JPH02152819A - Clogging detecting method in mixing and carrying of powder - Google Patents

Abstract

PURPOSE:To conduct the detection rapidly and certainly by determining the pressure deviation or pressure changing rate of each part in mixing and carrying of powder in a hot metal preliminary treatment to check the pressure balance fluctuation and detecting a clogging by the pressure balance fluctuation and the cutting amount fluctuation. CONSTITUTION:The pressures in a reservoir tank 11, a carrying line 16A, a combined pipe 31, and a lance part 4 are detected by pressure sensors 11a, 14a, 32, 43, respectively, and inputted to a direct digital control unit (DDC) 6. The DDC 6 calculates the pressure changing rate or pressure deviation from them. On the other hand, the weight or cutting amount of a powder is inputted from a road cell 18 to the DDC 6. The DDC 6 detects a clogging of the carrying system based on the pressure changing rate or pressure deviation and the fluctuation of the powder cutting amount. According to such constitution, the clogging start can be rapidly and certainly detected.

Description

[Detailed Description of the Invention] [Industrial Applicability] The present invention is applicable to hot metal pretreatment, secondary smelting equipment, etc.
A unique powder material used as a reactant is used for scouring molten metals such as molten steel.
The present invention relates to a method for detecting powder clogging on a protrusion in a powder mixing/transporting device in which the mixing ratio can be freely adjusted using a post-mix method.

[Prior Art] Conventionally, mixed powder as a reactant has been injected into molten metal in hot metal pretreatment and secondary smelting equipment, but this method has been disclosed in Japanese Utility Model Publication No. 57-21032 and Japanese Patent Application Laid-Open No. 1983-1989. 67
The conventional blowing technology disclosed in Publication No. 4.22 is to store mixed powder, which is a mixture of multiple powder materials at a predetermined mixing ratio, in a blowing tank, and to adjust the pressure inside the tank to a predetermined pressure. The powder was controlled and blown from the tip of the lance at a predetermined powder blowing speed.

However, as is well known, in the scouring operation, when refining molten metal to a desired purity, it is necessary to remove a plurality of impurities. For example, in hot metal pretreatment, it is usually necessary to remove silicon, phosphorus, and sulfur components from the hot metal, and the allowable contents of silicon, phosphorus, and sulfur components vary depending on the properties of the steel to be manufactured. Since they are different, it was necessary to change the components of the mixed powder to be blown in according to the components to be removed, and also to change the mixing ratio of flux, the amount of blown in, etc. according to the target content. For this reason, in the above-mentioned conventional technology, it is necessary to replace the powder in the blowing tank each time with one having a different component ratio (mixing ratio).

On the other hand, the present applicant had previously applied for patent application No. 62-10075.
In No. 5, the component ratio of multiple powder materials of the reactant is mixed during the transportation process of each powder material using a post-mix method, and the mixing ratio can be freely adjusted as necessary, making it possible to exchange powders. We proposed a powder mixing/transporting method and device that eliminates the need for work and improves workability.

FIG. 8 is an explanatory diagram of the conventional powder mixing/transporting method and device. 11 is a reservoir tank that accommodates one powder material; 12 is a rotary feeder that feeds a predetermined amount of the powder material by driving a motor 12a; 21. 23 is a pressure control valve that controls the pressure inside the tank 11 through the pressure line 13 by an actuator 22; 23 is a carrier gas pressure control valve that controls the supply gas pressure of carrier gas supply line 4 by an actuator 24; 15 is a rotary feeder 12; The cut out powder material is transported to the gas supply line 1.
A powder/gas mixer that uses the gas supplied from 4 as a carrier gas in a fluidized state; 16 is a conveyance line for the powder/gas; 3;
1 is a confluence pipe that connects the transport line I6 and other transport lines 16' and mixes a plurality of powder materials, 41 is a supply line that supplies the mixed powder to the lance section, and 42 is the lance section. These are the injection nozzles that make up the structure. Reservoir tank 11
The internal pressure forces the powder into the rotary feeder 12 to ensure cutting. The amount of cutout at this time is feedback controlled by controlling the motor 12a to increase or decrease the number of revolutions of the rotary feeder I2 so that the amount is always a predetermined set amount by weight detection or the like.

[Problems to be Solved by the Invention] However, the above-mentioned conventional powder mixing/transporting method and apparatus using the post-mix method is good when the powder is transported without clogging the piping, but
Some factors, such as reservoir tank 11. Merging pipe 31
．． When the pressure balance of the mixed powder supply line 41 of the lance part goes out of order, when the powder is being transported at a constant solid-air ratio, the flow rate of the carrier gas suddenly decreases, or when the amount of powder cut out If there is a sudden increase in powder, the powder will be transferred to the transport pipes (transport line 1G, mixed powder supply line 41).
It accumulates inside the pipes and causes pipe blockages.

