EP3681978B1 - Coke oven device with central recirculation for producing coke and method for operating the coke oven device and control system and use - Google Patents

Description

The invention relates to a device and a method for producing coke as well as a control device and corresponding uses. In particular, the invention relates to a device and a method according to the respective independent claim.

The demand for coke ovens remains high worldwide and is expected to remain high in the future, as described, for example, 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; PUBLISHING STAHLEISEN MBH; 1997 . The planning and construction of coke ovens must be carried out over a long period of time, especially since the operating time or service life of a coke oven can be quite long, so it is important to know what environmental improvements can be achieved in coke ovens in the next few years. Every year, despite increasingly strict environmental criteria, several hundred new coke ovens are built and put into operation. Nevertheless, most politicians are now well aware that generating energy using coke ovens is not particularly environmentally friendly. The construction of new coke ovens, or even the operation of existing coke ovens, is therefore subject to increasingly strict emissions requirements from many sides, particularly with regard to nitrogen oxides (NOx). In this context, there are numerous efforts to improve the efficiency of coking or environmental friendliness, as can be found, for example, in the following publication and the specialist articles cited therein: AJ Nowak et al.: CFD model of coupled thermal processes within coke oven battery .... Computer Assisted Mechanics and Engineering Sciences, 17: 161-172, 2010 . This publication deals with the simulation of previously known optimization measures.

The following emission limits are currently permitted or still tolerated in existing systems: 500mg/Nm ³ , corresponding to approx. 250ppm at 5% oxygen 02. Future limit values are: approx. 350mg/Nm ³ (approx. 170ppm at 5 % 02) in Europe, or soon probably only around 200mg/Nm ³ in Asia, especially Japan, Korea, Taiwan and China. In other words: NOx emissions should probably be reduced by half or more as quickly as possible. However, some environmental authorities are already demanding an upper limit in the range of only approx. 100mg/Nm ³ , especially in Asia, which would correspond to a factor of 5. In view of increasingly strict requirements, especially for diesel-powered vehicles, it must also be expected in Europe that the permissible limit value will soon be lower than 350 mg/Nm ³ .

Nitrogen oxides are released in particular by the flue gas generated by coke oven gas combustion or are formed during combustion, especially from a nozzle stone temperature (in the exhaust gas-carrying heating duct on the floor) of approx. 1,250 ° C (so-called thermal NOx formation). The thermal NOx formation is exponentially further promoted or fanned with higher temperatures, so that the emission of nitrogen oxides is largely determined by the thermal conditions in the coke oven. It is known that NOx emissions can be influenced by setting a specific temperature regime, particularly in the vertical, flue gas-carrying heating flues of the coke oven. The rule of thumb applies: the higher the temperature, the greater the NOx emissions. A furnace operator therefore tries or is forced by environmental regulations to keep the temperature as low as possible, in particular not to allow it to rise above the limit of 1,250°C. The furnace operator is also interested in an efficient coking process and would like an operating mode with nozzle stone temperatures of up to 1,325°C; The efficiency of coking increases with temperature, and the higher the operating temperature, the more compact a furnace battery can be designed with the same output. Example: Instead of 100 ovens, only around 95 to 98 ovens have to be built at a higher operating temperature, corresponding to an equipment saving of 2 to 5 percent (lower investment volume, up to 5% less system costs, e.g. in relation to an investment volume of 100 to 800 million . Euro).

In order to reduce NOx emissions, attempts are therefore only made with great reluctance to achieve a lower temperature level during coking or to avoid temperature peaks in the heating flues, especially by adjusting the operating mode, because this entails power losses and makes coke production less economical. It is therefore not interesting or feasible for the oven operator not to operate the coke oven in optimal operating condition. Consequently, it is accepted that NOx emissions will remain disadvantageously high. However, the furnace operator knows: If it were possible to keep the heat energy input constantly high at a comparatively moderate, reduced temperature, this would have a positive effect on NOx emissions with a comparable output.

An oven operator must take these boundary conditions into account for different types of coke ovens. In particular, a distinction is made between vertical chamber ovens and horizontal chamber ovens according to the direction in which the coke is pushed out: In horizontal chamber ovens, coking is carried out in batches. After coking, the coke is expressed in a horizontal direction (batch operation). In contrast, in vertical chamber furnaces the coal is continuously fed in and removed in a vertical direction (Conti operation). The present invention relates particularly to horizontal chamber furnaces.

Furnace chambers usually have a height in the range of 4 to 8.5m, with the height of the furnace chambers or heating channels also being dictated by the mode of operation. The height influences the pressure difference that occurs in the heating duct. If a large pressure difference is required, a large altitude must be selected. It can be assumed that the temperature should be kept as constant as possible over the altitude, because only then will it be possible to set an efficient operating state without a too strong increase in NOx emissions. The temperature gradient should be as significantly smaller as possible than 40K or 40°C, especially at a temperature in the oven chamber in the range of 1,000 to 1,100°C. A temperature maximum significantly above the average temperature would promote thermal NOx formation. A coke oven can therefore be operated with an optimal compromise between high output and low NOx emissions if the temperature remains homogeneously just below the temperature at which thermal NOx formation occurs.

The simulation of operating states is a useful tool to better assess the effects of individual optimization measures. However, a coke oven is a comparatively complex system, requiring a corresponding amount of simulation effort. For example, a new design with a new way of routing gas can require several weeks of calculations per calculation, so that simulations can also require several years of work (e.g. with over 100 variations required). Not only does testing of new measures on a technical scale have to be carried out with limited options, but also a simple design measure must first be checked from numerous aspects for cost reasons alone before this measure can be examined in more detail through simulations. This means that constructive variations on existing furnace designs are only carried out in a very moderate, conservative manner.

Measures that have so far been tried and tested directly on the coke oven or on its structural design, which should also work in performance-optimized operating mode, are usually the internal pressure difference-driven or temperature and density differences-driven flue gas recirculation from the heating flue flowing downwards into the upward flow (internal circulation of a partial volume flow of the flue gas , so-called circulating flow), and/or the grading of the combustion air, i.e. the introduction of combustion gas from partition walls or truss walls at different height positions into the heating flues. The steps are carried out in particular with regard to the following criteria: maximum gas collection room temperature in the adjacent furnace chamber above the coal charge must be less than 820 ° C; If possible, the ceiling surface temperature must be less than or equal to 60°C; Furnace chamber wall internal temperature difference <= 40K, especially between the height positions 500mm above the furnace sole/burner level and 500mm below the top edge of the furnace chamber.

Circular current routing (partially at one end of the heating duct or completely in a circle) is usually implemented in so-called twin heating flues. Heating cables or heating channels arranged next to one another in pairs, in particular in a vertical orientation, are coupled to one another by returning the gas from the flamed heating channel into the non-flamed heating channel, be it only at an upper/lower reversal point, or be it both above and below . In a horizontal chamber furnace, approximately 24 to 40 heating channels can be provided in the direction of expression, i.e. approximately 12 to 20 pairs of twins. An optionally realizable circulating flow can form autonomously due to the pressure differences, i.e. without additional active flow control or support.

The optimization of circular current routing, particularly for the purpose of homogeneous heat distribution, began on an industrial scale as early as the 1920s. Since the 1970s, the influences of circulating flow on NOx emissions have also been examined in more detail.

The configuration of coke ovens with circulating flow that have been used in most cases to date can be described as follows: In pairs of heating channels (twin heating flues), a heating gas is led upwards in the direction of flow, i.e. in the flamed heating channel, and is burned in particular in multiple stages, which is then passed through as flue gas parallel, exhaust gas-carrying heating channel is led back down to the floor and sucked off there, with a partial volume flow of the inert (burned out) exhaust gas in the circuit is led back into the upward, flamed heating channel. The heating channels can be coupled to one another at the upper and lower ends by means of an exhaust gas recirculation opening or a passage, in particular in the area of the bottom of the furnace chamber at least approximately at the same height as the inlets. In this way, the average nozzle stone temperature in the heating train can be controlled and, in particular, by lowering the local flame temperature (for strong gas heating above 2000°C, for mixed gas heating below 2000°C) it can be kept at a moderate level (e.g. at a nozzle stone temperature of 1240 to 1300 °C), with the effect that NOx emissions can be reduced. For example, the following arrangement (height position) of the lower passage can be mentioned: between 0mm (i.e. directly at the level of the burner level) to 300mm above the burner level. The cross-sectional area is usually specified by a layer height of approx. 120mm. If necessary, the lower passage can be closed in the arrangement on the floor by means of a roller, which can be rolled on the burner level in front of the passage. The passage is advantageously realized by means of a recess in a wall layer (gap or missing stone).

Such heating channels or twin heating flues, arranged in pairs and aligned in the vertical direction, make it possible to influence the temperature profile with comparatively little effort, especially when specifically adapting the circulation of flue gas. A distinction is always made between two types of heating flues/heating channels: upward flow, flamed heating channel; downward-flowing, exhaust gas-carrying heating channel. The paired heating channels are connected to one another in the upper area via a free opening cross section, i.e. a passage through which the heating channels are fluidly coupled to one another. With strong gas heating, a partial volume flow of the flue gas that is usually led back into the flamed heating channel is, for example, 30 to 45% of the total flue gas volume generated in the heating channel flowing upwards. An example of this arrangement of twin heating flues with circulating current is the so-called Combiflame heating system, which has been established since the late 1980s. This involved a combination of air staging and circulating flow. Before that, until the mid-1980s, there was either air staging (Otto system) or circular flow (Koppers system).

If the present description refers to a single passage, it can also mean a pair of passages, which are arranged in pairs in the same height position.

As previously indicated, the combustion can also be staggered by passing gas or air into the respective heating flue via at least one stepped air duct in at least one height position above the burner level (floor), or by expelling the corresponding exhaust gas. Staged combustion can be combined with circulating current.

If the measures directly on the coke oven are specifically considered, i.e. measures for thermal optimization, in particular through an optimized way of media management, the structural structure of the coke oven and the associated stability of the coke oven are of great relevance, in particular the structural structure of the individual walls a respective oven chamber and the respective heating flue (rotor walls, partitions). Small structural changes can have major effects on the temperature balance and the coking process. However, each measure may also have very disadvantageous side effects that should be avoided, for example on the statics of the heating walls, on the flow resistance, or on the flow velocities 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 carried out within a narrow tolerance range. In particular, the expert is faced with the task of not risking any weakening of the heating wall composite through new measures. Depending on the operating condition, high lateral forces can act on every wall. For example, after about 75% of the cooking time, a high lateral internal pressure (driving pressure of the coal charge) arises, especially on the rotor walls at a height of approx. 1m above the burner level, which driving pressure can even cause joints to widen and thereby create unwanted bypass flows (in Connection with coke oven gas overflows and the associated CO formation) arise between individual heating flues and (adjacent) oven chambers. The balance of the gas mixture is thereby disturbed: In particular, there is only an insufficiently large amount of air available for additional quantities of gas to be burned in the heating duct. Different filling times, for example staggered by 12 hours, also lead to different lateral forces in the respective walls of the neighboring furnace chambers. The stability of the oven is therefore a high priority when it comes to measures to reduce emissions. High stability is usually achieved through a tongue and groove arrangement of the stones. This design is also preferred in terms of tightness to avoid bypass flows and pre-combustion.

In the case of a battery with several furnace chambers, e.g. 40 or 60 furnace chambers, the furnace chambers are delimited from gas-carrying heating channels by runner walls, in particular on a relatively narrow end face of the respective channel, in particular by two opposite runner walls extending along the entire respective furnace chamber. The individual heating channels are sealed off from one another by so-called binder walls (partition walls), which extend in particular orthogonally to the two rotor walls between the rotor walls, in particular on the relatively wider side of the furnace chambers. Three truss walls separate two channels from each other or a twin heating flue from another twin heating flue. A respective heating channel is delimited by two runner wall sections and two truss walls. In the direction of expression (depth y), each heating channel is approx. 450 to 550mm long or deep (middle to middle). A runner wall thickness is, for example, in the range of 80 to 120mm. A truss wall thickness is, for example, in the range of 120 to 150mm.

