Reduction Of SO2 Emissions Research Articles

Study on the emission characteristics of VOCs under the condition of biomass blending combustion

In order to understand the emission characteristics of volatile organic compounds (VOCs) in the flue gas under the mixed combustion of biomass, the study on the emission characteristics of VOCs in the flue gas was carried out on a 58 MW circulating fluidized bed (CFB) unit. The results show that the co-firing of biomass can significantly reduce the emissions of VOCs and NOx and SO2. Changes in blended fuel particle size and combustion temperature reduce VOCs emissions. The most obvious change in the emission reduction of VOCs is reflected in the increase of the biomass mixing ratio from 20 % to 30 %. Biomass contains less S and N elements is the reason for the reduction of NOx and SO2 emissions. The emission of pollutants such as VOCs was the lowest when the biomass blending ratio was 40 %. Based on the actual operation of the power plant, 30 % is the optimal mixing ratio. The analysis showed that the amount of VOCs components had a strong positive correlation with the proportion of biomass in the fuel. The emission of VOCs under the condition of biomass blending has different characteristics from coal-fired boilers and biomass boilers. Under the two different mixing ratios, benzene series accounted for the largest proportion of VOCs emissions, reaching 44.38 % (20 %) and 33.75 % (40 %), respectively. The emission of benzene series is dominated by benzene and toluene, the emission of alkanes is dominated by n-hexane, and the emission of esters is dominated by ethyl acetate. The ozone formation potential (OFP) was analyzed by the maximum incremental reactivity method. The contribution of ozone generation potential at 20 % and 40 % mixing ratios was mainly from benzene series, which contributed 69.88 % and 70.24 %, respectively, and alkanes. contribution can also account for 25.76 % and 17.75 %.

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.

Experimental study on a concentrating solar photovoltaic/thermal system using different fluid spectral beam filters

Spectral splitting photovoltaic/thermal technology is the leading field in the area of extremely efficient utilization of solar energy. Due to its complexity, experimental research on spectral splitting photovoltaic/thermal devices is relatively limited, mainly focusing on the laboratory scale energy efficiency test or calculation process verification. These studies do not provide intuitionistic guidance for the actual operation of engineering systems. In this paper, a fluid filter-based compound parabolic concentrator solar photovoltaic/thermal system with engineering application dimensions is designed and experimentally studied under actual outdoor environments. Different fluid filters are prepared and used to regulate the spectral splitting characteristics of the proposed system, including the deionized water, silver/water nanofluids and silver-cobalt sulfate/water nanofluids. When the environmental parameters are relatively stable, the method of adjusting the composition of the fluid filter is used to obtain the dynamic operating characteristics of the system. The results show that silver nanoparticles and cobalt sulfate can improve the spectral absorptivity of the deionized water. Compared with the deionized water, when the silver/water nanofluids is used as the fluid filter, the thermal efficiency of the system increases, the electric efficiency and overall exergy efficiency of the system both decrease, and the three efficiencies are 56.0%, 8.5% and 19.6%, while for the silver-cobalt sulfate/water nanofluids, the efficiencies are 58.0% 8.0% and 20.0%. Moreover, the results reveal that for the photovoltaic/thermal system with a low solar concentration ratio, by enhancing the absorptivity of the fluid filter, the fill factor of the photovoltaic module can increase, but the output electric power will decrease. When the silver-cobalt sulfate/water nanofluids is used, the fill factor and maximum output power of the proposed system are 0.633 and 69.2 W. For a unit consisting of four sets of the proposed photovoltaic/thermal systems, the emission reductions of CO2, NOx, SO2 and dust for the whole lifetime are approximately 7794.19 kg, 181.48 kg, 191.95 kg and 111.68 kg, respectively.

