JPH0886510A - Atmospheric pressure type hot-water boiler haing corrosion preventive structure - Google Patents

Abstract

PURPOSE: To intercept contact between retaining water in a boiler main body and atmosphere to eliminate the melting of corrosive gas, such as oxygen, carbon dioxide and the like, in atmosphere and prevent the corrosion of the boiler main body by the corrosive gas, in an atmospheric pressure type hot-water boiler. CONSTITUTION: In an atmospheric pressure type hot-water boiler, consisting of a boiler main body 10, a combustion chamber 14 for generating combustion gas heating retaining water 12 stored in the boiler main body 10, and an expansion absorbing tank 16, provided continuously to the upper part of the boiler main body 10 and communicated with atmosphere, the boiler is operated at an atmospheric pressure by controlling the level of retaining water 12 in the boiler main body 10 at a height within a given range in the expansion absorbing tank 16 while the surface of the retaining water 12 in the boiler main body 10 is covered by a soft membrane member 30 so as to be air-tight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an atmospheric pressure hot water boiler having a corrosion prevention structure and having high corrosion resistance.

[0002]

2. Description of the Related Art A conventional atmospheric pressure hot water boiler is, as shown in FIG. 3, a boiler body 10 and a combustion chamber 14 for heating the retained water 12 stored in the boiler body 10.
It is composed of an expansion and absorption tank (expansion water tank) 16 which is connected to the upper portion of the boiler body 10 and communicates with the atmosphere. 18
Is a burner and 20 is a flue. A hot water heater is constituted by the atmospheric pressure hot water boiler and the heat exchanger 22. Reference numeral 24 is a circulation pump, and 26 is a retained water discharge valve.

Since the pressure in the boiler body 10 holding the boiler water does not exceed the atmospheric pressure, there is no pressure breakdown and the safety is high. Therefore, handling qualification is not required and it is widely used as a hot water boiler. However, in the conventional atmospheric hot water boiler, since the water surface is in contact with the atmosphere, oxygen in the atmosphere,
Corrosive gas such as carbon dioxide dissolves in the water retained in the boiler main body 10 to corrode the steel plate forming the boiler main body 10,
There was a problem that durability was lowered.

[0004]

As described above, when a corrosive gas such as dissolved oxygen is dissolved in the retained water in the boiler body, corrosion occurs in the steel plate of the boiler body. Also,
Only when dissolved salts such as chloride ions also have dissolved oxygen,
Greatly promotes corrosion of steel sheets. Thus, one of the major causes of corrosion is corrosive gas such as dissolved oxygen. In conventional atmospheric hot water boilers, the water held in the boiler body is in contact with the atmosphere, so the corrosive gas in the atmosphere is always dissolved in the water held in the boiler body from the water surface of the expansion absorption tank. However, it is a factor that continuously corrodes the steel plate of the boiler body.

As a solution to this problem, if the water surface of the expansion / absorption tank is simply covered with a steel plate or the like and cut off from the atmosphere, the retained water expands by about 3% due to a temperature rise, and this expansion causes the internal pressure to be higher than atmospheric pressure. Therefore, it will not be a highly safe atmospheric pressure hot water boiler that does not require pressure rupture and does not require handling qualifications under the application of the Ministry of Labor's "Boiler and Pressure Vessel Safety Regulations".
The present invention has been made in view of the above points, and an object thereof is to cover the water surface of an expansion / absorption tank with a film member such as heat-resistant rubber whose shape changes flexibly, and to shut off the contact between the water surface portion and the atmosphere (air seal). This keeps the internal pressure of the boiler at atmospheric pressure even if the volume expands and contracts due to the temperature change of the main body water, and prevents the corrosive gas in the atmosphere from dissolving and the water surface of the expansion absorption tank and the atmosphere. By blocking the contact (air seal),
It is to provide an atmospheric pressure hot water boiler having high corrosion resistance.

[0006]

In order to achieve the above object, an atmospheric pressure hot water boiler having a corrosion prevention structure of the present invention comprises:
It consists of a boiler body, a combustion chamber for heating the stored water stored in the boiler body, and an expansion and absorption tank that is connected to the atmosphere and is connected to the upper part of the boiler body. In an atmospheric pressure hot water boiler in which the water level of the water is controlled to a certain range of height in the expansion and absorption tank and operated at atmospheric pressure, the water surface portion of the retained water in the boiler body is hermetically sealed with a flexible membrane member. It is configured by coating.

