US1818713A - Coke oven - Google Patents

Description

Aug. 11, 1931.

C. H. HUGHES COKE: ovEN` Filed May 13. 192e 2 Sheets-Sheet l mm M 4 TTORNE Y Patented Aug. 11, 1931 PATENT OFFICE CHARLES H. HUGHES, OF HACKENSACK,

ENGINEERING CORPORATION, F NEIN'` YORK, N.

NEW JERSEY, ASSIGNOR TO SEMET-SOLVAY Y., A CORPORATION OF NEW 'YORK 'Y COKE ovEN Application l'ed May 13,

This invention relates to high temperature heat transfer structures, and more lparticularly to heating ues, recuperators, and regenerators, adapted to transfer heat in a byproduct coke oven.

rlihe object of the invention is to. increase the heat transferring efficiency of hot gases partly by causing a concentration of heat transfer lat those surfaces through which the heat is to be transferred, and in part to accencoke.

ing a fuel in the presence Aand burn in the heating iiues,

tuate this concentration, by constructingthe heat transferring surfaces of special material which, it has been discovered, possesses the properties of resistance .against physical destruction under ygiven operating conditions and at the same time preserves to a high degree the property of high heat conductivity. A major constituent of the operating costs of a lay-product coke oven is the cost of the heat required for the carbonization of coal to This heat is usualy supplied by burnof 'pre-heated air in heating iues contiguous to the coking chambers. The customary fuel used is a gaseous one, such as producer gas, water gas, blast furnace gas, coke oven gas, and the like. It is the usual practice' to preheat the low B. t. u. gas in regenerators or recuperators as Well as the air required for the combustion. The pre-heated air and fuel gas meet as noted :heretofore. These burning gases flow through the heating flues and transmit their heat to walls ofl the latteru The heat -then iiows through the walls proper to the charge of coal in the coking chambers. The material usually used for the` construction of these flues contains silica and is not a rapid conductor of heat. Consequently, with the silica material an excessive high and-wasteful temperaturemust be maintained in the heating tlues in order to attain an ethcient carbonizing temperature in the coking chambers. In other words, the heat enerated in the flues to coke a charge of coal in the cokin chamber must be greatly in excess of that t eoretically needed, since the low heatconductivity of the wall between the heating ue and the coking chamber inter-poses a resistance which must be constantly overcome in order that 1926. Serial No. 108,751.

the requisite degree of heat actually reaches the coal. In order, therefore, to maintain y in thellues a temperature necessary for the coking operation in the coking chamber, excessive l quantities of fuel must be burned. Moreover, Walls constructed of silica brick, spawl and crack at oven necessitating constant and expensive repairs and renewals.

A substantial saving in the heat required for carbonization could be eected by constructing the heat transferringwall of. material having a high coefficient of heat conductivity, but heretofore it has been believed, upon the basis of numerous experiments, that no material possessing the property of high heat conductivity was sufficiently durable, physically, to withstand disintegration under the prevailing operating conditions. I have, for example, myself endeavored touse material such as Well known carborundum refractories, but found that as a general rule such refractories failed to function satisfactorily, especially in that they failed to withstand conditions such as are prevalent in a coke oven flue. I have nowfound, however, that a refractory wall, when made of shapes or bricks of special refractory material composed chiefly of a component possessing hi h heat conductivit but containing also an a equate amount o a component which though of less heat conductivity supplies the required cohesive strength Will function successfully under conditions prevalent in the heating ues such as those of a by-product coke oven. It is preferable to have the highly conductive component present in the refractory in amounts such that the high heat transmitting qualties thereofv is imparted to the refractory as a Whole. A typical proportion of components is approximately 90% of carborundum (silicon carbide) and approximately 10% of a highly refractory bonding material such as refractory clay. The proportion of carborundum cannot he increased very substantially over" 90% without destroying the capacity of the bricks to withstand the eHects of the operating conditions, and the proportion of the bonding component must' never be reduced to such a degree that the resulting retemperatures, thus l fractory fails physically and structurally under actual conditions of operation.. l prefer to use a maximum quantity of the highly conductive component and a minimum quantity of the bonding and strengthening component. rlhe percentage of the latter component, although it may be increased, is preferably as lo'vv as possible Within the limits of the required strength and bonding necessities of the refractory under particular circumstances. In other Words, what l require is a silicon carbide brick of high physical strength under the heat conditions prevailing in ley-product coke oven practice. A commercial embodiment of the refractory material heretofore described is typified by the carborundum refractory known as carbofrax B disclosed in the patent to ITone, No. 1.2%,211 of November i, 1916. Carbofrax B, contrary to the experience With other refractories of a similar nature, is suihciently durable to withstand disintegration, 'While ar, the same time possessing to a high degree, the desired property of high heat conductivity. In carbofraa B I have 'therefore discovered a. material which by reason of its constituents possesses a high coeflicient of heat conductivity, While at the same time the material is extremely resistant against disintegrating effects under the prevailing operating conditions. In fact, a Wall of carbofrax B is much stronger at oven `temperatures than a Wall of silica brick, and does not vshrink or expand as much as a Wall made of the latter material.` It is this nevv and unexpected property of the carbofran IB material which thus maires it peculiarly adaptable for the purposes of use as the heat transferring Wall of a coke oven flue..

