41a swells, and the overall thickness of the white rice R increases in a cross section perpendicular to the conveying direction of the primary steaming conveyor 41, changing from thickness L3 to thickness L4, which is thicker than thickness L3, and the vertical height of the recessed portion of the valley RV decreases.

This allows the steam V that passes through the polished rice R between the point where it comes into contact with the conveying surface 41a located above the multiple vent holes 54a in the first steam concentrating plate 54 and the openings 55a in the second steam concentrating plate 55, and the bottom of the valley RV, to remain in the polished rice R for a longer period of time and disperse throughout the polished rice R, enabling a larger amount of polished rice R to be gelatinized.

The specified time required for steam V to spread throughout the entire mass of white rice R stacked on the conveying surface 41a in a cross section perpendicular to the conveying direction of the primary steaming conveyor 41 varies depending on the variety, quality, moisture content, and thicknesses L3 and L4 of the white rice R, but it is preferable to set the time as short as possible to promote gelatinization of the white rice R.

(Effect of polygonal drum)
Generally, when a chain is driven using a sprocket, the radius from the center of the rotation axis differs between the sprockets at both ends of each link of the chain and the middle of each link, and this causes the chain's driving speed to fluctuate each time the sprocket rotates a certain angle. This is particularly noticeable when the sprocket has a small number of teeth.

Furthermore, because the space within the facility in which the steam rice cooker 1 of this embodiment is installed is limited, it is necessary to make the configuration of the steam rice cooker 1 as small as possible. Therefore, it is also necessary to make the configuration of the primary steaming section 40 as small as possible, which necessitates making the sprockets 45a, 45b, 46a, and 46b of the primary steaming conveyor 41 as small as possible.

In particular, as shown in Figure 1, downstream of the conveyor that transports white rice R, the conveyor for the next process can be positioned below the discharge position of the white rice R with a small difference in height between the conveyor transport surfaces on the upstream and downstream sides, ensuring reliable transport of the white rice R to the next process.

Even in the steam rice cooker 1 of this embodiment, the sprockets 45a, 45b, 46a, and 46b must be as small as possible, so the radius from the center of the rotation axis differs between the ends and middle parts of each link of the chains 43 and 44, and there is a risk that the speed at which the chains 43 and 44 circulate will fluctuate each time the sprockets 45a, 45b, 46a, and 46b rotate a predetermined angle.

The chains 43, 44 and the net 42 are connected by connecting members 42a at the lugs 43a, 44a located in the middle of each link of the chains 43, 44. The chains 43, 44 are driven by sprockets 46a, 46b, and the radius from the center of the rotation axis is different between the portions of each link of the chains 43, 44 that are hooked onto the sprockets 46a, 46b at both ends and the middle portions of each link.

On the other hand, when the net 42 is driven by a circular drum, its radius from the center of the rotation axis is constant. When driven by a circular drum, the chains 43, 44 and the net 42 have different radii from the center of the rotation axis, which places excessive tension on the parts connecting the chains 43, 44 and the net 42 with the connecting members 42a, causing distortion in the circulating net 42.

In the present invention, as shown in Figures 5 and 8, the length L1 of one side of the polygon of the polygonal drum 46, which is provided downstream in the conveying direction of the white rice R on the primary steaming conveyor 41, is set to be approximately equal to the pitch length L2 of the chains 43, 44. Note that "approximately equal" means that there may be a difference greater than the design tolerance, for example, a difference of approximately ±1 to 3 mm.

The size of the cross section of the polygonal drum 46 in a direction perpendicular to the axial direction should be such that the length L1 of one side of the polygonal drum 46 is approximately equal to the pitch length L2 of the chains 43, 44, and the size of the circle circumscribed by the cross section of the polygonal drum 46 in a direction perpendicular to the axial direction should be approximately equal to the pitch circle diameter of the sprockets 46a, 46b.

This allows the net 42 to be driven in a polygonal shape, with a radius from the center of the rotation axis that is approximately equal to that of the chains 43 and 44. The circulation speed of the net 42 can then be intentionally varied in accordance with the fluctuations in the circulation speed of the chains 43 and 44 and their timing.

Furthermore, a net non-contact section 46d with a circular cross section perpendicular to the axial direction is provided between the polygonal drum 46 and the sprockets 46a, 46b at both ends. This prevents the net 42 located at the net non-contact section 46d from contacting the drum, and even if there is a difference between the length L1 of one side of the polygonal drum 46 and the pitch length L2 of the chains 43, 44, the tension applied to the section connecting the chains 43, 44 and the net 42 with the connecting member 42a can be released.

