DE102019206628B4 - Coke oven device for producing coke and method for operating the coke oven device and use - Google Patents

Abstract

Coke oven device (10) for producing coke by coking coal or coal mixtures at least with mixed gas heating and optionally also with temporary coke oven gas heating, wherein the coke oven device is designed for minimizing nitrogen oxide emissions through internal thermal energy compensation by means of gases from the steelworks and gases from the coke oven (G1, G4, G5), with a plurality of twin heating flues (13), each with a gas-flamed heating channel (11) and a downward-flowing heating channel (12) carrying exhaust gas, wherein the heating channels (11, 12) are each separated from one another in pairs by a partition wall (14) and sealed off from a respective furnace chamber (10.2) by two opposing rotor walls (15), wherein the paired heating channels (11, 12) are fluidically connected by means of at least one upper coupling passage (14.2) and also by means of at least one lower coupling passage (14.2) each for internal exhaust gas recirculation are coupled to one another on at least one circular flow path, wherein in the lower region on the floor (5.4) of the respective twin heating flue (13) at least one inlet from the following group is provided: coke oven gas inlet (18), combustion air inlet (16), mixed gas inlet (17); characterized in that at the respective base (5.4) the ratio (y1:y2) of the distance (y1) between the facing edges of the combustion air inlet (16) and the mixed gas inlet (17) to the distance (y2) of the inner edges of the partition walls (14) of a respective heating channel (11, 12) is at least 10%, wherein the distance (y1) between the facing edges of the combustion air inlet (16) and the mixed gas inlet (17) is at least 50mm, wherein at least one of the combustion air and mixed gas inlets (16, 17) is arranged eccentrically at an x-distance greater than a factor of 0.7 of the absolute x-extension of the heating channel between opposite rotor walls (15), and wherein the combustion air inlet (16) is arranged further inside closer to the opposite rotor wall (15) than the mixed gas inlet (17), or vice versa.

Description

TECHNICAL AREA

The invention relates to a device and a method for producing coke with minimized NO _x emissions and corresponding uses. In particular, the invention relates to a device and a method according to the preamble of the respective independent claim.

BACKGROUND

The demand for coke ovens remains high worldwide and is expected to remain so in the future, as described in the following publication: K. WESSIEPE et al.: Optimization of Combustion and Reduction of NOx-Formation at Coke Chambers.... COKE MAKING INTERNATIONAL; 9, 2; 42-53 ; VERLAG STAHLEISEN MBH; 1997. Even today, despite increasingly strict environmental criteria, several hundred new coke ovens are built and put into operation every year. The number of new coke ovens built each year is estimated to be well over 1,000 in Asia alone. Nevertheless, it is now well known not only among engineers but also within society that energy generation using coke ovens is not particularly environmentally friendly. The construction of new coke ovens, or the operation of existing coke ovens, is therefore subject to increasingly strict requirements from many sides with regard to minimizing emissions, particularly with regard to nitrogen oxides (NO _x ). In this context, numerous efforts are being made to improve the efficiency of coking. The planning and construction of coke ovens must be carried out over a long time horizon. Particularly with regard to the desired long operating period or service life of a coke oven, it is important to know which environmental improvements can be realized in coke ovens in the coming years. However, a targeted pursuit of individual optimization measures is not trivial in view of the process-technical and structural complexity of coke ovens; rather, individual optimization measures must be put into perspective and balanced against each other in an overall concept with numerous interdependencies.

In recent years, there has been increasing communication at specialist conferences and in specialist journals that local environmental authorities in the respective countries and customers are already making much stricter demands on reducing environmental pollution caused by flue gas emissions or are expected to do so in the near future. Thermal NO _x formation in the vertical flue gas-carrying heating flues of coke ovens has proven to be one of the main causes of these flue gas emissions.

The emission limit value that is permissible in 2018 or still tolerated in existing plants is 500 mg/Nm ³ , corresponding to approx. 250 ppm at 5% oxygen 02. However, this limit has been in force for many years and may be further reduced in many countries in the near future. There is therefore interest in significantly undercutting this limit value by means of technical measures in the near future.

Nitrogen oxides are released in particular by the flue gas generated during the combustion of coke oven gas, particularly from a nozzle stone temperature (i.e. a temperature in the exhaust gas-carrying heating channel at the bottom) of around 1,250°C; this is referred to as thermal NO _x formation. Thermal NO _x formation is exponentially promoted or fueled further as temperatures continue to rise, so that the emission of nitrogen oxides is strongly determined by the thermal operating conditions of the coke oven under the respective load condition. It is therefore also well known that NO _x emissions can be influenced, particularly in the vertical, flue gas-carrying heating flues of the coke oven, by setting or regulating a certain temperature regime. A furnace operator therefore endeavours, or is forced by environmental regulations, to keep the temperature in the exhaust gas-carrying heating channel as low as possible, and in particular not to allow it to rise above 1,250°C. Nevertheless, significantly higher process temperatures in the range of 1,250 to 1,320°C have become established in plant practice worldwide as a compromise for not only ecological but also economical plant operation.

A plant operation optimized with regard to NO _x emissions must therefore be coordinated with a reduced (relatively low) temperature level in the heating train. However, this is associated with a reduction in coking performance and thus inevitably with a loss of coke production. Example: Instead of 100 furnaces, only about 95 to 98 furnaces need to be built at a higher permissible operating temperature. corresponding to an equipment saving of 2 to 5 percent (lower investment volume, up to 5% less plant costs, e.g. in relation to an investment volume of 100 to 800 million euros).

Due to these uneconomical performance losses, attempts are made only very reluctantly to maintain a reduced temperature level during coking or to avoid local temperature peaks in the heating flues in order to reduce NO _x emissions. Rather, as long as it remains legally permissible, it is accepted that NO _x emissions remain disadvantageously high. However, the furnace operator knows that if it were possible to keep the heat energy input constantly high at a comparatively moderate, reduced temperature, this would have a positive effect in terms of the lowest possible NO _x emissions with a comparable output.

Coke ovens can be divided into vertical chamber ovens and horizontal chamber ovens, particularly with regard to the direction in which the coke is pressed out. In horizontal chamber ovens, coking takes place in batches: after coking, the coke is pressed out in a horizontal direction (batch operation). In contrast, in vertical chamber ovens, the coal is continuously fed in and removed in a vertical direction (continuous operation). The present invention relates in particular to horizontal chamber ovens.

Coke ovens are heated either by a mixed gas produced from blast furnace top and coke oven gas or by pure coke oven gas (coke oven gas heating usually takes place in less than 10% of the annual operating time). Due to the high proportions of hydrogen and carbon monoxide and the resulting high flame temperature, the flue gas produced by coke oven gas combustion in particular is contaminated with high NOx levels. This is also why many of the measures taken to date have primarily been aimed at reducing NOx emissions, especially when coke oven gas is heated. The following is a tabular overview of the element distribution (in vol.%) of the respective gas type, whereby this information is based on average values determined over several years, in particular by the owners of the intellectual property of the present invention: component Blast furnace gas Coke oven gas Mixed gas from blast furnace and coke oven gas hydrogen 0...6 50...60 4...10 oxygen 0...4 0...3 0...3 Nitrogen 35... 75 2...10 40... 55 Carbon monoxide CO 25...30 2...10 15...30 Carbon dioxide CO ₂ 10...25 0...5 10...20 methane <1 15...35 0...5 Higher hydrocarbons <1 0...5 0...2 Hydrogen sulphide <1 0...1 <1

Trace elements in all three types of gases: e.g. ammonia, noble gases;

Blast furnace gases are produced during iron ore smelting processes in blast furnaces and are also referred to as "low-calorific" gases because they typically have only low heat contents (lower calorific values between 2,700 and 3,800 kJ/Nm ³ ). Blast furnace gases are comparatively inexpensive. Coke oven gases are produced during the coking process in coke ovens and have high heat contents (lower calorific values between 15,900 and 19,500 KJ/Nm ³ ). They are therefore also referred to as "strong gases". Coke oven gases are comparatively expensive.

For economic reasons, both types of gas are usually used in practice in such a way that they are mixed in advance in a ratio of 87 to 97 vol.% blast furnace gas to 3 to 13% coke oven gas and fed to the coke ovens for combustion. This mixed gas is usually used as heating gas in the coke ovens for more than 90% of the year. Other types of gas that are occasionally mixed in as alternative components to the starting gases (blast furnace gas, coke oven gas) (the resulting gas mixture is usually referred to as "coke oven mixed gas") are known under the term "converter gas" or "generator gas". "Converter gases" mostly come from the steel-producing industry. "Generator gases" are generated in many industries, mostly in coal-processing processes. The existing The present invention relates primarily to the use of mixed gases in the narrower sense, i.e. mixed gas without a predefined proportion of “converter gas” or “generator gas”.

With reference to the table above, hydrogen is considered to be the component whose combustion is associated with the highest local flame temperature and thus with the highest thermal nitrogen oxide formation. Coke oven gas has a considerably higher hydrogen content than blast furnace gas. Therefore, coke oven gas heating causes particularly great difficulties in plant operation in terms of emission limits.

It is worth mentioning that there are also coking plants with so-called "strong gas furnaces" which cannot be connected to a blast furnace, particularly due to their isolated geographical location, and which (must) use the gas produced in the coke ovens themselves during coal pyrolysis for heating for 100% of their operating time. The gas is usually returned to the furnaces after appropriate removal of impurities or valuable materials in a so-called by-product recovery plant. However, these furnaces are not designed for standard "mixed gas heating".

The furnace chambers of the coke ovens described above usually have a height in the range of 4 to 8.5 m (situation in 2018), whereby the preferred height of the furnace chambers or heating channels is also determined by the operating mode. The height influences the pressure difference that occurs in the heating channel. If a large pressure difference is required, a large height must be selected. It can be assumed that the temperature should be kept as constant as possible over the entire height of the furnace chamber, because only then should it be possible to set an efficient operating state without an excessive increase in NO _x emissions. The temperature gradient should be as much smaller as possible than 40 K or 40 ° C, especially when the temperature in the furnace chamber is in the range of 1,000 to 1,100 ° C. Such a small temperature gradient also promotes optimal coke quality. A maximum temperature significantly above the average temperature would promote thermal NO _x formation. A coke oven can be operated at a particularly optimal compromise between high output and low NO _x emissions if the temperature distribution is very homogeneous and if the temperature in the entire oven chamber remains just below the temperature at which thermal NO _x formation occurs or is exponentially increased.

Design variations in coke oven construction involve a great deal of effort. The effects of individual optimization measures must be predictable as cost-effectively as possible before the measures can be implemented in the oven construction. The simulation of operating conditions is a useful tool for better assessing the effects of individual optimization measures. However, a coke oven is a comparatively complex system, so that even purely computer-aided simulations involve a corresponding amount of effort. For example, a new design with a new way of guiding gas can mean a calculation effort of several weeks per calculation (even with the technological possibilities in 2018), so that even purely electronic/computer-aided simulations can result in a work effort of several years (e.g. with over 100 required variations). Not only does testing of new measures on a technical scale on the completed coke oven therefore have to be carried out under limited options, but even a simple design measure must first be checked under numerous aspects for cost reasons alone before this measure can be examined in more detail using simulations. This means that constructive variations on existing furnace designs are only suggested, tested and experimentally verified in a very moderate, conservative manner.

