US2498784A - Horizontal coke oven method - Google Patents

Description

Feb. 28, 1950 J. BECKER nonxzou'm. com: ovsn mmon Filed Aug. 30, 1

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Patented Feb. 28 1950 HORIZONTAL COKE OVEN METHOD Joseph Becker, Pittsburgh, Pa., assignor to Koppers Company, Inc., a corporation of Delaware Application August 30, 1947, Serial No. 771,469

5 Claims.

in horizontal coke ovens and particularly to improvements in'the conformation of their cokingchambers whereby known operating diiilculties and their efiects on oven-operations and operating results are made less considerable even in those instances where such problems are not en+ tirely solved by the instant improvements.

More particularly the present invention is directed to the method of coking coal in horizontal coke ovens described in my copending application, Serial No. 562,442, filed November 8, 1944, now Patent 2,447,837, of which this application is a division. v

In th art of coking coals and especially highvolatile coals at high temperatures and fast coking-times in horizontal coke ovens, one of the onerous operating problems that can present itself is that of maintaining the roofs and the upper side-walls of the coking-chambers substantially free of so-called roof-carbon," i. e., accreted hardcarbon that gradually accumulates on the masonry of the coking-chamber roofs and the upper side-walls and requires their frequent policing for its removal in order that the space of the gas-collecting space, provided in each coking-chamber between its roof and the top of the coal charge, does not become so charged with said "roof-carbon that its capacity is importantly reduced and the layer of charged coal that is at the top of the oven-charge, and which normally forms the bottom of said gas-collectin space, does not become narrower than the ovencharges lower part. In the event such circumstance arises, the upper part of the oven-charge will be completely coked long before the cokingreaction has penetrated through the remainder because less'than the normal amount of coal will be present there for carbonization by the heat radiated directly thereto through said gascollecting space from the surrounding hot masonry. Such condition occasions overheating of the tops of the oven-charges while trying to coke the remainder thereof and is conducive to production of the phenomenon known as hottops, and this condition in the coking chambers causes in turn excessive cracking of the gases and vapors evolved from the coking coal, thus aggravating the formation of roof-carbon and also reducing the potential yield of valuable liquid byproducts, such as phenols, and the like. If, therefore, the heating conditions, for any reason required of employment in vertically walled coking-chambers of coke ovens of the prior art, have a tendency because of the behavior of the employed coal to occasion deposition of roofcarbon, its formation can become acceleratedly aggravated in a vicious cycle that canchange the nature and amounts of recovered byproducts. Manifestly, the provision of simple means whereby development of the above-described phenomena in horizontal coke ovens can be importantly inhibited or substantially eliminated will be a, distinct contribution to the available apparatus of the byproduct coking art.

An object of the present invention is therefore the provision for a horizontal coke oven of a substantially vertically-walled coking-chamber that is adapted automatically to inhibit the formation of I roof-carbon" in the gas-collecting space of said oven and to avoid the deleterious operating effects and results its presence therein engenders.

A further object of invention is the provision ,of novel features of design whereby cokingchambers of horizontal coke ovens that are equipped therewith are advantageously operative with lower temperatures in the gas-collecting spaces than are like coking-chambers unequipped with said novel features.

A further object of invention is the provision of novel substantially vertically-walled cokingchambers for horizontal coke ovens whereby penetration of the coking reaction completely through the upper parts of the coking-chamber charges of coal is automatically delayed until after the lower parts of said charges are coked and whereby the thickness of those horizontally extending seams of the fused coal that form in the top of said charges are automatically maintained of easier apparent penetrability, and consequently offer less resistance to escape of gases and vapor from the interior of said charges than do those fused-coal seams that simultaneously form therein adjacent to and extend in parallelism with the sides and bottoms of the cokingchambers, so that the pressure of the coking charges of coal against the heating-walls is made less than would otherwise obtain.

