| Titanium powder is mainly for raw materials of powder metallurgy,also used in electric vacuum pump source,electric vacuum solid pump source,plastic filling agent,surface coating materials,aircraft parts,and for making all kinds of titanium compound.It’s application field is very wide.Titanium powder,belongs to dangerous goods,is easy to oxidize,combustion and explosion.Dust explosion poses a great threat to people,property and environment.Therefore,Studying the explosive parameters and evaluating the explosion risk of titanium powder is provide theoretical basis for preventing titanium powder explosion during production,transportation and processing.The main research contents and conclusions as follows:(1)The hartmann tube was used in experiment with the spherical titanium powder of five different particle sizes.Fitting out the function between the minimum ignition energy(MIE)and concentration,particle size,and the function between the sensitive concentration and the particle size.The results show that:The sensitive concentration of the titanium powder corresponding to the average size of 18μm,25μm,38μm,48μm and 74μm are respectively 700g/m3,750g/m3,800g/m3,800g/m3 and 850g/m3;The minimum ignition energy were 33.2mJ,38.1mJ,41.3mJ,44.3mJ and 67.4mJ respectively;The minimum ignition energy decrease first and then increase with the increase of concentration in the form of quadratic function,and increase with the increase of the particle size in the form of quadratic function;The sensitive concentration is positively related to the particle size of titanium powder;The sensitivity of turbulent flow index is negatively related to the dispersion pressure;When the dispersion pressure is constant,the larger the particle size,the greater the sensitivity of the turbulent flow index;When the turbulent flow index is constant,theLarger the particle size of titanium powder,the greater the sensitive value of the dispersion pressure.(2)The 20L spherical vessel was used in explosion experiment of spherical titanium powder of five different particle sizes.Fitting the function of tendency of maximum explosion pressure(Pmax)and maximum explosion index(Kmax)influenced by titanium particle size and concentration,and then fit the function of tendency of the sensitivity concentration of Pmax and Kmax and lower explosive limit(LEL)influenced by titanium particle size.The results show that:Pmax of the titanium powder corresponding to the average size of 18μm,25μm,38μm,48μm and 74μm are respectively 0.662MPa,0.619MPa,0.574MPa,0.497MPa and 0.263MPa;Sensitivity concentration are respectively 700g/m3,750g/m3,800g/m3,800g/m3 and 850g/m3;Kmax are respectively 22.35MPa-m/s,14.76MPa·m/s,11.72MPa·m/s,9.7MPa·m/s and 7.41MPa·m/s;Sensitivity concentration are respectively 800g/m3,950g/m3,950g/m3,1000g/m3 and 1200g/m3;The sensitivity concentration and sensitivity turbulence index of Kmax are equal or higher than those of Pmax;As particle size increases,Pmax decrease in the form of quadratic function,while Pmax decrease in the form of exponential function,and the sensitivity concentration and LEL of Pmax and Kmax increase in the form of Linear function;As the concentration of titanium powder increase,Pmax and Kmax increase at first,and then decrease in the form of quadratic function.(3)The Godbert-Grenwald furnace and minimum ignition temperature of dust layer testing apparatus were used to investigate minimum ignition temperature of dust cloud(MITC)and minimum ignition temperature of dust layer(MITL)of the spherical titanium powder with five different particle sizes.The function between MITC-MITL and particle size,and the function between MITC and concentration were fitted.The results showed that:MITC of the titanium powder corresponding to the average size of 18μm,25μm,38μm,48μm and 74μm are respectively 482℃,498℃,530℃,567℃ and 647℃;MITL of which are respectively 430℃,440℃,460℃,470℃ and 480℃;The increase of spray pressure has no obvious effect on the ignition temperature of titanium dust cloud,the increase of mass concentration makes MITC decrease firstly and then increase in the form of quadratic function;The increase of particle sizes make MITC increase in the form of quadratic function,and make MITL increase in the form of exponential function;MITC is higher than MITL when the particle sizes is the same.(4)The explosive risk assessment of 5 types of titanium powder was evaluated by the composite index Method,the German explosion index method,the original Soviet evaluation method and the Chinese dust explosion hazard analyze framework method.Because that different evaluation methods have different criteria,the results are not consistent.However,in general,the ignition sensitivity of titanium powder is low and the explosion intensity is high,and the explosion risk of titanium powder increases with the increase of its particle size. |
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