WO2000020147A1

WO2000020147A1 - The method for drying and heating of the casting ladle lining and the device to accomplish these processes

Info

Publication number: WO2000020147A1
Application number: PCT/PL1998/000040
Authority: WO
Inventors: Jerzy Tomeczek; Zbigniew Sikora; Andrzej Adamiec; Jan GÓRAL; Janusz Kowalik; Jerzy Kowalski; Józef OCHMAN; Maciej Rozpondek; Janusz SŁOWIŃSKI; Sławomir STARZYKOWSKI
Original assignee: Huta Buczek S.A.
Priority date: 1998-10-08
Filing date: 1998-10-08
Publication date: 2000-04-13

Abstract

The object of the present invention is the method for drying and heating of the casting ladle, and a device to accomplish these processes. In the method according to the invention, the ladle (3) is closed tight by the cover (2), and the processes of drying and heating of the ladle (3) are performed at two programmable substrates rates of the outflow from the self-recuperative burner (10). A device according to the invention contains the self-recuperative burner (1) situated in plane of the cover (2) closing the heated space of the ladle (3). Before starting the drying and heating processes, the ladle (3) is aligned in horizontal position, or tilted from horizontal position, or placed in vertical position, depending on a modification of the device being used. Owing to the mechanisms which enable horizontal and/or vertical shift of the ladle (3) towards the cover (2) it is possible to apply a device according to the invention to drying and heating of conventionnal ladles, stoppered ladders and lip-pour ladles of capacities ranging from 5 to 350 Mg.

Description

The method for drying and heating of the casting ladle lining

and the device to accomplish these processes

The object of the present invention is a method for drying and heating of the casting ladle lining, and a device for drying and heating the casting ladle lining.

The drying process requires very slow and uniform increase in temperature with regulated rate depending on the ladle capacity. The heating rate in the drying process

is within the range of a few to several °C/h. The heating process proceeds at conside¬

rably higher heating rates amounting to over 100°C/h. Up to present, a number of methods for drying and heating of the ladle have been developed.

From the Polish patent no 158 841 the method is known for drying of the fireproof steel ladle lining as well as the station for drying the fireproof steel ladle lining, a device utilizing the enthalpy of the combustion gases arising from another source. The reported method consists in that into a newly lined ladle the steel ingots of the ini¬

tial temperature of 800°C are introduced and kept in the ladle under untight covering

until the temperature reduces to 450°C, followed by replacing the ingots by successive ingots of high temperature, the drying process being conducted until the temperature

outside the armour reaches 60° to 80°C.

Another method for drying and heating of the ladle with the use of a device equipped with a recuperator was described by H. Kroger and W. Schnabel in "Steel

Times" 10 (1988). Also a device is known for drying and heating of the steel ladles with the use of self-recuperative burner, where heating of the ladle occurs through the outflow nozzles of the gaseous fuel and air situated in the ladle interior at its bottom. Temperature uniformity is obtained owing to the multi-hole nozzles applied.

The disadvantages of such a solution include a high leakage amounting to 10 - 30 %, accompanied by unsatisfactory gasodynamics of the burner. Further inconveniences include a possibility of damaging the device due to improper placement of the burner relative to bottom of the ladle, as well as a possibility of using a burner to the ladle of only one capacity. In addition, the process of drying the ladle is performed in an unsatisfactory way due to the local overheating of the ladle bottom.

The method for drying and heating of the casting ladle lining with the use of self-recuperative burner consists in that the ladle situated in the drying and heating station is aligned horizontally, followed by pushing towards each other the cover and the ladle to close it tight. Then, the substrates outflow rate at the outlet of the self-recuperative burner situated in the cover is settled within the range of 5 to 120 m/s, followed by turning the burner on, and, in the case of the newly lined or regenerated ladles the drying process is conducted at lower substrates outflow rates and at the

heating rate amounting to 3-10°C/h until the settled temperature of isothermal heat resistance is reached. Then, the heating is restarted using higher substrates outflow

rates until the reached final temperature of heating the ladle does not exceed 1300°C,

at which the burner is automatically turned off. In the case of the exploited ladles the

drying stage is omitted, and only the heating is performed at higher rates of the sub¬

strates outflow from the burner. After heating, the ladle is moved to the casting station by means of standard mechanical tools. The reported method for drying and heating of the ladle can be conducted also in other modifications, in which the ladle is tilted from horizontal plane at the angle not

larger than 30°, and pushed close to the appropriately positioned cover in order to close tight, or the ladle mounted vertically is moved to the cover previously hung on the stands of various construction. The remaining stage of the drying and heating process is conducted according to the procedure described above.

