SOx Emissions Research Articles

Evaluation of the impact of the national strike of the road freight transport sector on the air quality of the metropolitan region of Rio de Janeiro, Brazil

In May 2018, there was a road freight transport standstill in Brazil that lasted 11 days. During this period, several impacts on Rio de Janeiro’s daily life were reported, such as the reduction of road passenger transport services and lack of fuels. This study aimed to evaluate the impact on the air quality of the metropolitan region of Rio de Janeiro (MRRJ) of the reduction of heavy-duty vehicles on the streets and roads. For this purpose, the reductions of PM10, NOx, SOx and CO emissions, due to low circulation of buses and trucks, were estimated in order to assess the levels of air pollution indirectly. Besides, air quality data (PM10, NO2, SO2, and CO) monitored before and during the strike were used. The results showed a reduction in total emissions of local air pollutants, harmful to human health from 22 % to 43 % during strike days. However, the air quality reflexes were not observed in the same proportion, on the contrary, increases were observed in pollutant concentrations in the atmosphere during traffic stoppage in the study areas, due to different weather conditions in the two periods, which directly influenced air pollutants dispersion.

Achieve Global Renewable Energy and Low Carbon Goal Through Constructing Human 'Faults' in Electric Grids

The current 25% of global renewable energy among electric grids generation is far from the stated goal of 60% in 2040 and 100% in 2050. One of the biggest dilemma to cost-effectively increase this percentage, through grids interconnection, is that the traditional fault blocking methodology has reached its safety protection ceiling. In contrary to the traditional wisdom that any form of faults must be avoided, here we proposed a fault dredging methodology by constructing human “faults” to create artificial fault current release channels to solve high-level fault current bottleneck during grids interconnection. Using actual region electric grids from globally representative countries across six continents for demonstration, our results show that human “faults” can enable the percentages of renewable energy in USA, UK, China, Brazil, Australia, Nigeria and IEEE RTS system increase from 19.2%~47.2% to over 90%, which are much higher than all of conventional technologies. Correspondingly, the emissions of CO2, NOX and SOX in these systems respectively decrease by 67.84%~88.07%, 61.17%~88.24% and 58.25%~88.33%. Our findings suggest a new approach to reach the global renewable energy goal and promote the progress toward achieving carbon-free energy system.

Wet torrefaction of empty fruit bunches (EFB) and oil palm trunks (OPT): Effects of process parameters on their physicochemical and structural properties

In this work, the effect of wet torrefaction using conventional acid digestion vessel at three different temperatures (i.e., 180, 210, and 240 °C for 3.0 hours) and three different residence times (i.e., 2.0, 2.5, and 3.0 hours at 240 °C) onto the physicochemical, phase, and fuel properties as well as minerals content of EFB and OPT are evaluated. In both EFB and OPT cases, increasing temperature from 180 to 240 °C at 3 hours residence time and increasing residence time from 2 to 3 hours at 240 °C led to the reduction in the mass yield and an increase in the energy density. Generally, OPT hydrochar has lower mass yield relative to that of EFB. Van Krevelen diagram analysis reveals that EFB and OPT experienced dehydration and decarboxylation reactions. Such reactions reflect the occurrence of hemicellulose and partial cellulose decomposition during wet torrefaction as indicated by the changes in the intensities of several FTIR bands as a function of temperature and residence time and also by the changes in the intensities of the three XRD peaks at 2θ of 15.5, 22.7, and 34.6o representing crystalline cellulose phase when subjected to wet torrefaction at 240 °C for 3 hours. XRD peak analysis also indicates the presence of Si, Mg, and CaCO3 in the original and wet torrefied EFB and OPT. XRF results show that wet torrefaction at up to 240 °C for 3 hours can effectively remove K, Ca, and Cl from EFB and OPT and maintain S content at below 3 wt.%, which may partially resolve the slagging and agglomeration problems related to the EFB and OPT use in boiler as well as their SOx emission issue upon combustion.

Flamelet LES of a swirl-stabilized multi-stream pulverized coal burner in air and oxy-fuel atmospheres with pollutant formation

A large-eddy simulation of a swirl-stabilized multi-stream laboratory-scale pulverized coal burner designed specifically for oxy-fuel investigation is conducted using a three-mixture-fraction flamelet model, in which both NOx and SOx emissions are considered. The simulation results are compared to those in an air atmosphere and the available experimental data. The flame structures and pollutant formation mechanisms are analyzed in detail. The results show that the oxy-coal flame is narrower in the radial direction compared to the air-coal flame. Further, the particle clustering phenomenon can be observed in the oxy-fuel atmosphere. The distributions of the thermo-chemical quantities in different conditions are significantly different. For pollutant formation, the results show that NO is mainly formed around the quarl zone in an oxy-fuel atmosphere, while a large amount of NO is formed in the far downstream region in an air atmosphere. Although the instantaneous distributions of SOx are qualitatively similar in different conditions, they are quantitatively different due to the different oxygen partial pressure in the air and oxy-fuel atmospheres.

