JP2002162022A - Heat treatment furnace equipped with a plurality of regenerative burners - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat treatment furnace wherein valve control of a plurality of regenerative burners can be achieved with an inexpensive simplified construction and with an improvement of reliability thereof. SOLUTION: A heat treatment furnace is provided, in which a plurality of radiant tube regenerative burners are provided, for each of which regenerative burners a pair of combustion and ventilation three-way valves 9, 10 are provided and driven by compression air, and the pair of the three-way valves 9, 10 of each of the plurality of the regenerative burners located in a predetermined combustion group are controlled with the aid of the foregoing compression air such that they are changed over in the same direction. In the furnace, common solenoid valves 22, 23, 24, and 25 are provided for controlling the compression air fed to all the three-way valves 9, 10 in the foregoing predetermined combustion group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a heat treatment furnace.
More specifically, the present invention relates to a heat treatment furnace capable of controlling valves of a plurality of regenerative burners with an inexpensive and simple configuration and improving the reliability of valve control.

[0002]

2. Description of the Related Art In a relatively high-temperature heating zone such as a continuous annealing furnace or a heat treatment furnace, a radiant tube type regenerator with a built-in heat storage type heat exchanger has recently been used as a heater for heating the furnace from the viewpoint of energy saving. Tib burners (hereinafter referred to as regenerative burners) are used. This regenerative burner is provided with a pair of burners having a heat storage body, and by burning the burners alternately, heat of exhaust gas generated by combustion of one burner is recovered by the heat storage body of the other burner.

A general radiant tube type regenerative burner includes a radiant tube, a pair of burners provided at both ends of the radiant tube, each having a heat storage body, and a pair of combustion vents respectively connected to the pair of burners. And a gas switching valve.

[0004] By switching a pair of combustion ventilation switching valve and gas switching valve at predetermined time intervals (about 20 to 30 seconds), the atmosphere and fuel gas are introduced into a burner which performs one combustion, and the other combustion burner. Exhaust and heat storage can be performed through a non-burner burner.

[0005] Usually, 150-300
Several regenerative burners are provided. In a plurality of regenerative burners, the switching valve for combustion ventilation and the gas switching valve are controlled in the same switching direction in the same group in the furnace. In addition, one group is 3 ~
It is composed of about 14 regenerative burners, and these groups usually form two or more groups to form a zone controlled at the same temperature.

[0006] Each of the combustion ventilation switching valve and the gas switching valve is driven by using compressed air for control. The supply and cutoff of the compressed air are performed using solenoid valves provided for each switching valve.

[0007]

However, in the conventional heat treatment furnace, a solenoid valve for supplying and shutting off compressed air is provided for the combustion ventilation switching valve and the gas switching valve of each regenerative burner. There is a problem that the number of solenoid valves becomes very large, and equipment costs for electric instrumentation are required.

On the other hand, a plurality of regenerative burners described in Japanese Patent Application Laid-Open No. 9-145020 reduce the required number of switching valves and the equipment cost by using a common intake and exhaust pipe and gas pipe. The responsiveness at the time of combustion switching is improved. Specifically, in this regenerative burner, as shown in FIG. 5, burners 52 at both ends of a plurality of radiant tubes 51 are connected to a common intake pipe 53, exhaust pipe 54, and gas pipe 55. . The common intake pipe 53, exhaust pipe 54 and gas pipe 55 are provided with one switching valve 56, 57 and 58, respectively.

However, the regenerative burner of FIG. 5 requires a huge space for laying a common pipe having a large diameter. Moreover, in order to prevent the influence of a crack on one radiant tube from affecting another radiant tube, it is necessary to provide an expensive shut-off valve having heat resistance in the common piping portion of the intake pipe 53 and the exhaust pipe 54. There is.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a heat treatment furnace capable of performing valve control of a plurality of regenerative burners with an inexpensive and simple structure and improving the reliability of valve control. The purpose is to provide.

[0011]

According to a first aspect of the present invention, there is provided a heat treatment furnace comprising a plurality of radiant tube type regenerative burners, each of which is driven by compressed air for each of the regenerative burners. A heat treatment furnace provided with at least one switching valve and controlling the combustion ventilation switching valves of a plurality of regenerative burners in a predetermined combustion group using the compressed air so as to have the same switching direction. And a common electromagnetic valve for controlling the compressed air sent to all the combustion ventilation switching valves in the predetermined combustion group.

