DE112004002205T5 - Oven and degreasing process - Google Patents

Abstract

A furnace comprising a heating unit, a furnace body capable of degreasing an object to be degreased by heating the article with the heating unit, and a treatment gas introducing unit, the object being disposed in the furnace body and containing an organic substance,
the furnace body including an outlet for discharging a degreasing gas containing a small amount of gaseous oxygen and a large amount of gaseous organic decomposition products generated in an inner portion of the furnace body during degreasing of the article, and
wherein the furnace body also includes an inlet for receiving a dilution gas from outside to reduce the concentration of the gaseous organic decomposition products in the furnace body to prevent the explosion of gaseous organic decomposition products;
the heating unit includes a first heater capable of heating and degreasing the object disposed in the furnace body, and a second heater heating the degreasing gas discharged from the outlet of the furnace body.

Description

Technical part

The The present invention relates to furnaces and degreasing processes (or debindering procedure). The present invention relates in particular to a furnace, which is an object to be degreased preserved in such a way because of abnormal Combustion of gaseous organic decomposition products to be torn to that concentration of gaseous Oxygen in the furnace is kept low. The stove can do the Degrease the item quickly with low cost in a short time. The present invention also relates to a degreasing method, that's useful is a degreased object without cracks at low cost to get in a short time.

State of the art

ceramic Materials containing organic substances (for example, organic Binder or organic pore-forming agents) are used in the preparation used by ceramic products, for example for the production of ceramic honeycomb structures used in exhaust emission control systems for vehicles be used because such structures have high quality features as having a function of supporting a catalyst and the ceramic materials show good impression properties. A shaped body (An object to be degreased), which by molding a ceramic Material containing an organic substance must be prepared ordinary Way before burning the molding be degreased at high temperature to a fired body, so that the organic substance is removed from the article. In this Process is the organic substance (for example, polyvinyl alcohol or the like) contained in the article is decomposed and gaseous by heating made gaseous organic decomposition products (for example, methyl alcohol, acetaldehyde and the like). As the gaseous organic decomposition products each have an upper and lower explosion limit (for example are the respective upper and lower explosion limits of methyl alcohol 7.3% and 19% and that of acetaldehyde 4.1 and 55% respectively), There is a problem that an abnormal combustion like an explosion while Degreasing occurs, causing cracks or imperfections in the article be caused when the concentration of gaseous organic Decomposition products between their upper and lower explosion limits lies. To solve the problem, a gas inlet is provided in an oven and a diluent gas (For example, air) through the gas inlet so introduced that the concentration of gaseous organic decomposition products is reduced, making them lower than the lower explosive limit and thus prevents the explosion becomes. In this technique, however, the above abnormal combustion while Degreasing can not be prevented because the concentration of gaseous organic combustion products in the furnace is high. Consequently, must the object heated slowly and at a low temperature for one be degreased for a long period of time. Consequently, this technique is inefficient.

in view of the previous circumstances the following oven was proposed: a microwave oven, which a microwave heater, a furnace chamber for receiving an object (which can be referred to as burning object, because he is fired in a subsequent step) to degrease the is, and an inlet pipe for a carrier gas for insertion a carrier gas includes, which contains oxygen and which has a lower oxygen content than air, to reduce the combustion of an organic substance (see Patent Document 1).

Patent document 1: Japanese unaudited published Patent Application No. 2003-302166.

Of the However, the microwave oven disclosed in Patent Document 1 has one complicated configuration and is expensive in operation, because the microwave oven requires the use of a carrier gas, the has a lower oxygen content than air to the combustion from such an organic substance decrease and needed Inlet pipe for the carrier gas for insertion the carrier gas. Therefore, the microwave oven is not necessarily satisfactory.

The present invention has been made in light of the foregoing circumstances. It is an object of the present invention to provide a furnace which prevents an object to be degreased in such a manner from being torn due to the abnormal combustion of gaseous organic decomposition products that the concentration of oxygen gas in the furnace becomes low and which can easily degrease the object at a low cost in a short time. It is also an object of the present invention to provide a degreasing process which is useful for Quickly getting a defatted item without cracks at a low cost in a short time is useful.