Variability of sulfur and oxygen isotope values within wet precipitation and its correlation with diminished anthropogenic sulfur dioxide (SO2) emission

Atmospheric sulfate (SO42−) aerosols have the capacity to scatter solar radiation, thus exerting a cooling effect on the climate. It is widely acknowledged that SO42− deposition significantly contributes to ecosystem effect in aquatic and terrestrial environments worldwide. Over the course of several decades, considerable efforts have been undertaken to mitigate anthropogenic sulfur dioxide (SO2) emissions in China, leading to remarkably low SO2 concentrations. Nevertheless, the implications of reduced anthropogenic SO2 emission on atmospheric sulfate transformation and compositions of isotope values (δ34S-SO42–, δ18O-SO42–) remain inadequately understood. To address this knowledge gap, we conducted multiple rainfall sampling instances between 2010 and 2022 (n = 191), encompassing the period of transitioning anthropogenic SO2 emission from high to low levels. Remarkably, we observed a significant reduction in the volume-weighted mean value (VWMV) of SO42− concentrations, declining from 20.86 mg L−1 in 2010 to 2.41 mg L−1 in 2022, and the VWMV of SO42−/NO3− molar ratios also decreased from 12.90 in 2010 to 0.55 in 2022, reflecting the synchronously decreasing annual SO2 emissions and annual SO2 concentrations from 2010 to 2022. In contrast to the declining trends in VWMV of SO42− concentrations, the VWMV of δ34S-SO42– values exhibited a different pattern from 6.6‰ in 2010 to −0.1‰ in 2017 and slightly increased to 2.5‰ in 2022. Furthermore, the VWMV of δ18O-SO42– values demonstrated an increase from 8.8‰ in 2010 to 14.5‰ in 2018, but subsequently decreased to 5.4‰ in 2022. We attributed the sharply dropping VWMV of δ34S-SO42– values to the reduction in the input of primary sulfate with enriched δ34S-SO42– values. The strict desulfurization reduced SO2 emissions, leading to oxidation of these trace SO2 with negative δ34S values, resulting in low sulfate concentrations and negative δ34S-SO42– values. In addition, the monthly average δ18O-SO42– values exhibited a positive correlation with monthly mean δ18O-H2O values (p < 0.05), strongly indicating the water incorporation during SO2 heterogeneous oxidation. More importantly, during spring rainfall, positive δ18O-SO42– values but relatively negative δ34S-SO42– values were influenced by SO2 heterogeneous oxidation facilitated by air oxygen catalyzed under metal ions in dry weather condition, attributed to the low relative humidity (RH) coupled with high deuterium excess (dexcess) values. Conversely, in summer, negative δ18O-SO42– values but relatively positive δ34S-SO42– values resulted from the SO2 heterogeneous oxidation with H2O2 due to high RH and low dexcess values. Moreover, the VWMV of δ18O-H2O exhibited variations from −3.7‰ in 2019 to −9.7‰ in 2021, and displayed a positive correlation with annual temperature (p < 0.01) and a negative correlation with annual precipitation (p < 0.05), making it a valuable indicator of climate change alongside δ18O-SO42– values. Our findings underscore the importance of continued monitoring of atmospheric wet depositions in response to changes in anthropogenic SO2 emission activities. Furthermore, they highlight the substantial impact of variations in δ34S values of SO2 and primary sulfate on rainwater sulfate concentrations and isotope values.

Energy, exergy, economic and environmental assessment of solar photovoltaic direct-drive refrigeration system for electronic device cooling

The cooling systems dissipate the high heat flux of miniaturized and highly integrated electronic devices in order to keep the temperature of the electronic devices within acceptable limits. In this paper, a solar photovoltaic direct-drive refrigeration system with an embedded direct evaporator was designed and tested under different conditions. An energy, exergy, economic and environmental analysis was used to investigate and assess the performance of the presented system based on the experimental data. The results indicate that the highest COP of the proposed system is 8.5 at the compressor speed of 4350 rpm. When the average solar radiation intensity is 776.5 W/m2, the photovoltaic cells generate 1.81 kW h of electricity, where 24.9% of electricity is consumed on the proposed system. The PV cells and compressor need be improved in term of their large exergy destruction (1059.4 W, 86.3 W) and low exergy efficiency (24.9%, 26.8%). The exergy performance of equipment and VCR subsystem is more sensitive to the compressor speed than the heating power. The exergy efficiency of the VCR subsystem reduced by 48.4 %. The payback period is 2.2 years, and the reductions of CO2, SO2 and NOx emissions are 395.1 kg, 11.9 kg and 5.9 kg, respectively.

