JPH0445139B2 - - Google Patents

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, steamed buns, pudding, cutlet cakes, and other foods called steamed foods (steamed processed); meat foods such as ham and sausage; 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. Ta.

Compared to the traditional method of using steam obtained by heating a pot to steam food, 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 has excellent economic efficiency and operability, such as easy control of steam generation.

[Problem that the invention seeks to solve]

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

The first problem is that the steam obtained from the boiler is saturated steam, and the gauge pressure is generally 5 to 7 kg/kg.
cm ² G, and the saturation temperature is about 158°C to 169°C, it is superheated steam at high temperature and pressure, so it cannot be used as it is for steaming food, so this steam is It cannot be used unless it is supplied into a food steaming device at a reduced pressure and temperature of about 1 to 2 kg/cm ² G, which does not interfere with the continuous operation of the boiler, 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.

Generally, 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 under such high-temperature conditions of 100℃ or higher for steaming food products may cause changes in the product's characteristics such as surface burns, scorching, and dryness, and There is a problem in that the conductivity and moisture permeability change, which has an unfavorable effect on quality conditions such as "uneven spots" appearing on the product at a later date.

Here, if we consider how the steaming of food causes changes in physical properties in terms of thermal energy, the supplied steam envelops the food as thermal energy, and the moisture generated by heat exchange with the food This is a continuous movement in which steam forms a surface film on the food and continues to be applied as thermal energy, which conducts heat to the inside of the food through this moisture film and raises the temperature of the food.

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, when high-temperature, 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, causing drying of the food surface and releasing 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 generated by a general-purpose boiler using a pressure reducing valve, the boiler itself is inherently high-temperature and about 5 to 7 kg/cm ² G.
Since the purpose is to obtain high-pressure steam, the range in which pressure can be reduced is at most 2 to 3 kg/cm ²
It is difficult to continuously obtain steam at a reduced pressure of about 0.1 to 0.4 Kg/cm ² G, which is suitable for food steaming as mentioned above, in terms of boiler operation adjustment, and this general-purpose boiler The problem is that equipment supplied to other factory facilities cannot operate because the pressure is unusable (commonly used at 2 to 3 kg/cm ² G).

Furthermore, the second problem that arises when steam obtained from a boiler is used for food manufacturing and processing is:
A cleaning agent added to boiler water to protect the boiler body gets mixed into the steam, which causes a significant problem with the quality of food and impairs its 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 11 to 13, and it also contains trace amounts of heavy metals 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 types of steam to be supplied depending on the moisture content of the product (food), from saturated steam with a high moisture content to heated steam that is close to dry.

However, in the conventional method, low-pressure steam (0.5-1Kg/cm ²
G), there is a problem in that it is impossible to use saturated steam and superheated steam differently.

For example, when steaming steamed buns, gyoza, shyu mai, sekihan, etc., moist saturated steam is preferable, but if you heat it with dry superheated steam, it will become dry.
Quality deteriorates. Also, when drying vegetables etc., it is preferable to heat them with dry superheated steam.
If it is dried with moist saturated steam, it will become squishy and mushy, making it impossible to perform the required drying.

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 has an appropriate moisture content of 0.4
The purpose is to obtain food of good quality by supplying saturated steam at around 100°C at a low pressure of about Kg/cm ² G.

[Means for solving problems]

In the present invention, high-pressure steam from the boiler 1 is blown out from a special nozzle 9 in a steam supply pipe 8 connected to the upper part of a tank 7 that has supplied water to the boiler 1.
The barrier plate 36 adsorbs heavy metals etc. from the can cleaning agent mixed in during evaporation into the water inside the tank 7, converts the high-pressure steam blown into the tank 7 into low-pressure steam, and blocks the flow of this low-pressure steam. The steam is introduced into a steam separation chamber 34 having a steam separation chamber 34, and excess moisture is separated by contact with a barrier plate 36 in the separation chamber 34, and saturated steam of 110° C. or lower with moderate humidity is supplied to the food heating means 38. This is a method of supplying steam for heating food.

In addition, the present invention provides that the high pressure steam from the boiler 1 is
The water 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 etc. from the can cleaning agent mixed in during evaporation in the boiler 1 are adsorbed into the water inside the tank 7. 7
Converts the high pressure steam blown out into low pressure steam,
This low-pressure steam passes through a heat exchanger 22, which secondarily heats the low-pressure saturated steam generated in the tank 7 and converts it into heated steam.Then, this low-pressure steam is passed through a barrier plate 36 that blocks the flow of the low-pressure steam. The steam is introduced into a steam separation chamber 34 having a steam separation chamber 34, and excess moisture is separated by contact with a barrier plate 36 in the separation chamber 34, and saturated steam of 110° C. or lower with moderate humidity is supplied to the food heating means 38. This is a method of supplying steam for heating food.

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

[Effect]

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 agents are adsorbed to the water in the tank 7, producing low-pressure steam in a state close to pure water. can be obtained efficiently and economically.

Further, according to the present invention, by secondarily heating the low-pressure steam from the tank 7 using the heat exchanger 22, it is possible to continuously supply steam of any humidity from saturated steam to superheated steam.

Furthermore, the low-pressure steam generated here is transferred to a steam separation chamber 3 having a barrier plate 36 that blocks the flow of this low-pressure steam.
4, excess water is separated by contact with the barrier plate 36, and low-pressure steam with any humidity ranging from saturated steam with moderate humidity below 110°C to dry superheated steam is produced. This is then supplied to the food heating means 38.

