JP4328307B2 - Method for preventing metal vapor deposition in regenerative alternating combustion furnace - Google Patents

Description

  The present invention relates to a method for preventing metal vapor deposition in a regenerative alternating combustion furnace that prevents metal sublimated by heat treatment in the furnace body from being deposited on a heat accumulator and being clogged.

  A conventional heat storage type alternating combustion furnace (see Patent Document 1) is shown in FIG. A pair of burners 1a and 1b are each provided with a heat storage chamber 3 containing a heat storage body 2, and an air supply blower 4 and an exhaust blower 5 are connected to both burners 1a and 1b via a four-way valve B. 1b is alternately burned, while the combustion of one burner 1a is performed, exhaust gas (high-temperature furnace air) in the furnace body 6 is exhausted through the other burner 1b, and exhaust heat is recovered in the heat storage chamber 3, and this exhaust gas is recovered. The combustion air is preheated when the burner 1b is burned next by heat. FIG. 3B shows the structure of the heat storage chamber 3. As the heat storage body 2, ceramic small balls or a honeycomb structure is usually used.

In this heat storage type alternating combustion furnace, for example, when forging an alloy containing molybdenum, molybdenum in the alloy is oxidized to molybdenum trioxide (MoO ₃ ), which is sublimated and mixed in the exhaust gas to store heat. When passing through the inside of the chamber 3, there is a problem that vapor deposition occurs in the low temperature portion of the heat storage body 2 and clogging occurs, and the heat storage chamber 3 is blocked. When the high-temperature furnace air in the furnace body 6 is exhausted, both the burners 1a and 1b and the air supply blower 4 are stopped, the furnace door 61 is opened halfway, the switching operation of the four-way valve B and the operation of the exhaust blower 5 are performed. The high-temperature furnace air in the main body 6 is alternately distributed and passed through the two heat storage chambers 3, and the high-temperature furnace air is passed through the heat storage chambers 3 of the burners 1 a and 1 b to resublimate the deposited material of the heat storage body 2. It was.

However, in this conventional heat storage type alternating combustion furnace, when the high temperature furnace air in the furnace body 6 is exhausted as described above, the high temperature furnace air is passed through the four-way valve B to the heat storage chamber 3 of both burners 1a and 1b. Since one side is allowed to pass and it takes time to complete exhaust of the high-temperature furnace air in the entire furnace body 6, the heat storage chamber 3 is maintained at a high temperature during this time, and the heat storage body of the heat storage chamber 3 As a result, the durability of the support 31 that supports 2 decreases. For this reason, what has completed the process which exhausts the high temperature furnace air in the furnace main body 6 through the thermal storage chamber 3 in a short time was desired.
Japanese Patent Laid-Open No. 09-210346

  The present invention has been made in view of the above points, and an object of the present invention is to provide a regenerative alternating combustion furnace in which the process of exhausting high-temperature furnace air in the furnace body through the heat storage chamber is completed in a short time. The object is to provide a method for preventing metal deposition.

  In order to solve the above-mentioned problem, in the invention according to claim 1, the pair of burners 1a and 1b are each provided with the heat storage chamber 3 having the heat storage body 2, and the air supply blower 4 is connected to the heat storage chambers of both burners 1a and 1b. 3 is connected via an air supply pipe 41 having an air supply on / off valve 42, and the exhaust blower 5 is connected to the heat storage chambers 3 of both burners 1 a and 1 b with an exhaust on / off valve 52. 51, and switching between opening and closing of the air supply on-off valve 42 and the exhaust on-off valve 52 is performed in the heat storage chamber 3 of the other burner 1b (or 1a) during combustion of one burner 1a (or 1b). In a regenerative alternating combustion furnace in which exhaust heat is recovered, after the combustion operation is stopped, the burners 1a and 1b and the air supply blower 4 are stopped, the air supply on-off valve 42 is closed and the furnace door 61 is opened halfway. Exhaust valve 52 is opened and exhausted By operating the lower 5 and exhausting the high-temperature furnace air in the furnace body 6 through the heat storage chambers 3 of both burners 1a and 1b at the same time, the temperature of the heat storage body 2 is raised to a temperature higher than the sublimation temperature of the deposited material. It is characterized by this.

  With this configuration, when exhausting the high-temperature furnace air in the furnace body 6 after stopping the combustion operation, the high-temperature furnace air in the furnace body 6 is passed through the heat storage chamber 3 of the burners 1a and 1b. Can be exhausted through both the heat storage chambers 3 at the same time, exhaust processing of the high-temperature furnace air in the furnace body 6 can be completed in a short time, and the support 31 that supports the heat storage body 2. The deterioration of durability can be suppressed.

  Further, in the invention according to claim 2, in claim 1, at least the temperature of the heat storage body 2 is vapor-deposited for the time for passing the high-temperature furnace air in the furnace body 6 into the heat storage chamber 3 of the burners 1 a and 1 b. It is characterized in that the time until the temperature rises above the sublimation temperature of the object is set.

