かくして、本発明によれば、下記の１〜８の発明を提供する：
１．少なくとも２塔式の吸着塔の１塔に於いて、揮発性有機化合物（以下ＶＯＣ）及び水 分を含有する空気を相対的低温でＶＯＣ吸着塔に導入してＶＯＣ選択型吸着剤と接触させてＶＯＣを吸着剤に吸着させて空気を系外に放出し、吸着したＶＯＣを相対的高温で窒素を使用して脱着して、ＶＯＣ処理ガスを減容濃縮し、減容濃縮したＶＯＣガスを少なくとも２塔式の吸着塔の１塔に於いて、揮発性有機化合物及び水分を含有する窒素を加圧して水分吸着塔に導入して水分選択型吸着剤と接触させて水分を吸着剤に吸着させてＶＯＣと分離し、続いて最寒冷温度になるように冷却器で冷却してＶＯＣを液化回収し、流過する低ＶＯＣ、低水分濃度の窒素を減圧して、他の水分吸着した水分選択型吸着剤吸着塔に導入して吸着剤と接触させて水分を吸着剤から脱着させて水分吸着剤を再生し、水分が破過する前に塔を切り替えて水分除去し、流過した窒素を水分除去した後、ＶＯＣ選択型吸着剤の高温再生に使用する温度スイング法ＶＯＣ濃縮、低温液化ＶＯＣ回収方法。
２．上記１において、少なくとも２塔式のＶＯＣ選択型吸着剤を充填したＶＯＣ吸着塔の替わりに、低温吸着ゾーンと高温再生ゾーンを有するローター式のＶＯＣ吸着塔を使用し、高温再生ゾーンのパージガスに窒素を使用し、低温液化凝縮器でＶＯＣを液化回収した後、流過した窒素を水分除去後、ＶＯＣ選択型吸着剤の高温再生に使用する、温度スイング法ＶＯＣ濃縮、低温液化ＶＯＣ回収方法。
３．同じく上記１において、少なくとも２塔式のＶＯＣ選択型吸着剤を充填したＶＯＣ吸着塔の替わりに、低温吸着ゾーンと高温再生ゾーンを有するローター式のＶＯＣ吸着塔を使用し、高温再生ゾーンのパージガスに高温空気を使用し、低温液化凝縮器でＶＯＣを液化回収した後、流過した不凝縮ＶＯＣおよび水分を含有する空気をＶＯＣ選択型吸着剤の低温吸着ゾーンに還流する、温度スイング法ＶＯＣ濃縮、低温液化ＶＯＣ回収方法。
４．ＶＯＣ選択型吸着剤が、シリカライト、ＵＳＭ、β、ＵＳＹ、ＭＰＳからなる群より選ばれる一種以上である、上記１記載のＶＯＣ、水分含有空気からの水分除去後の温度スイング法ＶＯＣ濃縮、低温液化ＶＯＣ回収方法。
５．水分選択型吸着剤が、Ｋ−Ａ、Ｎａ−Ａ、Ｎａ−Ｋ−Ａ及びＣａ−Ａからなる群より 選ばれる一種以上である、上記１記載のＶＯＣ、水分含有空気からの水分除去後の低温液化ＶＯＣ回収方法。
６．水分選択型吸着剤が、表面が液相で有機ケイ素化合物の加水分解生成物によりシリカ コートされたＫ−Ａ、Ｎａ−Ａ、Ｎａ−Ｋ−Ａ及びＣａ−Ａからなる群より選ばれる一種以上である、上記１記載のＶＯＣ、水分含有空気からの水分除去後の低温液化ＶＯＣ回収方法。
７．水分選択型吸着剤が、表面が気相で有機ケイ素化合物の加水分解生成物によりシリカ コートされたＫ−Ａ、Ｎａ−Ａ、Ｎａ−Ｋ−Ａ及びＣａ−Ａからなる群より選ばれる一種以上である、上記１記載のＶＯＣ、水分含有空気からの水分除去後の低温液化ＶＯＣ回収方法。
８．水分選択型吸着剤が、ハニカム形成された、上記１〜７のいずれか一に記載の水分除去、冷熱の回収を行う、低温液化ＶＯＣ回収方法。
Thus, according to the present invention, the following inventions 1 to 8 are provided:
1. In one of at least two towers, an air containing a volatile organic compound (hereinafter referred to as VOC) and water is introduced into the VOC adsorption tower at a relatively low temperature and brought into contact with the VOC selective adsorbent. VOC is adsorbed by an adsorbent, air is released to the outside of the system, and the adsorbed VOC is desorbed using nitrogen at a relatively high temperature to reduce and concentrate the VOC processing gas, and to reduce at least the reduced and concentrated VOC gas. in 1 column of the adsorption tower of the double column, a volatile organic compound Mono及 beauty a nitrogen containing water pressurized by introducing into water adsorption tower water selective adsorbent adsorbent moisture in contact with Adsorption and separation from VOC, followed by cooling with a cooler to reach the coldest temperature, liquefying and collecting VOC, reducing low VOC and low moisture concentration nitrogen flowing through, adsorbing other moisture It is introduced into a moisture-selective adsorbent adsorption tower and brought into contact with the adsorbent to remove moisture. The temperature used to regenerate the moisture adsorbent by desorbing from the adsorbent, switching the tower to remove the moisture before the moisture breaks through, removing the nitrogen that has passed through, and then regenerating the VOC selective adsorbent at a high temperature Swing method VOC concentration, low temperature liquefied VOC recovery method.
