Abstract: The present technology describes various embodiments of methods and systems for improved coke quenching. More specifically, some embodiments are directed to methods and systems for improving the coke quenching process by partially cracking coke before it is quenched. In one embodiment, coke is partially cracked when placed in horizontal communication with one or more uneven surfaces. In another embodiment, a coke loaf is partially broken when dropped a vertical distance that is less than the height of the coke loaf. In another embodiment, a mass of coke is partially broken when first placed in vertical communication with one or more uneven surfaces and then placed in horizontal communication with the same or different one or more uneven surfaces. In some embodiments, the one or more uneven surfaces may be mounted to a coke oven, train car, hot car, quench car, or combined hot car/quench car.

Abstract: Oxycombustion process wherein a combustor is fed with a fuel, a comburent and compounds under the form of coherent aggregates having Young modulus ?104 MPa, the combustor being isothermal and flameless.

Abstract: The ovens (F) are arranged side by side in a battery and are each delimited by two sidewalls (10) formed by side bricks (11) and joined by transverse bricks (12, 13). The method comprises: cutting each sidewall (10) to be repaired in accordance with a cutting plane (PC) defining a respective end flat face (14) in the middle portion of the wall (10a) to be maintained and coinciding with the face of a row of transverse bricks (12, 13) facing an adjacent end wall portion (10b) which is being removed; providing in each flat end face (14), a pair of cutouts (15), each having in a basic transverse face, a longitudinal middle channel (15c) in which a tongue (11c) of new bricks from a new end wall portion (10b) is fitted; fitting in each cutout (15) a corresponding portion of a vertical row of side bricks (11a, 11b) for the new end wall portion (10b) until the formation is complete.

Abstract: The present technology is generally directed to systems and methods for controlling air distribution in a coke oven. In a particular embodiment, a coke oven air distribution system comprises an oven chamber having an oven floor configured to support a coal bed, a plurality of sidewalls extending upward from the oven floor, and an oven crown covering a top portion of the oven chamber. The air distribution system further includes an air inlet positioned above the oven floor and a distributor proximate to the inlet. The inlet is configured to introduce air into the oven chamber and the distributor is configured to at least one of preheat, redirect, or spread air within the oven chamber.

Abstract: Embodiments presented herein describe an apparatus and method to control the conversion of carbonaceous materials, particularly biomass and those biomass resources, into a high performance solid fuel. This method, and the apparatus described as the means to accomplish this method, provides a process having a control system that enables the system to produce a fuel of uniform quality, even with a change in biomass supply.

Abstract: A device for proportioning of secondary combustion air into the secondary air soles of coke oven chamber ovens is shown. The device is formed by a slide gate or a parallelepiped device or by plates moved by means of a thrust bar, the thrust bar being moved longitudinally in parallel to the coke oven chamber wall so that the plates move away from the secondary air apertures and open or close these. The thrust bar is moved by means of a positioning motor, with the power transmission being effected hydraulically or pneumatically. Via suitable measuring parameters, it is thus possible to optimize secondary heating so that heating is provided evenly from all sides, thus achieving an improvement in coke quality.

Abstract: A method for producing individual compacts made of coke and suitable for coke oven chambers by dividing a coal cake in a non-mechanical manner, wherein the coal cake is produced by a compression method according to the prior art and the coal cake is divided by non-mechanical, energy-supplying media, and the non-mechanical media supplying shearing energy are, for example, a laser beam, a high-pressure water jet, an abrasive-solid jet, an ultrasonic beam, a compressed-air jet, or a gas jet. By using the method, coal compacts can be produced from coal cakes without forming dust, without wearing out cutting tools, and with high precision.

Abstract: A method and an apparatus for pyrolysing a solid organic feed material are disclosed. Solid organic material is moved through a reaction chamber and exposed to a temperature profile within the chamber that dries and pyrolyses the organic material and releases water vapour and a volatile products gas phase. The water vapour phase and the volatile products gas phase are moved counter-current to the solid organic material so that the water vapour phase and condensable components of the volatile products gas phase condense in cooler upstream sections of the chamber and form a liquid water product and a separate liquid oil product. The liquid water product is discharged via an outlet along the length of the chamber and a dried and pyrolysed solid product is discharged from a downstream outlet in the chamber. The chamber includes a plurality of heat transfer members extending within the chamber and a supply of oxygen-containing gas for establishing and maintaining the temperature profile within the chamber.

