|Publication number||US3432398 A|
|Publication date||Mar 11, 1969|
|Filing date||Jul 14, 1964|
|Priority date||Jul 14, 1964|
|Also published as||DE1431563A1, DE1431563B2, DE1923888U|
|Publication number||US 3432398 A, US 3432398A, US-A-3432398, US3432398 A, US3432398A|
|Inventors||Lawrence D Schmidt|
|Original Assignee||Allied Chem|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (8), Referenced by (8), Classifications (16), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
March 11, 1969 1 D. SCHMIDT 43,431,391?,
CHARGINGVCOKE OVEN WITH HOT COARSELY COMMINUTED COAL March ll, 1969 L.. D. SCHMIDT 3,432,398
CHARGING COKE OVEN WITH HOT COARSELY COMMINUTED COAL Filed July 14. 1964 sheet Z of 5 F/G. 3 ,[27 F/G. 2
March 11, 1969 L. D. SCHMIDT CHARGING COKE OVEN WITH HOT COARSELY COMMINUTED COAL Sheet Filed July 14, 1964 questa can o 0 I NVE N TOR. Ava-#rf 5mn/ar March 11, 1969 L.. D. SCHMIDT 3,432,398
cHARGING coxE ovm wml HOT coAnsELY coMMINuTED coAL Filed July 14, 1964 sheet 4 SOLEA/O/D INVENTOR. 4x/Piva! .2 ww/,ar
4March 11, 1969 L. D. SCHMIDT 3,432,398
CHARGING COKE OVEN WITH HO'I.1 COARSELY COMMINUTED COAL Filed July 14. 1964 sheet 5 of 5 fl] l//Jll//l/ SoaEA/a/D "M52 /l//l/l/l//l/l/l/l/l/ 0 o o 0 o o o o o e 0 w1 u I N VEN TOR. Mya-'m2 SoWi/a7 VBY 4United States Patent O 9 Claims ABSTRACT OF THE DISCLOSURE A method of charging coking chambers or coke oven battery with hot coarsely comminuted coal particles, the particles being introduced into the chamber through a pipeline through which they are carried by a carrier gas under superatmospheric pressure, the gas being the means for inducing ow of the hot coal through the pipeline, the pressure being controlled carefully to maintain a certain coalto-carriergas Weight ratio and venting the line at least once before ythe oven, so that the oven feels a charge which has a high coal-to-carrier-gas weight ratio, which is brought to the oven at a relatively low pressure.
This invention relates to the charging of coal into the coking chambers of a coke oven battery.
The advantages of charging the coking chambers with coal preheated to a temperature such that the coal is completely dried and below the temperature at which the coal is in a plastic state has long been recognized. Paramount among lthese advantages is the reduction of coking times within the coking chambers, with consequent marked increase in the capacity of the battery. When coal containing moisture is introduced into the coking chambers the amount of heat required to be transferred through the walls of each 4chamber to and through the stationary charge to evaporate the water content of the charge is indeed large. Abut 40% of the total coking time is spent, in prior conventional coking practice, to effect the necessary heat input throughout the charge to evaporate and remove the water content of the charge and to raise the temperature thereof to Within the range of from 250 F. to 700 F. In modern practice, with large coking chambers having a capacity, say, of about l5 to 25 tons per chamber, the coking time is usually from about to about 30 hours depending on the type of the coke produced, namely Whether blast furnace coke or foundry coke; a saving of 40% of this time is indeed of vast economic importance.
It has been proposed to preheat the coal in the fluidized state in a uidizing and heating chamber externally of the coking chambers of the battery to a temperature of about 700 F. and then convey the preheated tluidized coal Iparticles by the uidizing gas into the coking chambers of the battery where carbonization of the preheated coal is effected (U.S. Patent 2,658,862). This procedure is objectionable for a number of reasons, among which may be mentioned that it requires the pulverization ofthe coal to reduce it to particle size such that it can be transported in iluidized condition, with the expense involved in so doing. The coking of coal particles fine enough to be readily transported in fluidized condition results in coke of poor quality, unsatisfactory for many metallurgical uses.
Transport of the hot coal with a carrier lgas under pressure has the serious objection that at the mixture of coal particles land the gas travels along the pipeline, the pressure within the pipeline continually decreases and the gas expands with the attainment of increasing velocities. In other words, the rapid increase in specific volume of the expanding gaseous mixture is accompanied by a correspondingly rapid increase in velocity in accordance with the mass continuity equation. Bearing in mind the length of a battery, it will be appreciated that relatively long pipelines are necessary to supply the preheated coal to all of the coking chambers of the battery. Excessively high velocities produce excessive friction losses with consequent lower eiciencies. It is known that friction and abrasion in a solid transport system varies proportionately to the cube of the velocity of the solid; hence a velocity should be used as low as is compatible with the smooth transport of the coal, in order to reduce wear on the pipeline. Moreover, employing known pneumatic conveyance and with the relatively high velocity of the carrier gas required for transport of the solids through a long pipeline, the solids to gas ratio at the exit end of the pipeline is relatively low. The charging of coking chambers with such low coal to gas ratio presents several problems, e.g., the diiculties involved in effecting disentrainment of the coal from the carrier gas in the coking chamber being charged and the prevention of excessive carryover of coal particles into the collector main.
Pulsating discharges of air at intervals along the length of a pipeline to advance solid material progressively from one zone to the next in a wave-like manner has been disclosed (U.'S. Patent 1,465,269). This transport procedure cannot be used for the transport of preheated coal because the coal would be oxidized destroying its coking properties. The ilow of air into the hot coking chamber with ythe coal would result in combustion of the coal. Furthermore, such transport procedures cannot be used for relatively long distances such as are necessary in coke oven battery installations, and this even though an inert gas were used instead of air, because the velocities of the stream would soon increase to a level rendering such procedure objectionable. Moreover, due to the periodic introduction along the length of the pipeline of inert gas under pressure, the coal to gas weight ratio would progressively fall along the length of the pipeline so that lat the exit end thereof relatively low coal to gas weight natio results, with the serious and thus far insolvable problems hereinabove noted in the charging of coking chambers with low coal to gas weight ratios.
