JP4419159B2

JP4419159B2 - Method for processing gas from object to be heated and heating furnace therefor

Info

Publication number: JP4419159B2
Application number: JP07485299A
Authority: JP
Inventors: 進高橋
Original assignee: Kanto Yakin Kogyo Co Ltd
Current assignee: Kanto Yakin Kogyo Co Ltd
Priority date: 1999-03-19
Filing date: 1999-03-19
Publication date: 2010-02-24
Anticipated expiration: 2019-03-19
Also published as: JP2000274947A

Description

【０００１】
【発明の属する技術分野】
被加熱処理物が熱間加工のために、またはそれに先だって脱脂等のために加熱炉内で加熱されると、被加熱処理物から炉室内に有機性物質が蒸発、気散する。このような物質は油脂性ガスやダイオキシン派生型ガスであったりする。
【０００２】
本発明は、このような被加熱処理物からのガスの環境汚染性を低減させて、炉外に排出するための新規な処理方法と、そのための新規な加熱炉に関するもので有る。
【０００３】
【従来の技術】
上記した如く加熱炉で加熱されて被加熱処理物より炉室内に蒸発、気散したガスは、大気中に排出される。このため、パイプによってガスを炉外の燃焼筒に導き、ここで燃焼した後に大気中に排出することが知られている。
【０００４】
【発明が解決しようとする課題】
ところが、このように加熱された被加熱処理物からのガスは、炉室内の各部分の全般にわたって一様の量で蒸発するのではなく、しかもガスは一般に油脂性で粘着性が強いので、ガスの全部を一様に燃焼筒やバーナー中に導いて完全に燃焼することが難しく、その一部はパイプ内や炉室内の壁上に軟化あるいは融解状態で付着し、灰状の堆積物となって炉の燃焼を阻害したり、炉壁を侵食したりすることになる。
【０００５】
そこで、本発明では、被加熱処理物からのガスが炉室を侵食したりすることがなく、しかも該ガスを炉室内に設けられたバーナーに良好に導くことができる方法と、そのための加熱炉を提案するものである。
【０００６】
【課題を解決するための手段】
本発明では、断熱材で囲まれた炉室内に耐熱性のマッフルを設け、この中で被加熱処理物をマッフル外の炉室内に設けられた負圧燃焼輻射加熱管によって加熱することより、被加熱処理物からのガスが炉室を侵食したりすることがない。しかも、このマッフルの外周に複数の開口を設け、かつこの開口の開度を調節自在とすることにより、ガスを上記した負圧燃焼輻射加熱管に良好に導くことができるものである。以下、添付の図面を参照して、本発明になる好適な実施例を説明する。
【０００７】
【発明の実施の形態】
実施例１
図中で符号１は、本発明の方法を達成するために好適な長尺な加熱炉の全体を示している。鋼製の炉殻２に覆われて断熱材３があり、この断熱材３の壁に囲まれて断面が矩形で長尺な炉室４が作られている。この実施例では、炉室４の幅は１００cm、高さは７０cmで、その全長は２９６cmである。
【０００８】
この炉室４の全長にわたり、かつその両端から炉外へ伸展するように、耐熱鋼製のマッフル５が加熱炉１に設けられている。炉室４とマッフル５との間は、後記する開口８を除いては気密を保つように取り付けられている。この実施例では、マッフルの幅は８０cmで、高さは３０cmで、その全長を３２６cmとした。
【０００９】
上記した開口８の複数が、マッフルの外周に設けられる。この実施例では、マッフル５の両側壁に互いに間隔を置いてそれぞれ直径が６cmの４個の円形の開口を設けたが、該開口８はマッフルの底面または上面壁に設けられてもよい。
【００１０】
また、図示されていないが、その開口度を炉外から調節できるように作られている。マッフル５の両端の入口と出口とはそれぞれ開閉自在な蓋１５で覆われており、マッフル中を循環して走るコンベヤベルト６上に乗って被加熱処理物９がマッフル５内を通過する。
【００１１】
符号７は、マッフル５の外で炉室４内に設けられた複数の負圧燃焼輻射加熱管で、内筒１１と外筒１２とからなり、炉外に伸びる内筒１１の外方端１４から燃料と燃焼用の空気とが送られ、一方、炉外に伸びる外筒１２の外方端には炉室４内よりも外筒１２内が負圧となるように働く排気口１３が設けられている。内筒１１と外筒１２の炉室４内に伸びる内方端はそれぞれ炉室４内に開口する。なお、符号１０は加熱炉１の支脚である。
【００１２】
上述した構成になる加熱炉は、以下に述べる如く運転される。負圧燃焼輻射加熱管７の内筒１１の外方端１４から内筒中に送られた燃料と空気は内筒１１中で燃焼し、その燃焼廃ガスは排気口１３に働く負圧により外筒１２を通って該排気口１３から大気中に排出される。
【００１３】
コンベヤ６に乗ってマッフル５中を通る被加熱処理物９は、加熱管７によって加熱され、被加熱処理物から蒸発、離脱した有機性蒸発物質は、開口８と炉室４とを通って負圧燃焼輻射加熱管７に吸入され、そこで燃焼または熱分解して加熱管の排気口１３から大気中に排出される。
【００１４】
なお、コンベヤに乗って図中で左手の入口からマッフル５内に入った被加熱処理物９は、マッフル５内を進行するのにつれて次第に加熱され、図３に示されるように被加熱処理物からの蒸発ガスの量も次第に増す。このようなガスをマッフルからその開口８を介して炉室内に円滑に流し、効率良く加熱管７に吸入させるために、必要によっては開口８の開口度を調節する。例えば、図中の一番左手の開口を半開にし、次の開口を３／４開にし、次の２つの開口を何れも全開にする。
【００１５】
１個８g の鋼製のネジを、毎時１２０Kgで上記した加熱炉で６００℃に加熱した。毎時1.2 Kgの機械加工用鉱油が、被加熱処理物のネジから蒸発した。この蒸発物は、マッフル５の側面の開口８から円滑にマッフル外に流れ、負圧燃焼輻射加熱管７に吸引され、加熱管に送られた燃料と共に燃焼した。このときの加熱管の全部に送られた天然燃料ガスの燃焼総量は、毎時９５０００Ｋｃａｌで、加熱管からの廃ガス中の残量酸素量が５％を保つように燃焼用空気の加熱管への供給を調節した。排気口１３から排出された廃ガス中にはメタンは検出されず、被加熱処理物のネジから蒸発した鉱油が熱分解されていることが確認できた。
【００１６】
延べ１５０時間の操業後に、ネジをマッフル中に送らずにマッフルを７００℃で２時間加熱し、いわゆる空焼きした。マッフルの開口からの蒸発物が認められ、マッフル中の壁に付着していた堆積物が高温に曝されて、蒸発し、除去されたことが認められた。
【００１７】
実施例２
上記した加熱炉のマッフル内に開口部から大気が侵入しないように、窒素ガスを送りながら摂氏６００℃に炉の温度を保ち、毎時４３Kgの炭素繊維前駆体を熱処理したところ、排気ガス中にはメタンは検出されなかった。
【００１８】
実施例３
上記加熱炉のマッフル内に、開口部から大気が侵入しないように窒素ガスを送りながら、プレス成型した構造用クロム鋼粉体からなる歯車の焼結前駆体を、毎時４００個（総重量２００Kg）を６００℃で熱処理したところ、プレス成型時に粉体に加えられた高分子化合物の９８％以上が蒸発、除去された。また、排気ガス中にはメタンは検出されなかった。
【００１９】
【発明の効果】
上述したところから明らかな通り、本発明によれば被加熱処理物に含まれる有機性物質等が炉内にて熱処理によって蒸発、気散されるとき、これらの物質が炉内でほとんど完全に加熱分解されて炉外に排出される。しかも、本発明の方法と加熱炉では、該有機性物質等は炉内で燃焼されて、被加熱処理物の加熱のための加熱源として利用される副次的な効果もある。
