JP3654858B2

JP3654858B2 - Pyrolysis equipment for oiling of mixed waste plastic

Info

Publication number: JP3654858B2
Application number: JP2001349483A
Authority: JP
Inventors: 宏幸藤村; 寛一伊藤
Original assignee: Ebara Corp
Current assignee: Ebara Corp
Priority date: 2001-10-11
Filing date: 2001-10-11
Publication date: 2005-06-02
Anticipated expiration: 2021-10-11
Also published as: JP2003119472A

Description

【０００１】
【発明の属する技術分野】
この発明は、ＰＶＣなどの塩素系プラスチックを含む混合廃プラスチックの油化等における熱分解装置に係わる。
【０００２】
【従来の技術】
廃プラスチックなどの熱分解において、砂を熱媒体として熱分解流動床と燃焼流動床の間を循環させる周知の２塔循環式流動床は、熱分解で生成するチャー類を燃焼して熱分解の吸熱反応に要する熱量を補う方式で、チャーやタールを自己消化して生成物をガス又は油に集約でき、熱媒体（砂）を常にクリーンに維持できるのでタールによる運転障害を防げ、熱分解ガスに燃焼排ガスが混入せず少量かつ高熱量のガスとなるので以降のガス精製や油化処理が有利になる、などの多くの長所があるが、ＰＶＣなどの塩素系プラスチックを含む廃プラスチックを原料とする場合は、塩素の悪影響を事前に除くためにまず脱塩素を行ってから熱分解する必要がある。この場合、前段の脱塩素温度（約３００℃）が後段の熱分解温度（４００〜７００℃）より低いので、単一循環方式では脱塩素と熱分解に要する熱量をチャー類の燃焼熱で全て補うことはできない。そのために熱分解流動床の加熱を原料の部分燃焼で行うと、生成する熱分解ガスは燃焼排ガスの混入により熱量が低下しガス量が増大するので、以降のガス精製や油化処理が不利になる。
【０００３】
一方、砂を熱媒体として脱塩素と熱分解を行う既存のプロセスとしては、原料をまず高温の砂と一緒にロータリーキルンで脱塩素してから、砂と原料をスクリューコンベアで機械攪拌式熱分解槽に送って熱分解し、次に砂とチャーを流動床に送ってチャーを燃焼させ、ここで加熱した砂の温度を調整してロータリーキルンと機械攪拌式熱分解槽とにそれぞれ戻す方法がある（例えば三菱重工技報Ｖｏｌ．３８，Ｎｏ．１参照）。この方式はロータリーキルン、機械攪拌式熱分解槽、流動床、熱交換器、など多種類の装置で構成する繁雑なフローとなるので、各装置間の砂の搬送、運転管理、装置の維持などが繁瑣にならざるを得ない。
【０００４】
【発明が解決しようとする課題】
この発明は、ＰＶＣなどの塩素系プラスチックを含む混合廃プラスチックの油化等用の熱分解において、脱塩素と熱分解をチャー類の燃焼熱で補い得る循環型流動床の装置を提供し、多種類の装置で構成する既存の上記プロセスの繁雑さを解消することを課題とする。
【０００５】
【課題を解決するための手段】
上記目的を達成するために請求項１に記載の発明は、砂を共通の熱媒体としてそれぞれ脱塩素、熱分解、及び燃焼の各作用を行わせる３つの流動床を円環状に形成すると共に、各流動床の間及び円環中央部に移動層路を設けて、砂が脱塩素流動床から熱分解流動床、燃焼流動床を経て脱塩素流動床に戻る循環と、熱分解流動床から燃焼流動床を経て熱分解流動床に戻る循環の２つの循環を行うように各流動床と移動層路とを連通せしめることにより、燃焼流動床で加熱された砂の適量を脱塩素流動床と熱分解流動床とに分配しそれぞれを所要温度に加熱して原料の脱塩素と熱分解を連続的に行わせることを特徴とする熱分解装置である。
【０００６】
また，請求項２に記載の発明は、請求項１に記載の熱分解装置において、砂を燃焼流動床から脱塩素流動床及び熱分解流動床に移送する２つの移動層路に熱交換器を設けたことを特徴とする。
【０００７】
また、請求項３に記載の発明は、請求項１に記載の熱分解装置において、砂を燃焼流動床から脱塩素流動床及び熱分解流動床に移送する２つの移動層路の出口端に絞り弁を設けて高温砂の配分を調節可能とすることを特徴とする。
【０００８】
【発明の実施の形態】
以下、本発明の実施の形態を実施例の説明図を参照して説明する。図１〜図４は油化プロセスにおける本発明の実施例の説明図で、図１は図２のＰ−Ｐ断面視矢図を、図２は図１のＸ−Ｘ断面図を、図３は図１のＹ−Ｙ断面図を、図４は図１の円弧Ｑ展開図を、それぞれ示す。