- In a flue provided with a heat-transferring Wallof carbofrax B material, it vvill be apparent that the non-heat-transferring Walls of the due, when 'composed of material of a lower coemcient of heat conductivity, Will result ina concentration of heat transfer at that part of the line `which is specially intended for the transfer of heat, and that the transfer of heat consequently, through the high heat conductive section of the nue, is intensified and accentuated. This concentration of eihciency may be intensified/by partially or entirely lining or enclosing the heat transfer structure With a special heat-insulating material having a lower coeihcient of heat conductivity than the customary silica brick. Such an insulating lining or shell Will prevent heat losses through the division Walls, roof, foundation, and other parts of the coke oven. By isolatingl each heattransfer unit, the is concentrated, thus facilitating the transmission of heat from the heating fluid to the hody to be treated. The special material which l have found suitable for use' as the heat insulating material, is Zhconia.Y The combination, therefore, of carbofraX B malaria as the material constituting the heat transferring surfaces and of zirconia as the material constituting the heat insulating surface, is extremely useful for high temperature structures such as coke ovens, particularly in that the coefficients of expansion of these tvvo niaterials are approximately alike. l`he relation betweenzirconia and carbofrax B with reference to their respective coeficiente of erpansion isof marked importance, for it is this lproperty which makes the conjoint use of these two materials pecularly and specially appropriatev for the special conditions prevalent in coke oven practice.

The tendency in the structure tovvard cracking and rupturing, due to temperature changes, is therefore greatly reduced, while the efficiency of each part, especially in conjunction with or in relation to the other parts of the structure is materially enhanced.

My invention is applicable,vnot only to the heating fines of Toy-product colte ovens, but also to the heat economizing systems of such ovens as exemplified in their usual recuperators or regenerators, as vvell as to other types of high temperature heat transfer apparatus.v

The yinvention is illustratively exemplified ,p

tional view of a part of a recuperator system embodying my invention. lif. l is a sectional view of a regenerator of a y-product coke oven embodying my invention.

Similar characters of reference designate similar parts throughout the accompanying drawings.

Referring noW more particularly to Figs. l` and 2 of the drawings, the numeral l designates a coking chamber of a ley-product coke oven having heating lines 2 of the horizontal type and division Walls 3 adjacent thereto, all other parts of the oven being omitted for the purpose of clarity. rlhese ovens, generally speaking, are composed of a series of pa'rallel coking chambers similar to chamberl l, having heating lues interposed between adv jacent chambers in colte ovens of the vertical flue type, and heating-:dues adjacent to each side of each colring chamber in ovens of the horizontal llue t pe. ,1 The heating ues may be of any type, ut are usually eithe of the horizontaler the vertical typ-e. ln many ovens, particularl those with horizontal fines, division ,Wallis of heavy masonry construction are built between contiguous coling chambers, thus 'isolating each chamber with its heating dues. Associated With the ilues are heat economizers or interchangers which function in a Well-known mannerand usually consist of either regenerators or recuperators.

ltion the outer walls According to the present invention, the inner walls C ofthe heating flues 2 contiguous to theinterior of the coking chamber 1 are preferably made of carbofrax B. The thermal head or gradient through carbofrax B is approximately but one-fifth of that through the conventional silica material.

