5.3　Process Equipment

5.3.1　The series of converter volumes shall include 30t，50t，80t，100t，120t，150t，180t，200t，250t，300t and 350t.A new converter steelmaking shop shall be provided with the furnace volume specified in the series and also the volume selected shall not be less than 120t.

5.3.2　For a new furnace lining，the volume ratio shall be 0.9m3/t-1.0m3/t.The aspect ratio of vessel shall be 1.30-1.60.

5.3.3　The furnace vessel shall be equipped with symmetric furnace nose，cylindrical vessel body and cylindrical-spherical or taper-spherical bottom.New converter shall adopt integral shell.The shell and trunnion ring may be transported by sections and assembled and welded on site.After heat treatment，the assembly welds are subject to ultrasonic flaw detection and magnetic powder inspection.The coaxiality tolerance of the trunnion for converter with volume of＞120t shall not be more than φ1.5mm and that for converter with volume of≤120t shall not be more than φ1mm.

5.3.4　The converter with volume of less than 150t should adopt simple top repair mode in maintenance.The converter with volume of not less than 150t should adopt the mechanical top repair mode with furnace repair tower.

5.3.5　Converter should be equipped with water-cooled furnace mouth and water-cooled furnace nose.The furnace bottom and trunnoin shall be designed based on combined blowing process.The trunnion ring should be water cooled or air cooled.The gap between trunnion ring and vessel shell should be 100mm-250mm，which shall be determined based on the connecting form between trunnion ring and furnace body，the vertical position of trunnion ring relative to furnace body，furnace body cooling method and other conditions.

5.3.6　The connection between the vessel shell and trunnion ring should adopt suspended bottom connection，or top mounted connection may be adopted.The seat of trunnion may be a bearing seat with a movable or swinging end.

5.3.7　The converter shall be equipped with a fully-suspended tilting mechanism.The balance mechanism should be torsion bar type.The tilting should be controlled with AC variable frequency technology and driven by 4 motors independently.The rotating speed shall be 0.1r/min-1.5r/min.The furnace body can be rotated continuously by±360° and can be tilted steadily and stopped accurately at any angle.In case of hearth freezing or collapse fault the 4 motors can work at the same time and the converter can be tilted at a low speed.In case of failure of one motor，the converter can be tilted at a medium speed and then the one-day operation can be completed.In case of failure of 2 motors，the converter can be tilted at a low speed and then the operation of one heat can be completed.

5.3.8　The tilting moment designed shall be in accordance with the maximum combined moment in normal operation.The furnace vessel with volume of≤200t shall be designed with full positive moment in order that it can be automatically returned to the home position by its dead weight in case of power or mechanical failure.The furnace vessel with volume of＞200t should be designed with positive and negative moments.

5.3.9　A converter shall be equipped with slag stopping device and taphole relining device.In addition，the converter shall be provided with the necessary facilities for mechanical dismantling，gunning and repair and slag splashing operation.

5.3.10　Each converter shall be provided with two lances，of which the quick exchange is performed by remote control，and the corresponding lifting and shifting devices.The lance lifting/lowering shall be realized by double-wire-rope hoisting and the speed may be 2m/min-40m/min with two-stage or stepless speed regulation.The wire rope tension measurement，falling protection device and emergency lifting device shall be provided for the lance lifting device.The control of specific lance stop position shall be interlocked with control of furnace tilting，canopy hood lifting/lowering，oxygen connection/disconnection，and lance cooling water temperature and flow rate.

5.3.11　The furnace shall be equipped with water cooled 3-6-nozzle Laval lance.The rated maximum oxygen flow rate in the lance body shall not be more than 50m/s and the mach number of spray nozzle shall be 1.8-2.1（except for dephosphorizing furnace）.For the lance cooling water，the hardness shall not be above 178mg/L and the content of suspended solids shall be lower than 50mg/L.Moreover，the outlet temperature of cooling water shall not be higher than 50℃（in summer）and the difference between inlet temperature and outlet temperature shall not be higher than 15℃.

5.3.12　The oxygen lances for converter include tapered lances and straight lances，which are selected according to the types of steel grade to be produced and the slag sticking condition of lance tubes.

5.3.13　The elbows of oxygen lances shall be made of austenitic stainless steel.When flow rate of oxygen is 50m/s-60m/s，the inner tube of the lance should be made of austenitic stainless steel.

5.3.14　A new converter shall be provided with a bottom blowing system with N2/Ar switching.The gas supply pipeline of each porous element is controlled individually.Moreover，compressed air or oxygen for purging porous elements may be provided.The gas supply system shall be equipped with complete valves and measuring elements.

5.3.15　For the transferring of hot metal，liquid steel and molten slag in converter steelmaking shop，the casting crane shall be used.

5.3.16　The capacity of crane for liquid steel transfer shall be defined based on the maximum tapping volume，ladle weight and slag weight of converter.For hot metal charging of furnace，the lifting capacity of the crane shall be determined based on the maximum hot metal charge weight of the converter，weight of the hot metal ladle and the weight of hot metal and slag.

5.3.17　The capacity of the primary dedusting system of converter shall be calculated based on the maximum decarburization rate of 0.4%/min-0.5%/min and the maximum quantity of hot metal charged into furnace.The secondary dust-bearing fume shall be collected by the doghouse around the furnace vessel，which is provided with front and back movable doors，and sent to the cleaning system.

5.3.18　The capacity of a slag pot at furnace shall meet the requirement for slag volume of 1-2 heats and the slag volume shall be calculated based on 40kg/t-120kg/t.

5.3.19　Argon should be used as the medium for ladle bottom blowing and stirring.There shall be 1-2 porous bricks.The gas supply pipeline of each porous brick should be controlled individually.

5.3.20　Deflector ladle nozzles shall be designed for hot metal ladle of converter.

5.3.21　The liquid steel ladle cars，hot metal ladle cars，return steel cars and slag pot cars in a converter steelmaking shop should be provided with AC VVVF control.The maximum speed at heavy load shall not be greater than 40m/min.

5.3.22　The rotary joints for converter shall be designed in a safe and reliable manner.New converters should be provided with separate rotary joints for gas supply and water supply respectively.For a small number of rotary joints for both steam and water，measures for identifying emergency states（water and gas leakage）shall be taken.Water-gas mixture shall not be input to converter.

5.3.23　Regenerative preheaters should be adopted to preheat liquid steel ladles and hot metal ladles.