CA1069160A - Arc furnace fumes control system - Google Patents
Arc furnace fumes control systemInfo
- Publication number
- CA1069160A CA1069160A CA268,490A CA268490A CA1069160A CA 1069160 A CA1069160 A CA 1069160A CA 268490 A CA268490 A CA 268490A CA 1069160 A CA1069160 A CA 1069160A
- Authority
- CA
- Canada
- Prior art keywords
- charging
- fumes
- duct
- exhaust
- mouth
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000003517 fume Substances 0.000 title claims abstract description 67
- 238000007600 charging Methods 0.000 claims abstract description 69
- 230000033001 locomotion Effects 0.000 claims abstract description 17
- 238000002844 melting Methods 0.000 claims abstract description 17
- 230000008018 melting Effects 0.000 claims abstract description 17
- 238000010079 rubber tapping Methods 0.000 claims abstract description 11
- 238000010891 electric arc Methods 0.000 claims abstract description 4
- 230000008878 coupling Effects 0.000 claims description 9
- 238000010168 coupling process Methods 0.000 claims description 9
- 238000005859 coupling reaction Methods 0.000 claims description 9
- 230000008093 supporting effect Effects 0.000 claims description 7
- 239000000428 dust Substances 0.000 claims description 6
- 238000001816 cooling Methods 0.000 claims 1
- 239000002893 slag Substances 0.000 claims 1
- 239000003638 chemical reducing agent Substances 0.000 description 6
- 238000001914 filtration Methods 0.000 description 5
- 239000000543 intermediate Substances 0.000 description 4
- 239000007789 gas Substances 0.000 description 3
- 210000001364 upper extremity Anatomy 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 210000003141 lower extremity Anatomy 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000013011 mating Effects 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000002939 deleterious effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000013618 particulate matter Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000029058 respiratory gaseous exchange Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Landscapes
- Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
- Vertical, Hearth, Or Arc Furnaces (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An exhaust system for use with an electric arc melting furnace having a crucible and an upwardly directed mouth covered by a roof, and a device coupled to the roof for projecting it upwardly along an axis and pivotally about the axis to a position out of registry with the mouth for providing access for charging the furnace, and a device for tilting the furnace for tapping. The main fumes exhaust duct is coaxial with the tilt axis of the furnace at the point where the furnace exhaust system is coupled to the main fumes exhaust duct. The furnace exhaust system is coupled to the main duct by a swivel which allows the furnace system to remain coupled to the main duct during tapping. The furnace exhaust system is in the form of a column and is attached to the crucible for tilting movement therewith. The charging hood is movably supported upon the exhaust system column. The charging hood pivots in a horizontal plane into and out of its use position in close overlying relationship to the furnace mouth.
An exhaust system for use with an electric arc melting furnace having a crucible and an upwardly directed mouth covered by a roof, and a device coupled to the roof for projecting it upwardly along an axis and pivotally about the axis to a position out of registry with the mouth for providing access for charging the furnace, and a device for tilting the furnace for tapping. The main fumes exhaust duct is coaxial with the tilt axis of the furnace at the point where the furnace exhaust system is coupled to the main fumes exhaust duct. The furnace exhaust system is coupled to the main duct by a swivel which allows the furnace system to remain coupled to the main duct during tapping. The furnace exhaust system is in the form of a column and is attached to the crucible for tilting movement therewith. The charging hood is movably supported upon the exhaust system column. The charging hood pivots in a horizontal plane into and out of its use position in close overlying relationship to the furnace mouth.
Description
91~0 ;
This application discloses an improvement over the invention disclosed in co-pending Canadian Patent Application Serial No. 246-933, filed March 2, 1976, titled "Arc Furnace Fumes Control System" and assigned to the same assignee as the present invention.
In accordance with one aspect of the present invention, there is provided in a fumes control system for an electric arc furnace comprising a crucible providing an upwardly directed mouth, a roof covering said mouth, said roof being movable into an opening position away from said mouth, a plurality of arc electrodes extending downwardly through said roof, said crucible having at least one pouring spout opening therein and being tilt-able for tapping, said control system comprising exhaust means, first hood means for collecting fumes generated during furnace operations from said roof, said first hood means being movable with said roof to expose said mouth, the improvement comprising charging hood means for movement into a use position in close overlying relationship with said mouth when said first hood means and said roof are moved away from said mouth, said charging hood means having an opening therein through which said crucible is charged, said charging hood means also having a storage position away from said mouth, a columnar exhaust ductj means for supporting said columnar exhaust duct upon said crucible, said columnar exhaust duct comprising upper, intermediate and lower portions, said exhaust means being flexibly attached to said lower portion to allow said exhaust duct to tilt with said crucible, first conduit means for coupling said first hood means to said upper portion when said roof is covering said mouth, said intermediate portion including means for supporting said charging hood means from said columnar exhaust duct for movement between said storage and use positions and ~or coupling said charging hood means to said exhaust duct when said charging hood means is in said use position.
