年產(chǎn)10萬噸纖維質(zhì)原料酒精發(fā)酵工藝設(shè)計(jì)畢業(yè)設(shè)計(jì)

1、唐 山 學(xué) 院畢 業(yè) 設(shè) 計(jì)設(shè)計(jì)題目： 年產(chǎn)10萬噸纖維質(zhì)原料酒精發(fā)酵工藝設(shè)計(jì) 系 別： 環(huán)境與化學(xué)工程系 班 級： 08化學(xué)工程與工藝（2）班 姓 名： 路 冉 冉 指 導(dǎo) 教 師： 李 云 凱 2012年6月11 日唐山學(xué)院畢業(yè)設(shè)計(jì)（論文）任務(wù)書 環(huán)境與化學(xué)工程 系 08化工本 專業(yè) 2 班 姓名：路冉冉 畢業(yè)設(shè)計(jì)（論文）時(shí)間： 2012 年 3 月 21 日 至 2012 年 6 月 24 日畢業(yè)設(shè)計(jì)（論文）題目： 年產(chǎn)10萬噸纖維質(zhì)原料酒精發(fā)酵工藝設(shè)計(jì) 1.畢業(yè)設(shè)計(jì)（論文）的目的和意義本設(shè)計(jì)主要設(shè)計(jì)工藝流程、物料衡算、熱量衡算和主要設(shè)備工藝計(jì)算，參考淀粉質(zhì)原料較成熟的工藝，同時(shí)考慮國內(nèi)

2、外的一些先進(jìn)設(shè)備，以盡量減少損失，達(dá)到最佳的操作，并獲得較大的酒精收率，為后續(xù)工藝設(shè)計(jì)合理的技術(shù)路線。整個(gè)設(shè)計(jì)應(yīng)安全適用并符合國家要求，添加合適的安全系數(shù)后本設(shè)計(jì)可以應(yīng)用到實(shí)際的生產(chǎn)當(dāng)中去。2.畢業(yè)設(shè)計(jì)（論文）課題任務(wù)的內(nèi)容和要求通過論證分析和技術(shù)經(jīng)濟(jì)比較，確定較為合理工藝流程。通過對工藝流程和工藝參數(shù)的確定，進(jìn)行物料衡算、熱量衡算、水平衡計(jì)算、耗電量計(jì)算、設(shè)備的計(jì)算與選型以及經(jīng)濟(jì)概算等。并在設(shè)備的計(jì)算與選型基礎(chǔ)上，繪制圖紙。3.畢業(yè)設(shè)計(jì)（論文）成果的要求根據(jù)設(shè)計(jì)結(jié)論對所需設(shè)備進(jìn)行選型。通過對物料進(jìn)行工藝計(jì)算，確定每個(gè)設(shè)備的的工藝尺寸。進(jìn)行各種衡算。完成圖紙四張(2號圖紙)：重點(diǎn)設(shè)備圖、全廠工

3、藝流程圖、車間平面布置和全廠平面布置圖。畢業(yè)設(shè)計(jì)（論文）進(jìn)度計(jì)劃安排階段應(yīng)完成的主要工作起止教學(xué)周1查閱相關(guān)文獻(xiàn),論文總體設(shè)計(jì),填寫工作進(jìn)度計(jì)劃表，撰寫開題報(bào)告4-52確定設(shè)計(jì)大致思路63進(jìn)行工藝比較，方法的論證，物料衡算7-84熱量衡算的計(jì)算，空氣、水量的計(jì)算，設(shè)備的選型9-105工藝圖和設(shè)備圖的作圖11-146整理試驗(yàn)數(shù)據(jù)，撰寫論文，上交指導(dǎo)老師157論文答辯168主要參考文獻(xiàn)1 吳思方. 發(fā)酵工廠工藝設(shè)計(jì)概況M. 北京：中國輕工業(yè)出版社,1998.102 陳寧. 氨基酸工藝學(xué)M. 北京：中國輕工業(yè)出版社,2007，1 3陳洪章. 纖維素生物技術(shù)M. 北京,化學(xué)工業(yè)出版社, 20054吳德

