US3178164A

US3178164A - Apparatus for injecting particulate material into furnaces

Info

Publication number: US3178164A
Application number: US231079A
Authority: US
Inventors: Elwood V Schulte; Preston Elliott
Original assignee: Koppers Co Inc
Current assignee: Beazer East Inc
Priority date: 1962-10-17
Filing date: 1962-10-17
Publication date: 1965-04-13
Anticipated expiration: 1982-04-13
Also published as: DE1508046A1

Description

April 1965 E. v. SCHULTE ETAL 3,178,164

APPARATUS FOR INJECTING PARTICULATE MATERIAL INTO FURNACES 5 Sheets-Sheet 1 Filed Oct. 17, 1962 14 732119 d/V 7V0.)

INVENTORS. El-WOOD V- SCHULTE ELLIOTT PRESTON KM M T/Ieir A T TORNE Y April 13, 1965 E. v. SCHULTE ETAL 3,178,164

APPARATUS FOR INJECTING PARTICULATE MATERIAL INTO FURNACES Filed Oct. 17, 1962 3 Sheets-Sheet 2 INVENTORS EL W000 V. SCHULTE BY ELLIOTT PRESTON X MMM Their- ATTORNEY April 13, 1965 E. v. SCHULTE ETAL 3,178,164

APPARATUS FOR INJEGTING PARTICULATE MATERIAL INTO FURNACES Filed Oct. 17, 1962 3 Sheets-Sheet 3 FIG. 7

INVENTORS ELWOOD V. SCHULTE ELLIOTT PRE$TON Kauai 6M Their A T TORNE Y United States Patent ration of Delaware Filed 0st. 17, 1962, Ser. No. 231,079 3 Claims. (Cl. 266-28) This invention relates to an improved process and apparatus for the injection of particulate material into furnaces, and more particularly, to an improved process and apparatus wherein powdered coal is injected into blast furnaces.

Early in the development of the blast furnace art, attempts were made to charge a part of the fuel as lumps along with the ore and the fiuxing compounds at the top of the blast furnace and to supply the remainder of the fuel by introducing pulverized, solid fuel into the hearth of the blast furnace with the blast. Erratic operation of the blast furnace resulted because even distribution of the coal particles was not obtained and control of the quantity of coal particles being injected into the blast furnace was not obtained heretofore.

The present invention provides a process and apparatus enabling an accurate control of the amount of coal fed to the blast furnace and an even distribution of such coal, thereby providing for continuous and uniform operation of the blast furnace.

The combustion of carbon injected into the lower part of a blast furnace has a number of advantages. It furnishes the heat necessary for maintaining the thermal equilibrium of the blast furnace. It also supplies the carbon monoxide used for effecting the reduction of the ore to metallic iron. Simultaneously, by direct reduction, it effects the decomposition of the slag before the slag is discharged from the blast furnace. This slag would otherwise be present if the ore had not been completely reduced during its descent through the blast furnace. The reducing power in the blast furnace may be varied by suitably regulating the ratio of carbon to air and the quantity of carbon injected into the lower part of the blast furnace. In this manner it is also possible to obtain to desired temperature in the blast furnace.

The carbon is desirably introduced into the blast furnace as a powdered coal and air mixture. Such method of introduction necessarily requires injection of the mixture under considerable pressure, for example as high as fifty pounds per square inch gage or more.

Heretofore, it was believed that the entire coal delivery and injection system must be maintained under a high pressure to enable the powdered coal-air mixture to be injected into the blast furnace. Accordingly, the practice heretofore has been to place the powdered coal in a pressurized bin from which a plurality of pipe lines lead to the tuyeres of the blast furnace. This practice has serious disadvantages. For example, the cost of maintaining a bin of suitable size under a high pressure is extremely expensive. In addition, when this type of system is used, it is difficult if not impossible to regulate the flow rate of the powdered coal since any valves inserted in the pipe lines cause clogging of these lines.

It has now been discovered that the feeding of coal particles into a pressurize pneumatic feed line can be carried out more accurately and economically by the use of an improved rotary coal feeder, described hereinafter, in conjunction with a hopper which is maintained at atmospheric pressure and in which the introduction of the coal particles into the coal feeder takes place at atmospheric pressure.

