The research on explosion suppression effect of aluminum alloy explosion-proof materials cleaned by ultrasonic

Transactions of the VSB - Technical university of Ostrava Safety Engineering Series, ISSN 1805-3238 Vol. XIV, No. 1, 2019 14 THE RESEARCH ON EXPLOSION SUPPRESSION EFFECT OF ALUMINUM ALLOY EXPLOSION-PROOF MATERIALS CLEANED BY ULTRASONIC Hu SHOUTAO1, Zhou SHANGYONG2, Gao JIANCUN3, Wang LE4, Jia SHAOKANG5 1 Beijing Institute of Petrochemical Technology, Faculty of safety engineering and Beijing Academy of Safety Engineering and Technology, Beijing 102617, China, [email protected] 2 Beijing Institute of Petrochemical Technology, Faculty of safety engineering and Beijing Academy of Safety Engineering and Technology, Beijing 102617, China, [email protected] 3 Beijing Institute of Petrochemical Technology, Faculty of safety engineering and Beijing Academy of Safety Engineering and Technology, Beijing 102617, China, [email protected] 4 Beijing Institute of Petrochemical Technology, Faculty of safety engineering and Beijing Academy of Safety Engineering and Technology, Beijing 102617, China, [email protected] 5 Beijing Institute of Petrochemical Technology, Faculty of safety engineering and Beijing Academy of Safety Engineering and Technology, Beijing 102617, China, [email protected] Abstract: Premixed gas explosion pipe system was established to study the change rule of explosion pressure and pressure rise rate of 10% methane/ air premixed gas under four condition that no material was fi lled, used material was fi lled, new materials was fi lled and cleaned materials was fi lled in explosive pipe. The results show that compared with the used material and cleaned material, the average maximum explosion pressure was reduced by 21.62% and the average pressure rise rate decreased by 84.80%. The results show that the suppression performance of used aluminum alloy explosion-proof materials improved greatly after the used materials is cleaned. Keywords: Aluminum alloy explosion-proof materials, maximum explosion pressure, pressure rise rate, ultrasonic, free radical. Research article Introduction At present, the main barrier explosion-proof materials can be divided into three categories, namely metal, non-metal and composite. Metal barrier explosion-proof materials include mesh aluminum alloy, mesh titanium alloy, mesh copper alloy, mesh nickel alloy and foam metal material. Aluminum alloy is the most widely used metal barrier explosion-proof material; Non-metallic barrier explosion-proof materials are polyester, polyether, foam ceramics, etc. Among them, spherical non-metallic barrier explosion-proof materials are a new type of barrier explosion-proof materials, and mesh polyurethane foam is the most common non-metallic porous explosion-proof material, while foam Ceramic is the best insulation material. Composite barrier explosion protection technology is nanotechnology and coating technology. Early research on the mechanism of anti-explosion of barrier explosion-proof materials focused on the fi eld quenching in micro-scale space. (Holm, 1933; Birk, 2008) At present, the research on the explosion-proof mechanism of porous materials is relatively mature, but there is no unifi ed conclusion. The viewpoint focuses on the wall effect and cold wall effect of porous materials. The wall effect is that the fl ame collides multiple times on the surface of the explosion-proof material to cause the destruction of free radicals in the reaction, which leads to the termination of the combustion explosion reaction and prevents the explosion from continuing to spread. The cold wall effect is that after the fl ame enters the barrier explosion-proof material, since the barrier explosion-proof material has a large specifi c surface area, the energy of the reaction continues to be lost, and the temperature of the reaction system is lowered, thereby preventing further diffusion of the combustion explosion. (Chen, 2011; Hammel et al., 2014; Nan et al., 2001) pp. 14 - 20, DOI 10.35182/tses-2019-0002 Transactions of the VSB - Technical university of Ostrava Safety Engineering Series, ISSN 1805-3238 Vol. XIV, No. 1, 2019 15 The related