Gaseous SO2 Concentrations Research Articles

Synergistic reduction of SO2 emissions while co-firing biomass with coal in pilot-scale (1.5 MWth) and full-scale (471 MWe) combustors

The objective of this study was to understand the synergistic effect of sulfur dioxide (SO2) emission reduction during the combustion of biomass-coal blends in comparison to pure coal by recording the gaseous SO2 concentrations, analyzing the composition of combustion ash by energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), and simulating and verifying the fate of sulfur by a thermodynamic equilibrium software (FactSage). In Set A experiments, five combinations of coal and steam-exploded biomass (100/0, 75/25, 50/50, 25/75, 0/100 in percentages by mass) were co-fired in a 1.5 MWth pilot-scale combustor. In Set B, pure coal (100/0) and an 85/15 percent mass blend of coal and torrefied biomass were co-fired in a 471 MWe utility boiler. Woody biomass contains lower amounts of sulfur compared to coal and the linear lowering of SO2 emissions as a result of co-firing is called the dilution effect. For Set A tests, FactSage predicted, and ash analysis confirmed that calcium was primarily responsible for the synergistic emission reduction (beyond dilution effect) in all the blends, except in pure biomass, where potassium was responsible. During pure coal combustion, 41.1% of the sulfur in the system was absorbed in the ash, compared to 97.0% during pure biomass testing. In Set B tests, the 85/15 coal-biomass blend, showed a 28.1% reduction in SO2 emissions along with a 22.1% reduction in the lime slurry utilization at flue gas desulfurization (FGD) towers compared to pure coal, which is equivalent to saving 7.4 L of lime slurry per MWe-hour. The results suggest that blending woody biomass with coal can help coal-fired utility boilers meet environmental emission standards and reduce desulfurization costs. These results are important since the current literature is deficient in research conducted at suspension-fired full-scale boilers to reduce SO2 emissions by co-firing coal and biomass blends.

The effect of microstructure for Ni-based surface finishing thin film on corrosion behavior

Electroless and electroplated single-layer Ni and multilayer Ni/Pd/Au were used as surface finishing materials for automobile device substrates. When the samples were placed in a chamber with various gaseous SO2 concentrations, better corrosion resistance was observed for single-layer electroless Ni and multilayer electroplated Ni/Pd/Au compared with their well-crystalline electroplated and electroless counterparts, respectively. Electrochemical analysis and materials characterization are adopted to investigate the disparate corrosion behaviors. Galvanically displaced Pd(P) and immersion Au with a high grain boundary density provided a large number of diffusion paths for the increased growth of corrosion products on the electroless Ni/Pd/Au surface than on the electroplated surface. Reduced hydrogen gas formed blisters exerting pressure on the grain boundaries and causing defects that may enhance the diffusion of the atoms. These results proved that the microstructure and crystallinity of surface finishing films have a predominant effect on their corrosion behaviors.

In-situ monitoring of transient gas phase K–Cl–S chemistry in a pilot-scale combustor

Biomass and waste derived fuels contain large amounts of sodium, potassium, and chlorine that form NaCl and KCl, that is, compounds that cause operational problems, such as slagging, fouling, and high-temperature corrosion. Therefore, alkali chlorides are the main reasons that explain why steam parameters are less advanced and efficient in biomass and waste-based power generation when compared to coal. These problems can be mitigated by introducing sulphur into the system to form alkali sulphates that are not as problematic on steel surfaces as alkali chlorides. However, the alkali sulphation process in realistic combustion environments needs further exploration. Thus, new diagnostic methods for in-situ monitoring of alkali sulphation kinetics in combustion systems are required. In this work, the simultaneous monitoring of KCl and KOH concentrations in a pilot-scale combustor using Collinear Photofragmentation and Atomic Absorption Spectroscopy (CPFAAS) during stationary and transient operation of the combustor, is introduced. The CPFAAS information is complemented by monitoring SO2 and HCl concentrations using Fourier-transform infrared spectroscopy (FTIR). The temporal performance of the system is demonstrated by measuring the temporal combustor response curves for KCl sulphation for different Cl/K ratios during rapid changes in gaseous SO2 concentrations. The temporal concentration curves obtained imply that the Cl/K ratio has a significant impact on the temporal alkali sulphation behaviour. The measurement system described enables further exploration of K–Cl–S chemistry in realistic large-scale power plant environments.

