WO2012077832A2

WO2012077832A2 - Active power-controlled electric boiler and operating method thereof

Info

Publication number: WO2012077832A2
Application number: PCT/KP2011/000024
Authority: WO
Inventors: Munchol Bong
Original assignee: Munchol Bong
Priority date: 2010-12-06
Filing date: 2011-07-12
Publication date: 2012-06-14
Also published as: WO2012077832A3

Abstract

The active power controlled electric boiler (100) includes a steam generating tank (119), inner space of which is divided by the dividing walls (112') into a first space (111) and a second space (112); electrodes (113) disposed in the first space (111); a blow-off motor valve (121); an isobaric motor valve (122); an underpressure valve (123); a water supply device (130) including a water pail (131), an isobaric pipe (132), a water supply pipe (133), an intake pipe (134) and a water supply motor regulating valve (135); a pressure relief valve (125); an explosion valve (126); and a control panel (140). The motor valves (121, 122, 135) are configured to be automatically controlled by the control panel (140) so as to allow the water of the first space (111) to flow into the second space (112) or vice versa to regulate the amount of the water of the first space (111), thereby actively regulating the amount of the electric current flowing between the electrodes, so that the output of the steam and the power consumption are optimized, and the safety of the electric boiler is ensured.

Description

ACTIVE POWER-CONTROLLED ELECTRIC BOILER AND OPERATING METHOD THEREOF Technical Field

This invention relates to an electric boiler for generating steam by electricity, and more particularly, to an active power controlled electric boiler which can actively regulate an electric power applying thereto in order to regulate an output of the steam according to a capacity of a steam consuming unit, and an operating method thereof.

Background art

In general, most of the electric boilers for generating steam or producing hot water are in use of resistance heating and electrode heating.

The conventional electric boilers regulate the steam production by means of turning it on or off.

Other conventional electric boilers include power supply controlling devices which can adjust the electric voltage and current applying to resistances or electrodes in the boilers using a number of the electric and electronic devices, such as transformers, voltage level controllers, DC/AC or AC/DC converters and so on.

These conventional electric boilers have some drawbacks. For instance, they cannot actively control the electric power according to various capacities of the steam consuming equipments, thereby the electric energy loss due to the equal steam production were inevitable.

And, in these conventional electric boilers, there need a number of electric and electronic devices for controlling the voltage and current supplying to the boilers, thereby increasing costs for manufacturing of boilers. Not only that, most of the controlling methods are limited to the step-control modes of electric power, thereby they are not flexible in controlling the electric power and also has low economic effectiveness. In addition, they have drawbacks such as the energy loss due to thermal inertia of boilers, electric power loss due to unnecessary preparation of high pressure for supplying the produced steam, and degradation of the steam quality due to a sudden fluctuation of the electric voltage and frequency of the power source, which cause deterioration of the thermal and energy efficiencies.

Disclosure of the Invention

In order to overcome the above drawbacks inherent in the prior arts, it is an object of the present invention to provide an active power controlled electric boiler including a double space-structured steam generating device, simple motor valves for controlling the steam production, a control panel for the operation of the valves and a water supplying device, and an operating method thereof, so that the electric power is automatically controlled according to the variable capacities of the steam consuming units with the easy and flexible control modes.

Simple details of the invention

The above object of the present invention is accomplished by providing an electric boiler comprising a steam generating device, a pressure control device, a control panel, a safety device and a sensor device.

The steam generating device comprises a double space-structured steam generating tank and electrodes. The inner space of the steam generating tank is divided by dividing walls mounted around a circumference of the tank into a first space capable of submerging the electrodes and a second space in fluid communication with the first space. The dividing walls are upward welded to the inner wall of the steam generating tank so as to provide a tight seal between upper parts of the first and second spaces, and downward extended to a position lower than the levels of bottoms of the installed electrodes but spaced apart from a bottom of the tank, so that in these configuration the first and second spaces can be in fluid communication each other. And a size of the second space is so large to receive all the water filled in the first space when the electric boiler generates the maximum output of the steam.

The pressure control device comprises an isobaric motor valve configured to enable upper parts of the first and second spaces to be connected or blocked off each other, a blow-off motor valve configured to enable an upper part of the second space and the atmosphere to be connected or blocked off each other, an underpressure valve enabling an upper part of the first space and the atmosphere to be connected or blocked off each other, and a manometer configured to measure an inside pressure in the first space.

