RU2841308C1 - Device for drying and heating steel-teeming ladles - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy. Device for drying and heating steel ladles comprises chamber (1) with opening (4) for installation of ladle (2), exhaust unit (8) for the exhaust gases removal from inner space (17) of chamber (1) through exhaust pipe (9) and supply pipeline (11) from outlet side (12) for the exhaust gases supply to burner (7). Exhaust pipe (9) is made composite and has fixed section (13), which passes through chamber (1), and, on inlet side (15), movable portion (14), which is adapted to telescopically move relative to fixed portion (13) and is located inside chamber (1). Making of exhaust pipe with movable section allows changing position of intake point of gases released during drying of steel ladle lining.

EFFECT: providing utilization of gases formed at steel ladle drying, and excluding ingress of hazardous substances into air of working zone.

1 cl, 1 dwg

Description

The invention relates to metallurgy, more specifically to drying and heating the lining of steel-pouring ladles before filling them with liquid metal.

The ladle is used to transport liquid metal and pour molds, has a steel casing, the walls and bottom of which are lined from the inside with refractory material in the form of brickwork. For cast iron pouring, the ladle is lined with chamotte, and for steel pouring - with chamotte or magnesite. After lining, the ladles must be thoroughly dried until all moisture is removed, in addition, the refractory lining of the ladle must be heated to a specified temperature before feeding liquid metal into the ladle in order to prevent two phenomena - crystallization of the metal in the ladle, on the one hand, and damage to the lining of the ladle due to thermal shock, on the other hand.

During drying, about 50% of toxic gases are released from the steel ladle lining, and the remaining part forms the carbon crystal lattice of the molded refractories. Gaseous substances released from the brick lining, such as benzene, phenol, formaldehyde and cresol, are carcinogens or at least carcinogenic and have a direct impact on the production environment and, accordingly, on the health of the people working there.

During traditional drying of steel ladles, these gases escape through the evaporation holes in the steel ladle casing, polluting the air of the working area, and are also emitted untreated into the atmosphere through the chimney.

In recent decades, environmental protection requirements and, accordingly, environmental regulations around the world have become increasingly strict. And the ability to detect and measure hazardous substances has become much better. It is logical that maximum permissible concentrations of pollutants are becoming increasingly stringent.

From a technical point of view, there are three known solutions for neutralizing exhaust gases:

- afterburning in a separate afterburning chamber;

- catalytic afterburning at lower temperatures than thermal;

- direct afterburning in a steel ladle.

A device for heating pouring ladles is known (patent RU No. 2104122, B22D 41/015 (1995.01), published 10.02.1998), in which the pouring ladle is placed in a closed chamber, and the combustion products of the supplied gas are removed from the working cavity of the ladle using appropriate pipelines connected to a suction fan.

A device for implementing a method for drying buckets is also known (patent RU No. 2094171, B22D 41/015 (1995.01), published 10/27/1997), in which the bucket is placed in a closed volume, and combustion products are removed both from the bucket cavity and additionally from the closed volume.

A common drawback of the known devices is that the toxic exhaust gases are directed through pipelines to the afterburning chamber and there, at more than 800°C and with oxygen supplied, they are burned. On the way to the afterburning chamber, the gases are cooled and must be reheated to 800°C using additional energy. The thermal energy generated during combustion, especially of phenol, remains unclaimed and is released into the atmosphere. Depending on the length and diameter, the pipelines used are quite expensive.

Catalytic afterburning has a significant drawback, which is the decrease in the efficiency of the catalysts over time, so it is necessary to change the expensive catalyst kit approximately once a year, as well as the lining of the pre-chamber every 3 months.

In the case of direct thermal afterburning, the evaporated toxic gases are collected in a chamber and fed back into the steel ladle. There, at a temperature of over 800°C and with the addition of additional oxygen through nozzles in the ladle lid, the harmful fumes are heated and almost completely burned. The thermal energy generated during the afterburning of harmful substances is automatically used to further heat the lining of the steel ladle. As a result of afterburning with the addition of additional oxygen, only carbon dioxide (CO ₂ ) and water (H ₂ O) are formed in the steel ladle.

