U.S. patent application number 14/112839 was filed with the patent office on 2014-02-13 for device to inject solid material into a bath of liquid metal, and corresponding method.
This patent application is currently assigned to DANIELI & C. OFFICINE MECCANICHE SPA. The applicant listed for this patent is Marco Ansoldi, Alfredo Poloni. Invention is credited to Marco Ansoldi, Alfredo Poloni.
Application Number | 20140042676 14/112839 |
Document ID | / |
Family ID | 44554019 |
Filed Date | 2014-02-13 |
United States Patent
Application |
20140042676 |
Kind Code |
A1 |
Poloni; Alfredo ; et
al. |
February 13, 2014 |
DEVICE TO INJECT SOLID MATERIAL INTO A BATH OF LIQUID METAL, AND
CORRESPONDING METHOD
Abstract
Device and method for injecting solid material in particles,
powder or granulated form, of varying grain size. The device
comprises a tubular pipe which can be applied on a lateral wall of
a melting furnace so as to dispose its exit end inside the volume
of the melting furnace and above the meniscus of the liquid metal.
The device also comprises a chamber or tank to contain the solid
material and emitter means comprising valve means which can be
selectively opened for an opening time in the range of tenths of a
second, to introduce an impulsive jet of pre-compressed gas or air
which, in coordination with the opening of an exit valve which can
be selectively opened, disposed at one end of said pipe, determines
the emission of an impulsive flow of the solid material contained
in said chamber or tank, with high kinetic energy and quantity of
motion.
Inventors: |
Poloni; Alfredo; (Fogliano
di Redipuglia, IT) ; Ansoldi; Marco; (Udine,
IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Poloni; Alfredo
Ansoldi; Marco |
Fogliano di Redipuglia
Udine |
|
IT
IT |
|
|
Assignee: |
DANIELI & C. OFFICINE
MECCANICHE SPA
Buttrio
IT
|
Family ID: |
44554019 |
Appl. No.: |
14/112839 |
Filed: |
April 17, 2012 |
PCT Filed: |
April 17, 2012 |
PCT NO: |
PCT/IB2012/000753 |
371 Date: |
October 18, 2013 |
Current U.S.
Class: |
266/44 ;
266/216 |
Current CPC
Class: |
Y02P 10/20 20151101;
F27D 3/0032 20130101; B65G 53/42 20130101; Y02P 10/216 20151101;
F27D 3/18 20130101; C22B 9/103 20130101; C21C 5/5217 20130101 |
Class at
Publication: |
266/44 ;
266/216 |
International
Class: |
C22B 9/10 20060101
C22B009/10 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 18, 2011 |
IT |
UD2011A00060 |
Claims
1.-13. (canceled)
14. An injection device for injecting a discrete amount of solid
material in particle, powder or granulated form, comprising: a
melting furnace having walls defining a liquid metal retaining
area, a first pipe having a lower end, an upper end and mounted
through a lateral wall of the melting furnace wherein the lower end
of the first pipe is disposed inside the furnace and configured to
be above a meniscus of liquid metal contained within the liquid
metal retaining area, a chamber configured to store the solid
material and having an upper part and a lower end, an exit valve
connecting the upper end of the first pipe to a lower end of the
chamber wherein the exit valve is configured to be selectively
opened for a period between about 0.2 seconds and about 0.8
seconds, a second pipe connecting the upper part of the chamber to
introduce the solid material into the chamber, a third pipe
connecting to the upper part of the chamber to introduce a
pre-compressed fluid into the chamber, a fluid valve connecting the
third pipe to the upper part of the chamber wherein the fluid valve
is configured to be selectively opened for a period less than about
0.4 seconds, wherein by rapidly and sequentially opening the exit
valve and the fluid valve, the exit valve emits an impulsive flow
of the solid material into the furnace.
15. The injection device according to claim 14, wherein the
impulsive flow of the solid material is higher than about 4
m/s.
16. The injection device according to claim 15, wherein the
impulsive flow of the solid material is higher than about 8
m/s.
17. The injection device according to claim 16, wherein the
impulsive flow of the solid material is higher than about 9-10
m/s.
18. The injection device according to claim 14, wherein the opening
period of the fluid valve is less than about 0.3 seconds.
19. The injection device according to claim 18, wherein the opening
period of the fluid valve is less than about 0.2 seconds.
20. The method according to claim 14, wherein the pressure of the
pre-compressed fluid is higher than about 5 bar.
21. The method according to claim 20, wherein the pressure of the
pre-compressed fluid is higher than about 7 bar.
