EP3904764B1 - Boiler system for treating waste gases - Google Patents

Description

The invention relates to a boiler system for the treatment of exhaust gases, in particular dust-containing exhaust gases from a melting process of electrical scrap and/or shredder light fractions, with at least one inlet opening and at least one outlet opening for the exhaust gases, the boiler system having at least one combustion chamber and at least one of the combustion chambers in the direction of flow Exhaust gases have a downstream waste heat boiler. The invention further relates to a method for treating exhaust gases with such a boiler system and a use of such a boiler system for the treatment of exhaust gases from a melting process of electrical scrap and/or shredder light fractions.

Boiler systems and methods for treating exhaust gases are basically known in practice and from the prior art in various embodiments. The exhaust gases are usually passed through a combustion chamber and a waste heat boiler. The exhaust gases cool as they flow through such boiler systems and steam can be generated using a steam generation circuit. Such boiler systems are usually connected to a melting furnace or combustion furnace from which the exhaust gases to be treated flow out. DE 196 27 758 A1 describes a high-temperature system for burning toxic pyrolysis gases and pyrolysis residues with a combustion chamber and a waste heat boiler downstream of the combustion chamber, which is annular. DE 10 2011 002 615 A1 relates to a method for treating an exhaust gas from an electric melting process and describes a device with a combustion chamber and a downstream heat exchanger. Depending on the process or procedure in which the When boiler systems are used, it is often necessary that a certain temperature and a certain residence time for the exhaust gases are maintained in the combustion chamber. This is the case, for example, when treating exhaust gases from a melting process of electrical scrap and/or shredder light fractions. However, the known boiler systems often do not make it possible to control or regulate the temperature and/or the residence time behavior of the exhaust gases in the combustion chamber depending on the application and depending on the requirements or legal requirements. Compliance with the residence time and/or temperature specifications for the combustion chamber is then only possible with great effort. With the known boiler systems or methods for treating exhaust gases, it is often difficult to optimally utilize the energy of the exhaust gases, for example to generate steam - and at the same time easily and reliably maintain the required temperature and/or the required residence time in the combustion chamber. - In this respect there is a need for improvement.

In contrast, the invention is based on the technical problem of specifying a boiler system for the treatment of exhaust gases, with which high efficiency in terms of cooling the exhaust gases and the use of energy or energy production from the exhaust gases is possible, which is nevertheless simple and space-saving and with the ever The temperature and/or the residence time or the residence time behavior in the combustion chamber can be controlled or regulated as required. Furthermore, the invention is based on the technical problem of specifying a method for treating exhaust gases with such a boiler system and the use of a boiler system for the treatment of exhaust gases from a melting process of electrical scrap and/or shredder light fractions.

• wobei die Brennkammer zumindest eine Brennstoffzugabeeinrichtung, vorzugsweise zumindest eine Brennstoffzugabeöffnung, für die Zugabe von Brennstoffen bzw. Ersatzbrennstoffen, bevorzugt von flüssigen und/oder gasförmigen Brennstoffen bzw. Ersatzbrennstoffen, aufweist
• und wobei der Abhitzekessel zumindest bereichsweise einen eckigen, insbesondere einen rechteckigen Querschnitt aufweist und wobei zwischen der Brennkammer und dem Abhitzekessel ein Querschittsübergang von rund bzw. im Wesentlichen rund nach eckig, insbesondere rechteckig, erfolgt.

To solve the technical problem, the invention teaches a boiler system Treatment of exhaust gases, in particular dust-containing exhaust gases from a melting process of electrical scrap and/or shredder light fractions, with at least one inlet opening and at least one outlet opening for the exhaust gases, the boiler system having at least one combustion chamber and at least one waste heat boiler connected downstream of the combustion chamber in the flow direction of the exhaust gases, wherein the combustion chamber wall has cooling pipe sections, the combustion chamber having at least one air addition device, preferably at least one air addition opening, for supplying combustion air into the combustion chamber, the combustion chamber being round in cross section at least in some areas, preferably over its entire length or substantially over its entire length or is essentially round,

• wherein the combustion chamber has at least one fuel addition device, preferably at least one fuel addition opening, for the addition of fuels or substitute fuels, preferably liquid and/or gaseous fuels or substitute fuels
• and wherein the waste heat boiler has a square, in particular a rectangular, cross-section at least in some areas and a cross-sectional transition from round or essentially round to square, in particular rectangular, takes place between the combustion chamber and the waste heat boiler.

The boiler system according to the invention is used to treat exhaust gases. The exhaust gases can come from a melting process, in particular from a melting process of iron and other metals and/or residues. According to a preferred embodiment, the boiler system according to the invention is used for the treatment of dust-containing exhaust gases from a melting process of electrical scrap and/or Shredder light fractions used.

The electronic waste is in particular old electrical devices or their components. Shredder light fractions are, in particular, residues from shredding processes in shredder systems, for example from old vehicles, household appliances, construction scrap and the like. The electronic scrap and/or the shredder light fractions usually contain iron and/or other residual metals and/or plastics and/or glass and similar components. It is possible for additional iron or other metals to be added to the electronic scrap and/or the shredder light fractions for the melting process. The electronic scrap and/or the shredder light fractions are expediently melted in a melting furnace.

