KR100973886B1 - Apparatus for controlling press of annealing furnace during atmosphere gas change - Google Patents

Abstract

According to the present invention, in the strip annealing process of the bright annealing furnace, the supply flow rate of the bright annealing furnace is automatically controlled even when the density of the atmospheric gas is changed according to the mixing ratio of the hydrogen / nitrogen atmosphere gas according to the steel grade, so that the pressure is always kept stable. It is an object of the present invention to provide a pressure stabilization control device for converting atmospheric gas.

The present invention, the pressure monitoring unit 110; A setpoint smoothing unit 120; A set value change detector 130; Pressure setting value selection unit 140; Pressure controller 150; Cooling zone flow setpoint selector 160; Cooling zone flow controller 170; Heating zone flow setpoint selector 180; And a heated flow rate controller 190.

According to the present invention, the prevention of contamination of innet silol and outnet silol, improvement of the surface quality of the strip, cost reduction through the reduction of the use of atmospheric gas, elimination of causes of production disruption by satisfying the annealing working conditions, and prevention of large equipment accidents Has the effect of achieving

Bright Annealing Process, Annealing Furnace, Atmospheric Gas, Furnace Pressure Stabilization

Description

Pressure regulating control device for switching atmospheric gas {APPARATUS FOR CONTROLLING PRESS OF ANNEALING FURNACE DURING ATMOSPHERE GAS CHANGE}

1 is a block diagram of a conventional bright annealing facility.

2 is a configuration diagram of atmospheric gas supply of a conventional bright annealing facility.

Figure 3 is a configuration diagram of the atmospheric gas supply of the bright annealing equipment according to the present invention.

(A) and (b) is a block diagram of the no-pressure stabilization control apparatus of FIG.

5 is an operation time chart of the set value smooth unit 120 of FIG. 3.

6 is a flowchart showing a no-pressure stabilization method at the time of switching the atmosphere gas according to the present invention.

Explanation of symbols on the main parts of the drawings

110: no-pressure monitoring unit 120: set value smooth unit

130: set value change detection unit 140: no pressure set value selection unit

150: no-pressure controller 160: cooler flow rate set value selector

161: multiplier 162: selector

163 multiplier 164 selector

170: cooling stage flow rate controller 180: heating stage flow rate setting value selection unit                 

181: multiplier 182: selector

183: Multiplier 184: Selector

190: heating table flow controller

The present invention relates to a no-pressure stabilization control device when converting the atmosphere gas in the bright annealing furnace, and in particular, in the strip annealing process of the bright annealing furnace, By automatically controlling the supply flow rate of the annealing furnace to keep the furnace pressure stable at all times, it prevents contamination of the innet seal and outnet seal rolls, improves the surface quality of the strip, and reduces the cost by reducing the use of atmospheric gases and annealing. The present invention relates to a no-pressure stabilization control device when converting the atmosphere gas to achieve the elimination of the cause of production disruption and the prevention of large-scale equipment accidents by satisfying the conditions.

In general, the bright annealing furnace of stainless cold rolling mill is divided into heating zone and cooling zone. In the heating zone, depending on the steel type, the atmosphere gas composed of hydrogen / nitrogen is blown at a temperature of about 900 to 1300 ° C. Anneal the strip as it is made, and lower the plate temperature to 150 – 200 ° C on the cooling stand.

1 is a configuration diagram of a conventional bright annealing equipment, Figure 2 is a configuration diagram of the atmosphere gas supply of the conventional bright annealing equipment.

1 and 2, in the conventional bright annealing facility, the bright annealing furnace 1 is largely divided into a heating table 4 and a cooling table 5. When the atmospheric gas 3 is supplied, the heating table ( 4) The muffle (6) is installed inside and filled with the atmosphere gas (3), the burner (burner) is installed outside the muffle (6) is heated to about 900 ~ 1300 ℃. Then, the strip 2 is annealed while passing through the muffle 6 filled with the atmosphere gas 3, and the muffle 6 shields the strip 2 from the oxygen O 2 in the atmosphere and the strip 2 is external. Oxygen (O2) component that can be sucked when entering the bright annealing furnace (1) to the atmosphere gas (3) in order to prevent the chemical reaction of the strip (2) to deteriorate the surface quality of the strip (2) Hydrogen (7) is added to make a reducing component crisis.