Mass balance and partitioning of trace elements under oxy-coal combustion: First experiences

Mass balance and partitioning of inorganic trace pollutants have been evaluated at the largest oxy-Pulverised Coal Combustion (oxy-PCC) demonstration plant to date owned by Fundación Ciudad de la Energía (CIUDEN). Results reveal that the concentration of gaseous SO2, B, Se, F, and HCl increases progressively in the CO2-rich flue gas along the depuration train. This results in negative retention efficiencies of these types of pollutants and in the enrichment of trace elements in the oxy-fly ashes (oxy-FAs). These two factors affected the MB closure for highly volatile S, Cl, and F, and moderately volatile with high condensation potential B, As, and Se over the oxy-PCC and whole installation. This first experience has lead us to focusing further work on 1) elucidating the behaviour of inorganic trace pollutants in the CO2-rich flue gas after a number of CO2-rich flue gas re-circulations back to the boiler; and 2) investigating the speciation and leaching potential of inorganic trace pollutants, especially F, retained in the oxy-FAs in order to establishing remediation actions if required.

Online single particle measurement of fireworks pollution during Chinese New Year in Nanning

Time-resolved single-particle measurements were conducted during Chinese New Year in Nanning, China. Firework displays resulted in a burst of SO2, coarse mode, and accumulation mode (100–500nm) particles. Through single particle mass spectrometry analysis, five different types of particles (fireworks-metal, ash, dust, organic carbon-sulfate (OC-sulfate), biomass burning) with different size distributions were identified as primary emissions from firework displays. The fireworks-related particles accounted for more than 70% of the total analyzed particles during severe firework detonations. The formation of secondary particulate sulfate and nitrate during firework events was investigated on single particle level. An increase of sulfite peak (80SO3−) followed by an increase of sulfate peaks (97HSO4−+96SO4−) in the mass spectra during firework displays indicated the aqueous uptake and oxidation of SO2 on particles. High concentration of gaseous SO2, high relative humidity and high particle loading likely promoted SO2 oxidation. Secondary nitrate formed through gas-phase oxidation of NO2 to nitric acid, followed by the condensation into particles as ammonium nitrate. This study shows that under worm, humid conditions, both primary and secondary aerosols contribute to the particulate air pollution during firework displays.

EVALUATION OF LITHUANIAN AIR QUALITY MONITORING DATA APPLYING SYNOPTICAL ANALYSIS

Relationship between synoptical patterns and different pollutants was analysed in the study. Cases with ozone concentrations higher or equal to the 95th percentile of monthly ozone concentrations were analysed over the period 2002–2005. Ozone concentration cases were grouped into seven concentration intervals and analysed according to synoptical patterns (cold, warm and occluded fronts). Relationship between SO2, SO4 and NO2 and synoptical objects was analysed during warm and cold seasons. The influence of cold, warm and occluded fronts on the high ozone level formation are very similar at both Lithuanian rural stations of Preila and Rūgšteliškes. The influence of all the fronts was more significant during night hours at a relatively low (50–100 μg/m3) and high (>100 μg/m3) ozone levels during day hours. The concentrations of gaseous SO2, NO2 and aerosol SO4 pollutants for the cases with hourly ozone concentration values ≥95th percentile were analysed. The influence of different synoptical patterns was found to be stronger during a warm season and lower during a cold season of the year.

