US2158710A - Coke oven apparatus - Google Patents

Description

y 15, 1939' B. J. c. VAN DER HOEVEN 2,158,710

COKE OVEN APPARATUS Filed Jan. 19, 1937 4 Sheets-Sheet l 1! u zorrumw ZOEHUMW INVENTOR. Bee/men J. C. vq/vafl? l/as YEN. WM M ATTORNEY.

May 16, 1939.

B. J. C. VAN DER HOEVEN COKE OVEN APPARATUS Filed Jan. 19, 1937 4 Sheets-Sheet 2 INVENTOR. QER/VOEVE/Y- ATTORNEY.

May 16, 1939. B. J. c. VAN DER HOEVEN 2,158,710

COKE OVEN APPARATUS Filed Jan. 19, 1937 4 Sheets-Sheet s mm we J w A w m ATTORNEY.

May 16, 1939.

B. J. C. VAN DER HOEVEN COKE OVEN APPARATUS Filed Jan. 19, 1937 4 Sheets-Sheet 4 U 0w/// /H 7/ X\ 0// ///v/////// H/ H IN VENT OR, BERN/9RD J. C. m as)? l/oxsvzsm ATTORNEY.

Patented May 16, 1939 UNITE srA'rEs PTENT FFECE COKE OVEN APPARATUS Delaware Application January 19, 1937, Serial No. 121,244

9 Claims.

The present invention relates to horizontal retort coking ovens and especially to those that employ the well-known underjet system of supplying underfiring gas to the oven heating walls.

5 In coking structures of this type, rich un'derfiring sensor a gas of high thermal content, such as for example is produced as a by-product of the carbonization process, is distributed to the heating walls from a distribution system that is posi- 10- tioned in accessible passageways beneath the oven-supporting mat, and the instant invention pertains more particularly to improvements in the disposition of the riser-pipes that branch from the distributor-headers of the underjet disi=5 tribution system and deliver underfiring gases to the individual heating fines of the oven heating Walls from a' main supply line that is itself adapted to furnish fuel to a battery of ovens of this type. In a battery of retort coking ovens adapted for underfiring according to the underjet principle, a main gas-supplying main disposed to supply heating gas to all the heating walls of the battery structure is usually positioned in the acces- 5' sible passageways beneath the battery-supporting mat. The heating gas for the individual heating walls, or large fractions of said walls, is flowed from this principal gas-supplying main into a plurality of distributor-headers that branch off 3- laterally thereof substantially in parallelism with the individual heating walls. These distributorheaders are likewise located in the accessible basement of the battery. Riser-pipes extendupward from these distributor-headers and communicate with the above-lying heating flues oi the heating walls by means of conduits that extend vertically through the battery regenerator walls and port at their upper ends into the lower part of the heating flues. In a distribution sys-- tem then of this type the heating gas arrives in the individual heating flues by successively flowing through the principal supply-main, the distributor-header or headers for an individual wall and the riser-pipes that finally convey the gas 4 5* from the distributor-headers into the regenerator wall conduits.

During one period of the heating cycle in the regenerative underfiring of a battery of underjet ovens, half of the distributor-headers for the 56 heating walls are not functioning to distribute underfiring gas to the therewith connected heating dues, and at such times it is customaryto employ said headers for the introduction of decarbonization air into the vertical ducts located 55 in the regenerator division walls. This decarb-onization air serves to consume carbonaceous matter that may have been deposited in the ducts by the cracking of hydrocarbons of that heating gasjust previously flowed therethrough and which decomposition results from the high temperature at which these ducts are maintained by their surrounding regenerator walls.

Immediately prior to the introduction of the decarbonization air into said distributor-headers, they are substantially filled with residual underfiring gas which may diffuse into the inflowing air to form such mixtures of the two as can only be ignited by an accompanying report when they flow out of the distributor-headers into the hot rich gas conduits in the regenerator division walls. This feature of operating procedure also gives rise to the possibility that the distributorheaders may become filled with such a mixture of gas and air that its ignition will be accompanied by an explosion or explosions in the headers and cause a flash-back therethrough which may project a flame out of the decarbonization air-inlet orifice. Although these explosions are of relative minor nature, they will, if allowed to take place during each period of flow reversal in the regenerative heating cycle, have the effect of eventually loosening brickwork joints and sutures between structural elements comprising a battery structure, and so give rise to short circuits and leaks in the underfiring system.

u The possibility of producing gaseous mixtures of an explosive nature again arises in the regenerative heating cycle when rich gas is re-introduced into distributor-headers that are filled with residual .air remaining therein from the decara bonization step. During both periods of a regenerative heating cycle in un'derjet underfired ovens it is then therefore possible for explosive mixtures to be formed in the distributor-headers of the distribution system when operating practice requires that decarbonizing air and rich gas shall be introduced into the battery structure through the same distributors.