Simultaneous prediction of steam production and reduction efficiency in recovery boilers of pulping process

The role of the recovery boiler in the process of pulping is vital as it renders the industrial plant environmentally and economically viable. This boiler reduces the environmental impact of directly disposing liquor. Moreover, the equipment produces “green” steam without the use of fossil fuels as it burns the byproduct (black liquor). The reduction efficiency is the most important variable used to verify the completeness of black liquor combustion. However, because of the need to ensure green steam production, vapor generation in recovery boilers has become an important variable for evaluation. In the literature, only one of the cited variables (reduction efficiency and vapor generation) is found at a time. In this study, a recovery boiler is simulated using Aspen Plus® commercial software to determine the effect of airflows on both the reduction efficiency and green steam production simultaneously. The free energy minimization method is used to predict the composition and production of smelt and the composition of exhaust gas. The results are compared with industrial and literature data, and the model predictions are found to agree with the measurements. Furthermore, a sensitivity analysis is performed on the airflow rates to verify the possibility of increasing steam production without impairing the reduction efficiency. The observations indicated a feasibility of increasing steam by 1 t/h, resulting in a reduction of 675,840 Nm³/year of natural gas usage in conventional boilers. Reduction of CO, SOX, and NOX emissions by 57, 76, and 22%, respectively, can also be achieved owing to these improved airflow rates.

Optimization of the Performance of Marine Diesel Engines to Minimize the Formation of SOx Emissions

Optimization procedures are required to minimize the amount of fuel consumption and exhaust emissions from marine engines. This study discusses the procedures to optimize the performance of any marine engine implemented in a 0D/1D numerical model in order to achieve lower values of exhaust emissions. From that point, an extension of previous simulation researches is presented to calculate the amount of SOx emissions from two marine diesel engines along their load diagrams based on the percentage of sulfur in the marine fuel used. The variations of SOx emissions are computed in g/kW·h and in parts per million (ppm) as functions of the optimized parameters: brake specific fuel consumption and the amount of air-fuel ratio respectively. Then, a surrogate model-based response surface methodology is used to generate polynomial equations to estimate the amount of SOx emissions as functions of engine speed and load. These developed non-dimensional equations can be further used directly to assess the value of SOx emissions for different percentages of sulfur of the selected or similar engines to be used in different marine applications.

Combustion and Emission Characteristics of Emulsified Biofuel Used for Diesel Engines

In April 2018, the International Maritime Organization (IMO) adopted its Initial GHG Strategy, which defined goals for the international shipping sector to achieve by 2050: reducing CO2 emissions per transport work by 70% and total GHG emissions by at least 50% compared to 2008. As for SOx emissions from ships, the 0.5% global cap on the sulfur content of any fuel oil on board ships took effect on 1 January 2020. Biofuel is described as carbon neutral and, in general, has low levels of sulfur. For these reasons, it is expected to be more commonly used as a marine fuel in the future. However, biofuel emits more NOx from diesel engines, because its oxygen content is higher than that of gas oil.

Performance enhancement and emission control of diesel engine

In order to solve the problem of emission of harmful gases like Nox, Sox, and CO which are being emitted into the atmosphere and to improve the performance of the engine we have made three subprojects like hydrogen generator equipment, urea injection in exhaust gas flow and a separate chamber to control the emission. In the hydrogen generator equipment, we have made a setup using aluminum rods and baking soda solution to generate hydrogen gas which should be mixed with the inlet compressed air of the engine. Then, the aqueous urea is injected in the exhaust before the Selective Catalytic Reduction (SCR) to increase the conversion of harmful nitrogen oxides to nitrogen and oxygen. At last, the separate chamber is made to absorb the fine carbon particles and to considerably reduce the Sox and Nox emission. Form this analysis engine emits less smoke than normal exhaust as the average value of HSU is 38.01.

