Patent Application
20080271985
This invention relates to coke oven door implemented by hollow metallic door plug having bottom-less gas combustion space to provide heating function, which accelerates coking reaction of coal particles charged in the vicinity of coke oven door plug, gasifying of tar generated during coking and adhered to door and, at the same time, preventing charged coal particles enter into bottom-less combustion space of hollow metallic door plug.
Coke battery manufactures coke by heating coal particles by the heat supplied through heating walls on both sides of coking chamber of coke oven. Hot coke pushed out from coke oven includes poor quality coke generated in the vicinity of both ends of coke oven because of insufficient coking. This poor quality coke causes low yield of good quality blast furnace coke. This problem arises from existing refractory door plug, which usually has about 400 mm of thickness and is heated up to a high temperature during coking operation. Heated plug is exposed to the open air when door is extracted from its service position and looses heat by radiation. When door is put in service again temperature of door plug is lower than before and it causes a delay of coking of coal particles charged in the vicinity of door plug in next coking cycle.
To solve this problem, many heating type coke oven doors have been invented to accelerate temperature rise of coal layer in the vicinity of door plug by utilizing the sensible heat of high temperature gas generated in coking chamber as a heating agent. For example, Patent Document 1 discloses a “method for coking coal particles charged in the vicinity of high heat conductive metal wall of coke oven door plug by sending the generated hot coke oven gas to the gas passage through the vertical flue provided in at least one of the doors in contact with said coal charge and separated from the interior of the coke oven by the heat conductive metal wall constituting said door and moving part of said hot gas to an upper end region in contact with said partition wall therethrough by the ascending of said gas and the heat conductivity of the partition wall” and Patent Document 2 discloses a “coke oven door carrying on the inner side thereof a shield allowing passage of gases generated in the oven that comprises shielding members made up of spacers and coking plates”.
Known coke oven door structures, such as those shown in Patent Document 3 and Patent Document 4 disclose coke oven door, said Coking Plate, provided gas passageway from bottom to top of its hollow plug. A part of gas generated in coking chamber flows into the hollow space and then is ignited by properly placed ignition device. Necessary air or oxygen to burn the gas is supplied from outside of the door. Although this type doors, compared with those existing coke oven door using refractory plug, may have effects to increase coking speed of coal particles charged in the vicinity of coke oven door plug and decrease the generation of poor quality coke, but have not come to industrial use. Possibly this is because of several reasons such as quick distortion of “coking plate” structured by steel plates caused by cyclic rapid heating-cooling during door open-close operation, scratch damage of coking chamber brick wall by distorted “coking plate” and contamination of product coke by fragments of oven wall bricks generated by distorted coking plate scratching. In addition, maintenance of ignition control system for individual door of a coke battery consists of 50 to 80 ovens is not practical under the bitter operating condition of high temperature and dusty atmosphere. Moreover, gas pressure behavior in the period later than middle of a coking cycle is too complicated and unpredictable to follow.
The inventor, considering above-mentioned situation, developed a coke oven door having heating function comprising air supply nozzle having air delivery-end in bottom-less combustion space of hollow metallic coke oven door plug to burn coke oven gas generated in the coking chamber and coming into said bottom-less combustion space of hollow metallic coke oven door plug as shown in Patent Document 5 and Patent Document 6. Air volume to be supplied is neither controlled by means of electric nor manual system but automatically determined following the behavior of gas pressure in the bottom-less combustion space of hollow metallic plug by movement of specially designed valve. The structure of hollow metallic coke oven door plug consists of exchangeable metallic bars and supporting brackets mounted on the coke oven side surface of insulation boxes mounted on door body. Bars hang on supporting brackets mounted on said insulation boxes having certain pitches over the length of oven door giving narrow slits between each bar. Width of slit is large enough to let the gas generated in the coke oven flow into said bottom-less combustion space of hollow metallic door plug but not large as to allow charged coal particles enter into said bottom-less combustion space of hollow metallic door plug. The inventor, as shown in Patent Document 7 and Patent Document 8 (filed in Japan), also developed an air supply system equipped with a kind of check valve to protect the system itself from poor controllability caused by adhesion of viscous tar mist, small coal and/or coke particles suspended in the backward flowing coke oven gas. This system consists of a disk plate positioned at the top end of air intake pipe capable of moving up and down functioning as a check valve according to the gas pressure change in said bottom-less combustion space of hollow metallic door plug and additional device positioned between above-mentioned check valve and delivery end of air supply pipe for separating tar mist and small solid, coal and/or coke, particles. Above-mentioned additional device is an impingement type separator set inside of air supply pipe. This coke oven door raises the temperature of coal particle layer in the vicinity of coke oven door plug and, at the same time, makes said solid particles and tar adhering to the foot of door plug disappear by heat generated by burning coke oven gas flowing into said bottom-less combustion space of hollow metallic door plug through the slits of metallic bars by supplying necessary amount of combustion air from outside of coking chamber. It is known, however, that the gas pressure in coking chamber fluctuates all through the coking cycle with a considerably wide range from positive to negative pressure. These phenomena may cause backward flowing of gas accompanied by said small solid particles with viscous tar mist and also clogging of air supply system in spite of above-mentioned counter measures.
