JP2001179425A - Method for heating ladle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drastically reduce the amount of carbonaceous material by setting a molten steel tapping temperature from a converter low and also, to accurately control of the molten steel tapping temperature. SOLUTION: In the method for heating a ladle 1, which is placed on a molten metal receiving carriage 5 after completing a continuous casting and a slag removal, then is kept in the waiting state for a prescribed time in a molten steel receiving area D2 on the molten steel receiving carriage 5 after being carried to the molten steel receiving area D2 of the converter 3 with the molten steel receiving carriage 5 and receives the molten steel; from the converter 3 immediately after waiting, before receiving the molten steel, the ladle 1 is quickly heated with a heat-storage type burner 10 fitted to a ladle cover 12 for covering the upper part of the ladle 1 within the prescribed time keeping the waiting state in the molten steel receiving area D2 of the converter 2. Heat conductive amount into a ladle refractory is obtained from input calory and exhaust gas sensible heat at this time and also, the temperature given into the ladle 1 by quickly heating is obtained base on the heat conductive amount, the molten steel tapping quantity from the converter and the specified heat of the molten steel to control the molten steel tapping temperature of the converter 3 according to the temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for heating a ladle used in a converter operation for transporting molten steel received from a converter.

[0002]

2. Description of the Related Art Referring to FIG. 5, a ladle 1 used for a converter operation is moved to a waste area B1 by a crane 2 or the like after continuous casting, and the ladle 1 is tilted in the waste area B1. By doing so, the slag remaining inside is discharged. Next, it moves to a maintenance and inspection area (not shown), and after cleaning or replacing the sliding nozzle in the maintenance and inspection area, moves to the preheating area C1. In the preheating region C1, the ladle 1 is heated using the burner 4 or the like for the purpose of drying the ladle 1 and compensating for the temperature drop of the molten steel received from the converter 3.

Next, the ladle 1 is placed on the steel receiving cart 5 by the crane 2 or the like, and in this state, the steel receiving area D1 of the converter 3 is placed.
Transport to The ladle 1 conveyed to the steel receiving area D1 is on standby for a predetermined time on the steel receiving cart 5, and immediately after receiving the molten steel from the converter 3, the standby state is reached. After receiving the steel, the ladle 1 is transported to a secondary refining area (not shown) by the steel receiving cart 5, and in the secondary refining area, the molten steel in the ladle 1 is subjected to secondary refining by, for example, the RH method.

[0004] Next, the ladle 1 on the steel receiving carriage 5 is moved to the continuous casting area A1 by the crane 2 or the like. In the continuous casting area A1, the ladle 1 is installed in an existing continuous casting machine, and the ladle 1 is placed.
By operating the opening of the sliding nozzle provided below, the required flow of molten steel is continuously supplied to the tundish to perform continuous casting, and after the continuous casting, the above steps are repeated to operate. I do.

[0005]

By the way, the tapping temperature of the converter 3 is determined so that the molten steel temperature until the end of the continuous casting can be secured. Therefore, the amount of drop of the molten steel temperature in the ladle 1 after receiving steel has a great influence on the converter tapping temperature. However, in the conventional converter operation, the preheating region C1
Since the time from heating the ladle 1 to receiving the molten steel in the steel receiving area D1 is long, especially after the steel receiving area D1 is in standby, the temperature of the ladle refractory decreases due to natural cooling while the steel is received. As a result, the temperature drop of the molten steel becomes large, and as a result, it becomes necessary to set the converter tapping temperature high to secure the molten steel temperature until the end of continuous casting. However, there is a disadvantage that the amount of carbonaceous material (coke and the like) increases.

Further, since the temperature difference between the temperature of the ladle 1 at the time of receiving the steel and the temperature of the converter is increased, the thermal attack of the refractory of the ladle is increased and the life of the refractory is shortened. In addition, there is a disadvantage that the temperature distribution of the molten steel in the ladle 1 varies greatly. Furthermore, since the heating time of the ladle 1 by the burner in the preheating region C1 also requires a long time, there is a disadvantage that a large amount of fuel gas (C gas or the like) must be used during the heating.

SUMMARY OF THE INVENTION The present invention has been made to solve such inconvenience, and it is possible to significantly reduce the amount of carbonaceous material by setting the converter tapping temperature low, and to control the tapping temperature accurately. In addition, the thermal attack can be mitigated and the basic unit of the ladle refractory can be improved, and the amount of fuel gas used when the ladle is heated by the burner can be reduced, contributing to energy saving. It is an object of the present invention to provide a method of heating a ladle that can be performed.

