JPH073123Y2 - Heat storage type electric boiler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an improvement in an electric steam boiler, and relates to a heat storage type electric boiler provided with a heat storage device for heating feed water.

(Prior Art) Generally, the steam load of a boiler fluctuates over a considerable range. For this reason, steam generators that generate large amounts of steam are equipped with steam accumulators and the like to prepare for peak loads.

However, in a boiler with a relatively small steam load, such as an electric steam boiler with a steam generation amount of approximately 10 kg / h to 300 kg / h, an accumulator or the like may not be provided simply as a measure against peak load. However, the boiler cost will be extremely high, and the economy will be lacking. For this reason, normally, instead of providing an accumulator or the like, a method of selecting a slightly larger boiler capacity and thereby covering a peak load is widely adopted.

However, in the electric steam boiler, if the boiler capacity is selected to be large considering the peak load as described above,
There is a problem that the basic charge and power receiving equipment cost will rise sharply.

In other words, Japan's electricity tariff system is a type of system in which the basic tariff rises with an increase in power receiving capacity. Therefore,
In order to reduce the front basic charge, it is necessary to make the power receiving equipment capacity as small as possible, and it is a significant disadvantage in terms of economic efficiency to select a slightly larger boiler capacity in consideration of the peak load as described above. Will be invited. This is because the basic fee must continue to be paid regardless of whether the boiler equipment is operating or stopped.

(Problems to be Solved by the Invention) The present invention has the above-mentioned problem in the conventional electric steam boiler, that is, in the electric steam boiler having a relatively small capacity, an accumulator or the like is provided only for the purpose of preventing the peak load. If it is installed, the boiler will be extremely expensive, and it will not be economical, and if the boiler capacity is selected to be large in order to prevent peak load, the basic electricity charge will increase significantly and operating costs will increase. If the reduction cannot be achieved, and if the boiler capacity is insufficient, the problems such as shortage of steam amount at the time of peak load, or reduction of the operating number of steam-using equipment will be solved. The electric steam boiler is equipped with a heat storage device for heating the feed water, which uses low-priced late-night power to store heat at night with a small power-receiving capacity facility, and when the peak load is reached, the water supply preheated by the heat storage device is used. Electric The present invention provides a heat storage type electric boiler which can sufficiently cope with a peak load of steam with a small power receiving capacity by supplying the steam type steam boiler and can achieve extremely excellent economical efficiency.

(Means for Solving the Problem) The present invention provides an electric steam boiler 8 equipped with an electric heater 9 and a peak load detecting device 12 for detecting a peak load; A heat storage device 1 that stores a heat storage mixture 5 composed of a heat storage material 6 and a heat medium 7; disposed inside the heat storage device 1 and connected in parallel to a boiler water supply pipe line 14 of the electric steam boiler 8. Heat exchange tube 13 and
The operation is controlled by the peak load detecting device 12, and the water supply control valve device 15 for supplying the boiler feed water 16 to the electric steam boiler 8 through the heat exchange pipe 13 at the time of the peak load is the basic constitution of the invention. is there.

(Operation) The heat storage electric heater 3 of the heat storage device 1 is operated at night, and heats the heat storage mixture 5 using inexpensive late-night power to store a desired amount of heat.

When the steam load is in the steady range, the boiler feed water 16 is sent directly to the electric steam boiler 8 through the pipe 14, and the boiler 8 is operated.

When the peak load state is reached, the peak load detection device 12 detects this, and the signal supplies the water supply control valve device 15 to operate.
By the operation of the water supply control valve device 15, the boiler water supply 16 is supplied to the electric steam boiler 8 through the heat exchange pipe 13 in the heat storage device 1, and by preheating the boiler water supply 16 using the heat storage, Correspondence is taken.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

The drawing is an overall system diagram of a heat storage type electric boiler according to the present invention. In the figure, reference numeral 1 is a heat storage device, which is provided with a heat storage tank 2, a heat storage electric heater 3, a temperature detector 4, and the like. The heat storage mixture 5 is stored in. The heat storage mixture 5 is composed of a heat storage material 6 and a heat medium 7 as described later. An electric steam boiler 8 is provided with an electric heater 9 for the boiler, a water level detection device 10, a heater control steam pressure detection device 11, a peak load detection device 12, and the like.

