scholarly journals Investigation into the Suppression Effects of Inert Powders on the Minimum Ignition Temperature and the Minimum Ignition Energy of Polyethylene Dust

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 294
Author(s):  
Chendi Lin ◽  
Yingquan Qi ◽  
Xiangyang Gan ◽  
Hao Feng ◽  
Yan Wang ◽  
...  
Keyword(s):  
Ignition Temperature ◽  
Potassium Salt ◽  
Explosion Energy ◽  
Inert Material ◽  
Minimum Ignition Energy ◽  
Suppression Effect ◽  
Minimum Ignition Temperature ◽  
Comparison Of The Results ◽  
Suppression Effects ◽  
Better Than

The risks associated with dust explosions still exist in industries that either process or handle combustible dust. This explosion risk could be prevented or mitigated by applying the principle of inherent safety. One effective principle is to add an inert material to a highly combustible material in order to decrease its ignition sensitivity. This paper deals with an experimental investigation of the influence of inert dust on the minimum ignition temperature and the minimum explosion energy of combustible dust. The experiments detailed here were performed in a Godbert–Greenwald (GG) furnace and a 1.2 L Hartmann tube. The combustible dust (polyethylene—PE; 800 mesh) and four inert powders (NaHCO3, Na2C2O4, KHCO3, and K2C2O4) were used. The suppression effects of the four inert powders on the minimum ignition temperature and the minimum explosion energy of the PE dust have been evaluated and compared with each other. The results show that all of the four different inert dusts have an effective suppression effect on the minimum ignition temperature and the minimum explosion energy of PE dust. However, the comparison of the results indicates that the suppression effect of bicarbonate dusts is better than that of oxalate dust. For the same kind of bicarbonate dusts, the suppression effects of potassium salt dusts are better than those of the sodium salt. The possible mechanisms for the better suppression effects of bicarbonate dusts and potassium salt dusts have been analyzed here.

scholarly journals Variation of ignition sensitivity characteristics of non-stick coal dust explosions

2020 ◽  
Author(s):  
Di Sha ◽  
Yucheng Li ◽  
Xihua Zhou ◽  
Ruiqing Li
Keyword(s):  
Ignition Temperature ◽  
Coal Dust ◽  
Dust Cloud ◽  
Particle Sizes ◽  
Ignition Energy ◽  
Minimum Ignition Energy ◽  
Dust Layer ◽  
Independent Variables ◽  
Minimum Ignition Temperature ◽  
Dust Explosions

Abstract The ignition and explosion of coal dust are significant hazards in coal mines. In this study, the minimum ignition temperature and energy of non-stick coal dust were investigated empirically at different working conditions to identify the key factors that influence the sensitivity and characteristics of coal dust explosions. The results showed that for a given particle size, the minimum ignition temperature of the coal dust layer was inversely related to the thickness of the coal dust layer. Meanwhile, when the layer thickness was kept constant, the minimum ignition temperature of the coal dust layer decreased with smaller coal dust particle sizes. Over the range of particle sizes tested (25–75 μm), the minimum ignition temperature of the coal dust cloud gradually increased when larger particles was used. At the same particle size, the minimum ignition temperature of the coal dust layer was much lower than that of the coal dust cloud. Furthermore, the curves of minimum ignition energy all exhibited a minimum value in response to changes to single independent variables of mass concentration, ignition delay time and powder injection pressure. The interactions of these three independent variables were also examined, and the experimental results were fitted to establish a mathematical model of the minimum ignition energy of coal dust. Empirical verification demonstrated the accuracy and practicability of the model. The results of this research can provide an experimental and theoretical basis for preventing dust explosions in coal mines to enhance the safety of production.

Mechanical and flame retardant properties of isotactic polypropylene/magnesium oxysulfate whisker composite

2017 ◽  
Vol 31 (4) ◽  
pp. 514-534 ◽  
Author(s):  
Li Dang ◽  
Xueying Nai ◽  
Xin Liu ◽  
Donghai Zhu ◽  
Yaping Dong ◽  
...  
Keyword(s):  
Isotactic Polypropylene ◽  
Interfacial Interaction ◽  
Flexural Behavior ◽  
Cone Calorimetry ◽  
Melt Mixing ◽  
Suppression Effect ◽  
Peak Heat Release Rate ◽  
Magnesium Oxysulfate ◽  
Flame Retardant Properties ◽  
Better Than