[0008]

In order to achieve the above object, a method for heating a ladle according to the present invention is arranged such that the ladle is placed on a steel receiving cart after continuous casting and waste disposal, and then the steel receiving tray is heated. After being transported to the steel receiving area of the converter by the bogie, the steel receiving area is put on standby in the steel receiving area for a predetermined time. After the standby, the steel is immediately moved to the steel receiving position to receive molten steel from the converter. In the method for heating a ladle to be steel before receiving the steel, the ladle is attached to a pan lid that covers an upper opening of the ladle within a predetermined time in a standby state in the steel receiving area of the converter. Rapid heating by a type burner, the amount of heat of the ladle refractory is determined from the input heat amount and the exhaust gas sensible heat at that time, and the rapid heating is performed based on the amount of heat, the output of the converter and the specific heat of the steel. Obtaining the temperature given to the ladle by the above, and controlling the tapping temperature of the converter according to the temperature. And it features.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view for explaining a ladle heating method as one example of an embodiment of the present invention. FIG. 2 is a diagram showing a rapid heating of a ladle on a steel receiving cart by a regenerative burner during standby in a steel receiving area. Explanatory diagram for explaining the method of
FIG. 3 is a plan view of FIG. 2, and FIG. 4 is a schematic view for explaining the operation of the regenerative burner.

Referring to FIG. 1, a ladle 1 used for the operation of a converter is subjected to a continuous casting, and then a slag area B by a crane 2 or the like.
2 and the slag remaining inside is discharged by tilting the ladle 1 in the waste area B2. Next, it moves to a maintenance and inspection area (not shown), and after cleaning or replacing the sliding nozzle in the maintenance and inspection area, moves to the heat retention area C2. In the heat retaining area C2, the ladle 1 is not heated by the conventional burner, but the upper opening of the ladle 1 is covered with the pan lid 1a to keep the ladle 1 warm.

Next, the ladle 1 is placed on the steel receiving cart 5 by the crane 2 or the like, and in this state, the steel receiving area D2 of the converter 3 is placed.
Transport to The ladle 1 conveyed to the steel receiving area D2 is on standby for a predetermined time on the steel receiving cart 5, and during the standby, the ladle 1
The ladle 1 is rapidly heated using the regenerative burner 10 for the purpose of drying the steel and compensating for the temperature drop of the molten steel received from the converter 3.

Immediately after the rapid heating, the molten steel is received from the converter 3 immediately, and after the steel is received, the ladle 1 is transported to a secondary refining area (not shown) by the steel receiving carriage 5, and in the secondary refining area. The molten steel in the ladle 1 is secondarily refined by, for example, the RH method. Then
The ladle 1 on the steel receiving trolley 5 is moved to the continuous casting area A2 by the crane 2 or the like. In the continuous casting area A2, the ladle 1 is installed in an existing continuous casting machine and provided below the ladle 1. By operating the sliding nozzle, the required flow rate of molten steel is continuously supplied to the tundish to perform continuous casting. After the continuous casting, the above-described steps are repeated to operate.

Next, referring to FIG. 2 to FIG.
The ladle 1 on the steel receiving cart 5 waiting at 2 is stored in the regenerative burner 10
The method of rapid heating will be described. In FIGS. 2 and 3, reference numeral 11 denotes a portal frame, and the portal frame 11 is disposed at a standby position of the steel receiving truck 5 in the steel receiving region D2 so as to straddle the transport path of the steel receiving truck 5. . A circular pot lid 12 that covers the upper opening of the ladle 1 on the steel receiving cart 5 is supported on the gate-shaped frame 11 by a lifting device 100 so as to be able to move up and down. The regenerative burner 10 is attached to the pot lid 12. Have been.

First, the lifting device 100 will be described. The lifting device 100 supports the upper surface of the pot lid 12 at two places separated in the width direction of the steel receiving cart 5 to suspend the pot lid 12 so as to be able to move up and down. Each of the chains 101 and 102 extends upward from the upper surface of the pot lid 12, and then is connected to the steel receiving cart 5 via sprockets 103 and 104 attached to the upper part of the portal frame 11. The end extends horizontally in the width direction and is connected to the connecting member 105 at its tip.

