Results are provided for determination of the abrasion resistance of refractory concretes of different composition according to the standard ASTM C-704. Principles are considered for constructing abrasion-resistant linings in order to protect heating units in various branches of industry.Refractory lining of heating units in different branches of industry is subject to abrasive wear. The problem of protecting equipment from the action of high temperature and simultaneously abrasive wear of moving dust, granular, and lump materials exists in ferrous and non-ferrous metallurgy (the blast furnace process, coke-oven batteries, various roasting and melting furnaces, etc.), in the cement industry, in power engineering using solid fuel, in the oil processing, petrochemical, and chemical industries (in various catalytic processes), in rubbish incineration units, etc.OOO Aliter-Aksi specializes in preparing refractory concretes that exhibit high abrasion resistance using about 50 designated raw materials, producing about ten thousand tons per year of refractory concrete mixtures and articles (Al 2 O 3 up to 99%) with a very broad range of properties: application temperature up to 1800°C, apparent density from 0.4 to 3.1 g/cm 3 , ultimate strength in compression up to 250 MPa. During the last thirty years rRefractory concretes have actively crowded out traditionally formed refractories in different branches of industry. On the whole in developed countries the volume of production of formed and unformed refractories is approximately the same; in some branches concretes are used more than formed articles. The advantages of concrete linings compared with those made of individual items are well known: the technological efficiency of laying and assembly, absence of numerous joints, low labor expenditure in laying, and the repair capacity of linings. However, there are factors holding back the spread of concrete linings: the necessity of maintaining a positive temperature during preparation of the concrete and performing lining work, use of additional equipment (mixers, torcrete guns, vibrators, pneumatic rams, etc.), use in the work of qualified personnel, higher requirements for drying and the first firing of the lining.Presented in Table 1 and in Fig. 1 are the properties of abrasion-resistant concretes produced by OOO Aliter-Aksi. The abrasion resistance was determined according to the standard ASTM C-704 in the research center of the firm Causeway Steel Products Ltd (Great Britain) according to the volume of the crater formed during action on a specimen of a jet of silicon carbide powder. The smaller the crater volume, the higher the concrete abrasion resistance. Abrasion resistance less than 12 cm 3 is assumed to be very high, and less than 6 cm 3 it is assumed to be extremely high.Abrasion-resistant concretes produced by OOO AliterAksi may be broken down into three main groups:· ALKOR is a mixture of dense aluminosilicate fillers (from fireclay to corundum) with alumina or high-alumina cement. The cement content is more t...
No abstract
Advantages of concrete over brick linings are indicated. The following furnace descriptions are given: high-temperature furnaces fired by natural gas or fuel oil, furnaces in Claus plants, and furnaces with after-burning of acid gases and an abrasive effect on the lining.High-temperature furnaces designed for the heating and/or burning of gaseous, liquid, and solid products have come into widespread use in various branches of industry. To protect against high temperatures and chemical, mechanical, and other effects, the metallic housing of the furnace is fitted with a refractory lining. In the past, refractory bricks were used as the primary material for fabrication of the lining. At the present time, monolithic furnace linings are being used all the more frequently owing to rapid development of the technology of refractory-concrete production.Let us examine the feasibility of using refractory concretes for furnace linings in the oil-refining and petrochemical industry.Basic advantages of concrete over brick linings are as follows:• use of bricks, including the molded and feather-edge bricks that satisfy rigid size and curvature requirements and are rather scarce at the present time, is precluded; no operations involving the cutting and grinding of bricks are required; • use of ceramic and metallic anchors in the inner layer of the furnace permits the application of fibrous thermal-insulating materials and lightweight concretes with a density of 0.5-1.5 g/cm 3 ; this lightens the lining and elevates its thermal-insulating properties; • when in service, a concrete lining, despite the formation of cracks, will retain its geometry, but, in the case where brick is used with insufficiently high-quality masonry, sagging or caving of the lining (especially in large-diameter furnaces) is possible as a result of caking of mortar and local damages to the lining; • a concrete lining will have considerably higher gas tightness; a tight fit between the concrete and metallic housing makes it possible to eliminate the circulation of hot gases, which cause overheating and blow holes; this is critical when a pressure gradient exists within the furnace (for example, in zones of reduced width); • local repair of the concrete lining is appreciably simpler; and • the selection of refractory concretes is now much broader today than feathered-edge articles (bricks); under the operating conditions of a specific furnace, it is therefore possible to select concretes that possess higher resistance. Use of concretes is particularly expedient for the fabrication of new furnaces. In that case, the lined furnace can be fabricated on a turn-key basis for a specialized establishment. The inner layers of fibrous insulating materials and lightweight concretes are applied in sectors as the metallic housing is rotated in the horizontal position. The effective layer is poured into a form with the housing in the vertical position. A furnace fabricated in accordance with this procedure can be transported over long distances.
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