EP0459603B1 - Process and apparatus for continuous drying of wood chips, wood fibres or other bulk materials - Google Patents

Process and apparatus for continuous drying of wood chips, wood fibres or other bulk materials Download PDF

Info

Publication number
EP0459603B1
EP0459603B1 EP91250134A EP91250134A EP0459603B1 EP 0459603 B1 EP0459603 B1 EP 0459603B1 EP 91250134 A EP91250134 A EP 91250134A EP 91250134 A EP91250134 A EP 91250134A EP 0459603 B1 EP0459603 B1 EP 0459603B1
Authority
EP
European Patent Office
Prior art keywords
combustion chamber
dryer
flue gases
heat exchanger
vapour
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Revoked
Application number
EP91250134A
Other languages
German (de)
French (fr)
Other versions
EP0459603A1 (en
Inventor
Uwe Dr. Wiedmann
Peter Dr. Puppich
Herbert Dipl.-Ing. Krichel
Holger Dipl.-Ing. Zierholz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bison Werke Baehre and Greten GmbH and Co KG
Koerting Hannover GmbH
Original Assignee
Bison Werke Baehre and Greten GmbH and Co KG
Koerting Hannover GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=6407697&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=EP0459603(B1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Bison Werke Baehre and Greten GmbH and Co KG, Koerting Hannover GmbH filed Critical Bison Werke Baehre and Greten GmbH and Co KG
Priority to AT91250134T priority Critical patent/ATE97225T1/en
Publication of EP0459603A1 publication Critical patent/EP0459603A1/en
Application granted granted Critical
Publication of EP0459603B1 publication Critical patent/EP0459603B1/en
Anticipated expiration legal-status Critical
Revoked legal-status Critical Current

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/02—Circulating air or gases in closed cycles, e.g. wholly within the drying enclosure
    • F26B21/04—Circulating air or gases in closed cycles, e.g. wholly within the drying enclosure partly outside the drying enclosure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B23/00—Heating arrangements
    • F26B23/02—Heating arrangements using combustion heating
    • F26B23/022—Heating arrangements using combustion heating incinerating volatiles in the dryer exhaust gases, the produced hot gases being wholly, partly or not recycled into the drying enclosure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B2200/00—Drying processes and machines for solid materials characterised by the specific requirements of the drying good
    • F26B2200/24—Wood particles, e.g. shavings, cuttings, saw dust

Definitions

  • the invention relates to a method and a plant for the continuous drying of wood chips, wood fibers or other bulk materials, in which the heat of flue gases generated in a combustion chamber is used in a dryer charged with the material to be dried.
  • DE-A-24 61 415 discloses a drying system with a dryer heated directly by flue gases, the flue gases being generated in a combustion chamber upstream of the dryer.
  • the mixture of flue gases and vapors leaving the dryer, which is contaminated with pollutants, is cleaned by means of cyclone dusting and then divided into two partial flows.
  • One part of the stream is returned to the combustion chamber and injected into the hottest zone for the combustion of the pollutants, so that there is intensive mixing with the flue gases, which are then fed back to the dryer.
  • the other partial flow is released into the atmosphere via an exhaust pipe.
  • This method has the advantage of a reduced amount of exhaust gas, which means that fewer pollutants leave the system, but, with due regard to the legal regulations on emission limitation, it also does not manage without the additional cleaning methods described above.
  • a method and a device for drying solids contained in liquid with two independent combustion chambers is known. Part of the vapors is fed to the main combustion chamber, from which the combustion gases are led into the atmosphere.
  • the auxiliary combustion chamber which contains its own burner, is supplied with a portion of the vapors after preheating by the exhaust gases from the first combustion chamber in a heat exchanger, the combustion gases being introduced from the auxiliary combustion chamber into the dryer charged with the material to be dried.
  • oxygen-containing combustion gases are used for drying, so that there is an increased risk of explosion when drying wood chips or wood fibers.
  • the object of the invention is to provide a method and a system of the type mentioned, whereby pollutant emission limit values can be maintained with less effort than previously, which are smaller than previously prescribed, and which increases the efficiency and at the same time the Risk of explosion is reduced.
  • this object is achieved by a method according to the teaching of claim 1 and by a system according to claim 9.
  • the vapors which are polluted with pollutants but are free of flue gas, are returned to the dryer in the circuit and used as a drying agent for direct heating of the dryer.
  • the heat content required for this is obtained by indirect heating before entering the dryer. It is heated with smoke gases that are generated in a combustion chamber.
  • this combustion chamber is the 'lock' for a vapor partial flow which has to be removed from the circuit due to the mass balance to be maintained, i.e. pollutants can only leave the circuit via the combustion chamber. There they are burned and in this way provide part of the energy required to heat the circuit.
  • a further vapor partial flow can be generated after the indirect heating of the Circuit branched from this and introduced into the combustion chamber. Since this vapor partial flow is heated, it can be mixed more effectively with the flue gases. In this case, the first vapor partial flow is reduced by the volume of the second vapor partial flow due to the mass balance to be maintained in the circuit.
  • the invention is explained in more detail below using an exemplary embodiment.
  • the accompanying drawing shows a basic circuit diagram of a system for the continuous drying of wood chips, wood fibers or the like.
  • a dryer 8, a separator 10, a fan 11, one or more cyclones 12 and a recuperative heat exchanger 7 are connected together in a circuit via pipes. Design measures ensure that the leakage in this circuit is low.
  • the system also has a combustion chamber 1 with a burner 2, which is connected to the heat exchanger 7 on the flue gas side, but is not part of the circuit.
  • Supply lines for air 3, light oil or gas 4 and wood dust 5 lead to burner 2.
  • the fuels can be burned individually or in any mixture.
  • the material to be dried is entered between the heat exchanger 7 and dryer 8 via a material lock, not shown, for example a rotary valve, and a pipeline 9 into the circuit.
  • the material can also be fed directly into the entrance area of the dryer 8, which, as is customary for this application, can be a nozzle tube dryer, single-pass, multi-pass drum dryer or the like.
  • a pipeline 6 branches off in the flow direction upstream of the heat exchanger 7 to the combustion chamber 1.
  • the flue gases generated in the combustion chamber 1 are fed to the heat exchanger 7.
  • the hot vapor stream is fed to the dryer 8 for direct heating via the section of the pipeline 13 arranged between the heat exchanger 7 and the dryer 8.
  • further vapors and harmful ingredients are released from the material to be dried, which are removed from the dryer 8 together with the dried material.
  • the coarser fractions of the dried material are separated in the subsequent separator.
  • the fine fractions of the dried material remaining in the vapors are then fed together with the vapors via a blower 11 to one or more cyclones 12. This is where the fine fractions of the dried material are separated.
  • the vapors leaving the cyclone (s) 12 are contaminated with fine dust and the pollutants formed during drying. They are returned to the dryer 8 via the pipeline 13, passing through the heat exchanger 7 and being heated up. This closes the almost inert vapor cycle.
  • the cooled flue gases leaving the heat exchanger 7 are conveyed by means of a fan 15 into a filter device 16, which is designed as a dry filter in the form of a bag filter or the like, where they are cleaned.
  • This filter device can be omitted if ash-free fuel is used.
  • the flue gases are passed into a heat exchanger 17 and used there to preheat the combustion air. This is fed to the burner 2 via the pipeline 19.
  • the flue gases are passed into the atmosphere via a chimney 18.
  • the invention is not only limited to the drying of wood chips, wood fibers or the like, but also for other bulk materials, e.g. Fish meal, peat, coal, grain and sewage sludge, applicable.

