A catalytic combustion system coupled with adsorbents for air clean up in sealed spacecraft environment

摘要

Catalytic combustion coupled with activated carbon and molecular sieve adsorbents is applicable to all areas of air and gas clean up ranging from high to low levels of pollutants and trace contaminants control in a spacecraft environment is of no exception. In this study we propose a combined activated charcoal and catalytic combustion system based on a 70 watt power input achieving 350°C, operating on a 6 hour per 24 hour day catalytic cycle with an actual flow of 10.6 l min{sup}(-1)in a residual free volume of 60 m{sup}3. The catalysts are optimally sized for keeping the contaminants within a specified limits whilst paying particular attention to the following design parameters in descending order of priority power consumption, catalyst mass and catalyst volume We consider 2 conceptual catalytic systems namely: 1. A combined charcoal pre-filters and a catalyst operating at 350°C for 6 hours per earth day using an allocated power of 70 watts. 2. A single catalytic system operating at 350°C for 6 hours per 24 hour day. The catalysts are precious metals on single or mixed base oxides to give the sustained low temperature performance. One of the catalyst is an extruded monolith of 200 cells per square inch and the other is a washcoated honeycomb substrate (cordierite) of 600 cpsi. The ceramic monolith has some significant advantages over the granular type catalyst namely: Low pressure drop, Large geometric area, Low coefficient of expansion, Good thermal shock resistance, and Good vibration and crushing resistance. The two recommended catalysts of different formulations are: -