201231639 六、發明說明： 【發明所屬之技術領域】 本發明係關於一種回收生物氣體中所含有之甲烷的甲烷 回收方法，尤其是關於一種自生物氣體除去雜質並以較高 之回收率回收甲烧的甲烧回收方法及甲烧回收褒置。。 【先前技術】 生物氣體係藉由有機性資源之厭氧性醱酵等而生成，其 組成一般以甲院為主要成分，並含有二氧化碳及其他微量 之氧、氮、硫化氫、矽氧烷等，且除去硫化氫、矽氧烷等 有害雜質而用作鋼爐之熱源或發電機之燃料等。 先前，生物氣體中所含有之雜質係藉由以下除去方法而 除去：藉由高壓水吸收法使c〇2、硫系雜質溶解於水中（例 如參照日本專利特開2006_955丨2號公報），或使其吸附於吸 附劑（例如參照曰本專利特開2002·60767號公報），或使其 作為反應生成物而除去（例如參照日本專利特開2〇〇3_ 277779號公報）’或藉由多級分離膜而使其分離（例如參照 曰本專利特開2009-242773號公報）等。 又，如日本專利特開2006_16439號公報中所記載般將 • 以以及。等作為交換陽離子之X型沸石作為二氧化碳吸附 ' 劑而填充至吸附塔，藉由變壓式吸附法除去二氧化碳及水 而濃縮甲烧。 由於曱烷等以可燃性氣體為主要成分之氣體係用於燃燒 用途，故於自生物氣體獲得之氣體中，可不含硫化氫等有 害物質，而即便含有氧亦無任何問題。因此，先前，以曱 I60670.doc 201231639 炫:為主要成分之生物氣體中所含之氧並非除去之對象。 假3又因某些原因而嘗試降低生物氣體中之氧含量時，使 用觸媒使氧與甲烷反應，但是，若溫度未達約38(rc以 上，則使用了觸媒之甲烷與氧之反應無法充分產生，故為 了加熱氣體而必需極大能量。 又’提出有藉由精製生物氣體以除去二氧化碳等而製成 以曱烷為主要成分之氣體，作為汽車及家庭用發電機等之 燃料電池用燃料氣體而加以利用。就生物氣體之有效利用 之觀點而言，較佳為使精製之生物氣體與主要包含天然氣 之都市氣體混合。 然而，於作為燃料電池用燃料氣體而利用之情形時，由 於氧會促進對天然氣進行水蒸氣改質之觸媒的劣化，故必 須限制作為家庭用發電機之燃料而利用的都市氣體之氧含 量。因此，於將精製之生物氣體與都市氣體混合之情形 時’為了確保燃料氣體之品質’必須將生物氣體之氧含有 率降低至未達10莫耳ppm。 此處’由於即便於高壓下氧溶於水之溶解度亦較小，故 於如日本專利特開2006-95512號公報之高壓水吸收法中， 氧與甲烷之分離在原理上便較為困難。又，於藉由如日本 專利特開2002-60767號公報、日本專利特開2〇〇3·277779號 公報、曰本專利特開2009-242773號公報及曰本專利特開 2006-16439號公報之分離技術而分離氧之情形時，甲烧之 回收率較低。 【發明内容】 160670.doc 201231639 本發月之目的在於提供一種可將氧抑制至特定含量以 下、並且以較高之回收率自生物氣體回收甲烷的甲烷回收 方法及甲貌回收裝置。 本發明係一種甲烷回收方法，其特徵在於：其係自以曱 烷為主要成分、並含有至少氧為雜質之生物氣體回收曱烷 者， 其匕括.吸附除去步驟，其使生物氣體中之石夕氧烧吸附 於吸附劑而除去； 反應除去步驟，其使生物氣體中之硫化氫與金屬氧化物 反應’並作為金屬硫化物而除去； 捕捉步驟，其使生物氣體中之氧與銅-氧化鋅反應，並 作為氧化銅而捕捉；及 濃縮步驟，其藉由變壓式吸附法使生物氣體中之二氧化 奴分離而濃縮甲烷；藉由進行吸附除去步驟、反應除去步 驟捕捉步驟及濃縮步驟而自生物氣體回收曱烧。 根據本發明，藉由吸附除去步驟使生物氣體中之石夕氧烧 吸附於吸附劑而除去’並藉由反應除去步驟使生物氣體中 之硫化氫與金屬氧化物反應並作為金屬硫化物而除去。於 捕捉步驟中’使生物氣體中之氧與銅，氧化鋅反應並作為 ，化銅而捕捉。於濃縮步驟中，藉由變壓式吸附法將生物 氣體中之二氧化碳分離而濃縮甲烷。 藉由進行該等各步驟，可將氧抑制至特定含量以下、例 如10 ppm以下，並且以較高之回收率自生物氣體回收曱 烷。 160670.doc 201231639 又，於本發明中，較佳為，於上述捕捉步驟中，於 200 C〜300 C之溫度條件下使被處理氣體與銅氧化鋅接 觸。 根據本發明，於上述捕捉步驟中，於2〇〇〇c〜3〇(rc之溫 度條件下使被處理氣體與銅_氧化鋅接觸。 藉此，相較於使氧與甲烷反應之方法，可以較低之溫度 自生物氣體除去氧。 又，於本發明中，較佳為，於上述濃縮步驟中，利用加 壓使生物氣體中之二氧化碳吸附於吸附劑，並藉由設為大 氣壓而使二氧化碳自吸附劑脫離。 根據本發明，於上述濃縮步驟中，由於利用加壓使生物 氣體中之二氧化碳吸附於吸附劑，並藉由設為大氣壓而使 二氧化碳自吸附劑脫離，故可高效地分離二氧化碳。 又，於本發明中，較佳為，上述捕捉步驟於上述反應除 去步驟之後進行。 根據本發明，於上述捕捉步驟中，由於導入除去了硫化 氫之生物氣體，故不存在硫化氫與銅-氧化鋅反應，從而 不會阻礙氧與銅-氧化鋅之反應。 又，本發明係一種甲烷回收裝置，其特徵在於：其係自 以甲烷為主要成分、並含有至少氧為雜質之生物氣體回收 甲燒者， 其包括.吸附塔，其使生物氣體中之矽氧烷吸附於吸附 劑而除去； 硫化氫反應塔，其使生物氣體中之硫化氫與金屬氧化物 160670.doc 201231639 反應，並作為金屬硫化物而除去； 脫氧反應塔’其使生物氣體中之氧與銅-氧化鋅反應， 並作為氧化銅而捕捉；及 變壓式吸附裝置’其藉由變壓式吸附法使生物氣體中之 二氧化碳分離而濃縮甲院；藉由使吸附塔、硫化氫反應 塔、脫氧反應塔及變壓式吸附裝置運作而自生物氣體回收 甲烷。 根據本發明’利用吸附塔使生物氣體中之矽氧烷吸附於 吸附劑而除去，並利用硫化氫反應塔使生物氣體中之硫化 氫與金屬氡化物反應並作為金屬硫化物而除去。利用脫氧 反應塔，使生物氣體中之氧與銅-氧化鋅反應並作為氧化 銅而捕捉。利用變壓式吸附裝置，藉由變壓式吸附法分離 生物氣體中之二氧化碳而濃縮甲烷。 藉由使該#各塔及裝置運作，可將氧抑制至特定含量以 下、例如10 ppm以下，並且以較高之回收率自生物氣體回 收曱烷。 又，於本發明中，較佳為，進而包括如下氫導入裝置： 將氫導入至脫氧反應塔内，使藉由反應而生成之氧化銅還 原。 根據本發明，由於氫導入裝置將氫導入至脫氧反應塔 内，使藉由反應而生成之氧化銅還原，故可使氧化銅·氧 化鋅再生為銅-氧化辞。 又，於本發明中，較佳為，將預先利用上述硫化氫反應 塔除去了硫化氫之生物氣體導入至上述脫氧反應塔。 160670.doc 201231639 根據本發明，由於將預先利用上述硫化氫反應塔除去了 硫化氫之生物氣體導入至上述脫氧反應塔，故硫化氫不與· 上述脫氧反應塔内之銅-氧化辞反應，從而不會阻礙氧與 銅-氧化鋅之反應。 【實施方式】 本發明之目的、特點及優點可藉由下述之詳細說明與圖 式而明確。 以下’以圖式為參考’對本發明之較佳實施形態進行詳 細說明。 本發明係自生物氣體回收曱烷之回收方法。生物氣體係 自例如污水處理場之污泥等中產生之氣體，其主要成分包 含約60莫耳％之甲烷及約40莫耳％之二氧化碳，除此以外 含有微量之氧、氮、硫化氫及矽氧烷等。 於使用生物氣體作為汽車用或都市氣體用氣體之情形 時，曱烷濃度較佳為95莫耳％以上。於作為汽車用氣體而 利用之情形時，由於係壓縮而使用，故必須避免作為生物 氣體之主要雜質之一氧化碳壓縮而液化，因此需要曱烧濃 度為95莫耳％以上。又，於作為都市氣體用氣體而利用之 情形時，若濃度較低則熱量較低，故與汽車用一樣，需要 甲烷濃度為95莫耳％以上。 以在，雖然生才勿氣體係作為用以燃燒之燃料氣體而利 用’故不存在將氧作為雜f而除去之情形，但於面向燃料 電池之制中，由於生物氣體中所含之氧會使水蒸氣改質 用之觸媒劣化’故必須除去氧。根據本發明，可將氧抑制 160670.doc 201231639 至特定含量以下、例如10 ppm以下，並且以較高之回收 率、例如80%以上之回收率回收甲烧。 圖1係表示作為本發明之實施之一形態之甲烷回收方法 的步驟圖。本發明之曱烷回收方法包括：吸附除去步驟， 其為了自生物氣體除去雜質、並以較高之回收率回收曱院 而（步驟S1)除去>5夕氧院；反應除去步驟，其（步驟$ 2)除去 硫化氫；捕捉步驟，其（步驟S3)捕捉氧；及濃縮步驟，其 (步驟S4)濃縮曱烷。 (步驟S1)吸附除去步驟 於吸附除去步驟中，藉由將吸附劑填充至吸附塔並將生 物氣體導入至吸附塔内，而使作為生物氣體中所含之雜質 之矽氧烷吸附於吸附劑，從而自生物氣體中除去矽氧烷。 作為吸附劑，係易於吸附矽氧烷者，亦可係不易吸附曱烷 者，例如使用活性炭。活性炭雖然可使用椰殼及木炭等天 然活性炭、瀝青及石油焦等礦物活性炭等，但由於活性炭 無法再生而須更換新劑，故較佳為儘量採用廉價之椰殼活 性炭。 較佳為，藉由吸附除去步驟將生物氣體中之矽氧烷之含 量設為2mg/Nm3以下，更佳為丨mg/Nm3以下。 (步驟S2)反應除去步驟 於反應除去步驟中，藉由將金屬氧化物填充至反應塔並 將生物氣體導人至吸附塔内，而將生物氣體中所含之雜質 即硫化氫、硫醇等硫系化合物作為金屬硫化物而固定於反 應塔内。作為金屬氧化物，可使用氧化鐵、氧化銅、氧化 160670.doc 201231639 辞等。例如’若該等金屬氧化物與硫化氫進行化學反應， 則分別變為硫化鐵、硫化銅、硫化鋅等金屬硫化物。 較佳為藉由反應除去步驟將生物氣體中之硫化氫之含量 設為3莫耳ppm以下，更佳為1莫耳ppm以下。 藉由如上述般進行吸附除去步驟及反應除去步驟，可除 去生物氣體中之矽氧烷及硫化氫。 再者，吸附除去步驟與反應除去步驟中，可先進行任一 步驟’並未特別限定步驟順序。 又，亦可於吸附除去步驟及反應除去步驟之前，進行壓 縮生物氣體之壓縮步驟及除去生物氣體中之水分之除濕步 驟。於除濕步驟中，例如，將生物氣體於(TC左右冷卻而 脫水。又，亦可利用氧化鋁球、沸石（MS-3A)等吸附水分 而脫水，亦可將氧化鋁球、沸石等水分吸附劑填充至吸附 4並導人生物氣體。進而，亦可將氧化銘球、沸石等水分 吸附劑填充至用以吸附除去矽氧烷之吸附塔，於進行吸附 除去步驟之同時除濕。 (步驟S3)捕捉步驟 於捕捉步驟中，藉由將銅.氧化鋅之混合物作為氧捕獲 劑填充至反應塔，並將除去了石夕氧院及硫化氫之生物氣體 導入至吸附塔内，而將生物氣體中所含雜質之氧作為氧化 銅加以捕捉。 銅-氧化鋅混合物與生物氣體接觸後，生物氣體中之氧 與銅反應而成為氧化鋼，並作為氧化銅氧化鋅混合物而 於反應塔内被捕捉。 I60670.doc 201231639 於捕捉步驟中，使除去了⑦氧烧及硫化氫之被處理氣體 於200 C〜300 C之溫度條件下與鋼_氧化鋅接觸。於此情 形時，即便二氧化碳以3〇〜帆之比率共料被處理氣體 中亦有可月b產生氧化銅生成反應，故相較於使氧與甲烧 反應而使氧含量降低之情形，可減少用以加熱被處理氣體 之能量。 而直接填充至反應塔 雖然銅-氧化鋅混合物可粒子化 但為了使其與導人至塔内之生物氣體之接觸效率提昇，較 佳為使微粒子狀之銅·氧化辞混合物擔載於氧化紹、石夕藻 土等擔載體上而填充至反應塔。 於本發明之捕捉步料所制之銅·氧化料合物，係 藉由利用惰性氣體稀釋後之氫氣將作為甲醇蒸汽重組觸媒 使用者還原而獲得之氧捕獲劑。例如，由於甲醇蒸汽重 組觸媒有市售之氧化銅氧化鋅擔載於氧化銘上者，故使 該甲醇蒸汽重組觸媒與利用纟、氮等惰性氣體稀釋至卜 5%之氫氣於230〜26(rc之溫度條件下接觸，藉此氧化銅 得以還原成為鋼’並作為擔載於氧化紹上之鋼_氧化辞混 合物而獲得。 、較佳為，藉由捕捉㈣將生物氣體中之氧含量設為1〇 ppm 以下’更佳為1 ppm以下。 此處，對用以除去硫化氫之反應除去步驟之實施效果、 及其與捕捉氧之捕捉步驟之關聯性進行說明。 由於硫化氫等硫系化合物吸附於活性炭，故於用以除去 石夕氧烧之吸附除去步驟巾，於制活性炭作為吸附劑之情 160670.doc 201231639 形時，雖然亦可除去些許硫化氫，但並不充分。於省略利 用硫化氫與金屬氧化物之反應的反應除去步驟之情形時， 捕捉步驟中之被處理氣體中會含有硫化氫。若銅_氧化鋅 與硫化氫接觸，則硫化氫還原而產生硫，進而與氧反應而 產生二氧化硫。又，氧化鋅與硫化氫反應而生成硫化鋅。 如此，若捕捉步驟中之被處理氣體中含有硫化氫，則硫化 氫會與銅-氧化鋅反應，故而阻礙氧與銅·氧化鋅之反應， 從而無法充分捕捉氧。 為了使捕捉步驟t之氧與銅-氧化鋅充分反應而使氧含 量為10 ppm以下，僅利用吸附除去步驟而吸附除去硫化氫 並不充分，而利用硫化氫與金屬氧化物之反應的反應除去 步驟則很有必要。 (步驟S4)濃縮步驟 藉由吸附除去步驟、反應除去步驟及捕捉步驟，充分地 除去生物氣體中之雜質即矽氧烷、硫化氫及氧，而藉由濃 縮步驟處理之被處理氣體僅包含曱烷與二氧化碳。於濃縮 步驟中，藉由變壓式吸附法使二氧化碳吸附於吸附劑，從 而獲得濃縮後之高純度甲烷。 於變壓式吸附法中，例如為了自2種物質之混合氣體中 濃縮而獲得1種氣體，使用吸附能力相對於—種物質較高 而相對於另一種物質較低之吸附劑’於高壓下使一種物質 吸附於吸附劑《其後，於低壓下使經吸附一種物質自吸附 劑脫離，從而再生吸附劑。 於濃縮步驟中，將吸附二氧化碳之吸附能力相對較言、 160670.doc •12- 201231639 且吸附甲烧之吸附能力相對較低之吸附劑填充至複數個吸 附塔使塔内之壓力變化並且適時切換所使用之吸附塔， 從而分離二氧化碳與甲烷，並回收高純度之曱烷。 濃縮步驟係基於變壓式吸附法，反覆進行吸附操作與脫 離操作。吸附操作係使填充有吸附劑之吸附塔内之壓力相 對咼於脫離操作時之壓力，於高壓條件下導入除去了矽氧 烷、硫化氫及氧氣之生物氣體^於高壓條件下，雖然二氧 化碳吸附於吸附劑，但曱烷幾乎不吸附於吸附劑，故於吸 附塔内，二氧化碳與曱烷分離，獲得濃縮後之曱烷。若連 續導入生物氣體至1個吸附塔内，則吸附劑中所吸附之二 氧化碳增加，吸附能力下降，故藉由脫離操作再生吸附 劑。 脫離操作係停止生物氣體之導入，並使吸附塔内之壓力 相對低於吸附操作時之壓力，而使吸附劑中所吸附之二氧 化碳自吸附劑脫離。脫離後之二氧化碳向吸附塔外排出。 於使用2個吸附塔之情形時，利用i個吸附塔進行脫離操 作時，另一個吸附塔進行吸附操作，利用各個塔同時進行 吸附操作與脫離操作《而且，於處理特定量之後，切換吸 附操作與脫離操作。藉此，由於任一塔中必然進行著吸附 操作，故可一面再生吸附劑，一面連續進行曱烷之分離濃 縮。 作為二氧化碳之吸附能力較高、曱烷之吸附能力較低之 吸附劑，可使用碳系吸附劑，較佳為碳分子筛。