Preferably, the combustion vent switching valve comprises a three-way valve.

Preferably, the combustion ventilation switching valve comprises a four-way valve.

A heat treatment furnace according to a fourth aspect of the present invention comprises:
A plurality of radiant tube type regenerative burners are provided, at least one pair of gas switching valves driven by compressed air is provided for each of the regenerative burners, and the plurality of regenerative burners in a predetermined combustion group are provided. A heat treatment furnace for controlling a gas switching valve using the compressed air so as to have the same switching direction, wherein a common heat control furnace for controlling the compressed air sent to all the gas switching valves in the predetermined combustion group is provided. Characterized in that the electromagnetic valve is provided.

A heat treatment furnace according to claim 5 of the present invention comprises:
A plurality of radiant tube type regenerative burners are provided, and for each of the regenerative burners, at least one combustion air switching valve and at least one pair of gas switching valves driven by compressed air are provided, and A heat treatment furnace for controlling the combustion ventilation switching valve and the gas switching valve of a plurality of regenerative burners in a group by using the compressed air so that the switching directions are the same as each other, wherein the predetermined A common first solenoid valve for controlling the compressed air sent to all the combustion ventilation switching valves in the combustion group is provided, and the compressed air sent to all the gas switching valves in the predetermined combustion group is compressed. It is characterized by comprising a common second solenoid valve for controlling.

Preferably, a manual valve is provided in the compressed air conduit between each of said regenerative burners and said common solenoid valve.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a heat treatment furnace having a plurality of regenerative burners will be described in more detail with reference to the drawings. FIG. 1 schematically shows a piping of a heat treatment furnace having a common solenoid valve for controlling a three-way valve and a gas switching valve, showing an embodiment of the heat treatment furnace having a plurality of regenerative burners of the present invention. FIG. 2 is a cross-sectional explanatory view of the regenerative burner of FIG. 1, FIG. 3 is a block diagram for explaining the operation of the common solenoid valve, gas switching valve, and manual valve of FIG. 1, and FIG. It is explanatory drawing which shows arrangement | positioning of the regenerative burner inside the heat processing furnace.

The heat treatment furnace shown in FIGS. 1 to 4 has a plurality of radiant tube type regenerative burners 21. As shown in FIG. 4, 84 regenerating burners 21 are provided inside the heat treatment furnace. In the regenerative burner 21, the three-way valves 9 and 10 for combustion ventilation and the gas switching valves 4 and 5 are controlled by the solenoid valves 28 to 31 described later so that the switching direction is the same for each group of six units. . Then, temperature control is performed so that each zone has the same temperature.

In the heat treatment furnace shown in FIG.
Are arranged in a matrix, and one zone includes a plurality of groups (2 to 4 groups) arranged in a column.
In the case of dividing into a side where a worker is located (work side) and a side where a machine is located (drive side) based on a small zone composed of one row of groups, there are six vehicles per group.

For example, in the example of FIG. 4, there are two types of zones in the heat treatment furnace, one zone consisting of one row group and one zone consisting of two row groups. The total number of groups is 14 groups, and both the work side and the drive side are composed of 7 groups. In order to reduce the capital investment, it is better to reduce the number of groups, but on the contrary, the failure of the solenoid valve has a greater effect on the heat treatment line.

A pull-type regenerative burner 21 shown in FIG. 2 has a U-shaped radiant tube 1 provided inside a heating furnace and a pair of burners having heat storage bodies 7 provided at both ends of the radiant tube 1. 2, 3 and gas pipe 6
Gas switching valves 4, 5 for supplying and shutting off gas from the burners 2, 3, three-way valves 9, 10 for switching the combustion ventilation connected to the pair of burners 2, 3, and three-way valve 9, respectively. , Exhaust blower 14 provided in exhaust path 13
It is composed of

The regenerative burner 21 of the pull type shown in FIG.
By making the pressure inside the radiant tube 1 negative by the exhaust blower 14, the combustion air is blown into the radiant tube 1 through the intake passages 11 of the individual three-way valves 9, 10 attached to the burners 2, 3. Can be supplied to In such a pull method, the amount of combustion gas necessary for heat-treating the material inside the heat treatment furnace is supplied to the burners 2 and 3, and the appropriate ratio of gas to air is determined according to the amount of gas supplied with combustion air. The pressure just before the exhaust blower 14 is adjusted so that

As the heat storage element 7 in FIG. 2, a small-diameter alumina ball or a ceramic having a honeycomb structure having air permeability is employed.