• (1) Ein Ofen (hiernach in einigen Fällen als „ein Ofen gemäß eines ersten Aspekts der vorliegenden Erfindung" bezeichnet) schließt eine Heizeinheit und einen Ofenkörper ein, der einen zu entfettenden Gegenstand durch Aufheizen des Gegenstandes mit der Heizeinheit entfetten kann, wobei der Gegenstand in dem Ofenkörper angeordnet ist und eine organische Substanz enthält. Der Ofenkörper schließt einen Auslass zum Ausstoßen eines Entfettungsgases ein, das eine kleine Menge an gasförmigem Sauerstoff und eine große Menge an gasförmigen organischen Zersetzungsprodukten enthält, die in einem inneren Abschnitt des Ofenkörpers während der Entfettung des Gegenstandes erzeugt wurden. Der Ofenkörper schließt ebenso einen Einlass zum Empfangen eines Verdünnungsgases von außen her zum Verringern der Konzentration der gasförmigen organischen Zersetzungsprodukte in dem Ofenkörper ein, um die Explosion der gasförmigen organischen Zersetzungsprodukte zu verhindern. Die Heizeinheit schließt einen ersten Heizer, der den in dem Ofenkörper angeordneten Gegenstand erhitzen und entfetten kann, und einen zweiten Heizer, welcher das Entfettungsgas aufheizt, das aus dem Auslass des Ofenkörpers ausgestoßen wird, ein, so dass die gasförmigen organischen Zersetzungsprodukte entfernt werden und so dass das Entfettungsgas in ein Behandlungsgas umgewandelt wird, das eine kleine Menge an gasförmigem Sauerstoff enthält. Der Ofen schließt ferner eine Einheit zum Einführen von Behandlungsgas zum Einleiten des Behandlungsgases zur Verdünnung in den inneren Abschnitt des Ofenkörpers von dem zweiten Heizer durch den Einlass und/oder den ersten Heizer ein. Das Behandlungsgas wird in den inneren Abschnitt des Ofenkörpers von dem Einlass und/oder dem ersten Heizer in einer solchen Art und Weise eingeführt, dass das Behandlungsgas durch den inneren Abschnitt des Ofenkörpers, den Auslass, den zweiten Heizer, die Einführeinheit für das Behandlungsgas und den Einlass und/oder den ersten Heizer zirkuliert wird, wodurch die Konzentration der gasförmigen organischen Zersetzungsprodukte in dem inneren Abschnitt des Ofenkörpers verringert wird, so dass die Explosion verhindert wird, wodurch die Konzentration an gasförmigem Sauerstoff in dem inneren Abschnitt des Ofenkörpers niedrig gehalten wird, so dass der Gegenstand davor geschützt wird, aufgrund der anormalen Verbrennung der gasförmigen organischen Zersetzungsprodukte gerissen zu werden, und wodurch der Gegenstand in einer kurzen Zeit entfettet und dann einem nachfolgenden Brennschritt unterzogen werden kann.
• (2) Ein Ofen (hiernach in einigen Fällen als „ein Ofen gemäß eines zweiten Aspekts der vorliegenden Erfindung" bezeichnet) schließt eine Heizeinheit und einen Ofenkörper ein, der einen zu entfettenden Gegenstand durch Erhitzen des Gegenstandes mit der Heizeinheit entfetten kann, wobei der Gegenstand in dem Ofenkörper angeordnet ist und eine organische Substanz enthält. Der Ofenkörper schließt einen Auslass zum Ausstoßen eines Entfettungsgases ein, das eine kleine Menge an gasförmigem Sauerstoff und eine große Menge an gasförmigen organischen Zersetzungsprodukten enthält, die in einem inneren Abschnitt des Ofenkörpers während der Entfettung des Gegenstandes erzeugt wurden. Der Ofenkörper schließt ebenso einen Einlass zum Empfangen eines Verdünnungsgases von außen her zum Verringern der Konzentration der gasförmigen organischen Zersetzungsprodukte in dem Ofenkörper ein, um die Explosion der gasförmigen organischen Zersetzungsprodukte zu verhindern. Die Heizeinheit schließt einen dritten Heizer ein, welcher das Entfettungsgas erhitzt, das von dem Auslass des Ofenkörpers ausgestoßen wird, so dass die gasförmigen organischen Zersetzungsprodukte entfernt werden, und so dass das Entfettungsgas in ein Behandlungsgas umgewandelt wird, das eine kleine Menge an gasförmigem Sauerstoff enthält. Der Ofen schließt ferner eine Einführeinheit für das Behandlungsgas zum Einleiten des Behandlungsgases zum Verdünnen in den inneren Abschnitt des Ofenkörpers von dem dritten Heizer durch den Einlass ein. Das Behandlungsgas wird in den inneren Abschnitt des Ofenkörpers von dem Einlass in einer solchen Art und Weise eingeleitet, dass das Behandlungsgas durch den inneren Abschnitt des Ofenkörpers, den Auslass, den dritten Heizer, die Einführeinheit für das Behandlungsgas und den Einlass zirkuliert wird, wodurch die Konzentration der gasförmigen organischen Zersetzungsprodukte in dem inneren Abschnitt des Ofenkörpers verringert wird, so dass eine Explosion verhindert wird, wodurch die Konzentration an gasförmigem Sauerstoff in dem inneren Abschnitt des Ofenkörpers niedrig gehalten wird, so dass der Gegenstand davor bewahrt wird, aufgrund der anormalen Verbrennung der gasförmigen organischen Zersetzungsprodukte gerissen zu werden, und wodurch der Gegenstand in einer kurzen Zeit entfettet und dann einem nachfolgenden Brennschritt unterzogen werden kann.
• (3) Der Ofen gemäß den Punkten (1) oder (2) schließt ferner eine Einführeinheit für ein Gas mit niedrigem Sauerstoffgehalt zum Einleiten eines Gases mit niedrigem Sauerstoffgehalt ein, das sich in der Zufuhrleitung von dem Behandlungsgas in den inneren Bereich des Ofenkörpers zusätzlich zu oder anstatt von der Einführeinheit für das Behandlungsgas unterscheidet.
• (4) In dem Ofen gemäß einem der Punkte (1) bis (3) enthält die organische Substanz mindestens eine, die aus der Gruppe ausgewählt wurde, die aus Polyvinylalkohol, Polyethylenglycol, Stärke, Methylcellulose, Carboxymethylcellulose, Hydroxyethylcellulose, Hydroxypropylmethylcellulose, Polyethylenoxid, Natriumpolyacrylat, Polyacrylamid, Polyvinylbutyral, Ethylcellulose, Celluloseacetat, Polyethylen, einem Ethylen-Vinylacetat-Copolymer, Polypropylen, Polystyren, einem Acrylharz, Polyamid, Glycerin, Polyethylenglycol und Dibuthylphthalat besteht.
• (5) In dem Ofen gemäß einem der Punkte (1) bis (4) wird die Konzentration an gasförmigem Sauerstoff in dem inneren Abschnitt des Ofenkörpers bei 0,5 bis 17 Volumenprozent unter Verwendung des Behandlungsgases aufrecht erhalten.
• (6) In dem Ofen gemäß einem der Punkte (1) bis (5) sind die ersten bis dritten Heizer Gasbrenner.
• (7) In dem Ofen gemäß einem der Punkte (1) bis (6) schließt die Einführeinheit für das Behandlungsgas eine abgedichtete Rohrleitung zum wechselseitigen Verbinden des zweiten oder dritten Heizers mit dem Ofenkörper ein.
• (8) Der Ofen gemäß einem der Punkte (1) bis (7) schließt ferner eine Wärmeaustauscheinheit ein, die zwischen dem zweiten oder dritten Heizer und der Einführeinheit für das Behandlungsgas und/oder der Einführeinheit für das Gas mit niedrigem Sauerstoffgehalt angeordnet ist.
• (9) In dem Ofen gemäß einem der Punkte (1) bis (8) ist der Gegenstand porös und der Prozentsatz der Summe des Volumens von nicht entflammbaren und/oder nicht flüchtigen anorganischen Verbindungen, die in dem entfetteten Gegenstand verbleiben, in dem offensichtlichen Volumen des entfetteten Gegenstandes [(die Summe der Volumina von nicht entflammbaren und/oder nicht flüchtigen anorganischen Verbindungen, die in dem entfetteten Gegenstand verbleiben)/(das offensichtliche Volumen des entfetteten Gegenstandes) × 100] ist bevorzugt 5 % bis 60 %.
• (10) Ein Entfettungs-Verfahren (hiernach in einigen Fällen als „ein Entfettungs-Verfahren gemäß eines dritten Aspekts der vorliegenden Erfindung" bezeichnet) schließt einen Schritt des Entfettens eines zu entfettenden Gegenstandes unter Verwendung eines Ofens ein, welcher eine Heizeinheit und einen Ofenkörper aufweist, durch Erhitzen des Gegenstandes mit der Heizeinheit und einen Brennschritt nachfolgend zu dem Entfettungsschritt, wobei der Gegenstand in einem inneren Abschnitt des Ofenkörpers angeordnet ist und eine organische Substanz enthält. Der Ofenkörper schließt einen Auslass zum Ausstoßen eines Entfettungsgases ein, das eine kleine Menge an gasförmigem Sauerstoff und eine große Menge an gasförmigen organischen Zersetzungsprodukten enthält, die in einem inneren Abschnitt des Ofenkörpers während der Entfettung des Gegenstandes erzeugt wurden. Der Ofenkörper und schließt ebenso einen Einlass zum Empfangen eines Verdünnungsgases von außen her ein zum Verringern der Konzentration der gasförmigen organischen Zersetzungsprodukte in dem Ofenkörper, um die Explosion der gasförmigen organischen Zersetzungsprodukte zu verhindern. Die Heizeinheit schließt einen ersten Heizer, der den in dem Ofenkörper angeordneten Gegenstand erhitzen und entfetten kann, und einen zweiten Heizer, welcher das Entfettungsgas aufheizt, das aus dem Auslass des Ofenkörpers ausgestoßen wird, ein, so dass die gasförmigen organischen Zersetzungsprodukte entfernt werden, und so dass das Entfettungsgas in ein Behandlungsgas umgewandelt wird, das eine kleine Menge an gasförmigem Sauerstoff enthält. Der Ofen schließt ferner eine Einheit zum Einführen von Behandlungsgas zum Einleiten des Behandlungsgases zur Verdünnung in den inneren Abschnitt des Ofenkörpers von dem zweiten Heizer durch den Einlass und/oder den ersten Heizer ein. Das Behandlungsgas wird durch den inneren Abschnitt des Ofenkörpers, den Auslass, den zweiten Heizer, die Einführeinheit für das Behandlungsgas und den Einlass und/oder den ersten Heizer zirkuliert, wodurch die Konzentration der gasförmigen organischen Zersetzungsprodukte in dem inneren Abschnitt des Ofenkörpers verringert wird, so dass die Explosion verhindert wird, wodurch die Konzentration an gasförmigem Sauerstoff in dem inneren Abschnitt des Ofenkörpers niedrig gehalten wird, so dass der Gegenstand davor geschützt wird, aufgrund der anormalen Verbrennung der gasförmigen organischen Zersetzungsprodukte gerissen zu werden, und wodurch der Gegenstand in einer kurzen Zeit entfettet und dann einem nachfolgenden Brennschritt unterzogen werden kann.
• (11) In dem Entfettungs-Verfahren gemäß Punkt (10) wird das Behandlungsgas durch den inneren Abschnitt des Ofenkörpers, den Auslass, den zweiten Heizer, der Einführeinheit für das Behandlungsgas und den Einlass ohne den Betrieb des ersten Heizers zirkuliert.
• (12) Ein Entfettungs-Verfahren (hiernach in einigen Fällen als „ein Entfettungs-Verfahren gemäß eines vierten Aspekts der vorliegenden Erfindung" bezeichnet) schließt einen Schritt des Entfettens eines zu entfettenden Gegenstandes unter Verwendung eines Ofens ein, der eine Heizeinheit und einen Ofenkörper umfasst, durch Erhitzen des Gegenstandes mit der Heizeinheit und einen Brennschritt nachfolgend zu dem Entfettungsschritt, wobei der Gegenstand in einem inneren Abschnitt des Ofenkörpers angeordnet ist und eine organische Substanz enthält. Der Ofenkörper schließt einen Auslass zum Ausstoßen eines Entfettungsgases ein, das eine kleine Menge an gasförmigem Sauerstoff und eine große Menge an gasförmigen organischen Zersetzungsprodukten enthält, die in einem inneren Abschnitt des Ofenkörpers während der Entfettung des Gegenstandes erzeugt wurden. Der Ofenkörper schließt ebenso einen Einlass zum Empfangen eines Verdünnungsgases von außen her zum Verringern der Konzentration der gasförmigen organischen Zersetzungsprodukte in dem Ofenkörper ein, um die Explosion der gasförmigen organischen Zersetzungsprodukte zu verhindern. Die Heizeinheit schließt einen dritten Heizer ein, welcher das Entfettungsgas erhitzt, das von dem Auslass des Ofenkörpers ausgestoßen wird, so dass die gasförmigen organischen Zersetzungsprodukte entfernt werden, und so dass das Entfettungsgas in ein Behandlungsgas umgewandelt wird, das eine kleine Menge an gasförmigem Sauerstoff enthält. Der Ofen schließt ferner eine Einführeinheit für das Behandlungsgas zum Einleiten des Behandlungsgases zum Verdünnen in den inneren Abschnitt des Ofenkörpers von dem dritten Heizer durch den Einlass ein. Das Behandlungsgas wird durch den inneren Abschnitt des Ofenkörpers, den Auslass, den dritten Heizer, die Einführeinheit für das Behandlungsgas und den Einlass zirkuliert, wodurch die Konzentration der gasförmigen organischen Zersetzungsprodukte in dem inneren Abschnitt des Ofenkörpers verringert wird, so dass eine Explosion verhindert wird, wodurch die Konzentration an gasförmigem Sauerstoff in dem inneren Abschnitt des Ofenkörpers niedrig gehalten wird, so dass der Gegenstand davor bewahrt wird, aufgrund der anormalen Verbrennung der gasförmigen organischen Zersetzungsprodukte gerissen zu werden, und wodurch der Gegenstand in einer kurzen Zeit entfettet und dann einem nachfolgenden Brennschritt unterzogen werden kann.
• (13) Das Entfettungs-Verfahren gemäß einem der Punkte (10) bis (12) schließt ferner eine Einführeinheit für Gas mit niedrigem Sauerstoffgehalt zum Einleiten eines Gases mit niedrigem Sauerstoffgehalt ein, das in der Zufuhrleitung für das Behandlungsgas in dem inneren Abschnitt des Ofenkörpers zusätzlich zu oder anstatt von der Einführeinheit für das Behandlungsgas unterschiedlich ist.
• (14) In dem Entfettungs-Verfahren gemäß einem der Punkte (10) bis (13) enthält die organische Substanz mindestens eine, die aus der Gruppe ausgewählt wurde, die aus Polyvinylalkohol, Polyethylenglycol, Stärke, Methylcellulose, Carboxymethylcellulose, Hydroxyethylcellulose, Hydroxypropylmethylcellulose, Polyethylenoxid, Natriumpolyacrylat, Polyacrylamid, Polyvinylbutyral, Ethylcellulose, Celluloseacetat, Polyethylen, einem Ethylen-Vinylacetat-Copolymer, Polypropylen, Polystyren, einem Acrylharz, Polyamid, Glycerin, Polyethylenglycol und Dibuthylphthalat besteht.
• (15) In dem Entfettungs-Verfahren nach einem der Punkte (10) bis (14) wird die Konzentration an gasförmigem Sauerstoff in dem inneren Abschnitt des Ofenkörpers bei 0,5 bis 17 Volumenprozent unter Verwendung des Behandlungsgases aufrecht erhalten.
• (16) In dem Entfettungs-Verfahren gemäß einem der Punkte (10) bis (15) sind die ersten bis dritten Heizer Gasbrenner.
• (17) In dem Entfettungs-Verfahren gemäß einem der Punkte (10) bis (16) schließt die Einführeinheit für das Behandlungsgas eine abgedichtete Rohrleitung zum wechselseitigen Verbinden des zweiten oder dritten Heizers mit dem Ofenkörper ein.
• (18) Das Entfettungs-Verfahren gemäß einem der Punkte (10) bis (17) schließt ferner eine Wärmeaustauscheinheit und/oder einen Katalysator ein, der zwischen dem zweiten oder dritten Heizer und der Einführeinheit für das Behandlungsgas und/oder der Einführeinheit für das Gas mit niedrigem Sauerstoffgehalt angeordnet ist.
• (19) In dem Entfettungs-Verfahren gemäß einem der Punkte (10) bis (18) ist der Gegenstand porös und der Prozentsatz der Summe der Volumina an nicht entflammbaren und/oder nicht flüchtigen anorganischen Verbindungen, die in dem entfetteten Gegenstand verbleiben, in dem offensichtlichen Volumen des entfetteten Gegenstandes [(die Summe der Volumina an nicht entflammbaren und/oder nicht flüchtigen anorganischen Verbindungen, die in dem entfetteten Gegenstand verbleiben)/(das offensichtliche Volumen des entfetteten Gegenstandes) × 100] ist bevorzugt 5 % bis 60 %.