This problem in the operation of underjet underfired coke ovens arises in part as a consequence of the difference in densities between the coal gas and air which contributes to them a natural tendency to, remain stratified or segregated in substantially separate layers when flowed into the same receiver unless caused to intermingle under someinfluence that will give rise to turbulence or the like. If the volume or storage capacity of the distributor-headers is relatively small in respect of the quantities of gases flowed thereinto, sufficient turbulence of flow through the distributor-headers may be engendered by the infiowing gas to minimize the effects of these density differences and to cause said infiowing gas to flow to all parts and levels of said headers and quickly sweep the residual gas therefrom ahead of it and out into the heating flues with a relatively small volume of inflowing gas, and. without allowing pockets of said residual gas or zones of stagnant flow to exist wherein the residual gases may be entrapped to later diffuse into new quantities of infiowing gas in such manner as to form explosive mixtures. If, on the other hand, the storage capacity of the distributorheaders is large in relation to the volume of infiowing gasessuch a relationship being highly desirable so that a substantially uniform static pressure will exist in the gas of the distributorheaders at points adjacent the outlets of all the there-from branching riser-pipes that connect with the heating flues, in order to facilitate distributioncoal gas and decarbonization air flowed intermittently thereinto may tend to segregate respectively in the upper and lower levels of said headers because of both the difference in the densities of the two gases and the relatively lower gas velocity existing in distributorheaders of the larger capacities.

This phenomenon of segregation and entrapment is promoted by and becomes especiaily evident and important in distributor-headers that have been constructed in accordance with prior practice. In the prior art, the outlets from the distributor-headers of under-jet ovens to those riser-pipes that branch therefrom for the delivery of underfiring media to the above-lying heating fines of the oven walls, have all been disposed in such manner as to withdraw gases from said headers at only one level. That is to say, the riser-pipes have all been communicably connected with their headers at the top, the middle section, or the bottoms thereof, but have not been disposed so that gases may issue from the different levels of said headers simultaneously.

From the above-recited, it becomes obvious that the provision of means whereby heating gas and decarbonization air may be intermittently employed to displace each other from the distributor-headers of underjet coke ovens and in such manner that explosive mixtures of the same will not result, will be an advantageous contribution to the underjet coke oven art, and this is an object of the present invention. The invention has for further objects such other improvements and such other operative advantages or results as may be found to obtain in the processes or apparatus hereinafter described or claimed.

According to the present invention, for underjet ovens that have distributor-headers adapted to convey underfiring gases to a plurality of heating fiues through riser-pipes that branch therefrom to communicably connect with individual heating flues, I provide diversely disposed outlets from the distributor-headers to the riserpipes, said outlets being so disposed in respect of said headers that gases may be flowed outward into the riser-pipes simultaneously from different levels of the gas volume contained therein. By means of my instant improvement it is possible to discharge gases simultaneously from the top, the bottom or intermediate levels of the distributor-headers, with the result that light and heavy gravity gases which may tend to collect and stratify respectively in the upper and lower levels of the headers, will be afforded outlets respectively arranged in accordance With their physical characteristics, so that gases of both types may be discharged quickly from the headers and without the otherwise existing danger arising that a pocket of one gas may be entrapped by another gas of different density.