進而，於 根據目標產品氣體組成，例如欲降低產品氣體之所含氮濃 160670.doc 13· 201231639 度之情形時，於原料氣體之所 i之橹报蛀农/又权间時專必須除去 時，除碳分子筛以外亦可積層彿石。 作為吸附操作中之技内之厭 MPU 4“ ° I力P1，例如為大氣壓(0.101 MPa)〜4.0 MPa。柞&眙雜切a丄 為0_ " 纟為脫離刼作中之塔内之虔力P2,例如 為0.001〜0.3]^(其中，1>1>1)2)。 下如：述般經各步驟而獲得之氣體中，氧含量為H) ppm以 =從而獲得甲燒純度例如為98莫耳％以上之富子炫氣 ' 肖本發明之自生物氣體回收甲院之回收裝置進行 說明。本發明之回收裝置，只要係能實施上述回收方法之 裝置，則可為任意構成。 圖2係表示作為本發明之實施之一形態的回收裝置⑽之 構成的概略® °回收裝置1⑽包括I缩機1、除濕裝置2、 ^氧统㈣塔3、硫化氫反應塔4、脫氧反應塔5及變壓式 吸附裝置6,並處理自氣體供給源7供給之生物氣體。氣體 供給源7係、例如污水處理場等產生生物氣體之產生源。 自氣體供給源7供給之包含雜質之生物氣體係藉由壓縮 機1壓縮，並送往用以除去水分之除濕裝置作為除濕裝 置例如可使用冷卻式脫水機、加壓吸附式脫水機、加熱 再生式脫水機等，但較佳為將生物氣體於〇t：左右冷卻而 脫K之冷卻式脫水機。又，亦可使用填充有氧化紹球或沸 石（MS-3A)等水分吸附劑之吸附塔作為用以吸附脫水之、 非使用脫水機之除濕裝置2。又，根據水分量，亦可於用 以吸附矽氧烷之矽氧烷吸附塔3之後的各塔内，積層填充 160670.doc 201231639 氧化紹球、〉弗石等水分吸附劑。 吸附除去矽氧烷之矽氧烷吸附塔3，係如吸附除去步驟 中所說明般’將例如活性炭填充至吸附塔内作為用以吸附 矽氧烷之吸附劑❶反應除去硫化氫之硫化氫反應塔4，係 如反應除去步驟中所說明般，將與硫化氫反應生成金屬硫 化物之金屬氧化物填充至反應塔内。 將除去了矽氧烷與硫化氫之生物氣體導入至脫氧反應塔 5。如捕捉步驟中所說明般，將銅·氧化鋅混合物以擔載於 例如氧化鋁等擔載體上之形態而填充至脫氧反應塔5。導 入後之生物氣體中所含之氧與銅-氧化辞混合物之銅反 應，並作為氧化銅而被捕捉。此時，脫氧反應塔5内係藉 由未圖示之加熱器加熱至2〇〇〜3〇〇。(：。 較佳為進而包括如下氫導入裝置5a :將氫導入至脫氧反 應塔5之塔内而還原氧化銅_氧化鋅，從而再生銅-氧化鋅。 例如，設置利用自脫氧反應塔5之出口返回至入口之循環 路徑的氮氣之旋轉鼓風機，可藉由氫導入裝置“將氫添加 至氮氣中’從而向脫氧反應塔5内提供再生用氫氣。 變壓式吸附裝置6可使用公知之PSA(Pressure Swing Absorption，變壓吸附）裝置，例如使用2塔式pSA裝置。 圖3係表示變壓式吸附裝置6之一例的概略圖。變壓式吸 附裝置6具有第1吸附塔12及第2吸附塔13，並將作為碳系 吸附劑之碳分子篩填充至各吸附塔12、13。 原料配管13f經由切換閥12b、13b與各吸附塔12、13之 入口 12a、13 a連接。吸附塔12、13之入口 12a、13a各自與 160670.doc 201231639 切換閥12c、13c及消音器13e連接，以可向大氣中開放之 方式而構成。又’吸附塔下部均壓配管13g經由切換閥13d 而分別連接於吸附塔13之入口 12a、13a。 吸附塔12、13之出口 12k、13k係各自經由切換閥121、 131與流出配管13〇連接，並經由切換閥12m、13m與洗淨 配管13p連接，並經由切換閥13n與吸附塔上部均壓配管 13q連接。 流出配管13〇經由止回閥13r及手動閥13s而與均壓槽14 連接。均壓槽14經由壓力調節閥14a而與產品槽15連接。 產品槽15係與變壓式吸附裝置6之出口配管15a連接。變壓 式吸附裝置6之吸附壓力係藉由壓力調節閥14a控制。 洗淨配管13t經由流量控制閥13u、流量指示調節計13v 而與洗淨配管13p連接，並調節洗淨配管13p之氣體流量至 固定值，藉此’吸附塔12、13之填充劑得以洗淨至固定程 度。 於變壓式吸附裝置6之第1吸附塔12及第2吸附塔13之各 自之内部’依次進行吸附操作、均壓操作、脫離操作、洗 淨操作及均壓操作。 打開切換閥12b，將所供給之生物氣體導入至第1吸附塔 12 ’又，於第1吸附塔12中，與切換閥12b同時打開的僅有 切換閥121。藉此，藉由第丨吸附塔12中所導入之生物氣體 中之至少一氧化碳吸附於吸附劑而進行吸附操作，而未吸 附於吸附劑之甲烷與二氧化碳分離並經由流出配管13〇自 第1吸附塔12導出。此時’送入至流出配管13〇中之曱烧之 160670.doc 201231639 一部分經由洗淨配管13p、13t、流量控制閥i3u而送入至 第2吸附塔13，於第2吸附塔13中進行洗淨操作。 繼而’關閉切換閥12b、121，打開切換閥Un、nd，進 行使第1吸附塔12與第2吸附塔13之塔内壓力均勻的均壓操 作。 繼而’藉由關閉切換閥⑴、13d，打開切換闕12c，而 進行使包含二氧化碳之雜質自第i吸附塔12之吸附劑脫離 的脫離操作’ @包含二氧化碳之雜質與氣體一起經由消音 器13e排放至大氣中。 此時，於打開切換閥13b之同時，打開手動閥⑴，自均 壓槽14將降低了二氧化碳含量之甲烷氣體通過流出配管 13。導入至第2吸附塔13 ’進行升壓操作及吸附操作。其後 之各操作係以與對第丨吸附塔12之操作相同之方式進行。 藉由於第1吸附塔12、第2吸附塔13之各自之内部依次反 覆進行該等各操作，而獲得包含二氧化碳之雜質之含量降 低後之甲烷氣體。 再者’變壓式吸附裝置6並不限定於圖3所示之構成，塔 數除可為2以外，例如亦可為3塔或4塔，通常為9塔以下。 根據此種回收裝置刚，可自所供給之生物‘體除去 水、石夕氧減硫化狀後，藉由使生物氣體巾之氧盘銅_ 氧化鋅反應而作為氧化鋼加以捕捉，最後藉由變壓式吸附 法分離二氧化碳而獲得經濃縮之高純度甲烷。 ，本發明並不限定於上述之構成，例J可於壓縮機以 後设置硫化氩反應塔4’亦可調轉矽氧烷吸附塔埃硫化氫 160670.doc •17- 201231639 反應塔4之配置順序而設置，亦可調轉脫氧反應塔5與變壓 式吸附裝置6之配置順序而設置。 [實施例1] 假定自污水處理場之污泥產生之生物氣體，並以甲炫 60.0莫耳％、二氧化碳38.7莫耳％、氮0.5莫耳％、水〇.3莫 耳°/。、氧〇.3莫耳％、硫化氫〇.2莫耳％及矽氧烷50 mg/Nm3 之混合氣體為處理對象氣體，以流量450 NL/hr進行供 給。 將處理對象氣體於25 °C下導入至如下石夕氧院吸附塔3 : 於直徑為37 mm之圓筒狀吸附塔内部，積層有〇2 kg作為 脫水劑之氧化鋁球（住友化學股份有限公司製造，khd_ 24)、及〇·5 kg作為矽氧烷之吸附劑之椰殼活性炭（Kuraray Chemical股份有限公司製造，GG)。繼而，將自石夕氧烧吸 附塔3導出之生物氣體於25C下導入至如下硫化氫反應塔 4:於與矽氧烷吸附塔3相同尺寸之反應器之内部，填充有 2.0 kg氧化鋅（Hakusui Tech公司製造之1種JIS規格造粒 品）0 繼而，將1.2 kg氧化銅-氧化鋅觸媒（Siid_Chemie觸媒股 份有限公司製造，MDC-3)導入至與矽氧烷吸附塔3相同尺 寸之脫氧反應塔5,並藉由氫導入裝置&將氫導入至脫氧 反應塔5使氧化銅-氧化鋅觸媒還原而成為銅-氧化鋅混合 物。將脫氧反應塔5之塔内溫度升溫至26〇t為止並保持， 導入自硫化氫反應塔4導出之生物氣體。 繼而，將自脫氧反應塔5導出之生物氣體導入至如下變 160670.doc -18, 201231639 壓式吸附裝置6 :於與矽氧烷吸附塔3尺寸相同之吸附塔内 部’填充有0_6 kg微孔孔徑為3人之碳分子篩（Kuraray Chemical製造，GN_UC_H)。變壓式吸附裝置6之操作與上 述操作相同’將吸附操作中之最高壓力設為〇 8 Mpa，將 脫離操作中之最低壓力設為大氣壓，從而將曱烷與二氧化 碳分離而濃縮。 生物氣體中之二氧化碳及氮之濃度係使用股份有限公司 島津製作所製造的GC-TCD(附有熱傳導性檢測器之氣相層 析儀）進行測定，水分係藉由露點計進行測定，氧濃度係 藉由DELTA F公司製造的微量氧氣濃度計（型號DF_15〇E)進 打測定，矽氧烷濃度係使用島津製作所製造的GC/MS(氣 相層析質量分析計）進行測定，硫化氫濃度係使用島津製 作所製造的GC-FPD(附有火焰光度檢測器之氣相層析儀）進 行測定。 測定自脫氧反應塔5導出之氣體之組成，結果為：曱烷 62·5莫耳％、二氧化碳37莫耳％、氮0.5莫耳°/。及水與氧與 硫化氫與矽氧烷未達1莫耳ppm。 又，自變壓式吸附裝置6導出之產品氣體之甲烷濃度為 98莫耳％之時，甲烷回收率為851%，且產品氣體中之氧 》辰度未達1莫耳ppm。 [實施例2] 父換石夕氧烧吸附塔3與硫化氫反應塔4，即調轉石夕氧烧吸 附步驟與脫硫化氫步驟之順序，除此以外，以與實施例i 相同之方式自處理對象氣體濃縮曱烷。 160670.doc -19- 201231639 自變壓式吸附裝置6導出之產品氣體 耳%之時’甲烷氣體回收率為84 9 二農度為98莫 氣濃度未達1莫耳PPm。 產。口氣體中之氧 [比較例1] 不經由脫氧反應塔，即不進行氧之捕捉步驟 外，以與實施例1相同之方戎白#评A '、匕Λ 自變壓式吸附裝置6導二=象二，^ …時，氣體回收率為84·。:體==广' 濃度為90莫耳ppm。 產。。氣體中之氧 [比較例2] 不經由脫氧反應塔，即不逸杆 …… 不進仃氧之捕捉步驟，並藉由降 低原料流量至370 NL/hr為止，使產品氣體中之氧濃^ 莫耳PPm’除此以外，以與實施例！相同之 氣體濃縮甲烷。 曰〜埋對象 使自變壓式吸附裝置6導出之產品氣體中之氧濃 耳PPm之時，產品氣體之甲烧濃度為99莫耳％以上卞 氣體之回收率為72.4%。 如比較例1般，若欲獲得較高 。α 較円之回收率’則無法降低產 。口軋體中之氧濃度，如比較例2般， * 万又右奴降低產品氣體中 之氧濃度，則甲烷氣體之回收率降低。相對於此，於實施 例1、2中，可將產品氣體中之氧濃度設為未心莫耳卯爪， 並以較高之回收率自生物氣體回收甲烷。 本發明可不脫離其精神或主要特徵，以其他各種形能進 行實施。因此，上述實施形態於所有方面均僅為例示^本 160670.doc •20· 201231639 發明之紅圍係為申請專利範圍中所示者，而絲毫不限定於 說明書正文。進而’屬於申請專利範圍内的變形或變更， 其所有内容均為本發明之範圍内之内容。 【圖式簡單說明】 圖1係表示作為本發明之實施之一形態之甲烷回收方法 的步驟圖。 圖2係表示作為本發明之實施之一形態的回收裝置之構 成的概略圖。 圖3係表示變壓式吸附裝置之一例的概略圖。 【主要元件符號說明】 1 壓縮機 2 除濕裝置 3 矽氧烷吸附塔 4 硫化氫反應塔 5 脫氧反應塔 5a 氫導入裝置 6 變壓式吸附裝置 7 氣體供給源 12 第1吸附塔 12a > 13a 吸附塔入口 12b、12c、12m、13b、13c、 13d、13m、13n、121、131 切換閥 12k、13k 吸附塔出口 13 第2吸附塔 160670.doc -21 · 201231639 13e 消音器 13f 原料配管 13g 吸附塔下部均壓配管 13o 流出配管 13p ' 13t 洗淨配管 13q 吸附塔上部均壓配管 13r 止回閥 13s 手動閥 13t 洗淨配管 13u 流量控制閥 13v 流量指示調節計 14 均壓槽 14a 壓力調節閥 15 產品槽 15a 出口配管 100 回收裝置 SI 除去矽氧烷之吸附除去步驟 S2 除去硫化氫之反應除去步驟 S3 捕捉氧氣之捕捉步驟 S4 濃縮曱烷之濃縮步驟 160670.doc ·22·201231639 VI. Description of the Invention: [Technical Field] The present invention relates to a method for recovering methane from methane contained in a biogas, and more particularly to a method for removing impurities from a biogas and recovering a high recovery rate The recovery method of the A-burn and the recovery of the A-burning. . [Prior Art] The biogas system is produced by anaerobic fermentation of organic resources, and its composition is generally composed of a hospital, and contains carbon dioxide and other traces of oxygen, nitrogen, hydrogen sulfide, helium oxide, and the like. And removing harmful impurities such as hydrogen sulfide and helium oxide and used as a heat source of a steel furnace or a fuel of a generator. Previously, the impurities contained in the biogas were removed by the following removal method: c〇2, a sulfur-based impurity was dissolved in water by a high-pressure water absorption method (for example, refer to Japanese Patent Laid-Open Publication No. 2006_955丨2), or It is adsorbed to the adsorbent (for example, refer to Japanese Laid-Open Patent Publication No. 2002-60767), or