JP2002333103A - Generating method of superheated steam and equipment therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a generating method of superheated steam which generates safely and economically the superheated steam of high temperature by inexpensive equipment having a simple structure, and the equipment therefor. SOLUTION: Water 11 is put in a closed vessel 13 and the vessel 13 is heated, while the pressure is reduced by a blowing means 14. The water 11 inside the vessel is boiled at a low temperature to generate steam. The steam thus generated is pressurized by the blowing means 14 and passed through a heater 15 so that the temperature thereof be raised, and thus the superheated steam is generated. The equipment 10 for generating the superheated steam has the vessel 13 provided with a heating source 12 changing the water 11 inside into the steam, the blowing means 14 connected to the vessel 13 to reduce the pressure inside to be lower than the atmospheric pressure and discharging the generated steam outside, and the heater 15 heating further the pressurized steam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for generating superheated steam used in a drying line for, for example, wood, metal, plastic, ceramics, etc., a food sterilizing apparatus, and a heating facility using steam such as a baking furnace. .

[0002]

2. Description of the Related Art Conventionally, a superheated steam generator used in a drying line for wood, metal, plastic, ceramics, etc., a food sterilizer, a heating equipment using steam, such as a baking furnace, is disclosed in, for example, JP-A-09-140578. As disclosed in the official gazette, a steam generator is heated by a burner from below to generate steam, and the steam is introduced into a superheater provided in a flue that discharges combustion gas by a steam pipe, and the combustion gas is discharged. Superheated steam is generated by heating saturated steam by heat. When generating superheated steam (hereinafter also referred to as superheated steam) using a boiler, first generate steam having a temperature of 100 ° C. or more and a pressure of 1 kg / cm ² or more, and then raise the temperature using a heater or the like. Generated by heating.

[0003]

However, the above-described method for generating superheated steam has the following problems. When using a burner to generate superheated steam, the combustion gas generated by the burner heats the superheater after heat is removed by the steam generator, so the temperature of the combustion gas that heats the superheater causes the steam generator to heat. The temperature of the superheated steam generated by the superheater is lower than when the
It is about 50 ° C. Here, even if the capacity of the burner or the superheater is increased to increase the temperature of the superheated steam generated in the superheater, the temperature is limited to about 500 ° C., and the equipment cost of the superheated steam generator increases, and 1000
The high temperature superheated steam between ℃ was not obtained, and the capacity of the heating equipment could not be fully exhibited. When a superheated steam is generated using a boiler, the pressure inside the boiler is high, and the temperature of the boiler itself is high, which is dangerous. Therefore, the boiler method is restricted. The present invention has been made in view of such circumstances, and provides an inexpensive apparatus having a simple structure, a method for generating superheated steam that safely and economically generates high-temperature superheated steam, and an apparatus therefor. With the goal.

[0004]

According to the above object, there is provided a method for generating superheated steam according to the present invention, in which water is placed in a sealed container, the container is heated and the pressure is reduced by a blowing means, and the water in the container is boiled at a low temperature. Steam is generated, and the generated steam is pressurized by a blowing means, passed through a heater and heated to generate superheated steam. As described above, since the boiling point of water falls below 100 ° C. by reducing the pressure in the container by the blowing means,
Water can be boiled at a low temperature without heating to about 100 ° C. to generate steam. Then, after the steam is pressurized by a blowing means, the temperature is increased by passing through a heater, so that the predetermined steam pressure and the steam temperature, for example, the steam pressure is 2 kg / cm ² in absolute pressure and the steam temperature is 100 ° C. It is possible to generate superheated steam in a wide temperature range from a low temperature of about 200 ° C. to a high temperature of about 1200 ° C. Here, in the superheated steam generation method according to the present invention, the temperature in the container is 70 to 95.
It is preferred that the temperature be kept in the range of ° C. Thus, since the water in the container can be converted into steam at a low temperature of less than 100 ° C. without increasing the temperature, the heat conduction from the heated water to the container storing the water can be reduced.