Measures that have been tested directly on the coke oven or on its structural design, and which are also intended to be effective in performance-optimized operating modes, are usually the internal pressure difference-driven or temperature and density-driven flue gas recirculation from the downward flow to the upward flow (internal circulation of a partial volume flow of the flue gas, so-called circular flow), and/or the staging of the combustion air, i.e. the introduction of combustion gas from partition walls or binder walls at different heights into the heating flues. The staging of the combustion air takes place in particular with regard to the following criteria: the maximum gas collection chamber temperature in the adjacent furnace chamber above the coal charge must/should be less than 820°C, for example; the ceiling surface temperature must be less than or equal to 65°C, for example; The temperature difference inside the furnace chamber wall must be less than or equal to 40K, in particular between the height positions 500mm above the furnace base/burner level and 500mm below the upper edge of the furnace chamber.

A circular flow (partly at only one end of the heating channel or completely in a circle) is usually implemented in so-called twin heating flues. Heating flues or heating channels arranged next to each other in pairs, especially in a vertical orientation, are coupled to each other by returning the gas from the flame-exposed heating channel to the non-flamed heating channel, either only at an upper/lower reversal point, or both at the top and bottom. In a horizontal chamber furnace, around 24 to 48 heating channels can be provided in series next to each other in the direction of expulsion, i.e. around 12 to 24 twin pairs. An optionally realizable circular flow can develop autonomously due to the pressure differences, i.e. solely due to temperature and density differences in the two respective twin heating flues, i.e. without additional active fluid control or support. In other words: constructive design variations are also limited by the sensitive (thermal) equilibrium, which must be achieved by means of pressure differences.

The optimization of circular flow control, particularly for the purpose of homogeneous heat distribution, began on an industrial scale in the 1920s. Since the 1970s, the influences of circular flow control on NOx emissions have also been investigated in more detail/systematically.

In paired heating channels (twin heating trains), the average nozzle stone temperature must be controlled or limited and must be kept at a moderate level (e.g. with a nozzle stone temperature of 1240 to 1300°C) by lowering the local flame temperature (for strong gas heating above 2000°C, for mixed gas heating below 2000°C). Effect: Control of NOx emissions. The flame temperature for mixed gas heating is, for example, in a range of 1,500 to 1,700°C, in particular around 1,600°C.

For example, the following arrangement (height position) of a lower passage between paired heating channels can be mentioned: between 0 mm (i.e. directly at the level of the burner level) to 300 mm above the burner level. The cross-sectional area of the passage is usually specified by a layer height (or width of the layer) of approx. 110 mm to 150 mm. If necessary, the lower passage can be closed in the arrangement on the floor using a roller, which can be rolled in front of the passage on the burner level. The passage is advantageously realized using a recess in a wall layer (gap or missing stone). If a single passage is mentioned in this description, this can also mean a pair of passages which are arranged in pairs at the same height position.

The burner level is understood to be the height level at which the inlets are designed to enter the heating flue, and from which height level a height variation can be achieved within certain limits using extended inlet nozzles, in particular up to 1,000 mm above the burner level. This can be distinguished from furnace types which are referred to as staged gas furnaces, and in which at least one inlet is only provided at a height significantly above 1,000 mm above the burner level.

The height position of a lower passage or a pair of lower passages can also be arranged up to a height of 1,000 mm above the burner level.

The height position of a lower passage or a pair of lower passages can also be arranged below the burner level, in particular up to 500 mm below the burner level.

A partial volume flow of the flue gas, which is usually led back into the flame-exposed heating channel, amounts to 30 to 45% of the total flue gas volume generated in the upward-flowing heating channel in the case of strong gas heating. An example of this arrangement of twin heating flues with circular flow is the so-called Combiflame heating system, which has been established since the end of the 1980s. This involves a combination of air staging and circular flow. Previously, up until the mid-1980s, there was either only air staging (Otto system) or only circular flow (Koppers system).

As previously indicated, combustion can also be staged by directing gas or air into the respective heating flue via at least one staged air duct at at least one height position above the burner level (floor), or by discharging the corresponding exhaust gas. Staged combustion can be combined with circular flow control.

If we specifically look at the measures directly on the coke oven, i.e. measures to optimize the thermal technology, in particular through an optimized way of guiding the media, the structural design of the coke oven and the associated stability of the coke oven are of great relevance, in particular the structural design of the individual walls of each oven chamber and the respective heating pass (runner walls, partition walls). Small measures to the structural design can have a major effect on the temperature balance and the coking process. However, each measure may also have very disadvantageous side effects that should be avoided, e.g. on the statics of the heating walls, on the flow resistance, or the flow speeds and temperature profiles that ultimately arise. It is therefore to be expected that changes to the structure described in more detail below can only be made within a narrow tolerance range. In particular, the specialist is also faced with the task of not risking any weakening of the heating wall assembly through new measures. This is because high lateral forces can act on each wall depending on the operating state. For example, after about 75% of the cooking time, a high lateral internal pressure (driving pressure of the coal charge) is created, particularly on runner walls, with a maximum pressure at a height of about 1 m above the burner level, which driving pressure can even cause joints in the masonry of the partition wall to the furnace chamber to widen, possibly also with the effect of undesirable bypass flows (in connection with coke oven gas transfers and the associated CO formation) between individual heating flues and (neighboring) furnace chambers. The balance of the gas mixture is also disturbed as a result; in particular, only an insufficient amount of air is available for additional gas quantities to be burned in the heating channel. Different filling times, for example staggered by several hours, also lead to different lateral forces in the respective walls of the neighboring furnace chambers. The stability of the furnace is therefore also a high priority for the necessary measures to reduce emissions described above. High stability is usually achieved by a tongue-and-groove arrangement of the bricks. This very flexible design is also preferred in terms of tightness to avoid bypass flows and pre-combustion. The specialist has no reason to deviate from a design that is as flexible as possible and at the same time as robust as possible without special reason.

In a battery with several furnace chambers, e.g. at least 15 to a maximum of 90 furnace chambers, the furnace chambers are separated from gas-carrying heating channels by rotor walls, in particular on a relatively narrower front side of the respective channel, in particular by two opposing rotor walls extending along the entire respective furnace chamber. The individual heating channels are separated from one another by so-called binder walls (partition walls), which extend in particular orthogonally to the two rotor walls between the rotor walls. A binder wall separates two channels from one another, or two binder walls separate a pair of twin heating flues from another adjacent pair of twin heating flues. Each heating channel is therefore separated by two rotor wall sections and two binder walls. In the direction of extrusion (depth y), each heating channel is, for example, approx. 400 to 550 mm long or deep (center to center). A stretcher wall thickness is, for example, in the range of 80 to 120 mm. A truss wall thickness is, for example, in the range of 120 to 150 mm.

The term "binder wall" has become established in common parlance. In this description, this term is used synonymously with the term "partition wall", in particular to clarify that a runner wall and a binder wall/partition wall can be made using the same construction method, namely by lining up bricks on their narrow sides. The "runner wall" of a horizontal chamber kiln can also be described as a longitudinal wall arranged lengthways in the direction of expulsion, and the "binder wall" can also be described as a transverse (partition) wall arranged transversely to the direction of expulsion.

Combustion air openings and mixed gas openings are provided on the underside of each heating channel, the function of which can be selected or adjusted depending on the type of heating (mixed gas or coconut oven gas heating). A coke oven gas opening opens into the heating channel on the underside. In a circular flow system, a pair of heating channels is coupled to one another via exhaust gas recirculation openings arranged on the underside of the furnace chambers, so that a twin heating flue with circular flow is formed. The volume flow through the exhaust gas recirculation openings can be optionally regulated, in particular by means of an adjusting roller arranged on the floor in the burner plane and movable there. Staged gas channels are provided in the binder walls, which introduce combustion air (stage gas) into the furnace chamber at one or more height positions (air stage or binder wall opening). A typical ratio of the volume flows introduced into the furnace chamber can be mentioned as follows: approx. 30% through the bottom-side combustion air inlet, approx. 30% through the bottom-side mixed gas inlet, and approx. 40% through at least one stage gas inlet (binder wall opening). This ratio can also be set analogously for the discharge of gases from the furnace chamber, depending on the performance requirements.

Above the exhaust gas turning point (recirculation passage), a bypass flow in the form of a heating differential can be formed to adjust coking parameters. The bypass flow can be sealed off from the heating flues by a wall or ceiling, in particular a horizontal one, in which openings are provided that can be covered, for example, by means of slide blocks or can be adjusted in terms of their cross-section.

The aforementioned publication by K. WESSIEPE also considers in particular measures for furnaces with twin heating flues, whereby in the 1990s it was already worked out that the so-called circular flow arrangement can provide advantages in terms of the lowest possible NO _x concentration.

The patent documents can be considered as state of the art DE 34 43 976 C2 and DE 38 12 558 C2 Examples include those in which the aspect of an optimal circulating flow rate and a sensible height position for the gradual introduction of combustion air is discussed, particularly using the example of the Koppers circulating flow furnace. It is also mentioned that a return of flue gas at a height position in the area of the heating flue sole enables a reduction in the temperature in the respective heating flue, with the effect of a reduction in NO _x emissions.

In the disclosure document CN 107 033 926 A from August 2017, an arrangement with twin heating flues with stepped introduction of combustion air and with circular flow openings is described, which are arranged on both sides of the stepped air duct.

Experiments have also already been carried out with a certain type of gas guide components or packing elements in order to be able to influence the heat distribution in the coke oven. For example, in the patent specification DE 39 16 728 C1 Heating rooms (heating flues) are fitted with fittings in the form of permeable honeycomb bodies or honeycomb grids or spherical fill, whereby certain types of flue gas routing are also said to be advantageous in certain sections. The aim is to improve the flow conditions in the heating rooms, and it is also proposed to supply combustion air at different heights.

Experiments have also been carried out with certain coatings to effectively dissipate or reflect heat energy from internal surfaces.

The measures described above directly on or in the coke oven or heating train can be referred to here as primary measures, i.e. measures that are intended to counteract the primary NO _x formation mechanisms in the heating train (in particular internal flue gas recirculation or circulating flow, staging of the combustion air). With all of the measures described above, it must be noted that the ovens described here are usually operated with self-ignition (in particular at over 800°C), so that the corresponding measure for cooling or lowering the gas temperature can only be carried out under narrow boundary conditions or only in a narrow temperature range, in particular to prevent combustion from extinguishing.

Furthermore, so-called secondary measures have already been tested, which can be carried out downstream of the coke oven in downstream plant components, for example by using selective catalysts in the stack (SCR or DeNO _x ) to reduce the NO _x content in the flue gas before it is evacuated into the atmosphere, or the external recirculation of already evacuated flue gas from the stack back into the coke oven. Regardless of how effective these downstream measures are, in many cases they fail due to extremely high costs (up to 50% of the total investment for the entire coke oven) or the additional maintenance effort. Although these measures are effective, in many cases they are too expensive.

Furthermore, the patent application EN 40 06 217 A1 can be mentioned, in which the combination of several measures is described, including both measures on regenerators in the central section of the furnace and measures for external flue gas circulation, with the aim of homogeneous heating conditions and low NO _x emissions even in high furnace chambers.