  By adopting such a configuration, the temperature of the heat accumulator 2 is raised to the sublimation temperature of the deposited material or more simply by adjusting the length of time for exhausting the high-temperature furnace air in the furnace body 6 after the combustion operation is stopped. Can do.

  The invention according to claim 3 is the intake on-off valve for taking in outside air between the heat storage chamber 3 of the supply pipe 41 and the supply on-off valve 42 in claim 1 or 2. The intake branch pipe 7 provided with 71 is provided, and the high temperature furnace air in the furnace body 6 is exhausted through the heat storage chambers 3 of both burners 1a and 1b so that the exhaust temperature is about 300 ° C. The on-off valve 71 is adjusted.

  By setting it as such a structure, the exhaust blower 5 can be prevented from burning.

  In the present invention, after the combustion operation is stopped, the high-temperature furnace air in the furnace body can be exhausted through both the heat storage chambers at the same time, and the process of exhausting the high-temperature furnace air in the furnace body is completed in a short time. Thus, it is possible to suppress a decrease in durability of the support body that supports the heat storage body of the heat storage chamber.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows an embodiment of a regenerative alternating combustion furnace of the present invention. Each of the burners 1a and 1b is integrally provided with a heat storage chamber 3 that houses the heat storage body 2. The heat storage chamber 3 is formed inside the heat storage chamber outer shell 30 as shown in FIG. 2, and a reticulated support 31 is disposed in the heat storage chamber 3 and ceramic small spheres (for example, a diameter of 10) are provided on the support 31. The heat storage body 2 consisting of ˜20 mm) is placed and accommodated. Burners 1a and 1b (or a vent to the burner) are connected to the upper side of the portion of the heat storage chamber 3 containing the heat storage body 2, and below the portion of the heat storage chamber 3 containing the heat storage body 2 An air supply pipe 41 from the air supply blower 4 and an exhaust pipe 51 to the exhaust blower 5 are connected to each other. The air supply pipe 41 and the exhaust pipe 51 are formed as separate pipes for each of the heat storage chambers 3 of both burners 1a and 1b, and each of the air supply pipe 41 and the exhaust pipe 51 is supplied with air. The on-off valve 42 and the exhaust on-off valve 52 are provided in the middle. An intake branch pipe 7 having an intake opening / closing valve 71 for intake of outside air is provided between the heat storage chamber 3 of the supply pipe 41 and the supply opening / closing valve 42. Further, a fuel supply pipe 8 having a fuel supply opening / closing valve 81 is connected to the burners 1a and 1b. In this regenerative alternating combustion furnace, electromagnetic valves are used as the on-off valves 42, 52, 71, 81, and the electromagnetic valves, the air supply blower 4, and the exhaust blower 5 are controlled by a control unit (not shown). It is like that. In the figure, 6 indicates a furnace body, and 61 indicates a furnace door.

  The combustion operation of the regenerative alternating combustion furnace is such that the high-temperature furnace air that is the exhaust gas in the furnace body 6 is exhausted from the other burner 1b (or 1a) during the combustion of one burner 1a (or 1b). 4 and the exhaust blower 5 are operated and stopped, and the open / close valve 42 for supply and the open / close valve 52 for exhaust are switched to perform alternating combustion. At this time, the heat storage in the heat storage chamber 2 is performed by the heat of the high-temperature furnace air. The combustion air is preheated through the body 3. Further, at this time, the temperature of the high-temperature furnace air in the furnace body 6 reaches about 1200 ° C. or more, and the cycle of the alternating combustion is, for example, about several tens of seconds to several minutes. The heat recovery efficiency is set to be optimum.

  By the way, during the combustion operation, the burners 1a and 1b are alternately burned in the above alternating combustion cycle. During this combustion operation, the temperature of the lower end D (see FIG. 2) of the heat accumulator 2 is the sublimation temperature of the deposited material. It will never rise. That is, when the burner 1a (or 1b) is burning during the combustion operation, air is supplied from the supply air blower 4 to the heat storage chamber 3 of the burner 1a (or 1b), and the air is as shown in FIG. As shown, it flows from the lower side of the heat storage chamber 3 to the upper side through the heat storage body 2 and is heated by the heat storage body 2 when passing through the heat storage body 2, resulting in a high temperature from the upper end to the burner 1 a (or 1 b). At this time, the lower end D of the heat storage body 2 is exposed to low temperature air and becomes the lowest temperature. Further, when exhausting from the burner 1a (or 1b), the high-temperature furnace air flows from the upper side of the heat storage chamber 3 to the lower side through the heat storage body 2, and gives heat to the heat storage body 2 when passing through the heat storage body 2. At this time, the lower end D of the heat storage body 2 is exposed to the high-temperature furnace air having a temperature lower than that of the upper heat storage body 2, so that the temperature becomes the lowest. For this reason, the temperature of the lower end part D of the thermal storage body 2 does not rise higher than the sublimation temperature of the deposited material during the combustion operation.

