JPH02504651A - How to minimize process gas consumption in metallurgical processes - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] name of invention How to minimize process gas consumption in metallurgical processes Technical field The present invention allows a gas such as argon, oxygen, or air to enter the molten metal into the inner tube and into the inner tube. The molten metal is blown through a feed pipe consisting of a concentric outer pipe and terminating below the liquid surface. The present invention relates to a method for minimizing the consumption of process gases in metallurgical processes.

Background technology During the last few years, numerous applications of the technical methods described at the outset have been developed. Against this Accordingly, the purpose is to carry out confectioning to minimize the consumption of main gas and cleaning gas. A study was conducted to show that the gas consumption in such a method is clearly This is because it is of critical importance to the economics of this method. For example, “5teel” Research 55 (1984)” Magazine, Volume 12, pp. 537-579 , the basics of nozzle configuration for blowing gas into molten metal were scientifically investigated. , for the practical implementation of such a method for gas introduction, a minimum gas flow and It is necessary to be able to adjust the area between the maximum gas flow and pointed out. Of course, the minimum mass flow of gas must not be lowered, because if This is because the supply pipe or nozzle becomes clogged. The compositional prescription described in the above-mentioned literature is The minimum volume flow is adjusted so that the sonic velocity is adjusted as the discharge velocity at the exit cross section. It stipulates that the air must be blown through the ring-shaped gap and nozzle. This will cause the melt to It is possible to adjust a pressure greater than the static pressure of molten steel in the molten metal tank at the nozzle outlet. Becomes Noh. At this time, nozzle blockage is impossible.

Up to now, it is understood among those skilled in the art that in the processes related to this specification, gases are It is said that it should enter the molten metal bath as a jet rather than as a blow stream. A consensus of opinion prevails. In this case, the transition from bubbles to jet flow is at the speed of sound at the latest. This is done when the .

However, in this context, for example when producing special steel in a converter (converter), For example, technical gases such as argon or oxygen or nitrogen are consumed in large quantities. must also be taken into consideration.

The amount of oxygen required depends on the amount of molten metal and primarily on the carbon to be removed.

The required oxygen flow depends on the time clock given in advance by e.g. an electric arc furnace. Depends more. This sets the geometry of the nozzle, since the This is because it operates within an area that is restricted above and below.

However, this is true even though this introduction requires more metallurgical work to be done. Nozzles with expensive inert gases, especially argon, even when carried out in small quantities shall be guided into the turret with a minimum amount set by the geometric configuration of means.

Therefore, a device with which the adjustment area of the nozzle can be extended in the direction of smaller mass flow The installation provides significant cost savings.

technical challenges The object of the invention is to terminate below the molten metal liquid surface, e.g. with argon or oxygen or It not only prevents blockage of supply pipes for gases such as nitrogen, but also reduces the consumption of these gases. The aim is to minimize the

The above object is solved by the features described in the characterizing part of claim 1.

Using the well-known physical law that the volume of a gas is proportional to its temperature, process gas It is possible to reduce energy consumption to about half what it used to be, and perhaps even less It is Noh. A particular advantage of the invention is here indicated. nozzle or gas outlet To maintain the space in the mouth opening, just generate a gas flow in the form of a gas jet For this purpose, rather than a "mass flow", the velocity of sound at the nozzle tip is The key is to reach it.

The value of sound speed a - (kRT)"" (k, R; are constants) is proportional to (7) + zt However, the gas velocity increases proportionally to T when the mass flow is constant. Therefore, the sound velocity is reached at a carrying mass flow s2<1 at a high temperature T2>T, and the That is, the nozzle has a smaller mass flow at a temperature T than the mass flow at a lower temperature T. The flow allows space to be maintained in the nozzle.

However, even during active cleaning or processing times it is advantageous to heat the gas. Ga The nozzle cross section and operating pressure of the cleaning gas are mutually specific for the specific mode of action of the cleaning gas. and is configured for maximum gas supply. In this case, the adjustment area is Adjustment range in a simple manner by gas heating according to the invention, which is very narrowly limited can be expanded. This is done by extending the adjustment area downwards. Ru.

In metal melting processes for the heating of process gases, which may otherwise not be available. Any sufficient heat source can be used. Therefore, the process gas to be heated is melted. The temperature of this process gas before its introduction into the metal can depend on the ambient temperature. It is possible to pass it through a heat exchanger that heats it several hundred degrees higher. gas into molten metal 35% to 50% savings by heating the gas temperature to approximately 500°C during gas injection. It is possible to realize the promise.

Embodiments result from the features of claims 2 and 3.

The combination measures according to claim 4 are particularly advantageous.

Additionally, the method according to the invention eliminates the disadvantages that occur in foam flows. The resulting pressure fluctuations are used to check the minimum allowable process gas flow.

The invention utilizes well-detected pressure fluctuations in the inner tube to minimize gas consumption. It is based on the recognition that it can be used for

In a practical implementation of the method according to the invention, the pressure in the inner tube of the gas supply nozzle is A force sensor is attached.

This detects the pressure fluctuations caused by the formation and interruption of individual blows. .

The pressure fluctuations are strong enough that they can be detected and further processed as a signal. The signal represents a reliable pressure fluctuation, therefore the regulating valve for gas flow The gas flow starts from an initial value and decreases continuously until it exceeds a threshold pressure fluctuation. It can also be controlled so that the valve is opened by a predetermined value and the cycle begins. starts anew.