Abstract

The process according to the invention, in which the heat from flue gases generated in a combustion chamber is utilised in a drier charged with the material to be dried, is characterised in that the flue gas-free vapours leaving the drier are recirculated to the drier and, upstream of the drier, heated indirectly by the flue gases leaving the combustion chamber to the temperature required for drying the material to be dried, a vapour part-stream being branched off from this circulation and taken to the combustion chamber. <??>The apparatus for carrying out the process provides that, from the cyclone or cyclones (12) used in such processes for precipitating the dry material, a pipe (13) for the vapours leads back to the drier (8), that a heat exchanger (7) for the indirect heating of the vapours by the flue gases leaving the combustion chamber (1) is arranged in the pipe (13), and that a line (6), branching off from the pipe (13) upstream of the heat exchanger (7) in the direction of flow and leading to the combustion chamber (1), is provided. This invention makes it possible, at low cost, to maintain lower pollutant emission limits than those hitherto prescribed, to improve the efficiency and at the same time to reduce the explosion risk. <IMAGE>

Description

Die Erfindung betrifft ein Verfahren und eine Anlage zur kontinuierlichen Trocknung von Holzspänen, Holzfasern oder anderen Schüttgütern, bei dem die Wärme von in einer Brennkammer erzeugten Rauchgasen in einem mit dem zu trocknenden Gut beschickten Trockner ausgenutzt wird.The invention relates to a method and a plant for the continuous drying of wood chips, wood fibers or other bulk materials, in which the heat of flue gases generated in a combustion chamber is used in a dryer charged with the material to be dried.

Es ist dabei üblich, die Rauchgase unmittelbar in den Trockner einzuleiten.It is customary to introduce the flue gases directly into the dryer.

Bei der Trocknung von Holzspänen, Holzfasern oder anderen Schüttgütern werden organische Schadstoffe freigesetzt, die neben den in den Rauchgasen und Brüden enthaltenen Feinstäuben eine Belastung der Umwelt darstellen. Die den Trockner verlassenden Abgase müssen deshalb vor ihrer Einleitung in die Atmosphäre gereinigt werden. Dies geschieht durch Entstaubung und erforderlichenfalls durch weitere, nachgeschaltete Reinigungsverfahren, wie z.B. Naßentstaubung, Elektrofilter, Tuchfilter, Kiesbettfilter, Spänebettfilter und thermische Nachverbrennung. Mit derartigen Reinigungsverfahren lassen sich zwar die Emissionen verringern, aber hierzu sind hohe Investitions- und Betriebskosten erforderlich.When wood shavings, wood fibers or other bulk materials are dried, organic pollutants are released which, in addition to the fine dust contained in the flue gases and vapors, are a burden on the environment. The exhaust gases leaving the dryer must therefore be cleaned before being discharged into the atmosphere. This is done by dedusting and, if necessary, by further, subsequent cleaning processes such as wet dedusting, electrostatic filters, cloth filters, gravel bed filters, chip bed filters and thermal afterburning. With such cleaning processes, the emissions can be reduced, but this requires high investment and operating costs.

In der DE-A-24 61 415 ist eine Trocknungsanlage mit einem direkt durch Rauchgase beheizten Trockner offenbart, wobei die Rauchgase in einer dem Trockner vorgeschalteten Brennkammer erzeugt werden. Das den Trockner verlassende, mit Schadstoffen belastete Gemisch aus Rauchgasen und Brüden wird mittels Zyklonentstaubung gereinigt und anschließend in zwei Teilströme aufgeteilt. Der eine Teilstrom wird zur Brennkammer zurückgeführt und dort zur Verbrennung der Schadstoffe in die heißeste Zone eingedüst, so daß eine intensive Durchmischung mit den Rauchgasen stattfindet, die dann wieder dem Trockner zugeführt werden. Der andere Teilstrom wird über eine Abgasleitung in die Atmosphäre abgegeben.DE-A-24 61 415 discloses a drying system with a dryer heated directly by flue gases, the flue gases being generated in a combustion chamber upstream of the dryer. The mixture of flue gases and vapors leaving the dryer, which is contaminated with pollutants, is cleaned by means of cyclone dusting and then divided into two partial flows. One part of the stream is returned to the combustion chamber and injected into the hottest zone for the combustion of the pollutants, so that there is intensive mixing with the flue gases, which are then fed back to the dryer. The other partial flow is released into the atmosphere via an exhaust pipe.

