JPH1194203A - Steam producing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide steam producing equipment which can simply prevent concentration of impurities in a liquid in a boiler part which generates steam. SOLUTION: This equipment has a boiler part 2 which turns a liquid into steam by heating, a level detecting means 42 which monitors a liquid level of the boiler part 2, a first automatic on-off valve 43 which is provided in a feed water system 18 feeding the liquid to the boiler part 2, a second automatic on-off valve 44 which is provided in a drainage system 19 draining the liquid in the boiler part 2 and an operating means 46 for start or stop, and it is provided with a control part 4 which controls opening and closure of the first automatic on-off valve 43 on the basis of an output of the level detecting means 42. When an operating means 46b for stop is operated, the first automatic on-off valve 43 is closed, while the second automatic on-off valve 44 is opened so that the whole of the liquid in the boiler part 2 be drained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to steam used as a source of superheated steam used for cooking, thawing, sterilizing, washing, and sauna of foods, or for various heating and treatment in the chemical industry. The present invention relates to a steam production device for generating steam.

[0002]

2. Description of the Related Art In order to generate steam, a tube into which a liquid is introduced so as to maintain a liquid level at a predetermined level, an exciting coil wound around the tube, and a change in a magnetic field generated by the exciting coil. Attention has been paid to an electromagnetic induction heating-type steam generator having a heating element that generates heat due to the electromagnetic induction heating.

In this case, tap water is introduced into the pipe in accordance with the evaporation of the water in the pipe, so that impurities such as calcium are concentrated in the pipe. Therefore, there has been proposed a steam production apparatus in which the impurity concentration of a liquid in a tube is measured by, for example, a conductivity meter, and when the concentration reaches a predetermined concentration, the liquid in the tube is discharged and replaced with fresh tap water (Japanese Patent Application Laid-Open No. Hei 9 (1997)). −
No. 122635).

[0004]

However, in order to accurately measure the impurity concentration in water using a conductivity meter or the like, an expensive measuring instrument is required, and the control system becomes complicated by adding a concentration meter. There was a problem of becoming.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a steam producing apparatus which can easily prevent concentration of impurities in a liquid in a boiler section for generating steam. .

[0006]

According to a first aspect of the present invention, there is provided a boiler section for heating a liquid to produce a vapor, a liquid level detecting means for monitoring a liquid level in the boiler section, The first water supply system that supplies liquid to the boiler
An automatic opening / closing valve, a second automatic opening / closing valve provided in a discharge system for discharging the liquid in the boiler section, and operating means for starting or stopping, and based on an output of the liquid level detecting means, 1 comprising a control unit for controlling the opening and closing of the automatic on-off valve,
The control unit is configured to operate the operation unit for stopping,
A steam production apparatus, wherein the first automatic on-off valve is closed and the second automatic on-off valve is opened so as to discharge all the liquid in the boiler section.

According to a second aspect of the present invention, in the first aspect, when the operating means for starting is operated, the control unit closes the second automatic opening / closing valve and sets a predetermined amount in the boiler unit. The first automatic on-off valve is opened to allow the liquid to enter.

According to a third aspect of the present invention, in the first or second aspect, the control unit supplies the boiler unit with water for replenishment based on an output of the liquid level detection unit. When the predetermined number of times of opening and closing is reached, the second automatic opening and closing valve is opened for a predetermined time to discharge a predetermined amount of liquid accumulated in the boiler section, and the first automatic opening and closing valve is opened to match the drainage amount. New water supply.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the boiler section includes a tube, an exciting coil wound around the tube, and a magnetic field change generated by the exciting coil. And a heating element made of a conductive material in which a number of passages are formed.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an equipment configuration diagram of a superheated steam production apparatus of the present invention.

In FIG. 1, a steam producing apparatus 1 comprises a boiler section 2, a superheat section 3, a control section 4, and a processing section 5, and is configured to generate superheated steam. The heating section 3
Is not essential, and the processing unit 5 may be connected to the boiler unit 2.

The boiler unit 2 has a heating element 12 housed in a vertically upward tube 11 and an exciting coil 13 wound around the tube 11. The tube 11 is formed in a pipe shape from a nonmagnetic material such as ceramic having excellent heat resistance, corrosion resistance and pressure resistance. The heating element 12 housed in the tube 11 has a large number of passages formed of a conductive material such as a metal which generates heat due to a change in a magnetic field generated by the exciting coil 13. That is, the boiler unit 2 is configured as an electromagnetic induction heating unit.