Enhancing energy efficiency for new generations of containerized shipping

The present paper aims to study the best methods that can be applied to improve energy management onboard container ships of large capacity. Container ships of class A13, A15, and A19 are considered. Those ships are taken as a reference to evaluate the impact of the proposed methods from the viewpoints of environmental and economic aspects. Their calculated energy efficiency values are 3.94. 4.28, and 16.29 gCO2 per ton. Nautical mile, respectively. Ship class A19 appeared as the best ship in terms of emissions rates that can be reduced annually with reference to the transported cargo. These rates are 3.4, 149.9, 13.8, 5677, and 1.8 kg/TEU for SOx, NOx, CO, CO2, and PM emissions, respectively. To enhance energy management for the A13, the ship will be forced to decrees its speed by 45 percent. The proposed concept will fulfil with 2023-year legislations by rate of 5860 $ per each ton CO2 decreased. Alternatively, applying the strategy of LNG fueled engine for container ship class A19 can expand the energy measure about 9.34% at yearly operating reduction by 24.7 million dollars.

Experimental study on sulfur-containing products in pressurised oxy-fuel pyrolysis of pulverised coal

Although the contribution of the pressurised oxy-fuel combustion technology for improving energy conversion efficiency and reducing SOx emissions is well recognised, the mechanism of sulfur transformation in the initial pyrolysis step has not yet been elucidated because of the complexity of the pyrolysis process. Clarifying such scientific fundamentals and overcoming technological challenges can effectively advance the implementation of pressurised oxy-fuel combustion technology and realise cleaner production. Herein, the transformation mechanisms of sulfur among solid, liquid, and gaseous states during the pressurised oxy-fuel pyrolysis of pulverised coal were experimentally investigated. The analysis of the gaseous products indicated that the concentration of H2S, the most abundant gaseous product, decreased from 840.3 to 32.1 ppm as the operating pressure increased from 0.1 to 3.1 MPa. Similar trends were observed for CH3SH and SO2. Conversely, COS concentration first increased from 61.4 to 143.4 ppm, after which it decreased to 30.4 ppm, a level similar to H2S concentration. The decreasing sulfur concentration in the volatiles is attributable to the oxidation of low-valence sulfur to form high-valence sulfur and the subsequent absorption by alkali metals in the char residue. The sulfur concentration in liquid tar, which was determined by the competitive reactions of the cracking of heavy hydrocarbons and the polymerisation of light volatiles, first decreased from 6.25 to 3.17 mg/L, followed by an increase to 5.03 mg/L as the operating pressure increased. To further investigate the sulfur transformation, the physicochemical, morphological, and structural properties of pyrolysed char were characterised. The crystal phase, microstructure, average particle size, specific surface area, and surface elemental content of the char affected the distribution and conversion of organic and inorganic sulfur in the char residue. The total sulfur content in the char residue typically increased with operating pressure. Moreover, the effect of operating temperature on the sulfur-containing products was investigated. Based on the experimental results, a binary correlation fitting was applied to predict the various trends in different sulfur-containing gaseous products of pressurised oxy-fuel pyrolysis.

Shipping emissions in the Iberian Peninsula and the impacts on air quality

Abstract. Marine traffic has been identified as a relevant source of pollutants, which cause known negative effects on air quality. The Iberian Peninsula is a central point in the connection of shipping traffic between the Americas, Africa, and the rest of Europe. To estimate the effects of shipping emissions inland and around the Iberian Peninsula, the EMEP/MSC-W model was run considering and not considering shipping emissions (obtained with STEAM3). Total estimated emissions of CO, CO2, SOx, NOx, and particulate matter (subdivided into elementary carbon – EC, organic carbon – OC, sulfate, and ash) for the study domain in 2015 were respectively 49, 30 000, 360, 710, 4.5, 11, 32, and 3.3 kt yr−1. Shipping emissions increased SO2 and NO2 concentrations, especially near port areas, and also increased the O3, sulfate, and particulate matter (PM2.5 and PM10) concentrations over the entire Iberian Peninsula coastline (especially in the south coastal region). Shipping emissions were responsible for exceedances of WHO air quality guidelines for PM2.5 in areas far from the coastline, which confirms that shipping emissions can contribute negatively to air quality, both in coastal and inland areas.

