HCl Emissions Research Articles

Upcycling Polytetrahydrofuran to Polyester

Upcycling Polytetrahydrofuran to Polyester

Flue Gas Composition and Treatment Potential of a Waste Incineration Plant

Waste-to-energy (WtE) incineration is an important technique in waste management systems and waste hierarchy. It is used to treat approximately 63% of the waste in European countries. The flue gas volumetric rate and its composition are essential to determine and monitor the emissions from waste incineration plants. This paper presents two methodologies used to evaluate the emissions from incinerators during the design phase. The first consists of a set of equations applicable in Excel (calculation model), while the second is the built-in components in Ebsilon 13.2 software which simulates the emissions from a furnace. This paper also proposes a comprehensive flue gas cleaning system for a simulated waste incineration plant in Jordan. According to Ebsilon, the results showed that for a 25 kg/s loading rate, there was 258,514 mg/Nm3, 749.90 mg/Nm3, 890.20 mg/Nm3, and 717 mg/Nm3 of CO2, NO2, SO2, and HCL, respectively. It was noted that these values relate to 1.5 of excess air ratio, where the effect of excess air ratio as the main driver for any combustion process was examined. The calculation method (set of equations) evaluated the flue gas volumetric rate, the CO2 emissions, and N2O and SO2 levels. Ebsilon allows for simulation of the treatment stages and calculates the amount of materials required. Selective non-catalytic reduction (SNCR) (a built-in component in the Ebsilon library) was used to treat the NO2 emissions. For 1.5 of excess air ratio, those emissions were reduced from 749 mg/Nm3 to 180 mg/Nm3, while the Ca(OH)2 injector used to treat the SO2 and HCL emissions reduced emissions from 890.20 mg/Nm3 and 717 mg/Nm3 to 44 mg/Nm3 and 7.16 mg/Nm3, respectively. Regarding the reduction in CO2, the spherical carbon absorption concept was simulated using 9.4 kg/s of carbon which was adequate to verify a 91% reduction rate of CO2. Furthermore, the calculation model was validated and approved as a valuable model to predict the flue gas volume, the oxygen required, and flue gas emissions at the design stage.

Global Emissions of Hydrogen Chloride and Particulate Chloride from Continental Sources.

Gaseous and particulate chlorine species play an important role in modulating tropospheric oxidation capacity, aerosol water uptake, visibility degradation, and human health. The lack of recent global continental chlorine emissions has hindered modeling studies of the role of chlorine in the atmosphere. Here, we develop a comprehensive global emission inventory of gaseous HCl and particulate Cl- (pCl), including 35 sources categorized in six source sectors based on published up-to-date activity data and emission factors. These emissions are gridded at a spatial resolution of 0.1° × 0.1° for the years 1960 to 2014. The estimated emissions of HCl and pCl in 2014 are 2354 (1661-3201) and 2321 (930-3264) Gg Cl a-1, respectively. Emissions of HCl are mostly from open waste burning (38%), open biomass burning (19%), energy (19%), and residential (13%) sectors, and the major sources classified by fuel type are combustion of waste (43%), biomass (32%), and coal (25%). Emissions of pCl are mostly from biofuel (29%) and open biomass burning processes (44%). The sectoral and spatial distributions of HCl and pCl emissions are very heterogeneous along the study period, and the temporal trends are mainly driven by the changes in emission factors, energy intensity, economy, and population.

Emission characteristics and impact factors of air pollutants from municipal solid waste incineration in Shanghai, China