Isotactic polypropylene (iPP) composites containing magnesium oxysulfate whisker (MOSw) or lauric acid-modified MOSw (LA-MOSw) were prepared via melt mixing in a torque rheometer. Scanning electron microscopy pictures showed that the interface between MOSw and iPP matrix was defined, whereas a vague interface was seen in the iPP–LA-MOSw composites. Mechanical properties of these two groups of composites were investigated in terms of tensile, notched impact, and flexural behavior aspects for the purposes of studying toughening effect of MOSw and LA-MOSw. Tensile results showed that yield strength of composites further reduced with the presence of LA, indicating the decrease in interfacial interaction bewteen iPP matrix and MOSw. As such, LA-MOSw performed better than MOSw in toughening of iPP matrix. Flexural strength and modulus of iPP–MOSw composites increased sharply with the increase in MOSw content, while less dependence on the LA-MOSw content indicated that MOSw was deemed beneficial to increase the stiffness. In addition, flammability properties were investigated by cone calorimetry experiment. The results showed that the peak heat release rate apparently reduced with addition of MOSw or LA-MOSw. Besides, iPP–LA-MOSw composites showed higher specific extinction area values than iPP–MOSw composites, which meant the weaker smoke suppression effect of LA-MOSw. It was chiefly because of the incomplete combustion caused by the continuous and complete charred (MgO) shield. The presence of LA was another possible reason.

Minimum Ignition Temperature of Dusts, Gases, and Solvents Hybrid Mixtures

2016 ◽  
Vol 188 (11-12) ◽  
pp. 1693-1704 ◽  
Author(s):  
Emmanuel Kwasi Addai ◽  
Dieter Gabel ◽  
Haider Ali ◽  
Ulrich Krause
Keyword(s):  
Ignition Temperature ◽  
Minimum Ignition Temperature ◽  
Hybrid Mixtures

The Influence of Variable-Speed Waveforms on Vibration Suppression in Time-Varying Speed Cutting

2013 ◽  
Vol 690-693 ◽  
pp. 2514-2518
Author(s):  
Juan Cong ◽  
Yun Wang ◽  
Wei Na Yu
Keyword(s):  
Wave Speed ◽  
Vibration Suppression ◽  
Sine Wave ◽  
Time Varying ◽  
Variable Speed ◽  
Suppression Effect ◽  
Speed Variation ◽  
Input And Output ◽  
System Input ◽  
Better Than

Through the research on the change of system input and output energy in time-varying speed cutting, the influence of variable-speed waveforms on vibration suppression effect in time-varying speed cutting is quantitatively analyzed in this paper. A conclusion can be drawn that sine wave speed variation is better than triangle wave speed variation in vibration suppression.

scholarly journals Analysis of minimum ignition temperature of pellet dust layer and cloud due to adding BC and ABC fire extinguishing powders

2018 ◽  
Vol 247 ◽  
pp. 00003
Author(s):  
Bożena Kukfisz
Keyword(s):  
Outer Surface ◽  
Ignition Temperature ◽  
Test Results ◽  
Dust Layer ◽  
Fire Extinguishing ◽  
Minimum Ignition Temperature ◽  
The Impact

The paper describes the impact of adding fire extinguishing powders acting based on oxygen or flame on values of minimum ignition temperatures of the layer and cloud of pellet dust, and as a consequence the impact or lack of impact on values of maximum admissible temperature on external surfaces of electrical appliances working in their atmospheres. Tests were conducted of the minimum ignition temperature of layer and cloud of the agro armakow pellet dust and the agro jesień pellet dust, with and without additives of fire extinguishing powders BC Jet, BC LB2, ABC 90 and Ogniotex 103 at concentrations ranging from 5 to 70% by weight of powder contents in the mixture. Based on obtained test results it has been ascertained that type ABC powders appear to be much more effective than those type BC, because they have a much bigger impact on increasing the minimum ignition temperature of the layer and the cloud of analysed dust types. Adding only 15% of ABC 90 extinguishing powder to the agro jesień pellet has caused an increase in the minimum ignition temperature of dust layer by 80°C. The BC LB2 powder with agro armakow pellet dust has not been found to cause any changes, even at its concentration as high as 70%. The most optimum additive of powder to the biomass dust was 10% by weight of ABC powder in the mixture. At this concentration the highest increase was recorded in the maximum admissible temperature on the outer surface of electrical appliances from 235°C to 273°C.

scholarly journals Comparison of Periodic Flow Fields in a Radial Pump among CFD, PIV, and LDV Results

