Marc A. Duchesne

High temperature monitoring of an oxy-fuel fluidized bed combustor using femtosecond infrared laser written fiber Bragg gratings

Femtosecond pulse duration infrared laser (fs-IR) written fiber Bragg gratings (FBGs), have demonstrated great potential for extreme environment sensing. Harsh environments are inherent to the advanced power plant technologies under development to reduce greenhouse gas emissions. The performance of new power systems are currently limited by the lack of sensors and controls capable of withstanding the high temperature, pressure and corrosive conditions present. This paper discusses fabrication and deployment of several fs-IR written FBG arrays, for monitoring the temperature distribution within a fluidized bed combustor. Results include: calibration data to ~ 1100 °C, discussion of deployment strategies, contrast with thermocouple data, and comments on reliability.

Entrained-flow gasifier and fluidized-bed combustor temperature monitoring using arrays of fs-IR written fiber Bragg gratings

Femtosecond written fiber Bragg gratings, have shown great potential for sensing in extreme environments. This paper discusses the fabrication and deployment of several fs-IR written FBG arrays, for monitoring main-spool skin temperatures of an entrained-flow gasifier, as well as the internal temperature gradient of a fluidized bed combustor.

Combustor deployments of femtosecond laser written fiber Bragg grating arrays for temperature measurements surpassing 1000 °C

Femtosecond Infrared (fs-IR) laser written fiber Bragg gratings (FBGs), have demonstrated great potential for extreme sensing. Such conditions are inherent to advanced power plant technologies and gas turbine engines, under development to reduce greenhouse gas emissions; and the ability to measure temperature gradients in these harsh environments is currently limited by the lack of sensors and controls capable of withstanding the high temperature, pressure and corrosive conditions present. This paper reviews our fabrication and deployment of hundreds of fs-IR written FBGs, for monitoring temperature gradients of an oxy-fuel fluidized bed combustor and an aerospace gas turbine combustor simulator.

Vanadium Oxidation State Determination by X‐Ray Absorption Spectroscopy

Vanadium is found in slags produced during metal refinement and fossil fuel combustion/gasification. The oxidation state of vanadium in slag has technological and environmental implications. For example, it may affect slag flow and refractory wear inside reactors, as well as leachability and toxicity of industrial by-products. Determination of vanadium’s oxidation state in crystalline phases can be achieved via the widely adopted X-ray diffraction (XRD) technique. However, this technique does not provide information on vanadium in amorphous phases. The objective of this research is to determine the oxidation state of vanadium in petroleum coke gasification samples and laboratory samples using X-ray absorption spectroscopy (XAS) with Canadian Light Source’s soft X-ray micro-characterization beamline (SXRMB). Linear combination fitting of XAS spectra with reference samples allowed quantitative determination of vanadium speciation.

Slag Surface Tension Measurements with Constrained Sessile Drops

Physical properties of slag are critical in the design and operation of refining technologies and slagging energy systems. The surface tension of slag impacts phenomena such as granulation, foaming, removal of solid inclusions, erosion of refractory and fouling. In this study, slag sessile drops formed on graphite, alumina and molybdenum substrates were compared. Use of graphite resulted in the largest contact angles, a desirable trait for surface tension measurements, but also led to reactions with the slag. Alumina and molybdenum were less reactive, but resulted in contact angles too small for measurements. When sessile drops were constrained by small substrate diameters to increase the apparent contact angle, surface tension measurements could be achieved with alumina and molybdenum substrates. The surface tension of coal slag was measured at up to 1600 °C in oxidizing and reducing gas atmospheres.

Understanding Phase Equilibria in Slags Containing Vanadium

In modern high temperature entrained flow gasifiers, the extensive use of petroleum coke (petcoke) as a replacement for or an addition to coal as a carbon feedstock introduces an appreciable amount of vanadium in the molten slag, resulting in unknown chemical and physical slag properties. A long-term research effort to understand phase equilibria of Al2O3-CaO-FeO-SiO2-V2O3 slag system representative of that commonly found in coal/petcoke carbon feedstock mixtures was initiated by the U.S.-DOE NETL. In collaboration with CanmetENERGY and McGill University, synthetic vanadium bearing slag was investigated for phases formed under controlled temperature, partial pressure of oxygen, and composition. The slag compositions representing U.S. and Canadian coal and petcoke ashes are considered in this work. Equilibrium phase diagrams of the vanadium slag systems are reported.

A Thermodynamic Study of Mixed Carbon Feedstock Gasification Slags

Integrated Gasification Combined Cycle used in power and chemical production is considered a clean technology, with the ability to capture almost all CO2, NOx, and SOx emissions. In entrained bed slagging gasifiers, molten slags formed from feedstock’s non-volatile impurities contribute to gasifier liner degradation and can cause gasifier clogging, affecting system efficiency and operation. Increased petcoke use as a key feedstock in addition to or as a replacement for coal has drastically modified slag chemistry, leading to unknown chemical/physical slag properties and behavior in the gasifier. In this work, thermodynamic phase equilibria in synthetic slags (Al2O3-CaO-FeO-SiO2-V2O3) were evaluated under simulated gasifier conditions to establish an understanding of the phase equilibrium in these slag systems. The effects of V2O3 content, slag chemistry, and additives on amorphous and crystalline phases were studied. In this study, increasing calcium oxide and iron oxide additive agents was found to lower the slag melting temperature and caused the karelianite (V2O3) crystal size to increase. Equilibrium phase diagrams showing the additive effect on the mixed coal-petcoke slag systems studied were constructed.