The emission of air pollutants from the municipal solid waste (MSW) incineration is one of the major concerns in air pollution. The up-to-date emission situation for Chinese MSW incineration is largely unknown. The emission factors (EFs) are the key parameters to estimate the emissions from MSW incineration. The localized EFs from MSW incineration in Shanghai, China were established using continuous emission monitoring system data from 2017 to 2019. Our results showed that the EFs were 9.80 g t−1 of PM, 46.62 g t−1 of SO2, 812.68 g t−1 of NOx, 25.84 g t−1 of CO, and 17.49 g t−1 of HCl for the period 2017–2019, nearly 1.7–24.2 times lower than those in 2010, implying that the current EFs should be updated to avoid overestimation of MSW emissions in China. Compared with 2010, the emissions of PM, SO2, CO, and HCl in 2019 were significantly reduced by 84%, 69%, 47%, and 72%, respectively, except for NOx with a 106% increase, although the corresponding MSW incineration amount increased by 356%. The current levels of air pollutants from MSW incineration have already met the current national emission standard as well as the stricter standard of the European Union (98.87%–99.91%). Our findings suggest that China should update the current standards of MSW incineration, which can be a benefit for the prevention and control of MSW incineration in the future. It is still challenging to control NOx emissions from MSW incineration for Shanghai and even greater China.

Impact of Pandemic COVID-19 on Air Quality at a Combustion Plant and Adjacent Areas

Following the emergence of the infectious disease COVID-19, caused by the coronavirus SARS-Cov-2, the WHO (World Health Organization) declared a pandemic in March 2020. The pandemic has affected people’s health, social behaviour, and the economy around the world. It has also had an indirect impact on the environment, including atmospheric air quality, related to changes in the levels of pollutant emissions and the amounts of greenhouse gases released into the atmosphere. The observed changes have, in part, been a consequence of restrictions on human movement, which has translated into an increase in water consumption, and consequently into an increase in the volume of wastewater. As a result, a new type of incoming load has appeared in sewage treatment plants. Municipal sewage sludge (MSS) is a waste product from the wastewater treatment process, containing substances that are hazardous to both the environment and humans (bacteria, pathogens, viruses). To dispose of these contaminants, MSS is thermally processed in specially designed installations. Thermal recycling technology is based on a fluidized bed, in which MSS is rapidly transformed at a temperature of at least 750 °C. Organic compounds are oxidized, gasified, and combusted. The exhaust fumes are emitted into the atmosphere. They also carry a load of pollutants, which can affect the air quality both on site and in the surroundings of the treatment plant. This paper presents measurements of air pollutant emissions and pollutant concentrations provided by the Group Sewage Treatment Plant in Łódź Itd. Łódź is a city located in Poland, in central Eastern Europe. The research covers the area of the wastewater treatment plant and its immediate surroundings within a radius of about 1.5 km. The data show the influence of the pandemic restrictions on the concentrations of gaseous substances, bacteria, fungi, and particulate matter on the state of air quality. Increased emissions of NOx (by 86%), PM10 (by 50%), HCl (by 37%), and SO2 (by 16%) were observed compared to the pre-COVID-19 period.

Impact of COVID-19 Case Numbers on the Emission of Pollutants from a Medical Waste Incineration Plant

This article examines the correlation between the amount of pollutants emitted from medical waste incinerator plant and the number of COVID-19 infections, based on the example of Podlaskie Voivodeship in Poland. This paper deals with the issues of medical waste management during the COVID-19 pandemic. Thermal processing is characterised as a method of medical waste utilisation. The technological sequence of the medical waste incineration installation and the integrated exhaust gas cleaning system are discussed. The results of studies on the emission of pollutants into the atmosphere during combustion are compared with the number of COVID-19 cases in the same voivodeship to investigate how the coronavirus pandemic affects the amount of medical waste generated, thus the amount of pollutants emitted into the atmosphere. The Pearson's linear correlation coefficient and the Student's t-test are used to verify the results. The analysis results show a statistically significant, moderate positive correlation between the amount of covid waste and the number of COVID-19 cases (0.5140). In turn, there is also a statistically significant moderate correlation between the number of COVID-19 cases and emissions of SO2 (r = 0.6256, p = 0.010), NOx (0.5019, p = 0.048), and HCl (0.5130, p = 0.042). This correlation finding highlights additional costs to the environment and public health as the number of COVID-19 cases increase, which can be taken into account for pandemic planning by governments in the future.

