Pittsburgh, Pa. — Researchers at the U.S. Department of Energy’s National Energy Technology Laboratory (NETL) received nine patents in 2012 for innovations that address the Nation’s energy challenges. The patents include an integrated process for removing pollutants from fossil-fuel combustion systems; a metallurgical melting process to produce defective-free metal ingots; catalysts that make it easier to reform hydrocarbon fuels; stainless steel compositions and heat treatment processes to enhance stainless steel durability; a method to measure the circulation rate of coal solids in gasification reactors; and a process to separate and purify carbon dioxide (CO2). Deployment of these technologies will enhance energy efficiency, improve metallurgical processes, and allow for better emissions monitoring and control.
NETL pursues patent protection for NETL-developed technologies to protect U.S. taxpayers’ investment in energy-related research. NETL’s Technology Transfer Office manages the process, identifying those technologies with the greatest commercial potential. The office also fosters the development and deployment of new technologies by moving inventions from the laboratory into the commercial marketplace. Many innovations developed at NETL have been successfully transferred to industrial partners, including three of the technologies patented in 2012.
Brief summaries of NETL’s 2012 patents, and licenses resulting from these patents, are presented below. NETL is seeking additional partners interested in licensing or further developing these technologies.
Improved Martensitic Steel for High-Temperature Applications (U.S. patents 8,317,944 and 8,246,767). The operating efficiency of coal-fired power plants is directly related to combustion system temperature and pressure. Incorporating ultrasupercritical (USC) steam conditions into power plants can increase
| Advanced stainless steel alloys and fabrication processes enhance corrosive resistance in high-temperature environments, such as steam and gas turbines. |
efficiency and reduce coal utilization, while reducing CO2emissions and other pollutants. Traditional materials of construction for boilers and turbines do not possess the optimal characteristics for operation under USC conditions. Advanced stainless steel alloys and fabrication processes are needed for operation under such extreme conditions. Martensitic grades of stainless steel that contain chromium (Cr) offer an alternative for high-temperature applications due to their corrosion resistance and ability to be hardened by heat treatment. These alloys are also potentially more cost-effective than nickel-based superalloys. NETL has developed a stainless steel composition and heat-treatment process for a high-temperature, titanium alloyed, iron-9 Cr-1 molybdenum steel exhibiting improved creep strength (the ability to resist deformation due to applied stress) and oxidation resistance at elevated temperatures. The material provides improved performance compared to commonly used high-temperature steels and requires a heat treatment consisting solely of high-temperature treatment, rapid cooling, tempering, and final cooling—avoiding the need for any hot-working at elevated temperatures. This technology will have applications in advanced high-temperature power plant components, including coal-fired boilers, steam and gas turbines, and piping, as well as other applications where heat- and oxidative-resistant stainless steel components are required.
Use of Pyrochlore and Hexaaluminate Catalysts for Reforming Hydrocarbon Fuels (U.S. patents 8,241,600; 8,142,756; and 8,133,463). Reforming methods to generate synthesis gas from simple hydrocarbons like methane have been available for many years. These
| Catalysts made from pyrochlore (top) and hexaaluminate (bottom) efficiently reform diesel fuel into hydrogen while maintaining thermal stability and resisting catalyst deactivation. |
processes routinely involve the use of a catalyst—a material that speeds up the reaction but is not consumed—to make the process economically feasible. However, the high sulfur and aromatic content of fuels such as diesel poses a major technical challenge, because these components can deactivate or &"poison” reforming catalysts. No economically feasible reforming catalyst is available for converting heavy hydrocarbons into hydrogen-rich synthesis gas for use in solid oxide fuel cells (SOFC)—a highly efficient, fuel-flexible, and low-emission energy source. To minimize catalyst poisoning while maintaining high activity, NETL researchers developed processes for incorporating active metals into the crystal structure of thermally stable materials including pyrochlore and hexaaluminate. Substituting various metals into the crystal structure can alter specific properties such as activity, selectivity, and thermal stability. This approach minimizes the poisoning effects that compromise traditional catalyst designs, improves performance, and reduces the level of expensive reforming metals. Together these inventions help overcome the limitations of current catalysts by efficiently reforming diesel fuel while maintaining thermal stability and resistance to sulfur, aromatics, and carbon formation. Through collaboration with industry, academia, and other government agencies, the superior function and value of these catalysts have been demonstrated, and significant advances have been made in development and deployment of commercially viable products. For example, NETL is working with Pyrochem Catalyst Corporation to further develop pyrochlore catalysts for use in SOFC auxiliary power units to provide non-propulsion power for vehicles, including long-haul truck transport, and to supply power in several military applications.