However, the lower grade steel grades whose surface quality is not important because hydrogen (7) is very expensive may be introduced into the atmosphere gas (3) mixed with nitrogen (8), the higher the ratio of nitrogen (8) The cost of the atmosphere gas (3) can be reduced, but the surface quality of the strip (2) can be deteriorated, so it is mainly used in low grade steels where surface quality is not important. In the current manufacturing technology, hydrogen (7) and nitrogen (8) ), The mixing ratio of 80%: about 20%, and 100% hydrogen (7) in the muffle (6) atmosphere to the lower grade steel grade, the mixing ratio of hydrogen (7): nitrogen (8) is 20%: 80 Atmospheric gas (3) is converted to the atmosphere gas (3) at this time, the density of the atmosphere gas (3) increases by the gas content, the actual flow rate is reduced, the pressure inside the muffle (6) is lowered and detected by the no-pressure detection pressure gauge (14) There is a problem that the pressure is reduced.

In addition, in the annealing conditions of the bright annealing furnace 1, when the no-pressure detected by the no-pressure detection pressure gauge 14 decreases, it is determined that the atmospheric gas 3 leaks, thereby shutting off the hydrogen 7 and supplying 100% of nitrogen. This is to prevent the explosion caused by the hydrogen (7) is leaked to the outside.

Accordingly, the operator 13 opens and anneales the cooling zone atmosphere gas control valve 9 and the heating zone atmosphere gas control valve 11 before the pressure detected by the pressure detection pressure gauge 14 decreases below a certain range. The flow rate is adjusted to satisfy the conditions and supply sufficient atmosphere gas 3 so that the interior of the muffle 6 can be maintained in a reducing atmosphere. In addition, when the high-grade steel grade is produced again, hydrogen (7) 100% of atmospheric gas (3) is supplied, and at this time, the opposite phenomenon occurs. Atmospheric gas control valve 11 is closed to an appropriate flow rate.

To recapitulate the above process, lower grade steel conversion => atmosphere gas (3) change (100% hydrogen = 80% hydrogen, 20% nitrogen) => increase in atmospheric gas density => decrease in feed flow rate => muffle (6) Internal pressure decrease => operator (13) valve open => increase in flow rate => muffle (6) internal pressure rise => low grade steel grade production => high grade steel grade conversion => atmosphere gas (3 ) Change (80% hydrogen, 20% nitrogen => 100% hydrogen) => decrease in atmospheric gas density => increase in feed flow rate => increase in muffle (6) internal pressure => operator 13 close valve => Reduced flow rate => Reduced pressure inside muffle (6) => High grade steel grade production sequence.

However, in the conventional bright annealing operation, the influencing factors are the dew point and annealing temperature in the bright annealing furnace 1, the cooling temperature, the degree of oxidation of the surface of the strip 2, and the mixing ratio of hydrogen / nitrogen in the atmospheric gas. When the hydrogen / nitrogen mixing ratio is applied differently according to the steel type, the density of the atmosphere gas (3) changes according to the change of the mixing ratio of hydrogen / nitrogen injected into the bright annealing furnace (1), and thus the flow rate changes. When the flow rate changes, the pressure in the furnace occurs, and the fine powder accumulated in the furnace is scattered and contaminates the strip 2, the innet silol 15, and the outer silol 16, thereby degrading the surface quality of the strip 2. There is a problem that occurs.

In other words, if the pressure in the bright annealing furnace 1 is severely changed, the powder accumulated in the interior (17, muffle 6) is used, and the powder is generated in a hydrogen atmosphere, and the exact cause of the dust is still unknown. The strip 2, the innet silol 15, and the outer silol 16 are contaminated, resulting in deterioration of the surface quality of the strip 2. The pressure detected by the pressure detection pressure gauge 14 that monitors the pressure inside the muffle 6 is adjusted to match the pressure and the flow rate. Bright Annealing Furnace (1) The operator (13) operates the valve manually, and if the operator (13) fails to operate the valve properly, waste of atmospheric gas (3) occurs and surface quality of the strip (2) occurs. In addition, the annealing conditions of the bright annealing furnace 1 using hydrogen 7 may not be satisfied, which may cause a production disruption and a large equipment accident.