Last but not least, chemical, reactive measures have also been considered, such as introducing CH ₄ gas or increasing the humidity by injecting water or feeding in ammonia. However, injecting water or steam is not possible at any point in the furnace chamber, but only centrally at a medium height; this measure also has adverse effects on the (silicate) materials used. Increasing the regenerative preheating temperature of gas and air is a measure that is now considered to be exhausted and uneconomical.

In 2018, it still seemed unthinkable that the requirements described above could be met, especially with the internal, primary measures described above, either alone or cumulatively. A reduction in NO _x emissions by a considerable factor, in particular by a factor in the range of 2 to 5, is therefore unlikely to be feasible, especially not to a level below 200 mg/Nm ³ or below 100 mg/Nm ³ , at least not with reasonable effort, i.e. not in an economical way.

Despite the concerns expressed above, the present invention is aimed at optimizing coke ovens by taking measures directly on the coke oven or on its structural design, in particular by taking measures on the established heating system with heating flues with at least one recirculation opening, in particular with circular flow, in particular to possibly create the option of being able to operate the coke oven in a performance-optimized mode without any downstream system components (only internal, primary measures to reduce NO _x ). There may be great potential for improvement here, with great advantages for the oven operators as well, and thus also with good chances of the technical concept being implemented on the market.

Previous measures have primarily been aimed at reducing the disproportionately high NO formation when heating with coke oven gas, i.e. when heating with pure coke oven gas (not with mixed gas) - these measures may tend to be less effective when heating with mixed gas. Many of these measures may even have a negative effect on NO _x formation when heating with mixed gas.

However, coke oven plants are usually operated primarily by mixed gas heating; it is estimated that mixed gas heating is the dominant heating method in more than 90% of applications or in more than 90% of the operating time (coke oven gas heating, for example, only in emergency situations or during maintenance work). In theory, therefore, the measures aimed at heating the coke oven gas would have to be around 10 times more effective than a measure for mixed gas heating in order to achieve the same overall NO _x savings over the life of the oven. Many measures aimed at heating the coke oven gas also have the disadvantage of increased pressure losses in the oven, which means that a negative pressure source with increased output must be planned in the plant design.

Even more recent measures to reduce disproportionately high NO formation have so far primarily affected coke oven gas heating. There is therefore interest in NOx-related optimization of existing heating methods and of the heating flue design, especially for the mixed gas heating method, which has so far received less attention in many cases. In this case, the known primary _NOx reduction technologies can of course be taken into account first.

From the EN 10 2017 216 437 A1 A coke oven device for producing coke by coking coal or coal mixtures has become known, wherein the coke oven device is designed to minimize nitrogen oxide emissions through internal thermal energy compensation by means of coke oven gases by measures internal to the coke oven device, with a plurality of twin heating flues, each with a gas-flamed heating channel and a downward-flowing heating channel carrying exhaust gas, which heating channels are each separated from one another in pairs by a partition wall and sealed off from a respective furnace chamber by two opposing rotor walls, wherein the paired heating channels are fluidically coupled to one another by means of an upper coupling passage and optionally also by means of a lower coupling passage each for internal exhaust gas recirculation on an outer circular flow path, wherein in the lower area on the floor of the respective twin heating flue at least one inlet from the following group is provided: coke oven gas inlet, combustion air inlet, mixed gas inlet, wherein at least one of the inlets in relation to the width of the heating channel is arranged more eccentrically than at least one of the passages and defines a flow path arranged more eccentrically than the exhaust gas recirculation.

Although useful measures to reduce NO _x emissions have already been described here, there is still room for improvement.

DESCRIPTION OF THE INVENTION

The object of the invention is to provide a coke oven device and a method for operating the coke oven device, with which NO _x emissions can be kept low, especially for mixed gas heating, or can be minimized in existing or new systems even when operating at full load, whereby the coke oven device should enable an advantageously low NO _x emission level, preferably without downstream system components. In particular, the object is to provide a coke oven device and a method for operating the coke oven device, with which NO _x emissions can be reduced, especially for mixed gas heating, by measures internally in the heating flues, in particular exclusively by internal primary measures. Preferably, such measures should only require minimally greater pressure losses, especially for mixed gas heating; in particular, any increases in pressure loss in the oven required by these measures should be in a non-critical range of less than 50Pa. Ultimately, such measures specifically for mixed gas heating should be compatible with any measures for coke oven gas heating, or at least not have a particularly negative impact on the mode of operation of coke oven gas heating, even if coke oven gas heating only takes place for a small proportion of the annual operating time. This would enable a comparatively flexible mode of operation, i.e. a very variable furnace for a wide range of tasks.

This object is achieved according to the invention by a coke oven device for producing coke by coking coal or coal mixtures at least with mixed gas heating and optionally also with temporary coke oven gas heating, wherein the coke oven device is set up for minimizing nitrogen oxide emissions through internal thermal energy compensation by means of steelworks' own gases (in particular blast furnace-original gases) and coke oven-own gases G1, G4, G5 by measures internal to the coke oven device, with a plurality of twin heating flues, each with a gas-flamed heating channel and a downward-flowing heating channel carrying exhaust gas, which heating channels are each separated from one another in pairs by a partition wall (also referred to as a binder wall) and sealed off from a respective furnace chamber by two opposing rotor walls, wherein the paired heating channels are fluidically coupled to one another by means of at least one upper coupling passage and also by means of at least one lower coupling passage each for internal exhaust gas recirculation on at least one circular flow path, wherein in the lower At least one inlet from the following group is provided in the area at the bottom of each twin heating flue: coke oven gas inlet, combustion air inlet, mixed gas inlet; wherein at the respective bottom the ratio y1:y2 of the distance y1 between the facing edges of the combustion air inlet and the mixed gas inlet to the distance y2 of the inner edges (inner surfaces) of the dividing walls of a respective heating channel is at least 10%, wherein the distance y1 between the facing edges of the combustion air inlet and the mixed gas inlet is at least 50mm, wherein at least one of the combustion air and mixed gas inlets is arranged eccentrically at an x-distance greater than a factor of 0.7 of the absolute x-extension of the heating channel between opposite rotor walls. This enables a reduction in NO _x emissions by means of internal thermal measures.

According to the invention, the combustion air inlet and the mixed gas inlet are arranged relatively far apart from each other in the y-direction, with a relative minimum distance being defined with respect to the entire y-extension of the respective heating channel. According to the invention, an absolute minimum distance is also defined (y1min = 50mm). This enables an advantageous influence on the temperature and flow profile. The minimum distance y1 is, for example, in the range from 60 to 220mm. The distance y2 between opposing partition walls is, for example, in the range from 250 to 400mm.

The absolute position of the mixed gas inlet can be defined, for example, by a minimum distance to the rotor walls in the y-direction and/or by a minimum distance to the partition walls, in particular, e.g. > 10mm between the outer edge of the mixed gas opening and the inner edge of the partition wall (binder wall). The distance between the mixed gas opening and the coke oven gas nozzle (relative position) can be at least 100mm in the x-direction.

According to the invention, it has been shown that an economically favorable process temperature above 1,250°C and thus a high plant performance can be ensured with good effect while simultaneously complying with the strict limit values described above based on geometric measures at the bottom of the heating flues. In this case, any increase in pressure losses can also be compensated for in a comparatively moderate manner. The relative or absolute positioning of the mixed gas inlet according to the invention also makes it possible to achieve the desired temperature distribution in a particularly effective manner.

The combustion of mixed gases, which was previously considered less critical due to the low hydrogen content, has not yet been the main subject of nitrogen oxide-reducing developments in vertical heating channel designs in composite coke ovens. However, operation with mixed gas heating often affects a considerable proportion of the absolute operating time of a furnace. According to the invention, particularly advantageous NO _x -reducing effects can be achieved especially with mixed gas heating.

An increase in the absolute distance between the exit positions for the combustion media "soil air" and "mixed gas", particularly in connection with a relative minimum distance with respect to the entire extension of the heating channel in the y-direction, enables the furnace to be designed independently of the specific volumes or performance ranges of the furnace.

As far as the respective function of the individual inlets is concerned, this can also be described in terms of different operating modes: For a composite furnace connected to a steelworks, two openings or inlets are provided on the floor of the heating flue when heated with mixed gas, namely an inlet for mixed gas and an inlet for (combustion) air. For a composite furnace heated with coke oven gas, the mixed gas channels are also supplied with air. For a furnace designed exclusively for coke oven gas heating (so-called strong gas furnace), only one air inlet is required (no mixed gas inlet). The latter design is to be understood as a special case.

In the case of pure mixed gas heating, the arrangement of the coke oven gas inlet is comparatively unimportant; the relative arrangement of the coke oven gas inlet can therefore be varied more or less depending on the application, whether in the longitudinal and/or transverse direction. A sensible compromise then also depends on the expected operating times for the respective type of heating. Using the absolute and relative arrangement of the inlets for combustion air and mixed gas according to the invention, a good compromise with minimized NO _x emissions can be provided for a large proportion of the absolute operating time for various different designs of ovens.

A comparatively large distance between the two inlets for combustion air and mixed gas relative to the coke oven gas inlet can be assumed to be expedient or even optimal; however, it has been shown that the effects according to the invention can also be achieved largely independently of the relative arrangement of the coke oven gas inlet. This also provides further design or process-related variables (or degrees of freedom) for adapting a furnace to specific applications within the scope of the present invention.

For example, a distance y1 in the range of 100 to 300 mm is provided. For example, a ratio y1/y2 in the range between 30 and 60% (or 0.3 and 0.6) is selected. The ratio y1/y2 can also be significantly larger, for example up to 90% (or 0.9). Preferably, the ratio y1/y2 is in a medium range below 0.5. This has proven to be advantageous, particularly with regard to temperature distribution in the vertical direction.

It has been shown that a variation of the distance y1 can be used as an effective measure for NO _x optimization. In particular, a positive effect of the inventive size or the inventive range of the distance y1 on the formation of NO _x could be demonstrated in a systematic manner. Up to now, the furnace manufacturers have refrained from varying the distance y1. In particular, this distance was not identified as a measure for NO _x savings. There was therefore no reason for such a purposeful variation of the distance y1, especially since a distance variation at first glance does not allow/allowed any systematic conclusions about the NO _x emissions.

The x-position of the combustion air and mixed gas inlets can be defined in particular in relation to their center points. In particular, at least one of the combustion air and mixed gas inlets, in particular its center point, can be arranged eccentrically at an x-distance greater than a factor of 0.8 of the absolute x-extension of the heating channel between opposing rotor walls. This degree of eccentricity in the x-direction can also ensure advantageous primary mixing of the gases before combustion.

In a broader sense, steelworks gases are understood to mean gases associated with steel production, in particular so-called converter gas. Strictly speaking, converter gas is not associated with pig iron production in the blast furnace, but rather with the underlying process chain of actual steel production in the steelworks. The term "steelworks gases" can also include hydrocarbon components or natural gas, particularly as components of mixtures.

A comparatively small ratio y1:y2, especially below 15%, can be advantageous, especially for larger systems.

The arrangement according to the invention also enables, for example, comparatively moderate flame temperatures at a comparatively high nozzle stone temperature, in particular a flame temperature with mixed gas heating of a maximum of about 1,600°C at a nozzle stone temperature of at least 1,300°C or 1,320°C.