A Summary of Airborne Concentrations of Sulfur- and Nitrogen-Containing Pollutants in the Northeastern United States

ABSTRACT Airborne concentrations of SO2, SO4 2-, HNO3, NO3 -, NH4+, and O3 were monitored over the six-year period from September 1, 1989, through August 31, 1995, at 10 largely rural Clean Air Status and Trends Network (CASTNet) sites in the northeastern United States. Each of the sulfur- and nitrogen-containing air pollutants monitored by CASTNet displays regular, seasonal cyclical behavior and also exhibits a relatively strong high-to-low spatial concentration gradient from southwest to northeast. On average, more than 70% of the measured airborne sulfur is present as SO2, except during the summer, when the figure drops to about 50%. During the summer, the SO2 concentration is the lowest, SO4 2- is the highest, and the fraction of airborne sulfur present as SO4 2- varies considerably with location, ranging from an average of 42% at five sites in Pennsylvania to 70% at two sites in New England. Studywide, more than 70% of the measured, oxidized, airborne nitrogen (N) is present as HNO3, except during the winter, when the figure drops to about 60%. The concentrations of gaseous SO2 and HNO3 are usually comparable but not always larger than the corresponding concentrations of measured sulfur and nitrogen aerosols. Nevertheless, the relatively faster deposition velocities for gases are sufficient to ensure that SO2 and HNO3 are usually the dominant contributors to dry sulfur and nitrogen deposition. Observed changes of 1990–1995 annual average airborne sulfur and N concentrations at 10 CASTNet sites in the Northeast are generally consistent with changes in emissions estimated to have occurred in the Northeast over the same period.

Effects of SO2 fumigations on photosynthetic CO2 gas exchange, chlorophyll a fluorescence emission and antioxidant enzymes in the lichens Evernia prunastri and Ramalina farinacea

The effects of elevated gaseous SO2 concentrations in the lichens Evernia prunastri (L.) Ach. and Ramalina farinacea (L.) Ach. were investigated by means of gas exchange, modulated chlorophyll fluorescence analysis and antioxidant enzyme assays. The response to SO2 of the studied species differed markedly. Net photosynthetic rates were more adversely affected in E. prunastri than in R. farinacea. In addition, processes dependent on thylakoid membrane integrity such as PSII‐mediated electron flow and nonphotochemical quenching were reduced to a greater extent by exposure to SO2 in E. prunastri. Moreover, the ability to reoxidize the quinone pool was lower in this species. Finally, the activity of chloroplastidic and cytoplasmic antioxidant enzymes was decreased in E. prunastri in response to fumigations but increased in R. farinacea. The results suggest that the ability to process and deal with the SO2 once it has been absorbed must play a role in determining the sensitivity of these lichen species to this air pollutant.

The Chemical Characteristics of Springtime Precipitation in Lushan Mountains, East China

Abstract A comprehensive field measurement was set up in the springtime of 1993 to study the chemical characteristics of precipitation in the Lushan Mountains. The results showed that the concentrations of gaseous SO2, NOx, NH3, and HNO3 were low and precipitation was seriously acidified. The pH of all samples was less than 5.6 with an average of 4.6 and a minimum of 3.71. Sulfuric acid was the primary acidic substance to cause the acidification and nitric acid was the secondary. Both acidity and concentrations of compositions in cloud water were much higher than those in rainwater. Comparisons of different phases of precipitation showed that concentrations of ionic components in the solid phase were two to five times higher than those in rainwater, and its pH was 0.6 higher than that of rainwater. According to the measurement results, it was postulated that the acidification of precipitation was caused by joint effects of washout of local atmospheric pollutants and long-distance transportation of acidic ...

