JPH03204501A - Steam generating device of electrical heating type - Google Patents

Abstract

PURPOSE:To carry out scale removal for the scale adhering to the circumferential wall of an evaporation tank in the same way as for the scale adhering to the bottom wall face by providing the evaporation tank for storing water to be evaporated and electrical heating means which heats and evaporates the water in the evaporation tank and in stalling that electrical heating means on the bottom wall face and circum ferential wall face of the evaporation tank. CONSTITUTION:The water stored in an evaporation tank 1 is heated and evaporated by a bottom wall face heater 8 and a circumferential wall face heater 11, and the steam is supplied to a steam chamber 5 through a steam supply pipe 4. As the opera tion is continued, scale 10 adheres to the bottom wall face 1a and circumferential wall face 1b of the evaporation tank 1, but it is possible to remove satisfactorily the adhering scale 10 from the bottom wall face 1a and circumferential wall face 1b by repeating expansion and contraction of the bottom wall face 1a and circumferen tial wall face 1b caused by repeating the increase and decrease in the electric power supplied to the bottom wall face heater 8 and circumferential wall face heater 11. Lumps 10 of the scale that is removed is crushed by balls 9 that flow with the convec tion flow of the stored water and are discharged through a drain pipe 3 by a drain valve V2.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electrically heated steam generator used in steam saunas, steam heating, and the like.

<Prior Art> FIG. 5 is a schematic diagram of a conventional electrically heated steam generator.

As shown in the figure, a water supply valve V is installed on the bottom wall surface 1a of the evaporation tank l.
A water supply pipe 2 equipped with , and a drain pipe 3 equipped with a drain valve V are connected. A steam supply pipe 4 extends from the top plate of the evaporation tank 1 and communicates with a steam chamber 5. A temperature sensor 6 is provided in the steam chamber 5. A water level detection chamber 7 is provided in communication with the upper and lower parts of the evaporation tank 1, and three float switches S+, Sx, and Ss are provided inside the chamber 7. A spiral heater 8 is provided on the outside of the bottom wall surface 1a of the evaporation tank 1 so as to cover almost the entire surface of the bottom wall surface 1a. Inside the evaporation tank 1, balls 9 are housed for crushing exfoliated scale. The specific gravity of this pole 9 is almost the same as the specific gravity of water.

The lower float switch S1 is for detecting the lower operating limit level L1 of the water level in the evaporator tank 1, the eight middle float switches are for detecting the upper operating limit level L2, and the upper float switches S, Detects the cleaning level L3 when cleaning the inside of the evaporation tank 1.

Next, the operation of the above-mentioned conventional electrically heated steam generator will be explained.

When the operation starts, the water supply valve v1 opens and water is supplied to the evaporation tank 1 via the water supply pipe 2. The water level is at the lower operating limit level L
When it reaches 1, the lower float inch SI becomes ONI,
, energization of the heater 8 is started based on the ON signal. The water level of the stored water in the evaporation tank 1 is at the operating upper limit level L
When it reaches 2, the middle float switch S2 turns on,
Based on the ON signal, the water supply valve v1 is closed, and the water supply to the evaporation tank 1 is stopped.

The water stored in the evaporation tank 1 is heated and evaporated by the heater 8 , and steam is supplied to the steam chamber 5 via the steam supply pipe 4 . When the temperature detected by the temperature sensor 6 provided in the steam chamber 5 reaches the upper limit temperature determined by the set temperature, the heater 8
When the lower limit temperature is reached, the current is increased.

Further, when the water level decreases due to evaporation and falls below the lower operating limit level L1, the lower float switch S is set to 0FFL, and the water supply valve V1 is opened based on the OFF signal, and water supply to the evaporation tank 1 is resumed. When the middle float switch S2 is turned on with this water supply, the water supply is stopped. In other words, the water level in the evaporation tank 1 is the lower operating limit level L1 and the upper operating limit level L.
2, and steam is generated in this state.

Ions such as Ca'' contained in the water stored in the evaporation tank 1 are precipitated by heating by the heater 8, and are deposited as scale lO on the inner wall surface of the evaporation tank 1.
Evaporation tank 1
The scale 10 repeats expansion and contraction, and as a result, the attached scale 10 is peeled off from the inner wall surface. The balls 9, which are flowing with the convection of the stored water, crush the flaked chunks of scale 10.

