<p>U radu su ispitane mogucnosti separacaije<br />nesaharoznih jedinjenja ultrafiltracijom iz rastvora<br />B i C šecera sadržaja suve materije 60 i 30 <sup>o</sup>Bx.<br />Eksperimentalna ispitivanja su izvedena na<br />keramickim membrana sa otvorom pora od 20 i 5<br />nm, bez i sa primenom statickog mešaca kao<br />promotora turbulencije. Tokom recirkulacije i<br />koncentrovanja napojne smeše pracen je uticaj<br />nezavisno promenljivih (transmembranskog<br />pritiska, protoka, temperature i vremena trajanja<br />procesa) na fluks, boju, mutnocu i kvocijent<br />cistoce permeta. Ispitan je uticaj statickog mešaca<br />na prljanje membrane, na potrošnju energije i<br />smanjenja proizvodnih troškova. Eksperimentalni<br />rezultati su jasno pokazali da se najveca razlika u<br />vrednosti fluksa permeata rastvora B šecera dobija<br />kada se uporedi nacin rada bez i sa upotrebom<br />mešaca. Ta razlika iznosi 30% na 80<sup>o</sup>C, odn. 65%<br />kada se temperatura održava na 70<sup>o</sup>C. Pri<br />ultrafiltraciji rastvora C šecera, koji sadrži<br />mnogostruko vecu kolicinu nesaharoznih<br />jedinjenja, registruje se brža koncentraciona<br />polarizacija, te se pri istim uslovima postiže za<br />70% manji fluks od fluksa permeata rastvora B<br />šecera. Sadržaj saharoze permeata i retentata se ne<br />menja tokom ultrafiltracije, nema merljive<br />retencije saharoze, što je presudno za buducu<br />primenu ovog separacionog postupka u industriju<br />šecera. Dekoloracija rastvora B šecera bez<br />upotrebe mešaca ?? na nivou 40%, ? postiže se na<br />pritisku nižem od 6 bar i protoku od 250 L/h.<br />Upotrebom mešaca se efekat dekoloracije<br />poboljšava za oko 60%, i to pri protoku ispod 200<br />L/h. Izdvajanje bojenih materija pri ultrafiltraciji<br />rastvora C šecera je prividno manje efikasno, jer<br />ne prelazi vrednost od 25% racunato na napojnu<br />smešu, mada se u apsolutnim vrednostima iz<br />rastvora B i C šecera izdvoji približno ista kolicina<br />bojenih materija (900 IJ). Ultrafiltracijom se<br />mutnoca napojne smeše redukuje za 85%.<br />Ispitivanja prljanja membrane pri ultrafiltraciji su<br />pokazala da koncentraciona polarizacija i<br />formiranje sloja sastavljenog od nesaharoznih<br />jedinjenja na površini membrane predstavljaju<br />dominantan udeo ukupnog hidraulicnog otpora. U<br />membrani sa otvorom pora 20 nm, tokom<br />ultrafiltracije meduproizvoda f?ze kristalizacije,<br />otpor poraste usled prljanja za 20 – 50 puta, a u<br />membrani sa otvorom pora 5 nm za 100 – 300 puta<br />u odnosu na otpor ciste membrane. Korišcenje<br />mešaca je opravdano u intervalu gubitaka<br />hidraulicke snage od 0 – 7 W, jer se time postiže<br />povecanje fluksa i do 60%. Pri vecim gubicima<br />hidraulicne snage, odn. pri vecim brzinama<br />proticanja, nivo turbulencije u praznoj cevi je<br />znacajan, tako da se i bez upotrebe mešaca<br />registruju vece vrednosti fluksa. Povecanje stepena<br />koncentrovanja napojne smeše sa 1,0 na 1,2 prati<br />smanjenje ukupnih prizvodnih troškova u opsegu<br />od 30 – 77% kada se proces ultrafiltracije realizuje<br />uz upotrebu mešaca.</p> / <p>This work presents the study of possibility to<br />separate of non-sucrose compounds from B and C<br />sugar solutions, with a dry matter content of 60 and<br />30 oBx by ultrafiltration. Experimental<br />investigations were performed on ceramic tubular<br />20 and 5 nm pore diameters membranes, with and<br />without kenics static mixer as turbulence promoter.<br />The influence of independent parameters<br />(transmembrane pressure, flow rate, temperature<br />and ultrafiltration time duration) on permetate flux,<br />colour, turbidity and purity during feed<br />recirculation and feed concentration were<br />examined. The efficiency of static mixer was<br />investigated on membrane fouling, on energy<br />consumption and on economical calculations. The<br />experimental results showed that, the greatest flux<br />difference of B sugar solution was obtained when<br />the operation mode was with a static mixer in<br />comparation to the operation mode without one,<br />showing 30% difference at temperature 80 oC and<br />65% at 70 oC. While ultrafiltering the C sugar<br />solution, which contains more non-sucrose<br />compounds, a faster concentration polarization was<br />noticed, thus at the same working conditions 70%<br />less flux was reached in comparison with to the B<br />sugar solution permeate flux. The permeate and<br />retentate sugar content did not changed during<br />ultrafiltration, there is no measurable retention of<br />sucrose, which is important for the implementation<br />of this type of separation into sugar industry. The<br />decoloration of B sugar solution without static<br />mixer is 40%, and can be reached at<br />transmembrane pressure bellow 6 bar and flow rate<br />of 250 L/h. By using a static mixer the decoloration<br />effect is improved for 60%, when flow rate is held<br />bellow 200 L/h. The separation of coloured<br />compounds during ultrafiltration of C sugar<br />solution is apparently less efficient since the value<br />did not reach 25% calculated on feed, even though<br />measured in absolute values the same level of<br />coloured compounds was separated from B and C<br />sugar solution (900 IU). The turbidity of B and C<br />solution was reduced by ultrafiltration for 85%.<br />The examinations of membrane fouling during<br />ultrafiltration showed that the concentration<br />polarization and formation of a non-sucrose<br />compound layer on the membrane surface are<br />dominant parts of the total hydraulic resistance.<br />During ultrafiltration of intermediate products of<br />sugar crystallization using 20 nm pore membrane<br />diameter the resistance increased for 20 – 50 times<br />due to fouling. Using a 5 nm pore diameter<br />membrane the resistance increased for 100 – 300<br />times comparing to clean membrane. The use of<br />static mixer is justified when 0 – 7 W loss of<br />hydraulic power was determined, because in that<br />interval a 60% flux increase was detected. At<br />higher levels of hydraulic power loss, and at higher<br />values of flow rates the turbulency in empty tubular<br />membrane is significant, so even without using<br />static mixers higher values of flux are detected.<br />When a static mixer was used with the increase of<br />volume concentration ratio from 1,0 to 1,2 the total<br />production costs decreased in a range of 30 – 77%.</p>
| Identifer | oai:union.ndltd.org:uns.ac.rs/oai:CRISUNS:(BISIS)71292 |
| Date | 22 February 2008 |
| Creators | Šereš Zita |
| Contributors | Gyura Julianna, Tekić Miodrag, Vatai Gyula |
| Publisher | Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, University of Novi Sad, Faculty of Technology at Novi Sad |
| Source Sets | University of Novi Sad |
| Language | Serbian |
| Detected Language | English |
| Type | PhD thesis |
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