[0005] A superheated steam generator according to the present invention which meets the above object has a container provided with a heating source for converting water in the inside into steam, and is connected to the container to reduce the pressure of the inside of the container below atmospheric pressure and generate the steam. It has a blower for discharging steam to the outside, and a heater for further heating steam pressurized and exhausted by the blower. With this configuration, the inside of the container can be depressurized by the blowing means, so that the boiling point of water can be lowered below 100 ° C. and the water can be boiled at a low temperature without heating to about 100 ° C. to generate steam. It becomes possible. Then, after this steam is pressurized by the blowing means, the temperature is raised by a heater, so that the predetermined steam pressure and steam temperature, for example, the steam pressure is 2 kg / cm ² in absolute pressure,
It becomes possible to produce superheated steam in a wide temperature range from a low temperature of about 100 ° C. to a high temperature of about 1200 ° C. Here, in the superheated steam generator according to the present invention, the heater is preferably a heat exchanger. This makes it possible to prevent the generation of impurities such as combustion gas.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. Here, FIG. 1 is an explanatory diagram of a superheated steam generator according to one embodiment of the present invention, and FIG. 2 is an explanatory diagram of a superheated steam generator according to another embodiment of the present invention.

As shown in FIG. 1, a superheated steam generator 10 according to one embodiment of the present invention has a tube heater 12 which is an example of a heating source for converting internal water 11 into steam (hereinafter also referred to as steam). , A compressor 14 connected to the container 13 to reduce the pressure inside the container 13 below the atmospheric pressure and discharge the generated steam to the outside, and a compressor 14 which is exhausted by the compressor 14 and pressurized. And a heat exchanger 15 which is an example of a heater for further heating the heated steam, and further includes an operation control means 16 including a programmable controller for performing control for generating superheated steam. The details will be described below.

The container 13 is made of, for example, a pressure-resistant material. A water supply pump 17 is provided near the lower part of the container 13, and a water supply port 18 communicating with the water supply pump 17 is provided at a lower part of the container 13. . Note that two tube heaters 12 penetrating the lower side of the container 13 are provided in the container 13.
Is arranged. A water level detector (for example, a water level sensor) 19 is formed on the upper side (near the liquid level) in the container 13, and the water 11 in the container 13 flows into the water level detector 19. The water level detector 19 detects the height of the water level in the container 13 and outputs a water level detection signal. Further, the container 13 includes a container pressure detecting means (for example, a pressure gauge) 20 for detecting the pressure in the container 13 and a liquid temperature detecting means (for example, a thermometer or the like) for detecting the temperature of the water 11 in the container 13. ) 21 is provided, the container pressure detecting means 20 detects the pressure in the container 13 and outputs a container pressure detection signal, and the liquid temperature detecting means 21 detects the temperature of the water 11 in the container 13 and outputs a liquid temperature detection signal. Is output respectively.

A steam outlet 22 is formed at the upper end of the container 13, and a compressor 14 is connected to the steam outlet 22, and a heat exchanger 15 is connected to the upper end of the compressor 14. The upper end of the heat exchanger 15 has an inverted L
A pipe 23 having a U-shape is connected, and steam that is pressurized and heated, that is, superheated steam,
A plurality of holes (not shown) for spraying an object (for example, a drying line of wood, metal, plastic, ceramics, etc., a food sterilizer, a baking furnace, etc.) in a heating facility (not shown) are formed. .

On the other hand, from the upstream side to the center of the pipe 23, a steam temperature detecting means 24 for detecting the temperature of the pressurized and heated superheated steam and outputting a steam temperature detection signal;
A steam pressure detecting means 25 for detecting the pressure of the superheated steam and outputting a steam pressure detection signal, an automatic pressure regulating valve 26 which opens automatically when a predetermined pressure is reached, and a steam amount of the superheated steam sprayed on the object. A flow control valve 27 for adjustment is provided. It is preferable to use, for example, a heat-resistant austenitic special alloy steel containing nickel, chromium, molybdenum, or the like for the pipe 23 through which the superheated steam passes. Thereby, it is possible to sufficiently withstand high-temperature superheated steam of about 1000 ° C.