In this way, distortion of the net 42 at the points where the chains 43, 44 and the net 42 are connected by the connecting members 42a is suppressed, thereby extending the life of the net 42 and, ultimately, the life of the steam rice cooker 1.

(Actions and Effects of the First Steam Concentrating Plate and the Second Steam Concentrating Plate)
6 and 12, the flow of steam V generated in the first steam supply unit 50 can be concentrated in the width direction perpendicular to the conveying direction by the plurality of vent holes 54a in the first steam concentrating plate 54. Furthermore, the openings 55a in the second steam concentrating plate 55 can further concentrate the flow of steam V in the width direction perpendicular to the conveying direction.

In this way, the steam V generated from almost the entire surface of the fresh water 51a stored in the water tank 51 can be concentrated in the width direction perpendicular to the conveyance direction with a simple configuration simply by passing it through the two-tiered steam supply openings 54a, 55a. The concentrated flow of steam V is then sprayed onto the net 42 located directly below the valleys RV formed at the top of the white rice R being conveyed in a stack on the conveyance surface 41a of the primary steaming conveyor 41.

This allows more steam V to flow into and pass through the white rice R that is stacked and transported on the transport surface 41a of the primary steaming conveyor 41, allowing steam V to be supplied to the white rice R more effectively.

(Second immersion step)
The secondary soaking step S30, which follows the primary steaming step S20, will now be described.

As shown by the dashed line in Figure 1, the polished rice R that has completed the primary steaming step S20 is transported by the primary steaming conveyor 41 to the secondary soaking tank 61. The polished rice R is soaked for a predetermined time, for example, approximately 8 minutes, in the secondary soaking water W2 stored in the secondary soaking tank 61 and kept at a predetermined temperature, for example, 91 to 95 degrees C, while being transported downstream by the scraper conveyor 62.

After the white rice R in the secondary soaking water W2 stored in the secondary soaking tank 61 is soaked for a predetermined time, it is scraped out of the secondary soaking tank 61 by the scraper conveyor 62 and transported onto the conveying surface 71a of the secondary steaming conveyor 71 in the secondary steaming section 70, where it is stacked.

(Second steaming step)
The secondary steaming step S40, which follows the secondary soaking step S30, will now be described. The secondary steaming step S40 includes a first superheated steam supplying step S41, a steam supplying step S42, and a second superheated steam supplying step S43.

(First superheated steam supply step)
First, the first superheated steam supply step S41, which is the first step of the secondary steaming step S40, will be described.

As shown in Figure 1, the white rice R is intermittently scraped out of the secondary soaking tank 61 and piled up on the conveying surface 71a of the secondary steaming conveyor 71. While being transported by the secondary steaming conveyor 71, it is loosened by the rotating first loosening blade 79.

This makes it possible to make the height of the upper surface of the white rice R stacked and transported on the transport surface 71a of the secondary steaming conveyor 71 as uniform as possible. Furthermore, when the superheated steam V1, V3, and steam V2 supplied from between the outbound and inbound paths of the secondary steaming conveyor 71 is supplied to the white rice R stacked on the transport surface 71a of the secondary steaming conveyor 71, the superheated steam V1, V3, and steam V2 are supplied to the white rice R as uniformly as possible and brought into contact with the white rice R, allowing for even gelatinization of the white rice R.

Furthermore, by loosening the white rice R with the rotating first loosening blade 79, excess moisture adhering to the surface of the white rice R can be evaporated, and more gaps can be created between the white rice R, making it easier for superheated steam V1, V3 and steam V2 to pass through the white rice R, accelerating the gelatinization of the white rice R.

After being loosened by the first loosening blade 79, the white rice R is stacked and transported on the transport surface 71a of the secondary steaming conveyor 71. Superheated steam V1 is supplied to the white rice R from the first superheated steam supply unit 90, which is installed between the outbound and return paths of the secondary steaming conveyor 71.

Specifically, as shown in Figures 1 and 9, steam supplied from the boiler is dispersed downward from the steam supply pipe 92, and the steam supplied from this steam supply pipe 92 is heated by the heater 93 to become superheated steam V1, which is then supplied.