【図面の簡単な説明】
【図１】本発明の方法を達成するために好適に用いられる加熱炉の一例の説明的な正面断面図である。
【図２】図１に示される加熱炉の説明的な側面断面図である。
【図３】被加熱処理物が加熱炉内を通るとき、通過時間に伴って昇温し、処理物からの蒸発ガスの量も従って増加することを説明的に示すグラフである。
【符号の説明】
１−加熱炉の全体
２−炉殻
３−断熱材
４−炉室
５−マッフル
６−コンベアベルト
７−負圧燃焼輻射加熱管
８−マッフルの外周の開口
９−被加熱処理物
１０−支脚
１１−負圧燃焼輻射加熱管の内筒
１２−負圧燃焼輻射加熱管の外筒
１３−排気口
１４−燃料（燃焼用空気）供給口
１５−マッフルの入口と出口の開閉自在蓋[0001]
BACKGROUND OF THE INVENTION
When the object to be heated is heated in the heating furnace for hot working or prior to degreasing, the organic substance evaporates and diffuses from the object to be heated into the furnace chamber. Such a substance may be an oleaginous gas or a dioxin-derived gas.
[0002]
The present invention relates to a novel processing method for reducing the environmental pollution of gas from such a material to be heated and discharging it to the outside of the furnace, and a novel heating furnace therefor.
[0003]
[Prior art]
As described above, the gas heated in the heating furnace and evaporated and diffused from the object to be heated into the furnace chamber is discharged into the atmosphere. For this reason, it is known that gas is guided to a combustion cylinder outside the furnace by a pipe and burned here and then discharged into the atmosphere.
[0004]
[Problems to be solved by the invention]
However, the gas from the object to be heated heated in this way does not evaporate in a uniform amount throughout each part in the furnace chamber, and the gas is generally greasy and sticky. It is difficult to completely incinerate all of this into a combustion cylinder or burner, and some of them adhere to the inside of the pipe or the furnace chamber in a softened or molten state, resulting in ash-like deposits. This will hinder the combustion of the furnace and erode the furnace wall.
[0005]
Therefore, in the present invention, a gas from the object to be heated does not erode the furnace chamber, and the gas can be favorably guided to a burner provided in the furnace chamber, and a heating furnace therefor This is a proposal.
[0006]
[Means for Solving the Problems]
In the present invention, a heat-resistant muffle is provided in the furnace chamber surrounded by the heat insulating material, and the object to be heated is heated by a negative pressure combustion radiation heating tube provided in the furnace chamber outside the muffle. Gas from the heat-treated product does not erode the furnace chamber. Moreover, by providing a plurality of openings on the outer periphery of the muffle and making the opening degree of the openings adjustable, the gas can be favorably guided to the above-described negative pressure combustion radiation heating pipe. Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Example 1
In the figure, reference numeral 1 denotes the whole of a long heating furnace suitable for achieving the method of the present invention. A heat insulating material 3 is covered with a steel furnace shell 2, and a long furnace chamber 4 having a rectangular cross section surrounded by a wall of the heat insulating material 3 is formed. In this embodiment, the furnace chamber 4 has a width of 100 cm, a height of 70 cm, and a total length of 296 cm.
[0008]
