Numerical Analysis For The Inhibition Of Phosphorus-containing Compounds On Methane Flame

Energy and environmental problems are becoming more and more prominent in the rapid development of the global economy.Therefore,the research on combustion safety and clean extinguisher is getting more and more attention.The halogenated fire suppressants,which have been used for many years,have been gradually forbidden to be produced and used.In the study of new and efficient fire extinguishing agent,the phosphorus inhibitors are being widely used because of their characteristics such as high efficiency,low smoke,non-toxic,halogen-free and so on.It has also become a hot spot for researchers.At present,a lot of research has been carried out on the mechanism of flame in-hibition of phosphorus-containing compounds.However,recent studies have found that the phosphorus-containing inhibitors can not inhibit the combustion of flame in ex-tremely poor combustion environment,but show the effect of enhancing combustion,which brings great potential threat to fire prevention as well as fire fighting and res-cue.The inhibitory effect of a flame inhibitor is the result of a comprehensive effect of physical and chemical effects.The physical effect generally inhibits the combustion by endothermic cooling and dilution,and the chemical effect,which destroys the hain reactions of combustion by reorganizing the H and OH in the flame to extinguish the fire,is dominant in the inhibition of phosphorus inhibitors.So,under the condition of extreme poor combustion,where the phenomenon of the enhanced combustion comes,which reaction works,are worth studying.In addition,as a chemical flame inhibitor,we have been concerned about its chemical effect and chemical reaction mechanisms,ignoring the physical effect of phosphorus inhibitors,and not further exploring the two sides of the chemical effect.At the same time,because the experimental method can not effectively separate the physical effect from the chemical effect,it is more difficult to study the chemical effect in depth and even to decouple.With the rapid development of gas-phase chemical reaction dynamics and computer level,the numerical simulation method combined with the detailed chemical reaction kinetics mechanism has been able to accurately calculate and predict the fine structure and combustion characteristics of low dimensional laminar flame.It has become a research method commonly used in the current combustion chemistry.Due to the complexity of turbulent combustion,laminar flow combustion is currently used to study the mechanism and model of chemical re-action kinetics.Therefore,the effect of phosphorus inhibitor on the premixed flame of methane laminar flow is studied by the method of numerical calculation,the physical and chemical effects of phosphorus inhibitors are separated effectively,and the chemi-cal effect is further decoupled.First of all,the CHEMKIN PRO software combined the detailed chemical reac-tion kinetics mechanism with DMMP as an example is used to compare the chemical inhibition process of the phosphorous inhibitor for lean and rich methane-air flames.It is found that the inhibitory effect of DMMP on the methane flame is mainly through the two catalytic cycles of PO2(?)HOPO and PO2(?)HOPO2 to promote the recombi-nation of H and OH in the combustion reaction zone,and the former is more efficient.Therefore,the phosphorus-containing inhibitor has better effect on the fire suppression of rich flame.Secondly,the primary pyrolysis products of phosphorus inhibitors are divided into phosphorous-containing component and hydrocarbon component,and the phenomenon of enhanced combustion of phosphorus-containing inhibitors under ex-tremely poor combustion conditions is studied for a reasonable explanation.Finally,by interfering with the chemical reaction process of the reaction in the chemical reac-tion chain and introducing inert substances,the physical and chemical effects of the phosphorus inhibitor are effectively separated,and the method of replacing the initial inhibitors with the small molecules,which are the main catalytic agents in the pyrolysis products,is innovatively proposed to decoupled the total chemical effects of phospho-rus compounds into two parts:pyrolysis and catalytic effects,and then the interactions of each part effect under different conditions are compared.It is observed that the phys-ical effect is always in the flame suppression area.The promoting effect become the dominant factor for the reaction process when the equivalence ratio is smaller than 0.6 and the amount of the inhibitor is not more than 2%.In this lean-burn condition,the exothermic reactions were faster than the others within the reaction chains due to the reduction of radical recombination in hydrocarbon oxidation.The results are believed to be useful for the mechanism research and the further application and improvement of flame inhibitors.