Gas-Solid Two Phase Flow in Internally Circulating Two-Stage Spouted Desulfurization Tower
To study the circulating fluidized bed desulfurization tower flowing fields, a two-stage spouted tower was presented and an experimental installation was established. Experimental studies on flow fields have been carried out by using a particle dynamic analyzer (PDA). Results indicate: The stable annular flow patterns is obtained in the two-staged esulphurized tower. The irregular and uniform flow is advantage to strength mass transfer at the Veturi inlet of tower. The result of stable back flow of particle at the wall makes it possible that atomizing humidified water or slurry can not directly eject the wall of the tower. At the assurance of atomized covering area, the fact ensures that humid scaling will not be produced at the wall. Micro-particle in gas can be arrested stable dynamic particle layer forming from the particular two stages spouted structure combined proper aggregate accelerating agent.
Research on velocity distribution in semi-dry flue gas desulfurization tower
As an accurate high-quality instantaneous measurement technology, particle image velocimetry (PIV in acronym) has applied widely in single-phase flow and multiphase flow. The velocity distribution in semi-dry FGD tower directly influences gas-solid mix and contact situation. In base of the tower, gas-solid two-phase flow field is more complex, and has the quite tremendous influence to the overall system desulphurization efficiency. This paper utilized PIV to study velocity distribution in Semi-dry flue gas desulfurization tower and obtained velocity distribution.
Assessment of fractures in endodontically treated teeth restored with and without root canal posts using high-resolution cone beam computed tomography
Background Root fractures are a diagnostic challenge for dentists in endodontic treatment. This study aimed to determine the relationship between the characteristics of tooth fractures and the presence of root canal posts in endodontically treated teeth using high-resolution cone beam computed tomography (CBCT). Material and Methods Fifty high-resolution CBCT scans of endodontically treated teeth with a diagnosis of fracture were obtained, of which 30 were from women and 20 were from men. These scans were acquired with three Veraviewepocs 3D units and one 3D Accuitomo 170 unit, with a 40 × 40-mm field of view and 125 μm voxel size. The variables assessed included the type of fracture, extent of fracture, type of retention, post length, cause of endodontic failure, location of the lesion, and time required to detect the fracture (difficulty score). For data analysis, the chi-squared test, Student’s t-test, and multiple linear regression (α <0.05) were used. Results No association was found between the type of fracture and type of retention or between the type of fracture and its extent (P>0.05). On the other hand, the type of fracture significantly influenced the time required for its detection. Additionally, the most difficult plane for detecting the fracture and the difficulty score were associated, with statistically significant results. Conclusions The type of fracture in endodontically treated teeth was not associated with the type of post used for restoration. All of the CBCT systems used to detect tooth fracture showed the same efficiency. Key words:Cone-Beam CT, Tooth Fracture, Root Canal Post.