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 practised but without limiting the claimed invention specifically to such illustrative instance or instances:

Figure 1 is a composite transverse vertical section through a regenerative coke oven battery provided with an underjet underfiring system and showing one means of furnishing a battery structure with the improvements of the present invention, the section AA being taken through a heating wall whereas section 3-3 is taken through a coking chamber;

Figure 2 is an enlarged fragment of Figure 1 showing the usual general arrangement of an underjet distribution system but not embodying the improvement provided by the present invention;

Figure 3 is a view taken along the line III-III of Figure 2;

Figure 4 is an enlarged fragment of a part of Figure 1 showing in large scale the distributorheaders and riser-pipes of the underjet system and particularly that embodiment of the present improvement disclosed in said Figure 1;

Figure 5 is a view taken along the line VV of Figure 4;

Figure 6 is a view similar to that shown in Figure 4 but illustrating another means whereby the basic principle of invention may be embodied in an underjet underfiring system;

Figure 7 is a view taken along the line VII-VII of Figure 6;

Figure 8 is a view of an enlarged fragment of Figure 5 showing a preferred form of the present improvement; and

Figure 9 is a section on line IXIX of Figure 1.

The same characters of reference indicate like parts in the several views of the drawings.

Referring now to the drawings, Figure 1 shows a regenerative by-product coke oven having the means for the distribution of rich gas arranged according to the principles of an underjet underfiring system, and the heating fiues of the heating walls disposed according to the well-known system employed in the Becker ovens in which the combustion products issuing from the tops of the up-burning flame-flues of a heating wall are carried by means of cross-over ducts over the top of an adjacent oven and down into the heating fiues in the opposite heating wall of the coking chamber. The horizontal coking chamber Ill, which is provided with a door II at its opposite ends for closing and sealing the chamber during the carbonization period, has a heating wall I2 on either side thereof in which are disposed the vertical heating flues l3 that are arranged in groups of four, each group being provided with a short horizontal flue I4 that communicably connects the tops of the several heating flues of each group. The horizontal flues and vertical flue groups of one heating wall are connected individually by cross-overs I5 with a corresponding horizontal flue and vertical flue group in the opposite heating wall of the coking chamber. Beneath the heating walls and substantially paralleling the same are the regenerators IS in which underfiring media may be preheated before they are introduced into the lower part of the heating flues throughthe adjustably disposed ducts I! that provide-for interflow of gases between the regenerators and the vertical heating The heating walls are each provided with at least two regenerators that are disposed for independent gas flow and are separated from each other by masonry division walls that extend lengthwise of the oven chamber. Extending upward through the battery supporting-mat I8 from the therebeneath accessible passageway l9 are the vertical ducts 20 which are positioned in the regenerator division walls, each such duct 20 is adapted to port at its upper end into the lower part of a heating flue and to communicably connect with a source of rich gas supply at its lower end by means of-connections exposed in the accessible passageways beneath the batterymat. When underfiring the battery with rich gas, the same is flowed upwards through the ducts 20 in the regenerator division walls to ports 2| positioned at their upper end, and through which the rich gas is discharged directly into the heating flues to be burned with air that has been preheated'in the 'regenerators prior to being discharged into the heating fiues through conduits IT:

'The'rich heating gas employed for heating the battery walls is delivered to ducts 20 by a distribution system therefor positioned in the abovementioned accessible passageways l9, and said ducts'ZUare each communicably connected with the rich gas distribution system by means of pipe connections and gas flow regulating means that are accessible from the battery basement so that the 'volumeof underfiring gas delivered to each such duct can be -conveniently regulated from within said passageways. The rich gas for heatingthe oven walls is flowed into the battery basement through the arterial supply line'22 from a rich gas supply reservoir. For each heating wall comprising the battery; a pipe 23 branches off the arterial supp1y-1ine 22 and is fitted with a threeway cock 9 that is adapted both to regulate the volume of' gas withdrawn from line 22 into pipe 23 and to admit decarbonization air from thebasement atmosphere into the riser-pipe 23, when said cock has been adjusted to shut off the flow of rich gas into said riser-pipe. A distributorheader 24 is provided for each heating wall of the battery and each such header is communicably connected for purposes of gas flow with the riser-pipe 23. Branching from each distributorheader are other riser-pipes 25, that connect individually with the ducts 20 through which is flowed the rich gas that has been apportioned from the distributor-headers 24 to the heating flues by the gas-flow regulating means 26. The flow regulators 26 are positioned in pipe-connections 21 that are in turn adapted to join the riser-pipes 25 and distributor-headers 24 for gas flow, as shown in detail in Figures 2 to 7 inclusive. The three-way cook 9, shown in Figures 2 and 3 and as hereinbefore mentioned, is adapted both to flow rich gas from the battery main-supply line whereby decarbonization air may be drawn through the inlet 3i! of flanged pipe 3| from the battery basement and into distributor-header 24 by stack-draft that causes sub-atmospheric pressure to exist in the heating fines and therewith connected ducts 20 during that period of the regenerative heating cycle in which said heating fines-are functioning to carry combustion-products downward and out of the heating-flue system' to the stack.