22. The method according to claim 21, wherein the pressure of the
pre-compressed fluid is higher than about 8-10 bar.
23. The method according to claim 14, wherein the flow rate of
material emitted is higher than about 2 kg/s.
24. The method according to claim 23, wherein the flow rate of
material emitted is higher than about 3 kg/s.
25. The method according to claim 24, wherein the flow rate of
material emitted is higher than about 4-5 kg/s.
26. The method according to claim 14, wherein the opening period of
the exit valve is between about 0.3 seconds and about 0.7
seconds.
27. The method according to claim 26, wherein the opening period of
the exit valve is between about 0.4 seconds and about 0.6
seconds.
28. The injection device according to claim 14, wherein the chamber
is aligned axially to the first pipe.
29. The injection device according to claim 14 wherein further
comprising an entering valve connecting the second pipe to the
upper part of the chamber.
30. The injection device according to claim 14, wherein the upper
part of the chamber directly connects to the second pipe so that
the solid material is directly introduced into the chamber at a
pressure between about 1 bar and about 2 bar.
31. A method for injecting a discrete amount of solid material in
particle, powder or granulated form, comprising mounting a first
pipe through a lateral wall of a melting furnace, wherein the
melting furnace has walls defining a liquid metal retaining area,
the first pipe has a lower end and an upper end, the the lower end
of the first pipe is disposed inside the furnace and configured to
be above a meniscus of liquid metal contained within the liquid
metal retaining area, connecting the upper end of the first pipe to
a lower end of a chamber via an exit valve, wherein the chamber is
configured to store the solid material and has an upper part, the
exit valve is configured to be selectively opened for a period
between about 0.2 seconds and about 0.8 seconds, connecting a
second pipe to the upper part of the chamber to introduce the solid
material into the chamber, connecting a third pipe to the upper
part of the chamber to introduce a pre-compressed fluid into the
chamber via a fluid valve, the fluid valve is configured to be
selectively opened for a period less than about 0.4 seconds, and by
rapidly and sequentially opening the exit valve and the fluid
valve, the exit valve emits an impulsive flow of the solid material
into the furnace.
32. The method according to claim 31 wherein further comprising a
filling step comprising disposing the chamber aligned axially to
the first pipe, connecting the second pipe to the upper part of the
chamber via a entering valve, closing the exit valve, opening the
entering valve to feed the solid material into the chamber, and
closing the entering valve when the solid material in the chamber
reaches its desired amount.
Description
FIELD OF THE INVENTION
[0001] The present invention concerns a device, and the
corresponding method, to inject solid material under the bath,
mostly in granular form, powder and/or particles, in order to
minimize the time taken for the material to pass from the device to
the bath, thus increasing the volume (weight) of the material
introduced, so as to increase efficiency and generate appropriate
and desired chemical reactions in a bath of liquid metal, or to add
additives to the liquid metal to improve its quality, or for other
reasons.
[0002] The present invention is mainly although not exclusively
applied in processes for melting metals in electric arc furnaces
(EAF) in order to improve the efficiency of such processes, to
improve the quality of the product obtained, to reduce melting
times, to increase the working life of the components that are
subject to wear, to increase the energy efficiency of the solids
introduced, given the same volume and/or efficiency, to reduce the
volumes introduced and hence the consumption thereof, with a
reduction in the purchasing costs, to reduce energy consumption,
and to obtain other advantages as described hereafter.
BACKGROUND OF THE INVENTION
[0003] Melting processes are known, which use electric arc furnaces
to melt metal materials of various types and origin, and to obtain
liquid metal to be sent to working processes downstream, such as
for example casting, rolling or other.
[0004] It is known that, during the melting process, as well as
providing electric energy to feed the electrodes, auxiliary devices
are normally used which perform various functions which are
complementary but extremely important to optimize the process and
to obtain a good quality final product.
[0005] For example it is known to use burners, oxygen lances and
solid material injectors, of varying types and function, to improve
the process conditions, reduce energy consumption, and limit wear
on the parts, in particular the ends of the electrodes, forming
foamy slag, and the refractory material that constitutes the hearth
and parts of the lateral walls.
[0006] For example it is known to inject or introduce carbonaceous
material into the bath of liquid metal, in powder or particles, in
order to promote the formation of foamy slag on the surface of the
bath, so as to increase the cover factor of the electric arc and
thus to reduce both wear on the electrodes and also energy
consumption.