experimental research on the mechanism of barrier explosion prevention mainly focuses on the fl ame propagation under the condition of explosion-proof and the overpressure distribution of the explosion shock wave, and explores the infl uence of the parameters such as the aperture, material, packing density and blanking rate of the explosion-proof material on the explosion process. The metal barrier explosion-proof material is mainly a porous material which is made of aluminum alloy as a base material and which is cut and stretched to form a honeycomb network structure. The metal barrier explosion-proof material not only has the advantages of explosion-proof, but also has the advantages of low volume replacement rate and low oil retention rate. The pressure of methane/air explosion decreases 50% when Al2O3-SiC foam ceramic is fi lled in the pipeline. (Nie et al., 2011) The quenching effect of porous nonmetallic materials fails under certain conditions induced by acceleration of fl ame by obstacles. (Wen et al., 2013) The difference of explosion suppression performance between metal and non-metal explosion-proof material, the effect of material on oil properties, compatibility of polyethylene blocking explosion-proof material with methanol, gasoline and liquid dangerous chemicals are researched and compatibility judgment method of non-metallic barrier explosion-proof material and dangerous chemicals is established. (Lu et al., 2014; Bo et al., 2017) Effect of porous material properties, fi lling density and geometric size on explosionproof barrier performance are studied. (Xing et al., 2015) Special three-dimensional mesh structure of foam ceramics is conducive to the destruction of free radicals in gas explosion. (Ma et al., 2013) When CO2 was added in the methane/air mixed gas, the binding reaction of methyl radicals initiated by methane explosion chain are promoted by CO2, the concentration of methyl radicals is reduced and the methane explosion chain is interrupted, which achieves the purpose of explosion suppression. (Luo et al., 2015) The consumption rate of CH4 is faster than that of O2 in the process of explosion. The molar fractions of free radicals of ·H, ·O and ·OH rise sharply during explosion, which instantaneously forms an activation center with very high concentration and promotes gas explosion. (Jia et al., 2017) The addition of water vapor promotes the formation of a large number of ·OH free radicals in gas explosion reaction, and reduces the production of ·H free radicals. Simultaneously, the total heat released by gas explosion reduces, which inhibits the propagation of gas explosion. (Li et al., 2017) The effect of various gases with different properties on gas combustion process is studied by establishing mathematical model of gas explosion in confi ned space. (Liang et al., 2017) In 2005, aluminum alloy mesh barrier explosionproof material was applied in the storage of hazardous chemicals including oil stations in China. After several years of use, the surface will foul and deposit oil, and the explosion-proof performance will be signifi cantly reduced. The cost of replacing the new barrier-proof material is too high. After cleaning the cleaned barrier explosion-proof material by ultrasonic wave, the cleaned aluminum alloy barrier explosion-proof material can be reused. Materials and methods Experimental system The experimental system is a premixed gas explosion pipeline system. The premixed gas explosion pipeline system is mainly composed of a visual premixed gas explosion pipeline, a gas distribution system, a transient explosion pressure system, and a high energy ignition system. The visual premixed gas closed explosion pipeline is mainly composed of a quartz glass pipeline, pressure sensors and a circulation pump. The glass pipeline has a length of 1000mm, an outer diameter of 104mm, an inner diameter of 100mm, and a wall thickness of 2mm. The volume of the gas explosion pipeline is 8L, and the maximum pressure is 2MPa. One side of the pipeline is sealed with a bolted fl ange, which is fi tted with an igniter interface, a vacuum gauge and an outlet pipe with a valve. The other side of the pipeline