The coal particles are delivered from the feed bin under 3,178,154? 1C6 Patented Apr. 13, 1965 atmospheric pressure in a free falling stream into peripheral pockets of a rotary feeder wheel that is provided with teeth on its periphery, and rotates within a rigid casing. The pockets formed between the teeth of the wheel and the casing are configured to present an axis which is determined as the hypotenuse of a right triangle whose side is the vector of particle velocity of the free falling particles, and whose base is the vector of the tip velocity of the pockets. A wear plate is provided on either side of the rotary feeder wheel, and a novel seal member is positioned between each wear plate and the rotary feeder wheel. The rotary feeder wheel and the seal move against the wear plate which is fastened to the casing of the coal feeder. A small clearance is left between the seal and the wear plates to reduce the abrasion of the moving parts of the coal feeder. The seal is of such configuration that adequate sealing is obtained, even with this small clearance between the seal and the wear plate. The rotary feeder wheel of the coal feeder is driven by any appropriate variable drive means.

Crushed coal drops from the feed bin into the top of the rotary feeder wheel through a transition piece. The teeth of the rotary feeder wheel are spaced at an angle to enable the coal to fall smoothly into the pockets. The pockets are not provided with side plates, because the coal particles are removed from the pockets after they have rotated from the filling Zone to the discharge point by blowing air transversely across the face of the rotor parallel to the shaft. This air stream, as a conveying medium picks up the coal from the rotor pocket and carries the coal to the blast furnace. The coal particles leave the coal feeder at a sufficiently high pressure to allow the coal particles to be injected into the blast furnace.

Those skilled in the art will, of course, recognize that while air has been referred to as the conveying medium it is also possible to use air which has been enriched with oxygen. Furthermore, it is possible to use the products of combustion that have resulted from the burning of gases or coal.

The quantity of coal particles being delivered to the blast furnace may be accurately determined in accordance with this invention. The coal feeder acts as a meter. The amount of coal being fed through the coal feeder is directly proportional to the revolutions per minute of the coal feeder.

Introducing pulverized coal into the furnace through the main air blast of the tuyeres to supply fuel to the blast furnace has been proposed before. Various forms of apparatus have been designed to perform the handling, distribution and introduction of the pulverized coal into the tuyeres of the furnace but they have all encountered a number of practical difficulties. These diliiculties may, in general, be traced to the tendency of the pulverized coal to choke the conduit pipes, conveyors or other means which have been employed to feed the coal to the furnace.

In transporting pulverized coal in an air stream through a pipe line, it is found that the material tends to segregate in the bends of the pipe line, and if the pipe line is split into a pair of branch lines, great difiiculty is experienced in dividing the stream equally between the branches. This is apparently due to a force which tends to throw the majority of the material into one branch while the other branch receives only a small portion of the material. It is necessary for efiicient operation that each of the tuyeres of the blast furnace receive the same quantity of powdered coal, but this result has been diflicult to obtain since there are almost invariably bends in the pipe line which produce segregation of the coal. Moreover, the problem is rendered even more difficult because it has been impossible inthe past to accurately 3 measure the amount of powdered coal which is being injected' into the furnace.

The improved rotary coal feeder of this invention is capable of accurately determining the amount of powdered coal being fed to the blast furnace, since, as discussed. above, the amount of coal is directly proportional to-the revolutions per minute of the coal feeder. It is a simple matter to calibrate the coal feeder at the beginning of operations and then, as the operations continue, the amountof coal being injected into the blast furnace is easily determinable.

It has now been. found that by the use of a novel splitter, the coal-in-air stream can be segregated into two equal branches, whereby one coal feeder can be used for injecting the coal into two tuyeres. it is also possible, by usin' a plurality of the novel splitters of the invention, to split the coal stream a second time in each of the two branches, whereby a single coal feeder can supply four tuyeres of the blast furnace. Although more expensive, it is also possible, and in some instances desirable, to use a coal feeder to feed a single tuyere. One instance where this would be necessary would be in a system to feed a blast furnace having an odd number of tuyeres. In the preferred embodiment all but one coal feeder would lead to a coal splitter and would feed two tuyeres. A single coal feeder would lead directly to the odd tuyere.

