Carbon Capture Filter
Environment
Carbon Capture Filter (LEW-TOPS-176)
Cold Trap Filter Removes Carbon and Fine Particulates from Gaseous Streams
Overview
On the International Space Station (ISS), the Environmental Control and Life Support System (ECLSS) serves as a waste recovery system, air revitalization system, and oxygen generation system. Recently, Plasma Pyrolysis Assembly (PPA) technology, a supporting technology for CO2 chemical reduction that could enable the recovery of over 86% of the oxygen from CO2 produced on the ISS, has been under development at NASA. One of the main issues with plasma pyrolysis is that it generates effluent containing fine (100-200 nm) particles that could foul the PPA reactor and downstream ECLSS systems.
To address this challenge, NASA has developed a new Carbon Capture Filter system that uses a variety of mechanisms to trap and remove solid carbon dust. This NASA invention may provide value for a variety of terrestrial applications requiring continuous or batch removal of solid carbon emissions of pyrolyzed hydrocarbons, or high-capacity removal of inert fine dust. The filter system can be scaled up or down in size to accommodate different applications, and could also be applied for consumer products including portable vacuum cleaners and filter systems.
The Technology
NASA’s Carbon Capture Filter was designed to trap solid carbon dust through a variety of mechanisms. These include inertial separation, flow recirculation, flow tortuosity, media filtration, and quenching of hot particles or of precursor particles from pyrolysis. The filter uses a custom-designed housing to produce a strong and large recirculating pattern to remove dust through inertial forces and confine it into a large collection cup, which is enshrouded in a cold trap (using a thermoelectric cooler) to thermally induce precipitation of the solid carbon. The flow then passes through a single stage baffle and tube filters before exiting through the outlet at the top of the housing.
During operations, gaseous carbon-containing streams enter the filter via an inlet tube at the top of the housing. The inlet tube extends down towards the bottom of the collection cup, where the high-speed stream meets a sudden perpendicular bottom wall, inducing a stagnation flow. Large particles inertially separate from the flow and impinge onto the bottom wall. The partial enclosure of the collection cup (aside from a small slit connecting it to the upper chamber) causes a recirculation bubble to form, increasing the residence time of the stream. The vortical motion of the recirculation bubble causes the large particles to spin outwards towards the walls of the collection cup. The collection cup is cooled to quench the carbon particles, causing them to precipitate out and collect on the walls of the cup. The extended residence time caused by the recirculating flow further quenches the stream. Only small particles that are entrained sufficiently by the flow make it through the slit between the collection cup and upper chamber. On the top wall of the upper chamber, an array of tubular filters collects the remaining particles before the gaseous stream exits the system.
NASA’s Carbon Capture Filter has been prototyped and undergone initial testing with simulant dust, yielding promising results. The invention is available for licensing to industry.
Benefits
- Scalable: NASA’s filter system can be sized for long operation periods or scaled to the size of the application.
- Enhanced performance: NASA’s Carbon Capture filter may improve the performance of plasma pyrolysis systems and enable improved emissions control and carbon capture management.
- Captures small particles: NASA’s filter has been demonstrated to remove a percentage of very small particles (< 2 microns) in the collection cup. The filter could capture even smaller particles by changing geometric and flow parameters.
- Demonstrated: The system has been prototyped and tested in a laboratory environment.
- Regeneration: NASA’s filter can be produced to enable regeneration either by quick disassembly to empty the collection cup, or through a side port to vent or suction out the collection cup.
- Could extend lifespan of HEPA filters: Used upstream of a HEPA filter, the invention could capture larger airborne particles, extending the life of the HEPA filter.
- Potential synergy with regenerative thermal oxidizers (RTO): RTOs achieve high levels of VOC destruction but tend to capture particulate matter in processed gas at low efficiencies. NASA’s filter could be added to the exhaust of RTOs to substantially increase particle collection efficiency as well as remove any remaining condensable VOCs.
Applications
- Industrial applications using plasma pyrolysis (e.g., waste treatment, environmental remediation, metals recovery from “e-waste”)
- Carbon capture management systems
- Emissions control for smokestacks, NOx emissions, catalytic converters, portable vacuum cleaners, or other filter systems
- Space life-support systems employing plasma pyrolysis
Technology Details
Environment
LEW-TOPS-176
LEW-20420-1
Agui, J., Green, R., and Berger, G. (2022) 'Development of an Inertial and Cold Trap Filter for Carbon Fines Management', Available at: https://ttu-ir.tdl.org/server/api/core/bitstreams/e48442fc-8f9a-4896-beab-58875b76cab5/content
Agui, J., Berger, G. (2022) 'Cold Trap Carbon Capture Filter for Carbon Fines Management - In-laboratory Performance and Efficiency Results', Available at: https://ttu-ir.tdl.org/server/api/core/bitstreams/e86231ce-b4b6-4cc7-a7ee-157378498e13/content
Similar Results
Modular System for Waste Treatment, Water Recycling, and Resource Recovery
Because resupply of commodities for long duration space missions would be prohibitively expensive and could take an extensive length of time to reach habitats in orbit around or on other planetary bodies, it is critical that astronauts have the ability to recycle and reuse local waste streams to provide resources such as clean water, fuel, and nutrients for growing plants. Scientists at Kennedy Space Center and the University of South Florida have developed a technology that addresses this critical mission need. The modular system design incorporates all wastewater streams and some food waste including urine water, hygiene water, humidity condensate, Sabatier water, fecal waste, laundry water, and organic food waste. These sources are fed simultaneously into the system, and a function-driven, sequential purification process occurs. The primary processes include carbon conversion, phase separation (solid/liquid/gas), disinfection, nutrient/salts management, and salts balancing to generate a clean water stream. The heart of the closed-loop bio-regenerative system is an anaerobic membrane bioreactor (AnMBR), which takes raw wastewater streams and utilizes an anaerobic microbial consortium to carry out the breakdown of the organic matter. An ultrafiltration membrane captures and destroys pathogenic bacteria and viruses. The AnMBR system generates a clean water stream containing fertilizer constituents which can be used to cultivate either microalgae (for food, pharma/nutraceuticals, fuel or bioplastics) in photobioreactors or crops in hydroponic systems. The system also generates methane and hydrogen gas which can be used for fuel (or conversion to bioplastics), and CO2 which can be used to support plant growth.
