Legal Limits for NOx Emissions Related to Biomass in EU Countries and Serbia

In the last few years, the citizens of Serbia have witnessed great air pollution at the beginning of the heating season and the start of operation of small heating plants and individual combustion stoves, as well as due to relatively stable atmospheric conditions. Similarly, two-thirds of EU citizens live in cities constantly exposed to pollution, which often exceeds the limits recommended by laws. The use of biomass as RES somewhat alleviates this problem; however, biomass, like any other fuel, emits certain pollutants. The emission of nitrogen oxides (NOx) is one of the most important challenges in the field. The paper gives a review and analysis of the Serbian norms related to NOx emissions as well as the legal norms and the experiences of some of the selected European countries. As air pollution is among the ten most harmful phenomena for human health, it is important to know the limits of the emission as well as how to adapt to our circumstances the best solutions from the EU policy

Selective non-catalytic denitrification of biomass combustion flue gases (synthetic mixture)

Despite many benefits of agricultural biomass utilization as an energy source, there are certain disadvantages such as the possible high emission of NOx. The NOx emission represents one of the key challenges for agricultural biomass use as a fuel. The experimental denitrification chamber was used to evaluate the impact of initial NO content, NH3:NO molar ratio, flue gas temperature, and the temperature difference between two denitrification chamber sections on NOx reduction using ammonia aqueous solution. The optimization of experimental conditions was done in the NO concentration range from 200-800 ppm, NH3:NO molar ratios from 0.31-3 and second chamber section temperature range from 770-67°C. The denitrification process under controlled conditions is the starting point for the optimization of the secondary denitrification technique of selective non-catalytic reduction SNCR process on real-scale plants combusting biomass or any other fuels with increased NOx emission

The Potential for Reindustrialization of the Republic of Serbia with the Use of Biomass as a Renewable Fuel

U kontekstu savremene geopolitičke situacije i energetske neizvesnosti, cilj rada je da jače afirmiše upotrebu biomase kao domaćeg energenta i da ukaže na smernice za njeno pravilno i efikasno iskorišćenje. Prema zvaničnim podacima Ministarstva rudarstva i energetike Republike Srbije, biomasa predstavlja ubedljivo najveći potencijal obnovljive energije u zemlji. Preko 60% procenjenog potencijala obnovljive energije u Republici Srbiji pripada biomasi (ne računajući velika hidroenergetska postrojenja). Mogućnost energetskog iskorišćenja biomase, pri tome, ne zavisi od vremenskih prilika, doba dana ili godišnjeg doba, za razliku od drugih izvora obnovljive energije poput energije vetra i sunca. Pored ove i drugih prednosti koje biomasa kao jedino ugljenično – CO2 – neutralno obnovljivo gorivo ima, potrebno je istaći i to da su postrojenja za konverziju energije iz biomase putem sagorevanja relativno jednostavna i u celosti se mogu proizvoditi u našoj zemlji. Ukoliko bi se ova postrojenja koristila u sistemima daljinskog grejanja uz mogućnost korišćenja toplotne energije i za tehnološke procese u uzgoju i preradi poljoprivrednih proizvoda i van grejne sezone, potencijali se šire. Postrojenja za preradu i doradu poljoprivrednih proizvoda (poput sušara) takođe se u velikoj meri mogu proizvoditi u Republici Srbiji. Prednosti i stepen iskorišćenja biomase kao obnovljivog energenta još više dolaze do izražaja pri njenoj upotrebi u kogenerativnim postrojenjima. Kad se sve navedeno uzme u obzir može se zaključiti da primena biomase može zauzeti značajno mesto u sveobuhvatnoj reindustrijalizaciji naše zemlje, o čemu će više reči biti u ovom radu. U radu je, takođe, ukazano na neke od prepreka za realizaciju ovih napora kao i primeri dobre prakse.In the context of the current geopolitical situation and energy uncertainty, the aim of the paper is to affirm the use of biomass as a domestic energy source and to point out guidelines for its proper and efficient use. According to the official data of the Ministry of Mining and Energy of the Republic of Serbia, biomass represents by far the greatest potential for renewable energy in the country. Over 60% of the estimated potential of renewable energy in the Republic of Serbia belongs to biomass (not counting large hydropower plants). The possibility of energy use of biomass, further, does not depend on weather conditions, time of day or season, unlike other renewable energy sources such as wind and solar energy. In addition to this and other advantages that biomass as the only carbon - CO2 - neutral renewable fuel has, it should be noted that facilities for the conversion of energy from biomass through combustion are relatively technologically simple and can be produced entirely in our country. If these facilities were used in district heating systems with the possibility of using thermal energy for technological processes in the cultivation and processing of agricultural products even out of the heating season, the potentials and effects of biomass utilization would increase. Facilities for processing and finishing agricultural products (such as dryers) can also be largely produced in the Republic of Serbia. Advantages and the degree of utilization of biomass as a renewable energy source are even more pronounced when used in cogeneration plants. When all the above is considered, it can be concluded that the use of biomass can take a significant place in the overall reindustrialization of our country, which will be discussed in more detail in this paper. The paper also points out some of the obstacles to the realization of these efforts as well as examples of good practice