The coal-in-air stream must change direction several times while being transported from the coal feeder to the blast furnace tuyeres since the available space around a blast furnace is limited. Any such change in direction of the pipe lines multiplies the problems involved In accordance with the invention an improved and novel method has been devised to counteract this tendency towards uneven distribution in the pipe line downstream from a bend or elbow and upstream of a coal splitter. To counteract this tendency the pipe line is constricted or reduced in area upstream frornthe splitter and downstream from the bend in the pipe line. In this manner, a good mixing of air and coal is obtained and the coal-in-air stream can be evenly split. The reduction in area of the pipe increases the velocity of the coal-inair stream only at the point of reduced area and therefore the major portion of the system is not subjected, to the excessive air velocity. The constricted portion of the pipe line is of an area such that the velocity in the line exceeds 60 feet per second and of alength sufficient that the pressure loss across the reduced portion of the pipe line does not exceed 20 pounds per square inch. By staying within these limits the pipe line will be long enough to get the thorough mixing desired and still minimize the length of high velocity line-where wear or rosion of the pipe will be high.

By locating the splitter. in a vertical line with upward flow of coal and air, additional energy will be imparted to-the coal particles by the air stream because of the need for the air stream to overcome the downward acceleration of the coal particles due to the force of gravity. The additional energy thus imparted would create additional turbulence and tend to further the even distribution of the coal particles throughout the cross section of the pipe. With the location of the splitter in this position of upward flow, a lower velocity due to restriction of the pipe would be needed for the same resulting distribution of coal particles across the cross section of the pipe.

Cit

all

The branch lines after the coal splitter must be relatively symmetrical, and the length of each line after the splitter must be substantially equal. In addition, the cross-sectional area of each pipe should be substantially equal. In this manner, when the pipe lines after the split ter are clean, the resistances in each line between the splitter and the end of the line at the tuyere will be the same. The pressure loss between these points when both branch lines are open and free flowing should be at least 1 pound per square inch. These conditions will ensure even distribution of air to each branch line and thereby assist in making equal distribution of coal in each air stream.

With the method and apparatus of the invention, it has now been found possible to utilize coal particles having a high moisture content because of the improved system which utilizes a bin which is open to the atmosphere, the improved coal feeder, and the novel splitter of the invention, It is now possible to utilize coal havin a moisture content between about 3 and 10 percent and preferably between 4 /2 and 8 /2 percent.

The following description of the preferred embodiment of the invention is described with reference to the accompanying drawing in which:

FIGURE 1 is a schematic elevational tlow diagram of a typical injection system.

FIGURE 2 is a top view of the coal feeder of the invention.

FIGURE 3 is a vertical longitudinal cross-sectional view of the coal feeder of the invention, taken along lines 3-3 of FIGURE 2.

FIGURE 4 is a transverse cross-sectional view taken along lines 44 of FIGURE 2.

FIGURE 5 is an elevational view of the seal rings for the coal feeder.

FIGURE 6 is a cross-sectional view taken along lines 6-5 of FlGURE 5, and

FEGURE 7 is a cross-sectional view of the coal splitter of the invention.

Referring to the FIGURE 1 of the drawings, coal arriving at the coal injection plant from the mine or from storage is dumped into a hopper 16 from which it is carried by belt 12 to an impact crusher 14. The crushed coal is transferred by bucket elevator 16 from the crusher to a vibrating screen 18 of predetermined size. The eversized particles which are retained on the screen return to the hopper 19. Undersized particles which pass through the screen are fed through chute 20 to belt 22 which transports the material to a reversible shuttle conveyor 24 comprised of two conveyors 26, 28 which deposit the prepared coal evenly in rectangular feed bin 3%.

Underneath the bin 36 are a plurality of hopper devices 32 each delivering particles to a coal feeder 34. The bin is mounted on load cells (not shown) so that the'weight of coal particles in the bin can be determined periodically to obtain a check on the feed rate. This aids in making minor adjustments in coal feeder speed whichwoutd be necessary because of gradual changes in coal bulk density due to variations in-moisture content and coal pulveriaa tion.