A device for drying and heating of the casting ladle according to the invention contains a self-recuperative burner with the attached gas and air pipes, and the combustion gases offtake. The burner consisting of the air nozzles aligned concentrically with the inner gas nozzle, not whirling the gas jet, is settled in the cover, whereas at its outlet situated in plane of the cover closing the ladle a pipe-shaped combustion stabilizer is installed. From the inside, the cover is lined with a fibre stable to heat, levelling the irregularities on the entire surface of the ladle lining, the fibre being the seal of an interior of the ladle during the drying and heating processes. The cover is mounted to the base settled on the foundation, whereas the ladle is pushed close to the cover by means of a car with road wheels positioned on the steel rails. On the car are mounted a loose wheel unit and power wheel unit combined with a reducer driven with an electric motor. On the wheel units a turn-table with the ladle is placed. The power wheel unit has a wheel with chain teeth in mesh with a toothed sector of a pin rack aligned concentrically with the raceway which constitutes an integral part of the turn-table. The turn-table has two walls situated perpendicularly relative to each other, one of which being a base to settle the ladle, whereas the other has the pins of different heights constituting a support of the ladle in the service position, the pins enabling horizontal

alignment of the conical surface of the ladle jacket during its displacement towards the cover. In the service position the turn-table moves around making the upper surface of the ladle align parallel to the cover, whereas the car displaced by means of a hydraulic cylinder fixed with a shackle to the base and with a piston rod to the holder mounted to the frame of the car makes the ladle meet with the cover when moving towards the cover, thus closing tight the heating system.

In a modification, the ladle is placed on the seat in the car by means of a pin system and a screw gear. The seat has the pins of different heights constituting a support of the ladle in the service position which enable to align the conical surface of the ladle jacket horizontally on pushing the ladle close to the cover. The screw gear enables the correction of the lack of parallelism of the cover surface and the upper surface of the ladle.

In another modification intended for the stoppered ladles, the cover is mounted to the stand settled on the foundation, whereas on the stand a ladle hoist is fixed, which lifts the ladle towards the cover or falls the ladle down. The hoist is equipped

with the rollers settled on the rails, the rollers tread and rolling surface of the rails being prismatic in shape. The hoist is set in motion by means of a piston rod of the hydraulic cylinder, whereas the ladle is displaced onto the hoist via the car moving on the rails.

In the case of drying and heating of the so called lip-pour ladle (tilting ladle), the

ladle is placed vertically, and the cover is fixed to a rotary outrigger suited to make 90° turn in horizontal plane. The outrigger is connected to a movable part of the stand

which moves in vertical plane, whereas an immovable part of the stand settled on the

foundation has two sets of rollers sliding a movable part of the stand. In an immovable part of the stand a seat is situated where the ladle is placed. The pipes supplying gas and air to the burner are fixed to the burner, and in the area not subjected directly to heat emissioned from the ladle these pipes are connected with the installations by fie- xible pipes enabling to turn the cover as well as to move the cover upward and downward. The combustion gases offtake above its bend has a telescope connection enabling the turn as well as the upward and downward motion. The upward and downward displacement of a movable part of the stand is accomplished by means of the hydraulic cylinder.

The method according to the invention ensures the heating of the ladle to be uniform, controlled and in compliance with technological requirements, being accompanied by reduced emission of gaseous NO_x contaminations to below 38 ppm, i.e. 20.1 g/GJ, and of CO to below 28 ppm, i.e. 9.1 g/GJ. The process conducted according to the method described ensures to obtain the castings without structural defects, and to prolong time between overhauls of the ladle lining.

A device according to the invention enables drying and heating of the ladles of various charge capacities and different constructions, such as among others the stoppered ladles and lip-pour ladles, and also allows to recover heat from the combustion gases, which may be utilized for drying and heating of the charge material for melting.