There are many other factors like this, and depending on the situation, the duration may be short or long, and the reality is that the duration is not constant. However, in FIG. 8, for example, if the conveyance line 16 starts to be blocked, the powder will not be cut out according to the set value of the cutout amount (less than the set value will be cut out).
, the feedback control automatically moves in the direction of increasing the amount of cut-out, that is, increases the rotation of the rotary feeder 12 to supply more powder, which leads to more and more piping clogging. .

Therefore, in order to prevent this, it has been a conventional problem to detect piping blockage early and reliably. The present invention was devised to solve the above-mentioned problems, and in order to avoid troubles caused by pipe blockage in a post-mix method and apparatus for transporting and mixing powder, the present invention promptly and reliably starts the pipe blockage. The purpose of the present invention is to provide a method for detecting occlusion.

[Means for Solving the Problems] In order to achieve the above object, the method for detecting occlusion in transporting and mixing powder according to the present invention has the following structure: Each stored powder is cut out into each transport pipe connected to the container and pneumatically transported with a carrier gas, the pneumatic powder is mixed at the confluence of the transport pipes, and the mixed powder is transferred to a lance downstream of the confluence. When mixing and transporting the powder that is blown into the molten metal from the tip of the part, first, the pressure of the pressure vessel, the confluence of the transport pipe 1, and the lance part of the powder transport system is detected, and the pressure deviation or pressure change between these parts is detected. Next, check the pressure balance fluctuation from the pressure vessel to the injection point at the tip of the lance from the pressure deviation or pressure change rate, and compare this pressure balance fluctuation with the fluctuation in the amount of powder cut out from the pressure vessel. The present invention is characterized in that blockage of the powder conveying system is also detected.

[In the action copost mix type powder mixing and conveying device,
When powder is being mixed and transported normally, the pressure decreases and balances in the order of pressure vessel, confluence pipe, and lance, but if a blockage occurs in each transport pipe, the pressure on the upstream side As the pressure approaches the supply pressure value of the pressurized gas, it becomes impossible to convey the powder, and the number of cutting claws for the powder stored in the pressure vessel decreases to zero. The present invention detects the pressure at each predetermined part, determines the pressure deviation or pressure change rate between each part from the detected pressure, checks the pressure balance fluctuation, and checks this and the fluctuation of the powder cutting claw. Detects the beginning of blockage.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a configuration diagram showing an example of a post-mix type powder conveying/mixing apparatus to which a blockage detection method according to an embodiment of the present invention is applied. The same members as those in the prior art shown in FIG. 8 are given the same numbers to simplify the explanation. This configuration example is based on a case where two types of powders A and B are transported and mixed, and a transport section lΔ for powder A, a transport section II3 for powder B, and a transport section I
A valve unit 2A that supplies pressurized gas to A, and a transport section I! a valve unit 2I3 that supplies pressurized gas to 3;
A mixing unit 3 that mixes the powder transported from each transport unit IA, lr3, a lance unit 4 that injects the mixed powder into the hot metal in the container 5, and a lance unit 4 that collectively controls each part to mix the powder. DDC (Dire
ct Digital Control) unit 6, etc.

Since the transport sections IA and IB are constructed in substantially the same manner, the only difference being the quality of the powder material to be accommodated, the structure can be set for one of the transport sections IA. 11 is a reservoir tank which is a pressure vessel, 12 is a rotary feeder for cutting out powder, +2
a is the rotary drive motor, IB is the pressure line, 1
4 is a transport waste supply line, 15 is a powder/gas mixer, 1
6Δ is a powder/gas conveyance line. Reference numeral 17 denotes a powder supply cutoff valve that is opened and closed by an actuator 17a, and is closed when the system is stopped or the like. lla is a pressure sensor for the internal pressure of tank 1, 14a is a pressure sensor for the pressure of the gas supplied to the conveyance line +6A, 18 is a weight sensor composed of a load cell, etc., for measuring the weight of powder and cut-out insects in tank 1, 18a is a signal generator for transmitting the detection signal to the DDC unit 6, and the detection signals from these sensors are input to the DDC unit 6, which will be described later. 19 is 1'
l) The DC unit 6 monitors the remaining m of powder material using the weight sensor 18, and when the amount is less than a predetermined amount, the powder material 1'-1-supply control valve supplies new powder material to the tank 11. be.

Since the valve units 1-2A and 2B have the same configuration, the configuration of one of them will be described. Valve unit 2
A has a gas flow control valve 25, a pressure control valve 21, and a carrier gas control valve 23.