is removed as a reaction product (for example, refer to Japanese Patent Laid-Open Publication No. Hei. No. 2-277779). The membrane is separated and separated (for example, see Japanese Patent Laid-Open Publication No. 2009-242773). Further, as described in Japanese Laid-Open Patent Publication No. 2006_16439, The X-type zeolite, which is an exchange cation, is charged as a carbon dioxide adsorbing agent to the adsorption tower, and carbon dioxide and water are removed by a pressure swing adsorption method to concentrate the methylate. Since a gas system containing a flammable gas as a main component such as decane is used for combustion, it is possible to contain a harmful substance such as hydrogen sulfide from a gas obtained from a biogas, and there is no problem even if it contains oxygen. Therefore, previously, I 670 I60670.doc 201231639 Hyun: The oxygen contained in the biogas as the main component is not the object of removal. False 3 For some reasons, when trying to reduce the oxygen content in the biogas, the catalyst is used to react oxygen with methane. However, if the temperature is less than about 38 (rc or more, the reaction of methane with oxygen is used. In order to heat the gas, it is necessary to increase the amount of energy. In addition, it is proposed to produce a gas containing decane as a main component by purifying a biogas to remove carbon dioxide, and to use it as a fuel cell for automobiles and household generators. In view of the effective use of the biogas, it is preferable to mix the purified biogas with the city gas mainly containing natural gas. However, when it is used as a fuel gas for a fuel cell, Since oxygen promotes the deterioration of the catalyst for reforming the natural gas by steam, it is necessary to limit the oxygen content of the city gas used as the fuel for the household generator. Therefore, when the purified biogas is mixed with the city gas, In order to ensure the quality of the fuel gas, the oxygen content of the biogas must be reduced to less than 10 mol ppm. Since the solubility of oxygen in water is small even under high pressure, the separation of oxygen and methane is difficult in principle in the high-pressure water absorption method of Japanese Patent Laid-Open Publication No. 2006-95512. The separation technique of the Japanese Patent Laid-Open Publication No. 2002-60767, the Japanese Patent Laid-Open Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. In the case of separating oxygen, the recovery rate of the smoldering is low. [Summary of the Invention] 160670.doc 201231639 The purpose of this month is to provide a method for suppressing oxygen to a specific content and recovering from biogas at a higher recovery rate. Methane recovery method and method for recovering methane. The present invention relates to a method for recovering methane, which is characterized in that it recovers decane from a biogas containing decane as a main component and containing at least oxygen as an impurity. An adsorption removal step of removing the sulphur oxygen in the biogas by adsorbing it to the adsorbent; and a reaction removing step of reacting the hydrogen sulfide in the biogas with the metal oxide' Removing as a metal sulfide; a capturing step of reacting oxygen in the biogas with copper-zinc oxide and capturing it as copper oxide; and a concentration step of oxidizing the biogas by a pressure swing adsorption method Separating and concentrating methane; recovering the calcination from the biogas by performing the adsorption removal step, the reaction removal step, the capture step, and the concentration step. According to the present invention, the adsorption of the gas in the biogas is adsorbed to the adsorption by the adsorption removal step. And removing the 'hydrogen sulfide in the biogas by the reaction removal step and removing it as a metal sulfide. In the capturing step, 'the oxygen in the biogas is reacted with copper and zinc oxide. Captured by copper. In the concentration step, methane is removed by separating the carbon dioxide in the biogas by a pressure swing adsorption method. By performing the above steps, oxygen can be suppressed to a specific content or less, for example, 10 ppm or less, and decane is recovered from the biogas at a higher recovery rate. Further, in the present invention, preferably, in the above-described capturing step, the gas to be treated is brought into contact with copper zinc oxide at a temperature of from 200 C to 300 C. According to the present invention, in the above-described capturing step, the gas to be treated is brought into contact with copper-zinc oxide at a temperature of 2 〇〇〇c to 3 〇 (the temperature of rc is compared with the method of reacting oxygen with methane, Further, in the present invention, it is preferable that in the concentration step, carbon dioxide in the biogas is adsorbed to the adsorbent by pressurization, and is set to be atmospheric pressure. The carbon dioxide is detached from the adsorbent. According to the present invention, in the concentration step, since carbon dioxide in the biogas is adsorbed to the adsorbent by pressurization, and carbon dioxide is released from the adsorbent by being set to atmospheric pressure, the carbon dioxide can be efficiently separated. Further, in the present invention, preferably, the capturing step is performed after the reaction removing step. According to the present invention, in the capturing step, since hydrogen sulfide-removed biogas is introduced, hydrogen sulfide is not present. The copper-zinc oxide reaction does not hinder the reaction of oxygen with copper-zinc oxide. Further, the present invention is a methane recovery device characterized in that: A biogas recovery combustor containing methane as a main component and containing at least oxygen as an impurity, comprising: an adsorption tower for adsorbing a helium alkane in the biogas to adsorb the adsorbent; and a hydrogen sulfide reaction tower; Hydrogen sulfide in the biogas is reacted with the metal oxide 160670.doc 201231639 and removed as a metal sulfide; the deoxygenation