A heat-resistant steel muffle 5 is provided in the heating furnace 1 so as to extend from the both ends of the furnace chamber 4 to the outside of the furnace. The furnace chamber 4 and the muffle 5 are mounted so as to be airtight except for an opening 8 described later. In this example, the width of the muffle was 80 cm, the height was 30 cm, and the total length was 326 cm.
[0009]
A plurality of the openings 8 described above are provided on the outer periphery of the muffle. In this embodiment, four circular openings each having a diameter of 6 cm are provided on both side walls of the muffle 5 at intervals, but the openings 8 may be provided on the bottom or top wall of the muffle.
[0010]
Moreover, although not shown in figure, it is made so that the opening degree can be adjusted from the outside of a furnace. The inlets and outlets at both ends of the muffle 5 are covered with openable / closable lids 15, and the object 9 to be heated passes through the muffle 5 on the conveyor belt 6 that circulates in the muffle.
[0011]
Reference numeral 7, a plurality of negative pressure combustion radiant heating pipe provided in the furnace chamber 4 outside the muffle 5 consisted inner cylinder 11 and the outer cylinder 12. The outer side end of the inner tube 11 extending out of the furnace 14 On the other hand, an exhaust port 13 is provided at the outer end of the outer cylinder 12 extending outside the furnace so that the inside of the outer cylinder 12 has a negative pressure rather than the inside of the furnace chamber 4. It has been. The inner end extending to the inner cylinder 11 and the outer cylinder 12 in the furnace chamber 4 is open to the respective furnace chamber 4. Reference numeral 10 denotes a support leg of the heating furnace 1.
[0012]
The heating furnace configured as described above is operated as described below. Fuel and air sent into the inner cylinder from the outer end 14 of the inner cylinder 11 of the negative pressure combustion radiant heating pipe 7 are combusted in the inner cylinder 11, and the combustion waste gas is generated by the negative pressure acting on the exhaust port 13. 12 is exhausted from the exhaust port 13 to the atmosphere.
[0013]
An object 9 to be heated passing on the conveyor 6 and passing through the muffle 5 is heated by the heating tube 7, and the organic evaporated substance evaporated and separated from the object to be heated is negatively passed through the opening 8 and the furnace chamber 4. It is sucked into the pressure combustion radiation heating pipe 7, where it is combusted or pyrolyzed and discharged from the exhaust pipe 13 of the heating pipe into the atmosphere.
[0014]
In addition, the to-be-heated processed material 9 which entered the muffle 5 from the entrance of the left hand in the figure on the conveyor is gradually heated as it travels through the muffle 5, and from the heated processed material as shown in FIG. The amount of evaporative gas gradually increases. In order to allow such a gas to flow smoothly from the muffle through the opening 8 into the furnace chamber and to be sucked into the heating tube 7 efficiently, the opening degree of the opening 8 is adjusted as necessary. For example, the leftmost opening in the figure is half open, the next opening is 3/4 open, and the next two openings are both fully open.
[0015]