In order to achieve the above object, the inventors have made intensive investigations. As a result, the inventors have found that an object to be defatted may be broken as follows: gaseous organic decomposition products generated during degreasing are rapidly burned in an atmosphere containing a large amount of gaseous oxygen. Moreover, the inventors have found that the article can be prevented from being cracked in such a manner that a degreasing gas used for degreasing and containing a small amount of gaseous oxygen is efficiently circulated in a system, so that the gaseous organic decomposition products are removed from the system and the concentration of gaseous organic decomposition products in the system is reduced. In addition, the article may be degreased in such a manner that the article is degreased in an atmosphere containing a small amount of gaseous oxygen. The present invention is based on these findings. The present invention provides furnaces and degreasing methods as described below.

• (1) A furnace (hereafter referred to as "a furnace according to a first aspect of the present invention" in some cases) includes a heating unit and a furnace body which can degrease an object to be degreased by heating the article with the heating unit The furnace body includes an outlet for discharging a degreasing gas containing a small amount of gaseous oxygen and a large amount of gaseous organic decomposition products stored in an inner portion of the furnace body during degreasing of the degassing gas The furnace body also includes an inlet for receiving a diluent gas from outside to reduce the concentration of the gaseous organic decomposition products in the furnace body to prevent the explosion of gaseous organic decomposition products t includes a first heater capable of heating and degreasing the object disposed in the furnace body, and a second heater which heats the degreasing gas discharged from the outlet of the furnace body so as to remove the gaseous organic decomposition products and thus the degreasing gas is converted into a treatment gas containing a small amount of gaseous oxygen. The furnace further includes a processing gas introducing unit for introducing the treatment gas for dilution into the inner portion of the furnace body from the second heater through the inlet and / or the first heater. The treatment gas is introduced into the inner portion of the furnace body from the inlet and / or the first heater in such a manner that the treatment gas passes through the inner portion of the furnace body, the outlet, the second heater, the treatment gas introduction unit and the treatment gas introduction unit Inlet and / or the first heater is circulated, whereby the concentration of the gaseous organic decomposition products in the inner portion of the furnace body is reduced, so that the explosion is prevented, whereby the concentration of gaseous oxygen in the inner portion of the furnace body is kept low, so that the article is prevented from being torn due to the abnormal combustion of gaseous organic decomposition products, and whereby the article can be degreased in a short time and then subjected to a subsequent firing step.
• (2) A furnace (hereafter referred to as "a furnace according to a second aspect of the present invention" in some cases) includes a heating unit and a furnace body which can degrease an object to be degreased by heating the article with the heating unit The furnace body includes an outlet for discharging a degreasing gas containing a small amount of gaseous oxygen and a large amount of gaseous organic decomposition products stored in an inner portion of the furnace body during degreasing of the degassing gas The furnace body also includes an inlet for receiving a diluent gas from outside to reduce the concentration of the gaseous organic decomposition products in the furnace body to prevent the explosion of gaseous organic decomposition products t includes a third heater which heats the degreasing gas discharged from the outlet of the furnace body so as to remove the gaseous organic decomposition products, and so that the degreasing gas is converted into a treatment gas containing a small amount of gaseous oxygen. The furnace further includes a treatment gas introducing unit for introducing the treatment gas for diluting into the inner portion of the furnace body from the third heater through the inlet. The treatment gas is introduced into the inner portion of the furnace body from the inlet in such a manner that the treatment gas is circulated through the inner portion of the furnace body, the outlet, the third heater, the treatment gas introducing unit, and the inlet, whereby the treatment gas Concentration of the gaseous organic decomposition products in the inner portion of the furnace body is reduced, so that an explosion is prevented, whereby the concentration of gaseous oxygen in the inner portion of the furnace body is kept low, so that the object is prevented from being torn due to the abnormal combustion of the gaseous organic decomposition products, and thus the article degreased in a short time and then subjected to a subsequent firing step.
• (3) The furnace according to item (1) or (2) further includes a low-oxygen gas introduction unit for introducing a low-oxygen gas, which is in the supply line from the treatment gas into the inner portion of the furnace body in addition to or instead of the introduction unit for the treatment gas.
• (4) In the furnace according to any one of (1) to (3), the organic substance contains at least one selected from the group consisting of polyvinyl alcohol, polyethylene glycol, starch, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropylmethyl cellulose, polyethylene oxide, sodium polyacrylate , Polyacrylamide, polyvinyl butyral, ethyl cellulose, cellulose acetate, polyethylene, an ethylene-vinyl acetate copolymer, polypropylene, polystyrene, an acrylic resin, polyamide, glycerol, polyethylene glycol and dibutyl phthalate.
• (5) In the furnace according to any one of (1) to (4), the concentration of gaseous oxygen in the inner portion of the furnace body is maintained at 0.5 to 17% by volume using the treating gas.
• (6) In the furnace according to any one of (1) to (5), the first to third heaters are gas burners.
• (7) In the furnace according to any one of (1) to (6), the treatment gas introducing unit includes a sealed pipe for mutually connecting the second or third heater to the furnace body.
• (8) The furnace according to any one of (1) to (7) further includes a heat exchange unit interposed between the second or third heater and the treatment gas introduction unit and / or the low oxygen gas introduction unit.
• (9) In the furnace according to any one of items (1) to (8), the article is porous and the percentage of the sum of the volume of nonflammable and / or nonvolatile inorganic compounds remaining in the degreased article is in the apparent volume of the degreased article [(the sum of the volumes of nonflammable and / or nonvolatile inorganic compounds remaining in the degreased article) / (the apparent volume of the defatted article) x 100] is preferably 5% to 60%.
• (10) A degreasing method (hereinafter referred to as "a degreasing method according to a third aspect of the present invention" in some cases) includes a step of degreasing an object to be degreased using a furnace having a heating unit and a furnace body by heating the article with the heating unit and a firing step subsequent to the degreasing step, wherein the article is disposed in an inner portion of the furnace body and contains an organic substance The furnace body includes an outlet for discharging a degreasing gas containing a small amount of gaseous Containing oxygen and a large amount of gaseous organic decomposition products generated in an inner portion of the furnace body during the degreasing of the article The furnace body and also includes an inlet for receiving a diluent gas from the outside to the decrease n the concentration of gaseous organic decomposition products in the furnace body to prevent the explosion of the gaseous organic decomposition products. The heating unit includes a first heater that can heat and degrease the object disposed in the furnace body, and a second heater that heats the degreasing gas discharged from the outlet of the furnace body so as to remove the gaseous organic decomposition products, and so that the degreasing gas is converted into a treatment gas containing a small amount of gaseous oxygen. The furnace further includes a processing gas introducing unit for introducing the treatment gas for dilution into the inner portion of the furnace body from the second heater through the inlet and / or the first heater. The treatment gas is circulated through the inner portion of the furnace body, the outlet, the second heater, the treatment gas introducing unit, and the inlet and / or the first heater, thereby reducing the concentration of gaseous organic decomposition products in the inner portion of the furnace body that the explosion is prevented, thereby keeping the concentration of gaseous oxygen in the inner portion of the furnace body low, so that the article is prevented from being torn due to the abnormal combustion of the gaseous organic decomposition products, and thereby the article in a short time degreased and then subjected to a subsequent firing step.
• (11) In the degreasing method according to item (10), the treatment gas is circulated through the inner portion of the furnace body, the outlet, the second heater, the treatment gas introducing unit, and the inlet without the operation of the first heater.
• (12) A degreasing method (hereinafter referred to as "a degreasing method according to a fourth aspect of the present invention" in some cases) includes a step of degreasing an object to be degreased using a furnace comprising a heating unit and a furnace body by heating the article with the heating unit and a firing step subsequent to the degreasing step, wherein the article is disposed in an inner portion of the furnace body and contains an organic substance The furnace body includes an outlet for discharging a degreasing gas containing a small amount of gaseous Contains oxygen and a large amount of gaseous organic decomposition products generated in an inner portion of the furnace body during the degreasing of the article The furnace body also includes an inlet for receiving a diluent gas from the outside to reduce the concentration ration of the gaseous organic decomposition products in the furnace body to prevent the explosion of the gaseous organic decomposition products. The heating unit includes a third heater which heats the degreasing gas discharged from the outlet of the furnace body so as to remove the gaseous organic decomposition products, and so that the degreasing gas is converted into a treatment gas containing a small amount of gaseous oxygen , The furnace further includes a treatment gas introducing unit for introducing the treatment gas for diluting into the inner portion of the furnace body from the third heater through the inlet. The treatment gas is circulated through the inner portion of the furnace body, the outlet, the third heater, the treatment gas introducing unit, and the inlet, thereby reducing the concentration of gaseous organic decomposition products in the inner portion of the furnace body, thereby preventing an explosion, whereby the concentration of gaseous oxygen in the inner portion of the furnace body is kept low, so that the article is prevented from being cracked due to the abnormal combustion of the gaseous organic decomposition products, and whereby the article is degreased in a short time and then a subsequent firing step can be subjected.
• (13) The degreasing method according to any one of (10) to (12) further includes a low-oxygen gas introduction unit for introducing a low-oxygen gas which is additionally present in the treatment gas supply passage in the inner portion of the furnace body to or instead of the introduction unit for the treatment gas is different.
• (14) In the degreasing method according to any one of (10) to (13), the organic substance contains at least one selected from the group consisting of polyvinyl alcohol, polyethylene glycol, starch, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropylmethyl cellulose, polyethylene oxide , Sodium polyacrylate, polyacrylamide, polyvinyl butyral, ethyl cellulose, cellulose acetate, polyethylene, an ethylene-vinyl acetate copolymer, polypropylene, polystyrene, an acrylic resin, polyamide, glycerine, polyethylene glycol and dibutyl phthalate.
• (15) In the degreasing method according to any one of (10) to (14), the concentration of gaseous oxygen in the inner portion of the furnace body is maintained at 0.5 to 17% by volume using the treating gas.
• (16) In the degreasing method according to any one of (10) to (15), the first to third heaters are gas burners.
• (17) In the degreasing method according to any one of (10) to (16), the treatment gas introducing unit includes a sealed pipe for mutually connecting the second or third heater to the furnace body.
• (18) The degreasing method according to any one of (10) to (17) further includes a heat exchange unit and / or a catalyst interposed between the second or third heater and the treatment gas introduction unit and / or the gas introduction unit is arranged with low oxygen content.
• (19) In the degreasing method according to any one of (10) to (18), the article is porous and the percentage of the sum of the volumes of nonflammable and / or nonvolatile inorganic compounds remaining in the degreased article in the apparent volume of the degreased article [(the sum of the volumes of nonflammable and / or nonvolatile inorganic compounds remaining in the degreased article) / (the apparent volume of the defatted article) x 100] is preferably 5% to 60%.

