Abstract. An experimental study was performed to determine the drying characteristics of an oversized fraction of RDF alternative fuel using a laboratory scale hot air dryer at a variety air temperatures and a constant air velocity. For this research the industrial RDF was derived from a Regional Municipal Waste Treatment Facility near the city of Kraków, Poland. The samples of RDF were prepared in two forms: ovesized (unmodified condition) and shreded in a two-drum crusher. In addition, the RDF was sorted into three groups of samples: paper, plastic, textiles. Each form of RDF and each group of samples were dried in hot air dryer at temperatures of 50, 70 i 90 °C and a constant air velocity of 1,5 [m·s]. The loss of the the samples mass were measured in a continues manner until the equilibrum moisture content was reached. The effective moisture diffusivity [m 2 ·s -1 ] and activation energies [kJ·mol -1 ] was amounted. The analysis of the course of moisture content change concludes that that the drying of the RDF alternative fuel occured mainly in the II period of the process during which the transport of water content was carried out by diffusion. And, to a lesser extent, with the surface heat transfer in II period. Based on the calculated data there was a model determined which presented the best possible matching of the course of moisture content change.

Torrefaction is one of the methods of thermal treatment of biomass, which allows obtaining a product of better quality in the form of biochar. The aim of the paper was to analyze the possibility of using goldenrod (Solidago canadensis, Solidago gigantea) for the production of biochar. The torrefaction process involved the vegetative and generative parts as well as the whole plant at temperatures of 250 °C and 275 °C, for 3 h. Next, the physicochemical properties of the raw material and biochar were determined, namely moisture content, ash content, volatile matter content, calorific value, and heat of combustion. The bulk density of raw biomass and biochar was also determined. It was found that after biomass torrefaction, the ash content, calorific value, and heat of combustion increased, while volatile matter content decreased. It has been observed that in both the case of raw biomass and biochar, the plant species and the sampled parts have a significant impact on the ash content, volatile matter content, calorific value, and heat of combustion.

The impact of biomass addition to the RDF oversize fraction on quality parameters obtained from this blend of briquettes produced under semi-industrial conditions was analysed. For the purposes related to the experiment four RDF mixtures with fragmented biomass of common willow Salix viminalis L., differing only with percentage participation of base elements, were prepared. The briquetting process was performed with the use of a semi-industrial briquetting machine at the determined compaction pressure of 47 MPa and a diameter of a sleeve (and a briquette at the same time) of 50 mm. Selected quality parameters of produced briquettes were determined, i.e. density, mechanical strength DU and compression strength. The best parameters were obtained for briquettes produced from the blend with a 50% share of willow (ρ=843.9 kg·m -3 , DU=86.1%, R c =0.46 MPa). The lowest parameters were in case of briquettes without biomass addition. Statistical analysis of research results indicates that biomass additions to RDF significantly affect the improvement of quality parameters of the obtained briquettes.

The paper presents a relational model of a technological line used for bottling fruit juices, which constitutes a stage of works aimed at building mathematical and simulation models. The model has been developed using the system analysis method. A relational model is defined as a pair of relations between a set of model elements and a relational structure. Creation of this model is a work stage approaching the construction of mathematical and simulation models. Relation model was developed with the system analysis method developed by Jaros and Pabis. The creation of the empirical system model is carried out in several stages: analysis of the system and its structure, mapping selected system objects into model elements, creating a relational model, analysis of states that are important for the purpose of modelling for each object in the system, formulation of mathematical models, assessing the compliance of the block diagram of the model operation with the model's relational structure, development of an operational model, programming the operating model. In this publication, we present the first three stages of model creation. The analysis of the complex empirical system of the modelled fruit juice bottling line made it possible to create a system diagram and isolate 24 objects of the actual system. The representation of a set of system objects as a set of model elements made it possible to obtain a relational model consisting of 6 elements and a set of 16 relations, which form the structure of the model. The elements of the relational model include a blower, monobloc, packaging unit, labelling device, transport equipment, check and repair service. In addition, the model includes forklift trucks as an element of the environment. The formulated relational model provides the basis for the development of an operational model and its logical acceptance.

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