RU2164838C1 - Method and apparatus for thermically insulating ladle cover of fibrous material - Google Patents

Abstract

FIELD: metallurgy, namely insulation of working space of ladle. SUBSTANCE: method comprises steps of pricking fibrous material onto cantilever rods arranged in parallel relative to profile line of casing and mounted along concentric circles in staggered fashion; using fibrous material in the form of belt arranged in vertical direction; winding belt layer-by-layer around belt-guiding center. The last is in the form of cylinder or regular polygon with length of its generatrix equal to thickness of heat insulation. Belt is pricked onto rods and it is tightened by means of bandages fit onto each row of rods and tightened to center by means of braces secured to bandage and to casing. Spacing between adjacent rows of rods is equal to (0.5-1)l, where l is rod length. Ends of rods are oriented from center to edges of casing and they are arranged on the same line as leading ends of rods of next row. EFFECT: enhanced strength of heat insulation of ladle cover. 2 cl, 3 dwg, 1 tbl

Description

 The invention relates to metallurgy, and more particularly to the isolation of the bucket’s working space from the environment when it is heated and cast.

 Known designs of lining of ladle covers from refractory products and concrete, similarly, for example, lining of covers of electric furnaces (see M.N. Izhorin, Refractory lining works, Moscow, Vysshaya Shkola, 1990, p. 41).

 The disadvantage of this design of the thermal insulation of the cover is the increased material consumption of the lining.

 For this reason, significant heat losses (due to accumulation and thermal conductivity) during drying, heating and casting of steel from the ladle under the lid are significant. In addition to the above, the increased material consumption of the lid leads to increased laboriousness of repair work and the use of mechanisms of increased power for its movement.

 These drawbacks are absent when using fibrous materials as thermal insulation (see ibid., Pp. 214-218). As the closest technical solution — an example of the use of fibrous material for insulating lids — a method of isolating the dome of a bell furnace with fibrous materials has been adopted (see A. Lukashevich, Refractory Works, Moscow, Stroyizdat, 1979, pp. 147-148).

A known method for isolating flat surfaces involves attaching studs (pins) to the furnace casing, perpendicular to the casing surface, pricking a layer of fibrous material on the pins and then securing said layer with washers screwed onto the ends of the pins protruding into the insulated space. The disadvantage of this method of insulation of the casing of the cover with fibrous materials is:
- the impossibility of its use for insulation of curved surfaces (since when piercing the insulation layer on the pins in a known manner, the heat-insulating layer does not fit with the curved surface);
- the impossibility of applying the method for rotary lids of ladles, since the insulation is not secured when the lid is rotated;
- limited application of the method due to the insufficient durability of the metal elements (ends, pins, washers) located during operation in the high temperature zone;
- limited application of the method due to heat loss by thermal conductivity through metal pins, one end located in the high temperature zone, the other end mounted on a casing in the atmosphere.

 As the closest technical solution - an example - a device for thermal insulation of fibrous material adopted GOST 17314-81, a device for fixing the thermal insulation of steel vessels and apparatuses. According to hell. 17 and damn. 3 appendices 2 of the specified GOST, the device’s thermal insulation device with fibrous materials includes cantilever pins of length l attached to the casing, perpendicular to its surface (onto which a layer of thermal insulation is impaled), as well as bandages (or rings) and couplers attached to the pins along the insulation surface .

 The specified known device for insulation of the casing with fibrous materials has all the disadvantages noted in the analysis of the known method.

 Moreover, this insulation is not durable, since the main elements of its fastening (bandages, ties, ends of the pins) are during operation of the lid of the bucket in the high temperature zone and quickly fail.

 The technical result of the invention is to increase the stability of thermal insulation of the lids of ladles made of fibrous materials.

 The specified technical result is achieved in that the thermal insulation of the lid of the bucket is made of fibrous material, including the fastening of the pins to the casing of the lid and the pricking of the fibrous material on the pins, by attaching the pins to the casing in concentric rows. At the same time, the fibrous material is used in the form of a tape, which is mounted vertically during installation, by layerwise winding around the tape guide center, pinning it sequentially on concentric rows of pins, and thermal insulation layers made in this way are periodically tightened with bandages.

 When fastening the pins to the casing in concentric rows (turned towards the edges of the cover) and pricking the insulation on them in the form of a tape located vertically around the tape guide center, it turns out that the pins are recessed in the thickness of the insulation, and therefore not subject to the high temperature of the worker bucket volume. The indicated service conditions for fastening reinforcement operating at moderate temperature increase the durability of the thermal insulation (having higher heat resistance than fastening reinforcement).

 When piercing the insulation on the pins and periodically tightening the impaled layer with bandages, heat insulation is formed, turning its end surfaces of the layers into the working volume of the bucket.