When the operation is stopped, the power supply to the heater 8 is stopped, and the water supply valve V is turned off to clean the evaporation tank 1.

Open and supply water. This water supply raises the water level to cleaning level L.
When it reaches 3, the upper float switch S.

ONL, based on the ON signal, closes the water supply valve (1) and opens the drain valve (2) to discharge the stored water containing the scale 10 to the outside via the drain pipe 3.

<Problems to be Solved by the Invention> In the conventional electrically heated steam generator, measures are taken to prevent the scale 10 from peeling off as described above, but this alone is insufficient.

That is, the scale 10 is peeled off by repeated expansion and contraction of the evaporation tank 1. Although the expansion and contraction tends to occur mainly on the bottom wall surface 1a of the evaporation tank 1, which is directly heated by the heater 8, This does not occur much on the peripheral wall surface 1b which is not a heating surface. Therefore, although the scale 10 is easily peeled off from the bottom wall surface 1a, it is difficult to peel off from the peripheral wall surface 1b, and the scale 10 is easily deposited thereon. Note that as the accumulation of scale 10 progresses, heating efficiency decreases, which is not preferable.

The present invention was devised in view of the above circumstances, and an object of the present invention is to ensure that scale adhering to the peripheral wall of an evaporation tank can be peeled off as well as from the bottom wall. do.

Means for Solving the Problems> In order to achieve the above objects, the present invention has the following configuration.

The electrically heated steam generator of the present invention includes an evaporation tank that stores water for steam generation, and an electric heating means that heats and evaporates the water in the evaporation tank, and the electric heating means It is characterized in that it is provided on the bottom wall side and the peripheral wall side of the evaporation tank, respectively.

<Function> According to the above configuration, since the electric heating means is provided not only on the bottom wall surface of the evaporation tank but also on the peripheral wall surface, the expansion and contraction of the inner wall surface of the evaporation tank due to changes in the heating capacity of the electric heating means is minimized. It becomes large on the peripheral wall surface as well as on the wall surface.

<Example> Hereinafter, an example of the present invention will be described in detail based on the drawings.

Figure 1 is a schematic diagram of the electrically heated steam generator according to the first embodiment.

In Fig. 1, 1 is the evaporation tank, 1a is the bottom wall surface of the evaporation tank L, 1b is the peripheral wall surface, 2 is the water supply pipe, ■ is the water supply valve, 3 is the drain pipe, v2 is the drain valve, 4 is the steam supply pipe , 5 is a steam chamber, 6 is a temperature sensor, 7 is a water level detection chamber, Sl is the lower limit level of operation L
1, S2 is the middle float switch that detects the operating upper limit level L2, S3 is the upper float switch that detects the cleaning level L3, 8
9 is a heater provided outside the bottom wall surface 1a of the evaporation tank 1;
@ is the ball for crushing the scale, and lO is the scale. Since these structures are similar to those of the conventional example explained in FIG. 5, the same reference numerals are given here, and the explanation thereof will be omitted.

In this embodiment, in addition to providing a heater 8 as an electric heating means on the bottom wall surface 1a of the evaporation tank 1, a heater 11 is also provided in a spiral manner on the outside of the peripheral wall surface 1b of the evaporation tank 1. ing. Hereinafter, in order to distinguish between these heaters 8 and 11, the heater 8 on the bottom wall surface 1a will be referred to as the bottom wall heater 8, and the heater 11 on the peripheral wall surface 1b will be referred to as the peripheral wall heater 11.

FIG. 2 is a block circuit diagram of a control system according to the first embodiment.

The bottom wall heater 8 and the peripheral wall heater 11 are each connected to a commercial power source 14 via a power control section 12.13 that performs phase control using a tritic and a thyristor. The input terminals of the controller 15 are the lower float switch S+-the middle float switch S! , an upper float switch S, and a temperature sensor 6 are connected, as well as an operation switch 16 and a temperature adjustment key 17 provided on a remote control device (not shown) attached to the steam chamber 5. Further, the output terminal of the controller 15 is connected to a water supply valve V2, a drain valve (2), and a power control section 12.13.

Next, the operation of the electrically heated steam generator of this embodiment will be explained.