The present invention has been proposed to solve the above problems, the object of which is in the strip annealing step of the bright annealing furnace, even when the density of the atmospheric gas changes depending on the mixture ratio of hydrogen / nitrogen atmosphere gas according to the steel type By automatically controlling the supply flow rate to keep the furnace pressure stable at all times, it prevents contamination of the innet seal and outnet seal rolls, improves the surface quality of the strip, and reduces the cost by reducing the use of atmospheric gas and satisfies the annealing work conditions. It is to provide a pressure stabilization control device when converting the atmosphere gas that can eliminate the cause of production disruption and prevent the occurrence of large-scale equipment accidents.

In order to achieve the above object of the present invention, the no-pressure stabilization control device of the present invention                     

A no-pressure monitoring unit for determining whether the pressure by the no-pressure detection pressure gauge is equal to or greater than a preset upper limit set value SV1 or less than a preset lower limit set value SV2;

A set value smooth unit which gradually changes the gas concentration set value SV3 during a preset change necessary time ST when the no pressure change signal is input from the no pressure monitoring unit;

A set value change detection unit detecting a falling and a rising of the gas concentration setting value SV3 by using the output signal S120 of the set value smoothing unit;

 A no-pressure set value selection unit for selecting one of the gas concentration set value (SV3) or the output signal (S120) of the set value smooth unit according to the detection signal of the set value change detection unit and the detection signal of the no pressure monitoring unit;

A no-pressure controller for controlling the nitrogen flow control valve VL1 according to the deviation value between the set value and the detected value selected by the no-pressure set value selector;

According to the monitoring result of the no-pressure monitoring unit, the multiplication value S161 obtained by multiplying the cooling table atmospheric gas flow rate set value correction value SV12 and the cooling table atmospheric gas flow rate set value SV11 by the no-pressure rise, and the cooling-zone atmosphere gas flow rate when no-pressure drop is performed. A cooling zone flow rate setting value selecting unit for selecting one of a multiplication value S163 obtained by multiplying the setpoint correction value SV13 by the cooling zone atmosphere gas flow rate setting value SV11 and the cooling zone atmosphere gas flow rate setting value SV11;

A cooling zone flow rate controller for controlling a nitrogen cooling zone atmosphere gas flow control valve VL2 according to a deviation value between a set value selected by the cooling zone flow rate setting value selection unit and a detection value;                     

The multiplication value S181 obtained by multiplying the heating table atmosphere gas flow rate value SV22 and the heating table atmosphere gas flow rate setting value SV21 according to the monitoring result of the no-pressure monitoring section, the heating table atmosphere gas flow rate value SV23 and A heating table flow rate setting value selecting unit for selecting one of a multiplication value S183 multiplied by the heating table atmosphere gas flow rate setting value SV21 and the heating table atmosphere gas flow rate setting value SV21; And

Heating table flow controller for controlling the nitrogen heating table atmosphere gas flow control valve (VL3) in accordance with the deviation value between the set value and the detection value selected by the heating table flow rate setting value selector

Characterized in having a.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings referred to in the present invention, components having substantially the same configuration and function will use the same reference numerals.

Figure 3 is a configuration diagram of the atmospheric gas supply of the bright annealing equipment according to the present invention.

(A) and (b) is a block diagram of the no-pressure stabilization control apparatus of FIG.

3, 4 (a) and (b), the pressure stabilization control device at the time of switching the atmosphere gas according to the present invention is the pressure by the pressure detection pressure gauge 14 or more than the preset upper limit set value (SV1) or The gas pressure setting value SV3 during the change necessary time ST, which is set in advance when the pressure change signal is input from the pressure monitoring unit 110 and the pressure monitoring unit 110 that determines whether or not the preset lower limit set value SV2 is less than or equal to a predetermined value. ) And a set value change detection unit 130 for detecting the falling and rising of the gas concentration set value SV3 using the set value smooth unit 120 gradually changing the value) and the output signal S120 of the set value smooth unit 120. And selecting one of the gas concentration set value SV3 or the output signal S120 of the set value smooth unit 120 according to a detection signal of the set value change detection unit 130 and a detection signal of the no-pressure monitoring unit 110. No pressure set value selector 140 and the furnace No pressure controller 150 for controlling the nitrogen flow control valve VL1 according to the deviation value between the set value selected by the set value selector 140 and the detected value, and the no pressure according to the monitoring result of the no pressure monitoring unit 110. Multiplication value S161 multiplied by the cooling stage atmosphere gas flow rate setpoint correction value SV12 and the cooling stage atmosphere gas flow rate setpoint SV11, cooling zone atmosphere gas flow rate setpoint correction value SV13 and cooling stand atmosphere A multiplication value S163 multiplied by the gas flow rate setting value SV11, a cooling zone flow rate setting value selection unit 160 for selecting one of the cooling zone atmosphere gas flow rate setting values SV11, and the cooling zone flow rate setting value selection unit ( Cooling zone flow controller 170 for controlling the nitrogen cooling zone atmosphere gas flow control valve (VL2) in accordance with the deviation value between the set value and the detection value selected by 160, and in accordance with the monitoring results of the pressure monitoring unit 110 Heating atmosphere at elevated pressure The multiplication value S181 which multiplied the switch flow rate value SV22 and the heating table atmosphere gas flow rate setting value SV21, and the multiplication value obtained by multiplying the heating table atmosphere gas flow rate setting value SV23 and the heating table atmosphere gas flow rate setting value SV21 at the time of no-pressure drop. S183), the heating table flow rate setting value selector 180 which selects one of the heating table atmosphere gas flow rate setting values SV21, and the nitrogen heating table atmosphere according to the deviation value between the set value selected by the heating table flow rate setting value selector and the detected value. Heating bed flow controller 190 for controlling the gas flow control valve (VL3).

