Research on the sensitivity for the coal mine gas concentration detection by laser spectrum absorption

• 来源期刊: 煤炭学报（英文版）
• 年，卷（期）: 2007,（3）
• 页码范围: 370-372
• 页数: 3页
• 语种: 英文

摘要

Because of the former gas chemistry examination method defects, tunable diode laser absorption spectrum technology (TDLAS) was used. Itused an isolated absorption spectrum of the gas molecule to measure the gas absorption spectrum in order to distinguish the gas conveniently. The second harmonic (2f) was measured in this system.Due to the fact which the harmonious signal is proportional to the concentration of the absorption gas, the gas concentration may be obtained through examining harmonious signal. The theoretical analysis and the experimental result indicate that under the same level of pressure, survey with the signal-to-noise ratio(SNR) of 2f signal increases the accuracy by one order of magnitude and may reach 10-3 and the sensitivity may reach the 10-6 level compared to that of direct absorption. 5% methane density and a 30 cm absorption cell were used in the experiment. It has several advantages including high sensitivity, best resolution, and faster response and so on. The gas concentration monitoring ofcoal mine may be accomplished.