The gas flow control valve 25 controls the flow of pressure gas introduced into the valve unit 2A from the pressure gas supply source of the circuit.

The control of the gas flow rate control valve 25 at this time is DI) C
The unit 6 manually detects the detection signal of the gas flow rate sensor 26. The pressure control valve 21 is disposed within the pressure line 13, and adjusts the pressure gas supplied to the powder material paste reservoir tank I+ to adjust the pressure within the tank 11. on the other hand,
The carrier gas control valve 23 is disposed in the carrier gas supply line 14, and controls the adult of the carrier gas introduced into the carrier line t6A, as well as the gas flow rate and gas pressure flowing through the carrier line 16A. are doing.

The mixing section 3 is equipped with a merging pipe 31, and the conveyance line +6A of the conveyance section IA and the conveyance line 16B of the conveyance section IB are merged and mixed, and the mixed powder is not sent to the mixed powder supply line 41.

32 is a confluence point pressure sensor that detects the pressure at the confluence point in this confluence pipe 31, and its detection signal is sent to the DDC unit 6.
is input.

The lance section 4 includes an injection nozzle 42 and is connected to the above-mentioned mixed powder supply line 41. 43 is a pressure sensor that detects the pressure of the mixed powder supply line 41 in order to detect the back pressure of the lance section, and its detection signal is manually input to the DDC unit 6.

FIG. 2 is a block diagram showing the circuit configuration of the DDC unit. The DDC unit 6 is composed of a computer. 61 is a processor (CPU), 62 is r (AM
63 is a ROM that stores programs including control procedures and control data; 64 is a pattern table memory; 65
66 is a tarok oscillator that supplies the clock required by the CPU 61; 66 is an input unit that is equipped with an A/D converter and converts the analog inputs from the various sensors and signal generators mentioned above into digital signals, and inputs the digital signals to the CPU 61; 67; is an output unit that outputs control signals to actuators such as feeder drive motors and various control valves.

Various powder supply patterns and gas pressure change patterns are preset in the no-turntable memory 64. The pattern table memory 64 can be set in the flOM 63 or lAM 62, or can be an external memory such as a floppy disk or hard disk.

With the configuration described below, the powder mixing and conveying device of this embodiment has the following functions necessary for this embodiment.

(+) The pressure of the reservoir tank can be measured.

(2) The weight of powder inside the tank can be measured. Thereby, the amount of powder cut out and the powder flow m can be determined.

(3) The amount of powder cut out can be changed depending on the rotation speed of the rotary feeder.

(4) The powder cut out using a carrier gas is transported by a carrier line, and the carrier gas supply pressure can be measured.

(5) It has a confluence pipe that mixes the plurality of powders transported,
Confluence pipe pressure can be measured.

(6) It is connected to the lance part by the mixed powder supply line, and the mixed powder inone excidine is produced into the hot metal.

(7) Back pressure on the lance part can be increased to 41 mm in total.

(8) Built-in computer, capable of judgment, calculation, automatic control, etc.

An example of a method for detecting powder clogging (occlusion) applied to a post-mix type powder mixing/transporting device having the above-mentioned functions will be described below. FIG. 3 is a flowchart showing one embodiment. This embodiment is realized by the internal control procedure (control algorithm) of the DDC unit 6 shown in FIG. It is possible to detect the beginning of blockage of pipes during powder transport or supply by measuring the pressure at each part and checking for changes in the balance of each part. That is, as shown in FIG. 4, the pressure normally decreases in the order of reservoir tank, confluence pipe, and nozzle, but if the conveyance line +6A in FIG. The pressure in the reservoir tank becomes abnormally high (approaching the carrier gas supply pressure value) and becomes higher than other reservoir tanks, causing the pressure balance to become out of order. Furthermore, when the mixed powder supply line 41 begins to become clogged, the pressure in the confluence pipe 31 begins to rise, causing the reservoir tank 11 to become clogged.
As the pressure approaches the pressure value of 11. ...and the confluence pipe 31 have the same pressure value (
is equal to the carrier gas supply pressure value). In addition to these phenomena, when the pipe is blocked, it is natural that the powder to be transported cannot be supplied, so the amount of powder cut out from the reservoir tank 11 decreases as the rotary feeder 12 rotates. The phenomenon of snow zero occurs in a short period of time. Therefore, in this embodiment, the above-mentioned pressure balance and the fluctuation phenomenon of the powder cutting claws were investigated by the DDC unit 6 in Fig. 1.
Timely judgment is made inside the system to detect powder blockage in various parts.

