JPH0559426A - Method and apparatus for humidifying atmospheric gas in heat treatment furnace - Google Patents

Abstract

PURPOSE:To prevent a metal used to the position vaporizing moisture from the heat deformation and the development of crack. CONSTITUTION:This apparatus is constituted of a water tank 1 for weighing and feeding out liquid-phase water, a metering pump 2, a flow meter 3 linked with the pump, a spray nozzle 7 for atomizing the water as mist state, a vaporizing pot 8 for directly connecting to the nozzle and immediately vaporizing by heating the mist with a heating device 13, a humidified gas supplying piping 14 for supplying into a heat treatment furnace 17 by mixing the gasified steam with carrier gas and an injecting header 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for humidifying atmospheric gas used in a heat treatment furnace for steel or the like.

[0002]

2. Description of the Related Art In a heat treatment furnace for a certain type of steel sheet, for example, an electromagnetic steel sheet, in order to remove carbon in the steel material to obtain a desired quality, the atmospheric gas of the heat treatment furnace contains water vapor and its humidity, Alternatively, the temperature at which water vapor in the atmospheric gas starts to condense, that is, the dew point is managed.

In this method, the reaction of H ₂ O + C → H ₂ + CO is carried out between the water vapor in the atmospheric gas and the carbon in the steel material to decarburize. Therefore, in order to perform dew point control accurately, it is important to accurately control the amount of water contained. There is also a method of directly blowing steam into the atmospheric gas as water, but as is generally known, it is very difficult to accurately measure a small amount of water vapor, and the pressure, temperature, amount of steam, etc. of the steam can be accurately measured. Since it cannot be measured and grasped, it is not often used. Generally, the amount of water in the liquid phase is accurately measured, and this is sent into the atmospheric gas in the furnace to be vaporized.

In this method, however, the total amount of water input to the furnace can be accurately grasped, but since the water is vaporized in the furnace, the composition and concentration of the gas in the furnace cannot be avoided. There is. Therefore, it has been proposed that the water that has been measured and cut out is not directly put into the furnace, but that the water is preheated outside the furnace to be vaporized and then mixed with the atmospheric gas. As one example thereof, FIG. 2 shows the configuration of a humidifying / supplying device for atmospheric gas disclosed in Japanese Patent Laid-Open No. 1-263216.

In this figure, 21 is a supply pipe for liquid water for steam, and 22 is a supply pipe for dry atmosphere gas. 3
1, 32 are flow control valves for water and dry atmosphere gas, 33, 34
Are respective flow meters. 51 is a first heating device for heating liquid water, 52 is a second heating device for heating atmospheric gas,
Reference numeral 53 is a third heating device for heating the humidified atmospheric gas in which the steam generated by the first heating device and the high dew point dry atmospheric gas heated by the second heating device are mixed.

Reference numerals 61, 62, and 63 are thermometers for steam, dry atmosphere gas, and humid atmosphere gas, 64 is a pressure gauge for dry atmosphere gas, and 17 is a heat treatment furnace for supplying the humid atmosphere gas. When the amount of humidified atmospheric gas and the dew point required in the heat treatment furnace 17 are determined, the required amount of water and dry atmospheric gas to be supplied to 21, 22 are determined, and the liquid phase water is passed through the flow control valve and the flow meter. In the first heating device, the steam passing through the outlet is heated by the heating control device 41 so as to become superheated steam having a saturated steam temperature or higher corresponding to the pressure of the dry atmosphere gas.

On the other hand, the dry atmosphere gas is heated in the second heating device by the heating control device 42 so as to have a dew point temperature or higher due to the temperature and flow rate at the outlet thereof.
Further, the humidified atmosphere gas obtained by mixing the superheated steam and the dry atmosphere gas is heated and kept at a temperature higher than the dew point temperature in the third heating device and supplied to the heat treatment furnace 17.

According to this method, the amount of water is accurately measured as water in the liquid phase, and it is heated to the dew point temperature or higher before being supplied to the furnace and uniformly mixed with the atmospheric gas. Although there is no vaporization of water and non-uniformity of the composition and concentration of the gas in the furnace does not occur, there is a facility problem that three heating devices and their control devices are required. On the other hand, FIG. 3 shows an evaporation pot system proposed by Japanese Utility Model Laid-Open No. 2-53959, in which the water tank 1 is connected to the pump 2, the flow meter 3, the flow rate controller 4, and the flow rate control valve 5. After that, the necessary amount of water is measured and cut out, and is sent by a water pipe 7 into an evaporation pot 8 embedded in an outer wall portion 18 of the heat treatment furnace and dropped from a water pipe tip 10.

The evaporating pot 8 is surrounded by a partition plate around the lower side so that water can be stored in the inner space, but the upper side facing the inside of the furnace is open so that the water in the inside can be removed by the heat inside the furnace. The vaporized vapor is supplied into the furnace through the opening 8a. In addition, instead of this evaporation pot, a water pipe is extended into the furnace so that it is completely vaporized as an S-shaped flexible pipe until it reaches the opening at the tip, or the flexible pipe is heated outside the furnace by a heating device. A method is also used in which the gas is completely vaporized and fed into the furnace.

[0010]

By the way, the evaporation pot system or the flexible tube system is simpler as a facility than the heating and mixing system of FIG. 2, but in any case, it is exposed to high heat. While there is an exposed metal part, water droplets drop at the bottom of the evaporation pot or at a specific position of the flexible pipe, large thermal stress is generated locally and the evaporation pot and flexible pipe are deformed. As a result, the crack is generated as a result of being further specified and the deformation is promoted, and if there is a heating device in the vicinity, the crack may be deformed. Due to these deformations, it was extremely difficult to replace the evaporation pot and the flexible pipe.

