JPS63267243A - Supply of steam for heating food and device therefor - Google Patents

Abstract

PURPOSE:To obtain steam for heating foods, having proper humidity, by jetting high-pressure steam from a boiler from a specific nozzle into a tank, by adsorbing a heavy metal of antiscales on water, changing the high-pressure steam into low-pressure steam and separating excess water in a steam separating chamber. CONSTITUTION:High-pressure steam from a boiler 1 is jetted from a specific nozzle 9 in a steam supply pipe 8 connected to the top of a tank 7 to which water is fed and a heavy metal, etc., of antiscales admixed during evaporation in the boiler 1 are adsorbed on water in the tank 7. Simultaneously the high- pressure steam jetted to the tank 7 is changed into low-pressure steam. Then the low-pressure steam is introduced to a steam separating chamber 34 equipped with a barrier plate 36 to obstruct the flow and excess water is separated by contact with the barrier plate 36 in the separating chamber 34. Then saturated steam having proper humidity at <=110 deg.C is fed to a food heating means 38.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for supplying steam for heating food by heating and processing food using steam heat, and a steam supply device for the same. Japanese sweets, sekihan,
Foods called steamed foods (H-processed) such as steamed buns, puddings, and cupcakes, meat foods such as ham and sausage, and kamaboko.

It is widely used in the production of seafood paste products such as hampen.

[Conventional technology]

When steaming food using steam heat, in the old days, a steamer with food stored in it was placed over a pot, the pot was heated, the water in the pot evaporated, and the steam generated was used to steam the food inside the steamer. However, in recent years, steam obtained from high-pressure steam generators such as boilers has been increasingly used in order to be adaptable to mass production methods using factory production. .

Compared to the traditional method of using steam obtained by heating a pot for food steaming, the method of using steam obtained from a boiler has a lower rate of wasteful loss of the heating heat source and the obtained steam energy. It is economical and easy to operate, as it is easy to control the occurrence of

[Problem that the invention seeks to solve]

However, it is unreasonable to directly use the steam obtained from a boiler for food manufacturing and processing.
As a result, this causes several problems in product quality.

The first problem is that the steam obtained by the boiler is saturated steam, which is generally superheated steam with a gauge pressure of 5 to 7 kg/dG and a saturation temperature of 158 to 169 degrees Celsius. The temperature is too high to be used as it is for steaming, so this steam is removed by a pressure reducing valve at a temperature of 1 to 2 k that does not interfere with the continuous operation of the boiler.
It cannot be used unless it is supplied into a food steaming apparatus under reduced pressure and temperature to about 130°C and a saturation temperature of about 130°C. A large amount of drain is generated from the steam passing around the pressure-reduced valve, and a large-diameter pressure-reducing valve is required in terms of efficiency (no energy savings) and flow rate restrictions.

In general, when processing products under these conditions during food manufacturing, it is better to have a certain amount of steam pressure, because the flow rate of steam passing around and inside the product can be accelerated, so the processing time can be shortened. It is believed that good quality can be obtained.

However, in reality, using steam at a high temperature of 100°C or higher for steaming food products may result in
This causes changes in properties such as surface burns, scorching, and dryness, which changes the thermal conductivity and moisture permeability of the affected area, which later has undesirable effects on quality conditions such as uneven spots on the product. There is a problem.

Now, if we think about how the steaming process of food causes changes in physical properties in terms of thermal energy,
The supplied steam wraps around the food as thermal energy,
The moisture generated by heat exchange with the food forms a film on the surface of the food, and the steam as thermal energy that continues to be applied sequentially conducts heat to the inside of the food through this moisture film, raising the temperature of the food. It is a continuous movement.

In this case, if the temperature of the steam heat is high, moisture on the surface of the food will easily conduct heat into the food.

In other words, there is no need to spray high-temperature, high-pressure steam on anything as long as the temperature is right so that the steam can surround the food and raise its temperature. In addition, high temperature
When high-pressure steam is blown onto food, even though a moisture film with high thermal conductivity is formed on the surface during initial heating, water re-evaporates from the surface of the food, and due to the high pressure, the flow rate increases and the food This causes the surface to dry and releases thermal energy to the outside, resulting in large heat loss and greatly impairing economic efficiency. Conversely, heat is no longer transmitted to the center of the food, creating a large temperature difference between the heat on the surface of the food and the internal heat, making it impossible to obtain a uniform food, resulting in a very poor taste and significantly reduced shelf life. This may cause problems such as shortening the length.