In the preferred embodiment of my inven- R of the heating 'llues 2 are made of a refractory material having a very low coelicient of heat conductively, preferably zirconia. Zirconia and the like are heat. insulators which transmit heat very slowly, and thus prevent the loss of heat from the heating flues. In some cases it is advantageous to encase not only the outer walls of the heating lues, but also the exposed portions of the coking chamber in a shell 'of inheating fines,

. ing in the num fio sulating material 'R as shown in Fig. 2. By this arrangement the coking chamber and related lues are isolated so that the heat from the heating fluid is concentrated in the chambers and is thus utilized with substantially no loss. y

In the operation of a by-product coke oven embodying my invention, the chambers 1 are charged With coal in the usual manner. l Fuel gas is burned in the heating flues 2 to supply the heat necessary to carbonize the coal to coke. vDue `to the fact that only a smalll therinal head or gradient is required to force the heat through my improved 4lining of the a temperature very muchl lower than that employed'heretofore in the heating lines may be used. Since the upper temperature limit is lower, the amount of heat required is greatl reduced, and thus the savr of B. t. u.s generated tc coke a ton ofcoal is considerable. When my insulating lining or shell is used in conjunction with my conducting lining, an additional saving in heat, and thus in fuel, is obtained. The linsulatin shell prevents the heat from flowing or lea ing into they division walls 3 or into the roof,masonry orl foundation of the coke ovens, all indicated as B in the drawings. By this arrangement the heat losses usually occurring 'in a'by-product'colre oven from radiation, cbnvection, and conduction, are reduced to a minimum.

lA 1oy-prodlict coke oven-embodying my invention olers great flexibility in operation, so that any desired type of co e or'set of bg'- products' may be obtained accordinl tot e mode of operation. By utilizing t e same amount of heat per ton of charge which is now being used, I am ing time substantially, thus materially. reducing the fixed charges per unit of output and increasingV the capacity of the equipment. For example, in an illustrative instance, the coking time is reduced from twelve to eight hours, thus increasing the daily capacity of the equipment vfifty4 percent. On the other hand, w

able to reducel the cok-A en the same period of time as now usedA for coking 'a charge of coal is employed, the quantity of heat required to coke a ton of coal is reduced substantially. As an illustrative example, the heat required may be reduced from 2,100,000 B. t. u. per ton of coal to 1,500,000 B. t. u.' perton of coal, thereby nakinlg a reduction of 600,000 B. t. u. per ton o coa My invention may also be used to advan-` large channel is for the hot Waste gases comin from the heating lues of an oven' and going to the waste stacktwhereas the two small channels are for cold incoming air from the 'atmosphere going tothe heating flues.

The separating walls C, interposed between the air channels or passages and the hot waste gas channel or passa e, are'composed of carbofrax B. Surroun in the said passages is a shell R composed o insulating material, preferably zirconia.` By this construction the transmission of heat from the hot waste gas to the cold incoming air is facilitated, whereas the low ofleakage of heat to the surrounding masonry is prevented; The air is thus pre-heated to `a `higher tem erature than formerly, and, consequently, higher temperatures may be attained in the heating flues. At the saine time the temperature ofthe waste gas is reduced, so that the `thermal eliiciency of the ovens is increased.

In Fig. 4, a regenerator is shown embodying my invention. The regenerator is built of ychecirerbrielrs C in the usual manner.

These checkerbricks are composed of carbo-` frax B. It is advantageousv to encase the highl conductive checkerbriclc structure in a she l It of zirconia insulating material so that substantially all'of the heat is retained within the checkerbrick and practically none of the heat is permitted to escape. In the operation of a lay-product coke-oven the hot waste gas from the heating flue or'flues surrounds the checker-brick on its way to the chimne As the vas passes throu the' spaces tween the gheckerbrick, it gives up its heat to the latter. By making the checkerbrick of material of high heat conductivity, all theI heat that is practical to withdraw from the hot waste gasv is withdrawn. Upon the reversal of flow of gas, cold air passes in contact with the hot checkerbricks which give up their heat quickly to the air. The transfer of heat the heat of the checkerbricksis transferred iis ist

to the air, thus raising the temperature thereof to a high value. Moreover, since my improved regenerator possesses a high rate of heat transfer, it may be constructed smaller than the customary type of regenerator, thereby effecting a substantial saving in the .initial capital cost of the structure. The inof each of the heating flues being adjacent to the coking chamber, the Walls adjacent to the coking chamber comprising a high heattransmitting material consisting of approxmately 90% vsilicon carbide and approximately 10% of a refractory bonding material, and the opposite Walls of said heating lluescomprising a heat insulating material consisting substantially of zirconia.