The boiler section 2 has a rising pipe 15 for controlling the liquid level and a bypass pipe 16 for gas-liquid separation.
, The pipe 11, the rising pipe 15, and the bypass pipe 16
And a common header section 17 is provided. Further, a water supply system 18 and a drainage system 19 are connected to the header section 17. The bypass line 16 is a T-shaped portion 16a that performs vapor-liquid separation by colliding the steam from the tube 11 laterally against a wall.
And a connecting portion 16b for returning the liquid separated by the T-shaped portion 16a to the header portion 17, and an elbow portion 16c for changing the vapor separated by the T-shaped portion 16a from upward to horizontal.

The superheater 3 is placed in a horizontal horizontal tube 31.
The heating element 32 is housed, and the exciting coil 33 is wound around the tube 31. The tube body 31 is formed in a pipe shape from a nonmagnetic material such as ceramics having excellent heat resistance, corrosion resistance and pressure resistance. Heating element 3 housed in tube 31
Reference numeral 2 denotes a structure in which a large number of passages are formed of a conductive material such as a metal which generates heat due to a change in a magnetic field generated by the excitation coil 33. That is, the superheating unit 3 is also configured as an electromagnetic induction heating unit. Further, a processing unit 5 is connected to an outlet side of the superheating unit 3. The processing unit 5 in the illustrated example is configured so that food can be cooked using superheated steam.

The control unit 4 is attached to the thermometer 41, the level meter (liquid level detecting means) 42 provided to the riser 15, and the water supply system 18. A first electromagnetic on-off valve (first automatic on-off valve) 43, a second electromagnetic on-off valve (second automatic on-off valve) 44 attached to the drainage system 19, and a controller 45. The control unit 4 is provided with an operation box (operation means) 46 having a start button 46a and a stop button 46b. The control unit 4 controls the first solenoid on-off valve 43 on and off based on the input from the level meter 42 to adjust the supply amount, and controls the liquid level in the tube 11 of the boiler unit 2 to a predetermined value. doing.

When the start button 46a is operated in addition to the liquid level control at the time of operation, the control unit 4 performs a second drainage operation.
Close the electromagnetic on-off valve 44 and open the first electromagnetic on-off valve 4 for water supply.
When the stop button 46b is operated, the first solenoid valve 43 for water supply is closed, and the second solenoid valve 44 for drainage is opened to open the boiler unit. A function to discharge all liquid in the boiler unit 2 and a predetermined amount of water for each supply of water by operating the first solenoid on-off valve 43 a predetermined number of times so that impurities in the liquid in the boiler unit 2 are not concentrated during normal operation. Has a function of opening the second electromagnetic on-off valve 44 for a predetermined time in order to discharge the liquid.

The high-frequency power supply devices 14 and 34 for the exciting coils 13 and 33 of the boiler unit 2 and the superheater unit 3 are controlled to predetermined outputs by a controller 45 that receives an input from a thermometer 41. Further, the reason why the tube body 31 and the heating element 32 of the superheating section 3 are arranged horizontally horizontally is that the inlet side of the heating element 32 of the superheating section 3 is not covered with condensed water, This is because the time when the steam production device 1 is started up is reduced by ensuring the passage of steam. However, in a chemical device or the like, the superheater 3 may be disposed vertically.

Next, the operation of the steam producing apparatus 1 having the above-described structure will be described with reference to the equipment diagram of FIG. 1 and the flowchart of FIG.

When the start button 46a is pressed, the flow starts (S1). At this time, the boiler section 2 and the overheating section 3
Is dry, the water supply electromagnetic on-off valve 43 is opened to start water supply to the boiler unit 2 (S
2). The level meter 42 determines whether or not a predetermined level of liquid in the boiler unit 2 is secured (S3). When the level reaches a predetermined level (S3, YES), the water supply electromagnetic on-off valve 43 is closed (S4). As a result, the boiler unit 2 is filled with a predetermined amount of liquid, and the electromagnetic induction heating units of the boiler unit 2 and the superheating unit 3 are started (S5). Since the boiler unit 2 is immersed in the liquid, it immediately starts generating steam by heat exchange. If the generation of steam in the boiler section 2 continues, the liquid level decreases. Therefore, it is determined whether or not the level meter 42 has reached the lower limit (S6). Open (S7). Since the water supply increases the level, it is determined whether or not the level meter 42 has reached the upper limit (S8). When the upper limit has been reached (S8, YES), the water supply electromagnetic on-off valve 43 is closed (S9).

