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METHOD AND APPARATUS FOR HANDLING AND INDIRECTLY COOLING COKE
FIELD OF THE INVENTION The present invention relates generally to a system for handling coke in an environmentally friendly manner by substantially eliminating pushing and quenching emissions, and more particularly concerns a coke box and carrier which receives the hot coke from the oven, transports it to an indirect cooling station and, when cooled, transports the coke cake to and discharges it at an environmentally sound receiving station in a cost effective manner.
BACKGROUND OF THE INVENTION
In conventional coke ovens, coal is heated to approximately 2000°F. for approximately 20 to 40 hours to drive off all volatile gases and other materials which account for approximately 30% of the weight of the coal. The still hot and burning coke is then pushed out of the oven, cooled by quenching, and placed on a wharf to be carried away by appropriate transport equipment. During both pushing and quenching, uncontrolled emissions are highly noxious and very detrimental to the environment and should be eliminated to the extent possible. It should also be realized that pushing emission control and quenching emission control conventionally are totally separate systems and it is possible to have one without the other. In fact, in North America there are no commercial dry quenching systems with effective environmental controls because of the age of the coke ovens and the tremendous cost of such installations. In Europe, most coke ovens are required to have dry quenching systems and all new ovens that are being considered worldwide must utilize dry quenching of the coke.
In typical coking systems of the type in use in North America as mentioned above, the hot coke is pushed out of the oven and dropped into a railcar or other suitable carrier which transports the hot coke to a wet quenching station. It will be understood that dropping the coke, especially when hot, generates large amounts of particulate matter and further burning of the coke takes place until the coke is quenched. Wet quenching uses thousands of gallons of water, a substantial portion of which is turned into steam and immediately released to the atmosphere. The steam picks up many chemicals detrimental to the environment and releases them into the atmosphere.
An alternative to wet quenching is dry quenching and has recently been adopted and or required in some countries. In dry quenching, a railcar carries a
2 box which captures the falling coke from the oven. The box containing the hot and still burning coke is then taken to a tall silo, lifted up to the top of the silo and the coke is again dropped, this time into the silo. The coke is then cooled by inert gases passing up through the coke in the silo. The heat from the inert gas, in some cases, is recovered and used for other purposes. However, the value of the recovered heat seldom pays for the extremely high capital cost and operating cost of such dry quenching systems.
Another serious disadvantage of such dry quenching systems is the abrasion the coke is subjected to as it works itself down from the top of the silo to the bottom of the silo. This reduces the yield of the usable coke. Coke to be of value to the steelmaking and foundry industries must be in large chunks. Small particles or coke "breeze" which is generated by the physical manipulation and degradation of the coke in the cooling process is of much less value.
In all of the above cases, the cost of containing the pollution generated as the coke falls and is moved from place to place is very high. In the past, many types of pushing emission control systems have been proposed to contain this pollution. However, a substantial number of these systems still have to be replaced because they do not meet the increasingly stringent environmental requirements. Indeed, many systems now in operation do not meet environmental standards, but are allowed to operate because closing them would have a potentially serious negative commercial impact. Moreover, due to the limited technology presently available, environmental standards in place are unnecessarily low, and need to be replaced with more environmentally sound and reliable standards. In addition, virtually all present systems are extremely expensive to install and operate.
It will also be appreciated that commercially operating coke ovens must have backup equipment for transporting the coke from place to place, even when their environmental control systems are inoperative, or being repaired. This is because the ovens themselves must continue to operate even without appropriately functioning environmental controls for handling and cooling the coke. This, of course, also negatively impacts the environment.
SUMMARY AND OBJECTS OF THE INVENTION
The improved method and apparatus for handling and indirectly cooling coke in accordance with the present invention substantially eliminates all the problems experienced by other systems, simply by not creating them in the first
3 place. Rather, the hot coke is never exposed to the atmosphere, never physically disturbed, and always kept in its original "cake" form as it was in the oven, even after it is dry cooled and then placed, still in its original "cake" form, on the coke wharf. It is anticipated that the coke handling and indirect cooling system of the present invention will have a substantial return on investment, where other systems are very capital intensive, have no payback, have very high operating expenses, and less than desirable reliability. In addition, although revenue with conventional systems will continue to be diminished because of their tendency to reduce yield, the system of the present invention is expected to show very positive economic results.