 In this case, due to friction between its constricted layers, local collapse of its individual layers is excluded and the resistance of the entire insulation as a whole increases.

 When performing thermal insulation in this way, the device (thermal insulation design) must have the appropriate features that provide the specified technical result, that is, the thermal insulation resistance.

 The specified technical result is achieved in that the fiber insulation design comprising cantilever pins, braces and couplers is additionally equipped with a tape guide center in the form of a cylinder or a regular polyhedron, the length of which is equal to the thickness of the insulation. The pins in the claimed design of thermal insulation are installed parallel to the profile line of the casing and fixed around the tape guide center in concentric rows in a checkerboard pattern. The distance between adjacent rows of pins is maintained equal to 0.5 - 1 l, where l is the length of the pin, the ends of the pins are directed from the center to the edges of the casing and are in line with the beginning of the pins of the next row. The tightening bandages are carried on by each row of pins and ties tightened to the center, attached to the bandage and casing.

 Thus, to increase the insulation resistance, the insulation device is characterized by the following features.

- in the center of the lid there is a tape guide center, in the form of a cylinder or a polyhedron, with a generatrix length equal to the width of the tape. The specified center, when wrapping around it a tape of fibrous material, stacks the tape layers vertically, setting the specified location of the tape to subsequent layers. The thermal insulation formed in this way is turned by the end surfaces of the layers into the working volume of the bucket, and these thermal insulation layers protect each other from temperature influence, increasing its resistance;
- the pins are attached to the center and the casing parallel to the casing profile and are deployed from the center to the edges.

 The specified location of the pins when the tape is pierced on them provides a reliable suspension of thermal insulation on the entire surface of the cover casing, regardless of its profile.

The pins are taken with the console length equal to l = 30-60 of the pin diameters, as practice shows, which do not undergo deformation and preserve the thermal insulation profile during operation of the device;
- the pins are placed in rows (relative to the center of the lid), in a checkerboard pattern, with the ends of the pins of the previous row in line with the beginning of the pins of the next row. The specified location of the pins provides uniform mounting of the insulation over the entire surface of the cover without injuring it, without interfering with the tape sticking onto the pins (when making the insulating layer), that is, bypassing encountered obstacle rods on the casing;
- rows of pins placed in increments of 0.5 - 1 l. As practice shows, with the specified length of the pin, it does not deform during operation, (lower values are impractical due to an increase in the number of pins and an increase in the complexity of work on the isolation device);
- the bandage is worn on a concentric row of pins and, when tightened, compresses the insulation layer located on the indicated row, increasing its resistance. Thus, it turns out that on each row of rods there is a bandage that provides fixation of the compressed insulation layer during operation;
- each band is drawn to the center and the casing with ties, due to the fastening of the ends to the band and casing, closer to the center.

 The specified insulation fastening provides reliable insulation fastening during operation and turning the cover. At the same time, the fastening elements of the insulation are located inside its layer (that is, separated from the high temperature zone by a thermal insulation layer), which ensures higher durability than the prototype.

 In FIG. 1 shows a general view of a cover with isolation in isometry, with sections along the main axes.

 In FIG. 2 shows a top view of the fastening elements of the lid insulation, FIG. 3 shows a fragment of a vertically arranged section of the lid on an enlarged scale.

 The lid 1 of the bucket has a casing 2 and thermal insulation 3 located around the tape guide center 4.

 Pins 5 are attached to the casing 2, having a cantilever 6 with the length indicated by the symbol "l" and a shaft 7 for attaching the pin 5 to the casing 2. The diameter of the pin 5 is indicated by the symbol "d".

 The pins 5 are located around the tape guide center in 4 rows, along the lines of 8 rows, in a checkerboard pattern of the location of the pins 5 of the previous row relative to the next, with the ends of the 9 pins 5 of the previous row and the beginning (rods 7) of the pins 5 of the next row on the indicated lines of 8 rows. The distance between the rows of pins is indicated by the symbol "Z" and is 0.5 - 1 l.

 The ends of 9 pins 5 are deployed from the guide center 4 to the edges 10 of the cover 1.

 Around the tape guide center 4, a tape 11 of heat-insulating material having a width S equal to the thickness of the insulation 3 is laid. The tape guide 4 is made in the form of a cylinder 12 (or a regular polyhedron) having a generatrix 13 of length S.

 The tape 11 of the heat-insulating material is impaled on the pins 5 and touches its upper edge 14 of the casing 2 of the cover 1.

 A bandage 15 is put on each row of pins 5, which is drawn to the center of the lid 1 by ties 16 attached to the bandages 15 and to the casing 2 of the lid 1.

The insulation 3 cover 1 is as follows:
- attach 2 pins 5 to the casing.

