Influence of RDF composition on mercury release during thermal pretreatment

The growing world population is contributing to the increasing amounts of waste and a significant increase in energy demand. Therefore, coal will increasingly be replaced by refuse derived fuel (RDF), which is produced from municipal solid waste. The use of such fuel poses many difficulties because of its heterogeneity and high mercury emission. One method to stabilize the properties of RDF and reduce the mercury content is thermal pretreatment. The purpose of this study was to investigate the release of mercury from RDF samples following thermal pretreatment. The study was carried out in the temperature range of 100–350 ◦C. Statistical analysis was performed on the correlation between the composition of the RDF samples and the release of mercury. The RDF samples showed a very high variation in the mercury content, ranging from 45 to 849 µg Hg/kg (1.7 to 35.3 µg Hg/MJ). Thermal pretreatment removed a significant amount of mercury at 250 ◦C (94–99%). Paper content positively affected mercury release. Relatively low correlation coefficients were obtained in the statistical analysis, which may be explained by the significant heterogeneity of the RDF samples magnified by the variability in the mercury content within particular fractions.Web of Science162art. no. 77

Distribution of polycyclic aromatic hydrocarbons in coke plant wastewater

The subject of examinations presented in this paper is the distribution of polycyclic aromatic hydrocarbons (PAHs) between solid and liquid phases in samples of raw wastewater and wastewater after treatment. The content of 16 PAHs according to the US EPA was determined in the samples of coke plant wastewater from the Zdzieszowice Coke Plant, Poland. The samples contained raw wastewater, wastewater after physico-chemical treatment as well as after biological treatment. The ΣPHA16 content varied between 255.050 μg L−1 and 311.907 μg L−1 in raw wastewater and between 0.940 and 4.465 μg L−1 in wastewater after full treatment. Investigation of the distribution of PAHs showed that 71–84% of these compounds is adsorbed on the surface of suspended solids and 16–29% is dissolved in water. Distribution of individual PAHs and ΣPHA16 between solid phase and liquid phase was described with the use of statistically significant, linear equations. The calculated values of the partitioning coefficient Kp changed from 0.99 to 7.90 for naphthalene in samples containing mineral-organic suspension and acenaphthylene in samples with biological activated sludge, respectively.</jats:p

The method of determination of mercury adsorption from flue gases

For several recent years Faculty of Energy and Fuels of the AGH University of Science and Technology in Krakow conduct intensive studies on the occurrence of mercury contained in thermal and coking coals, as well as on the possible reduction of fossil-fuel mercury emissions. This research focuses, among others, on application of sorbents for removal of mercury from flue gases. In this paper we present the methodology for testing mercury adsorption using various types of sorbents, in laboratory conditions. Our model assumes burning a coal sample, with a specific mercury content, in a strictly determined time period and temperature conditions, oxygen or air flow rates, and the flow of flue gases through sorbent in a specific temperature. It was developed for particular projects concerning the possibilities of applying different sorbents to remove mercury from flue gases. Test stand itself is composed of a vertical pipe furnace inside which a quartz tube was mounted for sample burning purposes. At the furnace outlet, there is a heated glass vessel with a sorbent sample through which flue gases are passing. Furnace allows burning at a defined temperature. The exhaust gas flow path is heated to prevent condensation of the mercury vapor prior to contact with a sorbent. The sorbent container is positioned in the heating element, with controlled and stabilized temperature, which allows for testing mercury sorption in various temperatures. Determination of mercury content is determined before (coal and sorbent), as well as after the process (sorbent and ash). The mercury balance is calculated based on the Hg content determination results. This testing method allows to study sorbent efficiency, depending on sorption temperature, sorbent grain size, and flue-gas rates

Carbon dioxide emission in hydrogen production technology from coke oven gas with life cycle approach

The analysis of Carbon Footprint (CF) for technology of hydrogen production from cleaned coke oven gas was performed. On the basis of real data and simulation calculations of the production process of hydrogen from coke gas, emission indicators of carbon dioxide (CF) were calculated. These indicators are associated with net production of electricity and thermal energy and direct emission of carbon dioxide throughout a whole product life cycle. Product life cycle includes: coal extraction and its transportation to a coking plant, the process of coking coal, purification and reforming of coke oven gas, carbon capture and storage. The values were related to 1 Mg of coking blend and to 1 Mg of the hydrogen produced. The calculation is based on the configuration of hydrogen production from coke oven gas for coking technology available on a commercial scale that uses a technology of coke dry quenching (CDQ). The calculations were made using ChemCAD v.6.0.2 simulator for a steady state of technological process. The analysis of carbon footprint was conducted in accordance with the Life Cycle Assessment (LCA)

Carbon dioxide emission in hydrogen production technology from coke oven gas with life cycle approach

The analysis of Carbon Footprint (CF) for technology of hydrogen production from cleaned coke oven gas was performed. On the basis of real data and simulation calculations of the production process of hydrogen from coke gas, emission indicators of carbon dioxide (CF) were calculated. These indicators are associated with net production of electricity and thermal energy and direct emission of carbon dioxide throughout a whole product life cycle. Product life cycle includes: coal extraction and its transportation to a coking plant, the process of coking coal, purification and reforming of coke oven gas, carbon capture and storage. The values were related to 1 Mg of coking blend and to 1 Mg of the hydrogen produced. The calculation is based on the configuration of hydrogen production from coke oven gas for coking technology available on a commercial scale that uses a technology of coke dry quenching (CDQ). The calculations were made using ChemCAD v.6.0.2 simulator for a steady state of technological process. The analysis of carbon footprint was conducted in accordance with the Life Cycle Assessment (LCA)