In accordance with another aspect of the invention, there is provided in a funes exhaust system for use with a furnace having a crucible with an upwardly directed mouth, a roof for covering said mouth during melting operations in said furnace, and means for projecting said ' ~ , , ,, '' : ' ' .. ... .. . .
10691~;0 ; roof vertically upwardly along an axis and pivotally about said axis to a position out of registry with said mouth for providing access thereto for charging said furnace, means for tilting said furnace for tapping, said fumes exhaust system comprising exhaust means and first hood means movable with said roof to a position out of registry with said mouth, the improvement comprising charging hood means movable between a use position in close overlying relationship with said mouth when said roof is moved to a position out of registry with said mouth and a storage position remote from said mouth, said charging hood means having a top - 10 with an opening therein for passage of a charging bucket therethrough` when said charging hood means is in overlying relationship with said mouth, said charging hood means having means therein disposed to provide air movement past said mouth, and into said exhaust means for exhausting fumes and dust generated during charging of said furnace, a columnar exhaust duct, means for supporting said columnar duct upon said crucible for tilting movement therewith, said columnar duct having upper, inter-mediate and lower portions, means for flexibly coupling said lower portion to said exhaust means to allow said tilting movement of said columnar duct, said upper portion includîng means for engaging said first hood means when said roof is covering said crucible for connecting said first hood means to said columnar duct for withdrawing fumes generated during said melting operations, and said intermediate portion including means for flexibly coupling said charging hood means to said columnar duct to allow said charging hood means to move between said storage and use positions.
As used herein, "flexible" means capable of being moved or changed in direction or orientation without breaking, i.e., not stiff.
"Flexible" is thus meant to include "swivelling", "pivoting" and "tele-scoping", etc.
The invention may best be understood by reference to the following description and accompanying drawings of which:
Figure 1 is a diagrammatic top elevational view, partly cut away, of a metal melting furnace incorporating the invention, some of the . .
` ` 10691~;0 dashed lines of which partially illustrate movement of exhaust ducts, hoods and manifolds during various furnace operations;
Figure 2 is a diagrammatic side elevation of the furnace of Figure 1, some of the dashed lines of which partially illustrate movement of exhaust ducts, hoods and manifolds during various furnace operations;
Figure 3 is a diagrammatic rear elevation of the furnace of Figures 1-2;
Figure 4 is a sectional view of a detail of the duct structure of Figures 1-3 taken along section lines 4-4 of Figure 2;
Figure 5 is a fragmentary sectional view of the duct structure , of Figures 1-3 taken along section lines 5-5 of Figure l; and -- Figure 6 is a diagrammatic top plan view of an . ~
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t~ - 3a -.
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`` 10691f~0 " alternative embodiment of a detail of the exhaust system of Figs. 1-5.
Referring now to Figs. 1-2, a plurality of electrodes 14 protrude through a roof 12 into the interior of a metal melting furnace. Roof 12 is moved into and out of engagement with the furnace mouth by a member 113 mounted on the side of crucible 10. Member 113 projects the roof 12 ; vertically upwardly and then pivots the roof to a positionout of registry with the furnace mouth as indicated in Fig.
10. 1. Frame members 115 attached to pivot member 113 are adapted to lift roof 12 by lifting means, e.g., winches or chain hoists (not shown), mounted on frame members 115 and selectively engagable with roof 12. A melting fumes exhaust hood 126 is also attached to frame 115 and is supported ; thereby in close overlying relationship with the perforations in roof 12 through which electrodes 14 protrude. Hood 126 includes openings 226 covered by adjustable vanes. In use, air is drawn through openings 226 to sweep away fumes and gas generated during the melting cycle. An exhaust duct 127 20. opens interiorly of hood 126. At the end of exhaust duct 127 remote from hood 126 is a mating flange 125.
Crucible 10 is mounted upon a pair of trunnions 122. Crucible 10 is tilted by a pair of tilt cylinders 200, located to the rear of, and on each side of, crucible 10.
The main fumes exhaust duct section 46 is coaxial with the tilt axis of crucible 10. Duct section 46 is attached by a duct swivel 40 to a rearwardly running main fumes exhaust duct section 124. Duct section 124 joins a duct section 128 which executes a rising right angle bend about half way along 30. the side of the crucible as illustrated in Fig. 2. A support . . . . . ~
~691~
post 206 passes through a downwardly and rearwardly facing side wall 204 of duct section 128.