【０００９】
図１〜図４に示すように、基本構成は、砂を熱媒体としそれぞれ脱塩素、熱分解、燃焼の役割を果す脱塩素流動床１、熱分解流動床２、燃焼流動床３の３つの流動床を円環状に形成すると共に、各流動床の間に移動層路４、５、６をまた円環中央部に移動層路７を設けてある。各移動層路４、５、６、７をそれぞれ上流側隔壁４Ａ、５Ａ、６Ａ、７Ａと、下流側隔壁４Ｂ、５Ｂ、６Ｂ、７Ｂとにより各流動床と仕切り、各流動床から各移動層路への砂の流入口として移動層路の上流側隔壁の上端面１０の高さを流動床の上面よりＨ低く設定すると共に下流側隔壁の最下部に砂出口１１を設けて幅Ｊを開口することにより、流動床と移動層の比重差が駆動力となって砂は図中の矢印の方向に循環する。すなわち、熱媒体となる砂は各流動床の流動化に伴って図１の矢印に示すように、脱塩素流動床１、移動層路４、熱分解流動床２、移動層路５、燃焼流動床３、移動層路６を経て脱塩素流動床１に戻る第一の循環と、熱分解流動床２、移動層路５、燃焼流動床３、移動層路７を経て熱分解流動床２に戻る第二の循環の、２つの循環を同時に行い得る。さらにこれらの循環過程において、移動層路６、７の下流側隔壁の砂出口１１に設けた絞り弁８、９により開口幅Ｊを縮小して燃焼流動床３から脱塩素流動床１及び熱分解流動床２に供給される高温砂量の配分を調整すると共に、移動層路６、７に水冷式の熱交換器１２、１３を埋設して砂温を調整することにより、脱塩素流動床１及び熱分解流動床２の温度を任意に設定することができる。なお、熱交換器１２、１３の砂との接触は動きの緩慢な移動層内で行われるので管の磨耗は少なく、しかも比較的高い伝熱効率を維持することができる。以上の構成の下に、以下脱塩素と熱分解のプロセスを説明する。
【００１０】
脱塩素流動床１においては、流動化ガスとして水蒸気または熱分解ガスなどの非酸化性ガス３１をガス室４１からガス分散板５１を介して供給して砂を流動化させると共に、燃焼流動床３から移動層路６を経て供給される適量の高温砂で脱塩素流動床１を加熱して流動層温度をＰＶＣの脱塩素温度３００℃付近に維持すると、原料中のＰＶＣの塩素は離脱して塩酸となり、一部の低温分解性プラスチック原料から発生する熱分解ガスを含んで塩酸リッチガス６１となる。このガスを脱塩酸装置１６で洗浄してクリーンな熱分解ガス７１が得られる。図中、１４は原料供給装置、１５は原料中に含まれる金属などの異物排出装置をそれぞれ示す。
【００１１】
熱分解流動床２においては、流動化ガスとして上記同様の非酸化性ガス３２をガス室４２からガス分散板５２を介して供給して砂を流動化させると共に、燃焼流動床３から移動層路７を経て供給される適量の高温砂で熱分解流動床２を加熱して流動床温度を油化の適温４５０℃付近に維持してガス化すれば、油化に適した熱分解ガス６２が得られる。該熱分解ガス６２を前記熱分解ガス７１と合せて周知の油生成装置１７に供給すれば、軽油、灯油、重油などに相当する油を回収することができる。なお、熱分解ガスを油化せずに水素などの低分子ガスとして回収する場合は、熱分解流動床２の温度を７００℃付近に維持するとよい。
【００１２】
燃焼流動床３においては、流動化ガスとして空気３３をガス室４３からガス分散板５３を介して供給して砂を流動化させると共に、熱分解流動床２から移動層路５を介して供給される砂の中のチャー類を燃焼させて砂を昇温させ、前記のように、熱交換器１２、１３で温度調節して脱塩素流動床１と熱分解流動床２にそれぞれ適量を配分する。燃焼排ガス６３から廃熱回収装置１８で回収される水蒸気は、流動化用の非酸化性ガス３１、３２の水蒸気として或いは発電に利用され、燃焼排ガスはさらに排ガス洗浄装置１９で浄化後大気に解放される。尚、油生成装置１７から排出される各種の可燃分残滓は燃焼流動床３に供給して熱利用できることは勿論である。
【００１３】
【発明の効果】
本発明は以上説明したように構成されているので、以下に記載されるような効果を奏する。
【００１４】
ＰＶＣなどの塩素系プラスチックを含む混合廃プラスチックの熱分解プロセスにおいて、脱塩素と熱分解をチャー類の燃焼熱で補い得る循環型流動床方式を提供することにより、チャーやタールを自己消化して円滑な運転を可能とするのみならず、少量で高熱量・高価値の熱分解ガスが得られるので以降のガス精製や油化処理が有利になり、且つまた、従来のプロセスに比べて装置が著しく簡略化され運転管理や装置の維持が容易となる。
【図面の簡単な説明】
【図１】本発明の実施例の説明図で、図２のＰ−Ｐ断面視矢図である。
