NETL Researchers Studying Chemical Looping Combustion

	Thomas Simonyi uses a thermogravimetric analyzer in NETL’s studies of chemical looping combustion, a novel, flameless technology for coal combustion.

Researchers at the National Energy Technology Laboratory (NETL) are studying the feasibility of using a novel,flameless technology for coal combustion.

Chemical looping combustion, or CLC, is a new combustion technology that involves using a reusable metal oxide as an oxygen carrier to deliver oxygen from the air to the fuel. This combustion environment would greatly simplify separation of CO₂ from the flue gas for eventual CO₂ sequestration.

A solid fuel such as coal faces many challenges in the CLC process. NETL researchers are working to overcome the challenges because CLC would be a very economical way to use coal while sequestering the CO₂.

As part of this work, NETL is studying several metal oxides as oxygen carriers. So far,the best results were obtained using copper oxide as the oxygen carrier. Thermogravimetric analysis (TGA) experiments showed full coal combustion at 600-1000^o C in the CLC process.

Ranjani Siriwardane presented a paper on NETL’s chemical looping combustion research at the annual American Institute of Chemical Engineers meeting in Philadelphia.

Researcher Discusses NETL’s Studies of Fuel Interchangeability

	Dr. Don Ferguson, right, and a doctoral student from West Virginia University, were involved in studies of ways to update and improve methods of determining fuel interchangeability for various combustion applications.

Researchers at the National Energy Technology Laboratory (NETL) are studying ways to update and improve methods of determining fuel interchangeability for various combustion applications.

The research funded through the Department of Energy’s Office of Energy Efficiency and Renewable Energy- Industrial Technologies Program is focused on improving computational methods and related fundamental combustion characteristics to physical and chemical properties of the fuels and burner geometries.

Dr. Don Ferguson described the NETL research in an invited presentation to gas producers, pipeline operators and their customers at a recent Platts Gas Interchangeability and Quality Forum in Washington, D.C.

Fuel interchangeability continues to be a serious concern for pipeline operators and end users including power providers. The Energy Information Administration is predicting over the next 10 years there will be a substantial increase in the use of conventional natural gas alternatives such as landfill gas, coal derived syngas, biogas and imported liquefied natural gas (LNG).

Alternative and opportunity fuels typically have compositions that vary from that of conventional pipeline natural gas. This could potentially alter combustion properties in the end use applications, thus resulting in concerns regarding fuel interchangeability.

Current practices used by industry to predict the interchangeability of gases fuels were developed during the 1930s and ‘40s. The result of this effort produced a series of indices related to various combustion phenomena based on the current “state-of-the-art” at the time. These indices have become outdated and are inadequate for use in today’s sophisticated combustion applications.

The goal of the NETL Fuel Flexibility Program is to develop a series of updated tools that will allow gas suppliers and end-users the ability to accurately predict the interchangeability of gaseous fuels for their combustion application. Given this technology, end-users may be more willing to take advantage of opportunity fuels such as landfill gas, coal derived syngas and biogas.

NETL Files for Patent on Novel Flue Gas CO₂ Capture Process

	NETL's inventors of the novel carbon dioxide capture process are, from left, Yee Soong, Sheila Hedges and Robert Dilmore.

The National Energy Technology Laboratory (NETL) has filed a patent application for a novel carbon dioxide capture process invented by NETL researchers. The process involves dissolving CO₂ into an aqueous solution and eventually separating it out.

Preliminary calculations indicate that CO₂ could be separated by this process with as much as 20 percent less heat requirement than the typical monoethanolamine (MEA) scrubbing process.

In the NETL process, the CO₂ from combustion flue gas dissolves into an aqueous solution of amine and soluble potassium carbonate. Potassium carbonate rapidly reacts with amine-associated carbamate and water to form less-soluble potassium bicarbonate that precipitates from solution.

This reaction serves both to chemically regenerate the amine solution by removing the carbamate, and separate CO₂ in the form of solid bicarbonate. Separated potassium bicarbonate can then be heated to regenerate back to solid potassium carbonate, releasing concentrated CO₂ gas.

Finally, potassium carbonate is re-dissolved in the regenerated amine solution, and the reactive solution re-exposed to flue gas to close the process loop.

The process has the potential to achieve high CO₂ capture efficiency with relatively low regeneration energy requirements, suggesting that it could achieve CO₂ capture from utility emission streams at lower overall cost.