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Title:OPTIMIRANJE PROCESOV PROIZVODNJE BIOPLINA IZ ŽIVALSKIH IN DRUGIH ORGANSKIH ODPADKOV Z UPORABO RAČUNALNIŠKO PODPRTE PROCESNE TEHNIKE
Authors:Drobež, Rozalija (Author)
Kravanja, Zdravko (Mentor) More about this mentor... New window
Novak Pintarič, Zorka (Co-mentor)
Files:.pdf DR_Drobez_Rozalija_2012.pdf (4,74 MB)
 
Language:Slovenian
Work type:Dissertation (m)
Organization:FKKT - Faculty of Chemistry and Chemical Engineering
Abstract:Eden glavnih okoljevarstvenih problemov živilskopredelovalne industrije je nenehno naraščajoča proizvodnja odpadkov različnega izvora. Proizvodnja bioplina iz organskih in živalskih odpadkov z anaerobno fermentacijo je primeren način za predelavo teh odpadkov. Predelava prinaša mnoge okoljske, ekonomske in družbene koristi. Po drugi strani procesna sistemska tehnika s svojimi vrhunskimi orodji, ki temeljijo na matematičnem programiranju oz. optimizaciji, omogoča generiranje optimalnih in dopustnih rešitev za doseganje višjega nivoja konkurenčnosti proizvodnih podjetij. V doktorski disertaciji obravnavamo uporabo algoritemskih metod procesne integracije v industrijskem merilu in sicer na primeru velikega živilskopredelovalnega podjetja za doseganje okoljsko sprejemljivih rešitev pri ravnanju in predelavi živalskih substratov in organskih odpadkov. Na osnovi iniciative živilskopredelovalne industrije smo za sintezo procesov proizvodnje bioplina razvili matematični model, ki omogoča selekcijo optimalnega procesa proizvodnje bioplina in sestave vhodnega substrata ter simultano optimizacijo snovnih tokov, investicijskih sredstev in obratovalnih stroškov procesa. Z matematičnim programiranjem smo postopoma najprej izvedli sintezo procesa za proizvodnjo bioplina, nato simultano sintezo s toplotno integracijo in nazadnje še sintezo procesa s simultano sintezo omrežja toplotnih prenosnikov. Tako smo najprej razvili mešano celoštevilski nelinearni (MINLP) model za sintezo procesov proizvodnje bioplina. V primeru simultane toplotne integracije in sinteze procesa smo ga nadgradili z modelom za simultano toplotno integracijo (Duran in Grossmann, 1986), ki smo ga za potrebe industrijskega problema prilagodili za konstantne temperature in izotermno mešanje procesnih tokov. Model omogoča določitev optimalne procesne sheme in minimalne porabe pogonskih sredstev za množico alternativnih toplih in hladnih tokov procesa proizvodnje bioplina. Z omenjeno modifikacijo simultanega modela toplotne integracije in s konveksifikacijo konkavnih investicijskih členov v namenski funkciji z odsekovno linearizacijo smo razvili mešano celoštevilski linearni model (MILP), ki omogoča reševanje industrijskega problema do globalnih rešitev. Ker pri reševanju sinteznih problemov praviloma dobimo boljše rešitve, če obravnavamo snovne in energetske bilance ter investicijska sredstva in obratovalne stroške hkrati, smo se v končni fazi sinteze procesa odločili, da tudi omrežje toplotnih prenosnikov (OTP) pri proizvodnji bioplina sintetiziramo simultano s procesom. Tako smo celotni sintezni problem zapisali na osnovi dveh med seboj povezanih superstruktur v obliki mešano celoštevilskega nelinearnega problema. Pri tem smo predlagali novo superstrukturo procesnih tokov, kjer se lahko procesni tokovi ne-izotermno mešajo in kombinirajo. Predhodno razviti model MINLP za sintezo procesa proizvodnje bioplina smo nadgradili z večstopenjskim modelom za simultano sintezo omrežja toplotnih prenosnikov (Yee in Grossmann, 1990), ki smo ga modificirali za potrebe simultanega pristopa in nove superstrukture procesnih tokov. Tako dodelan model omogoča simultano določitev optimalne procesne sheme z optimalnim omrežjem toplotnih prenosnikov pri optimalni sestavi in porabi vhodnih surovin, optimalnih obratovalnih stroških in investicijskih sredstvih.
Keywords:sinteza procesov, bioplin, anaerobna fermentacija, živalski odpadki, optimiranje, toplotna integracija, mešano celoštevilsko nelinearno programiranje, metoda odsekovne linearizacije, omrežje toplotnih prenosnikov, industrijska aplikacija
Year of publishing:2011
Publisher:[R. Drobež]
Source:Maribor
UDC:66.011:628.477.042(043.3)
COBISS_ID:15798806 Link is opened in a new window
NUK URN:URN:SI:UM:DK:WQQPTQBP
Views:2948
Downloads:232
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Categories:KTFMB - FKKT
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Secondary language