Anthropogenic Impacts on Tropospheric Reactive Chlorine Since the Preindustrial

AbstractTropospheric reactive gaseous chlorine (Cly) impacts the atmosphere's oxidation capacity with implications for chemically reduced gases such as methane. Here we use Greenland ice‐core records of chlorine, sodium, and acidity, and global model simulations to show how tropospheric Cly has been impacted by anthropogenic emissions since the 1940s. We show that anthropogenic contribution of nonsea‐salt chlorine significantly influenced total chlorine and its trends after the 1940s. The modeled regional 170% Cly increase from preindustrial to the 1970s was driven by acid displacement from sea‐salt‐aerosol, direct emission of hydrochloric acid (HCl) from combustion, and chemical reactions driven by anthropogenic nitrogen oxide (NOx) emissions. Since the 1970s, the modeled 6% Cly decrease was caused mainly by reduced anthropogenic HCl emissions from air pollution mitigation policies. Our findings suggest that anthropogenic emissions of acidic gases and their emission control strategies have substantial impacts on Cly with implications for tropospheric oxidants, methane, and mercury.

Co-combustion behavior of municipal solid waste and food waste anaerobic digestates: Combustion performance, kinetics, optimization, and gaseous products

With the rapid development of food waste anaerobic digestion, the safe treatment of its digestates (FWD) is an urgent mission. Co-combustion of FWD with municipal solid waste (MSW) provided a cleaner and sustainable solution. In this study, the co-combustion behavior of FWD and MSW was investigated by thermogravimetric and Fourier transform infrared (TG-FTIR) analysis. Co-combustion with MSW improved the combustion performance of FWD. Compared to calculative value, experimental CCI were maximally improved at M9F1, with growth of 32.9%. Besides, the combustion indexes were exponentially enhanced as the heating rate increased. CCI of MSW and FWD increased by 7.97 times and 7.33 times as heating rate rose from 10 K/min to 40 K/min. Kinetic analysis showed that the average apparent energy for FWD and MSW were 141.3 and 159.1 kJ/mol, respectively. The lowest average apparent energy was obtained at M1F9 with 135.5 kJ/mol. According to the established model, optimal operating condition was achieved at 540.4 °C, 40 K/min and MSW proportion of 0.95. FTIR results showed that total gas emissions of CO2, CO, NO, HCN and HCl from MSW were greater than FWD. High proportion of FWD was beneficial to reduce the emissions of gaseous pollutants. The experimental emissions of NO and HCl were decreased by 20.8% (M3F7) and 18.6% (M7F3).

Impacts of chlorine chemistry and anthropogenic emissions on secondary pollutants in the Yangtze river delta region

Multiphase chemistry of chlorine is coupled into a 3D regional air quality model (CMAQv5.0.1) to investigate the impacts on the atmospheric oxidation capacity, ozone (O3), as well as fine particulate matter (PM2.5) and its major components over the Yangtze River Delta (YRD) region. The developed model has significantly improved the simulated hydrochloric acid (HCl), particulate chloride (PCl), and hydroxyl (OH) and hydroperoxyl (HO2) radicals. O3 is enhanced in the high chlorine emission regions by up to 4% and depleted in the rest of the region. PM2.5 is enhanced by 2–6%, mostly due to the increases in PCl, ammonium, organic aerosols, and sulfate. Nitrate exhibits inhomogeneous variations, by up to 8% increase in Shanghai and 2–5% decrease in most of the domain. Radicals show different responses to the inclusion of the multiphase chlorine chemistry during the daytime and nighttime. Both OH and HO2 are increased throughout the day, while nitrate radicals (NO3) and organic peroxy radicals (RO2) show an opposite pattern during the daytime and nighttime. Higher HCl and PCl emissions can further enhance the atmospheric oxidation capacity, O3, and PM2.5. Therefore, the anthropogenic chlorine emission inventory must be carefully evaluated and constrained.