Process for CO2 Capture using Zeolites (U.S. patent 8,128,735). Carbon dioxide emitted from coal-fired power plants has been identified as a major factor in climate change. As a result, the separation and storage of CO2 from gaseous streams is being investigated as a way to reduce greenhouse gas
| Low-cost, zeolite-grafted amine sorbents may represent a breakthrough technology for CO2 capture from coal-derived flue gas. |
emissions. Zeolites are microporous, aluminosilicate minerals commonly used for a variety of adsorption processes including water purification. Current commercial processes for removing CO2 from high-pressure gas streams require gas to be cooled to ambient temperatures, which lowers thermal process efficiencies and increases cost. NETL researchers have developed a method to separate CO2 from high-pressure, moderate-temperature gas streams using a zeolite sorbent in a temperature swing adsorption/regeneration process. The NETL process is more efficient than other, commercial CO2-removal processes. Removing CO2 at moderate temperatures improves thermal efficiency, while recovering CO2 at high pressures contributes to low compression costs. Another benefit is that moisture in the gas stream does not affect the CO2 adsorption and desorption process. The availability of stable, high-capacity CO2-removal sorbents that can be regenerated at low-energy will significantly reduce the cost of CO2 capture and storage.
Apparatus and Method for Determining Solids Circulation Rate (U.S. patent 8,116,992). Gasification is a partial oxidation process that converts low-cost feedstocks such as coal, lignite, petcoke, and biomass into synthesis gas, which can then be used to produce electricity. Advanced gasification systems can use a variety of fossil fuel sources and produce near-zero emissions. Particle size and distribution within a gasification reactor can affect system performance and operating efficiency. Using conventional instrumentation to determine the circulation rate of coal or other solid particles within a reactor is difficult due to the harsh environment within the reactor system; in addition, high pressures with particulate-laden flows make it difficult to seal mechanical motion detectors across the pressure boundary. This NETL invention provides a method to measure differential pressure over known lengths of the gasifier standpipe in conjunction with gas velocity measurements. Monitoring the flow rate of fossil-fuel particles within a reactor will allow for better process control and lead to enhanced system efficiency, lower raw material use and reduced operational and maintenance costs. NETL’s apparatus and technique can be used in all solids-circulating systems at high or low temperatures. Ultimately, this technology is expected to be used in a variety of systems including circulating fluidized-bed combustion, circulating fluidized-bed gasification, transport reactor, chemical looping, and any other process where solids move in a packed bed with flowing gas.
Electric Current Locator (U.S. patent 8,111,059). Vacuum arc remelting (VAR) is a process used to refine alloys with the advanced properties and performance characteristics needed for applications in the aerospace, power generation, defense, and medical and nuclear industries. A VAR melt occurs within
| NETL’s electric current locator tracks the position of electric arcs within a vacuum arc remelting furnace, allowing for better process control and defect-free alloy production. |
a crucible typically made of copper, with a water jacket that cools the metal being formed. VAR is an expensive procedure, which sometimes produces an ingot that must be rejected because of defects or lack of uniformity. Maintaining control in the heat transfer and remelting process is critical to producing defect-free material. Current controls of the remelting process rely on system current and voltage, which cannot reliably show what the electric arcs are doing and what causes ingots to sometimes be defective. Without first knowing when problems occur, it is nearly impossible to fix them. NETL’s newly patented arc-sensing technology, the electric current locator (ECL), enables visualization of variations in arc positions (and hence energy distribution into the molten metal). Developed under a CRADA between NETL and the Specialty Metals Processing Consortium, the ECL tracks, in real-time, the positions of electric arcs inside the VAR furnace. Knowing where the arcs are shows the energy distribution to the molten metal during the remelting process and serves as a first step toward controlling them—and thereby controlling the melting process. Initially envisioned as monitoring device for processes such as VAR, the ECL technology can easily be retrofitted to existing furnaces.
Oxy-fuel Combustion with Integrated Pollution Control (U.S. patent 8,087,926). Flue gases derived from fossil-fueled power plants contain multiple compounds that must be captured at the plant to protect the environment. Working through a CRADA, scientists at NETL and Jupiter Oxygen Corporation developed an integrated process that combines oxy-combustion of coal with a process that removes multiple pollutants from the resulting flue gas, while concentrating CO2 and reducing overall energy consumption. The process can be applied to new or existing power plants to reduce the cost associated with flue gas cleanup. The patented process will facilitate carbon capture while also removing other coal-derived pollutants—including sulfur oxides, nitrogen oxides, and mercury—allowing for compliance with existing and emerging regulatory requirements. Jupiter continues to work with NETL to develop a pilot-scale boiler system incorporating Jupiter’s high-flame-temperature oxy-combustion technology and NETL’s integrated pollution removal technology. Results from this work will be used to develop improved computer models for designing next-generation oxy-fuel systems. This innovative approach in the field of carbon capture, coupled with the size of the test facility and burner capacities, will accelerate technology development so that large-scale demonstrations, and ultimately commercialization, can be realized for both new and retrofitted power plants.