Two-Strand Tundish with Chambers for Plasma Heating of Liquid Metal

Abstract

An improved design of tundish which has chambers for the plasma heating of liquid steel has been developed and tested. The design of the tundish improves heat and mass transfer processes inside it. The new design elements of the tundish accelerate the entry of the metal into zone occupied by the hightemperature plasma in order to improve the conditions for its heating and making the metal's temperature uniform throughout the volume of the tundish. Two tundishes of the new design were made and the plasma heating unit was factory-tested during the casting of steel on continuous caster No. 4 in the oxygen converter shop at the Magnitogorsk Metallurgical Combine. Keywords: continuous casting of steel, tundish, chamber for plasma heating of metal, intake compartment, teeming compartment, transfer channels, deflector, distribution of steel temperature in the heating chamber, mixing of the steel.The changes which have been to the technologies used for the continuous casting of steel have also changed the role of the tundish in this process as a device that distributes molten steel to the molds of the caster. A range of techniques is used to improve the quality of the resulting cast steel. The experience accumulated thus far shows that use of the simplest design of tundish can no longer satisfy the increasingly demanding requirements on the quality of continuous-cast semifinished products. The tundish should be designed so as to protect the molten steel from such sources of contamination as erosion of the refractories, repeat oxidation, and reaction with the ladle slag. At the same time, the tundish design should also provide for the coagulation, surfacing, and removal of nonmetallic inclusions through proper organization of the steel's movement and the elimination stagnation zones and truncated flow paths. Finally, the tundish should be designed so as to allow the use of complementary techniques such as inert-gas injection, the use of special covers and covering fluxes, the installation of sills and filters, control of the temperature of the steel, and the steel's deoxidation and microalloying [1-9]. On modern continuous casters, the steel is poured into the tundish through a protective tube injected with inert gas. To decrease the amount of interaction between the metal and air and to provide the tundish with thermal insulation, it is equipped with a cover and fluxes are added to the surface of the melt. The fluxes form slags of moderate basicity that can absorb deoxidation products and effectively prevent saturation of the steel by gases. It is recommended that the lining of the tundish be made of refractories having high contents of CaO, MgO, Al 2 O 3 , and ZrO 2 . The following measures help actively remove NIs from the steel: proper selection of the angle of inclination of the walls of the tundish and the positions of the partitions in the tundish; injection

Application of Graphite Electrode Plasma Heating Technology in Continuous Casting

“…Low temperature and constant temperature can stabilize the parameters such as superheat and casting speed, simplify the operation of the pouring process, and prevent steel leakage during continuous casting. Furthermore, the low superheat can refine grains, increase the proportion of equiaxed grains [ 7 , 8 ], and reduce the central segregation of the continuous casting slab [ 9 , 10 , 11 , 12 , 13 ].…”

“…Due to the characteristics of plasma, such as energy concentration, high temperature, easy control, fast heating response, and not introducing pollution to molten steel, plasma tundish heating (PTH) has attracted extensive attention in the 1980s and 1990s, and single or twin water-cooled metallic torch plasma heating equipment was developed. However, due to the short service life of electrodes, low heating efficiency, high operation cost, and heavy bottom electrode installed on tundish, plasma heating tundish technology has not been widely used [ 10 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. In addition, the tundish induction heating equipment has a large volume, and the tundish capacity is 20%.…”

Molten Steel Flow, Heat Transfer and Inclusion Distribution in a Single-Strand Continuous Casting Tundish with Induction Heating

“…Particularly, electromagnetic metallurgical technology [10][11][12] utilizes the force or heat effect of the electromagnetic field or simultaneously uses the force and heat effect [13][14][15] to control molten metal flow, heat transfer and inclusion migration in the metallurgical process [16,17]. Plasma heating [18] and induction heating (IH) [19] are the leading heating methods in the process of heating molten steel in the continuous-casting tundish [20,21]. A channel-type IH tundish is developed by utilizing the thermal and force effects of electromagnetic fields [22][23][24].…”

Influence of Plasma Heating on the Metallurgical Effects of a Continuous Casting Tundish

“…The working gas (argon) is flushed from the hollow part of the electrode and ionized into plasma under the action of an electromagnetic field, forming arc plasma, which converts electric energy into heat energy and dynamically heats the molten steel. At present, the ability of plasma to heat molten steel in tundishes has been generally accepted [10][11][12][13], and numerous scholars [14][15][16][17] have carried out simulation research on the plasma heating process. Barron-Meza et al [18] studied the influence of the plasma heating position and flow control device on the flow and heat transfer of molten steel in a tundish by means of physical simulation and numerical simulation.…”