Compressed air is supplied to all the coal feeders 3 3 by supply means 35 through a common header 36 from which parallel branch lines '38 flow to the individual units.

The coal-air mixture leaving each coal feeder flows Air pressures and air flows are automatically regulated to The improved coal feeder 34, FIG. 3, will be seen to comprise the following sections or major parts: A body or rotor

housing end sections

102, 104, section 102 forming the outlet end of the pump and section 104 being the air intake end of the coal feeder; a feeder wheel 106 having teeth 108 and shaft 110; and a feed hopper 116.

The rotor housing 100 has a generally cylindrical body provided with an extended upper section 118 having a fiat top 120. Set between the rotor housing 100 and each of the

end members

102, 104 are

wear plates

122, 124 and seal discs 126, 128. The rotor 106 and the seals 126 and 128 rotate together with an extremely small clearance between them and the

wear plates

122, 124 whereby leakage of high pressure air through the feeder is prevented. Each of the seals 126, 128 is disc shaped with a circular aperture in the center thereof for the shaft 110. Along the outer rim of each of the seals 126, 128 is a

flange

127, 129 upon which is fitted a

seal ring

130, 132 for positioning in circular slots 134 (FIG.

The seal rings 130, 132 of coal feeder 34 comprises rings-shaped members 194 (FIGS. 5 and 6) having an outer periphery and an inner periphery the distance between said outer periphery and said inner periphery being greater than the thickness of the ring. Flanges are provided which extend from each of said outer periphery and said inner periphery, the flange 196 from said outer periphery extending further than the flange 1% from said inner periphery. This type of seal ring 1-30 in conjunction with seals 126, 128 effectively seals the pump whereby the high pressure existent in'sections 109 between teeth 103 of coal feeder wheel 106 does not leak from the coal feeder 34 to the atmosphere, and entrance of solids into the spaces between the rotor faces and the wear plate is prevented. This specific design of the seal and seal rings alfords a longer life to the coal feeder, requires less maintenance, and gives better sealing action than any other seal esign heretofore known. The seal ring may be made of such material as neoprene, polytetrafiuoroethylene, or a butadiene-acrylonitrile copolymer.

Discharge openings

144, 146, FIGURE 3, are formed in

wear plates

122, 124 in the vertical plane of and below the opening for the shaft 110 in each plate.

Detachable sections

102 and 124 are secured to the rotor housing 1% by means of a plurality of bolts 1 .8 (FIGURE 2) to provide for disassembly and maintenance. Section 102 of the coal feeder contains a substantially disc shaped plate having a fiange portion 152 which is provided with tapped holes for securely fastening end plate 154 thereto by the use of machine screws 156. Placed

b tween elements

152 and 154 is a thrust end sleeve 15?) and a rubber O-ring .160. Additional support is given by reinforcing ribs 162 positioned between

elements

150 and 152.

The shaft 110 of the feeder wheel 106 is supported at one end 102 by duplex bearing 162 and at the other end by single ball bearing means 164. The shaft 11% is keyed to feeder wheel 106 by key means 166 whereby the feeder wheel rotates with the shaft.

Section 104 of the coal feeder is similar to section 102 thereof in that it comprises a substantially disc-shaped plate 168 having a flange portion 170 which is provided with tapped holes for securely fastening end plate 172 thereto by the use of machine screws 174. A rubber 0- ring 176 is also provided to seal end plate 172 to a coupling end sleeve 178. Reinforcing ribs 180 are positioned between plate 168 and flange 170 of section 104.

High pressure air is fed to the coal feeder through pipe means 38 through connecting

means

184, 18%. The air then sweeps the coal particles out of the space 109 between teeth 108 and the coal and air mixture exits through connecting means 188, and pipe line means 40. The rotor housing 100 is provided with at least one vent 138 and preferably with a plurality of vents 138, 1 5-0,

6 14 2 for relieving the pressure within the rotor housing 100 and the spaces 109 between the teeth 108.

