Study On Explosion Limits And Autoignition Temperatures Of Methanol-gasoline Blends

It is one of the most important measures to promoting vigorously the use of methanolgasoline blends to solve the energy shortage and environmental pollution problems. However, methanol-gasoline blends, as flammable and explosive chemical, have a high combustion and explosion hazard in the process of allocation, storage, use and so on. There may be a serious blasting accident with a slight mistake.To assess the burning and explosion characteristics of methanol-gasoline blends, the FRTA explosion limit instrument and AIT551 autoignition temperature instrument were respectively used to test explosion limits and autoignition temperatures of samples being mixtures of 93# gasoline and methanol liquid. An effect of methanol concentration and that of sample volume on the explosion limits, autoignition temperatures and the delay time of the samples were analyzed. The research achievements show that:(1) The lower explosion limits of M0, M15, M30, M50, M65, M85 and M100 methanol-gasoline blends are 1.129%, 1.716%, 2.252%, 3.088%, 3.952%, 5.490% and 6.523% respectively. The lower explosion limits of methanol-gasoline blends rise with the increase of methanol concentration. Moreover, the rate of increase of the lower explosion limits increases.(2) With the initial temperature from 25°C to 100°C, the lower explosion limits of M50, M85 methanol-gasoline blends decrease respectively from(3.555%, 5.991%) at 25°C to(3.002%, 5.294%) at 100°C. With the increase of methanol concentration, the effect of temperature on the lower explosion limits increases. Compared with M50 and M85, the temperature has little influence on the lower explosion limit of M15 methanol-gasoline blend.(3) In the temperature range from 40°C to 120°C, the upper explosion limit of M15 methanol-gasoline blends changes between 11.253% and 11.451%. Considering the test error and test precision, it can be approximated that the upper explosion limit of M15 methanolgasoline blend is almost not affected by temperature.(4) The autoignition temperatures of M0, M15, M30, M50, M65, M85 and M100 methanol-gasoline blends are 323°C, 375°C, 405°C, 420°C, 427°C, 439°C and 443°C respectively. With the increase of methanol concentration, the autoignition temperatures of methanol-gasoline blends increase, and the rate of increase gradually decreases.(5) In a certain concentration range(sample volume from 50μL to 300μL), with the increase of the sample concentration, the autoignition temperature of M15 methanol-gasoline blend decreases at first and then tends to be stable. When the sample volume is 150μL, the autoignition temperature reaches minimum 375°C. However, when the sample volume is more than 150μL, sample concentration has practically no influence in the autoignition temperature of M15 methanol-gasoline blends.(6) The delay times of M0, M15, M30, M50, M65, M85 and M100 methanol-gasoline blends are 7s, 9s, 18 s, 36 s, 51 s, 62 s and 67 s respectively. With the increase of methanol concentration, the delay times of methanol-gasoline blends become longer. In addition, the effect of the delay time by methanol concentration gradually decreases with the increase of methanol concentration.(7) Compared with the effect of methanol concentration on the delay time, and considering the influence of experimental error, it can be approximated that the sample concentration has little influence on the delay time of M15 methanol-gasoline blends.