The term “truss wall” has become established in common usage. In the present description, this term is used synonymously with the term "partition wall", in particular to clarify that a runner wall and a truss wall/partition wall can be made in the same construction, namely by stones lined up together on their narrow side. The "runner wall" of a horizontal chamber furnace can also be described as a longitudinal wall arranged lengthwise in the ejection direction, and the "truss wall" can also be described as a transverse (dividing) wall arranged transversely to the ejection direction.

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). At the bottom, a coke oven gas opening opens into the heating channel. With 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 system 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 level and displaceable there. Step gas channels are provided in the truss walls, which introduce combustion air (step gas) into the furnace chamber at one or more height positions (air step or truss wall opening). A common ratio of the volume flows introduced into the furnace chamber can be mentioned: 30% through the bottom-side combustion air inlet, 30% through the bottom-side mixed gas inlet, and 40% through the at least one step gas inlet (binder wall opening). This ratio can also be set analogously for the exhaust of the gases from the furnace chamber, depending on the performance requirements.

Above the exhaust gas turning point (recirculation passage), a bypass flow in the manner of a heating differential can be formed to adjust coking parameters. The bypass flow can be isolated from the heating flues via a particularly horizontal wall or ceiling, in which passages are provided in the ceiling, which can be covered, for example, by means of slide blocks or adjusted with regard to the cross section.

DE 735 312 C discloses a composite coke oven with twin heating flues and circulating current heating. AT 147 818 B reveals a coke oven system with twin heating.

The aforementioned publication by K. Wessiepe also looks in particular at measures on ovens with twin heating flues (at least heating flues coupled to one another by means of an upper passage), although it was already worked out in the 1990s that the so-called circulating flow arrangement has advantages in terms of the lowest possible NOx -Concentration can deliver.

The patent specifications can be mentioned as examples DE 34 43 976 C2 and DE 38 12 558 C2 , in which the question of an optimal circulating flow rate and a sensible height position for the staged introduction of combustion air is discussed, particularly using the example of the Koppers circulating flow furnace. It also mentions that returning flue gas to a height in the area of the heating flue base enables the temperature in the respective heating flue to be lowered, with the effect of reducing NOx emissions.

In the disclosure document CN 107033926 A from August 2017 An arrangement with twin heating flues with a stepped introduction of combustion air and with circulating flow openings is described, which are arranged on both sides of the stepped air duct.

Experiments were also carried out with a certain type of gas-conducting components or fillers 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 provided with installations in the form of permeable honeycomb bodies or honeycomb grids or spherical fills, whereby certain types of flue gas routing are also said to be advantageous in some sections. This is about improving the flow conditions in the Heating rooms, and it is also proposed to supply combustion air at different height positions.

Experiments have also been carried out with certain coatings for effectively dissipating or reflecting thermal energy from internal surfaces.

The previously described measures directly on or in the coke oven or heating flue can be referred to here as primary measures. With all measures described above, it must be noted that the ovens described here are usually operated with self-ignition (particularly 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 can be done, in particular to avoid that the combustion goes out.

Furthermore, secondary measures were tested that can be carried out downstream of the coke oven in downstream system components, for example the use of selective catalysts in the chimney (SCR or DeNOx), or the external recirculation of already evacuated flue gas from the chimney back into the coke oven. Regardless of the question 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, they are too expensive in many cases.

Furthermore, the patent application can DE 40 06 217 A1 are described, in which the combination of several measures including both measures on regenerators in the central structure of the furnace and measures for external flue gas circulation flow is described, with the aim of homogeneous heating conditions and low NOx emissions even with high furnace chambers.

Last but not least, measures of a chemical, reactive nature have also been considered, such as introducing CH4 gas or increasing the humidity by injecting water. However, the injection of water or steam is not possible at any point in the chamber, but in particular only centrally at a medium height position and has disadvantageous effects on the (silicate) materials used. Increasing the regenerative preheating temperature of gas and air is a measure that is now considered exhausted and uneconomical.

However, it currently still seems unthinkable that the requirements described above can be met, particularly with the internal, primary measures described above, whether alone or cumulatively. A reduction in NOx emissions by a factor of 2 to 5 is therefore unlikely to be possible, at least not with reasonable effort, i.e. not in an economical way.

Despite the previously expressed concerns, the present invention is aimed at optimizing coke ovens through measures directly on the coke oven or on its structural design, in particular through measures on the established heating system with heating flues at least one recirculation opening, in particular with circulating current, in particular in order to obtain the option to be able to operate the coke oven in a performance-optimized operating mode without any downstream system components. There may be great potential for improvement in this, with great advantages also for the kiln operators, and thus also with good chances for the technical concept to be implemented on the market.

The object of the invention is to provide a coke oven device and a method for operating the coke oven device, with which NOx emissions can be kept low or, in existing or new systems, can be minimized even when operating under full load, the coke oven device having an advantageously low NOx -Emission level should preferably be possible without downstream system components. In particular, it is the task to provide a coke oven device and a method for operating the coke oven device, with which the NOx emissions can be reduced by measures internally in the heating flues.

This object is achieved according to the invention by a coke oven device for producing coke by coking coal or coal mixtures, the coke oven device being set up for minimized NOx emissions through internal thermal energy or temperature compensation using the coke oven's own gases or gas streams through primary measures internally on the coke oven device , with a large number of twin heating flues, each with a heating channel that is flamed with gas or combustion air (and therefore flows upwards) and an exhaust gas-carrying heating channel that flows downwards, which heating channels are each delimited from one another in pairs by a partition or binder wall and by two opposite rotor walls from a respective one Oven chamber of the coke oven device are sealed off, the paired heating channels, in particular at both the upper and lower ends, being fluidly 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 external circuit current path, in the lower one At least one inlet from the following group is provided in the area at the bottom of the respective twin heating train: coke oven gas inlet for introducing coke oven gas into the heating channel, combustion air inlet, mixed gas inlet; wherein at least one exhaust gas recirculation passage is arranged more centrally (closer to a central longitudinal axis of the heating channel) than at least one of the inlets with respect to the width (x) of the heating channel, i.e. between the rotor walls, and flows around a central or more central flow path from at least one of the gases admitted via the inlets, with at least two of the inlets being arranged closer to the rotor walls on both sides of the coupling passages in such a way that the respective exhaust gas recirculation passage between the inlets is laterally enclosed or delimited from the inlets and there are at least three in the corresponding heating channel or form four upwardly flowing partial streams on flow paths which run at least approximately parallel to one another or at least next to one another over a height section in the height range from 0 to 1000 mm and lead to delayed mixing in this height section in such a way that complete mixing only occurs above this height section. This exhaust gas recirculation flow path is arranged more centrally than the corresponding flow paths or inflow paths of the admitted gases. The recirculation, at least at the top, takes place more centrally than the inflow via the inlets. Through this measure for the relative positioning of the recirculation, the heat distribution in the heating channel can primarily be optimized, in particular evened out, in a mirror-symmetrical manner or simultaneously in both the upward and downward flow heating channel. In particular, the respective coke oven gas inlet can be arranged in terms of flow technology and thermal energy technology in relation to at least one passage or inlet. Effect: Influencing the heat distribution and gas mixing, especially in the floor area, by means of internal gas flows, i.e. by means of internal flow technology measures. External measures are not required. The internal measures can be purely passive measures, in particular purely constructive measures. The flow conditions can adjust autonomously thanks to design measures. Last but not least, this also makes the operation of the device easier. The oven can be controlled/regulated in a similar way to the previous way. The y position of the respective inlet between opposite partition walls can preferably be at least approximately centric. It has been shown that the y position is to be chosen secondary to the x position and can be chosen largely independently of the x position, in particular according to the respective design advantages or depending on a desired inflow angle.

The respective upper passage is arranged below an optionally present heating differential, in particular in one extending in the xz plane Partition wall. Openings of a heating differential, on the other hand, are arranged in a separating bulkhead extending in the xy plane. A lower passage is not necessarily provided.

By arranging the passage(s) as centrally as possible when viewed in an xy plane, an internal, circulating current can be provided on an additional internal, circulating current path, which is flowed around on the outside (eccentrically) by at least one admitted gas or also by an external circulating current an external circuit current path.

In the event that recirculation via one or more lower passages is not to be provided, the term “circular flow” or “circular current path” can also refer to a flow that is not completely closed but, for example, only circular over 180° or 270° .

These measures in particular enable a combustion-inert and mixing-retarding intermediate layer and cooling in the bottom area, and can be carried out directly on the coke oven or on its structural design, in particular on the heating system, without the need for downstream system components. In this way, a temperature maximum between the burner level and the lowest passage can in particular be reduced. In particular, the goal can be achieved to keep a temperature difference over the entire height of the heating channel well below 50K, with an average coal batch temperature in the range of 1000°C and a maximum temperature in the range of 1050°C and in any case less than 1100°C. Using these measures, the potential for a NOx reduction in the range of 70 to 80% relative to the current level of 350 to 500ppm NOx (at 5% 02) can be realized. In particular, a level of less than 100ppm NOx (at 5% O2) can be realized. The amount of refractory material can also be reduced by up to 5%, with the same output. This technical solution is therefore also very interesting from an economic point of view. A furnace operator can operate the furnace with high output, or at high nozzle stone temperatures, with comparatively low NOx emissions.

The measures described in the present description can be applied in particular to coke ovens with chamber operating times between filling and Expressing process between 15h and 28h, or on coke ovens with a heating flue temperature or nozzle stone temperature in the range of approx. 1200 to 1350 °C.

Until now, it was common practice to arrange the corresponding recirculation opening close to the rotor wall. It was also common practice to arrange the inlets centrally on the floor. As part of the investigations to optimize NOx emissions in the context of the present invention, it has been shown that a high combustion temperature results from the fact that the coke oven gas, together with the combustion air, forms a very hot gas mixture in a lower region of the oven chamber. By positioning the inlets according to the invention, temperature peaks can be avoided. This arrangement can also be equipped with a heating differential (bypass flow) above the exhaust gas turning points (passages). Optionally, downstream system components can reduce NOx emissions even further, provided this is still economically feasible.

The heating channel can also be described as a heating shaft. The respective heating channel is delimited at the bottom by the floor, which floor is also referred to as the burner level, even if no burners are used there (self-ignition, especially at over 800 ° C).

A heating channel is a term for a very specific vertical heating flue of the two vertical heating flues of a twin heating flue. A heating flue is to be understood as any of the two vertical heating flues of a twin heating flue. In a respective operating state of the coke oven, a heating channel is either flamed upwards or flows downwards. If it is not relevant in the corresponding context of the explanations in which direction the gas flows, the term heating flue is used here instead of the term heating channel. The term heating flue can therefore refer to the heating channel that flows upwards or downwards.

A coal mixture is to be understood as a mixture mainly of different types of coal, whereby the mixture can also include, for example, at least one additive from the following group: petroleum coke, oil, types of bitumen, for example in the form of old tires, coal and coke dust, binding or coking aids such as Molasses, oil residues, cellulose-like additives, sulfite or sulfate compounds or alkalis, whereby the mixture can also contain biomass.

When referring to channels, inlets, passages or nozzles, distance information is referred to the corresponding central longitudinal axis, and in the case of masonry or walls to an interior surface, unless otherwise stated.

It has been shown that the air or gas routing according to the invention can be implemented not only in twin heating flues, but also in so-called four-pass furnaces or alternative arrangements in which the concept of fluidically coupled heating flues is taken up and multiplied in particular when the heating flues are coupled in pairs .

The introduced combustion air or heating gas is used to generate the required process heat, be it in the floor area or in specific stepped height positions.