Reference numeral 13 denotes a heat exchange pipe for preheating feed water, which is disposed in the heat storage tank 2 and is a boiler water supply pipe line 14 of the electric steam boiler 8.
And are connected in parallel.

Reference numeral 15 is a water supply control valve device, which is operated by a signal from the peak load detection device 12, and when the peak load occurs, boiler water supply 16
Is switched to the side of the pipe line 17 and is supplied to the electric steam boiler 8 through the heat exchange pipe 13.

In FIG. 1, 18 is a water supply pump, 19 is a water supply tank, and 20 is a control panel.

Pellets of surface-crosslinked high-density polyethylene are used as the heat storage material 6 forming the heat storage mixture 5, which is a so-called latent heat storage type heat storage material. More specifically, the heat storage material 6 has a diameter of 1.5 to 5 mmφ, a specific gravity of about 0.9 to 1.0, and a softening temperature of about 80.
Surface-crosslinked high-density polyethylene pellets having a temperature of ° C to 200 ° C and a latent heat of 40 to 80 Kcal / kg are used. In this embodiment, pellets having a softening temperature of 133 ° C and a diameter of 0.5 to 1.5 mmφ are used.

Further, the pellet-shaped heat storage material 6 is enclosed in the heat storage tank 2 in the form of a so-called solid-liquid two-phase fluid together with the heat medium 7 for promptly transferring heat.

The surface cross-linking of the polyethylene pellets is performed by a so-called electron beam irradiation method or the like, and by performing the surface cross-linking treatment, only the surface layer portion of the polyethylene pellets is slightly cured. As a result, even if the inside of the pellet is in a molten state under heating, the surface layer portion remains solidified and the pellet shape is maintained. Even if the surface cross-linking treatment is applied, the latent heat of polyethylene is not significantly reduced.

The heat medium 7 forming the heat storage mixture 5 is used for speeding up the heat transfer of the heat storage material 6 as described above. Therefore, the heat medium 7 must have a specific gravity that allows the surface-crosslinked high-density polyethylene pellets to float, and further, does not impair the stability of the surface layer portion of the surface-crosslinked high-density polyethylene granules, and is chemically stable. A substance having a large heat capacity and excellent in fluidity and fluidity is advantageous. Water, ethylene glycol, and heat transfer oil almost meet the above requirements,
In this embodiment, ethylene glycol is used as the heat medium 7.

Further, the mixing ratio of the heat medium (ethylene glycol) 7 and the heat storage material 6 (surface-crosslinked high-density polyethylene granules) is preferably about 20 to 70 VOL%, and about 50% is heat storage, heat transfer, stirring fluidity, etc. It is the best from the point of.

Further, a so-called sheath heater is used as the heat storage electric heater 3 and is inserted into the heat storage tank 2 from the bottom of the heat storage tank 2. Power is supplied to the heat storage electric heater 3 mainly at midnight when the power charge is low, and the heat storage material 6 is heated.

Although not shown in the figure, a surface-crosslinking is performed by disposing a stirring device in the heat storage tank 2 and operating this continuously or intermittently to appropriately stir the solid-liquid two-phase fluid inside the tank. It is more desirable to make the high-density polyethylene pellets and ethylene glycol more evenly mixed and evenly store the heat in each pellet.

Further, although ethylene glycol is used as the heat medium 7 in the present embodiment, heat medium oil can be used as the heat medium 7.

Further, in the present embodiment, surface-crosslinked high-density polyethylene pellets are used as the heat storage material 6, but instead of this, crushed stone such as magnesia clinker having an appropriate particle size is used as the heat storage material 6 and the heat transfer oil. (Maximum operating temperature about 370 ° C)
The mixture with and may be the heat storage mixture 5.

Next, the operation of the heat storage type electric boiler according to this embodiment will be described.