2009 ◽  
Vol 2009 ◽  
pp. 1-10 ◽  
Author(s):  
Jianjun Feng ◽  
F.-K. Benra ◽  
H. J. Dohmen
Keyword(s):  
Unsteady Flow ◽  
Laser Doppler Velocimetry ◽  
Particle Image ◽  
Velocity Fields ◽  
Image Velocimetry ◽  
Rotating Impeller ◽  
Low Specific Speed ◽  
Radial Pump ◽  
Comparison Of The Results ◽  
Better Than

The interaction between the impeller and the diffuser is considered to have a strong influence on the unsteady flow in radial pumps. In this paper, the unsteady flow in a low specific speed radial diffuser pump has been simulated by the CFD code CFX-10. Both Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV) measurements have been conducted to validate the CFD results. Both the phase-averaged velocity fields and the turbulence fields obtained from different methods are presented and compared, in order to enhance the understanding of the unsteady flow caused by the relative motion between the rotating impeller and the stationary diffuser. The comparison of the results shows that PIV and LDV give nearly the same phase-averaged velocity fields, but LDV predicts the turbulence much clearer and better than PIV. CFD underestimates the turbulence level in the whole region compared with PIV and LDV but gives the same trend.

scholarly journals T142. SELF-OTHER DISTINCTION IN SCHIZOPHRENIA: ABNORMALITIES IN THE PREDICTION OF THE SENSORY CONSEQUENCES OF ONE’S OWN ACTIONS

2020 ◽  
Vol 46 (Supplement_1) ◽  
pp. S285-S285
Author(s):  
Lukas Uhlmann ◽  
Mareike Pazen ◽  
Bianca M van Kemenade ◽  
Tilo Kircher ◽  
Benjamin Straube
Keyword(s):  
Posterior Parietal Cortex ◽  
Sensory Input ◽  
Body Part ◽  
Predictive Processing ◽  
Hand Movements ◽  
Healthy Controls ◽  
Schizophrenia Spectrum Disorders ◽  
Action Execution ◽  
Suppression Effect ◽  
Suppression Effects

Abstract Background Core symptoms of schizophrenia include disturbances in the distinction between the self and the external world. It has been suggested that self-other distinction is governed by predictive processing: Copies of an action’s motor command are used to generate forward models that predict upcoming sensory input. These predictions are compared with actual sensory input, thereby enabling the brain to discard the processing of sensory input arising from one’s own actions. This is reflected in a decreased perception of and reduced BOLD signal for actively versus passively generated sensory input (suppression effect). Here, we investigated whether BOLD suppression effects for the processing of action feedback involving active and passive hand movements differ between patients with schizophrenia and healthy control participants. Since the identity of one’s body also contributes to self-other distinction, we additionally investigated if differences in BOLD suppression effects between patients and healthy controls are further modulated by whether participants see their own or someone else’s hand moving in accordance with their action. Methods 17 patients with schizophrenia spectrum disorders and 13 healthy controls (matched for age, sex, and educational degree) performed active and passive hand movements while lying in the MRI scanner. During movement execution (active and passive), participants saw either a real-time video of their current movement (“self”) or someone else’s hand moving in accordance with their action (“other”). This manipulation allowed disentangling the effects of movement characteristics (e.g., who is triggering the movement) from visual identity characteristics (whose hand is moving), which both contribute to self-other distinction. Variable delays were inserted between the movement and the images (“self” and “other”), which had to be detected by the participants. Results Preliminary results of behavioral performance showed an interaction between group (patients vs. healthy controls) and action execution (active vs. passive): Healthy controls detected less delays in the active condition than in the passive condition, whereas this difference was reduced in patients. In line with this, active vs. passive trials revealed larger BOLD suppression effects in healthy controls than in patients with schizophrenia in multiple brain areas (e.g., lingual gyrus, middle and superior occipital gyrus, posterior parietal cortex, cerebellum). Finally, an interaction effect was found in the thalamus, such that in healthy controls, but not in patients with schizophrenia, this area showed a BOLD suppression effect for active vs. passive movements specific for feedback of one’s own hand. Discussion Weaker behavioral and neural suppression effects in patients with schizophrenia (compared to healthy controls) show that actively generated sensory input is not as effectively discarded from further processing, suggesting that efference copy-based predictive mechanisms are impaired in patients with schizophrenia. Furthermore, BOLD suppression in the thalamus was not modulated by hand identity in patients with schizophrenia, indicating that predictive processing in schizophrenia might not take the identity of the seen body part into account.

Sign in / Sign up

Export Citation Format

Share Document