Dieses Verfahren hat den Vorteil einer verringerten Abgasmenge, wodurch weniger Schadstoffe die Anlage verlassen, kommt aber, mit Rücksicht auf die gesetzlichen Vorschriften zur Emissionsbegrenzung, auch nicht ohne die oben beschriebenen, zusätzlichen Reinigungsverfahren aus.This method has the advantage of a reduced amount of exhaust gas, which means that fewer pollutants leave the system, but, with due regard to the legal regulations on emission limitation, it also does not manage without the additional cleaning methods described above.

Aus DE-A-23 60 467 ist ein Verfahren und eine Vorrichtung zum Trocknen von in Flüssigkeit enthaltenen Feststoffen mit zwei voneinander unabhängigen Brennkammern bekannt. Dabei wird der Hauptbrennkammer ein Teil der Brüden zugeführt, aus der die Verbrennungsgase in die Atmosphäre geleitet werden. Der Nebenbrennkammer, die einen eigenen Brenner enthält, wird ein Teil der Brüden nach Vorwärmung durch die Abgase aus der ersten Brennkammer in einem Wärmetauscher zugeführt, wobei die Verbrennungsgase aus der Nebenbrennkammer in den mit dem zu trocknenden Gut beschickten Trockner eingeleitet werden. Auch hier werden also Sauerstoff enthaltende Verbrennungsgase zur Trocknung benutzt, so daß bei der Trocknung von Holzspänen oder Holzfasern eine erhöhte Explosionsgefahr besteht.From DE-A-23 60 467 a method and a device for drying solids contained in liquid with two independent combustion chambers is known. Part of the vapors is fed to the main combustion chamber, from which the combustion gases are led into the atmosphere. The auxiliary combustion chamber, which contains its own burner, is supplied with a portion of the vapors after preheating by the exhaust gases from the first combustion chamber in a heat exchanger, the combustion gases being introduced from the auxiliary combustion chamber into the dryer charged with the material to be dried. Here too, oxygen-containing combustion gases are used for drying, so that there is an increased risk of explosion when drying wood chips or wood fibers.

Aufgabe der Erfindung ist es, ein Verfahren und eine Anlage der eingangs genannten Art zu schaffen, wodurch mit geringerem Aufwand als bisher Schadstoff-Emissions-Grenzwerte eingehalten werden können, die kleiner sind als sie bisher vorgeschrieben waren, und wodurch der Wirkungsgrad erhöht und gleichzeitig die Explosionsgefahr vermindert wird.The object of the invention is to provide a method and a system of the type mentioned, whereby pollutant emission limit values can be maintained with less effort than previously, which are smaller than previously prescribed, and which increases the efficiency and at the same time the Risk of explosion is reduced.

Erfindungsgemäß wird diese Aufgabe durch ein Verfahren nach der Lehre des Patentanspruchs 1 und durch eine Anlage nach Anspruch 9 gelöst.According to the invention, this object is achieved by a method according to the teaching of claim 1 and by a system according to claim 9.

Demnach werden die den Trockner verlassenden, schadstoffbelasteten aber rauchgasfreien Brüden im Kreislauf zum Trockner zurückgeführt und als Trockenmittel zur direkten Beheizung des Trockners verwendet. Den dazu erforderlichen Wärmeinhalt erhalten sie durch indirekte Beheizung vor Eintritt in den Trockner. Beheizt wird mit Rauchgasen, die in einer Brennkammer erzeugt werden.Accordingly, the vapors, which are polluted with pollutants but are free of flue gas, are returned to the dryer in the circuit and used as a drying agent for direct heating of the dryer. The heat content required for this is obtained by indirect heating before entering the dryer. It is heated with smoke gases that are generated in a combustion chamber.

Diese Brennkammer stellt gleichzeitig die 'Schleuse' für einen Brüden-Teilstrom dar, der aufgrund der im Kreislauf einzuhaltenden Massenbilanz aus diesem abgeführt werden muß, d.h., Schadstoffe können den Kreislauf nur über die Brennkammer verlassen. Dort werden sie verbrannt und liefern auf diese Weise einen Teil der zur Aufheizung des Kreislaufs erforderlichen Energie.At the same time, this combustion chamber is the 'lock' for a vapor partial flow which has to be removed from the circuit due to the mass balance to be maintained, i.e. pollutants can only leave the circuit via the combustion chamber. There they are burned and in this way provide part of the energy required to heat the circuit.

Durch diese Lösung gelingt es, ohne die sonst erforderlichen zusätzlichen Reinigungsverfahren, die in die Atmosphäre abgegebenen Emissionen sowohl von festen als auch von gasförmigen bzw. kondensierten organischen Schadstoffen unter den Grenzwerten der gesetzlichen Vorschriften zu halten. Die zusätzlichen Investitionskosten für die indirekte Beheizung des Kreislaufs sind aufgrund des bislang unerreichten Gesamtreinigungs-Effektes kurzfristig amortisierbar. Zudem werden diese Kosten durch Einsparungen infolge vergleichsweise kleiner dimensionierter Anlagenteile, wie Trockner, Abscheider, Ventilator, Filtervorrichtung und Kamin nahezu kompensiert. Von besonderem Vorteil ist, daß der Kreislauf, in dem sich die Brüden durch den Trockner bewegen, wegen des vollständigen Ausschlusses von Rauchgasen sehr sauerstoffarm ist, so daß die Gefahr einer Explosion stark vermindert wird. Der geringe Sauerstoffgehalt wiederum ermöglicht eine nah-stöchiometrische Verbrennung, so daß eine hohe Ausnutzung des Brennstoffes erfolgt und damit ein hoher Wirkungsgrad erreichbar ist.With this solution, it is possible to keep the emissions of solid, gaseous and / or condensed organic pollutants below the limit values of the statutory regulations without the additional cleaning processes otherwise required. The additional investment costs for the indirect heating of the circuit can be amortized at short notice due to the unprecedented overall cleaning effect. In addition, these costs are almost offset by savings due to comparatively small system parts such as dryers, separators, fans, filter devices and chimneys. It is particularly advantageous that the circuit in which the vapors move through the dryer is very low in oxygen due to the complete exclusion of flue gases, so that the risk of an explosion is greatly reduced. The low oxygen content in turn enables near-stoichiometric combustion, so that the fuel is used to a high degree and a high degree of efficiency can be achieved.