On the other hand, no matter how much you try to reduce the pressure of steam produced by a general-purpose boiler using a pressure reducing valve, the boiler mechanism itself is originally intended to obtain high-temperature, high-pressure steam of about 5 to 7 kg/ctA G. The range in which the pressure can be reduced is at most about 2 to 3 kg/cnlG, and as mentioned above, the range is 0, 1 to 0, which is suitable for steaming food.
Continuously obtaining steam at a reduced pressure of about 4 kg/ciG is difficult in terms of boiler operation adjustment, and this general-purpose boiler has a pressure that cannot be used for equipment supplied to other industrial facilities ( Commonly known as 2-3 kg/cr
(used in AG) has the problem of not being able to operate.

Furthermore, the second problem that arises when steam obtained from a boiler is used for food manufacturing and processing is that can cleaning agents added to boiler water to protect the boiler body mix into the steam. This poses a significant problem to food quality,
It impairs the sense of taste.

As is well known, the water injected into the boiler is treated with a deoxidizing can cleaning agent that turns hard water into soft water to prevent deterioration of iron heat exchangers and prevent scale buildup. The agent is usually highly alkaline water with a pH of about PHII to 13, and contains trace amounts of heavy metal substances that are harmful to the human body, which is undesirable from a food hygiene perspective. Removing heavy metals from can cleaning agents not only improves the taste, but is also preferable from the viewpoint of food hygiene.

Furthermore, the third problem is that the conventional method cannot distinguish between saturated steam and superheated steam at low pressure.

In other words, in food processing and manufacturing, each food is shaped and contains an appropriate amount of moisture just before being steamed. However, it is natural that the moisture content varies depending on the product.

In order to process foods with different moisture contents using the same machine, it is necessary to use different moisture contents of the supplied steam, from saturated steam with a lot of moisture to heated steam that is close to dry, depending on the product (food). Ru.

However, in the conventional method, the low pressure steam (approximately 0.5 to 1 kg/eraG) generated using a pressure reducing valve divided into several stages has the problem that it is impossible to distinguish between saturated steam and superheated steam. have.

For example, when steaming steamed buns, dumplings, shumai, sekihan, etc., moist saturated steam is preferable, but if heated with dry superheated steam, the food will become dry and the quality will deteriorate. Furthermore, when drying vegetables, etc., it is preferable to heat them with dry superheated steam, but if they are dried with moist saturated steam, they will become messy and the required drying cannot be performed.

The present invention solves the problems described above when using steam from a boiler for food manufacturing and processing.

In other words, the present invention is capable of producing 0.4 kg/c with moderate moisture.
The purpose is to obtain food of good quality by supplying saturated steam at around 100° C. at a low pressure of about alG.

[Means for solving problems]

In the present invention, the high-pressure steam from the boiler 1 is blown out from a special nozzle 9 in the steam supply pipe 8 connected to the upper part of the tank 7 that supplied water, and the heavy metals in the can cleaning agent mixed in during evaporation in the boiler 1 are At the same time, the high-pressure steam blown into the tank 7 is converted into low-pressure steam, and this low-pressure steam is introduced into the steam separation chamber 34 having a barrier plate 36 that blocks the flow of the steam. A method for supplying steam for heating food, characterized by separating excess moisture by contacting with a barrier plate 36 in a separation chamber 34, and supplying saturated steam at 110° C. or lower with appropriate humidity to a food heating means 38. It is.

In addition, the present invention provides that the high-pressure steam from the boiler 1 is blown out from a special nozzle 9 in the steam supply pipe 8 connected to the upper part of the tank 7 that supplied water, and the heavy metals in the can cleaning agent mixed in during evaporation in the boiler 1 are At the same time, the high-pressure steam blown into the tank 7 is converted into low-pressure steam, and this low-pressure steam passes through the heat exchanger 22 and is generated inside the tank 7 by the heat exchanger 22. Low-pressure saturated steam is converted into heated steam by secondary heating, and then this low-pressure steam is introduced into a steam separation chamber 34 having a barrier plate 36 that blocks the flow of the low-pressure steam. This method of supplying steam for heating food is characterized by separating excess moisture by contact and supplying saturated steam at 110° C. or lower with appropriate humidity to the food heating means 38.

Furthermore, the present invention includes a boiler 1, a tank 7 in which water is kept at a constant water level by a level sensor 20, a steam supply pipe 8 connected to the upper part of this tank 7, a special nozzle 9 in this steam supply pipe 8, and this A heat exchanger 22 provided above the tank 7 and a steam storage chamber 2 provided above the heat exchanger 22
3 and a steam separation chamber 34 having a barrier plate 36 connected to the steam storage chamber 23.

[For production]

When high-pressure steam from the boiler 1 is adiabatically expanded using a special nozzle 9, it is blown into the tank 7 and impurities such as can cleaning agent are adsorbed to the water in the tank 7, resulting in low-pressure steam that is close to pure water. can be obtained both economically and economically.