Well-to-wheel analysis of energy consumption, greenhouse gas and air pollutants emissions of hydrogen fuel cell vehicle in China

Hydrogen fuel cell vehicle (HFCV) is considered as a promising solution for reducing greenhouse gas (GHG) and air pollutants emissions and improving energy security in the transportation sector. This study presents a well-to-wheel (WTW) analysis to estimate the WTW fossil fuel consumption, GHG emission and air pollutants emissions of VOCs, CO, NOx, SOx, PM2.5 and PM10 for HFCV under 12 hydrogen pathways in China for the current (2017) and near future (2030). The results were compared with the gasoline-fueled internal combustion engine vehicle (gasoline-ICEV) and battery electric vehicle (BEV) counterparts. The results show that HFCV can reduce 11–92% fossil fuel consumption compared with gasoline-ICEV in 2017, with one exception that HFCV based on on-site water electrolysis by grid electricity in which fossil fuel consumption increased by 10% instead. Compared with BEV, HFCV based on by-product hydrogen from chlor-alkali process and renewable water electrolysis have the fossil fuel consumption reduction benefits. Regarding GHG emissions, HFCV based on water electrolysis using the renewable electricity performs the best with a value of 31 g CO2-eq/km while that based on on-site water electrolysis using grid electricity performs the worst with a value of 431 g CO2-eq/km in 2017. For air pollutants, HFCV based on all hydrogen pathways can achieve a significant reduction of VOCs and CO emissions on a WTW basis, in comparison with gasoline-ICEV in 2017. In terms of NOx, SOx, PM2.5 and PM10, HFCV based on on-site water electrolysis by grid electricity electrolysis has the highest emissions due to high emission factors of the electricity generation process. Moreover, due to increased share of renewable electricity and improvement in the fuel economy, reductions in WTW fossil fuel consumption and pollutants emissions are excepted by 2030. This study indicates the importance of hydrogen production when considering the energy and environment performance of HFCV to ensure a life cycle low carbon and air pollutants emissions.

Sulfidic mine tailings and marl waste rock as compatible resources in a microwave-assisted roasting process

Copper (Cu) is a popular commodity metal, and novel technologies are being developed to extract Cu from low-grade sources, such as sulfidic tailings. Roasting of tailings allows efficient Cu extraction and reduces environmental risks associated with tailing storage. However, conventional roasting is energy-intensive and releases harmful sulfur oxide gas (SOx). This study combines two mining wastes, sulfidic tailing and carbonate-rich waste rock (marl), in an energy-efficient microwave-assisted roasting step to simultaneously oxidize sulfide minerals and fixate formed SOx gas as sulfates. The roasting procedure was first optimized via conventional roasting (varying temperature, mixing ratio) by characterizing roasted materials (XRD/Rietveld, SEM-EDX, XRF, TGA-MS). Later, these optimized conditions were tested with microwave-assisted roasting. Subsequently, the influence of roasting treatments on Cu extraction was examined via ammoniacal leaching. Results showed that sulfate formation (SOx fixation) was highest for roasting at 500 °C via conventional roasting and increases with increasing marl content. Microwave-assisted roasting at 500 °C performs slightly below conventional roasting, as FeS2 was not fully oxidized. Marl addition negatively affects Cu extraction, likely because it limits the formation of water-soluble CuSO4. This study demonstrates the potential of mixing marl with tailings to control SOx emissions during roasting, but also shows limitations in terms of Cu extraction.

Environmental effects of emission control areas and reduced speed zones on container ship operation

To examine the dual environmental effects of emission control areas (ECAs) and reduced speed zones (RSZs), this study formulates an integrated container ship operation optimization model based on the fundamental facet of liner-service market. Capturing the critical characteristics of container ship operation, the proposed model explicitly incorporates the entire voyage that consists of container ship sailing and port activities as well as nonproductive stay in port. Compared to the separate establishment of ECAs, joint regulations of ECAs and RSZs can lead to more SOx emission reduction within it and less profit loss of the container ship by means of differentiated operation. Meanwhile, the optimal operation speed inside ECAs and RSZs of profit maximization is 10.638 knots, applied to the case study of CSCL Pacific Ocean, the container ship sailing MEX route from Far East (Shanghai, China) to Persian Gulf (Dammam, Saudi Arabia). These findings can provide insights for liner operators in carrying out differentiated operation from the demand side, as well as environmental regulators in adjusting emission reduction regulations dynamically.

Prediction of SOx–NOx emission from a coal-fired CFB power plant with machine learning: Plant data learned by deep neural network and least square support vector machine

The circulating fluidized bed boiler is an advanced clean energy technology that has received much attention in the power industry due to its fuel flexibility. In this study, a deep neural network with a modified early stopping algorithm and least square support vector machine were developed to predict SOx and NOx emissions associated with coal conversion in energy production. The models were trained on commercial plant data and the effect of dynamic coal and limestone properties (which is assumed constant in the literature) such as proximate analysis, ultimate analysis and particle size distribution on prediction accuracy were investigated. The results revealed that training the models without the assumptions improved the accuracy of the testing phase by at least 10% and 40% with a coefficient of efficiency of 0.8925 and 0.9904 for SOx and NOx respectively. In addition, interactive and pairwise correlation featuring were implemented which gave a maximum computational time reduction of 46.67% for NOx emission prediction. The developed models and findings can be applied not only for online operation and optimization of a coal-fired CFB boiler with high accuracy but also in the scale-up of power production at a low computational cost.