4、榮. 化工工藝設(shè)計(jì)手冊 第四版(上下冊) M. 化學(xué)工業(yè)出版社, 20095謝林, 呂西軍. 玉米酒精生產(chǎn)新技術(shù)M. 北京, 中國輕工業(yè)出版社, 20006賈樹彪等. 新編酒精工藝學(xué)M. 北京,化學(xué)工業(yè)出版社, 2004指導(dǎo)教師（簽名）： 審批人（簽名）：畢業(yè)設(shè)計(jì)(論文)指導(dǎo)教師評議書(1)序號評分指標(biāo)具 體 要 求分?jǐn)?shù)范圍得 分1學(xué)習(xí)態(tài)度努力學(xué)習(xí)，勤于思考，遵守紀(jì)律，作風(fēng)嚴(yán)謹(jǐn)務(wù)實(shí)。04分2調(diào)研論證能獨(dú)立查閱文獻(xiàn)資料及從事其它形式的調(diào)研，能較好地理解課題任務(wù)并提出實(shí)施方案，有分析整理各類信息并從中獲取新知識的能力。08分3綜合能力能綜合運(yùn)用所學(xué)知識和技能發(fā)現(xiàn)與解決實(shí)際問題，工作中有創(chuàng)新精神，成

5、果有新意或有實(shí)用價(jià)值。010分4設(shè)計(jì)（論文）質(zhì)量論證、分析、設(shè)計(jì)、計(jì)算、建模、實(shí)驗(yàn)正確合理，工作量飽滿。010分5外文翻譯摘要及外文資料翻譯準(zhǔn)確，文字流暢，符合規(guī)定內(nèi)容及字?jǐn)?shù)要求。04分6說明書(論文)撰寫質(zhì)量說明書文字通順、結(jié)構(gòu)嚴(yán)謹(jǐn)、邏輯性強(qiáng)、格式規(guī)范、符合規(guī)定字?jǐn)?shù)要求，繪圖清楚、工整、規(guī)范。 04分合計(jì)040分評語：指導(dǎo)教師： 年 月 日本畢業(yè)設(shè)計(jì)（論文）需要特殊說明的有關(guān)問題指導(dǎo)教師： 年 月 日畢業(yè)設(shè)計(jì)(論文)評閱教師評議書(2)序號評分指標(biāo)具 體 要 求分?jǐn)?shù)范圍得 分1調(diào)研論證能獨(dú)立查閱文獻(xiàn)資料及從事其它形式的調(diào)研，能較好地理解課題任務(wù)并提出實(shí)施方案，有分析整理各類信息并從中獲取新知

6、識的能力。04分2綜合能力能綜合運(yùn)用所學(xué)知識和技能發(fā)現(xiàn)與解決實(shí)際問題，工作中有創(chuàng)新精神，成果有新意或有實(shí)用價(jià)值。05分3設(shè)計(jì)（論文）質(zhì)量論證、分析、設(shè)計(jì)、計(jì)算、建模、實(shí)驗(yàn)正確合理，工作量飽滿。06分4外文翻譯摘要及外文資料翻譯準(zhǔn)確，文字流暢，符合規(guī)定內(nèi)容及字?jǐn)?shù)要求。02分5說明書（論文）撰寫質(zhì)量說明書文字通順、結(jié)構(gòu)嚴(yán)謹(jǐn)、邏輯性強(qiáng)、格式規(guī)范、符合規(guī)定字?jǐn)?shù)要求，繪圖清楚、工整、規(guī)范。 03分合計(jì)020分評語：評 閱 人： 年 月 日畢業(yè)設(shè)計(jì)(論文)答辯小組評議書(3)評分指標(biāo)具 體 要 求分?jǐn)?shù)范圍自 述思路清晰，語言表達(dá)準(zhǔn)確，概念清楚，論點(diǎn)正確，分析歸納合理。0 7分水 平工作中有創(chuàng)新精神，成果有