Support post 206 is attached at its lower extremity by a gusseted support member 208 to the side wall of crucible 10. Upwardly from its lower extremity, support post 206 is attached to the side wall of crucible 10 by a support member 210 which extends through a side wall 212 of duct section 128.
Near the upper extremity of duct section 128, open-10. ings are provided in side wall 204 and in an opposite side wall 214 thereof. A tapping fumes exhaust manifold 24, which overlies tapping spout 16 of the crucible 10 is con-nected to duct section 128 by a duct section 130 and a controllable damper 132. Damper 132 allows air flow into tapping manifold 24 to be regulated or shut off entirely, e.g., when the furnace is not being tapped.
A slagging fumes exhaust hood 48 is attached to duct section 128 through the rearwardly facing opening in duct side wall 204 by a controllable damper 154 and a duct 20. section 156. Damper 154 is controllable to vary the rate of withdrawal of the fumes from slagging fumes exhaust hood 48.
Upwardly from dampers 132, 154, duct section 128 is connected to a reducer duct section 216 which reduces the exhaust system cross sectional area slightly and changes the cross sectional shape from rectangular to circular. A
swivel 218 is mounted on the upper lip 220 of reducer section 216. A duct section 230 which comprises a charging -fumes exhaust manifold is mounted on swivel 218. A swivel 232 is mounted on the upper extremity of duct section 230.
30. Above swivel 232 is another reducer duct section - - ~ .
69i~
236 which reduces the cross sectional area of the duct sys-tem and changes its cross sectional shape from circular to rectangular. Duct section 230, and the charging hood 58 which it supports, are supported from post 206 by a plural-ity of radially extending braces 237 which are connected between the interior side walls of both of reducer sections 216, 236 and the exterior side wall of support post 206.
An illustrative layout of braces 237 is shown in Fig. 4, a - sectional view of reducer section 216 taken along ~ection 10. lines 4-4 of Fig. 2. A right angle bend duct section 240 is mounted on top of reducer section 236. The upper extrem-ity of support post 206 extends through a side wall 242 of duct section 240. A damper 244 regulates the air flow through duct section 240. Duct section 240 is terminated ; by a mating flange 160 which opens toward crucible 10 and mates with the flange 125 on melting fumes exhaust manifold 127 when frame 115 is in position over roof 12 and roof 12 is in its use position, closing crucible 10.
A charging hood operating cylinder 250 is mounted 20. on a bracket 252 which extends outwardly from the columnar fumes exhaust system away from crucible 10. An operating rod 254 extends from the end of cylinder 250 facing crucible 10 and is attached to a bracket 256 on an outer side wall 258 of a charging hood fumes exhaust duct 175. Duct 175 contains a damper 260 near its end adjacent duct section 230.
Radially extending cross sections of charging hood 58 are triangular, with the central opening 168 being defined by an inwardly and downwardly facing surface. Such a radial cross section is illustrated in Fig. 5. Duct section 175 30. conducts fumes from a plurality of inwardly and downwardly ~0691~0 facing radially extending slots 262 on the surface defining ; central opening 168. The rate of flow of fumes and gas through slots 262 and into duct section 230 is controlled by damper 260.
Charging hood 58 is generally circular. Opening 168 allows a charging bucket 71 to drop its contents into crucible 10 when hood 58 is in registry with the furnace mouth. In certain situations, however, it may be desirable to manufacture charging hood 58 with a section removed, the 10. opening in the charging hood thereby defining an arc. Of course, the ends of the arc would be closed to prevent air , from entering through them. Thus, there is illustrated in Fig. 6 an arcuately shaped charging hood 58' with two ends 264 defining an open sector 270 therebetween. Open sector ,` 270 allows a charging bucket 71 to pass into and out of opening 168 without requiring bucket 71 to be lifted above the level of charging hood 58'. This feature is important in situations in which there is relatively low vertical cl~arance between the charging hood 58' and the roof of 20. ceiling of the building in which the furnace is located.
; When the furnace of Figs. 1-4 has been charged, swivels 218, 232 allow charging hood 58 to be pivoted rear-wardly of the furnace about the axis of support post 206 by cylinder 250. With the charging hood 58 thus moved out of registry with the furnace mouth, frame 115 and melting hood 126 can be pivoted about the axis of member 113, moving roof 12 into position to close the furnace for the melting opera-tion. As roof 12 is moved into its position in registry with the furnace mouth, flanges 125, 160 seal against one 30. another to provide the necessary connection of melting hood 1C~69160 126 to duct section 128. -- As can be seen from the broken lines in Fig. 2, the entire duct system, including charging hood 58, tilts with the crucible for tapping. The columnar duct system is sup-ported from crucible 10 by support post 206 with duct sections 128, 216, 236 and 240 being mounted directly to the post. Charging hood 58 is supported by duct section 230 which is supported between swivels 218, 232 to allow charg-ing hood 58 to rotate to and from its use position.