The cooling stage flow rate setting value selector 160 provides a multiplier 161 which multiplies the cooling stage atmosphere gas flow rate setting value SV12 and the cooling stage atmosphere gas flow rate setting value SV11 when the pressure rises. And a selector 162 for switching from the cooling zone atmosphere gas flow rate setting value SV11 to the output value of the multiplier 161 when the pressure in the furnace pressure monitoring unit 110 is greater than or equal to an upper limit. A multiplier 163 for providing a multiplication value S163 by multiplying the flow rate set value correction value SV13 by the coolant atmosphere gas flow rate set value SV11, and when the no pressure is less than or equal to the lower limit value in the no-pressure monitoring unit 110, And a selector 164 for switching from the output of the selector 162 to the output of the multiplier 163.

The cooling zone atmosphere gas flow rate setpoint correction value SV12 is set to a value smaller than one, and the cooling zone atmosphere gas flow rate setpoint correction value SV13 is set to a value greater than one.

The heating table flow rate setting value selector 180 includes a multiplier 181 for providing a multiplication value S181 for multiplying the heating table atmosphere gas flow rate value SV22 and the heating table atmosphere gas flow rate setting value SV21 when the pressure rises. When the pressure in the furnace 110 is equal to or higher than the upper limit, the selector 182 for switching from the heating table atmosphere gas flow rate setting value SV21 to the output value of the multiplier 181, the heating table atmosphere gas flow rate value SV23 and the heating table when the pressure falls. A multiplier 183 providing a multiplication value S183 multiplied by the atmospheric gas flow rate setting value SV21 and the multiplier (at the output value of the selector 182 when the no pressure is lower than or equal to a lower limit in the pressure monitoring unit 110). And a selector 184 for switching to the output value of 183.

The heating zone atmosphere gas flow rate value SV22 is set to a value smaller than one, and the heating zone atmosphere gas flow rate value SV23 is set to a value greater than one.

Hereinafter, the operation and effects of the present invention will be described in detail with reference to the accompanying drawings.

The bright annealing furnace 1 of the present invention performs annealing at about 900 ° C to 1200 ° C. If the steel grade conversion is carried out during the operation, it is necessary to change the composition of the atmosphere gas (3) necessary for the converted steel grade, and the gas concentration set value (SV3) is changed to suit the production steel grade.

FIG. 5 is an operation time chart of the set value smooth unit 120 of FIG. 3, and FIG. 6 is a flowchart illustrating a no-pressure stabilization method when switching atmospheric gas according to the present invention.

Referring to Figure 3 to 6 with reference to the pressure stabilization control device when switching the atmosphere gas according to the present invention, first, the set value smooth unit 120 of the present invention when the pressure change signal input from the pressure monitoring unit 110 In addition, the relay contact 52 is switched so that the output is fed back to the input, thereby gradually changing the gas concentration set value SV3 during the preset change required time ST, after which the change required time ST has elapsed. In this case, the contact 52 is returned, and the gas concentration set value SV3 is input (S51-S55).

In other words, when the gas concentration set value SV3 is changed abruptly, the set pressure smooth unit 120 is used to change the set value slowly so as to prevent this from changing rapidly. This function changes slowly as the time entered. The preset change required time (ST) required when the set value smooth unit 120 operates is different from the capacity of the bright annealing furnace 1, the operation method, and other site conditions, so that the driver of the site may input an appropriate value. To help.

