Experimental investigation and mathematical modelling of wood combustion in a moving grate boiler

An internally circulating fluidized bed (ICFB) was applied to investigate the behavior of chlorine and sulfur during cofiring RDF and coal. The pollutant emissions in the flue gas were measured by Fourier transform infrared (FTIR) spectrometry (Gasmet DX-3000). In the tests, the concentrations of the species CO, CO2, HCl, and SO2 were measured online. Results indicated when cofiring RDF and char, due to the higher content of chlorine in RDF, the formation of HCl significantly increases. The concentration Of SO2 is relatively low because alkaline metal in the fuel ash can absorb SO2. The concentration of CO emission during firing pure RDF is relatively higher and fluctuates sharply. With the CaO addition, the sulfur absorption by calcium quickly increases, and the desulfuration ratio is bigger than the dechlorination ratio. The chemical equilibrium method is applied to predict the behavior of chlorine. Results show that gaseous HCl emission increases with increasing RDF fraction, and gaseous KCl and NaCl formation might occur.

The paper presents the results of measurements of aerosol optical depth (AOD) and mass concentration of fine aerosols PM_2.5 and PM₁₀ in the coastal zone of Lake Baikal during summer of 2020. During period of high aerosol turbidity of the atmosphere, a relationship was revealed between variations in the spectral characteristics of the aerosol optical depth and the mass concentration of PM_2.5 and PM₁₀. With dense filling of the atmosphere with smoke aerosol from 10 to 14 August, a sharp increase in AOD (τ_0.5< 0.47) at st. Boyarsk to the absolute maximum on August 11 (τ_0.5< 0.57) was noted. At the same time, an increase in the mass concentrations of PM_2.5 (19-24 μg/m³) and PM₁₀ (42-59 μg/m₃) was recorded. The correlation coefficient between the mass concentration of PM₁₀ (PM_2.5) and AOD was 0.87 (0.86).

Incineration of kitchen waste with high nitrogen in vortexing fluidized-bed incinerator and its NO emission characteristics

Limits to Paris compatibility of CO2 capture and utilization

A deep learning approach to real-time CO concentration prediction at signalized intersection

Methane emitted from low-gas mines exhibits an extremely low concentration, and its direct release results in significant greenhouse effects and waste of resources. Fluidized-bed energy storage reactors enhance lean combustion limits, demonstrate superior fuel adaptability compared to conventional fixed-bed combustion technologies, and enable large-scale utilization of ultra-low concentration gas. Based on Fluidized-bed energy storage combustion technology, this study thoroughly investigates the influence mechanisms of multiple operating parameters, including bed temperature T0, intake air preheating temperature TP, fluidization velocity u 0, inlet methane concentration N[CH4]in, static bed packing height H, and catalyst mass fraction ω, on methane conversion efficiency. Furthermore, a five-factor, five-level orthogonal experiment was designed to determine the optimal experimental conditions for the fluidized combustion of ultra-low concentration methane. The results indicate that bed temperature is the most critical factor affecting CO emissions and methane conversion, with flue gas CO concentration first increasing and then decreasing with T0, while the effect of fluidization velocity and inlet methane concentration on methane conversion vary significantly under different T0 conditions, static bed height shows a negative correlation with methane conversion, and intake air preheating temperature exerts no significant effect on it. Additionally, the addition of Cu/γ-Al₂O₃ catalyst particles significantly lowers the required reaction temperature threshold, though the improvement in methane conversion efficiency is less than 10% when the catalyst mass fraction exceeds 10 wt%, and range analysis of the orthogonal experiment indicates that for methane conversion efficiency as the main evaluation index, the order of influence is T0 > u 0 > H > Tp > N[CH4]in, while for CO emission concentration as the main index, the order is T0 > N[CH4]in > u 0 > H > Tp. This study aims to systematically analyze the effects of multiple key operating parameters on exhaust emission characteristics and methane conversion efficiency during the treatment of ultra-low concentration gas, providing a theoretical basis and practical reference for the optimal design of operating parameters in large-scale industrial treatment systems.