Hot and dust-containing exhaust gases preferably flow from the melting furnace through the at least one inlet opening into the combustion chamber, flow through the combustion chamber and the at least one waste heat boiler connected downstream of the combustion chamber and then exit the boiler system again through the at least one outlet opening. In this context, flow direction of the exhaust gases means in particular the direction of movement of the exhaust gases from the inlet opening to the outlet opening of the boiler system. Preferably, the inlet opening is arranged on the combustion chamber and preferably forms the entrance to the combustion chamber. The outlet opening is expediently arranged on the waste heat boiler and preferably forms the outlet of the waste heat boiler.

According to the invention, the combustion chamber is formed by at least one combustion chamber wall and this combustion chamber wall has cooling pipe sections. These cooling pipe sections are preferably components of a Plurality of cooling tubes. The combustion chamber wall is preferably designed as a cooling tube wall and particularly preferably the combustion chamber is completely or essentially completely formed by a combustion chamber wall designed as a cooling tube wall. A cooling medium is guided in the cooling pipe sections or cooling pipes. This cooling medium is preferably water. According to a particularly preferred embodiment of the invention, the cooling pipe sections or cooling pipes are part of a steam generation circuit. This will be explained in more detail later.

According to the invention, the combustion chamber has at least one air addition device. The air addition device serves in particular to supply combustion air into the combustion chamber. The air addition device is preferably designed as an air addition opening, preferably as a closable air addition opening. Within the scope of the invention, the air addition device can be set up as an opening in the combustion chamber wall, as a nozzle or nozzle opening or as an air addition nozzle which has an air addition opening or the like. According to a preferred embodiment, the air addition device is at least one air addition nozzle, which has at least one air addition opening or closable air addition opening. The addition of combustion air to the combustion chamber makes it possible within the scope of the invention for the exhaust gas entering the combustion chamber, in particular the hot, dust-containing exhaust gas from a melting process of electrical scrap, and/or shredder light fractions, to be completely burned in the combustion chamber.

According to the invention, the combustion chamber is designed to be round or essentially round in cross-section at least in some areas, preferably over its entire length or essentially over its entire length. In this context, cross section of the combustion chamber means in particular the cross section transversely or perpendicular to the longitudinal extent or largest longitudinal extent of the combustion chamber. In the sections of the combustion chamber that are round or essentially round in cross section, the combustion chamber is therefore preferably cylindrical or truncated in shape and the combustion chamber wall expediently forms the cylinder jacket or the lateral surface of the truncated cone. It is within the scope of the invention that the combustion chamber is round or substantially round in cross section over at least 50%, preferably over at least 60%, preferably over at least 70%, particularly preferably over at least 80% and most preferably over at least 90% of its length is round. According to a particularly preferred embodiment of the invention, the combustion chamber is round or essentially round in cross section over its entire length or essentially over its entire length. Length of the combustion chamber here means in particular the extension of the combustion chamber from its entrance or from the inlet opening of the boiler system, which is preferably arranged on the combustion chamber, to the transition of the combustion chamber into the waste heat boiler. The combustion chamber can be composed of several cylindrical and/or frusto-conical combustion chamber sections that merge into one another. Round or essentially round cross-section preferably means a circular or oval cross-section, preferably a circular or essentially circular cross-section. The round or essentially round cross-sectional design of the combustion chamber is based on the knowledge that efficient cooling and energetic use of the exhaust gases is possible, which at the same time can be controlled easily and reliably. The round or essentially round cross-sectional design of the combustion chamber enables optimal mixing of the exhaust gases with the supplied combustion air and, in addition, undesirable creeping flows of the exhaust gases can be prevented.

According to the invention, the combustion chamber has at least one fuel addition device, preferably at least one fuel addition opening for the addition of fuels or substitute fuels. Load fluctuations can preferably be compensated for by adding fuels or substitute fuels. Such load fluctuations occur in particular when the furnace load has largely been burned and the exhaust gas quantity and/or exhaust gas temperature therefore decreases. The substitute fuels are preferably liquid and/or gaseous substitute fuels. According to one embodiment, this can be natural gas. Alternatively or additionally, waste materials can be introduced into the combustion chamber as substitute fuel by the fuel addition device.

According to a preferred embodiment of the invention, the fuel addition device is designed in the form of at least one fuel addition opening in the combustion chamber wall, through which the fuels or substitute fuels can enter the combustion chamber. The fuel addition device or fuel addition opening is preferably set up in such a way that at least one addition lance can be introduced into the combustion chamber through it, with which the fuel or substitute fuel is then supplied to the combustion chamber. It is within the scope of the invention that the fuel addition device is at least one fuel addition nozzle which has at least one fuel addition opening or closable fuel addition opening.