In addition, the present invention provides low pressure steam from the tank 7 to the heat exchanger 2.
By performing secondary heating in step 2, steam of any humidity from saturated steam to superheated steam can be continuously supplied.

Furthermore, the low-pressure steam generated here is introduced into a steam separation chamber 34 having a barrier plate 36 that blocks the flow of this low-pressure steam, and excess moisture is separated by contact with the barrier plate 36.
The low-pressure steam is supplied to the food heating means 38 as low-pressure steam with any humidity ranging from moderately moist saturated steam at 110° C. or lower to dry superheated steam.

〔Example〕

As shown in the first diagram, the boiler 1 communicates through valves 2, 3, 4° 5 and a conduit 6 with a special nozzle 9 for adiabatic expansion in a steam supply pipe 8 installed vertically in the center of the upper surface of a flat water tank 7. . As shown in the second figure, this special nozzle 9 has 40 perforated plates 9c fixed in holes 9b each having a diameter of 2φ in an outer casing 9a which extends in the shape of a trumpet tube.

The lower end of this steam supply vibe 8 opens into the water tank 7 . A water supply pipe 12 is connected to the upper part of the water tank 7 via valves 10 and 11, and a trap 1 is connected to the lower part of the water tank 7.
3. It communicates with a drain pipe 19 via valves 14 and 15. The valve 10 is controlled by a water level sensor 20 and replenishes water so that the water level on the water surface 21 is always at a predetermined level;
Further, water exceeding a predetermined water level is automatically discharged by the steam trap 13 in proportion to the water level exceeding the upper limit, thereby controlling the water level. Therefore, the water level of the water surface 21 in the water tank 7 is controlled to be 173 points from the bottom of the water tank 7.

A cylindrical heat exchanger 22 surrounding the supply pipe 8 is provided on the water tank 7, and the storage chamber 23 is provided above the heat exchanger 22. The primary side of the heat exchanger 22 communicates with the boiler 1 via valves 24, 25 and a conduit 26, and with the upper side of the water tank 7 via valves 27, 28 and a drain pipe 29. The lower end of the secondary side of the heat exchanger 22 communicates with the earth in the water tank 7, and the upper end of the secondary side communicates with the steam storage chamber 23. In addition, 30 in the figure is the steam storage chamber 23
31 is the same safety valve.

The steam storage chamber 23 is connected to the steam separation chamber 34 via a conduit 33.
The other side of this steam separation chamber 34 is connected to a conduit 35.
to a food heating means 38, such as a steamer.

A barrier plate 36 interposed between the steam conduits 33 and 35 is provided at the upper center of the steam separation chamber 34 so as to be slid up and down by an actuating mechanism 37, and its lower part communicates with the water tank 7 via a conduit 39. .

Next, the operation of this device will be explained.

The high-temperature, high-pressure steam generated in the boiler 1 is adiabatically expanded from the special nozzle 9 via the valve 2゜3.4 and the conduit 6, and becomes low-temperature, low-pressure steam from the lower end of the steam supply vibe 8 to the water level in the water tank 7. Speech towards 21. Due to this adiabatic expansion, after the high-pressure steam is blown out into the water tank 7, it becomes 0.2~
Converts to low pressure steam of about 0.5 kg/cntG.

At this time, the heavy metals and other additives in the steam are adsorbed by the water in the water tank 7.

The water in the water tank 7 should be kept at a constant level by the level sensor 20 to prevent it from decreasing again due to evaporation (on the other hand, excess water is automatically drained outside the can via the steam trap 13, etc.). It is discharged.

The steam generated in the water tank 7 passes through a heat exchanger 22, is reheated, and is stored in an upper steam storage chamber 23. The generated low-pressure steam can be adjusted from saturated steam to superheated steam by controlling reheating in the heat exchanger 22 using the valve 25.

The low pressure steam stored in this upper steam storage chamber 23 is
The steam is introduced into the side steam separation chamber 34 through the conduit 33, but since there is a barrier plate 36 in this steam separation chamber 34 that blocks the flow of steam flowing from the direction of the steam parallel storage chamber, the steam is introduced into the side steam separation chamber 34. Excess moisture contained in the steam comes into contact with the surface of the barrier plate 36 and adheres to the barrier plate 36.

The steam from which excess moisture has been removed by the barrier plate 36 passes under the barrier plate 36 and leaves the steam separation chamber 34 at a gauge pressure of 0.4 mu/cdG and a saturated steam temperature of 109.43.
Any low-pressure steam can be produced, from moderately moist saturated steam containing no impurities to superheated steam that is close to dry.
The heat is supplied through a conduit 35 into a food heating means 38 such as a steamer, and is used as food processing heat.

The humidity or water content of this low pressure steam can be controlled by adjusting the barrier plate 36 up and down by the actuating mechanism 37.

