Effects of the type of biomass and ashing temperature on the properties of solid fuel ashes

Ashes were prepared by annealing selected types of solid fuels (biomass: corn cobs, sunflower husks, olive pomace, hay pellets and rice husks; coal: lignite and bituminous; and alternative fuel: paper sludge) at different temperatures (550 degrees C, 815 degrees C and 975 degrees C). Based on X-ray fluorescence spectra, the slagging/fouling indexes were used to study the effects of the type of ash and the ashing temperature on the ash fouling and slagging properties. Slagging indexes were compared with the ash fusion temperatures. Ash fusion temperatures were measured by a LECO AF-700. The lowest deformation temperature (below 1000 degrees C) was seen for the ashes prepared from hay pellets and corn cobs. On the other hand, the deformation temperature exceeded 1500 degrees C for ashes prepared from paper sludge, sunflower husks and rice husks. By calculating the different slagging/fouling indexes, all the ashes exhibited slagging/fouling problems of varying degrees.Web of Science212514

Measurement of emissions of ultrafine particles from small combustion equipments with regard to new findings from research on the safety of nanoparticles

Import 04/11/2015Svět se v dnešní době potýká s globálním problémem znečištění ovzduší a s jeho nepříznivými dopady na zdraví obyvatelstva. Tuhé znečišťující látky (TZL) v ovzduší ovlivňují člověka mnohem více než jiné škodliviny v tomtéž prostředí (například SOx, NOx). V devadesátých letech minulého století bylo dosaženo významného zlepšení kvality ovzduší v ČR. Avšak v mnohých, zejména dopravou a průmyslem silně zatížených oblastech (například některé oblasti Moravskoslezského kraje) jsou stále překračovány imisní limity pro ochranu zdraví obyvatelstva. Zdroje TZL v ovzduší jsou zejména spalovací procesy. Z těchto zdrojů jsou významnými zástupci v produkci TZL malá spalovací zařízení (MSZ). Problémem MSZ je nízká výška komínů, která způsobuje hromadění TZL v dýchací zóně obyvatelstva i skutečnost, že tato zařízení nemají prakticky žádné čištění spalin (filtry) a neplatí pro ně obdobné kontrolní a regulační mechanismy jako pro velké zdroje znečišťování ovzduší, které jsou z velké části kontrolovány kontinuálně. Ze zdravotního hlediska je zde blízká vazba kvantitativního vztahu mezi expozicí vysoké koncentrace částic PM10 a PM2,5 a vzrůstajícího počtu onemocnění či úmrtí [3]. Částice menších velikostí mohou být rizikovější než částice větších rozměrů, protože pronikají hlouběji do dýchacího systému a bylo zjištěno [2],[57], že ultrajemné částice (částice menší než 100 nm) jsou schopny aktivně pronikat přímo do krevního řečiště. S rozvojem toxikologických znalostí o ultrajemných částicích (nanočásticích) se ubírá pozornost na jejich možná rizika pro lidské zdraví. Pochopení vztahu mezi množstvím emisí, jejich fyzikálně-chemickými vlastnostmi a biologickou aktivitou jsou velmi důležité při navrhování a zavádění efektivních opatření pro snížení rizik exponovaného obyvatelstva. Cíl disertační práce se zaměřil na stanovení měrných emisí (ME) TZL, PM10 PM2,5, PM1, PM0,1 (ultrajemných částic) ze spalování tuhých paliv v malých spalovacích zařízeních při běžném provozu v domácnostech -při jmenovitém a sníženém výkonu a při spalování různých druhů paliv. Byla vyvinuta vhodná a v praxi využitelná metoda odběru jednotlivých velikostních frakcí částic pro stanovení, jak hmotnostní, tak početní koncentrace částic (PM0,1 - PM10). Z dvaceti pěti provedených spalovacích zkoušek vychází, že procentuálně v PM10 jsou ultrajemné částice (UFP) zastoupeny v průměru 8 %hm. a frakce PM1 je zastoupena v průměru 90 %hm. Při porovnání početní a hmotnostní koncentrace částic vychází, že procentuálně jsou ultrajemné částice v PM1 zastoupeny v průměru 65 %poč. a 10 %hm. Absolutní hodnoty ME tuhých znečišťujících látek a ME jednotlivých velikostních frakcí jsou mnohem vyšší u kotlů staršího typu spalování (prohořívací a odhořívací kotle). U novějších typů spalovacích zařízení (automatické a zplyňovací kotle) je snížení ME TZL velmi výrazné. Avšak hodnoty ME PM0,1 zůstaly v průměru stejné. S ohledem na získané výsledky je potřeba se i nadále zaměřit na charakterizaci malých spalovacích zařízení se zaměřením na jemné a ultrajemné částice. Zjišťovat fyzikálně-chemické vlastnosti těchto částic pro rozšíření informací o jejich míře toxicity a využít toxikologické testy, neboť některé látky mohou být silně biologicky aktivní i při nízkých koncentracích přítomných škodlivin.The world today is facing a global problem of air pollution and its adverse impacts on human health. Total suspended particles (TSP) in the atmosphere influence man much more than other harmful substances in the same environment. In the nineties, a significant improvement in air quality in the Czech Republic was achieved. However, many, particularly transport and industry heavily loaded areas (e.g. some Moravian-Silesian regions), still exceed the value limits for the protection of public health. Sources of TSP in ambient air are mainly from combustion processes. These sources are important agents in the production of TSP of small combustion equipment (SCE). The SCE problem is the low height of the chimney, which causes an accumulation of solid pollutants in the breathing zone of the population, and the fact that these devices have virtually no exhaust gas purification (filters), and do not operate similar supervisory and regulatory frameworks as large combustion sources of air pollution, whose parts are controlled continuously. From a health perspective, there is a close link in the quantitative relationship between exposure to high concentrations of PM10 and PM2.5 and the growing number of illnesses and deaths [3]. Particles of smaller size may be more risky than larger particle sizes, as they penetrate deeper into the respiratory system. It was found [2],[57] that the ultrafine particles (particles smaller than 100 nm) are able to actively penetrate directly into the bloodstream. With the development of toxicological knowledge about ultrafine particles (nanoparticles), attention to their potential risks to human health is falling.Understanding the relationship between the amounts of emissions, their physicochemical properties, and biological activity are very important when designing and implementing effective measures to reduce the risk of exposure to the population. The objective of the dissertation thesis is focused on determining the specific emissions (SE) TSP, PM10, PM2.5, PM1, PM0.1, from the combustion of solid fuels in small combustion equipment in normal operation in households - at nominal and reduced power, and during the combustion of different types of fuels. A suitable and practical usable method of taking individual particle size fractions to determine both the mass and number concentration of particles (PM0.1 - PM10) was developed. From the twenty five combustion tests performed, based on the percentage of PM10, ultrafine particles (UFP) represented an average of 8%wt., and PM1 fraction is represented by an average of 90%wt. When comparing numerical and mass concentrations of particles based on the percentage of the ultrafine particles in the PM1, they represented on average 65%num. amount and 10%wt. Absolute values of SE TSP and SE individual particle sizes are much higher among older types of combustion equipment. The newer types of combustion devices (automatic and gasification burners) reduce the SE of SCE very significantly. However, the value of the SE PM0.1 average remained the same. With regard to the results obtained, it is necessary to continue to concentrate on the characterization of SCE with a focus on fine and ultrafine particles. Identifying the physico-chemical properties of these particles to spread information about their level of toxicity and toxicological tests should be used, as some substances can be biologically highly active even when low concentrations of pollutants are present.040 - Katedra bezpečnosti práce a procesůvyhově