'As will be noted in Figures 2 and 3, the pipeconnections 21 that are disposed to conduct gases from distributor-header 24 to riser-pipes 25 and to the communicating ducts 2B, are all arranged to withdraw said gases from the same relative position along the distributor-header, i. e., from the bottom thereof. This conforms with customary procedure in prior practice in which the gas outlets from any distributor-header have been disposed in such manner as to flow gases to all therewith connected heating flues from similarly positioned outlets. That is to say, it is not new provide outlets for the distributor-headers whereby gases flowed therefrom will all be withdrawn either from the top, the bottom or some peripheral point therebetween, but what is new in the improvement provided by my present invention is the provision of means whereby gases flowed to a plurality of heating flues from the same distributor-header will be removed not all from the same level of the header but rather from more than one level, and if preferred from several levels thereof.

Whenever underfiring gas of high thermal content is being flowed from arterial supply main 22 to adistributor-header 24 through the three-ways cock 9, the heating flues I3 connected with said distributor-header, by means of ducts 2G and riser-pipes 25, are functioning as flame fines and all said members of the distribution system are filled with rich underfiring gas, and the decarbonization air inlet 3% of pipe 3! is closed to prevent-the escape of heating gas therefrom. Duringthe subsequent period of reverse flow in the heating flues when they are operating to carry combustion-products to the stack from other and similarly positioned heating flues which are func tioning at the moment as flame-flues, the rich gas supply to the distributor-header 24: is interrupted by suitable adjustmentof three-way cock 9 which, thereafter, is-placed in-such position by tension applied to cable 29 that the passageway, provided-for the withdrawal of decarbonization air from the battery basement, is opened, so that air can be introduced through inlet 3% of pipe 3| into said header and riser-pipes in which the gasesare under sub-atmospheric pressure in consequence of the stack draft.

As hereinbefore mentioned, the flowing of this decarbonization air into distributor-headers 24'. that are already filled with heating gas, is often attended by the development of mixtures of the two-gases which explode when ignited by the regenerator-heated walls of ducts 20, unless precautionary'measures are provided for avoiding the production of such mixtures. This detrimental phenomenon is encountered in divers types of underjet ovens, and operating expediences have been variously proposed and employed which have led to a partial elimination of this difliculty for which I now provide a complete solution by providing new and useful improvements in distributor-header apparatus that have been especially designed to meet this circumstance.

Decarbonization air drawn by stack draft through pipe 30 and cock 9 into gas-filled riserpipe 23, will rise therein and displace the lighter density fuel gas into the above-lying distributorheader 24. When the level of the air reaches the junction of riser 23 and header 24, said air will tend to flow to the right and left along header 24 and displace the therein-contained heating gas ahead of it and into pipe-connections 2'! and riserpipes 25. If the velocity of the air flowing into and through the header is sufficiently great, air may, upon entering the header, flow as high as the top thereof and therealong to form a column of air that will fill the distributor cross-section completely, and force all the fuel gas ahead of it while operating as a sort of fluid piston and without causing substantial intermingling of the two gases except at the interface. If however the capacity of the header is large in relation to the volume of the decarbonization air introduced thereinto, said air by reason of its heavier gravity may tend to flow along the bottom of the distributor-header and into pipe-connection 21 and risers 25 without reaching the top of the header thereby leaving a volume of heating gas entrapped in the upper levels of the distributor-header, whence said heating gas will later diffuse into more infiowing decarbonization air to form a mixture that will explode when ignited in the heated ducts 20. During the reverse from air to gas, the lighter gravity gas entering the airfilled header will tend to travel to the top of the header, and as there are no outlets at the top of the distributor-header the gas cannot escape at that point to entrap air in the bottom of the distributor-header, but on the contrary, will crowd the heavier air through the outlets positioned at the bottom of the distributor, as the layer of gas gradually increases in depth from the top of the header downwardly. Thus when all outlets from the distributor-headers are positioned at the bottom thereof it would be anticipated that the explosions would occur during that interval of the regenerative heating cycle when the reverse is made from gas to air, or at such times as it is possible for pockets of gas to lie sluggishly in the upper part of the header. This anticipation is confirmed in the practice. On the other hand and by the same reasoning,

