[ad_1]
Ignition temperature and explosion strain of suspended coal mud clouds
Minimal ignition temperature of suspended coal mud cloud underneath completely different circumstances
The particle dimension of the coal samples used within the experiment is lower than 75 μm. The minimal ignition temperature of coal mud cloud underneath the situation of spraying mud strain of 20 kPa is 983 Okay, as proven in Desk 3. Within the confined house of the experimental tools, at a temperature of 983 Okay, suspended coal mud clouds are ignited, which is the important temperature at which coal mud clouds may be ignited. Beneath this temperature, coal mud clouds can’t be ignited. This check knowledge can present a foundation for understanding the combustion and explosion traits of coal mud.
On this foundation, the minimal ignition temperature of coal mud clouds may be examined underneath completely different spray strain circumstances. The check outcomes are proven in Fig. 5. It may be obtained that when the mud spray strain is larger than 20 kPa, the minimal ignition temperature of the suspended coal mud cloud will increase. When the mud spray strain is 60 kPa, the minimal ignition temperature is 1123 Okay. When the mud spray strain is lower than 20 kPa, the minimal ignition temperature of the suspended coal mud cloud will increase. When the mud spray strain is 5 kPa, the minimal ignition temperature is 1133 Okay. These outcomes point out that the optimum mud spray strain is 20 kPa. Below this situation, coal mud clouds usually tend to ignite.
Minimal ignition temperature underneath completely different mud spray strain circumstances.
As proven in Fig. 6, the impact of mud spray strain on the diffusion of coal mud cloud particles within the ignition house is offered. Within the experimental tools, when the mud spray strain is 20 kPa, the coal mud cloud diffuses extra evenly, and extra coal mud particles transfer into the ignition house, forming a suspended coal mud cloud. As a result of warmth trade and switch between coal mud particles, the coal mud cloud underneath this situation is extra simply ignited. If the spraying strain is lower than 20 kPa, the driving pressure obtained by coal mud particles is considerably inadequate, and the variety of coal mud particles that may enter the ignition house is significantly decreased. The particles are concentrated within the higher a part of the house, which weakens the warmth trade between particles. To be ignited, increased temperatures are required. If the spraying strain is larger than 20 kPa, the ability to drive coal mud particles into the ignition house is comparatively excessive. Below the motion of gravity, extra coal mud will likely be concentrated beneath the inside of the ignition house, which isn’t conducive to the discharge and trade of warmth from coal mud particles, and the temperature required for ignition will likely be increased.
Impact of mud spray strain on ignition of suspended coal mud clouds.
Explosion strain of suspended coal mud clouds underneath completely different circumstances
Within the explosion strain check experiment, the mud spray strain is 2 MPa, the ignition delay time is 0.1 s, and the ignition power is 10 kJ. In line with the experimental outcomes, the utmost strain of suspended coal mud cloud explosion is 0.78 MPa, and the utmost strain rise fee is 73.27 MPa s−1, the outcomes are proven in Desk 4. Below regular circumstances, the usual atmospheric strain is 0.1 MPa, and an explosion produces a most strain of 0.78 MPa. The required coal mud is barely 10 g. This explosion has a terrific energy, and the focus of coal mud clouds within the explosion house can attain 500 g m−3. This focus situation may be very favorable for the event of the explosion.
Within the explosion strain experiment talked about above, the mass of coal mud used is 10 g. The change in coal mud high quality will have an effect on the focus of suspended coal mud clouds within the explosion house. The focus of coal mud clouds can have a big impression on explosion strain. Subsequently, to be able to examine the impact of coal mud cloud focus on explosion strain, experiments may be carried out constantly by altering the quantity of coal mud used. The connection between the mass focus of coal mud cloud obtained from the check and the explosion strain is proven in Fig. 7. It may be clearly seen that when the mass focus of coal mud cloud is 500 g m−3, the utmost strain and most strain rise fee are each the best, with values of 0.78 MPa and 73.27 MPa s−1, respectively. When the mass focus of coal mud cloud is lower than or larger than 500 g m−3, the utmost strain and the utmost fee of strain rise will lower. It’s because if the mass focus of coal mud clouds is simply too small, the coal mud particles that launch warmth are inadequate. If the mass focus of coal mud clouds is simply too excessive, the oxygen required for the explosion will likely be inadequate. There’s a dynamic equilibrium between coal mud particles and oxygen. When the mass focus of coal mud cloud is 500 g m−3, the suspended coal mud cloud reaches this equilibrium state, and the explosion strain can be the utmost.
