Fly ash immobilization with vitrification

Raziskali smo možnost imobilizacije letečega pepela iz sežiga komunalnih odpadkov. Leteči pepel smo skupaj s slovenskim odpadnim steklom stalili in ulili v kovinske kokile, da je nastal pretežno amorfen produkt, tj. steklo, ki smo ga toplotno obdelali, da se je tvorila steklokeramika. Leteči pepel je bil sestavljen iz delcev velikosti <1 m, ki se povezujejo v aglomerate velikosti okrog 180 m. Tali se pri temperaturi okoli 1300 °C in se v tekočem stanju dobro meša z odpadnim steklom. Steklo, nastalo pri litju, se pretvori v steklokeramiko pri žarjenju v temperaturnem območju med 700 °C in 950 °C, pri čemer se tlačna trdnost poveča za dvakrat. Vrednosti izluževanja težkih kovin iz vzorčnega letečega pepela prekoračujejo predpisane mejne vrednosti za odlaganje na odlagališčih za nevarne odpadke, medtem ko so vrednosti za nastalo steklo in steklokeramiko pod predpisanimi vrednostmi. Zasteklen leteči pepel lahko odložimo kot stabiliziran in nereaktiven odpadek na odlagališčih nenevarnih odpadkov, mogoče pa bi ga bilo tudi predelati in uporabiti v koristne namene.The possibility of fly ash immobilization was investigated. Municipal solid waste fly ash mixed with waste glass cullet was melted and poured into metal moulds. Mainly amorphous glass product was formed, which was then heat treated to obtain glass- ceramics. Fly ash consisted of particles with size <1m, normally joined to larger agglomerates (r180 m). Its melting temperature was around 1300 °C and it mixed well with the glass cullet in the liquid state. Glass formed during solidification was transformed into the glass-ceramics after heat treatment in the temperature range between 700 °C in 950 °C, that doubled the compressive strength. Leaching of heavy metals from fly ash exceeded the allowed values for dumping dangerous waste in landfill, whereas the values for the produced glass and glass-ceramics were under the allowed values. The produced glass and glass-ceramics can be landfilled as a stabilised and unreactive waste in landfills for nonhazardous wastes. Their properties also offer the possibility for manufacturing useful products

Assessment of a simplified equilibrium model for waste gasification

The applicability is studied of a simplified equilibrium model for prediction of the composition and quality of producer gas from gasification of different waste. A simplified equilibrium model of stoichiometric type based on system thermodynamic equilibrium has been developed in the form of a stand-alone computer application. Standard numerical methods have been implemented for solving the mathematical problem formulation. The model`s predicted results have been compared with the published results for biomass and some waste types - municipal solid wastes and refuse derived fuels. Results are included for a bubbling fluidized bed and downdraft fixed bed allothermal gasification, also for catalytic supported gasification. Producer gas predictions by calibrated and non-calibrated versions of the simplified equilibrium model have been studied. The accuracy of these predictions has been evaluated. The results obtained by the simplified equilibrium model have confirmed that such model is a very useful tool for studying the gasification process for municipal solid wastes and refuse derived fuels process parameters for two mostly implemented gasifier types

Assessment of a simplified equilibrium model for waste gasification

The applicability is studied of a simplified equilibrium model for prediction of the composition and quality of producer gas from gasification of different waste. A simplified equilibrium model of stoichiometric type based on system thermodynamic equilibrium has been developed in the form of a stand-alone computer application. Standard numerical methods have been implemented for solving the mathematical problem formulation. The model`s predicted results have been compared with the published results for biomass and some waste types - municipal solid wastes and refuse derived fuels. Results are included for a bubbling fluidized bed and downdraft fixed bed allothermal gasification, also for catalytic supported gasification. Producer gas predictions by calibrated and non-calibrated versions of the simplified equilibrium model have been studied. The accuracy of these predictions has been evaluated. The results obtained by the simplified equilibrium model have confirmed that such model is a very useful tool for studying the gasification process for municipal solid wastes and refuse derived fuels process parameters for two mostly implemented gasifier types

THE EFFECT OF WATER EMULSIFIED IN DIESEL FUEL ON DIESEL EXHAUST EMISSION

Sažetak 10 i 15%-tnu stabiliziranu emulziju voda/gorivo (v/g) koristili smo s namjerom da se smanje štetne emisije ispušnih plinova. Stabilnu emulziju v/g s dugačkom postojanošću moguće je polučiti dodavanjem male količine odgovarajućeg emulgatora i primjenom vremenski kontroliranog postupka miješanja. Voda pomiješana s gorivom ima jak utjecaj na fizičke procese i kemijsku kinetiku stvaranja smjese, zapaljenje i izgaranje, te značajno smanjuje brzinu reakcija stvaranja zagađivača, posebno NOx i čađe. Na osnovi snimljenih krivulja osloba|anja topline i tlaka u cilindru, bilo je moguće naznačiti i razmotriti razlike tijekom izgaranja, uzrokovanih izgaranjem emulzije goriva i vode. Rezultati ispitivanja motora u širokom području opterećenja i brzina vrtnje pokazali su da se emisija NOx i čađe smanjuje od 20 do 50%, a da pri tome ne dolazi do pogoršanja specifične potrošnje goriva.Abstract The 10% and 15% water/fuel (W/F) stabilized emulsions have been used with the purpose to reduce diesel exhaust emissions. The stabilized long-term W/F emulsion may be obtained by adding a small amount of an appropriate emulsifier by applying time controlled mixing procedure. Water mixed with fuel has a strong effect on physics and chemical kinetics of the mixture formation, ignition, premixed and diffusion combustion, significantly reducing the reaction rate of pollutant formation, especially NOx and soot. From in-cylinder pressure time history and rate of heat release history it was possible to indicate and discuss the differences of combustion development when W/F emulsion is burnt. The results of engine testing in a broad field of engine loads and speeds have shown a NOx and soot emissions reduction from 20 to 50% without worsening the specific fuel consumption. The experimental results are presented and discussed here