The water removed by this barrier plate 36 is sent from the lower part of the steam separation chamber 34 to the lower part of the water tank 7 through a conduit 39.

The special nozzle 9 has a porous nozzle with a larger area than the supply conduit 6 at the end of the conduit 6 for steam discharged from the boiler 1, and uses adiabatic expansion of the steam to obtain low-pressure steam. . At this time, the relationship between the steam pressure (horizontal axis) of the boiler 1 and its steam amount is as shown in Fig. 3, and a + , at +
a3+ aa ras shows graphs when the diameter of the supply steam conduit 6 is 15A, 20A, 258, 32A, and 404, respectively.

A fixed amount of high pressure steam supplied has heat proportional to its pressure. When the steam is supplied at a pressure of 4 to 5 kg/colG and the pressure is reduced to 2 to 3 kg/cdG using the special nozzle 9, the steam is saturated and no drain comes out.

Normally, when a pressure reducing valve is used to lower the pressure on the secondary side, heat escapes only by the enthalpy-losing bone squeezed by the nozzle as a drain, and if it continues to flow, enthalpy is lost and a drain occurs. However, in this example, as shown in the third diagram, steam whose pressure has been reduced to 3 to 4 kg/dG is forced into the tank 7, so that the loss of enthalpy and heat caused by the drain is small. That is, the special nozzle 9 can prevent a decrease in enthalpy. Additionally, if the steam pressure drops too much, you can prevent the pressure inside the can from dropping by increasing the size of the blowout nozzle or reducing the supply pressure.

It can also be adjusted by tightening the degree of opening and closing of the valve 5.

However, since the released steam loses heat from the air in the tank 7, some drain occurs. Here, if the steam is created by making the drain into as fine a mist as possible, the efficiency of the drain can be minimized.

A similar effect can be obtained by creating superheated steam (less steam) and flowing it through the nozzle.

When the low-pressure steam thus obtained is subjected to secondary heating in the upper heat exchanger 22, it becomes superheated steam, and dry steam can be obtained. Therefore, by controlling the heating of the heat exchanger 22, it is possible to obtain low-pressure saturated steam and superheated steam of arbitrary humidity such that the degree of dryness of the product can be adjusted.

In addition, when the barrier plate 36 is lowered by the actuating mechanism 37, the surface activity of the steam is increased and moisture in the steam can be removed, and the humidity of the low-pressure steam can also be adjusted by this.

〔Effect of the invention〕

As described above, in the present invention, saturated steam and superheated steam can be used at any humidity, so steaming and drying can be performed appropriately.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an overview of an embodiment of the present invention, FIG. 2 is an enlarged view of the special nozzle, and FIG. 3 is a graph of pressure and steam amount in an experimental example of the present invention. 1...boiler, 7...tank, 8.
... Steam supply pipe, 9 ... Special nozzle, 36 ... Barrier plate, 34 ... Steam separation chamber, 38 ... Food heating means , 22...
Heat exchanger, 20...Level sensor.

Claims (3)

[Claims] (1) High-pressure steam from the boiler is blown out from a special nozzle in the steam supply pipe connected to the top of the tank that supplied water, removing heavy metals from the can cleaning agent mixed in during evaporation in the boiler into the water inside the tank. At the same time, the high-pressure steam blown into the tank is converted into low-pressure steam, and this low-pressure steam is introduced into a steam separation chamber equipped with a barrier plate that blocks the flow of the steam. 1. A method for supplying steam for heating food, characterized by separating moisture and supplying saturated steam at 110° C. or lower with appropriate humidity to a food heating means. (2) High-pressure steam from the boiler is blown out from a special nozzle in the steam supply pipe connected to the top of the tank that supplied water, removing heavy metals from the can cleaning agent mixed in during evaporation in the boiler into the water inside the tank. At the same time, the high-pressure steam blown into the tank is converted into low-pressure steam, and this low-pressure steam passes through a heat exchanger, which secondarily heats the low-pressure saturated steam generated inside the tank and turns it into superheated steam. Next, this low-pressure steam is introduced into a steam separation chamber equipped with a barrier plate that blocks its flow, and excess moisture is separated by contact with the barrier plate in the separation chamber, and the temperature is reduced to 110°C or lower with appropriate humidity. A method for supplying steam for heating food, characterized by supplying saturated steam to a food heating means. (3) A boiler, a tank that keeps water at a constant level using a level sensor, a steam supply pipe connected to the top of this tank, a special nozzle inside this steam supply pipe, and a heat exchanger installed above this tank. A steam supply device for heating food comprising: a steam storage chamber provided on the heat exchanger; and a steam separation chamber having a barrier plate connected to the steam storage chamber.