The operation control means 16 receives a water level detection signal from the water level detector 19, and performs a feedback control of the water supply pump 17 so as to maintain a predetermined water level, and a vessel pressure detection means 20. Receiving the container pressure detection signal from the container 13 and the liquid temperature detection signal from the liquid temperature detection means 21 respectively, reducing the pressure inside the container 13 to below atmospheric pressure, and maintaining the water in the container 13 at a temperature at which the water in the container 13 boils at a low temperature. It has a liquid state controller 29 for controlling the heater 12 and the compressor 14 in a feedback manner.
Further, the operation control means 16 receives the steam temperature detection signal from the steam temperature detection means 24 and the steam pressure detection signal from the steam pressure detection means 25, respectively, and controls the heat exchanger 15 so as to maintain the predetermined temperature and pressure. Superheated steam state controller 30 for feedback control of compressor and compressor 14 respectively
And a superheated steam output controller 31 for controlling the flow regulating valve 27 according to the use state of the superheated steam.

Next, a method for generating superheated steam according to an embodiment of the present invention will be described with reference to the above-described superheated steam generator 10.
This will be described with reference to FIG. First, the water 11 is charged (supplied) into the sealed container 13 so that the water level rises to near the center of the water level detector 19 by the water supply pump 17. The water 11 in the container 13 is heated using the tube heater 12,
While maintaining the temperature in the range of 70-95 ° C.
The pressure of the container 13 is reduced to less than the atmospheric pressure by the compressor 14 so that the temperature range of ~ 95 ° C is the boiling point.
The water 11 in 3 is boiled at a low temperature to generate steam.

Here, the water 11 fluctuates with the generation of steam.
The water surface height is determined by inputting a water surface detection signal from the water surface detector 19 to the water supply controller 28 and setting the water supply pump 17 to the water supply controller 2.
By performing feedback control according to 8, a predetermined water level, for example, about 70 to 90% of the container is maintained. Also,
The pressure in the container 13 and the temperature of the water 11 in the container 13 are obtained by inputting a container pressure detection signal from the container pressure detection means 20 and a liquid temperature detection signal from the liquid temperature detection means 21 to the liquid state controller 29, respectively. Then, the tube heater 12 and the compressor 14 are feedback-controlled by the liquid state controller 29, so that the pressure inside the container 13 is reduced to less than the atmospheric pressure, and the water 11 in the container 13 is maintained at a temperature and pressure at which the water 11 boils at a low temperature.

Here, the temperature in the container 13 is set to 70 to 95 ° C.
The reason defined in the range is explained. When the temperature inside the container 13 is lower than 70 ° C., the power of the compressor 14 required to reduce the pressure inside the container 13 needs to be increased in order to lower the pressure inside the container 13 in order to boil the water 11 at a low temperature. Also need to be high and not economical.
On the other hand, when the temperature in the container 13 exceeds 95 ° C.,
The amount of electric power of the tube heater 12 used to boil the water 11 in the inside 3 increases, which is not economical, and the heat conduction from the heated water 11 to the container 13 storing the water 11 increases, resulting in poor thermal efficiency. In addition, the temperature of the container 13 increases, and the workability deteriorates. Thereby, the temperature in the container 13 was maintained in the range of 70 to 95 ° C., but more economically,
In order to generate superheated steam with good thermal efficiency and good operability, it is preferable to maintain the temperature in the container 13 in the range of 75 to 90 ° C, more preferably 80 to 90 ° C.

