JPS5940244B2 - Melt level detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides a method for transferring molten material such as hot metal, molten steel, and slag to a hot metal ladle.
The present invention relates to a method capable of detecting the level of molten material in a processing container such as a ladle such as a molten steel ladle or a slag ladle, a torpedo car, or a tundish when the melt is charged into the processing container.

The hot metal tapped from the blast furnace is received by a hot metal ladle or torpedo car, and the hot metal is further refined into molten steel at a steelmaking factory. It is being received and transported.

It is important to always maintain the same level of the melt charged into the melt processing vessel in these series of steps from the viewpoint of processability and workability.

In other words, the hot metal received by the torpedo car is
The hot metal is sent to the next desulfurization process, and in the desulfurization process, the lance is lowered from above and the hot metal is desulfurized while blowing in NO gas along with the desulfurization agent. However, if the torpedo car receives more than the specified amount, N2 If an overflow occurs due to gas injection and less than the specified amount of pig iron is received, N
The lance for blowing two gases did not reach the required depth in the hot metal, resulting in insufficient desulfurization. In addition, when receiving and transporting molten material in ladle such as hot metal ladle, molten steel ladle, slag ladle, etc., if the charging amount is small, the so-called combining work and transportation of two ladle parts into one ladle will increase, and loading will increase. If the quantity is large, there is a risk of overflow during transportation.

From the above point of view, attempts have been made to maintain a constant level of molten material in the processing container. There is a problem that the torpedo car cannot be easily handled, and when using a torpedo car, the equipment is very large and the equipment cost is high.Also, due to the corrosion of the inner refractory material due to the number of times the torpedo car is used, Even if the amount of pig iron is constant, the level of molten material varies, causing problems in torpedo desulfurization.

Therefore, there is a lot of reliance on visual inspection by on-site workers, and even in the case of visual inspection, there are large errors in accuracy, and there are problems in that the working environment is poor due to high heat, dust, etc. In view of the above-mentioned problems, the present invention aims to provide a method that can always safely and reliably detect a desired level of molten material in a processing container. Among the bricks, ceramic bricks such as zirconia bricks, thoria bricks, and yttoria bricks, which have oxygen ion conductivity at high temperatures, are installed at positions corresponding to the desired level, and the oxygen source such as oxygen or air is supplied to the ceramic bricks. This is a method for detecting the level of molten material, which is characterized by measuring the electromotive force generated by ceramic bricks and detecting the charging level of molten material.

The details of this invention will be explained below.

In the method of the present invention, the ceramic brick is of course a refractory material, and for example, in a zirconia brick which is a ceramic brick, the oxygen atoms contained in the brick are separated into O→02++27 at a high temperature range of 6000C or higher.

When the molten steel whose level is to be measured and the air supplied as an oxygen source are in contact with the zirconia bricks, oxygen ions are conducted from the zirconia bricks to the molten steel with a low oxygen concentration, and from the air with a high oxygen concentration. Oxygen ions are conducted into the zirconia brick. In this way, inside the high-temperature zirconia brick, oxygen ions are conducted from the air side supplied as an oxygen source to the molten steel side, and the contact surface between the air and the brick,
And an electromotive force is generated between the contact surfaces of the molten steel and the bricks,
The voltage of the generated electromotive force increases as the difference in oxygen concentration between the molten material in contact with the zirconia brick and the oxygen source increases, and as the temperature of the molten material increases, the voltage increases, and the following equation holds true. RT
PO2() E=1・1・n? 4FP02 (1) E: Generated electromotive force (VOlt) R: Gas constant (1.9865Cat/MOl・℃) T:
Absolute temperature of ceramic brick (0K) F: Falade constant (23.066caVv01t-MOl) PO2 (1)
:Oxygen partial pressure of melt (Atm)PO2():Oxygen partial pressure of oxygen source (Atm) Next, embodiments of the present invention will be described based on the drawings.

In FIG. 1, 1 is an iron shell of a steel receiving ladle, 2 is mortar for fixing refractories, 3 is a high alumina refractory brick, and 4 is a zirconia brick for obtaining generated electromotive force. The zirconia brick 4 is assembled at a desired melting level position of the steel receiving ladle, and a cavity 5 with a diameter of 10 mm is provided in the zirconia brick 4, and an air blowing pipe 6 for an oxygen source is connected to both ends of the cavity 5. However, the air blown from the blower 10 is circulated through the cavity 5 via the joint 7 and the air blowing pipe 6, and is discharged to the outside of the pot.
In this invention, in order to measure the electromotive force generated in the zirconia brick 4, an electrode 8 is fixed in the cavity 5, a wiring 9 is installed at one end of the electrode 8, and a wiring q is connected to the iron shell 1. It is fixed to the surface, and each wiring is connected to a generated electromotive force measuring device consisting of a generated electromotive force setting device 11 and an alarm device 12.

The generated electromotive force setting device 11 of the measuring device is preset with a generated electromotive force value as a reference so that the alarm device 12 is activated when a certain generated electromotive force is generated. In this case, the generated electromotive force shows different electromotive force depending on the various melts charged into the processing vessel, and the generated electromotive force varies in stages between when the processing vessel is empty and when it is charged. Since the electromotive force varies, the reference value of the generated electromotive force that should be set in advance may be set based on experimental values. That is, since the steel receiving ladle is always preheated to about 1000°C before receiving the steel, the generated electromotive force measured while blowing a gentle breeze of 50ccA1r from the air blowing pipe 6 using the method shown in Fig. 1 is several hundred meters. However, usually 140
When molten steel at a temperature of 0 to 1500°C is received, and as the amount of received steel increases, the molten steel rises to the zirconia brick 4 position and comes into contact with the zirconia brick, the electromotive force generated by the zirconia brick further increases, and approximately It reaches as high as 1400mV. This change in the generated electromotive force is detected by the setting device 11, and by comparing the detected value with the setting value 1300m preset in the setting device 11, the alarm device 12 is notified only when a value of 1300mV or more is detected. An alarm is issued. This alarm causes the steel receiving ladle to stop receiving steel, thereby ensuring the desired level.
``In addition, if a protective cover 13 is attached to protect the air blowing pipe 6 and electric wiring 9, 9' provided in the steel receiving ladle, it can be protected from dust and leaked molten steel.In this invention method, When the amount of air blown into the cavity provided in the ceramic brick increases, the temperature of the ceramic brick decreases,
Also, if the air flow rate is very low, the oxygen source will decrease, so the diameter of 10m7! In the L cavity, the air blow rate is 30-50
A light breeze of CC/4-1r is most suitable.

As explained above, the method of the present invention makes it possible to easily and accurately detect the level of the melt in the melt processing vessel.

Furthermore, since the melt level can be detected remotely, the problems of danger and poor working environment associated with conventional visual inspection work can be eliminated. Further, the present invention has a simple configuration and has excellent responsiveness.

[Brief explanation of drawings]

The drawings are explanatory diagrams showing one embodiment of the present invention. 1... Iron skin, 2... Mortar, 3...
...High alumina refractory brick, 4... Zirconia brick, 5... Cavity, 6... Air blowing pipe, 7... Fitting, 8... ...electrode, 9.
...Electrical wiring, 10...Blower, 11...
... Setting device, 12 ... Alarm device, 13 ...
...protective cover.

Claims (1)

[Claims] 1. Install a ceramic brick at a position corresponding to a desired level among the refractory bricks lined in the melt processing container, measure the electromotive force generated by the ceramic brick while supplying an oxygen source to the ceramic brick, A method for detecting a level of a melt, comprising detecting a charging level of the melt.