Preheated coal by reason of its dry hot condition has substantially different properties from the standpoint of its handling and conveyance than the original wet coal from which it is produced and fwhich wet coal is ordinarily charged into the coking chambers of a coke oven battery. Such preheated coal has a substantially reduced angle of repose and tends to disperse or float when owed through conveying systems and particularly when introduced into a confined space such as a coking chamber at rates necessary in effecting the charging of a coking chamber. This tendency to disperse or float is accentuated by the property of the dry hot coal particles not to tend to adhere to each other as do the particles of Wet coal normally employed for charging the coking charnbers of a coke oven battery. This tendency of the hot coal produces conditions detrimental to eicient charging of coking chambers When attempts are made to charge preheated coal into the coking chambers by heretofore known methods. Thus when preheated coil is introduced into the charging holes of a coking chamber from the chutes of a larry car, the hot coal entering the hot coking chamber entrains air which reacts with the coal and the volatile matter evolved from the coal to form fires and explosions resulting in damage to the coking chambers, to the larry car and hazards to operating personnel.
When attempts are made to transport the coal of size desirable for coking, by a pneumatic conveying system from the preheater to the ovens, the amount of carrier gas required to effect movement of the coal over the distances involved, except possibly to the coking chambers immediately adjacent the preheater, is such that the introduction of the hot coal and carrier gas mixture into the coking chamber produces the undesired conditions and problems noted above. Moreover, these undesired conditions and problems become accentuated as the distance from the preheater to the coking chamber being charged, or the length of the pneumatic conveying line, becomes longer, e.g., in the case of relatively large batteries or where more than one battery is supplied with preheated coal from one locality.
It is a primary object of the present invention to provide a novel procedure of conveying coarsely comminuted preheated coal particles from a preheater to the coking chambers of a coke oven battery, which procedure results in the feed of a hot coal carrier gas stream having a relatively high coal to carrier gas /weight ratio when introduced into the coking chamber and otherwise overcomes the difficulties and problems hereinabove noted.
Another object of this invention is to provide a novel pipeline construction for effecting such conveyance of preheated coal particles of a particle size conventionally used for charging the coking chambers of a battery, referred to herein as coarsely comminuted coal particles.
Other objects and advantages of the present invention will be apparent from the following detailed description thereof.
In accordance with this invention, a carrier gas under superatmospheric pressure is employed to effect feed of preheated coarsely comminuted coal particles through a pipeline to the coking chambers of a battery, and at one or more points along the length of the pipeline and desirably at or just before the mixture of hot coal and carrier gas is discharged from this pipeline into each coking chamber, excess carrier gas is bled off or vented from the pipeline to produce at the exit end of the pipeline a hot ocal carrier gas mixture at a relatively low pressure and having a relatively high coal to carrier gas V weight ratio. The carrier gas can be superheated steam or coke oven gas; superheated steam is preferred. This relatively W pressure stream of hot coal and carrier gas having such relatively high coal to carrier gas weight ratio is introduced into each coking member to be charged to effect the charging thereof.
Since the weight ratio of preheated coal particles and carrier gas in the stream charged into the coking chambers is kept high and at an optimum level for facilitating the disentrainment of the coal from the gas in the coking chamber, ready separation of the coal from the gas in the coking chamber takes place. Moreover, the steam or coke oven gas employed as the carrier gas introduced into the coking chamber exits into the collector main. The steam condenses in the collector main, adding to the water therein. In the case of coke oven gas, it mixes 'with the coke oven gas in the collector main. Thus the use of superheated steam or coke oven gas does not complicate the operation of the coke oven battery; in fact, it improves the operation, giving clean smoke-free charging, preventing the oxidation of the coal and minimizing charging difficulties.
In a preferred embodiment of the present invention, when employed for the transport of 1 to 3 tons per minute of hammer-milled preheated coal through a pipeline of 4 six-inch diameter, the coal being unscreened and having a maximum particle size of about one inch, the hot coarsely comminuted coal particles and superheated steam are introduced into the upstream end of the pipeline. The superheated steam is supplied from a steam line at a pressure of from 25 to 600 p.s.i.g., preferably 250 to 350 p.s.i.g. The steam is introduced from this steam line through one or more steam jets and the steam expands upon introduction into the pipeline so that it has a velocity of at least sonic, preferably supersonic, at the point of introduction into the pipeline, i.e., at it leaves the steam jets. The pressure within the pipeline at the upstream end thereof is from 4 to 50 p.s.i.g. and the velocity of the steam, preheated coal mixture is from 10 to 200 feet per second. Jets for introducing additional superheated steam are positioned in the bottom of the pipeline to produce jets of steam at an angle of from five degrees to 20 degrees to the horizontal and in a direction the same as the desired direction of ow of the preheated coal through the pipeline. Along the length of the pipeline at the bottom thereof, i.e., at the outside of the pipeline on curved sections desirably having a radius preferably of 6 feet or more and at the bottom on straight horizontal runs, the spacing of these jets is from 6 inches to 36 inches apart, preferably l2 inches to 18 inches apart. The closer the spacing of the jets, (a) the less pressure required entering the pipeline, (b) the less velocity required for smooth transport, (c) higher coal-steam weight ratios can be attained, and (d) higher rates of coal flow can be attained. The jets are spaced somewhat closer in the bends, e.g., every 5 degrees to 9 degrees of arc. At least 10 jets are positioned in a degree bend having a six foot radius which corresponds to one jet every 12 inches, although preferred spacing is one jet every six or seven inches. A larger radius of curvature permits larger spacing of the jets. The closer the spacing the less the pressure drop per unit length of pipe at a given rate of coal ow.
In accordance with this invention excess steam is bled off from the mixture thereof with the preheated coal particles at one or more points along the length of the pipeline by subjecting the mixture to centrifugal force, for example, by flow through a cunved section of the pipeline or by passing a side stream of the mixture through a cyclone separator to produce a body of steam substantially free of coal particles. Steam is vented from the body thereof substantially free of coal particles formed by subjecting the mixture to centrifugal force or from the side stream passed through the cyclone separator in this modification of the invention. Where a side stream is removed coal particles carried thereby are returned to the pipeline.