Abstract: A improved solar biochar reactor, system including the reactor, and methods of forming and using the reactors and systems are disclosed. The methods and system as described herein provide sufficient solar energy to a biochar reactor to convert animal waste or other biomass to biochar in a relatively cost-effective manner.

Abstract: A coking oven has a battery of longitudinally extending and transversely spaced coking chambers each provided with a plurality of downwardly open and longitudinally spaced filling holes. Coal is charged into the chambers through the respective filling holes. A respective longitudinally movable leveling rod in each of the chambers can level coal charged by the filling equipment into the chambers. Sensors provided on the leveling rods scan from above transversely and longitudinally spaced points on a surface of the coal charged through the holes into the respective chambers. A controller connected to the sensors records a respective measurement corresponding to a vertical position of the surface at each the points and determines from the measurements thereof a three-dimensional filling-level profile of the surface of the charged coal for controlling operation of the filling equipment and filling of the chambers with the coal.

Abstract: Described is a method for the coking of coal, in particular coal with a high or alternating volatility, in coking plants comprising coking chambers, according to the non-recovery method or the heat-recovery method. Also described is device, which can be used to carry out said method simply, as the overheating of the coking furnace is prevented by the injection of water vapor. If a battery of coking furnaces is used, the disclosed method can be carried out irrespective of the number of said furnaces.

Abstract: Methods, processes, apparatus, systems, and compositions are disclosed for improving the sustainability of oil sands processing. In some embodiments, bitumen is combined with biodiluent comprising one or more liquid pyrolysis fractions obtained from pyrolyzing biomass and collecting multiple liquid fractions. The bitumen may be any source of bitumen, such as bitumen obtained from oil sands. In some embodiments, a water-rich pyrolysis liquid displaces water use in an oil sands process. The water-rich pyrolysis liquid may be used for primary separation of bitumen from oil sands or for hydrotransport, for example. Also, biochar produced from biomass pyrolysis may be introduced to an oil sands tailing pond with various benefits. Water may be recycled from a tailing pond. Integration of a pyrolysis and separation process into an oil sands refining process reduces the overall greenhouse-gas emissions on a well-to-refined product basis by 10-70% or more. Various compositions and products are also disclosed.

Abstract: A system and process for gasification of a carbonaceous feedstock uses pyrolysis to produce a gas product, which may include methane, ethane, and other desirable hydrocarbon gases, and a solids product, which includes activated carbon or carbon. The gas product may then be filtered using at least a portion of the activated carbon from the solids product as a filtering medium. In an embodiment, at least some of the noxious chemicals are sequestered or removed from the gas product in one or more filtering steps using the activated carbon as a filtering medium. In a further embodiment, the filtering steps are performed in stages using activated carbon at different temperatures. A high-temperature pyrolysis system that produces activated carbon may be combined with another high-temperature pyrolysis system that does not produce activated carbon to provide filtering of noxious compounds using activated carbon from the first high-temperature pyrolysis system.

Abstract: A method for collecting biomass, such as straw, and for producing a pyrolysis liquid, such as oil or tar, from the biomass, includes the step of collecting the biomass from a growth site, e.g. a field, by means of a mobile unit. The biomass is continuously fed into a pyrolysis apparatus accommodated by the mobile unit, as the mobile unit is moved across the growth site. While the biomass is processed in the pyrolysis apparatus, further biomass is simultaneously being collected. The pyrolysis apparatus may be a flash pyrolysis or fast pyrolysis apparatus relying on centrifugal forces for forcing biomass towards a reactive surface in a pyrolysis reactor. The mobile unit may be self-propelled.

Abstract: A fast pyrolysis apparatus (200) for producing pyrolysis liquid, such as oil or tar, char and pyrolysis gas from biomass, such as straw, comprises a centrifuge chamber (204) and a rotor (210) arranged to impart rotation on the biomass in the centrifuge chamber to force the biomass outwardly under the action of centrifugal forces. A furnace (206) arranged coaxially around the centrifuge chamber (204) maintains the temperature at an outer reactive wall of the centrifuge chamber at an elevated temperature to effect the pyrolysis process at or near the reactive wall. The apparatus comprises a condenser (218) arranged coaxially with and surrounded by the centrifuge chamber (204). The apparatus may be accommodated by a mobile unit for simultaneously collecting biomass from a field and processing the biomass in the apparatus.