In the regenerative burner shown in FIG. 2, a pair of burners 2 and 3 mix a gas supplied from a gas pipe 6 with air introduced through an intake passage 11 of a three-way valve 9 in one burner 2. Then, the tube 1 is heated by burning inside the radiant tube 1. Exhaust gas generated by the combustion passes through the inside of the tube 1 and passes through the regenerator 7 of the other burner 3, at which time the heat of the exhaust gas is used to raise the temperature of the regenerator 7. A pair of burners 2,
The combustion of 3 is performed alternately every 20 to 30 seconds,
As a result, the radiant tube 1 can be heated at a substantially uniform temperature, and the inside of the heating furnace can be uniformly heated. Reference numeral 15 denotes a pilot burner for igniting the burners 2 and 3.

The three-way valves 9 and 10 and the gas switching valves 4 and 5 of the plurality of regenerative burners 21 in a predetermined combustion zone (see FIGS. 1 and 4) of the heat treatment furnace each have the same switching direction in each group. Is controlled using compressed air pumped from a compressed air source (not shown) through compressed air conduits 22-27.

The pair of compressed air conduits 22 and 23 and the pair of compressed air conduits 24 and 25 are provided with a left and right side for reciprocating the valve body inside the pair of three-way valves 9 and 10 between the intake side and the exhaust side. Two are provided. In addition, gas switching valve 4,
Since the valve body inside 5 is normally urged to be closed by a spring, the compressed air conduits 26 and 27 may be one each to obtain a unidirectional driving force.

The heat treatment furnace shown in FIG.
A common first solenoid valve 28, 29 is provided for controlling the compressed air sent to all pairs of three-way valves 9, 10 in a given combustion group through 5, respectively.

The heat treatment furnace shown in FIG.
With common second solenoid valves 30, 31 (see FIGS. 1 and 3) for controlling the compressed air respectively sent to all the gas switching valves 4, 5 in a given combustion group through 6, 27. I have.

With this configuration, in the heat treatment furnace of the present embodiment, the first solenoid valves 28 and 29 and the second solenoid valve 3
By operating 0, 31 the compressed air conduits 22-25 for the three-way valves 9, 10 and the gas switching valves 4, 5
Pressure is applied to the compressed air conduits 26 and 27 for the regenerative burner, and the three-way valves 9 and 10 and the gas switching valves 4 and 5 of the plurality of regenerative burners can be operated simultaneously. Further, the transmission speed of the pressure in the compressed air conduit after the operation of the solenoid valve is high, and the time lag during the valve operation hardly occurs, so that the solenoid valve can be shared in group units.

In the control method using the solenoid valve common to the group, the number of solenoid valves can be greatly reduced, and the capital investment and the maintenance burden can be reduced. Further, it is possible to install the solenoid valve away from the vicinity of the furnace and in a place where the temperature is low, which leads to prolonging the life of the solenoid valve and improving the reliability of valve control operation.

In the case where a crack occurs in any one of the radiant tubes 1 (see FIG. 2) of the plurality of regenerative burners 21, the supply of the combustion gas is conventionally stopped to measure the O ₂ concentration in the exhaust gas. By doing so, the occurrence of cracks is detected.

In this embodiment, a crack is detected by an increase in the exhaust gas temperature of the regenerative burner. That is,
When a crack is generated in the radiant tube 1, the amount of combustion air passing through the tropics decreases due to gas infiltration into the furnace from the crack, while the amount of exhaust gas passing through the tropics is almost the same as in the case without cracks. Since the temperature of the exhaust gas between the burner 2 and the three-way valve 9 and between the burner 3 and the three-way valve 10 at both ends of the radiant tube 1 increases, such a temperature increases. ,
17 (see FIG. 2), the occurrence of cracks can be detected.