The improved, environmentally sound and cost effective coke handling and indirect cooling system of the present invention uses a coke box having an interior approximately the size and shape of the coke oven. The box which is effectively sealed against the coke oven during the push is preferably covered by flowing water during the push and during the cooling cycle. A carrier moves the box to a cooling rack and places the box into the rack. The carrier then moves to an adjacent cooled box, removes it from the cooling rack, transports the box to an environmentally sound receiving station and discharges the coke from the box into the receiving station . The method and apparatus of the invention are environmentally friendly, improve the quality of the coke, improve the yield of each push, and increase the size of the coke, which is also an advantage. The invention also has the potential to reduce the time the coke needs to spend in the oven thereby increasing the productivity of the coke ovens. In addition, there is also a potential of treating the coke as it is cooled in the box to further improve the quality of the coke.
It should be realized that many existing ovens are in very confined areas and do not have space for a cooling rack of the preferred type and in these instances wet quenching must be used. The present invention is a vast improvement over existing pushing emission systems which may require large bag houses, large suction fans, large exhaust ducts and special valves for each oven. All these systems are very costly to construct and maintain and generate pollutants in themselves. Furthermore, they are not as effective environmentally as the system of the present invention when pushing is taking place. In addition, the preferred system disclosed herein is more reliable. For example, the system of the present invention is not a fixed system. It provides for extra carriers and coke boxes for off-line repair and maintenance which fixed systems do not have,
4 causing them to be inoperative when repair and maintenance is required. The system of the present invention also produces higher yields, because the hot coke is not dropped. Rather, it will be slid, largely intact, onto a receiving surface and thus greatly reduces particulate matter emissions. To further reduce these emissions, a receiving chute can be added. Moreover, coke losses from burning, even when wet quenching is required, will be a small fraction of the losses experienced with conventional pushing emission systems.
Even in those situations where slow dry indirect cooling is not possible, and wet quenching is the only option, it will now be possible to "slow" wet quench the hot coke. By contrast, wet quenching in a traditional quench tower must be accomplished in only one or two minutes because the quench car that contains the hot coke must continue the cycle and quickly return to the coke oven. As a consequence, it is nearly impossible to contain the vast amount of steam and associated pollutants that are generated by the thousands of gallons of water used to quickly quench the hot coke. However, by using the coke box and carrier of the present invention to transport the hot coke to a receiving station with two wharves, one on each side of the receiving box, it is possible to achieve "slow" wet quenching of the hot coke of up to 20 minutes and still accommodate a 10 minute push cycle from the ovens. Thus, providing up to 10 minutes to "slow" wet quench the hot coke should enable containment of a very high percentage of the traditional quenching pollutants even when slow dry indirect cooling with all of the additional benefits of the present invention is not an option.
These and other features and advantages of the invention will be more readily apparent upon reading the following description of a preferred exemplified embodiment of the invention and upon reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a schematic perspective view showing the general arrangement of a coke oven battery, cooling rack, and receiving station with which the coke box and carrier of the present invention are associated;
FIG. 2 is a small perspective view of the entry end of the coke box carrier shown in FIG. 1 ;
FIG. 2a is an enlarged, fragmentary perspective view, of the portion substantially within circle A of Fig. 2, showing the mechanism that drives the coke box into and out of the cooling rack and how the box is moved fore and aft in the carrier of FIGS. 1 and 2;
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FIG. 3 is a small perspective view of the opposite end of the coke box and carrier shown in FIG. 1 ;
FIG. 3a is an enlarged, fragmentary perspective view of the portion substantially within circle A of FIG. 3 showing the mechanism used to push the coke from the coke box into the receiving station;
FIG. 4 is a schematic perspective view somewhat larger than FIG. 1, showing the carrier at the receiving station with the pushing mechanism in the operative position and the coke being pushed into the receiving box;
FIG. 5 is a view similar to FIG. 4 showing the carrier leaving the receiving station with the pushing mechanism rotated to the transport position as well as the receiving box in a tipped position with a coke cake sliding out of the receiving box onto the coke wharf;
FIG. 6 is a schematic perspective view of the coke box and carrier with an alternative pushing mechanism supported on its own carrier; FIG. 7 is a side elevation of the coke box, carrier and pushing mechanism of FIG. 6 showing the coke being pushed from the coke box onto a receiving wharf;
FIG. 8 is a view similar to FIG. 4 showing a plurality of water jets on the receiving surface of the coke wharf; FIG. 9 is a view similar to FIG. 5 showing the addition of a plurality of water spray nozzles directed downwardly onto the coke cake on the receiving surface of the coke wharf;
FIG. 10 is a schematic perspective view of the coke box and carrier, somewhat larger than FIG. 4 but from the opposite end, showing the coke being pushed onto an alternative receiving chute disposed below a plurality of water spray nozzles to wet quench the coke, if necessary; and
FIG. 1 1 is another schematic perspective of the coke box and carrier, similar to FIG. 6 but from the opposite end, showing the coke being pushed from the opposite end of the coke box into an alternative receiving station located on the opposite side of the carrier rail tracks from the coke ovens.
