高温高压条件下可燃性气体爆炸极限的试验研究

Experimental test on the explosion limit of the combustible gas at high temperature and pressure

注空气采油技术是一种重要的采油方法,在注空气采油过程中容易形成可燃性气体混合物,在地层高温高压环境下有发生火灾或爆炸事故的可能性。为了保证注空气采油过程的安全性,需要对高温高压条件下可燃气体的爆炸特性进行研究。设计了一种测定高温高压条件下可燃气体爆炸极限的试验系统,通过试验研究了采油现场实测可燃气体混合物在40-60℃和1-10 MPa下的爆炸极限,同时利用经验公式对可燃气体混合物的爆炸极限进行了理论估算。结果表明,压力对爆炸上限的影响很大,高压下尤为明显,在高压状态下,温度的影响比常压下更为明显,10 MPa、120℃的爆炸上限高达50. 6%。而温度和压力对爆炸下限的影响很小。

In this paper, the author has made efforts in developing a well-efficient device for testing the maximum explosion limit of the flammable gases under the elevated temperature and pressure conditions so as to be able to identify and determine the explosion limit of the combustible gas under the said high temperature and pressure. To achieve the said purpose, we have first of all analyzed and determined the explosion limit of the measured combustible gas mixtures under the normal temperature and at-mospheric pressure by using Le Chatelier formula. And, next, we have managed to work out the empirical formula through calculating the explosion limit at different temperature conditions in ho- ping to improve the gas injection efficiency remarkably by separately the natural gas and the air to be injected into the device. And, then, the combustible gas and the air can be injected into the device consequentially by a partially pressure method to be ignited. According to the pressure change in the reactor, it would be possible to judge whether there occurs an explosion. The resuits of the test may indicate that the pressure rise may have been caused by the strength of the explosion, if it could be strong enough to be beyond 3 MPa and the concentration of combustible gas in the reactor may reach the equivalent concentration. To be exact, when the concentration can gradually increase, with its pressure growing enough till the explosion can gradually decrease and finally get stabilized. However, the upper explosion limit un- der high pressures would be getting much higher than that of the normal pressure. For example, in the conditions under study, it would be possible for the ultimate explosion limit to increase by the ratio of 35%, though the effect of pressure on the lower explo- sion limit can remain weak. In addition, under high pressures, the effect of temperature on the upper explosion limit proves to be more significant than under normal pressure, with the effect of the temperature on the lower explosion limit being not very great. Therefore, the results of this paper indicate that it is necessary to monitor the content of the flammable gas strictly in the air injection oil production site and control the outside of the explosion limit to ensure the safety of the explosion process.