Patent Document 1: JP H3-40074 B
Patent Document 2: JP S61-49353 B
Patent Document 3: JP 2953319 B
Patent Document 4: JP H8-283735 A
Patent Document 5: JP 2004-99859 A
Patent Document 6: WO2004/007639A1(EP1533357A1)
Patent Document 7: JP 2004-276148
Patent Document 8: JP 2004-333740
The inventor, after a number of various tests and trials, concluded that it is possible to continue stable coke battery operation for a long time protecting above-mentioned check valve from contamination caused by viscous tar mist and said solid particles suspended in backward flowing gas by providing labyrinth type partitions installed in the air chamber unit between above-mentioned check valve and air supply pipe equipped with impingement type separator.
The present invention is based on the above-mentioned information. The outline of the invention is as follows. An air chamber unit having two functions is divided into two sections by labyrinth partition. One of said two sections contains check valve unit and the other contains separator that catches and separates mixture of tar mist and said solid particles. Air intake pipe is inserted into air chamber unit through bottom plate of said check valve unit section of air chamber. Spring supported check valve plate is set horizontally on top end of air intake pipe fitted vertically. This supporting spring has larger diameter than that of air intake pipe as to be inserted by air intake pipe. Air supply pipe is allocated in the opposite side section of said labyrinth partition. Air supply pipe goes down vertically through bottom plate of said separator unit section of air chamber. Impingement type tar mist and said solid particle separator is mounted in the tail part of air supply pipe. Tar mist and said slid particles caught by impingement flow down through vertical pipe and never stay around impingement. To protect check valve plate from contamination by tar mist and said solid particles completely, an appropriate resistance against backward gas flowing from inside of coking chamber is required. For this purpose each labyrinth plate has an opening at its corner having appropriate gas passage area to assure complete removal of tar mist and said solid particles. Check valve plate moves under the delicate balance of its own weight, supporting force of coil spring and gas pressure fluctuation. Said check valve plate shall keep its horizontal posture at any moment during operation. For that purpose at least one guide piece is provided to keep said check valve plate movement correctly in vertical direction. Above said check valve plate, a plate is provided as a stopper against excess jump-up of check valve plate. Another role of above-mentioned guide piece is to support this stopper plate. The lower end of coil spring is fixed on said air chamber bottom plate by a fitting ring. Another ring is fitted to lower surface of check valve plate to assure perfect contact between said check valve plate and top end of coil spring. Air supply pipe is connected to the line pipe that goes into above mentioned bottom-less combustion space of hollow metallic door plug. Thus this system composes a coke oven door that gives additional heat to charged coal particles under controlled combustion in the bottom-less combustion space of hollow metallic door plug.
In addition to the present invention, cylindrical cover hoods can be added to said air chamber unit. One having diameter larger than that of said check valve plate can be fitted above said check valve unit and the other having diameter larger than that of said air supply pipe can be fitted above tail end of said air supply pipe. Both hoods provide air/gas stagnant space for each section of said air chamber unit. Also impingement pieces can be fitted to inside of air supply pipe.