It has been shown that the arrangement according to the invention can be implemented both with a structural design of the twin heating flues in the form of a "back-to-back" heating system (vertically identical flow direction in adjacent twin heating flues) and with a structural design of the twin heating flues in the form of a forward-directed flow (vertically opposite flow direction in adjacent heating flues). In the case of "back-to-back" heating, either a single lower recirculation passage or several recirculation passages, in particular in pairs, can be provided. In the case of forward-directed flow, lower recirculation passages are preferably provided in pairs.

In the "forward burning" operating mode, for example, the heating flues with odd numbers #1, #3, #5, #7, #9,... (n+2) burn, or after the heating is switched over, the even heating flues with numbers #2, #4, #6, #8, .... (n+2) burn. In particular, at least one recirculation opening is provided in each binder wall. Preferably, at least two lower recirculation openings are provided in this type of furnace, which enclose or border or surround the stepped air channel in the binder wall. It has been shown that the flue gas flowing through the recirculation openings can at least partially form a combustion-inert intermediate layer in the horizontal direction to at least one of the admitted media (gas and/or air). It has been shown that this can delay combustion in the vertical direction, which can have a positive effect on the temperature distribution. For example, there are at least two recirculation openings per layer in each binder wall. A first pair of recirculation openings is preferably located in one of the lowest five truss wall layers. For stability reasons in particular, further openings are only provided in the next layer above (e.g. vertical layer number 3), which can be arranged in particular parallel (symmetrical) to layer number 1.

In the "back-to-back" operating mode, in particular the heating flues number #1, #4, #5, #8, #9, ... (starting with 1, where n+3/n+1) burn, or after the heating changeover the heating flues number #2, #3, #6, #7, #10, #11, ... (starting with 2, where n+1/n+3) burn. It has been shown that by means of the flue gas flowing back through the recirculation openings, a combustion-inert intermediate layer can be formed to at least one of the admitted media (gas and/or air). In particular, at least one recirculation opening is provided in every second binder wall. For example, a (in particular comparatively large) individual recirculation opening is provided in the middle of the binder wall. For example, the stepped air duct and recirculation opening(s) are only located together in the corresponding binder wall. Preferably, at least one further recirculation opening is provided in at least one of the wall layers located above.

The respective arrangement of the at least one recirculation passage can be chosen largely freely. Optionally, its arrangement can be defined relative to the arrangement of the other inlets. Optionally, an x-coordinate and/or a z-coordinate can be specified for the arrangement of the center of the recirculation passage. For example, the (lowest) recirculation passage or the (lowest) recirculation passages are arranged at a height position less than 2 m above the floor. According to one variant, pairs of recirculation passages are provided for each height position, in particular in a symmetrical arrangement with respect to the x-extension of the heating flue. For example, one or two pairs of recirculation passages are arranged in height positions on the same x-coordinate as at least one of the air and mixed gas inlets.

It has been shown that it is advantageous to arrange at least one of the air and mixed gas inlets at a comparatively small x-distance to the closer rotor wall, in particular a maximum of 50 mm or even only a maximum of 20 mm or 10 mm.

It has also been shown that the air and mixed gas inlets can optionally be arranged completely overlapping in the x-direction, i.e. without an offset being realized, or without the geometrically smaller inlet protruding beyond the geometrically larger inlet in the x-direction. It has also been shown that the air and mixed gas inlets can optionally be arranged completely without overlapping in the x-direction, i.e. with such a large offset that an overlap in the x-direction cannot be detected.

In particular, only one of the types of inlets described here is provided for each heating flue, i.e. only one combustion air inlet and only one mixed gas inlet.

It has also been shown that the combustion air can preferably be supplied in stages, in particular for the purpose of two-stage combustion over the entire height of the respective heating flue. Corresponding recesses or inlets for staged air can be arranged in an individually optimized manner depending on the application.

According to one embodiment, the ratio y1:y2 is at least 25%. This also enables good distribution or mixing of the gases over the entire extent of the heating channel.

According to one embodiment, the distance y1 is at least 100mm, for example at least 150mm, for example 200 to 250mm. This allows the gas flow paths to be adjusted and regulated more individually.

According to one embodiment, the ratio y1:y2 is at least 35%, in particular a maximum of 50% or a maximum of 60% or a maximum of 70%. It has been shown that the distance y1 can be further increased or even maximized starting from 10% or 15% without this being accompanied by noticeable disadvantages with regard to NO _x emissions or with regard to other operating parameters of the furnace. This opens up further degrees of design freedom.

According to one embodiment, the distance y1 is at least 150 mm or at least 200 mm. This ensures an advantageous relative arrangement even in comparatively large-volume furnaces.

According to one embodiment, the distance y1 is a maximum of 350 mm or a maximum of 375 mm. It has been shown that distances y1 greater than 400 mm could be associated with disadvantages with regard to other process parameters of the furnace. According to the invention, it is recommended to limit the distance to an upper limit below 400 mm.

According to one embodiment, the distance y1 is in the range from 200mm to 300mm or in the range from 150mm to 250mm. These ranges or this distance spectrum have proven to be particularly advantageous in many tests. A more precise distance specification can be defined depending on the total extension of the furnace or the heating channels.

Preferably, the distance is the same in each heating flue of the coke oven device. An analogous construction or symmetrical design with regard to all heating flues also has thermal and structural advantages.

A comparatively large ratio y1:y2, especially over 25% or even over 35% or 40%, can be advantageous, especially for smaller systems.

According to one embodiment, the geometric centers of the inlets of the respective heating flue and of the at least one lower coupling passage, in particular one of several lower coupling passages that is further away from the combustion air and mixed gas inlet, define a triangular or square arrangement (polygonal arrangement), the surface area (A) of which in plan view is at least 50cm ² , in particular at least 200cm ² or at least 300cm ² or at least 500cm ² or at least 700cm ² or at least 900cm ² , in particular between 1,000cm ² and 1,350cm ² . This enables a good distribution of material and energy flows largely independent of the individual structural characteristics of the respective furnace. It has been shown that even from a surface area of 200cm ² particularly strong effects can be achieved. The effects can be further enhanced, particularly from 300cm ² or 500cm ² .

According to one embodiment, the triangular or square arrangement has a surface area (A) in plan view of a maximum of 2,000cm ² , in particular a maximum of 1,800cm ² or a maximum of 1,500cm ² or a maximum of 1,300cm ² or a maximum of 700cm ² , in particular between 1,000cm ² and 1,300cm ² . These upper limits can indicate an advantageous range that can also be implemented in a reasonable manner from a structural perspective. It has been shown that the surface area must not be chosen to be too large, in particular in order to be able to avoid potentially disadvantageous side effects depending on the furnace configuration. A surface area of less than 1,500cm ² can already benefit a particularly large number of furnace configurations, but the upper limit can also be greater than 1,500cm ² , in particular in the case of very large or high furnace chambers.

The preferred lower/upper limit can also depend on the height of the furnace chamber, for example, as explained in more detail in connection with the description of the figures. In particular, the lower limit can be increased by 100 or 200 cm ² for furnace chambers with a height of more than seven (7) meters.

A relative triangular or square arrangement, with corner points defined by geometric centers of the mixed gas and combustion air inlets and the (more distant) lower recirculation passage (relative position geometry relative to each other) also provides the advantage of the best possible use of the available (combustion) space, in particular in such a way that the mixing ratio of the gases can be advantageously adjusted. In particular, an advantageous distribution of the material and energy flows can be ensured with a comparatively large surface area. In particular, thanks to the widely distributed arrangement of the inlets on the available floor space, a particularly advantageous (in particular greatly delayed) combustion in the vertical direction can be ensured for the usual types of heating (mixed gas or coke oven gas heating).

In particular, the corner points of the triangular arrangement are defined by the geometric centers of the mixed gas and combustion air inlets and by the center of the (more distant) lower recirculation passage, i.e. offset inwards with respect to an exit plane from the corresponding partition wall.

According to one embodiment, the edges of the combustion air inlet and the mixed gas inlet facing the rotor walls are arranged at different distances x1, x2 from at least one of the two opposite rotor walls of the respective twin heating flue, in particular with a distance difference of at least 10 mm or at least 50 mm. The offset in the x-direction also enables additional differentiation with regard to temperature and flow distribution.

It has been shown that the distances x1, x2 to the two rotor walls can be set relatively freely. The respective openings/inlets can also be of different sizes in both the x and y directions and have a different geometry. The inlets can also be offset in the x direction while maintaining the same cross-section.

According to one embodiment, the cross-sectional area of the combustion air inlet and/or the mixed gas inlet at the respective bottom is at least 30cm ² or at least 50cm ² . This can also further promote a flattening of temperature peaks.

According to one embodiment, the cross-sectional area of the combustion air inlet and/or the mixed gas inlet is a maximum of 500cm ² or a maximum of 400cm ² . These comparatively large areas also promote a large-area heat input.

According to one embodiment, the respective inlet cross-sectional area is comparatively large, in particular by a factor of 2 to 3 larger than previously usual cross-sectional areas. In the prior art, only significantly smaller cross-sectional areas are described, for example in the range of approximately 50 to 100cm ² . For example, the aforementioned publication by K. WESSIEPE describes dimensions of 51mm × 144mm, i.e. only approximately 75cm ² .

In particular, a connecting opening for exhaust gas or flue gas flow reversal (passage) with a passage area of at least 500cm ² can be designed. This enables Last but not least, it also helps to keep undesirable increases in pressure loss in the heating duct within an acceptable and economically advantageous range, especially at less than 50 Pa. This also saves the need for an increased or additional negative pressure source. In other words: Raising the exhaust chimney and/or an additional fan is not necessary.

According to one embodiment, the cross-sectional geometry of the combustion air inlet and/or the mixed gas inlet is rectangular or elliptical or round. The geometry can also be optimized with regard to design specifications or stability aspects, for example. In particular, further optimization can also be carried out by means of adjustable outlet openings (inlets) for the gases, in particular by means of slide blocks.

Further measures can achieve further advantageous effects. In particular, further optimization can be achieved based on a variation of the position of the inlets with regard to an asymmetric arrangement (at least for soil air and mixed gas), e.g. by non-parallel arrangement on the ground in relation to the rotor wall.

It has been shown that by means of measures according to the invention, particularly with mixed gas heating, a reduction in NO _x formation or NO _x emissions by at least 15% can be achieved compared to the current state (state of the art). This percentage may not seem revolutionary at first glance, but it can justify economical operation, especially if economical operation was previously not possible due to emission specifications and restrictions to a certain maximum temperature.

According to one embodiment, the cross-sectional area of the combustion air inlet and/or the mixed gas inlet is adjustable in terms of geometry and/or size at the respective bottom, in particular by means of at least one movable slide block and/or by means of at least one replaceable/removable nozzle. This allows further optimizations to be implemented, in particular during operation (fine adjustment).

According to one embodiment, the at least one upper recirculation passage coupling the two respective heating channels of a respective twin heating train in the upper region is designed for the mutual transfer of gases, wherein the recirculation passage has a cross-sectional area of at least 250cm ² , in particular of a maximum of 1200cm ² or a maximum of 1000cm ² . This also allows optimization to be carried out in a comparatively flexible manner thanks to comparatively large passage openings.

According to one embodiment, the paired heating channels are fluidically coupled to one another by means of at least two lower coupling passages, wherein the combustion air inlet is arranged at least approximately in the same x-position as the corresponding lower coupling passage, in particular with the respective center point of the combustion air inlet and the corresponding passage in an arrangement on the same x-coordinate. This promotes a mixing of recirculation gas and combustion air in a particularly advantageous manner, in particular before combustion.