Sollte das Einmischen des relativ kühlen Brüden-Teilstroms in die heiße Brennkammer Schwierigkeiten bereiten, kann ein weiterer Brüden-Teilstrom nach der indirekten Aufheizung des Kreislaufs von diesem abgezweigt und in die Brennkammer eingeleitet werden. Da dieser Brüden-Teilstrom aufgeheizt ist, läßt er sich effektiver mit den Rauchgasen vermischen. In diesem Falle wird aufgrund der im Kreislauf einzuhaltenden Massenbilanz der erste Brüden-Teilstrom um das Volumen des zweiten Brüden-Teilstroms verringert.If it is difficult to mix the relatively cool vapor partial flow into the hot combustion chamber, a further vapor partial flow can be generated after the indirect heating of the Circuit branched from this and introduced into the combustion chamber. Since this vapor partial flow is heated, it can be mixed more effectively with the flue gases. In this case, the first vapor partial flow is reduced by the volume of the second vapor partial flow due to the mass balance to be maintained in the circuit.

Andere vorteilhafte Merkmale der Erfindung gehen aus den weiteren Unteransprüchen hervor.Other advantageous features of the invention emerge from the further subclaims.

Die Erfindung wird nachstehend an einem Ausführungsbeispiel näher erläutert. Die dazugehörige Zeichnung zeigt ein Prinzip-Schaltbild einer Anlage zur kontinuierlichen Trocknung von Holzspänen, Holzfasern oder dergl.The invention is explained in more detail below using an exemplary embodiment. The accompanying drawing shows a basic circuit diagram of a system for the continuous drying of wood chips, wood fibers or the like.

In dieser Anlage sind ein Trockner 8, ein Abscheider 10, ein Ventilator 11, ein oder mehrere Zyklone 12 und ein rekuperativer Wärmeaustauscher 7 über Rohrleitungen in einem Kreislauf zusammengeschaltet. Durch konstruktive Maßnahmen wird dafür Sorge getragen, daß die Leckage in diesem Kreislauf gering ist.In this system, a dryer 8, a separator 10, a fan 11, one or more cyclones 12 and a recuperative heat exchanger 7 are connected together in a circuit via pipes. Design measures ensure that the leakage in this circuit is low.

Des weiteren weist die Anlage eine Brennkammer 1 mit einem Brenner 2 auf, die rauchgasseitig mit dem Wärmeaustauscher 7 verbunden, aber nicht Bestandteil des Kreislaufs ist. Zum Brenner 2 führen Versorgungsleitungen für Luft 3, Leichtöl oder Gas 4 und Holzstaub 5. Die Brennstoffe können einzeln oder in beliebiger Mischung verbrannt werden.The system also has a combustion chamber 1 with a burner 2, which is connected to the heat exchanger 7 on the flue gas side, but is not part of the circuit. Supply lines for air 3, light oil or gas 4 and wood dust 5 lead to burner 2. The fuels can be burned individually or in any mixture.

Das zu trocknende Gut wird zwischen Wärmeaustauscher 7 und Trockner 8 über eine nicht dargestellte Materialschleuse, beispielsweise eine Zellenradschleuse, und eine Rohrleitung 9 in den Kreislauf eingegeben. Die Zuführung des Gutes kann aber auch direkt in den Eingangsbereich des Trockners 8, der, wie für diesen Einsatzfall üblich, ein Düsenrohrtrockner, Einzug-, Mehrzug-Trommeltrockner oder dergl. sein kann, erfolgen.The material to be dried is entered between the heat exchanger 7 and dryer 8 via a material lock, not shown, for example a rotary valve, and a pipeline 9 into the circuit. The material can also be fed directly into the entrance area of the dryer 8, which, as is customary for this application, can be a nozzle tube dryer, single-pass, multi-pass drum dryer or the like.

Von der zwischen dem bzw. den Zyklonen 12 und dem Trockner 8 für die Rückführung der Brüden zum Trockner 8 angeordneten Rohrleitung 13 zweigt in Strömungsrichtung vor dem Wärmeaustauscher 7 eine Rohrleitung 6 zur Brennkammer 1 ab.From the pipeline 13 arranged between the cyclone or cyclones 12 and the dryer 8 for returning the vapors to the dryer 8, a pipeline 6 branches off in the flow direction upstream of the heat exchanger 7 to the combustion chamber 1.

Die Anlage arbeitet wie folgt:The system works as follows:

Die in der Brennkammer 1 erzeugten Rauchgase werden dem Wärmeaustauscher 7 zugeführt. Dort erfolgt zwischen den heißen Rauchgasen und den im Kreislauf geführten relativ kühlen Brüden ein indirekter Wärmeaustausch, in dessen Ergebnis sich die Brüden auf die für die Trocknung des zu trocknenden Gutes erforderliche Verfahrenstemperatur aufheizen. Nach diesem Wärmeaustauschvorgang wird der heiße Brüdenstrom über das zwischen dem Wärmeaustauscher 7 und dem Trockner 8 angeordnete Teilstück der Rohrleitung 13 dem Trockner 8 zu dessen direkter Beheizung zugeführt. Während des Trocknungsvorganges werden weitere Brüden und schädliche Inhaltsstoffe aus dem zu trocknenden Gut freigesetzt, die zusammen mit dem getrockneten Gut aus dem Trockner 8 abgeführt werden. In dem sich anschließenden Abscheider werden die gröberen Fraktionen des getrockneten Gutes abgetrennt. Die in den Brüden verbleibenden feinen Fraktionen des getrockneten Gutes werden dann zusammen mit den Brüden über ein Gebläse 11 einem oder mehreren Zyklonen 12 zugeführt. Dort erfolgt die Abscheidung der feinen Fraktionen des getrockneten Gutes. Die den bzw. die Zyklone 12 verlassenden Brüden sind mit Feinstäuben und den bei der Trocknung entstandenen Schadstoffen belastet. Sie werden über die Rohrleitung 13 zum Trockner 8 zurückgeführt, wobei sie den Wärmeaustauscher 7 passieren und aufgeheizt werden. Damit ist der annähernd inerte Brüdenkreislauf geschlossen.The flue gases generated in the combustion chamber 1 are fed to the heat exchanger 7. There is an indirect heat exchange between the hot flue gases and the relatively cool vapors which are circulated, as a result of which the vapors heat up to the process temperature required for drying the material to be dried. After this heat exchange process, the hot vapor stream is fed to the dryer 8 for direct heating via the section of the pipeline 13 arranged between the heat exchanger 7 and the dryer 8. During the drying process, further vapors and harmful ingredients are released from the material to be dried, which are removed from the dryer 8 together with the dried material. The coarser fractions of the dried material are separated in the subsequent separator. The fine fractions of the dried material remaining in the vapors are then fed together with the vapors via a blower 11 to one or more cyclones 12. This is where the fine fractions of the dried material are separated. The vapors leaving the cyclone (s) 12 are contaminated with fine dust and the pollutants formed during drying. They are returned to the dryer 8 via the pipeline 13, passing through the heat exchanger 7 and being heated up. This closes the almost inert vapor cycle.

Da im Kreislauf während des Trocknungsvorganges ständig neue, mit Schadstoffen versetzte Brüden entstehen, muß der zirkulierende Brüdenstrom aus Gründen der technologisch im Kreislauf einzuhaltenden Massenbilanz laufend reduziert werden. Das geschieht mittels der Abzweigleitung 6, über die ein Brüden-Teilstrom in die Brennkammer 1 geleitet und dort verbrannt wird. Für den Fall, daß die Einmischung des relativ kühlen Brüden-Teilstromes in die heißen Rauchgase der Brennkammer 1 nicht effektiv ist, kann eine weitere Abzweigleitung 14 in die Brennkammer 1 geführt werden, die hinter dem Wärmeaustauscher 7 vom Kreislauf abgeht. Die darin geführten aufgeheizten Brüden lassen sich einfacher mit den heißen Rauchgasen der Brennkammer 1 mischen. Die Summe der beiden Brüden-Teilströme ist dabei wegen der im Kreislauf einzuhaltenden Massenbilanz immer gleich groß.Since new vapors containing pollutants are constantly formed in the circuit during the drying process, the circulating vapor flow must be continuously reduced for reasons of the mass balance to be observed technologically in the circuit. This is done by means of the branch line 6, via which a vapor partial flow passed into the combustion chamber 1 and burned there. In the event that the mixing of the relatively cool vapor partial flow into the hot flue gases of the combustion chamber 1 is not effective, a further branch line 14 can be led into the combustion chamber 1, which branches off from the circuit behind the heat exchanger 7. The heated vapors contained therein are easier to mix with the hot flue gases from the combustion chamber 1. The sum of the two vapor partial streams is always the same because of the mass balance to be maintained in the circuit.

Die den Wärmeaustauscher 7 verlassenden, gekühlten Rauchgase werden mittels eines Ventilators 15 in eine Filtervorrichtung 16, die als Trockenfilter in Gestalt eines Schlauchfilters oder dergl. ausgebildet ist, gefördert, wo sie gereinigt werden. Wird aschefreier Brennstoff verwendet, kann diese Filtervorrichtung entfallen. Nach der Reinigung werden die Rauchgase in einen Wärmeaustauscher 17 geführt und dort zur Vorwärmung der Verbrennungsluft genutzt. Diese wird über die Rohrleitung 19 dem Brenner 2 zugeführt. Nach dem Wärmeaustauscher 17 werden die Rauchgase über einen Kamin 18 in die Atmosphäre geleitet.The cooled flue gases leaving the heat exchanger 7 are conveyed by means of a fan 15 into a filter device 16, which is designed as a dry filter in the form of a bag filter or the like, where they are cleaned. This filter device can be omitted if ash-free fuel is used. After cleaning, the flue gases are passed into a heat exchanger 17 and used there to preheat the combustion air. This is fed to the burner 2 via the pipeline 19. After the heat exchanger 17, the flue gases are passed into the atmosphere via a chimney 18.

Die Erfindung ist nicht nur auf die Trocknung von Holzspänen, Holzfasern oder dergl. beschränkt, sondern auch für andere Schüttgüter, wie z.B. Fischmehl, Torf, Kohle, Getreide und Klärschlamm, anwendbar.The invention is not only limited to the drying of wood chips, wood fibers or the like, but also for other bulk materials, e.g. Fish meal, peat, coal, grain and sewage sludge, applicable.