Pilot-scale experimental and CFD modeling investigations of oxy-fuel combustion of Victorian brown coal

The occurrence and transport of dust storms and anthropogenic air pollutants in East Asia have been monitored using the meteorological satellite data of the National Oceanic and Atmospheric Administration (NOAA) and ground-based measurements at Cheongwon, a background observation site in central Korea. The nine cases, measured over 14 days, of natural dust particles caused by dust storms originating from northern China and Mongolia were observed at Cheongwon in the spring, autumn, and winter of 2010. In addition, seven cases, measured over 18 days, of anthropogenic dust particles originating from eastern China were observed over the course of a year. In those cases of natural and anthropogenic dust particles observed at Cheongwon, the level of particle matter (PM) with a diameter of ≤10 μm (PM10) (100 μgm−3 day−1) or PM2.5 (50 μgm−3 day−1) exceeded the air quality standards of Korea for 5 and 6 days, respectively. At the same time, CO concentrations rose higher due to long-range transport, while CO levels in the cases of anthropogenic dust particles (954 ppb) rose higher compared with the cases of natural dust particles (812 ppb). While gusty north–northwesterly winds were blowing in the front side of high-pressure systems, an increase in CO concentrations along with the influx of dust storms was observed at Cheongwon in the three natural dust particle cases with continental background airflow (n-CBAs). However, the other six natural dust particle cases with continental polluted airflow (n-CPAs) were also observed where mass concentrations of TSP, PM10 and PM2.5, and CO increased simultaneously after the CO concentrations rose and fell before dust storms had flowed in, showing double peaks. The mass concentrations of total suspended particle (TSP), PM10, and PM2.5 were high, and the PM2.5/TSP mass concentration ratio was high in n-CPAs, compared with n-CBAs. However, the anthropogenic dust particle cases with continental polluted airflow (a-CPA) are affected by air pollutants transported from eastern China by warm southwesterly winds, since central Korea is located in the rear side of the high-pressure system and in the foreside of the low-pressure system. Also, the anthropogenic dust particle cases with regionally polluted airflow (a-RPA) were observed in central Korea due to a stagnant high-pressure system for several days in the Yellow Sea region. In a-CPA, the mass concentrations of TSP, PM10, and PM2.5; the PM2.5/TSP mass concentration ratio; and the CO concentrations were all higher than in a-RPA.

Article 2 of the United Nations Framework Convention on Climate Change (UNFCCC) calls for stabilization of greenhouse gas (GHG) concentrations at levels that prevent dangerous anthropogenic interference (DAI) in the climate system. However, some of the recent policy literature has focused on dangerous climatic change (DCC) rather than on DAI. DAI is a set of increases in GHGs concentrations that has a non-negligible possibility of provoking changes in climate that in turn have a non-negligible possibility of causing unacceptable harm, including harm to one or more of ecosystems, food production systems, and sustainable socio-economic systems, whereas DCC is a change of climate that has actually occurred or is assumed to occur and that has a non-negligible possibility of causing unacceptable harm. If the goal of climate policy is to prevent DAI, then the determination of allowable GHG concentrations requires three inputs: the probability distribution function (pdf) for climate sensitivity, the pdf for the temperature change at which significant harm occurs, and the allowed probability (“risk”) of incurring harm previously deemed to be unacceptable. If the goal of climate policy is to prevent DCC, then one must know what the correct climate sensitivity is (along with the harm pdf and risk tolerance) in order to determine allowable GHG concentrations. DAI from elevated atmospheric CO2 also arises through its impact on ocean chemistry as the ocean absorbs CO2. The primary chemical impact is a reduction in the degree of supersaturation of ocean water with respect to calcium carbonate, the structural building material for coral and for calcareous phytoplankton at the base of the marine food chain. Here, the probability of significant harm (in particular, impacts violating the subsidiary conditions in Article 2 of the UNFCCC) is computed as a function of the ratio of total GHG radiative forcing to the radiative forcing for a CO2 doubling, using two alternative pdfs for climate sensitivity and three alternative pdfs for the harm temperature threshold. The allowable radiative forcing ratio depends on the probability of significant harm that is tolerated, and can be translated into allowable CO2 concentrations given some assumption concerning the future change in total non-CO2 GHG radiative forcing. If future non-CO2 GHG forcing is reduced to half of the present non-CO2 GHG forcing, then the allowable CO2 concentration is 290–430 ppmv for a 10% risk tolerance (depending on the chosen pdfs) and 300–500 ppmv for a 25% risk tolerance (assuming a pre-industrial CO2 concentration of 280 ppmv). For future non-CO2 GHG forcing frozen at the present value, and for a 10% risk threshold, the allowable CO2 concentration is 257–384 ppmv. The implications of these results are that (1) emissions of GHGs need to be reduced as quickly as possible, not in order to comply with the UNFCCC, but in order to minimize the extent and duration of non-compliance; (2) we do not have the luxury of trading off reductions in emissions of non-CO2 GHGs against smaller reductions in CO2 emissions, and (3) preparations should begin soon for the creation of negative CO2 emissions through the sequestration of biomass carbon.