The isobaric motor valve allows the water filled in the first space to flow into the second space or vice versa, by differences of the pressure or water levels made between the above first and second spaces when closing or opening it, thereby regulating an amount of the water of the first space in which the electrodes are submerged to adjust an amount of the electric current flowing between the electrodes.

The blow-off motor valve, when an abnormal condition occurs within the steam generating valve, is opened and accordingly it is made a difference in the pressures between the first and second spaces, thereby allowing all the water filled in the first space to flow into the second space, and as a result the amount of the electric current decreases to the initial state where the electric current is zero.

And, the underpressure valve is a non-return valve. It, in the case of a stoppage or shutting off of power supply, is opened by the underpressure made when the steam filled in the first space is condensed, thereby allowing the first space to be connected with the atmosphere, and simultaneously, owing to the underpressure made when the steam filled in the second space is condensed, the whole water filled in the first space flows into the second space in a moment, so that the amount of the electric current flowing between the electrodes decreases to zero. Then, the electric current doesn't flow through the electrodes, even if it starts power supply again.

The safety device comprises a pressure relief valve and an explosion valve, which are disposed at lower parts of the second space positioned lower than the bottoms of the electrodes. Once it is made an overpressure within the steam generating tank owing to a failure of function of any one of the above valves in good order, the pressure relief valve is opened or/and the explosion valve is exploded, thereby the whole water in the steam generating tank discharges out of the steam generating tank so that the electric current flowing between the electrodes decreases to zero without any rise of pressure. The sensor device comprises a water gage configured to view a height of the water level in the first space, a water temperature sensor configured to measure a temperature of the steam generated in the first space, and a current sensor configured to measure an electric current flowing between the electrodes.

A datum level, by which are defined the upper parts and the lower parts of the first and second spaces, is just the water level of the first and second spaces when the amount of the water as much as needed practically for the maximum output of steam was put into the steam generating tank.

The water supply device comprises a water pail including a water hole and its stopple through which the water can be manually put into the steam generating tank, an isobaric pipe configured to supply the steam generated from the steam generating tank to the water pail, a water supply pipe configured to supply the water of the water pail to the steam generating tank, an intake pipe configured to suck up water from the water source to the water pail, and a water supply motor regulating valve configured to open or close the above pipes.

When supplying water to the steam generating tank, the water supply motor regulating valve is opened to close the intake pipe, with opening the isobaric pipe and the water supply pipe. At this time, some of the steam generated in the tank flow into the water pail, thereby with the aid of the increased steam pressure within the water pail, enabling the water filled in the water pail to flow into the steam generating tank by itself.

And, the water supply motor regulating valve carry a function such as regulating a degree of opening of the isobaric pipe, thereby regulating the amount of water supplied to the steam generating tank.

If there is no water in the water pail, the water supply motor regulating valve is closed to close the isobaric pipe and the water supply pipe, and to open the intake pipe, thereby with the aid of the underpressure made during the steam filled in the water pail being condensed, allowing the water to be sucked up from the water source into the water pail through the intake pipe, one end of which is submerged in the water source.

The control panel is equipped with one microprocessor or a number of microprocessors, which, on the basis of the measurements received from the temperature sensor and the current sensor and under a control principle named herein as "power-constant first and temperature-constant afterwards" automatically controls all the motor valves so as to regulate the electric power applying to the electrodes in order to keep the temperature of the first space at a predetermined temperature. And when the measured amount of the electric current exceeds the predetermined amount, the control panel controls all the motor valves to decrease the electric power applying to the electrodes so that it ensures the safety of the power supply lines for the electric boiler. And in the case of failure of function of any one of the above motor valves, the control panel allows the steam generating device to be returned to the initial state so that the operator can start to operate the electric boiler at beginning again.

The above principle of "power-constant first and temperature-constant afterwards" hereinabove should be understood that first of all, the control panel controls all the motor valves so as to increase the electric power as long as reaches a predetermined electric power, and afterwards once it exceeds a predetermined temperature, so as to decrease or increase the electric power in order to keep the temperature of the first space at the predetermined temperature.

Advantageous effects

As mentioned above, the above mentioned active power controlled electric boiler according to the present invention is capable of regulating the amount of the electric current flowing between the electrodes and regulating the amount of the water supply to the steam generating tank automatically so that the output of the steam is optimized, together with minimizing of the power consumption.

