Project No: FC26-07NT43088
Performer: Praxair

Richard Dennis
Technology Manager (Acting)
Advanced Combustion Systems
National Energy Technology Laboratory
3610 Collins Ferry Road
P.O. Box 880
Morgantown, WV 26507-0880

Steven Richardson
Federal Project Manager
National Energy Technology Laboratory
3610 Collins Ferry Road
P.O. Box 880
Morgantown, WV 26507-0880

Sean Kelly
Principal Investigator
Praxair, Inc.
175 East Park Drive
Tonawanda, NY 14534

Award Date:  04/01/2007
Project Date:  09/30/2015

DOE Share: $41,188,249.00
Performer Share: $23,939,957.00
Total Award Value: $65,128,206.00

Performer website: Praxair -

Advanced Energy Systems - Advanced Combustion Systems

Recovery Act: Oxy-combustion: Oxygen Transport Membrane Development

Project Description

Praxair determined (under a prior agreement with DOE) that the cost of CO2 capture utilizing oxygen transport membrane (OTM) air separation integrated with oxy-combustion is competitive with other CO2 capture processes when applied to large power plants. This work also demonstrated that durable OTMs for oxy-combustion can be fabricated to survive and operate reliably in a fuel environment. Praxair observed a zero percent failure rate for the OTM membranes during prior testing; however, the highly durable materials selected for the OTM reactors require substantial development in order to improve the oxygen flux through the system while maintaining durability and reducing manufacturing costs. In the first stage of this project, Praxair will further develop high-performance materials used for OTMs, optimize and test process configurations, validate manufacturing capabilities, and produce a preliminary engineering design for an OTM pilot plant system. With the addition of ARRA funding, the second stage of this project will focus on operating OTM modules in syngas and conducting oxy-combustion development- and pilot-scale tests incorporating critical system components required of commercial systems. Praxair will develop and operate a robust and reliable OTM module that will provide the foundation for commercial deployment of reactively driven ceramic membrane systems. Praxair will develop first-generation OTM modules and test them in a developmental-scale, fully integrated, multi-module syngas system producing 160,000 standard cubic feet per day (scfd) of syngas and incorporating components of a commercial system. Praxair will develop second-generation OTM modules incorporating improvements identified through module testing, and test them in a pilot-scale skidded, multi-module syngas system as well. All testing and modeling results will be evaluated to develop preliminary cost estimates for a demonstration-scale syngas system and a preliminary design for pilot-scale oxy-combustion system.

Program Background and Project Benefits

Advanced combustion power generation from fossil fuels involves combustion in a high-oxygen (O2) concentration environment rather than air. This type of system eliminates introduction of most, if not all, of the nitrogen (N2) found in air into the combustion process, generating flue gas composed of CO2, water (H2O), trace contaminants from the fuel, and other gas constituents that infiltrated the combustion system. The high concentration of CO2 (≈60 percent) and absence of nitrogen in the flue gas simplify separation of CO2 from the flue gas for storage or beneficial use. Thus, oxygen-fired combustion is an alternative approach to post-combustion capture for Carbon Capture and Storage (CCS) for coal-fired systems. However, the appeal of oxygen-fired combustion is tempered by a number of challenges, namely capital cost, energy consumption, and operational challenges associated with supplying O2 to the combustion system, air infiltration into the combustion system that dilutes the flue gas with N2, and excess O2 contained in the concentrated CO2 stream. These factors mean oxygen-fired combustion systems are not cost-effective at their current level of development. Advanced combustion system performance can be improved either by lowering the cost of oxygen supplied to the system or by increasing the overall system efficiency. The Advanced Combustion Systems Program targets both of these possible improvements through sponsored cost-shared research into two key technologies: (1) Oxy-combustion, and (2) Chemical Looping Combustion (CLC).

Oxy-combustion power production involves three major components: oxygen production (air separation unit [ASU]), the oxy-combustion boiler (fuel conversion [combustion] unit), and CO2 purification and compression. These components along with different design options are shown below. Based on the different combinations of these components, oxy-combustion can have several process configurations. These different configurations will have different energetic and economic performance.

Today's oxy-combustion system configuration would use a cryogenic process for O2 separation, atmospheric-pressure combustion for fuel conversion in a conventional supercritical pulverized-coal boiler; substantial flue gas recycle; conventional pollution control technologies for SOx, NOx, mercury, and particulates; and mechanical compression for CO2 pressurization. However, costs associated with currently available oxy-combustion technologies are too high. The Advanced Combustion Systems R&D Program is developing advanced technologies to reduce the costs and energy requirements associated with current systems. R&D efforts are focused on development of pressurized oxy-combustion power generation systems, as well as membrane-based oxygen separation technologies.

Praxair is developing a unique oxy-combustion system that integrates oxygen-separation membrane modules into the boiler, thereby using oxygen as it’s produced, resulting in a significant reduction in the size of the ASU to only what is necessary for coal gasification. In addition, the OTM oxy-combustion system can provide a highly concentrated, sequestration-ready stream of CO2 without the need for a large CO2 post-combustion capture system. These factors have the ability to reduce equipment size and complexity, thereby reducing capital cost, which has the potential to drive down the cost of electricity and the cost of CO2 capture relative to supercritical coal-fired power plants with post-combustion CCS. Successful testing of a development-scale OTM partial-oxidation unit will validate the feasibility of Praxair’s approach, and cost and performance analysis of a full-scale system will support design and development of an OTM oxy-combustion boiler prototype.

This project is a continuation of an ongoing effort that has been performed by Praxair under "Advanced Oxyfuel Boilers and Process Heaters for Cost Effective CO2 Capture and Sequestration" (Contract No.: FC26-01NT41147). The Final Report for the original project provides more detailed discussion of the work.

Project Scope and Technology Readiness Level

Phase III of the project will start with significant efforts related to design of the OTM modules and systems. Once first-generation modules are completed, the modules will be integrated in a development-scale reactor and corresponding balance-of-plant designed for a nominal 160,000 scfd syngas production demonstration. Praxair will partner with a global ceramic manufacturing company and work together to define and create subsequent generations of OTM modules. The development-scale test system will be modified as necessary to allow testing of OTM modules as improvements are introduced. There will be additional scope associated with the development-scale syngas system to develop a design to convert it to a combustion system capable of transferring heat to a load.

The Technology Readiness Level (TRL) assessment identifies the current state of readiness of the key technologies being developed under the DOE’s Clean Coal Research Program. In FY 2012, this project was assessed a TRL of 3.

The TRL assessment process and its results including definition and description of the levels may be found in the "2012 Technology Readiness Assessment-Analysis of Active Research Portfolio".