The closest in technical essence to the claimed invention is the device described in the heating system and method for heating a ladle for receiving liquid metal material (patent RU No. 2624580, B22D 41/015 (2006.1), published on 04.07.2017, Bulletin No. 19), including a ladle installed in a space limited by a mantle and heated by a flame torch from a burner installed on the ladle cover. To remove exhaust gases, the mantle has a through exhaust duct with an inlet located on the inner side of the mantle. In this case, the exhaust gases removed from the inner space of the mantle are supplied to the burner through a gas pipeline for combustion.

The disadvantage of the known device is that this design does not allow for the complete removal of harmful gases from the inner space of the lining. The steel ladle is equipped with channels or evaporation holes over the entire surface of the casing to remove water vapor when drying the lining, and harmful hydrocarbon compounds (exhaust gases) evaporate from the ladle through these evaporation holes.

The amount of evaporated gases (gas density) depends on the mass of the working lining of the ladle. Ladles have different capacities and, accordingly, differ in geometric parameters, in particular, height. The location of the evaporation holes depends on the ladle height, and, as a result, the epicenter of the cloud of evaporated gases is different for each ladle.

The ladles at each plant are different in height and diameter, and the use, as in the prototype, of one stationary exhaust channel for the removal of evaporated gases does not allow for the high-quality removal of harmful gases from the interior of the lining. Depending on the manufacturer of molded refractories, the amount of binder in the brickwork of the lining may vary. Accordingly, the amount and density of evaporated gases also differs from ladle to ladle, which directly affects the location of the epicenter of evaporation.

Thus, a permanently installed exhaust duct does not guarantee complete removal of harmful gases from the batter space before the end of the drying process. To eliminate this drawback, it is necessary to increase the ventilation time of the internal batter space, but this leads to additional decarbonization of the lining and a decrease in the service life of the lining.

The use of several exhaust ducts or installations simultaneously is not economically or structurally feasible (it increases the dimensions of the equipment, increases labor costs for maintenance, etc.).

The problem that the invention is aimed at solving is to increase the efficiency of removing harmful gases formed during the drying of steel ladle linings, as well as to increase the safety of work during this process.

The technical result achieved by implementing the invention is the complete utilization of harmful gases and the elimination of harmful substances from entering the air of the working area due to the adaptation of the claimed device to buckets with different locations of the epicenter of the evaporated harmful gases.

The specified technical result is achieved in that the device for drying and heating steel ladles contains a chamber with an opening for installing a ladle, a closing device for closing the chamber opening. The ladle has an opening for filling it with liquid metal, a lid for closing this opening, and a burner installed in the ladle lid. The device contains an exhaust unit with an exhaust pipe passing through the chamber on the inlet side for removing gases from the interior of the chamber and a supply pipeline on the outlet side for feeding the removed gases to the burner. The exhaust pipe is made composite and has a fixed section and a section movable from the inlet side, wherein the section movable from the inlet side is designed with the possibility of telescopic movement relative to the fixed section, wherein the fixed section of the exhaust pipe passes through the chamber, and the movable section of the exhaust pipe is located inside the chamber.

In accordance with the invention, the point of collection of harmful gases during drying of the ladle lining can be changed by changing the position of the movable section of the exhaust pipe along the height of the chamber.

The design of the device for drying and heating steel ladles is illustrated by a drawing, which shows:

Fig. 1 - shows the basic diagram of the claimed device.

The device for drying and heating steel ladles includes a chamber 1 for installing a ladle 2 through an opening 4, a closing device 5 for closing the opening 4. The ladle 2 has an opening 3 for filling it with liquid metal and a cover 6 for closing the opening 3, a burner 7 for creating a flame torch 16, installed in the cover 6. In addition, the device contains an exhaust unit 8 with an exhaust pipe 9 on the inlet side 10 for removing gases from the internal space 17 of the chamber 1 and a supply pipeline 11 on the outlet side 12 for feeding the removed gases to the burner 7. The exhaust pipe 9 has a fixed section 13 and a movable section 14 on the inlet side 15. The steel ladle 2 is equipped with evaporation holes 18 and 19 over the entire surface of the casing (not indicated in the drawing).