Influence of continental outflow events on the aerosol composition at Cheju Island, South Korea

The chemical composition of aerosols measured at Cheju Island, Korea, over the 3‐year period March 1992 to February 1995 are presented and discussed, with a particular emphasis on the Pacific Exploratory Mission in the Western Pacific (PEM‐West B) time period. Cheju Island is under the influence of continental outflow conditions nearly 70% of the year, and as a result the aerosol loading of sea salt as well as continental aerosol components is high. The 3‐year mean values derived from the daily tape filters are non‐sea‐salt (nss) SO22− = 6.8 μg/m3, NO3− = 1.2 μg/m3, Cl− = 1.9 μg/m3, Na+ = 1.7 μg/m3, Ca2+ = 0.5 μg/m3, NH4+ = 1.3 μg/m3, Mg2+ = 0.3 μg/m3, and K+ = 0.4 μg/m3. Sea‐salt components show peak values in winter, while calcium, nitrate, potassium, and to a lesser extent, sulfate and ammonium, show higher values in the spring, and all species exhibit a pronounced minimum in summer. Trajectory and principal component analysis show that elevated levels of primary aerosols (both sea salt and soil‐derived) occur with strong wind conditions associated with winter and spring, and high concentrations of non‐sea‐salt components are most strongly associated with springtime continental outflow events. During the PEM‐West B period, nitrate and calcium are found to be ∼60% higher than the annual mean, sea‐salt components ∼30% higher, and sulfate ∼10% higher. The aerosol data are combined with gaseous SO2 concentrations, precipitation chemistry data and companion aerosol measurements taken at the same site, to provide further insights into the aerosol composition at Cheju. At Cheju, sulfate and ammonium are found mostly in the fine fraction (∼80 to 90%), while calcium and nitrate reside in the coarse size fraction. Sulfate and nitrate are not associated with the primary aerosols, but rather become associated with the aerosol during the long‐range transport process.

Acid deposition at the summit of Mt. Fuji: Observations of gases, aerosols and precipitation in summer,1993 and 1994

Intensive observations of chemical species in aerosols, gases and other samples at the summit of Mt. Fuji and at Tarobo (at 1300m on the mountain'ts southern slope) was performed from July 28 to Aug. 3, 1993 and from July 25 to 30,1994. The most interesting observation was the abrupt increase in the sulfate concentration in aerosol collected in July, 1993 just after the typhoon (number 9306) passed the Japanese archipelago and the wind direction shifted from south to west. Chemical analysis indicated this aerosol was acidic. In contrast, the summit aerosol observed in 1994 was not acidic following a less dramatic rise in sulfate content. Back trajectory analyses were used to extrapolate from these measurement to an inventory of polluted air over the Asian Continent. The concentrations of gaseous SO2 and HCl remained low during both observation periods, with some higher concentrations of NH3.

Cloud chemistry effects on tropospheric photooxidants in polluted atmosphere — Model results

The mathematical model presented in this paper describes in detail the gas-phase chemistry (22 reactions), gas-phase/liquid-phase equilibrium (18 equilibria) and liquid-phase chemistry (57 reactions and equilibria) in a stratiform cloud system. The model is used to analyze the influence of the liquid phase on the photooxidant formation and destruction for different gaseous SO2 concentrations with and without consideration of organic aqueous phase chemistry. It has been shown that for [SO2]>1 ppb the cloud is quantitatively a sink for H2O2, OH, HO2 and O3. The ozon destruction via O3+O2-, which is most important in remote areas, is in polluted areas only significant at summer days. The role of organic components in cloud water consists in the transformation OH → HO2 where HO2 is further transformed into H2O2.

Numerical simulation on the rainout-removal of sulfur dioxide and acidification of precipitation from stratiform clouds

The rainout-removal of SO2 and the acidification of precipitation from stratiform clouds are simulated using a one-dimensional, time-dependent model, parameterized microphysically in which dissolution and dissociation of gaseous SO2 and H2O2, and oxidation reaction in aqueous phase are taken into account. The effects of dynamic factors, including updraft flow and turbulent transport, and the concentration of gaseous SO2 and H2O2 being transported into the clouds on pH value of the precipitation, the conversion rateS(IV)-S(VI) and the wet deposition rate of SO2 are discussed.