Assessing transboundary air pollution and joint prevention control policies: evidence from China

This study addresses the pressing issue of transboundary air pollution, an environmental concern characterised by the dispersion of pollutants across administrative boundaries. Prior research in this area has lacked an in-depth examination of the efficacy of cooperative environmental policies in managing this challenge. To address this gap, our study first evaluates transboundary sulphur dioxide pollution across 31 provinces in China from 2005 to 2020 utilising the Hybrid Single-Particle Lagrangian Integrated Trajectory model. Following this, we apply a staggered Difference-in-Difference model to gauge the impact of the joint air pollution prevention and control policies adopted by China for high-priority provinces. Our analysis revealed an imbalance in emissions and transboundary pollution levels across provinces. Provinces such as Shandong, Shanxi, and Tianjin face the most severe transboundary SO2 pollution, whereas the highest SO2 emissions were noted in Shandong, Inner Mongolia, and Hebei. The implementation of the joint pollution prevention and control policy resulted in a significant reduction in SO2 emissions and transboundary SO2 pollution by factors of 10.60 and 9.70, respectively, when compared to other provinces. These findings provide valuable insights for shaping environmental cooperation policies and identifying priority provinces for mitigating air pollution.

Modeling the effects of speed limit cameras (SLCs) on air quality and traffic flow on access-controlled highways

The impact of speed limit cameras (SLCs) on speed limit enforcement and traffic safety has long been studied. However, the effects of SLCs on air quality have not been thoroughly investigated due to the lack of data at sites where both air quality and traffic flow measurements (such as speed and volume) are monitored in close proximity to SLCs. This study aims to quantify the effect of SLCs on air quality and traffic flow parameters on access-controlled highways using linear regression models (LRM) and generalized additive models (GAM). The latter allows the modeling of nonlinear functional relationships between the predictor and outcome variables. We collected experimental data, including traffic flow parameters, weather conditions, and air pollutants (CO, CO2, NO2, SO2, and VOC), on high-volume, high-speed access-controlled highways in the wider metropolitan area of Dammam, Saudi Arabia. Key parameters related to traffic, such as volume, speed, percentage of heavy-duty vehicles (HDV), and percentage of traffic exceeding the speed limit, were used to estimate air pollutant generation from vehicular exhaust emissions near highway locations. Our analysis of the collected data revealed that locations with SLCs showed higher adherence to the speed limit of 120 km/h. The 85th percentile speed at these sites was approximately 114 km/h, which was 11 percent lower than that at the no-camera sites. Additionally, field data demonstrated a significant reduction in CO and SO2 emissions at the camera locations by approximately 23.7 and 20.3 percent, respectively. However, at these locations, the CO2, NO2, and VOC gas concentrations increased slightly, ranging from 1.5 to 4.9 percent. The predictive capabilities of the GAMs for gas emissions were higher than those of the LRMs, except for CO2 emissions. The GAM results identified optimal speed values between 110 km/h and 130 km/h to minimize vehicle emissions. Furthermore, the GAM results indicated that SLC locations had significantly lower concentrations of exhaust gas emissions for CO, SO2, and VOC, but higher levels of CO2 and NO2 gases. Thus, the field data and GAM results were in agreement for all gases except VOC. These findings have implications for shaping environmental transportation policies and guidelines, highlighting the multifaceted impact of SLCs on both traffic behavior and air quality.

