应用光学
應用光學
응용광학
JOURNAL OF APPLIED OPTICS
2014年
5期
917-921
,共5页
激光诱导击穿光谱%碱金属火焰原子吸收%Beer-Lambert定律%热力学平衡
激光誘導擊穿光譜%堿金屬火燄原子吸收%Beer-Lambert定律%熱力學平衡
격광유도격천광보%감금속화염원자흡수%Beer-Lambert정률%열역학평형
laser induced breakdow n spectroscopy%flame atomic absorption by alkali metals%Beer-Lambert law%thermodynamic equilibrium
当使用激光诱导击穿光谱技术（L IBS ）测量火焰场内碱金属元素时，等离子体内碱金属原子所发出的LIBS信号，会受到等离子体外火焰中基态碱金属原子的吸收，影响测量精度。基于Beer-Lambert定律和CH4-空气火焰场内气态含K物质的热力学平衡原理，建立了火焰场内K元素LIBS信号的原子吸收模型，并分析了实际生物质颗粒燃烧K元素释放浓度范围内，火焰气氛、K元素浓度分布以及总K浓度对火焰原子吸收效率的影响。研究发现，随着O2/C H4的摩尔比值的增加，火焰中热力学平衡状态下K原子占总K的比例从约25％逐步降低，火焰原子吸收效率也从86．8％逐步降低。当O2/C H4的摩尔比值大于2时，火焰尾气中会存在剩余O2，此时火焰内K原子的吸收效率均低于13％。同时，火焰中K元素浓度分布以及总K浓度的合理调整亦对火焰原子吸收效率具有降低作用。在此基础上，提出了创造氧化性气氛、调整K 浓度分布来降低火焰原子吸收效率和提高LIBS测量精度的解决途径。
噹使用激光誘導擊穿光譜技術（L IBS ）測量火燄場內堿金屬元素時，等離子體內堿金屬原子所髮齣的LIBS信號，會受到等離子體外火燄中基態堿金屬原子的吸收，影響測量精度。基于Beer-Lambert定律和CH4-空氣火燄場內氣態含K物質的熱力學平衡原理，建立瞭火燄場內K元素LIBS信號的原子吸收模型，併分析瞭實際生物質顆粒燃燒K元素釋放濃度範圍內，火燄氣氛、K元素濃度分佈以及總K濃度對火燄原子吸收效率的影響。研究髮現，隨著O2/C H4的摩爾比值的增加，火燄中熱力學平衡狀態下K原子佔總K的比例從約25％逐步降低，火燄原子吸收效率也從86．8％逐步降低。噹O2/C H4的摩爾比值大于2時，火燄尾氣中會存在剩餘O2，此時火燄內K原子的吸收效率均低于13％。同時，火燄中K元素濃度分佈以及總K濃度的閤理調整亦對火燄原子吸收效率具有降低作用。在此基礎上，提齣瞭創造氧化性氣氛、調整K 濃度分佈來降低火燄原子吸收效率和提高LIBS測量精度的解決途徑。
당사용격광유도격천광보기술（L IBS ）측량화염장내감금속원소시，등리자체내감금속원자소발출적LIBS신호，회수도등리자체외화염중기태감금속원자적흡수，영향측량정도。기우Beer-Lambert정률화CH4-공기화염장내기태함K물질적열역학평형원리，건립료화염장내K원소LIBS신호적원자흡수모형，병분석료실제생물질과립연소K원소석방농도범위내，화염기분、K원소농도분포이급총K농도대화염원자흡수효솔적영향。연구발현，수착O2/C H4적마이비치적증가，화염중열역학평형상태하K원자점총K적비례종약25％축보강저，화염원자흡수효솔야종86．8％축보강저。당O2/C H4적마이비치대우2시，화염미기중회존재잉여O2，차시화염내K원자적흡수효솔균저우13％。동시，화염중K원소농도분포이급총K농도적합리조정역대화염원자흡수효솔구유강저작용。재차기출상，제출료창조양화성기분、조정K 농도분포래강저화염원자흡수효솔화제고LIBS측량정도적해결도경。
When the measurement of alkali metals is performed using laser-induced breakdow n spectroscopy (LIBS) in flame ,the emission of the alkali atoms in the plasma can be absorbed by the alkali atoms outside the plasma in the flame ,influencing the LIBS measurement accuracy . Based on the Beer-Lambert law and the thermodynamic equilibrium calculation ,a flame atomic absorption model covering the concentration range of K released during practical biomass com-bustion was developed ,and the influences of the atmosphere of the flame ,the K distribution and the total K concentration on the flame atomic absorption efficiency were analyzed .It is found that ,with the increase of the O2/CH4 ratio ,the equilibrium molar fraction of atomic K in all K-containing species decreases from approximate 25% ,leading to the decrease of the flame atomic absorption efficiency from 86 .8% .When the O2/CH4 molar ratio ratio exceeds 2 ,excess O2 exists in the flame ,and the flame atomic absorption efficiency is always less than 13% . Meanwhile ,by proper adjustment of K distribution and the total K concentration ,the flame a-tomic absorption efficiency can also be reduced .Based on this ,it is proposed that to reduce the flame atomic absorption efficiency and facilitate the K LIBS measurement accuracy in flame ,an oxidizing flame atmosphere and a proper K distribution profile should be created .
