Magnetic γ-Fe2O3-Loaded Attapulgite Sorbent for Hg0 Removal in Coal-Fired Flue Gas

A magnetically recoverable composite mercury removal sorbent was produced by introducing magnetic γ-Fe2O3 into attapulgite (ATT) (xFe1ATT) via the co-precipitation method and used to remove Hg0 in the simulated coal-fired power plant flue gas. The as-prepared 0.5Fe1ATT sorbent was characterized by X-ray diffraction, Brunauer–Emmett–Teller, transmission electron microscopy, vibrating sample magnetometer, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy analyses. The results showed that the Hg0 removal performance of the composite of γ-Fe2O3 and ATT was significantly promoted in comparison to pure γ-Fe2O3 and ATT individually. A relatively high magnetization value and good Hg0 removal performance were obtained by the sample of 0.5Fe1ATT. O2 could enhance Hg0 removal activity via the Mars–Maessen mechanism. NO displayed a significant promotion effect on Hg0 removal as a result of the formation of active species, such as NO2 and NO+. SO2 inhibited the removal of Hg0 as a result of its competition adsorption against Hg0 for the active sites and the sulfation of the sorbent. However, the introduction of NO could obviously alleviate the adverse effect of SO2 on the Hg0 removal capability. H2O showed a prohibitive effect on Hg0 removal as a result of its competition with Hg0 for the active sites. The findings of this study are of fundamental importance to the development of efficient and economic magnetic mercury sorbents for Hg0 removal from coal-fired boiler flue gases

Prediction of Rice Husk Gasification on Fluidized Bed Gasifier Based on Aspen Plus

A biomass gasification model was developed using Aspen Plus based on the Gibbs free energy minimization method. This model aims to predict and analyze the biomass gasification process using the blocks of the RGibbs reactor and the RYield reactor. The model was modified by the incomplete equilibrium of the RGibbs reactor to match the real processes that take place in a rice husk gasifier. The model was verified and validated, and the effects of gasification temperature, gasification pressure, and equivalence ratio (ER) on the gas component composition, gas yield, and gasification efficiency were studied on the basis of the Aspen Plus simulation. An increasing gasification temperature was shown to be conducive to the concentrations of H2 and CO, and gas yield and gasification efficiency reached peaks of 2.09 m3/kg and 83.56%, respectively, at 700 °C. Pressurized conditions were conducive to the formation of CH4 and rapidly increased the calorific value of syngas as the gasification pressure increased from 0.1 to 5 MPa. In addition, the optimal ER for gasification is approximately 0.3, when the concentrations of H2 and CO and the gasification efficiency reach peaks of 23.65%, 24.93% and 85.92%, respectively

Investigation of elemental mercury removal from coal-fired flue gas over MIL101-Cr

In this work, the MIL101-Cr sorbent with a large BET surface area was prepared and used to remove Hg0 from the simulated coal-fired boiler flue gas. The chemical and physical properties of the prepared sorbent were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and X-ray photoelectron spectroscopy (XPS). A range of experiments was conducted in a fixed-bed reactor to investigate the effects of reaction temperature, Hg0 inlet concentration, gas hourly space velocity (GHSV) and flue gas composition on the Hg0 removal for the prepared sorbent. The mechanisms and kinetics of the Hg0 adsorption were also studied. The results showed that the MIL101-Cr sorbent achieved the Hg0 removal efficiency of more than 85% for 4 h at 200 oC under the condition of a relatively high Hg0 inlet concentration (203 μg/m3) and large GHSV (8 105 h-1). The O2 in the flue gas was found to be beneficial to Hg0 removal. The NO in the flue gas favoured Hg0 removal both in the presence and absence of O2. The SO2 in the flue gas notably inhibited Hg0 adsorption in the absence of O2, whereas a low concentration of SO2 slightly inhibited Hg0 removal in the presence of O2. However, high concentrations of SO2 in the flue gas still significantly weakened the Hg0 removal ability even in the presence of O2 due to the competitive adsorption of SO2 with Hg0 on the sorbent and the sulfation of the sorbent. A simultaneous presence of O2 and NO in the flue gas could overcome the adverse impact of SO2 on the Hg0 adsorption. The H2O in the flue gas could have a minor influence on Hg0 removal as a result of the competitive adsorptions between Hg0 and H2O. The XPS analysis indicated that the surface Cr3+, oxygen species and C=O group in MIL101-Cr acted as the active adsorption/oxidation sites for Hg0. The Hg0 removal by MIL101-Cr belonged to chemisorption and could be described by the pseudo-second-order model. The equilibrium adsorption capacity calculated for the sorbent amounted to 25656 μg/g at 200 oC, which indicated that MIL101-Cr could be used as a promising sorbent to remove Hg0 from coal-fired boiler flue gases