Characterization and sources of water-soluble inorganic ions during sulfate-driven and nitrate-driven haze on the largest loess accumulation plateau

With the rapid reduction of anthropogenic SO2 emissions, the critical driver of haze in China has shifted from being dominated by sulfate to alternating sulfate and nitrate. Haze induced by different driver species may differ in the chemical forms of water-soluble inorganic ions (WSIIs). The unique topography and high-emission industrial agglomeration of the Loess Plateau determine its severe local PM2.5 pollution and influence global weather patterns through the outward export of pollutants. PM2.5 samples were conducted in Pingyao, on the eastern Loess Plateau of China, in autumn and winter. The average mass of PM2.5 was 88.82 ± 57.37 μg/m3; sulfate, nitrate, and ammonium were the dominant component. The chemical form of the ion was dominated by (NH4)2SO4, NH4NO3, NaNO3 and KNO3 during the nitrate-driven (ND) haze, while (NH4)2SO4, NH4HSO4, NH4NO3, NaNO3 and KNO3 were predominant species during the sulfate-driven (SD) haze. Heterogeneous oxidation reactions dominated the mechanism of sulfate formation. Primary sulfate emissions or other generation pathways contributed to sulfate formation during the SD haze. The gas-phase homogeneous reaction of NO2 and NH3 dominates the nitrate generation during the ND haze. The heterogeneous reactions also played an essential role during the SD haze. Nitrate aerosol (42.30%) and coal and biomass combustion (23.23%) were the dominant sources of WSIIs during the ND haze. In comparison, nitrate aerosol (31.80%) and sulfate aerosol (25.08%) were considered the primary control direction during the SD haze. The chemical characteristics and sources of aerosols under various types of haze differ significantly, and knowledge gained from this investigation provides insight into the causes of heavy haze.

Analysis of SO2 Emission Reduction Effect of Smart City Construction Based on a Multi-period DID Model

Along with the acceleration of urbanization and industrialization, the problem of environmental pollution in China has become increasingly prominent, putting forward new requirements for city construction. In 2012, the Chinese government proposed to build smart cities. This policy not only strengthened the urban informatization construction, but also provided valid solutions for China's environmental governance. However, there is little literature about the effect of smart city construction on pollution emission. Based on this, this paper used panel data from 284 cities in China during 2003–2019 to evaluate the effect of smart city construction on SO2 emissions by constructing a multi-period DID model. The findings are as follows: (1) The smart city construction could significantly reduce the emission of SO2 and the conclusion was robust. (2) There was a temporal hysteresis in the response of SO2 emissions to the smart city construction, and SO2 emissions began to decrease significantly in the third year after smart city construction. (3) Industrialization could significantly increase SO2 emissions, while opening up to the outside world and the concentration of population could significantly decrease SO2 emissions.

Revisiting the dynamics of gaseous ammonia and ammonium aerosols during the COVID-19 lockdown in urban Beijing using machine learning models

The concentration of atmospheric ammonia (NH3) in urban Beijing substantially decreased during the COVID-19 lockdown (24 January to 3 March 2020), likely due to the reduced human activities. However, quantifying the impact of anthropogenic interventions on NH3 dynamics is challenging, as both meteorology and chemistry mask the real changes in observed NH3 concentrations. Here, we applied machine learning techniques based on random forest models to decouple the impacts of meteorology and emission changes on the gaseous NH3 and ammonium aerosol (NH4+) concentrations in Beijing during the lockdown. Our results showed that the meteorological conditions were unfavorable during the lockdown and tended to cause an increase of 8.4 % in the NH3 concentration. In addition, significant reductions in NOx and SO2 emissions could also elevate NH3 concentrations by favoring NH3 gas-phase partitioning. However, the observed NH3 concentration significantly decreased by 35.9 % during the lockdown, indicating a significant reduction in emissions or enhanced chemical sinks. Rapid gas-to-particle conversion was indeed found during the lockdown. Thus, the observed reduced NH3 concentrations could be partially explained by the enhanced transformation into NH4+. Therefore, the sum of NH3 and NH4+ (collectively, NHx) is a more reliable tracer than NH3 or NH4+ alone to estimate the changes in NH3 emissions. Compared to that under the scenario without lockdowns, the NHx concentration decreased by 26.4 %. We considered that this decrease represents the real decrease in NH3 emissions in Beijing due to the lockdown measures, which was less of a decrease than that based on NH3 only (35.9 %). This study highlights the importance of considering chemical sinks in the atmosphere when applying machine learning techniques to link the concentrations of reactive species with their emissions.