Claims (12)

  1. A process for continuous drying of wood chips, or wood fibres, from flue gases generated in a separate combustion chamber by means of heat in a dryer loaded with the material to be dried characterised in that residual vapour from the dryer returns to the dryer in a flue gas free cycle, and immediately before the dryer passes over a heat exchanger through which the combustion chamber waste gases are heated to a temperature required for drying of material to be dried, whereby a subsidiary vapour stream is diverted from that cycle before the heat exchanger and is returned to the combustion chamber.
  2. A process according to claim 1, characterised in that a further subsidiary vapour stream is diverted from the cycle following heat exchange.
  3. A process according to one of the preceding claims, characterised in that a greater vapour current is flowing in the cycle than in the subsidiary vapour stream.
  4. A process according to one of the preceding claims, characterised in that the entire combustion is substantially stoichiometric.
  5. A process according to one of the preceding claims, characterised in that the primary combustion material for the generation of the flue gases comprises oil, preferably light oil, gas or combustible powder, either alone or optionally included in a mixture.
  6. A process according to one of the preceding claims, characterised in that after the heat exchange the resulting cooled flue gases are purified in a dry filtration process.
  7. A process according to one of the preceding claims, characterised in that the residual heat of the flue gases is used for preheating a burner of one of the combustion chambers for generation of flue gas combustion air flow.
  8. A process according to one of the preceding claims, characterised in that the vapours flowing in the cycle are heated to drying operation temperature of between 400°C and 600°C.
  9. Apparatus for carrying out a method according to one or more of the preceding claims, with a separate combustion chamber for generation of drying heat for a dryer, a feeding device for the material to be dried in the dryer, conveyor means for transfer of dried material and vapour from the dryer and one or more cyclones for separation of the dried material from the vapour, characterised in that a tubing (13) from the cyclones (12) returns the vapour separated from the flue gas to the dryer (8), a heat exchanger (7) is arranged in the tubing (13) for heat exchange between the combustion chamber waste flue gases and the vapour, and a branch (6) extends from the tubing (13) prior to the heat exchanger (7) in the direction of current flow to the combustion chamber (1).
  10. Apparatus according to claim 9, characterised in that a ventilator (15) is arranged for removal of waste flue gases from the heat exchanger (7) to a chimney (18) above a filter device (16).
  11. Apparatus according to claim 9, characterised in that the filter device (16) is formed as a drying filter in the form of a tube filter or the like.
  12. Apparatus according to claim 11, characterised in that a heat exchanger (17) is adjacent to the filter device (16), by means of which the residual heat of the flue gases is used to heat the combustion atmosphere, which arrives in the burner (2) above a tubing (19).
EP91250134A 1990-06-01 1991-05-15 Process and apparatus for continuous drying of wood chips, wood fibres or other bulk materials Revoked EP0459603B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT91250134T ATE97225T1 (en) 1990-06-01 1991-05-15 PROCESS AND PLANT FOR CONTINUOUS DRYING OF WOOD CHIPS, WOOD FIBERS OR OTHER BULK MATERIALS.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4017806A DE4017806A1 (en) 1990-06-01 1990-06-01 METHOD AND SYSTEM FOR THE CONTINUOUS DRYING OF WOODCHIPS, WOOD FIBERS OR OTHER SHEET GOODS
DE4017806 1990-06-01

Publications (2)

Publication Number Publication Date
EP0459603A1 EP0459603A1 (en) 1991-12-04
EP0459603B1 true EP0459603B1 (en) 1993-11-10

Family

ID=6407697

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91250134A Revoked EP0459603B1 (en) 1990-06-01 1991-05-15 Process and apparatus for continuous drying of wood chips, wood fibres or other bulk materials

Country Status (12)

Country Link
US (1) US5237757A (en)
EP (1) EP0459603B1 (en)
JP (1) JPH04227464A (en)
AT (1) ATE97225T1 (en)
AU (1) AU7806091A (en)
CA (1) CA2043681A1 (en)
CZ (1) CZ280448B6 (en)
DE (2) DE4017806A1 (en)
ES (1) ES2046848T3 (en)
FI (1) FI912615A (en)
RU (1) RU2023964C1 (en)
ZA (1) ZA914130B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1363097A1 (en) 2002-05-13 2003-11-19 Robert Dr. Bankwitz Pneumatic centrifugal dryer
EP3759056A4 (en) * 2018-03-01 2022-05-11 Steve Macchio Systems and methods for environmentally-clean thermal drying

