| | SLO | ENG | Cookies and privacy

Bigger font | Smaller font

Show document Help

Title:Synthesis of regional networks for biomass and biofuel production
Authors:ID Lam, Hon Loong (Author)
ID Kravanja, Zdravko (Mentor) More about this mentor... New window
ID Klemeš, Jiří (Comentor)
Files:.pdf DR_Lam_Hon_Loong_2011.pdf (4,25 MB)
MD5: 6DD0B7A10F49E3DC8E6052065FF7FE4B
PID: 20.500.12556/dkum/ed1ce14f-691b-4658-b3a5-5531a8d8eef1
 
Language:English
Work type:Dissertation
Organization:FKKT - Faculty of Chemistry and Chemical Engineering
Abstract:This thesis presents two different approaches to the synthesis of regional networks for biomass and biofuel production and supply: Mathematical Programming and Graph Theoretic approach. The optimisation criterion for both approaches is the maximisation of profit. The first approach is based on a generic optimisation model of biomass production and supply networks. This superstructure approach is based on a flexible number of network layers: plantation, collection using a pre-treatment, process, and consumption. A Mixed Integer Linear Programming (MILP) model has been successfully developed during this work. However, the solution of this biomass production network model is very challenging due to the large sizes of the networks and the number of interconnections. The huge number of redundant variables reduces model efficiency (time taken to solve the model and the interpretation of the results). This model when representing very large size networks cannot be solved over a reasonable time even by professional mathematical programming software tools. Several model-size reduction techniques are therefore proposed for the solution of large-scale networks. In particular, methods are proposed for (i) reducing the connectivity within a biomass supply chain network by setting the maximum allowable distance between the supply zones to the collection centres, (ii) eliminating unnecessary variables and constrains to reduce the zero-flows in the full model, and (iii) aggregating the network and hence the synthesis process by merging the collection centres. The network synthesis is also carried out by P-graph (Process Graph) tools. P-graph is a directed bipartite graph, having two types of vertices — one for operating units and another for those objects representing material or energy flows/quantities. In this procedure, firstly a maximum feasible superstructure for biomass production network is generated from which the optimal structure is then selected by the Branch and Bound method. This graph-based method clearly shows where, how, and what kind of material and energy carriers will be transferred from one supply chain layer to another. In order to test the efficiency of the model, a small regional renewable network problem was solved using both methods. Their performances were tested and the results confirmed the applicability on a regional scale. The proposed model-size reduction techniques were also tested. A large-scale regional case study was created to demonstrate these techniques. The results are very positive and some suggestions for future work are given in the conclusion.
Keywords:Biomass and bioenergy network synthesis, Model-size reduction techniques, Mathematical Programming, MILP, P-Graph
Place of publishing:Maribor
Publisher:[H. L. Lam]
Year of publishing:2010
PID:20.500.12556/DKUM-17206 New window
UDC:66.011:519.68(043.3)
COBISS.SI-ID:254123008 New window
NUK URN:URN:SI:UM:DK:HLEIDZBC
Publication date in DKUM:06.01.2011
Views:3905
Downloads:151
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FKKT
:
Copy citation
  
Average score:(0 votes)
Your score:Voting is allowed only for logged in users.
Share:Bookmark and Share



Hover the mouse pointer over a document title to show the abstract or click on the title to get all document metadata.

Secondary language

Language:Slovenian
Title:Sinteza regionalnih omrežij za proizvodnjo biomase in biogoriv
Abstract:V doktorski disertaciji predstavljamo dva različna pristopa k sintezi regionalnih omrežij za proizvodnjo in dobavo biomase in biogoriv: matematično programiranje in pristop, ki temelji na teoriji grafov. Uporabljen kriterij optimiranja pri uporabi obeh pristopov je maksimiranje dobička. Prvi, superstrukturni pristop temelji na splošnem optimizacijskem modelu omrežja za proizvodnjo in dobavo biomase in biogoriv. Pri tem superstrukturo sestavljajo štiri ravni dobavne verige: nivo proizvodnje obnovljivih surovin, nivo zbiranja s pred-obdelavo, nivo proizvodnje in nivo povpraševanja. S to raziskavo smo uspešno razvili mešano celoštevilski linearni programirni (MILP) model. Vendar pa predstavlja reševanje tega modela zaradi obsežnosti regionalnih omrežij z velikim številom povezav precejšen izziv. Veliko število odvečnih spremenljivk zmanjšuje učinkovitost reševanja (čas reševanja in razlago rezultatov). Obsežnih regionalnih omrežij tako pogosto ni mogoče rešiti v realnem času, četudi pri tem uporabljamo profesionalna matematično programirna računalniška orodja. Zato predlagamo nekatere tehnike za zmanjševanje velikosti mrežnih modelov. Predlagane tehnike so namenjene predvsem i) zmanjševanju števila povezav v omrežju z definiranjem največje dovoljene razdalje med dobavnimi conami in zbirnimi centri, ii) odpravi nepotrebnih ničelnih spremenljivk in pogojev in iii) zmanjšanju razvejanosti omrežja in s tem zmanjšanju sinteznega problema z združitvijo zbirnih centrov v manjše število centrov. Sintezo omrežja smo izvedli tudi z uporabo orodja P-graf ('procesni graf'). P-graf je usmerjeni dvopartitni graf z dvema vrstama oglišč – ena so za procesne enote in druga za objekte, ki predstavljajo snovne ali energijske tokove oz. količine. V tem postopku se za omrežje proizvodnje in porabe biomase najprej generira maksimalna dopustna superstruktura, nakar se z metodo vejanja in omejevanja (Branch-and-Bound) izbere optimalna struktura. Pri tej metodi grafov je jasno razvidno, kako in kateri snovni in energijski nosilci se prenašajo iz enega na drugi nivo dobavne verige. Z namenom preizkušanja učinkovitosti modela smo najprej za regionalno omrežje rešili računsko manj zahteven problem in pri tem uporabili obe metodi ter preizkusili njuni zmogljivosti. Dobljeni rezultati potrjujejo uporabnost obeh metod za reševanje problemov na regionalni ravni. Preizkusili smo tudi učinkovitost predlaganih tehnik za zmanjšanje obsežnosti modela in za ta namen razvili obsežnejši primer. Dobljeni rezultati so zelo obetavni. V zaključkih dodajamo tudi nekaj predlogov za nadaljnje delo.
Keywords:Sinteza omrežij za proizvodnjo in dostavo biomase in biogoriv, Tehnike zmanjševanja velikosti modelov, Matematično programiranje, MILP, P-graf


Comments

Leave comment

You must log in to leave a comment.

Comments (0)
0 - 0 / 0
 
There are no comments!

Back
Logos of partners University of Maribor University of Ljubljana University of Primorska University of Nova Gorica