Class II capital repairs to furnace No. i in November, 1982 showed that nearly 5 yrs of use of the slag-thinning materials had not significantly affected the condition of the lining of the shaft, which can evidently be attributed to maintenance of the melting point of the slags at the optimum level (1250-1350~

CLASS II CAPITAL REPAIRS TO BLAST FURNACE NO. 2 AT THE ORSK-KHALILOVO

METALLURGICAL COMBINE

Yu. V. Vasilenko UDC 669.162.16.2:66.042.2

Blast furnace No. 2 at the Orsk-Khalilovo Metallurgical Combine underwent class II capital repairs from November 14 to December 15, 1982. The planned duration of the repair according to the Minchermet SSSR (ministry of Ferrous Metallurgy of the USSR) schedule was 25 days, while the actual duration was 22 days.

The furnace, built in August, 1958, has a useful volume of 1033 m 3. The furnace is char- acterized by the following dimensions: hearth diameter 7700 ram, hearth height 3200 ram, diam- eter of boshes 7200/8200 mm, height of boshes 3000 mm, diameter of belt 8200 mm, height of belt 2000 ram, diameter of the inwall 6000/8200 ram, height of the inwall 1500 ram, diameter and height of the top 6000 and 2300 ram, respectively. The useful height of the furnace is 26,600 mm. The furnace has 14 tuyeres, one slag notch, seven mantle columns, and six shaft columns. The furnace is water-cooled.

In accordance with the defect list, the overhaul plan called for replacement of the lin- ing of the hearth, lining, and protecting plates, the shaft itself, the top cone, the top ring, the bosh and inwall (stack) coolers, the cone liner plates, the top protecting plates, and the cooling bands of the boshes and stack. The plan also called for replacement of the charging apparatus and inspection or replacement of the mechanical equipment in the cast house, the stove building, dust catcher, the motor room, and the stockhouse.

Most of the work was to be done by the Novotroitsk SSMU of the "Uraldomnaremont ~' trust in collaboration with the repair shops at the combine. To ensure that the repairs were made in the times prescribed by the Minchermet, the following preparatory tasks were completed be- fore the furnace was shut down: l) development of a plan of labor organization~:for each day (24-h period); 2) disposition of mechanisms and equipment in accordance with the plan; 3) in- stallation of a dragline hoist in the tuyere zone to remove pieces of the stack and brick debris; 4) installation of three vertical two-belt hoists to deliver refractories to the fur- nace stack and top; 5) installation of a scaffold bridge to deliver refractories; 6) pressure testing of the stack coolers and their arrangement in rows; 7) checking of all hoists, weld- ing equipment, and the cement mixer; 8) installation and testing of a phone system; 9) in- stallation of metal structures to tap the molten upper "salamander"; I0) installation of powerful lamps to fully illuminate the furnace. The following components were assembled under close supervision : charging apparatus and revolving dis tributor, top protecting plates, the stack part of the furnace shell, and all annular monorails.

f Protective shelter Furnace axi~ - - ~ =

F

Fig. i. Container for installing the belts of the suspended plat- forms: i) roll-out sections; 2) roller; 3) belts for the platforms (three); 4) hinges; 5) central section.

Novotroitsk SSMU of the "Uraldomnaremont" Trust. Translated from Metallurg, No. I0, pp. 21-23, October, 1983.

0026-0894/83/0910-0325507.50 �9 1984 Plenum Publishing Corporation 325

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Fig. 2 Fig. 3 Fig. 4

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Fig. 2. Attachment of top protecting plates to shell: i) stop; 2) lining; 3) wedge; 4) bracket.

Fig. 3. Scheme of replacement of the cooled part of the shell: i) panel P-l; 2) panels P-2 and P-3; 4) panels P-4 and P-5; 4) panel P-6.

Fig. 4. Stack coolers of blast furnace No. 2: i) spiral tube; 2) cooler; 3) fur- nace stack; 4) outlet of spiral tube; 5) flange; 6) bolt with nut.

The following components were assembled into unitized elements during the preparatory period: the suspended platforms (one element consisting of two platforms, and one element of three platforms); the belts for the platforms (Fig. 1- the belts were placed in a special container); the charging apparatus and revolving distributor; the protective shelter with the annular monorails; the furnace shell.

The stack portion of the shell was made of three belts. The cooled part of the shell (the first belt) consisted of six panels. Holes for the pipes and bolts of the stack coolers were drilled in the cooled portion during the preparatory period. The uncooled part of the shell (the second belt) also consisted of six panels, with an allowance of 300 mm at the top of the panels.

The third belt (the zone of the top protecting plates, the top cone, and the top ring) was assembled into one element, with the top ring being installed exactly horizontal and welded about its circumference. The brackets for the protecting plates were also installed and secured in this element in the preparatory period (Fig. 2).

After being cleaned of dust and debris, the furnace was given over to the repair crews. Disassembly work was done at three different levels: at the top, in the stack, and in the hearth. At the first level, the fact that the furnace was equipped with a construction girder on the dust catcher was used to dismantle the receiving hopper and charging apparatus as a unit over the course of two shifts. An 8500-mm-diam. hole was then cut into the top platform and the underlying supports were dismantled. At the same time, on the second level we rein- forced the stack columns and cut the cooling bands. We then blew out the bolts fastening the coolers and the spiral tubes.

