A swirling burner with adjustable inner secondary air flaring angle is proposed and a laboratory-scale opposed-firing furnace is built. The effects of burner flaring angle on dense-dilute low-NO x burning are experimentally studied. The temperature distributions along the depth and height direction of furnace are emphatically illustrated. NO x emission and char burnout are compared and discussed. Experiment results indicate that under the dense-dilute burning conditions, variation of burner inner secondary air flaring promotes ignition conditions. Under different conditions of dense-dilute ratio, variation of burner flaring angle can help decreasing NO x emission and improving char burnout. Finally the optimum flaring angle of swirling burner under different dense-dilute ratios is summarized in the form of curves, which could provide reference for exquisite and novel combustion adjustment.
Annulus pressure build-up is a potentially serious issue with high-pressure and high-temperature wells created by annuli which maybe heated up during production. Considering the mass conservation, energy conservation, and heat stability of fluid, the pressure-volume interaction models of multi-scale annulus are established based on PVT and the matrix of micro-annular temperature fields. Results indicate that the pressure-volume interaction moves the balance point of adjacent annulus early, which is a potentially serious issue for well integrity. The relationship between annulus temperature and pressure is linear. Moreover, at the same production, annulus pressure rapidly rises as the temperature increases, and the change rate of temperature increases at a negative exponential function. After the same production time, the relationship among temperature, pressure, and production is a quadratic function.
Considering the influence of flattening of casing cross-section on collapse, the stress equivalence principle was applied to conclude the triaxial stress and collapse strength. The method to determine casing collapse strength considering flattening of casing cross-section was established. The diameter-to-thickness ratio had a major influence on the flattening of the casing cross-section compared with curvature. For the 5 1/2”×7.72mm P110 casing, the flattening coursed by the 0.01/m curvature decreased the collapse strength concluded by API 5C3 by approximately 7.5%.
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