. when all outlets from the distributor-headers are positioned at the top thereof where the lighter gravity gas is provided with opportunity to be discharged freely from the headers, air may be trapped in the bottom of the headers and in this instance the explosions should take place at an interval of the heating cycle different than when all outlets are at the bottom of the distributor. This expectation is also confirmed by observations in operation and said explosions predominate in this instance on the reversal from air to gas. Such mixtures of the two gases as may be formed at any time will lie at levels between the top and bottom of the distributor-headers, by reason of the fact that their densities will lie between the extremes represented by the unmixed fuel gas and air. When, therefore, the header outlets are all positioned at one level intermediately of the top and bottom of the headers, said outlets tend to promote quick removal of mixtures of the two gases before their air component becomes so large as to render them explosive in nature, and experience has shown that the tendency to produce explosive mixtures is somewhat reduced by this expediency, but it does not completely eliminate the danger.

According to my present invention which provides outlets, for a distributor-header of an underjet oven, that are variously disposed about its periphery, the gases flowed from the header are withdrawn from more than one gas level of the same. The increase of pressure on the residual header-gases, which is required to cause them to flow from the headers, is provided by the inflowing gases and is of course transmitted substantially uniformly to all levels of the header and operates to cause residual gases to flow simultaneously into all the therewith connected riserpipes, and my present improvement in contrast to the prior art by furnishing header-outlets at a plurality of gas levels of the distributor-header provides means whereby a speedy purging of re sidual gases is made possible and the opportunity for gases to remain stratified therein according to their densities is greatly diminished.

Referring again to Figures 2 and 3 illustrating an underjet oven distributorheader with which considerable difi'iculty was experienced from explosions that took place shortly after decarbonization air was introduced into the gas-filled header, it Was found by experimentation that if the distributor-header was so adapted that the alternate riser-pipes 25 tapped the gases of the header at a point near its upper level, the production of explosive mixtures immediately ceased and the reverse from gas to air or vice-versa could be effected quietly and without accompanying reports of any kind. This alteration was simply carried out, as shown in accompanying Figures 4 and 5, by screwing a threaded nipple 35 into the aperture 36 of the distributor-header 24. means of this simple provision, each alternate risen-pipe 25 along the entire length of header 24 was supplied with gas that came from adjacent the upper level of said header, and the remaining riser-pipes 25 were supplied with gases having their origin at the lowest level thereof. This improvement substantially eliminates the chances for pockets of relative stagnant gas flow to exist at either the top or the bottom of the header, and the gases present in the header at any time can be displaced ahead of infiowing gases simply and efiectively and without excessive intermingling, since outlets are provided for both gas and air if they have become segregated for any reason.

In further experiments with this improvement it was found that the distance which the nipples 35 were extended in the distributor-header was of import. For example if in a distributor-header having a 4-inch diameter, the inlet to the nipple extensions were disposed about 1 inches from the top of the header, it was found that the innovation only aggravated the situation it was designed to correct, but when the tops of said nipples 35 were adjusted to within about inch from the inner surface of the top of the header (the distance represented by A in Figure 5) complete elimination of explosions during reversal was effected. It has also been determined that not all of the alternate apertures 36 of the distributor-header need be supplied with outlets that are adapted to withdraw gases from a side of the header opposite that which supplied the intermediate apertures, since equally good results have been obtained in a header, such as shown in Figure 1 and which is disposed to supply fuel gas to an entire heating wall, if the nipples 35 are omitted from all the apertures between riserpipe 23 of Figure 1 and points about one-third the distance between said riser and the ends of the distributor.