10. The inclusion of a pluraiity of dampers, e.g., dampers 132, 154, 260, provides an added benefit to the arc furnace fumes exhaust systems of the present invention. As illustrated, temperature sensing means comprising a thermom-eter are mounted near the melting fumes exhaust hood 126, e.g., in duct section 240. Thermometer 300 measures the temperature of the fumes collected by melting hood 126. -This thermometer is connected by conventional electrical -and/or mechanical control means 302 to an automatic control 304 mounted on one of the dampers 132, 154, 260. In prac-20. tice, it is frequently of extreme importance to insure that the filtering material through which fumes collected by the fumes control systemY of this invention pass is not heated beyond a predetermined temperature. Heating beyond such temperature may, for example, cause the filtering material to begin to-:burn, destroying its effectiveness as a filter.
Thus, if thermometer 300 senses that an excessive temperature has been reached by the melting fumes being conducted through the exhaust system, the apparatus 302, 304 opens one or more of dampexs 132, 154, 260, allowing cooler make-up air to 30. enter the exhaust system through the tapping fumes exhaust .,. ., : ' ' ' - :
', ' , ' , ~ ' - ':
~ ' . .. -',' : ' . . ', .. -~ 10~91~0 . ~
hood 24, the slagging fumes exhaust hood 43, and the charg-ing fumes exhaust hood 58, respectively. The damper provid-ing the cooler make-up air which lowers the temperature of the exhaust flowing into the filtering equipment remains open until the melting fumes exhaust temperature indicated by thermometer 300 is reduced to a safe level. The filter-ing equipment may include a bag house in which are suspended a plurality of bags through which the exhaust fumes flow, the bags collecting particulate matter from the fumes. Such 10. equipment is protected from the effects of excessive fume temperature by the described system.
It may be seen that the disclosed "close capture"
- fumes control system provides apparatus for immediately cap-turing any fumes or dust generated during any phase of operation of the arc furnace. All fumes and dust are thus ; prevented from escaping and may be conducted away through the fumes exhaust system to a point where solids and harmful and deleterious gaseous pollutants may be separated from the effluent fumes before final exhaustion of the gas into the 20. environment. An additional and significant advantage of close capture arrangements of the type herein presented is that considerably less air volume is required to insure com-plete withdrawal of fumes and dust from the furnace into the exhaust system. The significant decrease in air volume required results in important economies in exhaust fan capacity, ductwork capacity and filtering equipment (bag-house) capacity. Capturing the fumes by these close capture hoods also insures that the fumes and dust from the electric arc furnace do not contaminate the breathing air of the 30. operators who may be working in the area.
_ ~ _ :~
,. . . . . . .
- : , .
.
This application discloses an improvement over the invention disclosed in co-pending Canadian Patent Application Serial No. 246-933, filed March 2, 1976, titled "Arc Furnace Fumes Control System" and assigned to the same assignee as the present invention.
In accordance with one aspect of the present invention, there is provided in a fumes control system for an electric arc furnace comprising a crucible providing an upwardly directed mouth, a roof covering said mouth, said roof being movable into an opening position away from said mouth, a plurality of arc electrodes extending downwardly through said roof, said crucible having at least one pouring spout opening therein and being tilt-able for tapping, said control system comprising exhaust means, first hood means for collecting fumes generated during furnace operations from said roof, said first hood means being movable with said roof to expose said mouth, the improvement comprising charging hood means for movement into a use position in close overlying relationship with said mouth when said first hood means and said roof are moved away from said mouth, said charging hood means having an opening therein through which said crucible is charged, said charging hood means also having a storage position away from said mouth, a columnar exhaust ductj means for supporting said columnar exhaust duct upon said crucible, said columnar exhaust duct comprising upper, intermediate and lower portions, said exhaust means being flexibly attached to said lower portion to allow said exhaust duct to tilt with said crucible, first conduit means for coupling said first hood means to said upper portion when said roof is covering said mouth, said intermediate portion including means for supporting said charging hood means from said columnar exhaust duct for movement between said storage and use positions and ~or coupling said charging hood means to said exhaust duct when said charging hood means is in said use position.