According to a particularly preferred embodiment of the invention, at least one combined air addition and fuel addition connection is provided, which serves as an air addition device and as a fuel addition device, in particular with at least one combined air addition and fuel addition opening is trained. Through such a combined addition nozzle, at least one addition lance for at least one fuel or substitute fuel can be introduced into the combustion chamber, and air or combustion air can flow into the combustion chamber. It is possible for several combined air addition and fuel addition ports to be arranged on the combustion chamber or combustion chamber wall. The preferred embodiment of the combustion chamber with at least one fuel addition device for the addition of fuels or substitute fuels is based on the knowledge that load fluctuations can be effectively compensated for by adding the fuels or substitute fuels. Depending on the requirements of the process or method, fuel or substitute fuel can be fed into the combustion chamber and in this way the load fluctuations can be compensated for. Furthermore, the addition of fuels or substitute fuels can be used to control or regulate the temperature and/or the residence time or the residence time behavior of the exhaust gases in the combustion chamber.

According to a particularly preferred embodiment of the invention, at least one burner is arranged in the combustion chamber. Preferably, several burners are arranged within the combustion chamber, which can particularly preferably be switched on depending on the fuels or substitute fuels used to burn the substitute fuels.

A recommended embodiment of the boiler system according to the invention is characterized in that the inside of the combustion chamber or the combustion chamber wall is lined at least in areas with at least one fireproof material. The inside of the combustion chamber or the combustion chamber wall is expediently over at least 50%, preferably over at least 65%, particularly preferably over at least 80% of its length. very particularly preferably lined with a fireproof material over its entire length or essentially over its entire length. It is within the scope of the invention that the refractory material is a ceramic material. The refractory material can be applied, in particular in the form of plates and/or as a coating compound and/or as a ramming compound, to the inside of the combustion chamber or the combustion chamber wall. The fireproof material is preferably a fireproof ramming mass.

According to the invention, the combustion chamber wall has cooling pipe sections. These cooling pipe sections are preferably part of a plurality of cooling pipes. According to a particularly preferred embodiment of the invention, the combustion chamber wall or the cooling pipe sections of the combustion chamber wall are designed, at least in some areas, as a membrane wall. It is recommended that the combustion chamber or the combustion chamber wall over at least 50% of its length, preferably over at least 65% of its length, preferably over at least 80% of its length, particularly preferably over at least 90% of its length, very particularly preferably over its entire length or is designed as a membrane wall essentially over its entire length. It is recommended that the combustion chamber wall is a membrane wall. In this context, membrane wall means in particular a wall made of mutually adjacent cooling tubes, each of which is connected to one another via a web, so that a closed combustion chamber wall is formed.

It is within the scope of the invention that the combustion chamber has a dwell section. The dwell section of the combustion chamber preferably forms an end section of the combustion chamber in the direction of flow of the exhaust gases. The dwell section of the combustion chamber is expediently designed with a membrane wall as a combustion chamber wall. But it is also within the scope of the invention that the residence section of the combustion chamber has a Wall without cooling pipes or without cooling pipe sections. The residence section of the combustion chamber serves in particular to extend the distance through which the exhaust gases flow within the combustion chamber and in this way in particular to increase the residence time of the exhaust gases in the combustion chamber or to control or regulate the residence time behavior of the exhaust gases. This embodiment is based on the knowledge that the required or legally required residence time of the exhaust gases in the combustion chamber can be guaranteed or maintained by the residence section or the resulting residence section, which preferably forms an end section of the combustion chamber.

The requirements for the residence time or the residence time behavior of the exhaust gases and/or the temperature in the combustion chamber can vary depending on the process or method. Typically, the required or legally required residence time can be around two seconds. The legally required temperature that must prevail in the combustion chamber for this residence time can be around 1100 °C. The special design of the combustion chamber according to the invention makes it possible to effectively adapt the residence time and/or the temperature to the requirements and at the same time to use the exhaust gases extremely efficiently to generate energy, in particular to generate steam.

A particularly preferred embodiment of the boiler system according to the invention is characterized in that the waste heat boiler has at least one boiler empty draft part. It is within the scope of the invention that the boiler empty draft part of the waste heat boiler is arranged immediately after the combustion chamber in the direction of flow of the exhaust gases. The boiler empty train part expediently has at least one, preferably at least two boiler empty trains, which are preferably separated from one another by a partition are. It is within the scope of the invention that the waste heat boiler has at least one convection part. It is recommended that the convection part has at least one convection train, preferably at least two convection trains. In the context of the invention, the term draft refers in particular to a boiler part or boiler section through which the exhaust gases flow essentially without changing direction.

According to a preferred embodiment of the invention, the waste heat boiler comprises at least one boiler empty draft part and at least one convection part. It is within the scope of the invention that a boiler empty draft part of the waste heat boiler follows immediately after the combustion chamber in the flow direction of the exhaust gases and that a convection part of the waste heat boiler follows in the flow direction of the exhaust gases after the boiler empty draft part. In the context of such an embodiment, the exhaust gases emerging from a furnace or melting furnace first flow through the combustion chamber, then the boiler empty draft part of the waste heat boiler and finally the convection part of the waste heat boiler. This configuration of the boiler system according to the invention makes it possible, in particular, for the required or legally required residence time and/or the temperature to be maintained in the combustion chamber and then for rapid heat reduction of the exhaust gases to take place in the boiler empty draft part and/or in the convection part of the waste heat boiler, The heat of the exhaust gases can be used to effectively generate steam.

