查看更多>>摘要：Single-fire and double-fire extinguishments by water mist were conducted to assess the similarities and differences. The double-fire extinguishment requires higher applied volume flux of the water mist and spray momentum, while it is achieved faster than the single-fire extinguishment, owing to the smaller size of the single flames of the double-fire. Both the air entrainment restriction among the two flames of the double fire and the typical re-ignition phenomenon have a significant effect on the double-fire extinguishment. A double-fire merging from the burner surface is more difficult to be extinguished in terms of the critical operating pressure since the air entrainment restriction among the two flames of the double-fire is more intense. A double-fire with a smaller flame spacing requires a longer extinguishing time since re-ignition happens more easily. The equivalent diameter (D-e) is applied to calculate the plume-spray thrust ratio of the double-fire and evaluate the competition between the double-fire and the water mist quantitatively.(C) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
查看更多>>摘要：Low-cost, stable materials that can be used for oil-water separation have significant industrial applications. A simple two-step immersion approach was used to successfully create a melamine sponge with superhydrophobic/superlipophilic characteristics. The polyphenolamine@ 1 H,1 H,2 H,2 H-perfluorodecyltrichlorosilane sponge (PPA@PF sponge) produced in this study possesses exceptional superhydrophobic and superlipophilic properties. Scanning electron microscopy (SEM), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS) were used to examine the surface morphology and chemical content of the PPA@PF sponge. The prepared PPA@PF sponge has a static contact angle (SCA) of 156 degrees. More notably, PPA@PF sponge has extremely stable and anti-corrosion properties. After being corroded by acidic solutions, alkaline solutions, and organic solvents, the PPA@PF sponge retains good hydrophobic characteristics on its surface. Finally, the PPA@PF sponge is successfully applied to the rapid oil-water separation. (c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
查看更多>>摘要：The oxygen production efficiency of microalgae is a critical factor for the performance of algal-bacterial symbiotic systems during real wastewater treatment. This study proposed a new method to enhance the growth and oxygen production rate of microalgae via microwave irradiation. The oxygen production per-formance of Chlorella pyrenoidosa grown in real wastewater was evaluated in the presence of microwaves, and the photosynthetic oxygen production rate was calculated based on the produced chlorophyll-a and dissolved oxygen. The results showed that microwave treatment promoted both algal growth and oxygen production. Chlorella pyrenoidosa was irradiated by microwave during the logarithmic phase. When the radiation power was 400 W and the treatment time was 25 s, the oxygen production of Chlorella pyrenoidosa and chlorophyll-a increased by 10.7% and 12.4%, while the photosynthetic oxygen production rate increased by 5.8%. Therefore, microwave can save the aeration energy required for degrading organic matter in real wastewater by algal-bacterial systems.(c) 2022 Published by Elsevier Ltd on behalf of Institution of Chemical Engineers.
Abdullah, Mohd Amirul MukminSeman, Mazrul Nizam AbuChik, Syed Mohd Saufi TuanAbdullah, Syamsul...