zontal coke ovens are provided with cokingchambers of which the heated side-walls are throughout substantially their entire height vertically disposed but, in contrast to horizontal coke ovens of the prior art, the upper minor portion of each said side-wall, from a level adjacent the horizontal flue of the heating flue system, or its structural equivalent, is disposed in a vertical plane remoter from the longitudinal center of the coking-chamber than is the lower major portion of said heated side-wall thereby forming in combination with its opposite similarly formed side-wall a coking-chamber which is wider'adjacent its top than throughout the greater part of its height. A vertical section taken crosswise of the coking-chamber of invention exhibits a contour similar to that of a capitaled pillar. The invention also preferably provides for use in combination with the abovedescribed invention a pusher-side coke-oven door of which the lower edge of the leveller-door is above the horizontal level of the juncture between the upper wider and lower narrower parts of the associated coking-chamber so that the top of a levelled coal-charge will present to the gas-collecting space a surface of coal that is wider than would obtain were the top of the levelled coal-charge restricted to the narrower portion of the instant coking-chamber, although even in the latter instance some, but not all, of

the utility of the present novel construction can be enjoyed because of the greater capacity of the wider gas-collecting space to accumulate roofcarbon without restricting the expanse of coal that is directly exposed near the top of the ovencharge to coking-heat radiated thereon from the masonry of the coking-chamber roof and the upper side-walls. The many benefits that accrue from employment of the present innovation in horizonal coke-oven design will be more easily appreciated by reference to the accompanying drawings and the hereinafter-given discussion thereof.

In the accompanying drawings forming a part of this specification and showing for purposes of exemplification a preferred apparatus and method in which the invention may be embodied and practiced but without limiting the claimed invention specifically to such illustrative instance or instances:

Fig. 1 is a view showing a vertical section taken longitudinally through a coking chamber of the horizontal coke-oven battery of Fig. 2 embodying the present improvement and is taken along the line I-I of said figure; and

Fig. 2 is a view showing a vertical section taken longitudinally, along the line IIlI, of the battery of Becker-type horizontal coke ovens of Fig. 1 provided with the present improvement in coking chambers.

The same characters of reference designate the same parts in each of the views of the drawings.

Referring now to the drawings: the coke-oven battery shown in the views of the figures and embodying features of the present improvement is of the well-known Becker type of combination horizontal coke-oven wherein heating-fines of a heating-wall are communicably connected with a corresponding group of heating-fines in an adjacent heat-ing-wall by means of crossover duct means that extend over thetop of the intermediate coking-chamber. The coking-chambers [0 are formed between spaced heating walls that extend transversely of the battery and comprise a multiplicity of vertically disposed heating-flues II, the heating-Hues of each heating-wall being operatively divided into flue-groups of which each communicates by means of a crossover duct 12 with a corresponding group of heating-fines in an adjacent heating-wall, and the so-connected fluegroups alternate periodically a flame-flues and combustion-products flues. Each heating-flue at its lower part communicates individually with a source of rich fuel-gas and with a pair of regene erators that are separated by and are adjacent opposite sides of a pillar-wall l3 which supports the flued heating-wall thereabove. These regenerators, l4, l5, that extend transversely the entire width of the battery, at their upper parts are provided with conduits respectively 5, II, whereby each heating-flue of the heating-wall above communicates individually with said regenerators, and said conduits merge a short distance below the bottom of each flue into a common duct l8 that operates as their heating-flue inlet. eflective opening of said duct is regulated by portcore l9 that is replaceably mounted atop-that portion of the capital of pillar-wall I3 which serves to form the dividing wall between the inclined said ducts 16, ll. Rich fuel-gas, at such times as the illustrated battery is heated by its combustion, is introduced into the outer end of a duct 20 that extends the full length of a pillar wall l3, wherein it is formed, and is apportioned to all the heating-flues of the above heating-wall by means of upwardly-extending branch-conduits 2| and of calibrated nozzles 22, each said conduit and nozzle being individual to aheating flue. During said rich-gas underfiring, the flame-fines are supplied with air for combustion from both of the regenerators I4, l5 that are located directly therebeneath, and their combustion-products are delivered to the battery-stack through another pair of adjacent regenerators l4, I5 that communicate with the same common crossover duct l2. During preheated lean-gas underfiring,

upfiow regenerators [4 are adapted to receive, in-.

stead of air, lean fuel-gas from an outside reservoir therefor through their sole-channels 23 and to preheat said gas prior to its delivery to their associated flame-flues, Whereas the adjacent upfiowing regenerators I5 still serve to preheat the air required for its combustion; at such times as their directly associated heating-flues are operating as downflow heating-fines, all the regenerators l4, l5, serve to carry combustion-products to the battery stack (not shown). During a regenerative heating-cycle in the illustrated battery, all the heating-fines in the same heating-Wall function simultaneously either as flame-fines or combustion-products flues.

