Pursuant to the contract, the specialists of Wellons.RU LLC, together with the construction and installation organization SMU-1, under the leadership of Andrei B. Gaberman, replaced the refractory lining of the top screen of the Wellons boiler from July 17 to July 25, 2017. These works were carried out in full using refractory materials selected and manufactured in accordance with Wellons requirements for the lining operations of the boiler unit. All refractory materials are manufactured in the factory, in accordance with applicable standards (GOST, TU), which guarantees the quality of refractory products and, accordingly, the resistance of the refractory lining of the boiler as a whole.
To carry out work on replacing the lining of the upper screen of the Wellons boiler, company specialists performed calculations for the selection of refractory materials based on a preliminary project to replace the refractory lining of the upper screen of the boiler. In connection with the repeated destruction of the refractory lining of the upper screen, as well as to ensure reliable operation of the lining, it was decided to construct a combined two-layer lining of the upper screen for various zones: a straight section of the upper screen; superheater zone; zones of pipes of the vertical screens of the boiler; Pipe hangers in the upper screen.
In accordance with the specification of materials developed by us, in close cooperation with the refractory materials factory, we manufactured and supplied the following refractory materials:
All materials are checked for integrity of the package, the appearance is checked, the contents of the packages are checked. There are no comments or any deviations from the technical conditions, as well as any visible damage or violation of the integrity of the packaging of materials. All materials delivered to the site are suitable for use in carrying out repairs related to the replacement of the refractory lining of the top screen of the Wellons boiler.
All work related to the device for replacing the lining of the upper screen of the boiler was carried out under the direct supervision of the specialists of Wellons.RU LLC. Refractory installation, as well as the necessary auxiliary work, were carried out by specialists of SMU-1 LLC, who are working on a subcontract as part of our EPC contract with Solikamskbumprom JSC. All main types of work are described below in the relevant sections. They can also be viewed in our brief video report in the section BOILER TOP SCREEN Lining.
The most difficult and critical part of laying the refractory lining of the upper screen of the boiler! Due to the tight interweaving of the pipes of the upper screen, superheater, upper bypass pipes of the collectors of the side screens of the boiler, cramped conditions, laying of molded types of refractory materials (tiles, bricks, etc.) is not possible. In this regard, as the main refractory material of the working layer, BORCAST-55W refractory concrete was used, which has not only a high working temperature of application (up to 1450 ° C), but also high strength up to (500 kgf / cm2), which is an important factor for the selection of refractory material in a given area. Material is supplied in 25 kg bags. in dry form, is two-component, shuts with water. After preparation, concrete is fed into the laying area through service hatches in buckets and through the pipes it is fed to the pre-installed formwork from plywood, it is leveled and rammed manually. The thickness of the concrete layer is 60 mm. Pipes are prewound in a single layer with heat-insulating roll material, to ensure compensatory expansion of various materials (steel, concrete).
In the spaces between the pipes of the inlet and outlet collectors of the superheater and the “U-shaped" part of the superheater, the refractory tile was laid. The presence of "free" space in these areas allowed the use of molded refractory (tile), in compliance with all requirements of the instructions for the installation of refractory lining.
After hardening of the refractory concrete of the working layer, thermal insulation concrete of the brand “BORTHERM-1.0” with a thickness of 60 mm is laid. Material is supplied in 20 kg bags. in dry form, is two-component, shuts with water. Concrete is prepared according to the instructions for each type of concrete. The technology of laying the insulating layer is similar to the construction of the “BORCAST-55W” refractory layer of “heavy” concrete.
ShA brand molded refractory, tile size 460x230x60 mm, was used as a working layer refractory. The tile size (length) is selected so that the tile rests on three pipes. In this case, the probability of failure of the tile between the pipes is minimal. Tiles fit into the dressing. To fasten the tiles together, a masonry mortar / glue prepared on the basis of the mortar MSH-39 is used. The thickness of the joint of the masonry mortar should not exceed 2 mm.
To ensure the necessary density and strength of the refractory structure in the zone of passage of pipes of the side screens, as well as in the area of suspension of pipes of the upper screen, the BORCAST-55W refractory concrete is used as a lining. This concrete is stacked, rammed by hand, in a pre-installed formwork. It is necessary to achieve complete filling of the entire surface of the annular space and the installation of suspensions. The outer formwork is installed with an offset, to form a load-bearing shelf of concrete with overlapping refractory tiles. The width of the concrete strip at the points of attachment of the suspensions is 250-300 mm. The width of concrete along the screen pipes is up to 200 mm. The thickness of the upper layer of concrete (concrete strip) 40-60 mm. All screen pipes, before laying concrete, must be wrapped with a roll of thermal insulation material, to compensate for the thermal expansions of various materials (steel, concrete).
The transition / bending zone of the front screen pipes to the upper screen is formed using two tiles, one of which is installed almost vertically to the front screen wall (in the spacer), the second tile is inclined, repeating the pipe bending. The distance between the tiles of the upper screen and the "rotary" tiles on the inside is covered with plywood, to prevent the leakage of concrete.
The entire space formed by the tiles, the front wall of the boiler, plywood, and the next tile of the upper screen is filled with BORCAST-55W refractory concrete. The upper part of the formwork is installed with an offset to form the supporting shelf of concrete with overlapping tiles (photo below).
After lining of the working layer of the entire surface of the upper screen, including lining of the straight section of tiles, sections of the passage of vertical pipes through the lining, suspensions of the pipes of the upper screen, superheater zone, etc. using the BORCAST-55W refractory concrete, the BORTHERM-1.0 heat-insulating concrete was laid over the entire area of the upper screen. Heat-insulating concrete is laid in sections; the thickness of the heat-insulating layer is ~ 60 mm.
After laying the heat-insulating layer, setting it, the lining works are considered completed. A visual inspection of the laid lining, after a period of natural drying, setting of materials, showed that there were no comments (cracks, leaks, etc.). The material is durable, not prone to punching, cracking, you can walk on the lining without fear.
The design feature of the multilayer lining, the selected and laid refractory materials, the laying technology - all this ensures that the newly laid lining will serve for a long time without additional repairs, subject to the rules of technical operation of the equipment supplier of Wellons, Inc. A short video of the work and a package of photos were handed over to the specialists of the plant.