column 'reacts oxygen in the biogas with copper-zinc oxide and is captured as copper oxide; And a pressure swing adsorption device which condenses carbon dioxide in the biogas by a pressure swing adsorption method to concentrate the chamber; by operating the adsorption tower, the hydrogen sulfide reaction tower, the deoxygenation reaction tower and the pressure swing adsorption device The biogas recovers methane. According to the invention, the adsorption of the helioxane in the biogas by the adsorption tower is carried out by adsorption to the adsorbent, and the hydrogen sulfide reaction tower is used to react the hydrogen sulfide in the biogas with the metal halide and as a metal sulfide. And using a deoxidation reaction tower, the oxygen in the biogas is reacted with copper-zinc oxide and captured as copper oxide. The methane is concentrated by the pressure swing adsorption method to separate the carbon dioxide in the biogas. By operating the # towers and the device, the oxygen can be suppressed to a specific content or less, for example, 10 ppm or less, and recovered at a higher rate. Further, in the present invention, it is preferable to further include a hydrogen introduction device that introduces hydrogen into a deoxidation reaction column to reduce copper oxide formed by the reaction. Since the hydrogen introduction device introduces hydrogen into the deoxidation reaction column and reduces the copper oxide formed by the reaction, the copper oxide and the zinc oxide can be regenerated into copper-oxidation. Further, in the present invention, it is preferable that The biogas from which hydrogen sulfide has been removed in advance using the above-described hydrogen sulfide reaction column is introduced into the above-described deoxygenation reaction column. 160670.doc 201231639 According to the present invention, the biogas from which hydrogen sulfide has been removed in advance using the above hydrogen sulfide reaction column is introduced into the above deoxidation In the reaction tower, hydrogen sulfide does not react with the copper-oxidation reaction in the above deoxidation reaction column, so that the reaction between oxygen and copper-zinc oxide is not hindered. The objects, features, and advantages of the invention will be apparent from the description and drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The present invention is a method for recovering decane from a biogas. The biogas system is produced from a sludge such as a sewage treatment plant, and the main component thereof contains about 60 mol% of methane and about 40 mol% of carbon dioxide, and contains a trace amount of oxygen, nitrogen, hydrogen sulfide, and the like. Oxane and the like. When biogas is used as a gas for automobiles or urban gases, the decane concentration is preferably 95 mol% or more. When it is used as a gas for automobiles, it is used for compression. Therefore, it is necessary to prevent oxidizing carbon from being liquefied as one of the main impurities of the biogas. Therefore, it is necessary to have a smoldering concentration of 95 mol% or more. Further, when it is used as a gas for a city gas, if the concentration is low, the amount of heat is low. Therefore, like the automobile, the methane concentration is required to be 95 mol% or more. Therefore, although the raw gas system is used as a fuel gas for combustion, there is no case where oxygen is removed as a hetero atom f, but in the system for fuel cells, the oxygen contained in the biogas is The catalyst for reforming the water vapor is deteriorated, so oxygen must be removed. According to the present invention, oxygen can be inhibited from 160670.doc 201231639 to a specific content or less, for example, 10 ppm or less, and the combustibles can be recovered at a higher recovery rate, for example, a recovery rate of 80% or more. Fig. 1 is a view showing the steps of a method for recovering methane as one embodiment of the present invention. The decane recovery method of the present invention comprises: an adsorption removal step for removing impurities from the biogas and recovering the brothel at a higher recovery rate (step S1) removing the <5 oximeter; reaction removal step, Step $2) removes hydrogen sulfide; a capture step, which (step S3) captures oxygen; and a concentration step (step S4) concentrates the decane. (Step S1) Adsorption removal step In the adsorption removal step, the adsorbent is adsorbed to the adsorbent by filling the adsorbent into the adsorption tower and introducing the biogas into the adsorption tower to introduce the helium as an impurity contained in the biogas. Thereby removing the oxane from the biogas. As the adsorbent, those which are easy to adsorb oxime or those which do not easily adsorb decane, for example, activated carbon. Although activated carbon, such as natural activated carbon such as coconut shell and charcoal, mineral activated carbon such as pitch and petroleum coke, can be used, since the activated carbon cannot be regenerated and a new agent needs to be replaced, it is preferable to use cheap coconut shell activated carbon as much as possible. Preferably, the content of the oxoxane in the biogas is 2 mg/Nm3 or less, more preferably 丨mg/Nm3 or less, by the adsorption removal step. (Step S2) Reaction Removal Step In the reaction removal step, impurities such as hydrogen sulfide, mercaptan, etc. contained in the biogas are filled by filling the metal oxide into the reaction column and introducing the biogas into the adsorption tower. The sulfur-based compound is fixed in the reaction column as a metal sulfide. As the metal oxide, iron oxide, copper oxide, or oxidized 160670.doc 201231639 can be used. For example, if these metal oxides are chemically reacted with hydrogen sulfide, they become metal sulfides such as iron sulfide, copper sulfide, and zinc sulfide. The content of hydrogen sulfide in the biogas is preferably set to 3 mol ppm or less, more preferably 1 mol ppm or less by the reaction removal step. By carrying out the adsorption removal step and the reaction removal step as described