Combustion-products, formed' by the combustion of the employed heating-gas and air in the flame-fines, flow upwardly therein and all the combustion-products from all the heating-fines comprising a heating-wall fluegroup commingle at their tops in a common horizontall extending conduit-like opening 3| whence they pass into crossover duct I2 and over the top of an intermediate coking-chamber into a corresponding group of heating-fines in an adjacent heating Wall on their Way to the battery stack.

Coal that is to be carbonized in coking-chambers I0 is introduced thereinto at their tops through charging-holes 25 in the well-known manner, after which it is levelled by reciprocation, through leveller-opening 26 of oven-door 21, of a leveller-bar that is supported on a pushermachine for the battery.

Heat evolved in the fiame-flues by said combustion of heating-gas and air therein is absorbed into their masonry and is transmitted into the .coal, that is charged into the coking-chambers,.

by those portions of the heating-flue and the entire heating-system masonry that form side-walls The 28, the roofs 28, and the bottoms ll of said cokins-chambers. Sufficient heating-gas is burned in the heating-flues to cause the coking reaction to penetrate from coking-chamberside-walls 28 into the oven-charges at the rate of about one half inch per hour from each said side-wall.

The coal-coking reaction comprises a rather complex sequence of physical phenomena and includes, in a freshly charged coke oven, the initial fusion at a relatively low temperature of a narrow band or layer of coal that is either directly in contact with the hot choking-chamber surfaces or is subjected to direct radiation therefrom. This band or layer of fused coal is variously referred to in the coking art as the plastic zone" or the tar-seam. Continued heating of the fused band or layer of coal brings about, as its temperature increases, decomposition of the fused constituents and an evolution therefrom of gases and vapors and this phenomenon is followed by a solidification and cementation of the nonvolatilized residue of said fused zone into the substance known as coke." As the coking reaction progresses through an oven-charge over a period of many hours and before its complete conversion to coke, said oven-charge presents, an outer surface or rind of solidified coke that is increasing in thickness with continued heating,

an inner core of unfused coal that is becoming narrower and narrower, and an intermediate band or zone of fused coal which grows gradually of lesser and lesser periphery as the center. of the oven-charge is approached but remains always approximately of the same relatively minor thicknessless than about one inch. Inasmuch as most coking coals fuse below about 500 C. and the heated surfaces of the masonry of the coking-chamber walls are atincandescent heat, the zones of plastic coal progress toward the center of the oven-charge in fused bands that exist more or less in parallelism with the adjacent hot coking-chamber surfaces including the top and the bottom; in result, these fused zones together form a sort of continuous envelope that entirely surrounds the inner core of uncoked coal and is intermediate such core and the coked outer rind of the coal-charge until all parts of said zones merge at the center of the oven-charge. The degree of plasticity obtaining in the zone of plasticity during the period when its fused components are decomposing into gases and vapors is very important both for success of coking operations and the integrity of the cokeoven structure. Some coals and mixtures thereof exhibit such rather high viscosity in their plastic seams, during the time when gases and vapors are being evolved therefrom, that said gases and vapors can escape only after they have accumulated therein under relatively high pressure: this internal pressure in the oven-charges is transmitted to the coking-chamber walls and in the instances of some bituminous coals exhibits sumcient pressure to cause permanent misalignment of the masonry of the heating walls. In the cases of coals that show this tendency to exert more than a preferred amount of pressure against the oven-masonry, it has been found expedient for alleviating this eventuality to coke them at somewhat slower than normal coking rates; that is, coking the charged coal throughout all parts of the oven -charges more slowly than at the usual faster coking rates makes it possible for the gases and vapors of carbonization to volatilize from said ovencharges at reduced and permissible pressures 6 therein. Such expedient is a hardly-to-be-observed practice in modern coking installations because it seriously limits the output of costly coke plants and prompts coke-oven managers to employ predominantly those coals, or coal mixtures, that exhibit a relatively high degree of fluidity during their fusion-phases and are consequently coked without special precaution in their heating.