It has been shown that the arrangement according to the invention also makes it possible to dispense with multiple staged air inlets (in particular by only providing a single gas stage), particularly for furnace chamber heights below 8m. A modification according to the invention of the position of the lower, bottom inlets makes it possible to reduce the design effort or complexity of the furnace elsewhere.

The respective partition preferably has a width (wall thickness) of 80 to 200mm, more preferably 120 to 150mm. The respective runner wall preferably has a width (wall thickness) of 80 to 120mm. This provides sufficiently strong insulation and stability.

Independently of the individual optimization measures described, at least one combustion air or staged air inlet for introducing combustion air from a staged air duct running in the partition into the heating channel in at least one combustion stage height position can be provided in the partition wall.

The lower area at the bottom of the heating flue can correspond to the burner level, or also a height range over a maximum of 2 to 3 layers of bricks of a brick oven (2 to 3 wall layers), with a height of each layer in the range of approx. 120mm. The floor area according to the definition of the present description can also extend, for example, to a height of 1200mm. The floor area is preferably defined as an area from the burner level to a height of 100 to max. 800mm above the burner level. Height information in this description refers to the burner level, i.e. to the lowest point of a respective heating channel. A lower passage is a passage that defines a lower turning point of a circulating stream or flow, particularly below an upper passage. The respective lower passage does not necessarily have to be arranged in the floor area.

According to one exemplary embodiment, all exhaust gas recirculation passages are arranged more centrally with respect to the width (x) of the heating channel than at least one of the inlets, in particular than all of the inlets. This provides a consistent, clear separation according to the type of gas flows, namely centrally guided recirculation gas and eccentrically guided newly admitted gas.

According to one embodiment, all exhaust gas recirculation passages are arranged more centrally than at least one of the inlets. This enables particularly effective decoupling from the runner walls. According to one embodiment, at least one exhaust gas recirculation passage is arranged more centrally than all of the inlets. This makes it possible to seal off the rotor walls from recirculated exhaust gas by means of a gas carpet of admitted new gas. According to one embodiment, all exhaust gas recirculation passages are arranged more centrally than all inlets. This provides a particularly effective arrangement. According to one exemplary embodiment, at least two of the inlets comprising the coke oven gas inlet are arranged on both sides of the coupling passage(s) closer to the rotor walls in such a way that the circulating current flowing from the passage(s) is arranged on a circular current path further inside, closer to the central longitudinal axis of the heating channel than an inflow path of the gases introduced via the corresponding inlets. This can in particular prevent excessive mixing of coke oven gas and combustion air or mixed gas.

According to the claimed invention, at least two of the inlets are arranged on both sides of the coupling passages closer to the rotor walls in such a way that the respective exhaust gas recirculation passage between the inlets is laterally enclosed or separated from the inlets and there are at least three or four upward-flowing ones in the corresponding heating channel Partial flows form on flow paths that are at least over a certain height section in the height range from 0 to 1000mm at least run approximately parallel to each other or at least next to each other and lead to delayed mixing in this height section, so that more complete mixing only occurs above this height section.

According to one embodiment, the respective coke oven gas inlet is arranged adjacent to the corresponding rotor wall, and/or the respective combustion air inlet is arranged opposite the coke oven gas inlet adjacent to the corresponding rotor wall. This arrangement as close as possible relative to the runner wall enables centric recirculation even in a floor area, which provides advantages in terms of homogeneous heat distribution. In particular, it has been shown that the mixing of the individual gas streams can be delayed or further shifted to a higher height position. According to one embodiment, the respective combustion air and/or mixed gas inlet is arranged adjacent to the corresponding rotor wall and the respective exhaust gas recirculation passage is arranged centrally, in particular mirror-symmetrically with respect to a central longitudinal axis in the respective heating channel. This combination of optimization measures delivers a particularly strong effect.

According to one exemplary embodiment, the respective partition wall has at least one further coupling lower and/or upper passage, which is arranged in a more central height position (more central in the z direction) closer to the height center of the heating channels than the external circulating current path and is set up to form an internal inert one Intermediate layer on a/the centric flow path between the gas and air volume flows. This allows the temperature distribution to be evened out, especially in the floor area. In particular, it has been shown that temperature peaks in specific height positions can be effectively avoided by means of additional recirculation passages, in particular without risking a weakening of the heating wall assembly. In other words: In the partition wall between the heating channels, a heat-insulating intermediate layer can be formed using gas, through which a partial volume flow of exhaust gas/flue gas can be conducted from the descending heating channel and back into the ascending heating channel, with a combustion-inert intermediate flow being created by means of the intermediate layer can be generated with a combustion-retarding effect. According to the invention, a noticeable NOx reduction effect can be achieved using just a single additional passage. Exhaust gas or a larger exhaust gas volume flow can in such a way that the local temperature is reduced and the temperature profile is evened out in width and/or height.

According to the invention, the respective partition wall can have at least one further coupling passage further up, which is arranged further inside closer to the height center of the heating channels than the external circulating current path and is set up to form an inner inert intermediate layer (acting in terms of combustion or mixing technology) between the gas and air volume flows. This enables a homogeneous temperature profile even at higher altitudes.

It has been shown that it is advantageous for the flow conditions that at least one additional exhaust gas recirculation passage (for recirculated exhaust gas volume flow through the binder wall back into the upward flow heating channel) is arranged in a height position between the stepped air inlets and the bottom-side gas inlets of the heating channel . According to the invention, an inert separating layer can be formed by internally introducing internally reused inert exhaust gas, with a heat-insulating function, with the effect of delayed, later mixing. In particular, a separating laminar layer can be formed, which prevents cross-mixing or at least shifts it slightly further up to a higher height position.

The invention is also based on the knowledge that the exhaust gas can also be guided into a middle height position of the respective heating channel, with a smaller pressure difference than at the upper and lower ends, in the sense of an exhaust gas recirculation passages further out in relation to the furthest outer internal bypass. The bypass or circulating flow located further inside and surrounded by the outer circulating flow does not affect the outer circulating flow or does not affect it noticeably, in particular due to the lower pressure difference. Nevertheless, the heat transfer or the local temperature can be influenced effectively.

In particular, it has been shown that even with one or more inner circuit flow paths, there is no risk of short-circuiting the outer circuit flow or reducing the volume flow too much. A short circuit with the external circuit current or between individual passages can be effectively avoided in particular by spacing between the passages and/or the diameter ratios are adapted to the pressure conditions in the respective furnace. The risk of a circulating flow forming in the opposite direction can also be controlled, in particular by using a flow impulse from the admitted gases.

According to one exemplary embodiment, the respective partition wall has at least one further coupling lower and/or upper exhaust gas recirculation passage, which is arranged in a central height position closer to the height center of the heating channels than the external circulating flow and is set up for an additional internal bypass circulating flow (additional recirculation ) upwards or downwards to form an inner inert intermediate layer (acting in terms of combustion or mixing technology) between the gas and air volume flows on an additional inner bypass circular flow path, the inner inert intermediate layer preferably being delimited by the outer circular current path.

According to one embodiment, the respective partition has a plurality of further coupling exhaust gas recirculation passages, which are arranged above and below at least one air stage in the partition and are set up for at least two additional bypass circuit flows further inside, closer to the height center of the heating flues than the one on the outside Circulating flow around one or more of the air stages, for forming one or more inner inert intermediate layers (acting in terms of combustion or mixing technology) between the gas and air volume flows on an additional inner bypass circuit flow path, the respective inner inert intermediate layer preferably being delimited by the outer circuit flow path . This enables a graduated influence on the flow and temperature profile in different height positions, independent of stepped air ducts.

According to the invention, cross-mixing of recirculated exhaust gases with newly introduced gases can be prevented or at least delayed, in particular thanks to primarily laminar flow conditions in at least one inert intermediate layer. Delaying the cross-mixing can be done more or less effectively depending on the flow conditions, but in particular at least in such a way that cross-mixing occurs at the earliest above that of a NOx formation zone. The energetically and economically advantageous concept of circulating current can then advantageously continue to be used be used when a very high flame temperature prevails, i.e. with strong gas heating.

According to one exemplary embodiment, the lower and optionally also the upper exhaust gas recirculation passages are formed in the height direction over at least 2 to 5, in particular over at least 3 to 4 wall layers, and / or over a maximum of 8 to 10 wall layers. This provides a good compromise between sufficient structural stability and adequate flow resistance or flow velocity of the recirculated gas. According to one exemplary embodiment, the respective lower/lowest exhaust gas recirculation passage extends over several wall layers or fireproof layers in the height direction, in particular over at least 2 to 5 wall layers. This also enables an adequate flow profile. It can also be easily integrated into an existing construction.

According to one exemplary embodiment, the inner inert intermediate layer is arranged further inside or more centrally in the x direction than the flow paths of the inflowing gases and further centrally or in a more central height position than the outer circular current path. This promotes graduated influence in the relevant height position.

According to one exemplary embodiment, the exhaust gas recirculation passages are arranged in the area of the central width (x) of the heating channel, in particular at an x distance from the central longitudinal axis of less than 30 or 20 or 10% of the width of the heating channel. This results in the advantages explained above with regard to the inert intermediate layer.

According to one embodiment, the respective lower exhaust gas recirculation passage is arranged between the respective coke oven gas inlet and the respective combustion air and/or mixed gas inlet. This enables the previously explained influence on the temperature and flow profile, particularly in the bottom area, in particular a separation of the individual gas streams.

According to an exemplary embodiment, the respective coke oven gas inlet is arranged closer than the third of the width of the heating train (x distance between opposite rotor walls) to the rotor wall, in particular at an x distance of 10 to 350 mm, in particular less than 300 mm, to an inner surface of the rotor wall, whereby the respective lower exhaust gas recirculation passage is closer than the third of the width of the heating flue to the center or to The central longitudinal axis of the heating cable is arranged, in particular at an x-distance of 30 to 300mm. This provides effective separation of the gas streams. The flow paths can run parallel without or before cross-mixing occurs.

According to one embodiment, the respective combustion air inlet and/or mixed gas inlet is arranged closer than the third of the width of the heating flue (x-distance between opposing rotor walls) to the rotor wall, and the respective lower exhaust gas recirculation passage is closer than the third of the width of the heating flue arranged towards the center of the heating cable, in particular at an x-distance of 30 to 300mm. This provides effective separation of the gas streams. The flow paths can run parallel without or before cross-mixing occurs.

It has been shown, particularly in the context of flow tests, that relocating the lower exhaust gas recirculation passages closer to the heating flue center enables separation of incoming gases and a reduction in cross-mixing. This allows targeted influence on the temperature distribution, especially in selected height positions. It has been shown that this makes it possible to set a comparatively low, homogeneous combustion temperature T2, particularly in the lower region of the furnace chamber, with a positive effect on NOx emissions.

According to a variant, the respective coke oven gas inlet is arranged closer to the corresponding rotor wall than the respective lower exhaust gas recirculation passage, in particular with its central longitudinal axis at a distance of 10 to 350 mm, in particular less than 300 mm, from an inner surface of the rotor wall. This can also provide constructive advantages.

According to one exemplary embodiment, at least one further lower exhaust gas recirculation passage or at least one further pair of lower exhaust gas recirculation passages is provided for each twin heating flue, in particular in at least one further height position above the (first) lower coupling passage, in particular below at least one stepped air inlet. This enables targeted influence on the temperature and flow profile in selected altitude positions.

According to one exemplary embodiment, there are up to five additional lower exhaust gas recirculation passages or up to five pairs of lower ones per twin heating flue between two stepped air inlets Exhaust gas recirculation passages are provided. This provides particularly great flexibility when influencing the respective height position.

According to one exemplary embodiment, at least two further pairs of lower exhaust gas recirculation passages are provided in at least two further height positions above a lowest pair of passages for each twin heating flue, in particular three to seven pairs of lower exhaust gas recirculation passages in three to seven further height positions. This provides great variability with up to seven internal circuit currents.

