Morphology and size of soot from gas flares as a function of fuel and water addition

A large-scale, laboratory turbulent diffusion flame was used to study the effects of fuel composition on soot size and morphology. The burner and fuels are typical of those used in the upstream oil and gas industry for gas flaring, a practice commonly used to dispose of excess gaseous hydrocarbons. Fuels were characterized by their carbon-to-hydrogen ratio (from 0.264 to 0.369) and their volumetric higher heating value (HHVv) (from 35.8 to 75.2 MJ/m3). Transmission electron microscopy (TEM) was used to assess primary particle and aggregate size, showing that the scaling of primary particle size to aggregate size was roughly the same for all of the considered fuels (dp = 16.3(da,100 [nm]/100)0.35). However, fuels with higher HHVv produced substantially larger soot aggregates. A scanning mobility particle sizer (SMPS) was also used (i) to measure mobility diameter distributions and (ii) in tandem with a centrifugal particle mass analyzer (CPMA) to determine the two-dimensional mass-mobility and effective density-mobility distributions using a new inversion approach. The new approach was shown to improve internal consistency of inferred morphological parameters, though with a shift relative to median-based analysis of the tandem data. Raman spectroscopy was used to quantify the degree of graphitization in the soot nanostructure. The addition of water to the fuel consistently reduced the soot yields but did not affect other morphological parameters. Larger aggregates also tended to have larger primary particles and higher Raman D/G ratios suggesting larger graphitic domains

Functional and Hemodynamic Cardiac Determinants of Exercise Capacity in Patients With Systolic Heart Failure

Decreased exercise capacity is the main symptom in patients with heart failure (HF). We assessed the association among noninvasively determined maximal cardiac output at exercise, systolic and diastolic cardiac functions at rest, and peak oxygen uptake (pVo(2)) exercise capacity in patients with congestive HF. We studied 102 patients 62 ± 11 years of age with New York Heart Association class II to IV stable HF and left ventricular (LV) ejection fraction <45%. All patients underwent echocardiography and a treadmill cardiopulmonary exercise test for evaluation of pVo(2) corrected for fat-free mass. During the cardiopulmonary exercise test, cardiac output was estimated noninvasively and continuously using Nexfin HD. Fat-free mass-corrected pVo(2) was associated in an univariate linear regression analysis with peak exercise cardiac index (CI) (beta 0.511, p <0.001), LV end-diastolic pressure estimates (peak early diastolic filling velocity/early diastolic tissue velocity [E/e'], beta -0.363, p = 0.001), and right ventricular function (tricuspid annular plane systolic excursion, beta 0.393, p <0.001). In multivariate analysis peak exercise CI (beta 0.380, p = 0.001), but not cardiac output or LV ejection fraction at rest, was an independent predictor of pVo(2). Other independent predictors of pVo(2) were E/e' (beta -0.276, p = 0.009) and tricuspid annular plane systolic excursion (beta 0.392, p <0.001), also when adjusted for age and gender. In conclusion, peak CI is an independent predictor of fat-free mass-corrected pVo(2) in patients with systolic HF. Of all echocardiographic parameters at rest, right ventricular function and E/e' were independently and significantly associated with pVo(2), whereas LV ejection fraction at rest was no

Using two-dimensional distributions to inform the mixing state of soot and salt particles produced in gas flares

Gas flaring is a common practice in the oil and gas industry, where droplets of flowback water with varying levels of dissolved salts (mainly composed of sodium and chloride) often become entrained in the flared gas. In this study, we examine the mixing state of the aerosol produced by a laboratory flare with and without entrained droplets of sodium chloride solutions. The resultant aerosol is cross-examined using several different methods, including: transmission electron microscopy (TEM), tandem measurements using a CPMA and a differential mobility analyzer (DMA), tandem measurements using a centrifugal particle mass analyzer (CPMA) and a single particle soot photometer (SP2), and Raman spectroscopy. A focus is placed on two-dimensional distributions of properties and the kind of morphological information contained therein. The TEM and CPMA-SP2 measurements both show that the majority of soot particles were internally mixed with salt, while TEM and CPMA-DMA measurements indicate that there are also a large number of isolated salt particles