1. 聚丙烯(xi)工藝(yi)的技(ji)術發展
聚(ju)丙烯(Polypropylene,PP)是以丙烯為(wei)單體(ti)經(jing)(jing)聚(ju)合反應(ying)而生(sheng)成(cheng)的聚(ju)合樹脂(zhi)。已經(jing)(jing)成(cheng)為(wei)我國經(jing)(jing)濟建設(she)中不(bu)可缺少的材料(liao)。具(ju)體(ti)應(ying)用(yong)在包裝材料(liao)、服裝用(yong)料(liao)、產業(ye)用(yong)料(liao)、過濾(lv)用(yong)料(liao)、衛生(sheng)用(yong)料(liao)和煙(yan)用(yong)絲束等。
四(si)十(shi)多年來,聚丙(bing)烯的催化劑(ji)不(bu)斷開發,不(bu)斷改性(xing),尤其(qi)是近(jin)二十(shi)年來,其(qi)技術一次又一次飛躍式的進(jin)步,極大地簡化了(le)聚丙(bing)烯的工藝流程,使裝置的投資和(he)生產成(cheng)本(ben)降到很低(di)的水(shui)平(ping)。
聚(ju)丙烯常用工藝方法包括(kuo)淤漿法工藝和本體法工藝。
①. 淤(yu)漿(jiang)(jiang)(jiang)法(fa)(fa)工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)(Slurry Process)又稱(cheng)漿(jiang)(jiang)(jiang)液法(fa)(fa)或溶劑(ji)(ji)法(fa)(fa)工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi),是(shi)世界(jie)上最(zui)早用(yong)于生(sheng)(sheng)(sheng)產(chan)(chan)(chan)(chan)聚丙(bing)烯的(de)工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)技術。從1957年第(di)(di)一套工(gong)(gong)(gong)(gong)業化(hua)裝置到現在一直(zhi)是(shi)最(zui)主要(yao)的(de)聚丙(bing)烯生(sheng)(sheng)(sheng)產(chan)(chan)(chan)(chan)工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)。典型工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)主要(yao)包(bao)括意大利 Montedison 工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)、美國Hercules 工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)、日(ri)本三(san)井(jing)東(dong)壓(ya)化(hua)學工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)、美國Amoco 工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)、日(ri)本三(san)井(jing)油化(hua)工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)以(yi)及索維爾工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)等。這些工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)的(de)開(kai)發都基于當時的(de)第(di)(di)一代催化(hua)劑(ji)(ji),采(cai)用(yong)立(li)式(shi)攪拌釜反應(ying)器(qi),需要(yao)脫(tuo)灰(hui)和脫(tuo)無(wu)規物(wu)(wu),因采(cai)用(yong)的(de)溶劑(ji)(ji)不同(tong),工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)流程和操作條件有所不同(tong)。近(jin)年來,傳統的(de)淤(yu)漿(jiang)(jiang)(jiang)法(fa)(fa)工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)在生(sheng)(sheng)(sheng)產(chan)(chan)(chan)(chan)中的(de)比例明顯(xian)減少,保留的(de)淤(yu)漿(jiang)(jiang)(jiang)產(chan)(chan)(chan)(chan)品主要(yao)用(yong)于一些高價值領(ling)域(yu),如(ru)特種BOPP薄膜、高相對分子質量吹(chui)塑膜以(yi)及高強度管(guan)材(cai)等。