In operation coal particles from the feed bin fall into the pockets 109 between teeth 108 of rotary feeder wheel 1%. As the rotary feeder wheel 106 rotates it carries the coal particles down to the bottom of the coal feeder 34

adjacent openings

144, 146 in

wear plates

122, 124. At this point a blast of high pressure air enters through line 38 which blast of air picks up and entrains the coal particles from pockets 109, and carries the air entrained coal to the blast furnace through line 40. The high pressure blast of air creates a large pressure differential through the pump which tends to cause leakage between rotor 106 and wear plates 122, .124. The high pressure air stream may also carry coal particles therewith. By virtue of seal discs 126, 12$ and seal rings 130, 132 this tendency is counteracted and the novel seal members effectively seal the coal feeder from the deleterious effects of the high pressure air.

The coal and air mixture stream flows through line 40 by way of a coal splitter 42 to the blast furnace 46. Coal splitter 42 comprises a simple Y-shaped member comprising a main conduit 212 and branch conduits 44, 44'. The pipe 40 containing the coal and air mixture from the coal feeder 34 is constricted in cross-sectional area as shown at 210, and then feeds into main conduit 212 which is of the same cross-sectional area as the constricted area 210 of pipe 4-0. Main conduit 212 and pipe 40 are joined by means of

flanges

214, 216 integral with each of sections 210, 212.

Flanges

214, 216 are connected by suitable means such as bolts 218. Knife edge 220 is carefully positioned in the constricted portion of the pipe 212 to cause even distribution of the coal and air stream into each of the branch conduits 44, 44'.

The constricted portions 210, 212 of the pipe line ahead of the splitter have a cross-sectional area such that the velocity in the line at this point exceeds 60 ft./sec. The constricted cross-sectional area is of such length that the pressure loss across this portion of the pipe line does not exceed 20 lbs./in. So long as the length and cross-sectional area of this constricted portion is maintained within these limits, the constricted .area will provide the desired thorough mixing in order to obtain equal splitting and will minimize the distance exposed to high velocity where wear or erosion is high.

The surprising effect of the foregoing arrangement is emphasized by actual performance tests where two coal splitters were set up in the line from a coal feeder to the tuyeres of the blast furnace and measurements were made of the approximate total standard cubic feet per minute of air, the coal rate, and the percent of coal received in each of the tuyeres. The results are shown below in Table I.

Table I Y-TYPE SPLITTER NO CONSTRICTION (1% INCH PIPE) Y-TYPE SPLITTER FOLLOWING 2 FEET OF INCH PIPE 5, 548 51. 1 48. 9 4, 456 50. 2 49. 8 3, 696 49. 4 50. 6 1, 932 53. 4 46. 6 3, 720 50. 3 49. 7 l, 592 46. 0 54. O 3, 672 53. 9 46. 1 3, 088 48. 7 51. 3 1, 600 50. O 50. 0 1, 450 51. 7 48. 3 1, 572 50. 1 40. 9 1, 432 46. 9 53. 1 1, 272 46. 3 53. 7

As can be readily seen, the coal splitter Without the constriction in the line is inadequate to evenly divide the coal, whereas when the coal was fed through a constriction upstream of the splitter, the splitting of the coal was substantially even in all instances, regardless of the air rate or the coal rate.

In operation of the device, coal arriving at the coal injection plant is dumped into hopper 10 from which it is carried by belt 12 to an impact crusher 14. The crushed coal is transferred by bucket elevator 16 from the crusher 14 to a vibrating inch screen 18 from which the oversize material (greater than inch) which is retained on the screen returns to the hopper it Undersize coal (less than inch) which falls through the screen is fed through means 20 to belt 22 which transports the material to a reversible shuttle conveyor 24 which deposits the coal evenly in feed bin 20.

Underneath bin 2% are a plurality of hopper devices 32 each delivering coal to a coal feeder 3-4. For an average blast furnace having 19 tuyeres ten coal feeders are provided. The coal-in-air streams from each of nine of the coal feeders is divided and feeds '18 of the 19 tuyeres. The tenth coal feeder feeds a single tuyere. Compressed air is supplied to each of the coal feeders 34 by supply means 35 through a common header 36 and branch lines 38. The coal from hopper devices 32 falls into the hoppers 116 on the coal feeders 34 and into the spaces 139 between the teeth 138 of rotary feeder wheel 1%.