The venting of the steam from the pipeline as herein disclosed permits replacement thereof along the length of the pipeline by the steam introduced at sonic or supersonic velocities in the fonm of jets to effect the propulsion of the coal particles through the pipeline and this without excessive build up of velocity of mixture of coal and superheated steam in the pipeline and 'with the delivery of the mixture to the coking chamber at a high solids to steam weight ratio and at a relatively low pressure rnot exceeding about 2 p.s.i.lg. The number of such venting units employed in any pipeline will depend on the particle size of the coal particles transported, the length of the line and the quantity of steam jetted thereinto. Por any given pipeline, it is a comparatively simple matter to determine the number of such venting 'units Iwhich should be used for optimum flow of the preheated coal particles. In general, two units should be used per feet of pipeline length when conveying preheated hammer-milled coal in a pipeline having an inside diameter of 6 inches employing steam as the carrier gas supplied to the jets under a pressure of 25 to 600 p.s.i.g., the steam jets being spaced apart approximately l5 inches between adjacent jets. The steam upon entering the pipeline through the jets expands to at least sonic velocity when the absolute pressure of the steam supply is at least twice the absolute pressure in the pipeline.
At least one venting unit should be positioned at the point near the discharge into the coking chamber. The branches leading from the main pipeline, each branch being individual to a coking chamber, may each be shaped to produce a curved bend subjecting the mixture flowing therethrough to centrifugal force to produce in the bend a body of steam substantially free of coal particles, 'which body is vented either to the atmosphere or to an adjacent coking chamber or to t-Wo or more adjacent coking chambers. Thus is created a high weight ratio (20 to 500) of preheated coal particles to steam with consequent desired low pressure not exceeding about 2 p.s.i.g. in the mixture which is discharged into the coking chamber. This high weight ratio greatly facilitates disentrainment of the coal particles from the steam within the coking chamber and hence minimizes carryover of coal into the gas olf-take.
`Good transport through the pipeline equipped with steam jets is obtained when the ratio of preheated coal particles to steam on a weight basis is within the range of from 2O to 150; `60 pounds of preheated coal per pound of steam represents preferred densi-ty of the mixture containing particles as large as 1 inch conveyed through pipeline. At the inlet end of the pipeline the coal to steam weight ratio can be from 20 to 350 to 1, preferably 80 to 1. At the point of discharge into the coking chamber this -weight ratio can be `20 to 5100 to 1, preferably 8O to 1. Where the coal particles are of smaller size a higher weight ratio of coal particles to steam can be employed.
`Coke oven gas when used as the carrier gas can be introduced in the same manner as the steam into the pipeline, as herein disclosed, and also vented in the same manner except that coke oven gas, unlike steam, cannot be condensed and the coke oven gas is desirably vented into a coking chamber other than the one being changed from which it flows into the collector main. Since superheated steam is the preferred carrier gas, the description which follows, for the most part, will be limited to steam. It will be understood, however, that the invention is not limited to the use of steam as the carrier gas.
Other objects and advantages of the present invention will become apparent as the detailed description proceeds in connection with the accompanying drawings, wherein:
FIGURE 1 is a diagrammatic elevational view, partly in section, showing one embodiment of the invention employed for the charging of the coking chambers of a coke oven battery;
FIGURE 2 is a fragmentary sectional view through a pipeline taken in a plane and in the direction indicated by 2-2 on FIGURE 5, showing one of the jet nozzles;
FIGURE 3 is a fragmentary sectional view taken in a plane passing through line 3-3 on FIGURE 2;
FIGURE 4 is a fragmentary sectional View showing a horizontal curve in a horizontal run of a pipeline embodying a preferred form of the present invention in which a curvilinear section of the pipeline applies centrifugal force to the Imixture flowing therethrough and thus effects separation of the coal particles from the steam;
FIGURE 5 is a fragmentary sectional view showing a vertical curve in a horizontal run of a pipeline, i.e., a curve disposed in a vertical plane rather than in a horizontal plane as in the case of FIGURE 4;
FIGURE 6 is a vertical section through a modified form of bleed-off device of the invention involving a cyclone separator construction for effecting separation of coal particles from the steam in 'a side stream removed from the pipeline and owing therefrom into the separator;
:FIGURE 7 is a vertical section showing still another modified form of the invention utilizing a cyclone separator for reflecting separation of the coal particles from the steam;
FIGURE 8 is a vertical section through a bend or elbow of the pipeline showing a preferred construction minimizing, if not completely avoidinig, the effect of wear of the pipel-ine Walls at the bends which are subjected to maximum erosion conditions by the solid particles in the mixture flowing therethrough; and
FIGURE 9 shows another embodiment of the invention in which cyclone separators are used to bleed off steam at points of entry of coal into the usual charging holes of a coking chamber.
The drawings have been made not to scale in order to better illustrate the structure and principles of the present invention. The dimensions of the parts, it will be understood, will depend on the desired capacity of a give-n installation and can be varied as desired.
Referring rst to FIGURE 1 of the drawings, 21 is a pressurized bin of the type disclosed, for example, in applicants copending application Ser. No. 282,351 led May 22, 1963. Bin 21 receives dried preheated hammermilled coal particles for feed -to a Crusher 22 in an accelerator chamber 23. To facilitate flow of the coal particles from bin 21 to chamber 23 steam is introduced through line 24 into bin 21. Flow of coal from bin 21 to the accelerator chamber 23 is controlled by a gate valve 25 operated by a pressure fluid cylinder 26. lt will be understood that the source of coal particles shown in FIGURE l for the pipeline 27 represents one convenient and preferred source. Coarsely comminuted coal particles can be supplied to the pipeline 27 from any suitable source.
