Abstract
The current invention refers to a blowing spear (100) used in the primary refining process for obtainment of steel, developed in such a way to maintain the loading and blowing operational conditions, comprising at the base a copper nozzle (101) to which is welded in its extremity a tube (102), comprising yet a module (125) with cleaning output (103) and positioned above module (125) a steel tube (118) and on its upper extremity, the head (107) that comprises a cooling liquid inlet (115), a gases inlet (116) and a cooling liquid outlet (117), comprising yet the spear (100) in its interior the inner tube (122) responsible for the gas passage and the intermediate tube (123) responsible for the division between the cooling liquid inlet flow and its outlet passing mandatorily through the copper nozzle (101).
Claims
1. A blowing spear for fabrication of metals and maintenance of loading and blowing operational conditions in a steel production oven in which molten steel is processed and purified, said spear comprising an inlet end comprising a steel tube and an outlet end comprising a copper nozzle, said steel tube having a cooling liquid inlet and outlet and a combustion gas inlet, a conical form tube disposed intermediate said steel tube and said nozzle, with the reduced diameter end of said conical tube being secured to said nozzle, and a plurality of cleaning outlets in communication with said combustion gas inlet disposed between said conical tube and said steel tube for emitting combustion gas for heating said spear and said oven and preventing dross formation thereon.
2. A blowing spear as defined in claim 1 in which said conical tube is formed from copper.
3. A blowing spear as defined in claim 1 in which said cleaning outlets are disposed in a copper module disposed between said conical tube and said steel tube.
4. A blowing spear as defined in claim 1 in which said cleaning outlets have working angles that vary from 0° through 170° in relation to vertical, with a minimum angle of 10° to vertical in the direction of the molten steel and a minimum angle of 0° to vertical in the direction of said inlet end.
5. A blowing spear as defined in claim 1 and including fins in said conical tube for dissipating heat.
6. A blowing spear as defined in claim 5 in which said fins are helical in shape.
Description
FIGURES
(1) The current invention will be meticulously described below based on an execution example represented at the figures listed as follows:
(2) FIG. 1—it is a cut overview of the spear at operation position in the oven.
(3) FIG. 2—it is a cut overview of the spear
(4) FIG. 3—it is a top overview of the spear's outlets set destined for cleaning the “mouth” and top part cleaning maintenance;
DETAILED DESCRIPTION OF FIGURES
(5) FIG. 1 presents the overview of spear set (100) positioned inside a steel production oven. This set is comprised by a copper nozzle (101), which has in its extremity the oxygen outlets in a varied number of holes quantity, and the conical tube (102) having internal fins in copper. The conical tube's length (102), as well as its conicity is a function of the products and processes characteristics of each oven. In a general way, the more the oven's capacity, the greater will be the conical region's length, as it implicates in the positioning of the outlets that will perform the spear's cleaning at the oven's upper part and “mouth”. The conicity is dimensioned in function of the slag volumes, being in a general way, the more the slag volume, the lesser the spear's conicity. Above the conical tube (102), it is situated the set of cleaning gases outlets (103), whose quantities and dimensions vary, depending on the process needs, in relation to the mouth's cleaning (105) or cleaning of the spear's cylindrical upper part (106) or both, or yet, of the oven's dimensions (104). The size of the cleaning gases outlets may vary from sonic speeds to supersonic speeds, being the sonic speed for post-combustion at short distances, maintaining the spear's upper part in higher temperatures, and the supersonic speed for post-combustion at long distances, maintaining the oven's “mouth” region heated, avoiding the “dross” adherence. The oven's dimensions determine the quantity of outlets, as the adequate distribution promotes a homogeneous cleaning at the “mouth” circumference. Above the cleaning outlets (103), it is located the spear's cylindrical upper part (106), in steel. At the upper extremity, there is the spear's head (107), which purpose is promoting the inlet of gases and inlet and outlet of the cooling liquid.
(6) Yet, in FIG. 1, it is presented a metallurgy oven (104), which have a metallic external wall named carcass (108), forming a container opened at the upper part, the oven's mouth (105). The metallurgy oven is coated internally with a refractory wall (109) with the objective of maintaining the liquid metal at the temperatures developed in the process.
(7) During the steel fabrication process, the oven's interior (104) is invaded by three phases mixed by the agitation caused by the copper nozzle holes (101). The phases are: liquid metal or bath (110), slag (111) and gases (112). The projections of these elements at the wall situated at the oven's “mouth” region (105), when solidified, form what we call dross (119).
(8) At the upper part of the oven (104), a de-dusting duct (113) is installed with a side opening (114) that permits the entering movement of the spear (100) routing inside the oven (104) and its removal at the end of the processed batch.