above, the oxoxane and hydrogen sulfide in the biogas can be removed. Further, in the adsorption removal step and the reaction removal step, any step may be performed first, and the order of the steps is not particularly limited. Further, the compression step of compressing the biogas and the step of removing the moisture in the biogas may be performed before the adsorption removal step and the reaction removal step. In the dehumidification step, for example, the biogas is cooled and dehydrated by (TC), and dehydrated by adsorbing water such as alumina balls or zeolite (MS-3A), or adsorbing moisture such as alumina balls or zeolite. The agent is filled to the adsorption 4 and conducts the biogas. Further, a moisture adsorbent such as an oxidized spheroid or a zeolite may be filled in the adsorption tower for adsorbing and removing the decane, and the adsorption removal step may be performed while dehumidifying (step S3). The capturing step is carried out in the capturing step by filling a mixture of copper and zinc oxide as an oxygen scavenger into the reaction column, and introducing the biogas from which the Oxygen and the hydrogen sulfide are removed into the adsorption tower, and the biogas is introduced The oxygen contained in the impurities is trapped as copper oxide. After the copper-zinc oxide mixture is in contact with the biogas, the oxygen in the biogas reacts with copper to become oxidized steel, and is captured as a copper oxide zinc oxide mixture in the reaction tower. I60670.doc 201231639 In the capturing step, the treated gas from which 7 oxygen and hydrogen sulfide are removed is brought into contact with steel_zinc oxide at a temperature of 200 C to 300 C. In the case of the shape, even if the carbon dioxide is mixed at a ratio of 3 〇 to sail, there is a reaction of generating copper oxide in the treated gas, so that the oxygen content can be reduced compared with the case where the oxygen is reacted with the methane. To heat the energy of the gas to be treated, and directly fill the reaction tower. Although the copper-zinc oxide mixture can be particleized, in order to improve the contact efficiency with the biological gas introduced into the tower, it is preferable to make the particles in the form of copper. The oxidized mixture is supported on a support such as Oxal Oxide or Shishizao soil and filled into the reaction column. The copper oxidized hydrate prepared by the capture step of the present invention is hydrogen diluted by using an inert gas. An oxygen scavenger obtained by reduction of a methanol vapor recombination catalyst user. For example, since the methanol vapor recombination catalyst has a commercially available copper oxide zinc oxide supported on the oxidation, the methanol vapor recombination catalyst is Dilute to 5% of hydrogen with inert gas such as helium or nitrogen at 230~26 (contact at rc temperature, whereby copper oxide can be reduced to steel' and act as steel supported on oxidized steel. Preferably, the oxygen content in the biogas is set to 1 〇 ppm or less by the capture (4), more preferably 1 ppm or less. Here, the reaction removal step for removing hydrogen sulfide is carried out. The effect and the correlation with the capture step of capturing oxygen are explained. Since the sulfur-based compound such as hydrogen sulfide is adsorbed to the activated carbon, the adsorption step is removed to remove the ascorbic acid, and the activated carbon is used as the adsorbent. 160670.doc 201231639, although some hydrogen sulfide can be removed, but it is not sufficient. When the reaction removal step using the reaction of hydrogen sulfide with metal oxide is omitted, the gas to be treated in the capturing step will contain sulfur. Hydrogen. If copper-zinc oxide is contacted with hydrogen sulfide, hydrogen sulfide is reduced to produce sulfur, which in turn reacts with oxygen to produce sulfur dioxide. Further, zinc oxide reacts with hydrogen sulfide to form zinc sulfide. As described above, when hydrogen sulfide is contained in the gas to be treated in the capturing step, hydrogen sulfide reacts with copper-zinc oxide, so that the reaction between oxygen and copper-zinc oxide is inhibited, and oxygen cannot be sufficiently trapped. In order to sufficiently react the oxygen in the capture step t with the copper-zinc oxide to have an oxygen content of 10 ppm or less, it is not sufficient to adsorb and remove hydrogen sulfide by only the adsorption removal step, and the reaction by the reaction of hydrogen sulfide with the metal oxide is removed. Steps are necessary. (Step S4) The concentration step sufficiently removes impurities such as helium oxide, hydrogen sulfide, and oxygen in the biogas by the adsorption removal step, the reaction removal step, and the capture step, and the gas to be treated treated by the concentration step contains only rhodium. Alkanes and carbon dioxide. In the concentration step, carbon dioxide is adsorbed to the adsorbent by a pressure swing adsorption method to obtain concentrated high purity methane. In the pressure swing adsorption method, for example, one gas is obtained by concentration in a mixed gas of two substances, and an adsorbent having a higher adsorption capacity than the other substance and lower relative to the other substance is used under high pressure. Adsorption of a substance to the adsorbent "Then, the adsorbed substance is detached from the adsorbent at a low pressure, thereby regenerating the adsorbent. In the concentration step, the adsorption capacity of the adsorbed carbon dioxide is relatively relatively high, and the adsorbent having a relatively low adsorption capacity for adsorbing the A-burning is filled to a plurality of adsorption towers to change the pressure in the column and switch at a timely time. The adsorption column is used to separate carbon dioxide from methane and recover high purity decane. The concentration step is based on a pressure swing adsorption method, and the adsorption operation and the separation operation are repeated. The adsorption operation is such that the pressure in the adsorption