[0007] In order to perform this function, the carbonaceous material
can be introduced into the bath together with the metal material to
be melted, for example mixed with it both in the case of a
continuous charge with a transporter, and also in the case of an
intermittent charge with baskets.
[0008] Alternatively, or in combination, the carbonaceous material
can be injected into the bath by means of suitable lances disposed
above, or even below, the upper level of the bath of liquid metal
(meniscus), so as to mix with the bath and allow to achieve
chemical reactions that promote the rapid development of the foamy
slag.
[0009] Examples of such solutions can be found in U.S. Pat. No.
6,614,831 and U.S. Pat. No. 4,110,107.
[0010] Other examples of injectors known in the state of the art
are shown in DE-C-927.113, U.S. Pat. No. 3,199,924, U.S. Pat. No.
3,239,278 and GB-A-792.192.
[0011] DE'113 describes an injector to inject solid material into a
furnace, which is mounted horizontally on the wall and,
substantially near its terminal end and outside the furnace, has a
magnet that regulates the quantity of material to be injected. This
solution in no way allows to obtain an injection deep into the
bath, keeping the injector outside and above the bath. Moreover,
with the regulation methods using the magnet, it is not possible to
obtain the emission speeds and energies required to obtain an
injection of the carbonaceous material deep into the bath of liquid
metal.
[0012] US'924 describes an injector to inject solid material
through a thin channel made on the wall of the furnace, which leads
into the bath of metal. The injection of the solid material
directly inside the bath does not allow to obtain an in-depth
distribution and determines a loss of efficiency and a delay in the
effect of the solid particles in the bath. Furthermore, to prevent
the material of the bath from rising inside the channel in the wall
of the furnace and into the injector, the pressure in the chamber
used for loading the carbonaceous material must be higher than the
pressure in the furnace, and this causes operational and management
complications.
[0013] US'278 also has a solution similar to US'924, with an
injector inserted into the furnace wall that leads out directly
inside the bath of liquid metal, with the same disadvantages as
described above.
[0014] GB'192 does not show an injector suitable to be applied to
the wall of an electric furnace for melting metal, but shows a tank
of solid material from which an adjustable quantity of material is
extracted.
[0015] It must also be considered that none of the documents
described above teaches to use a flow of air or other gas under
pressure, delivered in an impulsive manner (that is, with extremely
limited emission times, high speed and high energy) to inject sold
material from above the meniscus into deep into the bath.
[0016] It has been seen that the known methods described above for
the introduction of carbonaceous material, and in general other
solid materials inside the bath of liquid metal, are not
satisfactory from the perspective of increasing the energy
efficiency of the solids introduced and optimization of the results
sought.
[0017] Indeed it has been found that, where the injector is above
or inside the bath, the efficiency of the process is limited
because the carbonaceous powders or particles affect only the upper
layer, or in any case a limited layer, of the bath of liquid metal,
and only later do they affect the remaining part.
[0018] In these cases, the delayed and limited start of the
chemical reactions between the carbonaceous material and the bath
of liquid metal causes the foamy slag to form late, and therefore
the effect of covering the arc is contained, and hence the function
of preserving the electrodes from wear is not performed
efficiently, nor are energy savings achieved.
[0019] Another disadvantage is that this type of introduction
promotes a loss of the product, which burns and goes into the
fumes, without any advantage whatsoever for the process.
[0020] One purpose of the present invention is therefore to
increase the efficiency of introducing the solid material, mostly
in granular, powder and/or particle form, inside a bath of liquid
metal in a melting process, in order to maximize the volume or
weight of material introduced into the bath and the depth into the
same, with the advantage that when it is under the bath it reacts
with maximum yield.
[0021] Another purpose is to accelerate the start of the chemical
reactions, involving all the liquid metal of the bath so as to
maximize the final result of said reactions.
[0022] The Applicant has devised, tested and embodied the present
invention to overcome the shortcomings of the state of the art and
to obtain these and other purposes and advantages.
SUMMARY OF THE INVENTION
[0023] The present invention is set forth and characterized in the
independent claims, while the dependent claims describe other
characteristics of the invention or variants to the main inventive
idea.
[0024] According to the present invention, an injection device is
provided with high kinetic energy and high quantity of motion, to
inject a discrete amount of solid material in particles, powder or
granulated form, of varying grain size, for example comprised
between 0.15 and 15-20 mm, preferably between 5 and 8 mm. The
injection device comprises a tubular pipe which can be applied on a
lateral wall of a melting furnace so as to dispose its exit end
inside the volume of the melting furnace, with a desired
orientation with respect to the vertical, for example comprised
between 15 and 70 degrees, above the meniscus of the liquid metal
contained in the melting furnace.