In FIG. 3, the blockage detection method of this embodiment is as follows:
The powder flow rate vs. pressure characteristics shown in Figure 4 are memorized, and based on these characteristic values and measured values, a pressure deviation check or a pressure change rate check can be performed in a timely manner to detect the onset of pipe blockage and issue an alarm. emanate.

The flow m vs. pressure characteristics in each part of the device illustrated in FIG. 4 are as follows:
Although the characteristics change due to changes in the brand of powder material or process changes, the learning function is used at certain intervals within the DDC unit based on the initial design conditions to adapt the relationship between the powder flow rate and pressure at each part to the actual situation. Correct it as follows. The details are omitted because they are not particularly relevant to the present invention, but the judgment that the powder injection is normal and has reached a steady state, the zumbling method and calculation method of the operational data (for example, the number of zumbling points and the interval,
This can be corrected by determining an average processing method, etc., and performing signal processing.

The pressure deviation check mentioned above refers to the measured value for the powder flow mP at the time of pressure measurement (
Determine whether the pressure deviation (ΔP or ΔP1') calculated from the normal powder flow rate vs. pressure characteristic graph 8 obtained from the learning function and the learning function is within the normal fluctuation range B or C. However, if it exceeds the limit, it is determined that there is an abnormality and a warning is issued. In addition, pressure change rate check means that even if the pressure deviation is within normal fluctuation ranges B and C, the time (i
'), the powder flow rate changes to F2-F3 and the pressure changes to l), -4p3, the rate of pressure change (
Find PP, ) / ((F'3-F',)・T),
It is determined whether this is within the normal fluctuation range of the rate of pressure change, and if it is exceeded, it is determined that there is an abnormality and an alarm is issued.

Next, determine in what part these alarms occurred, and then in series, determine the rise in the pressure horn and the decreasing trend in the amount of powder cut out (powder flow rate) in the part where the alarm occurred. If the determination is No, it is assumed that the blockage has been avoided due to a temporary phenomenon, and the current detection operation is terminated.If the determination is YlεS, the blockage starting point is specified according to each part, and an alarm is displayed.

This embodiment predicts a pipe clogging phenomenon as described below.

Below, a method for automatically avoiding pipe blockage when the pipe blockage alarm occurs will be described. 6th
The figure is a flowchart showing an example of the avoidance method. This method is realized by the control procedure included in the DDC unit 6 shown in FIG.

The method of avoiding pipe blockage according to this embodiment is carried out as follows depending on the location where the blockage starts.

(+) In the case of blockage of the nozzle 42, a state (pause) is automatically created in which powder blowing is temporarily stopped, and the nozzle is removed from the container. As a result, powder injection is automatically stopped according to the immersion depth of the nozzle, and the nozzle is in a state in which only the transported waste is injected in the atmosphere, thereby avoiding clogging of the nozzle portion. If blockage can be avoided using the nozzle back pressure sensor (discrimination is made from the pressure characteristic value at powder flow rate of 0), injection is restarted again. Do these automatically.

(2) In the case of blockage of the mixed powder supply line 41, the same control as in the case of blockage of the nozzle part is performed, but the judgment to avoid blockage is based on the powder flow rate versus pressure characteristic by the confluence pipe part pressure sensor.

(3) In the case of blockage of the transport line +6A, 16B, first increase the gas ffi S V of the pressurized gas supply line to the relevant transport line's reservoir tank by α% (α has an appropriate value depending on the equipment). At the same time as issuing a setting value change command to the gas flow m control system (valve unit), the powder flow rate S
In the rotary feeder control system (motor) that controls V,
Issued β% powder nail reduction command 4゛. This state is "i",
(Timer) Continue for a long time, and perform another pipe blockage W $11 depending on the reservoir tank pressure vs. powder flow rate characteristics. To avoid piping blockage, the commands output to the gas flow m control system and powder flow control system (rotary feeder control system) are returned to their original state (in a ramp) after the 'r (timer) elapses, and powder injection continues. Keru.

However, if the pipe blockage cannot be avoided, a command is issued to further increase the gas m by α% and reduce the powder tIT'Lm by β%, and continues for 'r, (timer) to make a judgment to avoid the pipe blockage. In the case of avoidance, as above, TI'+'ry
’ (timer), return to the original position (in a ramp shape) and continue powder blowing.

If the pipe blockage cannot be avoided even with this, 1゛+'r
After t (timer), the powder flow M in the normal reservoir tank with no piping blockage is further uniformly reduced by γ%, and the situation is observed during T3 (timer). If you can avoid the pipe blockage by doing this, put it back together by doing the reverse operation. That is, after 'r3' (timer) has elapsed, the normal powder flow rate of the reservoir tank is restored (in a ramp), and then 'r t'
+ After 'I゛p' (timer) elapses (in a ramp shape),
The amount of waste in the pressurized waste supply line, which was blocked, is restored to its original level, and the powder flow rate is also restored to its original level.