The The present invention provides a furnace which is to be degreased Subject in such a way can protect against it the abnormal combustion of gaseous organic decomposition products to be torn, that the concentration of oxygen gas in the Oven is kept low. The oven can handle the item quickly degrease at low cost in a short time. The present The invention also provides a degreasing method useful for rapidly obtaining a degreased object without cracks at low cost in one short time useful is.

1 FIG. 10 is a schematic view illustrating an embodiment of the present invention (a furnace according to a first embodiment and a degreasing method according to a third embodiment). FIG.

2 Fig. 12 is a graph showing the relationship between the temperature and the weight change of polyvinyl alcohol which has been sufficiently dried at 80 ° C and which is an organic substance, the relationship being by heating polyvinyl alcohol at a rate of 5 ° C per minute was obtained in three types of gas streams.

3 Fig. 12 is a graph showing the relationship between the temperature and the heat generated by polyvinyl alcohol, which has been sufficiently dried at 80 ° C, and which is an organic substance, the relationship being determined by heating polyvinyl alcohol at a rate of 5 ° C per minute Minute was obtained in three types of gas streams.

4 FIG. 12 is a schematic view illustrating an embodiment of the present invention (a furnace according to a second embodiment and a degreasing method of a fourth embodiment). FIG.

5 Fig. 10 is a schematic view illustrating an example of the present invention (a furnace according to the first or second embodiment and a degreasing method of the third or fourth embodiment).

1

heating unit

2

furnace body

3

insertion unit for the gas treatment

3a

sealed pipeline

3b

circulation fan

3c

damper

4

Heat exchange unit

4a

Erhitzerkessel

4b

water sprayer

4c

adjustment for the Efficiency of

heat exchange

5

to degreasing object

6

Entfettungsgas

7

gas treatment

7a

circulating gas

7b

exhaust

7c

steam

8th

Heat exchange gas

9

insertion unit for gas with low

oxygen content

9a

gas with low oxygen content

9b

introducing member for gaseous nitrogen

9c

gaseous nitrogen

10

oven

11

first Heater (stove burner)

11a

inlet for the circulating gas of the kiln burner

11b

fuel for the kiln burner

11c

air for the kiln burner

12

second Heater (afterburner)

12a

combustion chamber of the afterburner

12b

fuel for the afterburner

12c

air for the afterburner

13

third stoker

20

internal Section of the furnace body

21

inlet

22

outlet

embodiments The present invention will now be described with reference to the accompanying drawings described.

1 FIG. 10 is a schematic view illustrating an embodiment of the present invention (a furnace according to a first embodiment and a degreasing method according to a third embodiment). FIG. With reference to 1 The furnace according to the first embodiment closes a heating unit 1 and a furnace body 2 a, the object to be degreased 5 by heating the object 5 with the heating unit 1 can degrease, the object 5 in the furnace body 2 is arranged and contains an organic substance. The furnace body 2 closes an outlet 21 for discharging a degreasing gas 6 a, which contains a small amount of gaseous oxygen and a large amount of gaseous organic decomposition products, which in an inner section 20 of the furnace body during degreasing of the article 5 be generated. The furnace body 2 also closes an inlet 22 for receiving a diluent gas from outside to reduce the concentration of gaseous organic decomposition products in the furnace body 2 to prevent the explosion of gaseous organic decomposition products. The heating unit 1 closes a first heater 11 that in the furnace body 2 arranged object 5 can heat up and degrease, and a second heater 12 one which the degreasing gas 6 that's from the outlet 21 of the furnace body 2 is heated, so that the gaseous organic decomposition products are removed (the gaseous organic decomposition products are substantially absent), and so that the degreasing gas 6 in a treatment gas 7 is converted, which contains a small amount of gaseous oxygen. The oven further includes an insertion unit 3 for a treatment gas for introducing the treatment gas 7 for thinning into the inner portion of the furnace body 2 from the second heater 12 through the inlet 22 and / or the first heater 11 one. The treatment gas 7 will be in the inner section 20 of the furnace body through the inlet 22 and / or the first heater 11 introduced in such a way that the treatment gas 7 with, for example, a circulation fan 3b through the inner section 20 of the furnace body, the inlet 21 , the second heater 12 , the introduction unit for the treatment gas 3 and the inlet 22 and / or the first heater 11 which causes the concentration of the gaseous organic decomposition products in the inner section 20 of the furnace body is reduced, so that an explosion is prevented, whereby the concentration of gaseous oxygen in the inner portion 20 the furnace body is kept low so that the article 5 is prevented from being torn due to the abnormal combustion of the gaseous organic decomposition products, and whereby the article 5 degreased in a short time and then subjected to a subsequent firing step.

In this embodiment, when the treatment gas 7 for thinning in the inner section 20 of the furnace body from the second heater 12 with the insertion unit 3 for the treatment gas is introduced (circulated), the treatment gas 7 here in through one or both of the inlet 22 and the first heater 11 introduced (circulated) (which serve as circulation connections). In this case, the conditions are preferably selected depending on the design of the furnace, so that the temperature of the furnace can be easily controlled.