tower filled with the adsorbent is relatively lower than the pressure at the time of the desorption operation, and the biogas from which helium, hydrogen sulfide and oxygen are removed under high pressure is introduced under high pressure conditions, although carbon dioxide adsorption In the adsorbent, but the decane is hardly adsorbed to the adsorbent, in the adsorption tower, carbon dioxide is separated from the decane to obtain a concentrated decane. When the biogas is continuously introduced into one adsorption tower, the carbon dioxide adsorbed in the adsorbent increases, and the adsorption capacity decreases, so that the adsorbent is regenerated by the detachment operation. The detachment operation stops the introduction of the biogas and causes the pressure in the adsorption tower to be relatively lower than the pressure at the adsorption operation, so that the adsorbed carbon dioxide in the adsorbent is detached from the adsorbent. The carbon dioxide after the detachment is discharged to the outside of the adsorption tower. When two adsorption towers are used, when one adsorption tower is used for the separation operation, the other adsorption tower performs the adsorption operation, and the adsorption operation and the separation operation are simultaneously performed by the respective columns. Moreover, after the specific amount is processed, the adsorption operation is switched. With the detachment operation. Thereby, since the adsorption operation is inevitably carried out in any of the columns, the separation and concentration of the decane can be continuously performed while regenerating the adsorbent. As the adsorbent having a high adsorption capacity of carbon dioxide and a low adsorption capacity of decane, a carbon-based adsorbent, preferably a carbon molecular sieve, can be used. Further, in the case of reducing the nitrogen content of the product gas according to the target product gas composition, for example, when the raw material gas is reported to be removed, it is necessary to remove it when it is reported. In addition to carbon molecular sieves, it is also possible to accumulate Buddha stones. As the technique in the adsorption operation, the MPU 4 "° I force P1 is, for example, atmospheric pressure (0.101 MPa) to 4.0 MPa. 柞 & 眙 切 丄 丄 丄 0 0 0 0 0 0 0 0 0 之 之 之The force P2 is, for example, 0.001 to 0.3] (wherein 1 > 1 > 1) 2). In the gas obtained by each step as described above, the oxygen content is H) ppm to obtain the purity of the methane. For example, the recovery device of the Biogas Recovery Institute of the present invention will be described. The recovery device of the present invention can be configured as long as it can perform the above-described recovery method. Fig. 2 is a schematic view showing a configuration of a recovery apparatus (10) which is one embodiment of the present invention. The apparatus 1 (10) includes a reduction machine 1, a dehumidification apparatus 2, an oxygen system (four) tower 3, a hydrogen sulfide reaction tower 4, and a deoxidation reaction. The tower 5 and the pressure swing type adsorption device 6 process the biogas supplied from the gas supply source 7. The gas supply source 7 is a source for generating biogas, for example, a sewage treatment plant. The impurity supplied from the gas supply source 7 contains impurities. The biogas system is compressed by the compressor 1 and sent to Dehumidification device for dehumidification As the dehumidification device, for example, a cooling dehydrator, a pressure adsorption dehydrator, a heating regenerative dehydrator, or the like can be used, but it is preferable to cool the biogas by 〇t: cooling and dehydration. Further, an adsorption tower filled with a moisture adsorbent such as oxidized glass or zeolite (MS-3A) may be used as the dehumidifying device 2 for adsorbing dehydration and not using a dehydrator. Further, depending on the amount of water, In each column after the helium-oxygen adsorption column 3 for adsorbing the decane, the layer is filled with a water sorbent such as 160670.doc 201231639 oxidized spheroidal ball, > vermiculite, etc. , for example, as described in the adsorption removal step, a hydrogen sulfide reaction column 4 for removing hydrogen sulfide by reacting, for example, activated carbon into an adsorption column as a adsorbent for adsorbing a helium oxide, as described in the reaction removal step a metal oxide which reacts with hydrogen sulfide to form a metal sulfide is filled into the reaction column. The biogas from which helium oxide and hydrogen sulfide are removed is introduced into the deoxygenation reaction column 5. As in the capture step In the same manner, the copper-zinc oxide mixture is charged to the deoxidation reaction column 5 in a form supported on a support such as alumina, and the oxygen contained in the introduced biogas reacts with the copper of the copper-oxidation mixture. In this case, the inside of the deoxidation reaction column 5 is heated to 2 〇〇 to 3 Torr by a heater (not shown). (1) It is preferable to further include the following hydrogen introduction device 5a: Hydrogen is introduced into the column of the deoxygenation reaction column 5 to reduce copper oxide-zinc oxide, thereby regenerating copper-zinc oxide. For example, a rotary blower for nitrogen gas which is returned to the circulation path of the inlet from the outlet of the deoxygenation reaction column 5 can be used. Hydrogen for regeneration is supplied to the deoxygenation reaction column 5 by a hydrogen introduction device "addition of hydrogen to nitrogen". The pressure swing type adsorption device 6 can use a well-known PSA (Pressure Swing Absorption) device, for example, a 2-tower pSA device. Fig. 3 is a schematic view showing an example of a pressure swing type adsorption device 6. The pressure swing type adsorption device 6 has a first adsorption column 12 and a second adsorption column 13, and a carbon molecular sieve as a carbon-based adsorbent is filled in each of the adsorption columns 12 and 13. The raw material piping 13f is connected to the inlets 12a and 