As the ecder wheel 1% rotates it carries the coal particles down to the bottom of the coal feeder 34 adjacent the

openings

144, 146 in

wear plates

122, 124. At this point a blast of air entering through line 38 and connecting means 188, 1% and into pipe line 40. Pipe line 40 transfers the coal and air mixture to the section of the pipe line which is reduced in area immediately before the coal splitters 42. Each coal splitter 42 splits the coal and air stream into two substantially equal sections through branch lines 44, 44' each of which branch lines leads to alternate tuyeres 45 'of blast furnace 46.

The maximum amount of coal that can be injected into a blast furnace will be on the order of about 3000 pounds of coal per hour per tuyere, therefore, for an avenage blast furnace having 19 tuyeres, there would be a maximum amount of 57,000 pounds of coal per hour fed to the blast furnace. A preferred amount of coal injected into the blast furnace is 1400 pounds per hour per tuyere, which, on the same blast furnace would average about 2627,000 pounds of coal per hour. The minimum air rate for proper operation would be about standard cubic feet per minute because if the air rate falls below 45 standard cubic feet per minute, the lines will become plugged causing failure of the coal injection equipment. Generally, not more than 115 standard cubic feet per minute of air would be used. Itwill normally be necessary to use between about 0.75 to 2.25 standard cubic feet of air per pound of coal injected into the blast furnace. It is preferred that about 1.2 standard cubic feet of air per pound of coal be used. A lesser amount of air than 0.75 standard cubic foot per pound of coal will be insuflicient to carry thecoal particles, and air in amounts greater than 2.25 standard cubic feet per pound of coal will be excessive.

While the above description has referred to the introduction of coal particles into blast furnaces it should be understood that the teachings also relate to the injection of other solid materials into blastfurnaces. These solid materials may be, for example, sized lime, limestone, or flue dust. It also should be understood that the teachings apply to the injection of coal or other solid materials into metallurgical furnaces other than blast furnaces.

We claim:

1. Apparatus for injecting coal particles into a blast furnace comprising a hopper, a crusher for crushing said coal particles, a conveyor belt to transport said coal particles from said hopper to said crusher, a sizing screen for sizing the crushed coal into undersize coal particles which pass through the screen and oversize coal particles which are retained on the screen, an elevator for transporting crushed coal particles from said crusher to said sizing screen, means for returning oversize coal particles from said sizing screen to said hopper, means for feeding undersized coal particles from said vibrating screen to a feed bin, a plurality of coal feeders, means for feeding the coal particles from said feed bin to each of said coal feeders, means for eutraining the coal particles in each coal feeder in an air stream to form a coal-in-air stream, a plurality of coal splitters, a conduit for the transport of said coal-in-air stream operatively associated with each of said coal feeders, each of said conduits leading to a coal splitter, each of said coal splitters dividing one coalin-air stream into two branch lines, each of said branch lines transporting said divided coal-in-air stream to a tuyere on said blast furnace, each of said coal feeders comprising a rotary solids tnansfer pump having a peripherally pocketed rotary feeder Wheel mounted for rotation in an annular pump casing having a solids entrance and aligned air inlet and discharge opening in register with the pockets of the feeder wheel, the feeder wheel having non-rubbing close clearance with the pump casings, and further including a seal disc seated in an annular groove beti-veen the feeder wheel and the wear plate, said seal disc having a flange extending from its outer circumference, a seal ring fitted on said flange, said seal ring having an outer periphery and an inner periphery, the distance between said outer periphery and said inner pe riphery being greater than the thickness of said ring, and flanges extending from each of said outer periphery and said inner periphery, the flange from said outer periphery extending further than the flange from said inner periphery and the flange from said outer periphery being operatively associated with said seal disc, said feeder wheel, and said wear plate whereby entrance of solids into the spaces between the rotor faces and the wear plate is prevented, and wherein each of said coal splitters for splitting a coal-in-air stream into two substantially equal portions comprises three pipe lines joined together in the shape of a Y, said Y comprising a main conduit and two branch conduits, said main conduit having a constricted portion immediately upstream of the branch conduits, and a knife edge at the juncture of the main conduit and the branch conduits, said knife edge extending in a direction substantially parallel to said main conduit.