Abstract: A deheader valve is fitted onto an existing or new coke drum by initially positioning the body and valve, and then raising the valve to mate with the flange using a lifting device other than a chain fall. The vertical positioning of the deheader valve is preferably accomplished with a hydraulic or pneumatic piston, winch, scissor jack, ratchet jack, screw jack, and so forth. The distance traveled by the valve using these devices is more than 2 cm, commonly at least 20 cm, and in some installations up to 40 cm or more. In retrofit situations an oil inlet is provided in a side wall of the drum above the bottom drum flange.

Abstract: The invention relates to a coke oven of a non-recovery horizontal type of construction, known as a non-recovery or heat-recovery coke oven, in which the coke oven floor is made up of at least two layers and each layer is formed of the same or different silica materials, wherein the first layer, seen from the oven space, is formed from a solid refractory material and the second layer comprises a multiplicity of openings, gaps, apertures or the like, the gas spaces of these openings, gaps, apertures or the like being in communication with the gas space of the flue gas duct running under them.

Abstract: The method enables the attainment of an open and continuous flow of an aqueous slurry containing carbonaceous solids into a high-pressure and high temperature environment which will result in the occurrence of at least two chemical processes: (1) aqueous pyrolysis (hydrous pyrolysis) and (2) hydrolytic disproportionation. This combination of processes will effect conversion of suspended organic materials into hydrocarbon liquids or gases depending on the mix of the temperature, pressure, and residence time in the reactor. Thereafter, the hydrocarbon-bearing slurry can be refined (separated into various constituents) using standard existing technologies.

Abstract: Relatively high speed methods for increasing the bulk density of coal particles, apparatus for increasing the bulk density of coal particles and methods for making metallurgical coke. Once such method includes depositing coal particles onto a charging plate external to a coking oven to provide an elongate bed of dry, uncompacted coal having an upper surface of the charging plate. The charging plate has side walls, and at least one movable end wall An impact pressure is applied to the upper surface of the bed of dry, uncompacted coal while degassing the coal to provide a dry, compacted coal bed having a bulk density ranging from about 960 to about 1200 kilograms per cubic meter.

Abstract: A coke drum bottom de-heading system having an internal shroud enclosure and a shroud end cap opened by a flange to a coke bottom de-heading valve capable of accepting the end of a gate valve upon actuation. Acting in coordination with the shroud enclosure to prevent the escape of steam is a gate seal assembly having a gate seal slidably engaged against the sliding gate to prevent the passage of steam thereby.

Abstract: A coke drum bottom de-heading system having an internal shroud enclosure and a shroud end cap opened by a flange to a coke bottom de-heading valve capable of accepting the end of a gate valve upon actuation. Acting in coordination with the shroud enclosure to prevent the escape of steam is a gate seal assembly having a gate seal slidably engaged against the sliding gate to prevent the passage of steam thereby.

Abstract: To make it easier to carbonize the processing target material to a desired carbonized condition and also to make installment within a limited installment space possible. A carbonizing apparatus includes a carbonizing furnace having a feeding portion for a processing target material, a takeout portion for a carbonized material, a blowout portion for combustion air and an exhausting portion for combustion exhaust gas and a stirring device capable of stirring the processing target material inside the carbonizing furnace. The blowout amount of the combustion air is adjustable. The apparatus is operable to carbonize the processing target material fed from the feeding portion, with stirring, spontaneously combusting and moving the material while moving this material toward the takeout portion and subsequently to take out the resultant carbonized material from the takeout portion.

Abstract: Methods are disclosed for pyrolizing carbonaceous materials to carbonaceous materials having lower boiling points by heating the carbonaceous material to a desired reaction temperature and holding the carbonaceous material in contact with the heat for a sufficient time to achieve the desired reaction to a lower boiling point carbonaceous materials, then rapidly cooling the desired reaction products. The heating source is a jet which will provide hot and high velocity gas streams to the carbonaceous material to be heated.

Abstract: A method and a device for the hot-repairing of the heating flues of a coke-oven battery according to which the completed sections of a heating flue still under construction are heated by means of a heated gas. The heated gas comprises the air usually provided for combustion in the heating flues during coking operations. The air is guided through the flow paths provided for in the coke-oven battery for combustion air and waste gases as well as through the regenerator, heated as it passes through the flow paths and then guided through the heating flues to be repaired. The completed section of the heating flue is separated from the non-completed portion by an air-reversion device that also directs the heated air.