One chain 106 is connected to the connecting member 105.
Are connected, and the chain 106 is connected to the chain 10
The sprocket 10 extends horizontally to the side away from the first and second 102 and is mounted on the upper part of the portal frame 11.
The front end is connected to the counter weight 108 by extending downward through the counter 7. The counterweight 108 has a weight that balances the weight of the pot lid 12 including the regenerative burner 10.

The sprocket 107 is connected to the drive motor 1
09, the pot lid 12 is moved up and down together with the regenerative burner 10 by driving the drive motor 109 forward and reverse. At the time of such ascending and descending, four slide bars 110 projecting from the upper surface of the pot lid 12 are vertically guided by guide cylinders 111 attached to the upper part of the portal frame 11 in accordance with the number of the slide bars 110. It is supposed to be.

Next, the regenerative burner 10 will be described. The regenerative burner 10 has a pair of burner portions 112a and 112b mounted on the upper surface of the pot lid 12 so as to be separated from each other in the conveying direction of the steel receiving cart 5. And the burner section 112
a and 112b are heat storage bodies 113 made of ceramics or the like.
a and 113b are integrally attached. Thermal storage 11
3a and 113b respectively have a supply pipe 11 for combustion air.
4a, 114b and an exhaust pipe 121a, 1 for a combustion exhaust gas.
21b is connected.

The supply pipes 114a and 114b have switching valves 115a and 115b interposed therebetween.
The supply pipes 114a and 114b join on the upstream side to form one supply pipe 116. In the supply pipe 116,
A flow regulating valve 117 and a flow meter (orifice) 118 are sequentially interposed toward the upstream side, and the upstream end reaches a supply fan 119 mounted on the upper part of the portal frame 11. Further, as shown in FIG.
It has a vertically extending portion, and the portion includes a pot lid 1
A bellows 120 is interposed to enable the ascending and descending of the second.

On the other hand, switching valves 122a and 122b are interposed in the exhaust pipes 121a and 121b.
On the upstream side of the on-off valves 122a and 122b, the heat storage body 113
Thermometers T _a and T _b for measuring the exhaust gas temperature on the outlet side of the a and 113b are attached. Also, the exhaust pipe 12
1a and 121b are joined on the downstream side to form one exhaust pipe 12
The exhaust pipe 123 is provided with a flow meter (orifice) 124 and a flow control valve 125 in order toward the downstream side. The downstream end of the exhaust pipe 123 reaches an exhaust fan 126 attached to the upper part of the portal frame 11. As shown in FIG. 2, the exhaust pipe 123 has a vertically extending portion, and a bellows 127 is interposed in this portion to enable the pan lid 12 to move up and down.

Fuel gas supply pipes 128a and 128b are connected to the burner sections 112a and 112b, and switching valves 129 are provided to the supply pipes 128a and 128b.
a, 129b are interposed. In addition, the supply pipe 128
a and 128b are joined on the upstream side to form one supply pipe 130
The flow control valve 131 and the flow meter (orifice) 132 are sequentially interposed in the supply pipe 130 toward the upstream side. As shown in FIG. 2, the supply pipe 130 has a vertically extending portion, and a bellows 133 is interposed in the portion to enable the pot lid 12 to be moved up and down. In FIG. 4, a symbol _Tc is a thermometer for measuring the temperature in the ladle 1.

Next, a method for heating the ladle 1 using the regenerative burner 10 having such a configuration will be described. When the steel receiving cart 5 on which the ladle 1 is placed is transported to the steel receiving area D2 of the converter 3 and stops at a predetermined position of the portal frame 11, this is detected by a position detection sensor attached to a column or the like of the portal frame 11. (Not shown), and based on the detection signal, a drive motor 109 mounted on the upper part of the portal frame 11 drives the sprocket 107 to rotate in a direction in which the counterweight 108 rises, and thereby, the heat storage type The pot lid 12 to which the burner 10 is attached descends to close the upper opening of the ladle 1. At the time of such closing, since the pot lid 12 to which the regenerative burner 10 is attached is balanced by the counterweight 108, the impact when the pot lid 12 abuts on the upper opening edge of the ladle 1 can be reduced. The upper opening edge can be prevented from being broken.