(9) In the position of bath processing (110) inside the oven (104), the spear needs to be advanced at an appropriate distance from the bath (110) so that the oxygen jet, going out of the copper nozzle (101), is able to promote the necessary mixture so that the reactions happen. During the process, the three mixed phases form an emulsion that covers part of the spear's body (100) submitting it to elevated temperatures. This emulsion projects bath particles (110) and slag (111), which can adhere either to the spear (100) as to the oven's “mouth” (105), in the form of “dross” (119).
(10) As it can be observed in FIG. 2, the spear (100) comprises an inlet (115) for cooling liquid, an inlet for gas (116) and an outlet for cooling liquid (117), all located at spear's upper part, and the head (107). By means of the cooling liquid circulation, the spear's heat is removed (100), increasing its lifetime. Between the copper nozzle (101) and the steel tube (118), the conical tube (102) is installed, having its smaller diameter welded to the extremity (101). The tube's conical shape (102) propitiates the detachment of the adhered mixture, as there is no opposition to the gravitational force. Thus, the mixture of bath's liquid metal (110) and slag (111) adhered (dross) is detached by the action of its own weight. In addition, the thermal contraction speed difference prevents the mixture adherence to the conical tube (102). In the current invention, the increase of heat extraction promoted in the region of the conical tube (102), results in the quick contraction of the material adhered during its solidification. This way, the forming dross (119) suffers rupture and fall, due to the gravitational force. Besides the tube's conical geometry (102), the current invention proposes the copper employment in the fabrication of the conical tube (102), while a steel tube, of cylindrical geometry, is used in the state of art. The advantages of using copper reside in the fact that this metal has a thermal conductivity 5 times higher than steel, even having a lower melting point, which at first might be contradictory, as copper would melt too much sooner than steel. However, the heat absorbed by the conical tube (102) of the current invention is rapidly transmitted to the cooling liquid, not permitting that the copper melting temperature is reached, preventing that the mixture thin layer (dross) (119) remains adhered. Besides, copper is chemically stable within the oven's atmosphere, which minimizes undesirable reactions.
(11) FIG. 3 displays the region of cleaning outlets (103). For the purpose of mouth cleaning (105), the cleaning outlets (103) are determined taking into consideration the dross forming profile (119) of each oven. The ovens are generally suspended by trunnions that permit the rotation over their shafts. The tilting direction determines two basic operations: the bath leakage (110) by the leakage channel (121) and the slag leakage (112) in the opposite direction. In function of the passage of these materials, the formation of dross (119) of mouth (105) assumes varied profiles. The cleaning outlets (103) are projected to reach regions where there is accumulation of dross (119) and avoid reaching the cleaned regions with the apparent refractories (109), thus contributing for increasing the oven's campaign (104). It is taken into consideration, for sizing of the cleaning outlets, the distance of the spear (100) to the oven (104), as well as the angles compensation taking into account the speed of the ascendant gases (112) coming from the reactions with the metallic bath (110). The possibilities or working angles at cleaning outlets (103) during the spear moves (100) inside the oven (104) vary of 170° in relation to the vertical line, making possible a minimal angle of 10° with the vertical line in the bath direction, and a minimal angle of 0° with the vertical line in the spear's head direction (107). For this purpose, the cleaning outlets (103) have a supersonic character, allowing to reach the regions of interest. However, when the purpose is maintaining the cleanliness of the cylindrical steel tube (118) located above the conical tube (102), the cleaning outlets (103) are projected to have low or sonic velocities, causing the temperature increase near the spear's upper regions (100).
(12) FIG. 2 displays the spear set assembly (100), having on the base a copper nozzle (101) connected by the external and lower portion to the conic tube (102). Afterwards, the module with the cleaning outlets (103) is inserted. Above this module, there is the steel tube (118) and on its upper end, there is the head (107) that comprises the cooling liquid inlet (115), gases inlet (116) and cooling liquid output (117). Inside the spear (100), as it is observed in FIG. 3, two more tubes are showing: the inner tube (122), responsible for the gas passage and the intermediate tube (123), responsible for the division between the cooling liquid inlet flow and its outlet passing mandatorily through the copper nozzle (101). The tubes, inner (122) and intermediate (123), do not need to be in copper, as they are not in direct contact with the external atmosphere. The assembling of these parts is made in a tightly way. Between the intermediate tube (123) and the conical tube (102), helical fins (124) are inserted. The helical fins have the purpose of maximizing the thermal exchange at the copper conical tube (102), being its sizing variable in the number of fins, as well as in the formation angle of the helicoids. In the fabrication and assembling process, the helical fins may be fabricated directly at the external wall of the intermediate tube (123) or at the internal wall of the conical tube (102).
(13) The cleaning outlets (103) are distributed in a copper module (125). The liquid used by the spear's refrigeration (100) has normally a turbulent flow, as it must have enough speed to not get heated reaching ebullition inside the ducts. For this purpose, the copper module (125) is projected to permit the free passage of the cooling liquid in both directions, with no losses for the flows and pressures necessary for the performance.