According to one embodiment, the combustion air inlet and the mixed gas inlet are arranged offset in the x-direction with respect to the opposite rotor wall. This variation can promote good mixing. Different geometries and/or cross-sectional areas can also be provided.

According to one embodiment, the ratio x1:y1 or x2:y1 of the distance x1, x2 of the combustion air inlet and/or the mixed gas inlet to the opposite rotor wall to the distance y1 is at least 90% and/or a maximum of 290%, in particular between 200% and 250%. In other words: the inlets remain comparatively far away from the center in the x-direction, at least one of the inlets. This allows the gas distribution to be further differentiated.

According to the invention, the combustion air inlet is arranged further inside, closer to the opposite rotor wall, than the mixed gas inlet (or vice versa), in particular with a distance difference of at least 10 mm or at least 50 mm, in particular in an at least approximately central area in the middle between the opposite rotor walls. Such an offset in the y-direction allows the flow paths to be further spread out.

According to one embodiment, the combustion air inlets and the mixed gas inlets of a twin heating flue are arranged relative to one another in such a way that a line connecting the inlets is a diagonal or extends at least approximately diagonally through the respective heating channel, in particular a straight diagonal through the centers of the inlets, in particular a diagonal at an angle in the range of 40° to 50° with respect to the horizontal x-direction, in particular a diagonal running through the corner points between the rotor and binder walls. This allows an advantageous local diversification of temperature and mass transport in the respective heating flue to be set. The diagonal design can also be characterized by an at least approximately aligned arrangement on a line between diagonally opposite corners.

ITEM1 The above-mentioned object is also achieved by a coke oven device for producing coke by coking coal at least with mixed gas heating, with nitrogen oxide emissions minimized by internal thermal energy compensation, with a plurality of twin heating flues with paired heating channels, which are each separated from one another in pairs by a partition wall and sealed off by two opposing rotor walls, wherein at least one inlet from the following group is provided at the bottom of the respective heating channel: coke oven gas inlet, combustion air inlet, mixed gas inlet; wherein the paired heating channels are fluidically coupled to one another by means of at least one upper coupling passage and also by means of at least two lower coupling passages, each for internal exhaust gas recirculation on at least one circular flow path, wherein at the respective bottom the ratio of the distance between the facing edges of the combustion air inlet and the mixed gas inlet to the distance between the inner edges of the partition walls is at least 10%, wherein the distance between the facing edges of the combustion air inlet and the mixed gas inlet is at least 50mm, wherein at least one of the combustion air and mixed gas inlets is arranged eccentrically at an x-distance greater than a factor of 0.7 of the absolute x-extension of the heating channel between opposite rotor walls; wherein the paired heating channels are fluidically coupled to one another by means of at least two lower coupling passages, wherein the combustion air inlet is arranged at least approximately in the same x-position as the corresponding lower coupling passage, in particular with the respective center point of the combustion air inlet and the corresponding passage in an arrangement on the same x-coordinate, in particular in combination with the features of a previously described coke oven device. This provides the aforementioned advantages, in particular with regard to primary mixing of recirculation gas and combustion air before combustion.

ITEM2 The aforementioned object is also achieved by a coke oven device for producing coke by coking coal at least with mixed gas heating and with nitrogen oxide emissions minimized by internal thermal energy compensation, with a plurality of twin heating flues with heating channels, which are each separated from one another in pairs by a partition wall and sealed off by two opposing rotor walls, wherein the paired heating channels are fluidically coupled to one another by means of at least one upper coupling passage and also by means of at least one lower coupling passage each for internal exhaust gas recirculation on at least one circular flow path, wherein in the lower region on the bottom of the respective heating channel at least one inlet from the following group is provided: coke oven gas inlet, combustion air inlet, mixed gas inlet; wherein at the respective bottom the ratio y1:y2 of the distance y1 between the facing edges of the combustion air inlet and the mixed gas inlet to the distance y2 of the inner edges of the dividing walls is at least 10%, wherein the distance y1 between the facing edges of the combustion air inlet and the mixed gas inlet is at least 50mm, wherein at least one of the combustion air and mixed gas inlets is arranged eccentrically at an x-distance greater than a factor of 0.7 of the absolute x-extension of the heating channel between opposite rotor walls; in particular the coke oven device described above; wherein furthermore the distance y1 is at least 100mm, in particular at least 150mm, wherein the combustion air inlet and the mixed gas inlet are arranged offset in the x-direction with respect to the opposite rotor wall. This provides numerous advantages mentioned above.

The above-mentioned object is also achieved according to the invention by a method for operating a coke oven device for producing coke by coking coal or coal mixtures with optimized, minimized nitrogen oxide emissions through internal thermal energy compensation by means of steelworks gases (blast furnace-original gases) and coke oven gases by measures internal to the coke oven device at least with mixed gas heating and optionally also with temporary coke oven gas heating, in particular for operating a previously described coke oven device, wherein in a respective twin heating pass of the coke oven device with a flamed heating channel and an exhaust gas-carrying an internal exhaust gas recirculation is set on at least one circular flow path around the dividing wall by means of at least one coupling passage through a dividing wall in the heating channel, wherein in the lower region at the bottom of the respective twin heating flue at least two gases from the following group are admitted: coke oven gas, combustion air, mixed gas, wherein the group of admitted gases comprises at least the two gases combustion air and mixed gas; wherein at the respective bottom the combustion air and the mixed gas are admitted on flow paths at a distance y1 from each other in the ratio y1:y2 of at least 10% to the distance y2 of the inner edges (inner surfaces) of the dividing walls of a respective heating channel, wherein the distance y1 of these two admitted flow paths is at least 50mm, wherein combustion air and/or mixed gas are admitted eccentrically at an x-distance greater than a factor of 0.7 of the absolute x-extension of the heating channel between opposite rotor walls and wherein combustion air is admitted through the combustion air inlet, which is arranged further inside closer to the opposite rotor wall than the mixed gas inlet or vice versa. This provides the aforementioned advantages.

According to one embodiment, the cross-sectional area of the combustion air inlet and/or the mixed gas inlet is adjusted in terms of geometry and/or size at the respective bottom, in particular by means of at least one slide block. This enables further optimization.

According to one embodiment, the flame temperature for mixed gas heating is a maximum of 1,700°C or a maximum of 1,600°C or a maximum of 1,500°C, in particular with a nozzle stone temperature of at least 1,300°C or at least 1,320°C. This can also create an advantageous framework with regard to operating parameters and output. In particular, the device can be operated either with regard to maximized output (no strict NO _x limits) or with regard to minimized NO _x emissions. In comparison to previously known devices, a higher output can be achieved with comparably high NO _x emissions.

According to one embodiment, the gas flows in the respective heating train are adjusted in such a way that the ratio of flame temperature to nozzle stone temperature is minimized, in particular at a nozzle stone temperature of at least 1,300°C or 1,320°C. Such a minimized ratio can characterize a comparatively homogeneous temperature distribution, with as few or as small areas with temperature peaks as possible. This also provides process optimization in terms of output and economic efficiency.

According to the invention, a bulge in the temperature profile can be homogenized over the height. Up to now, many designs have usually had a two-stage temperature profile over the height, each with a relatively pronounced "bulge" or a relatively blatant uneven distribution. The arrangement according to the invention enables the temperature profile to be flattened, in particular over a large height section of the entire heating flue.

According to one embodiment, the mixed gas and/or the combustion air is/are admitted at the respective base by means of the respective inlet at least approximately in a vertical direction. Alternatively, the mixed gas and/or the combustion air can be admitted at the respective base by means of the respective inlet in a direction inclined to the vertical. Optionally, the mixed gas and/or the combustion air can be admitted at the respective base with a vortex or with a swirl impulse on at least one spiral-shaped flow path. This also enables a fine adjustment of flow paths.

According to one embodiment, the admitted gas (in particular combustion air, mixed gas) and/or the circulating gas is aligned or guided in a horizontal direction, in particular at several height levels, in particular by means of impact fittings or impact plates or stones or screens, in particular each made of refractory material. This enables further optimization measures with regard to internal energetic mixing and flattening of temperature profiles, in particular over the height of the heating flue.

According to one embodiment, the gas (combustion air and/or mixed gas) is admitted by means of the inlets at different height levels, in particular with the mixed gas inlet at a height level above the combustion air inlet, in particular by means of the mixed gas inlet in an arrangement on a base above the floor. This also allows further influence on the temperature distribution.

The above-mentioned object is also achieved according to the invention by using combustion air and mixed gas inlets in a coke oven device with a plurality of twin heating flues, each with two heating channels for producing coke by coking coal or coal mixtures, at least with mixed gas heating and optionally also with temporary coke oven gas heating, in particular in a previously described coke oven device, wherein in a respective twin heating flue an internal exhaust gas recirculation is set on at least one circular flow path by means of at least one coupling passage, wherein the inlets are arranged in a ratio y1:y2 of the distance y1 between facing edges of the combustion air inlet and the mixed gas inlet to the distance of the inner edges of the partition walls of a respective heating channel of at least 10% in order to minimize nitrogen oxide emissions through internal thermal energy compensation, wherein the distance y1 between the facing edges of the combustion air inlet and the mixed gas inlet is at least 50mm and wherein the Combustion air inlet is located further inside, closer to the opposite rotor wall than the mixed gas inlet, or vice versa. This provides the previously mentioned advantages.

The aforementioned object is also achieved by using combustion air and mixed gas to minimize nitrogen oxide emissions through internal thermal energy compensation in heating channels of a plurality of twin heating flues of a coke oven device, in particular in a previously described coke oven device, wherein in a respective twin heating flue by means of at least one coupling passage an internal exhaust gas recirculation is set on at least one circular flow path, wherein the combustion air and the mixed gas are admitted at a distance ratio y1:y2 of the distance y1 between their inlets and the distance y2 of the inner edges of partition walls of a respective heating channel of at least 10% and at a distance from one another of at least 50mm, in particular at a flame temperature with mixed gas heating of a maximum of 1,700°C or a maximum of 1,600°C or a maximum of 1,500°C, in particular at a nozzle stone temperature of at least 1,300°C or at least 1,320°C. This provides the previously mentioned advantages, in particular with a nozzle stone temperature increased by at least 20 Kelvin compared to previous operating modes (optional) with the same or lower NO _x emissions.

Further features and advantages of the invention will become apparent from the description of at least one embodiment with reference to drawings, as well as from the drawings themselves.

FIGURE DESCRIPTION

• 1A , 1B , 1C , 1D , 1E , 1F , 1G , 1H each in schematic representation in sectional side views and top views of twin heating trains or coke ovens according to the state of the art;
• 2A , 2 B , 2C , 2D , 2E each in schematic representation in sectional side views and in plan views of twin heating trains or coke oven devices according to embodiments;
• 3 , 4 , 5 , 6 , 7 each in a schematic representation in plan view a relative arrangement of inlets according to an embodiment;
• 8th in schematic representation in plan view a relative arrangement of inlets according to the prior art;
• 9 in schematic representation in plan view structural dimensions for twin heating flues;
• 10A , 10B , 10C each in a schematic representation in plan view a relative arrangement of the inlets relative to a more distant lower recirculation passage according to an embodiment;
• 11 in a schematic representation in plan view a relative arrangement of the inlets relative to a single lower recirculation passage according to an embodiment;
• 12 in schematic representation in plan view an illustration of a flow exchange section with a relative arrangement of the inlets according to the prior art;
• 13A , 13B each in a schematic representation in plan view an illustration of a flow exchange section with a relative arrangement of the inlets according to one of the embodiments.