In the embodiment of the invention shown in FIGURE l, pipeline 27 has an inside diameter of from 4 inches to 8 inches, preferably about 6 inches, and leads from the exit end of the accelerator chamber 23 to a main 28 which extends along the length of the battery. Main 28 has individual to each coking chamber a discharge conduit 29 leading into that coking chamber, preferably at an angle less than about 23 degrees to the horizontal, so that the coal mixture is discharged near one end of the coking chamber and ows therefrom as disentrainment lfrom the steam takes place towards the opposite end of the coking chamber. As customary, the coking chambers, a section through one of which is shown in FIGURE 1, are each provided with doors 31, 32 at the opposite ends and an uptake pipe or gas otftake 33 at the end remote from the coal discharge conduit 29. One of the doors 31 or 32 as customary can be provided with a levelling door for the levelling door opening through which the levelling ram is reciprocated to level the charge in the coking chamber. The present invention, however, lends itself to operations in which the charge in the coking chamber. The present invention, however, lends itself to operations in which the charge is self-levelling, the superheated steam mixture introduced having substantially the ow characteristics of a liquid so that a relatively uniform charge of coal is produced during the disentrainment of the solid coal particles from the steam, which charge does not require levelling. It will be appreciated that the invention includes the transport of the coal-steam mixture into the coking chambers both with and without subsequent levelling of the charge with a conventional levelling bar.
Pipeline 27 is provided at closely spaced points along its length, as hereinabove described, with jets 34 for introducing steam, preferably superheated steam. These jets are supplied with steam from a steam line 35 running parallel to the pipeline 27. Extending from steam line 35 at spaced points therealong are a plurality of branches 36 each leading to a jet nozzle 37 which injects the steam into the coal-steam mitxure flowing through the pipeline 27. The steam is jetted in the direction of How entering at sonic or supersonic velocities and imparting an impulse or velocity to the flowing mixture. The direction of the injected jets of steam is indicated by the arrow 38 (FIG- URE 3). Branches 36 can be provided with valves 39 which can be adjusted to give the desired velocity of flow into the pipeline or can be closed when it is desired to reduce the number of branches 36 supplying fresh steam to the pipeline.
A preferred form of jet nozzle 37 is shown in FIG- URES 2 and 3 and comprises a hexagonal plug 41 having a threaded end 42 in threaded engagement within a bore 43 in the wall of the pipeline 27. The top of threaded end 42 lies flush with the inner wall of the pipeline to provide a smooth interior where the jets enter the pipeline, free of obstructions to the ow of the steam-coal mixture and also free of pockets or dead spaces. Plug 41 has a group of radiating nozzles 44, each of venturi shape having a divergent or exit portion 44a, the included angle formed by the walls of which is between and 7 and having an entrance portion 44h that is effectively convergent. In the embodiment shown in FIGURE 2 each plug 41 has three such nozzles communicating with a common passage 45 leading into a central bore 46 in plug 41. Preferably each nozzle 37 delivers a jet stream of steam at an angle of about 5 to 201 with respect to the axis of the pipeline at the point where the jet nozzle is positioned, e.g., in the case of a straightaway horizontal pipeline, at an angle of about 5 to 20 with respect to the horizontal. The end 47 of each plug 41 is threaded at 48 to receive the threaded end 49 of a branch 36 leading from steam line 35. This arrangement provides fanlike jets of gas imparting velocity or impulses to the flowing coal-steam mixture in the direction of ow indicated by the arrows 50 (FIGURE 4).
In the embodiment of the invention shown in FIGURE 1, pipeline 27 is provided at one point along its length, indicated at A, with a curved portion 51 for subjecting the mixture of superheated steam and preheated coal particles flowing therethrough to centrifugal force. Each discharge conduit 29 is shaped to contain a curved portion 51'.
In FIGURE 1, portion 51 is a skew curve; it need not be in a single plane. In FIGURE 5 the curvilinear portion S1 is disposed in a plane which can be tilted in any direction but is vertical as shown; FIGURE 4 shows a curve arranged in a horizontal plane, but can be in any desired plane. The curvilinear portions can be skew curves not in a single plane and still operate in the same way.
Referring to FIGURE 4, curvilinear portion 51 comprises a first curved section S3 having a center of curvature at C1 and leading into and smoothly continuous with a second curved section 54 having a center of curvature at C2. Section 54 leads into and is smoothly continuous with a third curved section 55 having a center of curvature at C3. The radii of curvature of adjacent sections 53 and 54, and 54 and 5S are diametrically opposite each other, i.e., the center of curvature C1 is on one side of the pipeline, C2 on the opposite side and C3 on the same side of the pipeline as C1. For a 6" pipeline for transporting hammer-milled coal, the radius of curvature can be from l to 9 feet, preferably about 6 feet.
The successive curved sections 53, 54 and 55 are designed for streamline flow therethrough; section 53 is connected with its section of the pipeline through a suitable flanged coupling 53a for streamline flow thereinto from the pipeline. Similarly section 55 is connected through a flanged coupling 55a with the pipeline for streamline flow from section 55 into the pipeline section contiguous thereto.
As the mixture of preheated coal and superheated steam flows through the first curved section 53 having the center of curvature C1, the coal particles S are propelled by centrifugal force in a radially outward (outward relative to the center of curvature) direction away from C1 (upward and to the right as viewed in FIGURE 4) so as to have a relatively dense concentration in the radially outward interior region 56 of curvilinear portion 51 whereas the radially inward interior region S7 of the latter contains steam which is relatively free of coal particles. Similarly in the continued ow of the mixture through curved section S4, the coal particles are thrown by centrifugal force outwardly forming the relatively coal-free steam body 59. As the coal-steam mixture flows through the next curved section 55, the coal particles are thrown toward the outer region forming a relatively coalfree steam body 60. Thus the curvature of conduits 51 act to apply centrifugal force to the coal-steam mixture flowing therethrough to separate the coal particles S from the steam.