In accordance with another aspect of the invention, there is provided in a funes exhaust system for use with a furnace having a crucible with an upwardly directed mouth, a roof for covering said mouth during melting operations in said furnace, and means for projecting said ' ~ , , ,, '' : ' ' .. ... .. . .
10691~;0 ; roof vertically upwardly along an axis and pivotally about said axis to a position out of registry with said mouth for providing access thereto for charging said furnace, means for tilting said furnace for tapping, said fumes exhaust system comprising exhaust means and first hood means movable with said roof to a position out of registry with said mouth, the improvement comprising charging hood means movable between a use position in close overlying relationship with said mouth when said roof is moved to a position out of registry with said mouth and a storage position remote from said mouth, said charging hood means having a top - 10 with an opening therein for passage of a charging bucket therethrough` when said charging hood means is in overlying relationship with said mouth, said charging hood means having means therein disposed to provide air movement past said mouth, and into said exhaust means for exhausting fumes and dust generated during charging of said furnace, a columnar exhaust duct, means for supporting said columnar duct upon said crucible for tilting movement therewith, said columnar duct having upper, inter-mediate and lower portions, means for flexibly coupling said lower portion to said exhaust means to allow said tilting movement of said columnar duct, said upper portion includîng means for engaging said first hood means when said roof is covering said crucible for connecting said first hood means to said columnar duct for withdrawing fumes generated during said melting operations, and said intermediate portion including means for flexibly coupling said charging hood means to said columnar duct to allow said charging hood means to move between said storage and use positions.
As used herein, "flexible" means capable of being moved or changed in direction or orientation without breaking, i.e., not stiff.
"Flexible" is thus meant to include "swivelling", "pivoting" and "tele-scoping", etc.
The invention may best be understood by reference to the following description and accompanying drawings of which:
Figure 1 is a diagrammatic top elevational view, partly cut away, of a metal melting furnace incorporating the invention, some of the . .
` ` 10691~;0 dashed lines of which partially illustrate movement of exhaust ducts, hoods and manifolds during various furnace operations;
Figure 2 is a diagrammatic side elevation of the furnace of Figure 1, some of the dashed lines of which partially illustrate movement of exhaust ducts, hoods and manifolds during various furnace operations;
Figure 3 is a diagrammatic rear elevation of the furnace of Figures 1-2;
Figure 4 is a sectional view of a detail of the duct structure of Figures 1-3 taken along section lines 4-4 of Figure 2;
Figure 5 is a fragmentary sectional view of the duct structure , of Figures 1-3 taken along section lines 5-5 of Figure l; and -- Figure 6 is a diagrammatic top plan view of an . ~
.; ' .
t~ - 3a -.
.
`` 10691f~0 " alternative embodiment of a detail of the exhaust system of Figs. 1-5.
Referring now to Figs. 1-2, a plurality of electrodes 14 protrude through a roof 12 into the interior of a metal melting furnace. Roof 12 is moved into and out of engagement with the furnace mouth by a member 113 mounted on the side of crucible 10. Member 113 projects the roof 12 ; vertically upwardly and then pivots the roof to a positionout of registry with the furnace mouth as indicated in Fig.
10. 1. Frame members 115 attached to pivot member 113 are adapted to lift roof 12 by lifting means, e.g., winches or chain hoists (not shown), mounted on frame members 115 and selectively engagable with roof 12. A melting fumes exhaust hood 126 is also attached to frame 115 and is supported ; thereby in close overlying relationship with the perforations in roof 12 through which electrodes 14 protrude. Hood 126 includes openings 226 covered by adjustable vanes. In use, air is drawn through openings 226 to sweep away fumes and gas generated during the melting cycle. An exhaust duct 127 20. opens interiorly of hood 126. At the end of exhaust duct 127 remote from hood 126 is a mating flange 125.
Crucible 10 is mounted upon a pair of trunnions 122. Crucible 10 is tilted by a pair of tilt cylinders 200, located to the rear of, and on each side of, crucible 10.
The main fumes exhaust duct section 46 is coaxial with the tilt axis of crucible 10. Duct section 46 is attached by a duct swivel 40 to a rearwardly running main fumes exhaust duct section 124. Duct section 124 joins a duct section 128 which executes a rising right angle bend about half way along 30. the side of the crucible as illustrated in Fig. 2. A support . . . . . ~
~691~
post 206 passes through a downwardly and rearwardly facing side wall 204 of duct section 128.
Support post 206 is attached at its lower extremity by a gusseted support member 208 to the side wall of crucible 10. Upwardly from its lower extremity, support post 206 is attached to the side wall of crucible 10 by a support member 210 which extends through a side wall 212 of duct section 128.
