Impacts of Air-Assist Flare Blower Configurations on Flaring Emissions

Air-assisted flares, operating under low flow conditions (<1% of maximum flow) with low BTU gases, have relatively narrow bands of air-to-vent gas ratios that can achieve destruction and removal efficiencies (DREs, fraction of waste gases destroyed by complete and incomplete combustion) greater than 98%. If blower configurations are not able to operate within these narrow bands, emissions may be greater than those predicted based on 98% DRE, but if air-assist rates can be finely tuned, emissions much lower than those predicted assuming 98% DRE are achievable. This work examines the potential impact on emissions of using four different blower configurations (single fixed speed, dual fixed speed, single variable speed, and dual variable speed) on an air-assisted flare. Typical patterns of flare vent gas flow rates were obtained from hourly data on flared gas flow rates from Houston, Texas. The analyses indicate that flare emissions can be much greater (up to a factor of 40) than a base case assuming 98% DRE if single, fixed speed blower configurations are used. Conversely, flare emissions can be much lower than a base case assuming 98% DRE if air-assist rates can be closely matched to stoichiometric requirements

Application of the Carbon Balance Method to Flare Emissions Characteristics

The destruction and removal efficiency (DRE) computation of target hydrocarbon species in the flaring process is derived using carbon balance methodologies. This analysis approach is applied to data acquired during the Texas Commission on Environmental Quality 2010 Flare Study. Example DRE calculations are described and discussed. Carbon balance is achieved to within 2% for the analysis of flare vent gases. Overall method uncertainty is evaluated and examined together with apparent variability in flare combustion performance. Using fast response direct sampling measurements to characterize flare combustion parameters is sufficiently accurate to produce performance curves on a large-scale industrial flare operating at low vent gas flow rates

Confined Chemical Fluid Deposition of Ferromagnetic Metalattices

A magnetic, metallic inverse opal fabricated by infiltration into a silica nanosphere template assembled from spheres with diameters less than 100 nm is an archetypal example of a “metalattice”. In traditional quantum confined structures such as dots, wires, and thin films, the physical dynamics in the free dimensions is typically largely decoupled from the behavior in the confining directions. In a metalattice, the confined and extended degrees of freedom cannot be separated. Modeling predicts that magnetic metalattices should exhibit multiple topologically distinct magnetic phases separated by sharp transitions in their hysteresis curves as their spatial dimensions become comparable to and smaller than the magnetic exchange length, potentially enabling an interesting class of “spin-engineered” magnetic materials. The challenge to synthesizing magnetic inverse opal metalattices from templates assembled from sub-100 nm spheres is in infiltrating the nanoscale, tortuous voids between the nanospheres void-free with a suitable magnetic material. Chemical fluid deposition from supercritical carbon dioxide could be a viable approach to void-free infiltration of magnetic metals in view of the ability of supercritical fluids to penetrate small void spaces. However, we find that conventional chemical fluid deposition of the magnetic late transition metal nickel into sub-100 nm silica sphere templates in conventional macroscale reactors produces a film on top of the template that appears to largely block infiltration. Other deposition approaches also face difficulties in void-free infiltration into such small nanoscale templates or require conducting substrates that may interfere with properties measurements. Here we report that introduction of “spatial confinement” into the chemical fluid reactor allows for fabrication of nearly void-free nickel metalattices by infiltration into templates with sphere sizes from 14 to 100 nm. Magnetic measurements suggest that these nickel metalattices behave as interconnected systems rather than as isolated superparamagnetic systems coupled solely by dipolar interactions