Intertemporal environmental efficiency assessment in China: A new network-based dynamic super-efficiency measure.

In order to make a complete ranking of intertemporal environmental efficiency in a dynamic manner, this paper combines the network-based dynamic data envelopment analysis (DEA), super-efficiency with the unified efficiency under natural and managerial disposability, and designs a dynamic DEA model and the corresponding dynamic super-efficiency DEA model. Compared with previous studies, the proposed measure can fully rank the overall environmental efficiency of all decision making units (DMUs) in a dynamic manner, and more importantly, it provides the information about when and what factors lead to inefficiency or efficiency of DMUs. The proposed models are applied to examine the environmental efficiency of 30 provinces in China from 2008 to 2017. The results show that there are significant regional differences of environmental efficiency in China. In addition, slack analysis shows that most eastern efficient provinces have no obvious advantages in energy consumption, labor and waste water emission; most central and western efficient provinces have no advantages in sulfur dioxide (SO2) emissions and GDP. To improve overall efficiency, eastern inefficient provinces should mainly focus on reducing energy consumption, SO2 emissions and labor, and increasing capital investment in right years, central and western inefficient provinces can focus on reducing SO2 emissions and labor in most years, most of provinces need to increase gross domestic capital formation.

The abatement effect of total emission control policy: Evidence from China

The Total Emission Control (TEC) policy has been implemented in China for >20 years and plays a pivotal role in China's environmental governance system. Given the current reality of prominent environmental issues in China, there is ongoing controversy regarding whether the TEC policy has effectively reduced pollution as desired. Inspired by this, this paper takes the TEC policy implemented in the 11th Five Year Plan as an example, and based on the manually collected city-level SO2 emission reduction targets, we construct a difference-in-differences evaluation framework to investigate the abatement effect of the TEC policy. The results demonstrate a significant reduction in SO2 emissions resulting from the implementation of the TEC policy. A series of identification tests verify the robustness of the findings. The mechanism analysis shows that the end-of-pipe treatment and cleaner production are important channels to achieve the abatement effect, while the scale effect is deemed insignificant. Heterogeneity analysis shows that the policy effect varies significantly across different types of firms and regions. The conclusions contribute not only to a comprehensive understanding of the TEC policy, but also provide an important practical value for building a modern pollution control system and promoting the construction of ecological civilization.

Does a mandatory cleaner production audit have a synergistic effect on reducing pollution and carbon emissions?

The mandatory cleaner production audit (MCPA) is an important initiative to promote energy conservation, emission reduction and green transformation and upgrading of enterprises. This paper matches 16,841 enterprises that implemented MCPA between 2003 and 2012 to the Chinese Industrial Enterprise Database and the Chinese Enterprise Pollution Emission Database. And carrying out the MCPA as a quasi-natural experiment, a difference-in-differences model based on propensity score matching is used to identify the net effect of it on the reduction of enterprise sulfur dioxide (SO2) emissions. The paper discovers that MCPA can significantly reduce the intensity of SO2 emissions, and this finding is robust to multiple scenarios. According to heterogeneity analysis, the MCPA is more conducive to reducing the intensity of SO2 emissions in domestic enterprises, enterprises with low financing constraints and heavily polluting industries. Mechanism tests show that MCPA can reduce SO2 emissions by optimising energy structure, increasing energy efficiency, and encouraging green process innovation. Further analysis reveals that the MCPA is an effective tool for achieving the synergistic effect of reducing SO2 and carbon dioxide (CO2) emissions in enterprises, and it serves the dual function of winning the pollution battle while also achieving the carbon peaking and carbon neutrality goals.