According to one exemplary embodiment, up to ten additional lower exhaust gas recirculation passages or up to ten pairs of lower exhaust gas recirculation passages are arranged in further height positions below the stepped air inlets for each twin heating flue. This enables the recirculated gas to be distributed in such a way that the circulating flow can form homogeneously and the gases can gradually mix with one another in the respective height position. A higher number of passages also opens up the option of geometrically adapting the passages to the desired flow condition without restricting the boundary conditions.

The term staged air is used here synonymously with the term staged gas. A stepped air duct can also carry gas unlike air.

According to one exemplary embodiment, at least one further lower exhaust gas recirculation passage or at least one further pair of lower exhaust gas recirculation passages is arranged in at least one further height position between at least two stepped air inlets for each twin heating flue. This enables optimization by combining circulating flow paths of recirculated gas and inflow paths of staged gas.

According to one exemplary embodiment, at least one further lower exhaust gas recirculation passage or at least one further pair of lower exhaust gas recirculation passages is arranged both below and above the or all staged air inlets for each twin heating flue. This provides particularly high variability.

According to one exemplary embodiment, for each twin heating flue there is at least one further lower exhaust gas recirculation passage or at least one further pair of lower exhaust gas recirculation passages in at least one further height position above or arranged by all staged air inlets. This also enables an internal circuit flow (path) that is decoupled from the gas introduced in stages.

According to one exemplary embodiment, up to five further upper exhaust gas recirculation passages or up to five further pairs of upper exhaust gas recirculation passages are arranged above the or all staged air inlets for each twin heating flue. This provides particularly high variability.

Through the measures described above, an increased residence time and a more complete burnout can be ensured, especially with a reduced CO content, and a higher and more homogeneous heat input into the furnace chamber in the vertical height direction can also be achieved. In particular, it has been shown that with an exhaust gas recirculation of more than 50% it can be ensured that the combustible gas components burn completely into exhaust gas. This allows the energy content of the medium to be better utilized, especially continuously over time. This also allows the CO content of usually 200 to 400 ppm in the exhaust gas to be further reduced.

If the exhaust gas recirculation passages are arranged above all step gas inlets, part of the hot exhaust gas can be guided into the downward flow heating channel before the reversal point, which has a positive influence on the temperature control, especially in the gas collection space above the charge. Here, temperatures usually do not exceed 800 to 820°C (soot formation, chemical quality of the raw gas). The temperature of the respective furnace chamber can also be reduced by exhaust gas being recirculated further down.

The exhaust gas recirculation passages can each be provided in pairs or individually, i.e. even if there are an odd number, for example three or five additional exhaust gas recirculation passages.

It has been shown that, depending on the design of the coke oven device, a number of between two and ten additional exhaust gas recirculation passages is advantageous.

According to one exemplary embodiment, at least two intermediate layers are provided between the individual passages. This also provides good stability. Such stabilization of the heating wall composite consisting of the runner and binder wall is advantageous in terms of stability against coal driving pressures (maximum at around 75% of the cooking cycle). Coke ovens are usually constructed in layers, with layer heights including a joint between 100 and 160mm, especially approx. 120 to 130mm. The construction theory for coke ovens teaches that as many stones as possible in a heating wall should be connected using a tongue-and-groove connection, or by means of tongue-and-groove curvature. If a large passage cross-sectional area over several layers is desirable, the heating wall composite is weakened and there is a risk of deformation and raw gas leaking out of the furnace chamber through widening joints. This can disadvantageously lead to CO formation due to insufficient quantities of combustion air in the heating duct. Therefore, high stability in the lateral (horizontal) direction is very important.

Prestressing of the heating wall in the vertical direction is also desirable in order to protect the heating wall composite from vertical bending. A tongue and groove connection is therefore preferred on the top and bottom sides of the stones. The vertical prestressing of the heating wall takes place in particular via a sufficiently large ceiling weight.

Further large loading forces on the wall composite occur, for example, when the coke charge is pushed out horizontally at the end of the cooking cycle by a steel stamp moving through the chamber and must be taken into account by a sufficiently large preload of the heating wall composite in the lateral and vertical directions. Additional passages, especially those with comparatively large cross-sectional areas, therefore require sophisticated considerations for the stability and longevity of a furnace.

According to a variant, the recirculation passages are arranged as follows: each a wall layer with a recirculation passage and above it a composite-stabilizing refractory material layer without a passage, always alternating up to, for example, a maximum of ten passages; or one wall layer with a recirculation passage and above it two bond-stabilizing refractory material layers without a passage and then a wall layer with a recirculation passage and above it one or two bond-stabilizing refractory material layers without a passage. This provides good stability. The passages are comparatively small, but can be easily integrated into the design of the oven.

According to an exemplary embodiment, at least one, in particular centrally arranged, step air duct with at least one step air inlet is formed in the partition, in particular with at least one step air inlet above at least one recirculation passage. This opens up further possibilities for influencing the flow and temperature profile.

According to an exemplary embodiment, at least two staged air channels, in particular arranged in parallel, are formed in the (respective) partition, which unite above the upper/topmost exhaust gas recirculation passage and open into the flamed heating channel in a topmost staged air inlet above all the exhaust gas recirculation passages. This also enables, for example, an optimization of the temperature and flow profiles by means of gas introduced in stages at different width positions or (x) positions. The combined passage can be easily adjusted from above on the ceiling using an adjusting element or slider.

According to one exemplary embodiment, at least two step air channels, in particular arranged in parallel, are formed in at least one of the partition walls, which open into the flamed heating channel above the upper/top exhaust gas recirculation passage in two top step air inlets above all exhaust gas recirculation passages. As a result, the gas introduced in stages can be introduced into the heating channel homogeneously across the width (x-direction).

The redundant design of the staged air ducts, be it each with a separate inlet or with a common inlet, provides the advantage that the circulating flow, particularly in the lower area of the heating duct, can be moved to the center as desired and can therefore be very effectively decoupled from the admitted gases. This can also result in design advantages, including cost advantages in the construction of the device, or advantages for operation. The stepped air ducts can also be relocated to the outside, so that an inert exhaust gas flow can be formed as centrally as possible (at least more centrally than the other gases) using recirculated gases. An advantageous secondary heat distribution can also be achieved. Last but not least, there are constructive advantages.

According to one exemplary embodiment, the respective lower/lowest exhaust gas recirculation passage is arranged at a distance of at least 50 mm above the lower region or above the bottom of the heating channel. In this way, a good fluidic effect can be achieved, particularly in coordination with the arrangement of the inlets. In particular, a lower edge of the lowest recirculation passage is arranged in the range 0 to 150 mm above the burner levels, above this is a stabilizing separating layer with a height of approximately 120 to 130 mm, and above this is another passage with a minimum height of, for example, approximately 120 mm, with this alternation between Passage and separation layer can extend up to a height of 800mm.

According to one embodiment, the coke oven gas inlet or the corresponding gas flue (nozzle or pipe) is arranged at a distance from the central longitudinal axis of at least 50% of the width of the heating channel. This spacing provides effective decoupling from the more centrally arranged flow paths of the recirculation gases.

According to one variant, the grading is only provided in the ascending heating channel.

According to a variant, at least three additional coupling exhaust gas recirculation passages are provided, with at least two inner additional circular flows being formed, with one exhaust gas recirculation passage being provided above and below a gas stage (outlet of a staged air duct). This enables an effective combination of measures.

According to one embodiment, the combustion air inlet and/or mixed gas inlet and/or coke oven gas inlet are at an angle of 0° with respect to the central longitudinal axis of the heating duct (or with respect to a normal to the floor or with respect to the vertical) or aligned at an angle of less than 30°, in particular less than 20° or less than 10° with respect to the vertical (z), in particular all inlets inclined or aligned in the same direction. This orientation, which is as vertically upward as possible, enables a centrally arranged flame, which provides advantages in terms of temperature distribution. As a result, the exhaust gas volume flows can flow centrally and almost vertically upwards, i.e. in the normal direction in the vertical height direction z in the heating channel, and the new, admitted gases can form a gas carpet for isolation. In contrast to a strongly inclined orientation, the volume flows do not collide with the walls. This allows the combustion to be directed towards the center of the heating channel, not the outer surfaces, which means that moderate temperatures can be set. Local temperature peaks can be effectively avoided. It has been shown that the respective inflow pulse can be used particularly advantageously for additional suction of flue gas from the unflamed heating channel or for more targeted mixing of the gases. The respective inflow pulse can be delivered to the other gases, so it does not dissipate on the walls. In contrast, the inlets in previous ovens are usually oriented obliquely at a large angle of inclination of over 30°. It has been shown that the inflow momentum of the respective gas is not used particularly effectively with this orientation, especially not for Sucking in flue gas from the unflamed heating duct. The orientation according to the invention enables particularly high recirculation rates.

According to one exemplary embodiment, the respective combustion air inlet and/or the respective mixed gas inlet and/or the respective coke oven gas inlet have a cross-sectional area of a maximum of 0.06m ² , in particular even with oven chamber heights over 6m. With this upper limit, it can be ensured that the admitted gas flows into the heating channel with a certain minimum impulse or a certain minimum speed, so that the flow conditions in the heating channel can be effectively influenced by means of the inlets. Such a comparatively small cross-sectional area allows a high injector effect to be achieved. In particular, the gases can be admitted in such a way that the circulating flow rate or the proportion of recirculated gas is increased. Through such reduced or small cross-sections, the inlet impulse of the media can also be increased in such a way that the rate of recirculated exhaust gas can be increased, in particular from approximately 30 to 45% to approximately 50 to 80% with coke oven gas heating. A high flow velocity can be set, with the effect that the volume flow of exhaust gas sucked in or entrained increases. In particular, high inflow velocities into the heating flue of greater than 2m/s can be achieved. A stable flame contour can also be ensured, which promotes delayed burnout characteristics.

According to one exemplary embodiment, the cross-sectional area of the respective lower and/or upper exhaust gas recirculation passage is greater than 0.005m ² , in particular greater than 0.01m ² . This enables a comparatively weak flow impulse of the recirculated exhaust gas, with the effect that the flow impulse of the newly admitted gas has a stronger effect. With a comparatively small newly admitted volume flow, a large effect can be achieved and a high circulating flow rate can be selected.

According to one exemplary embodiment, the cross-sectional area of the respective lower exhaust gas recirculation passage has a rectangular, elongated geometry, in particular in the width direction (x), transverse to the ejection direction. This allows for easy integration into the walls, with the option of size adjustment with minimal design effort. Likewise, the cross-sectional area of the respective upper exhaust gas recirculation passage can have a rectangular geometry, in particular in the width direction (x), transverse to the expression direction, an elongated geometry, or a square geometry.

The respective inlets and/or the respective passages can be of the same size or can be specifically adapted to each height position.

According to one exemplary embodiment, the respective exhaust gas recirculation passage has at least one rounded flow edge and/or convex curvature, in particular with a radius of at least a quarter wall layer (corresponding in degrees or millimeters) or at least 30°, in particular one on the inside with respect to the respective circular current path lying rounded flow edge or convex curvature. This makes circulating flow easier, especially when there are only small pressure differences. At the same time, an advantageous flow profile can be ensured in the upward flow heating channel.

According to one exemplary embodiment, the respective exhaust gas recirculation passage has at least one sharp flow edge and/or concave curvature, in particular with a radius of a maximum of one or two wall layers (corresponding in degrees or millimeters), in particular a sharp flow edge lying on the outside in relation to the respective circular current path or concave curvature. This can ensure that the flow flows on an optimal flow path. Gas guiding contours can be provided by means of the passages or in the passages.

According to one exemplary embodiment, the respective exhaust gas recirculation passage has at least one flow around contour with at least one radius and at least one sharp flow edge (or tear-off edge). This combined contour provides a particularly good fluidic effect and has the advantage that an additional internal circulating flow can form even at very low differential pressures. The respective radius can in particular be formed over an angle of 30 to 60°. Such flow optimization can make the arrangement of the passages more flexible, especially since even in comparatively high heating channels there can only be very small pressure differences in the range of a few Pascals (Pa). By means of the edges, a flow obstacle can be created in the passage, with the effect that the flow is only directed back into the heating channel through which the flow flows upwards.