Trends and opportunities of tertiary education in safety engineering moving towards Safety 4.0

Industry and related work and workplaces are constantly changing as a result of the implementation of new technologies, substances and work processes, changes in the composition of the workforce and the labor market, and new forms of employment and work organization. The implementation of new technologies represents certain ambivalence. Next to the positive impact on workers' health, new risks and challenges can arise in the area of process and occupational safety and health of people at work. On these bases, it follows the need for predicting and handling the new risks, in order to ensure safe and healthy workplaces in the future. The aim of most forecasting studies is not only to identify new emerging risks, but also to foresee changes that could affect occupational safety and health. However, a number of questions still require proper investigation, i.e., "What impact do new emerging risks have on tertiary education in the area of Safety engineering? Has tertiary education already reacted to progress in science and research and does it have these innovations in its syllabus? How are tertiary graduates prepared for the real world of new technologies?" This paper represents a first attempt in the literature to provide answers to the raised questions, by a survey approach involving academics, Health Safety and Environment (HSE) industrial experts and university students in the Czech Republic. Even if statistical evaluation is limited to a single Country and to a small sample size, the obtained results allow suggesting practical recommendations that can contribute to ensuring new challenges in the area of education by addressing relevant culture issues needed to support new workplace realities according to the newly defined Safety 4.0.Web of Science132art. no. 52

Effects of the type of biomass and ashing temperature on the properties of solid fuel ashes

Ashes were prepared by annealing selected types of solid fuels (biomass: corn cobs, sunflower husks, olive pomace, hay pellets and rice husks; coal: lignite and bituminous; and alternative fuel: paper sludge) at different temperatures (550°C, 815°C and 975°C). Based on X-ray fluorescence spectra, the slagging/fouling indexes were used to study the effects of the type of ash and the ashing temperature on the ash fouling and slagging properties. Slagging indexes were compared with the ash fusion temperatures. Ash fusion temperatures were measured by a LECO AF-700. The lowest deformation temperature (below 1000°C) was seen for the ashes prepared from hay pellets and corn cobs. On the other hand, the deformation temperature exceeded 1500°C for ashes prepared from paper sludge, sunflower husks and rice husks. By calculating the different slagging/fouling indexes, all the ashes exhibited slagging/fouling problems of varying degrees

