基于VSP2的引发剂质量分数对醋酸乙烯聚合反应失控特性及安全泄放设计影响研究

为了解决醋酸乙烯聚合反应失控所引起的超压问题,通过VSP2绝热量热仪研究了醋酸乙烯聚合反应的失控特性,并通过Leung's法对某醋酸乙烯聚合反应器的安全泄放面积进行了计算;然后,在其他条件不变的情况下,研究引发剂质量分数对失控特性和泄放面积的影响,结果表明,引发剂质量分数对反应总放热量的影响不大,体系绝热温升为105~115℃;但引发剂质量分数越大,失控反应的最大温升速率和最大压升速率越大。这是因为引发剂质量分数越大,在相同泄放压力和最大累积压力下,单位质量反应物的放热速率就越大,也就需要更大的泄放面积;最后,引入无量纲数W~*、G~*和A~*,拟合出它们与引发剂质量分数X*的关系式,结果表明,在研究范围内所需安全泄放面积随引发剂质量分数线性增大。

Impact of the initiator mass fraction on the resulted runaway reaction features of the vinyl acetate polymerization and the safety ventilation design via VSP2

The paper is inclined to present a design project for the relief system to evade the overpressure induced by the reaction runaway of vinyl acetate polymerization which is known as a great risk for the reactor design and operation.In order to identify and determine the reaction runaway characteristics of the relief system and its size,we have managed to conduct a series of the runaway reactions of the vinyl acetate polymerization by using a VSP2 (Vent Sizing Package 2) adiabatic calorimeter imported from abroad.The emergency relief system of the specified vinyl acetate polymerization reactor we have developed has been designed by using Leung's method and the experimental testing data while we were making efforts in investigating the effects of the initiator mass fraction on the runaway reaction characteristics and on the safety relief size.The results of our research indicate that the initial exothermic temperature of the vinyl acetate polymerization should be kept at about 80 ℃.The adiabatic temperature rise of the reaction runaway system should be kept between 105 ℃ and 115 ℃.With the increase of the initiator mass fraction,both the maximum rate of temperature rise and the maximum rate of pressure rise are actually quite large.Judging by the experimental data,the emergency relief system for the said vinyl acetate polymerization runaway reaction is by nature a vapor system.In accordance with the Emergency Relief System (ERS) method offered by the Design Institute,the relief flow rate,the relief capacity,as well as the relief area for a specified vinyl acetate polymerization reactor can be determined by the Leung method and ERM.The emergency relief area tends to increase with the increase of the initiator mass fraction due to its prompt heat release characteristics at a fixed relief pressure and a specified maximum cumulative one.And,finally,the paper has also introduced the three target dimensionless parameters,that is,W*,G* and A* and an independent dimensionless parameter X*,indicating the initiator mass fraction.The algebraic equations of W*,G * and A * with X * prove to be fit for the said signs according to the experimental data.The fitting equations imply that the emergency relief area increases linearly with the initiator mass fraction under the proper experimental conditions.