Relationship between mass focus of coal mud clouds and explosion strain.
Inhibitory impact of explosion suppressants on ignition temperature and explosion strain of coal mud clouds
Inhibitory impact of explosion suppressants on ignition temperature of coal mud clouds
Within the earlier textual content, the minimal ignition temperature of suspended coal mud clouds underneath completely different circumstances was obtained. Subsequent, use explosion suppressants Al(OH)3, KH2PO4, and NH4H2PO4 to check their suppression traits on the minimal ignition temperature of coal mud clouds. When the mud spray strain is 20 kPa, the minimal ignition temperature of the coal mud cloud is 983 Okay. Below this situation, combine completely different explosion suppressants with coal mud particles individually, after which check the minimal ignition temperature of the combination. The higher restrict for experimental tools testing is 1273 Okay. The mass share of the explosion suppressant combined with coal mud is p. The mud particle dimension of the explosion suppressant can be 0–75 μm. Desk 5 reveals the minimal ignition temperature of coal mud clouds underneath completely different mass percentages of suppressants combined with coal mud.
As proven in Desk 5, the minimal ignition temperature after mixing completely different explosion suppressants and coal mud considerably will increase. When Al(OH)3 is combined with coal mud and the mass share is 60%, the minimal ignition temperature of the coal mud cloud is 1213 Okay. Below this situation, the coal mud cloud can nonetheless be ignited. When KH2PO4 is combined with coal mud, the higher restrict of the check temperature is simply reached when the share of combination is 55%. When NH4H2PO4 is combined with coal mud, the higher restrict of the check temperature can be reached when the share of combination is 40%. Primarily based on the above outcomes, the inhibitory results of three explosion suppressants may be in contrast, with NH4H2PO4 having the strongest inhibitory impact, KH2PO4 having the second strongest inhibitory impact, and Al(OH)3 having the weakest inhibitory impact. Determine 8 is drawn to check the inhibitory results of explosion suppressants. It may also be discovered that the inhibitory impact of NH4H2PO4 is the best. When p is 40%, inside the higher restrict vary of the check temperature, the ignition of coal mud clouds may be fully suppressed.
Inhibitory impact of various explosion suppressants on minimal ignition temperature of coal mud clouds.
The next analyzes the impression of explosion suppressants on the ignition means of coal mud clouds from the angle of ignition suppression mechanism. After mixing Al(OH)3 with coal mud, underneath heating circumstances, Al(OH)3 will bear the next chemical response: Al(OH)3 → Al2O3 + H2O. The generated Al2O3 will stop the coal mud particles from releasing warmth outward, whereas the generated H2O will evaporate and take in warmth. When heated to 673 Okay, KH2PO4 generates KPO3 and H2O. KPO3 will block the warmth trade of coal mud particles, and H2O will likely be evaporated to soak up warmth. Below the heating circumstances of NH4H2PO4, P2O5, H2O, and NH3 are generated. P2O5 is a stable product that may stop warmth switch and take in house warmth. H2O is a liquid product that may evaporate and take in warmth. NH3 is a gasoline product that may dilute oxygen. Resulting from the truth that NH4H2PO4 generates extra kinds of merchandise after being heated, it performs a larger position in suppressing the ignition of coal mud clouds.
Inhibitory impact of explosion suppressants on explosion strain of coal mud clouds
On the premise of the earlier dialogue on the suppression impact of Al(OH)3, KH2PO4, and NH4H2PO4 on the minimal ignition temperature of suspended coal mud cloud, though the inhibitory impact of various explosion suppressants has been obtained, as a result of comparatively excessive value of NH4H2PO4 mud, it’s tough to make use of NH4H2PO4 mud alone to suppress the explosion of coal mud in trade. Subsequently, to be able to cut back the fee, on this half, the blending of various suppression mud in line with completely different schemes is taken into account, and the combined suppression mud is used to check the explosion strain suppression impact.
