Marián Lázár

HIGH-TEMPERATURE GASIFICATION OF RDF WASTE AND MELTING OF FLY ASH OBTAINED FROM THE INCINERATION OF MUNICIPAL WASTE

Objective of this paper is to describe innovative solutions of thermal processing of selected components of municipal waste (so-called RDF waste) using low-ionized depended plasma arc generated by a progressive and promising technology, which is plasma reactor. Its application can transform hazardous waste into inert waste while significantly reducing the volume of waste. Results given in this paper indicate experimentally achieved outputs with thermal disposal of RDF waste and ash from municipal waste.

Determination of Boundary Conditions and Optimalisation of the Graphite Electrode Cooling Circuit

The present paper describes the determination of boundary conditions of the 10 kVA plasma reactor graphite electrode cooling. The water cooler installed on the lid of the reactor, connected in open circuit, sustains the permissible service temperatures in the analysed area of the reactor. With the monitoring of the coolant flow and temperatures at the inlet and outlet of the cooler, the heat flux necessary for the design of a closed circulation cooling circuit was determined. Software support of HTC-FC (heat transfer coefficient – natural convection) and simulation software ANSYS CFX were used to solve the design and functionality of the proposed solution. This software is designed for the numerical calculation of differential equations describing fluid flow and heat conduction with the use of the finite volume method. With the application of time-dependent boundary conditions in the simulation tool ANSYS CFX, we acquired information about the temperature distribution of the cooling medium during the operation of the described technology and also about the change in the variation of heat flux between the environment and the proposed container.

Mechanical properties of slag treated by a thermal plasma system

The article details the results of wastes treatment by plasma reactor technology operated in a dependent connection. High-temperature treatment of asbestos-cement and fly ash from fluidised bed boilers ensures the transformation of asbestos fibers into a glass matrix of a new product in the form of glassy slag. This final product is of inert character and it offers, except for the solutions of environmental issues related to waste landfilling the possibility of material recovery of the final melting product. Moreover, there are described selected mechanical properties of glassy slag from plasma melting of the two mentioned waste types in one common process. It is important to know these properties before proposing glassy slag recovery possibilities – as it is not very frequently used as a secondary raw material yet.

APPLICATION OF ANALYTICAL SOLUTION FOR EXTENDED SURFACES ON CURVED AND SQUARED RIBS

Abstract The presented article discusses how to increase heat transfer through ribbed surfaces and it is oriented to the mathematical representation of temperature fields and the total thermal flow. The complexity of solving for some types of ribs with variable cross-section requires the application of numerical methods, which are applied consequently to the planar rib as well. In this case there was chosen the finite- difference method (FDM). During solution of the cylindrical ribs the FDM method is preferably used directly with regard to the complexity of solving for infinite sums and improper integrals in Bessel functions. In conclusion is assessed the application suitability of the calculation procedure applied to curved ribs. This procedure is usually used to planar ribs. At the same time it is pointed out the possibility of using this method for calculation of the total thermal flow through cylindrical ribs, which have got the squared form.

Experiment of Gasification of the Synthetically Mixed Sample of Waste in Nitrogen Atmosphere

Abstract The article presents results of gasification of the synthetically mixed sample of waste in a 30 kVA transferred DC plasma reactor with a hollow graphite electrode. The subject of the research is a sample of waste consisting of components normally found in a municipal waste. The experimental test of waste gasification with a high level of organic fraction was implemented due to the verification of previously mentioned technology application also in the area of waste disposal at the current construction design of the reactor. Gasification took place in the inert atmosphere at the average temperature of 1578 °C. The goal of the experiment was the verification of possible synthesis gas production applicable in the energetic applications and focus of the possible usage of the energetic potential of, up to now not often used, secondary energy sources such as wastes.

