James R. Fincke

Plasma Thermal Conversion of Methane to Acetylene

This paper describes a re-examination of a known process for the direct plasma thermal conversion of methane to acetylene. Conversion efficiencies (% methane converted) approached 100% and acetylene yields in the 90–95% range with 2–4% solid carbon production were demonstrated. Specificity for acetylene was higher than in prior work. Improvements in conversion efficiency, yield, and specificity were due primarily to improved injector design and reactant mixing, and minimization of temperature gradients and cold boundary layers. At the 60-kilowatt scale cooling by wall heat transfer appears to be sufficient to quench the product stream and prevent further reaction of acetylene resulting in the formation of heavier hydrocarbon products or solid carbon. Significantly increasing the quenching rate by aerodynamic expansion of the products through a converging–diverging nozzle led to a reduction in the yield of ethylene but had little effect on the yield of other hydrocarbon products. While greater product selectivity for acetylene has been demonstrated, the specific energy consumption per unit mass of acetylene produced was not improved upon. A kinetic model that includes the reaction mechanisms resulting in the formation of acetylene and heavier hydrocarbons, through benzene, is described.

Diagnostics and Control in the Thermal Spray Process

The plasma-spray process features complex plasma-particle interactions that can result in process variations that limit process repeatability and coating performance. This paper reports our work on the development of real-time diagnostics and control for the plasma spray process. The strategy is to directly monitor and control those degrees of freedom of the process that are observable, controllable and affect resulting coating properties. This includes monitoring of particle velocity and temperature as well as the shape and trajectory of the spray pattern. Diagnostics that have been developed specifically for this purpose are described along with the demonstration of a closed loop process controller based on these measurements.

Plasma spraying of alumina: Plasma and particle flow fields

A comprehensive experimental examination of the interaction between a subsonic thermal plasma jet and injected alumine, particles is presented. Measurements of plasma velocity, temperature, and entrained air were obtained from an enthalpy probe and mass spectrometer combination. A diffusive separation, or demixing, of the Ar and He plasma gas was observed. Centerline plasma velocities and temperatures ranged from 1501500 m/s and 2000 to 14,000 K, respectively, in the region between the torch and a typical substrate location of 90 mm. Measurements of particle size, velocity, tempearture and local number density were obtained from a combination laser particle sizing system, Laser doppler velocimeter (LDV), and two-color pyrometer. Centerline temperatures and velocities for the nominally 30 μm particles used were 2400–2800 K and 150–200 m/s, respectively.

Thermal Conversion of Methane to Acetylene

This report describes the experimental demonstration of a process for the direct thermal conversion of methane to acetylene. The process utilizes a thermal plasma heat source to dissociation products react to form a mixture of acetylene and hydrogen. The use of a supersonic expansion of the hot gas is investigated as a method of rapidly cooling (quenching) the product stream to prevent further reaction or thermal decomposition of the acetylene which can lower the overall efficiency of the process.

Empirical Study Of Tube Wave Suppression For Single Well Seismic Imaging

This report addresses the Idaho National Engineering and Environmental Laboratorys portion of a collaborative effort with Lawrence Berkeley National Laboratory and Sandia National Laboratories on a borehole seismic project called Single Well Seismic Imaging. The INEELs role was to design, fabricate, deploy, and test a number of passive devices to suppress the energy within the borehole. This energy is generally known as tube waves. Heretofore, tube waves precluded acquisition of meaningful single-well seismic data. This report addresses the INEEL tests, theories, observations, and test results.