Next, the generated steam is exhausted to the downstream side by the compressor 14 through the steam discharge port 22 and is pressurized. At this time, when the pressure increases to a predetermined pressure, for example, about 1.05 to ² kg / cm ^{2 in} absolute pressure, the automatic pressure control valve 26 opens. The pressure and temperature of the steam pressurized to the predetermined pressure are first determined by the steam temperature detection signal from the steam temperature detection means 24 and the steam pressure detection means 25.
Superheated steam state controller 30 based on the steam pressure detection signal from
Is input to Next, this steam is passed through the heat exchanger 15 so that the temperature can be raised to a predetermined temperature, for example, about 100 to 1200 ° C., and a predetermined pressure, for example, 1.0 to 1.0 ° C.
The feedback control of the heat exchanger 15 and the compressor 14 is performed so that the pressure can be increased to about 5 to ² kg / cm ² .
As described above, the steam is pressurized to a predetermined pressure and is heated to a predetermined temperature, thereby generating superheated steam having a required steam pressure and a necessary steam temperature. After opening 27, the generated superheated steam is sent to a heating facility.

The temperature of the superheated steam is controlled, for example, at 500 to 1000 ° C.
It is also possible to control to a temperature range of 0 to 1000 ° C, 700 to 1000 ° C, and the like. The operation of the compressor 14 is controlled by the operation control means 16 by the heat exchanger 1.
On the 5th side, a pressure taking into account the pressure required when utilizing superheated steam and the pressure loss in the heat exchanger 15 and the pipe 23 (the greater the pressure loss in the heat exchanger 15, the greater the heating capacity. ), While the container 13 side is connected to the container 1
Control is performed so that water 11 in 3 can be decompressed so as to boil at low temperature.

Next, a superheated steam generator 32 according to another embodiment of the present invention will be described. The temperature of the water 11, the pressure and the temperature of the superheated steam are the same as those of the superheated steam generator 10 according to the above embodiment. The conditions are the same, and the operation control means 16 for performing the control is the same, so that the detailed description is omitted. As shown in FIG. 2, a superheated steam generator 32 according to another embodiment of the present invention includes a low-pressure boiler (an example of a container) including an electric heater 33 which is an example of a heating source that converts internal water into steam. And a blower 35 which is an example of a blower connected to the low-pressure boiler 34 to reduce the pressure inside the low-pressure boiler 34 to less than the atmospheric pressure and discharge the generated steam to the outside, that is, to a pipe (not shown) for sending downstream. And a heater 36 composed of a heating wire for further heating the steam exhausted by the blower 35 and pressurized in the pipe, and the control for generating superheated steam is as follows:
The operation is performed by the operation control means 16 including the programmable controller described in the above embodiment. In addition,
The temperature in the low-pressure boiler 34 is maintained in a range of 70 to 95 ° C. by the operation control means 16.

With this configuration, water is poured into the sealed low-pressure boiler 34, the low-pressure boiler 34 is heated by the electric heater 33, and the inside of the low-pressure boiler 34 is depressurized by the blower 35. As a result, water in the low-pressure boiler 34 is boiled at a low temperature to generate steam. At this time, the temperature of the water in the low-pressure boiler 34 also decreases.
Heating by the electric heater 33 is increased. The generated steam is exhausted to a pipe connected to the downstream side of the blower 35, pressurized to a predetermined pressure in the pipe by the blower 35, passed through a heater 36, and heated to obtain a required steam. Generate superheated steam with pressure and steam temperature.

As described above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the configurations described in the above embodiments, and is described in the claims. The present invention also includes other embodiments and modifications that can be considered within the scope of the matters. For example, in the above-described embodiment, a case where a tube heater is used as a heating source has been described.
If it is possible to maintain the temperature in the range described above, it is also possible to equip another heating source, for example, a burner outside the container, to heat and hold the water. In the above embodiment, the case where a compressor is used as the blowing means has been described.However, if the inside of the container can be reduced to a pressure lower than the atmospheric pressure and the generated steam can be pressurized, other blowing means, for example, a blower or the like may be used. Is also possible.