According to the invention, the waste heat boiler has, at least in some areas, an angular, in particular a rectangular, cross-section. In this context, cross section of the waste heat boiler means in particular the cross section of the waste heat boiler transversely or perpendicular to its longitudinal extent or largest longitudinal extent. The waste heat boiler is expediently over at least 50%, preferably over at least 60%, preferably over at least 70%, particularly preferably over at least 80% and very particularly preferably over at least 90% of its length are angular or rectangular in cross section. According to a particularly preferred embodiment of the invention, the waste heat boiler is angular, in particular rectangular, in cross section over its entire length or essentially over its entire length. It is within the scope of the invention that the waste heat boiler has a square cross-section at least in some areas. In principle, other angular cross-sectional shapes, for example a hexagonal, octagonal or similar cross-section, are also within the scope of the invention. It is recommended that the boiler empty draft part and/or the convection part has an angular, in particular a rectangular, cross-section at least in some areas. The boiler empty draft part and/or the convection part is preferably designed to be angular, in particular rectangular, in cross section over its entire length or essentially over its entire length.

According to the invention, a cross-sectional transition from round or essentially round to square, in particular rectangular, takes place between the combustion chamber and the waste heat boiler. If, according to a preferred embodiment of the invention, the combustion chamber is round in cross-section over its entire length or essentially over its entire length and the waste heat boiler is angular in cross-section, in particular rectangular, at least in some areas, preferably over its entire length or essentially over its entire length is formed, a cross-sectional transition from round or essentially round to square, in particular rectangular, takes place at the transition point or in the transition area between the combustion chamber and the waste heat boiler. A corresponding transition piece can be provided for this purpose. The cross-sectional transition takes place very particularly preferably between the combustion chamber and the boiler empty draft part of the waste heat boiler.

According to an alternative embodiment of the boiler system according to the invention, the waste heat boiler has a round or essentially round cross-section at least in some areas, preferably over its entire length. In the context of such an embodiment, the boiler empty draft part and/or the convection part is expediently designed to be round or essentially round in cross-section at least in some areas, preferably completely. In this way, deformation of the components due to high internal pressure in the boiler system can be counteracted.

According to a preferred embodiment of the boiler system according to the invention, the waste heat boiler has at least one dust separation device. The dust separation device is preferably funnel-shaped. It is within the scope of the invention that the boiler empty draft part and/or the convection part of the waste heat boiler has at least one dust separation device, preferably a funnel-shaped dust separation device.

It is preferred that the walls of the waste heat boiler have cooling pipe sections and in particular are designed as a membrane wall at least in some areas. It is recommended that the walls of the empty boiler draft part are provided with cooling pipe sections and are preferably designed as a membrane wall at least in some areas, particularly preferably over the entire length or essentially over the entire length of the empty boiler draft part. The boiler empty draft part of the waste heat boiler can in particular be at least one boiler empty draft. In the context of the invention, boiler empty draft means in particular a boiler section or boiler part in which only the walls Have cooling pipe sections or are designed as a cooling pipe wall, in particular as a membrane wall, and in the interior of which otherwise preferably no further cooling pipes or essentially no further cooling pipes are arranged. In principle, a boiler empty pass can also be designed completely without cooling pipe sections.

At least two such empty boiler trains are expediently provided for the empty boiler train part. In contrast, in the convection part of the waste heat boiler, which preferably has at least one convection flue, in particular convection heating surfaces are provided which run in the interior of the convection part or the convection flue and are preferably arranged transversely to the flow direction of the exhaust gases or transversely to the longitudinal direction of the convection part. The convection heating surfaces can be, for example, cooling pipes or cooling pipe bundles. In the context of the invention, convection draft means in particular a boiler section or boiler part, in the interior of which convection heating surfaces are arranged - preferably transversely to the flow direction of the exhaust gases. Within the scope of the invention, at least two convection flues are provided as the convection part of the waste heat boiler.

In the boiler empty section of the waste heat boiler, the heat transfer from the exhaust gases to the cooling pipe sections can take place by radiation if the exhaust gas temperature is correspondingly high. It is additionally or alternatively possible for the heat transfer from the exhaust gases to the cooling pipe sections of the walls in the empty boiler draft part to take place by convection. In the convection part of the waste heat boiler, in which the temperature of the exhaust gas is preferably lower, the heat transfer from the exhaust gas to the convection heating surfaces or cooling pipes takes place essentially by convection.

According to one embodiment of the invention, a boiler empty pass or additional boiler empty pass is arranged to redirect the exhaust gas flow between two convection flues, so that the exhaust gas flows through the convection flues from top to bottom.