The present invention provides a coke oven door equipped with a system that sends necessary amount of air to burn coke oven gas that flows through slits of metal shield bars into said hollow space of said metallic door plug under simple actions and prevents excess air supply that causes temperature drop in the bottom-less combustion space and excess oxidation of coke in front of said hollow metallic door plug. Also the present invention provides very easy maintenance control for the system. Tar mist and said solid particles suspended in backward flowing gas from bottom-less combustion space of hollow metallic door plug caused by sudden fluctuation of gas pressure do not contaminate check valve plate because those contaminants are caught by such components as impingements, labyrinth partition and stagnant spaces provided in said air chamber unit. Under this condition check valve plate operates always satisfactorily and sends necessary amount of air to the bottom-less combustion space and accelerates coking reaction of coal layer in the vicinity of metallic door plug.
Details of this invention will be described by reference to the drawings.
Reference numeral 3 is an oven door structure that opens and closes an opening 4 of coke oven 1. The oven door structure 3 comprises a sturdy cast iron or steel frame 5, slide plate 6 on coke oven side of frame 5, flanges with knife-edge cross section 7 that contact to door jamb 8, seal plate 9 made of heat-resistant metal plate that works as a gas sealing member in conjunction with flanges 7, inner plate 10, heat-insulation box 12 filled with insulating material 11 such as alumina silicate, isolate, ceramic fiber and other conventional insulating materials and bottom-less combustion space 13 in the metallic door plug that projects into the opening 4 of coke oven.
Bottom-less combustion space 13 is so structured as to let coke oven gas generated from coal particles 2 charged in coke oven 4 flow easily into the bottom-less combustion space 13. Horizontal brackets 14 made of heat resistant steel mounted on heat-insulation box in such a manner as to partition the box into several spaces one on top of another. Shield bars 15 made of heat resistant steel are mounted on bracket 14 horizontally or vertically facing to the coke oven 1 and to coke oven heating walls on both sides having narrow slits or holes 16 to provide gas passage way for coke oven gas to flow into bottom-less combustion space 13 of the hollow metallic door plug structured as to be easily disassembled and reassembled. For horizontal shield bars, two types are acceptable. One has U-shaped plan view and the other has round-cornered quadrangular plain view. Both types have louver type vertical cross section providing louver plate sloping from inside edge facing to said bottom-less combustion space 13 down to front edge facing to charged coal particles 2 and to said coke oven heating walls on both sides.
Front edge of said shield bars are stacked up horizontally providing horizontal gas inlet slit between each bar. In this invention, required structure for bottom-less combustion space 13 in the hollow metallic door plug is to let gas generated in coke oven 1 flow into the bottom-less combustion space 13 of hollow metallic door plug. There is no limitation for structural design of hollow metallic door plug.
Reference numeral 17 is air chamber unit for controlling supply air to burn coke oven gas flowing into the bottom-less combustion space 13 of hollow metallic plug. Air chamber unit 17 is fitted to coke oven door 3 and the air supply pipe 44 is connected to the combustion nozzle 45 located in the bottom-less combustion space 13 of hollow metallic door plug. Air chamber unit 17 is a device to suck and send necessary amount of air to burn coke oven gas flowing into the bottom-less combustion space 13 of the hollow metallic door plug. Detail structure of air chamber 17 is as follows. Air chamber unit 17 is fitted to coke oven door 3. At least one air chamber unit shall be provided for different levels over the length of coke oven door. Reference numeral 18 denotes a latching device that strongly presses and fastens coke oven door 3 to the coke oven opening 4. Latching device 18 comprises compression springs, latching bar and fittings such as bolts and nuts and other fastening members. Coke oven door 3 is equipped with spring-loaded plungers 19 that freely move to and back to press flange members 7 engaged to seal-plate 9 against door jamb 8 to make tight sealing of coke oven opening 4. In this invention coke oven door 3 has two functions such as to open and close job of coke oven opening 4 and to burn coke oven gas that flows into the bottom-less combustion space 13 of hollow metallic door plug.