近(jin)年來,人們對該(gai)方法(fa)(fa)進行了(le)改(gai)進,改(gai)進后的(de)淤(yu)漿(jiang)(jiang)(jiang)法(fa)(fa)生(sheng)(sheng)(sheng)產(chan)(chan)(chan)(chan)工(gong)(gong)(gong)(gong)藝(yi)(yi)(yi)使用(yong)高活性的(de)第(di)(di)二代催化(hua)劑(ji)(ji),可刪除催化(hua)劑(ji)(ji)脫(tuo)灰(hui)步驟,能(neng)(neng)減少無(wu)規聚合物(wu)(wu)的(de)產(chan)(chan)(chan)(chan)生(sheng)(sheng)(sheng),可用(yong)于生(sheng)(sheng)(sheng)產(chan)(chan)(chan)(chan)均聚物(wu)(wu)、無(wu)規共聚物(wu)(wu)和抗沖共聚物(wu)(wu)產(chan)(chan)(chan)(chan)品等。目前世界(jie)淤(yu)漿(jiang)(jiang)(jiang)法(fa)(fa)PP的(de)生(sheng)(sheng)(sheng)產(chan)(chan)(chan)(chan)能(neng)(neng)力(li)約占(zhan)全(quan)球PP總生(sheng)(sheng)(sheng)產(chan)(chan)(chan)(chan)能(neng)(neng)力(li)的(de)13%。
②. 本體(ti)法工(gong)(gong)(gong)藝(yi)的(de)(de)研究開發始于(yu)20世紀60年代,1964年美(mei)國(guo)Dart公司采用(yong)釜式反(fan)應(ying)(ying)(ying)器建成(cheng)了(le)世界(jie)上第一套工(gong)(gong)(gong)業化本體(ti)法聚(ju)(ju)(ju)(ju)丙(bing)烯(xi)(xi)生產(chan)(chan)裝置。1970年以后(hou),日本住友(you)、Phillips、美(mei)國(guo)EI Psao等(deng)公司都(dou)實現了(le)液(ye)(ye)(ye)(ye)相本體(ti)聚(ju)(ju)(ju)(ju)丙(bing)烯(xi)(xi)工(gong)(gong)(gong)藝(yi)的(de)(de)工(gong)(gong)(gong)業化生產(chan)(chan)。與采用(yong)溶(rong)劑的(de)(de)漿液(ye)(ye)(ye)(ye)法相比(bi),采用(yong)液(ye)(ye)(ye)(ye)相丙(bing)烯(xi)(xi)本體(ti)法進(jin)行(xing)聚(ju)(ju)(ju)(ju)合(he)(he)具有(you)(you)不(bu)使用(yong)惰性溶(rong)劑,反(fan)應(ying)(ying)(ying)系統內單(dan)(dan)體(ti)濃度高(gao)(gao),聚(ju)(ju)(ju)(ju)合(he)(he)速率(lv)快,催化劑活性高(gao)(gao),聚(ju)(ju)(ju)(ju)合(he)(he)反(fan)應(ying)(ying)(ying)轉化率(lv)高(gao)(gao),反(fan)應(ying)(ying)(ying)器的(de)(de)時空生產(chan)(chan)能力更大(da),能耗低,工(gong)(gong)(gong)藝(yi)流程簡(jian)單(dan)(dan),設備少(shao),生產(chan)(chan)成(cheng)本低,“三廢”量(liang)(liang)少(shao);容易除去(qu)聚(ju)(ju)(ju)(ju)合(he)(he)熱(re),并使撤熱(re)控制簡(jian)單(dan)(dan)化,可以提高(gao)(gao)單(dan)(dan)位反(fan)應(ying)(ying)(ying)器的(de)(de)聚(ju)(ju)(ju)(ju)合(he)(he)量(liang)(liang);能除去(qu)對(dui)產(chan)(chan)品性質(zhi)有(you)(you)不(bu)良影響(xiang)的(de)(de)低分子量(liang)(liang)無(wu)規聚(ju)(ju)(ju)(ju)合(he)(he)物和催化劑殘(can)渣,可以得到高(gao)(gao)質(zhi)量(liang)(liang)的(de)(de)產(chan)(chan)品等(deng)優點。不(bu)足之(zhi)處是反(fan)應(ying)(ying)(ying)氣體(ti)需要氣化,冷凝后(hou)才(cai)能循環回反(fan)應(ying)(ying)(ying)器。反(fan)應(ying)(ying)(ying)器內的(de)(de)高(gao)(gao)壓液(ye)(ye)(ye)(ye)態烴類物料容量(liang)(liang)大(da),有(you)(you)潛在的(de)(de)危險性。此外,反(fan)應(ying)(ying)(ying)器中乙烯(xi)(xi)的(de)(de)濃度不(bu)能太(tai)高(gao)(gao),否(fou)則(ze)在反(fan)應(ying)(ying)(ying)器中形成(cheng)一個單(dan)(dan)獨的(de)(de)氣相,使得反(fan)應(ying)(ying)(ying)器難以操作,因而所得共聚(ju)(ju)(ju)(ju)產(chan)(chan)品中的(de)(de)乙烯(xi)(xi)含量(liang)(liang)不(bu)會太(tai)高(gao)(gao)。