is sealed with a fl ange. The fl ange is controlled by a pneumatic valve. The fl ange can also be bolted. For the safety of the experiment, a rupture disk is installed on the fl ange. The critical pressure of the rupture disk is 0.8MPa. The structural diagram of the premixed gas explosion pipeline system is shown in Fig. 1. Test method The weight of the explosion-proof material fi lled with the explosion-proof material is 187g, so as to ensure that the explosion-proof material in the explosion pipeline has a packing density of 25kg/m3 and a fi lling rate of 95%. Leave 5% near the ignition head and fi ll the rest of the space. A certain length of aluminum alloy explosion-proof material is cut and rolled into a cylindrical shape with a diameter slightly larger than the inner diameter of the explosion pipe, and fully fi lled into the explosion pipe. After the airtightness check, the explosion pipeline is pumped to a vacuum state, and 0.8L pp. 14 - 20, DOI 10.35182/tses-2019-0002 Transactions of the VSB - Technical university of Ostrava Safety Engineering Series, ISSN 1805-3238 Vol. XIV, No. 1, 2019 16 Fig. 2 Explosion pressure/time curve of 10% methane-air gas unfi lled with barrier explosionproof material of methane is injected into the pipeline through the fl owmeter, and the air inlet of the explosion pipeline is connected to the atmosphere until the pipeline vacuum gauge reading back to 0MPa, and the pipeline intake valve is closed. The circulation pump was started, and the premixed gas was circulated in the explosion pipeline for 5minutes to complete uniform mixing of methane-air. Results Results of tests (1) Test of methane-air premixed gas explosion unfi lled with barrier explosion-proof material The pressure/time curve of the explosion of 10% methane-air premixed gas unfi lled with barrier explosion-proof material is shown in Fig. 2. 14 11 15 16 7 6 9 123 4 5 8 10 12 13 1# 3# 5# 2# 4# 6# 30cm 30cm 25cm Fig. 1 Structure diagram of the premixed gas explosion pipeline system; 1-non-metallic transparent material premixed gas explosion pipeline 2-transient pressure sensor 3-pneumatic valve 4-removable pneumatic valve control sealing fl ange 5-pneumatic valve controller 6-gas cylinder 7-rotor fl owmeter 8-three Through valve 9-circulation pump 10-air compressor 11-high energy ignition table 12-vacuum table 13-check valve 14-ignition head 15-transient pressure acquisition host 16-data acquisition computer 0 500 1000 1500 2000 0 100 200 300 400 500 Pressure/KPa Time/ms 1# 2# 3# 4# 5#  pp. 14 - 20, DOI 10.35182/tses-2019-0002 Transactions of the VSB - Technical university of Ostrava Safety Engineering Series, ISSN 1805-3238 Vol. XIV, No. 1, 2019 17 The pressure peak and pressure rise rate obtained by processing the pressure data are shown in Tab. 2. Tab. 2 Explosion pressure of 10% of methane/air gas fi lled with cleaned barrier explosion-proof material It can be seen from Tab. 2 that the maximum pressure of all sensors collected in the explosion pipeline is 87.459KPa, the minimum value is 32.550KPa, and the average pressure peak is 44.716KPa. The maximum pressure rise rate is 853.716KPa/s, and the minimum pressure rise rate is 106.192KPa/s. With the propagation of fl ame, the pressure rise rate tends to decrease gradually. (3) Test of methane-air premixed gas explosion fi lled with new barrier explosion-proof material The time/pressure curve of the explosion of 10% methane-air premixed gas with fi lled new barrier explosion-proof material is shown in Fig. 4. Fig. 4 Explosion pressure/time curve of 10% methane-air gas fi lled with new barrier explosionproof material The pressure peak and pressure rise rate obtained by processing the pressure data are shown in Tab. 1. Tab. 1 Explosion pressure of 10% methane/air gas unfi lled with barrier explosion-proof material It can be seen from Tab. 1 that the maximum pressure in the explosion pipeline is 416.579KPa collected by the 5# sensor, and the maximum pressure collected by other sensors is about 330KPa, and the average maximum pressure is 352.925KPa. The 5# sensor pressure rise rate is the largest, and the pressure rise rate of the 1# and 2# sensors close to the ignition