2. A by-product cokeoven comprising coking chambers and heating Walls therefor arranged side by side in alternate relation, said heating Walls comprising combustion lues, a part of the walls-of each of which are disposed adjacent the coking chambers the walls lof said flues disposed adjacent the cokiiig chambers comprising material having substantially all the properties of a refractory material consisting of approximately 90% silicon carbide and 10% refractory bonding material, and the remaining Walls of said ilues comprising material having substantial ly all of the properties of zirconia.

3. In a coke oven, the combination with a coking chamber,v of heating lues, a part of the Walls of each of which are adjacent to op- I posite sides of said chamber, the walls of said flues adjacent to said chamber comprising approximately 90% silicon carbide and 10% of refractory bondingmaterial, and an insulating shell of material having substantially all of the properties. of zirconia surrounding said chamber and the walls of said lues opposite to the first mentioned wallsl 4. In a high heat-transfer a paratus, heating flues, a part of the walls o each of which are adapted totransmit heat and the remain'- ing Walls of which are insulated against the passage of heat, the heat-transmitting Walls comprising high heat-transmitting material consisting of approximately 90% silicon carbide and approximately 10% of 'a refractory bonding material, and the insulating walls comprising zirconia.

5. In a b -product coke oven, a coking chamber an heating fines, part ofthe walls of each of the heating flues being adjacent to the coking chamber, the Walls adjacent to the coking. chamber comprising a material having a high heat conductivity and physical strength'and theopposite Walls of said heating ues comprising zirconia.

6. In a cokeovema coking chamber and heating flues, part of the Walls of each of the heating flues being adjacent to the Acoking chamber, the ue walls opposite to the walls adjacent to the coking chamber comprising heat insulating material comprising zirconia and the ue walls adjacent to the cokin throughout of a carborundum ing a high heat conductivity. i

In a coke oven,a coking chamber and heating iues, part of the Walls of each of the heating flues being adjacent tothe coking chamber, the flue Walls remote from the coking chambery comprising a heat insulating material consisting substantially of zirconia, While the flue walls adjacent to the coking chamber comprise material consisting of approximately 90% silicon carbideand approximately 10% of a refractory bonding material material havg chamber .being comprised substantially and having a high 'heat conductivity and physical strength and having a coelicient of expansion approximately equal to that of zirconia.

8. A by-product coke oven having heating-y passages for the hot gases, prising heat transferring of approximately 90% of approximately 10% eilicient of expansion approximating that of zirconia.

9. In a coke oven ofthe type set forth in claim 5 in which the zirconia material forms a continuous protective envelope about' said heating flues and coking chamber.

10. In a by-product coke o ven, a coking chamber and heating lues, 'part of the Walls of leach of the ,heating flues being adjacent to the coking chamber, to the cbking chamber comprising material containingl approximately 90% silicon carbide and approximately \10% iire clay, and

said passages comelements composed.

having a coeicient of expansion approximating that of zirconia, and the remainin Walls ofT said heating flues being comprise of zirconia.

11. In a by-product lcoke oven, a coking chamber and heating ues, a part of the walls of each of the heating fines being adj acent to the coking chamber, the Walls adjacent to the coking c amber comprising a high heattransmitting material consisting of approximately 90% silicon carbide and approximately 10% of a refractory bonding material and the opposite walls of said heating fluesbeing comprised of a heat insulating material.

12. A coke oven, having heating flues which have high heat-transmitting portions comprised of a refractory material consisting of approximately 90% silicon carbide andapproximately 10% of a refractory bonding material.

silicon carbide and. fire clay and having a cov the walls ad] acent structure,

means defining a space adjacent heating flues,

13. A byproduct coke oven having a coking chamber and heating filles, part .of the Walls of each of the heating lues being adjacent the coking chamber and said walls adjacent to the coking chamber comprising a high heat-transmitting material consisting of approximately 90% silicon carbide and approximately 10% of a refractory bonding material.

14. In a high temperature heat-transfer the combination of an insulating shell composed substantially of zirconia,

cent space for recelving heat from said passage a being composed of high heat-transmitting material consisting of approximately 90% silicon carbide and approximatelyl0% of refractory bonding material.

15. In a coke oven, a coking chamber and the -lue wall on'the side next. to the coking chamber space being composed of carborundurn brick of substantially the same coeiicient of expansion as v Zirconia and the opposite Wall of the flue being composed of zirconia brick.

Intestimony whereof I have hereunto set my hand. CHARLES H. HUGHES.-

passage within the shell for` a heating fluid positioned to forml an adja-v the walls of said passage adjacent said n

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