The no-pressure monitoring unit 110 of the present invention determines whether the pressure by the no-pressure detection pressure gauge 14 is equal to or higher than the preset upper limit set value SV1 or lower than the lower limit set value SV2 (S56-S59). When the pressure by the detection pressure gauge 14 is more than the upper limit set value SV1, the output of the comparator 39 becomes high, and the fourth TR 41 is turned on to operate the relay 72 (at the time of no-pressure rise). When the pressure by the no-pressure detection pressure gauge 14 is equal to or lower than the lower limit set value SV2, the output of the comparator 40 becomes high, and the fifth TR 42 is turned on to operate the relay 73 (at the time of no-pressure drop). . If any of the outputs of the fourth TR 41 or the fifth TR 42 is low, the output of the exclusive oar gate 45 becomes high so that the no-pressure fluctuation signal S110 is set to the smooth value 120. TR 58 is then turned on to operate the relay 59.

In the present invention, since the flow rate of the cooling table atmosphere gas and the heating table atmosphere gas flow rate is controlled by switching from the manual valve to the control valve so that the flow rate control is performed by the controllers 170 and 190 in real time, there is no sudden change in the flow rate.

The setpoint change detection unit 130 of the present invention detects the fall and rise of the gas concentration setpoint SV3 by using the output signal S120 of the setpoint smoother 120. The first comparator 26 and the second comparator 27 of the change detection unit 130 receive and compare the output value S120 of the set value smooth unit 120 and the gas concentration set value SV3.

The first comparator 26 operates when the gas concentration set value SV3 rises (for example, when the concentration of hydrogen gas rises to 80% => 100%) and operates the first TR 28 to output 29 Value is set to a low potential, and the second comparator 27 operates when the gas concentration set value SV3 is lowered (for example, when the concentration of hydrogen gas is lowered to 100% => 80%). ) The second TR 29 is operated so that the value of the output 31 becomes a low potential. When either the output 30 of the first TR 28 or the output 31 of the second TR 29 is in a low potential state, the output 33 is high by the NAND gate 32 (NAND). ) And the S / R flip-flop 34 (S / R FF) is SET to operate the third TR 35 and the third TR 35 to operate the relay 36. On the other hand, if the gas concentration set value SV3 and the output signal S120 of the set value smooth unit 120 are the same, the relay 36 does not operate.

The no-pressure set value selector 140 according to the present invention detects the gas concentration set value SV3 or the set value smooth unit 120 according to the detection signal of the set value change detection unit 130 and the detection signal of the no pressure monitoring unit 110. When one of the output signals S120 is selected, that is, when the relay 36 of the set value change detection unit 130 operates, the relay contact is switched to select the output signal S 120 of the set value smooth unit 120 as the set value. . On the other hand, if the relay 36 does not operate, the relay contact returns and the gas concentration set value SV3 is selected as the set value.

The no-pressure controller 150 of the present invention controls the nitrogen flow control valve VL1 according to the deviation value between the set value selected by the no-pressure set value selector 140 and the detected value by the hydrogen concentration analyzer, and there may be no-pressure fluctuations. In this case, since the nitrogen flow control valve VL1 is controlled based on the set value 120 by the set value smooth part 120, the no-pressure can be stabilized.

Cooling zone flow rate setting value selector 160 of the present invention according to the monitoring results of the pressure monitoring unit 110, the cooling zone atmosphere gas flow rate set value correction value (SV12) and cooling zone atmosphere gas flow rate set value (SV11) at the time of no-pressure rise. Multiplication value S161 multiplying by, multiplication value S163 obtained by multiplying the cooling zone atmosphere gas flow rate setting value correction value SV13 and the cooling zone atmosphere gas flow rate setting value SV11 by the lowering of the pressure, and the cooling zone atmosphere gas flow rate setting value. One of (SV11) is selected, which will be described in more detail as follows (S61-S65).

First, when the pressure rises, the multiplier 161 of the cooling zone flow rate setting value selector 160 multiplies the cooling zone atmosphere gas flow rate setting value SV12 and the cooling zone atmosphere gas flow rate setting value SV11 when the pressure rises. The value S161, and then the selector 162 sets the cooling zone atmosphere gas flow rate setting value SV11 when the no pressure is higher than the upper limit in the no pressure monitoring unit 110, that is, when the relay 72 is operated. Switch to the output value of the multiplier 161 at. Here, the value SV12 is set to a value smaller than 1 in advance, thereby lowering the cold pressure of the cooling zone and thereby stabilizing (S61-S63).