As the flexible film member, heat resistant rubber or heat resistant plastic is used. Further, instead of the flexible membrane member, it is also possible to use liquid oil which has a smaller specific gravity than water and is immiscible (is immiscible with water). Examples of the liquid oil include low specific gravity silicone oil and paraffin.

In the above hot water boiler, it is preferable that an overflow port is provided in the expansion / absorption tank for overflowing the water retained in the boiler body in an emergency, and a water seal tube is connected to this overflow port. A seal liquid that does not dissolve corrosive gas, for example, an inert liquid such as silicone oil or a saturated aqueous solution in which sodium carbonate or the like is previously dissolved is stored in the water-sealed seal tube. In addition, the expansion and absorption tank is equipped with an overflow port for overflowing the retained water in the boiler main body in an emergency, and the gas separation plate for guiding the corrosive gas separated from the retained water in the boiler main body to the overflow inlet side is expanded and absorbed. It is preferably provided in the tank.

[0009]

The retained water (boiler water) in the boiler body is heated (for example, around 85 ° C.) by the combustion gas in the combustion chamber and introduced into the heat exchanger by the circulation pump. Here, water is heated by exchanging heat with water (for example, 5 to 40 ° C.) and taken out as warm water (for example, around 60 ° C.). Boiler water (for example, around 70 ° C.) to which heat is applied by the heat exchanger is circulated into the boiler body. The water level of the water held in the boiler body changes due to temperature changes, but even if the water level changes, the flexible membrane member always shuts off the water surface from the atmosphere. The corrosive gas does not dissolve in the holding water.

[0010]

EXAMPLES The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to the following examples, and various modifications can be made as appropriate. FIG. 1 shows an atmospheric pressure hot water boiler having a corrosion prevention structure according to an embodiment of the present invention, and FIG. 2 shows the details around the expansion absorption tank in FIG. 10 is a boiler body,
Retaining water (boiler water) is stored inside. A combustion chamber 14 is provided inside the boiler body 10 so that the retained water 12 is heated by the combustion gas. 18 is a burner.

An expansion / absorption tank 16 is provided above the boiler body 10.
Are continuously provided, and even if the volume of the retained water expands or contracts due to the temperature change of the retained water 12, the pressure inside the boiler body 10 does not change from the atmospheric pressure. Further, the water surface portion in contact with the atmosphere in the boiler body 10 or the expansion / absorption tank 16 is air-tightly covered with a film member 30 such as heat-resistant rubber or heat-resistant plastic whose shape changes flexibly to block the contact between the water surface portion and the atmosphere. By (air-sealing), corrosive gases such as oxygen and carbon dioxide in the atmosphere are prevented from dissolving in the retained water. The peripheral edge of the membrane member 30 is fixed to the expansion and absorption tank 16.

In the expansion / absorption tank 16, as shown in FIG.
An overflow port 32 is provided so that the retained water 12 in the boiler body 10 overflows in an emergency such as an abnormal increase in internal pressure of the boiler body 10. A water seal tube 36 is provided between the overflow port 32 and the overflow outlet 34 of the expansion / absorption tank 16. This water seal tube 36
Sealing liquid 3 that does not dissolve corrosive gas inside
8. For example, an inert liquid such as silicone oil or a saturated aqueous solution such as sodium carbonate is put therein so that the corrosive gas is not dissolved. In addition, the sealing liquid 38 is a gas separation plate 40, which will be described later, provided in an expansion absorption tank for generating gas generated from the retained water when the retained water initially poured is heated.
In case of emergency, it is injected after being discharged to the overflow port 32 side. Furthermore, a gas separation plate 40 is provided in the expansion absorption tank 16,
By heating the retained water, the corrosive gas separated from the retained water is guided to the overflow port 32 side. Four
2 is a seal liquid injection port, 44 is a water injection port for an initial water seal tube, 46 is a solenoid valve, 48 is a water detection electrode, 50 is a bubble, 52
Is a partition plate for guiding the corrosive gas generated by heating the retained water to the lower part of the gas separation plate 40. 1 and 2, the membrane member 30 has a shape shown by a solid line before the retained water is heated. However, when the retained water is heated, the membrane member 3 is heated.
0 changes to the shape shown by the chain double-dashed line.