Near the upper extremity of duct section 128, open-10. ings are provided in side wall 204 and in an opposite side wall 214 thereof. A tapping fumes exhaust manifold 24, which overlies tapping spout 16 of the crucible 10 is con-nected to duct section 128 by a duct section 130 and a controllable damper 132. Damper 132 allows air flow into tapping manifold 24 to be regulated or shut off entirely, e.g., when the furnace is not being tapped.
A slagging fumes exhaust hood 48 is attached to duct section 128 through the rearwardly facing opening in duct side wall 204 by a controllable damper 154 and a duct 20. section 156. Damper 154 is controllable to vary the rate of withdrawal of the fumes from slagging fumes exhaust hood 48.
Upwardly from dampers 132, 154, duct section 128 is connected to a reducer duct section 216 which reduces the exhaust system cross sectional area slightly and changes the cross sectional shape from rectangular to circular. A
swivel 218 is mounted on the upper lip 220 of reducer section 216. A duct section 230 which comprises a charging -fumes exhaust manifold is mounted on swivel 218. A swivel 232 is mounted on the upper extremity of duct section 230.
30. Above swivel 232 is another reducer duct section - - ~ .
69i~
236 which reduces the cross sectional area of the duct sys-tem and changes its cross sectional shape from circular to rectangular. Duct section 230, and the charging hood 58 which it supports, are supported from post 206 by a plural-ity of radially extending braces 237 which are connected between the interior side walls of both of reducer sections 216, 236 and the exterior side wall of support post 206.
An illustrative layout of braces 237 is shown in Fig. 4, a - sectional view of reducer section 216 taken along ~ection 10. lines 4-4 of Fig. 2. A right angle bend duct section 240 is mounted on top of reducer section 236. The upper extrem-ity of support post 206 extends through a side wall 242 of duct section 240. A damper 244 regulates the air flow through duct section 240. Duct section 240 is terminated ; by a mating flange 160 which opens toward crucible 10 and mates with the flange 125 on melting fumes exhaust manifold 127 when frame 115 is in position over roof 12 and roof 12 is in its use position, closing crucible 10.
A charging hood operating cylinder 250 is mounted 20. on a bracket 252 which extends outwardly from the columnar fumes exhaust system away from crucible 10. An operating rod 254 extends from the end of cylinder 250 facing crucible 10 and is attached to a bracket 256 on an outer side wall 258 of a charging hood fumes exhaust duct 175. Duct 175 contains a damper 260 near its end adjacent duct section 230.
Radially extending cross sections of charging hood 58 are triangular, with the central opening 168 being defined by an inwardly and downwardly facing surface. Such a radial cross section is illustrated in Fig. 5. Duct section 175 30. conducts fumes from a plurality of inwardly and downwardly ~0691~0 facing radially extending slots 262 on the surface defining ; central opening 168. The rate of flow of fumes and gas through slots 262 and into duct section 230 is controlled by damper 260.
Charging hood 58 is generally circular. Opening 168 allows a charging bucket 71 to drop its contents into crucible 10 when hood 58 is in registry with the furnace mouth. In certain situations, however, it may be desirable to manufacture charging hood 58 with a section removed, the 10. opening in the charging hood thereby defining an arc. Of course, the ends of the arc would be closed to prevent air , from entering through them. Thus, there is illustrated in Fig. 6 an arcuately shaped charging hood 58' with two ends 264 defining an open sector 270 therebetween. Open sector ,` 270 allows a charging bucket 71 to pass into and out of opening 168 without requiring bucket 71 to be lifted above the level of charging hood 58'. This feature is important in situations in which there is relatively low vertical cl~arance between the charging hood 58' and the roof of 20. ceiling of the building in which the furnace is located.
; When the furnace of Figs. 1-4 has been charged, swivels 218, 232 allow charging hood 58 to be pivoted rear-wardly of the furnace about the axis of support post 206 by cylinder 250. With the charging hood 58 thus moved out of registry with the furnace mouth, frame 115 and melting hood 126 can be pivoted about the axis of member 113, moving roof 12 into position to close the furnace for the melting opera-tion. As roof 12 is moved into its position in registry with the furnace mouth, flanges 125, 160 seal against one 30. another to provide the necessary connection of melting hood 1C~69160 126 to duct section 128. -- As can be seen from the broken lines in Fig. 2, the entire duct system, including charging hood 58, tilts with the crucible for tapping. The columnar duct system is sup-ported from crucible 10 by support post 206 with duct sections 128, 216, 236 and 240 being mounted directly to the post. Charging hood 58 is supported by duct section 230 which is supported between swivels 218, 232 to allow charg-ing hood 58 to rotate to and from its use position.