ENVIRONMENTALLY SAFE REMEDIAL OF ACID SLUDGE BY INCINERATION

Sažetak Kiseli gudron je zauljena otpadna tvar, koja nastaje prilikom kisele rafinacije međuprodukata nafte odnosno rabljenih ulja koncentriranom sumpornom kiselinom. U Sloveniji postoji nekoliko starih deponija kiselog gudrona. Nedavno se odlučilo pristupiti projektu saniranja tih starih nerješenih ekoloških problema. Poslije ispitivanja i nekih drugih postupaka sanacije, sada se odlučilo isprobati mogućnost spaljivanja gudrona. Za naš rad je bilo odlučeno, da se naprave kemijske analize gudrona sa dvije najveće deponije na području grada Maribora, dakle s deponija na Studencima i u Pesnici. Ove dvije lokacije, kao i neke druge manje bi trebale biti idućih godina sanirane. Gudron je dospio na te deponije prije više od 20 godina. Nastao je pri preradi starih ulja postupkom rafinacije sa sumpornom kiselinom, pri čemu se izvuku nezasičeni ogljikovodici, spojevi metala i organski kloridi. Količina otpadnog materijala pri takvoj preradi iznosi od 3 do 10 % od ulaznih količina.Vidi se da postoji razlika između uzoraka, pogotovo glede koncentracije klora, cinka i olova. Kalorične vrijednosti i koncentracije sumpora su slične i one će najodlučnije utjecati na proces izgaranja te na tvorbu produkata. Najprije je bila obavljena teoretsko - tehnička studija mogućih i za okoliš sigurnih postupaka spaljivanja neobrađenog gudrona. Zbog karakterističnog kemijskog sastava i fizikalnih svojstava gudrona opredijelili smo se za spaljivanje na osnovi dvije različite tehnologije s različitim postupcima obrade dimnih plinova, koje su neophodno potrebne, radi dostizanja nižih emisijskih koncentracija polutanata u odnosu na propisane dozvoljene emisije od EU. Dobrim planiranjem svih pokusa, dobrim izborom tehnologije spaljivanja i tehnologijom prečišćavanja dimnih plinova te kvalitetnim izvođenjem pokusa uspjeli smo izvesti spaljivanje gudrona, koji je dao veoma povoljne rezultate. Pogotovo smo zadovoljni, što smo uspjeli sniziti koncentraciju SO2 ispod dozvoljinih granica. Koncentracije SO2 su bile u dimnim plinima pred čišćenjem na nivou 10g/Nm3, što pokazuje da je gotovo sav sumpor izgorio i napustio primarnu komoru s dimnim plinovima. Sniženje njegove koncentracije se obavilo u dva odnosno tri koraka. Koncentracije teških metala u šljaki pokazuju da je samo manji dio napustio primarnu komoru, što je olakšalo rad naprava za čišćenje plinova.Abstract Acid sludge or gudron is oily waste that forms in the process of acid rafination inter products of crude oil or waste oil with concentrated sulphur acid. There are several old dump sites for acid gudron in Slovenia. Recently was made a decision to start the remedial process of these old unsolved ecological problems. After the recent investigation of some other remedial processes, a decision was made to investigate the incineration of acid sludge. In order to conduct the investigation, chemical analyses of acid sludge from two biggest dump sites in area of the city of Maribor, located in the city suburbs of Studenci and Pesnica was made. These two locations and several smaller will be in remedial process in the course of next years. Gudron was transported there more then 20 years ago. It was produced while processing old oils with the process of rafination with sulphur acid. With this process the unsaturated hydrocarbons, metal parts and carbon chlorides are removed. The amount of waste material in such a process is between 3 and 10 percent of input quantity. There is a difference between the two samples, especially in concentration of chlorine, zinc and lead. Calorific value and concentration of sulphur are similar and they are the most influential in the process of combustion and formation of combustion products. In the very beginning, the theoretical-technical study of possible and environmentally safe processes of incineration of unprocessed acid sludge was conducted. Due to specific chemical composition and physical properties of acid sludge the decision was made to perform test incineration of acid sludge by using two different technologies with variety of flue gas treatment systems, which are indispensably necessary for reaching the flue gas emission levels set by the European Community Directive. Appropriate planning of all test trials with correct selection of incineration technology and technology of flue gas treatment together with precise execution of tests shows, that it is possible to incinerate acid sludge with very good results. The concentration of SO2 was the hardest to get under the legislative value. The SO2 concentration in raw gases was around 10 g/Nm3, showing that all sulphur has been burnt and has left the primary combustion chamber with flue gases. The reduction of its concentration was undertaken in two or in three steps. The concentration of heavy metals in slag shows, that only smaller part of them has left the primary chamber, adding to the eased work of flue gas treatment devices