In the above embodiment, the case where a heat exchanger is used as the heater has been described. However, if the generated steam can be heated to a predetermined temperature, for example, a heater that can be set to a high temperature or a high-temperature gas can be used. It is also possible to arrange and use a tube or the like that passes through inside the pipe through which the steam passes. And in the said embodiment, the water supplied to a container by a water supply pump is dissolved oxygen by a deaerator in advance,
It is preferable to remove gas such as carbon dioxide. This makes it possible to prevent corrosion of pipes and the like through which steam passes, and to prevent oxidation of the target object due to the use of superheated steam. Further, in the above embodiment, the superheated steam is supplied to the pipe for spraying the superheated steam at a predetermined pressure, for example, 2 kg /.
A safety valve for releasing superheated steam when the pressure exceeds cm ² may be provided.

[0021]

According to the method of generating superheated steam according to the first and second aspects, since the boiling point of water falls below 100 ° C. by reducing the pressure in the vessel by the blowing means, the water is heated to 100 ° C.
It is possible to generate steam by boiling at low temperature without heating to the extent. Then, after the steam is pressurized by the blowing means, the steam is passed through a heater to raise the temperature, so that the predetermined steam pressure and the steam temperature, for example, the steam pressure is 2 kg / c in absolute pressure.
m ² , it is possible to generate superheated steam in a wide temperature range from a low temperature of about 100 ° C. to a high temperature of about 1200 ° C. Therefore, it is possible to work safely without increasing the pressure in the container and the temperature of the water in the container to be lower than 100 ° C., and to clear the regulations such as the boiler method. It becomes possible.
In particular, in the method of generating superheated steam according to claim 2, since the water in the container can be converted into steam at a low temperature of less than 100 ° C. without increasing the temperature, heat conduction from the heated water to the container storing the water. Can be reduced. Therefore, the heat efficiency is improved and the economic efficiency is improved.

In the superheated steam generator according to the third and fourth aspects, since the inside of the vessel can be depressurized by the blowing means, the boiling point of water is lowered below 100 ° C.
It is possible to generate steam by boiling at low temperature without heating to the extent. Then, after the steam is pressurized by the blowing means, the temperature is raised by a heater, so that the predetermined steam pressure and the steam temperature, for example, the steam pressure is 2 k in absolute pressure.
g / cm ² , from a low temperature of about 100 ° C. to 120 ° C.
It becomes possible to produce superheated steam in a wide temperature range up to a high temperature of about 0 ° C. Therefore, it is possible to provide an inexpensive superheated steam generator with a simple structure that can safely perform the operation without increasing the pressure in the container and reducing the temperature of the water in the container. . In particular, in the superheated steam generator according to the fourth aspect, since generation of impurities such as combustion gas can be prevented, a clean superheated steam generator that does not pollute the environment can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a superheated steam generator according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a superheated steam generator according to another embodiment of the present invention.

[Explanation of symbols]

10: superheated steam generator, 11: water, 12: tube heater (heating source), 13: container, 14: compressor (blowing means), 15: heat exchanger (heating device), 16: operation control means, 17: Water supply pump, 18: water supply port, 19:
Water level detector, 20: container pressure detecting means, 21: liquid temperature detecting means, 22: steam outlet, 23: piping, 24: steam temperature detecting means, 25: steam pressure detecting means, 26: automatic pressure regulating valve, 27 : Flow control valve, 28: water supply controller, 2
9: liquid state controller, 30: superheated vapor state controller, 3
1: superheated steam output controller, 32: superheated steam generator, 3
3: electric heater (heating source), 34: low-pressure boiler (vessel), 35: blower (blower means), 36: heater

Claims (4)

[Claims] 1. A closed container is filled with water, the container is heated and the pressure is reduced by a blowing means, the water in the container is boiled at a low temperature to generate steam, and the generated steam is added by the blowing means. A method for generating superheated steam, comprising pressurizing, passing through a heater and raising the temperature to generate superheated steam. 2. The superheated steam generation method according to claim 1, wherein the temperature in the vessel is maintained in a range of 70 to 95 ° C. 3. A container provided with a heating source for converting water inside into steam, a blowing means connected to the container to reduce the pressure inside the container below atmospheric pressure and discharge the generated steam to the outside, A heater for further heating steam pressurized and exhausted by the blowing means. 4. The superheated steam generator according to claim 3, wherein said heater is a heat exchanger.