Corrosive gases such as oxygen dissolved in water have a large solubility at low temperatures and a smaller solubility at higher temperatures. In an atmospheric hot water boiler, the temperature of the retained water rises during operation, the solubility of corrosive gases such as oxygen dissolved in water decreases, and the dissolved oxygen at 10 ° C in water is about 11 ppm, but the operating temperature ( Dissolved oxygen is degassed to about 2 ppm at the temperature of the stored water) 85 ° C. In the conventional atmospheric hot water boiler, the water held in the main body and the atmosphere are always in contact with each other, so that when the operation is stopped and the temperature drops, the solubility increases, and the corrosive gas dissolves in the water again. However, in the atmospheric pressure hot water boiler of the present invention, the retained water that has been initially injected is not deaerated, and then the corrosive gas does not dissolve again. 2 of the remaining dissolved oxygen
The ppm disappears after being consumed for a slight oxidation of the can body, and after that, in the atmospheric pressure hot water boiler, since the initial holding water is not replaced, it can be maintained in the state of no dissolved gas and the corrosion resistance can be significantly improved. . It should be noted that in order to deaerate the retained water of the initial water injection, deaeration may be performed only at the initial stage by using a chemical such as an oxygen absorber.

[0014]

Since the present invention is constructed as described above, it has the following effects. (1) Since the water surface of the retained water (boiler water) is airtightly covered with a membrane member whose shape changes flexibly or a non-mixable liquid oil, the contact between the retained water and the atmosphere is blocked, and It is possible to prevent the corrosive gas, such as oxygen and carbon dioxide gas, from being melted in and prevent the corrosion of the boiler body due to the corrosive gas. Of course, even if the volume expands or contracts due to the temperature change of the retained water, the pressure inside the boiler main body can always be maintained at atmospheric pressure. (2) In the conventional atmospheric hot water boiler shown in FIG. 3, natural water evaporates from the water surface of the expansion and absorption tank to reduce the amount of water retained in the boiler body, and as a result, new water in which corrosive gas is dissolved is replenished. However, in the atmospheric hot water boiler of the present invention, since spontaneous evaporation is small, a corrosive gas such as dissolved oxygen is not newly introduced.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of an atmospheric pressure hot water boiler having a corrosion prevention structure of the present invention.

FIG. 2 is a vertical cross-sectional view showing details around the expansion and absorption tank in FIG.

FIG. 3 is a vertical sectional view showing a conventional atmospheric pressure hot water boiler.

[Explanation of symbols]

 10 Boiler Main Body 12 Retained Water 14 Combustion Chamber 16 Expansion Absorption Tank 18 Burner 20 Flue 22 Heat Exchanger 24 Circulation Pump 30 Membrane Member 32 Overflow Port 36 Water Seal Seal Pipe 38 Seal Liquid 40 Gas Separation Plate

Claims (5)

[Claims] 1. A boiler main body, a combustion chamber for heating the retained water stored in the boiler main body, and an expansion absorption tank communicating with the atmosphere, which is connected to the upper portion of the boiler main body. In an atmospheric pressure hot water boiler in which the water level of the retained water in the boiler body is controlled to a certain range of height in the expansion absorption tank and operated at atmospheric pressure, the water surface portion of the retained water in the boiler body is An atmospheric pressure hot water boiler with a corrosion prevention structure characterized by being airtightly coated with a transparent film member. 2. The atmospheric pressure hot water boiler having a corrosion prevention structure according to claim 1, wherein the flexible membrane member is made of heat resistant rubber or heat resistant plastic. 3. A non-mixable liquid oil having a specific gravity smaller than that of water is used instead of the flexible membrane member.
Atmospheric pressure hot water boiler with the described corrosion prevention structure. 4. The large corrosion prevention structure according to claim 1, 2 or 3, wherein an overflow port is provided in the expansion / absorption tank for overflowing the retained water in the boiler body in an emergency, and a water seal pipe is connected to this overflow port. Barometric hot water boiler. 5. An expansion / absorption tank is provided with an overflow port for overflowing the retained water in the boiler body in an emergency, and a gas separation plate for guiding the corrosive gas separated from the retained water in the boiler body to the overflow port side. An atmospheric pressure hot water boiler having a corrosion prevention structure according to any one of claims 1 to 4, which is provided in the expansion absorption tank.