【図２】本発明の実施例の説明図で、前１のＸ−Ｘ断面図である。
【図３】本発明の実施例の説明図で、図１のＹ−Ｙ断面図である。
【図４】本発明の実施例の説明図で、図１の円弧Ｑ展開図である。
【符号の説明】
１脱塩素流動床
２熱分解流動床
３燃焼流動床
４、５、６、７移動層路
４Ａ、５Ａ、６Ａ、７Ａ上流側隔壁
４Ｂ、５Ｂ、６Ｂ、７Ｂ下流側隔壁
８、９絞り弁
１０上流側隔壁の上端面
１１下流側隔壁の砂出口
１２、１３熱交換器
１４原料供給装置
１５異物排出装置
１６脱塩酸装置
１７油生成装置
１８廃熱回収装置
１９排ガス洗浄装置
３１，３２非酸化性ガス
３３空気
４１，４２，４３ガス室
５１、５２、５３ガス分散板
６１塩酸リッチガス
６２熱分解ガス
６３燃焼排ガス[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal decomposition apparatus for liquefaction of mixed waste plastic including chlorinated plastic such as PVC.
[0002]
[Prior art]
In pyrolysis of waste plastics, etc., the well-known two-column circulating fluidized bed that circulates between the pyrolysis fluidized bed and the combustion fluidized bed using sand as a heat medium burns chars generated by pyrolysis to endothermic reaction of pyrolysis This is a method that compensates for the amount of heat required for the process, and can self-digest char and tar to condense the product into gas or oil, and the heat medium (sand) can always be kept clean. There are many advantages, such as gas purification and oil conversion process being advantageous because the gas becomes a small amount and high heat quantity without mixing exhaust gas, but waste plastics including chlorinated plastics such as PVC are used as raw materials. In this case, it is necessary to first perform dechlorination and then pyrolyze in order to eliminate the adverse effects of chlorine in advance. In this case, since the first stage dechlorination temperature (about 300 ° C.) is lower than the second stage pyrolysis temperature (400 to 700 ° C.), the amount of heat required for dechlorination and pyrolysis in the single circulation system is all consumed by the combustion heat of chars. It cannot be supplemented. For this reason, when the pyrolysis fluidized bed is heated by partial combustion of the raw material, the pyrolysis gas that is produced is reduced in heat quantity due to the mixing of combustion exhaust gas, resulting in an increase in gas quantity. Become.