In this way, the number n of opening / closing operations of the water supply electromagnetic on-off valve 43 for replenishing the liquid accompanying the evaporation is counted (S10). It is determined whether the number of times n of opening and closing has reached, for example, five times n _max (S11). When the predetermined value _nmax is reached (S11, YES), the drainage electromagnetic on-off valve 44 is opened for a predetermined time to discharge a predetermined amount of liquid accumulated in the boiler unit 2 and to clear the number of times n of opening and closing to zero (S12). .
At this time, the water supply electromagnetic on-off valve 43 is activated, and water is supplied by the drainage electromagnetic on-off valve 44 according to the amount of drainage. Unless the stop button 46b is operated (S13, N
O), the water supply corresponding to the evaporation and the predetermined amount of drainage corresponding to the number of times of water supply are repeated (S6 to S12). Stop button 4
When 6b is operated (S13, YES), the electromagnetic induction heating units of the boiler unit 2 and the superheating unit 3 are stopped (S14), the water supply electromagnetic on / off valve 43 is closed, and the drainage electromagnetic on / off valve 44 is opened, All of the liquid in the boiler section 2 is discharged (S15).

3 and 4 show another steam producing apparatus. The superheater 103 of the steam production apparatus 101 of FIG.
Is the same as the superheated section 3 of However, the boiler unit 102
The evaporator 111 is heated by a burner flame 112 to generate steam. The configuration in which the level meter LC, the electromagnetic valve for water supply SV1 and the electromagnetic valve for drainage SV2 are connected to the evaporator 111 is the same as that in FIG. The steam production apparatus 201 of FIG. 4 does not have a superheating section, and has only a boiler section 202. The boiler section 202 includes an evaporator 211
In this type, a sheathed heater 212 for electric resistance heating is provided. Level meter L for evaporation tube 211
C, solenoid valve for water supply SV1 and solenoid valve for drainage SV2
Are connected in the same manner as in FIG. In such a type of the evaporators 111 and 211, in the case of a compact type having a relatively small capacity, drainage and water supply do not take much time, and when the evaporators 111 and 211 are not operated, the evaporators 111 and 211 are not used.
Can be left empty.

When the heating element is constituted by the multilayer laminated structure so as to increase the heat transfer area, the volume of the liquid in the boiler portion becomes extremely small, and drainage and water supply are completed in several tens of seconds.
There is no problem even if the vehicle is empty when not driving. The structure of such a heating element will be described with reference to FIGS.
In addition, although the structure of a heating element differs in size, it is preferable to use the same shape in the boiler part 2 and the superheating part 3.

As shown in FIG. 5, a first metal plate 531 and a flat second metal plate 532 bent in a zigzag mountain shape are alternately laminated to form a cylindrical laminated body as a whole. As a material of the first metal plate 531 and the second metal plate 532, a martensitic stainless steel such as SUS447J1 is used.

As shown in FIG. 6, the first metal plate 531
Are arranged so as to be inclined by an angle α with respect to the central axis 534, and the peaks (or valleys) 533 of the first metal plates 531 adjacent to each other with the second metal plate 532 interposed therebetween intersect. It is arranged in. Then, the adjacent first metal plate 5
At the intersection of the peaks (or valleys) 533 in 31, the first metal plate 531 and the second metal plate 532 are welded by spot welding and joined to be electrically conductive.

After all, between the first metal plate 531 and the second metal plate 532 on the near side, the first small flow path 5 inclined by the angle α is provided.
35 is formed, and between the second metal plate 532 and the first metal plate 531 on the back side, the second small flow path 53 inclined by an angle -α
6, the first small flow path 535 and the second small flow path 53
6 intersect at an angle of 2 × α. Also, the first metal plate 53
On the surface of the first or second metal plate 532, a hole 537 is provided as a third small flow path for generating a turbulent flow of the fluid. Furthermore, the surfaces of the first metal plate 531 and the second metal plate 532 are not smooth, but are provided with fine irregularities 538 by satin finish or embossing. The unevenness 538 is negligibly small compared to the height of the peak (or valley) 533.

When a high-frequency current is applied to the exciting coils 13 and 33 to apply a high-frequency magnetic field to the heating elements 12 and 32, an eddy current is generated in the entire first metal plate 531 and the second metal plate 532, and , 32 generate heat. The temperature distribution at this time is an eyeball shape extending in the longitudinal direction of the first metal plate 531 and the second metal plate 532, and the central portion generates heat more than the peripheral portion,
This is advantageous for heating a fluid (liquid or vapor) which is going to flow in the central part.