head is almost the same. When the pressure is transmitted to the end of the pipeline, the pressure rise rate fl uctuates up and down, but the overall trend is decreasing. (2) Test of methane-air premixed gas explosion fi lled with cleaned barrier explosion-proof material The time/pressure curve of the explosion of 10% methane-air premixed gas with fi lled cleaned barrier explosion-proof material is shown in Fig. 3. Fig. 3 Explosion pressure/time curve of 10% methane-air gas fi lled with used barrier explosionproof material 0 500 1000 1500 2000 -20 -10 0 10 20 30 40 50 60 Pressure/KPa Time/ms 1# 2# 3# 4# 5#  0 500 1000 1500 2000 -60 -40 -20 0 20 40 60 80 100 Pressure/KPa Time/ms 1# 2# 3# 4# 5#  Sensor number Peak pressure/ KPa Rate of pressure rise/KPa/s 1# 346.875 834.448 2# 339.971 818.025 3# 332.737 761.412 4# 328.463 774.539 5# 416.579 997.837 Sensor number Peak pressure/ KPa Rate of pressure rise/KPa/s 1# 87.459 853.716 2# 33.866 281.064 3# 36.167 174.039 4# 32.550 148.722 5# 33.537 106.192 pp. 14 - 20, DOI 10.35182/tses-2019-0002 Transactions of the VSB - Technical university of Ostrava Safety Engineering Series, ISSN 1805-3238 Vol. XIV, No. 1, 2019 18 The pressure peak and pressure rise rate obtained by processing the pressure data are shown in Tab. 4. Tab. 4 Explosion pressure of 10% methane-air gas fi lled with barrier explosion-proof material cleaned by ultrasonic It can be seen from Tab. 4 that the maximum pressure in the explosion pipeline is 61.484KPa, the minimum value is 27.285KPa, and the average pressure peak is 35.048KPa. The maximum pressure rise rate is 148.535KPa/s and the minimum pressure rise rate is 20.919KPa/s. Analysis of test results Through the analysis of the maximum pressure data of 10% concentration methane-air premixed gas explosion under the four conditions: unfi lled barrier explosion-proof material, fi lled cleaned barrier explosion-proof material, fi lled with new barrier explosion-proof material, and fi lled barrier explosion-proof material cleaned by ultrasonic. Compared with the cleaned barrier-proof explosionproof materials, the average explosion pressure of the new barrier-proof explosion-proof materials is reduced by 34.41%, and the average pressure rise rate is reduced by 85.12%, indicating that the performance of aluminum alloy barrier explosion-proof material reduced seriously after it was soaked by oil for many years. Compared with the cleaned barrier-proof explosion-proof materials, the average explosion pressure of the barrier-proof explosion-proof materials cleaned by ultrasonic is reduced by 21.62%, and the average pressure rise rate is reduced by 84.80%, which indicates that the explosion-proof performance of used barrier explosion-proof material reduces dramatically because of corrosion. Compared with the barrier-proof explosion-proof materials cleaned by ultrasonic, the average explosion pressure of the new barrier-proof explosion-proof materials is reduced by 16.32%, and the average pressure rise rate is reduced by 2.13%. It shows that the explosion performance of the cleaned aluminum alloy barrier explosion-proof material cleaned by ultrasonic is similar to the explosion-proof performance of The pressure peak and pressure rise rate obtained by processing the pressure data are shown in Tab. 3. Tab. 3 Explosion pressure of 10% methane/air gas fi lled with new barrier explosion-proof material It can be seen from Tab. 3 that the maximum pressure in the explosion pipeline is 51.62KPa, the minimum value is 15.782KPa, and the average pressure peak is 29.328KPa. The maximum pressure rise rate is 132.811KPa/s and the minimum pressure rise rate is 18.251KPa/s. (4) Test of methane-air premixed gas explosion fi lled with barrier explosion-proof material cleaned by ultrasonic The time/pressure curve of the explosion of 10% methane-air premixed gas with fi lled barrier explosion-proof material cleaned by ultrasonic is shown in Fig. 5. Fig. 5 Explosion pressure/time curve of 10% methane-air gas fi lled with barrier explosion-proof material cleaned by ultrasonic 0 500 1000 1500 20 0 -40 -20 0 20 40 60 Pressure/KPa Time/ms 1# 2# 3# 4# 5# Sensor number Peak pressure/ KPa Rate of