It is within the scope of the invention that the combustion chamber runs predominantly in the height direction. The exhaust gases entering the combustion chamber therefore preferably flow predominantly in the height direction in the combustion chamber. Height direction here means in particular vertical and/or obliquely to the surface of the boiler system. It is within the scope of the invention that the combustion chamber has sections whose longitudinal axis is arranged vertically to the ground and/or has sections whose longitudinal axis is arranged obliquely to the ground. It is also within the scope of the invention that the waste heat boiler is at least a vertical boiler, the longitudinal axis of which is arranged vertically or essentially vertically, in particular vertically to the base of the boiler system, and through which the exhaust gas flows vertically or essentially vertically. Preferably, the boiler empty draft part and/or the convection part of the waste heat boiler is at least a vertical boiler or a vertical draft. According to a particularly preferred embodiment of the invention, the combustion chamber runs predominantly in the vertical direction and the waste heat boiler connected downstream of the combustion chamber in the direction of flow of the exhaust gases is designed as a vertical boiler with several vertical flues. The boiler empty draft part of the waste heat boiler expediently has at least one, preferably at least two vertical boiler empty flues and/or the convection part of the waste heat boiler has at least one, preferably at least two vertical convection flues. As part of such an embodiment, the dust separation devices preferably provided are in the lower region of the boiler empty flue part and/or the convection part and in particular in the lower region of the boiler empty flue and/or the convection trains. In this context, the lower area means in particular the area of the waste heat boiler facing the subsoil. In principle, it is also within the scope of the invention that the boiler empty draft part and/or the convection part are designed as horizontal boilers or horizontal drafts, the longitudinal axis of which is arranged horizontally or essentially horizontally and which is horizontally or essentially horizontally separated from the boiler in its longitudinal direction Exhaust gas flows through. According to a further embodiment of the invention, the empty boiler part of the waste heat boiler is designed as at least one vertical boiler or vertical pass and the convection part of the waste heat boiler is designed as at least one horizontal boiler or horizontal pass.

According to the recommended embodiment, the cooling pipe sections are part of a steam generation circuit, which is preferably set up in such a way that steam can be generated in natural circulation and/or in forced circulation with the boiler system. The cooling tube sections are expediently part of a plurality of cooling tubes, which preferably form a cooling tube wall, for example a membrane wall. The cooling medium is preferably supplied to the cooling pipe sections or cooling pipes via at least one feed line. The cooling medium heated in the boiler system, in particular in the combustion chamber and/or the waste heat boiler, is recommended to be removed again via at least one return line. The boiler system or the steam generation circuit of the boiler system expediently has at least one steam drum or an upper steam drum. If the boiler system is operated in natural circulation, the cooling medium or the steam generated is circulated in particular by convection. If the boiler system is operated in forced circulation, at least one circulation pump is provided for forced circulation of the cooling medium or the steam generated. It is within the scope of the invention that the boiler system is set up in such a way that a combination of natural circulation and forced circulation is possible. According to one embodiment of the boiler system according to the invention, the steam generation circuit is set up so that saturated steam and/or superheated steam can be generated.

• Einleitung von Abgasen in die Brennkammer,
• Vollständige bzw. im Wesentlichen vollständige Verbrennung der Abgase unter Zugabe von Verbrennungsluft in der Brennkammer,
• Einleitung der Abgase in den Abhitzekessel zur weiteren Abkühlung der Abgase,

wobei während der Durchströmung der Brennkammer und/oder des Abhitzekessels durch die Abgase durch Wechselwirkung der Abgase mit den Kühlrohrabschnitten Dampf erzeugt wird und wobei der Brennkammer, insbesondere durch die Brennstoffzugabeeinrichtung, Brennstoffe bzw. Ersatzbrennstoffe zugeführt werden, die vorzugsweise zum Ausgleich von Lastschwankungen in der Brennkammer verbrannt bzw. mitverbrannt werden.To solve the technical problem, the invention further teaches a method for treating exhaust gases - in particular dust-containing exhaust gases from a melting process of electrical scrap and / or shredder light fractions - with a boiler system described above, comprising the following steps:

• Introduction of exhaust gases into the combustion chamber,
• Complete or essentially complete combustion of the exhaust gases with the addition of combustion air in the combustion chamber,
• Introducing the exhaust gases into the waste heat boiler for further cooling of the exhaust gases,

wherein during the flow through the combustion chamber and / or the waste heat boiler through the exhaust gases, steam is generated by interaction of the exhaust gases with the cooling pipe sections and wherein the combustion chamber, in particular through the fuel addition device, is supplied with fuels or substitute fuels, which are preferably used to compensate for load fluctuations in the combustion chamber burned or co-burned.

According to the invention, fuels or substitute fuels are supplied to the combustion chamber, in particular through the fuel addition device, which are preferably used to compensate for load fluctuations in the combustion chamber burned or co-burned.

As part of the method according to the invention, the exhaust gases preferably flow from a melting furnace through the at least one inlet opening of the boiler system into the combustion chamber. The method according to the invention is preferably carried out as a batch process, so that the melting furnace is loaded with a certain amount of fuel, in particular electrical scrap and/or shredder light fractions, and is only loaded with new fuel after the amount of fuel has been burned. In this context, according to a preferred embodiment of the invention, fuel or substitute fuels can be supplied to the combustion chamber in order to compensate for fluctuations in the load of the melting furnace. However, it is also fundamentally within the scope of the invention for the melting furnace to be operated continuously by continuously supplying new fuel to the furnace.

The invention furthermore relates to the use of a boiler system described above for the treatment of exhaust gases from a melting process of electrical scrap and/or shredder light fractions. The boiler system according to the invention has proven particularly useful for treating the exhaust gases from a melting process of electrical scrap and/or shredder light fractions.