Abstract: A coke drum bottom head removal system and method for deheading the bottom head cover of a coke drum comprises a carriage that is positionable beneath the bottom head cover, and a cart mounted to the carriage. Several clamps vertically mounted to the cart are positionable in a closed position, in which the clamps apply a compressive force that maintains substantially fluid tight engagement between the bottom head cover and bottom head flange, and an opened position, in which the clamps allow a limited spacing between the bottom head cover and the bottom head flange. A plurality of supports mounted to the cart support the bottom head cover once the fasteners coupling the bottom head cover to the bottom head flange are removed and the clamps are in the opened position. The system can be remotely operated to enhance operator safety when the bottom head cover is removed.

Abstract: A coke oven and a method of operating the same, capable not only of achieving a uniform combustion temperature heightwise within a combustion chamber when a rich gas or a lean gas is burnt, but also of reducing NOx content in the waste gas, while eliminating localized high-temperature combustion. The combustion chamber of the coke oven comprises a rich-gas port 2 located near an oven wall 6 bordering a carbonization chamber in the bottom 5 of combustion chamber, and the midpoint P3, connecting the center P2 of a lean-gas port 7 and the center P of an air port 3, is on the side opposite to the rich-gas port 2 relative to the center line CL of the combustion chamber. (See FIG.

Abstract: A low-energy input process for the pyrolytic conversion of biomass to charcoal or carbonized charcoal is provided. The biomass is sealed in a container, pressurized with air and heated to ignition. Control of pressure by input of air and release of gases to maintain successively lower pressure levels results in a typical time for the conversion of less than 30 minutes.

Abstract: An improved method and apparatus is disclosed for reclaiming volatile products and non-volatile residue through the pyrolysis of a polymeric material comprising placing the polymeric material in a reactor and establishing an oxygen deficient atmosphere in a reactor. The polymeric material is simultaneously compressed and heated to a temperature sufficient to pyrolyze the polymeric material to produce volatile products and non-volatile residue. The volatile products and non-volatile residue are subsequently removed from the reactor and collected.

Abstract: A method and an apparatus for heating fluid with a gas heater and distilling fluid with the pilot light of the gas heater are disclosed. The apparatus for heating fluid and distilling fluid includes a main tank for containing fluid to be heated, a heater, adapted to have a pilot light, for heating the fluid in said main tank and an evaporator tank for vaporizing fluid received therein with heat from the pilot light. The method of heating fluid and distilling fluid includes heating a first volume of fluid with a heater having a pilot light and heating a second volume of fluid with the pilot light.

Abstract: A conventional method of pyrolytically decomposing plastic to make low-molecular compounds is poor in efficiency of use of energy due to high heating temperatures (at least 600° C. and 800° C. at maximum).

Abstract: A method and an apparatus for heating fluid with a gas heater and distilling fluid with the pilot light of the gas heater are disclosed. The apparatus for heating fluid and distilling fluid includes a main tank for containing fluid to be heated, a heater, adapted to have a pilot light, for heating the fluid in said main tank and an evaporator tank for vaporizing fluid received therein with heat from the pilot light. The method of heating fluid and distilling fluid includes heating a first volume of fluid with a heater having a pilot light and heating a second volume of fluid with the pilot light.

Abstract: When a pitch composition prepared by mixing 100 parts by weight of mesophase pitch with 10 to 1,000 parts by weight of coal tar pitch, is heat-treated at a temperature of 500° C. or higher, it is possible to produce a high-density coke at a high yield while avoiding the foaming of the mesophase pitch. In addition, when the coke is graphitized at a temperature of 2,000° C. or higher, it is possible to obtain an artificial graphite having a high graphitization degree. Further, when the coke is first pulverized and then graphitized at a temperature of 2,000° C. or higher, it is possible to obtain a high-crystallinity graphite powder which can be suitably used as a carbon material for a negative electrode of non-aqueous solvent type secondary battery having a high discharge capacity and a high charge-discharge efficiency.

Abstract: A pressure controller for a coke box has a fan assembly and a valve assembly selectively coupling the fan assembly to the coke box. A barometer senses a pressure level in the coke box. A control element controls a speed of the fan assembly to maintain the pressure level in the coke box below a desired pressure level.

Abstract: A method is provided for cooling coke drum deheading devices, thereby extending the life of same. The method calls for spraying water or other coolant on the devices when they are in operation.