Families Citing this family (32)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2654811B1 (en) * 1989-11-20 1994-11-04 Kurt Gisiger PROCESS AND PLANT FOR DRYING ORGANIC MATERIALS, PARTICULARLY WOOD PARTICLES.
NL9100606A (en) * 1991-04-08 1992-11-02 Vandenbroek Int Bv DRYING DEVICE.
US5697167A (en) * 1994-11-24 1997-12-16 W. Kunz Drytec Ag Method for drying a substance, in particular wood shavings
US5603751A (en) * 1995-06-02 1997-02-18 Mac Equipment, Inc. Method and apparatus for removing particulate material from a wood drying system
US5653042A (en) * 1995-07-21 1997-08-05 Besnard; Rene Apparatus for drying crop materials
SE507409C2 (en) * 1995-10-19 1998-05-25 Vattenfall Ab Procedure for fuel treatment
US5758434A (en) * 1996-11-12 1998-06-02 Georgia-Pacific Corporation Wood drying system
DE19654043C2 (en) 1996-12-23 1998-05-28 Martin Dipl Ing Knabe Dryer with exhaust gas cleaning using thermal post-combustion
EP1012516B1 (en) * 1998-06-11 2005-01-26 Universal Dynamics, Inc. Method and apparatus for drying granular solids with venturi powered gas circulation
DE10011177A1 (en) * 2000-03-08 2001-09-20 Valmet Panelboard Gmbh Drying of wood particles as chips or fibers and the like has an initial drying stage partially heated by cleaned exhaust gas from the main drier where hot gases are the drying medium from a combustion chamber
FI4752U1 (en) * 2000-08-24 2000-12-18 Pauli Matias Haukka Timber drying and heat treatment equipment
DE10056459C1 (en) * 2000-11-14 2002-04-04 Fraunhofer Ges Forschung Wood fibre treatment method has closed drying circuit supplied with steam-gas mixture separated from dried wood fibres
US6742284B2 (en) 2001-01-08 2004-06-01 Advanced Dryer Systems, Inc. Energy efficient tobacco curing and drying system with heat pipe heat recovery
DE10157596C1 (en) * 2001-11-23 2003-03-20 Fraunhofer Ges Forschung Fibrous substance preparation process involves diverting part flow into second heat exchanger before first heat exchanger in flow direction
EP1843114A1 (en) * 2006-04-06 2007-10-10 Swedish Exergy Consulting AB Dryer plant
US20080271335A1 (en) * 2007-05-03 2008-11-06 Archer-Daniele-Midland Company System for using heat to process an agricultural product, a fluidized bed combustor system, and methods of employing the same
ES2554638T3 (en) 2008-01-10 2015-12-22 Douglas Technical Limited Procedure and device for continuous drying of bulk product, in particular of wood fibers and / or wood chips
ATE514909T1 (en) * 2008-12-23 2011-07-15 Kronotec Ag WOOD SHREDDING PRODUCT DRYING PLANT
HUE024574T2 (en) * 2009-03-10 2016-02-29 Kronotec Ag Wood chips drying plant for drying wood chips and method for drying wood chips
EP2411749A4 (en) * 2009-03-25 2016-01-20 Saxlund Internat Holding Ab System and method for drying
RU2446371C2 (en) * 2010-06-09 2012-03-27 Научно-производственная фирма с ограниченной ответственностью "Экополимер" Device for drying sediments, active sludge or industrial and household sewage sediments
DE102010036425A1 (en) * 2010-07-15 2012-01-19 Polysius Ag Apparatus and method for drying and Torrefizierung of at least one carbonaceous material flow in a multi-deck oven
CN101915497B (en) * 2010-08-13 2012-07-04 李相荣 Lignite-drying and quality-improving process for preparing superheated steam from waste heat steam
RU2467269C1 (en) * 2011-05-20 2012-11-20 Федеральное государственное образовательное учреждение высшего профессионального образования "Красноярский государственный аграрный университет" Independent drying unit of high-moisture plant raw material
US20150267963A1 (en) * 2012-10-14 2015-09-24 Applied Cleantech Inc. Systems and devices for feedstock production from sewage
CN103148690B (en) * 2013-04-07 2015-01-21 江苏快乐木业集团有限公司 Wood shaving drying device
CN103722754B (en) * 2013-12-19 2016-05-04 中材科技股份有限公司 A kind of solidification equipment that is applicable to hollow composite material production line
US11248845B2 (en) 2017-03-03 2022-02-15 Douglas Technical Limited Apparatus and method for continuously drying bulk goods, in particular wood chips and/or wood fibers comprising a heat exchanger
UA124778C2 (en) * 2017-03-03 2021-11-17 Даґлас Текнікал Лімітед Apparatus and method for continuously drying bulk goods, in particular wood chips and/or wood fibers comprising multi-fuel burner with a muffle cooling system
EP3589891A1 (en) * 2017-03-03 2020-01-08 Douglas Technical Limited Apparatus and method for continuously drying bulk goods, in particular wood chips and/or wood fibers comprising a solid fired hot gas generator
EA201991750A1 (en) * 2017-03-03 2020-02-28 Дуглас Текникал Лимитед DEVICE AND METHOD FOR CONTINUOUS DRYING OF LOOSE PRODUCTS, IN PARTICULAR WOOD CHIP AND / OR WOOD FIBERS, INCLUDING A CYCLE FOR HOT GAS
CN110730895A (en) 2017-06-06 2020-01-24 道格拉斯科技有限公司 Device and method for continuously drying bulk goods

Family Cites Families (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2254848B2 (en) * 1972-11-09 1976-08-05 Böhler-Zenkner GmbH & Co KG Strömungstechnik, 4005 Meerbusch ARRANGEMENT FOR THERMAL POST-COMBUSTION
CH559151A5 (en) * 1972-12-06 1975-02-28 Seiler Hermann & Sohn Ag
GB1429972A (en) * 1973-08-24 1976-03-31 Duur Kg Otto Process of and apparatus for heating circulating air in drying quipment
DE2461415A1 (en) * 1974-12-24 1976-07-08 Hans Roos Unit for return and combustion of vapours in drying plants - has portions of exhaust gas and fines as well as odoriferous materials combusted in burner
US4231165A (en) * 1977-06-22 1980-11-04 Bruckner Apparatebau Gmbh Process for heat-treating a fabric web
US4132007A (en) * 1977-08-17 1979-01-02 Voorheis James T Single burner heater and incinerator
US4218832A (en) * 1979-04-27 1980-08-26 Champion International Corporation Apparatus for processing wood products using heat from a boiler for indirectly heating drying gas
US4276835A (en) * 1979-10-04 1981-07-07 Von Roll Ag method for processing sewage sludge
US4926567A (en) * 1985-07-04 1990-05-22 Fuji Photo Film Co., Ltd. Process and apparatus for drying coated web
DE3605100A1 (en) * 1986-02-18 1987-08-27 Monforts Gmbh & Co A TEXTILE MACHINE WITH CONTINUOUS CONVECTIVE HEAT TREATMENT
DE3616333C1 (en) * 1986-05-15 1987-04-16 Krantz H Gmbh & Co Process for the thermal cleaning of exhaust gases from a heat treatment device
US4715965A (en) * 1986-05-19 1987-12-29 Sigerson Adam L Method for separating and recovering volatilizable contaminants from soil
DE3715668A1 (en) * 1987-05-11 1988-12-01 Baehre & Greten METHOD AND SYSTEM FOR CLEANING DRYING EXHAUST GASES WHEN DRYING WOODCHIPS, WOOD FIBERS OR THE LIKE
US4759777A (en) * 1987-11-10 1988-07-26 Bact Engineering, Inc. Decontamination of wood chip dryer gas
FR2654811B1 (en) * 1989-11-20 1994-11-04 Kurt Gisiger PROCESS AND PLANT FOR DRYING ORGANIC MATERIALS, PARTICULARLY WOOD PARTICLES.
CH676500A5 (en) * 1990-05-18 1991-01-31 Werner Kunz