pressure rise/KPa/s 1# 51.620 132.811 2# 16.440 18.874 3# 15.782 17.269 4# 43.729 46.051 5# 19.070 17.656 Sensor number Peak pressure/ KPa Rate of pressure rise/KPa/s 1# 61.484 148.535 2# 28.605 22.208 3# 27.285 20.919 4# 28.276 21.669 5# 29.591 24.397 pp. 14 - 20, DOI 10.35182/tses-2019-0002 Transactions of the VSB - Technical university of Ostrava Safety Engineering Series, ISSN 1805-3238 Vol. XIV, No. 1, 2019 19 an important role in suppressing gas explosion pressure. Compared with fi lling new materials and cleaned materials, the peak pressure of premixed gases explosion fi lled with cleaned barrier explosion-proof materials is about 20KPa higher. It shows that the explosion suppression performance decreases with the prolongation of the time of barrier explosion-proof materials. The peak pressure of the pre-mixed gas explosion is basically the same when the new material and cleaned material is fi lled, which indicates that the anti-explosion performance of the material after cleaning basically reaches the anti-explosion performance of the new material. It can be seen from Fig. 7 that in four cases, the pressure rise rate at the 1# sensor near the ignition head is the maximum value, wherein the maximum pressure rises in the case of not fi lling the barrier explosion-proof material and fi lling the cleaned barrier explosion-proof material. The rate is above 800KPa/s. In the case of fi lling the new barrier explosion-proof material and the explosion-proof material cleaned by ultrasonic, the explosion pressure rise rate curve is basically consistent, the maximum pressure rise rate is very close, both are less than 200KPa/s, and the pressure rise rate measured by other sensors is less than 30KPa/s. The pressure rise rate at 1# sensor is much higher than the pressure rise rate at other sensors because the 1# sensor is close to the ignition head. In order to ensure that the premixed gas can be ignited smoothly, leave 5cm at the ignition head end, and the explosion of the empty space is suffi cient. The explosion caused the pressure collected at the 1# sensor to be larger. Discussion Wall effect is one of the mechanisms of anti-explosion of barrier explosion-proof materials. The wall effect is that the fl ame collides multiple times on the surface of the explosion-proof material to cause the destruction of free radicals in the reaction, which leads to the termination of the combustion explosion reaction and prevents the explosion from continuing to spread. The surface of the explosion-proof material is polluted by oil and oil sludge. And scale is formed on the surface which can affect the wall effect signifi cantly. ·O, ·H, ·OH, ·HO, ·HCO are key free radicals in gas explosion chain reaction. After the aluminum alloy explosionproof materials is cleaned by ultrasonic, the scale on surface disappears. The free radical consumption rate increases and the growth rate of free radicals decreases which terminate chain reaction. the new barrier explosion-proof material. It can be seen from the above analysis that the inhibitory effect of the barrier explosion-proof material on the pressure rise rate is signifi cantly greater than the suppression effect on the maximum pressure. In the four cases, pressure and pressure rise rate of 10% methane/air premixed gas explosion measured by different sensors are shown in Fig. 6 and Fig. 7 separately. Fig. 6 Peak pressure of each sensor with 10% concentration of methane/air premixed gas in four cases Fig. 7 Pressure rise rate of each sensor with 10% concentration of methane/air premixed gas in four cases It can be seen from Fig. 6 that when no barrier explosion-proof material is added in the pipeline, the peak pressure of premixed gas explosion is much higher than that of other three cases, which indicates that barrier explosion-proof material plays 0 200 400 600 800 1000 1# 2# 3# 4# 5# Rateofpressurerise˄ ˄ KPa/s ˅ No.ofsensor nomaterial usedmaterial newmaterial cleanedmaterial 0 50 100 150 200 250 300 350 400 450 1# 2# 3# 4# 5# Peakpressure(KPa) No.ofsensor nomaterial usedmaterial newmaterial cleanedmaterial ˄˅ pp. 14 - 20, DOI 10.35182/tses-2019-0002 Transactions of the VSB - Technical