2. In the above SL 1, the VOC adsorption towers instead filled at least two tower of VOC selective adsorbent, using VOC adsorption tower of the rotor type having a low temperature adsorption zone and high temperature zone, the purge gas of the hot regeneration zone A temperature swing method VOC concentration and low temperature liquefied VOC recovery method, in which nitrogen is used to liquefy and recover VOC in a low temperature liquefaction condenser, and then the nitrogen that has passed is removed from the water, and then used for high temperature regeneration of the VOC selective adsorbent.
3. In the above SL 1 Similarly, the VOC adsorption towers instead filled at least two tower of VOC selective adsorbent, using VOC adsorption tower of the rotor type having a low temperature adsorption zone and high temperature zone, a purge gas of the hot regeneration zone Temperature swing method VOC concentration in which high-temperature air is used for liquefaction and VOC is liquefied and collected in a low-temperature liquefaction condenser, and then air containing non-condensed VOC and water that has passed through is returned to the low-temperature adsorption zone of the VOC selective adsorbent. Low temperature liquefied VOC recovery method.
4 . The VOC selective adsorbent is at least one selected from the group consisting of silicalite, USM, β, USY, MPS, VOC according to 1 above , temperature swing method VOC concentration after removing moisture from moisture-containing air, low temperature Liquefied VOC recovery method .
5 . Moisture selective adsorbent, K-A, is Na-A, one or more selected from the group consisting of Na-K-A and Ca-A, according to the above item 1, wherein VOC, after removal of water from moisture-laden air Low temperature liquefied VOC recovery method .
6 . One or more kinds of moisture-selective adsorbents selected from the group consisting of KA, Na-A, Na-KA and Ca-A whose surfaces are in a liquid phase and silica-coated with a hydrolysis product of an organosilicon compound in it, the one wherein the VOC, low-temperature liquefied VOC recovery method after removal of water from the moisture-containing air.
7 . One or more kinds of moisture-selective adsorbents selected from the group consisting of KA, Na-A, Na-KA and Ca-A whose surfaces are in the gas phase and silica-coated with hydrolysis products of organosilicon compounds in it, the one wherein the VOC, low-temperature liquefied VOC recovery method after removal of water from the moisture-containing air.
8 . 8. A low-temperature liquefied VOC recovery method in which a moisture-selective adsorbent is formed in a honeycomb and performs water removal and cold recovery as described in any one of 1 to 7 above .