In this embodiment, the oven preferably further includes an insertion unit 9 for low-oxygen gas for introducing a gas 9a with a low oxygen content, which from the supply line for the treatment gas 7 is different, in the inner section 20 of the furnace body in addition to or instead of the insertion unit 3 for the treatment gas. In particular, when it is difficult to adjust the oxygen concentration to a desired value only by circulating the treatment gas 7 to control is the introduction unit 9 for low-oxygen gas, in particular, effective in forcibly reducing the oxygen concentration. In addition to the treatment gas 7 (in the case where a heat exchange unit 4 as described below, as a heat exchange gas 8th In some cases, the following gas is referred to as "a circulating gas 7a "denotes an imaginary gas (in other words, gas repeatedly introduced into the inner portion of the furnace body), which is a gaseous mixture of the treatment gas 7 (the heat exchange gas 8th ) and the gas 9a containing low oxygen content. Examples of the gas 9a low oxygen content include an inert gas such as argon or nitrogen and an exhaust gas of a boiler heater. Examples of the introduction unit 9 for low-oxygen gas include a unit containing the gas 9a low-oxygen content introduction, for example, a piping system connected to a boiler or a low-oxygen gas generator. The introductory unit 9 for low-oxygen gas may depend on the design of the furnace in addition to the introduction unit 3 for the treatment gas as described above or instead of the introduction unit 3 be used for the treatment gas. The introductory unit 9 for low-oxygen gas as well as the introduction unit 3 for the treatment gas, both to one or both of the inlet 22 and the first heater 11 be connected.

The organic substance used in this embodiment is not particularly limited and may contain, for example, at least one selected from the group consisting of polyvinyl alcohol, polyethylene glycol, starch, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropylmethyl cellulose, polyethylene oxide, sodium polyacrylate, polyacrylamide, polyvinyl butyral, Ethyl cellulose, cellulose acetate, polyethylene, an ethylene-vinyl acetate copolymer, polypropylene, polystyrene, an acrylic resin, polyamide, glycerin, polyethylene glycol and dibuthyl phthalate, each serving as an organic binder. When the subject matter described in detail below 5 is porous, the organic substance may contain a pore-forming agent in addition to an organic binder. The pore-forming agent contains natural organic particles of starch or rice hulls, paraffin waxy hydrocarbon particles having a molecular weight of 1,000 or less, or particles of an organic ester having a molecular weight of 1,000 or less. These materials are decomposed by combustion, producing the gaseous organic decomposition products. The gaseous organic decomposition products are, for example, methyl alcohol, acetaldehyde, methyl formate, carbon dioxide, carbon monoxide, water and tar.

2 Fig. 14 shows the relationship between the temperature and the weight change of polyvinyl alcohol which has been sufficiently dried at 80 ° C and which is contained in the organic substance, the relationship being obtained by heating polyvinyl alcohol at a rate of 5 ° C per minute in three ways Gas flows was obtained. 3 shows the relationship between the temperature and the heat generated from polyvinyl alcohol.

How out 3 is clear, that of polyvinyl alcohol heated in a gas stream containing 20% oxygen (80% nitrogen and 20% oxygen) generated heat 95. The polyvinyl alcohol which was heated in a gas stream containing 10% oxygen (90 In addition, the heat generated from polyvinyl alcohol heated from a gas stream containing no oxygen (100 nitrogen) is about 19. When a graph (not shown) is given. in which the horizontal axis represents the oxygen content and the vertical axis represents the generated heat on the basis of the above data, the graph shows that generated from polyvinyl alcohol heated in a gas stream containing 15% oxygen Heat is 45, and the heat generated from polyvinyl alcohol heated in a gas stream containing 1% oxygen is 20%. That is, the heat generated from polyvinyl alcohols heated in the gas stream containing 15% oxygen is half or less that generated from polyvinyl alcohol heated in the gas stream containing 20% oxygen. This means that the gaseous organic combustion products were heavily burned but evaporated. As in 2 is shown, the weight of the carbonaceous residue obtained by heating polyvinyl alcohol to 400 ° C or higher in the gas stream containing no oxygen (100% nitrogen) is about 8% of that of unheated polyvinyl alcohol. If the residue is heated to a higher temperature, the residue is completely decomposed.

There the furnace has the above configuration, the degreasing time, the for the stove is needed, about half those known by conventional ovens is.

Of the in this embodiment used item is not particularly limited and can for example to be a ceramic structure. A ceramic material for making the article is not particularly limited and may be oxide ceramics powder, for example, alumina powder and 1 to 20% by mass of a contain organic compound.

In this embodiment (as well as in the second to fourth embodiments of the present invention) is the subject matter 5 preferably porous, and the percentage of the sum of the volumes of nonflammable and / or nonvolatile inorganic compounds present in the defatted article 5 remain in the apparent volume of the degreased article 5 [(the sum of the volumes of nonflammable and / or nonvolatile inorganic compounds remaining in the defatted article) / (the apparent volume of the defatted article) x 100] is preferably 5% to 60%, more preferably 5% to 40% %, and most preferably 5% to 20%, because the oven has advantages. That is, when the object 5 is porous, the content of the organic substance containing the organic binder and the organic pore-forming agent is in the article 5 greater than the content of the organic substance in a conventional article. The diffusion of heat and gas in the object 5 is higher than that in a conventional article. As a result, abnormal combustion occurs in the article 5 only hard on. In addition, the subject matter 5 has a low material strength is the object 5 vulnerable to stress caused during degreasing. Consequently, the object is 5 preferably porous because the furnace preferably has significant advantages. The name "Non-flammable and / or nonvolatile inorganic compounds" does not cover any carbonaceous material such as graphite, and the term "the apparent volume of the object to be degreased 5 "covers the volumes (volumetric capacities) of microcavities such as small closed cells, open cells and joints, but does not cover the volumes (volumetric capacities of microcavities such as large closed cells, open cells and joints having an inner radius of 10 mm or have more.

The heating unit 1 (the first heater 11 and the second heater 12 ) used in this embodiment is not particularly limited and may be a fuel oil burner, a gas burner, an electric heater, a regenerative burner, or the like. The second heater 12 For example, a catalytic combustion method in which an oxidation catalyst containing platinum or the like and the direct combustion method may be used in combination. The catalytic combustion method is useful in more effectively burning off the gaseous organic decomposition products and effective in controlling the heating temperature of the degreasing gas, which is lower compared with a method (the direct combustion method) and which does not use a catalyst (the heating temperature of the degreasing gas can be raised to 300 ° C 350 ° C depending on the components of the degreasing gas are controlled). Only the heating unit 1 (the first heater 11 and the second heater 12 ) and another heating unit may be in addition to the heating unit 1 be used.

The introductory unit 3 The treatment gas used in this embodiment is not particularly limited and preferably includes a sealed pipe 3a for mutually connecting the second heater 12 with the furnace body 2 one. Alternatively, the insertion unit 3 for the treatment gas contain a channel made of bricks or a heat insulator. The treatment gas 7 (the circulating gas 7a ) can be circulated with the circulation fan.

In this embodiment, the furnace preferably further includes the heat exchange unit 4 which, for example, is a heat exchanger which is between the second heater 12 and the introduction unit 3 is arranged for the treatment gas. In this configuration, the treatment gas becomes 7 passing through the heat exchange unit 4 passes through the heat exchange gas 8th with a lower temperature than that of the treatment gas 7 transformed. The heat exchange gas 8th will be in the inlet 22 introduced. According to this configuration, heat from the degreasing gas 6 recovered, which is released from a conventional oven. The recovered heat can be used in a steam boiler or the like. In addition, the atmosphere in the inner section 20 of the furnace body are controlled in such a manner that the temperature and the flow rate of the treatment gas 7 (of circulating gas 7a ), which is in the inner section 20 of the furnace body from the inlet 22 was initiated with the heat exchange unit 4 is controlled. Examples of the heat exchange unit 4 include a device for directly spraying water onto a stream of the treatment gas 7 for cooling the treatment gas 7 one. When such a device is used, the sprayed water is converted to steam, which is mixed with the treatment gas. Consequently, the temperature of the treatment gas becomes 7 not only reduced (heat is recovered), but also the content of oxygen in the treatment gas 7 reduced.

The compositions, oxygen contents and temperatures of these gases will now be described comparatively. The degreasing gas 6 (of which the composition and temperature with that of the gas in the inner section 20 of the furnace body) contains a large amount of the gaseous organic decomposition products and has a low oxygen content and an average temperature. The treatment gas 7 contains only a few gaseous organic decomposition products and has a low oxygen content and a high temperature. The heat exchange gas 8th contains only a few gaseous organic decomposition products and has a low oxygen content and a high temperature. In particular, the degreasing gas 6 a content of organic decomposition products of 1 to 15% by volume, an oxygen content of 0.5 to 17% by volume and a temperature of 100 ° C to 400 ° C. The degreasing time for removing the organic substance is 50% of that of a conventional oven. The treatment gas 7 has an oxygen content of 0.5 to 17 Volume percent on. The treatment gas 7 heated with the second heater (afterburner) has a temperature of 500 ° C to 900 ° C. The heat exchange gas 8th preferably has an oxygen content of 0.5 to 17% by volume and a temperature which is 1 ° C to 100 ° C higher than the temperature of the furnace during degreasing.

Since in this embodiment the treatment gas 7 (the circulating gas 7a ) is circulated, the concentration of gaseous oxygen in the inner section 20 the furnace body at 0.5 to 17 Vo lumenprozent be maintained.

