龍文宇, 李東勝, 李曉鷗, 秦永航, 杜振佰
(1.遼寧石油化工大學(xué),遼寧撫順113001;2.中國石油撫順石化公司洗滌劑化工廠,遼寧撫順113001)
糠醛精制在潤滑油基礎(chǔ)油生產(chǎn)中具有舉足輕重的作用[1-10]。在“老三套”工藝中可以提高基礎(chǔ)油的產(chǎn)品質(zhì)量[11],在加氫處理工藝中可以優(yōu)化原料,提高產(chǎn)品收率[12-13]。大連石化公司生產(chǎn)基礎(chǔ)油的“老三套”裝置是以大慶原油為基礎(chǔ)設(shè)計(jì)的,隨著大慶原油資源日益減少,加工大慶潿洲混合油(體積比1∶1)時(shí),減二線脫蠟油生產(chǎn)HVI150SN基礎(chǔ)油的黏度指數(shù)不能滿足中國石油天然氣股份有限集團(tuán)公司Q/SY44—2009通用潤滑油基礎(chǔ)油黏度指數(shù)為100的質(zhì)量標(biāo)準(zhǔn)的要求。因此,本文對大慶潿洲混合減二線脫蠟油進(jìn)行糠醛精制研究,分析基礎(chǔ)油產(chǎn)品質(zhì)量不合格的具體原因,確定合理的解決方案。
減二線脫蠟油(V(大慶)/V(潿洲)=1∶1),性質(zhì)如表1所示。
表1 原料性質(zhì)Table1 Properties of experimental material
糠醛由大連石化糠醛溶劑罐區(qū)采得,使用時(shí)蒸?。?60±1)℃餾分。
采用劉潔等[14]提出的方法對工業(yè)裝置理論塔板數(shù)進(jìn)行標(biāo)定,采用李曉鷗等[15-19]與李東勝等[20-21]提出的方法進(jìn)行多級靜態(tài)萃取實(shí)驗(yàn)。
中試裝置主要是由抽提塔、抽出液溶劑回收塔、抽余液溶劑回收塔構(gòu)成,由計(jì)算機(jī)控制,處理量為2~12L/h,設(shè)計(jì)理論板數(shù)為3-4塊,實(shí)際理論板數(shù)為4塊。
運(yùn)動(dòng)黏度:GB/T 265—1988石油產(chǎn)品運(yùn)動(dòng)黏度測定法和動(dòng)力黏度計(jì)算法;黏度指數(shù):GB/T 1995—1998石油產(chǎn)品黏度指數(shù)計(jì)算法;酸值:GB/T 4945—2002石油產(chǎn)品和潤滑劑酸值和堿值測定法。
采用色質(zhì)譜法對原料進(jìn)行了族組成分析,結(jié)果如表2所示。
表2 原料族組成Table2 Group composition of experimental material%
續(xù)表2
由表2可以看出,減二線脫蠟油原料的總鏈烷烴質(zhì)量分?jǐn)?shù)為19.1%、總芳香烴質(zhì)量分?jǐn)?shù)為28.5%、總環(huán)狀烴質(zhì)量分?jǐn)?shù)為52.4%,而三環(huán)以上的環(huán)狀烴(環(huán)烷烴及芳烴)質(zhì)量分?jǐn)?shù)高達(dá)36.2%??啡┚蒲b置加工該原料生產(chǎn)合格質(zhì)量的HVI150SN潤滑油基礎(chǔ)油壓力較大。
采用單級萃取模擬抽提塔的逆流萃取進(jìn)行塔的理論塔板數(shù)標(biāo)定。假二段萃取實(shí)驗(yàn)與工業(yè)裝置的操作條件與實(shí)驗(yàn)結(jié)果如表3所示。
表3 假二段與工業(yè)裝置的操作條件與實(shí)驗(yàn)結(jié)果Table3 The operating conditions and experimental results in both simulate-two-stage extractions and industrial unit
由表3可以看出,裝置的理論板數(shù)接近2塊。工業(yè)裝置的抽提塔為轉(zhuǎn)盤塔,其理論板數(shù)要低于填料塔。生產(chǎn)過程中經(jīng)常出現(xiàn)轉(zhuǎn)盤不轉(zhuǎn)的情況,降低了傳質(zhì)效果。標(biāo)定的結(jié)果是符合裝置實(shí)際情況的。