10. The inclusion of a pluraiity of dampers, e.g., dampers 132, 154, 260, provides an added benefit to the arc furnace fumes exhaust systems of the present invention. As illustrated, temperature sensing means comprising a thermom-eter are mounted near the melting fumes exhaust hood 126, e.g., in duct section 240. Thermometer 300 measures the temperature of the fumes collected by melting hood 126. -This thermometer is connected by conventional electrical -and/or mechanical control means 302 to an automatic control 304 mounted on one of the dampers 132, 154, 260. In prac-20. tice, it is frequently of extreme importance to insure that the filtering material through which fumes collected by the fumes control systemY of this invention pass is not heated beyond a predetermined temperature. Heating beyond such temperature may, for example, cause the filtering material to begin to-:burn, destroying its effectiveness as a filter.
Thus, if thermometer 300 senses that an excessive temperature has been reached by the melting fumes being conducted through the exhaust system, the apparatus 302, 304 opens one or more of dampexs 132, 154, 260, allowing cooler make-up air to 30. enter the exhaust system through the tapping fumes exhaust .,. ., : ' ' ' - :
', ' , ' , ~ ' - ':
~ ' . .. -',' : ' . . ', .. -~ 10~91~0 . ~
hood 24, the slagging fumes exhaust hood 43, and the charg-ing fumes exhaust hood 58, respectively. The damper provid-ing the cooler make-up air which lowers the temperature of the exhaust flowing into the filtering equipment remains open until the melting fumes exhaust temperature indicated by thermometer 300 is reduced to a safe level. The filter-ing equipment may include a bag house in which are suspended a plurality of bags through which the exhaust fumes flow, the bags collecting particulate matter from the fumes. Such 10. equipment is protected from the effects of excessive fume temperature by the described system.
It may be seen that the disclosed "close capture"
- fumes control system provides apparatus for immediately cap-turing any fumes or dust generated during any phase of operation of the arc furnace. All fumes and dust are thus ; prevented from escaping and may be conducted away through the fumes exhaust system to a point where solids and harmful and deleterious gaseous pollutants may be separated from the effluent fumes before final exhaustion of the gas into the 20. environment. An additional and significant advantage of close capture arrangements of the type herein presented is that considerably less air volume is required to insure com-plete withdrawal of fumes and dust from the furnace into the exhaust system. The significant decrease in air volume required results in important economies in exhaust fan capacity, ductwork capacity and filtering equipment (bag-house) capacity. Capturing the fumes by these close capture hoods also insures that the fumes and dust from the electric arc furnace do not contaminate the breathing air of the 30. operators who may be working in the area.
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.
Claims (12)
1. In a fumes control system for an electric arc furnace comprising a crucible providing an upwardly directed mouth, a roof covering said mouth, said roof being movable into an opening position away from said mouth, a plurality of arc electrodes extending downwardly through said roof, said crucible having at least one pouring spout opening therein and being tiltable for tapping, said control system compris-ing exhaust means, first hood means for collecting fumes generated during furnace operations from said roof, said first hood means being movable with said roof to expose said mouth, the improvement comprising charging hood means for movement into a use position in close overlying relationship with said mouth when said first hood means and said roof are moved away from said mouth, said charging hood means having an opening therein through which said crucible is charged, said charging hood means also having a storage position away from said mouth, a columnar exhaust duct, means for support-ing said columnar exhaust duct upon said crucible, said columnar exhaust duct comprising upper, intermediate and lower portions, said exhaust means being flexibly attached to said lower portion to allow said exhaust duct to tilt with said crucible, first conduit means for coupling said first hood means to said upper portion when said roof is covering said mouth, said intermediate portion including means for supporting said charging hood means from said columnar ex-haust duct for movement between said storage and use positions and for coupling said charging hood means to said exhaust duct when said charging hood means is in said use position.
2. A fumes control system according to claim 1 wherein said crucible has a pouring spout opening forwardly and a slagging port opening rearwardly, said crucible being tiltable forwardly to pour through said spout and rearwardly for removing slag from said port, third hood means for col-lecting fumes from said pouring spout, third conduit means for connecting said third hood means to said lower portion of said exhaust duct, fourth hood means for collecting fumes from said slagging opening, fourth conduit means for connect-ing said fourth hood means to said lower portion of said exhaust duct, said third and fourth hood means being mounted on said crucible for tilting movement therewith.