Study of bisulfite and metabisulfite aerosol generation systems.

Sulfur (IV) aerosols may be generated only as the fully neutralized sulfite by nebulization techniques. Attempts to generate bisulfite and metabisulfite aerosols result in the production of sulfite aerosols and large amounts of SO2. Previous toxicologic studies on metabisulfite and bisulfite aerosols apparently documented the effects of high concentrations of gaseous SO2.

Effects of Sulphur Dioxide on Sugar and Free Amino Acid Content of Pine Seedlings

AbstractTreatment of jack pine (Pinus banksiana Lamb.) seedlings with gaseous SO2 resulted in a shift between the reducing and non‐reducing sugars. Increasing concentrations of gaseous SO2 caused an increase in reducing sugars and a decline in the non‐reducing sugars, suggesting a conversion from the latter to the former at high SO2 concentrations. The total amino acid content of the intact tissues also increased with increasing concentrations of gaseous SO2. Gas‐liquid chromatographic analyses of the amino acids indicated that SO2 (1. 34 mg · m‐3 for 96 h) resulted in an increase in the content of alanine, valine, glycine, isoleucine, leucine, threonine, aspartic acid tyrosine, lysine, and arginine, and a decrease in the content of serine and glutamic acid. The enzymatic and other implications of such changes are discussed.

THE EFFECTS OF SULPHUR DIOXIDE UPON ESTABLISHED CELL LINES CULTIVATED IN VITRO

Studies have been made on the effects of SO2 and its salts on strain L, mouse liver, and HeLa cells. Of the cell lines tested, the HeLa cells seemed to be more sensitive to SO2 and its salts than the cells of mouse origin.Cells cultivated in "biological" medium grow in concentrations of gaseous SO2 up to 2000 p.p.m., although somewhat inhibited. Cells subjected to a concentration of 500 p.p.m. in this medium are not affected greatly and their growth is comparable to those cells in control cultures.The addition of various salts of SO2 (Na2SO4, Na2SO3, and NaHSO3) in concentrations from 10 to 200 mg% produced responses ranging from complete inhibition of growth (by 200 mg% NaHSO3) to apparent stimulation of growth by some concentrations of Na2SO4. Toxicity of these salts was in the order of NaHSO3 > Na2SO3 > Na2SO4.When cells in vitro are directly exposed to SO2 in specially designed culture flasks, strain L cells are apparently able to tolerate 5 p.p.m. SO2 for five 8-hour exposure intervals, provided a "recovery" period follows each exposure.Certain components of serum seem to play a very important role as protective agents in modifying the effect of gaseous SO2, possibly by combination.

THE EFFECTS OF SULPHUR DIOXIDE UPON ESTABLISHED CELL LINES CULTIVATED IN VITRO

Studies have been made on the effects of SO2 and its salts on strain L, mouse liver, and HeLa cells. Of the cell lines tested, the HeLa cells seemed to be more sensitive to SO2 and its salts than the cells of mouse origin.Cells cultivated in "biological" medium grow in concentrations of gaseous SO2 up to 2000 p.p.m., although somewhat inhibited. Cells subjected to a concentration of 500 p.p.m. in this medium are not affected greatly and their growth is comparable to those cells in control cultures.The addition of various salts of SO2 (Na2SO4, Na2SO3, and NaHSO3) in concentrations from 10 to 200 mg% produced responses ranging from complete inhibition of growth (by 200 mg% NaHSO3) to apparent stimulation of growth by some concentrations of Na2SO4. Toxicity of these salts was in the order of NaHSO3 > Na2SO3 > Na2SO4.When cells in vitro are directly exposed to SO2 in specially designed culture flasks, strain L cells are apparently able to tolerate 5 p.p.m. SO2 for five 8-hour exposure intervals, provided a "recovery" period follows each exposure.Certain components of serum seem to play a very important role as protective agents in modifying the effect of gaseous SO2, possibly by combination.