With this adjustment according to the invention, the minimum gas flow is determined by the all-determining parameter, i.e. The wear characteristic curve and temperature of the metallurgical vessel and the contents of the metallurgical vessel and mainly the gas introduced. Adjusted temperature and matched.

The device only additionally requires a pressure sensor and a frequency filter. The sensor is connected to a pressure supply tube, which may be filled with liquid, that receives pressure from the nozzle tube. If it is led to the sensor, it can be connected at any location.

In practical tests of the method of the invention, the gas flow is independent of each other in the ring gap and in the nozzle until just before an adverse effect occurs or is anticipated. . In this case, the inner nozzle at a volume flow smaller than 1.75"N/win is possible to maintain completely in free space unless the temperature of the introduced gas is increased. I found out that it wasn't. As expected, this limit value is caused by foam. can be detected based on pressure fluctuations.

Submission of translation of written amendment (Article 184-8 of the Patent Act) February 26, 1990- Commissioner of the Japan Patent Office Yoshi 1) Takeshi Moon 1. Indication of international dispatch PCT/DE8 B100464 2 Name of the invention Method 3 of minimizing process gas consumption in metallurgical processes, patent application Man Address: Federal Republic of Germany, Day 4000, Dünseldorf 1, Manne Suman woofer 2 Name: Mannesmann Akchengesellschaft 4, Agent: 107 Technical field The present invention provides a method in which a gas such as argon or oxygen or nitrogen is introduced into the molten metal and into the inner tube. The molten metal is blown into a feed pipe consisting of a concentric outer pipe and terminating below the liquid surface. The present invention relates to a method for minimizing the consumption of process gases in metallurgical processes.

゛゛　Background technology For example, from French Patent Application No. A401 453, the outlet end of the blow tube The introduction of a fluid medium for cooling is monitored and the relationship between pressure and supply time is It is known that this can be minimized by adjusting it to an appropriate value.

Furthermore, from British Patent Application Publication No. 1062591, the molten metal in the ladle is For processing, the gas introduced into the molten metal is preheated to a temperature not lower than 200°C. It is known to heat. On the one hand, this avoids casting defects such as cavities. On the other hand, this not only removes gases such as hydrogen, but also makes the molten metal relatively It can be influenced to accommodate large alloy compositions.

However, minimization of process gas consumption cannot be gleaned from these documents.

During the last few years, numerous applications of methods of the type mentioned at the outset have been devised. Against this Accordingly, the objective is to make suggestions for minimizing the consumption of main gas and cleaning gas. A study was conducted to show that the gas consumption in such a method is clearly This is because it is of critical importance to the economics of this method. Therefore, for example, “5 "teel Re5search 55 (1984)" Magazine Volume 12, Page 537- On page 579, the basics of nozzle construction for blowing gas into molten metal are scientifically explained. It has been investigated and for the practical implementation of such a method for gas introduction a minimum It is necessary to be able to adjust the area between the gas flow and the maximum gas flow. It was pointed out that Of course it must not be less than the minimum mass flow of gas, because This is because if the temperature drops below this level, the supply pipe or nozzle will become clogged. The configuration described in the above literature The rule is that the minimum body should be adjusted so that the velocity of sound is exactly adjusted as the discharge velocity in the exit cross section. It stipulates that the bulk flow must blow through the ring-shaped gap and the nozzle. to this The pressure is adjusted at the nozzle outlet to be greater than the static pressure of the molten steel in the molten metal bath. becomes possible. Blocking of the nozzle is therefore impossible.

international search report international search report S^　　　23467

Claims (1)

[Claims] 1) A gas such as argon or enzyme or nitrogen is placed into the molten metal and concentrically with the inner tube. The metal is blown into a feed pipe consisting of an outer pipe and terminating below the surface of the molten metal liquid. A method for reducing process gas consumption in metallurgical processes, in which the gas Process gases in metallurgical processes characterized by being heated before introduction How to minimize consumption. 2) The gas is heated to a temperature several hundred degrees higher than the ambient temperature. minimizing the consumption of process gas in the metallurgical process according to claim 1; How to make it. 3) Claim 1, characterized in that said gas is heated to a temperature of about 500°C. A method of minimizing process gas consumption in a metallurgical process as described in Section. 4) Additionally, pressure fluctuations of the gas are advantageously determined in the inner pipe of the supply pipe. This pressure fluctuation is then subjected to frequency filtering as a signal, during which the pressure The oscillatory component of the force fluctuations is filtered out and the signal representing the pressure fluctuations is minimized. A claim characterized in that it is used to control the gas flow with respect to the required amount. Minimize the consumption of process gases in the metallurgical processes described in paragraph 1. How to do it. 5) starting from an initial value, the gas flow is successively reduced to a threshold value; in which the gas flow is increased by a predetermined amount and this operation is reintroduced. Minimizing the consumption of process gases in the metallurgical process described in item 4 how to. 6) The frequency of the pressure fluctuation in the gas supply pipe was determined in a previous test. , characterized in that the frequency filtering is matched to the determined pressure fluctuation frequency. The process in the metallurgical process according to claim 4 or 5, How to minimize gas consumption. 7) The signal obtained during the frequency filtering is amplified, and the amplified signal is Any of claims 4 to 6, characterized in that an average value is formed. Minimizing the consumption of process gases in the metallurgical process according to any one of the preceding paragraphs. Method. 8) A pressure sensor that detects the gas pressure in the supply pipe leading into the molten metal; Vibration components are filtered and removed, and the average value of pressure fluctuations is used as a control variable for process gas. Claims 1 to 7, characterized in that: Consumption of process gases in the metallurgical process according to any one of paragraphs How to minimize.