Finally, the invention relates to a system for the treatment of exhaust gases, in particular dust-containing exhaust gases from the combustion of electrical waste, with at least one boiler system according to the invention and at least one furnace or melting furnace connected to the boiler system.

The invention is based on the knowledge that with the boiler system according to the invention an efficient treatment of exhaust gases - in particular dust-containing exhaust gases from a melting process of electrical scrap and / or shredder light fractions - is possible and that in the combustion chamber of the boiler system according to the invention the required or legally required residence time and /or the temperature of the exhaust gas can be controlled or regulated depending on requirements. Through the fuel addition device provided according to the invention for fuels or substitute fuels, load fluctuations can be compensated for effectively and reliably and the required temperature within the combustion chamber can be ensured or maintained. The combustion chamber, according to the invention, which is round or essentially round in cross-section at least in some areas, enables very satisfactory control of the combustion processes in the combustion chamber, since the added combustion air is optimally mixed with the exhaust gases and creep flows can be almost completely avoided. In this way, the combustion chamber according to the invention simultaneously enables effective combustion, effective steam generation and optimal control of the parameters such as residence time or residence time behavior and / or temperature of the exhaust gases in the combustion chamber. The waste heat boiler, which according to the invention is connected downstream of the combustion chamber in the direction of flow of the exhaust gases and which preferably has an empty boiler draft part and a convection part, allows the exhaust gases to be cooled in a controlled manner, whereby the heat of the exhaust gases can be used efficiently to generate steam. In this respect, the boiler system according to the invention and the method for treating the exhaust gases carried out with the boiler system are characterized by both a simple and less complex structure and by high efficiency in cooling the exhaust gases and generating steam.

Fig. 1:

Ein erfindungsgemäßes Kesselsystem in einer Übersichtsdarstellung

Fig.2:

Eine Ansicht der Brennkammerwand des in Fig. 1 dargestellten Gegenstandes im Schnitt.

The invention is explained in more detail below using a drawing that only shows an exemplary embodiment. It shows schematically:

Fig. 1:

A boiler system according to the invention in an overview

Fig.2:

A view of the combustion chamber wall of the in Fig. 1 object shown in section.

The Fig. 1 shows a boiler system according to the invention for the treatment of exhaust gases, in particular dust-containing exhaust gases from a melting process of electrical scrap and/or shredder light fractions. The boiler system is preferably and in the exemplary embodiment connected to a melting furnace. According to the invention, the boiler system has at least one inlet opening 1 and at least one outlet opening 2 for the exhaust gases. The boiler system further comprises at least one combustion chamber 3 and at least one waste heat boiler 4 connected downstream of the combustion chamber 3 in the flow direction of the exhaust gases. Expediently and in the exemplary embodiment, the inlet opening 1 is arranged at the end of the combustion chamber 3 facing the furnace or connected to the furnace. It is recommended and in the exemplary embodiment that the outlet opening 2 is arranged on the waste heat boiler 4 or in the flow direction of the exhaust gases at an end section of the waste heat boiler 4. According to the invention, the combustion chamber wall 5 forming the combustion chamber 3 has cooling pipe sections 6. Appropriately and in the exemplary embodiment, the combustion chamber wall 5 is designed, at least in some areas, as a membrane wall. The cooling pipes of the membrane wall are preferably part of a steam generation circuit for generating steam using the hot exhaust gases.

The combustion chamber 3 is designed to be circular or substantially circular in cross-section at least in some areas, preferably and in the exemplary embodiment over its entire length or essentially over its entire length. Cross section here means in particular the cross section transverse or perpendicular to the longitudinal extent of the combustion chamber 3. The combustion chamber 3 is recommended and in the exemplary embodiment constructed from several, essentially cylindrical and/or truncated cone-shaped sections, in which the combustion chamber wall 5 forms the cylinder jacket or the lateral surface of the truncated cone forms.

According to the invention, the combustion chamber 3 has at least one air addition device, preferably and in the exemplary embodiment at least one air addition opening 7 for supplying combustion air into the combustion chamber 3. According to the invention and in the exemplary embodiment, the combustion chamber 3 also has at least one fuel addition device for the addition of fuels or substitute fuels. The fuels or substitute fuels are preferably liquid and/or gaseous fuels or substitute fuels. Appropriately and in the exemplary embodiment, the fuel addition device is at least one fuel addition opening 8. Recommended and in the exemplary embodiment, a combined air addition and fuel addition port 16 is arranged on the combustion chamber, which is designed as an air addition and fuel addition device and expediently and in the exemplary embodiment has at least one opening, which serves as an air addition opening 7 and is set up as a fuel addition opening 8 (see in particular Fig. 2 ). The combined nozzle 16 thus serves on the one hand as an air addition opening 7 for the flow of combustion air into the combustion chamber 3 and on the other hand as a fuel addition opening 8 for the addition of fuels or substitute fuels into the combustion chamber 3. Through the Fuel addition opening 8 or the combined nozzle 16 can expediently and in the exemplary embodiment at least one addition lance be introduced into the combustion chamber, with which the fuel or substitute fuel is supplied to the combustion chamber 3. By adding fuels or substitute fuels, load fluctuations in the furnace in particular can be compensated for and/or the temperature and the residence time or the residence time behavior of the exhaust gases in the combustion chamber can be controlled or regulated.

