PROJECT DESCRIPTION
While NASA seeks to develop technologies that will enable long- duration manned missions beyond low Earth orbit, oftentimes these technologies result in corresponding benefits on Earth. One example of this is in the area of life support. Life support technology aims to provide those critical functions of maintaining breathable air, providing potable water, managing human wastes, and ensuring a habitable environment for humans in space. Oxygen recovery is a key area of development in life support for long-duration manned missions in which oxygen, exhaled by the crew as carbon dioxide, can be recovered using physical/chemical systems. The Bosch
process is a chemical process in which carbon dioxide (CO2) is broken down, and when combined with water electrolysis, results in the production of oxygen (O2) and solid carbon (Cs). The Bosch for Terrestrial Applications project seeks to identify Earth applications for Bosch technology, to
evaluate the technical feasibility of using Bosch for a given application, and to determine the logistical and economic feasibility of Bosch technology in a commercial industry.
ACCOMPLISHMENTS
In 2017, NASA patented an approach to use the Bosch process, originally developed for space, for the benefit of the cement industry. Introduction of this process into the production of cement results in two benefits. First, the Bosch process provides a method to reduce the considerable CO2 emissions from cement production by converting the exhaust to water and solid carbon. Second, the process uses the cement as a catalyst for the Bosch process, thereby capturing the solid carbon in the cement product. When the Bosch cement is then used to
produce concrete, the result is a material that resists the transport of harmful ions through concrete. By blocking these ions, the steel rebar providing support to concrete structures is protected from corrosion which may result in significantly longer life. Prior to 2018, economic and logistical feasibility of the approach had been reviewed and deemed sufficiently reasonable for continued evaluation. Technical feasibility, however, was limited to benchtop scale demonstration in a packed bed reactor. While the packed bed reactor provided data to prove the chemistry necessary to use the Bosch process with cement, it was not able to prove that the effect would be similarly achievable in an industry-scale process. Further, the packed bed reactor was significantly limited in the overall achievable processing rate due to high pressure drop across the reactor. In an effort to support adaption of the Bosch process into industry and to increase the total processing rate, a more realistic proof of concept is necessary. To this end, a rotary kiln reactor, similar to those used in the production of cement (see Fig. 1) but at a laboratory scale, was purchased in FY 2018. Three milestones were
FIGURE 1. Industrial rotary kiln (≈30 ft diameter) in an operational
identified for FY 2019. The first was to complete the design of a test stand to support operation of the rotary kiln reactor. The second was to procure the necessary components and assemble the test stand. The final milestone was to begin experimentation of the Bosch process for cement in the rotary kiln reactor.
With support from multiple college interns from the University Student Research Association, all three targeted milestones for the project were achieved in FY 2019. An initial design for the test stand was prepared by engineers in the Environmental Control and Life Support Systems (ECLSS) Development Branch at MSFC. From there, an intern provided the day-to-day manpower to lead assembly of the Rotary Kiln test stand (see Fig. 2). The test stand provides the capability to test under targeted Bosch pressures and temperatures as well as developmental kiln parameters including 0–15° tilt and variable rotator speeds. Finally, initial testing was conducted using cement with the goal of demonstrating carbon formation from the Bosch process on the cement as well as increased reaction rates as compared to the packed bed reactor studies. These initial studies showed that the Bosch process was forming carbon on the cement in the rotary kiln reactor (see Fig. 3). Data reduction is ongoing to determine comparable carbon formation rates.
Future work will involve continued testing aimed at optimization of the rotary kiln for a demonstration of the Bosch process in the cement industry.
SUMMARY
The Bosch for Terrestrial Applications project seeks to identify Earth applications for Life Support Bosch technology. The cement industry has been identified as an industry that could benefit from Bosch technology through both reduction in CO2 emissions and an improvement in the durability of its resulting concrete product. In FY 2019, the project successfully designed and assembled a rotary kiln reactor in an effort to prove feasibility of the approach in a directly applicable reactor system.
Data reduction continues to determine if initial testing showed higher reaction rates with a rotary reactor over a packed bed reactor. Future work will seek to optimize operation of the rotary kiln and to generate the necessary data to increase the overall scale of the Bosch process for implementation in the cement industry.
PRINCIPAL INVESTIGATOR: Morgan Abney
PARTNERS: Iowa State University, Concrete Preservation
Institute, Lehigh Cement Company
FUNDING ORGANIZATION: Technology Transfer
FIGURE 2. Laboratory rotary kiln reactor in rotary furnace. A
custom quartz tube is used as the reactor in the furnace.
FIGURE 3. Close up of the 2 in reactor tube
containing Bosch cement. In this test, carbon formation was observed to form at the location nearest the gas inlet. This indicates unbalanced flow with respect to the aspect ratio of the reactor.