摘要:
Method and device to control the force applied to the electrode-bearing arms of an electric arc furnace, the vertical regulation of the electrodes being achieved with an electrohydraulic or electropneumatic system consisting of an operational cylinder actuated by a fluid under pressure so as to raise and lower the electrodes, the control means of the system being adjustable by means of an electrical device, whereby the working pressure of the operational cylinder is measured by a pressure transducer (15) and is processed by a processor system (16) so as to obtain the weight of the electrodes and the condition of static pressure, the processor system (16) governing a quick-response servovalve (18) and being governed by an interface (19) of the system that adjusts the electrical current fed to the electrodes (11).
摘要:
A cooled roof for electric arc furnaces (20) or ladle furnaces (29). The roof being used as a covering element and including a cooling system comprising tubes fed with cooling fluid. The roof including at least a central aperture (25) for the positioning and movement of the electrodes (30) and at least a peripheral aperture (14) for the aspiration and discharge of fumes. The aperture (14) being connected to intake systems. The roof including two single-block cooling structures, inner (1) and outer (12), consisting of respective bent tubes (15, 16) developing according to adjacent and superimposed rings or spirals. The inner (11) and outer (12) cooling structures being associated with one another at least in correspondence with the respective bases facing towards the inside of the furnace (20, 29). Between the inner cooling structure (11) and the outer cooling structure (12) there being defined an annular interspace (13) in which the fumes circulate in an annular direction and slow down. The annular interspace (13) communicating with the peripheral aperture. The inner cooling structure (11) including fume-transit interstices connecting the inside of the furnace (20, 29) with the annular interspace (13).
摘要:
Crystalliser and method to control the deformations of the sidewalls of a crystalliser (11) for the continuous casting of billets/blooms/slabs (24), which is associated with a mould (10) and cooperates externally with a box-shaped structure (13) creating a cooling chamber (14), in which a cooling fluid circulates, and cooperates internally with the skin of the billets/blooms/slabs (24) being formed, the cooling chamber (14) containing an intermediate wall (20) creating a circulation channel (21) in cooperation with the outer surface of the sidewall (12) of the crystalliser (11), at least one upper zone (37) being included in cooperation at least with the vicinity of the meniscus and with the portion below the meniscus (27) of liquid metal, a lower zone (38) being also included and beginning in the vicinity of the zone of separation of the forming skin from the inner surface of the sidewall (12) of the crystalliser (11) and extending towards the outlet of the crystalliser (11), the pressure of the cooling fluid in the lower zone (38) of the crystalliser (11) being a function of the desired value (g1) of an air interspace (36) between the sidewall (12) of the crystalliser (11) and the skin of the forming billet/bloom/slab (24), this desired value of air interspace (36) tending towards a zero value.
摘要:
The crystalliser (11) cooperates externally with a box-shaped structure (13) creating cooling chambers (14), in which a cooling fluid circulates, and cooperates internally with the skin of the billets, blooms or slabs (24) being formed. The cooling chambers (14) containing intermediate walls (20) create circulation channels (21) in cooperation with the outer surfaces (12) of the sidewalls of the crystalliser (11), at least one upper zone (34) being included in cooperation at least with the vicinity of the meniscus and with the portion below the meniscus (33) of liquid metal, a lower zone (26) being also included and beginning in the vicinity of the zone of separation of the forming skin from the inner surfaces (12) of the crystalliser (11) and extending towards the outlet of the crystalliser (11). By acting on the cross-section and/or conformation of at least one longitudinal portion of at least one side of the cross-section of the circulation channels (21), e.g., by providing elements to disturb the flow of cooling fluid in the circulation channels (21), and by acting on the different pressures of the cooling fluid present between the inlet and outlet of that longitudinal portion of the circulation channels (21) a desired turbulence of the cooling fluid is created which is such as to increase the coefficient of heat exchange to a value greater than 40,000 W/m.sup.2 K. The side walls of the crystallizer preferably have a thickness between 4 and 15 mm.
摘要:
Adapter device for composite electrodes having an auxiliary reactance function on electric arc furnaces, the furnace being able to be of a type fed with direct current or alternating current and comprising at least one secondary supply circuit which connects a transformer (13) to one or more electrode-holder arms (16), the adapter comprising a hollow cylindrical metallic body (21) associated with the relative electrode-holder arm (16) and directed towards the inside of the furnace, the metallic body (21) being connected at its lower end to a graphite segment (24), directed towards the bath of molten metal, at least part of the the adapter (20) including a conductive portion (30) which is made of a highly conductive material and is solidly associated with the metallic body (21) and is dimensioned according to the desired value of overall reactance of the secondary circuit of the furnace.
