Papers by Keyword: Explosive Limit

Abstract: Under the different experimental condition of ignition energy, the variations of gas explosive limit were obtained. The explosive limit ranges from 4.86% to 16.72%, under the condition of high ignition energy of 450 J. The result is quite different from the theoretical explosion limit range from 5% to 16%, thus providing a new basis to effectively prevent the gas explosion accidents.

Abstract: Traditional Pressure Swing Adsorption (PSA) approach of using single adsorbent probably makes methane concentration very close to the explosion limit and may result in explosion risk in the adsorption process, when methane concentration in coal min methane is blow 30%. Based on pressure swing adsorption, Proportion Pressure Swing Adsorption (PPSA), a new enrichment method with high safety, was suggested to enrich low concentration Coal mine methane (LCCMM). A mixture of active carbon (AC) and carbon molecular sieve (CMS) was employed as adsorbent in the process of PPSA. The methane and oxygen in CMM were adsorbed simultaneously. The experimental study was carried out in order to verify the feasibility of this method. The equilibrium adsorption characteristic of AC and CMS were tested, the mixture of AC1 and CMS5 are chosen as adsorbents for LCCMM enrichment by PPSA.

Abstract: Based on pressure swing adsorption, Proportion Pressure Swing Adsorption (PPSA), a new enrichment method with high safety, was suggested to enrich the low concentration coal bed gas. A mixture of active carbon (CA) and carbon molecular sieve (CMS) was employed as adsorbent in the process of PPSA. The methane and oxygen in coal bed gas were adsorbed simultaneously. The experimental study was carried out in order to verify the feasibility of this method. The equilibrium adsorption characteristic of CA and CMS were tested. The results showed that both concentrations of CH₄ and O₂ in desorption gas could be controlled well and would not exceed the explosion limit in enrichment process by adjusting the mass ratio of CMS5/AC1. Therefore, the new method, PPSA, can guarantee the safety in enrichment of coal bed methane.

Abstract: Detection of hydrogen gas is a crucial task for establishing safety and reliability of fuel cells, a key technology for the environment and our society. However, hydrogen is difficult to detect and various hydrogen sensors have many drawbacks. Here we report a novel hydrogen gas sensor, the ball surface acoustic wave (SAW) sensor, using Pd or PdNi sensitive film. The ball SAW sensor is based on a novel phenomenon, diffraction-free propagation of collimated beam along an equator of sphere. The resultant ultra-multiple roundtrips of SAW makes it possible to achieve highest sensitivity among SAW sensors. Moreover, it enables to use a very thin sensitive film, and consequently the shortest response time (2s) was realized. In terms of the sensing range, it has the widest range of 10 ppm to 100 % among any hydrogen sensors including FET or resistivity sensors. The ball SAW sensor can be applied not only to hydrogen but also to any gasses and possibly to liquids.