Next, in this state, the burners 112a, 1
The ladle 1 is rapidly heated during the standby time of the steel receiving cart 5 by burning the 12b alternately. For example, when burning the burner portion 112a, the on-off valve 115a of the supply pipe 114a for combustion air and the on-off valve 12 of the supply pipe 128a for fuel gas are used.
9a and on-off valve 122 of exhaust pipe 121b of combustion exhaust gas
b, the on / off valve 115b of the combustion air supply pipe 114b and the on / off valve 12 of the fuel gas supply pipe 128b.
9b and the on-off valve 122 of the exhaust pipe 121a of the combustion exhaust gas
a is closed, thereby burning the burner portion 112a to heat the ladle 1 by the radiant heat of the flame and the combustion gas, and exhausting the exhaust gas from the combustion through the heat storage body 113b and the exhaust pipes 121b and 123.

On the contrary, when the burner section 112b is burned, the on-off valve 115b of the combustion air supply pipe 114b,
The on-off valve 129b of the fuel gas supply pipe 128b and the on-off valve 122a of the combustion exhaust gas exhaust pipe 121a are opened, and the on-off valve 115a of the combustion air supply pipe 114a is opened.
The on / off valve 129a of the fuel gas supply pipe 128a and the on / off valve 122b of the combustion exhaust gas exhaust pipe 121b are closed, thereby burning the burner section 112b and heating the ladle 1 by the radiant heat of the flame and the combustion gas. Exhaust gas from the combustion is stored in the heat storage body 113a and the exhaust pipes 121a, 1a.
Discharge through 23. The on-off valves 115a, 115
The switching of b, 122a, 122b, 129a, 129b and the opening of the flow control valves 117, 125, 131 according to the measured values of the flow meters 118, 124, 132 are sequence-controlled by a heating control device (not shown). ing.

Here, the burners 112a, 1
12b are alternately burned, so that the burner 112
a, 112b is supplied to the heat storage 113
a, 113b, so as to be preheated to a high temperature close to the exhaust gas temperature, so that when mixed with fuel gas, stable combustion can be performed with a small amount of fuel to obtain a high-temperature combustion gas. Rapid heating is performed.

After the rapid heating, the drive motor 109 mounted on the upper part of the portal frame 11 drives the sprocket 107 to rotate in the direction in which the counterweight 108 descends, whereby the pot on which the regenerative burner 10 is mounted. The lid 12 is lifted to open the upper opening of the ladle 1, and in this state, it is immediately moved to the steel receiving position to receive the molten steel from the converter 3, and after the steel is received, the ladle 1 is removed by the steel receiving cart 5. The steel is transported to a secondary refining area (not shown) to perform secondary refining. After the secondary refining, the ladle 1 on the steel receiving carriage 5 is moved to the continuous casting area A2 by the crane 2 or the like to perform continuous casting. Do.

Next, a method of controlling the tapping temperature of the converter 3 according to the temperature given to the ladle 1 by the rapid heating will be described. In this embodiment, the amount of heat of the ladle refractory is determined from the amount of heat input during rapid heating and the sensible heat of exhaust gas, and rapid heating is performed based on the amount of heat, the amount of steel output from the converter, and the specific heat of the steel. To determine the temperature given to the ladle 1 and control the tapping temperature of the converter 3 according to the temperature.

The details will be described below. Where m: air ratio,
V _G : fuel gas flow rate per unit time, A _O : theoretical air amount, V _E : recovered gas amount per unit time, V _{E total} :
Exhaust gas amount per unit time, G _O : theoretical exhaust gas amount,
Q _G : calorific value of fuel, T _E : exhaust gas temperature at regenerator outlet,
S ₁ : Ladle refractory area, t ₁ : heating time, C _P : specific heat of exhaust gas on the exit side of the heat storage unit, V _E ': unrecovered gas amount per unit time, T _E ': unrecovered gas temperature, C _P ' : Specific heat of unrecovered gas, Q: Ladle refractory calorific value, M: Converter tapping amount, C _P0 : Specific heat of steel, T: Reduced tapping temperature by ladle heating, S ₂ : Rapid heating device Pot cover area.

The amount of heat input during rapid heating is determined by the following equation (1), and the sensible heat of exhaust gas is determined by the following equation (2).

[0029]

(Equation 1)

[0030]

(Equation 2)

Here, Q_GIs the set value, V_G, V_EIs the flow rate
The deviation between the actual value or set value measured by the
If it is within 5%, the set value may be used. Also,
V_E'Is the exhaust gas flow rate V_{E total}= V_G× ｛G_O+ A
_OFrom (m-1)｝, recovered gas amount V_ERequired by subtracting
Value, T_EIs the thermometer T_aOr thermometer T_bThe value obtained from
T_E'Is a thermometer T_cThe value obtained from C_PIs T_EAnd gas
Value obtained from composition, C_P'Is T _E′ And gas composition
Value.