Abstract: A blast furnace coal is produced by rapidly heating a coal blend having 10 to 30% by weight of a non-slightly-caking coal having softening initiation temperature T with the balance including a caking coal having softening initiation temperature T.sub.0 (T.sub.0 .ltoreq.T +40.degree. C.) at a rate of 1.times.10.sup.3 to 1.times.10.sup.6 .degree. C./min to a temperature region from (T -60.degree. C.) to (T +10.degree. C.) wherein T represents the softening initiation temperature of the non-slightly-caking coal; or rapidly heating a non-slightly-caking coal having softening initiation temperature T and a caking coal having softening initiation temperature T.sub.1 separately at a rate of 1.times.10.sup.3 to 1.times.10.sup.6 .degree. C./min to a temperature region from (T -100.degree. C.) to (T +10.degree. C.), wherein T represents the softening initiation temperature of the non-slightly-caking coal, or a temperature region from (T.sub.1 -100.degree. C.) to (T.sub.1 +10.degree. C.), wherein T.sub.

Abstract: The cycle time for a delayed coker unit is reduced by externally heating the coke drum near the junction of the drum shell and the supporting skirt thereof prior to beginning the hot coker feed fill step. This reduces the thermal stresses at the area around the welds of the drum skirt.

Abstract: A method of reducing the airburning tendency of petroleum coke and carbon anodes made therefrom includes calcining the coke and spray quenching the calcined coke with an additive-containing water. The additive includes an effective amount of a compound of aluminum which is soluble in the quench water. The additive is deposited on the quenched coke product surface and protects the coke from oxidation or premature combustion when in contact with the atmosphere at high temperatures. The additive-coated coke can then be formed into an anode which also has a reduced tendency to airburn during use in a high temperature environment such as an aluminum reduction cell or an electric furnace operation.

Abstract: Renovation of a heating wall, in particular a heating wall of a coke oven battery, includes starting with a vertical wall raising of a part to be renovated on a wall protective plate of the part, abutting a new masonry exactly on the wall protection plate, and arranging between the new masonry and the old masonry a vertically extending welding joint from a ceramic material.

Abstract: A method for operating a battery of coke ovens capable of accomplishing an increase in production and a decrease in the quantity of heat required for carbonization. The battery of cove ovens include a plurality of carbonization chambers to which a series of working numbers indicating the order of unit oven workings are assigned. An operation step is repeatedly practiced which includes a working step of carrying out the unit oven workings in the order of working numbers with respect to the carbonization chambers without providing a working interrupting time between the unit oven workings and an interruption step of interrupting the unit oven working until the the carbonization chamber of the coke oven which has been first subject to the unit oven working reaches a time at which discharge from the carbonization chamber is made possible.

Abstract: Individual coke ovens in a nonrecovery coke oven battery are charged through an open door at the pushing end of the ovens, and emissions escaping through the open door of the respective ovens during charging are captured by a hood mounted on the pushing and charging machine for movement therewith along the pushing side of the battery and for movement thereon from a retracted position spaced outwardly from the ovens and a capturing position above the open oven door. Air and emissions captured by the hood are withdrawn and passed through an air cleaner mounted on the pushing and charging machine to remove smoke and particulates before being discharged to the atmosphere.

Abstract: Renovation of a heating wall, in particular a heating wall head of a coke oven battery, includes starting with reconstruction of the wall to be renovated on a wall protective plate of the part, abutting a new masonry exactly on the wall protective plate, and arranging between the new masonry and the old masonry a vertically extending welding joint for sealing the ceramic welding after heating up the new masonry, which means after reaching final thermal expansion of the new masonry.

Abstract: According to this invention there is provided a process for the heat treatment of noncaking, noncoking coal with a process derived gaseous fuel having a variably controllable calorific heating value.

Abstract: This invention comprises a method and apparatus for removing oil and tar based wood preservatives from sawdust. A pole treated with oil or tar basee wood preservative is shaved to remove the treated outer wood layer, leaving the interior preservative free. The sawdust is subjected to rapid heating in a turbulent oxygen-free gas stream and the oil and tar are rapidly distilled from the sawdust. The sawdust and gas are separated in a mechanical separator and the hot gas is rapidly cooled, condensed and recovered.