摘要:
System for connection of pneumatic and/or hydraulic hoses (11) on composite electrodes (12) for arc furnaces, the electrodes (12) comprising, at least one hollow adapter (13) associated at their lower part with a replaceable graphite element (14), the electrode (12) cooperating with an electrode-holder arm (15) and being displaceable axially in relation to that electrode-holder arm (15), the hoses (11) being associated at one end with a first connection assembly (18a) associated with a support (17), the adapter (13) including a solidly attached second connection assembly (18b) mating functionally with the first connection assembly (18a), the first (18a) and second (18b) connection assemblies comprising mating connecting elements (19a, 19b) equipped with elements to interrupt the flow of the fluid which can be temporally actuated, the a support (17) associated with the first connection assembly (18a) having a first inactive position temporally solid with the electrode-holder arm (15) and a second working position released from the electrode-holder arm (15) and temporally solid with the second connection assembly (18b) associated with the adapter (13), the transition from the first inactive position to the second working position of the support (17) taking place according to the position of the electrode (12) in a defined position of engagement/disengagement.
摘要:
Electric arc furnace with alternative sources of energy, which functions with direct current or alternating current and comprises at least one lance (12) to inject pure or combined oxygen above the bath (16) and a plurality of tuyeres (13) positioned in the hearth of the furnace (10) to inject oxygen below the bath, the tuyeres (13) being cooled by a peripheral movement of a cooling mixture consisting of at least one gas having a high cooling power (methane, butane, inert gases, etc.) and of at least one diluting gas (nitrogen, carbon dioxide), pipes (15) being included to introduce additives and powdered coal, post-combustion burners (28) possibly being comprised, the tuyeres (13) including an oxygen delivery pipe (18) having a diameter greater than 8 mm., the oxygen pressure being capable of being modulated according to the working steps, there being a constant minimum pressure of delivery. Melting operating method associated with such an electric furnace, wherein the charging operation with each single charge (skip) is divided into defined periods, with which are associated a pressure of delivery of oxygen through the tuyeres (13) and a percentage of gas having a high cooling power and proportioned to the rate of flow of the oxygen, there being a minimum pressure of delivery of oxygen in each moment of the working of the furnace (10).
摘要:
This invention concerns a procedure for controlling the type of arc in an electrical furnace (F), which comprises the monitoring (R) of the short circuit power of the network line (L) during a period of inactivity of the arc, whereby the value thus monitored is processed (B) to determine a primary voltage (V) to be maintained at a transformer (T2) supplying the electrodes of the furnace (F), and whereby the processing (E) combines fixed parameters (P) and at least variable parameters relating to:pre-set conditions of the arc (S),conditions of a substation tap changer (VAR),and line parameters (C) including at least the state of connection of banks of capacitors (C1-C2).The invention also concerns an arc furnace (F) which employs a procedure for controlling the type of arc according to the methods described herein.
摘要:
Tapping method for molten metal from containers (13) including at the lower part a tapping channel (14) associated at the end part with a discharge hole (15) substantially vertical or sub-vertical, the discharge hole (15) being associated at the lower part with a sliding interception device (19), wherein the tapping channel (14) comprises, associated with the walls, an electromagnetic device (17) with spirals (18) and a system for cooling the walls, wherein, during the end-of-tapping step of the liquid metal the sliding interception device (19) is activated by closing the discharge hole (15) and allowing the metal in the tapping channel (14) to solidify so as to form at least a layer which lines both the tapping channel (14) and the discharge hole (15) filling it completely, and that during the start-of-tapping step the sliding interception device (19) is activated by leaving the discharge hole (15) free and the metal which is blocking the discharge hole (15) is melted by means of the electromagnetic device (17) by varying the characteristics of the current flow.Tapping device which achieves the method as described above and comprising means (38) to feed the electromagnetic device (17) with electric current as a function of the steps of melting and tapping, the sliding interception device (19) comprising a first part (23a) with a high resistance to heat shock, corrosion and erosion and a second part (23b), positioned adjacent to the first part (23a), with high heat conductivity.
摘要:
Method to manage an insulated cooling bed placed downstream of at least one continuous casting machine with one or more feeder ways (12a, 12b, 12c, 12d) and upstream of an outlet rollerway (20) associated with a reheating and temperature-equalisation furnace (15) serving a rolling mill (16), the cooling bed (11) comprising at the inlet a first bridge crane transfer (21a) to load the billets (13) from the feeder ways (12a, 12b, 12c, 12d) and cooperating at the outlet with a bench (14) to collect the billets (13), wherein the first bridge crane transfer (21a) removes the billets (13) from one rollerway (12) or the other and lays them gradually onto the cooling bed (11) insulated at least at the lower part, a second bridge crane transfer (21b) removes the billets (13) from one or another rollerway (12) or from the cooling bed (11) and lays the billets (13) on the outlet rollerway (20) or on the collection bench (14), the billets (13) being made to advance on the cooling bed (11) rotating on their axis. Cooling bed placed between at least a continuous casting machine and a rolling mill (16), including upstream one or more feeder rollerways (12) and downstream an outlet rollerway (20) associated with a bench (14) to collect cold billets and with a reheating and temperature-equalisation furnace (15), the bed comprising positioning seatings (19) for the billets (13) and a first bridge crane transfer (21a), the cooling bed (11) including at least at the lower part an insulated containing structure (18) and comprising a second bridge crane transfer (21b) which is driven autonomously and independently in relation to the first bridge crane transfer (21a), the second bridge crane transfer (21b) being functionally associated at least with the feeder rollerways (12), the positioning seatings (19) for the billets (13) and the outlet rollerway (20).