Emergy analysis for transportation fuels produced from corn stover in China

In order to provide more useful information for the decision makers in China to implement sustainable energy policies and to identify which region in China is most suitable to build the biofuel production plants for fast pyrolysis and hydroprocessing of corn stover, the present study has evaluated the production efficiency and sustainability of large-scale transportation fuel production via fast pyrolysis and hydroprocessing of corn stover in China using emergy analysis approach. Both the hydrogen production scenario (i.e. oil hydroprocessing using the hydrogen derived from bio-oil reforming) and the hydrogen purchase scenario (i.e. oil hydroprocessing using the hydrogen purchased from market) in three regions of China (Northeast China Plain (NECP), North China Plain (NCP) and Shaanxi Province (SXP)) have been investigated. The results have shown that maize production, and fast pyrolysis and hydroprocessing are the two biggest emergy input stages of the biofuel production system. The comparison of the emergy indices of all of the six cases investigated indicates that the hydrogen purchase scenario in NCP is the best biofuel production case due to its second best sustainability and the second highest production efficiency. In comparison to bioethanol from cassava chips and wheat and biodiesel from jatropha curcas L, the hydrogen purchase scenario in NCP is also the most sustainable plan for a biofuel production plant in China. As water, fertilizer and hydrogen are the three biggest emergy inputs in this case, improvements on the water management, fertilizer management and hydrogen production technology have been discussed. In order to further increase the efficiency and sustainability of the hydrogen purchase scenario in NCP, some of the necessary efforts required from the relevant sectors have also been put forward based on the results of the emergy analysis

Exertional heat stroke-induced changes in gut microbiota cause cognitive impairment in mice

Abstract Background The incidence of exertional heat stroke (EHS) escalates during periods of elevated temperatures, potentially leading to persistent cognitive impairment postrecovery. Currently, effective prophylactic or therapeutic measures against EHS are nonexistent. Methods The selection of days 14 and 23 postinduction for detailed examination was guided by TEM of neuronal cells and HE staining of intestinal villi and the hippocampal regions. Fecal specimens from the ileum and cecum at these designated times were analyzed for changes in gut microbiota and metabolic products. Bioinformatic analyses facilitated the identification of pivotal microbial species and metabolites. The influence of supplementing these identified microorganisms on behavioral outcomes and the expression of functional proteins within the hippocampus was subsequently assessed. Results TEM analyses of neurons, coupled with HE staining of intestinal villi and the hippocampal region, indicated substantial recovery in intestinal morphology and neuronal injury on Day 14, indicating this time point for subsequent microbial and metabolomic analyses. Notably, a reduction in the Lactobacillaceae family, particularly Lactobacillus murinus, was observed. Functional annotation of 16S rDNA sequences suggested diminished lipid metabolism and glycan biosynthesis and metabolism in EHS models. Mice receiving this intervention (EHS + probiotics group) exhibited markedly reduced cognitive impairment and increased expression of BDNF/TrKB pathway molecules in the hippocampus during behavioral assessment on Day 28. Conclusion Probiotic supplementation, specifically with Lactobacillus spp., appears to mitigate EHS-induced cognitive impairment, potentially through the modulation of the BDNF/TrKB signaling pathway within the hippocampus, illustrating the therapeutic potential of targeting the gut-brain axis

Improvement of slagging monitoring and soot-blowing of waterwall in a 650MWe coal-fired utility boiler

Owing to the lack of direct measurement on the slagging extent of the waterwall, random or empirical soot-blowing strategies practiced in many power plants can result in untimely or excessive soot-blowing operations. In this research, a dynamic slagging monitoring model was established based on the heat balance principle and GA-BP (genetic algorithm and backpropagation) neural networks. A soot-blowing optimization strategy was formulated by adopting the model of the maximum net heat profit and setting the accumulated system heat loss as the assessment variable. The applicability of the proposed monitoring model and optimization strategy was evaluated for the waterwall in a 650MWe coal-fired utility boiler. The monitoring results have verified that the change of system heat loss is in line with the actual slagging trend and the influence of the electric load change on the monitoring results is weakened greatly. The optimization results have shown that activating all soot blowers of the waterwall in every soot-blowing operation can achieve the higher net heat profit per unit time and the shorter duration for each pair of soot blowers. Using the optimized soot-blowing strategy can also realize the dynamic adjustment of the moment and the duration of soot-blowing, and improve the heat transfer performance of the waterwall remarkably