本方法においてはＶＯＣと水分を含有する原料ガスを、室温近傍の相対的低温でＶＯＣ選択型吸着剤で吸着して、無害化した空気を系外に放出し、吸着したＶＯＣを相対的高温で窒素を使用して、ＶＯＣを脱着して４〜１２倍程度に減容濃縮するため、後段の低温液化ＶＯＣ回収装置が小型化でき、パージガスとして窒素を使用することから、高温再生時の回収ＶＯＣの劣化、ＶＯＣ吸着剤の劣化を回避でき、またＶＯＣ回収時の引火、爆発等も回避できる。大気圧近傍の減容濃縮されたＶＯＣの回収では、ＶＯＣを殆ど吸着しない水分吸着剤を充填された吸着塔で行われ、ＶＯＣを除去された窒素は前段のＶＯＣ吸着剤の再生に使用されるため、本方法においてはＶＯＣ含有窒素中のＶＯＣを室温以下の低温で 液化、回収をすることが出来る。このため回収工程は窒素雰囲気で実施されるため安全であり、またＶＯＣは劣化することなく回収され、ＶＯＣ吸着剤も劣化されることがない。本方法を採用することにより、コンパクトで、窒素雰囲気で操作される安全な操作で、省エネルギーの、回収溶剤及び吸着剤の劣化のないＶＯＣの回収装置を提供することが可能である。
In this method, a raw material gas containing VOC and moisture is adsorbed by a VOC selective adsorbent at a relatively low temperature near room temperature, detoxified air is released out of the system, and the adsorbed VOC is released at a relatively high temperature. Since VOC is desorbed using nitrogen and the volume is reduced to about 4 to 12 times, the downstream low-temperature liquefied VOC recovery device can be miniaturized , and nitrogen is used as the purge gas. Deterioration, VOC adsorbent deterioration, and ignition, explosion, etc. during VOC recovery can be avoided. Recovery of volume-reduced and concentrated VOC near atmospheric pressure is performed in an adsorption tower filled with a moisture adsorbent that hardly adsorbs VOC, and the nitrogen from which VOC has been removed is used to regenerate the VOC adsorbent in the previous stage. Therefore, in this method, VOC in the VOC-containing nitrogen can be liquefied and recovered at a low temperature below room temperature. Therefore, the recovery process is safe because it is performed in a nitrogen atmosphere, and VOC is recovered without deterioration, and the VOC adsorbent is not deteriorated. By adopting this method, it is possible to provide a VOC recovery apparatus that is compact, safe and operated in a nitrogen atmosphere, and that saves energy and does not deteriorate the recovered solvent and adsorbent.
［ＰＳＡ−ＶＯＣ低温液化回収］
第１ステップ（Ａ塔−吸着工程、Ｂ塔−向流パージ工程）
図１に於いて、ＶＯＣ、水分を含有する窒素を流路１２、ブロワー１３からバルブ１４ ａを通じて水分／ＶＯＣ選択性の高い水分吸着剤１６の充填された水分吸着塔１５ａに、吸着圧力約１１０〜１５０ｋＰＡで供給されると水分のみが選択的に吸着されてＶＯＣを含有する室温、超乾燥状態の窒素が塔後方から流過し、減圧弁１７ａ、バルブ１８ａを通じて蓄熱材２０の充填された蓄熱材充填塔１９ａに供給される。この時、塔１９ａは前回の再生工程で回収された冷熱により冷却されており、ＶＯＣ含有、室温の乾燥窒素と接触して、蓄熱材２０は昇温し、乾燥窒素は冷却される。流路２２から流過した低温、ＶＯＣ含有乾燥窒素はチラーユニット２３で最寒冷に冷却されて、流路２５からＶＯＣが液化回収される。未回収ＶＯＣを含有する低温、超乾燥窒素は流路２４から蓄熱材２０の充填された蓄熱材充填塔１９ｂに供給され蓄熱材２０は冷却されて、乾燥窒素は昇温する。昇温した乾燥窒素はバルブ１８ｂ、減圧弁１７ｂを通じて水分吸着剤１６の充填された水分吸着塔１５ｂに向流に供給される。ここで吸着塔１５ｂは、バルブ２１ｂを通じて真空ポンプ２６で排気されるため、再生圧力約５０〜８０ｋＰａの低圧で吸着された水分は脱着して再生される。ここで蓄熱材としては０．５〜１０ｍｍφの鉄、アルミニュウム等の金属球で構成される。流過した水分含有窒素はチラーユニット２７で冷却されて流路２８から水分が除去され、ヒータ２９にパージガスとして還流する。
[PSA-VOC low temperature liquefaction recovery]
First step (A tower-adsorption process, B tower-countercurrent purge process)
In FIG. 1, the adsorption pressure of about 110 is applied to the moisture adsorption tower 15a filled with the moisture adsorbent 16 having a high moisture / VOC selectivity from the flow path 12 and the blower 13 through the valve 14a. When supplied at ˜150 kPA, only moisture is selectively adsorbed and room temperature and ultra-dry nitrogen containing VOC flows from the rear of the tower, and the heat storage material 20 is filled with the heat storage material 20 through the pressure reducing valve 17a and the valve 18a. It is supplied to the material packed tower 19a. At this time, the tower 19a is cooled by the cold heat collected in the previous regeneration step, and comes into contact with dry nitrogen at room temperature containing VOC, so that the heat storage material 20 is heated and the dry nitrogen is cooled. The low-temperature, VOC-containing dry nitrogen flowing from the flow path 22 is cooled to the coldest in the chiller unit 23, and the VOC is liquefied and recovered from the flow path 25. The low-temperature and ultra-dry nitrogen