According to one exemplary embodiment, the lower exhaust gas recirculation passages are arranged offset one above the other on both sides of a stepped air duct running in the partition, in particular in connection with a stabilizing web in the partition. This allows The flow profile can also be influenced over a larger width range (x). With regard to the horizontal, an offset between 10 and 200mm can be advantageous, especially for improved cooling effect.

According to one exemplary embodiment, at least one transfer passage is set up below the exhaust gas recirculation passage(s), in particular in a central structure above a regenerator of the coke oven device, for introducing recirculated exhaust gas on the underside of the respective heating channel at a position between the mixed gas inlet and the combustion air inlet arranged. These transfer passages have a larger flow path and are designed like a channel (round or rectangular) and can be provided in combination with the bypass openings (heating differential) described above.

According to an exemplary embodiment, at least one of the inlets in the lower region, in particular the coke oven gas inlet, comprises an inlet nozzle and opens into the heating channel at a height position of 0.0 to 0.45m, in particular 0.05 to 0.25m above the bottom of the heating channel. It has been shown that such a distance from the ground has a positive effect on the flow profile in the ground area. This design of the nozzle can be referred to as gas staging and can be advantageously combined with the other measures described here. A nozzle pipe arranged at the bottom of the heating channel preferably ends approximately 0.25m high above the channel base (burner level) and is preferably made of refractory material. The coke oven gas flows in from this pipe at a height of approx. 0.25m and mixes with the air flowing in from the ground.

An inlet nozzle for volume flow calibration can be arranged within this nozzle tube in top-heated furnaces (=side burner furnaces), preferably at its bottom at the level of the channel base/burner level. A height position of the nozzle tube of less than 500 mm or preferably less than 350 or 300 mm can also protect the nozzle arranged therein from carbon or soot caking, which reduces the flow cross section, and from high temperatures, and a loss of performance can be prevented. In sub-burner furnaces, the nozzle is located below the burner level in the battery cellar, which is operated under atmospheric conditions (no risk from high temperatures). In both types of ovens, the nozzle tube protrudes 0.05 to 0.5m, preferably 0.25m, into the heating channel, so that the gas is admitted at the same height position in bottom burner ovens as in side burners.

According to one embodiment, the inlet nozzle is aligned orthogonally to the bottom of the heating channel, in particular vertically. The further inlets are also preferably aligned at least approximately orthogonally or vertically.

The aforementioned 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 NOx emissions through internal thermal energy compensation using the coke oven's own gases through primary measures internally on the coke oven device, in particular for operating a previously described coke oven device, wherein in a respective twin heating flue with a flamed heating channel and a heating channel carrying flue gas or exhaust gas, in particular at both the upper and lower end of the heating channel, around a partition by means of at least one coupling passage, in particular by means of upper and lower coupling Passages through which an internal exhaust gas recirculation is set on an external circuit current path around the partition, with coke oven gas and/or combustion air and/or mixed gas being admitted in the lower area at the bottom of the respective twin heating flue, i.e. at least one gas from the following group: coke oven gas , combustion air, mixed gas; wherein the exhaust gas recirculation is carried out more centrally (i.e. closer to the central longitudinal axis in the xy plane) than the admitted gases on one/the circular flow path or at least one centric flow path, in particular surrounded or flowed around on both sides by the admitted gases, in particular in a circle, whereby at least two of the inlets are arranged on both sides of the coupling passages closer to the rotor walls in such a way that the respective exhaust gas recirculation passage between the inlets is laterally enclosed or separated from the inlets and at least three or four upwardly flowing partial flows form on flow paths in the corresponding heating channel, which run at least approximately parallel to one another or at least next to one another over a height section in the height range from 0 to 1000mm and lead to delayed mixing in this height section in such a way that complete mixing only occurs above this height section. This provides the previously mentioned advantages. In this case, a decoupling from the exhaust gas recirculation can be achieved in terms of flow technology and thermal energy technology using at least one of the admitted gases. By introducing at least one recirculated partial exhaust gas volume flow between the heating gas volume flow and at least one of the air partial volume flows flowing into the channel at the bottom, in particular in the bottom area of the upwardly flowing heating channel, the recirculated partial gas volume flow can be forwarded and used as an inert intermediate layer in such a way that the inert intermediate layer contains the reactances gas and Air is initially separated in the lower area of the heating duct (combustion technology decoupling) and as the flow progresses in the vertical direction further up it causes a delayed burnout characteristic. This can produce a NOx reducing effect.

According to one embodiment, in a plurality of twin heating flues, each with paired heating channels, at least one heat-insulating intermediate layer is formed from a partial volume flow of exhaust gas/flue gas from the descending heating channel in a partition between the heating channels.

According to one embodiment, at least one additional inner circuit flow is set more centrally than the admitted gases and further inside than the outer circuit flow path and bordered by the outer circuit flow path, in particular via at least one pair of additional passages at the top and bottom. It has been shown that a further internal circuit flow provided further inside can be formed when there is a pressure difference in the range of a few Pascals. The pressure difference can be well below 1 mbar, in particular in the range of less than 10 or 5 Pascals (Pa), for example 2 to 4 Pa, and the additional circulating current can still be formed.

According to one embodiment, the proportion of the exhaust gas internally recirculated on the circulating current path or paths is set to over 50%, in particular over 70%, in particular to 80%, in the case of strong gas heating or mixed gas heating. In contrast, the proportion of recirculated exhaust gas was previously a maximum of 25 to 45% for heavy gas heating or a maximum of 10 to 20% for mixed gas heating. The high recirculation rate can be achieved through optimized gas routing and enables an energy-efficient process with minimized emissions.

According to one embodiment, the strong gas heating method is carried out by essentially using coke oven gas; or wherein the method for mixed gas heating is carried out by essentially using a mixture of blast furnace gas, coke oven gas and optionally also converter gas; or wherein the process is carried out using natural gas as at least a partial replacement for coke oven gas. It has been shown that the flow concept according to the invention can be implemented in any of these operating modes.

Mixed gas is usually composed of two or three gases or gas mixtures: blast furnace gas (too large a proportion), coke oven gas (too small a proportion), and optionally also converter gas. Typically, a coke oven (particularly a composite oven) is only heated with strong gas for around 5% of its operating time per year, with a significantly higher flame temperature of over 2,000°C (high calorific value of the strong gas or coke oven gas). With mixed gas heating (Blast furnace gas), on the other hand, the flame temperature is only in the range of approx. 1,700°C. However, there are also ovens that are not operated in a network and have to be operated 100% with coke oven gas or strong gas. According to the invention, it has been shown that a comparably low NOx emission can be achieved for both strong and mixed gas heating, despite the very different flame temperatures. This provides the kiln operator with maximum flexibility in operating his kilns, more or less independent of emission regulations that may be predefined in terms of time or calendar days. In particular, the furnace operator can choose an operating mode with strong gas heating without hesitation.

Purified coke oven gas with lower calorific values between 17,000 and 19,000 kJ/Nm3 is used as strong gas, particularly in downstream system components. Strong gas usually consists of CO, H2, CH4, O2, N2, CO2 and higher hydrocarbons.

According to the invention, the circulating flow rate of the recirculated exhaust gas can be increased from the previous approx. 30 to 45% to over 50% with strong gas heating, and with mixed gas heating from the previous approx. 15 to 25% also to over 50%. This enables very effective cooling of the flame temperature in the upward-flowing heating channel with comparatively cold exhaust gas. In particular, a cooling effect in the range of at least 5 to 60 ° C can be achieved, whereby thermally formed nitrogen oxides can be minimized. Apart from that, a uniform coke quality can also be achieved, particularly thanks to a very homogeneous heat flow, and thanks to lower temperature gradients, thermal stress on the chamber walls can be minimized. The furnace can be operated at lower heating temperatures, with at least approximately the same coking rate as in furnaces previously operated at higher temperatures with higher NOx emissions.

Natural gas can also be fed in via the inlet for coke oven gas, in particular provided as LNG (liquefied natural gas). Depending on the location/origin, natural gas consists of 90 to 100% methane (CH4) and marginally other, higher hydrocarbons. Methane's low flame temperature makes methane a preferred replacement for coke oven gas (less thermal NOx is formed). However, methane/natural gas is more expensive. In addition, the purified coke oven gas produced in the factory would not find a buyer. Depending on the mode of operation, coke oven gas can be at least partially replaced by natural gas. The effects of the present invention can also be achieved using natural gas.

According to one embodiment, a substoichiometric combustion ratio of <0.9 is set, in particular a combustion ratio in the range from 0.5 to 0.8, in particular 0.7, in particular in the bottom area in the burner plane at the bottom of the respective heating channel. The smaller the excess air (lambda) is set below the first combustion stage, the weaker the combustion or heat transfer can be set in the lower area of the heating flue. It has been shown that with air ratios in the bottom area of the heating ducts less than 0.9, especially in the range 0.5 to 0.8, the required limit values for NOx emissions can be met with a good safety factor. In the head area, the air ratio can be set independently in the range from 1.2 to 1.3.

The combustion ratio can be regulated by supplying the total amount of air from a heating wall consisting of, for example, 10 to 25 twin heating flues into the air valves in front of the entire battery. For this purpose, for example, metal sheets are placed as resistance in the inlet cross section of the respective valve in order to reduce the amount of air sucked in and thus the so-called air ratio of the entire heating wall. In addition, regulating flaps can be provided in the air valves to further influence the total quantity or the direction of partial quantities, which partial quantities flow into individual regenerator segments. For example, a first regenerator preheats the respective gas and air of the subsets flowing in at the bottom, and a second regenerator preheats subsets for staged air.

According to one embodiment, a preferably laminar intermediate layer is formed between the admitted gas and a staged air channel or gas from the staged air channel by means of the recirculated exhaust gas, in particular in a height range of 5 to 75%, preferably 15 to 50% of the height of the heating channel, in particular over a height section of 0.25 to 4m. This can make it easier to separate the gas streams.

According to one embodiment, an insulating and mixing-retarding gas carpet is formed between the respective rotor wall and the circulating current path(s) by means of the admitted gas. The laminar flow or intermediate layer can be characterized in particular by Reynolds numbers less than 2320.

According to one embodiment, the proportion of the quantities of gas introduced between a first stage, in particular at the bottom through the combustion air and mixed gas inlet, (bottom stage) and a second stage (one or more binder wall stages) is 50:50 or with an even smaller proportion of the first Level set. A higher proportion of recirculated gas can optionally lower the proportion of gas introduced at the bottom in the first stage. This enables further variations in influencing the flow profile, especially in the bottom area.

According to one embodiment, the ratio of the volume flows introduced into the heating channels is set as follows: <30% through the combustion air inlet, <30% through the mixed gas inlet, and >40% through the recirculation passages and optionally at least one staged air inlet . According to one embodiment, the volume flow introduced into the furnace chamber at the combustion air inlet and at the mixed gas inlet is set or regulated to between 45 and 55% of the volume flow introduced through the recirculation passages and optionally the at least one staged air inlet. This also enables more effective influence at different height positions. The process is carried out in particular with strong gas heating. The method with strong gas heating is preferably carried out with lean strong gas with a reduced lower calorific value in strong gas heating mode by providing a gas with a lower calorific value in the range from 14,000 to max. 17,000 kJ/Nm3 as the strong gas. This allows the flame temperature to be reduced considerably in conjunction with the measures described above, in particular by a difference of 50 to 300K.

The aforementioned object is also achieved according to the invention by a logic unit or control device set up to carry out a method described above, the volume flows introduced into the heating channels being adjusted in accordance with the conditions explained above, and/or the direction of flow in the heating flues being changed cyclically, especially every 15 to 25 minutes. This allows a very homogeneous temperature profile to be achieved even with frequent switching. The switching time is, for example, in the range of 1 to 2 minutes.