When the operation switch 16 is pressed, the controller 15 opens the water supply valve v1 and drives a water supply pump (not shown) provided in the water supply pipe 2. As a result, water supply to the evaporation tank 1 via the water supply pipe 2 is started. Then, when the water level of the stored water in the evaporation tank 1 reaches the operating lower limit level Ll,
Lower float switch S is ONL, controller 1
5 controls the phase of the power control unit 12.13 to a state where the conduction angle is large based on the ON signal, and the bottom wall heater 8
and supplies large power to the peripheral wall heater 11. This starts heating the stored water.

When the water level reaches the operating upper limit level L2, the middle float switch S turns ON, and the controller 15 turns it ON.
Based on the signal, the water supply pump is stopped and the water supply valve is activated.■
1 to stop the water supply to the evaporation tank 1.

The water stored in the evaporation tank 1 is heated and evaporated by the bottom wall heater 8 and the peripheral wall heater 11, and steam is sent to the steam supply pipe 4.
It is supplied to the steam chamber 5 via.

When the temperature detected by the temperature sensor 6 provided in the air chamber 5 reaches the upper limit temperature determined by the temperature setting by the temperature adjustment key 17, the controller 15 controls the power control unit 12.1.
3 is phase-controlled so that its conduction angle is small, and small electric power is supplied to the bottom wall heater 8 and the peripheral wall heater 11. As a result, when the steam temperature falls and the temperature detected by the temperature sensor 6 reaches the lower limit temperature, the controller 15 phase-controls the power control section 12.13 to a state where the conduction angle is large, and the bottom wall heater 8 and the peripheral wall heater 11. In this way, the steam temperature is maintained approximately at the set temperature.

On the other hand, when the water level of the stored water in the evaporation tank 1 decreases due to evaporation and falls below the lower operating limit level L1, the lower float switch S1 goes to 0FFL, and the controller 15 opens the water supply valve ■ based on the OFF signal. At the same time, the water supply pump is driven and water supply to the evaporation tank 1 is restarted. Then, when the middle float switch St is turned on, the controller 15
stops water supply based on the ON signal. As a result, as in the conventional example, the water level in the evaporator tank 1 is at the lower operating limit level L.
1 and the operating upper limit level L2, and steam is generated in that state.

As the operation continues, the bottom wall surface 1a and the peripheral wall surface 1 of the evaporation tank 1
Although the scale 10 adheres to the area b, the power supply to the bottom wall heater 8 and the peripheral wall heater 11 as described above must be increased.
As the bottom wall surface 1a and the peripheral wall surface 1b repeatedly expand and contract, the peripheral wall surface 1 also expands from the bottom wall surface 1a.
The adhering scale 10 can also be peeled off well from b. Then, the peeled chunks of scale 10 are crushed by the balls 9 that are flowing together with the convection of the stored water.

The controller 15 counts the cumulative operating time, and when this reaches a certain time, or when the operating switch 16 is pressed again to perform a stop operation, the cleaning mode is executed. That is, the output of the trigger signal to the thyristor in the power control unit 12, I3 is stopped to stop the power supply to the bottom wall heater 8 and the peripheral wall heater 11, and the water supply valve 1 is opened to drive the water supply pump. As a result, water is supplied to the evaporation tank 1 until the water level reaches the cleaning level L3. When the cleaning level L3 is reached, the upper float switch S turns ONL and controller 1
5 stops the water supply pump based on this ON signal, closes the water supply valve V, and closes the drain valve V! By opening the drain pipe 3, the stored water containing the crushed scale 10 is discharged to the outside through the drain pipe 3.

When the controller 15 counts up the time required to complete the drainage (this is known in advance), it restarts the operation in the steam generation mode.

Figure 3 is a schematic diagram of the main parts of the electrically heated steam generator according to the second embodiment, and Figure 4 is a circuit diagram of the main parts of its control system.

The second embodiment has a bottom wall heater 8 and a peripheral wall heater 11.
Each of these is divided into two parts.