13a of the adsorption towers 12 and 13 via the switching valves 12b and 13b. The inlets 12a, 13a of the adsorption towers 12, 13 are each connected to the 160670.doc 201231639 switching valves 12c, 13c and the muffler 13e so as to be openable to the atmosphere. Further, the adsorption tower lower pressure equalizing pipe 13g is connected to the inlets 12a and 13a of the adsorption tower 13 via the switching valve 13d. The outlets 12k and 13k of the adsorption towers 12 and 13 are connected to the outflow pipe 13A via the switching valves 121 and 131, and are connected to the cleaning pipe 13p via the switching valves 12m and 13m, and are pressurized by the upper portion of the adsorption tower via the switching valve 13n. The pipe 13q is connected. The outflow pipe 13 is connected to the pressure equalizing groove 14 via the check valve 13r and the manual valve 13s. The pressure equalization tank 14 is connected to the product tank 15 via a pressure regulating valve 14a. The product tank 15 is connected to the outlet pipe 15a of the pressure swing adsorption device 6. The adsorption pressure of the pressure swing adsorption device 6 is controlled by a pressure regulating valve 14a. The cleaning pipe 13t is connected to the cleaning pipe 13p via the flow rate control valve 13u and the flow rate indicating regulator 13v, and adjusts the gas flow rate of the cleaning pipe 13p to a fixed value, whereby the fillers of the adsorption columns 12 and 13 are washed. To a fixed degree. The adsorption operation, the pressure equalization operation, the detachment operation, the cleaning operation, and the pressure equalization operation are sequentially performed in the respective interiors of the first adsorption tower 12 and the second adsorption tower 13 of the pressure swing adsorption device 6. The switching valve 12b is opened, and the supplied biogas is introduced into the first adsorption tower 12'. Further, in the first adsorption tower 12, only the switching valve 121 is opened simultaneously with the switching valve 12b. Thereby, at least carbon monoxide in the biogas introduced in the second adsorption tower 12 is adsorbed to the adsorbent to perform adsorption operation, and methane not adsorbed to the adsorbent is separated from carbon dioxide and is adsorbed from the first adsorption via the outflow pipe 13 Tower 12 is exported. At this time, a part of 160670.doc 201231639 which is sent to the outflow pipe 13A is sent to the second adsorption tower 13 via the cleaning pipes 13p and 13t and the flow rate control valve i3u, and is carried out in the second adsorption tower 13 Wash operation. Then, the switching valves 12b and 121 are closed, the switching valves Un and nd are opened, and the pressure equalization operation in the column of the first adsorption tower 12 and the second adsorption tower 13 is performed. Then, by closing the switching valves (1), 13d, the switching 阙12c is turned on, and the detaching operation of removing the carbon dioxide-containing impurities from the adsorbent of the i-th adsorption tower 12 is performed. @The impurity containing carbon dioxide is discharged together with the gas via the muffler 13e. To the atmosphere. At this time, the manual valve (1) is opened while the switching valve 13b is opened, and the methane gas having the reduced carbon dioxide content is passed from the pressure equalizing tank 14 through the outflow pipe 13. The second adsorption tower 13' is introduced to perform a pressure increasing operation and an adsorption operation. Subsequent operations are performed in the same manner as the operation of the second adsorption column 12. The respective operations of the first adsorption tower 12 and the second adsorption tower 13 are sequentially reversed to obtain methane gas having a reduced content of impurities including carbon dioxide. Further, the pressure swing type adsorption device 6 is not limited to the configuration shown in Fig. 3. The number of columns may be, for example, two or four columns, and usually nine columns or less, in addition to two. According to such a recovery device, water can be removed from the supplied organism, and after the sulfuric acid is reduced, the oxygen disk copper-zinc oxide of the biogas towel is reacted and captured as an oxidized steel, and finally by the oxidation steel. The carbon dioxide is separated by a pressure swing adsorption method to obtain concentrated high purity methane. The present invention is not limited to the above configuration. In the example J, the argon sulfide reaction column 4' may be disposed after the compressor, and the configuration sequence of the reaction tower 4 may be adjusted by the reaction of the helium oxide adsorption tower hydrogen sulfide 160670.doc • 17- 201231639 The arrangement may also be set by adjusting the arrangement order of the deoxidation reaction tower 5 and the pressure swing adsorption device 6. [Example 1] It is assumed that the biogas produced from the sludge of the sewage treatment plant is 60.0 mol%, 38.7 mol% of carbon dioxide, 0.5 mol% of nitrogen, and 3 mol% of water. A mixed gas of oxonium.3 mol%, hydrogen sulfide hydrazine, 2 mol%, and oxoxane 50 mg/Nm3 was supplied as a gas to be treated, and was supplied at a flow rate of 450 NL/hr. The gas to be treated was introduced at 25 ° C to the following adsorption tower 3 : Inside a cylindrical adsorption tower with a diameter of 37 mm, an alumina sphere with 〇 2 kg as a dehydrating agent was accumulated (Sumitomo Chemical Co., Ltd.) The company manufactures, khd_ 24), and 〇·5 kg of coconut shell activated carbon (manufactured by Kuraray Chemical Co., Ltd., GG) as an adsorbent for decane. Then, the biogas derived from the Shixia oxygen adsorption tower 3 is introduced at 25 C to the following hydrogen sulfide reaction column 4: inside the reactor of the same size as the helium oxide adsorption column 3, filled with 2.0 kg of zinc oxide ( One JIS-size granulated product manufactured by Hakusui Tech Co., Ltd.) 0. Then, 1.2 kg of copper oxide-zinc oxide catalyst (manufactured by Siid_Chemie Catalyst