PROGRESS IN VEHICULAR IC ENGINES AND FUELS QUALITY

Sažetak Međusobna ovisnost razvoja motora s unutarnjim izgaranjem i kvalitetom goriva/maziva postojala je sve od rođenja prvog motora. Upravo je prvi motor bio izumljen i konstruiran za korištenje samo određene vrste goriva. To je zahtijevalo neprekidnu i tijesnu suradnju između inženjera, istraživača i drugih eksperata iz obje grane industrije. U članku je dat prvo kratak pregled razvoja motora s unutarnjim izgaranjem (MUIZ) u toku prošlog stoljeća i navedeni su zahtjevi za performance motora u bližoj budućnosti. Dalje su analizirana i prodiskutirana neka najvažnija fizička i kemijska svojstva goriva koja određuju kvalitetu goriva za motore: oktanski i cetanski broj, kemijski sastav, prisutnost elementarnog S, N, P i kemijski vezanog N u gorivu, prvenstveno s gledišta njihovog utjecaja na efektivne parametre, radne performance motora i emisiju polutanata.Abstract The interdependence between IC engine development and fuel/lubricant quality has existed, ever since the first engine was born. In fact the first engine was invented and designed for using explicitly only a definite type of fuel. This has required a continuous and strong cooperation between engineers, researchers and other experts of both branches of industries. In this paper a short review of IC engine development during the last century is presented first, and the requirements on IC engine performance in the near future are listed. In continuation only a few of most important physical and chemical properties determining the quality of vehicular engine fuels have been analyzed and discussed: octane and cetane number, fuel chemical composition, fuel S, N, P and N, mainly from the stand point of their influence on IC engine effective parameters, operating engine performance and pollutant emissions

VEHICLE FUEL COMBUSTION CO2 EMISSION

Sažetak Prikazan je utjecaj motornih goriva i pogonskih motora osobnih vozila na emisiju ugljičnog dioksida CO2. Definirani su maseni i volumetrijski indeks i faktor emisije fosilnih goriva i izračunate njihove vrijednosti za najvažnija fosilna motorna goriva. Predstavljen je trend smanjenja specifične emisije CO2 [g CO2/km] osobnih vozila za razdoblje 1995.–2020. koji su predložili proizvođači vozila. Analizirani su procesi pretvaranja primarne energije goriva u pogonskim motorima vozila i njihov utjecaj na stupanj iskorištenja motora i emisiju CO2 vozila. Na osnovi rezultata statističke obrade podataka o deklariranom – tvorničkom i cestovnom specifičnom utrošku goriva [l/100 km] triju grupa vozila s benzinskim motorom, grupiranih po stapajnom obujmu motora, zbirno je ocijenjen utjecaj emisije CO2 na okoliš.Abstract The aim of this paper is to evaluate the contribution of vehicular fuel and IC engines on CO2 emission. Definitions of mass and volumetric emission indexes and emission factor are given, and the calculated values for mostly used CnHm fossil fuels are presented. The scenario of European carmaker voluntary agreement to reduce the specific CO2 emission [g CO2/km] over the years 1995 through 2020 is discussed. The role of fuel energy conversion process in vehicle engines is analyzed and its effect on fuel consumption [l/100 km] and CO2 emission is summarized. Average values of standardized (ECE) and road (test) fuel consumption performances of vehicles with SI engines have been calculated and associated CO2 emissions are presented. The requisite approaches to reduce vehicle CO2 emission are discussed

Numerical optimisation of a waste-to-energy plant\u27s operating parameters using CFD

The combustion process for using municipal solid waste as a fuel within a waste to energy plant calls for a detailed understanding of the following phenomena. Firstly, this process depends on many input parameters such as proximate and ultimate analyses, the season of the year, primary and secondary inlet air velocities and, secondly, on output parameters such as the temperatures or mass-flow rates of the combustible products. The variability and mutual dependence of these parameters can be difficult to manage in practice. Another problem is how these parameters can be tuned to achieving optimal combustible conditions with minimal pollutant emissions, during the plant-design phase. in order to meet these goals, a waste-to-energy plant with bed combustion was investigated by using computational fluid-dynamics approach. The adequate variable input boundary conditions based on the real measurement are used and the whole computational work is updated using real plant geometry and the appropriate turbulence, combustion, or heat transfer models. The operating parameters were optimized on output parameters through a trade-off study. The different operating conditions were varied and the combustible products were predicted and visualized. Finally, the response charts and matrix among the input and output parameters during the optimization process are presented, which monitored the dependence among these parameters