The object of the invention is shown in the drawings. Fig. 1 presents a vertical projection of the device for drying and heating of the casting ladle, where the cover is placed on the base and the ladle is located on the turn-table in the starting position. Fig. 2 provides the same solution, but in the service position, Fig. 3 - a vertical projection of a device with the ladle placed on the seat in the service position, Fig. 4 - a vertical projection of a modified device with the cover placed on the stand, and the ladle

equipped with a stopper mechanism located on the fork hoist, Fig. 5 - a vertical pro¬

jection of the device with the cover lifting mechanism and the mechanism of the cover

turn to 90°, where the cover is mounted to the rotary outrigger, whereas Fig. 6 shows the same modification in a horizontal projection. As shown on the drawing in Fig. 1 the self-recuperative burner with the gas and air supplying pipes as well as the combustion gases offtake is mounted in the cover 2 lined with kaolin fibre 2a stable to heat, playing the role of a seal of an interior of the ladle 3 during its drying and heating. The cover 2 is mounted to the base 4 settled on the foundation. A car 5 with the road wheels 6 is placed on the rails 7. On the car 5 is mounted a loose wheel unit 8 and a power wheel unit 9 coupled with a reducer 12 driven by an electric motor 1_3. On the wheel units 8 and 9 a turn-table 17 is placed. The power wheel unit 9 has a wheel with chain teeth 14 in mesh with a toothed sector of a pin rack 1_5 aligned concentrically with the raceway 16 which constitutes an integral part of the turn-table 17. The turn-table 17 has two walls situated perpendicularly relative to each other, one of which being a base to settle the ladle 3, whereas the other has the pins 18 of different heights constituting a support of the ladle 3 in the service position, the pins enabling horizontal alignment of the conical surface of the jacket of the ladle 3, which ensures the work safety during transportation of the ladle 3 by the car 5 towards the cover 2.

Fig. 2 shows the ladle 3 after turning which makes the upper surface of the ladle 3 align parallel to the cover 2 and reaching contact with it. The car 5 is driven by means of a hydraulic cylinder 19 fixed with a shackle to the base 20 and with a piston

rod to the holder 2Λ mounted to the frame of the car 5.

Fig. 3 illustrates the ladle placed on the seat 22 settled on the car by means of a pin system 23 and a screw gear 24. The seat 22 has the pins 18 of different heights constituting a support of the ladle 3 in the service position, and enabling to align the conical surface of the ladle jacket 3 horizontally pushing the ladle 3 close to the cover 2. The screw gear 24 enables the correction of the lack of parallelism of the cover surface 2 and the upper surface of the ladle 3. The drying and heating station, shown in Fig. 4, for the casting stoppered ladles has a self-recuperative burner 1 with the attached gas pipe, air pipe and combustion gases offtake - 33, 34 and 35, respectively. The burner 1 is settled in the cover 2 lined with kaolin fibre 2a, stable to heat, constituting a seal of an interior of the ladle 3 during its drying or heating. The cover 2 is mounted to the stand 25 settled on the foundation, whereas on the stand 25 a fork hoist 26 is attached, which lifts the ladle 3 towards the cover 2 or downward. The hoist 26 is equipped with the rollers 27 which are placed on the rails 28, the rollers tread 27 and rolling surface of the rails 28 being prismatic in shape. The hoist 26 is set in motion by means of a piston rod 27 of the hydraulic cylinder. The ladle 3 is displaced onto the fork hoist 27 with the aid of the car 30 moving on the rails 32, started by means of a driving gear 31

In Fig. 5 a station is shown for drying and heating of the so called lip-pour ladle in vertical position. The self-recuperative burner 1 with the attached gas, air and combustion gases pipes, 33, 34 and 35, respectively, is settled in the cover 2 lined with kaolin fibre 2a constituting a seal of an interior of the ladle 3 during its drying or heating.