Those hot gases and vapors of the coal distillation which create the internal pressure in the oven-charges are primarily those that have a tendency to evolve at the cooler coal-side of the levels of the oven-charges depends, amongst other factors, on the relative amounts of coal thereadjacent to absorb the available heat from the masonry; that is, the wider the layers of coal forming the tops of the oven-charges the more coal there will be there present to absorb the heat delivered thereto from the adjacent masonry and consequently the morev easy is the apparent penetrability of the plastic zone main tained at the oven level; and, in result, the gases and vapors flowing upwardly through the aforesaid uncoked core of the oven-charges escape from the plastic envelope with less pressure-development and therefore impose less pressure on the coking-chamber walls.

One of the salient advantages of the present improvement in the conformation of cokingchambers of horizontal coke ovens results from the fact that in the practice the plastic envelope of fused coal is thereby automatically maintained selectively more apparently penetrable in the top relatively minor portions of the coalcharges, and the gases and vapors of the distillation process can pass therefrom into the gascollecting spaces at internal pressures less than obtains in those coking chambers where the tops of the coal-charges are substantially the same width as their lower parts; this feature is especially advantageous for the coking of those coals, or mixtures thereof, exhibiting a relatively low degree of fluidity during their plastic phases because a relatively easily penetrable escape route for the evolution of gases and vapors is contin uously maintained at the tops of the coalcharges and the preponderance of their content of coal can be coked at coking times as fast as preferred because of this novel pressure-controlling safety-valve in the tops of the coal-charges.

According'to the present invention, side-walls 28 of coking-chambers iii, in the illustrated battery, are vertically disposed throughout substanviding in the upper parts of the coking-chambers greater coal-containing capacity per unit of the coking-chamber height than obtains in those parts of the coking-chambers that are directly adjacent the primary combustion-zones of heating flues H so that the charged and levelled coking-chambers contain at their tops more coal per unit of height than obtains in the lower parts thereof, and complete penetration of coking-heat through the wider upper parts of the coal-charges is delayed beyond that in the re- 'mainder thereof a period of time that is in direct relationship to the amount of provided topflare; for example, if the coking-chambers are two inches wider at the top than the bottom, complete coking of the coal adjacent gas-col-- lecting spaces 32 is delayed about two hours after the remainder of the oven-charge is coked. In consequence of the fact that the gas-collecting space 32 is formed of a greater width of coal than the lower major part of an oven-charge, the heat radiated to such coal from the ovenroof and the upper coking-chamber side-walls is absorbed by a relatively larger proportion of coal than is provided at such levels in the prior art and, in result, the tops of the coking-chambers are automatically maintained relatively cooler than heretofore and the plastic seams that are developed therein are automatically maintained relatively more penetrable, thereby facilitating the evolution therefrom of the volatile products of carbonization.

The present improvement in coking-chambers for horizontal coke ovens is of extensive utility in the coking art and provides advantages in operation and in operating results when employing coking coals, or mixtures of coals, chosen from the whole range of volatile-matter contents and plasticity characteristics identifying them. The