The operation of the furnace of this embodiment will now be described. With reference to 1 becomes the object (ceramic molding) 5 which contains the organic substance and which is to be degreased, in the inner section 20 disposed of the furnace body, which was made of a heat insulator. The stove is heated with the first heater (burner) 11 heated. An atmosphere in the furnace body 2 is gradually due to the heat of the burner 11 heated. The gaseous organic decomposition products are extracted from the article (ceramic molding) 5 produced at the time when the oven temperature exceeds 100 ° C. The gaseous organic decomposition products become the second heater (afterburner) 12 through the outlet 21 and the treatment gas introducing unit (channel) 3 of the furnace body 2 fed and then burned. The treatment gas 7 which has been heated to a high temperature by combustion is transferred to the heat exchange unit (heat exchanger) 4 and then to the heat exchange gas 8th cooled at a temperature close to that of the oven. The heat exchange gas 8th is through the inlet 22 and / or the first heater (burner) 11 that in the furnace body 2 is arranged, supplied. The gas 9a low oxygen content containing a different supply line from the treatment gas 7 can, with the introduction unit 9 for the low oxygen gas through the inner section 20 of the furnace body and / or the first heater (burner) 11 in addition to or instead of the treatment gas 7 (Heat exchange gas 8th ). Whether the treatment gas 7 (the heat exchange gas 8th ) and / or the gas 9a low oxygen content to either or both of the inlet 22 and the first heater (burner) 11 is preferably selected or determined by a switching operation or the like based on the concept of layout of the plant. Beyond that, one or both of the introducer 3 for the treatment gas (the treatment gas 7 and / or the heat exchange gas 8th ) and the insertion unit 9 for low-oxygen gas (the gas 9a low-oxygen content) is preferably selected or determined by a switching operation or the like based on the concept of designing the equipment (for example, the flow rate of the circulating gas 7a ) Controlled.

The flow rate of the circulating gas 7a is preferably high, so that the gaseous organic decomposition products generated in the furnace effectively through the outlet 21 be ejected. When the volume of the furnace body 20 With 10 is assumed, the flow rate of the circulating gas 7a preferably 1 to 100 per minute and in particular 10 to 50 per minute. If the flow rate thereof is lower than 1 per minute, it will take a long time, the gaseous organic decomposition products 6 eject. When the flow rate thereof is greater than 100 per minute, a large-sized furnace requires the provision of a fan, burner and heat exchanger having a large size and a large capacity, so that the flow rate and the temperature of the circulating gas 7a maintained at desired values. This is inefficient.

A degreasing method according to an embodiment (the third embodiment of the present invention includes a step of degreasing an object to be degreased 5 using a furnace 10 , similar to the one in 1 one shown, which is a heating unit 1 and a furnace body 2 involves, by heating the object 5 with the heating unit 1 and a firing step subsequent to the degreasing step, wherein the article 5 in an inner section 20 of the furnace body is arranged and contains an organic substance. The furnace body 2 closes an outlet 21 for discharging a degreasing gas 6 which contains a small amount of gaseous oxygen and a large amount of gaseous organic decomposition products in the inner region 20 of the furnace body during degreasing of the article 5 were generated. The furnace body 2 also closes an inlet 22 for receiving a diluent gas from outside to reduce the concentration of gaseous organic decomposition products in the furnace body 2 to prevent the explosion of gaseous organic decomposition products. The heating unit 1 closes a first heater 11 that in the furnace body 2 arranged object 5 can heat up and degrease, and a second heater 12 one which the degreasing gas 6 heated, that from the outlet 21 of the furnace body 2 was discharged, so that the gaseous organic decomposition products are removed, and so that the degreasing gas 6 in a treatment gas 7 is converted, which contains a small amount of gaseous oxygen. The oven further includes an insertion unit 3 for the treatment gas for introducing the treatment gas 7 (a circulating gas 7a ) for dilution into the internal section 20 of the furnace body 2 from the second heater 12 through the inlet 22 and / or the first heater 11 one. The treatment gas 7 (the circulating gas 7a ) goes through the inner section 20 of the furnace body, the outlet 21 , the second heater 12 , the introductory unit 3 for the treatment gas and the inlet 22 and / or the first heater 11 which causes the concentration of the gaseous organic decomposition products in the inner section 20 of the furnace body are reduced, so that an explosion is prevented, whereby the concentration of gaseous acid fabric in the inner section 20 the furnace body is kept low so that the article 5 is prevented from being torn due to the abnormal combustion of the gaseous organic decomposition products, and whereby the article 5 degreased in a short time and then subjected to the subsequent firing step.

In this embodiment, the furnace (the furnace of the first embodiment) incorporated in FIG 1 is shown used. The furnace of the first embodiment includes the gas burner as described above. The furnace of this embodiment, as well as the furnace of the first embodiment, may include a gas burner. Alternatively, the furnace of this embodiment may be an electric furnace which can supply a sufficient amount of the circulating gas and control the concentration of oxygen therein. The furnace of this embodiment may be a hybrid type of furnace including an electric heater and a gas burner (a furnace as described below in the fourth embodiment of the present invention, as well as a furnace of this embodiment).

In this embodiment, the article 5 be degreased in such a way that the treatment gas 7 (the circulating gas 7a ) through the inner section 20 of the furnace body, the outlet 21 , the second heater 12 , the introductory unit 3 for the treatment gas and the inlet 22 without operation of the first heater 11 the furnace according to the first embodiment is circulated. In order to maintain the temperature of the inner portion of the furnace body at 400 ° C or less, a heat exchange unit is preferably used 4 and / or an insertion unit 9 operated for low-oxygen gas. When the heat exchange unit 4 includes a boiler heater, closes the heat exchange unit 4 Preferably, a heat exchange efficiency setting device which adjusts the level of water in a piston enclosed in the boiler heater and which can adjust the temperature of the gas discharged from the outlet of the boiler to the temperature of the heat exchanger to control the inner portion of the furnace body. According to this configuration, the same advantages as those of the degreasing method according to the fourth embodiment can be obtained. That is, the degreasing can be carried out easily and efficiently.

4 Fig. 10 is a schematic view illustrating an embodiment of the present invention (a furnace according to a second embodiment and a degreasing method of the fourth embodiment). With reference to 4 The furnace of this embodiment (the second embodiment) closes a heating unit and a furnace body 2 a, the object to be degreased 5 by heating the object 5 with the heating unit can degrease, with the object 5 in an inner section 20 is arranged and contains an organic substance. The furnace body 2 closes an outlet 21 for discharging a degreasing gas 6 containing a small amount of gaseous oxygen and a large amount of gaseous organic decomposition products present in the interior section 20 of the furnace body during degreasing of the article 5 were generated. The furnace body 2 also closes an inlet 22 for receiving a diluent gas from outside to reduce the concentration of gaseous organic decomposition products in the furnace body 2 to prevent the explosion of gaseous organic decomposition products. The heating unit closes a third heater 13 (the third heater 13 can as well as the second heater 12 contained in the furnace of the first embodiment) containing the degreasing gas 6 heats up, that from the outlet 21 of the furnace body 2 was discharged, so that the gaseous organic decomposition products are removed, and so that the degreasing gas 6 in a treatment gas 7 is converted, which contains a small amount of gaseous oxygen. The oven further includes an insertion unit 3 for the treatment gas for introducing the treatment gas 7 (a circulating gas 7a ) for dilution into the inner portion of the furnace body 2 from the third heater 13 through the inlet 22 one. The treatment gas 7 gets into the inner section 20 of the furnace body from the inlet 22 introduced in such a way that the treatment gas 7 through the inner section 20 of the furnace body, the outlet 21 , the third heater 13 , the introductory unit 3 for the treatment gas and the inlet 22 which causes the concentration of the gaseous organic decomposition products in the inner section 20 of the furnace body is reduced, so that the explosion is prevented, whereby the concentration of the gaseous oxygen in the inner portion 20 the furnace body is kept low so that the article 5 is prevented from being torn due to the abnormal combustion of the gaseous organic decomposition products, and whereby the article 5 degreased in a short time and then subjected to a subsequent firing step.

How out 4 is clear, the difference between the furnace of this embodiment (the furnace of the second embodiment) and the furnace of the first embodiment that the furnace of this embodiment, the first heater 11 who in 1 is not included, but is included in the furnace of the first embodiment, and that the temperature of the furnace body with the third heater 13 , egg ner heat exchange unit 4 , an introductory unit 9 is adjusted for low-oxygen gas and / or the like. The furnace of this embodiment may have substantially the same configuration as the furnace of the first embodiment except for the above differences. According to this configuration, degreasing can be carried out easily and efficiently.

The degreasing method according to an embodiment (the third embodiment) of the present invention includes a step of degreasing an object to be degreased 5 using a furnace 10 a, similar to the one in 4 shown, which is a heating unit 1 and a furnace body 2 by heating the article 5 with the heating unit 1 and a firing step subsequent to the degreasing step, wherein the article 5 in an inner section 20 of the furnace body is arranged and contains an organic substance. The furnace body 2 closes an outlet 21 for discharging a degreasing gas 6 containing a small amount of gaseous oxygen and a large amount of gaseous organic decomposition products present in the interior section 20 of the furnace body during degreasing of the article 5 were generated. The furnace body 2 also closes an inlet 22 for receiving a diluent gas from outside to reduce the concentration of gaseous organic decomposition products in the furnace body 2 to prevent the explosion of gaseous organic decomposition products. The heating unit closes a third heater 13 one which the degreasing gas 6 heats up, that from the outlet 21 of the furnace body 2 was discharged, so that the gaseous organic decomposition products are removed, and so that the degreasing gas 6 in a treatment gas 7 is converted, which contains a small amount of gaseous oxygen. The oven further includes an insertion unit 3 for the treatment gas for introducing a treatment gas 7 (a circulating gas 7a ) for dilution into the inner section 20 of the furnace body 2 from the third heater 13 through the inlet 22 one. The treatment gas is passed through the inner section 20 of the furnace body, the outlet 21 , the third heater 13 , the introductory unit 3 for the treatment gas and the inlet 22 which causes the concentration of the gaseous organic decomposition products in the inner section 20 of the furnace body is reduced so that an explosion is prevented, whereby the concentration of the gaseous oxygen in the inner portion 20 the furnace body is kept low so that the article 5 is prevented from being torn due to the abnormal burning of the gaseous inorganic decomposition products, and whereby the article 5 degreased in a short time and then subjected to the subsequent firing step.