7、新意或有實(shí)用價(jià)值。0 8分答 辯能夠正確回答所提出的問題，基本概念清楚，有理論根據(jù)。020分資 料資料齊全，符合學(xué)院畢業(yè)設(shè)計(jì)（論文）規(guī)范化要求。0 5分合計(jì)040分評委1評委2評委3評委4評委5評委6評委7總 分平均成績答辯紀(jì)要：答辯小組秘書（簽字）：年 月 日答辯小組組長（簽字）：年 月 日答 辯 委 員 會 意 見指導(dǎo)教師評議評閱人評議答辯小組評議匯總成績秘書（簽字）唐山學(xué)院 系畢業(yè)設(shè)計(jì)（論文）答辯委員會于 年 月 日審查了 專業(yè)學(xué)生 的畢業(yè)設(shè)計(jì) （論文） （其中設(shè)計(jì)說明書（論文）共 頁，設(shè)計(jì)圖紙 張）。根據(jù)其設(shè)計(jì)（論文）的完成情況以及指導(dǎo)教師、評閱教師、答辯小組的意見，系畢業(yè)設(shè)計(jì)（論文）

8、答辯委員會認(rèn)真審議，決議如下：成績評定為： 主任（簽字）： 年 月 日 1 引 言11.1 酒精發(fā)展現(xiàn)狀11.1.1 酒精的概述11.1.2 酒精發(fā)酵工藝11.2 纖維質(zhì)概述11.2.1 纖維素的結(jié)構(gòu)與性質(zhì)21.2.2 半纖維素的結(jié)構(gòu)與性質(zhì)21.2.3 木質(zhì)素的結(jié)構(gòu)與性質(zhì)21.3 纖維質(zhì)酒精發(fā)酵現(xiàn)狀21.4 本課題的目的和意義32 設(shè)計(jì)概論52.1畢業(yè)設(shè)計(jì)的題目52.2畢業(yè)設(shè)計(jì)的目的52.3 畢業(yè)設(shè)計(jì)的任務(wù)52.4 設(shè)計(jì)的指導(dǎo)思想52.5 設(shè)計(jì)的依據(jù)62.6 生產(chǎn)方案的確定和產(chǎn)品方案62.7 廠址選擇的總原則6廠址選擇的重要性6廠址選擇的基本任務(wù)7廠址選擇的一般原則72.8工廠總平面布置7工廠

9、總平面布置的一般原則72.9車間布置82.9.1 車間(裝置)布置的重要性8車間 (裝置)布置的組成8車間 (裝置)布置的原則93 工藝論證103.1 纖維素發(fā)酵乙醇工藝概述103.2 工藝條件及說明103.2.1 預(yù)處理工序103.2.2 酶水解工序12發(fā)酵工序133.2.4 蒸餾工序174 工藝計(jì)算204.1酒精生產(chǎn)過程的總物料衡算20原料消耗量計(jì)算204.1.2 發(fā)酵醪量的計(jì)算20成品與廢醪量的計(jì)算214.1.4 年產(chǎn)量為10萬噸燃料酒精的總物料衡算224.2 酒精生產(chǎn)各工段物料和能量衡算234.2.1 預(yù)處理工段23水解工段23發(fā)酵工序24蒸餾工序244.3 供水衡算28精餾塔分凝器冷

10、卻用水28成品酒精冷卻和雜醇油分離器稀釋用水29用水量294.4 其他衡算29供氣衡算29供電衡算305設(shè)備選型及計(jì)算315.1預(yù)處理設(shè)備31調(diào)漿桶31蒸煮罐個(gè)數(shù)計(jì)算31蒸煮罐的輪廓尺寸計(jì)算325.2水解罐的計(jì)算32水解罐體積32水解罐數(shù)量325.3發(fā)酵設(shè)備設(shè)計(jì)33發(fā)酵罐容積和個(gè)數(shù)的確定33冷卻面積和冷卻裝置主要結(jié)構(gòu)尺寸34發(fā)酵罐壁厚36進(jìn)出口管徑37其他罐體設(shè)備375.5其他設(shè)備38蒸餾設(shè)備38換熱器的選型386車間常用布置設(shè)計(jì)406.1發(fā)酵設(shè)備406.2蒸餾設(shè)備及其他設(shè)備40結(jié) 論41謝 辭42參考文獻(xiàn)43外文資料44譯文501 引 言1.1 酒精發(fā)展現(xiàn)狀1.1.1 酒精的概述1.1.2