The aforementioned object is also achieved by using at least one partition with at least one positioned further inside in the width direction (x) more centrally than at least one gas inlet, in particular more centrally than all gas inlets Exhaust gas recirculation passage in a twin heating flue of a coke oven device, in particular in a previously described coke oven device. This results in the advantages mentioned above.

The aforementioned object is also achieved by using at least one partition with at least one exhaust gas recirculation passage positioned further inside in the width direction (x) more centrally than gas inlets exclusively in the half of the twin heating flues of the coke oven device facing the coke side of a coke oven device, in particular in a previously described coke oven device. This results in the advantages mentioned above.

The aforementioned object is also achieved by using at least one partition with at least two step air channels, in particular arranged in parallel, which combine above one/the uppermost exhaust gas recirculation passage and open into a flamed heating channel in a top step air inlet above all exhaust gas recirculation passages ; and/or by using at least one partition with at least two step air channels arranged in particular in parallel, which open into the flamed heating channel above one/of the upper/topmost exhaust gas recirculation passage in two top step air inlets above all exhaust gas recirculation passages, in particular in each case in a previously described one Coke oven device. This provides high variability with regard to individual optimization measures.

It has been shown that this structure can minimize the design effort. In many operating states, the coke-side half becomes hotter than the coal-side half, so that it may be sufficient to implement the measures described here in the coke-side half, for example 6 to 25, in particular in a maximum of 20 pairs of twins arranged further back in the ejection direction, i.e. each Oven chamber in approximately 6 to 25, especially in a maximum of 20 partitions.

The aforementioned object is also achieved by using a previously described coke oven device for coking coal or a coal mixture comprising at least one additive from the following group: petroleum coke, oil, types of bitumen, for example in the form of old tires, coal and coke dust, binding or coking aids such as e.g. molasses, oil residues, cellulose-like additives, sulfite or sulfate compounds or alkalis, whereby the mixture can also contain biomass.

The aforementioned object is also achieved according to the invention by using lean strong gas with a reduced lower calorific value when operating a previously described coke oven device. The lean strong gas is provided in particular by mixing blast furnace gas and strong gas.

• Hochofengas: 1.92% H2, 59.5% N2, 24.24% CO, 11.96% CO2, 2.37% H2O, mit einem unteren Heizwert von ca. 3349
• Starkgas: 54.98% H2, 0.66% 02, 5.33% N2, 5.75% CO, 1.52% CO2, 26.66% CH4, 2.74% C2H6, 2.37% H2O, mit einem unteren Heizwert von ca. 18422

In particular, the following values can be mentioned as preferred compositions in % by volume (wet state) and as lower calorific values (in KJ/m3, dry state, anhydrous) for both blast furnace gas (top gas) and strong gas (coke oven gas purified in secondary production):

• Blast furnace gas: 1.92% H2, 59.5% N2, 24.24% CO, 11.96% CO2, 2.37% H2O, with a lower calorific value of approx. 3349
• Strong gas: 54.98% H2, 0.66% 02, 5.33% N2, 5.75% CO, 1.52% CO2, 26.66% CH4, 2.74% C2H6, 2.37% H2O, with a lower calorific value of approx. 18422

In total, the percentages add up to 100% for the respective gas mixture, depending on the expert's selection. The components of the respective gas mixture add up to 100 percent. Further components, in particular higher hydrocarbons as well as NH3 and H2S, can be contained in trace amounts in the respective gas mixture, in particular less than 1.5% in each case. A tolerance of +-15% can be mentioned as a range of fluctuations for the individual components.

• Mischgas: 5.6% H2, 0.1% 02, 55.7% N2, 23.0% CO, 11.2% CO2, 1.9% CH4, 0.2% C2H6, 2.4% H2O, mit einem unteren Heizwert von ca. 4396
• Abgemagertes Starkgas: 45.1% H2, 0.6% 02, 14.4% N2, 8.9% CO, 3.3% CO2, 22.2 CH4, 2.3% C2H6, 2.4% H2O, mit einem unteren Heizwert von ca. 15910

In particular, a mixed gas or an emaciated strong gas can be mixed from the blast furnace gas and the cleaned strong gas, in particular according to the following components rounded to the first decimal place, each with a fluctuation range for the individual components of +-15% tolerance:

• Mixed gas: 5.6% H2, 0.1% 02, 55.7% N2, 23.0% CO, 11.2% CO2, 1.9% CH4, 0.2% C2H6, 2.4% H2O, with a lower calorific value of approx. 4396
• Depleted strong gas: 45.1% H2, 0.6% 02, 14.4% N2, 8.9% CO, 3.3% CO2, 22.2 CH4, 2.3% C2H6, 2.4% H2O, with a lower calorific value of approx. 15910

It has been shown that the use of lean strong gas can already enable a NOX reduction of 30 to 50 ppm (based on 7% O2 in the exhaust gas), in particular by lowering the local flame temperature to a range below 2000°C. In In combination with the measures described above, the beneficial effect of NOx reduction is further enhanced.

Further features and advantages of the invention emerge from the description of at least one exemplary embodiment based on the following figures, as well as from the figures themselves.

Fig. 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H

jeweils in schematischer Darstellung in geschnittenen Seitenansichten und Draufsichten Zwillingsheizzüge bzw. Koksöfen gemäß dem Stand der Technik;

Fig. 2, 3, 4, 5, 6, 7

jeweils in schematischer Darstellung in geschnittenen Seitenansichten in Breiten- und Tiefenrichtung Zwillingsheizzüge gemäß Ausführungsbeispielen;

Fig. 8A, 8B, 8C, 8D, 8E

jeweils in schematischer Darstellung in geschnittenen Seitenansichten und in Draufsichten Zwillingsheizzüge bzw. Koksofenvorrichtungen gemäß Ausführungsbeispielen;

Fig. 9

in schematischer Darstellung in geschnittener Seitenansicht einen Querschnitt bzw. eine Querschnittskontur eines Durchlasses in Zwillingsheizzügen gemäß Ausführungsbeispielen;

Fig. 10

ein Verfahrensschaubild bezüglich des Betreibens einer Koksofenvorrichtung gemäß Ausführungsbeispielen; und

Fig. 11, 12

jeweils in schematischer Darstellung in geschnittenen Seitenansichten Zwillingsheizzüge gemäß Ausführungsbeispielen.

This shows

Figs. 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H

each in a schematic representation in sectioned side views and top views of twin heating trains or coke ovens according to the prior art;

Fig. 2, 3, 4, 5, 6, 7

each in a schematic representation in sectioned side views in the width and depth directions of twin heating flues according to exemplary embodiments;

Figs. 8A, 8B, 8C, 8D, 8E

each in a schematic representation in sectioned side views and in top views of twin heating flues or coke oven devices according to exemplary embodiments;

Fig. 9

a schematic representation in a sectioned side view of a cross section or a cross-sectional contour of a passage in twin heating flues according to exemplary embodiments;

Fig. 10

a process diagram relating to the operation of a coke oven device according to exemplary embodiments; and

Fig. 11, 12

each in a schematic representation in sectioned side views of twin heating flues according to exemplary embodiments.

Reference numerals that are not explicitly described in relation to a single figure refer 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 are not 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 schematically illustrated (in particular only in individual heating channels), with the amounts of the respective distances or the angular orientation being defined in more detail in the description.

The Figures 1A, 1B , 1C , 1D, 1E , 1F, 1G , 1H show a coke oven 1 in the manner of a horizontal chamber oven, with several oven chambers 2, each with a coal charge. The Furnace chambers 2 have a height z2 of, for example, 6 to 8m. The furnace chambers 2 are sealed off by runner walls 3, each of which extends in a yz plane. Between two rotor walls 3, pairs of heating channels 5.1, 5.2 each form a twin heating flue 5, the inner wall 5.3 of which separates the heating space through which gases flow (free of coal) from the respective furnace chamber. The heating channels 5.1, 5.2 are operated alternately as a flamed or exhaust gas-carrying heating channel, which requires switching the flow direction and in a cycle of, for example, 20 minutes. he follows.

The paired heating channels are each separated from one another by a coupling partition (binder wall) 4, in which a coupling passage 4.4 is provided at the top and bottom, via which a circulating flow 9 of recirculated exhaust gas can be realized.

Adjacent twin heating flues are completely sealed off from each other by a partition wall 4a without any passages.

A staged air duct 4.1 is arranged in the partition walls 4, 4a, which is coupled to the heating duct via at least one combustion stage 4.2 or the corresponding inlet or outlet. The respective combustion stage 4.2 is arranged in a characterizing height position z4. For example, two or three height positions z4 are defined, into which stepped air is admitted.

The respective walls are made of stones, each of which defines a wall layer 3.1.

The x-direction indicates the width of the furnace 1, the y-direction indicates the depth (or the horizontal expression direction 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 directions with respect to the inner surfaces/inner walls. The center of each twin heating flue is not marked. It lies approximately in the center of the respective partition wall with a circular flow, in particular in the center of a centrally arranged stepped air duct. The term "centric" or "center" here refers to a center in the xy plane, and the term "center" or "center" 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 the inlets flows upwards on the wall surfaces 4.3 of the partition walls and on the inner walls of the runner walls.

The following temperatures at the coke oven 1 can be mentioned: nozzle stone temperature T1, (gas temperature T2 in the respective heating channel, and temperature T3 in the oven chamber. The present invention particularly relates to a distribution of the temperature T2 that is as homogeneous as possible.

With reference to the Figures 1F to 8E The individual gas streams are described below. The gas stream G1 indicates newly admitted or supplied heating gas or combustion air. The gas stream G1 can comprise a gas stream G1a (coke oven gas) and/or a gas stream G1b (mixed gas). The gas stream G4 characterizes 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 that are discharged from the respective heating duct or heating flue.

With reference to the Figures 1D, 1E The usual distances and relative positions of the individual inlets and passages are described below.

The distance d4 between previously known passages 4.4 in the x direction is comparatively large. The distance d5 of the coke oven gas inlet 8 to the further inlets 6, 7 in the x direction, in particular a distance between the coke oven gas inlet 8; G1a and the other admitted gas streams G1 are comparatively small. The distance d5 is smaller than the distance d4. The distance x4 of the respective passage 4.4 to the inner wall of the runner wall 3 is comparatively small (in particular, a distance of 120 to 140 mm was previously maintained between the runner wall and the outer edge of the passage). The distance x6, x8 of the inlet 6, 8 to the rotor wall 3 is comparatively large. The distance x8 is smaller than the distance x6. The distance x4 is significantly smaller than the distance x6, x8.

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

Fig. 1G shows schematically a heating differential 5.6 with individual openings 5.61, through which the gas can be redirected 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 circuit current 9.

An illustration of the middle section of the furnace arranged below the burner level 5.4 is deliberately omitted for the purpose of better clarity. The supply of gases and the regulation of the volume flows can take place in the middle section.

The Fig. 2 , 3 , 4 , 5 , 6 , 7 show the individual measures according to the invention for optimizing the temperature profile in the respective heating channel. In the Figures 8A , 8B , 8C , 8D, 8E Individual measures are further illustrated in detail.

A coke oven device 10 with oven chambers 10.2, in particular with horizontal chamber oven chambers, has a plurality of twin heating flues 13, each with a flamed heating channel 11 and a heating channel 12 carrying exhaust gas. The heating channels define with their inner wall 11.1 a heating cable for passing gases through. The individual heating channels are separated from one another by partition walls (binder wall) 14 with coupling passages 14.2 and isolating partition walls 14a without passages. At least one staged air channel 14.1 with one or more combustion stages 14.11 or inlets or outlets from/to the heating channel is provided in the partition walls 14, 14a. Runner walls 15 limit the furnace chambers and heating channels in the y direction.