containing unrecovered VOC is supplied from the flow path 24 to the heat storage material packed tower 19b filled with the heat storage material 20, the heat storage material 20 is cooled, and the dry nitrogen is heated. The heated dry nitrogen is supplied countercurrently to the moisture adsorption tower 15b filled with the moisture adsorbent 16 through the valve 18b and the pressure reducing valve 17b. Here, since the adsorption tower 15b is exhausted by the vacuum pump 26 through the valve 21b, the moisture adsorbed at a low pressure of about 50 to 80 kPa is desorbed and regenerated. Here, the heat storage material is composed of metal balls such as iron or aluminum having a diameter of 0.5 to 10 mm. The water-containing nitrogen that has passed through is cooled by the chiller unit 27 to remove the water from the flow path 28 and return to the heater 29 as a purge gas.
［ＰＳＡ−ＶＯＣ低温液化回収］
引き続き、図１に於いて、アセトン、水分を含有する窒素を流路１２、ブロワー１３か らバルブ１４ａを通じて水分／アセトン選択性の高い水分吸着剤１６の充填された水分吸 着塔１５ａに、吸着圧力約１１０〜１５０ｋＰＡで供給されると水分のみが選択的に吸着されてアセトンを含有する２５℃、露点−６８℃の超乾燥状態の窒素が塔後方から流過し、減圧弁１７ａ、バルブ１８ａを通じて蓄熱材２０の充填された蓄熱材充填塔１９ａに供給される。この時、塔１９ａは前回の再生工程で回収された冷熱により−５５〜−６０℃に冷却されており、アセトン含有乾燥窒素と接触して、蓄熱材２０は昇温し、乾燥窒素は−５５℃に冷却される。流路２２から流過した低温、アセトン含有乾燥窒素はチラーユニット２３で−６０℃に冷却されて、流路２５からアセトンが液化回収される。アセトン濃度１，４００ｐｐｍの未回収アセトンを含有する低温、超乾燥窒素は流路２４から蓄熱材２０の充填された蓄熱材充填塔１９ｂに供給され蓄熱材２０は冷却されて、乾燥窒素は２０℃に昇温する。昇温した乾燥窒素はバルブ１８ｂ、減圧弁１７ｂを通じて水分吸着剤１６の充填された水分吸着塔１５ｂに向流に供給される。ここで吸着塔１５ｂは、バルブ２１ｂを通じて真空ポンプ２６で排気されるため、再生圧力約５０〜８０ｋＰａの低圧で、吸着された水分は脱着して再生される。ここで蓄熱材としては０．５〜１０ｍｍφの鉄、アルミニュウム等の金属球で構成される。真空ポンプ２６から流過した水分含有窒素はチラーユニット２７で５℃に冷却されて、流路２８から水分が液化除去されて、乾燥窒素は再生用パージガスとしてヒータ２９に還流する。
[PSA-VOC low temperature liquefaction recovery]
Subsequently, in FIG. 1, acetone and nitrogen containing water are adsorbed from the flow path 12 and the blower 13 through the valve 14a to the water adsorption tower 15a filled with the moisture adsorbent 16 having high moisture / acetone selectivity. When supplied at a pressure of about 110 to 150 kPA, only moisture is selectively adsorbed, and acetone containing 25 ° C. and dew point −68 ° C. ultra-dry nitrogen flows from the rear of the column, and the pressure reducing valve 17a and valve 18a And supplied to the heat storage material filling tower 19a filled with the heat storage material 20. At this time, the column 19a is -55 by cold recovered in the last regeneration step - 60 ° C. and cooled to, in contact with the acetone containing dry nitrogen, the heat storage material 20 is heated, dry nitrogen is -55 Cool to ° C. The low-temperature, acetone-containing dry nitrogen flowing through the flow path 22 is cooled to −60 ° C. by the chiller unit 23, and acetone is liquefied and recovered from the flow path 25. Low-temperature, ultra-dry nitrogen containing unrecovered acetone with an acetone concentration of 1,400 ppm is supplied from the flow path 24 to the heat storage material packed tower 19b filled with the heat storage material 20, the heat storage material 20 is cooled, and the dry nitrogen is 20 ° C. The temperature rises to The heated dry nitrogen is supplied countercurrently to the moisture adsorption tower 15b filled with the moisture adsorbent 16 through the valve 18b and the pressure reducing valve 17b. Here, since the adsorption tower 15b is exhausted by the vacuum pump 26 through the valve 21b, the adsorbed moisture is desorbed and regenerated at a regeneration pressure of about 50 to 80 kPa. Here, the heat storage material is composed of metal balls such as iron or aluminum having a diameter of 0.5 to 10 mm. The water-containing nitrogen flowing from the vacuum pump 26 is cooled to 5 ° C. by the chiller unit 27, the water is liquefied and removed from the flow path 28, and the dry nitrogen returns to the heater 29 as a regeneration purge gas.