11、酒精發(fā)酵工藝1.2 纖維質(zhì)概述 纖維素的結(jié)構(gòu)與性質(zhì) 1.2.2 半纖維素的結(jié)構(gòu)與性質(zhì) 1.2.3 木質(zhì)素的結(jié)構(gòu)與性質(zhì) 1.3 纖維質(zhì)酒精發(fā)酵現(xiàn)狀1.4 本課題的目的和意義2 設(shè)計(jì)概論2.1畢業(yè)設(shè)計(jì)的題目2.2畢業(yè)設(shè)計(jì)的目的2.3 畢業(yè)設(shè)計(jì)的任務(wù)2.4 設(shè)計(jì)的指導(dǎo)思想2.5 設(shè)計(jì)的依據(jù)2.6 生產(chǎn)方案的確定和產(chǎn)品方案2.7 廠址選擇的總原則4廠址選擇的重要性廠址選擇的基本任務(wù)2.7.3廠址選擇的一般原則2.8工廠總平面布置工廠總平面布置的一般原則2.9車間布置2.9.1車間 (裝置)布置的重要性2.9.2車間 (裝置)布置的組成42.9.3車間 (裝置)布置的原則3.1 纖維素發(fā)酵乙醇工藝概述3

12、.2 工藝條件及說明 預(yù)處理工序（1）目的（2）工藝流程（3）工藝參數(shù)（4）主要設(shè)備 酶水解工序（1）目的 （2）工藝流程（3）工藝參數(shù)（4）生產(chǎn)設(shè)備發(fā)酵工序（1）目的（2）原料（3）工藝流程圖3-4 發(fā)酵工序工藝流程圖（4）工藝參數(shù)表3-3 發(fā)酵過程工藝參數(shù)（5）發(fā)酵醪的成熟指標(biāo)表3-4 發(fā)酵醪的成熟標(biāo)準(zhǔn)（6）清洗、滅菌（7）空氣壓縮及二氧化碳回收（8）主要設(shè)備3.2.4 蒸餾工序11（1）目的（2）工藝流程圖3-5 酒精蒸餾工藝流程圖（3）工藝參數(shù)表3-5 酒精蒸餾工藝參數(shù)13（4）4 工藝計(jì)算酒精生產(chǎn)過程的總物料衡算原料消耗量計(jì)算（基準(zhǔn)：1噸無水乙醇）（1）玉米秸稈原料生產(chǎn)酒精的總化學(xué)反

13、應(yīng)式為：（2）生產(chǎn)1000kg無水酒精的理論纖維素消耗量：4.1.2 發(fā)酵醪量的計(jì)算 4.1.3成品與廢醪量的計(jì)算 (kJ/kg.k) kJ kJ4.1.4 年產(chǎn)量為10萬噸燃料酒精的總物料衡算4.2 酒精生產(chǎn)各工段物料和能量衡算4.2.1 預(yù)處理工段Q2=c'·m·t2c'水解工段(g/h)發(fā)酵工序蒸餾工序圖2-1 醪塔的物料和熱量平衡圖表4-3 年產(chǎn)10萬噸酒精蒸餾工段精餾塔物料熱量衡算匯總表4.3 供水衡算4.3.1 精餾塔分凝器冷卻用水4.3.2 成品酒精冷卻和雜醇油分離器稀釋用水4.3.3 總用水量4.4 其他衡算4.4.1供氣衡算4.4.2供電衡

14、算5設(shè)備選型及計(jì)算5.1預(yù)處理設(shè)備調(diào)漿桶 拌料桶總?cè)莘e決定于操作周期長短，調(diào)漿桶的總?cè)莘e可按下式求得: V總=式中 G酒精廠每小時(shí)投人原料量(kg/h),取 n加水比 t調(diào)漿桶操作周期(min)，一般取30min左右 調(diào)漿后醪密度，玉米秸稈加水比為1：3時(shí)約為950kg/m3調(diào)漿罐填充系數(shù)，一般0.8V總= 調(diào)漿桶的個(gè)數(shù)為n= V總/ V調(diào)=199/51.5=3.86（個(gè)）調(diào)漿桶由于是分批投料，為了滿足連續(xù)蒸煮的要求，一般應(yīng)設(shè)兩組，一組調(diào)漿桶取4個(gè)。5.1.2蒸煮罐個(gè)數(shù)計(jì)算玉米秸稈加水比為1：3時(shí)，醪密度約為950kg/m35.1.3蒸煮罐的輪廓尺寸計(jì)算185.2水解罐的計(jì)算水解罐體積水解罐數(shù)