16页
查看更多>>摘要：This study aims to optimize the operating conditions of the forward osmosis (FO) process by introducing thermo-responsive ionic liquids (TRILs) namely 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) as a draw solution for seawater desalination applications. The influence of the operation parameters, such as the feed and draw flowrate (60-300 ml/min), draw solution concentration (0.6-3.0 M), temperature (25-50 ?), and type of flow with feed concentration using artificial seawater (0.6 M NaCl). The interaction between parameters has been specified using fractional factorial design (FrFD). The draw solution concentration and the interactions between draw and feed flowrate were the most significant factors in achieving high water flux 5.1 LMH. Besides that, the draw flowrate and the interaction of both draw and feed flowrate give high significance toward adverse effects (such as concentration polarization), which is good to obtain low reverse salt at 1.3 gMH. Use the desirability function (DF) to obtain the highest water flux of 5.04 LMH and the lowest reverse salt flux of 1.71 gMH, with a desirability of 0.95. The optimal condition for FO performance is 300 ml/min feed and draw flowrate with 3.0 M draw solution at 25 ?& nbsp;and co-current flow. (c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
查看更多>>摘要：The physical and chemical compositions of municipal solid waste (MSW) are important factors affecting the formation and release of polychlorinated dibenzodioxins/dibenzofurans (PCDD/Fs). A 4-year investigation (2017-2020) of the emission characteristics of PCDD/Fs from the flue gas and fly ash by a full-scale MSW incinerator in Ningbo city, Zhejiang province was conducted. This was undertaken to determine the implications of sorting MSW. Results showed that progress made in classifying MSW has led to a significant decrease in the proportion of kitchen waste components, the moisture and chlorine contents of MSW. However, there has also been a significant increase in the proportion of textile and wood components and calorific value. Approximately 60% of the PCDD/Fs generated during MSW incineration were captured in the fly ash that enters the filter bag. The PCDD/Fs emission factors were significantly positively correlated with the proportion of kitchen waste, plastics and heavy metal elements Fe, Ni, Mn, Cr, Pb, Cd, and Zn in the MSW, and negatively correlated with the wet-based high and low calorific values of the MSW. A decreasing trend in PCDD/Fs generation and emission from 3339.3 ng/t MSW in 2018-1787.5 ng/t MSW in 2020 was observed since the implementation of MSW classification as it can reduce the quantity of kitchen waste and plastics, and improve the calorific value of the MSW.(c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
查看更多>>摘要：Time-domain reflectometry (TDR) has been used for the characterization of media; however, the results of TDR tests significantly differ according to the types of solutions. The objective of this study is to suggest a new relationship between TDR output values and bulk electrical conductivity based on a machine learning algorithm for enhancing the reliability of TDR measurement. Various salinities (0%, 1%, 2%, and 3%) and lead concentrations (0, 0.5, 1, 2, 5, and 10 mg/L) are applied along with silica sand, classified as SP in USCS, to create media. A laboratory test is performed to measure the TDR waveform at the bottom of the cylindrical cell, and a resistance probe is also installed to obtain the true bulk electrical conductivity in the cell. A deep neural network machine learning algorithm is applied to establish the relationship between the TDR output value and the bulk electrical conductivity at each frequency of 0.1, 0.12, 1, 10, and 100 kHz. The highly important variables are also defined through random forest. This study demonstrates that the TDR can be reliably converted into bulk electrical conductivity when two different solutions are mixed.(c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
Nawaz, Muhammad SaqibAlamoudi, TalalSoukane, SofianeObaid, M....
11页
查看更多>>摘要：Water and energy are key components to assess the feasibility of any water treatment technique. For industrial applications of forward osmosis (FO), energy optimization needs to be explored further. Asymmetric temperature conditions, having different feed solution (FS) and draw solution (DS) temperatures, are likely to occur in industrial FO applications and are least explored. Some standard practices are followed without any scientific evidence of their impact on the system performance and energy utilization, like maintaining the colder stream temperature instead of letting it reach a steady state with the hotter stream. This study compares water flux, reverse solute flux (RSF), and energy utilization when the colder stream temperature is maintained and not maintained. Thin film composite-poly amide (TFC-PA) and cellulose triacetate (CTA) membranes were used at laboratory-scale in 24 h batch experiments with 0.75 M NaCl as DS and DI water as FS. All possible configurations of membrane orientation (AL-DS and AL-FS) and streams heating and cooling strategies were studied. The module material was made up of plexi-glass with 4 cm thick plates and flexible tubing of PVC was used. Results revealed that under not maintained conditions, on average, the water flux increased by 9.1-17%, RSF increased by 13.8-27.3%, and energy consumption reduced by 75.8-67% with CTA and TFC membranes, respectively. Therefore, if the RSF is not the primary concern of the application, it is advantageous not to maintain the colder stream temperature. However, it is recommended that scientists verify and compare the efficiencies between maintained and not maintained temperatures under their specific experimental conditions.