How out 4 is clear, the difference between the degreasing method of this embodiment (the degreasing method of the fourth embodiment) and the degreasing method of the third embodiment is that the furnace (which is not a heater 11 ) used in the degreasing method of this embodiment is different from the furnace used in the degreasing method of the third embodiment, which is the first heater 11 who in 1 is shown, and that the temperature of the furnace body with the third heater 13 , a heat exchange unit 4 , an introductory unit 9 is adjusted for low-oxygen gas and / or the like. The degreasing method of this embodiment may be substantially the same as the degreasing method of the first embodiment except for the above differences. According to this method, degreasing can be performed quickly and efficiently.

In the embodiments (The furnace of the first or second embodiment and the degreasing method the third or fourth embodiment) the present invention is the degreasing temperature (the final degreasing temperature) preferably set to an optimum value (for example 350 ° C to 500 ° C), dependent of the type of each organic substance, the form and the density every object (molding) and / or the like. The firing temperature for each firing step below is carried out as needed for each degreasing step is preferably at 1200 ° C up to 2000 ° C set.

Examples

The The present invention will be further explained in detail with reference to Examples described. The present invention is not limited to the examples limited.

In the examples, an oven was used 10 who in 5 is shown, including the following components used: a furnace body 2 with a volume of 0.5 m ³ ; a heating unit, which has a first heater (oven burner) 11 with a capacity of 100 kW and a second. Heater (afterburner) 12 with a capacity of 50 kW; a treatment gas introducing unit, which is a sealed pipe 3a , a circulation fan 3b and a damper 3c includes; a heat exchange unit which a boiler heater 4a (the one adjuster for the efficiency of the heat exchanger 4c including) having a thermal capacity of 25 kW and a water flow rate of one liter per minute and a water sprayer 4b at a water flow rate of 0.5 liters per minute; and a low oxygen gas introduction unit which is an introducing member 9b for gaseous nitrogen (gaseous nitrogen 9c ). In 5 represents reference signs 11a an inlet for a circulating gas of the furnace burner, reference numeral 11b a fuel for the furnace burner, reference numerals 11c Air for the oven burner, reference number 12a a combustion chamber of an afterburner, reference numerals 12b a fuel for the afterburner, reference numerals 12c Air for the afterburner, reference number 5 to be degreased objects, reference numerals 6 a degreasing gas, reference numeral 7 a treatment gas, reference numerals 7a a circulating gas, reference numerals 7b an exhaust gas, reference numerals 21 an outlet and reference numerals 22 an inlet.

One Aluminum oxide slip containing 10% by mass of starch was used as a pore-forming agent, and the following compounds, each serving as an organic binder contained was prepared: 2% by weight of polyvinyl alcohol, 2% by weight of polyethylene glycol, 2% by mass of methylcellulose, 2% by mass of carboxymethylcellulose and 2% by weight of hydroxyethylcellulose. The sum of the contents of these compounds was 10% by mass. The alumina slip was dried and then formed into articles, which in 55 porous moldings were formed. The moldings had a diameter of 50 mm and a height of 100 mm and contained about 50 volume percent of a nonflammable or nonvolatile inorganic compound present in the defatted moldings was.

(Example 1)

Five of the moldings containing the objects to be degreased 5 were in the oven 10 placed. Among the elements (units) that are in the oven 10 were enclosed, the following units (operated units) were operated as shown in Table 1: the heating unit, the first heater (oven burner) 11 with a capacity of 100 kW and the second heater (afterburner) 12 with a capacity of 50 kW, and the heat exchange unit, which includes the boiler heater 4a (the one adjuster 4c included for the efficiency of the heat exchange) with a thermal capacity of 25 kW and a flow rate of one liter per minute and a water spray with a flow rate of 0.5 liters per minute included. The circulating gas 7a was circulated. In Table 1, the letter A represents the operated units and the letter B represents the non-operated units. The type of the heat exchanging unit is shown in Table 1 when the heat exchanging unit was operated. The five moldings were heated to 500 ° C over a period of 25 hours at a rate of 20 ° C per hour in such a manner that air to the oven burner at 0.5 mm ³ per minute at a furnace temperature of 200 ° C was circulated, the circulating gas was circulated at 1.0 mm ³ / min, and the oxygen concentration was maintained at 10% by volume, whereby the moldings were degreased. Table 2 shows the heating conditions for the moldings. The degreased moldings had no cracks.

(Examples 2 to 8)

Five of the moldings were degreased in each example in the same manner as described in Example 1 except that the operated units shown in Table 1 and the heating conditions shown in Table 2 were satisfied , The degreased moldings had no cracks. In Example 6, the insertion element 9b for gaseous nitrogen (gaseous nitrogen 9c ) operated. In Example 7, the adjuster 4c for the efficiency of heat exchange in addition to the boiler heater 4a operated, so that the temperature of the furnace with the adjuster 4c was controlled for the efficiency of heat exchange. The adjuster 4c for the efficiency of the heat exchange, the temperature of the heater boiler could be reduced 4a discharged gas by adjusting the level of water in the heater boiler 4a Taxes. In Example 8, the water sprayer 4b which was enclosed in the heat exchange unit instead of the boiler 4a operated. In Example 7, the furnace was operated without the operation of the first heater (oven burner) 11 operated. An oven (similar to the oven, in 4 shown and described in the second embodiment) which does not have a first heater (oven burner) 11 may be operated under the same conditions as described in Example 7.

(Comparative Examples 1 to 3)

Five of the molded articles were degreased in each comparative example in the same manner as described in Example 1 except that the operated units shown in Table 1 and the heating conditions shown in Table 2 were maintained. In Comparative Example 1 to 3, the furnace became without circulation of the circulating gas 7a and without the operation of the heat exchange unit (the boiler 4a ) and the low oxygen gas introduction unit (insertion member 9b for gaseous nitrogen) operated. The following moldings were broken into pieces as if the moldings had exploded: four of the moldings degreased in Comparative Example 1 and three of the moldings degreased in Comparative Example 2. The other (or both) moldings were broken into two large pieces. In Comparative Example 3, the molded articles were degreased for a long period of time at low temperatures (the molded articles were heated at 500 ° C. over a period of 95 hours at a rate of 5 ° C.) Thus, the degreased molded articles showed no cracking of Comparative Example 3, however, is not efficient.

(Table 1)

Industrial applicability

An oven and a degreasing process according to the present invention are in the production various ceramic products useful. They are particularly useful in the manufacture of ceramic products formed using ceramic material containing an organic substance.

An oven 10 according to the present invention includes a heating unit 11 and a furnace body 2 a, the object to be degreased 5 containing an organic substance by heating the article 5 with the heating unit 1 can degrease. The furnace body 2 closes an outlet 21 and an inlet 22 one. The heating unit 1 closes a first heater 11 and a second heater 12 one. The oven further includes an insertion unit 3 for the treatment gas for introducing a treatment gas 7 one with the second heater 12 was treated in the furnace body 2 from the second heater 12 through the inlet 22 , The treatment gas 7 gets into an inner section 20 of the furnace body from the inlet 22 introduced in such a way that the treatment gas 7 through the inner section 20 of the furnace body 20 , the outlet 21 , the introductory unit 3 for the treatment gas and the inlet 22 is circulated, the concentration of the gaseous organic decomposition products in the inner section 20 of the furnace body is reduced, so that an explosion is prevented.

Summary the disclosure

An oven 10 according to the present invention includes a heating unit 11 and a furnace body 2 a, the object to be degreased 5 containing an organic substance by heating the article 5 with the heating unit 1 can degrease. The furnace body 2 closes an outlet 21 and an inlet 22 one. The heating unit 1 closes a first heater 11 and a second heater 12 one. The oven further includes an insertion unit 3 for the treatment gas for introducing a treatment gas 7 one with the second heater 12 was treated in the furnace body 2 from the second heater 12 through the inlet 22 , The treatment gas 7 gets into an inner section 20 of the furnace body from the inlet 22 introduced in such a way that the treatment gas 7 through the inner section 20 of the furnace body 20 , the outlet 21 , the introductory unit 3 for the treatment gas and the inlet 22 is circulated, the concentration of the gaseous organic decomposition products in the inner section 20 of the furnace body is reduced, so that an explosion is prevented.