15、量5.3發(fā)酵設(shè)備設(shè)計(jì)5.3.1發(fā)酵罐容積和個(gè)數(shù)的確定5.3.2冷卻面積和冷卻裝置主要結(jié)構(gòu)尺寸5.3.3發(fā)酵罐壁厚205.3.4進(jìn)出口管徑215.3.4其他罐體設(shè)備5.5其他設(shè)備5.5.1蒸餾設(shè)備11、18、22蒸餾設(shè)備采用差壓蒸餾兩塔系機(jī)組，可以充分利用過剩的溫差，也就是減少了有效熱能的損失。參照 “上海酒精總廠差壓蒸餾兩塔系機(jī)組方案”，設(shè)計(jì)蒸餾機(jī)組如下：（1）醪塔：仿法國方形浮閥塔板，塔徑3000mm，22板，板間距500mm，塔高14800mm，裙座直徑3000mm，高5000mm；（2）精餾塔：仿法國方形浮閥塔板，塔徑2600mm，65板，板間距350mm，塔高26500mm，裙座直徑2

16、600mm，高5000mm。5.5.2換熱器的選型調(diào)漿桶蒸煮罐7阮奇城 : 4吳德榮. 化工工藝設(shè)計(jì)手冊 第四版(上下冊) M, 化學(xué)工業(yè)出版社20095謝林, 呂西軍. 玉米酒精生產(chǎn)新技術(shù). M, 北京中國輕工業(yè)出版社2000100-1506賈樹彪等. 新編酒精工藝學(xué)M .北京化學(xué)工業(yè)出版社2004.7-3047姚汝華.酒精發(fā)酵工藝學(xué)M .華南理工大學(xué)出版社1999: 1-2538張鵬. 秸稈纖維素水解與木糖酒精發(fā)酵. 北京化工大學(xué)博士學(xué)位論文2010: 1-59王鐸, 常春. 木質(zhì)纖維素原料酶水解產(chǎn)乙醇工藝的研究進(jìn)展. 生物加工過程, 2010: 3-610李秋園. . : 2-511章克

17、昌, 吳佩琮. 酒精工業(yè)手冊M. 中國輕工業(yè)出版, 1989: 1-23112陳其斌（美）. 甘蔗糖手冊（下冊）M. 輕工業(yè)出版社, 1988:1-57413章克昌. 酒精與蒸餾酒工藝學(xué)M . 中國輕工業(yè)出版社, 2002: 1-56714賈樹彪等. 新編酒精工藝學(xué)M .化學(xué)工業(yè)出版, 2004: 1-33315許開天. 酒精蒸餾技術(shù)(第二版)M . 中國輕工業(yè)出版, 1998:1-43616馬贊華. 酒精高效清潔生產(chǎn)新工藝M. 化學(xué)工業(yè)出版社, 2003: 1-27317. . : 18郭年祥. 化工過程及設(shè)備M. 冶金工業(yè)出版社2003:1-41019邱樹毅. 生物工藝學(xué)M. 化學(xué)工業(yè)出版

18、社2009: 1-21920董大勤. 化工設(shè)備機(jī)械基礎(chǔ)M. 化學(xué)工業(yè)出版社2002: 1-51221鄭裕國. 生物工程設(shè)備M. 化學(xué)工業(yè)出版社2007: 1-33522 張君, 劉德華. . : . . : 外文資料Grain pearling and very high gravity (VHG) fermentation technologies for fuel alcohol production from rye and triticaleAbstractA SATAKE laboratory abrasive mill was used for rye and triticale

19、grain processing. About 12% of dry grain mass was removed after three and five successive abrasions for triticale and rye, respectively. Starch contents in the pearled grain were increased by 8.0% for triticale, and by 7.1% for rye. The pearled rye and triticale were ground and fermented by active d

20、ry yeast for fuel alcohol production by very high gravity (VHG) fermentation at 20°C. VHG technology was applied to increase final ethanol concentrations in the fermentors from 9.5 10.0% (v/v) (normal gravity) to 12.9 15.1% (v/v). The grain pearling process coupled with VHG technology further r

21、aised the ethanol concentration to 15.7 16.1% (v/v). Partial removal of outer grain solids in an alcohol plant would improve plant efficiency and decrease energy requirements for mash heating, mash cooling, and ethanol distillation. 1. IntroductionBecause wheat prices have increased during recent ye