In the embodiment of the invention shown in FIG- URE 4, relatively coal-free steam bodies 57 and 59 are vented to the atmosphere to bleed-olir from these regions steam which is discharged into the atmosphere or to a suitable disposal point. For this purpose there is provided a bleed-0E tube 61 having one end threaded or otherwise connected to conduit 51 and in communication with the radially inward interior region S7 thereof. Bleed-off tube 61 extends from said connected end in a direction generally opposite the direction of flow of the coal-steam mixture, for example, at about 45 to the axis of the pipeline at the point the bleed-off tube projects therefrom. The opposite end of bleed-olf tube 61 is provided with an orifice plate 62 for controlling the rate of discharge to the atmosphere of bleed-off steam indicated by the arrow 63. Orifice plate 62 can be detachably secured to the exit end of bleed-off tube 61 as by bolts 64. By changing the orifice plate to provide the bleed-off tube 61 with a desired size orifice opening, the flow rate of the steam bled off can be controlled as desired. Instead of an orifice plate a valve 65 (FIG- URE 5) can be used to control the discharge rate of the steam bled off from the pipeline. Alternatively, employing correctly sized bleed-off tubes, no valve or orifice plate is required.
Steam can be bled of from body 59 by a bleed-off tube 61e which operates in the same manner as bleedoff tube 61. Tube 61C, as shown in FIGURE 4, extends in a direction away from the pipeline 27 opposite to the direction of flow therethrough as in the case of bleedoff tube 61. In this way little or no coal particles enter the bleed-off tubes 61 or 61C; the velocity of ow and the action of centrifugal force resist ow of coal particles into the bleed-off tubes 61 and 61C.
FIGURE 5 is a side elevational view of a modified form of bleed-off device in which the conduit 51e` extends in a curvilinear path lying in a vertical plane, not in a horizontal plane as in the modification of FIGURE l. Hence, in the construction of FIGURE 5 the centrifugal forces acting on the coal particles S to effect separation from the steam are augmented by gravitational force which aid in effecting such separation. Conduit 51C is interposed in communicating series relation between the adjacent sections 51a and 51b of the pipeline as in the case of the construction of FIGURE 4 and is joined thereto at its opposite ends by suitable anged couplings 53a and 55a.
Conduit 51e comprises a first curved portion 53e` extending forwardly and downwardly in an arcuate path about the center of curvature Cla, a second curved portion 54C continuous with portion 53e and extending downwardly and then upwardly in an arcuate path about the center of curvature C2a, and a third curved portion 55e continuous with portion 54e and extending upwardly and forwardly in an arcuate path about the center of curvature C3a. As the steam-coal mixture flows through second conduit portion 54C in the direction indicated by arrow 50a, the combined centrifugal and gravitational forces act to throw the coal particles S downwardly in a direction away from the center of curvature C2a so that the radially outward interior region 68 has a relatively high coal density whereas the steam in the radially inward interior region 69 is relatively free of coal particles. A bleed-off tube 61e, similar to the bleed-off tube 61, bleeds of the relatively coal-free steam from the region 69. Bleed-off tube 61C has a valve 65 therein for adjusting the bleed-off rate of the steam. Tube 61c extends away from the pipeline in a direction away from the direction of ow of the coal-steam mixture through the pipeline.
A typical illustration of the effectiveness of the bleedoff arrangement similar to that shown in FIGURE 4 was obtained in charging a full scale coke oven with 13.3 tons of dry coal. The oven was filled in 6.3 minutes using a 6" pipeline with 8" spacing of the jets similar to those shown in FIGURE 3; the jets were supplied with steam at about 150 p.s.i.g. The coal was transported at the rate of 2.1 tons per minute using 88 pounds of jet steam per minute or 42 pounds of jet steam per ton of coal transported. The pressure at the head end of the pipeline was 8 p.s.i.g. and 3 p.s.i.g. at the end where it discharged into the coking chamber through a curved portion similar to 51' FIGURE 1. This curved portion had three 2" I.D. bleed-off pipes spaced about 30 apart. These bleed-offs were throttled on and off according to the amount of visible carryover of coal at the riser pipe at the far end of the oven chamber. At p.s.i.g. the calculated fiow out one bleed-off pipe 2 in diameter, based on isentropic flow, is 80 pounds of steam per minute. No difliculty was encountered in bleeding off sufiicient steam to avoid carryover of coal out the far end of the coking chamber during the charging operation.
As in the case of the modification of FIGURE 4, that of FIGURE 5 is provided with steam line 35 having branches 36 leading to jet nozzles 37 fiow through each of which is controlled by a valve 39. The jet nozzles 37 inject jets of steam at sonic or supersonic velocities into the flowing mixture of coal and steam to propel the latter through the pipeline and to replace at least some of the steam bled off, in the same manner as described above with respect to the modification of FIGURE 4.
In FIGURE 6 the pipeline 27 is provided with a branch line 71 through which a portion of the steam-coal mixture ows tangentially into a cyclone separator 72. This separator has a cylindrical upper portion 73 and a downwardly tapering conical portion 74. The latter is provided at its lower end with a circular opening or port 75 communicating with the upper end of a return conduit 76 leading down to and communicating with the interior of pipeline 27 through an opening 77 formed in the latter.
The opening 75 serves as a discharge port through which the collected coal particles indicated by the reference letter C are returned through return conduit 76 to the mixture flowing through pipeline 27. Discharge port 75 is normally closed by a closure plug 78 having a lower conical surface 79 adapted to engage the periphery of discharge port 75 so as to close the latter when plug 78 is in its lowermost position.
The upper end of closureplug 78 is connected to the lower end of a vertical rod 79 having its upper end con: nected at 81 to the movable core or armature 82 of a solenoid 83 and comprising a coil 84 into which armature 82 is drawn :by the electromagnetic field when coil 84 is energized. Thisv energization is effected periodically by an automatic timer switch 85 which supplies current to solenoid coil 84 through leads 86, 87 at predetermined intervals. Armature 82 is normally held in a lower position with respect to coil 84 by a spring 88 connected at its lower end to armature 82 and at its upper end to a bracket 91 mounted on solenoid 83.