Crystal-to-Cocrystal Transformation as a Novel Approach for the Removal of Aromatic Sulfur Compounds from Fuels

Refractory aromatic sulfur compounds present in gasoline, diesel and jet fuels causes serious environmental problems and must be removed to minimize the emissions of SOx, according to environmental...

Desulfurization on Boron Nitride and Boron Nitride-based Materials.

Combustion of liquid fuels containing sulfur compounds is highly unfavorable due to the adverse effects caused by the resultant SOx emission. Consequently, catalytic and adsorptive materials having the capacity to eliminate the sulfur compounds from liquid fuels are very attractive. Hexagonal boron nitride (BN), with its interesting chemical and physical properties, finds applications in diverse fields, especially in energy and environmental applications. Recently, BN and BN-based materials have gained significant interest in emerging desulfurization processes such as oxidative desulfurization and adsorptive desulfurization. In this review, BN and BN-based materials are elaborately discussed in the context of their use in various desulfurization techniques. A brief description about the different desulfurization processes is provided at the outset. The relationship between the characteristics (the defects, morphology, porosity and surface area) of BN and desulfurization efficiency is also summarized. Furthermore, the mechanistic insights regarding the action of BN materials in the desulfurization processes are discussed. With this review, the synthetic strategies for designing the novel BN-based catalysts/adsorbents for the effective desulfurization of liquid fuels can be grasped.

Technology of Thermal Preparation of Coal for Ecologically Pure Combustion of Fuel in Small Boilers

The problems of ecologically clean coal combustion are connected with the need to reduce the formation of pollutants to the environment during thermal transformation of fuel. Currently, about 180-190 million tons of coal are burned in Russia to produce heat and electricity, with more than 60% in the eastern regions of the country. Most of the coal (about 80%) is consumed by large thermal stations, which are equipped with pollutant trapping systems. The remaining part is burned in numerous boiler houses that operate in both urban and rural areas to provide heat to social facilities and the population. The analysis shows that the role of boiler houses increases significantly in the territories with a low population or in remote and decentralized areas. In this regard, the coal pretreatment technology before burning including the thermal preparation of coal is important. The use of thermally prepared fuel (semi-coke) will significantly reduce emissions of NOx and SOx, as well as improve the “culture” of thermal energy production at small boilers by switching to fully automated technologies, as well as significantly reducing the financial burden of utilities by reducing the wage fund and emission fees.

Green Maritime Transport as a Part of Global Green Intermodal Chains

Environmental pollution is increasingly becoming a major global problem. Consequently, companies and policy makers are facing mounting pressure to reduce their impacts of logistics activities and make transport greener. The challenge to reduce the carbon intensity of maritime transport is even more important when we take into equation the fact that carries about 90% of the world trade. While car industry has already taken actions to greener cars, maritime industry is subject to fewer regulations and slower progress. This article overviews upcoming trends of green intermodal chains, initiatives in green maritime transport and how noteworthy is share of their impact in the transport chain as a whole. Speed reduction is one of most important measures which can be implemented right away with win-win impacting on environment and fuel cost. The study analysis environmental impacts of different services to eastern Adriatic ports, with special emphasis of slow steaming impacts on pollution level. The paper exposes that direct lines with bigger ships cause lower emissions of CO2, NOx and SOx and that with decisions of slow steaming the pollution level decreases significantly.

Comparative Economic Analysis on SOx Scrubber Operation for ECA Sailing Vessel

The IMO (International Maritime Organization) has mandated the restriction of SOx emissions to 0.5 % for all international sailing vessels since January 2020. And, a number of countries have designated emission control areas for stricter environmental regulations. Three representative methods have been suggested to cope with these regulations; using low-sulphur oil, installing a scrubber, or using LNG (Liquefied Natural Gas) as fuel. In this paper, economic analysis was performed by comparing the method of installing a scrubber with the method of using low-sulphur oil without installing additional equipment. We suggested plausible layouts and compared the pros and cons of different scrubber types for retrofitting. We selected an international sailing ship as the target vessel and estimated payback time and benefits based on navigation route, fuel consumption, and installation and operation costs. Two case of oil prices were analyzed considering the uncertainty of fuel oil price fluctuation. We found that the expected payback time of investment varies from 1 year to 3.5 years depending on the operation ratio of emission control areas and the fuel oil price change.