The electric boiler further has advantages that the steam is generated within tens of seconds by reason of applying the electric power to the electrodes first of all and then providing continuous water supply to the boiler for generating a predetermined electric power, and that there occurs no electric spark at a power supply switch when turn boiler on or off.

The electric boiler has further advantages that it ensures a constant quality and a constant amount of the steam production independent of variations of voltage and frequency of the power source, and ensures its safe operation even at any abnormal condition such as owing to a power stoppage, an overvoltage and an overpressure. Further, the electric boiler is about one fifth again as large as that of the conventional boilers for the same capacity, thereby it is possible to install it close by the side of the steam consuming facilities so that a heat loss and an unneeded pressurization can be minimized. Further it is reduced in the power consumption by 30~50% as compared with the conventional boilers for the same capacity.

Brief description of Drawings

The above mentioned object, features and advantages of the present invention will be more clearly understood in the following detailed description in conjunction with the accompanying drawings, in which

Fig. 1 is a perspective view of an electric boiler according to an exemplary embodiment of the present invention.

Fig. 2 is a structural view of the electric boiler according to the embodiment.

Fig. 3 is a schematic view for showing the starting working process of the electric boiler according to the embodiment of the present invention.

Fig. 4 is a schematic view for showing the power regulating process of the electric boiler by means of the isobaric motor valve and the water supply motor regulating valve as long as the measured electric power reaches the predetermined amount.

Fig. 5 is a schematic view for showing the power regulating process of the electric boiler by means of the isobaric motor valve and the water supply motor regulating valve when the measured electric power exceeds the predetermined amount.

Fig. 6 is a schematic view for showing a process discharging the steam and water through the blow-off motor valve in the case of an abnormal condition.

Fig. 7 is a schematic view for showing a process discharging the water and steam through the pressure relief valve or/and the explosion valve in the case of an abnormal condition owing to the control panel or/and any one of the motor valves being not functioning in good order. Fig. 8 is a schematic view for showing the working principle of the water supply device when supplying the water to the electric boiler.

Fig. 9 is a schematic view for showing the working principle of the water supply device when sucking up the water to the water pail.

5 Fig. 10 is a flow chart for showing the control principle of the control panel.

Best mode for carrying out the above invention

Hereinafter, an active power controlled electric boiler according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

10 First it will be understood that like reference numerals refer to the like elements throughout the drawings. Additionally, in the description, well known functions and structures will not be explained herein not to obscure the invention.

As shown in Fig. 1 and Fig. 2, the electric boiler 100 according to the embodiment of the present invention comprises a steam generating device 110, a pressure control device l § 120, a water supply device 130, a control panel 140, a safety device comprising a pressure relief valve 125 and an explosion valve 126, and a temperature sensor and a current sensor (not shown).

The steam generating device 110 comprises a double space-structured cylindrical steel steam generating tank 119 and electrodes 113.

0 The inner space of the steam generating tank 1 19 is divided by the dividing walls

112' disposed around the inner circumference of the steam generating tank 119 into a first space 111 where the electrodes 113 is positioned and a second space 112. The dividing walls 112' are upward welded with the inner wall of the steam generating tank 119 so as to provide a tight seal between the first and second spaces, and downward extended to a 5 position lower than a level of a bottom of the installed electrodes 113, preferably 10 mm lower than the level, but spaced apart from a bottom of the steam generating tank 119 in order to be in fluid communication through a gap formed between the first and second spaces. And the size of the second space 112 is so large as to receive all the water filled in the first space 111 when the electric boiler 100 generates a maximum output of the steam production.

The steam generating tank 119 further comprises power supply terminals 114, power supply lines 115, a steam outlet 116 and a water gage 117 for visual observation of a water level in the first space of the steam generating tank 119 (see Fig. 2).

The pressure control device 120 comprises a blow-off motor valve 121 configured to enable an upper part of the second space 112 and the atmosphere to be connected or blocked up each other so that the water and steam in the second space can be discharged out of the steam generating tank, an isobaric motor valve 122 configured to enable upper parts of the first and second spaces to be blocked up or connected each other so that the water in the first space can flow into the second space or vice versa, an underpressure valve 123 configured to enable an upper part of the first space 111 and the atmosphere to be connected or blocked up each other, and a manometer 124 configured to view the inner pressure in the first space 111 (see Figs. 1 and 2).

The safety device comprises a pressure relief valve 125 and an explosion valve 126, which are disposed at a lower part of the second space 112 positioned lower than the bottom of the electrodes 113, preferably 10mm and more lower. And a drain valve 118 is disposed at the middle of the bottom of the tank 119 (see Figs. 1 and 2).