(c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
查看更多>>摘要：The safe design and operation of clean fuels like hydrogen require a detailed understanding of their explosion characteristics. An experimental study of the flame propagation behavior influenced by quadrangular, cylindrical, and triangular obstacles was executed in a 530 mm x 82 mm x 82 mm pipe. The results confirm the understanding that obstacles with a tip promote the generation of flow instability and produce a more intense burning behavior of the flame. The shear layers shed fewer larger vortices after the quadrangular obstacle; however, these vortices can be dislodged to form smaller and more vortices after passing through the triangular obstacles. The shear layer has weak shedding properties behind obstacles with curved edges. In the flame propagation process, the quadrangular obstacles have a more obvious promoting effect of the initial explosion, but the degree is weaker than with the triangular obstacles. The effect of the quadrangular obstacles on flame velocity is mainly influenced by gas flow at the flame front. In triangular obstacles, the shear layer became prominent in the later stage of the explosion process and this contributes to enhancing the flame velocity and overpressure.(c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
查看更多>>摘要：Hydrothermal treatment (HTT) of polyvinyl chloride (PVC) can efficiently remove chlorine (Cl) to produce low Cl hydrochar for solid fuel. This work performed co-hydrothermal treatment of PVC recycled plastics (PVCR) with biomass, then tried to reveal the combustion behavior and Cl migration behavior during combustion of PVC-derived hydrochar. It is shown that the hydrothermal temperature was the dominant factor affecting the degradation and dechlorination of PVCR. Treated at 220 degrees C for 60 min, the dechlorination efficiency of PVCR was 4.88 wt% and it was significantly increased to 34.09 wt%, 28.60 wt% and 32.50 wt% when PVCR was co-treated with bagasse, bagasse + high impact polystyrene (HIPS) and bagasse + acrylonitrile butadiene styrene (ABS), respectively. The substitution of Cl by hydroxyl (-OH) and elimination were two main dechlorination pathways. Bagasse could provide abundant-OH so as to promote the de chlorination of PVCR. Interestingly, in the combustion of PVCR and hydrochars, the Cl was mainly released in the form of HCl at lower temperature combustion stage but C-Cl mostly emitted at higher temperature combustion stage. The emitted Cl species strongly depends on the Cl content in hydrochar and combustion temperature, but did not show relevance to the existence form of Cl in hydrochar. Hydrothermal de chlorination could sharply reduce HCl emission.(C) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
查看更多>>摘要：Studies of overpressure loads are essential to mitigate the potential hazards of public safety induced by gas explosion accidents. Based on the computational fluid dynamics (CFD) code FLACS, numerical models of gas explosions in large-scale tunnels were developed and verified by comparing with testing data. Numerical simulations of gas explosions in confined and side-vented utility tunnels were carried out. The effects of the venting condition, gas cloud volume, and ignition position were analyzed and discussed. It is found that gas explosions in utility tunnels can be divided into three stages according to the pressure and flame development, i.e., the combustion-induced rise stage, oscillation rise stage, and oscillation decline stage. The pressure oscillation is significant, and a side vent near the tunnel end can reduce the peak pressure by 42~78% and the oscillation peak by 35~87%. The peak pressure, oscillation peak, and duration of oscillation rise stage varied significantly with the gas cloud volume. When the premixed gas cloud is ignited at the 1/ 4 L, the peak pressure and oscillation peak reach the maximum of 1242.5 kPa and 490.4 kPa for confined cases, which are one time higher than those of side-vented cases. What is more, based on the equivalent single degree of freedom (SDOF) approach in the elastic range, the dynamic effects of gas explosions in utility tunnels are figured out, and suggestions for engineering practice are proposed. (c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.
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