As described above, when a crack is generated in the radiant tube 1 of a certain regenerative burner 21, a common electromagnetic valve 28 to 31 is shared with each regenerative burner 21 so that the other regenerative burner is not affected. Preferably, a manual valve 32 is provided in each of the compressed air conduits 22-27. When the occurrence of cracks in the radiant tube 1 is detected by the above-described method, the operator presses the compressed air conduits 22 to 27 leading to the abnormal regenerative burner 21.
The regenerative burner 21 becomes abnormal by closing all the manual valves 32 and fixing the three-way valve body at an appropriate position.
Only the operation is stopped, and the other normal regenerative burners 21 can be operated normally.

In the present embodiment, an example has been described in which the three-way valve for combustion ventilation and the gas switching valve are controlled by a common solenoid valve. However, the present invention is not limited to this. The present invention can also be applied to a burner mode. For example, a so-called push-pull type regenerative burner in which one four-way valve for combustion ventilation is employed instead of a pair of three-way valves, and an intake blower is connected to a four-way valve together with an exhaust blower. Further, the valve control by the group-common electromagnetic valve may be valve control of only the combustion ventilation switching valve such as the three-way valve or the four-way valve, or may be valve control of only the gas switching valve,
Valve control of both the combustion ventilation switching valve and the gas switching valve may be performed.

[0035]

According to the present invention, valve control of a plurality of regenerative burners can be performed with an inexpensive and simple configuration, and the reliability of valve control can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic view illustrating a piping of a heat treatment furnace having a common solenoid valve for controlling a three-way valve and a gas switching valve, showing an embodiment of the heat treatment furnace having a plurality of regenerative burners of the present invention. FIG.

FIG. 2 is an explanatory sectional view of the regenerative burner of FIG.

FIG. 3 is a block diagram for explaining operations of a common solenoid valve, a gas switching valve, and a manual valve of FIG. 1;

FIG. 4 is an explanatory view showing an arrangement of a regenerative burner inside the heat treatment furnace of FIG. 1;

FIG. 5 is a block diagram showing a conventional heat treatment furnace including a plurality of regenerative burners.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Radiant tube 2, 3 Burner 4, 5 Gas switching valve 9, 10 Three-way valve 21 Regenerative burner 22, 23, 24, 25 Compressed air conduit 26, 27 Compressed air conduit 28, 29 First solenoid valve 30, 31 Second Solenoid valve

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K017 BB07 BB08 3K068 AA01 BA01 BB05 BB12 BB25 CA04 3K091 AA20 BB07 BB08 BB26 CC06 CC22 EA04 EA14 EA15 EA22

Claims (6)

[Claims] 1. A regenerative burner comprising a plurality of radiant tube-type regenerative burners, and at least one combustion ventilation switching valve driven by compressed air is provided for each of the regenerative burners. A heat treatment furnace for controlling the combustion ventilation switching valves of a plurality of regenerative burners by using the compressed air so as to have the same switching direction, wherein all the combustion ventilation switching within the predetermined combustion group are performed. A heat treatment furnace equipped with a common solenoid valve for controlling the compressed air sent to the valve. 2. The heat treatment furnace according to claim 1, wherein the combustion vent switching valve comprises a three-way valve. 3. The heat treatment furnace according to claim 1, wherein the combustion vent switching valve comprises a four-way valve. 4. A plurality of regenerative burners provided with a plurality of radiant tube type regenerative burners, at least one pair of gas switching valves driven by compressed air for each of the regenerative burners, A heat treatment furnace for controlling the gas switching valve of the rating burner using the compressed air so as to have the same switching direction, wherein compressed air sent to all the gas switching valves in the predetermined combustion group is supplied. A heat treatment furnace equipped with a common solenoid valve for control. 5. A regenerative burner comprising a plurality of radiant tube-type regenerative burners, each of which is provided with at least one switching valve for combustion ventilation driven by compressed air and at least one pair of gas switching valves. A heat treatment furnace for controlling the combustion ventilation switching valve and the gas switching valve of a plurality of regenerative burners in a predetermined combustion group by using the compressed air so as to have the same switching direction. A common first solenoid valve for controlling the compressed air sent to all the combustion ventilation switching valves in the predetermined combustion group,
And a heat treatment furnace including a common second solenoid valve for controlling compressed air sent to all gas switching valves in the predetermined combustion group. 6. A heat treatment furnace according to claim 1, wherein a manual valve is provided in a compressed air conduit between each of said regenerative burners and said common solenoid valve.