This study investigated the pressure inside a pleated filter cartridge and the dust cleaning efficiency when normal and cylindrical cones were installed in a cartridge during a pulse-jet process. An ...experimental pulse-jet pleated filter dust collector was designed. The static pressures at three points along the length of the pleated filter cartridge were measured and compared before and after the cartridge was installed with cones. Various parameters, including tank pressure, nozzle diameter and jet distance, were investigated. The pressure drop of the filter cartridge and the dust emission concentration were also studied. This study has demonstrated that the increase in tank pressure improves pulse-jet intensity regardless of the presence of cones in the cartridge. Pulse-jet intensity is also enhanced when the cartridge is installed with either type of cone. Pulse-jet uniformity is reduced for normal cone but increased for cylindrical cone. The effect of cones on pulse-jet pressure is verified by operating performance during dust clogging and cleaning in clean-on-demand mode. The residual pressure drop is decreased, and the peak concentration of dust emission is increased when the normal or cylindrical cone is installed in the cartridge. A cylindrical cone extends the cleaning interval and reduces the dust emission, while the normal cone accomplishes the opposite.
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•Intensity and uniformity of a pulse-jet in a cartridge installed with cones are studied.•Variation of pulse-jet pressure is verified by dust clogging and cleaning performance.•Installation of a cylindrical cone can reduce cleaning intervals and dust emission.
Nitride wide-bandgap semiconductors possess a wide tunable energy bandgap and abundant coordination anionic groups. This suggests their potential to display nonlinear optical (NLO) properties in the ...UV wavelength spectrum. This paper reports recent progress and material discoveries in exploring UV NLO structures using nitrides. The study emphasizes their underlying structure–property correlations in order to provide a summary of the potential performance and application value of important nitride NLO crystals. Additionally, the text underscores the benefits of nitrides in terms of optical transparency, second-harmonic-generation effects, and the birefringent phase matching output wavelength limits, while addressing current issues in terms of theoretical outlook and experimental exploration.
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•A new dust collection method is put forward for use in large tunnel construction.•A dry-type filtration dust collection device is designed independently.•Experiments and application ...of the dust collection system are carried out.•The new dust collector improves dust collection efficiency.
Large amounts of rock dust are produced in the process of constructing large tunnels. It then accumulates in the tunnel where, because it is difficult to disperse, it is a serious threat to workers’ health; more than 90% of dust is respirable. Traditional methods to reduce rock dust concentrations, such as a water spray, ventilation, and foam are not effective. Therefore, a new dry-type filtration dust collection method is put forward to use in the construction of large tunnels, and a dry-type filtration dust collection device is designed. Experiments and field application of the dry-type filtration dust collection device were carried out. Experimental results showed that the total dust suppression efficiency reached 98.41% and the leakage rate was 7.86% with the dry-type filtration dust collector. The field application in the Chaoyang tunnel indicated that the efficiency of the dry-type dust collector in suppressing total and respirable dust was 98.13% and 97.86%, respectively. During lining trolley shotcreting operations, the total dust concentration decreased from 253.41 mg/m3 to 29.97 mg/m3 and the respirable dust concentration dropped from 226.73 mg/m3 to 28.85 mg/m3. The dust collection system also reached the optimal dust removal efficiency in two other tunnel construction operations and made an obvious improvement in the environment behind the dust collection system in the large tunnel. The dry-type filtration dust collector effectively improves the rock dust collection efficiency and makes up for the problem of inadequate treatment of respirable dust by the traditional methods.
Roadheader is the core equipment of roadway excavation. Affected by the sudden change of cutting load and complex roadway floor conditions, the position pose of the roadheader is very prone to ...deviation. Usually, the roadheader’s position pose deviation is corrected by controlling its supporting and tracking unit. However, this will greatly reduce the roadway excavation efficiency in case of a small position pose deviation. Therefore, a new scheme for the automatic compensation of position pose deviation is proposed by controlling the cutting boom motion. Firstly, the kinematics model of cutting boom is established, and the pitch and yaw position pose deviation compensation models are constructed. To improve the control accuracy of cutting boom motion, the reduced-order active disturbance rejection controller is designed. Then, the compensation control experiments of pitch and yaw position pose deviation are carried out based on the position pose compensation experiment system. The results show that the maximum errors of cutting trajectory after compensation meet the requirements of roadway cross-section quality, proving the effectiveness of the proposed position pose compensation control scheme.