 The pins 5 should have a cantilever 6 size of not more than 60 times the diameter of the rod 7, since with the indicated cantilever value 6, a significant limb of the pin 5 is not observed during operation.

 The minimum size of the console (less than 30 diameters of the shaft 7) is not advisable due to the unjustified increase in the number of pins 5 for fastening the insulation 3 and increase, in connection with this, the complexity of the work on the manufacture and installation of pins 5.

 When mounting the pins 3, their consoles 6 are placed parallel to the profile line of the casing 2 of the cover 1, placing the pins 3 in concentric rows along lines 8 in a checkerboard pattern, with the ends 9 deployed from the tape guide center 4 to the edges 10 of the cover 1. The distance Z between the rows of pins is made in within 0.5-1 l of the length of the console 6 of the pin 5 (for the reasons mentioned above when analyzing the length of the console 6 of the pin 5).

 To perform thermal insulation 3, a tape 11 of fibrous material with a width S equal to the thickness of insulation 3 is used. When mounting the tape 11, it is placed vertically and the tape-forming center 4 is wrapped with tape 11, pricking its web on the pins 5 and touching the upper edge 10 of the tape 11 of the cover casing 2 of the cover 2 1. With multiple winding of the tape 11, a layer of thermal insulation 3 of thickness S is obtained, parallel to the casing 2 of the cover 1.

 The tape guide center 4 is made in the form of a cylinder 12 (or a regular polyhedron) with a generatrix 13 equal to the width of the tape 11. When winding (or laying) the tape 11 in a vertical position around a vertical cylinder 12 (or a polyhedron), the tape 11 is laid by a vertical ring (polyhedron) and further serves as a guide for laying subsequent layers of tape 11. When laying tape 11, it is put on the pins 5 and pressed to the center of the cover 1. Moreover, the subsequent rows do not interfere with the winding of the tape 11, since the pins 5 of the rows are offset from each other ( staggered) and this makes it possible to prick the tape 11 on the pins 5 of the previous series, rounding rods 7 fixed to the casing subsequent series.

 When laying the tape 11, it is usually drawn completely onto the pins 5 of the next row, and then pressed by the bandage 15, moving the insulation layer over the pins 5 to a size approximately equal to half of the console 6 of the pin 5. Then the bandage is fixed with ties 16 attached to one side of the bandage, the other to the casing 2, closer to the center of the cover 1. In this case, the tension of the tie 16 attracts the bandage both to the center of the cover 1 and to the casing 2 (preventing the sagging of the pins 5 due to the weight of the insulation 3).

 When tightening the insulation with 3 bandages 15, the elements of the tape 11 moving to the center can be cut by the rods 7 encountered on their way. But at the same time, from the sides, the tape 11, at the same time, pins on the ends 9 of the staggered pins 5. Thus, it turns out that everything the elements of the tape 11 are evenly impaled on the pins 5 over the entire surface of the casing 2 of the cover 1, and are drawn to the center.

 The thermal insulation 3 of the cover 1 made in this way has a longer service life than the known insulation with fibrous materials, since all the fastening elements of the specified insulation 3 are separated from the high temperature zone under the thermal insulation layer and operate under relatively more moderate temperature conditions than the known insulation.

 The results of the operation of the ladle covers with concrete and the proposed thermal insulation are presented in the table.

 In accordance with the table, the use of fibrous insulation reduces heat loss due to accumulation and thermal conductivity (by reducing the insulation mass by 8 times and thermal conductivity by 6 times).

 Accordingly, fuel consumption decreases, the heating temperature rises, the laboriousness of the work to restore insulation during repairs decreases, the insulation resistance increases.

Claims (2)

 1. The method of thermal insulation of the bucket lid made of fibrous material, including attaching the pins to the cover of the lid and pricking the fibrous material on the pins, characterized in that the pins are attached to the casing in concentric rows, the fibrous material is used in the form of a tape that is placed vertically and is wound in layers around the tape guide center, while the tape is sequentially pierced on the concentric rows of pins and periodically tighten the made annular layers of thermal insulation with bandages.  2. The device for thermal insulation of the casing of the bucket lid, containing cantilever pins, braces and couplers, characterized in that it is equipped with a tape guide center in the form of a cylinder or a regular polyhedron, the generatrix of which is equal to the thickness of the insulation, the pins are installed parallel to the profile line of the casing and are fixed around the tape guide center by concentric in rows in a checkerboard pattern, while the distance between adjacent rows of pins is 0.5 - 1l, where l is the length of the pin, the ends of the pins are directed from the center to the edges of the casing and p found on the rear on the same line with the beginning of the subsequent number of pins, and wore bandages on each row of pins and tightened ties to the center, attached to the shroud and shroud.

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