〔Example〕

As shown in the first diagram, the boiler 1 has valves 2, 3, 4,
5 and a conduit 6 to a special nozzle 9 for adiabatic expansion in a steam supply pipe 8 erected at the center of the upper surface of the flat water tank 7 . This special nozzle 9
As shown in the figure, there is a diameter
Forty perforated plates 9c are fixed in 2φ holes 9b.

The lower end of this steam supply pipe 8 opens into the tank 7 . At the top of this water tank 7 are valves 10 and 11.
A water supply pipe 12 is connected through the water tank 7, and the lower part of the water tank 7 is connected to a drain pipe 19 through a trap 13 and valves 14 and 15. The valve 10 is controlled by a water level sensor 20 to supply water so that the water level at the water surface 21 is always at a predetermined level, and when the water level exceeds the predetermined level, a steam trap 13 is used to prevent the water level from exceeding the upper limit. Only automatically drains and controls the water level. Therefore, the water tank 7
The water level of the water surface 21 inside is controlled to be 1/3 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.
The storage chamber 23 is provided above the storage chamber 2. The primary side of this heat exchanger 22 communicates with the boiler 1 via valves 24, 25 and a conduit 26, and also communicates with the boiler 1 through valves 24, 25 and a conduit 26.
8. Communicates with the upper side of the water tank 7 via a drain pipe 29. The lower end of the secondary side of the heat exchanger 22 communicates with the upper part of 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 steam storage chamber 2
3 is a pressure gauge, and 31 is the same safety valve.

The steam storage chamber 23 communicates via a conduit 33 to one side of a steam separation chamber 34, the other side of which is connected via a conduit 35 to food heating means 38, such as a steamer. A barrier plate 36 interposed between the steam conduits 33 and 35 is located at the upper center of the steam separation chamber 34.
is provided 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 and high pressure steam generated in boiler 1 is passed through valve 2,
3 and 4 and a special nozzle 9 through the conduit 6, and is blown out from the lower end of the steam supply pipe 8 toward the water surface 21 in the water tank 7 as low-temperature, low-pressure steam. Due to this adiabatic expansion, after the high pressure steam is blown out into the water tank 7, it changes to low pressure steam of about 0.2 to 0.5 kg/cm ² G. At this time, the heavy metals and other additives in the steam are removed from the water tank 7.
It is absorbed by the water inside.

The water in this water tank 7 only needs to be kept at a certain level by the level sensor 20 to prevent it from decreasing again due to evaporation, and on the other hand, excess water is automatically drained outside the can via the steam trap 13 etc. be discharged.

The steam generated in this water tank 7 is transferred to a heat exchanger 22.
The steam passes through, is reheated and stored in the 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 passed through a conduit 33 to a side steam separation chamber 34.
However, since there is a barrier plate 36 in this steam separation chamber 34 that blocks the flow of steam flowing in from the direction of the steam storage chamber, steam flows through this barrier plate 36.
Excess moisture contained in the vapor 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 removes impurities from the steam separation chamber 34 with a gauge pressure of 0.4 Kg/cm ² G and a saturated steam temperature of 109.43°C. Any low-pressure steam, from saturated steam with moderate humidity to almost dry superheated steam, is supplied through a conduit 35 to a food heating means 38 such as a steamer, and is used as food processing heat. It is.

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 transferred to the steam separation chamber 3
4 is sent to the lower part of the water tank 7 through a conduit 39.

Experimental Example The special nozzle 9 is a porous nozzle having a larger area than the supply conduit 6 at the end of the discharge steam conduit 6 from the boiler 1 to obtain low-pressure steam by utilizing the adiabatic expansion of the steam. At this _time , _the relationship between the steam pressure (horizontal axis) and the steam amount in the boiler ₁ is as shown _{in FIG} . are 15A, 20A, 25A, 32
A graph in the case of A, 40A is shown.

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/cm ² G and reduced to 2 to 3 kg/cm ² G by the special nozzle 9, the steam is saturated and no drain comes out.

Normally, when using a pressure reducing valve to lower the pressure on the secondary side,
Heat will escape as a drain by the amount of enthalpy lost by squeezing in the nozzle, and if it continues to flow, enthalpy will be lost and a drain will be generated. However, in this example, as shown in the third diagram, steam reduced in pressure to 3 to 4 kg/cm ² G is forced into the tank 7.
There is not much drain, and there is little loss of enthalpy and heat. 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.

The low pressure steam thus obtained is transferred to the upper heat exchanger 22.
When it is heated secondarily, it becomes superheated steam and dry steam can be obtained. Therefore, the heat exchanger 22
By controlling the heating of the product, it is possible to obtain low-pressure saturated steam and superheated steam with arbitrary humidity so that the degree of dryness of the product can be adjusted.

Furthermore, if 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 drawings]

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, 2
2... Heat exchanger, 20... Level sensor.

Claims (1)

[Scope of 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, and removes heavy metals from the can cleaning agent mixed in during evaporation in the boiler into the tank. At the same time, the high-pressure steam blown into the tank is adsorbed by the water inside the tank, and the high-pressure steam 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 low-pressure steam. A method for supplying steam for heating food, characterized by separating excess water by contact with the water and supplying saturated steam at 110°C or less 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, and the water inside the tank adsorbs heavy metals, etc. from the can cleaning agent mixed in during evaporation in the boiler. 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 in the tank and converts it into superheated steam. Next, this low-pressure steam is introduced into a steam separation chamber with a barrier plate that blocks its flow, and excess moisture is separated by contact with the barrier plate in the separation chamber. A method for supplying steam for heating food, characterized by supplying steam to a food heating means. 3. A boiler and a tank in which water is kept at a constant water level using a level sensor, a steam supply pipe connected to the top of this tank, a special nozzle in 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.