As shown in FIG. 6, a first small flow path 535 and a second small flow path 536 that cross each other are formed in the heating elements 12 and 32, and diffusion between the periphery and the center is performed. Due to the presence of the hole 537 forming the third small passage, the first small passage 53
5 and the second small flow path 536 are also diffused in the thickness direction.
Therefore, these small flow paths 535, 536, and 537 cause macroscopic dispersion, dissipation, and volatilization of the fluid (liquid or vapor) throughout the heating elements 12, 32. In addition, micro-diffusion due to minute irregularities 538 on the surface,
Emission and volatilization also occur. As a result, the fluid (liquid or vapor) passing through the heating elements 12 and 32 becomes a substantially uniform flow,
A uniform contact opportunity between the first metal plate 531 and the second metal plate 532 and the fluid is obtained. As a result, uniform heating of the liquid or vapor is ensured.

It is preferable that the thickness of the metal plates 531 and 532 is 30 μm or more and 1 mm or less, and the frequency of the high-frequency current generated by the high-frequency current generator is in the range of 15 to 150 KHz. When the thickness of the metal plate is 30 μm or more and 1 mm or less, it is easy to supply electric power, and it is easy to secure a small flow path by processing a waveform or the like for obtaining a large heat transfer area. In addition, the frequency used is 15 KHz to 150
When it is in the range of KHz, copper loss of the exciting coil and loss of the switching element can be prevented. In particular, the frequency band having a small loss is 20 to 70 KHz. Further, it is preferable that the heat transfer area per cubic centimeter of the heating elements 12 and 32 is 2.5 square centimeters or more. Heat exchange efficiency can be increased by stacking metal plates so that the surface area per cubic centimeter of the heating elements 12 and 32 is 2.5 square centimeters or more, more preferably 5 square centimeters or more. Further, it is preferable that the amount of fluid to be heated per square centimeter of the surface area of the heating element 8 is 0.4 cubic centimeter or less. When the amount of fluid per square centimeter of the surface area of the heating elements 12 and 32 is 0.4 cubic centimeter or less, and more preferably 0.1 cubic centimeter or less, rapid response of heat transfer to the fluid is obtained.

In the heating by the heating element having the above-described structure, the conversion efficiency from electric energy to heat energy is 9%.
It has been confirmed that it is as high as 2%. For example, 10
0mm diameter, length 200mm, surface area 2.2-6.2m ²
When the heating elements 12 and 32 are used, the thickness of the fluid (1 cm
⁽ Amount of water film per ³ ) is extremely thin as 0.5 to 0.2 mm, and the metal plates 531 and
Since 532 is also thin, the temperature difference is extremely small and heat transfer can be promptly promoted. Therefore, even if the superheater 3 is compact, a large amount of superheated steam can be generated.

FIGS. 7 to 10 show other heating elements used in the electromagnetic induction heating section. The heating elements of FIGS. 5 and 6 have excellent heating efficiency, but are not limited thereto. As shown in FIG. 7, even with a cylindrical heating element 501 having a cross section formed by crossing metal plates into a lattice shape, electromagnetic induction heating is possible,
The amount of liquid in the boiler is reduced. As shown in FIG. 8, even with a heating element 502 in which a single metal plate is wound into a coil shape having a gap between them, electromagnetic induction heating is possible and the amount of liquid in the boiler section is reduced. As shown in FIG. 9, even with the heating element 503 packed with a metal scourer, electromagnetic induction heating is possible, and the amount of liquid in the boiler section is reduced. Further, as shown in FIG. 10, even with the heating element 504 having a large number of through holes opened in the axial direction of the conductive ceramic cylinder, electromagnetic induction heating is possible, and the amount of liquid in the boiler section is reduced.

The exciting coils 13 and 33 are preferably formed by twisting litz wires, and are wound around the outer circumference of the tubes 11, 31 or wound and embedded in the thickness of the tubes. . The tubes 11 and 31 hold the exciting coils 13 and 33, define a fluid passage, and generate heat in the passage.
Because it accommodates 2, 32, corrosion resistance, heat resistance,
It is made of a non-magnetic material that has pressure resistance. Specifically, an inorganic material such as ceramic, a resin material such as FRP (fiber reinforced plastic), a fluororesin, a non-magnetic metal such as stainless steel, or the like is used, but ceramic is most preferable. The heating elements 12 and 32 are preferably, but not limited to, martensitic stainless steel which is a ferromagnetic conductive material and has excellent corrosion resistance. SUS304 which is a nonmagnetic or weak magnetic conductive material may be used, or carbon or a carbon compound (ceramic) which is a nonmagnetic conductive material
Can also be used.