次に、最近普及しているハニカムロータを使用し、ＶＯＣを減容濃縮した後、ＰＳＡ−ＶＯＣで液化回収する方法のフローシートを図２に示す。ＶＯＣとしてトルエン濃度５，０００ｐｐｍを含有する空気１５０ｍ３Ｎ／ｈを流路３１からＵＳＹハニカム３４の充填したハニカムロータ３３に供給して、吸着ゾーン３３ａにおいて出口トルエン濃度１００ｐｐｍになるように除去し、流路３２、ブロワー３５から系外に放出される。吸着したトルエンは脱着ゾーン３３ｂにおいて、脱着工程のパージガスとして温度１２０℃、流量２０ｍ３Ｎ／ｈの高温窒素を使用し、ヒータ２９から供給して脱着し、ブロワー１１、流路１２からＰＳＡ−ＶＯＣに、流量２０ｍ３Ｎ／ｈ、トルエン濃度３０，０００ｐｐｍで供給される。水分選択型吸着剤１６としては最も性能の高いＫ−Ａ（１０ｎｍ）をハニカ ムとして使用した。ＰＳＡ−ＶＯＣ液化回収ユニットにおいて不凝結ガス濃度５０ｐｐｍまで除去され、水分含有窒素はチラーユニット２７で露点５℃まで冷却され、水分は流路２８から系外に除去される。窒素をパージガスに使用することから回収トルエンおよびＵＳＹの劣化は回避された。ハニカムロータでは流量の約５％がリークすることから、窒素を１ｍ３Ｎ／ｈ程度を補充した。
Next, FIG. 2 shows a flow sheet of a method of using a recently popular honeycomb rotor and reducing and concentrating the volume of VOC and then liquefying and recovering with PSA-VOC. 150 m 3 N / h of air containing a toluene concentration of 5,000 ppm as VOC is supplied from the flow path 31 to the honeycomb rotor 33 filled with the USY honeycomb 34 and removed so as to have an outlet toluene concentration of 100 ppm in the adsorption zone 33a. 32, discharged from the blower 35 to the outside of the system. In the desorption zone 33b, the adsorbed toluene is supplied from the heater 29 and desorbed using high-temperature nitrogen at a temperature of 120 ° C. and a flow rate of 20 m 3 N / h as a purge gas in the desorption process, and is discharged from the blower 11 and the flow path 12 to the PSA-VOC. It is supplied at a flow rate of 20 m3 N / h and a toluene concentration of 30,000 ppm. As the moisture selective adsorbent 16, KA (10 nm) having the highest performance was used as a honeycomb. In the PSA-VOC liquefaction recovery unit, the non-condensed gas concentration is removed to 50 ppm, the moisture-containing nitrogen is cooled to a dew point of 5 ° C. by the chiller unit 27, and the moisture is removed from the flow path 28 to the outside of the system. Degradation of recovered toluene and USY was avoided because nitrogen was used as the purge gas. Since about 5% of the flow rate leaked in the honeycomb rotor, nitrogen was supplemented at about 1 m3 N / h.