People often ask about what FCS means when we talk about technology transfer; specifically, how does it differ from training. After all, it could be said that all training, our strong suit, is technology transfer.
Technology transfer is NOT “generic training” on a well-established technology such as the fundamentals of electricity for power plant generators. Instead, technology transfer deals with the introduction of new technologies that are often groundbreaking and new to the power industry. In some cases, the technology has been introduced as an experiment or on a pilot basis, but not yet (or ever) adopted by the power utility industry on a commercial scale.
One good example of new technology is Integrated Gasification combined cycle (IGCC) power plants. In an IGCC plant, a gasifier is used to convert coal or similar fuels to “syngas” which has carbon monoxide and hydrogen that is then burned in gas turbines that are part of a combined cycle power plant. The gasification process involves oxidation of coal with pure oxygen from an air separation unit (ASU) in a gasifier vessel at high pressure (300 to 800 psig). FCS has also developed training and documentation for an IGCC power plant that gasified petroleum coke from a refinery. The sulfur in the syngas was removed in a sulfur recovery unit before being burned in gas turbines at the power plant.
FCS also worked with a team that included the U.S. Department of Energy National Energy Technology Laboratory (NETL) to develop an operator training simulator for a large scale IGCC plant that uses a coal gasifier that is supplied with high-pressure oxygen from an ASU to produce syngas from coal. Mercury and sulfur are removed from the syngas using chemical processes. The syngas is burned in gas turbines in a 2 x 1 combined cycle power plant. This simulator is installed in NETLs AVESTAR (Advanced Virtual Energy Simulation Training and Research) center in West Virginia and also at West Virginia University. This simulator incorporates virtual reality to allow trainees to walk through the power plant and operate field equipment such as manually operated valves, as well as performing operations from DCS screens.
Another new technology that is part of the AVESTAR IGCC simulator is carbon capture which is part of a technology called Carbon Capture and Sequestration (CCS), which is implemented, in part, to reduce CO2 emissions to the atmosphere. Most of the carbon dioxide that is produced in the gasification process is captured by passing the syngas through a solvent at high pressure and relatively low temperature that absorbs the CO2. The CO2 is then removed from the solvent by heating the solvent and dropping its pressure. The CO2 is then compressed for sequestration.
Although the scope IGCC simulator did not include sequestration, the most common mode of sequestration in CCS is to inject the CO2 in geologically stable geological formations or to use the CO2 in old oil wells that we unproductive without injection of CO2 to push the oil out of the wells, a process called Enhance Oil Recovery (EOR). A recent example of CO2 capture and EOR is the NRG/Petro Nova project installed to process part of the flue gas (39%) from one 615 MW unit at NRG’s Parrish power plant; the project, the largest in the world, was commissioned in January 2017. The CO2 captured is used for EOR in nearby oil fields. Another example is the Canadian Boundary Dam CCS project in Saskatchewan, commissioned in 2014, the CO2 from a 110 MW lignite-fired power plant is used for EOR in oil fields near the plant.
Another example of relatively new technology is coal-fired fluidized bed boilers with limestone that are used to capture sulfur and thus minimize both SO2 and NOx emissions. In fluidized bed boilers, combustion and fluidizing air are admitted beneath a bed of fuel in the bottom of the boiler. By controlling the air admitted, the result is combustion of the fuel at a relatively low temperature as compared to coal-fired power plant boilers that use pulverized coal fired in suspension in the furnace. The low combustion temperature minimizes the production of thermal NOx. SO2 emissions are minimized by mixing crushed limestone with fuel fluidized bed. A chemical reaction between the sulfur in the fuel and the limestone captures the sulfur.
Admission of fluidizing air beneath the bed in the fluidized bed boiler results in a large number of unburned coal particles and ash with high carbon content being blown into the furnace. In a circulating fluidized bed boiler, the ash and unburned fuel in the flue gas leaving the furnace is captured in a cyclone separator and recirculated back to the bed for complete combustion.
FCS has developed training material and documentation for several large power plant CFB boilers.