The illustrated example shows a superheated steam 100 at atmospheric pressure.
Although the apparatus can be a non-oxygen atmosphere in terms of%, it can also be an apparatus in which air, nitrogen or other gas is mixed with superheated steam to obtain a mixed gas in a high temperature thirst state. In this case, a structure may be adopted in which a predetermined heated gas is blown into the point a in FIG. Further, the case where water as a liquid is converted into superheated steam has been described, but the present apparatus can be applied to liquids of hydrocarbons having a boiling point other than water.

[0033]

[Example] 6.5 kg / Hr of steam generated from tap water
(At rated time), operating the steam production apparatus of FIG. 1 having the capability of using superheated steam temperature of 250 ° C. (at rated time) for several hours in a day, stopping and then operating for several hours the next day Was.

Since the water in the boiler is discharged every day when the operation is stopped, the impurity concentration of the liquid in the boiler is not concentrated, and the scale does not precipitate on the heating element in the boiler.

[0035]

As described above, according to the first aspect of the present invention, when the boiler section is emptied when the operation is stopped every day, the impurities concentrated in the boiler section are discharged.
Even without providing a control device such as a concentration meter in the boiler unit, daily operation can be continued without any trouble.

According to the second aspect of the present invention, even when the boiler section is empty, when the start button is operated, water is automatically supplied to the boiler section.

According to the third aspect of the present invention, even if continuous operation of the boiler section continues, the liquid in the boiler is discharged according to the water supply, so that long-time operation is possible.

According to the invention of claim 4, as the heating element,
By using a fluid that can be dispersed, diffused, diffused, and volatilized, heat exchange becomes extremely high and it can be installed in the middle of piping, so a large amount of steam can be obtained continuously with a compact device configuration. As much as possible, the amount of fluid in the boiler section is reduced, and the time required for completely discharging the liquid in the boiler section and the time from the sky to a predetermined liquid level are reduced. Further, according to the electromagnetic induction heating, there is almost no adhesion of scale to the heating element, and there is no need to check or replace the heating element even during long-term operation.

[Brief description of the drawings]

FIG. 1 is a diagram showing the equipment configuration of a steam production apparatus of the present invention.

FIG. 2 is a flowchart of the operation of the steam production apparatus of the present invention.

FIG. 3 is a view showing the configuration of another steam production apparatus according to the present invention.

FIG. 4 is a view showing the configuration of another steam production apparatus according to the present invention.

FIG. 5 is an overall perspective view of a heating element.

FIG. 6 is a detailed structural diagram of a heating element.

FIG. 7 is a structural view of another heating element.

FIG. 8 is a structural diagram of another heating element.

FIG. 9 is a structural diagram of another heating element.

FIG. 10 is a structural view of another heating element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steam production apparatus 2 Boiler part 4 Control part 11 Tube 12 Heating element 13 Excitation coil 18 Water supply system 19 Drainage system 42 Level meter (liquid level detection means) 43 1st electromagnetic on-off valve (1st automatic on-off valve) 44 2nd Electromagnetic on-off valve (second automatic on-off valve) 45 Controller 46 Operation box 46a Start button (operation means for starting) 46b Stop button (operation means for stopping) 531 First metal plate 532 Second metal plate 535 First Small channel 536 Second small channel 537 Third small channel

Claims (4)

[Claims] 1. A boiler section for heating a liquid into steam.
A liquid level detecting means for monitoring the liquid level of the boiler section; a first automatic opening / closing valve provided in a water supply system for supplying liquid to the boiler section; and a discharge system for discharging liquid in the boiler section. A second automatic on-off valve, and a control unit having an operation unit for starting or stopping, and controlling opening and closing of the first automatic on-off valve based on an output of the liquid level detection unit, wherein the control unit is When the operating means for stopping is operated, the first automatic opening / closing valve is closed and the second automatic opening / closing valve is opened so as to discharge all the liquid in the boiler section. . 2. The control section, when operating means for starting is operated, closes the second automatic on-off valve,
The steam production device according to claim 1, wherein the first automatic on-off valve is opened to allow a predetermined amount of liquid to enter the boiler unit. 3. The control section counts the number of times of opening and closing the first automatic on-off valve for supplying water to the boiler section for replenishment based on an output of the liquid level detecting means, and reaches a predetermined number of times of opening and closing. Then, the second automatic opening / closing valve is opened for a predetermined time to discharge a predetermined amount of liquid accumulated in the boiler section, and the first automatic opening / closing valve is opened to perform new water supply corresponding to the drainage amount. Steam production equipment. 4. The boiler section includes a tube, an exciting coil wound around the tube, and a conductive material formed with a large number of passages while generating heat by a change in a magnetic field generated by the exciting coil. The hot steam producing apparatus according to any one of claims 1 to 3, comprising a heating element.