Influence of the Object's Emissivity on the Accuracy of Infrared Temperature Measurement

This paper aims to explain importance of emissivity in non-contact measurement. The significance and methods of contactless temperature measurement, as well as the physics of non-contact measurement, are presented. Non-contact temperature measurement method is based on the laws of radiation. The temperature value that will be measured by this method depends on the temperature and the emissivity of the object. To understand the importance of emissivity for accurate temperature measurement, first of all the term of emissivity is explained more closely. Furthermore, the parts of the laboratory equipment, which was used to experimentally determine the influence of the object’s emissivity on the accuracy of temperature measurement, are explained. The body with known emissivity was heated and its temperature was measured using an infrared sensor. In order to predict impact of emissivity of body on accuracy of temperature measurement emissivity was varied from 0.7 to 1.0 by the software. Six body’s temperature points were used for analysis. The measured temperature values are shown, as well as the deviations of the measured temperature from the actual body temperature. The graphical representation is given for a better understanding of the measurement error caused by used wrong value of body emissivity

Influence of the Object's Emissivity on the Accuracy of Infrared Temperature Measurement

This paper aims to explain importance of emissivity in non-contact measurement. The significance and methods of contactless temperature measurement, as well as the physics of non-contact measurement, are presented. Non-contact temperature measurement method is based on the laws of radiation. The temperature value that will be measured by this method depends on the temperature and the emissivity of the object. To understand the importance of emissivity for accurate temperature measurement, first of all the term of emissivity is explained more closely. Furthermore, the parts of the laboratory equipment, which was used to experimentally determine the influence of the object’s emissivity on the accuracy of temperature measurement, are explained. The body with known emissivity was heated and its temperature was measured using an infrared sensor. In order to predict impact of emissivity of body on accuracy of temperature measurement emissivity was varied from 0.7 to 1.0 by the software. Six body’s temperature points were used for analysis. The measured temperature values are shown, as well as the deviations of the measured temperature from the actual body temperature. The graphical representation is given for a better understanding of the measurement error caused by used wrong value of body emissivity

Thermodynamic equilibrium modeling of biomass gasification: Effects of operating conditions on gasifier performance

Biomass has remarkable potential to reduce harmful emissions and ensure stable and sustainable energy production. In this paper, various parameters such as operating temperature, type of gasifying agent, air–fuel ratio and steam-fuel ratio are investigated on the qualitative characteristics of the syngas obtained from biomass gasification. The qualitative indicators considered were the percentage of combustible components under the energy aspect and the percentage of undesirable components under the environmental aspect. The composition of the syngas was determined for a temperature range of 500–1000 °C as an equilibrium composition using the Gibbs free energy minimisation method. The results showed that increasing the gasification temperature above 900 °C had a positive effect on the energy and environmental properties of the syngas. Air and water vapour were selected as possible gasifying agents. The results showed that water vapour was significantly more favourable than air as a gasifying agent in terms of syngas quality. In the best case, the H2 yield for gasification with air is 35 %vol, while this value reaches 65 %vol for gasification with steam. In addition to the type, the ratio of the gasifying agent to the amount of fuel was also analysed. The analysis showed that it was more favourable to carry out the gasification process at lower air-to-fuel and steam-to-fuel ratios, which is consistent with the work of other authors

SNCR in biomass combustion facilities: from theories to existing models

With the significant use of biomass for energy purposes, as the only CO2-neutral carbon-based renewable energy source, besides several well-known advantages, certain disadvantages appear. One of them is the possible increased emission of nitrogen oxides, NOx, which is especially pronounced with the usage of agricultural biomass. Given the available resources of this biomass and increasingly stringent legal norms regarding NOx emissions, this problem needs special attention, which is the topic of this paper. The paper presents: mechanisms of NOx formation and conversion of nitrogen from fuel during combustion, a brief overview of available methods for denitrification, both conventional and newer ones that have not yet come to industrial-scale application. NOx emissions from biomass combustion are mainly caused by fuel-bound nitrogen, which is especially present in biomass with a high content of bound nitrogen such as agricultural biomass. Therefore, the focus is on selective non-catalytic reduction, SNCR, as a secondary measure of denitrification. Theoretical bases of SNCR, presentation of SNCR reagents, main pathways of chemical reduction reactions for different reagents, and reaction kinetics are given. Also, the general bases for setting numerical SNCR reduction models and reviewing existing ones, as well as experimental results from the available literature, are presented. Finally, examples of industrial applications of SNCR reactors and general recommendations for the application of this denitrification measure are introduced