High-temperature processing and recovery of autocatalysts

V tem clanku avtorji predstavljajo rezultate eksperimentalnih raziskav termicnega postopka pridobivanja kovin platinske skupine (PGM, angl.: Platinum Group Metals) s taljenjem izrabljenih avtomobilskih katalizatorjev v 80 kVA plazemskem reaktorju z uporabo primernih talil in redukcijskega sredstva. Kot zbiralnik plemenitih kovin je bila med taljenjem uporabljena siva litina. Produkti taljenja so zlitina, inertna steklasta žlindra, sintezni plin in pepel. V zlitini je bilo pri taljenju katalizatorja na osnovi kordierita koncentriranih 99,27 % PGM, pri katalizatorjih s Cr/Ni trakom pa 99,00%. Pri taljenju kordieritnih katalizatorjev se je v žlindri izgubilo 0,34 % PGM, pri Cr/Ni katalizatorjih pa 0,26 %. Kemijska analiza pepela je potrdila, da poleg mehansko pridobljenih oksidov CaO, SiO2, MgO, Al2O3, le-ta vsebuje tudi kondenzirane pare Fe in PGM. V pepelu se je pri taljenju katalizatorja na osnovi kordierita nahajalo 0,40 % plemenitih kovin, pri katalizatorju s Cr/Ni trakom pa 0,74 %. Sintezni plin iz procesa taljenja je imel zelo nizko kurilno (kaloricno) vrednost (0,16 MJ m–3 oz. 0,24 MJ m–3).

Pyrometallurgical treatment of silver-containing catalysts

The following article describes the thermal process for the recovery of used silver from Ag catalysts using an 80-kVA plasma reactor, along with an appropriate flux and reducing agent. An Ag catalyst was melted in three separate experiments with different weights. The overall recovery of silver from the melted Ag catalysts was high (93.8–96.4) %. The byproducts of the melting of the Ag catalysts were the inert vitrified slag, synthesis gas and fly ash. The chemical analysis of fly ash confirmed that, in addition to mechanically stripped oxides that were present in the batch (CaO, SiO2, MgO, and Al2O3), fly ash also contained a high amount of condensed silver. Indeed, silver evaporated at a high temperature during the melting process. The silver condensed in fly ash was at a level of 37.08–48.37 % of the total weight of fly ash. Therefore, fly ash had to be recycled. The synthesis gas from the process had a relatively low heating value (0.6335 MJ m).

Risk Related to the Application of Hydrogen Propulsion Technology in Cars

The introduction of hydrogen technologies in the automotive and energy industry requires research in all areas of its possible application including production of hydrogen, through its operation. All of these stages are burdened by the risk caused by interaction of hydrogen with the environment and technological subject. Security group risks represent significant risk of handling hydrogen due to the possibility of explosion. Based on the risk value, the safety level of the individual subsystems of hydrogen production and utilization process is subsequently assessed. Consequently, it is possible to assess the overall safety of the mobile system based on the final/resulting value of the risk. In case of improper handling, technical failure/incident or unexpected adverse event, there is a risk of hydrogen leak into the environment. With the wide range of explosive capacity of hydrogen-air mixture, it can represent a high risk of explosion with a relatively little energy initialization.

Measurement of Hydrogen Storage Capacity in Ca72Mg28 Alloy

This article discusses the measurement of hydrogen storage capacity in Ca72Mg28 alloy that has been produced by melt spinning. The alloy has an amorphous structure in which there is an assumption of hydrogen storage of acceptable concentration. The research is to analyse the possibility of desorption of the gas without recrystallization of the alloy. Subsequently, the problem of reversible hydrogen storage is examined at temperatures between 410–450 °C in the pressure range 0 to 3.5 MPa. This paper deals with the indirect determination of the amount of heat generated in the absorption of hydrogen by using the calorimetric method. In the conclusion there is a comparison of the storage capacity of hydrogen in the amorphous and crystalline structure of the alloy.

Recycling of the Electronic Waste Applying the Plasma Reactor Technology

Abstract The following paper discusses a high-temperature gasification process and melting of electronic components and computer equipment using plasma reactor technology. It analyses the marginal conditions of batch processing, as well as the formation of solid products which result from the procedure of waste processing. Attention is also paid to the impact of the emerging products on the environment.