At the next lower pressure drop, the multiplier 163 of the cooling table flow rate setting value selector 160 multiplies the cooling table atmosphere gas flow rate setting value SV13 and the cooling table atmosphere gas flow rate setting value SV11 when the pressure falls. (S163), the selector 164 of the multiplier 163 at the output value of the selector 162 when the pressure is below the lower limit in the pressure monitoring unit 110, that is, the relay 73 is operated. Switch to the output value. Here, the value SV13 is set to a value greater than 1 in advance, thereby increasing the pressure of the cooling stand to stabilize it (S61, S64, S65).

The cooling zone flow rate controller 170 according to the present invention is a nitrogen cooling zone atmosphere gas flow rate according to the deviation value between the set point S164 selected by the cooling zone flow rate setting value selector 160 and the detected value by the density corrector 65. Control valve VL2.

The heating table flow rate setting value selector 180 of the present invention multiplies the heating table atmosphere gas flow rate value SV22 and the heating table atmosphere gas flow rate setting value SV21 according to the monitoring result of the pressure monitoring unit 110. (S181), a multiplication value S183 obtained by multiplying the heating table atmosphere gas flow rate value SV23 and the heating table atmosphere gas flow rate setting value SV21 by the lower pressure, and the heating table atmosphere gas flow rate setting value SV21 is selected. More detailed description is as follows.

The multiplier 181 of the heating table flow rate setting value selector 180 provides a multiplication value S181 for multiplying the heating table atmosphere gas flow rate value SV22 and the heating table atmosphere gas flow rate setting value SV21 when the pressure rises. In the pressure monitoring unit 110, the pressure is equal to or higher than the upper limit, that is, when the relay 73 is operated, the heating table atmosphere gas flow rate setting value SV21 switches from the output value of the multiplier 181. Here, the value SV22 is set to a value smaller than 1 in advance, thereby increasing the furnace pressure in the heating table and thereby stabilizing it.

The multiplier 183 of the heating table flow rate setting value selecting unit 180 provides a multiplication value S183 obtained by multiplying the heating table atmosphere gas flow rate setting value SV23 and the heating table atmosphere gas flow rate setting value SV21 at the time of lowering the pressure. 184 switches from the output value of the selector 182 to the output value of the multiplier 183 when the pressure is less than or equal to the lower limit in the pressure monitoring unit 110. In this case, the value SV23 is set to a value greater than 1 in advance, thereby increasing the furnace pressure of the heating table and stabilizing it.

The heating table flow rate controller 190 of the present invention operates the nitrogen heating table atmosphere gas flow rate control valve VL3 according to a deviation value between the set value S184 selected by the heating table flow rate setting value selector and the detected value by the density compensator 66. To control.

According to the present invention as described above, in the strip annealing process of the bright annealing furnace, the supply flow rate of the bright annealing furnace is automatically controlled even when the density of the atmospheric gas changes in accordance with the mixture ratio of hydrogen / nitrogen atmosphere gas according to the steel type To keep the product stable at all times, preventing contamination of innet silol and outnet silol, improving the surface quality of the strip, reducing the cost by reducing the use of atmospheric gas, eliminating the cause of production disruption by satisfying the annealing working conditions, There is an effect that can prevent the prevention of large equipment accidents.

The above description is only a description of specific embodiments of the present invention, and the present invention is not limited to these specific embodiments, and various changes and modifications of the configuration are possible from the above-described specific embodiments of the present invention. It will be apparent to those skilled in the art to which the present invention pertains.