For reference symbols that are not explicitly described in relation to an individual figure, reference is made to the other figures. In figures that describe the prior art, the positions and angular orientations of the individual inlets and passages or flow paths are only exemplary (in particular only in individual heating channels) and are not fully illustrated or may not be arranged at an exact angle.

In figures describing the present invention, the positions and angular orientations of the individual inlets and passages or flow paths are illustrated schematically (in particular only in individual heating channels), the amounts of the respective distances being defined in more detail in the description.

DETAILED DESCRIPTION OF THE FIGURES

The 1A , 1B , 1C , 1D , 1E , 1F , 1G , 1H show a coke oven 1 in the form of a horizontal chamber oven, with several oven chambers 2, each with a coal charge. The oven chambers 2 have a height of e.g. 6 to 8m. The oven chambers 2 are separated by runner walls 3, each of which extends in a yz plane. Between two runner walls 3, pairs of heating channels 5.1, 5.2 form a twin heating flue 5, the inner wall 5.3 of which separates the heating chamber (free of coal) through which gases flow from the respective oven chamber. The heating channels 5.1, 5.2 are operated alternately as a flame-exposed or exhaust-gas-exposed heating channel, which requires switching the flow direction and takes place in a cycle of e.g. 20 minutes.

The paired heating ducts are each separated from one another by a coupling partition wall (binder wall) 4, in which a coupling passage 4.4 is provided at the top and bottom, via which a circular flow 9 of recirculated exhaust gas can be realized. Adjacent twin heating ducts are completely sealed off from one another by a sealing partition wall 4a without any passages.

A staged air channel 4.1 is arranged in each of the partition walls 4, 4a, which is coupled to the heating channel via at least one combustion stage 4.2 or the corresponding inlet or outlet. The respective combustion stage 4.2 can be arranged in a characteristic height position. For example, two or three height positions are defined into which staged air is admitted.

The respective walls are made of stones, which define a wall layer according to their dimensions.

The x-direction indicates the width of the furnace 1, the y-direction indicates the depth (or the horizontal direction of extrusion in a horizontal chamber furnace), and the z-direction indicates the vertical (vertical axis). The central longitudinal axis M of the respective heating channel runs through the center of the respective heating channel, which is arranged centrally in the x- and y-direction with respect to the inner surfaces/inner walls (not explicitly marked; for example in the center of the respective circular flow-around partition wall, in particular in the center of a centrally arranged stepped air channel). The term "centric" or "center" here refers to a center in the xy plane, and the term "central" or "middle" here refers to the height direction (z).

In the so-called burner level 5.4 or at the bottom of a respective heating channel, several inlets are arranged, namely a (first) combustion air inlet 6, in particular for coke oven gas heating, and a further combustion air inlet 7, in particular for mixed gas heating, and a coke oven gas inlet 8. Gas introduced via these inlets flows upwards on the wall surfaces 4.3 of the partition walls and on the inner walls of the rotor walls.

The following can be mentioned as temperatures at the coke oven 1 that are characteristic for the oven builder/operator: nozzle stone temperature T1, (gas) temperature T2 in the respective heating channel, temperature T3 in the oven chamber. The present invention relates in particular to a profile with regard to temperature T2 that is as homogeneous as possible (in particular also in the vertical direction).

With reference to the 1F to 8E The individual gas flows are described below. The gas flow G1 indicates newly admitted or supplied heating gas or combustion air. The gas flow G1 can comprise a gas flow G1a (coke oven gas) and/or a gas flow G1b (mixed gas). The gas flow G4 indicates recirculation exhaust gases which are returned or circulated. The gas flow G5 indicates gas or air from a respective combustion stage 4.2, 14.11, and the gas flow G6 indicates exhaust gases which are discharged from the respective heating duct or heating flue.

In the 1D The recirculation arrows shown are only schematic and do not exactly reflect the direction of the respective gas flow.

1G shows a schematic of a heating differential 5.6 with individual openings 5.61, through which the gas can be diverted in a head area of the heating channel. The heating differential 5.6 is separated from the respective twin heating flue by an (intermediate) ceiling 5.7. The heating differential 5.6 is independent of the circulating current 9. A distance E between the heating differential 5.6 and the passage 4.4 can be designed individually for each furnace. The reference symbol E can also characterize a cross-sectional area. The cross-sectional area E is preferably at least 300cm ² or at least 340cm ² .

An illustration of the central section of the furnace, which is located below burner level 5.4, has been deliberately omitted for the sake of clarity. The gases can be fed in and the volume flows can be regulated in the central section.

The 2A , 2 B , 2C , 2D , 2E show a coke oven device 10 according to an embodiment, comprising: oven chamber 10.2, flame-treated heating channels 11, inner wall 11.1, exhaust gas-carrying heating channels 12, twin heating flues 13, partition walls 14 with inner surface 14.3, isolating partition walls 14a without passages, staged air channels 14.1 with combustion stages 14.11, coupling passages 14.2, bulges 14.4, rotor walls 15 with inner surface 15.1, combustion air inlets 16, mixed gas inlets 17, coke oven gas inlets 18, slide blocks 19.

With reference to the 2A , 2 B , 2C , 2D , 2E In the following, the distances and relative positions of the individual inlets and passages according to the invention are described using further embodiments.

In 2A is schematically (in some heating channels) the paired arrangement of the inlets 16, 17 opposite the inlet 18.

In 2 B it is shown that the inlets 16, 17 are offset relatively far outwards in the x-direction (eccentric), and are relatively far apart from each other in the y-direction. The arrangement of the optional coke oven gas inlet 18 is independent of this, or can be chosen largely freely.

In 2C It is shown that the offset in the x and y directions can also result in an advantageous relative arrangement with respect to the step air G4. The 2C The angle indicated for an angular alignment of the inlets can be varied individually for each inlet. Depending on the design of the central structure, an angle in the range of 5 to 10° can be a rational compromise between additional construction and technical equipment expenditure and achievable thermal and/or flow effects.

In the 2C The arrangement, number and geometry of the passages 14.2 shown or the staged gas inlet 14.11 can also be varied according to the variants shown or discussed in the other figures.

With reference to the 8B to 8E The individual gas flows are described below. The respective gas flow path GP1 identifies inflow paths or flow paths according to the invention for at least one of the gases G1 introduced via the inlets. The respective gas flow path GP4 identifies flow paths of recirculated exhaust gas/flue gas G4, and the respective gas flow path GP5 identifies flow paths of gas G5 introduced in stages.

2D illustrates in particular the comparatively large distance y1.

2E shows a view analogous to that according to 2C . The 2C , 2E illustrated inflow angle, in particular for coke oven gas, is preferably less than 30°, in particular less than 10° in each case with respect to the z-axis. The inflow angle can also be realized analogously for the other inlets 17, 18.

The distances and relative positions mentioned with respect to the respective inlets and passages may also reciprocally refer to the distances and relative positions of the respective gas flow paths/circulating flow paths, at least in a section upstream of a subsequent mixing with adjacent gas flows.

The 3 shows an arrangement with the inlets 16, 17 on the same x-coordinate (x1=x2) at a comparatively large distance from the opposite rotor wall 15. The ratio y1:y2 is in the range of 25% to 30%, so it is comparatively large. Here, y1 is greater than 50mm. This arrangement in particular also offers the advantage of flexible compensation of pressure losses.

• - vergleichsweise hoher Druckverlust (z.B. im Sommer) im Heizzug: Schieber geöffnet zwecks Minimierung des Druckverlustes;
• - Regulierung von Druckverlust und Durchflüssen insbesondere zur Anpassung der Leistungskapazität der Anlage (insbesondere je nach gewünschtem Koks-Output);
• - Regulierung von Druckverlust und Durchflüssen insbesondere zur Anpassung der Betriebsparameter auf das Einsatzmaterial (Anpassung der so genannten Kohlebasis), z.B. bei zunehmendem Wassergehalt höherer Gasbedarf;

3 shows in particular an advantageously adjustable inlet cross-section of both openings (gas and air). This enables, in addition to optimization of the internal energy distribution, also process-related variations, particularly in connection with the following situations:

• - comparatively high pressure loss (e.g. in summer) in the heating flue: damper opened to minimize the pressure loss;
• - Regulation of pressure loss and flow rates, in particular to adapt the power capacity of the plant (in particular depending on the desired coke output);
• - Regulation of pressure loss and flow rates, in particular to adapt the operating parameters to the feedstock (adaptation of the so-called coal base), e.g. with increasing water content, higher gas demand;

In all the embodiments shown, the inner corners between the walls can also have radii or be rounded, in particular for reasons of stability, in particular in the form of so-called head ties. The size ratios and dimensions according to the invention are independent of such roundings; rather, the size ratios and dimensions refer to the distances between parallel walls or at least approximately parallel wall sections, in particular to the largest distances in the relevant cross-sectional plane.

3 shows an arrangement in which air inlet 16 and mixed gas inlet 17 completely overlap in the x-direction, wherein the inlets are arranged without x-offset and have at least approximately the same x-extension.

The 4 shows an arrangement with the inlets 16, 17 on different x-coordinates (x1>x2) at a comparatively large distance y1. The ratio y1:y2 is in the range of 25% to 30%. Here, y1 is much larger than 50mm. The extension y2 is dimensioned in relation to the inner surface of the respective partition wall as such (per se), in particular in relation to the furthest parallel section of the partition wall, i.e. independently of any optionally provided bulges 14.4 for step air ducts. Such bulges 14.4 are optionally provided in particular for stability reasons in comparatively narrow partition walls. The y-dimension (depth) is in the range of 5 to 40mm, for example.

Especially in the case of an arrangement according to 4 The advantage of great flexibility with regard to varying operating parameters can also be ensured.

• - Parameteroptimierung insbesondere hinsichtlich Änderungen der Gasqualität: im Verlauf der Lebensdauer kann temporär oder permanent ein niederkaloriges Mischgas (insbesondere mit unteren Heizwerten kleiner als 4185kJ pro Nm³; typische untere Heizwerten von Mischgasen im Bereich von 4185 bis 5500kJ pro Nm³) zur Anwendung kommen;
• - Variation des Gas/Luft-Verhältnisses am Boden über einen vergleichsweise großen Bereich mit gutem Effekt auf die vertikale Temperaturverteilung; dies kann insbesondere bei einer erforderlich werdenden Kapazitätsänderung des Ofens oder bei veränderter Beheizungsführung oder veränderter Kohlebasis vorteilhaft sein.

4 In particular, it also shows measures regarding the size and geometry of the outlet openings. In addition to optimizing the internal energy distribution, this also enables process-related variations, particularly in connection with the following situations:

• - Parameter optimization, particularly with regard to changes in gas quality: over the course of the service life, a low-calorific mixed gas (in particular with lower calorific values of less than 4185 kJ per Nm ³ ; typical lower calorific values of mixed gases in the range of 4185 to 5500 kJ per Nm ³ ) can be used temporarily or permanently;
• - Variation of the gas/air ratio at the bottom over a comparatively large range with a good effect on the vertical temperature distribution; this can be particularly advantageous if a change in the capacity of the furnace becomes necessary or if the heating system or coal base is changed.

