过程质谱仪测量气体浓度快速变化过程的应用研究

Use of a Process Mass Spectrometer to Measure Rapid Change of Gas Concentration

通过实验研究了微型流化床多阶段原位反应分析仪(MFB-MIRA)检测快速气固反应气体逸出过程的适应性。研究表明,取样毛细管的伴热性能对在线测量的稳定性有重要影响。基于所得规律,将精密温控器配置于毛细管的伴热系统,毛细管温度的控制精度达到±0.2℃,从而实现了取样流量和腔室真空度的稳定化。实测结果表明,改造后在线测量的周期性波动消失,稳定性显著提高。空气中O_2测量响应的波动度和30 s相对标准偏差由1.9%和0.5%,优化至1.4%和0.2%。同时还开发了精确控制取样点绝对压力的调节装置,使取样点绝对压力的控制精度达到±0.02 k Pa。实验结果表明,取样点绝对压力与过程质谱仪的响应呈正相关,准确控制取样点绝对压力非常必要。本研究提高了过程质谱仪测量结果的准确性和重复性,提升了MFB-MIRA分析快速气固反应的适应性,进而拓宽了MFB-MIRA及过程质谱仪可靠应用的范围。

Experiments were conducted to investigate the suitability of the multistage in-situ reaction analyzer based on a micro fluidized bed（ MFB-MIRA） for measuring the rapid change of the gas concentration during gas-solid reactions. The results showed that the control performance of capillary temperature had a great impact on the stability of on-line measurement. Based on the observed regular patterns,the capillary temperature control system was equipped with a precision temperature controller. The control precision of capillary temperature reached ± 0.2℃,which guaranteed the high stabilities of the sampling flow rate and the chamber vacuum. The measured results of the modified gas monitoring system showed the periodic fluctuations of the online measurement were eliminated. The stability of measurement was significantly improved. The fluctuating range and relative standard deviation of the measured response to O2 in air changed from 1.9% and 0.5% to 1.4% and 0.2%,respectively. A pressure regulating device was also developed to control the absolute pressure at the gas sampling point. The control precision reached ± 0. 02 k Pa. The measured results showed that the response of the process mass spectrometer was positively correlated with the absolute pressure at the sampling point,indicating the necessity of the pressure regulating device. The accuracy and repeatability of process mass spectrometer were improved. This study has enhanced the suitability of MFB-MIRA for studying rapid gas-solid reactions and broadened the scope of reliable applications of MFB-MIRA and process mass spectrometer.