The heat storage mixture 5 (solid-liquid two-phase fluid of ethylene glycol and surface-crosslinked high-density polyethylene pellets) stored in the heat storage tank 2 is heated by the heater 3 using night-time power at night to soften the surface-crosslinked high-density polyethylene. It is heated for a certain time at a temperature of (about 133 ° C.) or higher. As a result, the inside of the surface-crosslinked high-density polyethylene pellets is melted (the outer surface layer of the pellets is slightly softened, but the original shape is maintained), and the amount of heat corresponding to latent heat is accumulated and the pellets are stored. And so-called sensible heat storage is performed in ethylene glycol of the heat medium 3.

As described above, the polyethylene pellets in the heat storage mixture 5 have the outer surface layer in a solidified state even if the inside is melted, and the pellet shape is maintained. Also, the outer surface layer of the polyethylene pellets is slightly softened by heating, but since the outer peripheral surface of the pellets is wrapped with ethylene glycol in the heat storage tank 2, the pellets are never stuck to each other.

When the steam load is in a steady state, the boiler water supply 16 from the water supply tank 19 is the water supply pump 18 → the water supply control valve device 15 →
It is supplied to the electric steam boiler 8 via the water supply pipe 14 and heated by the heater 9.

The increase or decrease of the steam pressure is detected by the heater control steam pressure detection device (pressure switch) 11, and the detection signal S1
Thus, the operation of the heater 9 is controlled via the control panel 20.

The water level of the electric steam boiler 8 is detected by the water level detection device 10, and the operation of the water supply pump 18 is controlled via the control panel 20 by the detection signal Ws.

On the other hand, when a peak load state occurs due to a sudden increase in steam load, etc., the peak load detection device (steam pressure switch) 12 detects the decrease in steam pressure due to the peak load, and the control signal is detected by the control panel Sp. A water supply control valve device (three-way valve) 12 is operated via 20. As a result, boiler water supply 16
Is sent to the heat exchange tube 13 in the heat storage tank 2, where it is preheated by the heat storage mixture 5, and then sent to the electric steam boiler 8. As a result, a temporary peak load is dealt with.

Incidentally, the polyethylene pellets which have released latent heat by exchanging heat with the boiler feed water 16 through the heat exchange pipe 13 are in a state where the inside thereof undergoes a phase transition to a solid phase and remains in the ethylene glycol 3 in a floating state.

Further, in the present embodiment, the heat storage electric heater 3 is operated only at night, but the heater 3 may be appropriately operated when the steam load suddenly increases. Of course.

Further, in the present embodiment, the steam pressure switch 10 for controlling the electric heater 9 for the boiler and the peak load detecting device 12 for switching control of the water supply control valve device 15 are separately provided. , Heater 9 and water supply control valve device by one device
Needless to say, the configuration may be such that both 15 are controlled.

In addition, in the present embodiment, the water supply control valve device 15 is formed by a three-way valve, but it goes without saying that two control valves may be switched and used.

According to the calculation, when 500 liters of the surface crosslinked high-density polyethylene pellets and 300 liters of ethylene glycol are enclosed in the 1 m ³ heat storage tank 2, the latent heat storage amount of the surface crosslinked high-density polyethylene pellets is about 23,000 Kcal.

Assuming that the heat of 23,000 Kcal is stored within 8 hours of the midnight power hours, the capacity of the electric heater 3 for heat storage required for the heating is about 3.4 KW (23,000 Kcal / 860 Kal / h / 8 h).
Approximately 3.4 KW). However, heat loss is assumed to be zero.

On the other hand, when the peak steam load is covered by using the stored heat amount of 23,000 Kcal, if the heat transfer area of the heat exchange tube 13 is set to an appropriate value, the electric vapor of the converted evaporation amount of 100 kg / h is 100 kg / h. Boiler 8
By combining the latent heat storage device 1 with the above-mentioned latent heat storage device 1, a reduced evaporation amount of 150 kg / h for about 50 minutes
With a vaporization rate of kg / h, it is possible to cover the peak vapor load for about 80 minutes.