The superheated steam V1 supplied from the first superheated steam supply unit 90 evaporates the moisture adhering to the surface of the white rice R and dissipates it into the atmosphere. This heats the white rice R while evaporating the moisture adhering to the surface of the white rice R, and also evaporates the moisture inside the white rice R, forming multiple cavities on the surface of the white rice R.

(Steam supply step)
Next, the steam supplying step S42 performed after the first superheated steam supplying step S41 in the secondary steaming step S40 will be described.

As shown in Figures 1 and 9, after the first superheated steam supply step S41, the white rice R is stacked and transported on the transport surface 71a of the secondary steaming conveyor 71. Highly humid steam V2 is supplied to the white rice R from the second steam supply unit 100, which is located between the outbound and inbound paths of the secondary steaming conveyor 71, and brought into contact with the white rice R.

Specifically, the second steam supply unit 100 injects steam from the boiler downward from the steam supply pipe 102, evaporating the water stored in the water tank 101 and generating steam V2 at approximately 100 degrees C.

This makes it possible to supply steam V2 into the cavity formed on the surface of the white rice R in the first superheated steam supply step S41, allowing the steam V2 to reach the inside of the white rice R, producing truly delicious rice that is gelatinized all the way to the core.

(Second superheated steam supply step)
In the secondary steaming step S40, the second superheated steam supplying step S43 performed after the steam supplying step S42 will be described.

As shown in Figures 1 and 9, superheated steam V3 is supplied from a second superheated steam supply unit 110 installed between the outbound and inbound paths of the secondary steaming conveyor 71 to contact the white rice R that is stacked and transported on the transport surface 71a of the secondary steaming conveyor 71 after the steam supply step S42 has been completed.

This allows the white rice R to be heated while the excess moisture adhering to the surface of the white rice R in the second steam supply unit 100 is evaporated by the superheated steam V3 supplied by the second superheated steam supply unit 110. This prevents the surface of the white rice R from becoming soggy due to the excess moisture adhering to the rice, and allows the rice R to maintain a moderate level of moisture, completing the gelatinization of the rice R.

The steam V2 from the second steam supply unit 100 has a lower temperature than the superheated steam V1 and V3, and generates a larger amount of steam per unit time than the superheated steam V1 and V3.

As shown in Figures 1 and 9, superheated steam V3 is supplied from the second superheated steam supply unit 110 to the white rice R stacked on the conveying surface 71a of the secondary steaming conveyor 71, and then the cooked rice R', which is white rice that has completed gelatinization, is loosened by the rotating second loosening blade 80.

This allows air to be absorbed into the rice R' stacked and transported on the transport surface 71a of the secondary steaming conveyor 71, facilitating the evaporation of excess moisture on the surface of the rice R', resulting in the production of even more delicious rice R'.

The secondary steaming step S40 consists of three steps: a first superheated steam supply step S41, a steam supply step S42, and a second superheated steam supply step S43, which are carried out over a predetermined time, for example, approximately 15 minutes. The predetermined time for the secondary steaming step S40 varies depending on the amount, variety, quality, moisture content, etc. of the white rice R stacked on the conveying surface 71a of the secondary steaming conveyor 71.

In the first superheated steam supply step S41 and the second superheated steam supply step S43 that make up the secondary steaming step S40, the temperature of the superheated steam V1, V3 supplied to the white rice R is set to a predetermined temperature, for example, between 100°C and 120°C.

This prevents discoloration of the white rice R due to the heat being applied to the white rice R being too high. Note that the second superheated steam supply step S43 is not necessarily required, and the process may proceed from the steam supply step S42 to the removal step S50.

(Effect of polygonal drum)
Similar to the configuration of the primary steaming conveyor 41 in the primary steaming section 40, the secondary steaming conveyor 71 in the secondary steaming section 70 drives a net 72 in a circulating manner using a driven drum 75, a polygonal drum 76, and a driven drum 77. The net 72 is connected to chains 73 and 74 by connecting members 72a on both sides of the conveying direction of the white rice R, and the net 72 is driven in a circulating manner in conjunction with the chains 73 and 74.

As a result, the secondary steaming conveyor 71, which is driven in a circular motion in the secondary steaming step S40, also achieves the same effects as those described in the primary steaming step S20. In other words, the net 72 can be driven in a polygonal shape, and the radius from the center of the rotation axis can be made approximately equal to that of the chains 73 and 74. The circulation speed of the net 72 can then be intentionally varied in accordance with the fluctuations in the circular driving speed of the chains 73 and 74 and their timing, thereby suppressing distortion of the net 72 and extending the life of the net 72 and, ultimately, the life of the steam rice cooker 1.