Within the scope of the invention and in the exemplary embodiment, at least one burner, not shown in the figures, is arranged in the combustion chamber 3. It is recommended that several burners be provided in the combustion chamber 3. The burners can in particular support the combustion of the fuels or substitute fuels and/or serve to control the temperature in the combustion chamber 3.

Appropriately and in the exemplary embodiment, the inside of the combustion chamber 3 or the combustion chamber wall 5 is at least partially lined with a fireproof material 10. This is particularly the case Fig. 2 shown. The fireproof material 10 is preferably and in the exemplary embodiment a fireproof ramming mass.

According to the recommended embodiment and in the exemplary embodiment, the combustion chamber 3 has a dwell section 11, which expediently and in the exemplary embodiment according to Fig. 1 forms an end section of the combustion chamber 3 in the flow direction of the exhaust gases. The residence section 11 of the combustion chamber 3 extends in particular the residence distance of the combustion chamber 3, so that the residence time of the exhaust gas in the combustion chamber 3 is increased.

A particularly recommended embodiment of the invention is characterized in that the waste heat boiler 4 has a boiler empty draft part 12. Appropriately and in the exemplary embodiment, the boiler empty train part 12, which is in the Fig. 1 is shown in dash-dotted lines, directly to the combustion chamber 3 in the flow direction of the exhaust gases. The boiler empty train part 12 preferably comprises and in the exemplary embodiment according to Fig. 1 two boiler empty trains 17, which are separated from each other by a partition 18. Recommended and in the exemplary embodiment, the waste heat boiler 4 also has at least one convection part 13, which is in the Fig. 1 is shown in dashed lines. The convection part 13 adjoins the boiler empty draft part 12, as recommended and in the exemplary embodiment in the direction of flow of the exhaust gases. Preferably and in the exemplary embodiment, the convection part 13 comprises two convection channels 19.

Within the scope of the invention and the exemplary embodiment, the walls of the boiler empty train part 12 have cooling pipe sections 6 at least in some areas. The boiler empty trains 17 of the boiler empty train part 12 expediently have cooling pipe sections 6 only in the area of the walls and, in particular, have no further or essentially no further cooling pipes in their interior. It is recommended that convection heating surfaces - preferably and in the exemplary embodiment cooling tube bundles - be provided in the convection channels 19 of the convection part 13, which run in the interior of the convection channels 19, preferably and in the exemplary embodiment transversely to the flow direction of the exhaust gases.

According to the invention and in the exemplary embodiment, the waste heat boiler 4 is at least partially angular in cross section, in particular rectangular. The boiler empty trains 17 are expediently Boiler empty train part 12 and the convection trains 19 of the convection part 13 of the waste heat boiler 4 are at least partially angular in cross-section, in particular rectangular in cross-section and very particularly preferred and in the exemplary embodiment are rectangular in cross-section over their entire length or essentially over their entire length. According to the invention, a cross-sectional transition takes place between the combustion chamber 3 and the waste heat boiler 4 from round or essentially round to square, in particular rectangular. Preferably and in the exemplary embodiment, this cross-sectional transition from round to square takes place at the transition between the combustion chamber 3 and the empty boiler draft part 12 of the waste heat boiler 4.

Within the scope of the invention and in the exemplary embodiment, the combustion chamber 3 runs predominantly in the height direction. It is recommended that the waste heat boiler 4 is at least a vertical boiler, the longitudinal axis of which is arranged essentially vertically and through which the exhaust gas flows vertically or essentially vertically. Appropriately and in the exemplary embodiment according to Fig. 1 the boiler empty flues 17 of the boiler empty flue part 12 are designed as vertical flues or vertical boilers and the convection flues 19 of the convection part 13 are designed as vertical flues or vertical boilers. The boiler empty flues 17 and the convection flues 19 are thus flowed through vertically or essentially vertically by the exhaust gas in the exemplary embodiment.

According to a preferred embodiment and in the exemplary embodiment, the waste heat boiler 4 has at least one dust separation device 14, which is expediently funnel-shaped in the exemplary embodiment. In the exemplary embodiment according to the figures, funnel-shaped dust separation devices 14 are on the underside of the two convection flues 19 of the convection part 13 and on the underside of the boiler empty flue part 12 arranged.

Within the scope of the invention and in the exemplary embodiment, the cooling pipe sections 6 are part of a steam generation circuit, which is preferably set up in such a way that steam can be generated in natural circulation and/or in forced circulation with the boiler system. For this purpose, the boiler system in the exemplary embodiment has a steam drum or upper steam drum 20. The steam generation circuit is in particular set up so that saturated steam and/or superheated steam can be generated.