While the invention will be described and disclosed in connection with certain preferred embodiments and procedures, it is not intended to limit the invention to those specific embodiments. Rather it is intended to cover all such alternative embodiments and modifications as fall within the spirit and scope of the invention as disclosed herein.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning now more specifically to the accompanying drawings, the present invention is comprised of a carrier 100 containing a main frame structure 1 supported on rail wheels 2 rolling on ground rails 3 precisely located in front of a battery of coke ovens 103. The rails 3 are also used in moving and positioning a coke box 8 on the carrier 100 in front of one of the coke ovens 103, a cooling rack 104, and a receiving station 105. The ground rails 3 maintain the proper height and distance of the carrier 100 from the ovens 103. The lateral position of the carrier 100 is controlled by other suitable means for selectively moving the carrier along the rails 3. It will be understood by those skilled in the art that a door machine, schematically illustrated at 18 in FIG. 1 , is used to remove the door from the coke oven 103 before the coke is pushed from the oven into the box 8 and to replace the door after the push. The present invention can work with or without the door machine 18 as an integral part of the carrier 100. As best seen in FIGS. 4 and 5, the main frame structure 1 carries a large water tank 5 with a pump and a vertical pipe 6 running to the top of the frame structure 1 above the box 8. The pipe 6 is connected to a horizontal pipe 7 which distributes water over the top of the hot coke box 8, allowing the water to flow down over the box 8, cooling the box and the hot coke inside. The water then drains back into the tank 5 and is recirculated.
The coke box 8 has two doors. On the front of the box 8 is a guillotine door 10 and on the back is a swinging door 11. When closed, both doors 10 and 1 1 are tightly sealed to the respective front and rear ends of the box 8. The door 11 on the rear of the box 8, preferably has a one way vent 12 that allows volatile gasses, that can still be given off by the coke for a period of time after the push, to escape and be ignited. It will be understood that the ignited gas is substantially completely burned and is not environmentally detrimental. Furthermore, since no emission can escape during pushing, and some coking can continue to take place in the box, a reduction in the time the coke is in the oven can be utilized to increase the production of the ovens.
The guillotine door 10 at the front of the box 8 is opened and closed by actuating arms 38 connected to the main frame 1 and controlled by cylinders 39. The guillotine door 10 preferably contains locating slots 49 and as the box 8 moves into position against the oven door jamb 22, or the receiving box jamb 36, the door actuating arms 38 will index the guillotine door slots 49 with appropriate locating lugs on the respective door jambs. The door 10 can then be opened and
7 closed as required. When the coke box 8 is retracted back into the main frame 1 , the actuating arms 38 are rotated back far enough to clear the door machine 18 as the carrier travels on the rails 3 in front of the ovens 103.
As shown in FIG. 3 A, the coke box 8 preferably has four sets of rail wheels. The outer set 13 and the inner set 14 both allow the box 8 to be freely moved fore and aft on a pair of rails 4 within the carrier frame 1 by an advancing cylinder 15 disposed under the box 8. (See FIG. 2A). As mentioned above, it is desirable for the carrier 100 to be able to pass the door machine 18, located on a bench 19 in front of the ovens 103. Therefore, the box 8 must be pulled back at least six feet from the face of the ovens 103.
