Experimental Study On The Combustion Performance Of Fully Premixed-type Burner In Gas Appliances

Natural gas is a clean energy source. With the rapid economic progress andenergy structure optimizing adjustment, as well as facing the pressure of pollution inChina, natural-gas markets have entered a period of rapid growth. Terminal devicesusing fuel gas that have become further diversified and complex. The market share offully premixed burners is gradual increase. The key index of the gasinterchangeability and gas appliance flexibility which could adjust to the atmosphericcombustion type, whether could adjust to the fully premixed combustion type, it isnecessary to conduct some experimental verifications, moreover people increasinglyattach importance to the interchangeability of gas because of the multiple source ofgas for the city gas, therefore the interchangeability indexs for the fully premixedcombustion type were researched in this paper.First, the research methods and results of gas interchangeability for majorcountries in the world were analyzed and summarized, and from the aspects of ejectorcharacteristic in the fully premixed gas appliances, the combustion characteristics forthe fully premixed gas appliances were theoretically analyzed.Then, based on the combustion properties of the fully premixed gas appliances,and combined these commonly characteristic parameters which could reflect thecombustion properties for gas, such as high Wobbe index (Ws), low Wobbe index (Wi),high heat value (Hs), low heat value (Hi), combustion potential (CP), combustionvelocity (Sn), theoretical air requirement (V0) and yellow flame index (IY), this paperconfirmed about five combinations through analyzing and calculating:(Ws, Hi),(Ws,V0),(Ws, CP),(Hi, Sn),(V0, Sn); they would be tested as the interchangeability indexsfor the fully premixed combustion type.Finally, a displacing gas was confected by utilizing hydrogen, nitrogen,isobutene, that so-called three-component volumetric method, the reference gas andthe displacing gas were burned on an experimental system of fully premixedcombustion. Based on the combustion results, we researched the changes ofcombustion properties for the fully premixed gas appliances when gas compositionwas varied, and ascertained the major parameters of combustion characteristic whichcould affect the interchangeability of gas and flexibility of gas appliance, and proposed appropriate interchangeability index for the fully premixed gas appliances.From the aspects of energy efficiency indexs, combustion conditions and flue gasemission, the experiment results showed that:(1) From the aspect of changes of gas combustion characteristic indexs, when thevalues of Wsand Hifor a displacing gas were remained the same or extremityapproximate with a reference gas, with the exception of the values of CP, V0and Snfor a displacing gas had much more changed relative to the displacing gas, otherparameter values were changed in the range of2%.(2)(Hi, Sn) and (V0, Sn) could not be as a interchangeability index for the fullypremixed gas appliances.(3)(Ws, CP) could not be as an interchangeability index for the the fullypremixed gas appliances which have a gas/air proportioning valve.(4)(Ws, V0) may be as an interchangeability index for the the fully premixed gasappliances within a certain scope.(5) The gas composition of (Wi, Hs) and (Ws, Hi) is nearly identical,(Ws, Hi) or(Wi, Hs) could be as the interchangeability indexs for the fully premixed gas appliance,and the result of interchangeability by controlling the values of Wsand Hithat wasmore effective than (Ws, V0).