Abstract Low-energy consumption seawater electrolysis at high current density is an effective way for hydrogen production, however the continuous feeding of seawater may result in the accumulation of ...Cl − , leading to severe anode poisoning and corrosion, thereby compromising the activity and stability. Herein, CoFeAl layered double hydroxide anodes with excellent oxygen evolution reaction activity are synthesized and delivered stable catalytic performance for 350 hours at 2 A cm −2 in the presence of 6-fold concentrated seawater. Comprehensive analysis reveals that the Al 3+ ions in electrode are etched off by OH − during oxygen evolution reaction process, resulting in M 3+ vacancies that boost oxygen evolution reaction activity. Additionally, the self-originated Al(OH) n − is found to adsorb on the anode surface to improve stability. An electrode assembly based on a micropore membrane and CoFeAl layered double hydroxide electrodes operates continuously for 500 hours at 1 A cm −2 , demonstrating their feasibility in brine electrolysis.
The effect of wet environments on the dust cake of filter media was studied. The collapse angles of dust particles and the collapse angles between dust particles and filter media increase with ...increasing dust moisture content, relative humidity, and spray rate. The smallest growth rate of collapse was observed under dust moisture content, while the largest growth rate occurred under the spray rate condition. The collapse angles between dust particles and filter media of coated filter media were smaller compared to those of mechanical filter media under different wet environments. The dust cake drag coefficients of both filter media initially increase and then decrease with an increase in the dust moisture content, decrease with the acceleration of the relative humidity, and show a pattern of first decreasing and then increasing as the spray rate increases. The dust loading capacity of both filter media follows an opposite trend to that of the dust cake drag coefficients.
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•The dust cake uniformity was proposed and defined.•The residual dust cake uniformity had significant effect on the filtration process.•A filtration model considering the cake ...uniformity was built and fit well with test.
Residual dust cakes have significantly influenced the filtration process, although its distribution uniformity has been rarely studied in previous references. In this research, we propose a definition of the dust cake uniformity for the first time, based on the assumption that the dust cake was rearranged into new location on the filter and the filtration area was divided into three regions. A simple but effective model was established with the main focus being the effect of the residual dust cake uniformity RU on the filtration process. Results show that the numerical model was validated by the experiment, with RU being a key factor within the filtration model. The pressure drop increased noticeably with increasing RU, and the exponential correlation between the residual pressure drop and RU was obtained. The filtration cycle time decreased, with the increase of RU, while the regional surface dust mass, regional filtration velocity and rebuilding dust cake uniformity increased. Additionally, evolutions of the pressure drop increasing rate and regional dust cake thickness were complex with RU.
Dust pollutants generated from the coal transfer process in a high-rise building of the mine hoisting system not only undermine the operating environment but also reduce the surrounding air quality. ...Therefore, this study aimed to determine the spatiotemporal distribution of coal dust in the high-rise buildings using field measurement and numerical simulation. Based on the discrete phase model (DPM), the dust migration process under the hybrid ventilation system was investigated in detail. Then, the feasibility of the established model to predict the spatiotemporal distribution of dust pollutants was proven through the measurements of both the airflow and the dust concentration. The present study showed that dust distribution is not uniform in time and space, which also differs for different floors. The dust concentration of the 3
rd
floor is relatively larger when compared with those of other floors. The dust concentration increases for the upper floors when the upward air velocity increases, while those of the lower floors are not always low due to the backflows, particularly for the 2
nd
floor. PM
2.5
takes up more than 20% of all discharged particles.
A new domino reaction between thioaurones and malononitrile has been reported. This reaction allows efficient access to benzothiophene-fused pyran derivatives in good yields under mild reaction ...conditions. The substrate scope is broad; a series of benzothiophene-fused pyran derivatives have been synthesized.
Abstract
In this paper, several Al–Si–Co and Al–Si–Co–Fe alloys were prepared by varying the contents of Si, Co and Fe, solidified via fast and slow–cooling conditions. In the ternary Al–xSi–yCo (x = ...6, 12, 18; y = 2, 4) alloys, the Co–rich phase is Al
9
Co
2
–type with a certain Si content, which can be marked as (Al,Si)
9
Co
2
. The Al
9
Co
2
–type phase exhibits developed dendrites and block–like morphologies under fast and slow cooling conditions, respectively. In the quaternary Al–xSi–4Co–yFe (x = 6, 12, 18; y = 2, 4) alloys, the formed intermetallic compound is Al
13
Fe
4
–type, containing a certain amount of Si and Co. It exhibits fine and coarse dendritic morphologies under fast and slow–cooling conditions, respectively. With the increase of Si content and Fe: Co ratio in the Al–xSi–4Co–yFe alloys, the Si content and Fe: Co ratio in the Al
13
Fe
4
–type phase increase synchronously. The hardness of Al–xSi–4Co–yFe alloys were tested, and it was found that the fast–cooling alloys have higher hardness than the slow–cooling ones, while the value of fast–cooling Al–12Si–4Co–4Fe alloy is the highest. Besides, comparing with Al
9
Co
2
, the Al
13
Fe
4
phase has a much higher tendentiousness to precipitate from Al–Si–Co–Fe alloys. This work may be referred for the control of Co– and Fe–rich phases in Al–Si alloys, with the concept of altering element contents and solidification conditions.
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