[0025] The injection device is suitable to inject a predetermined
amount of solid material inside the bath of liquid metal,
substantially of any type in relation to the result to be obtained,
for example carbonaceous material, slag formers such as for example
lime, inert materials, slag, materials from demolitions, for
example fluff from shredders, powders from fume sleeve filters,
minerals of different types, etc.
[0026] According to the present invention, upstream of the tubular
pipe and associated with it, the injection device comprises a
chamber or tank to contain the solid material, and emitter means
able to be selectively connected to the chamber or tank, and
configured and suitable to produce an impulsive jet of
pre-compressed gaseous fluid which, in combination with an exit
valve that can be selectively opened, disposed at one end of the
pipe, determines the emission of an impulsive flow of the material
contained in the chamber or tank, with high kinetic energy and high
quantity of motion, such as to substantially reach the bottom of
the hearth, passing through the whole layer of slag and the bath of
liquid metal.
[0027] In a preferred solution, the impulsive jet of fluid consists
of a high pressure gas that is introduced, making it expand, inside
the chamber or tank containing the solid material, in a position
upstream of the exit valve, in temporal coordination with the
opening of the valve.
[0028] By doing this, that is, by substantially synchronizing the
introduction of the pressurized fluid, for example gas or air,
inside the device and the opening of the exit valve, and using
extremely limited opening times both of the valve that introduces
the pressurized gas inside the device where it expands, and also
the exit valve of the material from the device, a flow of material
is obtained with high kinetic energy and high quantity of motion,
which penetrates and passes through the layer of slag and liquid
metal and substantially reaches the bottom of the hearth.
[0029] In a preferential form of embodiment of the invention, a
speed to introduce the material is used which is more than 4 m/s,
advantageously more than 8 m/s, even more preferably more than 9-10
m/s.
[0030] In another preferential form of embodiment of the invention,
the opening time of the valve which introduces the pressurized gas
or air inside the tubular pipe of the device is less than 0.4
seconds, advantageously less than 0.3 seconds and even more
advantageously less than 0.2 seconds.
[0031] In a preferential form of embodiment, the pressure of the
gas introduced into the tubular pipe of the device to achieve the
emission of the impulsive flow of material is higher than 5 bar,
advantageously higher than 7 bar, even more advantageously higher
than 8-10 bar.
[0032] The flow rate of material emitted with every impulsive
emission cycle, in a preferential solution of the invention, is
advantageously higher than 2 kg/s, more advantageously higher than
3 kg/s, even more advantageously higher than 4-5 kg/s.
[0033] In another preferential solution, the opening time of the
exit valve of the material, associated with the end of the tubular
pipe of the device, is comprised between 0.2 and 0.8 seconds,
advantageously between 0.3 and 0.7 seconds, and even more
advantageously between 0.4 and 0.6 seconds.
[0034] According to the invention, the values indicated above can
be modified according to the operating conditions and the result to
be obtained.
[0035] For example, the values can be modified according to the
height of the liquid bath into which the material is injected,
which can vary according to the melting cycle under way. During and
at the end of the tapping step, for example, the level of the
liquid bath inside the furnace is very low, in the range of 200-400
mm, corresponding to the height of the "hot heel" that is always
maintained inside the furnace.
[0036] This situation, that is, the introduction of carbonaceous
material at the end of tapping, is very important for the
optimization of the process in that it is necessary that, when the
new melting cycle starts, a foamy slag is obtained with a height
and volume such as to guarantee the adequate cover of the electric
arc and the material of the furnace that is subject to wear.
[0037] In this situation, the introduction parameters, mainly speed
of flow, delivery rate and opening times of the valves, will be
suitably calibrated in order to ensure that the bottom of the
hearth is reached without ruining it by part of the jet of
materials, and that the latter are distributed to affect the whole
liquid bath.
[0038] If solid material is introduced during the melting process
and/or during refining, when the level of the bath can reach
800-1000 mm or more, the introduction parameters will be increased
compared to the previous case concerning the post-tapping step,
achieving the same advantages that the present invention allows to
obtain.