Each of
Air chamber unit 17 is divided into two parts, section (A) and section (B), by gas passage guide unit 24 as a partition placed in a voluntarily selected position. In section (A) air intake pipe 27 is fitted. The lower end of air intake pipe 27 is the air entrance 25. Top end of intake pipe 27 having horizontal edge 26 is the delivery end for sucked air. In section (B) air supply pipe 30 is fitted. Lower portion of air supply pipe 30 is the air delivery end 28 and upper portion is air suction end 29. In
When gas pressure in the bottom-less combustion space 13 in hollow metallic plug is positive, gas passage guide unit 24 reduces the pressure and velocity of gas flowing back to air intake pipe 27 via air supply pipe 30 or air delivery cup 32 in the air chamber unit 17 to clean backward flowing gas by catching and separating tar mist and said solid particles suspended in the gas. Gas passage guide unit 24 comprises, the guide plate 33 having a length shorter than distance between top plate 22 and bottom plate 21 of said air chamber unit 17 fixed on the bottom plate 21 or top plate 22 of said air chamber unit 17. When said gas passage guide unit 24 comprises at least two plates, each of said guide plate 33 providing opening at its corner as a gas flowing path 34 is fixed alternately to the top plate 22 or bottom plate 21 of air chamber unit 17. Guide plate 33 may have such cross section as flat, curved, waved or combination of such cross sections. Gas passage guide unit 24 is so formed as to let backward gas flow meanderingly into air chamber space 20 through guide plates 33.
In order to control the flow rate of air being supplied to bottom-less combustion space 13 of hollow metallic door plug, a check valve plate 35 is placed above the delivery end 26 of air intake pipe 27. Check valve plate 35 is kept in a floating position by a coil spring 36 having a diameter larger than that of air inlet pipe 27. Above check valve plate 35, a plate 37 is provided to assure the movement of check valve plate 35 within a limited range. Plate 37 is mounted on top of guide piece 38 standing on the ring bracket 39 fitted on middle portion of air intake pipe 27 or on the bottom plate of air chamber unit 17. Thus inside pressure of air chamber space 20 of this invention becomes positive when the gas pressure in bottom-less combustion space 13 becomes positive because of flow-in of coke oven gas into hollow metallic door plug. In the event of positive pressure in air chamber space 20, check valve plate 35 comes down pressing coil spring 36 down to the position to close the delivery end 26 of air intake pipe 27. On the other hand, when gas pressure in said bottom-less combustion space 13 becomes negative, pressure in said air chamber space 20 also becomes negative making check valve plate 35 float upward by the force of coil spring 36 and open the delivery end 26 of air intake pipe 27 to let air go into said air chamber space 20.
In the present invention, ring 40 is fitted to lower surface of check valve plate 35 keeping the relative position between check valve plate 35 and the head of coil spring 36 within a preferred range. Ring 41 is fitted on the ring bracket 39 to keep the bottom end of coil spring 36 within a preferred position.
Role of ring 40 and 41 is to keep check valve plate 35 in correct position always when the valve plate sits on the delivery end 26 of air intake pipe 27 during frequent vertical up and down movement of check valve plate 35. Rings 40 and 41 are required to keep the center of check valve plate 35 and the center of delivery end of air intake pipe 27 coincident with each other all through the operation. Ring 41 fixes the bottom of coil spring 36 in a selected position and does never allow any position change to the radial direction during operation.
To assure the smooth movement of check valve plate 35, it is acceptable to use such materials for said valve plate as glass, metal, plastics and mica. Among those materials, glass is superior to others because of its flatness and strength against temperature change and chemical attack. Glass is better than other materials.
Coil spring 36 helps check valve plate 35 float when air enters into air chamber space 20 and softens the contact shock when the check valve plate 35 comes to closed position. Elasticity of coil spring 36 shall meet above-mentioned requirements.
Stopper plate 37 mounted on top of check valve plate guide pieces 38 has a role to prevent excess jump-up of check valve plate 35. Possible shapes for stopper plate 37 are disk, ring, ribbon and others. At least one guide piece 38 for check valve plate shall be so positioned giving appropriate gap between guide piece surface and periphery of check valve plate 35 as not to interrupt the movement of check valve plate 35. Said guide piece 38 shall be so arranged surrounding coil spring 36 as to make air flow freely into said air chamber space 20.
To rectify the flow of air delivered from the end 26 of air intake pipe 27, a plate 42 is fitted cylindrically to exterior of said guide piece 38. The upper end of plate 42 may either have a gap between stopper plate 37 or be fixed to stopper plate 37 forming a cover-hood.