The upper end of cylindrical portion 73 of cyclone separator 72 is covered by a horizontal plate 92 having a central opening 93 through which extends a vertical tube 94. The latter is provided at its upper end with a flange 95 to which is secured by bolts 96 an interchangeable orifice plate 97 having therein a Ibleed-ofi? orifice 98. Rod 79 extends upwardly through orifice 98. Reciprocatory Imotion of rod 79 effected by energization and deenergization of solenoid 83, exercises a cleaning action on the orifice 98 and maintains the latter substantially free of coal particles which otherwise obstruct the fiow of bleedoff stream therethrough. The rate of discharge of bleedof steam may be controlled by selectively varying the size of orifice 98. That is, orifice plate 97 can be removed and replaced with a different plate having an orifice of a larger or smaller size to vary the rate of bleed-ofi, as desired.
The use of other servomechanisms such as thrusters etc. would serve as well as the solenoid mechanism described above.
The lower edge of tube 94 is tapered at 99 to coact with the tapered surface 101 at the upper end of closure plug 78 when the latter is in its raised position. Engagement of surface 101 with edge 99 closes off the bottom of turbe 94 and thereby shuts off fiow of bleed-off steam through orifice 98. Conduit 71, it will be noted from FIGURE 6, extends from port 102 in pipeline 27 upwardly to the upper region of separator 72 communicating with a coal-steam entry port 103 tangentially positioned in the side wall of the upper cylindrical portion 73 near the top thereof as shown in FIGURE 6.
As the coal-steam mixture fiows through pipeline 27 in a direction indicated by arrow 104 a portion of the mixture flows upwardly through conduit 71 as indicated by the arrow in conduit 71 and flows through the entry port 103 tangentially into the top of cyclone separator 72. Centrifugal forces thus generated act to separate the coal particles from the steam. The separated coal particles collect at C in the conical lower portion 74 of separator 72. Closure plug 78 is normally in its lowermost position to close discharge port 75 and thereby prevent the collected particles C from fiowing downwardly through return conduit 76. The separated steam flows upwardly through tube 94 and discharges to the atmosphere through bleed-off orifice 98 which is 4maintained clear by the reciprocatory movement of rod 79 therethrough. Orifice 98 controls not only the bleed-off rate of the steam but also the amount of coal-steam mixture withdrawn from the pipeline. Utilization of an orifice plate having the necessary size orifice gives the desired rate of withdrawal from the pipeline into the cyclone separator and bleed-off of steam.
The expanded steam is thus continuously bled off and the coal particles are collected at the bottom of separator 72 until solenoid 83 is energized by automatic timer 85, at which time the electromagnetic field of solenoid 83 acts upon armature 82 to raise the latter into coil 84 and thereby pull closure plug 78 upwardly to its uppermost position where discharge port 75 is opened and the lower end of tube 94 is closed. The coal particles C collected at the bottom of separator 72 are then free to fall through discharge port 75 and return conduit 76 back into the fiowing mixture within pipeline 27. After a predetermined time interval sufiicient for the collected particles to flow through discharge port 75, timer deenergizes solenoid 83 permitting closure plug 78 to move downwardly back to its lowermost position under action of spring 88 closing discharge port 75 and the cycle is then repeated at periodic intervals. Timer 85 can be adjusted to effect periodic opening of port 75 at time intervals to avoid excessive accumulation of coal particles in separator 72.
I et propulsion of the coal-steam mixture through pipeline 27, in FIGURE 6, is effected by the jets of superheated steam introduced through jets 37 as hereinabove described in connection with the embodiments of the invention of FIGURES 1 to 5, inclusive.
In the modification of FIGURE 7 the cyclone separator 106 has a discharge port 107 formed in the lower end of conical portion 108. Port 107 is in direct communication with an opening 109 in the wall of pipeline 27. Closure plug 111 is of conical configuration and tapers upwardly to an apex which is connected to the lower end of a rod 112 extending upwardly through hollow tube 113 and through a bleed-off orifice 114 formed in an interchangeable bleed-olf plate 115. The upper end of rod 112 is connected to the apex of a downwardly tapering bleed-off plug 116 which has its upper portion connected to a second rod 117 which in turn has its upper end connected to the armature 118 of a solenoid 119 having a coil 121. Armature 118 is normally maintained in an upper position projecting outwardly of coil 121 by a spring 122 secured to a bracket 123 mounted on solenoid 119.
Opening 109 tapers upwardly so as to coact with the control surface of plug 111 when the latter is in its uppermost position thereby closing off opening 109 and discharge port 107 to prevent flow therethrough of coal particles which collect at C as separator 106 separates them from the coal-steam mixture entering through conduit 124. The latter is connected tangentially to upper cylindrical portion 125 of the cyclone separator. The ,separated gas, relatively free of coal particles, flows upwardly through tube 113 and discharges to the atmophere through bleed-off orifice 114. The latter is tapered downwardly to coact with bleed-off plug 116 when the latter is in its lowermost position to close bleed-olf orifice 114. This occurs at periodic timed intervals determined by timer 126 which automatically energizes solenoid coil 121 to lower armature 118 against the action of spring `122 thereby lowering bleed-off plug 116 into its closed position and lowering closure plug 111 into its open posi tion permitting the collected coal particles C to `fall downwardly through discharge port 107 into the coal-steam mixture flowing in pipeline 27.
In the FIGURE 7 modification, when orifice 114 is closed by plug 116, pressure builds up in separator 106. This pressure aids in effecting return of the coal particles from the separator to the pipeline. In the FIGURE 7 modification the steam is vented periodically to the atmosphere or other suitable disposal point, i.e., only when orifice 114 is open which is the case during the major portion of each cycle of operation. Orifice 114 is closed only momentarily to effect return of coal particles to the pipeline. It is closed often enough to prevent excessive accumulation of coal particles in the base portion of the separator 106. Optimum cycle of opening and closing orifice 114 and closing and opening return port 109 will depend on the pressure conditions employed. The timer 125 can, of course, be adjusted to give the desired time cycle.
The number and type of bleed-off devices employed in any given pipeline and the spacing thereof in the pipeline will depend on the length of the pipeline, the pressure conditions employed within the disclosed range and the temperature of the superheated steam. The number should be such as to bleed-off enough steam substantially free of solids, at points spaced apart along the length of the pipeline to maintain the steam velocity within the pipeline within relatively narrow limits, say from 50 to 200 feet per second and to produce at the point of charging each coking chamber, a relatively high coal to carrier gas weight ratio at a relatively low pressure.