[0003]
On the other hand, as an existing process for dechlorination and pyrolysis using sand as a heat medium, the raw material is first dechlorinated together with high-temperature sand in a rotary kiln, and then the sand and raw material are mechanically agitated pyrolysis tank using a screw conveyor. And then pyrolyze, then send sand and char to the fluidized bed to burn the char, adjust the temperature of the heated sand and return it to the rotary kiln and mechanically stirred pyrolysis tank respectively ( For example, see Mitsubishi Heavy Industries Technical Report Vol.38, No.1). This method is a complicated flow consisting of various types of equipment such as rotary kilns, mechanically stirred pyrolysis tanks, fluidized beds, heat exchangers, etc., so it is possible to transport sand between each equipment, manage operations, maintain equipment, etc. I have to grow up.
[0004]
[Problems to be solved by the invention]
The present invention provides a circulating fluidized bed apparatus capable of supplementing dechlorination and thermal decomposition with the combustion heat of chars in the thermal decomposition for the liquefaction of mixed waste plastics including chlorinated plastics such as PVC. It is an object of the present invention to eliminate the complexity of the above-described existing process composed of various types of devices.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is characterized in that three fluidized beds are formed in an annular shape for performing dechlorination, thermal decomposition, and combustion, respectively, using sand as a common heat medium, A moving bed is provided between each fluidized bed and in the center of the ring to circulate the sand from the dechlorination fluidized bed to the pyrolysis fluidized bed, through the combustion fluidized bed and back to the dechlorination fluidized bed, and from the pyrolysis fluidized bed to the combustion fluidized bed. The appropriate amount of sand heated in the combustion fluidized bed is transferred to the dechlorinated fluidized bed and the pyrolytic fluidized fluid by connecting each fluidized bed with the moving bed so as to perform two circulations: The thermal decomposition apparatus is characterized in that it is distributed to a floor and each is heated to a required temperature to continuously perform dechlorination and thermal decomposition of the raw material.
[0006]
The invention according to claim 2 is the pyrolysis apparatus according to claim 1, wherein the heat exchanger is provided in two moving bed paths for transferring sand from the combustion fluidized bed to the dechlorination fluidized bed and the pyrolysis fluidized bed. It is provided.
[0007]
Further, the invention according to claim 3 is the thermal cracking apparatus according to claim 1, in which the sand is squeezed at the outlet ends of the two moving bed paths for transferring the sand from the combustion fluidized bed to the dechlorination fluidized bed and the pyrolysis fluidized bed. A valve is provided so that the distribution of hot sand can be adjusted.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the explanatory drawings of the examples. 1-4 is explanatory drawing of the Example of this invention in an oil-ized process, FIG. 1 is PP sectional view arrow view of FIG. 2, FIG. 2 is XX sectional drawing of FIG. FIG. 4 is a YY sectional view of FIG. 1, and FIG. 4 is a developed view of the arc Q of FIG.