Divers factors influence the behavior of gases in the distributor-headers to determine "their ;flow:path and type :of flow during the period of purging them of residual gas. .Amongst these factors are the dimensions of the header, the number of heating fines supplied therefrom, the preferred rate :at which .decarbonization air is flowed into the :regeneratonwal-l ducts, stack draft, density of the :gas and the like, and it is therefore obviously impossible .to define specificalrly zany preferred dimensional limitations within which my present invention will give the most desirableresults. "Consequently, Iprefer to have :the nipples 35 .so designed that their inlet ends may :be adej ustably disposed in respect of the jheaderwallsas shown in Figurera. this modification of the invention, the nipple 3-1,;affixed to the lower part of the distributor and disposed within the same, is provided its upper end with threads. The-sleeve-like member 38 is also sprovided with (threads which coeact with those of :thefixed :nipple 131. Bysimply turning member 381cm the threads of 31'Lthe aperture 39 of sleevelike :member 3 8 can :be adjusted to receive gas from a :multiplicity of gas-levels of the distributor-header. An adjustable member of this type can "be advantageously used in the operation of ;my present invention, since as already indicated. the preferred levels of the distributorheaders from which gases should be variously Withdrawn to the heating dues, in order to avoid explosive ignition thereof, must be empirically determinedifor eachindividual coke oven installation because of the diversity of factors that de termine :conditions .of gaseous flow in the headers and which factors will vary from plant to plant. By experi-mentation with various positions of the nipples :35 in the distributors-and variously adapt- :ing them to withdraw gases from the different lheader-rlevels, this device may be employed to eliminate completely those explosions which occur Lin =underjet coke oven distributor-headers during the regeneration heating cycle when the decarbonization air is introduced into the ocking structure through the same distribution system employed for the :heating gas.

1 do not :intend to limit my present inprovemerit itoithe above described.embodiment thereof as shown in Figures :4 and 5. I may prefer for example .to exploit the basic idea :of withdrawing gases of diverse densities from different levels of the same distributor-header simultaneously by means of the apparatus shown in Figures 6 and 7. As is clearly discernible in these drawings it is not necessary to employ means positioned within the header 24 to practice the invention. for it is also feasible to connect the riser-pipes 25 directly to the distributor-header at different levels thereof. In Figure 6, two of the risers 25 withdraw gases from the bottom of the header through. its lateral apertures 36, whereas the remaining two are disposed to withdraw gas similarly from the top of the header. Although I have only arranged the riser-pipes 25 at the top and bottom of the distributor-headers in Figures 6 and '7, I may if I prefer dispose said riser-pipes in such manner as to allow gases contained within the distributor-header to flow not only from the top and the bottom thereof but also from intermediate points without departing from the spirit of my invention. Outlets from the header 24 disposed intermediately of the top and bottom thereof would have the advantage of providing a quick outlet for ,mixed gas that would have a density between the extremes represented :by the heavier air and lighter coal gas.

.The invention :as :hereinabove set forth is embodied in particular form :and manner :but maybe variouslyembodied within the scope of the claims hereinafter made.

Iaclailmt '1. .In a coking :retort oven of the underjet type having said heating wall on either side thereof containing a plurality .of vertically disposed heat ing flues which are communicably connected by riserconduits with the-same distributor-header of a :gas distribution system therefor adapted to supply said heating flues alternately with both rich :underfiring gas and .decarbonization air, a gas.distributor header:being horizontally disposed for horizontal gas flow therethrough and having a plurality of outlets distributed horizontally ltherealong of which each is disposed to supply gases to an individual heating .fiue, rsaid ioutlets leading from the :header at elevations diversely disposed relative to the inner periphery of said distributor-header, .so that gases may be with- ;drawn simultaneously from divers levels of the .sameheader.

2.111 .a horizontal coking retort oven of the underjet type having a heating wall adjacent a side thereof and containing a plurality of vertically disposed heating flues which are communicably connected by riser conduits with the same distributor-headers of a distribution system therefor adapted to supply said heating fiues alternately with both 'underfiring gas and decalbonization air, said gas distributor-headers being horizontally disposed for horizontal flow of heat ing gases to therewith "connected heating flues,

and outlets distributed horizontally along the -respective headers for the riser conduits, said outlets leading from said distributor-headers at elevations diversely disposed in respect of their "inner peripheries so that gases supplied to the heating flueso'f the heating wall will be concurrently taken from divers levels of said distributorheaders 3. An'a'pparat'us as claimed in claim '7 and in which the members adapted to extend into the distributor-header are pipe-like parts having in- :let ports that are adjustably disposed in respect of the walls of said distributor-header.