While control of the coal steam weight ratio can be effected by venting steam from the pipeline at one or more points spaced from the discharge end of the pipeline branches leading into the coking chambers, it is preferred to control the coal to steam weight ratio of the mixture entering the coking chamber to facilitate disentrainment of the coal particles from the steam within the coking chamber by providing a venting unit in the pipeline or a branch therefrom just prior to the point of discharge into the coking chamber. FIGURE 1 shows one such venting unit at B in the form of a curvilinear portion 51. In FIG-URE 8 main 28 (FIGURE 1) which extends along the length of the battery is provided with branches 28a, leading to a cyclone separator 28h. Each charging hole of the battery is equipped with such cyclone separator. Steam is vented from the cyclone separator through vent line 28C and the coal particles discharged from exit port 28d into the charging hole.
The bends or elbows of the pipeline are the portions thereof which wear most rapidly, i.e., the portions where maximum wear takes place. FIGURE 8 discloses an elbow construction which minimizes, if not completely avoids, the effect of wear of the elbow. In this figure 27b is an elbow or curved portion of the pipeline comprising the elbow or curved portion 27c of the pipeline enclosed in a sleeve 27d concentric with the curved portion 27e. This sleeve 27d extends the full length of the curved p0rtion 27C and has its ends sealed to the pipeline by closure plates 27e and 27f, These plates can be welded or otherwise sealed to the outer periphery of the pipeline and the ends of sleeve 27d to provide an annular space 27g surrounding the curved portion 27e. Space 27g can be filled with the coal particles S to be transported during the fabrication fo the pipeline or just prior to placing the pipeline in operation or left empty to become filled should wear of the walls of curved portion 27c take place with formation of one or more openings 27h through which the coal tiows into space 27g. The layer 27i of coal particles S thus formed provide a protective layer for the walls of sleeve 27d minimizing if not completely preventing erosion thereof.
The mode of operation of the various modifications of this invention should be evident from the above description. The flowing stream of mixture of coal particles and steam is propelled through the pipeline by the jets of steam introduced at closely spaced points along the length of the pipeline at sonic or supersonic velocities to impart impulses or momentum to the mixture in the direction of iiow and thus maintain continuous fiow of the mixture. At least a portion of the carrier gas is vented to control the pressure and the coal to steam weight ratio, preferably by subjecting the mixture to centrifugal force at at least one intermediate point along the length of the pipeline to separate coal particles from the steam and produce a body of steam substantially free of coal particles, which body or a portion thereof is vented, as herein disclosed.
In the transportation of coal particles for charging the coking chambers of a battery, as shown in FIGURE 1 at B, preferably at least one venting or bleed-olf device is positioned following the feed main 28 in the conduit leading into the discharge conduit 29, one individual to each coking chamber. In this way the coal entering the coking chamber has a high coal to steam weight ratio, desirably about pounds of coal per pound of steam. This facilitates disentrainment of the coal particles from the steam in the coking chamber, prevents carryover of coal particles into the collector main, and speeds up the charging.
The steam employed to impart the impulses or momentum to the coal and effect its flow into the coking chambers, aids the charging. The steam atmospheres surrounding the hot coal particles entering the hot coke oven prevent the hot coal from flash coking. With the relatively high coal to steam weight ratio as the coalsteam mixture is introduced into the coking chamber rapid disentrainment of the coal from the steam takes place; the steam exits through the gas off-take into the collector main and the coal accumulates in the coking chamber to form the desired charge.
While it is preferred to have a multiplicity of closely placed steam jets along the length of the pipeline as herein disclosed, the invention is not limited thereto. With the hot coal-steam mixture introduced into the inlet of the pipeline with the coal dispersed in the steam, ow of the coal under the pressure of the steam introduced at the inlet end where the pressure is high enough, say of the order of 4 to 50 p.s.i.g., takes place to the branches from the pipeline leading into the coking chambers, steam being vented at or near the point of introduction of the mixture into the coking chambers to obtain the high coal to steam weight ratio and low pressure of the coal-steam mixture at the point of introduction of each charge into the coking chambers.
As noted, the preferred embodiment of the invention is in the transport of hot coarsely comminuted preheated particles of coal from the preheater to the coking chambers of a coke oven battery to effect the charging thereof. The invention, however, is not limited to this preferred embodiment. It can be used to convey coal from a coal drying plant to the point of consumption and can also be used for conveying other materials than coal; it is especially valuable in the conveyance of hot coal. In uses other than the charging of the coking chambers of a battery, instead of steam and coke oven gas, other carrier gases inert to the solids conveyed can be used, eg., nitrogen and other inert gases.
While preferred embodiments have been disclosed herein and illustrated in the drawings, it will be understood that this invention is not limited to this disclosure, including the showing of the drawings, because many variations and other modifications will occur to those skilled in the art.
What is claimed is:
1. A method of charging the coking chambers of a coke oven battery with hot coarsely comminuted coal particles comprising, introducing the coal particles and a carrier gas selected from the group consisting of steam and coke oven gas under superatmospheric pressure into a pipeline; eiecting flow of the hot coal through the pipeline under the 4influence of the pressure of the carrier gas, While holding the coal to carrier gas weight ratio from 20 to 150; controlling the pressure and the coal to carrier gas weight ratio of the mixture of hot coal and carrier gas in the pipeline by venting carrier gas from the pipeline at at least one point along the length thereof to obtain at the point of charging each coking chamber a relatively high coal to carrier gas weight ratio at a relatively low pressure not exceeding 2 p.s.i.g.; and successively charging the coking chambers of said battery with said mixture of hot coal and carrier gas having a relatively high Weight ratio of coal to carrier gas at a relatively low pressure.
2. The process of claim 1, in which the venting of the carrier gas is effected by subjecting the mixture of hot coal and carrier gas at a point just prior to introduction into a coking chamber to centrifugal force to separate the hot coal from the carrier gas, a portion of the carrier gas thus separated is vented into a coking chamber other than the one being charged, the coal to carrier gas weight ratio of the mixture introduced into the coking chamber is in the range of 20 to 500 to l and the pressure of the coal-carrier gas mixture at the point of introduction into the coking chamber does not exceed 2 p.s.i.g.