That is, the bottom wall heater 8 is divided into a first bottom wall heater 8a and a second bottom wall heater 8b, and the peripheral wall heater II is divided into a first peripheral wall heater 11a and a second peripheral wall heater Ilb. ing. On the bottom wall surface 1a of the evaporation tank 1, a first bottom wall heater 8a with an upward-sloping symbol and a second bottom wall heater 8b with a downward-sloping symbol are provided in an alternating double spiral shape. On the peripheral wall surface 1b, a first peripheral wall heater lla with a horizontal direction symbol and a second peripheral wall heater llb with a vertical direction symbol are provided.
It is provided in a double spiral shape with alternating lines.

As shown in FIG. 4, the first bottom wall heater 8a and the first peripheral wall heater lla are connected in series, and the relay switch 1
The second bottom wall heater 8 b and the second peripheral wall heater Ilb are connected in series and connected to the commercial power source 14 via a relay switch 20 .

Relay coil 1 to open and close each relay switch 19.20
9a and 20a are connected to the controller 15.

The other configurations are the same as those in the first embodiment, so illustration and description will be omitted.

Next, the operation of the electrically heated steam generator of the second embodiment will be explained.

Until the temperature detected by the temperature sensor 6 reaches the upper limit temperature, the controller 15 controls both relay coils 19a and 2.
Excite 0a and turn on both relay switches 19 and 20.
I have to. As a result, both the first bottom wall heater 8a and the second bottom wall heater 8b, and the first peripheral wall heater lla
Electric power is supplied to both the second peripheral wall heater llb and the second peripheral wall heater llb to increase their heating capacity.

When the detected temperature reaches the upper limit temperature, the controller 15
One relay coil 20a is demagnetized and the relay switch 2
0 is 0FFL, and only the relay switch 19 is in the ON state. As a result, power is supplied only to the series circuit of the first bottom wall heater 8a and the first peripheral wall heater lla, reducing its heating capacity.

When the detected temperature reaches the lower limit temperature, the controller 15
Energize the relay coil 20a again and turn on the relay switch 20.
Turn on the four heaters 8a.

8b, Ila, and llb to increase their heating capacity.

By repeating such large and small changes in heating capacity,
As in the first embodiment, the bottom wall surface 1a and the peripheral wall surface 1b are repeatedly expanded and contracted, and the adhered scale 10 can be effectively separated from both the bottom wall surface 1a and the peripheral wall surface 1b.

By the way, in the second embodiment, since power control is performed by a relay circuit, the circuit configuration is simpler than that in the first embodiment.

The present invention is not limited to the above-mentioned embodiment, and the heating capacity may be switched in three stages: high, low, and zero as a control form of the controller 15 during steam generation operation. That is, there is a high capacity state in which both relay switches 19 and 20 are turned on until a predetermined temperature below the set temperature is reached, a small capacity state in which one relay switch 2o is turned off when the temperature reaches the predetermined temperature or above, and It may also be possible to switch to a zero capacity state in which both relay switches 19 and 20 are turned off when the
The number of divisions of the bottom wall heater 8 and the peripheral wall heater 11 is not limited to two, but may be three or more.

<Effects of the Invention> As explained above, according to the present invention, the heater is provided not only on the bottom wall surface of the evaporation tank but also on the peripheral wall surface, so that the peripheral wall surface of the evaporation tank can be greatly expanded and contracted in the same way as the bottom wall surface. As a result, scale adhering to the peripheral wall surface can be peeled off as well as from the bottom wall surface.

[Brief explanation of drawings]

1 and 2 relate to a first embodiment of the present invention, in which FIG. 1 is a schematic configuration diagram of an electrically heated steam generator, and FIG. 2 is a block circuit diagram of a control system. Figures 3 and 4 relate to a second embodiment of the present invention, where Figure 3 is a schematic configuration diagram of the main parts of an electrically heated steam generator, and Figure 4 is a circuit diagram of the main parts of the control system. . FIG. 5 is a schematic diagram of a conventional electrically heated steam generator. ■...Evaporation tank, 1a...Bottom wall surface, lb...
・Peripheral wall surface, 8...Bottom wall surface heater, 11...
・Surrounding wall heater.

Claims (1)

[Claims] (1) It has an evaporation tank that stores water for steam generation, and an electric heating means that heats and evaporates the water in the evaporation tank, and the electric heating means is connected to the bottom wall side and the periphery of the evaporation tank. An electrically heated steam generator characterized in that it is provided on each side of the wall.