Showing papers by "Saroj Kumar Mohapatra published in 2019"

CFD modeling of erosion wear in pipe bend for the flow of bottom ash suspension

Abstract: In the present study, erosion wear behavior of slurry pipeline due to solid–liquid suspension in the pipeline has been investigated using commercial computational fluid dynamics (CFD) code FLUENT. A multiphase Euler–Lagrange model was adopted to predict the solid particle erosion wear in a 90° pipe bend for the flow of bottom ash–water suspension. A standard k–e turbulence modeling scheme was used to simulate the flow through the pipeline. Water and bottom ash were taken as liquid and as a dispersed phase of solid–liquid mixture, respectively. A simulation study for erosion wear in a pipe bend was carried out to investigate the influence of various parameters including velocity, solid concentration, and particle size. The velocity of the bottom ash–water suspension varied from 0.5 to 2.5 m/s for solid concentrations with a range of 2.5 to 10.0% (by volume). The particle diameters of the bottom ash were 162 and 300 µm. The simulation results agree with the results of previous studies.

Study on role of particle shape in erosion wear of austenitic steel using image processing analysis technique

Abstract: Properties of flowing media (e.g. such as fly ash, bottom ash, coal, mineral tailings, sand slurries, etc.) play a crucial role in the service life of centrifugal slurry pump components. Generally, these solid particles vary in shape and size. In literature, a limited number of studies have been carried out to investigate the influence of particle size and shape on erosion wear. Stainless steel (SS 316L) is the most commonly used material for the fabrication of slurry pump components namely, casing, impeller, shafts, and sealing columns. In the present study, the influence of particle type and circularity factor on erosion wear of austenitic steel has been studied. A slurry pot tester (Ducom TR-41) was used to perform the experiments that established the erosion wear of slurry pump austenitic steel under the influence of the parameters noted above. Abrasives used in the current study are fly ash, bottom ash, and sand. Surface smoothness, circularity factor, coefficient of variance, sphericity, and solidit...

Erosion wear performance of Ni-Cr-O and NiCrBSiFe-WC(Co) composite coatings deposited by HVOF technique

Abstract: Purpose This study/paper aims to investigate the erosion wear performance of Ni-based coatings [Ni-Cr-O and NiCrBSiFe-WC(Co)] under sand-water slurry conditions. Design/methodology/approach A high-velocity oxy-fuel (HVOF) process was used to deposit the Ni-based coatings [Ni-Cr-O and NiCrBSiFe-WC(Co)] on the surface of stainless steel (SS 316L) substrate. A Ducom TR-41 erosion tester was used to conduct the tribological experiments on bare/HVOF coated SS 316L. The erosion wear experiments were carried out for different time durations (1.30-3.00 h) at different impact angles (0-60°) by running the pot tester at different rotational speeds (600-1,500 rev/min). The solid concentration of sand slurry was taken in the range of 30-60 Wt.%. The surface roughness of Ni-based coated surfaces was also measured along the transverse length of the specimens. Findings Results show the arithmetic mean roughness (Ra) values of Ni-Cr-O and NiCrBSiFe-WC coated SS-316L were 7.04 and 6.67 µm, respectively. The erosion wear SS-316L was almost 3.5 ± 1.5 times greater than that of the NiCrBSiFe-WC coatings. NiBCrSi-WC(Co) sprayed SS-316L showed lower erosion wear than Ni-Cr-O sprayed SS-316L. Microscopically, the eroded Ni-Cr-O coating underwent plowing, microcutting and craters. Ni-Cr-O coating have shown the ductile nature of erosion wear mechanism. NiBCrSi-WC(Co) surface underwent craters, plowing, carbide/boride pullout, fractures and intact. Erosion wear mechanisms on the eroded surface of NiBCrSi-WC(Co) were neither purely ductile nor brittle. Practical implications It is a useful technique to estimate the erosion wear of hydraulic machinery coated with Ni-based coatings imposed under mining conditions. Originality/value The erosion wear performance of HVOF-sprayed Ni-Cr-O and NiCrBSiFe-WC(Co) powders was investigated through extensive experimentation, and the results are well supported by scanning electron micrographs and 3D topology.