The cover 2 is mounted to the rotary outrigger 36 suitable to make a 90° - turn in horizontal plane. The outrigger 36 is attached to a movable part of the stand 37a which moves in vertical plane. An immovable part of the stand 37 is fixed on the foundation. It contains two sets of the rollers 38 sliding a movable part of the stand 37a. In an immovable part of the stand 37 is settled a seat 37b where the ladle 3 is placed. The gas pipe 33 and air pipe 34 are fixed to the burner 1, and in the area not subjected directly to heat emissioned from the ladle 3 the pipes 33 and 34 are connected with the instal¬

lations by flexible pipes 33a and 34a enabling to turn the cover 2 as well as to move the cover upward and downward. The combustion gases offtake 35 above its bend has a telescope connection enabling the turn as well as the upward and downward motion. The upward and downward displacement of a movable part 37a of the stand

37 is accomplished by means of the hydraulic cylinder 39.

The method for drying and heating of the casting ladle lining is described in the example which takes into account the principle of operation of a device for drying and heating of the casting stoppered ladle made according to Fig. 4 of the drawing.

The self-recuperative burner with the attached gas, air and combustion gases

pipes, 33, 34 and 35, respectively, is settled in the cover 2 lined with kaolin fibre 2a, whereas the cover 2 is mounted to the stand 25 settled on the foundation. The ladle 3 placed on the car 30 is displaced towards the device for drying and heating, followed by placing the ladle onto the fork hoist 26, lowered to the extreme lower position, used to lift the ladle 3 towards the cover 2 aligned horizontally relative to the outrigger of the stand 25 thus making the ladle 3 close tight. Upon closing, the ladle 3 there occurs an ignition of the burner working in two operation modes, and the drying process of the

ladle lining 3 starts at the heating rate ranging from 3 to 10°C/h, which corresponds to the first programmed operation mode of the burner 1 Upon reaching the temperature

of isothermal heat resistance inside the ladle, usually close to 200°C, the drying process is stopped, and operation of the burner 1 is switched to the second of its bistable operation modes, the heating being then restarted at higher rate of the substrates outflow from the burner outlet, preferably amounting to 60 - 120 m/s. The ladle lining 3 is heated until the desired temperature is reached, then the hoist 26 is lowered to its extreme lower position, the ladle 3 is removed from the station by the car 30, and by means of standard mechanical tools, e.g. ladle crane, the ladle 3 is displaced to the melt station.

Claims

1. The method for drying and heating of the fireproof casting ladle lining realized with the use of recuperative burner, characteristic in that the ladle (3) situated in the area of the station for drying and heating is placed on the turn-table (17) and aligned horizontally, followed by pushing the ladle (3) and the cover (2) close to each other in

order to close the ladle tight, and then the substrates outflow rate within the range of 5

to 120 m/s is settled at the outlet of the recuperative burner (V) situated in the cover (2), followed by starting the burner (1), and in the case of newly lined or regenerated ladles the drying process is conducted at lower rates of the substrates outflow and at

the heating rate amounting to 3-10°C/h until the desired temperature of isothermal heat resistance is reached, and then the heating is restarted at higher rates of the sub¬

strates outflow until the final temperature of heating the ladle does not exceed 1300°C,

at which the burner (1) is automatically switched off, for the exploited ladles the drying stage being omitted and only heating being conducted at higher rates of the substrates outflow from the burner (1J.

2. The process according to claim 1 , characteristic in that the ladle (3) is situated

in a position where its roll axis is tilted from horizontal plane at the angle less than

±30°, followed by pushing the ladle close to the cover (2) mounted on the base (4) and

positioned at the angle corresponding to the angle at which the ladle (3) is placed.

3. The process according to claim 1 , characteristic in that the ladle (3) is mounted

on the seat (22) and pushed close to the cover (2) positioned on the base (4).

3. The method for drying and heating of the fireproof casting ladle lining, in particular that of the stoppered ladles, is conducted with the use of recuperative burner,

characteristic in that the ladle (3) situated in the area of drying and heating station is placed on the car (30), which is used to displace the ladle towards the base of the fork hoist (26), by means of which the ladle is lifted towards the cover (2) settled hori¬

zontally in the stand (25) achieving a tight closing of the ladle (3) by the cover (2), and

then, the rate of the substrates outflow at the outlet of the self-recuperative burner (1_) situated in the cover (2) is settled within the range of 5 to 120 m/s, followed by starting

the burner (1), and, in the case of the newly lined or regenerated ladles, conducting the drying process at lower rates of the substrates outflow and at the heating rate

amounting to 3 - 10°C/h until the desired temperature of isothermal heat resistance is reached, and then the heating is restarted at higher substrates outflow rates until the

final temperature of heating the ladle not exceeding 1300°C is attained, at which the burner (1) is automatically switched off, for the exploited ladles the drying stage being

omitted and only the heating being conducted at higher rates of the substrates outflow

from the burner (1).