(Removal step)
Finally, the removal step S50, which is performed after the secondary steaming step S40, will be described.

As shown in Figure 10, the rice R', which is white rice that has completed gelatinization in the secondary steaming step S40, is taken out and transported downstream on the conveyor 116. The rice R' is then dropped into a take-out container 117 installed downstream and stored there.

(Other embodiments)
The present invention may be configured as follows in relation to the above embodiment.

In other words, although the primary steaming conveyor 41 and secondary steaming conveyor 71 have been described as net conveyors that circulate nets 42, 72, they may also be configured as belt conveyors that circulate belts, as long as they are capable of passing steam V, V2 and superheated steam V1, V3 and conveying polished rice R in layers on the conveying surfaces 41a, 71a.

Furthermore, the steam rice cooker 1 described in this embodiment is a standard configuration, and any component may be omitted, added, or replaced as long as it is configured to be able to steam cook white rice R.

Furthermore, in this embodiment, the rice to be steam-cooked is described as white rice R, but it may also be brown rice or other grains that can be cooked using heat and moisture.

Although detailed explanations are omitted in the embodiment, each component in the steam rice cooker 1 is controlled by a control panel (not shown), and this control panel may be physically configured in any way as long as it controls the steam rice cooker 1. For example, the control panel may use software (programs), such as a microcomputer or programmable logic controller (PLC). Alternatively, the control panel may be implemented by combining hardware (circuit components).

The above embodiments are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or uses.

1 Steam rice cooking device 10 Pre-process section 11 Rice silo 12 Rice discharge device 13 Blower 14 Rice washer 14a Screw 15 Pre-process pump 16 Pre-process rice distribution pipe 17 Pre-process rice transport pipe 20 Primary soaking section 21 Primary soaking tank 22 Valve 23 Primary soaking rice transport pipe 24 Primary soaking pump 30 Ridge forming section 31 Receiving conveyor 31a Drainage pipe 32 Discharge outlet 33 Rice storage tank 34 Opening for supplying white rice 35 Ridge forming plate 35a Valley forming section 35b Mountain forming section 36 Drive mechanism 36a Handle 36b Transmission mechanism 40 Primary steaming section 41 Primary steaming conveyor (conveyor)
41a Conveying surface 42 Net 42a Connecting member 43 Chain 43a Ear portion 44 Chain 44a Ear portion 45 Driven drum (drum)
45a Sprocket 45b Sprocket 46 Polygonal drum (drum)
46a Sprocket 46b Sprocket 46c Drive motor 46d Net non-contact portion 47 Driven drum (drum)
48 Partition plate 49 Lid member 50 First steam supply unit 51 Water tank 51a Fresh water 52 Steam supply pipe 53 Steam pipe 54 First steam concentration plate 54a Multiple vent holes (steam supply openings)
55 Second steam concentration plate 55a Opening (steam supply opening)
60 Secondary immersion section 61 Secondary immersion tank 62 Scraper conveyor (conveyor)
63 Chain 64 Chain 65 Rotating shaft 65a Sprocket 65b Sprocket 66 Drive shaft 66a Sprocket 66b Sprocket 67 Rotating shaft 67a Sprocket 67b Sprocket 68 Conveyor plate 70 Secondary steaming section 71 Secondary steaming conveyor (conveyor)
71a Conveying surface 72 Net 72a Connecting member 73 Chain 73a Ear portion 74 Chain 74a Ear portion 75 Driven drum (drum)
75a Sprocket 75b Sprocket 76 Polygonal drum (drum)
76a Sprocket 76b Sprocket 76c Drive motor 76d Net non-contact part 77 Driven drum (drum)
78 Partition plate 79 First loosening blade 79a Blade 80 Second loosening blade 80a Blade 81 Lid member 90 First superheated steam supply unit 91 First superheated steam supply box 92 Steam supply pipe 93 Heater 94 Steam pipe 100 Second steam supply unit 101 Water tank 101a Fresh water 102 Steam supply pipe 103 Steam pipe 110 Second superheated steam supply unit 111 Second superheated steam supply box 112 Steam supply pipe 113 Heater 114 Steam pipe 115 Removal unit 116 Removal conveyor 117 Removal container S1 Pre-process step S10 Primary soaking step S20 Primary steaming step S30 Second soaking step S40 Second steaming step S41 First superheated steam supply step S42 Steam supply step S43 Second superheated steam supply step S50 Removal step