Corrosive components of nutshells and their chars

Biomass combustion stands among various technologies pointed at fossil fuels consumption decrease. Biomass can be found in very diversified sources spread more evenly across the globe, can be burned with use of traditional combustion solutions and is more CO2 neutral in combustion than their fossil fuel counterparts. On the other hand biomass has several problems with composition that despite its potential diversity. Problem of excess moisture can be already solved by material selection or by preliminary pyrolysis. The main problem concerns however biomass ash composition. Biomass ashes are more prone to have higher quantities of potentially corrosive components than their coal counterparts. The example of such constituents are alkali metals, sulphur and chlorine. Ash basic composition is also important due to various ash properties like its melting temperature and slagging or fouling tendencies. To address the problem, several indices for fast properties prediction and earlier problem identification can be appointed. This work concentrates on ash quality evaluation for potentially attractive biomass fuel from nutshell materials and their corresponding char obtained by pyrolysis in 300, 450 and 550 °C. Pistachio and hazelnut shells with their chars will be analysed for corrosive compounds and their potential influence on combustion process

Corrosive components of nutshells and their chars

Biomass combustion stands among various technologies pointed at fossil fuels consumption decrease. Biomass can be found in very diversified sources spread more evenly across the globe, can be burned with use of traditional combustion solutions and is more CO2 neutral in combustion than their fossil fuel counterparts. On the other hand biomass has several problems with composition that despite its potential diversity. Problem of excess moisture can be already solved by material selection or by preliminary pyrolysis. The main problem concerns however biomass ash composition. Biomass ashes are more prone to have higher quantities of potentially corrosive components than their coal counterparts. The example of such constituents are alkali metals, sulphur and chlorine. Ash basic composition is also important due to various ash properties like its melting temperature and slagging or fouling tendencies. To address the problem, several indices for fast properties prediction and earlier problem identification can be appointed. This work concentrates on ash quality evaluation for potentially attractive biomass fuel from nutshell materials and their corresponding char obtained by pyrolysis in 300, 450 and 550 °C. Pistachio and hazelnut shells with their chars will be analysed for corrosive compounds and their potential influence on combustion process

Influence of RDF Composition on Mercury Release during Thermal Pretreatment

The growing world population is contributing to the increasing amounts of waste and a significant increase in energy demand. Therefore, coal will increasingly be replaced by refuse-derived fuel (RDF), which is produced from municipal solid waste. The use of such fuel poses many difficulties because of its heterogeneity and high mercury emission. One method to stabilize the properties of RDF and reduce the mercury content is thermal pretreatment. The purpose of this study was to investigate the release of mercury from RDF samples following thermal pretreatment. The study was carried out in the temperature range of 100–350 °C. Statistical analysis was performed on the correlation between the composition of the RDF samples and the release of mercury. The RDF samples showed a very high variation in the mercury content, ranging from 45 to 849 µg Hg/kg (1.7 to 35.3 µg Hg/MJ). Thermal pretreatment removed a significant amount of mercury at 250 °C (94–99%). Paper content positively affected mercury release. Relatively low correlation coefficients were obtained in the statistical analysis, which may be explained by the significant heterogeneity of the RDF samples magnified by the variability in the mercury content within particular fractions

Contents of Ecotoxic Elements in Polish Coking Bituminous Coals and in Products of Coking

Ecotoxic elements include the ones which have a negative impact on human health and the environment, among others, mercury, arsenic and lead. Hard coal is a fuel which contains significant amounts of ecotoxic elements and the processes of coal combustion, coking and gasification are one of the main sources of their anthropogenic emission. In the coking process, individual ecotoxic elements in various proportions remain in coke and are released to the raw coke oven gas. During the cleaning and cooling of coke gas, ecotoxic elements are distributed between purified coke gas and other coking byproducts. In the paper, the measurement results of the contents of selected ecotoxic elements in the Polish coking bituminous coals are presented, i.e. mercury, arsenic and lead. The examination results of their content in the products of the coking process i.e. coke, coal tar, BTX, sulfur, and purified coke oven gas are also shown. Coke is characterized by a much lower content of mercury and lead than coal, and by a similar content of arsenic. Among the coking products, sulfur and tar are characterized by the highest content of mercury. Coal tar also contains a high amount of lead

Analysis of gas-phase mercury sorption with coke and lignite dust

In recent years the problem of mercury emission became a widely discussed topic. Its high impact is caused by its toxicity and ability to accumulate in living organisms, properties that justified the United States Environmental Protection Agency (US EPA) to classify mercury as hazardous pollutant. The problem of mercury emission is crucial for countries like Poland, where the most of the emission is caused by coaldepended energy sector. Current technology of mercury removal utilizes adsorption of mercury on the surface of activated carbon. Due to high price of activated carbon, this technological approach seems to be uneconomical and calls for cheaper alternative. One possible solution can be usage of other sorptive materials obtained from thermal processes like coke production. Example of such material is coke dust obtained from dry quenching of coke. The aim of this work was to analyse the sorption potential of lignite and coke dust and determine parameters influencing mercury behaviour during combustion