JPH01170574A - Method for adjusting inner pressure in furnace at waiting of pouring in pressurized type molten metal furnace - Google Patents

Abstract

PURPOSE:To improve safety of a molten metal pouring device by setting an inner pressure in a furnace at the time of waiting of the pouring to less than the pressure in the furnace at the time of the pouring operation and stopping and/or emergency-exhausting supply of medium for pressurized purge when the inner pressure in the furnace exceeds the reference value. CONSTITUTION:A molten metal storing chamber 2 is formed in a molten metal pouring furnace body 1 and also a pressure meter 10 with contact for alarm and the exhaust pipe 12 for emergency are arranged on a cover 2a. At the time of waiting before pouring the molten metal by supplying the pressurized medium, by observing the pressure meter 10, the pressure reducing valve 8 is controlled and the pressure of the storing chamber 2 is always held to less than the inner pressure of the furnace at the time of the pouring operation. When the inner pressure in the storing chamber 2 exceeds this setting pressure caused by plugging, etc., of the common use exhaust pipe 11, supply of the pressurized medium is stopped with a solenoid valve 9 or the exhaust pipe 12 for emergency is opened. By this method, the inner pressure in the storing chamber 2 is immediately lowered and leakage or scattering accident of the molten metal 3 out of the furnace is prevented. Therefore, the safety of the molten metal pouring device is improved.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a furnace that can effectively prevent leakage caused by rising molten metal level, which is a concern in pressurized pouring furnaces, especially during standby for pouring. This invention relates to a method for adjusting internal pressure.

(Prior Art) A pressurized pouring furnace is equipped with a tap outlet and a pouring port that communicate in a siphon-like manner with the bottom area of a normally sealed molten metal storage chamber.
The molten metal is tapped by supplying a pressurizing medium to increase the furnace internal pressure in the molten metal storage chamber and raising the level of the molten metal to the tap opening.

For example, Japanese Patent Publication No. 57-42419, Japanese Patent Publication No. 58-41143, or Japanese Patent Publication No. 60-21819 may be referred to as prior documents relating to the pressurized pouring furnace.

(Problems to be solved by the invention) By the way, the conventional pressurized pouring furnace as described above is
In order to prevent as much as possible the generation of slag and the incorporation of oxygen, nitrogen, etc. into the molten metal during non-pouring periods between pouring operations, a pressurized medium for purging, such as Ar, etc. is used. When inert gas is supplied, especially when the molten metal is to be held for a long time, the pipes in the furnace body may become clogged with fumes, causing the pressure inside the furnace to rise more than necessary and the level of the molten metal to rise. However, there was a risk of molten metal leaking from the molten metal inlet or the molten metal receiving port of the holding furnace main body because appropriate pressure control was not implemented to deal with this.

Furthermore, if molten metal leaks during the non-pouring stage, metal will adhere to the pouring passages, etc., causing a significant hindrance to pouring work, etc., and it will take a great deal of time and effort to restore these, and the pressure inside the furnace will rise rapidly. If the temperature rises above 100 degrees, the molten metal may scatter, posing a safety problem.

It is an object of the present invention to provide a solution that solves the conventional problems as described above and enables safe pouring work.

(Means for Solving the Problems) The present invention provides a method for purging when operating a pressurized pouring furnace equipped with a sealed molten metal storage chamber and a tap outlet and a pouring port that communicate with the bottom of the molten metal storage chamber. The pressure inside the furnace during pouring standby when pressurized medium is supplied is set to be lower than the furnace pressure during pouring work, and when the furnace pressure during pouring standby exceeds a preset reference value. This is a method for adjusting the pressure inside a pressurized pouring furnace during standby for pouring molten metal, characterized by stopping the supply of the pressurized medium for purging and/or performing emergency exhaust.

FIG. 1 shows a schematic diagram of a pressurized pouring furnace suitable for carrying out the present invention. In the figure, number 1 is the pouring furnace main body, 2 is the molten metal storage chamber sealed with the lid 2a, 3 is the molten metal, 4 is the tapping passage, 5 is the receiving passage, 6 is the pouring nozzle, and 7 is for pressurizing. A medium suction pipe, 8 a pressure reducing valve, and 9 a solenoid valve. Further, 10 is a pressure gauge with an alarm contact, 11 is a regular exhaust pipe, and 12 is an emergency exhaust pipe.