Impact of boiler type, heat output, and combusted fuel on emission factors for gaseous and particulate pollutants

Five different boiler types (automatic boiler, overfire boiler, boiler with down-draft combustion, and two types of gasification boilers) representing residential-scale combustion technology were tested. Boilers were fueled with various fuels (lignite, wet and dry wood, wood pellets, and mixed fuel), and the combustion emissions were measured both at nominal and reduced output. The investigated emissions comprised CO, organic gaseous compounds (OGC), and particulate matter (PM). A cyclone and a low-pressure impactor were used to determine PM emissions. It was found that the emission factors for CO, OGC, and PM depend more on boiler type and mode of operation (reduced or nominal output) than on fuel type. Data from the Dekati low-pressure impactor (DLPI) show that, in most cases, PM1 represents approximately 80% of the total PM mass. PM0.1 represents 15-30% (modern boilers) or 5-10% (old-type boilers) of the total PM mass. Comparison of the results shows that the emission factors for PM obtained by the cyclone were higher than the emission factors obtained using the DLPI.Web of Science30108456844

Influence of the type and output of domestic hot-water boilers and wood moisture on the production of fine and ultrafine particulate matter

The Ministry of the Environment of the Czech Republic within the Operational Programme Environment of the European Union (EU) has supported a 'grant to replace old boilers' from 2015 to 2020. The aim was to replace outdated, non-ecological, solid-fuel boilers with modern low-emission boilers (for the combustion of biomass, coal, or a combination), heat pumps, gas boilers, or solar systems. All heat sources must comply with the Ecodesign Directive of the EU. According to the Air Protection Act in the Czech Republic, commencing in 2022, outdated boilers of the 1st and 2nd emission classes will no longer be operable in households. The grant also aimed to reduce particulate matter (PM), organic gaseous compounds, and CO and NOx emissions. Our goal was to compare the PM emissions of four boilers: an outdated overfire boiler (B1), an outdated boiler with down-draft combustion (B2), a new gasification boiler (B3), and a new automatic boiler (B4). A Dekati low-pressure cascade impactor was used to determine the mass concentration of individual dust fractions; a scanning mobility particle sizer SMPS 3936 was utilized to determine the particle size distributions of the dust particles. Dry and wet spruce wood and wood pellets were combusted. Regarding the mass concentration of the PM and specific emissions (SE) of individual size fractions, they were much higher in boilers of older types (B1 and B2), while the reduction in SE of PM was very significant in boilers of newer types (B3 and B4). However, the SE of ultrafine particles (PM0.1) from the newer boilers remained in a range similar to that of B1 at a reduced output (P-min) and B2.Web of Science229art. no. 11743

Change in the wood moisture dependency on time and drying conditions for heating by wood combustion

The aim of this study was to determine the drying time of firewood under the climatic conditions of the Czech Republic to decrease the moisture content to an acceptable level for combustion (under 20%). The effects of log size, outdoor/indoor drying and wood species were evaluated.Web of Science63227226

PAH emissions from old and new types of domestic hot water boilers

Five different domestic heating boilers (automatic, over-fire, with down-draft combustion and gasification) and three types of fuel (lignite, wood and mixed fuel) were examined in 25 combustion tests and correlated with the emissions of particulate matter (PM), carbon monoxide (CO), total organic carbon (TOC) and 12 polycyclic aromatic hydrocarbons (PAHs with MW = 178-278 g/mol) focusing on particle phase. However, the distribution of 12 PAHs in gas phase was considered as well due to the presence mainly of lighter PAHs in gas phase. The PAHs, as well as the CO and TOC, are the indicators of incomplete combustion, and in this study PAH emission increased significantly with increasing emissions of CO and TOC. The PAHs were mainly detected on PM2.5, their contents were increasing linearly with increasing PM2.5 emissions. The highest emission factors of PAHs were measured for boilers of old construction, such as over-fire boiler (5.8-929 mg/kg) and boiler with down-draft combustion (3.1-54.1 mg/kg). Modern types of boilers produced much lower emissions of PAHs, in particular, automatic boiler (0.3-3.3 mg/kg) and gasification boilers (0.2-6.7 mg/kg). In general, the inefficient combustion at reduced output of boilers generated 1.4-17.7 times more emissions of PAHs than the combustion at nominal output of boilers. It is recommended to operate boilers at nominal output with sufficient air supply and to use the proper fuel to minimise PAHs emissions from domestic heating appliances.Web of Science225393