Study on pulping performance of a novel coal water slurry additive for Shenhua coal slurry with high concentration
Shenhua coal is difficult to form slurry of high concentration, low viscosity for its strong hydrophilicity. Based on that, coal water slurry (CWS) additive, denoted as LS-A, was used to prepare Shenhua coal blending slurry with high concentration, and then the slurry ability, rheological characteristic and static stability of LS-A were investigated. The results show that, the performances of CWS were improved by LS-A, and it had good viscosity reducing effect. The slurry concentration could reach 65.5%, and the apparent viscosity is smaller than 1200 MPa·s with good flow property under 100 s-1 of shearing rate when the dosage of LS-A was 0.7%. The rheological investigation indicated that the slurry pumped with LS-A is pseudoplastic fluid, and it had rheological property of shear-thinning, evident thixotropic property and good stability. Moreover, the comparison of pulping properties and stability between LS-A and the additive SPHF-3 of National CWS Center showed that, the slurry ability was similar under same additive dosage.
A METHOD FOR OPTIMIZING COAL SLURRYING PROPERTY
An orthogonal experiment was conducted in laboratory to investigate the Shenhua coal water slurrying property.The regression equation was obtained by multi-factor regression and variance analysis,and the optimal additives ratio and particle size distribution were gained through a computer program optimization method.The results show that the optimization method can raise solid concentration of the Shenhua coal water slurry,and the concentration is increased from 59.51% to 62.36%.Furthermore,the stability and rheology of the coal water slurry are also improved after particle size gradation.
Review of Literature on Probability of Detection for Magnetic Particle Nondestructive Testing
Abstract : A critical review of the available literature concerning the minimum reliably detectable defect size aNDI for magnetic particle testing (MPT) in aerospace applications is presented. Four probability of detection (POD) studies relevant to detection of fatigue cracks in aircraft components were found over the period 1968 to 2011. As the statistical methods used in these four previous studies were either outdated or otherwise deficient, the original data were reanalysed using currently accepted techniques. A meta-analysis of the results is presented, with emphasis on statistical inferences for the defect size expected to be detected with 90% POD. It is shown that the minimum reliably detectable defect size aNDI = 2.0 mm currently specified by the Royal Australian Air Force for wet fluorescent magnetic particle inspection using the continuous method is consistent with estimates of the average performance of MPT derived from the reanalysis of the literature.