If the pipe blockage cannot be avoided using the algorithm for avoiding pipe blockage using the method described in (1) and (2) above, the same measures as in (1) and (2) are automatically taken. In other words, shift to the stop F processing state during powder blowing. If the pipe blockage cannot be avoided even with this, the system will switch to a complete shutdown.

FIG. 7 is a block diagram schematically showing another post-mix type mixing/transporting device for mixing and transporting four types of powder materials. This configuration example is applied to hot metal pretreatment during the refining process, and the main configuration is the configuration shown in Figure 1 expanded to mix and transport four types of powder materials A and BCI).
Give the same part number and explain it (the above is omitted. However,
As is well known, in hot metal pretreatment, Tobeed Car 7
The hot metal transported is subjected to desiliconization, dephosphorization, and desulfurization treatments. In addition, dust (F
ed, Fe203) and lime are used, and the reactants for dephosphorization include 'bipod dust, in addition to lime71; talstone,
Soda ash is used, and lime and soda ash are used as reaction agents for removal (LC), so dust, lime, fluorspar,
Each piece of soda ash is stored in each reservoir tank 11 as a powder material.

In the figure, 8 is a control panel that provides data and control commands such as pattern control to the DDC unit 6. Parameters (α, β1TT,', Tt, T,
', 7. T3. Although T3') has an appropriate value depending on the powder properties and equipment configuration, an example of the value in the case of an apparatus using four brands of powder, which is not shown in FIG. 7, will be given below.

(Example) α=30. β-25. T,=60secT+'
=60sec, 'I'2=Tt' =60sec.

7=10. T, = T3' = 60 sec In the above embodiment, the pressure deviation check and pressure change rate check are as follows:
The object of the present invention can be fully achieved by implementing only one of them, or by implementing both. In this way, the present invention can be applied in various ways and can take various embodiments in accordance with its gist.

[Effects of the Invention] As is clear from the above explanation, according to the blockage detection method for mixing and transporting powder of the present invention, a post-mix method is adopted for mixing and transporting powder, and the mixing ratio,
The degree of freedom in selecting brands, etc. has been dramatically improved, making it possible to quickly respond to piping blockage problems, which has the effect of improving the equipment operating rate by a large 1+. Furthermore, when the powder mixing and conveying device to which the present invention is applied is used for preliminary treatment of hot metal for the purpose of refining, it is possible to perform desiliconization, dephosphorization, and desulfurization processes in one process without any equipment trouble. , which dramatically improves the workability and operation rate of hot metal pretreatment.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of a powder mixing/conveying device to which a blockage detection method according to an embodiment of the present invention is applied, and Fig. 2 is a diagram showing an example of a powder mixing/conveying device to which a blockage detection method according to an embodiment of the present invention is applied.
A block diagram showing the circuit configuration of the C unit, Fig. 3 is a time chart showing an example of a powder blockage detection method, Fig. 4 is a powder tIlf, quantity vs. pressure characteristic diagram, and Fig. 5 is a pressure deviation check. Fig. 6 is a flowchart showing an example of a method for avoiding powder clogging, Fig. 7 is a configuration diagram of another powder mixing/transporting device, and Fig. 8 is a conventional FIG. 2 is an explanatory diagram of a powder mixing/transporting method and apparatus. 4. Lance part, 6. DDC unit, 11. Reservoir tank, 12. Roch feeder, +6A. 1613... Conveyance line, 31 Merging pipe, 41... Kelp powder supply line, 42... Injection nozzle.

Claims (1)

[Claims] (1) While pressurizing multiple pressure vessels containing different powders, each stored powder is cut out into each transport pipe connected to each pressure vessel and pneumatically transported with a carrier gas, and the confluence of the transport pipes is When mixing and conveying the powder, the mixed powder is mixed and conveyed into the molten metal from the tip of the lance part on the downstream side of the confluence point, first, the pressure vessel of the powder conveyance system, the transport pipe, While detecting the pressure at the confluence point and the lance part, find the pressure deviation or pressure change rate between them, and then calculate the pressure balance fluctuation from the pressure vessel to the injection point at the tip of the lance part from the pressure deviation or pressure change rate. A blockage detection method in powder mixing and conveyance, characterized in that blockage in the powder conveyance system is detected based on the pressure balance fluctuation and the change in the amount of powder cut out from the pressure vessel.