O abordare moderna pentru producerea eficienta a biodieselului

Autor/autori: Nicolae Sdrula, Ioan Frasineanu

Rezumat: Uniunea Europeana este puternic dependenta in prezent de combustibilii fosili pentru nevoile crescinde de transport. Biocombustibilii pot oferi o alternativa importanta la cei fosili pe termen scurt si mediu. Dintre acestia, biodieselul este un combustibil ce poate fi produs direct din uleiuri vegetale, grasimi animale, seu sau ulei uzat de la gatit. Biodieselul poate fi utilizat in orice motor diesel conventional, nemodificat, reduce emisia de dioxid de carbon, poate fi utilizat ca atare sau in amestec in orice proportie cu dieselul fosil, este biodegradabil si netoxic si nu este considerat material periculos. Cea mai des aplicata tehnologie de producere biodiesel este din uleiuri vegetale sau animale care contin uleiuri si grasimi de calitate. Se obtine metil esterul brut si produsul secundar glicerina prin reactia de schimbare de ester, la adaugare de alcool metilic in prezenta de catalizator pe baza de metoxid de sodiu. Biodieselul se obtine dupa distilare iar glicerina urmeaza un proces de purificare prin distilare la vid. Actualul proces are in special probleme datorita compozitiei foarte variate atit ale biodieselului brut cit si ale glicerinei brute, urmat de faze de separare destul de complicate si energointensive, care se reflecta negativ in pretul final al produselor. Studiul de fata are in vedere aplicarea unor tehnologii de membrana atit pentru faza de reactie (trans-esterificare) cit si pentru cea de purificare a glicerinei, ca produs secundar, si se bazeaza pe noutati in domeniu relevate in lucrari de specialitate, informatii web si pe aplicatii demonstrative. O abordare comparativa a procedeului clasic de reactie dintre materia grasa si metanol ce are loc intr-un reactor cu agitare, fata de noul procedeu unde reactia de trans-esterificareare loc intr-un reactor cu membrana, precum si comparatia dintre procedeul clasic de purificare a glicerinei prin distilare la vid fata de abordarea purificarii prin membrane, scoate in evidenta avantajul procesului integrat utilizind procedeele de membrana. Rezultatele obtinute trebuiesc confirmate de un studiu de fezabilitate pentru o capacitate ceruta de beneficiar.

Cuvinte cheie: biocombustibili, biodiesel, trans-esterificare, reactor cu membrana, purificare glicerina cu membrane


Abstract: European Union is actually strongly depended on fossil fuels for growing transport needs. The biofuels can offer an important alternative towards fossils for short and medium term. Out of these, the biodiesel is a fuel which can be produced straight from vegetable oils, animal fats, tallow or used cooking oil. Biodiesel can be used in any conventional motor, unmodified, reduces dioxide emission, can be directly or blending in any proportion with fossil fuel utilised, is biodegradable and non toxic and not considered dangerous material. The most applicable biodiesel technology comes from vegetable or animal oils which contain quality oils or fats. It is obtain the crude methyl ester and the by-product glycerol by the exchange ester reaction, when methyl alcohol is added in the presence of the sodium methoxid as catalyst. The biodiesel is obtained after distillation and glycerol follows a purification process including vacuum distillation. The current process has some problems due to especially the versatile composition of crude biodiesel or glycerol, involving complex, energy-intensive separation stages, reflected in a negative modus upon the final costs of products. The actual study provides the applying of some membrane technologies both for reaction stage (trans-estherification) and glycerol purification, as by-product and is based on the brand new information and achievements in the domain, found by speciality works, web sites or demonstrative applications. A comparative approach of the existing reaction process between the raw fat material and methanol, occurring in a stirring reactor, against the new process where the trans-estherification take place in a membrane reactor, doublet by the comparison between the current process of glycerol purification by vacuum distillation and the new process based on membrane separation, pointed clearly out the advantage of the new integrated membrane process. The attempt has to be demonstrate by a deep feasibility study for a certain capacity.

Keywords: biofuels, biodiesel, trans-esterification, membrane reactor, membrane glycerol purification

 

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