Control of Particulate Matter from a Sabatier Catalyst Bed HSL 126 Loel Goldblatt, Hamilton Sundstrand Space Systems International, Inc. Karen Murdoch, Wolf Engineering, LLC

Sabatier Development Background Sabatier is a component of an advance air revitalization system It recovers precious water from otherwise waste products (CO2 and H2) System level development has been ongoing since 1999 to bring the technology to a level for incorporation on the International Space Station OXYGEN TO CREW SABATIER CO2 REDUCTION SYSTEM CO2 REMOVAL ASSEMBLY HYDROGEN BI-PRODUCT CO2 SCRUBBED FROM ATMOSPHERE CABIN AIR PRODUCT WATER FOR CREW OR ELECTROLYSIS ADVANCED AIR REVITALIZATION SYSTEM OXYGEN GENERATOR

Problem Statement Sabatier reactor catalyst is a packed bed of precious metal supported on an alumina substrate Vibration and thermal cycling cause the particles to break apart creating “fines” Fines have the potential to become trapped in downstream component causing poor performance or failure Particulate control is one of the major problems encountered in space flight hardware development.

Investigation Protocol Four-step approach  Determine quantity and size of fines generated  Assess system requirements for tolerance and size filter  Brainstorm ideas for filter components  Test filter prototypes with particulate challenge

Determine Quantity and Size of Fines Two known mechanisms for fines generation –Mechanical vibration due to launch loads –Thermal cycling due to normal system operation Create simulations of mechanisms and collect fines generated

Mechanical Vibration Test Simulated rectors with identical length and diameter exercised on vibration table at launch conditions After vibration, beds flushed with nitrogen and then with water Fines collected, weighed and sized

Thermal Cycle Test Thermal cycles simulate temperature extremes over shorter time span Fines are collected as generated in a membrane phase separator Fines are sized for comparison to vibration fines

Particle Generation Test Results Quantity of fines consistent from batch to batch About 50 mg of fines collected each time Most of the particles are under 50 micron in size All of the generation mechanisms create the same size range

Assess System Filtration Requirements Filtration must be 25 um absolute cutoff to protect valve seats and hydro-dynamic bearings in the phase separator Pressure drop at full flow must be less than 0.5 psid Must be compatible with hydrogen, methane, carbon dioxide and water Must not affect the separating and pumping performance of the phase separator

Brainstorm Ideas for Filter Prototypes To avoid the pressure drop created by filtering two phase flow, install the filter in the phase separator to filter only the liquid –Unlikely that the gas stream will carry particulate matter into the vent line Use non-woven, stainless steel filter with 25 um absolute rating Locate the filter where substantial filter area is available

Prototype Test Plan Map the separator performance –Without filter components –With clean filter components –With fines injected along with the water and gas Evaluate effectiveness of filter to capture fines Evaluate effect of filter on separator performance Addition of a particulate filter cannot derate the separator performance

Filter Components Evaluated Barrel shaped filter installed in the drum of the separator Once wet, the filter prevented gas from rising up to the gas outlet of the separator This configuration affected the pumping performance of the separator

Filter Components Evaluated Disk shaped filter installed in the barrel of the separator Vertical filter eliminated the gas binding problem Installed configuration allowed particle bypass to product water outlet

Filter Components Evaluated Radial filter installed at outer diameter of pumping section of separator Tested configuration captured particles with minimal pressure drop

Results / Recommendations  Locate the particulate filter in the phase separator Filtering single phase liquid avoids pressure drop problems associated with two phase flow. This configuration provides ample surface area to collect the quantity of fines expected over the life of the system.  Include this filter design in the next iteration of the Sabatier rotary drum separator / pump design.  Consider application of this filtration technique for other particulate generating systems.