Control of Particulate Matter from a Sabatier Catalyst Bed

HSL 126Loel 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 approachDetermine quantity and size of fines

generatedAssess system requirements for tolerance

and size filterBrainstorm ideas for filter componentsTest 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

Typical Sabatier Reactor Cycle Data

0

200

400

600

800

1000

0:28 1:40 2:52

Time of Day (hh:mm)

Tem

pera

ture

(F)

0

2

4

6

8

10

Hydr

ogen

Flo

w (l/

min

)

Reactor TempH2flow

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

Quantity of Particles Collected

0 10 20 30 40 50 60 70 80

Post-Vibe #1Nitrogen Flush

Post-Vibe #1 WaterFlush

Post-Vibe #2Nitrogen Flush

Post Vibe #2 WaterFlush

Amount Collected (mg)

Old Catalyst

New Catalyst

Particle Size Distribution

0

0.2

0.4

0.6

0.8

1

20-50 50-100 100-150 150-200 200-250 250-300 300-400 400-600

Particle Size (micron)

Nu

mb

er F

rac

tio

n o

f T

ota

l

Bed 1 Post Vibe 1 Water

Bed 1 Post Vibe 2 Water

Bed 1 Post Vibe 1 N2

Bed 1 Post Vibe 2 N2

Bed 2 Post Vibe 1 Water

Bed 2 Post Vibe 2 Water

Bed 2 Post Vibe 1 N2

Bed 2 Post Vibe 2 N2

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.