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1363097A1 (en) 2002-05-13 2003-11-19 Robert Dr. Bankwitz Pneumatic centrifugal dryer
DE10221367B4 (en) * 2002-05-13 2006-05-11 Bankwitz, Robert, Dr. Pneumatic centrifugal dryer
EP3759056A4 (en) * 2018-03-01 2022-05-11 Steve Macchio Systems and methods for environmentally-clean thermal drying

Also Published As

Publication number Publication date
CZ280448B6 (en) 1996-01-17
US5237757A (en) 1993-08-24
ATE97225T1 (en) 1993-11-15
FI912615A0 (en) 1991-05-31
JPH04227464A (en) 1992-08-17
AU7806091A (en) 1991-12-05
CA2043681A1 (en) 1991-12-02
FI912615A (en) 1991-12-02
RU2023964C1 (en) 1994-11-30
DE59100574D1 (en) 1993-12-16
ES2046848T3 (en) 1994-02-01
DE4017806A1 (en) 1991-12-05
EP0459603A1 (en) 1991-12-04
CS163591A3 (en) 1992-02-19
ZA914130B (en) 1992-03-25

Similar Documents

Publication Publication Date Title
EP0459603B1 (en) Process and apparatus for continuous drying of wood chips, wood fibres or other bulk materials
EP0461305B1 (en) Process for the purification of exhaust gases of plants for the production of cement clinker
EP0358006B1 (en) Method and apparatus for purifying waste gases from dryers
EP2078911B1 (en) Method for continuous drying of bulk material, in particular of wood fibres and/or wood chippings
DE4120277A1 (en) METHOD AND DEVICE FOR PURIFYING EXHAUST GASES FROM OVEN PLANTS
DE3836899C1 (en)
DE3010909A1 (en) METHOD AND DEVICE FOR BURNING FINE-GRAINED GOODS AND FOR GENERATING CARBON DUST
DE3542004A1 (en) Drying and combustion of sludges in the firing of mineral materials
EP0253079A2 (en) Method of and plant for reclaiming contaminated soils and similar materials
DD211358A5 (en) METHOD AND DEVICE FOR SMOKE-GASKING IN CARBOX FIRES
DE19654043A1 (en) Thermal dryer with exhaust gas cleaning, afterburning e.g. for wood chips
EP0883778B1 (en) Sewage sludge incineration process and plant
DE3047060C2 (en) Method and device for drying and burning sludge
EP0534225B1 (en) Plant for the heat treatment of powdery materials
DE4102216A1 (en) METHOD AND POWER PLANT FOR RECYCLING SLUDGE
EP0571722B1 (en) Process and plant layout for drying and burning waste materials
DE10011177A1 (en) Drying of wood particles as chips or fibers and the like has an initial drying stage partially heated by cleaned exhaust gas from the main drier where hot gases are the drying medium from a combustion chamber
DE3537595A1 (en) Method and installation for utilising moist waste, in particular sewage sludge
DE19501736C1 (en) Process for the incineration of sewage sludge and plant for carrying out the process
EP0391427B1 (en) Process and apparatus for environmentally safe preparation of an asphaltic mixture using recycled asphalt
DE2535683A1 (en) METHOD AND DEVICE FOR INCINERATION OF SLUDGE WITH THE HELP OF RECUPERATIVE SLUDGE DRYING
EP0040857B1 (en) Process and apparatus for the separation of gaseous and solid noxious products from residues arising from thermal processes, particularly from the pyrolysis of refuse
EP0118058A2 (en) Process and apparatus for the destruction of liquid or pasty waste
DE4431564A1 (en) Process and technical circuit for drying and burning sewage sludge
DD234336A3 (en) DEVICE FOR PRODUCING ALKALIUM CEMENT CLINKERS

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH DE ES FR GB GR IT LI SE

17P Request for examination filed

Effective date: 19920522

17Q First examination report despatched

Effective date: 19920911

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT BE CH DE ES FR GB GR IT LI SE

REF Corresponds to:

Ref document number: 97225

Country of ref document: AT

Date of ref document: 19931115

Kind code of ref document: T

REF Corresponds to:

Ref document number: 59100574

Country of ref document: DE

Date of ref document: 19931216

ET Fr: translation filed
REG Reference to a national code

Ref country code: ES

Ref legal event code: FG2A

Ref document number: 2046848

Country of ref document: ES

Kind code of ref document: T3

ITF It: translation for a ep patent filed

Owner name: ING. BETTELLO LUIGI

GBT Gb: translation of ep patent filed (gb section 77(6)(a)/1977)

Effective date: 19940121

PLBI Opposition filed

Free format text: ORIGINAL CODE: 0009260

26 Opposition filed

Opponent name: VANDENBROEK INTERNATIONAL B.V.

Effective date: 19940805

Opponent name: BABCOCK-BSH AKTIENGESELLSCHAFT, VORMALS BUETTNER-S

Effective date: 19940810

EAL Se: european patent in force in sweden

Ref document number: 91250134.3

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 19950504

Year of fee payment: 5

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: CH

Payment date: 19950510

Year of fee payment: 5

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: ES

Payment date: 19950511

Year of fee payment: 5

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: AT

Payment date: 19950529

Year of fee payment: 5

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 19950530

Year of fee payment: 5

Ref country code: GR

Payment date: 19950530

Year of fee payment: 5

Ref country code: FR

Payment date: 19950530

Year of fee payment: 5

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: BE

Payment date: 19950609

Year of fee payment: 5

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19950727

Year of fee payment: 5

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19960516

Ref country code: ES

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19960516

RDAH Patent revoked

Free format text: ORIGINAL CODE: EPIDOS REVO

RDAG Patent revoked

Free format text: ORIGINAL CODE: 0009271

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: PATENT REVOKED

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

Ref country code: GR

Ref legal event code: MF4A

Free format text: 3010729

27W Patent revoked

Effective date: 19960824

GBPR Gb: patent revoked under art. 102 of the ep convention designating the uk as contracting state

Free format text: 960824

EUG Se: european patent has lapsed

Ref document number: 91250134.3