[0039] The geometric parameters of the device, for example length
and diameter of the tubular pipe, distance of the exit end from the
upper level of the bath, angle with respect to the vertical, etc.,
can also be modified both during the initial assembly step and also
during the introduction of the material into the bath.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] These and other characteristics of the present invention
will become apparent from the following description of a
preferential form of embodiment, given as a non-restrictive example
with reference to the attached drawings wherein:
[0041] FIG. 1 shows a device according to the present invention
applied on a wall of an electric furnace;
[0042] FIG. 2 is a plan view of an electric furnace where an
injection device according to FIG. 1 is applied;
[0043] FIG. 3 shows a device according to the present invention in
a variant of FIG. 1.
DETAILED DESCRIPTION OF A PREFERENTIAL FORM OF EMBODIMENT
[0044] With reference to the attached FIGS. 1 and 2, the reference
number 10 denotes in its entirety a device to inject solid material
in granular form, powder or particles, able to be applied to a
panel that constitutes part of the lateral wall of an electric
furnace 11, in the case shown here the electric type (EAF).
[0045] The electric furnace 11, during use, contains a bath of
liquid metal 12 with an upper surface 12a that can have a variable
height, normally from a minimum of about 200-400 mm, usually
corresponding to the "hot heel" that always remains inside the
furnace, even after tapping, to a maximum of about 800-1000 mm,
during the completion of the melting step and refining.
[0046] The liquid metal 12 can be covered by a layer of slag 13
normally having a height of about 200-500 mm when inactive.
[0047] The furnace 11 comprises a hearth 14 made of refractory
material, which defines the bottom of the hearth 14 and lower part
of the lateral walls, above which cooling panels 15 are disposed.
The whole thing is closed by a roof (not shown) through which the
electrodes (also not shown) are inserted: all this is substantially
known in the state of the art.
[0048] The device 10 is applied in cooperation with the cooling
panels 15 and substantially comprises a tubular pipe 16, having a
diameter that can vary between 60 and 150-200 mm, advantageously
between 80 and 120 mm, and a length that can vary between 800 and
1500 mm.
[0049] In the case shown as an example in FIG. 2, there is a single
device 10 applied on a respective panel 15, but it is clear that in
some forms of embodiment there may be more than one injection
device, disposed on the circumference at the proper technological
distances from each other.
[0050] A lower end 16a of the tubular pipe 16 is inside the
electric furnace 11, facing toward the liquid metal 12 for the
injection of the solid material, and disposed during use above the
level of the upper layer of slag 13, and an upper end 16b of the
tubular pipe 16 is associated, that is, rigidly fixed, to a first
exit valve 17, and in axis with the latter.
[0051] The first exit valve 17 selectively connects the tubular
pipe 16 with the lower end of a chamber or tank 18, able to contain
a predetermined and discrete quantity of material.
[0052] The tank 18 is elongated in shape and substantially aligned
axially with the tubular pipe 16.
[0053] In the form of embodiment shown in FIGS. 1 and 2, a second
valve 19 is associated with the upper end of the tank 18. Upstream,
a pipe 20 is associated with the second valve 19, usable to feed
the solid material in granules, powder or particles into the tank
18.
[0054] The pipe 20 can be any type, and is connected to an
accumulation tank, an automatic feed line or other apparatus to
store and feed the solid material in powder or granular form of the
type in question.
[0055] The pipe 20 can also be associated to deflector mechanisms
and/or multi-way valves for connection to a plurality of tanks,
each containing a material of a different type and grain size
according to the type of processing and/or the processing step in
progress.
[0056] A pipe 21 to introduce a pre-compressed fluid, in this case
pressurized gas, for example air or preferably another,
substantially inert gas, is provided in association with the device
10: the connection or coupling position of the introduction pipe 21
is provided advantageously in correspondence with the upper part of
the tank 18.
[0057] A valve 22, or third valve, is provided along the pipe 21 in
order to activate/de-activate the introduction of the
pre-compressed gas upstream of the tank 18, thus generating, in
coordination with the opening of the first valve or exit valve 17,
the emission of an impulsive flow of material, indicated in FIG. 2
by the letter F, under the thrust of the pre-compressed jet of gas,
which expands, toward the liquid metal 12.
[0058] In a coordinated manner, the tank has a zone 18a of
selective communication, thanks to the third valve 22, with the
pipe 21, that is, a zone 18a of the tank 18, in correspondence with
the coupling of the pipe 21, where the pre-compressed gas enters,
expanding, into the tank 18: for the functioning of the device 10
the zone 18a must preferably remain free of material.
