Experimental Study On Characteristics Of Catalytic Reaction At Low And Medium Temperature And Micro-combustion Of Ethane

In this paper,in the condition of constant temperature preheating system and self stabilizing combustion system,catalytic combustion characteristics are discussed in quartz with inradium of 4mm and with Pt/ZSM-5 as catalyst.The effect on catalytic combustion of ethane of the equivalence ratio and the inlet velocity is compared.Catalytic combustion Characteristics of ethane such as,the conversion rate and product selectivity,combustion efficiency,reaction temperature are dicussed.In the constant temperature preheating experiment,carbonaceous product ethane catalytic combustion is mainly carbon dioxide,ethylene and carbon monoxide.Large equivalence ratio,large inlet velocity and large preheating temperature is conducive for the production of ethylene.When the equivalence ratio is 2.5,the flow rate is 0.2?0.5m/s,the production of carbon monoxide in the selectivity reached a maximum of up to 50%.In the lean burn area or stoichiometric conditions,conversion rate of ethane can reach as high as 90%and decreases significantly in the fuel rich region.When the inlet velocity is about 0.2m/s,the conversion rate reaches the maximum.At the flow rate greater than 0.2m/s,the conversion rate unchanges while the reaction temperature decreases first and then increases;In the lean burn area,the increase of the equivalence ratio and the inlet velocity makes the top temperature point along the path of burner moves upstream,while the effect of inlet velocity on the temperature along the path of burner is small,the highest temperature appears at the entrance of catalyst.In the self stabilizing combustion experiment,the lean burn limit equivalence ratio?lean and the fuel rich limit equivalence ratio ?rich under the inlet velocity range of 0.1-3m/s are measured.?lean is varied between 0.9-0.6 and decreases with the increase of the flow velocity;and ?rich is varied between 20-7 and decreases with the increase of the flow velocity.In terms of products,ethylene is less than 1%under all operating conditions.With the increase of equivalence ratio,the selectivity of ethylene increases firstly and then decreases.The greater the flow rate is,the greater the selectivity of ethylene is.Under the influence of external preheating,the selectivity ofCO is basically reaches the top at ?=1.55 and then decreases with the increase of ?.Methane appeares in the product at the flow velocity of 0.2 and 0.5m/s,but the content is very low.The maximum conversion rate of all working conditions is not more than 80%,and appears at the flow rate of 0.1 m/s and ?=0.9.Basically,the conversion rate of ethane at each flow rate decreases with the increase of the equivalence ratio in the lean burn zone,and decreases with the increase of the equivalent ratio in the rich combustion zone.The maximum wall temperature Tmax and the average wall temperature Tave increase with the increase of the equivalence ratio and the flow velocity.The wall heat dissipation power Qsurf increases with the increase of flow velocity.The rate of wall heat loss Qsurf/Qin decreases with the increase of flow velocity.Comparison of constant temperature preheating experiment and self stablizing combustion experiment,it is found that with the preheating of the external heat source,methane can not be generated;The maximum value of the ethylene selectivity changes not much;CO selectivity of self stablizing experiment is greater than it in constant temperature preheating experiment.The conversion rate in the constant temperature preheating experiment is also higher.Preheating can promote the catalytic combustion of ethane.For the reaction temperature,the reaction temperature of all working conditions under the preheating condition is above 500?,which is generally higher than that in the self stablizing experiment.For the burning limit of lean burn,n-butane<ethane<methane.The fuel rich burning limit of methane,ethane and n-butane all decrease with the increase of flow velocity.