One 8 g steel screw was heated to 600 ° C. in the heating furnace described above at 120 kg / h. 1.2 Kg / hour of mineral oil for machining evaporated from the screw of the object to be heated. The evaporated material smoothly flowed out of the muffle 5 from the opening 8 on the side surface of the muffle 5, sucked into the negative pressure combustion radiation heating pipe 7, and combusted together with the fuel sent to the heating pipe. The total amount of combustion of the natural fuel gas sent to all of the heating tubes at this time is 95000 Kcal per hour, and the remaining oxygen amount in the waste gas from the heating tubes is kept at 5% so that the combustion air is supplied to the heating tubes. The supply was adjusted. Methane was not detected in the waste gas discharged from the exhaust port 13, and it was confirmed that the mineral oil evaporated from the screw of the object to be heated was thermally decomposed.
[0016]
After a total of 150 hours of operation, the muffle was heated at 700 ° C. for 2 hours without sending the screws into the muffle and so-called baked. Evaporant from the opening of the muffle was observed, and it was observed that the deposits that had adhered to the walls in the muffle were exposed to high temperatures, evaporated and removed.
[0017]
Example 2
In order to prevent the atmosphere from entering the muffle of the heating furnace, the temperature of the furnace was maintained at 600 ° C. while sending nitrogen gas, and a carbon fiber precursor of 43 kg / hour was heat-treated. Methane was not detected.
[0018]
Example 3
400 Sintering Precursors of Gears made of Structural Chrome Steel Powder Press-molded while sending nitrogen gas into the muffle of the heating furnace so that the atmosphere does not enter through the opening (total weight 200 kg) As a result of heat treatment at 600 ° C., 98% or more of the polymer compound added to the powder during press molding was evaporated and removed. Also, no methane was detected in the exhaust gas.
[0019]
【The invention's effect】
As is apparent from the above description, according to the present invention, when organic substances contained in the object to be heated are evaporated and diffused by heat treatment in the furnace, these substances are almost completely heated in the furnace. It is decomposed and discharged out of the furnace. Moreover, in the method and heating furnace of the present invention, the organic substance and the like are combusted in the furnace and have a secondary effect of being used as a heating source for heating the object to be heated.
[Brief description of the drawings]
FIG. 1 is an explanatory front sectional view of an example of a heating furnace preferably used for achieving the method of the present invention.
2 is an explanatory side cross-sectional view of the heating furnace shown in FIG. 1. FIG.
FIG. 3 is a graph illustratively showing that when the object to be heated passes through the heating furnace, the temperature rises with the passage time, and the amount of evaporated gas from the object to be treated increases accordingly.
[Explanation of symbols]
1-Overall heating furnace 2-Furnace shell 3-Insulation material 4-Furnace room 5-Muffle 6-Conveyor belt 7-Negative pressure combustion radiation heating tube 8-Opening on the outer periphery of the muffle 9-Heated object 10-Support 11 -Inner cylinder 12 of the negative pressure combustion radiant heating tube-Outer cylinder 13 of the negative pressure combustion radiant heating tube-Exhaust port 14-Fuel (combustion air) supply port 15-Muffler inlet and outlet openable lids