4 shows an arrangement in which the air inlet 16 completely overlaps the mixed gas inlet 17 in the x-direction.

The 5 shows an arrangement with the inlets 16, 17 on comparatively clearly/strongly different x-coordinates (x1>x2) at a comparatively large distance y1, whereby the inlets 18 are arranged comparatively far in the middle in the x-direction, in particular also at least approximately in the middle in the y-direction. The ratio y1:y2 is in the range of 25% to 30%. Here y1 is greater than 50mm. The ratio nis x2:x1 is, for example, in the range of 0.7. Especially with this arrangement, the advantage of high practicability with regard to parameter variations can be ensured.

• - Luftöffnung am Boden in Ausgestaltung als Düse 16 (illustriert durch runde Querschnittsgeometrie); Düsen können insbesondere bei Zugang von oben von der Decke aus einfacher zugänglich und austauschbar sein als Schiebersteine.

5 In particular, it also shows measures regarding the geometry of the inlets or their design as nozzles. In addition to optimizing the internal energy distribution, this also enables process engineering variations, particularly in connection with the following situations:

• - Air opening at the bottom in the form of a nozzle 16 (illustrated by round cross-sectional geometry); nozzles can be easier to access and replace than slide blocks, particularly when accessed from above from the ceiling.

5 shows an arrangement in which the air inlet 16 completely overlaps the mixed gas inlet 17 in the x-direction.

In all embodiments shown, the coke oven gas inlets can optionally also be integrated into the partition wall, i.e. not arranged at a distance from the partition wall in the y-direction, but installed with the partition wall.

The 6 shows an arrangement with the inlets 16, 17 on comparatively clearly/strongly different x-coordinates (x1<x2) at a more or less maximum distance y1. The ratio y1:y2 is in the range of 25% to 30%. Here, y1 is much larger than 50mm. The ratio x1:x2 is, for example, in the range of 0.7. In embodiments according to 6 Particularly advantageous effects with regard to NO _x reduction and also with regard to other operating parameters such as pressure loss can be ensured.

In the embodiments according to 6 the air and mixed gas inlets 16, 17 can in particular be arranged without any overlap in the x-direction.

The 7 shows an arrangement comparable to that according to 6 , whereby the offset between the inlets 16 and 17 is inverted (x1>x2). The ratio y1:y2 is in the range of 25% to 30%. Here, y1 is much larger than 50mm. The ratio x2:x1 is, for example, in the range of 0.6 or 0.5. This arrangement in particular ensures the advantage of very effective mixing of recirculated exhaust gas with air.

For embodiments according to 7 In particular, thanks to the arrangement of the air inlet 16 in the area of the recirculation openings 14.2 (in particular comparable x-coordinate), the gas composition can be influenced before combustion. In particular, the recirculated exhaust gas is mixed with the air shortly after the respective recirculation opening, in particular without combustion being caused there. This process engineering arrangement can also be described as primary mixing of flue gas and air. Effect: Thanks to the arrangement according to the invention, external recirculation of flue gas and air is not required; this also means that measures relating to larger flow cross-sections in the regenerator can be saved.

In the embodiments according to 7 the air and mixed gas inlets 16, 17 can be arranged in particular without any overlap in the x-direction, in particular asymmetrically to the 6 arrangement shown.

In the embodiments according to 6 , 7 In particular, slide blocks can also be provided.

The 8th shows an arrangement according to the prior art, with the inlets 6, 7 on a comparable (in particular identical) x-coordinate and comparatively strongly offset towards the x-center, in particular in an at least approximately central x-arrangement, wherein the inlet 8 is arranged on an x-coordinate in the region of recirculation openings. The distance y1 is averagely large, and the ratio y1:y2 is averagely large. The x-coordinate of the inlets 6, 7, in particular of their centers, is approximately half the absolute x-width of the respective heating flue, and is in particular within the following range for the ratio of absolute x-distance of the rotor walls 15 to x1 or to x2: range from 0.4 to 0.6.

9 describes an exemplary arrangement of the openings according to the invention in the context of further structural details of a furnace. The furnace pitch x0 is in particular in the range of 1000 to 1800 mm (measure from furnace chamber half to furnace chamber half; center to center). The heating flue pitch y0 is in the particularly in the range from 400 to 550mm (center of partition wall to center of partition wall). The partition walls 14 have, for example, a thickness (y-dimension) in the range from 130 to 170mm. The runner walls 15 have, for example, a thickness (x-dimension) in the range from 70 to 130mm.

The y-extension of the combustion air inlets 16 is, for example, in the range greater than or equal to 50mm, with a minimum distance to the nearest partition wall 14 of at least 50mm. The y-extension of the mixed gas inlets 17 is, for example, in the range greater than or equal to 50mm, with a minimum distance to the nearest partition wall 14 of at least 50mm. The x-extension of the combustion air inlets 16 is, for example, in the range greater than or equal to 100mm, with a minimum distance to the rotor wall 15 of at least 50mm. The x-extension of the mixed gas inlets 17 is, for example, in the range greater than or equal to 100mm.

The 10A , 10B , 10C illustrate in particular the “forward burning” operating mode, with recirculation passages provided in pairs as an example. 10A describes an exemplary arrangement according to the invention with the inlets 16, 17, 18 in such a relative arrangement to the more distant lower recirculation passage 14.2 (center points in each case) that a quadrilateral with an area A is spanned. The area is, for example, in the range from 500cm ² to 1,700 cm ² , in particular in the range from 1,000cm ² to 1,500cm ² . 10A also illustrates the exit plane xz14 of the partition wall 14. The relevant corner point of the polygon is offset inwards towards the middle of the wall. The area specification is therefore independent of the wall thickness of the partition wall 14.

10B describes an exemplary arrangement according to the invention with the inlets 16, 17, 18 in such a relative arrangement to the more distant lower recirculation passage 14.2 (center points in each case) that a quadrilateral with an area A is spanned. The area is in particular in the range from 700cm ² to 1,600cm ² . The basic shape of the quadrilateral is trapezoidal.

10C describes an exemplary arrangement according to the invention with the inlets 16, 17, 18 in such a relative arrangement to the more distant lower recirculation passage 14.2 (center points in each case) that a quadrilateral with an area A is spanned. The area is in particular in the range from 500cm ² to 1,400cm ² .

It has been shown that for the previously described "forward burning" furnace configurations, a surface area A in the range of 1,100 to 1,500 cm ² can be particularly advantageous. Depending on the individual design of the furnace (size, performance), an advantageous range of 200cm ² to 2,000cm ² can be defined for the surface area A, particularly preferably 500cm ² to 1,500cm ² , particularly in the case of comparatively large furnaces with a furnace chamber height of more than seven (7) meters, more preferably 700cm ² to 1,500cm ² , i.e. at the heights of more than 7 meters that have become common in many applications in recent years.

11 describes an exemplary arrangement according to the invention with reference to a furnace design with only one lower recirculation passage, in particular with so-called "back-to-back" heating. The inlets 16, 17, 18 are arranged relative to one another and relative to the (only) lower recirculation passage 14.2 (each center point) in such a way that a quadrilateral with an area A is spanned. The area is, for example, in the range from 300cm ² to 1,300 cm ² , in particular in the range from 800cm ² to 1,300cm ²

It has been shown that in this "back-to-back" configuration, a surface area A in the range of 1,000 to 1,250 cm ² can be particularly advantageous. Depending on the individual design of the furnace (size, performance), an advantageous range of 50cm ² to 1,800cm ² can be defined for the surface area A, particularly preferably 300cm ² to 1,300cm ² , particularly in the case of comparatively large furnaces with a furnace chamber height of more than 7 meters, further preferably 500cm ² to 1,300cm ² .

This again applies to large ovens with a chamber height of more than 7 m (standard for new buildings). For smaller ovens with a chamber height of between 4 m and 7 m, I have again lowered the lower limit for the area requiring special protection significantly. If this optimal area is found to be too large, I would raise the lower limit by 200 cm2.

In the 10ff . and 11, a triangle can optionally also be spanned, namely in the case that the rich gas inlet 18 is arranged on a connecting line from one of the further inlets 16, 17 to the center of the recirculation passage 14.2.

In the 10ff . and 11, the geometric centers of the inlets of the respective heating flue and of the at least one lower coupling passage, in particular one of several lower coupling passages further away from the combustion air and mixed gas inlet, define a quadrilateral arrangement whose surface area in plan view is at least 50cm ² , preferably at least 200cm ² or at least 300cm ² or at least 500cm ² or at least 700cm ² .

In the arrangements described above, the height positions of the inlets may vary downwards or upwards with respect to the burner plane, as generally described above.

12 describes a relative arrangement of the mixed gas inlet 17 relative to the combustion air inlet 16 according to the prior art. A flow exchange section B resulting between these two adjacent inlets 16, 17, in the sense of a fluidically effective contact surface between two different types of gas or gas mixtures, is arranged orthogonally to cross connections between these inlets. It has been shown that this arrangement, with a comparatively small y-distance and a comparatively large flow exchange surface, leads to strong mixing just above the inlets, with the effect that a high temperature (too high maximum temperature) is established and a disadvantageously high NO _x emission cannot be avoided or can only be avoided by means of countermeasures.

13A shows a relative arrangement of the mixed gas inlet 17 relative to the combustion air inlet 16 according to one of the measures according to the present invention. The flow exchange section B is of comparable size to the arrangement according to 12 . The inlets overlap completely and are at least the same size in the x-direction. However, the distance in the y-direction is significantly larger than in the arrangement according to 12 , with the effect that the mixing of air and mixed gas can be delayed (in time or in relation to the height direction) and/or less intense mixing occurs. In this arrangement, the comparatively large flow exchange area is not a disadvantage.

13B shows an arrangement in which the flow exchange area or the flow exchange section B is reduced due to lateral x-offset. As an example, the flow exchange section B is also applied orthogonally to cross connections between the inlets. The inlets overlap only very slightly or optionally not at all. The y-distance is comparable to that according to the arrangement in 13A It has been shown that this combined measure can significantly delay the mixing of air and mixed gas and that a very advantageous temperature distribution can be ensured, particularly over the height of the heating flue and optionally also in other dimensions of the heating flue. NO _x emissions can be reduced very effectively.