22、ars,less expensive alternative crops such as rye and triticale are being considered as feedstocks by fuel alcohol plants in Western Canada. Corn, the major feedstock used by mostfuel ethanol plants operated in the United States, is not generally available in Western Canada. Previous studies have sho

23、wn that both rye and triticale are fermentable at normal and very high grav ity levels. The ability to ferment these grains, as measured by fermentation efficiency and duration for the completion of fermentation, were comparable with those of wheats, barley and oats.To increase the efficiency of an

24、existing fuel alcohol plant, two potential improvements would be the increase in starch concentration in the feedstock and the use of high or very high gravity(VHG) fermentation technology.VHG technology refers to the use of mashes with 300g or more dissolved solids per litre. Most distillers and fu

25、el alcohol manufacturers ferment grain mashes at normal gravity levels of 20 24 g of dissolved solids per 100 g. With wheat, oats, barley, rye and triticale, VHG fermentation technology has proven successful in increasing the final ethanol concentration and reducing processing costs. It .is also pos

26、sible to increase starch content in feedstock by partial removal of grain bran. Processes .for pearling wheat using modified rice polishing equipment have been developed .as the TrigoTecand PeriTec Systems. An excellent review of recent applications of pearling grains, including the two patented sys

27、tems, has been published by Dexter and Wood.A recent study on wheat preprocessing performed on a three- stage experimental Allis Chalmers Mill showed that starch contents were increased from 54 57% to 64 68% (as is basis) in flour. The concentrations of ethanol in beer were subsequently increased fr

28、om an average of 10·6% (w/v) to 12.4% .(w/v) . Grain abrasion per- formed on barley,rye and triticale by abrasive milling carried out on the SATAKE Testing Mill (model TM05,SATAKE Co.,Tokyo,Japan), removed 7.7 21.7% of outer grain solids, which was predicted to decrease gas consumption by 3.5 1

29、1.4%,and power consumption by 5.2 15.6% in a 10 million litre ethanol plant.The objectives of the current study were to determine the effect of grain pearling combined with the use of VHG fermentation technology on fermentation performances of rye and triticale for fuel alcohol production.2. Materia

30、ls and methods2.1. Rye and triticale samplesFall rye (PRIMA) and triticale (AC COPIA) were both developed by and obtained from Agriculture and AgriFood Canada (Saskatoon, SK Canada). The fall rye had a moisture content of 12.16±0.02%, and a starch content of 62.35± 1.31% (dry basis). The t

31、riticale had a moisture content of 10.50±0.02%, and a starch content of 63.13±1.32% (dry basis).2.2. MillingBefore milling,all grains were tempered or adjusted to 12.5% wb moisture levels for 18 h.The SATAKE abrasive testing mill (Model TM05, SATAKE Co., Tokyo,Japan), equipped with a mediu

32、m abrasive roller (stone) No.36,and a round hole (1.9mm diameter) screen,was used in all experiments.The roller speed was 750 rpm.The milling sequence included three and five abrasions for triticale and rye, respectively.Each abrasion lasted for 30 s. After each abrasion, the abraded fines were coll

33、ected by brushing and sifting,and the pearled grains were weighed be- fore the next abrasion.The milling conditions applied were predetermined to remove bran material while minimizing starch loss to the fines.The number of abrasions applied on triticale and rye was designed to give a final accumulat

34、ed grain mass removal rate of12%.2.3. Chemical analysisSamples of whole grain,pearled grain and abraded fine fractions were analysed for moisture and starch contents.Fermentation stillages were measured by the standard AACC procedures for moisture,crude protein,crude fat,and ash and the AOAC method

35、for total dietary fibre.Protein contents of the samples were calculated using the nitrogen-to-protein conversion factor of 5.7,based on the recommendation of Sosulski and Imafidon.Starch was measured as glucose after hydrolysis with -amylase and amyloglucosidase.2.4. Enzymes, reagents, and chemicals

36、A powdered fungal enzyme preparation from Tri - choderma 6iride, Roxazyme G, was provided by Hoff- mann-La Roche (Mississauga,ON,Canada). The Roxazyme G contained cellulase activity of 8000 IU/g and xylanase activity of 43 350 IU/g . 2.5. FermentationThe fermentors were connected to a D3-G water bat