Aspects of chemical recycling of complex plastic waste via the gasification route

Oxygen blown high-temperature gasification constitutes an opportunity for chemical recycling of plastic wastes. This article summarizes the results from comparative tests of combustion and gasification of two complex plastic wastes: a plastic reject (PR) from processing recycled paper and an automotive shredder residue (ASR). Calculated gasification efficiencies corresponded to about 80% and 60%, respectively. Gasification resulted in lower yields of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) compared to direct combustion. A two-stage process, including gasification followed by syngas combustion, reduced the emissions of HCl and PCDD/F in the flue gas to <1.4% and <0.2%, respectively, compared to the levels from direct combustion of the PR feedstock. Most of the PCDD/F (>99%) was captured along with particulate matter (soot) during gasification. The contribution to the toxic concentration of PCDD/F was mainly from the PCDF congeners. Fly ash particulate matter from ASR combustion contained a significant proportion of zinc, which thus constitutes a great potential for use in zinc recycling.

Assessment of Cow Dung Pellets as a Renewable Solid Fuel in Direct Combustion Technologies

Recently, biomass application as a renewable energy source is increasing worldwide. However, its availability differs in dependence on the location and climate, therefore, agricultural residues as cow dung (CD) are being considered to supply heat and/or power installation. This paper aims at a wide evaluation of CD fuel properties and its prospect to apply in the form of pellets to direct combustion installations. Therefore, the proximate, ultimate composition and calorific value were analyzed, then pelletization and combustion tests were performed, and the ash characteristics were tested. It was found that CD is a promising source of bioenergy in terms of LHV (16.34 MJ·kg−1), carbon (44.24%), and fixed carbon (18.33%) content. During pelletization, CD showed high compaction properties and at a moisture content of 18%,and the received pellets’ bulk density reached ca. 470 kg·m−3 with kinetic durability of 98.7%. While combustion, in a fixed grate 25 kW boiler, high emissions of CO, SO2, NO, and HCl were observed. The future energy sector might be based on biomass and this work shows a novel approach of CD pellets as a potential source of renewable energy available wherever cattle production is located.

Do FeCl3 and FeCl3/CaO conditioners change pyrolysis and incineration performances, emissions, and elemental fates of textile dyeing sludge?

The pyrolysis and incineration performances of sulfur-rich textile dyeing sludge (TDSS) were determined in response to the additions of FeCl3 or FeCl3 + CaO. The emissions of eight air pollutants from the incineration and pyrolysis were systematically identified. The 3-to-8% FeCl3 additions increased the comprehensive combustibility index by 2.14 and 1.62 times, respectively, as opposed to the 5-to-10% FeCl3 + 8-to-15% CaO additions. The CaO addition inhibited the TDSS incineration, while the FeCl3 addition increased HCl emission. NOx, SO2, and H2S emissions decreased initially and increased between 600 and 950 °C. SO2 and NOx emissions rose with FeCl3 but FeCl3 + CaO. FeCl3 catalyzed NOx, while CaO retained SO2. The main pyrolysis gas/liquid products were alkane, alkenes, nitrile, heterocyclic compounds, benzene, and its derivatives. Benzene and its derivatives accounted for 55.33% of the control group and 42.25–57.23% of the treatment groups. The FeCl3 and FeCl3 + CaO additions did not significantly influence the pyrolysis products. The measured versus thermodynamically simulated SOx and HCl emissions were consistent. Neural network-based simultaneous optimizations of the non-linear dynamics of eight kinds of gases pointed to 50% and 14.4% reductions in the emissions and the pyrolytic temperature, respectively, with the 3% FeCl3, relative to the control.

Анализ зарубежного опыта применения систем газоочистки тепловых электрических станций на твердых коммунальных отходах

The existing method for selecting the structure of a power plant for thermally recycling municipal solid waste (MSW) in the Russian Federation does not address the matter of selecting all components of an energy complex operating on MSW, but places focus on determining the best accessible waste thermal neutralization technology. This generates the need to search for new methods and to select criteria of choosing the structure for each particular project. A comparative analysis of various structural schemes of waste-to-energy plants widely used outside of Russia will make it possible to reveal their main advantages and drawbacks, and to determine their application fields. The article describes the statistical indicators characterizing the operation of the flue gas purification system from acid gases, which can be applied in performing a feasibility study, intellectual property assessment, and in carrying out front-end engineering. For waste-to-energy plants constructed in an urban environment and aimed to operate with keeping to a minimum the gross emissions of acid gases into the atmospheric air, the use of a wet reactor system is recommended, which will ensure low emissions of HF, HCl, and SOx. The system with a wet reactor will make it possible to reduce gross emissions of harmful substances during the operation of large capacity waste-to-energy power plants and will be a justified choice in such case. In constructing medium capacity waste-to-energy plants (with a throughput of up to 350 000 t of MSW per annum), semi-dry and dry reactors can be used; for such plants, the technology involving the use of a semi-dry reactor is the most preferred one.