Abstract: A method of controlling operation of a nonrecovery coke oven battery including a plurality of elongated coke ovens constructed in side-by-side relation with each oven having a separate system of sole flues beneath each end connected to the crown of the oven by measuring the temperature in the oven and regulating the draft to the oven in response to the measured oven temperature and by measuring the temperature in the sole flue systems beneath each oven and adjusting the draft to one of the sole flue systems only in response to differences in temperature in the two sole flue systems.

Abstract: A plant for treating industrial and/or urban waste includes a stage for drying of the waste, followed by a stage for effecting thermolysis of the dried waste and a stage for effecting recovery of the solids and gases resulting from the thermolysis. Thermolysis of the waste is effected in a reactor by indirect heat exchange with combustion gases and drying gases for drying of the waste are subsequently treated to remove vapor materials and then recycled to a gas generator for generating the drying gases. Additionally the plant includes a stage for effecting dechlorination of the solids resulting from the thermolysis by washing the solids with an aqueous liquid, as well as a stage of separating the wash solids and the resulting wash liquid.

Abstract: An automated top head cover and stem guide assembly adapted for covering a top opening in vertical vessels such as coking drums, and a method for remotely operating the assembly. The top head assembly includes a flanged connector unit attached pressure-tightly to a top flange opening of a coking drum and a top cover device including a cover unit pivotally attached to the flanged connector unit, so that the cover unit can be pivotally lifted and moved aside. A stem guide device is also pivotally attached to the top flange unit, so that a stem guide unit can be pivotally moved downwardly into place over the top flange unit opening, after a stem member is inserted into the vessel. Following coke removal from the drum, the stem member is withdrawn, the stem guide unit is pivotally moved upwardly, and the head cover unit is moved downwardly to cover the coking drum flanged unit. The invention also discloses method steps for operating the head cover and stem guide devices of the assembly.

Abstract: The heating flues in an oven are equipped with refractory components to control the feed and mixture of combustion air and gas into each heating flue. In one embodiment, the refractory component forms a plurality of passageways through which air and gas flow into mixture. Initially, the gas is mixed with small amounts of air to obtain substoichiometric combustion in the refractory component. Additional combustion air is supplied to the resulting partially combusted gases and unburned gas to complete the combustion of air and gas in the heating flue. This arrangement serves to optimize the flame control and the heat discharge over the height of the heating flue. In a second embodiment, the refractory component forms a plurality of passageways through which combustion air is supplied to the gas along the passageway outlets which are located at preselected positions along the length of the heating flue.

Abstract: A sole flue nonrecovery coking oven battery includes a plurality of elongated coking ovens constructed in side-by-side relation with common sidewalls downcomers connecting the ovens through the sidewalls to the sole flues, uptakes connecting the sole flues through the sidewalls to an elongated tunnel extending transversely of the battery and a single stack connected to the elongated tunnel applying a draft to all ovens in the battery through the downcomers, sole flues and uptakes, and an improved draft control system includes an adjustable draft regulating valve for controlling the flow of gas from the uptakes beneath each oven to the common tunnel. An adjustable damper type stack draft valve is also provided for opening and closing the stack to vary the draft applied to the stack to the battery.

Abstract: A gas jumper arrangement for a coke oven is composed of adjacently arranged coke oven chambers each having a gas opening with rims at the top portion thereof. The gas jumper arrangement overlaps gas openings of two adjacent coke oven chambers by one lid chamber each. The two lid chambers are connected in a duct-like manner by a gas jumper pipe and lids covering the gas openings during filling of a coke oven chamber are displaceable from an opened position into a closed position and settable into a rotational movement within the lid chambers by an actuation device. In order to ensure the tightness of the gas openings at the rims thereof even at larger pressure fluctuations and to enable the introduction of inert gas into the gas jumper arrangment, both the lid and the rim of each gas opening includes valve-face type sealing surfaces that mate with each other when pressed against each other in the closed position of the lid. A feed line for supplying an inert gas runs into the gas jumper arrangement.

Abstract: The method of reducing a nitrogen oxides content of a flue gas generated on firing of a rich gas or combination coke oven having a plurality of heating walls forming dual heating flues, in which a single stage or multistage combustion takes place, and also having a plurality of regenerators for recovery of flue gas heat and preheating of an underfiring medium, includes the steps of mixing one portion of the flue gas drawn from one flue of the dual heating flues with the underfiring medium, gas and/or air, prior to or on admission to the other flue of the dual heating flues, or a regenerator connected with it, and circulating another portion of the flue gas additionally inside the dual heating flues.