Appropriately and in the exemplary embodiment, the boiler system according to the invention is used to treat dust-containing, hot exhaust gases from a melting process of electrical scrap and/or shredder light fractions. As part of the method according to the invention for the treatment of exhaust gases - in particular dust-containing exhaust gases from a melting process and / or shredder light fractions - the exhaust gases from the melting furnace are introduced into the combustion chamber 3 via the inlet opening 1 and there completely or essentially completely with the addition of combustion air through the Air addition device or the at least one air addition opening 7 burned. The exhaust gases are then introduced into the waste heat boiler 4 for further cooling and preferably first flow through the boiler empty draft part 12 and then the convection part 13. The exhaust gases then leave the boiler system through the outlet opening 2, which is preferably arranged in an end section of the convection part 13 in the exemplary embodiment. While the exhaust gases flow through the combustion chamber 3 and/or the waste heat boiler 4, steam is generated by the interaction of the exhaust gases with the cooling pipe sections 6. As part of the method according to the invention, 8 fuels or substitute fuels are preferably supplied through the fuel addition device or the at least one fuel addition opening supplied, which are burned or co-burned to compensate for load fluctuations in the combustion chamber 3.

Claims (14)

1. A boiler system for treating exhaust gases, in particular dust-containing exhaust gases from a melting process of electronic scrap and/or shredder light fractions, with at least one inlet opening (1) and at least one outlet opening (2) for the exhaust gases, wherein the boiler system comprises at least one combustion chamber (3) and at least one waste heat boiler (4) downstream the combustion chamber (3) in the flow direction of the exhaust gases, wherein the combustion chamber wall (5) comprises cooling tube sections (6), wherein the combustion chamber (3) comprises at least one air supply device, preferably at least one air supply opening (7), for the supply of combustion air into the combustion chamber (3), wherein the combustion chamber (3) is constituted round or essentially round in cross-section at least in some areas, preferably over its entire length or essentially over its entire length,

   wherein the combustion chamber (3) comprises at least one fuel addition device, preferably at least one fuel addition opening (8), for the addition of fuels or substitute fuels, preferably liquid and/or gaseous fuels or substitute fuels,

   and wherein the waste heat boiler (4) has at least in some areas an angular, in particular a rectangular cross-section, and wherein a cross-section transition from round or essentially round to angular, in particular rectangular, takes place between the combustion chamber (3) and the waste heat boiler (4).
2. The boiler system according to claim 1, wherein at least one burner is arranged in the combustion chamber (3).
3. The boiler system according to any one of claims 1 or 2, wherein the inside of the combustion chamber (3) or the combustion chamber wall (5) is lined at least in some areas with a refractory material (10).
4. The boiler system according to any one of claims 1 to 3, wherein the combustion chamber wall (5) or the cooling tube sections (6) of the combustion chamber wall (5) are constituted at least in some areas as a membrane wall.
5. The boiler system according to any one of claims 1 to 4, wherein the combustion chamber (3) comprises a dwell section (11), which preferably forms an end section of the combustion chamber (3) in the flow direction of the exhaust gases.
6. The boiler system according to any one of claims 1 to 5, wherein the waste heat boiler (4) comprises at least one boiler empty pass part (12).
7. The boiler system according to any one of claims 1 to 6, wherein the waste heat boiler (4) comprises at least one convection part (13).
8. The boiler system according to any one of claims 1 to 7, wherein the waste heat boiler (4) comprises at least one dust separation device (14), which is preferably constituted funnel-shaped.
9. The boiler system according to any one of claims 1 to 8, wherein the walls (15) of the waste heat boiler (4), in particular of the boiler empty pass part (12), comprise cooling tube sections (6) and are preferably constituted at least in some areas as a membrane wall.
10. The boiler system according to any one of claims 1 to 9, wherein the combustion chamber (3) runs essentially in the height direction and/or wherein the waste heat boiler (4) is at least one vertical boiler, the longitudinal axis of which is arranged essentially vertically and through which the exhaust gas flows vertically or essentially vertically.
11. The boiler system according to any one of claims 1 to 10, wherein the cooling tube sections (6) are part of a steam generation circuit, which is preferably set up such that steam can be generated in a natural circulation and/or in a forced circulation with the boiler system.
12. The boiler system according to claim 11, wherein the steam generation circuit is set up in such a way that saturated steam and/or superheated steam can be generated.
13. A method for treating exhaust gases - in particular dust-containing exhaust gases from a melting process of electronic scrap and/or shredder light fractions - with a boiler system according to any one of claims 1 to 12, comprising the following steps:

    - introduction of exhaust gases into the combustion chamber (3)

    - complete or essentially complete combustion of the exhaust gases with the addition of combustion air in the combustion chamber (3)

    - introduction of the exhaust gases into the waste heat boiler (4) for further cooling of the exhaust gases,

    wherein, while the exhaust gases flow through the combustion chamber (3) and/or the waste heat boiler (4), steam is generated by the interaction of the exhaust gases with the cooling tube sections (6),

    and wherein fuels or substitute fuels are fed to the combustion chamber (3), in particular through the fuel addition device, which are preferably burned or co-burned in the combustion chamber (3) to compensate for load fluctuations.
14. The use of a boiler system according to any one of claims 1 to 12 for the treatment of exhaust gases from a melting process of electronic scrap and/or shredder light fractions.

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