A novel purification method for fluoride or chloride molten salts based on the redox of hydrogen on a nickel electrode.

A novel purification process was proposed for molten salts based on the polarization of a hydrogen electrode on nickel, i.e., H+/H2, Ni electrode. The features of the H+/H2, Ni electrode in typical chloride and fluoride molten salts were investigated. Consistent current electrolysis was performed in a feasible polarization range, and the deoxidation efficiency was higher than that of the traditional chemical or electrochemical purification methods in both chloride and fluoride molten salts. Only H2 was used as a purification source gas, and almost no toxic HF or corrosive HCl emissions were used or occurred in the new process. The application range of the proposed method was also discussed.

Operational guidelines for emissions control using cross-correlation analysis of waste-to-energy process data

The aim of this study was to develop a data analysis method which could provide operational insights and guidelines waste-to-energy (WtE) plant operators. A method to filter outliers with changing properties was combined with a cross-correlation analysis method that can capture nonlinearity and quantify time lags between variables. The method was applied to a dataset obtained from a commercial WtE plant. The method was able to detect already established correlations such as the influence of combustion conditions on NOx and CO emissions, which both had positive correlation with O2 concentration in the flue gas, while the effect of combustion conditions was unnoticeable for HCl emissions. Furthermore, the method could detect that NOx and SO2 emissions exhibited positive correlations with the furnace temperature. Time lags provided additional information about the sensor locations and plant dynamics. This methodology can be used especially when process data is available while good process models are not immediately accessible for determining non-obvious process phenomena not only for WtE sector but also for process industry in general.

EU countries experience analysis in using various fume gas treatment systems from acid gases removing for WTE Plants

The existing method of selecting the structure of a Waste to energy plant (WTE plant) for thermal utilization of MSW in the Russian Federation is often not applicable to real objects, which leads to the need for each project to search for new methods, select the criteria for choosing the best technology.Conducting a comparative analysis of various structural schemes WTE plant, common in the EU and Japan, will help to identify their main advantages and disadvantages, determine the scope of application.This article describes the statistical indicators of the flue gas treatment system (FGT) from acid gases, which can be applied at the stage of feasibility study, development of basic engineering. When building a WTE plant in urban conditions and striving to minimize the gross emissions of acid gases into the atmosphere, a wet FGT cleaning system can be recommended, which will provide low emissions of HF, HCl, and SOx. The system with a wet reactor will reduce the gross emissions of harmful substances during the construction of WTE plant with high-capacity, and in this case it is justified.When building WTE plant with medium-capacity (up to 350 thousand tons of MSW per year), it may be recommended to use a semi-dry and dry FGT, while the highest preference should be given to the technology with a semi-dry reactor as the most promising.

Significant Decrease in Wet Deposition of Anthropogenic Chloride Across the Eastern United States, 1998–2018

AbstractUsing deposition observations from precipitation samples collected by the National Atmospheric Deposition Program at 125 sites across the United States, we show that the mean wet deposition flux of non‐sea‐salt chloride (NSS Cl−) has decreased by 83% throughout the eastern United States between 1998 and 2018. We find that 30% of the sites switch from having excess Cl− to being depleted in Cl−. We attribute the observed decreases in NSS Cl− deposition to a 95% decrease in U.S. anthropogenic HCl emissions since 1998. We propose that industry emission controls that remove HCl as a cobenefit of NOx and SO2 have caused significant decreases in NSS Cl− deposition throughout the eastern United States, in addition to shifts from coal to natural gas and to coal with lower Cl− content. Our analysis implies that the lower tropospheric reactive inorganic chlorine burden was larger over the United States in the past than it is today.