The front outer set of wheels 13 on the box 8 are disposed beyond the support of the main frame box rail 4 when a "dragon tongue" 20 made up of items 16, 17, 24, 25, 26, 40 and 41 selectively advances toward any one of the ovens 103, cooling rack 104, or the receiving station 105 shown in FIG. 1, or an alternative receiving chute 58 as shown in FIG. 10. The "dragon tongue" 20, however, is not designed to carry a vertical load traveling in and out from the envelope of the carrier 100. The inside set of wheels 14 are, therefore, required to support the box 8.
The advancing cylinder 15 is preferably connected to an advancing structure 17 which contains a lock cylinder 40 and a box lock 16 that locks onto the box 8. The actuator 15 controls the fore and aft movement of the box 8 relative to the main frame 1 as long as the box lock 16 is in place. During receiving and discharging coke, the "dragon tongue" 20 is also used to transmit horizontal forces to the advancing cylinder 15, when the box lock 16 is in place. It will be understood that there are three basic box 8 positions when the box lock 16 is in place. First, when the advancing cylinder 15 is fully retracted, the box 8 is drawn into the carrier 100. This position is used when the carrier 100 is moving and allows the box 8 and carrier 100 to pass freely by the door machine 18.. The second position places the box 8 and its associated box seal tightly against the oven door jamb 22 in position to receive the coke push from the oven 103. This position is also used when the box 8 is against the receiving station jamb 36. The third position occurs when the advancing cylinder 15 is fully extended. This positions the box 8 at the cooling rack 104 where a lift cylinder 25 is extended against a cooling rack reaction pad 55 thereby forcing a drive roller 24 against the box 8. The lock 16 is then disengaged and a drive motor 26 and the roller 24 drive the box 8 forward into the rack 104. The process is reversed when
8 the cooled box 8 is pulled back into the carrier 100 from the rack 104. To support the "dragon tongue" 20, which is not intended to support the weight of the box 8, two sets of rollers 35 are positioned on the end of the main frame 1 and engage opposite sides of a supporting rail 41 on the "dragon tongue" 20. Support rails 37 are provided at the cooling rack 104.
When at the receiving station, both doors 10 and 1 1 will be opened and the cooled coke can be pushed out in either direction by a ram 28. The ram 28 can be either part of the carrier 100 as shown in FIGS. 1, 3-5 and 8-10 or separate from and located at either end of the carrier as shown in FIGS. 6, 7 and 11. In the preferred embodiment, the ram 28 is connected to the rear of the carrier 100 and the coke can be conveniently pushed out of the box 8 at any location. It will be understood that if the ram 28 is rigidly fixed to the carrier 100, it will almost double the length of the carrier 100 and the area required for the carrier to operate. Pursuant to the present invention, by pivoting the ram 28 and ram drive structure 29, which includes ram support rollers 48, a ram drive motor 51, rack gear 52, pinion gear 53, and 90 degree drive for pinion gear 54, by 90 degrees or more relative to the mainframe 1 of the carrier 100, with a ram drive structure rotating cylinder 42, this extra working space can be eliminated.
In further accordance with the invention, as the ram drive structure 29 pivots, it will preferably open the sealed door 1 1 on back of the box. This is accomplished by two push arms 30 pivotally mounted on the ram drive structure 29. The push arms 30, in turn, contact and push two spring loaded arms 31 mounted on the box that carry the rear door 11. The springs 33, which hold the door tightly shut are overcome when the ram drive structure 29 is rotated. The two spring loaded arms 31 hold the door 1 1 on two door center mount bearings 32, one on the top and one on the bottom, which evenly apply force to the door 1 1 and the seal 21 when the door is shut against the rear of the box 8. It will be understood, of course, that alternatively, the door 1 1 can also be opened by independent means, which would be provided when the ram 28 is independently mounted as shown in FIGS. 6. 7 and 11.
