SU1397690A1 - Cold crucible for melting metals - Google Patents

Abstract

The invention relates to metallurgy, in particular to cold crucibles for metal melting. The purpose of the invention is increased cooling efficiency. The cold crucible provides for the development of the heat removal surface by placing stiffening ribs in the cooling channel in a checkerboard pattern, and the flow ratio of the channel is 0.6-0.8, which allows for large heat flows without heat carrier boiling on the surface ma 3 ill., 1 tab.

Description

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The invention relates to the field of metallurges, in particular to cold crucibles for melting metals.

The purpose of the invention is to increase the cooling efficiency.

FIG. 1 shows a crucible for smelting materials, a general view; in fig. 2 shows section A-A in FIG. I; in fig. 3 is a view B in FIG. 2

The crucible consists of cooled sections 1, assembled with textolite rings 2 on pallet 3 and placed in the cavity of the inductor 4,

Melting to melt the tank Z.St. W- | 5 water drainage on furnaces with cold crucible bolts 6 and studs 7 secure the inductor against movements in the vertical direction.

The sections have a cooling cavity, inside which the stiffening ribs 8 20 are located. .

 The operation of a cold crucible for smelting materials takes place in the following manner.

The starting materials jbi are placed in the working space of the cold 25 crucible formed by sections 1 and tray 3 and include an inductor for heating and melting the charge. The heat flux due to heat losses from 30 melts and electric losses due to the release of Joule heat in the section metal, is heat-; Lo conductance on the ribs, on,. The water washes the ribs with a gesture of 35 bones.

The development of the heat removal surface allows for an increase in the specific heat load from the wall, since the stiffening ribs placed in the cooling channel 40 in staggered order (rather than in line with each other) lead to a local disruption of the normal steady flow of water

Flax to ensure normal flow of water, the flow ratio of the sections (i.e., the flow area of the channel) should be 0.6-0.8.

The boundary of the manifestation of the positive effect of the selected living section is the achievement of the channel wall temperature, since at this temperature the bubble boiling of the liquid goes into film boiling when the entire cooling surface is covered with a continuous film of vapor, pushing the liquid away from the surface. Heat transfer in the film boiling mode from the heating surface to the liquid is carried out by means of convective heat exchange and radiation through the vapor film. The intensity of heat transfer in this mode is quite low. At the time of film boiling, the heat flux withdrawn from the surface has a minimum value. Film boiling is undesirable.

The results of the experimental data are presented in the table.

to enhance the exchange of the amount of motion between particles of a moving fluid, thereby increasing the power dissipation.

The more developed the heat removal surface, the more heat flow can be removed.

However, the location of the stiffener in the channel leads to a loss of pressure, to a local increase in hydraulic resistance.

It was established experimentally that with the existing supply chain and

drainage on cold tig furnaces

Flax to ensure normal flow of water, the flow ratio of the sections (i.e., the flow area of the channel) should be 0.6-0.8.

The boundary of the manifestation of the positive effect of the selected living section is the achievement of the channel wall temperature, since at this temperature the bubble boiling of the liquid goes into film boiling when the entire cooling surface is covered with a continuous film of vapor, pushing the liquid away from the surface. Heat transfer in the film boiling mode from the heating surface to the liquid is carried out by means of convective heat exchange and radiation through the vapor film. The intensity of heat transfer in this mode is quite low. At the time of film boiling, the heat flux withdrawn from the surface has a minimum value. Film boiling is undesirable.

The results of the experimental data are presented in the table.

T $

Indicators

150

Film boil

0.8

(ribs all over)

132

0.9 130

(in chess order)

0.8

(in chess order)

109 104

0.7 105 (in chess order)

0,6 (in chess order)

0.52 (in chess order)

In all the compared variants, the inlet section inlet pressures were equal, and the water flow rates were different.

As can be seen from the above results, the temperature at characteristic points with a bore ratio of 0.52 is much higher, indicating a lack of cooling. This is due to the fact that in each section of the channel almost 50% of the flow area is blocked, and when moving to another section, water encounters a barrier from stiffeners, the flow is turbulized, the flow pressure is spent to overcome the resistance (friction) forces is falling. There are several such obstacles in the flow path (their number depends on the height of the cold crucible section), heat removal from the surface is difficult, this all leads to an increase in the temperature of the channel wall. Starting with the pass rate

135

150

115 -,

I 12

128

214

Lower duct wall temperature

Starting the film boil regime

Upper

pr ede

optimal

section

Significant reduction in wall temperature

lower limit

optimal

section

Film boil

cheni. equal to 0.9, the temperature at the characteristic points also begins to rise. This is because although the fins are placed in the channel, they are thin, so the oncoming flow, which almost does not hit and does not turbulent, is dissected into several flows (by the number of edges) and continues to follow at a constant speed.

The use of the proposed crucible design makes it possible to significantly increase the exhaust heat flux density. At the same time, the development of the surface of the heat sink allows removal of large heat fluxes without boiling heat carrier on the heat removal surface, which leads to an increase in the service life due to the absence of hardness salts falling on the walls.

In order to improve heat dissipation in existing cold crucible structures, one has to resort to the practice of diffusion. 2

Buf5

f

Fig.Z

Claims (1)

SUMMARY OF THE INVENTION A cold crucible for melting metals, containing an inductor, metal sections electrically isolated from one another ° with cooling channels, which have stiffeners, characterized in that, in order to improve cooling efficiency, stiffeners are installed in height staggered inductor. moreover, the coefficient of the passage section of the channel is 0.6-0.8. FIG. 2 View 5