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Application of graphite in the field of anti-corrosion
- 2019-12-05-

Abstract: At present, the main applications of graphite equipment are: graphite heat exchanger, graphite condenser, steel-lined graphite reactor, steel-lined graphite reaction tank, concentration tank, reaction tower, packed tower, phosphoric acid extraction tank, granulation tower and other high-temperature reactions Anti-corrosion lining of equipment, heat transfer equipment, condensing equipment and anti-corrosion equipment.
Keywords: graphite: anticorrosion: heat exchanger: synthesis furnace
1 Overview
Graphite is a typical brittle material, it has good corrosion resistance and thermal conductivity; small linear coefficient, good temperature resistance; good mechanical processing performance; wear resistance, light weight, temperature rise but strength does not decrease. The surface of the pressed graphite element is not easy to scale, which can ensure the purity of the product. The disadvantages are low mechanical strength, small elastic deformation, very brittle performance, poor impact resistance, and low tensile strength. Graphite equipment is basically thick-walled equipment. Generally, there is no instability failure before the material's compressive strength reaches the limit, and it is generally the strength of the cylinder. Graphite equipment is mostly used in normal pressure and low pressure operating conditions, and the use temperature is not too high. The design pressure of graphite equipment is not more than 2.4 MPa, and the design temperature is -60~400℃. Graphite equipment materials are generally impregnated impermeable graphite. Graphite materials are mostly usedGraphite heat exchanger, Towers, filters, reactors, graphite absorbers and other equipment. In the design of graphite equipment, the compressive strength characteristics of graphite materials should be used as much as possible, so that the graphite components are under compressive stress, avoiding or reducing tensile stress and bending stress. The direction of the heat exchanger channel must conform to the better heat conduction direction brought about by graphite anisotropy. As a heating device, the adhesive structure should be minimized when resin-impregnated graphite, pressed graphite and its cement are used in combination with metal materials or other materials. The main graphite parts of the equipment should be avoided as far as possible to use adhesive structures
2. The application of graphite in the field of anti-corrosion
Impermeable graphite adopts certain measures to fill the gaps of graphite to make it an impermeable graphite material. Including impregnated graphite, pressed graphite and cast graphite. With excellent corrosion resistance and physical and mechanical properties, it can be widely used in the chemical industry to manufacture anti-corrosion equipment. The performance of graphite anti-corrosion equipment is as follows: 1. Excellent corrosion resistance: various types of carbon and graphite have excellent corrosion resistance to all concentrations of hydrochloric acid, phosphoric acid and hydrofluoric acid, including fluorine-containing media, and the highest application temperature is 350 ℃-400℃ is the temperature at which carbon and graphite start to oxidize. 2. Resistant to a certain high temperature: The use temperature of impermeable graphite depends on the type of impregnating material. For example, phenolic impregnated graphite can withstand 170-200℃. If you add an appropriate amount of silicone resin impregnated graphite, it can withstand 350℃; When deposited on carbon and graphite, the oxidation resistance of carbon and graphite can be improved, and the actual operating temperature can be further increased [5]. 3. Excellent thermal conductivity: it is a non-metallic material with higher thermal conductivity than metal, ranking first among non-metallic materials. The thermal conductivity is 2 times that of carbon steel and 7 times that of stainless steel. Therefore, it is suitable for use in heat transfer equipment. 4. The surface is not easy to structure: the "affinity" between graphite and most media is very small, so dirt is not easy to adhere to the surface. Especially suitable for graphite condenser equipment and crystallization equipment