Mária Čarnogurská

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.

THE EFFECT OF TEMPERATURE PYROLYSIS PROCESS OF USED TIRES ON THE QUALITY OF OUTPUT PRODUCTS

Abstract Pyrolysis together with gasification and combustion create a group of so called thermic processes. Unlike the combustion it is based on thermic decomposition of organic materials without any access of oxidative media. Within the pyrolytic process, three main fractions are created: solid residue, pyrolytic gas and organic liquid product - pyrolytic oil. The presented article examines the effects of pyrolysis operational conditions (above all, temperature) on gas products, solid residues and liquid fractions.

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.

SIMULATION OF HEAT TRANSPORT AT THE COOLING OF THE SUGAR SOLUTION IN A RECUPERATION EXCHANGER

The paper describes a mathematical model of the cooling process of a highly concentrated sugar solution in an exchanger with a specifically shaped heat exchanging surface of the cooling panels. An analysis of the individual parts of the stum cooling line is made, dealing with the cooling performance of the cooling panels located in the stum tanks, whose volume is 3230 litres or 1430 litres. One of the monitored parameters is the cooling performance of the JN30 aggregate. The article also deals with an appropriateness of the aggregate for cooling the stum of the total volume 78.21 m 3 , from the real operation temperature to 0 °C during 48 hours.

Heat output of the recuperator for preheating natural gas from a mobile container device

The paper describes the methodology for determination of the heat exchanger output for mobile container device designed to supply stationary stations with natural gas. Expansion of the gas in the device is considered in two stages. In the first stage from over-pressure of 22 MPa down to over-pressure of 0.4 MPa and then in the second stage to over-pressure of 2.2 kPa or 170 kPa. The overall temperature drop during gas throttling, which depends not only on the initial and final pressure but also on the temperature, was calculated by numerical integration of the Joule-Thomson differential coefficient. For the throttling temperature between 0 and 55 °C, the total temperature drop in the first stage varies between 53.8 and 67.4 K, and in the second stage then up to 2 K. The heat exchanger output was determined by an iterative process. Smooth supply of 600 m3 of natural gas per hour requires a heat exchanger with an output of approx. 26 kW. Gas combustion micro-turbine consumption is of the order of m3 of natu...

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 DIMENSIONAL ANALYSIS IN HEAT LOSS DETERMINING IN DISTRICT HEATING SYSTEMS

Existing procedures for determining the heat loss in heat distribution use balance relations, or rather they are based on the theory of heat and mass transfer. Dimensional analysis enables a new point of view that demonstrated the functionality of heat loss from selected physical quantities that contribute to heat loss. The solution provides one complex criterion and four simplex criteria of similarity. Transforming these criteria of similarity leads to the formulation of the functional dependence of only two criteria, on the basis of which the amount of heat loss can be determined. The resulting criterial dependency is simple, and is calculated in this paper for a pipe one meter in longth. The mathematic model for demonstrating the heat loss is of universal validity, and applies to a wide range of piping used for hot water distribution. However, for each nominal diameter of piping it is necessary to take into account the mutual dependency of the dimensionless arguments p 5 on p 1 , the form of which is always different. In the paper, this dependency is demonstrated for two nominal diameters DN65 and DN125.

Power losses and the efficiency of industrially used gearboxes

This article gives the methodology for stating power losses and the efficiency of a gearbox working in natural cooling using dimensional analysis. The methodology reflects experimental research which investigated the effect of a change in revolutions and loading the gearbox on power losses. At the same time, it describes the conditions under which the proposed method may be applied for industrial, helical bevel geared motors.

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).