  Therefore, when the high-temperature furnace air in the furnace body 6 is exhausted after the combustion operation is stopped, the high-temperature furnace air in the furnace body 6 is passed through the heat storage chamber 3 and the temperature of the lower end D of the heat storage body 2 is set to the sublimation temperature of the deposited material. The deposition is re-sublimed by raising the temperature. The time during which the high-temperature furnace air in the furnace body 6 is passed through the heat storage chamber 3 is long enough for the temperature of the heat storage body 2 to rise above the sublimation temperature of the deposited material.

  More specifically, for example, when batch-type heat treatment is performed in the furnace body 6, the operation of the furnace is normally stopped once a day. After the combustion operation is stopped, the burners 1a and 1b and the air supply blower 4 are first stopped, the furnace door 61 is opened halfway, and exhaust is performed until the temperature in the furnace body 6 is sufficiently lowered by the exhaust blower 5. At this time, both the exhaust on / off valves 52 are opened and the exhaust blower 5 is operated so that the high-temperature furnace air in the furnace body 6 is simultaneously passed through the heat storage chambers 3 of both the burners 1a and 1b, so that the heat storage body 2 is deposited. Raise above the sublimation temperature. At this time, the open / close valve 71 for intake is opened, the low temperature outside air is sucked into the heat storage chamber 3 through the intake branch pipe 7, and the high-temperature furnace air exhausted from the heat storage chamber 3 through the exhaust pipe 51. The temperature is adjusted to about 300 ° C. or lower. This prevents the exhaust blower 5 having a heat resistant temperature of about 300 ° C. from being burned out.

  The reason why the furnace door 61 is in the half-open state is to prevent outside air from being sucked through the stopped supply air blower 4 and cooling the lower end D of the heat storage chamber 3, and thus the furnace door. 61 should not be opened too much so that the exhaust temperature does not drop below the sublimation temperature until all of the deposit is vaporized.

  With this configuration, when exhausting the high-temperature furnace air in the furnace body 6 after stopping the combustion operation, the high-temperature furnace air in the furnace body 6 is passed through the heat storage chamber 3 of the burners 1a and 1b. Can be exhausted through both the heat storage chambers 3 at the same time, and the process of exhausting the high-temperature furnace air in the furnace body 6 and resublimating the deposited material deposited on the heat storage body 2 is completed in a short time. Therefore, it is possible to suppress a decrease in the durability of the support 31 that supports the heat storage body 2. For example, the support 31 that has been replaced once a year may be replaced with a longer span.

1 is a system diagram of a regenerative alternating combustion furnace according to an embodiment of the present invention. It is sectional drawing which showed the structure of the thermal storage chamber same as the above. (A) is a systematic diagram of a regenerative alternating combustion furnace showing an embodiment of the prior art, and (b) is a main part systematic diagram showing the structure of a heat storage chamber.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a Burner 1b Burner 2 Heat storage body 3 Heat storage chamber 30 Heat storage chamber outer shell 31 Support body 32 Vent 4 Air supply blower 41 Air supply pipe 42 Air supply on / off valve 5 Exhaust blower 51 Exhaust pipe 52 Exhaust on / off valve 6 Furnace door 7 Intake branch pipe 71 Intake on-off valve 8 Fuel supply piping 81 Fuel supply on-off valve

Claims (3)

  A pair of burners are provided with heat storage chambers each storing a heat storage body, and the air supply blower is connected to the heat storage chambers of both burners via the air supply pipes each provided with an air supply on / off valve, and the exhaust blower is connected to both the burners. The heat storage chamber of the other burner is connected to the heat storage chamber of the other burner by switching the opening and closing of the air supply on-off valve and the exhaust on-off valve. In a regenerative alternating combustion furnace that collects exhaust heat at the end of the combustion operation, after the combustion operation is stopped, the burner and the air supply blower are stopped, the air supply on / off valve is closed, the furnace door is opened halfway, and both exhaust on / off valves are installed. Opening and operating the exhaust blower to exhaust the high-temperature furnace air in the furnace body through the heat storage chambers of both burners at the same time, thereby raising the temperature of the heat storage body above the sublimation temperature of the deposit. Metal deposition in regenerative alternating combustion furnace Stop method.   2. The time for passing the high-temperature furnace air in the furnace body through the heat storage chamber of the burner is set so as to be at least the time until the temperature of the heat storage body rises above the sublimation temperature of the deposited material. The method for preventing metal vapor deposition in the regenerative alternating combustion furnace described. An intake branch pipe having an intake on / off valve for intake of outside air is provided between the heat storage chamber of the supply air piping and the supply on / off valve, and the high-temperature furnace air in the furnace body is transferred to the heat storage chamber of both burners. The method for preventing metal vapor deposition in a regenerative alternating combustion furnace according to claim 1 or 2, wherein the intake on-off valve is opened and closed so that the exhaust temperature when exhausting through the exhaust gas is about 300 ° C.

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