3. A fumes control system according to claim 1 wherein said means for supporting said columnar exhaust duct comprises a support post mounted on said crucible and extend-ing generally vertically, said columnar exhaust duct being attached to said support post, said intermediate portion in-cluding a pair of swivels having a duct section therebetween, said charging hood means being attached to said duct section for movement between said storage and use positions.
4. A fumes control system according to claim 3 wherein said opening in said charging hood means is generally circular for allowing a charging bucket to enter said cruci-ble therethrough when said charging hood means is in said use position.
5. A fumes control system according to claim 3 wherein said charging hood means opening is generally arcuate, said charging hood means further defining an open sector for allowing a charging bucket to enter said opening by moving horizontally through said open sector.
6. A fumes control system according to claim 1 and further comprising means for sensing the temperature of fumes in said upper portion of said columnar exhaust duct, said sensing means being connected to said upper portion, a con-trolled damper coupled to said exhaust means and to a source of cooling make-up air, and damper control means connected to said temperature sensing means and to said controlled damper for opening said damper in response to sensing of fume temperature above a predetermined maximum in said upper por-tion.
7. In a fumes exhaust system for use with a furnace having a crucible with an upwardly directed mouth, a roof for covering said mouth during melting operations in said furnace, and means for projecting said roof vertically upwardly along an axis and pivotally about said axis to a position out of registry with said mouth for providing access thereto for charging said furnace, means for tilting said furnace for tapping, said fumes exhaust system comprising exhaust means and first hood means movable with said roof to a position out of registry with said mouth, the improvement comprising charging hood means movable between a use position in close overlying relationship with said mouth when said roof is moved to a position out of registry with said mouth and a storage position remote from said mouth, said charging hood means having a top with an opening therein for passage of a charging bucket therethrough when said charging hood means is in overlying relationship with said mouth, said charging hood means having means therein disposed to provide air movement past said mouth, and into said exhaust means for exhausting fumes and dust generated during charging of said furnace, a columnar exhaust duct, means for supporting said columnar duct upon said crucible for tilting movement therewith, said columnar duct having upper, intermediate and lower portions, means for flexibly coupling said lower portion to said exhaust means to allow said tilting movement of said columnar duct, said upper portion including means for engaging said first hood means when said roof is covering said crucible for connecting said first hood means to said columnar duct for withdrawing fumes generated during said melting operations, and said intermediate portion including means for flexibly coupling said charging hood means to said columnar duct to allow said charging hood means to move between said storage and use positions.
8. A fumes exhaust system according to claim 7 wherein said support means comprises a generally vertically extending support post mounted outwardly from a side wall of said crucible, said columnar duct being mounted upon said support post and extending generally longitudinally thereof, said means for flexibly coupling said charging hood means to said columnar duct comprising a pair of co-axial swivels lying in parallel planes extending generally transversely of said support post and a duct section sup-ported between said swivels, said charging hood means being rigidly attached to said duct section for swivelling move-ment between its storage and use positions upon said duct section.
9. A fumes exhaust system according to claim 7 wherein said opening in said charging hood means top has generally circular horizontal cross sections and vertical cross sections of said charging hood means extending radially from the center of said opening are generally triangular in shape providing a radially inwardly and downwardly facing surface, said means for providing air movement past said mouth including a plurality of apertures opening on said inwardly and downwardly facing surface and internally of said charging hood means for allowing fumes to pass into said charging hood means.
10. A fumes exhaust system according to claim 9 wherein said apertures are elongated slots extending down-wardly and radially outwardly from said charging hood means top.
11. A fumes exhaust system according to claim 7 wherein said opening has a generally arcuate horizontal cross section, said charging hood means further defining an open sector for allowing a charging bucket to enter said opening horizontally through said open sector for charging said furnace.
12. A fumes exhaust system according to claim 7 and further comprising means for sensing the temperature of fumes captured by said first hood means, selectively oper-able damper means connected to said exhaust means, and means for operating said damper means, said operating means being connected to said temperature sensing means and responsive thereto for opening said damper means to admit air into said exhaust means when the temperature of said fumes captured by said first hood means exceeds a pre-determined maximum temperature.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/664,947 US3999001A (en) | 1975-09-24 | 1976-03-08 | Arc furnace fumes control system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1069160A true CA1069160A (en) | 1980-01-01 |
Family
ID=24668101
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA268,490A Expired CA1069160A (en) | 1976-03-08 | 1976-12-22 | Arc furnace fumes control system |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1069160A (en) |
| IT (1) | IT1080303B (en) |
-
1976
- 1976-12-22 CA CA268,490A patent/CA1069160A/en not_active Expired
-
1977
- 1977-01-05 IT IT1907977A patent/IT1080303B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| IT1080303B (en) | 1985-05-16 |
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