Volatilization and Ignition of Oil Sand Samples During Intermittent Exposure to Hot Low-Velocity Air Streams

1989 ◽  
Vol 111 (2) ◽  
pp. 104-109 ◽  
Author(s):  
G. A. Karim ◽  
A. Hanafi ◽  
S. A. Mehta
Keyword(s):  
Combustion Front ◽  
Stream Temperature ◽  
Oil Sand ◽  
Low Velocity ◽  
Slow Cooling ◽  
Heated Air ◽  
Intermittent Exposure ◽  
Air Streams ◽  
In Situ Recovery

The behavior of small oil sand samples was monitored experimentally when subjected repeatedly to low-velocity heated air streams, with either prompt quenching or slow cooling of the samples to their initial temperatures between these exposures. The stream temperature was either in the range of 300°C to 500°C in air or at higher temperatures of up to 760°C, while being exposed to the products of combustion of very lean hydrogen-air mixtures. This was done in relation to understanding better the associated processes in some in-situ recovery trials where stoppage of the combustion front and/or the flow of the injected fluids can occur. A variety of multi-exposure-cooling schemes was considered and their effects on the extent of volatilization and ignition established. Comparison to the corresponding behavior of similar samples under uninterrupted exposure to the heated streams was made throughout.

scholarly journals Cosmic-Ray Driven Outflows to Mpc Scales from L* Galaxies

2020 ◽  
Author(s):  
Philip F Hopkins ◽  
T K Chan ◽  
Suoqing Ji ◽  
Cameron B Hummels ◽  
Dušan Kereš ◽  
...  
Keyword(s):  
Cosmic Ray ◽  
Plane Layer ◽  
Equilibrium Density ◽  
Pressure Gradients ◽  
Low Velocity ◽  
Star Forming ◽  
Stellar Feedback ◽  
Massive Halos ◽  
Halo Masses

Abstract We study the effects of cosmic rays (CRs) on outflows from star-forming galaxies in the circum and inter-galactic medium (CGM/IGM), in high-resolution, fully-cosmological FIRE-2 simulations (accounting for mechanical and radiative stellar feedback, magnetic fields, anisotropic conduction/viscosity/CR diffusion and streaming, and CR losses). We showed previously that massive (Mhalo ≳ 1011 M⊙), low-redshift (z ≲ 1 − 2) halos can have CR pressure dominate over thermal CGM pressure and balance gravity, giving rise to a cooler CGM with an equilibrium density profile. This dramatically alters outflows. Absent CRs, high gas thermal pressure in massive halos “traps” galactic outflows near the disk, so they recycle. With CRs injected in supernovae as modeled here, the low-pressure halo allows “escape” and CR pressure gradients continuously accelerate this material well into the IGM in “fast” outflows, while lower-density gas at large radii is accelerated in-situ into “slow” outflows that extend to >Mpc scales. CGM/IGM outflow morphologies are radically altered: they become mostly volume-filling (with inflow in a thin mid-plane layer) and coherently biconical from the disk to >Mpc. The CR-driven outflows are primarily cool (T ∼ 105 K) and low-velocity. All of these effects weaken and eventually vanish at lower halo masses (≲ 1011 M⊙) or higher redshifts (z ≳ 1 − 2), reflecting the ratio of CR to thermal+gravitational pressure in the outer halo. We present a simple analytic model which explains all of the above phenomena. We caution that these predictions may depend on uncertain CR transport physics.

Turbulent plumes of heat, moist heat, and carbon dioxide elicit upwind anemotaxis in tsetse flies Glossina morsitans morsitans Westwood (Diptera: Glossinidae)

2002 ◽  
Vol 80 (7) ◽  
pp. 1149-1155 ◽  
Author(s):  
W G Evans ◽  
R H Gooding
Keyword(s):  
Carbon Dioxide ◽  
Wind Tunnel ◽  
Relative Humidity ◽  
Glossina Morsitans Morsitans ◽  
Tsetse Flies ◽  
Glossina Morsitans ◽  
Low Velocity ◽  
Upwind Flight ◽  
Moist Heat ◽  
Heated Air

The roles and interactions of turbulent plumes of heat, moist heat, and carbon dioxide in mediating upwind flight of adult tsetse flies (Glossina morsitans morsitans Westwood) were investigated using a wind tunnel in a constant-environment chamber. Heat fluctuations in the plume that were detected by a thermocouple and displayed as oscilloscope traces allowed direct visualization of the structures of the plumes. Significantly more flies flew upwind when exposed to plumes of (i) carbon dioxide (0.0051% above background) and air (58% relative humidity) compared with air alone; (ii) carbon dioxide and heated air (35% relative humidity and temperature fluctuating up to 0.09°C above background) compared with carbon dioxide and air; and (iii) carbon dioxide and moist (82% relative humidity) heated air (temperature fluctuating up to 0.05°C above background) compared with carbon dioxide and heated air. However, there were no significant differences in upwind flight of flies exposed to plumes of (i) air compared with humidified air (65% relative humidity); (ii) carbon dioxide and heated air compared with heated air alone; and (iii) carbon dioxide and moist heated air compared with moist heated air alone. Recorded temperature fluctuations in heat plumes transported downwind from a tethered steer in a pasture showed patterns similar to those produced in the wind-tunnel plumes. These results suggest that host emissions of carbon dioxide alone and combined heat and moisture carried downwind by low-velocity winds elicit upwind anemotaxis in tsetse flies, which distinguish these emissions from a background of lower atmospheric levels.

Fuel Formation and Conversion During In-Situ Combustion of Crude Oil

SPE Journal ◽  
2013 ◽  
Vol 18 (06) ◽  
pp. 1217-1228 ◽  
Author(s):  
Hascakir Berna ◽  
Cynthia M. Ross ◽  
Louis M. Castanier ◽  
Anthony R. Kovscek
Keyword(s):  
Oil Recovery ◽  
Photoelectron Spectroscopy ◽  
Combustion Front ◽  
Combustion Products ◽  
Combustion Tube ◽  
Cross Sectional ◽  
In Situ Combustion ◽  
X Ray ◽  
Study Results

Summary In-situ combustion (ISC) is a successful method with great potential for thermal enhanced oil recovery. Field applications of ISC are limited, however, because the process is complex and not well-understood. A significant open question for ISC is the formation of coke or "fuel" in correct quantities that is sufficiently reactive to sustain combustion. We study ISC from a laboratory perspective in 1 m long combustion tubes that allow the monitoring of the progress of the combustion front by use of X-ray computed tomography (CT) and temperature profiles. Two crude oils—12°API (986 kg/m3) and 9°API (1007 kg/m3)—are studied. Cross-sectional images of oil movement and banking in situ are obtained through the appropriate analysis of the spatially and temporally varying CT numbers. Combustion-tube runs are quenched before front breakthrough at the production end, thereby permitting a post-mortem analysis of combustion products and, in particular, the fuel (coke and coke-like residues) just downstream of the combustion front. Fuel is analyzed with both scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). XPS and SEM results are used to identify the shape, texture, and elemental composition of fuel in the X-ray CT images. The SEM and XPS results aid efforts to differentiate among combustion-tube results with significant and negligible amounts of clay minerals. Initial results indicate that clays increase the surface area of fuel deposits formed, and this aids combustion. In addition, comparisons are made of coke-like residues formed during experiments under an inert nitrogen atmosphere and from in-situ combustion. Study results contribute to an improved mechanistic understanding of ISC, fuel formation, and the role of mineral substrates in either aiding or impeding combustion. CT imaging permits inference of the width and movement of the fuel zone in situ.

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