Separation of sulfur compounds from petroleum using hydrodesulfurization method to reduce SO2 emission: Process optimization and validation

Preparation of clean fuels from petroleum need decent removal of sulfur compounds from the petroleum which can be done using the well-known hydrodesulfurization (HDS) method. The removal of sulfur compounds from crude oil would be essential in order to control the emission of gas pollutants such as SO2. However, due to the complexity of the sulfur separation process, predictive modeling and computations are required to improve the separation efficiency. In this research, we have collected some experimental data for optimization of separation process. Each data point has four input features: temperature, pressure, initial sulfur content, and dose. On the other hand, the outputs included left sulfur amount in the feed, value of SO2 emission, and process cost ($). Adaboost technique integrated with three core models of DT, Lasso, and KNN is used for modeling. The models are tuned using LOA method on the available dataset, thereby the optimum models’ parameters were determined for the best fitting. For sulfur concentration and emission parameters, the ADA-DT technique is the best one among other methods, but for the HDS cost, the ADA-LASSO framework works the best. Using these models, the R2-score for outputs is, respectively, 0.940, 0.923, and 0.999. This work makes significant contributions by providing accurate predictive models that would enhance the understanding and optimization of sulfur separation process. These models pave the way for more efficient and environmentally-friendly production of clean fuels from petroleum, contributing to reduced gas pollutants emissions.

Anthropogenic amplification of biogenic secondary organic aerosol production

Abstract. Biogenic secondary organic aerosols (SOAs) contribute to a large fraction of fine aerosols globally, impacting air quality and climate. The formation of biogenic SOA depends on not only emissions of biogenic volatile organic compounds (BVOCs) but also anthropogenic pollutants including primary organic aerosol, sulfur dioxide (SO2), and nitrogen oxides (NOx). However, the anthropogenic impact on biogenic SOA production (AIBS) remains unclear. Here we use the decadal trend and variability in observed organic aerosol (OA) in the southeast US, combined with a global chemistry–climate model, to better constrain AIBS. We show that the reduction in SO2 emissions can only explain 40 % of the decreasing decadal trend of OA in this region, constrained by the low summertime month-to-month variability in surface OA. We hypothesize that the rest of the OA decreasing trend is largely due to a reduction in NOx emissions. By implementing a scheme for monoterpene SOA with enhanced sensitivity to NOx, our model can reproduce the decadal trend and variability in OA in this region. Extending to a centennial scale, our model shows that global SOA production increases by 36 % despite BVOC reductions from the preindustrial period to the present day, largely amplified by AIBS. Our work suggests a strong coupling between anthropogenic and biogenic emissions in biogenic SOA production that is missing from current climate models.

Beyond particulate matter: New evidence on the causal effects of air pollution on mortality

The increasing demand for electricity worldwide has caused a corresponding rise in the consumption of coal, leading to an increase in sulfur dioxide (SO2) pollution levels. Despite the severity of the issue, there is a lack of conclusive evidence establishing a causal link between SO2 pollution and health, particularly in developing countries. We leverage a large national environmental regulation policy, implemented in China to reduce SO2 emissions, to estimate the impacts of SO2 pollution on mortality. We find that 1-μg/m3 reduction in SO2 concentrations leads to 18 fewer cardiovascular deaths per 100,000 people aged 60 years and above (0.9% decrease) and 2 fewer deaths per 100,000 children under the age of 5 (1.5% decrease) annually. A back-of-the-envelope calculation suggests that the total health benefits of the environmental policy outweigh its economic costs. The results are consistent across various robustness checks.

