Mixed gases explosive limits

ABSTRACT Currently on combustible gas safety studies mostly for single gas, and the study of multivariate mixed gases is less, only a handful of concentration explosive limits data reports . This article proposes a application security research program about mixing two different sources, mine gas and fire-reversed stove gas which makes a detail about the theoretical analysis of the program feasibility, the determination method of mixed gas explosion limit, and the process of using test unit to test determination. Finally, it introduces the safety measures, which should be taken in practical apphcation. 

METHYLPROPYLAMINE (13952-84-6) C4H,o Highly flammable gas [explosion limits in air (vol %) 1.9 to 8.5 flash point -76°F/-60°C cc autoignition temp 550°F/288°C Fire Rating 4]. Reacts with oxidizers, strong acids strong bases. Mixed with oxygen this substance will explode on contact with nickel carbonyl in the... 

Whether the combustible gas in the air will explode or not when it meets fire, which is associated with combustible gas concentration. This range is called explosion limit. We call the lowest concentration of combustible gas in the air explosion when it meets fire (in volume percent) the lower explosive limit highest combustible gas concentration said the explosion limit. To avoid mixed gas exploding, we should find the gas explosive limits of each component. 

Let s now mm attention back to the flammability limit itself. When small increments of a combustible gas are successively mixed with air, a concentration is finally attained in which a flame will propagate if a source of ignition is present. This is referred to as the Lower Flammable Limit (LFL or lower explosion limit) of the gas in air. As further increments of the gas are added, a higher concentration of flammable gas in air will finally be attained in which... 

As vent collection systems normally contain vapor/air mixtures, they are inherently unsafe. They normally operate outside the flammable range, and precautions are taken to prevent them from entering it, but it is difficult to think of everything that might go wrong. For example, an explosion occurred in a system that collected flarmnable vapor and air from the vents on a number of tanks and fed the mixture into a furnace. The system was designed to run at 10% of the lower explosion limit, but when the system was isolated in error, the vapor concentration rose. When the flow was restored, a plug of rich gas was fed into the furnace, where it mixed with air and exploded [17]. Reference 34 describes ten other incidents. 

If a significant volume of gas (caused by a leak, for example) is exposed to an ignition source and this gas is mixed with air in proportions that are close to stoichiometric, the gas cloud can cause a lot of damage when it gives rise to a detonation. The accident at Flixborough is one example. The lower explosive limit of hydrocarbons is extremely low. If the carbon chain length exceeds 8, the autoinflammation temperature of a linear hydrocarbon is close to 200°C. All these parameters decrease with pressure. The table below shows to which extent pressure influences the AIT of ethylene ... 

A simplified process flow diagram of the ethylene-based vinyl acetate process is shown in Figure 20 [25]. Acetic acid feedstock is vaporized in the presence of fresh ethylene feed and unreacted ethylene recycle gas in the acetic acid vaporizer. The stream is preheated and high purity oxygen is added with a special mixing nozzle. The quantity of reactants and oxygen are carefully controlled to ensure that the mixture is outside of the explosive limits. 

Firstly, we should make sure the proportion and form of the mixed gas. Secondly, we should benchmark the gas components. In other words, we convert it to pure gas composition, no air base composition and the gas composition. Thirdly, we should find out the explosion limit of the unit gas. Fourthly, we should calculate the explosion limit of the pure combustible gas, no air flammable gas. Fifthly, we should calculate the overall gas (including gas, inert gases (C02,N2) and air) explosion limit in the air. 

---