university of Ostrava Safety Engineering Series, ISSN 1805-3238 Vol. XIV, No. 1, 2019 20 References A.M. Birk. 2008. Review of expanded aluminum products for explosion suppression in containers holding fl ammable liquids and gases. Journal of Loss Prevention in the Process Industries, 21: 493-505. DOI: 10.1016/j. jlp.2008.04.001. B.S. Jia, C.M.Li, B.Yin, et al. 2017. Computing study on multivariate mixed gas burning by CHEMKIN-PRO software. Journal of China Coal Society, 42(3): 646-652. DOI: 10.13225/j.cnki.jccs.2016.0728. B.S. Nie, X.Q. He, R.M. Zhang, et al. 2011. The roles of foam ceramics in suppression of gas explosion overpressure and quenching of fl ame propagation. Journal of Hazardous Materials, 192: 741-747. DOI: 10.1016/j.jhazmat.2011.05.083. C.B. Lu, X.D. Zhu, H.Z. Wang, et al. 2014. Comprehensive evaluation on explosion proof performance of non-metallic barrier and explosion proof material. Journal of Safety Science and Technology, 10(12): 125-130. DOI: 10.11731/j.issn.1673-193x.2014.12.021. Chen S. 2011. Application of inherent safety explosion-proof technology in oil storage & transportation device. Procedia Engineering, 15: 4814-4818. DOI: 10.1016/j.proeng. 2011.08.899. Hammel E C, Ighodaro OLR, Okoli O I. 2014. Processing and properties of advanced porous ceramics application based review. Ceramics International, 40(10): 15351-15370. DOI: 10.1016/j.ceramint.2014.06.095. Holm J M. 1933. On the ignition of explosive gaseous mixtures by small fl ames. Philosophical Magazine Series 7, 15( 98): 329-359. DOI: 10.1080/14786443309462190. K. Ma, Z.P. Ma, J.F. Zhang, et al. 2013. Chain scission of gas explosion reaction in foam ceramics. Mineral Engineering Research, 28(2): 33-36. DOI: 10.3969/j.issn.1674-5876.2013.02.008. X.C. Li, B.S. Nie, C.L. Yang, et al. 2017. Effect of Gas Concentration on Kinetic Characteristics of Gas Explosion in Confi ned Space. Chinese Journal of High Pressure Physics, 31(2): 135-147. DOI: 10.11858/ gywlxb.2017.02.005. X.F. Bo, C.B. Lu, X.D. Zhu, et al. 2017. Research on chemical compatibility of HDPE explosion suppression material with M85 Methanol gasoline. Petrochemical Safety and Environmental Protection Technology, 33(4): 38-41. DOI: 10.3969/j.issn.1673-8659.2017.04.010. X.P. Wen, M.Z. Xie, M.G. Yu, et al. 2013. Porous media quenching behaviors of gas defl agration in the presence of obstacles. Experimental thermal and fl uid science, 50:37-44. DOI: 10.1016/j.expthermfl usci.2013.05.002. Y.T. Liang, L.C. Wang, H.Z. Luo, et al. 2017. Computational model of reaction kinetic for gas explosion induced by shock wave. Journal of China Coal Society, 42(6): 1475-1481.DOI: 10.13225 / j.cnki.jccs.2016.1276. Z.J. Nan, A.Y. Song, F.H. Cao, et al. 2001. Study on explosion suppression properties of aluminum mesh material. Ordnance Material Science and Engineering, 24 (4):19-22. DOI: 10.3969/j.issn.1004-244X.2001.04.006. Z.M. Luo, K. Kang. 2015. Simulative analysis of microscopic mechanism of CO2 inhibiting methane-air chain explosion. China Safety Science Journal, 25(5): 42-48. DOI: 10.16265/j.cnki.issn1003-3033.2015.05.008. Z.X. Xing. Z. Du, H.X. Ou, et al. 2015. Study on fi re resistance-explosion proof performance of novel porous non-metallic material. China Safety Science Journal, 25(7): 74-79. DOI: 10.16265/j.cnki.issn10033033.2015.07.012. (3) The inhibitory effect of the barrier-proof material on the rate of pressure rise is signifi cantly greater than the suppression effect on the maximum pressure. Acknowledgments This work is fi nanced from Beijing Natural Science Foundation Committee (No. 2162016), Beijing Municipal Education Commission (No. KM201910017001), Research and Training Programs for College Students in Beijing (No. 2019J00091). Conclusion (1) After being used for many years, the aluminum alloy barrier explosion-proof material is oxidized by the oil, and the explosion-proof performance is seriously degraded. (2) The explosion performance of the cleaned aluminum alloy barrier explosion-proof material after ultrasonic cleaning is greatly improved, and the explosion-proof performance is similar to the new barrier explosion-proof material. pp. 14 - 20, DOI 10.35182/tses-2019-0002