本體法(fa)不(bu)同(tong)(tong)工藝路線的(de)區(qu)別主要是(shi)反(fan)應(ying)(ying)器(qi)的(de)不(bu)同(tong)(tong)。反(fan)應(ying)(ying)器(qi)可分(fen)為釜式反(fan)應(ying)(ying)器(qi)和環(huan)管(guan)反(fan)應(ying)(ying)器(qi)兩大(da)類。釜式反(fan)應(ying)(ying)器(qi)是(shi)利用(yong)液體蒸發的(de)潛(qian)熱來除去反(fan)應(ying)(ying)熱,蒸發的(de)大(da)部分(fen)氣(qi)體經循(xun)環(huan)冷凝(ning)(ning)后(hou)返回(hui)到反(fan)應(ying)(ying)器(qi),未冷凝(ning)(ning)的(de)氣(qi)體經壓(ya)縮機(ji)升壓(ya)后(hou)循(xun)環(huan)回(hui)反(fan)應(ying)(ying)器(qi)。而(er)環(huan)管(guan)反(fan)應(ying)(ying)器(qi)則是(shi)利用(yong)軸流(liu)泵使漿液高速(su)循(xun)環(huan),通過夾(jia)套冷卻撤熱,由于傳熱面(mian)積大(da),撤熱效果好,因(yin)此其單位反(fan)應(ying)(ying)器(qi)體積產率高,能耗低。
本體法生產工(gong)(gong)藝(yi)按聚合(he)(he)工(gong)(gong)藝(yi)流程,可以(yi)分為間歇式聚合(he)(he)工(gong)(gong)藝(yi)和連(lian)續式聚合(he)(he)工(gong)(gong)藝(yi)兩種。
a. 間歇式本體法工藝
間歇本體法聚(ju)(ju)丙烯聚(ju)(ju)合(he)技(ji)術(shu)是我國(guo)(guo)(guo)自行研制(zhi)開發成(cheng)功的(de)(de)生(sheng)產(chan)技(ji)術(shu)。它具有(you)生(sheng)產(chan)工藝(yi)技(ji)術(shu)可(ke)靠(kao),對(dui)原(yuan)料丙烯質(zhi)量(liang)(liang)要求不(bu)(bu)(bu)是很高,所需催化劑國(guo)(guo)(guo)內有(you)保(bao)證,流程簡(jian)單,投資省、收效(xiao)快,操(cao)作簡(jian)單,產(chan)品牌號轉換靈活、“三廢(fei)少”,適合(he)中國(guo)(guo)(guo)國(guo)(guo)(guo)情等(deng)優(you)點,不(bu)(bu)(bu)足(zu)之處是生(sheng)產(chan)規模小(xiao),難以產(chan)生(sheng)規模效(xiao)益;裝(zhuang)置手工操(cao)作較多,間歇生(sheng)產(chan),自動化控(kong)制(zhi)水(shui)平低,產(chan)品質(zhi)量(liang)(liang)不(bu)(bu)(bu)穩定;原(yuan)料的(de)(de)消耗定額較高;產(chan)品的(de)(de)品種牌號少,檔次不(bu)(bu)(bu)高,用途較窄。目前(qian),我國(guo)(guo)(guo)采(cai)用該法生(sheng)產(chan)的(de)(de)聚(ju)(ju)丙烯生(sheng)產(chan)能力約占全國(guo)(guo)(guo)總生(sheng)產(chan)能力的(de)(de)24%。
b. 連續式本(ben)體法(fa)工藝
該工(gong)藝(yi)主要包括美國(guo)Rexall工(gong)藝(yi)、美國(guo)Phillips工(gong)藝(yi)以及日本Sumitimo 工(gong)藝(yi)。
2. Dow化學公司Unipol 工藝
該工(gong)藝(yi)屬于Dow化(hua)學公司(si)所有,Unipol聚丙烯工(gong)藝(yi)和其聚乙(yi)烯工(gong)藝(yi)類似(si)。工(gong)藝(yi)過程(cheng)主要包(bao)括原(yuan)料精(jing)制、催(cui)化(hua)劑進料、聚合反應、聚合物脫氣(qi)和尾氣(qi)回收、造粒、摻混和包(bao)裝碼(ma)垛等工(gong)段(duan)。
Unipol聚丙烯(xi)工藝流程,如圖5-107所(suo)示。
3. BASF公司(si)的Novolen 工藝
該工藝(yi)是由(you)(you) BASF公(gong)(gong)(gong)司(si)開(kai)發成(cheng)(cheng)功的。1999年,該工藝(yi)擁有(you)者(zhe) Targor 公(gong)(gong)(gong)司(si)和ABB Lum-mus公(gong)(gong)(gong)司(si)達(da)成(cheng)(cheng)協議。由(you)(you)ABB Lummus 公(gong)(gong)(gong)司(si)負責在(zai)全(quan)球范圍內(nei)推廣Novolen工藝(yi)。2000年9月,被(bei)ABB公(gong)(gong)(gong)司(si)和Equistar公(gong)(gong)(gong)司(si)所組成(cheng)(cheng)的合資公(gong)(gong)(gong)司(si) Novolen Technology Holding(簡(jian)稱NTH)收購。2008年,由(you)(you)CB&-I整體(ti)收購了 Lummus,Novolen 工藝(yi)由(you)(you)新成(cheng)(cheng)立的CB&-ILummus負責全(quan)球轉讓。
Novolen 包(bao)括原料(liao)精制、催(cui)化劑配制、聚(ju)(ju)合(he)反應、聚(ju)(ju)合(he)物(wu)粉料(liao)的凈化、擠壓造(zao)粒等工序,如圖5-108和圖5-109所(suo)示。
4. 某國外工程聚(ju)丙烯裝置布置實例(圖(tu)5-110)