The heat quantity Q of the ladle refractory can be obtained by subtracting the exhaust gas sensible heat from the input heat quantity, and is expressed by the following equation (3).

[0033]

(Equation 3)

The calculations up to this point are performed by the above-mentioned heating control device, and the amount of heat Q of the ladle refractory obtained by the heating control device is a process computer for controlling the amount of carbon material charged into the converter and the amount of oxygen blown into the converter. (Not shown). In the process computer, T = Q / MC _P0 from the ladle refractory heating value Q, converter output M and specific heat C _{P0 of} steel.
The temperature T given to the ladle 1 is determined by using the relational expression (1), and the temperature (T ₀ −) obtained by subtracting the temperature T from the temperature T ₀ determined for each steel type in advance so that the molten steel temperature until the end of continuous casting can be secured.
T) is the tapping temperature, and the amount of carbon material charged and the amount of oxygen blown are controlled so as to reach the tapping temperature.

As described above, in this embodiment, the ladle 1 is heated until immediately before the molten steel is received from the converter 3.
The heat content of the ladle refractory at the time of receiving steel can be greatly increased as compared with the conventional case, and as a result, the tapping temperature of the converter 3 determined so as to ensure the molten steel temperature until the end of continuous casting is reduced. It is possible to set the temperature lower, and it is possible to reduce the amount of the carbonaceous material as the heating material to be charged during the converter blowing.

In addition, the amount of heat of the ladle refractory is determined from the amount of heat input during rapid heating and the sensible heat of exhaust gas, and the amount of heat is determined by rapid heating based on the amount of heat, the amount of steel output from the converter, and the specific heat of the steel. The temperature given to the pan 1 is determined, and the converter 3
Is controlled based on only the surface temperature of the ladle 1 raised by rapid heating.
The tapping temperature can be controlled more accurately than when tapping temperature is controlled.

Further, since the temperature difference between the temperature of the ladle 1 and the temperature of the converter at the time of receiving the steel can be reduced, the thermal attack of the refractory of the ladle is alleviated and the life of the refractory is extended. And variation in the temperature distribution of the molten steel in the ladle 1 can be reduced. Furthermore, since the heating time can be greatly reduced as compared with the conventional heating of the ladle 1 by the burner in the preheating region C1, the amount of fuel gas (C gas or the like) used at the time of heating can be reduced.
It can contribute to energy saving.

[0038]

As is apparent from the above description, according to the present invention, the converter tapping temperature can be set low, the amount of carbon material can be greatly reduced, and the tapping temperature can be controlled. Accurately, furthermore, it is possible to reduce the thermal attack and improve the basic unit of ladle refractory, and to reduce the amount of fuel gas used when heating the ladle by the burner, contributing to energy saving. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining a ladle heating method which is an example of an embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining a method of rapidly heating a ladle on a steel receiving cart by a regenerative burner during standby in a steel receiving area.

FIG. 3 is a plan view of FIG. 2;

FIG. 4 is a schematic diagram for explaining the operation of the regenerative burner.

FIG. 5 is an explanatory diagram for explaining a conventional ladle heating method.

[Explanation of symbols]

 A2: continuous casting area B2: waste area C2: heat retaining area D2: steel receiving area 1: ladle 3: converter 5: steel receiving cart 10: regenerative burner 12: pan lid (3)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Daisuke Takahashi 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. 1-chome (without address) Kawasaki Steel Corporation Mizushima Works F-term (reference) 4E014 AA03 AB01 EA01 4K002 AF05 BA08

Claims (1)

[Claims] After completion of continuous casting and slagging, it is placed on a steel receiving truck, and then transported by a steel receiving truck to a steel receiving area of a converter. In a method of heating the ladle for receiving molten steel from the converter immediately before receiving the molten steel from the converter, the ladle is set to a standby state for a predetermined time in the steel receiving area of the converter after the standby. The ladle is rapidly heated by a regenerative burner attached to a pan lid that covers an upper opening of the ladle within a predetermined time in a standby state, and a ladle refractory is obtained from the input heat amount and the exhaust gas sensible heat at that time. And the amount of heat
Determining the temperature given to the ladle by the rapid heating based on the heat amount, the amount of tapping of the converter and the specific heat of the steel, and controlling the tapping temperature of the converter according to the temperature. Ladle heating method.