The water supply device 130 comprises a water pail 131 including a water hole 13 Γ and its stopple, an isobaric pipe 132 configured to connect the water pail with the steam outlet 116, a water supply pipe 133 configured to connect the water pail with the steam generating tank 119, an intake pipe 134 configured to suck up water from the water source to the water pail, and a water supply motor regulating valve 135 configured to open or close the above pipes (132, 133, 134) (see Figs. 1 and 2).

The sensor device comprises a temperature sensor (not shown) configured to measure a temperature in the first space and a current sensor (not shown) configured to measure an electric current flowing between the electrodes.

It is provided with a control panel 140 which can automatically control the operation of the above motor valves (121 , 122, 135) by one or a number of microprocessors, on the basis of the measured temperature and current. Mode for the invention

The operation of the above structured electric boiler will now be explained.

First, it switches on the control panel 140 and supplies the electrical voltage to the electrodes, and in turn puts the control panel 140 in a manual controlling state, and opens the isobaric motor valve 122 and the blow-off motor valve 121. The operator enters the predetermined amounts of an electric power, a temperature and a limit current on the control panel 140. Then it opens the water supply motor regulating valve 135 and puts water through the water hole 131 Of the water pail 131 into the steam generating tank 119.

At this time, levels of water in the first and second spaces are same (see Fig. 3). The electric current flows between the electrodes 113 and starts to generate steam in the first space. When the generated steam discharges through the blow-off motor valve 121, it closes the blow-off motor valve 121 and the water hole 131 Of the water pail 131 , and then puts the control panel 140 in the automatic controlling state.

It continues to supply the water to the steam generating tank 119 through the water supply pipe 133 as long as the electrical power reaches the predetermined amount, so that the electric power is rising (see Fig. 4).

Once the electric power reaches the predetermined amount, it adjusts a degree of opening of the isobaric pipe 132 by means of the water supply motor valve 135 to regulate the water supply to the steam generating tank 119 according to variable amounts of the steam production, thereby changing the amount of the electric current flowing between the electrodes so that the output of the steam and the power consumption are optimized (see Fig. 4).

During the operation, when the electric power exceeds the predetermined amount and the measure temperature of the first space exceeds the predetermined amount, it closes the isobaric motor valve 122 in order to drop the temperature, thereby allowing the water of the first space 1 11 to flow into the second space 1 12 by the difference of the steam pressure made between the first and second spaces, so that the level of the water of the first space becomes lower, thereby reducing the amount of the currents flowing between the electrodes to decrease the electric power, and as a result the temperature falls (Fig. 5). Simultaneously, it closes the water supply motor valve 135 to close the isobaric pipe 132 and the water supply pipe 133, thereby cutting off the supply of the water to the steam generating tank 119.

Contrary to the above, when the temperature falls below the predetermined amount, it opens the isobaric motor valve 122, thereby allowing the water of the second space 112 to flow back into the first space 11 1 , together with opening the water supply motor valve 135 to open the isobaric pipe 132 and the water supply pipe 133, thereby allowing the supply of the water to the steam generating tank so that the electric power is rising again and as a result the temperature is rising again.

While the above processes repeat, the electric power applying across the electrodes is controlled to keep the temperature of the steam at the predetermined amount irregardless of fluctuations of the electric voltage and frequency of the power supplier.

If the electric power rises suddenly in excess of the predetermined amount for a sudden rising of the electric voltage or the other reason, and as a result an overpressure is made within the steam generating tank, it closes the isobaric motor valve 122 and opens the blow-off valve 121, thereby allowing the water and steam of the second space 112 to be discharged out of the steam generating tank through the blow-off valve 121 and the whole water of the first space to flow into the second space 112, so that the electric power is decreasing to zero (see Fig. 6).

When the power supply is shut off during operation, the underpressure valve 123 is opened under an underpressure made by the condensation of the steam filled in the upper part of the first space 11 1, and in turn by the underpressure made by the condensation of the steam in the second space 112, the water of the first space 1 1 1 flows into the second space 112, thereby reducing the amount of the electric current to zero so that the electric boiler returns to the initial working state.