At the third level (the hearth), we prepared the tuyere openings (for a pair of tuyeres) and set up the 100-kW dragline hoist" to remove the remains of the stack, brick pieces, and debris. During the same period, we began to reinforce the mantle ring by installing plate brackets underneath it. The operation took 4 days. During this period, we dismantled the top-cone panels and lowered a suspended platform into the furnace on a central pulley. It was discovered after the charging apparatus was removed that there were 2.5 courses of the top lining left. This lining was cut into pieces from the suspended platform and thrown into the furnace. The refractory lining of the stack was also almost all gone, except for a small crust in the belt zone.

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The stack coolers were dismantled from the outside of the furnace with jacks, so this work was done outside of the main flow of repair tasks and could be completed simultaneously with the dismantling of the top-cone panels and top lining. Immediately after disassembly of the lining, the suspended platform was lowered by the pulley from the top zone into the stack region and was used to help dismantle the mantle and bosh coolers. After this, the platform was returned to the top.

The collapsible shelter was lifted to the top by the main hoist. The shelter was then constructed over two lateral pulleys and lowered into the stack. There it was opened by means of stays and positioned at the level of the fourth row of coolers. Electric compound pulleys fastened earlier under the shelter were used to install the new bosh coolers. The shelter was then lowered to the bosh and work was begun in the hearth.

The shell in the shaft region was dismantled in three parts: the top cone with part of the adjacent shell and the top ring, a midsection ii m high, and the bottom 6 m.

The top cone and top ring were dismantled as one element in a single shift using the main hoist. The furnace shaft was cut with high-productivity gas cutters. The middle part of the shaft was dismantled in six panels (two at one time). The lower part was disassembled "indirectly," parallel with the installation of the new panels and welding of the horizontal joints. The scheme of replacement of the cooled part of the shell is shown in Fig. 3.

After the bottom part was installed, the tops of the panels were surveyed and cut ex- actly horizontal. The tops were then fastened to the stack columns with bolts. Movement of the vertical axis was checked with a plumb lowered into the center of the furnace from: balancers extended out on the shelter. The middle section, 7 m high~ was also installed with the main hoist two panels at a time. After the middle section was completed, the allowance at the top of the panels was trimmed with the aid of a level, which made it possible to in- stall the rest of the shaft with the top cone and top ring as one element with a horizontal deviation of -+0.5 ram.

The vertical joints were welded by electroslag welding, while the horizontal joints were closed by manual electric-arc welding. The shell was completely replaced and welded in 7 days. The belts were then installed in the shaft in the container and the suspended platforms were lowered on and hung from the belts. Rack-type pushers for clamping the coolers were mounted on the lowest platform. Work proceeded in the shaft at two levels: The coolers were installed at the first level, and the top protecting plates were installed at the second level. Lining was done simultaneously. During the same period, the gas offtakes were installed at the top, and then the top platform was erected. Up to this moment, in the hearth workers had finished dismantling operations, installed panels in the tuyere opening, installed six new tuyere coolers, and completed lining of the hearth.

Slab coolers of a new type were used in furnace No. 2. The coolers had a single pipe outlet located in one component for all of the spiral pipes, and they had one bolt for fasten- ing the cooler to the furnace shell (Fig. 4). Altogether, the plan called for the installation of seven rows of stack cooling slabs (the fourth and seventh rows were arranged in the form of boots).

A self-propelled cart was sent through a (1200 x 1300)-ram hole into the furnace shaft to deliver the coolers. Tl~e coolers were then installed by means of electric telphers and the rack-type pushers. Installation of the shaft coolers took 4.5 shifts, and 216 slab coolers in all were installed. Here it should be noted that as many as 58 coolers were installed in one shift, thanks to accurate marking, good cooler design, and the trouble-free continuous operation of the mechanisms. Fluting and beading of the coolers was done simultaneously with their installation. After the coolers were installed, the suspended platforms for install- ing the lining were hung and set up. The coolers were caulked by guniting from these plat- forms.

The shaft was lined one course at a time from the mantle. The bricks were delivered by three vertical two-belt hoists. The mortar for filling the gaps between the lining and cool- ers was delivered along a cable to the inspection platform and then along a pipe and hoses to the site of use. The top cone was also lined with refractory brick during this period. Af- ter the lining operations were completed, the charging apparatus was installed as one element (weight of the element 120 tons).

After the suspended platforms were cleaned and disassembled, we made and closed the ac- cess holes. Charging of the furnace was begun after the charging apparatus was centered and

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Access hole ~200X'~

Fig. 5. Self-propelled cart for de- livering coolers into furnace: i) frame of cart; 2) cart; 3) shaft cooler.

connected to its power source. This completed all mechanical-construction work and pipe laying called for in accordance with the defect list. The equipment in the dust catcher, stove building, motor room, and stockhouse was checked and, when necessary, replaced.

The early completion of the class II overhaul of blast furnace No. 2 was helped by the increase in labor productivity that resulted from careful organization of tasks among all re- pair personnel, the scientific organization of these tasks, the organization of socialist com- petition, the introduction of new repair technology and the timely completion of different tasks, the use of small-scale mechanization, quality control of repair work, the use of a piecework-bonus pay system, and the timely and uninterrupted supply of materials and equip- ment.

The organization of socialist competition during the repair was of primary importance. An operational headquarters was established for the competition, and one of the tasks of the headquarters was the posting of complete results of the competition on a special stand as it proceeded. Satirical leaflets and bulletins were regularly issued, and the Komsomol spot- lighted various aspects of the competition. Summaries of the work of each crew were reported daily, and first prizes were awarded. The progress of the repair was detailed regularly in the town newspaper and the plant paper.

Much attention was also given to questions regarding safe working techniques and repair methods. To check for safety during the repair, a 24-h detail of engineers assigned to cheek working conditions was organized. All of these measures helped to complete the repair work ahead of schedule without serious accidents.

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