top of the coal-charge that is formed by normally charging and levelling the coking-charge of invention yields oven-charges having substantially vertical sides that are of the same width from the oven-soles up to a region adjacent the termini of the heating fiues where they are capped by a layer of coal that is wider than the remainder of the charge, thereby providing for the lower wall of the gas-collecting space a wider than normal expanse of coal and consequently a greater than normal amount of coal for absorbing heat, from the adjacent masonry and from the hot distillation gases flowing therethrough to the stand-pipe 34 whereby they leave the cokingchamber and all of which promotes maintenance of cooler tops for the coal-charges. The resultant wider than normal gas-collecting spaces makes the roof-carbon problem less important of attention in the coking of high-volatile coals because there is less inclination for such carbon to restrict the width of the coal surface forming the lower wall of the gas-collecting space to less than that of the lower part of the oven-charge and thus reduces the tendency such condition has to promote the condition known as hot-tops" and inhibits the cracking of desirable liquid products before they have even left the coking-chamber. In the case of coals havin a tendency to develop during their high-temperature coking, higher than preferred internal pressures that are transmitted to the coking-chamber walls, the present development is of important advantage since it provides means whereby of those highly viscous plastic seams that always develop in the oven-charges along zones that are adjacent to and substantially parallel the different heating surfaces of the coking-chambers, one such seam can be maintained of greater apparent penetrability to gases and vapors than the others, thereby providing an outlet of lower resistance to penetration for volatile products evolving from the center of the coal-charges and thereby reducing the tendency to build up internal pressure in the coal charge and making faster coking-times practical for such coals because the degree of fluidity existing in the elastic zones in the other portions of the coal-charges become relatively unimportant. The novel effects made possible by the instant improvements for all types of coking coals can be further enhanced, for example, by formin the wider capping layer of coal of a higher bulk density than obtains in the remainder of the oven-charge, or by forming it of wet coal having preferably more than about ten percent of free moisture, and thereby still further increasing the additional time that is required for complete coking of the capping layer of said coalcharges which can be formed with their novel configuration either by flowing coal into the improved coking-chambers or by forming said charges as stamped cakes outside the battery structure and thereafter introducing said cakes into and coking them in coking chambers having substantially the same contour.

The invention as hereinabove set forth is embodied in particular form and manner but may be variously embodied within the scope of the claims hereinafter made.

I claim:

1. The improved method of producing hightemperature coke in a horizontal coke oven, said method comprising: forming an oven coal-charge for coking in said oven, prior to coking therein, as a horizontally elongated mass of coal with two opposite vertically disposed sides and uniform widthfrom the bottom thereof upwardly throughout the major portion of its total height, and with a top levelled overhanging cappinglayer of coal that is a minor portion of the total height of said mass but which is throughout the horizontal length of the mass, wider than, and projects over the two opposite sides of, the lower said major portion; the oven charge being performed to a total height, and the top of the capping layer being levelled, to leave above its top surface, as the top level for the levelled oveneoal-charge, a likewise overhanging gas collecting free-space extending horizontally along over said top level lengthwise beneath the crown of the coking chamber, through which the distillate gas may flow off from the charge, when underlying below, horizontally along the crown of the oven over the underlying levelled oven charge, during coking therein; and the top of the capping layer which, as the top level for levelled coal charges, is to be contiguous to the overlying gas-collecting ofiflow crown space being formed of a transverse width wider in a horizontal plane than the width of the portions of the oven' charge at levels below the overhanging capping layer; thereafter coking the oven charge, while still soformed, in said horizontal coke oven, and withdrawing the distillate gas off cooler horizontally through the gas-collecting space left above said charge, while still so-formed, while maintaining the gas-collecting space in the region where the top of the levelled coal charge is contiguous to the gas ofiflow crown space unobstructed to diffusion of gas from side to side and of an effective free cross-sectional area, transversely of the coking charge, greater than that of the area of the portion of the coal charge below the capping layer; and effecting the aforesaid coking of said oven charge by flowing hot combustion-products into indirect contact with the said lower major portion of said mass of coal along its two opposite sides from the bottom thereof upwardly and thereby absorbing coking-heat into said mass of coal and coking it; and simultaneously flowing hot combustion-products of a lower temperature than those employed for heating the lower portion of said mass of coal into indirect contact with its upper minor portion of saidwider capping-layer and absorbing coking heat thereinto so that the coal in the lower major portion of the mass of coal is completely coked before that in its said upper minor capping layer and thereby preventing, in conjunction with the dissipation of heat in a wider area of coal particles in the region contiguous to the gas offflow space, throughout the major portion of the coking period, overheating of the volatile products of the coking reaction continuously passing into and on through the gas-collecting space upon its evolution from the top of said coal mass.