If the control panel 140 or/and any one of the motor valves (121 , 122, 135) are not functioning in good order and as a result the electric power is so rising that an overpressure can be made within the steam generating tank, the pressure relief valve 125 or/and the explosion valve 126 is (are) opened or/and exploded, thereby allowing all the water and steam in the steam generating tank 1 19 to be discharged out of the steam generating tank (see Fig. 7). It is by reason that the pressure relief valve 125 and the explosion valve 126 are disposed at the lower part of the second space 112. Then the operator should operate the electric boiler from the beginning again.

The water supply device 130 is functioning as following:

Before the generation of the steam, it opens the water supply motor valve 135 by manual operation (it means the manual operation by the operator using the control panel 140) to open the isobaric pipe 132 and the water supply pipe 133. Then the water of the water pail flows into the steam generating tank 119 by a difference of the water level.

When it starts to generate steam, the water supply motor valve 135 is automatically controlled by the control panel 140. While the electric power reaches the predetermined amount, it opens the water supply motor valve 135, thereby allowing some of the produced steam in the tank to flow to the water pail 131 through the isobaric pipe 132 so that under the raised steam pressure, the water of the water pail 131 flows into the steam generating tank 119 through the water supply pipe 133 (see Fig. 8).

When the electric power reaches the predetermined amount, it adjusts a degree of opening of the isobaric pipe 132 to regulate the water supply to the steam generating tank, thereby keeping the temperature of the first space at the predetermined amount.

If the temperature rises over the predetermined amount or there is no water in the water pail, the water supply motor valve 135 is closed to close the isobaric pipe 132 and the water supply pipe 133, and to open the intake pipe 134. At this time, the water in the water source is sucked up through the intake pipe 134 into the water pail 131 with the aid of the underpressure made by the condensation of the steam in the water pail (see Fig. 9).

The control panel 140 includes one or a number of microprocessors which automatically control all the motor valves (121, 122, 135) so as to keep the temperature within the first space of the steam generating tank 1 19 at the entered temperature and not to exceed the entered limit current, using the predetermined electric power, the measured temperature and current, and using a limit current, and under the principle of "power-constant first and temperature-constant afterwards" (see Fig. 10). And, in the case of an abnormal condition, the control panel controls the above motor valves so as to let the steam generating device to be returned to the initial working state so that the operator can re-operate the electric boiler from beginning.

Although the preferred embodiment of the present invention has been disclosed for illustrative purposes, those skilled in the arts will appreciate that various modification, addition and substitution are possible, without departing from the scope and spirit of the invention as disclosed accompanying claims.

Claims

C l a i m s

1. Active power controlled electric boiler including:

5 - a steel cylindrical steam generating tank (119) of which the inner space is divided by dividing walls (1 12') disposed around the circumference of the steam generating tank into a first space (111) and a second device (112);

- electrodes (113);

- a blow-off motor valve (121 ) configured to allow an upper part of the second space I Q (1 12) and the atmosphere to be connected or blocked up each other;

- an isobaric motor valve (122) configured to allow the upper parts of the first and second spaces to be connected or blocked up each other;

- an underpressure valve (123) configured to allow an upper part of the first space (1 1 1 ) and the atmosphere to be connected and blocked up;

15 - a water supply device (130) including a water pail (131) having a water hole (131 '), an isobaric pipe (132) configured to connect the water pail with the steam generating tank, a water supply pipe (133) configured to connect the water pail with the steam generating tank, an intake pipe (134) configured to connect the water pail with the water source and a water supply motor regulating valve (135) configured to open or close the pipes (132, 133, 0 134)

- a pressure relief valve (125) disposed at a lower part of the second space (1 12);

- an explosion valve (126) disposed at the lower part of the second space (112);

- a temperature sensor configured to measure the temperature of the steam in the first space;

5 - a current sensor configured to measure the electric current flowing between the electrodes; and

-a control panel (140) configured to automatically control the motor valves (121 , 122,

135),

wherein the dividing walls (112') are upward welded with the inner wall of the steam generating tank (1 19) to provide a tight seal between the first and second spaces, and downward extended to a position lower than the bottoms of the electrodes (113), but spaced apart from the bottom of the steam generating tank so that the first and second spaces can be in fluid communication, and the size of the second space (112) is so large to receive the whole water of the first space where the electric boiler (100) generates the maximum output of the steam.

2. The active power controlled electric boiler of the claim 1, wherein the second space (112) may be disposed inside or outside the steam generating tank (119).

3. The active power controlled electric boiler of claim 1 or claim 2, wherein the dividing walls (112') are downward extended to a position 10mm and more lower than the bottoms of the electrodes (113).