Air chamber unit 17 is connected to air supply nozzle 45 located in bottom-less combustion space 13 of the hollow metallic plug via stop valve 43 connected to the delivery end of air supply pipe 28 illustrated in
Coke oven door having heating function presented in the present invention is operated in a same manner to that of existing coke oven doors. In earlier stage of coking of coal particles 2, a large amount of gas is generated in coke oven 1 and delivered to dry-main (not shown) through ascension pipe (not shown) and a part of this gas flows into bottom-less combustion space 13 of hollow metallic plug and raise gas pressure in the hollow metallic door plug up to a certain positive level. Gas pressure in air chamber unit 17 is raised up to positive level in accordance to the gas pressure in combustion space 13. During this period, check valve plate 35 comes down because of the positive pressure in the air chamber unit 17 to the edge of delivery end 26 of air intake pipe 27 and isolate air chamber space 20 from open air. Gas pressure in coke oven becomes lower gradually along with the progress of coking reaction because of decrease of gas generation and becomes close to atmospheric pressure at around middle of coking cycle. However, a considerable wide ranged and frequent fluctuation of gas pressure between positive and negative within a very short time continues during all period of coking cycle therethrough. The reason of this fluctuation is not clear at the moment. The inventor estimates that the gas pressure in each oven may be affected by the operation of other ovens directly because all ovens are connected by gas collecting-main (not shown). Every time when gas pressure in said bottom-less combustion space 13 of hollow metallic door plug becomes negative, gas pressure in air chamber space 20 also becomes negative. And check valve plate 35 is sucked upward and floated. A volume of air flows into air chamber space 20 corresponding to the time when check valve plate 35 is kept floating and burns coke oven gas in said bottom-less combustion space 13 of hollow metallic door plug. When gas pressure in bottom-less combustion space 13 of hollow metallic door plug becomes positive, gas pressure in air chamber space 20 also becomes positive and check valve plate 35 comes down and closes delivery end 26 of air intake pipe 27 and prevents flow-out of raw coke oven gas generated in coke oven 1 into open air. Raw coke oven gas flowing into air chamber space 20 through air supply pipe 30 or air delivery cup 32 fitted instead of air supply pipe 30 is cleaned by gas velocity slow down effect and labyrinth effect of partition 24. A part of removed mist and particles suspended in the raw coke oven gas that flows into the air chamber space 20 falls down in air delivery cup 32 or on the bottom plate of section (B) of air chamber space 20. Accordingly check valve plate 35 in the section (A) of air chamber space 20 separated by partition 24 is kept free from contamination by suspended contaminant particles in the raw coke oven gas and can continue stable supply of air necessary to burn coke oven gas that flows into bottom-less gas combustion space 13 in hollow metallic door plug for long time.
In the present invention, comparison
Coke oven door providing heating function having bottom-less combustion space 13 provided on coking chamber side of coke oven door and air chamber unit 17 mounted on outside of coke oven door frame 5 raises temperature of coal particles charged in the vicinity of coke oven door plug by high sensible heat and combustion heat of raw coke oven gas flowing into combustion space 13 of hollow metallic plug and, as a result, reduces the generation of poor quality coke remarkably and, in other words, improves the yield of good quality blast furnace coke. In addition, tar adhesion to the foot of coke oven door generated under lower temperature range in early stage of coking process disappears because of heat generated by burning raw coke oven gas in the combustion space 13, and, as a result, tar-cleaning operation for coke oven door in every coke pushing operation is not required anymore. Heat supply from door plug side raises the mechanical strength of coke produced in the vicinity of door plug and reduces coke cake collapsing during pushing operation and minimizes the damage of coke oven heating wall. By applying the present invention to the existing coke batteries, their lives are prolonged. The practical application of the present invention for existing coke batteries has already started in Japan. It is predicted that application of the present invention for both existing and newly constructed batteries will increase in the near future as an effective measure for not only economical but also environmental purposes.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-084745 | Feb 2005 | JP | national |
| 2005-122919 | Mar 2005 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2006/302949 | 2/20/2006 | WO | 00 | 8/21/2007 |