優(yōu)化裝置的操作條件及增加裝置的理論板數(shù)均可提高產(chǎn)品質(zhì)量。在現(xiàn)有工業(yè)裝置的理論板數(shù)及操作條件的基礎(chǔ)上,按照下面兩種方法進(jìn)行多級靜態(tài)萃取實(shí)驗(yàn):(1)固定理論板數(shù)為2塊,根據(jù)文獻(xiàn)[22]單因素實(shí)驗(yàn)結(jié)果,增加劑油體積比至5.47∶1進(jìn)行假二段實(shí)驗(yàn);(2)固定劑油體積比為3.2∶1,增加理論板數(shù),即進(jìn)行假三段及假四段實(shí)驗(yàn)。實(shí)驗(yàn)的操作條件、產(chǎn)品質(zhì)量及收率的數(shù)據(jù)如表4所示。
表4 多級靜態(tài)萃取實(shí)驗(yàn)的操作條件與實(shí)驗(yàn)結(jié)果Table4 The operating conditions and experimental results in multi-stage static extraction
由表4可以看出,假二段實(shí)驗(yàn)表明,現(xiàn)有的糠醛精制裝置加工大慶潿洲1∶1減二線脫蠟油,劑油體積比提高到5.47∶1,可以生產(chǎn)出合格的HVI150SN潤滑油基礎(chǔ)油;假三段實(shí)驗(yàn)表明,精制油的質(zhì)量隨萃取溫度的增加而提高,但當(dāng)溫度超過90℃時(shí),增加的趨勢趨于平緩,精制油的收率隨萃取溫度的增加而下降,但收率主要受沉降溫度的影響,當(dāng)沉降溫度一定時(shí),萃取溫度對精制油的收率的影響較小,當(dāng)劑油體積比為3.2∶1時(shí),通過優(yōu)化操作溫度的方法不能使黏度指數(shù)達(dá)到100;假四段實(shí)驗(yàn)表明,精制油的質(zhì)量隨萃取溫度的增加而提高,假四段實(shí)驗(yàn)1精制油黏度指數(shù)達(dá)到99,假四段實(shí)驗(yàn)2精制油黏度指數(shù)滿足要求。由此可見,在現(xiàn)有的操作條件下,至少需要4塊理論板的抽提塔才能生產(chǎn)合格的潤滑油基礎(chǔ)油。
通過計(jì)量泵調(diào)控中試裝置劑油體積比為3.2∶1,待裝置運(yùn)行平穩(wěn)后每4h取樣一次進(jìn)行黏度及溶劑含量測定,產(chǎn)品質(zhì)量穩(wěn)定后,進(jìn)行物料衡算計(jì)算精制油收率。中試實(shí)驗(yàn)的操作條件、精制油質(zhì)量與收率如表5所示。
由表5可以看出,與多級靜態(tài)實(shí)驗(yàn)的結(jié)果相比,中試實(shí)驗(yàn)結(jié)果略好。若裝置的抽提塔理論板數(shù)不低于4塊,在現(xiàn)有的操作條件下,大慶與潿洲體積比1∶1的減二線脫蠟原料油可以生產(chǎn)黏度指數(shù)合格的HVI150SN潤滑油基礎(chǔ)油。
表5 中試實(shí)驗(yàn)操作條件與結(jié)果Table5 The operating conditions and experimental results in the pilot plant
(1)HVI150潤滑油基礎(chǔ)油的黏度指數(shù)不合格的主要原因是抽提塔的理論板數(shù)偏低。
(2)在現(xiàn)有裝置的基礎(chǔ)上,提高劑油體積比達(dá)到5.47∶1,可生產(chǎn)合格的HVI150潤滑油基礎(chǔ)油。
(3)在現(xiàn)有劑油體積比的基礎(chǔ)上,增加理論板數(shù)達(dá)到4塊,可生產(chǎn)合格的HVI150潤滑油基礎(chǔ)油。
(4)由于裝置的加熱爐熱負(fù)荷及溶劑回收系統(tǒng)的限制,通過提高劑油體積比改善精制油質(zhì)量的方法難度較大。此外,該方法帶來處理量及精制油收率降低,生產(chǎn)成本增加等不利影響。因此最適合的解決方案是對糠醛精制裝置的抽提塔進(jìn)行改造,改造后的抽提塔理論板數(shù)不少于4塊。
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