[0059] The procedure for filling the tank 18 provides to close the
first exit valve 17, or exit valve, to open the second valve 19, or
entrance valve, and to activate a mechanism to feed the material
(not shown, and generally known) through the pipe 20. Once the tank
18 has been filled with the desired quantity of material, the
second valve 19 is closed and the device 10 is ready for the
introduction of the material inside the liquid bath when the valves
17 and 22 are subsequently opened. In particular, the material is
introduced toward the liquid metal 12 by opening the first exit
valve 17 and then, in rapid sequence, the third valve 22, to allow
the impulsive jet of pre-compressed gas to expand inside the tank
18. The impulsive jet of pre-compressed gas is mixed substantially
instantaneously with the solid material in the tank 18 and draws it
through the tubular pipe 16, obtaining the emission of the
impulsive flow F of material contained in the tank 18 with high
kinetic energy and high quantity of motion through the tubular pipe
16 toward the liquid metal 12.
[0060] Depending on the type of material, the processing
conditions, the result to be obtained, the quantity of liquid metal
12 inside the furnace 11, the position and structure of the device
10, the operating parameters of the device 10 can be regulated and
varied to obtain the best functionality, even during the course of
the introduction step itself.
[0061] The present parameters, preferential but not binding or
restrictive, were tested by Applicant for a procedure to introduce
carbonaceous material used to activate the formation of foamy slag
in a step after tapping a quantity of liquid metal from the furnace
10.
[0062] To obtain an introduction speed of the material higher than
9-10 m/s, which has proved itself to be advantageous to allow the
material to reach the bottom of the hearth 14 and allow an
effective propagation of the material to a great quantity of metal,
the third valve 22 was opened for a time of less than 0.2
seconds.
[0063] The pressure of the pre-compressed gas introduced from the
pipe 21 inside the tubular pipe 16 of the device 10 to achieve the
emission of the impulsive flow F of material was higher than 8
bar.
[0064] The flow rate of material emitted with every impulsive cycle
was higher than 4.5 kg/s, while the first exit valve 17 for the
material was opened for between 0.4 and 0.6 seconds. The overall
cycle for the impulsive flow F of material was less than 1
second.
[0065] The flow rate of material injected into the liquid bath was
about 5-6 kg/s, while the flow rate of the pressurized gas was
about 40-70 l/s.
[0066] Using these values, with an average grain size of the
carbonaceous material about 2-4 mm, the time taken to pass through
the whole height of the liquid bath was about 0.1 sec, thus
obtaining the result that all the carbonaceous material passed
through the layer of slag 13 above and the whole thickness of
liquid metal 12 without dispersing or creating flashes or other
losses during the passage.
[0067] In this way, an extremely high percentage of the
carbonaceous material injected was able to react substantially
immediately with the liquid metal 12, quickly creating the
conditions for the formation of a large volume of foamy slag,
giving advantages to the processing conditions for re-starting a
new casting cycle.
[0068] The above parameters can be modified in the case of
different materials, and/or different processing conditions, but
shall in any case come within the ranges indicated in the present
description.
[0069] FIG. 3 shows another form of embodiment of an injection
device 110. In this figure, the same numbers are used to refer to
components identical or corresponding to those shown in FIG. 1.
[0070] The device 110 shown in FIG. 3 does not have the second
introduction valve 19 to delivery the material, and the solid
carbonaceous material is accumulated in the tank 18, upstream of
the pipe 16, directly through the pipe 20 connected to an external
silo (not shown), at a relatively low constant pressure, for
example in the range of 1-2 bar. When the tank 18 is full, the
device 110 is ready for the injection, at high speed and high
energy.
[0071] When the valve 22 for the air or other gas is opened and the
introduction of the pressurized gas is activated and, in
coordination, the exit valve 17 is opened, in the way and with the
times as described above, the material in the tank 18 is shot
through the pipe 16 into the liquid metal 12 at extremely high
speed to obtain a high penetrating energy. As already described,
the pressure used for the expulsion is more than 5 bar,
advantageously more than 7 bar, even more advantageously more than
8-10 bar, and is therefore much higher than the pressure at which
the material is introduced inside the tank 18; thanks to the
difference between these two pressures, during the expulsion, the
introduction of material into the tank 18 is blocked. When the
introduction of the gas is finished, the tank 18 is automatically
refilled and is ready for a new cycle to introduce material into
the bath.
[0072] This variant allows to obtain a smaller device than the
device in FIG. 1, therefore having less weight, so as to be moved
manually, without having recourse to cranes or other devices for
mechanical movement.
[0073] It is clear that modifications and/or additions of parts may
be made to the device as described heretofore, without departing
from the field and scope of the present invention.
* * * * *