2. Apparatus for injecting coal particles into a blast furnace comprising a hopper, an impact crusher for crushing the coal particles, a conveyor belt to tnansport said coal particles from said hopper to said impact crusher, a vibrating screen for sizing said coal particles, a bucket elevator for transporting crushed coal particles from said impact crusher to said vibrating screen, means for returning oversized coal particles from said vibrating screen to said hopper, means for feeding undersized coal particles from said vibrating screen to \a feed bin maintained under atmospheric pressure, a plurality of coal feeders, each of said coal feeders comprising a rotary solids transfer pump having a peripherally pocketed rotary feeder wheel mounted for rotation in an annular pump casing, said casing having a solids inlet and aligned air inlet and outlet openings in register with said feeder wheel pockets, said feeder wheel having nonrubbing close clearance with said annular pump casing, a seal disc seated in an annular groove between said feeder wheel and a wear plate, said seal disc having a flange extending from its outer circumference, a seal ring fitted on said flange, said seal ring having an outer periphery and an inner periphery, the distance between said outer periphery and said inner periphery being greater than the thickness of said seal ring, flanges extending from said inner and outer periphery of said seal ring, said flange extending from said outer periphery extending further than said flange extending from said inner periphery, said flange extending from said outer periphery being operatively associated with said seal disc, said feeder wheel and said wear plate so that the entrance of coal particles into the spaces between said feeder wheel and said wear plate is prevented, means for feeding coal particles at atmospheric pressure from said feed bin to each of said coal feeders, a plurality of coal splitters, each of said coal feeders having a conduit associated therewith, means for feeding said coal particles from said respective coal feeder into said associated conduit and admixing said coal particles with an air stream under superatmospheric pressure to form a coal-in-air stream, said respective conduits arranged to transport said coal-in-air stream therethrough, each of said conduits leading to a coal splitter, each of said coal splitters dividing said coal-in-air stream into two branch lines, and each of said branch lines transporting said divided coal-in-air stream to a tuyere on said blast furnace.

3. Apparatus for injecting particulate material into a furnace comprising means for feeding coal particles to a feed bin which is open to the atmosphere, a plurality of coal feeders, said coal feeders comprising a peripherally pocketed rotary feeder wheel mounted for rotation in an annular pump casing having a solids entrance and aligned air inlet and discharge openings in register with the pockets of the wheel, the feeder wheel having nonrubbing close clearance with the pump casing, the improvement comprising a seal disc seated in an annular groove between the rotor and the wear plate, said seal disc having a flange extending from its outer circumference, a seal ring fitted on said flange, said seal ring having an outer periphery and an inner periphery, the distance between said outer periphery and said inner periphery being greater than the thickness of said ring, and flanges extending from each of said outer periphery and said inner periphery, the flange from said outer periphery extending further than the flange from said inner periphery and the flange from said outer periphery being operatively associated with said seal disc, said rotor, and said wear plate whereby entrance of solids into the spaces between the rotor faces and the wear plate is prevented, means for feeding coal particles from said feed bin to each of said coal feeders, means for admixing said coal particles from said coal feeders with air at superatmospheric pressure to form a coal-in-air stream, means for transporting said coal particles in a coal-in-air stream at a snperatmospheric pressure from said coal feeders to said coal splitters, each of said coal splitters dividing said coal particles in said coal-in-air stream into two portions, and means for transporting each portion to said furnace.

References Cited by the Examiner UNITED STATES PATENTS 1,640,770 8/27 Hamilton et al 110- 104 2,158,673 5/39 Carter et a1. 110 104 2,468,321 4/29 Bland 241-80 x MORRIS O. WOLK, Primary Examiner.

JAMES H. TAYMAN, IR., Examiner.

