JPS6159372B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improvement in a refining immersion lance for refining molten metal. Conventionally, when refining molten metal with an immersion lance, different types of gases have been used depending on the purpose and effect. For example, in the case of removing Si and carbon from hot metal, gaseous oxygen is used as an oxidizing agent to induce the oxidation reaction of Si and C. In the case of hot metal desulfurization, argon, nitrogen, dry air, or other gas is used as a carrier for the desulfurization agent depending on the product quality. Argon gas is generally used when the purpose is to control the composition of molten steel, adjust the temperature, float inclusions, etc. In addition, the difference between the top blowing method and the immersion method is that in the case of the immersion method, a strong stirring effect of the molten metal can be obtained at the same time as gas is supplied, and there are many studies regarding the effect of stirring on the refining effect. reported in the literature. However, although the immersion method has the above-mentioned advantages, it also has the disadvantages that the lance is immersed in molten metal, resulting in significant erosion and short service life of the lance. The service life of this lance is limited by the need for the refining lance to maintain proper refining conditions and to ensure safe operation. Conventional smelting lances generally have a structure in which the immersion part of the lance is coated with a refractory material in order to extend their service life.Depending on the operating temperature, dimensions, and type of refining gas, The lifespan is about 30 to 60 minutes at most. On the other hand, lances used in the top-blowing process are generally equipped with a closed circuit of cooling water in addition to a gas injection nozzle, and their service life is mainly due to slopping, spitting, and radiation transmission during refining. Approximately 1
It is 30,000 to 30,000 minutes. Considering this difference in lance life, it is expected that providing a closed circuit of cooling water for the immersion lance will dramatically reduce the difference in life, but if the cooling water leaks, there is a risk of a steam explosion. Therefore, it cannot be adopted at the current technological level. On the other hand, in order to strengthen the stirring with the aim of improving the refining effect with the immersion lance, the flow rate of the blown gas is increased〓〓〓〓
Alternatively, there are two methods of increasing the immersion depth at the nozzle outlet. In terms of equipment, an increase in gas flow rate leads to an increase in the diameter of the lance flow path pipe, and a method of increasing the immersion depth at the nozzle outlet leads to an increase in the length of the lance or the stroke of the lance support mechanism. Moreover, in either case, there is a drawback that the amount of refractory used is large. The present invention aims to solve the current situation as described above, and provides an independent system for a flow path for passing a refining gas and a flow path for passing a liquid made of the same element as the gas, so that the flow path for the liquid is This immersion lance for refining is characterized in that the outlet is arranged around the outlet of the gas flow path. In the above-mentioned immersion lance for refining, the channel through which the refining gas passes is an oxidizing gas such as gaseous oxygen or air,
Alternatively, it means a channel through which an inert gas such as argon gas or nitrogen passes. Placing the liquid flow path outlet around the gas flow path outlet is a necessary configuration in order to ensure cooling efficiency by removing heat from vaporization of the liquid and to prevent lance melting. The present invention will be explained below with reference to embodiments shown in FIGS. 1 and 6. FIG. 1 is a longitudinal sectional view of a refining immersion lance, FIG. 2 is a view taken along the line AA in FIG. 1, and FIGS. 3 and below are views showing examples of variations of the present invention. 1 is a tube forming a gas flow path, and 2 is a tube forming a liquid flow path. The tubes 1 and 2 have a concentric double tube structure with ribs 3 as spacers as shown in Fig. 2, or 5th and 6th tubes.
A separate piping structure as shown in the figure may also be used.
In either case, the liquid flow path outlet 5 is arranged around the gas flow path outlet 4, and these piping dimensions,
The cross-sectional area is selected in each case to suit the refining purpose and the geometry of the piping. In the figure, 6 is a refractory, and 7 is a stud for holding the refractory 6. 8 is a liquid flow rate control valve, and 9 is a gas flow rate control valve, which are connected to a liquid tank or a gas tank (not shown) via piping. By arranging the liquid flow path outlet 5 around the gas flow path outlet 4 in this way, the liquid is vaporized when discharged from the lance, so that the discharge surface 10 of the refining immersion lance and its vicinity can be efficiently Since the lance is cooled, the risk of melting, breakage, etc. of the lance is significantly improved compared to conventional lances, and its service life is also improved. By injecting ^1Nm3 of gas in liquid form, the refining gas is 72.3kcal when oxygen is used, and 72.3kcal when nitrogen is used as the refining gas.
You can get 61.0kcal of heat out, and 69.7kcal of heat with argon. The gas-liquid ratio is selected depending on the refining purpose, required stirring power, and set processing time. The effect of stirring molten metal is dramatically improved due to the expansion of vaporization volume when the state changes from liquid to gas. If the stirring effect is described by the formula below, when the same volume of liquid as gas is blown, approximately
You can get 1000 times more stirring effect. Therefore, it is possible to secure a large reaction interfacial area by simply blowing a small amount of liquid, so that the refining reaction can be promoted more skillfully than in the past. ε=0.0285Q・T・{log(1+Z/H)}/W where ε=: Stirring energy density (watt/T) Q: Refining gas flow rate (l/min) T: Temperature of molten metal (K ) Z: Depth of molten metal (cm) H: Vacuum height of molten metal at 1 atmosphere (cm) W: Weight of molten metal (T) By the way, when comparing the refining immersion lance according to the present invention with the conventional one, , the improvement is obvious as shown in the table below. The dimensions are determined in the table below under the following conditions. Argon is used as the refining gas Processing amount: 90TON/Heat Argon total flow rate: 22.5Nm ³ (gas equivalent amount,
Gas/liquid ratio 0.125) Geometric piping structure: Conventional = single pipe, present invention = concentric double pipe

[Table] 〓〓〓〓

[Table] As is clear from the above, the immersion lance for refining of the present invention is compact, has a service life more than twice as long, and can obtain a powerful stirring force by injecting a small amount of liquid, making it extremely useful for operations. It is a lance that has practical effects.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of the immersion lance for refining of the present invention, FIG. 2 is a view taken along the line A--A in FIG. 1, and FIGS. It is a figure showing other examples. 1: Pipe forming a gas flow path, 2: Pipe forming a liquid flow path, 3: Rib, 4: Gas flow path outlet,
5: Liquid flow path outlet, 6: Refractory, 7: Stud, 8: Liquid flow rate control valve, 9: Gas flow rate control valve,
10: Discharge surface of immersion lance for refining. 〓〓〓〓

Claims (1)

[Claims] 1. A channel for passing refining gas and a channel for passing a liquid made of the same element as the gas are provided as independent systems, and the outlet of the liquid channel is arranged around the outlet of the gas channel. Immersion lance for molten metal refining.