JPH07198102A - Steam generating device - Google Patents

Abstract

PURPOSE:To suppress the deposition of can stone on a heating surface, etc., from generating, and prevent a heater wire from breaking due to the sticking of can stone, or prevent the heat efficiency from reducing by a method wherein a heat conductive element is extended in a small sized heating tank to increase the heat conductive area, and the temperature of a heat conductive surface is kept low. CONSTITUTION:A heat conductive element is provided in a heating tank 1 by extending the heat conductive element 23 on a heating tank heat conductive part 4. When a power source is input, a heater 2 heats, and the heat is transmitted at the heating surface of the heating tank 1, and the temperature of water ascends. The water in the heating tank 1 of which the temperature ascends goes up by air bubbles which are generated by boiling, and is fed to a gas-liquid separator 10. In the gas-liquid separator 10, the deposition speed of can stone to the heating surface exponentially increases accompanying with the ascent of the water temperature at the heating surface, and from a viewpoint of can stone deposition control, the temperature of the heating surface needs to be suppressed as low as possible. However, since the heating surface is increased by providing the heat conductive element 23 by extending it on the heat tank heat conductive part 4, a heat conductive density can be drastically suppressed compared with a conventional method, even with the same outer shape dimensions. By this method, the deposition of can stone components can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small steam generator for use in an air conditioner, a humidifier, a home air conditioner, a constant temperature and constant humidity chamber, and in particular, a water containing a scale component such as calcium or magnesium. The present invention relates to a steam generator that is safe to use and safe to use, and that suppresses adhesion of scales to the heating surface.

[0002]

2. Description of the Related Art Steam generators are widely used for indoor humidification during the dry season of winter. Conventionally, there is a heating type steam generator as this kind of steam generator. In a conventional heating type steam generator, a sheath heater is placed in a heating tank, or a heater is provided at the bottom or side of the heating tank to heat water in the heating tank to generate steam. In this device, when water in the heating tank is heated to boil to generate steam, scales are deposited on the heating surface, the amount of deposition increases with the boiling time, and water further evaporates, causing the scale concentration of scale in the heating tank. However, there was a problem that the amount of scale deposits increased more drastically with increasing. In order to reduce the waiting time from the start of heating to the generation of steam, some of them heat the tank by reducing the amount of water in the heating tank, but it is not possible to heat this small amount of water in a small space. Although it is preferable in shortening the waiting time, since the scale component dissolved in water is concentrated at a high speed in this narrow space, the scale component is further precipitated at a high speed on the heating surface, This caused problems such as damage to the heater and reduction in thermal efficiency.

[0003]

A problem to be solved by the present invention is that a large amount of scale is deposited on a heated surface when steam is generated by heating. Especially,
When the heating tank is made small, scales are markedly attached. The present invention is small in size and suppresses the deposition of scales on the heating surface, and prevents problems such as damage to the heater wire due to scale deposits and a reduction in thermal efficiency.

[0004]

The present invention has been achieved as a result of extensive studies on the conditions for depositing scale components on the heating surface and the conditions for water evaporation. The precipitation rate of scale components is proportional to the cube of the concentration rate of scale components, and increases exponentially with temperature. According to the present invention, a heat transfer body is extended in a small heating tank to increase a heat transfer area and suppress a heat transfer surface temperature to a low level, thereby suppressing the amount of scale adhered to the heating surface.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 (a) is a vertical cross-sectional view of an example including a water supply / drainage type cartridge tank according to an embodiment of the present invention. Reference numeral 1 is a heating tank, 2 is a heater, and a heat insulating material 3 is provided around the heating tank 1 in order to prevent burns and heat dissipation. 10 is a gas-liquid separator,
Reference numeral 11 denotes a filler, which is made of glass wool, resin fiber, or the like, and serves as a filter for silencing blowout noise, promoting gas-liquid separation, and preventing small water droplets from jumping out. Reference numeral 24 is a cartridge tank, 25 is a cartridge tank water tap, and 26 is a water receiving tank which constitutes a water supply device. The cartridge tank water tap has a structure in which part of it extends into the cartridge tank and water does not run out. FIG. 1B shows a heating tank 1.
In the A-A sectional view of 23, a heat transfer member 23 is provided in the heating tank so as to extend to the heating tank heat transfer section 4. FIG. 2A shows a conventional embodiment directly connected to the water supply. 5 is a water level adjusting tank, 6 is an overflow, and 7 is a water tap, which constitutes a water supply device. 10 is a gas-liquid separator, and 11 is a filler. Reference numeral 14 is a drain port provided in the return water channel. FIG. 2 (b) shows A of the heating tank 1.
FIG.