An object of the present invention is to solve the above problems and to realize humidification of atmospheric gas in a heat treatment furnace with a simple facility without causing deformation or the like.

[0012]

A method for humidifying an atmosphere gas in a heat treatment furnace according to the present invention is to measure water in a liquid phase, supply the water to atomizing means, atomize it, and immediately heat it to vaporize it. It is characterized in that the vaporized vapor is mixed with a carrier gas and then supplied to a heat treatment furnace. Further, the atmosphere gas humidifier of the heat treatment furnace of the present invention is a water supply means for measuring and sending out liquid phase water, an atomizing means for atomizing the supplied water into a mist, and heating this mist. It is composed of vaporizing means for vaporizing, and humidified gas supplying means for mixing vaporized vapor with a carrier gas and supplying the mixture into the furnace.

[0013]

[Operation] According to the present invention, since the water content in the liquid phase is measured, the water content can be accurately controlled, and once atomized by the spray nozzle, it is immediately heated and vaporized.
Evaporation is performed uniformly from the entire heating surface of the evaporation pot or the flexible tube, which is the vaporizing means, and the heat load is averaged, so that deformation and cracking are small.

[0014]

FIG. 1 shows the configuration of one embodiment of the present invention. The water in the water tank 1 feeds back the indicated value of the flow meter 3, and a predetermined amount is supplied by the metering pump 2 to the spray nozzle 9 through the water pipe 7.
Is supplied to. Reference numeral 6 is a check valve for preventing water from flowing backward when the pump is stopped. On the other hand, as the spray gas, the same gas as the furnace atmosphere gas or a constituent gas of the furnace atmosphere gas that does not interfere with mixing (for example, when the atmosphere gas is H ₂ + N ₂ is used as the spray gas N ₂ ). The same check valve 11
And is supplied to the spray nozzle 9 through the spray gas pipe 12.

The spray nozzle 9 is directly attached to the inner surface of the evaporation pot 8, and the water is sprayed on the spray nozzle 9.
Is atomized into a fine mist and is ejected into the evaporation pot 8 and immediately heated by a heating device 13 surrounding the evaporation pot 8 to be vaporized. Recently, particle size 70μ at a gas pressure of 1 to ⁴ kg / cm ^2.
Nozzles with atomization performance of m or less are also commercially available, so mist of 100 μm or less can be easily realized.

The spraying gas supplied to the spray nozzle 9 becomes a carrier gas as it is, is mixed with the steam generated in the evaporation pot 8 and becomes a humidifying gas, and becomes a humidifying gas supply pipe 14, and further, a super heater 15 makes a temperature inside the furnace. And is supplied from the blowout header 16 into the heat treatment furnace 17. As the water supply means, the combination of the metering pump 2 and the flow meter 3 shown in this embodiment is excellent in control accuracy, but an ordinary pump is used instead of the metering pump 2, and as shown in the example of FIG. 3 above. A flow rate adjusting valve or controller may be combined with.

When the spray nozzle 9 is a pressure spraying system which sprays by the pressure of water without using the spraying gas as the atomizing means, the spraying gas pipe 12 becomes unnecessary, and the carrier gas is evaporated into an evaporation pot if necessary. All you have to do is send it to. Since the heat load of the evaporation pot 8 also changes when the amount of supplied water changes due to a change in the dew point of the atmosphere in the furnace, it is desirable to appropriately adjust the supply amount of the spray gas according to the change in the amount of water.

Further, in this embodiment, the evaporation pot 8 is installed outside the furnace as a vaporizing means and heated by the heating device 13, and further heated by the super heater 15 to the temperature inside the furnace to influence the furnace temperature and the plate temperature. However, the super heater 15 may be omitted depending on temperature conditions. A flexible tube may be used instead of the evaporation pot. Further, when the water injection amount is small and there is no concern about the influence on the furnace temperature and the plate temperature, the evaporation pot 8 is embedded in the outer wall portion as shown in FIG. The humidified gas may be directly supplied into the furnace through the opening to the inside. In this case, it is not necessary to supply the carrier gas from outside the system, and the atmospheric gas that enters from the opening of the evaporation pot 8 into the furnace becomes the carrier gas as it is.

[0019]

As described above, according to the present invention, it is possible to prevent water droplets from directly dropping on the metal part of the evaporation pot or the flexible tube in a high temperature state, so that thermal deformation and crack generation of these vaporization means are prevented, and the operation of the heat treatment furnace is prevented. Trouble was reduced and production efficiency was improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the configuration of an embodiment of an atmospheric gas humidifying device of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of an atmospheric gas humidifier according to a conventional technique.

FIG. 3 is an explanatory diagram showing a configuration of an atmospheric gas humidifier according to another conventional technique.

[Explanation of symbols]

 1 water tank 2 pump 3 flow meter 7 water pipe 8 evaporation pot 9 spray nozzle 13 heating device 17 heat treatment furnace

Claims (2)

[Claims] 1. A liquid phase water is measured and supplied to an atomizing means, atomized and then immediately heated to be vaporized, and the vaporized vapor is mixed with a carrier gas and then supplied to a heat treatment furnace. A method for humidifying an atmosphere gas in a heat treatment furnace, comprising: 2. Water supply means for measuring and sending out liquid phase water, and atomization means for atomizing the supplied water in a mist form,
An atmosphere gas humidifying device for a heat treatment furnace, which comprises a vaporizing means for heating and vaporizing the mist and a humidifying gas supplying means for mixing the vaporized vapor with a carrier gas and supplying the mixed gas into the furnace.