4. In a coking retort oven battery adapted for regenerative 'underfir'ing according to theunderjet principle and having heating walls provided with a plurality of vertically disposed heating fiues alternately disposed of coking chambers therealong and beneath the battery-supporting mat a distribution system for distributing combustion media, said system comprising, an arterial supply-line from which substantially horizontal distributor-headers branch in substantial parallelism with the above-lying heating walls, each horizontal header being adapted to flow gases to a plurality of heating flues, riser-pipes communicably connecting heating flues and distributorheaders, and means for intermittently introducing underfiring gases and decarbonization air into the same distributor-headers, means adapted to permit the withdrawal of gases from divers levels of the same distributor-headers substantially simultaneously and to deliver the same to the riser pipes, so that gases and mixtures thereof having diverse densities and a consequent tendency to segregate at different levels of the distributor-headers may be provided with outlet means closely adjacent the different levels of possible gaseous stratification in order to obviate entrapment in the distributor-headers of one gas by another of different density.

5. The combination of a battery of regenerative retort coking ovens provided with a rich gas distribution system of the underjet type in which a plurality of heating fines are adapted to be suD- plied with both rich underfiring gas and decarbonization air from the same distributor-header intermittently, and of a substantially horizontally disposed distributor-header that is provided with means for flowing gases individually from a plurality of the gas levels of the distributor-header to the plurality of therewith connected heating flues.

6. In a coking retort oven of the underjet type having a heating wall on either side thereof of which each is provided with a plurality of vertically disposed heating flues some of which are communicably connected by riser conduits with the same distributor-header of a gas distribution system positioned in the oven basement adapted to supply said heating flues alternately with both rich underfiring gas and decarbonization air, said distributor-header being horizontally disposed for horizontal gas flow therethrough and having a plurality of outlet apertures disposed in horizontally spaced relation along the distributor-header hrough which combustion media may be distributed from said distributor-header to the riser conduits of communicably connected heating flues, the points of communication of said outlet apertures being located along the distributorheader so as to approach uniform withdrawal along the header from the various strata.

7. In a coking retort oven of the underjet type having a heating wall on either side thereof of which each is provided with a plurality of vertically disposed heating fiues some of which are communicably connected by riser conduits with the same distributor-header of a gas distribution system adapted to supply said heating fiues alternately intermittently with both rich underfiring gas and decarbonizing air, said distributorheader being horizontally disposed for horizontal gas flow therethrough and having a plurality of outlet apertures similarly positioned in horizontally spaced relationship along the horizontal length of the header and adapted for distributing combustion media to the riser conduits for the heating flues, means whereby gases may be withdrawn from various strata of the distributorheader cross-section through said similarly positioned outlet apertures, said means comprising members that extend into said distributor header from the outlet apertures and communicate with the interior of the distributor-header at alternate diiferent levels from the levels at which others of said outlet apertures communicate.

8. In a coking retort oven of the underjet type having a heating wall on either side thereof of which each is provided with a plurality of verti-' ferent levels from the levels at which others of".

said outlet apertures communicate, whereby gases may be directly tapped off along the header from various strata.

9. A coking retort oven of the underjet type having a heating wall on either side thereof ofwhich each is provided with a plurality of vertically disposed heating fiues some of which are adapted to be supplied intermittently with both rich underfiring gas and decarbonizing air from the same substantially horizontally disposed dis-E" tributor-header of a gas distribution system positioned in the oven basement through outlet apertures in the walls of the distributor-header, and which includes means for improving the turbulence of gases flowed through the distributorheader, said means comprising members that communicably connect at least some of said apertures with the interior of the header and that are arranged in the path of flow of gases flowed through the distributor-header, to divert at least a portion of the gases to both the uppermost and lowermost levels of the interior of the header from the flow path they would otherwise assume, the said apertures and members also being so disposed as to tap directly various strata of the flow path of the gases through the header.

BERNARD J. C. VAN DER HOEVEN.

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