SYSTEMS FOR FLUE GASES TREATMENT AT THE COMBUSTION OF (AGRICULTURAL) BIOMASS

Biomass combustion has many advantages compared to fossil fuels due to reduction of carbon dioxide emissions, but several issues are present during biomass combustion. One that must always be considered is emission of nitrogen oxides (NOx), which have significant impact on the environment and health. At biomass combustion, main mechanism responsible for NOx emission is oxidation of fuel-bound nitrogen. Increased NOx emissions are particularly present at agricultural biomass combustion, due to its increased nitrogen content, which is further expressed by the use of nitrogen fertilizer. Denitrification methods are classified as pre-combustion, combustion control and post-combustion (flue gas treatment) methods. Aim of this paper is to provide insight in different flue gas denitrification methods (DeNOx measures) from the review of existing literature, with emphasis on post-combustion methods, since they have higher efficiency. Also, pre-combustion and combustion control methods at agricultural biomass combustion often do not provide reduction below emission standards. Selective catalytic (SCR) and selective noncatalytic reduction (SNCR), wet scrubbing, adsorption, electron beam, electrochemical method, non-thermal plasma and microbial approach were considered. For each method, mechanism of NOx reduction is given and discussed, alongside with efficiency that could be achieved. Overall comparison of advantages and disadvantages for these methods is provided. Further research of denitrification and optimization of described methods, to overcome NOx emission problem is required. Application of these methods in commercial use and increasing their efficiency, while solving cost and methods disadvantages, is key for biomass to be used as a renewable energy source and fossil fuel replacement

Polycyclic aromatic hydrocarbons emission from cigar burner combustion system and comparison of their content in fly ashes

Agricultural biomass is considered a preferred RES in Serbia because of its availability and suitability to limit the use of fossil fuel resources and reduce GHG emissions. Therefore, constant work has been done to develop technologies that enable its utilization for energy purposes. As an example of these efforts, in the Agricultural Corporation PKB, the soybean straw cigarette-type combustion system has been applied for greenhouse heating for over a decade. However, many volatile and semivolatile organic compounds are emitted directly into the atmosphere or concentrated in ash particles during agricultural biomass combustion. Since some of the emitted compounds, such as polycyclic aromatic hydrocarbons (PAHs), are toxic, monitoring their concentrations in fly ash is recommended. Literature data regarding PAHs content in agricultural biomass ashes are insubstantial, especially in Serbia. For that purpose, PAHs contents in the cyclone and stack fly ashes of soybean straw were investigated and compared. In addition, the emission factors, toxicity, carcinogenicity and benzo[a]pyrene equivalence concentrations were determined and used to estimate the potential environmental impact of these ashes. As a result, stack ash has been shown to have a higher potential environmental risk than cyclone ash. Hence, an assessment of using soybean straw as a feed fuel in a real cigarette-type combustion plant regarding PAHs emission is given. These results provide important information for optimizing combustion conditions and assisting the local entities in managing air pollution and control policies in Serbia

An overview of biomass combustion technologies with an emphasis on those for agricultural biomass

Nowadays increasing energy needs are experienced, while facing environmental issues as air pollution, global warming and acid rains. Due to many disadvantages of fossil fuels biomass is considered as a possible replacement. For energy purpose biomass could be used in direct combustion or in biogas and biodiesel production. This paper provides a review of different direct biomass combustion technologies, with emphasis on agricultural residual biomass as an energy source. Properties of biomass being used directly affect design of combustion furnace and operating parameter. Many agricultural raw materials which might be considered as a potential waste in fact have a great energy potential and when used for combustion this waste management problem can be reduced or even solved. With biomass usage potential issues are present as storage, high moisture contents, lower heating values and possible high emission of NOx during the combustion. New promising technologies and conventional combustion systems have been considered, among which are furnaces with combustion on grade, pulverized combustion, combustion in the fluidized bed and combustion in pushing furnace. Different agricultural biomass types are contemplated, alongside with applied technologies. Systematic comparison of described technologies is given in accordance with several different criteria, including overview of advantages and disadvantages. To achieve sustainable energy development, new technologies are necessary as well as advancement of the existing ones. In order for that to be achieved, it is important to systematize and categorize biomass combustion technologies.ISAE 2021 : 5th international symposium on agricultural engineering : proceedings; September 30th - October 2nd, 2021; Belgrade, Serbi