Search Results

You are looking at 1 - 3 of 3 items for

  • Author: Natalia Pietrzak x
Clear All Modify Search
Open access

Natalia Kamińska-Pietrzak, Natalia Howaniec and Adam Smoliński

Abstract

Increasing energy demand, limited resources of fossil fuels and environmental aspects are the main rationales of the research efforts aiming at wider utilization of renewable resources and waste in energy generation systems. Gasification technologies are based on thermochemical processing of solid, liquid and gaseous fuels to gas of the composition dependent on kind of gasification agent and operating parameters used. The range of applications of the product gas includes basically chemical and petrochemical industries. Its utilization in power generation systems is also of industrial interest since the environmental impact of gasification technologies is lower and the process efficiency is higher than of coal-fired power plants and it enables to utilize wide range of fuels, including fossil fuels, biomass, industrial waste and various fuel blends. One of the most important operational issues related with thermochemical processing of biomass and waste is the formation of tars, which reduces the energy efficiency of the process and causes technical problems in a system operation. The amount and quality of tars depends on the chemical composition of a fuel, a gasification agent used and its ratio to fuel flow, process temperature and pressure as well as the construction of a gasifier. In the paper review of the research on the influence of operating parameters and kind of feedstock on tar formation and composition in the process of gasification and co-gasification is presented.

Open access

Bogumił Wrana and Natalia Pietrzak

Abstract

In the paper, the slope stability problem of the Kościuszko Mound in Cracow, Poland is considered. The slope stability analysis was performed using Plaxis FEM program. The outer surface of the mound has complex geometry. The slope of the cone is not uniform in all directions, on the surface of the cone are pedestrian paths. Due to its complicated geometry it was impossible to do computing by Plaxis input pre-procesor. The initial element mesh was generated using Autodesk Autocad 3D and next it was updated by Plaxis program. The soil parameters were adopted in accordance with the detailed geological soil testing performed in 2012. Calculating model includes geogrids. The upper part was covered by MacMat geogrid, while the lower part of the Mound was reinforced using Terramesh Matt geogrid. The slope analysis was performed by successives reduction of φ /c parameters. The total multiplayer ΣMsf is used to define the value of the soil strength parameters. The article presents the results of slope stability before and after the rainfall during 33 days of precipitation in flood of 2010.

Open access

Bogumił Wrana and Natalia Pietrzak

Abstract

The paper deals with the comparison of Biot’s model for saturated, porous soils with other simplified models used in dynamic analysis. The purpose of this paper is to determine some limits of validity of the various models. In order to do this a full set of governing, dynamic equations of Biot model and a series of simplifying models such as u-p simplification and quasi-static consolidation models are considered. These formulations are applied to a simple soil layer under periodic surface loading. A displacement of skeleton and a displacement of fluid are shown and compared with each model for various formulations.