1

Claims (19)

A furnace comprising a heating unit, a furnace body capable of degreasing an object to be degreased by heating the article with the heating unit, and a treatment gas introducing unit, the object being disposed in the furnace body and containing an organic substance, the furnace body having a An outlet for discharging a degreasing gas containing a small amount of gaseous oxygen and a large amount of gaseous organic decomposition products generated in an inner portion of the furnace body during degreasing of the article, and wherein the furnace body also has an inlet for receiving a diluent gas from outside to reduce the concentration of the gaseous organic decomposition products in the furnace body to prevent the explosion of the gaseous organic decomposition products; the heating unit includes a first heater capable of heating and degreasing the object disposed in the furnace body, and a second heater which heats the degreasing gas discharged from the outlet of the furnace body so as to remove the gaseous organic decomposition products, and such that the degreasing gas is converted into a treatment gas containing a small amount of gaseous oxygen; the treatment gas introducing unit is used to introduce the treatment gas for dilution into the inner portion of the furnace body from the second heater through the inlet and / or the first heater; and the treatment gas is introduced into the inner portion of the furnace body from the inlet and / or the first heater in such a manner that the treatment gas passes through the inner portion of the furnace body, the outlet, the second heater, the treatment gas introducing unit and circulating the inlet and / or the first heater, thereby reducing the concentration of the gaseous organic decomposition products in the inner portion of the furnace body so as to prevent the explosion, thereby keeping the concentration of gaseous oxygen in the inner portion of the furnace body low; so that the article is prevented from being torn due to the abnormal combustion of the gaseous organic decomposition products, and whereby the article in a short time Degreased time and then subjected to a subsequent firing step. Oven, which has a heating unit, a furnace body, the an object to be degreased by heating the article with the heating unit can degrease, and an insertion unit for a Includes treatment gas, wherein the article is disposed in the furnace body and a contains organic substance, in which the furnace body an outlet for ejection of a degreasing gas, which involves a small amount gaseous Oxygen and a big one Amount of gaseous contains organic decomposition products that are in an inner section of the furnace body while the degreasing of the object were generated, and the furnace body also an inlet for receiving a diluent gas from outside for reducing the concentration of the gaseous organic decomposition products in the furnace body includes, around the explosion of gaseous to prevent organic decomposition products; the heating unit includes a third heater, which heats the degreasing gas, the from the outlet of the furnace body pushed out so that the gaseous organic decomposition products are removed, and so that the Degreasing gas is converted into a treatment gas, the one small amount of gaseous Contains oxygen; the insertion unit for the Treatment gas is used to dilute the treatment gas into the inner portion of the furnace body from the third heater to be introduced through the inlet; and the treatment gas is in the inner portion of the furnace body from the inlet in one introduced such a way that the treatment gas through the inner portion of the furnace body, the outlet, the third heater, the treatment gas introducing unit and the Inlet is circulated, reducing the concentration of gaseous organic Decomposition products in the inner portion of the furnace body reduced will, so that an explosion is prevented, reducing the concentration at gaseous Oxygen is kept low in the inner portion of the furnace body, so that the object is saved from it, due to the abnormal Combustion of gaseous organic decomposition products to be torn, and which the object degreased in a short time and then a subsequent one Firing step can be subjected. The furnace according to claim 1 or 2, which further comprises a insertion unit for a Low-oxygen gas for introducing a gas with low oxygen content, which is in the supply line of the treatment gas in the inner region of the furnace body in addition to or instead of the introductory unit for the Treatment gas is different. The furnace according to any one of claims 1 to 3, wherein the organic Substance contains at least one that selected from the group made of polyvinyl alcohol, polyethylene glycol, starch, methyl cellulose, carboxymethyl cellulose, Hydroxyethylcellulose, hydroxypropylmethylcellulose, polyethylene oxide, Sodium polyacrylate, polyacrylamide, polyvinyl butyral, ethyl cellulose, Cellulose acetate, polyethylene, an ethylene-vinyl acetate copolymer, Polypropylene, polystyrene, an acrylic resin, polyamide, glycerol, polyethylene glycol and dibutyl phthalate. The furnace according to any one of claims 1 to 4, wherein the concentration at gaseous Oxygen in the inner portion of the furnace body at 0.5 to 17 volume percent is maintained using the treatment gas. The oven according to any one of claims 1 to 5, wherein the first until third heater are gas burners. The oven according to any one of claims 1 to 6, wherein the introducing unit for the Treatment gas a sealed pipe to the reciprocal Connecting the second or third heater with the furnace body includes. The oven according to any one of claims 1 to 7, which further a heat exchange unit includes, the between the second or third heater and the insertion unit for the Treatment gas and / or the introduction unit for the Gas is arranged with low oxygen content. The oven according to any one of claims 1 to 8, wherein the article is porous, and the percentage of the sum of the volume of non-flammable and / or non-volatile inorganic compounds remaining in the degreased article, in the apparent volume of the defatted object [(the sum the volumes of non-flammable and / or non-volatile inorganic compounds remaining in the degreased article) / (the apparent volumes of the defatted article) x 100] 5 to 60% is. Degreasing process, which is a step of Degreasing of an object to be degreased using a Furnace, which a heating unit, a furnace body and an insertion unit for a treatment gas by heating the article with the heating unit and includes a firing step subsequent to the degreasing step, wherein the article is disposed in an inner portion of the furnace body is and contains an organic substance wherein the furnace body a Outlet for ejection of a degreasing gas, which involves a small amount gaseous Oxygen and a big one Amount of gaseous contains organic decomposition products that are in an inner section of the furnace body while the degreasing of the object were generated, and the furnace body also an inlet for receiving a diluent gas from outside for reducing the concentration of the gaseous organic decomposition products in the furnace body includes, around the explosion of gaseous to prevent organic decomposition products; the heating unit a first heater that houses the article disposed in the furnace body can heat and degrease, and a second heater, which the Degreasing gas which is expelled from the outlet of the furnace body, includes, so that the gaseous organic decomposition products are removed, and so that the Degreasing gas is converted into a treatment gas, the one small amount of gaseous Contains oxygen, the unit for insertion Treatment gas is used to treat the treatment gas for dilution the inner portion of the furnace body from the second heater through the inlet and / or the first heater initiate; and the treatment gas is through the inner Section of the furnace body, the outlet, the second heater, the treatment gas introducing unit and the Inlet and / or the first heater circulates, reducing the concentration the gaseous reduced organic decomposition products in the inner portion of the furnace body so that the explosion is prevented, reducing the concentration at gaseous Oxygen is kept low in the inner portion of the furnace body, so that the object is protected from it, due to the abnormal Combustion of gaseous organic decomposition products to be torn, and which the object degreased in a short time and then a subsequent one Firing step can be subjected. The degreasing method of claim 10, wherein the treatment gas through the inner portion of the furnace body, the Outlet, the second heater, the introduction unit for the treatment gas and the Inlet is circulated without the operation of the first heater. Degreasing process, which is a step of Degreasing of an object to be degreased using a Furnace containing a heating unit, a furnace body and an insertion unit for a Treatment includes by heating the article with the heating unit and a firing step subsequent to the degreasing step, wherein the article is disposed in an inner portion of the furnace body is and contains an organic substance wherein the furnace body a Outlet for ejection of a degreasing gas, which involves a small amount gaseous Oxygen and a big one Amount of gaseous contains organic decomposition products that are in an inner section of the furnace body while the degreasing of the object were generated, and the furnace body also an inlet for receiving a diluent gas from outside for reducing the concentration of the gaseous organic decomposition products in the furnace body includes, around the explosion of gaseous to prevent organic decomposition products the heating unit includes a third heater, which heats the degreasing gas discharged from the outlet of the furnace body, so that the gaseous organic decomposition products are removed, and so that the Degreasing gas is converted into a treatment gas, the one small amount of gaseous Contains oxygen, and the insertion unit for the Treatment gas is used to treat the treatment gas for dilution in the inner portion of the furnace body from the third heater through the inlet, and the treatment gas through the inner portion of the furnace body, the outlet, the third Heater, the insertion unit for the Treatment gas and the inlet is circulated, reducing the concentration the gaseous reduced organic decomposition products in the inner portion of the furnace body will, so that an explosion is prevented, reducing the concentration at gaseous Oxygen is kept low in the inner portion of the furnace body, so that the object is saved from it, due to the abnormal Combustion of gaseous organic decomposition products to be torn, and which the object degreased in a short time and then a subsequent one Firing step can be subjected. The degreasing method according to any one of claims 10 to 12, which further comprises an insertion unit for Low-oxygen gas for introducing a low-oxygen gas, which is different in the treatment gas supply passage in the inner portion of the furnace body in addition to or instead of the treatment gas introducing unit. The degreasing method according to any one of claims 10 to 13, wherein the organic substance contains at least one, the selected from the group made of polyvinyl alcohol, polyethylene glycol, starch, methyl cellulose, Carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, Polyethylene oxide, sodium polyacrylate, polyacrylamide, polyvinyl butyral, Ethylcellulose, cellulose acetate, polyethylene, an ethylene-vinyl acetate copolymer, Polypropylene, polystyrene, an acrylic resin, polyamide, glycerol, polyethylene glycol and dibutyl phthalate. The degreasing method according to any one of claims 10 to 14, wherein the concentration of gaseous oxygen in the inner Section of the furnace body at 0.5 to 17 volume percent using the treatment gas is maintained. The degreasing method according to any one of claims 10 to 15, wherein the first to third heaters are gas burners. The degreasing method according to any one of claims 10 to 16, wherein the insertion unit for the Treatment gas a sealed pipe to the reciprocal Connecting the second or third heater to the furnace body closes. The degreasing method according to any one of claims 10 to 17, which further comprises a heat exchange unit and / or includes a catalyst interposed between the second or third heater and the introduction unit for the Treatment gas and / or the introduction unit for the Gas is arranged with low oxygen content. The degreasing method according to any one of claims 10 to 18, wherein the article is porous is, and the percentage of the sum of the volumes of non-flammable and / or non-volatile inorganic compounds remaining in the degreased article, in the apparent volume of the defatted article [the Sum of volumes of non-flammable and / or non-volatile inorganic compounds remaining in the degreased article) / (the apparent volume of the defatted article) × 100] 5% to 60%.