Gas can flow into the respective heating channel via several inlets 16, 17, 18, in particular via a first combustion air inlet 16, in particular for coke oven gas heating, via a further combustion air inlet 17, in particular for mixed gas heating, and via a coke oven gas inlet 18 or a coke oven gas nozzle. The admitted and recirculated gas flows downwards or upwards through the respective heating channel both centrally and on the inner surfaces 14.3, 15.1 of the respective partition or rotor wall.

In Fig. 2 one of the measures according to the invention is primarily illustrated. A circular current 19 is formed by several circular currents that flow around each other on several paths. In Fig. 2 an outer circular current path 19.1 is shown, which delimits and flows around two further inner circular current paths 19.2, 19.3, the inner circular current paths 19.2, 19.3 being defined via the corresponding additional exhaust gas recirculation passages 14.2.

Fig. 2 shows an arrangement with three circular current paths 19.1, 19.2, 19.3, which run around a stepped air outlet 14.11 arranged at least approximately at half the height position in the heating duct. Staged gas G5 flows from the staged air outlet 14.11. Optionally, several staged air outlets can also be provided, in particular above the innermost circular current path 19.3. The optimization of the flow and heat profile can be carried out primarily by means of the recirculated gas G4, both in the floor area and in several height positions above.

Fig. 3 shows an arrangement with more than three circuit current paths, the number of lower passages being greater than the number of upper passages. The optimization can be carried out, particularly in the floor area, primarily by means of recirculated gas G4, without the need for a stepped inlet of stepped gas. A heating differential 5.6 is provided in the head area of the heating channel, which can be switched on, for example using slide blocks, independently of the respective circulating currents.

Fig. 4 shows an arrangement with more than three circuit current paths, with the number of lower passages being significantly larger than the number of upper passages. In particular, six lower passages (or pairs of passages) are provided in six different height positions. The lower passages are all arranged under a stepped air outlet 14.11 of a central stepped air duct. The six lower passages are provided in pairs adjacent to the stepped air duct, and the upper passages are individually provided and centrally arranged. A single central lower passage is arranged above the stepped air outlet. This arrangement results in a particularly wide central two-stream flow path from bottom to top, which is supplemented further above by staged gas and the centrally introduced recirculation gas.

With reference to the Figures 5, 6 , 7 the cross-sectional area Q14 of the respective coupling passage 14.2 on the inner surface to the heating channel is described. The cross-sectional area Q14 is arranged above a stepped air duct 14.1 Passages 14.2 is wider or more elongated than the cross-sectional area Q14 of passages 14.2 arranged laterally next to the stepped air duct 14.1.

Fig. 5 shows an arrangement with compared to Fig. 4 several central step air outlets 14.11 and with passages with different cross sections: the lower passages are at least partially elongated in the z direction, and the upper passages are elongated in the x direction. In this variant, the stepped air duct is surrounded on both sides by several lower passages, but not in pairs. The number of lower passages on one side is unequal to the number of passages on the other side. The passages stretched in the z-direction enable an advantageous relative arrangement, in particular very centrally (comparatively small distance d2), and in particular with an optimized flow profile. The comparatively large cross section Q14 of the passage shown on the right allows a strong flow effect of the admitted gas G1, especially over a large height section.

In Fig. 5 a distance d2 between an inner wall/edge of the corresponding passage 14.2 and an outer wall/edge of a stepped air duct 14.1 arranged centrally in the heating flue is shown in the x direction to one another. According to the invention, this distance d2 is very small, in particular 30 to 100mm, preferably 50 to 70mm. Particularly when the stepped air duct 14.1 is arranged centrally, the passages 14.2 can, according to the invention, be positioned as close as possible next to it in the x direction.

Fig. 6 shows an arrangement with two staged air ducts, which open separately into the heating duct at several height positions. All lower passages 14.2 below the top step air outlet are arranged centrally, in particular symmetrically with respect to the central longitudinal axis. Above the staged air inlets 14.11, two further pairs of lower passages (four passages) are arranged in a width position (x) at least approximately corresponding to the width position of the staged gas outlets 14.11. The paired passages can also be arranged at several height positions, including directly next to each other on the side.

Alternatively, the lower passages can also be designed to be narrower than the upper passage(s) and/or narrower than the uppermost lower passages. The uppermost lower passages can also be provided as single passages (not pairs) and be arranged in such a width position that step gas can flow past/along the respective passage and can mix with the recirculated gas.

Fig. 7 shows an arrangement with two staged air ducts, which, combined together, open centrally into the heating channel in a height position between individual lower passages 14.2, with additional separate staged air outlets optionally being provided in the respective staged air duct. The central stepped air inlet 14.11 extends in particular over a width which completely overlaps the lower passage above. The lower passages are arranged offset from one another in the x direction by the offset x2. The offset x2 also provides the advantage of a particularly wide, homogeneous flow (without a stronger flowing core), especially with passages 14.2 that are comparatively wide in the x direction. The circulating current can thereby be made even more homogeneous. Optionally, several upper passages can be provided. Such an offset can also occur in the in Fig. 6 shown arrangement can be provided.

In Fig. 7 an offset x2 in the x direction is illustrated. This offset between adjacent passages 14.2 is in particular 50 to 100 mm and provides the advantage of good heat distribution.

The Fig. 2 , 3 , 4 , 5 , 6 , 7 all show recirculation with full circulating current in the circuit. Optionally, the lower passage(s) can be dispensed with, especially if the measures described here are to or must be implemented independently of a full circuit flow, be it in individual twin heating flues or in the entire furnace device.

With reference to the Figures 8A , 8B , 8C , 8D, 8E The distances and relative positions of the individual inlets and passages according to the invention are described below using a further exemplary embodiment.

In Fig. 8A is shown schematically (in some heating channels) the arrangement of the inlets 16, 17, 18 opposite one another and spaced in the x direction from the central longitudinal axis as close as possible to the rotor walls 15. This arrangement can be selected for each of the heating channels or modified.

In Fig. 8B it is shown that the inlets 16, 17, 18 are arranged further outwards in the x direction than the passages 14.2. The passages are arranged at a distance d14 from one another that is smaller than the distance d15 of the inlets.

In Fig. 8C it is shown that the step gas G5 flowing in most centrally in the center is flowed around on both sides by recirculated gas G4, which is flowed around by admitted gas G1, G1a, G1b further out. The in Fig. 8C Angle α shown, in particular relating to the coke oven gas inlet 18, is set excessively large for better understanding. According to the invention, the angle α can be particularly small, in particular converge to zero or be 0°. Depending on the design of the central structure, an angle in the range of 5 to 10° can also be a rational compromise between additional constructive, technical effort and the achieved flow effect.

In the Fig. 8C The passages 14.2 shown or the stepped gas inlet 14.11 can be arranged in the arrangement, number and geometry according to the in Fig. 2 to 7 The variants discussed can be varied. In the Fig. 8C The individual gas streams G1, G1a, G4, G5 shown show how, according to the invention, a separation of the gas streams or a parallel flow can be achieved at least over a certain height section.

The distance d14 between the passages 14.2 in the x direction is comparatively small, in particular less than 50, 45, 40, 35 or 30 percent of the width (x) of the heating channel. The distance d15 of the coke oven gas inlet 18 to the further inlets 16, 17 in the x direction is comparatively large, in particular greater than 70, 75, 80 or 85 percent of the width (x) of the heating channel. The distance d15 is significantly larger than the distance d14, in particular at least 35, 40, 45, 50 or 55 percent larger. The distance x14 of the respective passage 14.2 to the inner wall of the rotor wall 3 is comparatively large, in particular greater than 35, 40 or 45 percent of the width (x) of the heating channel (for paired passages). Particularly preferably, the distance x14 is at least greater than 40 percent of the width (x) of the heating channel, especially in the floor area. The distance x16, x18 of the inlet 6, 8 to the rotor wall 15 is comparatively small, in particular less than 20, 15 or 10 percent of the width (x) of the heating channel. The distance x16, x18 is each smaller than the distance x14. In particular, the distance x14 is at least twice or at least three times as large as the distance x16, x18.

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

The in Fig. 8C , 8E illustrated inflow angle α, in particular for coke oven gas, is preferably smaller than 30°, in particular smaller than 10° in each case with respect to the z-axis. The inflow angle α can also be implemented analogously for the other inlets 17, 18.

The respective y position of the individual inlets can in particular be central.

The distances and relative positions mentioned in relation to the respective inlets and passages can also relate reciprocally to the distances and relative positions of the respective gas flow paths/circular flow paths, at least in a section upstream of a subsequent mixing with neighboring gas flows.

In Fig. 9 a passage cross-section is shown in the yz plane. The recirculated gas G4 flows through the respective lower passage 14.2 coming from above and also flows upwards again. The gas G4 flows around two rounded flow edges 14.21 and flows past two sharp flow edges 14.22. The partition 14 limits the passage at the top with a convex curvature downwards. This promotes low flow resistance. The partition 14 also limits the passage at the bottom. The circular flow, which here has a very narrow radius, can therefore flow through the passage and be redirected upwards without strong turbulence. One or more sharp edges 14.22 can limit a flow downwards. This type of flow optimization also makes it possible to achieve a major effect through the way the new gases are admitted. In particular, the recirculated gases G4 generate little or no turbulence, so that the flow profile can be effectively optimized using the inlets.

In Fig. 10 is schematically illustrated that the coke oven device 10 can have a control unit 20, set up to control/regulate one of the previously described volume flows V (t), in particular at least the volume flows G1, G1a, G1b, G4, G5, G6. Controlling and adjusting the volume flows makes it possible to influence the flow and temperature profile in the respective heating channel 11, 12. The NOx emissions can therefore also be adjusted indirectly via the volume flows.

The Fig. 11, 12 show variants of the in Fig. 5 shown embodiment. In Fig. 11 some of the lower passages arranged above the top step air outlet are formed in pairs, with a single larger, wider lower passage being provided.

In Fig. 12 Only two recirculation passages are provided between the lowest stage gas opening and the burner level, especially in a comparatively high height position greater than 500mm. This makes it possible to dispense with passages further down in the floor area.

The ones in the Fig. 2 to 12 The positions of the passages shown are shown as examples. Each inlet can be arranged and oriented independently of the other inlets. The exemplary embodiments shown can in particular also be varied by varying the arrangement of the lower passages, or by omitting individual or all lower passages.

In particular with reference to the exemplary embodiments of Figures 5, 6 , 11, 12 The arrangement and size of the passages, in particular the passages arranged above the top step air outlet and/or the passages arranged in a height position between individual step air outlets, can be varied by changing to pairs of passages. Some or all of the passages arranged in the floor area can also be dispensed with, especially if these passages are moved further upwards to a height range above 500mm. The number of stepped air outlets or height positions with steps is not limited to the variants shown.