37、h circulator,and equilibrated to 30°C for 15 min.Either 5 ml of sterile distilled water, or 5 ml of filter-sterilized urea solution,a common and effective yeast food, were added to each fermentor to provide a final concentration of 0 or 16 mm,respectively.Then,8 ml of Allcoholase II preparation

38、 was added per kilogram of pearled grain mashed to saccharify the dextrins to fermentable sugars.After 30 min, the temperature of the fermentor was lowered and maintained at 20°C throughout the fermentation, and the fermentor was inoculated with 6 ml of active dry yeast inocula (inoculated at a

39、pproximately 30 35 million cells per gram of mash).The fermentations were monitored until all dissolved solids were consumed.3.Results and conclusion3.1.Effect of grain pearling and VHG technology on ethanol yield, fermentation efficiency and ethanol concentrationFermentation results from the curren

40、t study were compared with those from whole grain normal gravity fermentations and whole grain VHG fermentations. VHG fermentations and grain pearling did not result in significant changes in average fermentation efficiencies.The average fermentation efficiencies obtained from the three studies were

41、 between 90.0 and 91.4%. Urea supplementation led to lower fermentation efficiencies,as more sugars were used for cell growth, a trade-off in exchange for faster fermentation rates and reduced fermentation cycles. Such decreases in fermentation efficiencies were more significant when less nutrient w

42、ere present in the fermentation media. Pearling removed part of the grain outer layers and therefore pearled grain may have deficiencies in some minerals, vitamins, and amino acids which normally promote fermentation.Coupled with the application of VHG, pearled grains showed significant declines in

43、fermentation efficiencies when urea was added.Such declines might be corrected if the concentrations of urea supplementation were reduced from the current 16 mm to lower levels.The application of VHG technology led to average ethanol yields per tonne of feedstock (dry basis) of 421 and 417 l for who

44、le grain normal gravity and VHG fermentations,respectively.The average ethanol yield per tonne of feedstock for pearled grain using VHG fermentation was455 l.Therefore, the ethanol per tonne of feedstock was increased by 8.5%, due to concentrated starch contents in the pearled grains. This increase

45、was proportional to the increase in starch content in the feedstock.However,increases in ethanol production were actually much greater when they were calculated on a fermentation volume basis.The VHG technology and grain pearling showed great benefits for increasing final ethanol concentration in th

46、e fermentation vessels. With normal gravity fermentation, the final ethanol concentrations were between 9.5 and 10.0% (v/v).VHG technology at the level applied here raised sugar concentrations by 33% as a result of reduction of water use during mashing and fermentation.The final ethanol concentratio

47、ns were thus increased to 12·9 14·8% (v/v).This is an average increase of 47%. Grain pearling increased the starch content in the fermentation feedstock by 7 8%. Cou- pled with the VHG technology,the final ethanol concentrations were further increased to 15.7 16.1% (v/v). This implied that

48、 the combined use of grain pearling and VHG technologies would increase ethanol production by an average of 64%,for a given fermentor volume, compared with normal gravity fermentations. Although normal gravity fermentations with low levels of sugar concentration would have short fermentation cycles,

49、 recent studies (unpublished results) on optimization of fermentation process showed that VHG gravity fermentation cycles could be significantly reduced by applying relatively high fermentation temperatures (25 30°C).VHG fermentation technology that reduces about 33% of water during mashing and

50、 fermentation process would lead to a significant saving in energy consump- tion for mash heating, cooling and ethanol distillation. Grain pearling removes a significant part of grain solids which results in reduced energy input and less fermentation stillages.The combined savings in energy expenses

51、, and increases in ethanol production,would raise fuel alcohol plant efficiency andcompetitiveness.3.2. Chemical composition of stillageStillage samples(spent grain) from rye and triticale fermentations contained mostly protein and total dietary fibre (TDF).There were few differences between stillag

52、e composition obtained from whole grain normal gravity and VHG fermentation.Protein and TDF each accounted for approx. 30% of stillages, on a dry basis. The remainder of the stillages were ash,fat, residual recalcitrant starch, yeast cells and nonvolatile fermentation by-products.The fact that stillages from rye were lower in protein content was due to the initial lower protein content in rye grain.Lower than expected TDF content in rye stillages