Lastnosti lesnih peletov izbranih proizvajalcev v Sloveniji

magistrsko delo

Živa Krelj (Author), Primož Oven (Mentor)

Abstract

Zaradi želje po zmanjšanju emisij CO2 v ozračje postaja izkoriščanje lesne biomase za proizvodnjo toplote in električne energije vse bolj pomembno. Les ima zaradi porozne strukture majhno gostoto. Gostoto biomase lahko povečamo s stiskanjem v pelete. Prednosti lesnih peletov so višja gostota energije, nižji stroški prevoza in skladiščenja, enostavnejše rokovanje, manjše onesnaževanje, možnost avtomatizacije in optimizacije izgorevanja. Namen naloge je bil pridobiti pregled fizikalnih lastnosti in kemične sestave lesnih peletov proizvedenih v Sloveniji pri sedmih izbranih proizvajalcih. Dobljene rezultate smo primerjali z mejnimi vrednostmi opredeljenimi v mednarodnem standardu SIST EN ISO 17225-2. Iglavci imajo večjo vsebnost lignina kot listavci, ki deluje kot vezivo in vpliva na boljšo mehansko obstojnost pri peletih. Proizvajalec E, ki je edini uporabljal surovino z večjim deležem listavcev, je imel najnižjo povprečno mehansko obstojnost peletov. Najvišjo kurilnost peletov v suhem stanju smo izmerili pri proizvajalcu C, ki je pri proizvodnji peletov uporabljal le smreko. Najnižjo kurilnost peletov pa smo izmerili pri proizvajalcu E, ki je v surovino dodajal 70% listavcev. Proizvajalec G, ki je imel največjo vsebnost skorje v peletih, je imel drugo najvišjo kurilnost peletov v suhem stanju in povečano vsebnost pepela. Najnižjo spodnjo kurilnost peletov v dostavljenem stanju smo izmerili v peletih proizvajalca D, ki so imeli največjo vsebnost vode. Največjo vsebnost dušika smo izmerili pri proizvajalcu G, ki je proizvajal pelete, ki so vsebovali skorjo. Skorja vsebuje več dušika kot čisti les. Na mehansko obstojnost vpliva delež skorje v surovini, vsebnost lignina in ekstraktivov, vsebnost vode, ter porazdelitev velikosti delcev v surovini. S pomočjo vrednosti masnih deležev velikosti delcev v surovini smo lahko le delno ocenili vpliv na mehansko obstojnost peletov.

Keywords

lesni peleti;kemični parametri;vsebnost vode;pepel;kurilnost;mehanska obstojnost;slovenski proizvajalci;

Data

Language:	Slovenian
Year of publishing:	2016
Typology:	2.09 - Master's Thesis
Organization:	UL BF - Biotechnical Faculty
Publisher:	[Ž. Krelj]
UDC:	630*83:620.97(043)=163.6
COBISS:	859767
Views:	48
Downloads:	12
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	Properties of wood pellets of selected producers in Slovenia
Secondary abstract:	The utilization of biomass for energy production is an attractive option for power producers to reduce their CO2 emissions. Because of its porous structure the wood has a low density. One solution to that problem is the densification of biomass materials into pellets. Densification of biomass materials increases the bulk density of biomass and could reduce the costs of transportation; storage, handling, and results in less pollution, lower amount of fine fraction and controlled combustion process. The aim of the thesis was to obtain an overview of the physical properties and chemical compounds in wood pellets produced by seven selected producers in Slovenia. The results obtained were compared with the values specified in the national standard for wood pellet SIST EN ISO 17225-2. Softwoods have a higher content of lignin than hardwoods and therefore pellets made from softwoods have a better mechanical durability than pellets made from hardwoods. Producer E was the only one, which used raw material with a greater proportion of hardwoods than softwoods. This had the lowest mechanical durability of the pellets. Softwoods have a high calorific value than hardwoods. The highest gross calorific value for a dry sample of pellets was measured at producer C. Producer C produces pellets only from pine. The lowest gross calorific value for a dry sample of pellets was measured at the producer E. They used for pellet production 70 % of hardwoods. Producer G, which had the highest content of bark in pellets, had the second highest calorific value for dry samples of pellets. The net calorific value for a sample of pellets as received is most affected by moisture content. Therefore, the lowest average net calorific value for samples of pellets as received was measured in pellets from producer D, which had the highest average moisture content in pellets. The highest nitrogen content was measured in pellets from manufacturer G, which produced pellets with bark. Bark has a higher content of nitrogen compared to wood. Bark content, content of lignin and extractives, moisture and particle size distribution are an important influencer of pellet durability. With the particle size distribution in the raw material we could only partially evaluate the influence on mechanical durability of pellets
Secondary keywords:	wood pellets;chemical parameters;moisture content;ash content;calorific value;mechanical durability;Slovenian producers;
Type (COBISS):	Master's thesis
Thesis comment:	Univ. Ljubljana, Biotehniška fak.
Pages:	XVII f., 142, [10] str.
ID:	24398890