[0009]
As shown in FIGS. 1 to 4, there are three basic configurations: dechlorination fluidized bed 1, pyrolysis fluidized bed 2, and combustion fluidized bed 3 that play the role of dechlorination, thermal decomposition, and combustion, respectively, using sand as a heat medium. The fluidized bed is formed in an annular shape, and moving bed paths 4, 5, and 6 are provided between the fluidized beds, and a moving bed path 7 is provided in the center of the ring. Each moving bed path 4, 5, 6, 7 is partitioned from each fluidized bed by upstream partition walls 4A, 5A, 6A, 7A and downstream partition walls 4B, 5B, 6B, 7B. The height of the upper end surface 10 of the upstream partition wall of the moving bed channel is set to be H lower than the upper surface of the fluidized bed, and a sand outlet 11 is provided at the lowermost part of the downstream partition wall to open the width J. As a result, the specific gravity difference between the fluidized bed and the moving bed becomes a driving force, and the sand circulates in the direction of the arrow in the figure. That is, the sand as the heat medium is dechlorinated fluidized bed 1, moving bed path 4, pyrolysis fluidized bed 2, moving bed path 5, combustion flow as indicated by the arrows in FIG. The first circulation returning to the dechlorination fluidized bed 1 through the bed 3 and the moving bed 6, the pyrolysis fluidized bed 2, the moving bed 5, the combustion fluidized bed 3, and the moving bed 7 into the pyrolysis fluidized bed 2. Two cycles of the returning second cycle can be performed simultaneously. Further, in these circulation processes, the opening width J is reduced by the throttle valves 8 and 9 provided at the sand outlet 11 of the downstream partition walls of the moving bed passages 6 and 7, and the dechlorination fluidized bed 1 and the thermal decomposition are reduced from the combustion fluidized bed 3. By adjusting the distribution of the amount of hot sand supplied to the fluidized bed 2, the dechlorinated fluidized bed 1 is adjusted by embedding water-cooled heat exchangers 12 and 13 in the moving bed paths 6 and 7 and adjusting the sand temperature. And the temperature of the pyrolysis fluidized bed 2 can be set arbitrarily. In addition, since contact with the sand of the heat exchangers 12 and 13 is performed in a moving layer that moves slowly, there is little abrasion of the tube, and a relatively high heat transfer efficiency can be maintained. The process of dechlorination and thermal decomposition will be described below with the above configuration.
[0010]
In the dechlorination fluidized bed 1, non-oxidizing gas 31 such as water vapor or pyrolysis gas is supplied as a fluidizing gas from a gas chamber 41 through a gas dispersion plate 51 to fluidize sand, and the combustion fluidized bed 3. When the dechlorination fluidized bed 1 is heated with an appropriate amount of high-temperature sand supplied through the moving bed path 6 to maintain the fluidized bed temperature at around the PVC dechlorination temperature of 300 ° C., the chlorine of PVC in the raw material is released. It becomes hydrochloric acid, and it becomes hydrochloric acid rich gas 61 including pyrolysis gas generated from some low temperature decomposable plastic raw materials. This gas is washed by the dehydrochlorination device 16 to obtain a clean pyrolysis gas 71. In the figure, reference numeral 14 denotes a raw material supply device, and 15 denotes a foreign matter discharging device such as a metal contained in the raw material.
[0011]
In the pyrolysis fluidized bed 2, a non-oxidizing gas 32 similar to the above is supplied as a fluidizing gas from the gas chamber 42 via the gas dispersion plate 52 to fluidize the sand, and from the combustion fluidized bed 3 to the moving bed path. If the pyrolysis fluidized bed 2 is heated with an appropriate amount of high-temperature sand supplied via No. 7 and gasified while maintaining the fluidized bed temperature at around 450 ° C, the pyrolysis gas 62 suitable for oiling is obtained. can get. If the pyrolysis gas 62 is combined with the pyrolysis gas 71 and supplied to a well-known oil generator 17, oil corresponding to light oil, kerosene, heavy oil, etc. can be recovered. In the case where the pyrolysis gas is recovered as a low molecular gas such as hydrogen without being converted to oil, the temperature of the pyrolysis fluidized bed 2 may be maintained at around 700 ° C.