Claims

A heat-resistant muffle is provided in the furnace chamber surrounded by the heat insulating material, and the furnace chamber outside the muffle is composed of an inner cylinder and an outer cylinder. From the outer end of the inner cylinder extending outside the furnace, fuel and combustion are used. Provided with a plurality of negative pressure combustion radiant heating tubes provided with an exhaust port at the outer end of the outer cylinder that is supplied with air and extends to the outside of the furnace so that the inside of the outer cylinder has a negative pressure in the outer chamber. The heated object to be heated in the muffle is heated by radiant heating by combustion in the heating pipe, and the gas in the muffle generated from the heated object in accordance with the heating is opened on the outer periphery of the muffle. Through a plurality of openings that can be adjusted , the negative pressure acting on the negative pressure combustion radiant heating tube is led to the outer cylinder of the heating tube, and the gas is thermally decomposed by combustion in the heating tube, and then outside the furnace chamber. Gas from the heat-treated object characterized by exhausting Method of processing.

A heat-resistant muffle is provided in a furnace chamber surrounded by a heat insulating material, and a plurality of openings whose opening degree is adjustable are provided on the outer periphery of the muffle, and an inner cylinder and an outer cylinder are provided in the furnace chamber outside the muffle. The fuel and combustion air are supplied from the outer end of the inner cylinder extending outside the furnace, while the outer cylinder has a negative pressure inside the outer cylinder than the furnace chamber. and a plurality of negative pressure combustion radiant heating tube with an exhaust port which acts so that, after the heated treated in a muffle predetermined period heat treatment by radiation heating by combustion in the heating tube, the heated treatment After the material is taken out of the furnace , the furnace is heated to a temperature higher than the normal operating temperature without placing the object to be heated in the muffle, and the muffle and the deposits in the furnace chamber generated from the object to be heated are removed. Heated by being exposed to high temperature and discharged outside the furnace Vinegar treatment method.

A heat-resistant muffle provided with a furnace chamber surrounded by a heat insulating material, a plurality of openings provided in the furnace chamber, the opening degree of which is adjustable on the outer periphery, and a furnace chamber outside the muffle; The inner cylinder, which consists of an inner cylinder and an outer cylinder , extends from the outer end of the inner cylinder so that fuel and combustion air are supplied into the furnace chamber, while the outer end of the outer cylinder extends outside the furnace. A plurality of negative pressure combustion radiation heating pipes having an exhaust port that works so that the inside of the outer cylinder has a negative pressure more than that in the furnace chamber is processed. Heating furnace.