At the receiving station 105, the front door 10 is opened as described above in connection with taking a push of coke from the oven 103. Then the ram 28, when in the position shown in FIG. 4, can push the hot or cooled coke cake 27 into the receiving box 34. The ram 28 is then retracted and rotated away as shown in FIG. 5 and the springs 33 close the door 1 1. The front door 10 can stay open as
9 the carrier 100 travels to the next oven 103 to receive a fresh charge of hot coke pushed from the oven.
The wharf receiving box 34, after receiving the cooled coke, is then rotated and the cool coke 27, still in its "cake" form, slides out onto the coke wharf 43 and will effectively stay in its cake form. There is an additional advantage to this procedure. The cool coke 27 can then be analyzed with appropriate optical or other sensing equipment which will be able to show just how each area of the respective oven 103 and cooling rack 104 is performing. On the next push, the receiving box 34 can be rotated to the opposite side for additional wharf capacity and the ability to analyze the coke which was in contact with the opposite side of the associated oven 103 and cooling rack 104. In the illustrated embodiment, the wharf receiving box 34 is mounted in the front by rollers 45 which are supported by a roller frame structure 46. On the back, it is supported by a center-mounted bearing 47 which takes both vertical and horizontal forces. Preferably, the wharf receiving box 34 can be rotated 120 degrees or more in each direction by two tipping cylinders 44 mounted on the wharf 43, or may be rotated by other power driven rotating means.
It is also the intent of this invention to provide for a pushing ram 28 mounted separately from the coke box carrier 100 in case there are special circumstances that would benefit from this arrangement. Such an alternative arrangement is shown in FIGS. 6 and 7 where the pushing ram 28 is mounted on a separate transport mechanism or carrier 107 supported by rail-engaging wheels 110 riding on a pair of rails 106 disposed parallel to the rails 3 which support the coke box carrier 100. Also, there are times that coke must be discharged onto a wharf 109 that will allow the coke to be picked up by a loader and placed into trucks for transport rather than by the belt off of the wharf. This can be done by either a ram 28 mounted on the carrier 100 or separately mounted on a transport mechanism 107 traveling on separate rails 106. FIG. 6 shows the position of the ram 28 prior to pushing the coke from the box and FIG. 7 shows the ram 28 extended substantially into the coke box to push the coke out onto the wharf 109. In certain instances it may also be necessary or desirable to supplement or even replace the indirect cooling of the coke in the cooling rack 104 with wet quenching of the coke on the surface of the coke wharf 43. For this purpose, a plurality of high pressure water jets 50 may be recessed in the surface of the wharf as shown in FIG. 8 so as to spray cooling water up through the coke "cake" 27 as shown in FIG. 9. Additionally, as also shown here, the upper surface of the coke
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"cake" may be sprayed with cooling water from a plurality of spray nozzles 52 supplied by a pipe or manifold 51 mounted above the wharf 43.
Due to the physical layout and other space limitations of the coking facility, it may be desirable to discharge the coke 'cake" 57 from the coke box 8 and turn the coke "cake" 57 from its substantially vertical position to a generally horizontal orientation. As shown in FIG. 10, the present invention accomplishes this type of discharge by means of a transition chute 58 secured to the coke box 8 so as to receive the coke "cake" 57 pushed by the ram 28 and turn the "cake" 57 through approximately 90° so that it exits substantially horizontally from the discharge end 56 of the chute 58. It will be understood that this type of discharge chute 58 may be used to reorient the coke "cake" after it is cooled in the cooling rack 104 or, alternatively, the coke can be wet quenched by suitable spray nozzles 54 mounted on a supply manifold above the coke "cake" 57 on the open slide portion 56 of the discharge chute 58. From the foregoing, it will be seen that a novel method and apparatus for handling and indirectly cooling coke has been provided which attains the aforementioned objects. When necessary due to space considerations, wet quenching may be used to supplement or replace the indirect cooling racks. Various other modifications of the embodiments in addition to those specifically illustrated and described herein will be apparent to those skilled in the art, particularly in light of the teachings of this invention. The present invention should not be construed as limited to the specific embodiments shown and described herein, but instead is intended to encompass such alternatives, as well.