2. The improved method of producing hightemperaturecoke in a horizontal coke oven, said method comprising: forming an oven coal-charge for coking in said oven, prior to coking therein, as a long, high, and narrow bed of coal of uniform width from the bottom thereof upwardly throughout the major portion of its total height, and with a top levelled overhanging cappingiayer of coal that is a minor portion of the total height of said bed but which is throughout the horizontal length of the bed, wider than, and projects over the opposite sides of, the lower said major portion of the bed; the oven charge being preformed to a total height, and the top of the capping layer being levelled, to leave above its top surface, as the top level for the levelled ovencoal charge, an overhanging gas-collecting freespace likewise projecting over the opposite sides of the lower major portion of said bed and extending horizontally along over said top level lengthwise beneath the crownof the coking chamber, through which the distillate gas may flow oil from the charge, when underlying below, horizontally along the crown of the oven over the underlying levelled oven charge, during coking therein; and the top of the capping layer which, as the top level for levelled coal charges, is to be contiguous to the overlying gas-collecting offflow crown space, being formed of a transverse width wider in a horizontal plant than the width of the portions of the oven charge at levels below the overhanging capping layer; thereafter, while the oven charge is still so formed, coking the same in said horizontal coke oven; continuously passing the volatile products of the coking reaction evolving from said coal bed into the upper gascollecting space; and withdrawing the distillate gas of! horizontally through the gas-collecting space left above said charge, while maintaining the gas-collecting space, in the region where 'the top of the levelled coal charge is contiguous i0 area of the portion of the coal charge bed below the capping flayer.

3. The improved method of producing hightemperature coke in an intermittent coke oven, said method comprising: forming an oven coalcharge for coking in said oven, prior to coking therein, as a horizontally elongated high, and narrow bed of coal with a top levelled overhanging offset capping-layer of coal that is a minor portion of the total height of said bed but which is throughout the horizontal length of the bed, wider than, and projects as an offset over at least one of the high sides of, the lower portion of the bed; the oven charge being preformed to a total height, and the top of the capping layer being levelled, to leave above its top surface, as the top level for the levelled oven-coal charge, an overhanging offset gas-collecting free-space likewise having its offset projecting over the same side that the capping layer is offset, and extending horizontally along over said top level lengthwise beneath the crown of the coking chamber, through which the distillate gas may fiow off from the charge, when underlying below, horizontally along the crown of the oven over the underlying levelled oven charge, during coking therein; and the top of the capping layer which, as the top level for levelled coal charges, is to be contiguous to the overlying gas-collecting ofiflow crown space, being formed of a transverse width wider in a horizontal plane than the portions of the oven charge at levels below the overhanging capping layer; thereafter coking the so-formed oven charge while it is still so formed, in said horizontal coke oven, and withdrawing the distillate gas oil through horizontally through the gas-collecting space left above said charge as it evolves from the charge, while maintaining the gas-collecting space unobstructed to diffusion of gas from side to side and of an effective free crosssectional area, transversely of the coking charge, greater than that of the area of the portion of the coal charge bed below the capping layer.

4. The method according to claim 2 characterized by a capping layer of higher bulk density than the lower major portion of said bed of coal.

5. The method according to claim 2 wherein said capping layer has a higher moisture content to the gas oifflow crown space, unobstructed to diffusion of gas from side to side and of an effective free cross-sectional area, transversely of the coking charge, greater than that of the than the lower major portion of said bed of coal.

JOSEPH BECKER.

REFERENCES CITED The following references are of record in the. file of this patent:

UNITED STATES PATENTS Number Name Date 659,048 Atwater Oct. 2, 1900 1,025,419 Moss May 7, 1912 1,650,127 Perry Nov. 22, 1927 1,707,427 Becker Apr. 2, 1929 1,986,007 Vobach Nov. 14, 1933 2,018,604 Flt! Oct; 29, 1985

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