L1 Length of one side of polygonal drum L2 Chain pitch length L3 Thickness L4 Thickness R White rice RM Peak RV Valley R' Rice V Steam V1 Superheated steam V2 Steam V3 Superheated steam W1 Primary soaking water W2 Secondary soaking water

Claims (5)

a primary soaking unit having a primary soaking tank that stores soaking water for soaking the polished rice;
a primary steaming section that has a primary steaming conveyor that stacks the polished rice soaked in the soaking water in the primary soaking section on a conveying surface and conveys the polished rice downstream in the conveying direction, and supplies steam to the polished rice stacked on the conveying surface of the primary steaming conveyor;
a secondary soaking section that soaks the polished rice transported from the primary steaming section in soaking water stored in a secondary soaking tank while transporting the polished rice downstream in the transport direction;
The apparatus has a secondary steaming conveyor that stacks the polished rice soaked in the soaking water in the secondary soaking section on a conveying surface and conveys the polished rice downstream in the conveying direction, and a secondary steaming section that supplies steam to the polished rice stacked on the conveying surface of the secondary steaming conveyor to complete gelatinization of the polished rice that has been secondarily soaked,
On the upstream side of the primary steaming section in the direction of conveyance of white rice,
a polished rice supply opening for supplying the polished rice soaked in the primary soaking section in a stacked manner onto the conveying surface of the primary steaming conveyor;
a ridge forming plate that is provided in the polished rice supply opening and has at least a portion of its lower end formed into a mountain shape, thereby forming a vertically recessed valley portion at the top of a cross section in a direction perpendicular to the conveying direction of the polished rice supplied from the polished rice supply opening;
and
This steam rice cooker is configured to supply steam from a first steam supply unit located below the conveying surface of the primary steaming conveyor, pass the steam along the conveying surface of the primary steaming conveyor toward the polished rice, allow the steam to flow between the polished rice grains stacked on the conveying surface of the primary steaming conveyor, and allow the steam to pass through the stacked polished rice while coming into contact with the polished rice, and then dissipate from the valleys into the atmosphere. The steam rice cooker according to claim 1, wherein the first steam supply section of the primary steaming section is provided with a steam supply opening for concentrating the flow of steam extending in the conveying direction so as to follow the valleys of the white rice. The first steaming section is
a water tank having a steam supply pipe disposed therein for generating steam;
a first steam concentrating plate that covers the water tank and has a vent hole through which steam generated in the water tank passes;
a second steam concentrating plate disposed above the first steam concentrating plate at a distance, the second steam concentrating plate having openings through which the steam passing through the vent holes further passes, the width of the passing steam being narrower than the width of the steam passing through the vent holes;
and
3. The steam rice cooker according to claim 2, wherein the steam supply opening is constituted by a vent hole in the first steam concentrating plate and an opening in the second steam concentrating plate. a first soaking step in which polished rice is soaked in soaking water for a predetermined time;
a primary steaming step in which the polished rice that has been subjected to the primary soaking step is stacked on a conveying surface of a conveyor and brought into contact with steam while being conveyed;
a second soaking step in which the polished rice that has been subjected to the first steaming step is placed in soaking water at a predetermined temperature and soaked for a predetermined time while being transported by a conveyor;
a secondary steaming step in which the polished rice that has been subjected to the secondary soaking step is stacked on a conveying surface of a conveyor and conveyed while being exposed to steam to complete gelatinization of the polished rice;
Including,
In the first steaming step,
The polished rice stacked on the conveying surface of the conveyor is shaped into a plurality of ridges that form valleys that are recessed in the vertical direction at the top of a cross section in a direction perpendicular to the conveying direction,
A method for producing cooked rice, characterized in that steam is supplied from a first steam supply unit located below the conveying surface of the conveyor, the steam is passed through the conveyor, the supplied steam is allowed to flow between the polished rice grains stacked on the conveying surface of the conveyor, the steam is allowed to pass through the stacked polished rice grains while coming into contact with the polished rice, and the steam is released into the atmosphere from the valleys. 5. The method for producing cooked rice according to claim 4, wherein in the primary steaming step, steam from the first steam supply unit is supplied from a steam supply opening extending along the valley portion.