Major US electric utility climate pledges have the potential to collectively reduce power sector emissions by one-third

Aerosol-based emission, solvent degradation, and corrosion in post combustion CO2 capture

Indoor air quality is essential, so its quality cannot be compromised. Hence, this research assessed indoor gaseous air pollutant concentrations from sources in thirty-three residential kitchens within the 4-zone of Ilorin-South Local Government, Kwara, Nigeria. The work focused on SO2, NO2, and CO emission concentration quantification, determination of the air quality index (AQI), estimation of health assessment risk, and deduced their health implications on the residents. The concentrations of NO2 and SO2 were determined by the Saltzman method using a Gilair-3 air sampler, while the concentration of CO was determined using an MSA Altair-5x multigas detector. Three types of eleven kitchen environments each (kitchens where liquefied petroleum gas (LPG), charcoal, and firewood were used as fuel sources) were considered. The concentrations of NO2, SO2, and CO were higher in kitchens that used charcoal and firewood. The major health risks were deduced in percentages from the questionnaire administered, where headaches had the highest percentage (20.7). The model indicated that the concentrations of the pollutants in the evening, irrespective of the sampling points, were higher than those in the morning. Firewood contributed significantly more than charcoal and LPG (p < 0.05). The results of the health assessment risk showed that the risk estimated for normal exposure to the pollutants in all the households studied revealed a hazard quotient of <1.0 except for SO2 from firewood for infants and children = 1.09. The AQI results showed the worst health conditions for households that used firewood (0.103–4.760 ppm NO2; 0.327–0.647 ppm SO2; and 12.30–57.83 ppm CO). The study concluded that the use of LPG should be preferred as a source of fuel for cooking.

The optimal design of a solvent based post combustion CO2 capture unit in a quicklime production plant is investigated. A 30 % weight aqueous monoethanolamine (MEA) solution is used as the absorption agent for the treatment of a 14 % mol CO2 flue gas stream. The objective function in the design optimization incorporates several equipment capacity and operating factors that have a direct impact on capital expenditure and energetic cost of the unit. A reliable and accurate equilibrium model is developed for the prediction of the process behavior. The model employs an orthogonal collocation on finite element formulation enabling structural flexibility for design purposes and efficient model reduction for computational facilitation. Nonlinear programming techniques are used for the identification of the optimal column configuration and the operating conditions. The ability of the optimally designed absorption/desorption column to achieve acceptable performance under varying separation operating conditions such as flue gas CO2 concentration, flowrate, and temperature is investigated.

Reduction of the CO emission from wood pellet small-scale boiler using model-based control

Iron ore sintering is a high-energy-consuming industry, and its high dependence on fossil fuels and the low concentration of CO in the sintering flue gas conceal the truth of the large total amount of CO emissions, which leads to the continuous emission of CO in the sintering flue gas has been harmful to the atmosphere and human health, and it is facing the great pressure of CO emission reduction. On the basis of commercially applied sintering technologies, the mechanism and characteristics of CO emission from sintering flue gas are discussed, and feasible ways to control CO emission in multiple aspects of source control, process emission reduction and end-of-pipe treatment are summarized. The core of source abatement is to reduce the fuel ratio, process abatement is to improve the combustion conditions of fuels to enhance the conversion rate of CO to CO2, and end-of-pipe treatment is to separate or oxidize CO to CO2 by physical or chemical means. Hydrogen sintering technology is the future development direction for source abatement, steam blowing sintering technology is introduced for process control, and catalytic oxidation technology has great prospects for removing CO from flue gas in end-of-pipe treatment. CO has great prospects, but efforts are needed to develop highly active catalysts with anti-poisoning and long-standing stability. Finally, feasible technical routes for sintering flue gas CO reduction and their challenges are analyzed, and a coordinated multifaceted control of source-process-end sintering technologies is proposed to achieve the goal of high-efficiency sintering flue gas CO reduction.