Claims (5)

A no-pressure monitoring unit 110 for determining whether the pressure by the no-pressure detection pressure gauge 14 is greater than or equal to a preset upper limit set value SV1 or less than or equal to a preset lower limit set value SV2; A set value smooth unit 120 which gradually changes the gas concentration set value SV3 during a preset change necessary time ST when the no pressure change signal is input from the no pressure monitoring unit 110; A set value change detection unit (130) for detecting the falling and rising of the gas concentration set value (SV3) by using the output signal (S120) of the set value smooth unit (120);  No pressure for selecting one of the gas concentration set value SV3 or the output signal S120 of the set value smooth unit 120 according to a detection signal of the set value change detection unit 130 and a detection signal of the no pressure monitoring unit 110. A set value selector 140; A no pressure controller 150 for controlling the nitrogen flow control valve VL1 according to the deviation value between the set value selected by the no pressure set value selector 140 and the detected value; According to the monitoring result of the pressure monitoring unit 110, a multiplication value S161 obtained by multiplying the cooling zone atmospheric gas flow rate setpoint correction value SV12 and the cooling zone atmospheric gas flow rate setpoint SV11 by the no-pressure increase, and cooling at the time of no-pressure drop. Selection of the cooling zone flow rate setting value for selecting one of the multiplication value S163 obtained by multiplying the large atmosphere gas flow rate setting value correction value SV13 and the cooling zone atmosphere gas flow rate setting value SV11 and the cooling zone atmosphere gas flow rate setting value SV11. Unit 160; A cooling zone flow rate controller 170 that controls the nitrogen cooling zone atmosphere gas flow rate control valve VL2 according to a deviation value between the set value selected by the cooling zone flow rate setting value selector 160 and the detected value; According to the monitoring result of the pressure monitoring unit 110, a multiplication value S181 obtained by multiplying the heating table atmosphere gas flow rate value SV22 and the heating table atmosphere gas flow rate set value SV21 by the pressure rise, and the heating table atmosphere gas flow rate value when the pressure falls. A heating table flow rate setting value selecting unit 180 for selecting one of a multiplication value S183 obtained by multiplying the SV23 and a heating table atmosphere gas flow rate setting value SV21 and the heating table atmosphere gas flow rate setting value SV21; And Heating table flow controller 190 for controlling the nitrogen heating table atmosphere gas flow control valve (VL3) in accordance with the deviation value between the set value and the detection value selected by the heating table flow rate setting value selection unit No-pressure stabilization control device when switching the atmosphere gas characterized in that it comprises a. The method of claim 1, wherein the coolant flow rate setting value selector 160 A multiplier 161 which provides a multiplication value S161 for multiplying the cooling zone atmosphere gas flow rate setpoint correction value SV12 and the cooling zone atmosphere gas flow rate setpoint SV11 when the pressure rises; A selector 162 for switching from the cooling zone atmosphere gas flow rate setting value SV11 to the output value of the multiplier 161 when the pressure is higher than the upper limit in the pressure monitoring unit 110; A multiplier 163 which provides a multiplication value S163 obtained by multiplying the cooling zone atmosphere gas flow rate setpoint correction value SV13 and the cooling zone atmosphere gas flow rate setpoint SV11 at the time of lowering of the no-pressure; And Selector 164 for switching from the output value of the selector 162 to the output value of the multiplier 163 when the pressure is less than the lower limit in the pressure monitoring unit 110. Pressure stabilization control device when switching the atmosphere gas, characterized in that it comprises a. 3. The cooling system atmosphere gas flow rate setpoint correction value SV12 according to claim 2, Is set to a value less than 1, The cooling zone atmosphere gas flow rate setpoint correction value (SV13) is No-pressure stabilization control device when switching the atmosphere gas, characterized in that set to a value greater than 1. The method of claim 1, wherein the heating table flow rate setting value selector 180 A multiplier 181 for providing a multiplication value S181 for multiplying the heating table atmosphere gas flow rate value SV22 and the heating table atmosphere gas flow rate setting value SV21 at the time of no pressure increase; A selector 182 for switching from the heating zone atmosphere gas flow rate setting value SV21 to an output value of the multiplier 181 when the pressure in the furnace pressure monitoring unit 110 is equal to or higher than an upper limit value; A multiplier 183 providing a multiplication value S183 obtained by multiplying the heating table atmosphere gas flow rate value SV23 and the heating table atmosphere gas flow rate setting value SV21 at the time of lowering of the no-pressure; And Selector 184 for switching from the output value of the selector 182 to the output value of the multiplier 183 when the pressure is less than or equal to the lower limit in the pressure monitoring unit 110. Pressure stabilization control device when switching the atmosphere gas, characterized in that it comprises a. The method of claim 4, wherein the heating zone atmosphere gas flow rate value (SV22) Is set to a value less than 1, The heating zone atmosphere gas flow rate value (SV23) is No-pressure stabilization control device when switching the atmosphere gas, characterized in that set to a value greater than 1.

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