The precise explosion check scheme is as follows: the mass of the coal mud pattern continues to be 10 g, of which 100% of the particle dimension is 0 ~ 75 μm, as a result of the micron sized coal mud particles are explosive, which is handy to look at the suppression impact. The mud particle dimension of the explosion suppressant can be 0–75 μm.
As well as, among the many three kinds of explosion suppression mud Al(OH)3, KH2PO4, and NH4H2PO4, since NH4H2PO4 has the best suppression impact, we should always give attention to the outcomes of the explosion suppression experiment with the participation of NH4H2PO4. There are three plans to combine explosive suppression mud, the primary is to combine Al(OH)3 and KH2PO4, the second is to combine Al(OH)3 and NH4H2PO4, and the third is to combine KH2PO4 and NH4H2PO4. In these three schemes, the mass share of various two kinds of explosion suppression mud is 50% for each. On this foundation, the explosion suppression knowledge obtained from the check are proven in Desk 6. Utilizing the info in Desk 6, the explosion strain curve underneath the situation of combined explosion suppression mud is drawn, and the outcomes are proven in Figs. 9 and 10.
Suppression of combined suppression mud on Pmax.
Suppression of combined suppression mud on (dP/dt)max.
By evaluating the explosion suppression impact of combined explosion suppression mud and single explosion suppression mud, some great benefits of combined explosion suppression mud may be higher understood. When utilizing a single sort of explosion suppression mud, the most effective impact of explosion suppression mud is NH4H2PO4, adopted by KH2PO4, and the worst is Al(OH)3. As proven in Figs. 9 and 10, underneath the situation of utilizing combined explosion suppression mud, the explosion suppression impact of blending KH2PO4 and NH4H2PO4 in 1:1 ratio is worse than that of utilizing NH4H2PO4 mud alone, as a result of when KH2PO4 and NH4H2PO4 are combined and the mass share of combined explosion suppression mud is 50%, the utmost explosion strain and the utmost strain rise fee are 0.19 MPa and 14.73 MPa s−1, respectively, which is bigger than the info of utilizing NH4H2PO4 mud alone for explosion suppression. It reveals that lowering the proportion of NH4H2PO4 within the explosion suppression mud will cut back the explosion suppression impact, however it’s going to significantly save the fee to a sure extent. When utilizing KH2PO4 and NH4H2PO4 because the combined explosion suppression mud, as soon as the mass share of suppression mud combined into coal mud is 60%, the explosion may also be prevented. Subsequently, it’s proved that deciding on the strategy of KH2PO4 and NH4H2PO4 mixing as an alternative of utilizing NH4H2PO4 alone also can management the explosion to a sure extent. This evaluation result’s of nice significance for explosion suppression analysis, as a result of the explosion suppression impact of NH4H2PO4 is certainly higher than that of KH2PO4, lowering the share of NH4H2PO4 will definitely cut back the explosion suppression impact.
Additional evaluation reveals that the explosion suppression impact of blending Al(OH)3 and NH4H2PO4 is inferior to that of blending KH2PO4 and NH4H2PO4. When Al(OH)3 and NH4H2PO4 are combined and the mass share of the suppression mud combined into coal mud is 60%, the explosion continues to be not fully suppressed. The utmost strain and the utmost strain rise fee of the explosion are 0.16 MPa and 18.62 MPa s−1, respectively. When the mass share of suppression mud will increase to 70%, the explosion is not going to happen once more. Subsequently, when it comes to the explosion suppression impact, the explosion suppression impact of combination Al(OH)3 and NH4H2PO4 is inferior to that of combination KH2PO4 and NH4H2PO4.
Lastly, the explosion suppression traits underneath the situation of blending Al(OH)3 and KH2PO4 are mentioned. From the check knowledge, it may be seen that the explosion suppression impact after mixing Al(OH)3 and KH2PO4 is the worst among the many three kinds of mixing schemes. When the mass share of suppression mud combined into coal mud is 80%, the utmost explosion strain and the utmost strain rise fee are respectively 0.15 MPa and 18.20 MPa s−1. The explosion doesn’t happen till the mass share of the explosion suppression mud is elevated to 90%, which isn’t excellent by comparability. The above evaluation outcomes are of nice significance for understanding the suppression impact of coal mud cloud explosion strain underneath completely different combined circumstances of explosion suppressants.
[ad_2]