Claims

1. APPARATUS FOR INJECTING COAL PARTICLES INTO A BLAST FURNACE COMPRISING A HOPPER, A CRUSHER FOR CRUSHING SAID COAL PARTICLES, A CONVEYOR BELT TO TRANSPORT SAID COAL PARTICLES FROM SAID HOPPER TO SAID CRUSHER, A SIZING SCREEN FOR SIZING THE CRUSHED COAL INTO UNDERSIZE COAL PARTICLES WHICH PASS THROUGH THE SCREEN AND OVERSIZE COAL PARTICLES WHICH ARE RETAINED ON THE SCREEN, AN ELEVATOR FOR TRANSPORTING CRUSHED COAL PARTICLES FROM SAID CRUSHER TO SAID SIZING SCREEN, MEANS FOR RETURNING OVERSIZE COAL PARTICLES FROM SAID SIZING SCREEN TO SAID HOPPER, MEANS FOR FEEDING UNDERSIZED COAL PARTICLES FROM SAID VIBRATING SCREEN TO A FEED BIN, A PLURALITY COAL FEEDERS, MEANS FOR FEEDING THE COAL PARTICLES FROM SAID FEED BIN TO EACH OF SAID COAL FEEDERS, MEANS FOR ENTRAINING THE COAL PARTICLES IN EACH COAL FEEDER IN AN AIR STREAM TO FORM A COAL-IN-AIR STREAM, A PLURALITY OF COAL SPLITTERS, A CONDUIT FOR THE TRANSPORT OF SAID COAL-IN-AIR STREAM OPERATIVELY ASSOCIATED WITH EACH OF SAID COAL FEEDERS, EACH OF SAID CONDUITS LEADING TO A COAL SPLITTER, EACH OF SAID COAL SPITTERS DIVIDING ONE COALIN-AIR STREAM INTO TWO BRANCH LINES, EACH OF SAID BRANCH LINES TRANSPORTING SAID DIVIDED COAL-IN-AIR STREAM TO A TUYERE ON SAID BLAST FURNACE, EACH OF SAID COAL FEEDERS COMPRISING A ROTARY SOLIDS TRANSFER PUMP HAVING A PERIPHERALLY POCKETED ROTARY FEEDER WHEEL MOUNTED FOR ROTATION IN AN ANNULAR PUMP CASING HAVING A SOLIDS ENTRANCE AND ALIGNED AIR INLET AND DISCHARGE OPENING IN REGISTER WITH THE POCKETS OF THE FEEDER WHEEL, THE FEEDER WHEEL HAVING NON-RUBBING CLOSE CLEARANCE WITH THE PUMP CASINGS, AND FURTHER INCLUDING A SEAL DISC SEATED IN AN ANNULAR GROOVE BETWEEN THE FEEDER WHEEL AND THE WEAR PLATE, SAID SEAL DISC HAVING A FLANGE EXTENDING FROM ITS OUTER CIRCUMFERENCE, A SEAL RING FITTED ON SAID FLANGE, SAID SEAL RING HAVING AN OUTER PERIPHERY AND AN INNER PERIPHERY, THE DISTANCE BETWEEN SAID OUTER PERIPHERY AND SAID INNER PERIPHERY BEING GREATER THAN THE THICKNESS OF SAID RING, AND FLANGES EXTENDING FROM EACH OF SAID OUTER PERIPHERY AND SAID FLANGES EXTENDING FROM EACH OF SAID OUTER PERIPHERY PERIPHERY EXTENDING FURTHER THAN THE FLANGE FROM SAID INNER PERIPHERY AND THE FLANGE FROM SAID OUTER PERIPH ERY BEING OPERATIVELY ASSOCUATED WITH SAID DISC, SAID FEEDER WHEEL, AND SAID WEAR PLATE WHEREBY ENTRANCE OF SOLIDS INTO THE SPACES BETWEEN THE ROTOR FACES AND THE WEAR PLATE IS PREVENTED, AND WHEREIN EACH OF SAID COAL SPLITTERS FOR SPLITTING A COAL-IN-AIR STREAM INTO TWO SUBSTANTIALLY EQUAL POSITIONS COMPRISES THREE PIPE LINES JOINED TOGETHER IN THE SHAPE OF A Y, SAID Y COMPRISING A MAIN CONDUIT AND TWO BRANCH CONDUITS, SAID MAIN CONDUIT HAVING A CONSTRICTED PORTION IMMEDIATELY UPSTREAM OF THE BRANCH CONDUITS, AND A KNIFE EDGE AT THE JUNCTURE OF THE MAIN CONDUIT AND THE BRANCH CONDUITS, SAID KNIFE EDGE EXTENDING IN A DIRECTION SUBSTANTIALLY PARALLEL TO SAID MAIN CONDUIT.