Another new technology in which FCS has supported technology transfer is concentrated solar power (CSP). CSP power plants use mirrors to concentrate sunlight on a steam generator that is used to generate steam for a Rankine cycle. FCS has developed training material and conducted training for the 377 MW, three-unit Ivanpah power plant, which is the largest CSP power plant in the world.
Many other new technologies have not yet been adopted on a commercial scale but may be applied in the future. FCS monitors these technologies to be in a position to serve customers that may implement these technologies in the future. Examples of these technologies include:
Fluidized Bed Boiler Gasification
These fluidized bed boilers gasify biomass, such as wood waste, to produce syngas. The syngas from these boilers, like that from coal gasification processes, is composed of carbon monoxide, hydrogen and methane as well as noncombustible nitrogen, carbon dioxide, and water. Unlike the coal gasifiers in IGCC plants, pure oxygen at high pressure is not needed, and so the ASU, with its cost and complexity, is not required. The heat from the boiler produces steam for a Rankine cycle plant. The syngas can be burned in gas turbines or in the boiler as supplemental fuel. The result is increased thermal efficiency. An advantage to the use of biomass is a reduction in the net CO2 released to the atmosphere per BTU that is produced when considering the cycle from growth of the biomass, which captures CO2 as carbon in the biomass, to burning the biomass, which releases the carbon as CO2 to the atmosphere again.
Chemical looping is a process for burning fossil fuels efficiently in a way that makes CO2 capture more efficient. The CO2 in the flue gas from a typical coal-fired power plant boiler is around 12% to 15% CO2; most of the rest of the flue gas is nitrogen, oxygen and water as steam. Capture of CO2 from this mixture using a solvent as described for the AVESTAR simulator is an expensive process that increases auxiliary power consumption considerably. Chemical looping produces a stream of flue gas that is principally CO2 and steam; the steam can be easily removed by condensation allowing the carbon dioxide to be compressed for sequestration without chemical processing.
The key to chemical looping is to burn fossil fuels, including natural gas and coal, with oxygen from a substance (called the oxygen carrier), such as a metal oxide, rather than air. There are two main chemical processes in the chemical looping. In the first process, the oxygen carrier is oxidized (“burned”) at high temperature in an air reactor using atmospheric air, to produce an oxide, which is a chemical compound that contains oxygen. The oxygen carrier compound is mixed with the fossil fuel at high temperature. The oxygen in the oxygen carrier compound is released to oxidize (burn) the fossil fuel in the fuel reactor. The heat released from the oxidization of the fossil fuel is used to generate steam in a Rankine cycle. The combustion products from the fuel reactor are CO2 and steam as flue gas and oxygen carrier that has been stripped of oxygen. The oxygen carrier is recirculated back to the air reactor to sustain the cycle.
Considerable research in chemical looping has been done overseas, including at the Chalmers University of Technology in Sweden. At Chalmers, three pilot and prototype systems (ranging in size from 10 kWt to 100 kWt – kWt is kilowatts, thermal) have been built and tested, burning both methane and solid fuels (coal and petroleum coke). The oxygen carriers used were ilmenite (iron titanium oxide – FeTiO3), and copper oxide (CuO) calcined with aluminum oxide (Al2O3) and Magnesium aluminate (MgAl2O4). Darmstadt University in Germany has developed a 1 MWt prototype system using ilmenite as the oxygen carrier and burning solid fuels.
In the United States, Alstom has worked to develop a process that it has trademarked as LCLTM (LimestoneBased Chemical Looping), which uses calcium sulfide (CaS) as the oxygen carrier. When calcium sulfide is oxidized, it produces Calcium sulfate (CaSO4). The advantage of this approach is that when used with coal and petroleum coke that contain sulfur, the sulfur in the fuel is captured. Alstom has tested this process in a 3 MWt prototype.
Many of the technologies described above are “on the shelf” at this writing because of the low cost of natural gas, and the current politics of “clean coal” and regulation of regulation of CO2 emissions to the atmosphere in the United States. No one knows what the future will bring, however, and so it is important for our customers to know that FCS has demonstrated a capability to help our customers to deal with the challenges of implementing new technologies.