Low-Temperature Oxidation/
Reduction Catalysts
The low-temperature oxidation catalyst technology employs a novel catalyst formulation, termed platinized tin oxide (Pt/SnOx). The catalysts can be used on silica gel and cordierite catalyst supports, and the latest developments provide sprayable formulations for use on a range of support types and shapes. Originally developed for removal of CO, the catalyst has also proven effective for removal of formaldehyde and other lightweight hydrocarbons.
NASA researchers have also extended the capability to include reduction of NOx as well as developed advanced chemistries that stabilized the catalyst for automotive catalytic converters via the engineered addition of other functional components. These catalyst formulations operate at elevated temperatures and have performed above the EPA exhaust standards for well beyond 25,000 miles. In addition, the catalyst can be used in diesel engines because of its ability to operate over an increased temperature range.
For use as a gas sensor, the technology takes advantage of the exothermic nature of the catalytic reaction to detect formaldehyde, CO, or hydrocarbons, with the heat being produced proportional to the amount of analyte present.
Air Revitalization for Vacuum Environments
The NASA life support system uses a regenerable vacuum swing adsorption process, known as Sorbent-Based Air Revitalization (SBAR), to separate water and carbon dioxide for disposal. The SBAR system is an adsorbent-based swing bed system that has been optimized to provide both humidity and carbon dioxide control for a spacecraft cabin atmosphere.
The system comprises composite silica gel and zeolite-packed beds for adsorption and a bypass system for flow control. Under normal operating conditions, the disposal system would require a high-quality vacuum environment to operate. Improvements to the SBAR system include an enhanced inherent capacitance that extends the operation time within a non-vacuum environment for up to 4.5 hours. Flight time can be further expanded with multiple SBAR systems to allow for system regeneration. By scheduling periodic thermal regenerations—nominally during sleep periods—the SBAR technology may be suitable for missions of unlimited duration.
Carbonated Cement for Production of Concrete with Improved Properties
The NASA cement innovation describes a method to make solid carbon material from CO2 captured during the cement-making process, and for using that carbon material in the mixture to improve cement properties. Doing so provides a direct use for the captured CO2, eliminating any CO2 storage/disposal issues and providing an improved cement product.
The innovation employs a chemical reaction, known as the Bosch process, which uses hydrogen gas and catalysis to reduce the CO2 to solid carbon and water. Cement manufacturing is uniquely suited to the use of the Bosch process. Cement manufacturing requires high temperatures, and harnessing this excess heat limits the total energy required to maintain a Bosch process at a cement plant. Also, cement contains iron, a metal shown to be an exceptional catalyst for the Bosch process. Thus, the cement product itself can be used as the catalyst for the reaction, also serving as a carbon sink. This eliminates any requirements for the storage or disposal of the waste carbon captured from CO2 emissions.
Test evaluations at the bench scale have provided encouraging indications of enhanced mechanical properties for the carbon-containing cement materials. In particular, the findings suggest that the carbon in the concrete might delay the environmental breakdown of concrete due to the blocking effect of the carbon on harmful ions (e.g., chlorine).
Wastewater Treatment and Remediation
NASA's system was developed for smaller-scale, space-based applications. However, the technology is scalable for larger industrial and municipal water treatment applications. Implementation of the Ammonia Recovery System could significantly reduce nitrogen content from water treatment processes, meaningfully improving the quality of water. This system offers a novel way to reduce nitrogen water pollutants, while allowing for the nitrogen to be collected and reused- reducing environmental and public health risks and providing an environmentally friendly fertilizer option. NASAs environmental solutions work to sustain life on earth through space based technology
The adaptable nature of this system gives it potentially broad applications in a wide variety of industries; it is particularly ideal for on-site remediation of wastewater in places like condo complexes, hotels and water parks. Current methods of ammonia recovery could not meet NASAs mission requirements, so a new process was devised to optimize for high ammonia selectivity, simplicity, low volume , low power usage and zero contaminants in the effluent. To do this, NASA designed a novel regenerable struvite-formation system for the capture of ammonia. This system has three primary functions:
1) Removal of ammonia from wastewater using a media that is highly selective for ammonia
2) Capture of the ammonia for later use (e.g., as a fertilizer)
3) Regeneration of the capture media for reuse in the system