Reducing HCl Release to the Environment by Eliminating Methyl Chloride at Reactors End of Run

Study of unreacted MeCl clearing from CSTR reactors at the end of run: It is a unique set up with CSTR reactors in cascade, used to produce salt-based product, esters and methanol from this unit operations. This study involves chemical reaction Engineering and process improvement experiments along with control logics to perform the steps to eliminating MeCl to the environment either in vapor or liquid form. pH and agitation speed are critical criterion to determine the presence of MeCl in the final drained liquid after the end of run. Process trends have been depicted in the study to verify the authenticity of the steps followed. Practical methods have been run through the lab analysis as well as studies done through the real unit operations environment. Reaction calculation was also part of methods used to conclude some portion of the study. Most literatures were referred through MeCl thermal and physical property data through published safety data sheets and pending patents on scrubbing methods of MeCl. Data was also collected through lab analysis on GC spectrometry with both gas and liquid methods, collected reading from unit operations at different ranges of pressure profile. This discussion would involve the use of water and caustic wash to react most of the MeCl out. The point in question is to minimize or eliminate of HCl emissions generated through unreacted MeCl when reactors are at the end of run and eventually getting washed off. Study concludes by giving quantity of MeCl (eventually HCl) sent to flare or thermal oxidizer to eventually burn-out. Recommendations were made with respect to number of cycles of wash to minimize the inert levels, thermal efficiency improvement to crack down the MeCl down that will be burned as well as changes in handling the unit operations. Conclusions are based on flash calculations, chemical reaction between Caustic, Water and MeCl + heat through steam jackets with combinations of pressure and temperature changes. Results published with the successful run of the process that is being recommended through the study.

Temporal Variations in Scrubbing of Magmatic Gases at the Summit of Kīlauea Volcano, Hawai‘i

AbstractMeasurements of gas compositions and emission rates play a major role in monitoring restless volcanoes. However, thermodynamic calculations imply that scrubbing by groundwater will prevent most HCl and significant SO2 emissions until dry pathways are established, thus leading to underestimates of gas released from magma and magma volumes. Despite the significance, direct evidence for scrubbing is mostly lacking. Based on 50 water samples collected between 2003 and 2011 from the deep NSF Well at the summit of Kīlauea Volcano, we show that the chemical and stable isotope compositions of groundwater were modified by magmatic gas condensation. Temporal variations of dissolved SO42− and Cl− in the water coincided with changes in magmatic and volcanic activities. The temporal variations in water level and chemical and isotopic compositions support prior inferences of magmatic SO2 and HCl scrubbing by groundwater at Kīlauea Volcano.

Effects of plant additives on the concentration of sulfur and nitrogen oxides in the combustion products of coal-water slurries containing petrochemicals

The active use of solid fossil fuels (coal) in the production of heat and electricity has led to significant pollution, climate change, environmental degradation, and an increase in morbidity and mortality. Many countries (in particular, European ones, China, Japan, the USA, Canada, etc.) have launched programs for using plant and agricultural raw materials to produce heat and electricity by burning them instead of or together with traditional fuels. It is a promising solution to produce slurry fuels, based on a mixture of coal processing, oil refining and agricultural waste. This paper presents the results of experimental research into the formation and assessment of the most hazardous emissions (sulfur and nitrogen oxides) from the combustion of promising coal slurry fuels with straw, sunflower and algae additives, i.e. the most common agricultural waste. A comparative analysis has been carried out to identify the differences in the concentrations of sulfur and nitrogen oxides from the combustion of typical coal, coal processing waste, as well as fuel slurries with and without plant additives. It has been shown that the concentration of sulfur and nitrogen oxides can be reduced by 62–87% and 12–57%, respectively, when using small masses of plant additives (no more than 10 wt%) and maintaining high combustion heat of the slurry fuel. However, the use of algae and straw in the slurry composition can increase the HCl emissions, which requires extra measures to fight corrosion. A generalizing criterion of slurry fuel vs. coal efficiency has been formulated to illustrate significant benefits of adding plant solid waste to coal-water slurries containing petrochemicals. Straw and sunflower waste (10 wt%) were found to be the best additives to reduce the air pollutant emissions.