可燃冰是一种清洁无污染的新型能源。为了对可燃冰资源进行深海连续走航勘探,膜分离-离轴积分腔输出光谱联用技术(M-ICOS)被应用于海水溶解CH4和CO2气体的探测。M-ICOS系统由膜分离单元、腔内温度压力控制单元、光腔、光谱测量单元和工业计算机等组成。实验研究发现,该系统的温度和压力控制精度分别为0.0003733 ℃和0.6799 Pa,CH4检测极限为0.56×10 -9,CO2检测极限为0.62×10 -6。利用M-ICOS系统在南海神狐海域进行了实地测量实验,实验发现,在海面下500~700 m处,水中溶解的CH4和CO2浓度有剧烈的波动,这可能是由于此处海流携带了海底可燃冰富集区域释放的高浓度溶解气体。M-ICOS系统具有良好的灵敏度和稳定性,能够在深海恶劣条件下对海水溶解CH4和CO2进行探测,从而实现对可燃冰资源的连续走航勘探。

Methane hydrate is a new clean energy source. For the cruise detection of methane hydrate, membrane separation off-axis integrated cavity output spectroscopy, M-ICOS, is applied to detect dissolved methane (CH4) and carbon dioxide (CO2). An M-ICOS system comprises a membrane separation unit, a cavity temperature and pressure controller, an optical cavity, a spectrometer unit, and an industrial personal computer. The M-ICOS system is tested for performance evaluation. The accuracies of the temperature and pressure controller are 0.0003733 ℃ and 0.6799 Pa, respectively. The limits of detection of CH4 and CO2 are 0.56×10 -9 and 0.62×10 -6, respectively. A field experiment in Shenhu area, South China Sea, found a strong fluctuation in the gas concentration at the depth of 500--700 m, which was probably because the sea flow took high concentration gas from the methane hydrate enrichment area. Experimental results reveal that the system exhibits a good sensitivity and stability, which make it usable to detect CH4 and CO2 in deep sea for cruise detection of the methane hydrate.