4. The method for drying and heating of the fireproof casting ladle lining, in particular that of the lip-pour ladle, realized with the use of the recuperative burner, characteristic in that the ladle (3) situated in the area of drying and heating station is settled

on the seat (37b) of the stand (37), whereas the cover (2) kept horizontally in the rota¬

ry outrigger (36) situated in a movable part (37a) of the stand (37) is moved over the

ladle (3) and lowers to the edge of the ladle (3) achieving tight closing, and then, the

rate of the substrates outflow at the outlet of self-recuperative burner (1_) situated in the

cover (2) is settled within the range of 5 to 120 m/s, followed by starting the burner (V),

and, for the newly lined or regenerated ladles, conducting the drying process at lower

rates of the substrates outflow and at the heating rate amounting to 3 - 10°C/h until the settled temperature of isothermal heat resistance is achieved, and then, the heating is restarted at higher rates of the substrates outflow until attaining the final temperature of heating the ladle, not exceeding 1300°C, at which the burner (1) is automatically switched off, for the exploited ladles the drying stage being omitted and only the heating being conducted at higher rates of the substrates outflow from the burner (1).

6. A device for drying and heating of the casting ladle containing the self-recuperative burner placed in the cover of the ladle being heated, characteristic in that the ladle (3) is mounted on the turn-table (17) placed on the car (5) equipped with a hyd¬

raulic mechanism for horizontal moving composed of a loose wheel unit (8) and power

wheel unit (9) coupled with a reducer (12) driven with an electric motor (13), the unit

(9) having a wheel with chain teeth (14) in mesh with a toothed sector of a pin rack

(15) aligned concentrically with the raceway (16) of the turn-table (17), whereas the co¬

ver (2) being mounted to the base (4) situated on the foundation, while the inner surfa¬

ce of the cover (2) being lined with a layer of heat-resisting needled cloth (2a), the bur¬

ner (1) being equipped with the air nozzles situated concentrically with the inner gas nozzle not whirling the gas jet, and inside the air nozzles there are the wedge-like paddles, and nearby the outlet of the burner (1) placed in plane of the cover (2) closing

the ladle (3) a pipe-shaped combustion stabilizer is placed.

7. A device according to claim 6, characteristic in that the ladle (3) is mounted on

the seat (22) with the pins (18) of different heights constituting a support of the ladle

(3), the seat being placed on the car (5) by means of the pin system (23) and the

screw gear (24) being used to correct a parallelism of the upper surface of the ladle (3)

and the cover (2) mounted to the base (4) settled on the foundation.

8. A device according to claim 6, characteristic in that the ladle (3) is situated on

the fork hoist (26) built-in the vertical stand (25), equipped with the rollers (27) placed

on the rails (28) fixed to the stand (25) which in addition keeps the cover (2) placed ho- rizontally, whereas the hoist (26) is equipped with a mechanism of vertical lifting with the piston rod (29) of hydraulic servomotor.

9. A device according to claim 6, characteristic in that the ladle (3) is settled on the

seat (37b) of an immovable part of the stand (37) placed on the foundation, to the movable part (37a) of the stand being fixed the rotary outrigger (36) keeping the cover (2)

in horizontal position, on an immovable part of the stand (37) being built-in the set of

rollers (38) sliding a movable part (37a) being started with the piston rod (39), whereas

the gas pipe (33) and the air pipe (34) are fixed to the burner (1), and in the area not

subjected directly to heat emissioned from the ladle (3) these pipes are connected with

the air and gas installations by flexible connectors (33a, 34a), whereas the combustion

gases offtake (35) above its bend is connected with the installation of combustion gases offtake via telescope connection.