(Function) Normally, when pouring molten metal 3 from the pouring furnace main body 1, as shown in FIG.
Blow in an inert gas such as R at a predetermined pressure. The level of the molten metal 3 in the storage chamber 2 is gradually lowered, and the level of the molten metal 3 in the tapping passage 4 and the receiving passage 5 is raised to perform pouring from the nozzle 6. After pouring, the regular exhaust pipe 11 is opened to lower the pressure in the storage chamber 2 to atmospheric pressure, and the molten metal levels in the storage chamber 2, pouring passage 4, and receiving passage 5 are made to be the same. Perform retention. In the above-mentioned work, especially when the holding time between pouring is long or the molten metal composition is severely restricted, it is recommended to use inert gas as the pressurizing medium used during pouring. However, it is not possible to avoid the generation of slag or changes in the composition by simply doing this, so a pressurizing medium such as an inert gas is introduced to keep the storage chamber 2 at a pressure slightly above atmospheric pressure even when the molten metal is not being poured. It is necessary to set the temperature high and purge the room.

By the way, during purging, the exhaust pipe was clogged due to the above-mentioned refume, etc., and there was a risk of molten metal leaking before pouring started.

Therefore, in this invention, the pressure inside the furnace is constantly monitored by the pressure gauge 10 so that the pressure inside the furnace is maintained at a level lower than the pressure inside the furnace during the pouring operation when the pressurized medium for purging is supplied and the furnace is waiting for pouring, that is, when the metal is not being poured. Control valve 8. Then, when the pressure inside the storage chamber 2 reaches a preset reference value P8, the supply of the pressurized medium for purging is cut off by the solenoid valve 9, or the emergency exhaust pipe 11 is opened at the same time as the solenoid valve 9 operates. The internal pressure of the storage chamber 2 is lowered to prevent leakage and scattering of molten metal.

Here, the above reference value P varies depending on the molten metal capacity of the pouring furnace used for pouring. This is because the pressure Ps in the furnace required to raise the level of the molten metal to the pouring nozzle 6 changes depending on the amount of molten metal accommodated. Therefore,
The reference value P6 corresponds to the area that satisfies the relationship PE<PS, that is, the shaded area in the figure, in Figure 3, which shows the relationship between the molten metal capacity of the pouring furnace and the furnace internal pressure required to raise the molten metal to the tapping port 4a. Must be set within the area.

In addition, when changing the reference value P6 according to changes in the amount of molten metal contained during pouring work, there is a risk of incorrect setting, so the pressure P when the amount of molten metal contained is the largest, as shown in Fig. 3, It is desirable to set it to a lower value P6'.

In this invention, it is best to use the pouring furnace shown in FIG. 1 above in pouring molten metal; The desired objective can also be advantageously achieved by providing a pressure gauge 10 and confirming with this pressure gauge 10 that the reference value PE has been reached. In carrying out the present invention, it is further preferable to provide a control device that automatically performs the above-mentioned operations when the pouring furnace is operated unmanned.

(Example) After storing 7.5 tons of molten metal in a pressurized pouring furnace with a capacity of 8 tons as shown in Fig. 1 above, Ar gas was injected into the storage chamber 2 at 1004 i! The molten metal was held while being continuously supplied at a flow rate of /min.

The internal pressure required for pouring into the above-mentioned pouring furnace is 1500+
The pressure P required to raise the molten metal to the tap hole 4a was 700+mmAq, and the alarm reference value P was set to 500mmAQ. Here, containment room 2
When the inside of the molten metal is raised to 500mmAQ, the specific gravity of the molten metal is 7
If this is the case, the hot water level in the hot water outlet passage 4 and the hot water receiving passage 5 will be approximately 71 mm higher than the hot water level in the accommodation chamber 2.

A. Gas was continuously supplied, and after 12 hours, the solenoid valve 9 for gas supply and the solenoid valve 12a of the emergency exhaust pipe 12 were activated. Afterwards, the regular exhaust pipe 10 was inspected, and it was found that the exhaust pipe was clogged with fume, and there was evidence that the molten metal level had risen by about 70 mm in both the pouring passage 4 and the receiving passage 5. It was done. After flushing the regular exhaust pipe 11, the alarm was reset and gas was supplied again, but no trouble occurred.

(Effects of the Invention) According to the present invention, it is possible to completely prevent leakage and scattering of molten metal caused by the pressurized medium for purging, which was a concern when using a pressurized pouring furnace, especially when waiting for pouring.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional schematic diagram of a pouring furnace suitable for carrying out the present invention, Fig. 2 is a cross-sectional schematic diagram of a conventionally used pouring furnace, and Fig. 3 is a diagram showing the capacity of molten metal. It is a graph showing the relationship between the furnace internal pressure required for pouring.

Claims (1)

[Claims] 1. When operating a pressurized pouring furnace equipped with a sealed molten metal storage chamber and a tap outlet and a metal receiving port that communicate with the bottom of the molten metal storage chamber, a pressurized medium for purging is supplied during pouring standby. The furnace pressure is set below the furnace pressure during pouring work, and when the furnace pressure during pouring standby exceeds a preset reference value, the supply of the pressurized medium for purging is stopped and/or Alternatively, a method for adjusting the pressure inside a pressurized pouring furnace during standby for pouring molten metal, which is characterized by emergency exhaust.