List of reference symbols:

1

Coke oven, especially horizontal chamber oven

2

Furnace chamber with coal charge

3

Runner wall

3.1

Wall location

4

coupling partition or truss wall

4a

Isolating partition wall without passages

4.1

Duct or stepped air duct in partition

4.2

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

4.3

wall surface

4.4

Two heating channels coupling passage (or flue gas reversal point or reversal point for heating gas)

5

Twin heating flue (arrangement of two vertical heating flues in pairs)

5.1

Flamed heating channel (vertical heating cable)

5.2

Exhaust gas heating duct (vertical heating flue)

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

(Intermediate) 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, especially with a horizontal chamber oven

10.2

oven chamber

11

Flamed heating channel (vertical heating cable)

11.1

inner wall

12

Exhaust gas heating duct (vertical heating flue)

13

Twin heating flue (arrangement of two vertical heating flues in pairs)

14

Partition wall or truss wall

14a

Isolating partition wall without passages

14.1

Duct or stepped air duct in partition

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

14.21

rounded flow edge

14.22

sharp flow edge

14.3

Interior surface of the partition

15

Runner wall

15.1

Interior surface of the runner wall

16

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

17

Additional combustion air inlet or inlet for mixed gas heating

18

Coke oven gas inlet or coke oven gas nozzle

19

Circulating current

19.1

external circuit current path

19.2

(first) inner circuit current path

19.3

(further) inner circuit current path

20

Logic unit or control device

d2

Distance between an internal wall/edge of the corresponding passage 14.2 and an external wall/edge of a stepped air duct 14.1 arranged centrally in the heating flue in the x direction to one another

d4

Distance between previously known passages 4.4 of a twin heating flue in the x direction

d5

Distance of the coke oven gas inlet 8 to further inlets in the x direction, in particular distance between the coke oven gas inlet 8; G1a and the other admitted gas streams G1

d14

Distance between passages 14.2 according to the invention of a twin heating flue in the x direction

d15

Distance according to the invention of the coke oven gas inlet 16 to further inlets in the x direction, in particular between G1 and G1a

G1

Heating gas or combustion air

G1a

Coke oven gas

G1b

mixed gas

G4

Recirculation exhaust gas

G5

Stage gas or stage air from the 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/flue gas

GP5

Flow path of gas introduced in stages

M

Central longitudinal axis of the respective heating channel

Q14

Cross-sectional area of the coupling passage on the inner surface to the heating channel

T1

Nozzle stone temperature

T2

(Gas) temperature in the heating flue/heating duct

T3

Temperature in the oven chamber

V(t)

Volume flow of the respective gas flow, e.g. in m3/h

x

horizontal direction (latitude or longitude)

x2

Offset in x direction

x4

Distance of the previously known passage 4.4 to the inner wall of the runner wall 3

x6

Distance of the previously known inlet 6 to the inner wall of the rotor wall 3

x8

Distance of the previously known inlet 8 to the inner wall of the rotor wall 3

x14

Distance of the passage 14.2 according to the invention to the runner wall

x16

Distance of the inlet 16 according to the invention to the rotor wall

x18

Distance of the inlet 18 according to the invention to the rotor wall

y

Depth or horizontal expression direction

e.g

vertical direction (vertical axis)

z2

Oven chamber height

z4

Height position of a respective step air inlet/outlet

α

Inflow angle for coke oven gas in relation to the z-axis (vertical)

Claims (15)

1. Coke oven device (10) for producing coke by coking coal or coal mixtures, the coke oven device being set up for minimized nitrogen oxide emission by internal thermal energy compensation by means of coke oven gases (G1, G4, G5) by measures internal to the coke oven device, having a plurality of twin heating passes (13), each having a heating passage (11) through which gas flows and a waste gas-carrying heating passage (12) through which gas flows downwards, which heating passages are in each case delimited from one another in pairs by a partition wall (14) and are sealed off from a respective oven chamber (10.2), the paired heating ducts being fluidically separated by means of an upper coupling passage (14.2) and optionally also by means of a lower coupling passage in each case for internal exhaust gas recirculation (19) are coupled to one another on an outer circular flow path (19.1), in each case at least one inlet from the following group being provided in the lower region at the bottom (5.4) of the respective twin heating train: coke oven gas inlet (18), combustion air inlet (16), mixed gas inlet (17); at least one exhaust gas recirculation passage (14.2) is arranged more centrically with respect to the width (x) of the heating duct than at least one of the inlets (16, 17, 18) comprising the mixed gas inlet (17), and defines a more centrical flow path (GP4) around which at least one of the admitted gases (G1, G5) flows,
   characterized in that at least two of the inlets (16, 17, 18) are arranged closer to the rotor walls (15) on both sides of the coupling passages (14.2) in such a way that the respective exhaust gas recirculation passage (14.2) between the inlets (16, 17, 18) is laterally enclosed and delimited from the inlets (16, 17, 18), respectively is arranged laterally between the inlets (16, 17, 18) or delimited from the inlets (16, 17, 18), and at least three or four upwardly flowing partial flows are formed in the corresponding heating duct on flow paths which run at least approximately parallel to one another or at least next to one another at least over a height section in the height range from 0 to 1000 mm and lead to delayed mixing in this height section such that complete mixing only takes place above this height section.
2. Coke oven apparatus according to the preceding claim, wherein all exhaust gas recirculation passages (14.2) are arranged more centrally with respect to the width (x) of the heating channel than all inlets (16, 17, 18).
3. Coke oven device according to one of the preceding claims, wherein the respective combustion air inlet (16) and/or the respective mixed gas inlet (17) and/or the respective coke oven gas inlet (18) have a cross-sectional area of at most 0.06m²; and/or wherein the cross-sectional area of the respective exhaust gas recirculation passage (14.2) is larger than 0.005m², in particular larger than 0.01m²; and/or wherein the combustion air inlet (16) and/or mixed gas inlet (17) and/or coke oven gas inlet (18) are oriented at an angle (α) of 0° with respect to the central longitudinal axis of the heating duct or at an angle smaller than 30°, in particular smaller than 20° or smaller than 10°.
4. Coke oven apparatus according to one of the preceding claims, wherein the respective partition (14) comprises at least one further coupling lower and/or upper passage (14.2) which is arranged in a more central height position closer to the height center of the heating channels than the outer circular flow path (19.1) and is arranged for forming an inner inert intermediate layer on the central flow path (GP4); and/or wherein the respective partition (14) comprises at least one further lower and/or upper coupling passage (14.2) which is arranged in a more central height position closer to the height center of the heating channels than the outer circular flow path (19.1) and is arranged for an additional inner circular flow for forming an inner inert intermediate layer on an inner circular flow path (19.2, 19.3).
5. Coke oven device according to one of the preceding claims, wherein at least one in particular centrally arranged stepped air duct (14.1) with at least one stepped air inlet (14.11) is formed in the partition wall (14); or wherein at least two in particular parallel arranged stepped air ducts (14.1) are formed in the partition wall (14), which merge above the upper/topmost waste gas recirculation passage (14.2) and open in an uppermost stepped air inlet (14.11) above all exhaust gas recirculation passages (14.2) into the flamed heating duct (11); and/or wherein at least two, in particular parallel, stepped air ducts (14.1) are formed in at least one of the partition walls (14), which ducts open into the flamed heating duct (11) in two uppermost stepped air inlets (14.11) above all exhaust gas recirculation passages.
6. Coke oven device according to one of the preceding claims, wherein the respective exhaust gas recirculation passage (14.2) has at least one rounded flow edge (14.21) and/or convex curvature, in particular with a radius of at least one quarter wall layer or at least 30°, in particular a rounded flow edge or convex curvature lying inside with respect to the respective circular flow path; and/or wherein the respective exhaust gas recirculation passage has at least one sharp flow edge (14.22) and/or concave curvature, in particular with a radius of at most one or two wall layers or 120 mm, in particular a sharp flow edge or concave curvature lying on the outside with respect to the respective circular flow path; and/or wherein the respective exhaust gas recirculation passage (14.2) has at least one flow-around contour with at least one radius and at least one sharp flow edge.
7. Coke oven device according to one of the preceding claims, wherein at least one of the inlets, in particular the coke oven gas inlet (18), comprises an inlet nozzle and opens into the heating channel (11, 12) at a height position of 0.0 to 0.45m, in particular 0.05 to 0.25m above the bottom of the heating channel.
8. Process for operating a coke oven device (10) for producing coke by coking coal or coal mixtures with optimized minimized nitrogen oxide emission by internal thermal energy compensation by means of gases (G1, G4, G5) specific to the coke oven by measures internal to the coke oven device, in particular for operating a coke oven device according to one of the preceding claims, wherein in a respective twin heating train (13) of the coke oven device with a flame-bearing heating duct (11) and an exhaust gas-bearing heating duct (12) by means of at least one coupling passage (14.2) through a partition wall (14), an internal exhaust gas recirculation (19) is set on an outer circular flow path (19.1) around the partition wall, at least one gas from the following group being admitted in the lower region at the bottom (5.4) of the respective twin heating flue: Coke oven gas (G1a), combustion air (G1), mixed gas (G1b), wherein the exhaust gas recirculation (19) is guided on a/the circular flow path (19.1, 19.2, 19.3) or at least one centric flow path (GP4) in each case more centrically than the admitted gases (G1a, G1, G1b) comprising mixed gas (G1b), in particular surrounded on both sides by the admitted gases, characterized in that at least two of the inlets (16, 17, 18) are arranged closer to the rotor walls (15) on both sides of the coupling passages (14.2) in such a way that the respective exhaust gas recirculation passage (14.2) between the inlets (16, 17, 18) is laterally enclosed and delimited from the inlets (16, 17, 18), respectively is arranged closer to the rotor walls (15), in that the respective exhaust gas recirculation passage (14.2) is laterally enclosed between the inlets (16, 17, 18) or is arranged delimited from the inlets (16, 17, 18), and at least three or four upwardly flowing partial flows are formed in the corresponding heating duct on flow paths which run at least approximately parallel to one another or at least next to one another over a height section in the height range from 0 to 1000 mm and lead to delayed mixing in this height section in such a way that complete mixing only takes place above this height section.
9. Process according to the preceding process claim, wherein at least one additional inner circular flow (19.2, 19.3) is set more centrically than the admitted gases (G1) and further inwardly than the outer circular flow path (19.1) and bounded by the outer circular flow path, in particular via at least one pair of additional passages (14.2) at the top and bottom.
10. Process according to one of the preceding process claims, wherein the proportion of the exhaust gas recirculated on the circuit current path(s) (19.1, 19.2, 19.3) is set at more than 50%, in particular at more than 70%, in particular at 80%, in the case of rich gas heating or in the case of mixed gas heating; and/or wherein the process for rich gas heating is carried out by essentially using coke oven gas or by using lean rich gas with lowered lower calorific value, in particular less than 17000kJ/Nm³; or wherein the process is carried out for mixed gas heating by essentially using a mixture of blast furnace gas, coke oven gas and optionally also converter gas; or wherein the process is carried out with natural gas as at least partial substitute for coke oven gas.
11. Process according to one of the preceding process claims, wherein a substoichiometric combustion ratio of <0.9 is set, in particular a combustion ratio in the range from 0.5 to 0.8, in particular 0.7, in particular in the burner plane (5.4) at the bottom of the respective heating channel (11, 12).
12. Process according to one of the preceding process claims, wherein by means of the recirculated exhaust gas (G4) an intermediate layer is formed between admitted gas (G1) and a step air duct (14.1) or gas (G5) from the stage air duct is formed, in particular in a height range of 5 to 75% or 15 to 50% of the height of the heating duct or over a height section of 0.25 to 4m; and/or wherein a gas carpet is formed between the respective rotor wall (15) and the circular flow path(s) (19.1, 19.2, 19.3) by means of the recirculated gas (G1).
13. Process according to one of the preceding process claims, wherein the proportion of the gas quantities introduced between a first stage, in particular at the bottom (5.4) through the combustion air and mixed gas inlets (16, 17), and a second stage (z4) is set to 50:50 or with an even smaller proportion of the first stage, in particular with high gas heating; and/or wherein the ratio of the volume flows introduced into the heating ducts (11, 12) is set as follows: <30% through the combustion air inlet (16), <30% through the mixed gas inlet (17), and >40% through the recirculation passages and optionally at least one stage air inlet (14.11), in particular with strong gas heating; and/or wherein the volume flow introduced into the furnace chamber at the combustion air inlet and at the mixed gas inlet is set to between 45 and 55% of the volume flow introduced through the recirculation passages and optionally the at least one step air inlet, in particular with strong gas heating.
14. Control device (20) arranged for carrying out a method according to one of the preceding method claims, wherein the volume flows (G1, G4, G5) introduced into the heating channels (11, 12) are adjusted according to the conditions according to claim 13.
15. Use of depleted rich gas with lowered lower calorific value for operating a coke oven device according to a method according to one of the preceding method claims, in particular in a coke oven device according to one of the preceding device claims.

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