[0012]
In the combustion fluidized bed 3, air 33 is supplied as a fluidizing gas from the gas chamber 43 via the gas dispersion plate 53 to fluidize the sand, and also supplied from the pyrolysis fluidized bed 2 via the moving bed path 5. The chars in the sand are burned to raise the temperature of the sand, and the temperature is adjusted by the heat exchangers 12 and 13 as described above, and appropriate amounts are distributed to the dechlorination fluidized bed 1 and the pyrolysis fluidized bed 2, respectively. . The steam recovered from the waste heat recovery device 18 by the waste heat recovery device 18 is used as steam for the non-oxidizing gases 31 and 32 for fluidization or for power generation. The combustion exhaust gas is further purified by the exhaust gas cleaning device 19 and released to the atmosphere. Is done. Needless to say, various combustible residues discharged from the oil generator 17 can be supplied to the combustion fluidized bed 3 and used as heat.
[0013]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0014]
By providing a circulating fluidized bed system that can compensate for dechlorination and thermal decomposition with the combustion heat of chars in the thermal decomposition process of mixed waste plastics including chlorinated plastic such as PVC, char and tar are self-digested. Not only can smooth operation be achieved, but a small amount of high-calorie and high-value pyrolysis gas can be obtained, so that subsequent gas purification and oil conversion treatment are advantageous, and the equipment is more efficient than conventional processes. Remarkably simplified and operation management and maintenance of the apparatus become easy.
[Brief description of the drawings]
1 is an explanatory diagram of an embodiment of the present invention, and is a cross-sectional view taken along the line PP in FIG.
FIG. 2 is an explanatory diagram of an embodiment of the present invention, and is a cross-sectional view taken along the line XX of FIG.
3 is an explanatory diagram of an embodiment of the present invention, and is a YY cross-sectional view of FIG. 1. FIG.
4 is an explanatory diagram of the embodiment of the present invention, and is a developed view of the arc Q in FIG. 1. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Dechlorination fluidized bed 2 Pyrolysis fluidized bed 3 Combustion fluidized bed 4, 5, 6, 7 Moving bed channel 4A, 5A, 6A, 7A Upstream partition 4B, 5B, 6B, 7B Downstream partition 8, 8 Throttle valve 10 Upper end surface 11 of upstream partition wall Sand outlets 12 and 13 of downstream partition wall Heat exchanger 14 Raw material supply device 15 Foreign matter discharge device 16 Dehydrochlorination device 17 Oil generation device 18 Waste heat recovery device 19 Exhaust gas cleaning device 31, 32 Non-oxidizing property Gas 33 Air 41, 42, 43 Gas chamber 51, 52, 53 Gas dispersion plate 61 Hydrochloric acid rich gas 62 Pyrolysis gas 63 Combustion exhaust gas

Claims

Three fluidized beds are formed in an annular shape for performing dechlorination, thermal decomposition, and combustion, respectively, using sand as a common heat medium, and moving bed paths are provided between the fluidized beds and in the center of the annular shape. The sand is circulated from the dechlorination fluidized bed to the pyrolysis fluidized bed, the circulation returning to the dechlorination fluidized bed through the combustion fluidized bed, and the circulation returning to the pyrolysis fluidized bed from the pyrolysis fluidized bed through the combustion fluidized bed. By connecting each fluidized bed to the moving bed, the appropriate amount of sand heated in the combustion fluidized bed is distributed to the dechlorinated fluidized bed and the pyrolysis fluidized bed, and each is heated to the required temperature to remove the raw material. A thermal decomposition apparatus for oiling mixed waste plastics, characterized by continuously performing chlorine and thermal decomposition.

The thermal decomposition apparatus according to claim 1, wherein a heat exchanger is provided in two moving bed paths for transferring sand from the combustion fluidized bed to the dechlorination fluidized bed and the pyrolysis fluidized bed.

2. The distribution of hot sand can be adjusted by providing a throttle valve at the outlet end of two moving bed paths for transferring sand from a combustion fluidized bed to a dechlorinated fluidized bed and a pyrolysis fluidized bed. The thermal decomposition apparatus as described in.