3. A method in accordance with claim 1 of charging the coking chambers of a coke oven battery with hot coarsely comminuted coal particles comprising, introducing the coal particles and steam into a pipeline, injecting jets of steam at at least sonic velocities at closely spaced points along the length of the pipeline in the direction of its length to propel said coal through the pipeline, subjecting at least a portion of the coal-steam mixture to centrifugal force at at least one intermediate point along the length of the pipeline to separate coal particles from the steam and produce a body of steam substantially free of coal particles, and withdrawing steam substantially free of coal particles from said body of steam.
4. A method in accordance with claim 1 of conveying coal particles, comprising introducing a coal-steam mixture into a pipeline, jetting steam into said pipeline at a plurality of closely spaced points along its length and in the direction of its length and at supersonic velocities, flowing the coal-steam mixture through a curvilinear path at a plurality of spaced points along the length of the pipeline and thus subjecting the coal particles in said mixture to centrifugal force to effect separation thereof from the main body of steam and produce contiguous to the inner wall of said curvilinear path closest to the center of curvature of said path steam substantially free of coal particles, and withdrawing said steam substantially free of coal particles from the pipeline.
5. A method of conveying hot coal particles comprising, introducing hot coal particles and steam into a pipeline, jetting steam into said pipeline at a plurality of closely spaced points along its length and at supersonic velocities, flowing the coal-steam mixture through a curvilinear path of large radius of curvature relative to the radius of the pipeline at a plurality of spaced points along the length of the pipeline and thus subjecting the coal particles in said mixture to centrifugal force to elect separation thereof from the steam and produce contiguous to the inner Wall of said curvilinear path closest to the center of curvature of said path a body of steam substantially free of coal particles, and withdrawing said steam substantially free of coal particles from the pipeline, the number of said spaced points along the length of said pipeline having said curvilinear path and from which steam substantially free of solid particles is withdrawn being correlated with the amount of steam supplied to said pipeline so that excessive velocities in the pipeline are avoided and at the exit end of the pipeline a high weight ratio of coal to steam within the range of from 20 to 500 pounds of coal per pound of steam is obtained.
6. A method in accordance with claim 5 of conveying coal particles comprising yintroducing a coal-steam mixture into a pipeline, jetting steam into said pipeline at a plurality of closely spaced points along its length and at a supersonic velocity, removing a side stream of said mixture from the pipeline, subjecting said side stream t0 centrifugal force to separate the coal particles from the steam, venting the steam thus separated from the coal particles, and returning the coal particles to the pipeline.
7. The method of charging the coking chambers of a coke oven battery which comprises conveying coal particles mixed with steam through a pipeline while holding the coal to steam weight ratio from 20 to 250 by jetting steam into said pipeline at a plurality of closely spaced points along the length of said pipeline to propel the mixture through the pipeline, flowing said mixture through a curvilinear path at a point near the exit end of said pipeline to subject the coal in said mixture to centrifugal force to eilect separation thereof from the steam and produce contiguous to the inner wall of said curvilinear path closest to the center of curvature of said path a body of steam substantially free of coal particles, venting said steam substantially free of coal particles from the pipeline thus producing at the exit end of said pipeline a dense mixture having a high coal to steam weight ratio and feeding said dense mixture into a coking chamber to be charged to produce a charge of coal therein to be coked.
8. A method of conveying coarsely comminuted solid particles comprising, introducing the coarsely comminuted solid particles admixed with a carrier gas under pressure into a pipeline, and while holding the solid particles to carrier gas weight ratio from 20 to 150, jetting a carrier gas into the pipeline at closely spaced points to aid in the flow of the solid particles through the pipeline, subjecting at least a portion of the mixture of solid particles and carrier gas during ow of the mixture through the pipeline to centrifugal force to separate the solid particles from the carrier gas and produce a body of carrier gas substantially free of solid particles and venting said body of carrier gas substantially free of solid particles to discharge from the pipeline carrier Igas thus controlling 15 i 16 the velocities of the solid particles gas mixture within the 1,597,438 8/ 1926 Ennis SO2-*64' pipeline. 1,783,983 12/ 1930 Runge 201--42 9. The process as defined in claim 8, in which the iets 2,149,056 2/ 1939 Klx 302-59 of carrier -gas are introduced into the pipeline at super- 2,794,686 6/1957 Anselman et al 302--24 sonic velocities. 5 3,047,473 7/1962 Schmidt 20l31 References Cited NORMAN YUDKOFF, Primary Examiner. l UNITED STATES PATENTS D. EDWARDS, Assistant Examiner.
266,973 11/1332 Conklin 3oz- 23 10 U-S- Cl- X-R- 545,013 3/1895 Dodge. 201--40; 302-24 1,350,337 8/1-920 Rhodes et al. 201-37 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,432 398 March 1l, 1969 Lawrence D Schmidt It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:
Column 14, line 45, "250 should read 150 Signed and sealed this 31st day of March 1970.
WILLIAM E. SCHUYLER, JR.
Commissioner of Patents Edward M. Fletcher, Jr.
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|U.S. Classification||201/38, 201/40, 406/95|
|International Classification||B01J8/18, C10B31/00, F23K3/00, B65G53/58|
|Cooperative Classification||B01J8/18, B65G53/58, F23K2203/006, C10B31/00, F23K3/00|
|European Classification||F23K3/00, C10B31/00, B01J8/18, B65G53/58|
|Apr 15, 1982||AS||Assignment|
Owner name: KRUPP WILPUTTE CORPORATION
Free format text: CHANGE OF NAME;ASSIGNOR:KKW CORPORATION, A DE CORP.;REEL/FRAME:003979/0664
Effective date: 19820320
|Apr 5, 1982||AS||Assignment|
Owner name: KKW CORPORATION, 152 FLORAL AVE., MURRAY HILL, NJ.
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:COALTEK CORPORATION;REEL/FRAME:003979/0488
Effective date: 19820319