Language:English
Title:Optimization of processes for biogas production from animal and other organic wastes using the computer aided process engineering
Abstract:The main environmental problem relating to the meat processing industry is the constantly increasing production of wastes from various sources. Anaerobic digestion can be regarded as an efficient, economical, and sustainable solution for converting organic and animal wastes into precious biogas and other products. On the other hand, process systems engineering with its efficient computer-aided, mathematical programming-based tools, enables us to generate optimal and useful solutions and thus facilitate the achievement of higher competitiveness from process industries. In this respect, the topic of this PhD thesis is devoted to the field of process integration: different algorithmic methods were applied in order to obtain economically- efficient and yet, environmentally benign solutions for the utilization of different animal and organic wastes within an existing large-scale meat company. A mathematical model for the synthesis of biogas process was developed based on the initiative of this meat company. This model enables the selection of an optimal biogas process flow sheet, optimal consumption of substrates and optimal production of biogas and other products, by the simultaneous optimization of mass flow rates, operating costs, and investment of the process. The mathematical programming approach was applied for increasing complexities, firstly to the synthesis of biogas process alone, then to the simultaneous heat integration and synthesis of the biogas process and, finally, to the simultaneous synthesis of the biogas process and its integrated heat exchanger network. Firstly, a mixed integer nonlinear programming (MINLP) model for the synthesis of biogas processes was developed. This model was then upgraded with heat balances and extended by a simultaneous heat integration model developed by Duran and Grossmann (1986) in order to perform the simultaneous heat integration and synthesis of the biogas process. The original heat integration model was modified in order to correspond to the specific needs of industrial applications. It was assumed that all units were operating at fixed temperatures and the process streams mixed isothermally. By applying the mentioned modifications and replacing concave investment terms within the objective function with convex ones by the use of a piecewise linearization method, we developed a mixed integer linear (MILP) model, which was capable of obtaining global optimal solutions for the given industrial problem. This model determines globally optimal process schemes for a set of alternative hot and cold process streams at minimum consumption of utilities. As superior solutions to the synthesis problems were expected when the mass and energy balances, as well as the capital and operating costs were optimized simultaneously, during the final stage of our biogas process synthesis we performed the process synthesis simultaneously with the synthesis of its heat integrated heat exchanger network (HEN). The combined synthesis problem was formulated as an MINLP problem based on the mathematical description of combined process/HEN superstructure. In addition, a new process streams superstructure was proposed where the streams could be non-isothermally mixed and merged into a significantly smaller set of streams in order to obtain optimal and yet simpler solutions. The final synthesis model thus consists of the MINLP model for biogas process synthesis, the MINLP model for the simultaneous synthesis of heat integrated HEN (Yee in Grossmann, 1990), now modified to enable the simultaneous process and its HEN synthesis, and the mass and energy balances models for the process streams superstructure. The developed MINLP model enables the selection of an optimal biogas process scheme together with its HEN at the optimal composition and consumption of inlet substrates, optimal operating costs, and investment.
Keywords:process synthesis, biogas, anaerobic fermentation, animal wastes, optimization, heat integration, mixed integer nonlinear programming, method of piecewise linearization, heat exchanger network, industrial application


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