The device operates as follows.

The steel-pouring ladle 2 with a lining (not shown in the figure), which must be dried or heated, is installed in the chamber 1 through the opening 4. The opening of the chamber 4 is closed by the closing device 5, and the opening 3 of the ladle 2 is covered with a lined lid 6 with a burner 7 installed in it. After a safety pause, the burner 7 is ignited. With the help of the thermal energy transferred from the torch 16 of the burner 7, the lining of the ladle is dried. When the lining is heated to a temperature above 450°C, hydrocarbon compounds harmful to the environment begin to be released from the brickwork, i.e. harmful gases are formed, which evaporate from the casing of the ladle 2 through the evaporation holes 18 and 19. The evaporated harmful gases enter the internal space 17 of the chamber 1 and are removed from it through the exhaust unit 8. The harmful gases are sucked from the inlet side 15 into the exhaust pipe 9, connected to the inlet side 10 of the exhaust unit 8, and through the supply pipeline 11, connected to the outlet side 12 of the exhaust unit 8, they enter the burner 7, for example, to the flame torch 16 of the burner 7, for subsequent afterburning inside the steel ladle 2. For a more complete and active afterburning of gases harmful to the environment, additional oxygen is supplied to the internal space of the ladle 2.

Intensive emission of harmful gases from evaporation holes 18, 19 of ladle 2 begins after reaching a temperature of ~700-800°C in the internal space of ladle 2.

Initially, the movable section 14 of the exhaust pipe 9 is installed at the level of the lower belt of the evaporation openings 18 of the bucket 2. As the drying process continues, the movable section 14 of the exhaust pipe 9 is moved to the upper belt of the evaporation openings 19 of the bucket 2 and back to the lower one with a certain frequency specified in the program.

Before the end of the drying process, the movable section 14 of the exhaust pipe 9 is moved to the upper belt of the evaporation openings 19 of the bucket 2 for the effective removal from the internal space 17 of the chamber 1 of the remaining harmful gases that were not captured by the exhaust flow.

After completion of the drying and heating process of ladle 2, burner 7 is switched off and ladle 2 is removed from chamber 1 through opening 4. The next ladle to be dried is placed in the chamber, and the cycle is repeated.

The composite design of the exhaust pipe is universal for buckets of different heights.

In addition, the ability to adjust the suction point (intake) of evaporated harmful gases allows for the most efficient removal of harmful gases from the interior of the chamber and maintaining clean air in the workshop's working area.

The device described in this application has been successfully implemented in the lining department of the EAFC of JSC OEMK im. A.A. Ugarov. The results of the work have been confirmed by instrumental measurements of the air purity of the working area during warranty tests of the equipment, which confirmed the complete absence of harmful substances in the air of the working area of the shop.

List of positions

1 - Camera

2 - Ladle

3 - Opening for filling the ladle with liquid metal

4 - Opening in the chamber for installing the bucket

5 - Closing device for closing the chamber opening

6 - Cover for closing the bucket opening

7 - Burner

8 - Exhaust system

9 - Exhaust pipe

10 - Inlet side

11 - Supply pipeline

12 - Release side

13 - Fixed section of the exhaust pipe

14 - Movable section

15 - Inlet side of the exhaust pipe

16 - Burner torch

17 - Internal space of the chamber

18 - Evaporation holes (lower belt)

19 - Evaporation holes (upper belt).

Claims (1)

A device for drying and heating steel-pouring ladles, comprising a chamber with an opening for installing a ladle with an opening for filling it with liquid metal, a closing device for closing the opening of the chamber, a lid for closing the opening of the ladle, a burner installed in the lid of the ladle, an exhaust unit with an exhaust pipe passing through the chamber on the inlet side for removing gases from the interior of the chamber and a supply pipeline on the outlet side for feeding the removed gases to the burner, characterized in that the exhaust pipe is made composite and has a fixed section and a section movable from the inlet side, wherein the section movable from the inlet side is made with the possibility of telescopic movement relative to the fixed section, wherein the fixed section of the exhaust pipe passes through the chamber, and the movable section of the exhaust pipe is located inside the chamber.

Images