On the other hand, if an electric steam boiler 8 with a converted evaporation amount of 150 kg / h is installed to cope with the peak steam load, the required power of the heater 9 of the electric steam boiler 8 is about 94 KW. Become. That is, the required heater capacity is about 1.5 times as much as the required electric power (about 63 KW) of the boiler electric heater 9 when the converted evaporation amount is 100 kg / h. As a result, the basic charge is about 1.5 times the amount, and the payment is required every month, so the difference in the required electricity charges between the two becomes enormous.

(Effect of the Invention) In the present invention, the electric steam boiler 8 is provided with the heat storage device 1, and at the time of a peak load, the boiler feed water 16 is preheated by the heat storage of the heat storage device 1 to cover the peak load. Therefore, it is not necessary to select a large capacity as in the conventional electric steam boiler. As a result, it is possible to reduce the capacity of power receiving equipment, and it is possible to significantly reduce the basic charge.

In addition, since the small-capacity heat storage electric heater 3 is used to store the amount of heat of the peak load by using the late-night power, it is extremely advantageous in terms of power charges and the like, and is economical.

Further, the heat storage mixture 5 of the heat storage device 1 attached to the electric steam boiler 8 is provided with pellets of surface-crosslinked high-density polyethylene having a relatively high softening temperature (about 133 ° C.) and a large heat storage amount and ethylene glycol or heat. Formed from oil carrier,
Alternatively, since it is formed from crushed stone and a high-temperature heat transfer oil that have a relatively large amount of heat storage and are inexpensive, high heat storage density and heat transfer properties can be obtained. As a result, the heat storage device 1 can be significantly downsized and the manufacturing cost can be reduced, and the responsiveness at the time of peak load can be improved.

Moreover, by appropriately combining the size of the heat storage tank 2 and the size of the heat transfer area of the heat exchange tube 13, it is possible to cope with various peak load states. For example, the heat transfer area of the heat exchange tube 13 Can be easily formed to absorb a large peak load for a relatively short time, and to reduce a heat transfer area to absorb a small peak load for a relatively long time.

The present invention has excellent practical utility as described above.

[Brief description of drawings]

The drawings are system diagrams showing the configuration of a heat storage type electric boiler according to the present invention. 1 ... Heat storage device, 2 ... Heat storage tank, 3 ... Heat storage electric heater, 4 ... Temperature detector, 5 ... Heat storage mixture, 6 ... Heat storage material, 7 ... Heat medium, 8 ... Electricity Type steam boiler, 9 ... Electric heater for boiler, 10 ... Water level detector, 11 ... Heater control steam pressure detector, 12 ... Peak load detector, 13
...... Heat exchange pipe, 14 …… Boiler water supply line, 15 …… Water supply control valve device, 16 …… Boiler water supply, 17 …… Pipe line, 18 …… Water pump, 19 …… Water tank, 20 …… Control Board.

Front page continuation (72) Inventor Masaru Otsu 1-41-1 Tosabori, Nishi-ku, Osaka City, Osaka Prefecture Kansai Electric Power Co., Inc. (72) Inventor Susumu Yoshida 1-1-4 Tosabori, Nishi-ku, Osaka City, Osaka Kansai Electric Power Co. In the company

Claims (3)

[Scope of utility model registration request] 1. An electric steam boiler (8) comprising an electric heater (9) for a boiler and a peak load detecting device (12) for detecting a peak load; and an electric heater (3) for heat storage, and
A heat storage device (1) which stores therein a heat storage mixture (5) composed of a heat storage material (6) and a heat medium (7); A heat exchange pipe (13) connected in parallel to the boiler water supply pipe line (14) of the steam boiler (8); the operation is controlled by the peak load detection device (12), and the boiler water supply (16) during peak load Regenerative electric boiler comprising a water supply control valve device (15) for supplying water to the electric steam boiler (8) through the heat exchange pipe (13). 2. A heat storage type electric boiler according to claim 1, wherein the heat storage material (6) is pellets of surface crosslinked high density polyethylene and the heat medium (7) is ethylene glycol or heat transfer oil. 3. The heat storage type electric boiler according to claim 1, wherein the heat storage material (6) is crushed stone and the heat medium (7) is heat carrier oil.