4. The active power controlled electric boiler of any one of claims 1 to 3, wherein the pressure relief valve (125) and the explosion valve (126) are disposed at the lower part of the second space (112) positioned 10mm and more lower than the bottoms of the electrodes (113).

5. The active power controlled electric boiler of any one of claims 1 to 4, wherein one side of the isobaric pipe (132) is connected at the upper part of the water pail (131 ) and the other side connected with the steam outlet (116) through the water supply motor regulating valve (135).

6. The active power controlled electric boiler of any one of claims 1 to 5, wherein the degree of opening of the isobaric pipe (132) can be regulated by the water supply motor regulating valve (135).

7. The active power controlled electric boiler of any one of claims 1 to 6, wherein one side of the intake pipe (134) is connected at the upper part of the water pail (131) and the other side connected with the water source through the water supply motor regulating valve (135).

8. The active power controlled electric boiler of any one of claims 1 to 7, wherein one side of the water supply pipe (131) is connected with the bottom of the water pail and the other side connected with the lower part of the steam generating tank (1 19) through the water supply motor regulating valve (135).

9. An operating method of the active power controlled electric boiler of claims 1 to 8 comprising the steps of:

a) turning on the control panel (140) and applying the electric voltage to the electrodes (113);

b) putting the control panel (140) in the manual controlling state and opening the isobaric motor valve (122) and the blow-off motor valve (121);

c) entering the predetermined temperature, limit current and electric power;

d) opening the water supply motor regulating valve (135) to close the intake pipe (134), and to open the isobaric pipe (132) and the water supply pipe (133), thereby supplying the water to the steam generating tank (119) through the hole (13 ) of the water pail (131);

e) closing the blow-off motor valve (121) and the hole (13Γ) when it starts to discharge the steam through the blow-off motor valve, and then putting the control panel (140) in the automatic controlling state;

f) regulating the water supply by adjusting of the degree of opening of the isobaric pipe (132) to optimize the power consumption;

g) closing the isobaric motor valve (122) when the electric power exceeds the predetermined electric power, and then closing the water supply motor valve (135) to close the isobaric pipe (132) and the water supply pipe (133), and to open the intake pipe (134), thereby cutting off the water supply and sucking up the water from the water source into the water pail (131) through the intake pipe (134).

h) once the measured temperature drops below the predetermined amount, opening the isobaric motor valve (122) and the water supply motor valve(135) to close the intake pipe (134), and to open the isobaric pipe (132) and the water supply pipe (133), thereby supplying the water to the steam generating tank (119);

i) In the case of an abnormal condition, opening the blow-off motor valve (121) to discharge the water and steam out of the steam generating tank through the blow-off motor valve (121), and then starting to operate the electric boiler from the step b; j) in the case of power failure, opening the underpressure valve (123), thereby enabling the whole water of the first space (111) to flow into the second space (112), and then starting to operate the electric boiler from the step b again;

k) when it is made an overpressure within the steam generating tank owing to the failure of functioning of the control panel (140) or/and any one of the above valves, opening the safety valve (125), thereby discharging the water and steam out of the steam generating tank (119), and then starting to operate the electric boiler from the step b again; and

1) in the case of failure of functioning of the safety valve (125), exploding the explosion valve (126), thereby discharging the steam and water out of the steam generating tank (119), and then starting to operate the electric boiler from the step b again.

10. The operating method of the active power controlled electric boiler of claim 9, wherein the pipes (132, 133) and the intake pipe (134) are alternatively opened or closed by the water supply motor regulating valve (135).

11. The operating method of the active power controlled electric boiler of claim 9 or claim 10, wherein the motor valves (121, 122, 135) can be manually opened or closed by means of the control panel (140).

12. The operating method of the active power controlled electric boiler of claim 11, wherein the motor valves (121, 122, 135) are automatically controlled by the control panel (140) under the principle of "power-constant first and temperature-constant afterwards" so as to keep the temperature of the first space at the predetermined amount.

13. The operating method of the active power controlled electric boiler of claim 12, wherein the motor valves (121 , 122, 135) are further controlled by the control panel (140) so as to decrease the electric power when the measured electric current exceeds the predetermined amount.

14. The operating method of the active power controlled electric boiler of any one of claims 9 to 13, wherein the control panel (140) and all the motor valves (121, 122, 135) can be driven at a direct current 12V, 0.3 A.