Energy, exergy, sustainability and environmental emission analysis of coal-fired thermal power plant

Exergy analysis has recently gained importance in understanding process control and mechanism. Above-mentioned approach is detrimental in dealing with today’s stringent policies in energy security, saving, reclamation through various strategies. The current investigation is an integrated coal-fired thermal power plant, from which one-unit processes at 210 MW. Through the energy analysis, about 64.24% of the total energy loss in the installed condenser is the major equipment for energy destruction. From the evaluated exergy analysis, the major equipment, the boiler in the overall plant, has exergy destruction of 88.91%. From sustainability analysis infers that the generation system's high depletion number corresponds to a low SI between 1.546 and 1.594. With an increase in environment temperature from 25 °C to 45 °C, reduction of coal consumption and ash generation per unit fuel increases from 19.01 to 21.05 kg/h. Also, CO2 and SO2 emission reduction increases from 35.03 and 0.213 to 38.79 and 0.236 kg/h.

Transient simulation of SO2 absorption into water in a bubbling reactor

A bubbling reactor is an important type of gas scrubber to reduce SO2 emissions in maritime shipping. Both experiments and simulations were conducted to study the relationship between the periodic gas bubbling process and SO2 concentration at the outlet of the reactor, and the entrainment of liquid droplets on SO2 absorption. The accuracy of the model was verified by comparing the bubble size, the depth of bubbles injected into the water, and the SO2 concentration obtained in both experiments and simulations. The gas bubbling process is accompanied by bubble formation, rise, and collapse. The gas bubbling period is affected by the disturbance of the liquid level. The period of the SO2 concentration at the outlet of the gas bubbling reactor is smaller than that at the gas jar outlet which acts as the gas buffering region. The amounts of water carried out of the bubbling reactor by the gas bubbling process increase with the gas flow rates. The droplets and liquid film in the gas jar and the connecting tube play an important role in the absorption of SO2. This study encourages more research to reduce the fluctuation of SO2 concentration and consider droplet entrainment in the design of bubbling reactors.

Optimum design of a deep cooling tower for waste heat and water recovery from humid flue gas

In order to efficiently recover the waste heat and gaseous water from humid flue gas, a deep cooling tower was designed to explore the heat and mass transfer performance, we optimized the design of tower equipment and absorption heat pump system. The running resistance of total tower is less than 240 Pa, the structured packing can reach the maximum heat transfer power under liquid to gas ratio of 3.5 L/Nm3, 3.0 L/Nm3 and 2.5 L/Nm3, respectively. Under gas velocity of 2.5 m/s, the heat transfer capacity is 54.1–149.2 W m−2 K−1, mass transfer capacity is 0.72–2.02 g m−2 s−1. The coefficient of performance of absorption heat pump can reach 1.71, for a 140 MW boiler, the energy recovery capacity can reach 24 MW and the water recovery capacity can reach 34 m3/h, the emission reductions of CO2, dust, SO2 and NOx can reach 7324 kg/h, 1992 kg/h, 219 kg/h and 109 kg/h, respectively.

Clean Preparation of Formed Coke from Semi-coke by the Carbonated Consolidation Process.

In order to address the low thermal efficiency of low-rank coal combustion and the accompanying serious environmental issues, formed coke was prepared using a carbonization consolidation method with low-rank coal semi-coke. The test for briquetting and carbonation consolidation conditions revealed that the optimal parameters were a briquetting pressure of 93.63 MPa, moisture content of 16%, Ca(OH)2 binder amount of 10%, and a CO2 concentration of 30% at 20 °C. Under these conditions and a carbonation consolidation time of 60 min, high-quality formed coke was produced, exhibiting a compressive strength of 1256.2 N/a, redrying strength of 286.2 N/a, and a dropping strength of 10.6 number/a. The combustion characteristics of the prepared formed coke were investigated, revealing that ignition temperatures (345.39 °C), burnout temperatures (495.57 °C), and peak of the maximum weight loss rate temperatures (437.93 °C) are slightly higher than those of bituminous coal. The low calorific value of the briquette was 20.4 MJ/kg. During the combustion process, the emission concentrations of SO2, NOX, and solid particles from the formed coke were significantly lower than those of bituminous coal, indicating that it is a cleaner energy source. Moreover, adding Ca(OH)2 effectively reduced SO2 emissions and achieved sulfur fixation and emission reduction.