Next, the operation will be described. When the power is turned on, the heater 2 generates heat, heat is transferred to the water on the heating surface of the heating tank 1, and the temperature of the water rises. The water in the heating tank 1 whose temperature has risen seven times rises due to the bubbles generated by boiling and is sent to the gas-liquid separator 10. The fluid boundary film on the heating surface is shaken by the rising bubbles and the film thickness becomes thin. The water that has entered the gas-liquid separator 10 slowly drops while wetting the surface of the filling material 11, drops into the return water channel pipe 15 and enters the heating tank again. A part of the dissolved components concentrated by evaporation flows back and diffuses in the water supply path from the cartridge tank to the heating tank and enters the cartridge tank. This concentrated water is discarded when the cartridge tank water tap 25 is removed during water supply. Since the deposition rate of scales on the heating surface increases exponentially as the water temperature of the heating surface increases, it is necessary to keep the heating surface temperature as low as possible from the viewpoint of controlling the precipitation of scales. Since the heat transfer body 23 is provided so as to extend to the heat transfer section 4 to increase the heating surface, the heat transfer density can be remarkably reduced as compared with the conventional example even with the same outer dimensions. As a result, precipitation of scale components can be suppressed.

FIG. 4 is a diagram showing the relationship between the heat transfer density and the amount of scale deposit taken under one condition. The horizontal axis is the heat transfer density and the vertical axis is the scale deposit thickness extrapolated to a boiling time of 3000H. is there. Figure 3
1 is a comparison test result of the example of FIG. 1B of the present application and the conventional example (cartridge tank water supply / drainage type) in which the heat transfer body is not provided. The test conditions are: heating tank inner diameter 26 mm, heater wire 40H, 250 W, raw water calcium hardness 110 m
g / l, water supply / drainage ratio 7 In the figure, a is the thickness of scale deposit in the heating tank of the embodiment of the present invention. B in the figure is the scale thickness of the scale of the conventional example. In this example, the scale deposit amount is about 1/5 of the conventional example. Scales initially deposit in areas with high heat transfer density. As the precipitation progresses, the heat conduction deteriorates and the places with high heat transfer density become lower and the averaging progresses. There are variations in precipitation even in areas where the flow of hot water is good and bad. The calculated average heat transfer density in the entire heat transfer area is 6.8 w / cm ^{2 of the} conventional example and 3.0 w / cm ² or less of the example of the present invention. Since the downward heat transfer area is increasing and averaging, it is expected that the difference will further increase in the future as the boiling time elapses, as shown in FIG. (See FIG. 4, a is 0.3 w / cm ² 0.3 mm /
It is expected to approach 3000H. In the example of the present application, the temperature in the vicinity of the heater wire was about 135 ° C. and remained almost unchanged after 3000 H was used.

Although the cartridge tank is used for water supply / drainage here, it may be of a direct water supply type, and the heat transfer body may be a spiral shape, a square shape, or a double pipe so that the heat transfer density can be lowered. If it is good. Further, although the heat source of the heater has been described as electric, other heat sources such as combustion heat and high temperature refrigerant from the compressor may be used.

[0009]

As described above, according to the present invention, the heating tank can be made small and have a low heat transfer density. As a result, even if steam containing scale component is used to generate steam, the heating surface is not heated. It is possible to provide a small-sized steam generator that has less scale deposits, can be used for a long time without maintenance, and has a short steam generation response time.

[Brief description of drawings]

FIG. 1 (a) is a vertical cross-sectional explanatory view of an embodiment of the present invention including a water supply / drainage type cartridge tank. Part (b) is a sectional view of the heating tank taken along line AA.

FIG. 2A is a vertical cross-sectional explanatory view of a conventional example. Part (b) is a sectional view of the heating tank taken along line AA.

FIG. 3 is a diagram showing a comparison test result of an example of the present invention and a conventional example.

FIG. 4 is a diagram showing a relationship between heat transfer density and scale deposit amount under one condition.

[Explanation of symbols]

1 heating tank 2 heater 3
Heat insulating material 4 Heating tank heat transfer part 5 Water level adjusting tank 6
Overflow 7 Water tap 10 Gas-liquid separator 11
Filler 14 Drainage port 15 Return channel 23
Heat transfer body 24 Cartridge tank 25 Cartridge tank water tap 26 Water receiving tank

Claims (1)

[Claims] 1. A steam generator comprising a heating tank and a water supply device, wherein the heating tank is a, and a heat transfer member is attached in contact with a heat transfer section for water of the heating tank.
Alternatively, a steam generator having a structure in which a heating tank and a heat transfer body extending from the heating tank heat transfer section into the heating tank are integrally formed.