Co., Ltd., MDC-3) was introduced into the same size as the siloxane adsorption column 3. The deoxidation reaction column 5 is introduced into the deoxygenation reaction column 5 by a hydrogen introduction device & to reduce the copper oxide-zinc oxide catalyst to form a copper-zinc oxide mixture. The temperature in the column of the deoxidation reaction column 5 is raised to 26 Torr and maintained, and the biogas derived from the hydrogen sulfide reaction column 4 is introduced. Then, the biogas derived from the deoxygenation reaction column 5 is introduced into the following change 160670.doc -18, 201231639 Pressure adsorption device 6: inside the adsorption column of the same size as the xanoxane adsorption column 3 'filled with 0_6 kg micropores A carbon molecular sieve having a pore diameter of 3 (manufactured by Kuraray Chemical, GN_UC_H). The operation of the pressure swing adsorption device 6 is the same as the above operation. The highest pressure in the adsorption operation is set to 〇 8 Mpa, and the lowest pressure in the detachment operation is set to atmospheric pressure, thereby separating and concentrating decane and carbon dioxide. The concentration of carbon dioxide and nitrogen in the biogas was measured using a GC-TCD (gas chromatograph with a thermal conductivity detector) manufactured by Shimadzu Corporation, and the moisture was measured by a dew point meter. The measurement was carried out by a trace oxygen concentration meter (model DF_15〇E) manufactured by DELTA F. The concentration of the oxirane was measured by GC/MS (Gas Chromatography Mass Spectrometer) manufactured by Shimadzu Corporation. The measurement was carried out using a GC-FPD (gas chromatograph equipped with a flame photometric detector) manufactured by Shimadzu Corporation. The composition of the gas derived from the deoxygenation reaction column 5 was measured, and as a result, decane 62·5 mol%, carbon dioxide 37 mol%, and nitrogen 0.5 mol/°. And water and oxygen with hydrogen sulfide and helium oxide are less than 1 mole ppm. Further, when the methane concentration of the product gas derived from the pressure swing adsorption device 6 was 98 mol%, the methane recovery rate was 851%, and the oxygen in the product gas was less than 1 mol ppm. [Example 2] The same procedure as in Example i was carried out except that the order of the parent-alterned oxygen-oxygen adsorption column 3 and the hydrogen sulfide reaction column 4, that is, the step of argon-oxidizing adsorption and the step of dehydrogenation. The treatment gas is concentrated in decane. 160670.doc -19- 201231639 Product gas derived from the pressure swing adsorption device 6 When the ear is at %' methane gas recovery rate is 84 9 The second degree is 98% The gas concentration is less than 1 mole PPm. Production. Oxygen in the mouth gas [Comparative Example 1] The same as in Example 1, except for the oxygen removal reaction column, that is, the step of capturing the oxygen, the same as in the case of Example 1, the A', the 匕Λ self-transformation type adsorption device 6 When the image is 2, ^, the gas recovery rate is 84·. : Body == wide' concentration is 90 moles ppm. Production. . Oxygen in the gas [Comparative Example 2] Does not pass through the deoxidation reaction column, that is, does not escape the rod... Does not enter the trapping step of oxygen, and reduces the oxygen flow in the product gas by reducing the flow rate of the raw material to 370 NL/hr. Mohr PPm' is in addition to this, with the embodiment! The same gas concentrates methane.曰~buried object When the oxygen concentration in the product gas derived from the pressure swing adsorption device 6 is PPm, the product gas has a methyl sulfide concentration of 99 mol% or more and the gas recovery rate is 72.4%. As in Comparative Example 1, if you want to get higher. The recovery rate of α is less than that of production. The oxygen concentration in the die-rolled body was as in Comparative Example 2, and the recovery rate of the methane gas was lowered by the reduction of the oxygen concentration in the product gas. On the other hand, in Examples 1 and 2, the oxygen concentration in the product gas was set to be unrecognized, and methane was recovered from the biogas at a high recovery rate. The present invention can be embodied in other various forms without departing from the spirit or essential characteristics thereof. Therefore, the above-described embodiments are merely illustrative in all respects. 160670.doc • 20· 201231639 The red envelope of the invention is shown in the scope of the patent application, and is not limited to the text of the specification. Further, all changes and modifications are intended to be within the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing a step of a method for recovering methane as one embodiment of the present invention. Fig. 2 is a schematic view showing the configuration of a recovery apparatus which is one embodiment of the present invention. Fig. 3 is a schematic view showing an example of a pressure swing type adsorption device. [Description of main components] 1 Compressor 2 Dehumidifier 3 Hydroxane adsorption tower 4 Hydrogen sulfide reaction tower 5 Deoxidation reaction tower 5a Hydrogen introduction device 6 Pressure swing adsorption device 7 Gas supply source 12 First adsorption tower 12a > 13a Adsorption column inlets 12b, 12c, 12m, 13b, 13c, 13d, 13m, 13n, 121, 131 switching valves 12k, 13k adsorption tower outlet 13 second adsorption tower 160670.doc -21 · 201231639 13e muffler 13f raw material piping 13g adsorption Tower lower pressure equalizing pipe 13o Outflow pipe 13p ' 13t Washing pipe 13q Adsorption tower upper equalizing pipe 13r Check valve 13s Manual valve 13t Washing pipe 13u Flow control valve 13v Flow indicating regulator 14 Pressure equalizing tank 14a Pressure regulating valve 15 Product tank 15a outlet piping 100 recovery unit SI removal of helium oxide removal step S2 removal of hydrogen sulfide reaction removal step S3 capture of oxygen capture step S4 concentration of decane concentration step 160670.doc · 22·