List of reference symbols:

1

Coke oven, especially horizontal chamber oven

2

Furnace chamber with coal charge

3

Runner wall

4

coupling partition wall or binder wall

4a

isolating partition wall without openings

4.1

Duct or step air duct in partition wall

4.2

Combustion stage or inlet or outlet on the stage air duct from/to the heating duct

4.3

Wall surface

4.4

two heating channels coupling passage (or exhaust gas reversal point or reversal point for heating gas)

5

Twin heating flue (paired arrangement of two vertical heating flues)

5.1

flame-treated heating channel (vertical heating channel)

5.2

Exhaust gas-carrying heating duct (vertical heating duct)

5.3

Inner wall

5.4

Burner level or bottom of a heating channel

5.6

Heating differential

5.61

single opening in the heating differential

5.7

(False) ceiling of a heating duct

6

(first) combustion air inlet, especially for coke oven gas heating

7

additional combustion air inlet or inlet for mixed gas heating

8th

Coke oven gas inlet or coke oven gas nozzle

9

Circulating current

10

Coke oven device, in particular with horizontal chamber oven

10.2

Oven chamber

11

flame-treated heating channel (vertical heating channel)

11.1

Inner wall

12

Exhaust gas-carrying heating duct (vertical heating duct)

13

Twin heating flue (paired arrangement of two vertical heating flues)

14

Partition wall or truss wall

14a

isolating partition wall without openings

14.1

Duct or step air duct in partition wall

14.11

Combustion stage or stage air inlet or outlet on the stage channel from/to the heating channel

14.2

two heating channels coupling passage

14.3

Inner surface of the partition

14.4

Bulge for step air duct

15

Runner wall

15.1

Inner surface of the runner wall

16

(first) combustion air inlet or air inlet, especially for coke oven gas heating

17

additional combustion air inlet or mixed gas inlet, especially for mixed gas heating

18

Coke oven gas inlet or coke oven gas nozzle

19

Slide stone

A

Area of polygon arrangement (triangle or quadrilateral)

B

Flow exchange section

E

Distance between heating differential and passage

G1

Heating gas or combustion air

G1a

Coke oven gas

G1b

Mixed gas

G4

Recirculation exhaust gas

G5

Stage gas or stage air from combustion stage

G6

Exhaust

GP1

Inflow path or flow path for at least one of the gases introduced via the inlets

GP4

Flow path of recirculated exhaust gas/flue gas

GP5

Flow path of staged gas introduction

M

Central longitudinal axis of the respective heating channel

T1

Nozzle stone temperature

T2

(Gas) temperature in the heating flue/duct

T3

Temperature in the oven chamber

x

horizontal direction (width or length; longitudinal extension of truss wall)

x0

Furnace division

x1

Distance of the combustion air inlet to the opposite rotor wall

x2

Distance of the mixed gas inlet to the opposite rotor wall

xz14

Exit level partition wall

y

Depth or horizontal expression direction (longitudinal extension of runner wall)

y0

Heating flue division

y1

Distance between facing edges of the combustion air inlet and the mixed gas inlet

y2

Distance between the inner edges of the partition walls

z

vertical direction (vertical axis)

Claims (12)

Coke oven device (10) for producing coke by coking coal or coal mixtures at least with mixed gas heating and optionally also with temporary coke oven gas heating, wherein the coke oven device is designed for minimizing nitrogen oxide emissions through internal thermal energy compensation by means of gases from the steelworks and gases from the coke oven (G1, G4, G5), with a plurality of twin heating flues (13), each with a gas-flamed heating channel (11) and a downward-flowing heating channel (12) carrying exhaust gas, wherein the heating channels (11, 12) are each separated from one another in pairs by a partition wall (14) and sealed off from a respective furnace chamber (10.2) by two opposing rotor walls (15), wherein the paired heating channels (11, 12) are fluidically connected by means of at least one upper coupling passage (14.2) and also by means of at least one lower coupling passage (14.2) each for internal exhaust gas recirculation are coupled to one another on at least one circular flow path, wherein in the lower region on the floor (5.4) of the respective twin heating flue (13) at least one inlet from the following group is provided: coke oven gas inlet (18), combustion air inlet (16), mixed gas inlet (17); characterized in that at the respective base (5.4) the ratio (y1:y2) of the distance (y1) between the facing edges of the combustion air inlet (16) and the mixed gas inlet (17) to the distance (y2) of the inner edges of the partition walls (14) of a respective heating channel (11, 12) is at least 10%, wherein the distance (y1) between the facing edges of the combustion air inlet (16) and the mixed gas inlet (17) is at least 50mm, wherein at least one of the combustion air and mixed gas inlets (16, 17) is arranged eccentrically at an x-distance greater than a factor of 0.7 of the absolute x-extension of the heating channel between opposite rotor walls (15), and wherein the combustion air inlet (16) is arranged further inside closer to the opposite rotor wall (15) than the mixed gas inlet (17), or vice versa. Coke oven device (10) according to the preceding claim, wherein the distance (y1) between the facing edges of the combustion air inlet (16) and the mixed gas inlet (17) is at least 100 mm; and/or wherein the ratio (y1:y2) of the distance (y1) between the facing edges of the combustion air inlet (16) and the mixed gas inlet (17) to the distance (y2) of the inner edges of the partition walls (14) of a respective heating channel (11, 12) is at least 25%. Coke oven device (10) according to one of the preceding claims, wherein the geometric centers of the inlets of the respective heating flue and of the at least one lower coupling passage (14.2), in particular of a plurality of lower coupling passages further away from the combustion air and mixed gas inlet, define a triangular or square arrangement, the surface area (A) of which in plan view is at least 50cm ² , in particular at least 200cm ² or at least 300cm ² or at least 500cm ² or at least 700cm ² or at least 900cm ² , in particular between 1,000cm ² and 1,350cm ² ; and/or wherein the triangular or square arrangement has a surface area (A) in plan view of a maximum of 2,000cm ² , in particular a maximum of 1,800cm ² or a maximum of 1,500cm ² or a maximum of 1,300cm ² or a maximum of 700cm ² , in particular between 1,000cm ² and 1,300cm ² . Coke oven device (10) according to one of the preceding claims, wherein at the respective bottom the cross-sectional area of the combustion air inlet (16) and/or the mixed gas inlet (17) is at least 30cm ² or at least 50cm ² ; and/or wherein the cross-sectional area of the combustion air inlet (16) and/or the mixed gas inlet (17) is at most 500cm ² or at most 400cm ² ; and/or wherein the cross-sectional geometry of the combustion air inlet (16) and/or the mixed gas inlet (17) is rectangular or elliptical or round. Coke oven device (10) according to one of the preceding claims, wherein the cross-sectional area of the combustion air inlet (16) and/or the mixed gas inlet (17) is adjustable in terms of geometry and/or size at the respective bottom, in particular by means of at least one displaceable slide block and/or by means of at least one replaceable/removable nozzle. Coke oven device (10) according to one of the preceding claims, wherein the at least one upper recirculation passage (14.2) coupling the two respective heating channels of a respective twin heating train (13) in the upper region is set up for the mutual transfer of gases, wherein the recirculation passage (14.2) has a cross-sectional area of at least 250cm ² , in particular of a maximum of 1200cm ² or a maximum of 1000cm ² ; and/or wherein the paired heating channels (11, 12) are fluidically coupled to one another by means of at least two lower coupling passages (14.2), wherein the combustion air inlet (16) is arranged at least approximately in the same x-position as the corresponding lower coupling passage (14.2), in particular with the respective center point of the combustion air inlet (16) and the corresponding passage in an arrangement on the same x-coordinate; and/or wherein at least two lower coupling passages are provided, in particular arranged in pairs at the same height position. Coke oven device (10) according to one of the preceding claims, wherein the combustion air inlet (16) and the mixed gas inlet (17) are arranged offset in the x-direction with respect to the opposite rotor wall (15); and/or wherein on the respective floor the edges of the combustion air inlet (16) and the mixed gas inlet (17) facing the rotor walls (15) are arranged at different distances (x1, x2) from at least one of the two opposite rotor walls (15) of the respective twin heating flue (13), in particular with a distance difference of at least 10 mm or at least 50 mm; and/or wherein the ratio (x1:y1) or (x2:y1) of the distance (x1,x2) of the combustion air inlet (16) and/or the mixed gas inlet (17) to the opposite rotor wall (15) to the distance (y1) is at least 90% and/or a maximum of 290%, in particular between 200% and 250%. Method for operating a coke oven device (10) for producing coke by coking coal or coal mixtures with optimized, minimized nitrogen oxide emissions through internal thermal energy compensation by means of gases from the steelworks and gases from the coke oven (G1, G4, G5) by measures internal to the coke oven device at least with mixed gas heating and optionally also with temporary coke oven gas heating, in particular for operating a coke oven device (10) according to one of the preceding claims, wherein in a respective twin heating flue (13) of the coke oven device with a flame-treated heating channel (11) and an exhaust gas-carrying heating channel (12) by means of at least one coupling passage (14.2) through a partition wall (14), an internal exhaust gas recirculation is set on at least one circular flow path around the partition wall, wherein in the lower area on the floor (5.4) of the respective twin heating flue (13) at least two gases from the following group are admitted: coke oven gas (G1a), Combustion air (G1), mixed gas (G1b), wherein the group of admitted gases comprises at least the two gases combustion air (G1) and mixed gas (G1b); characterized in that at the respective base (5.4) the combustion air (G1) and the mixed gas (G1b) are admitted on flow paths at a distance (y1) from one another in the ratio (y1:y2) of at least 10% to the distance (y2) of the inner edges (inner surfaces) of the partition walls (14) of a respective heating channel (11, 12), the distance (y1) between these two admitted flow paths being at least 50 mm, combustion air (G1) and/or mixed gas (G1b) being admitted eccentrically at an x-distance greater than a factor of 0.7 of the absolute x-extension of the heating channel between opposite rotor walls (15), and combustion air (G1) being admitted through the combustion air inlet (16), which is arranged further inside closer to the opposite rotor wall (15) than the mixed gas inlet (17), or vice versa. Method according to the preceding method claim, wherein the cross-sectional area of the combustion air inlet (16) and/or the mixed gas inlet (17) are adjusted at the respective bottom with regard to geometry and/or size, in particular by means of at least one slide block. Method according to one of the preceding method claims, wherein the flame temperature in mixed gas heating is a maximum of 1,700°C or a maximum of 1,600°C or a maximum of 1,500°C, in particular at a nozzle stone temperature of at least 1,300°C or at least 1,320°C; and/or wherein the gas flows in the respective heating pass are adjusted such that the ratio of flame temperature to nozzle stone temperature is minimized, in particular at a nozzle stone temperature of at least 1,300°C or 1,320°C. Method according to one of the preceding method claims, wherein the admitted gas and/or the circulating gas is aligned or guided in a horizontal direction, in particular at several height levels, in particular by means of impact fittings or impact plates or stones or screens, in particular each made of refractory material; and/or wherein the gas is admitted by means of the inlets at different height levels, in particular with the mixed gas inlet at a height level above the combustion air inlet, in particular by means of the mixed gas inlet in an arrangement on a base above the floor. Use of combustion air (16) and mixed gas inlets (17) in a coke oven device (10) with a plurality of twin heating flues (13) each with two heating channels (11, 12) for producing coke by coking coal or coal mixtures at least with mixed gas heating and optionally also with temporary coke oven gas heating, in particular in a coke oven device (10) according to one of the preceding device claims, wherein in a respective twin heating flue (13) by means of at least one coupling passage (14.2) an internal exhaust gas recirculation is set on at least one circular flow path, wherein the inlets are arranged in a ratio (y1:y2) of the distance (y1) between facing edges of the combustion air inlet (16) and the mixed gas inlet (17) to the distance (y2) of the inner edges of the partition walls (14) of a respective heating channel in order to minimize nitrogen oxide emissions by internal thermal energy compensation (11, 12) of at least 10%, wherein the distance (y1) between the facing edges of the combustion air inlet (16) and the mixed gas inlet (17) is at least 50mm and wherein the combustion air inlet (16) is arranged further inside closer to the opposite rotor wall (15) than the mixed gas inlet (17), or vice versa.

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