Catalytic reforming of synthetic biogas for hydrogen enrichment over Ni supported on ZnOCeO2 mixed catalyst

Abstract: Catalytic reforming has been considered as an effective technique to produce hydrogen (H2)/syngas from the various feedstocks. The present study focussed on the dry reforming of biogas with Ni (10 wt %) catalysts supported on ceria (CeO2) and Ni catalyst with mixed support of ceria and zinc oxide (ZnO). The synthesized catalysts were characterized by H2-TPR, FESEM, EDX, XRD and BET techniques. The effect of Zn loading (10 and 20 wt %) on the catalytic activity was assessed with respect to various performance parameters. Increased reaction temperature from 650 °C to 900 °C caused a significant increase in reactant conversion and product yield. At 650 °C, CH4 conversion and H2 selectivity achieved were 18.1 and 5.2%, respectively, whereas, at 900 °C, enhanced CH4 conversion (78.5%) and H2 (35.7%) selectivity was achieved with Ni0.1/CeO2 catalyst. Further, it was observed that Ni supported on mixed support exhibited higher reactant conversions when compared to Ni supported with ceria. At 900 °C, Ni0.10/(Zn0.1-Ce0.9) catalyst showed higher CH4 and CO2 conversion of 83.1 and 97.0%, respectively, with 40.3% of H2 enrichment. Carbon deposition rate in mixed support catalyst was observed to be less when compared to single support material after 7 h of continuous dry reforming reaction. Further, in order to reduce carbon deposition on the catalyst bed, dry oxidative reforming was carried out at 650 °C with varying proportions of O2/CH4 ratio which resulted in significantly higher CH4 conversion with low catalyst deposition.

Modeling of Erosion Wear of Sand Water Slurry Flow through Pipe Bend using CFD

Abstract: In the present study, erosion wear of a 90 pipe bend has been investigated using the Computational fluid dynamics code FLUENT. Solid particles were tracked to evaluate the erosion rate along with k-ɛ turbulent model for continuous/fluid phase flow field. Spherical shaped sand particles of size 183 μm and 277 μm of density 2631 kg/m are injected from the inlet surface at velocity ranging from 0.5 to 8 ms at two different concentrations. By considering the interaction between solid-liquid, effect of velocity, particle size and concentration were studied. Erosion wear was increased exponential with velocity, particles size and concentrations. Predicted results with CFD have revealed well in agreement with experimental results. The magnitude and location of maximum erosion wear were more severe in bend rather than the straight pipe.

An experimental study on head loss characteristics of pipe bends for flow of coal–water slurry at high solid concentration:

Abstract: Bending of pipes is a major problem facing the engineers during the construction of a long pipeline for transporting coal–water slurry. However, the use of 90° bends in slurry transportation is restricted because it causes high head loss, and so very high pumping power is required to overcome this resistance. In this context, the present study is carried out to reduce the head loss for the flow of coal–water suspension across 90° pipe bends by varying bend geometry. Rheological experiments were performed to study flow characteristics of coal–water suspension with/without the additive. Coal–water slurry exhibits Newtonian behavior at a solid concentration of 30 wt% and pseudoplastic flow nature at concentration above 30%. Head loss experiments were carried out on a pilot plant test loop for a solid concentration of 30.27–61.56% with flow velocity ranging from 2 to 5 m/s. The r/D ratio for the pipe bend varied within the range of 1.5–2.5. The present study reveals that the head loss across pipe bends increa...

Experimental Design-Based Analysis on Process Parameters for Head Loss in Pipe Bend

Abstract: In the present, the parameters responsible for head loss have been optimized by using Taguchi approach. The head loss characteristics in transportation of slurry are function of various parameters like solid concentration, flow velocity and additive proportion. Present investigation is focused to recognize the most influencing parameter for the head loss in 90° pipe bend. Several influencing parameters of head loss are optimized with the help of the Taguchi method. L16 array is used for experimental design of process parameters. The S/N ratio for head loss is characterized by using smaller-is-better rule. The solid concentration of slurry was varied from 30 to 60% (by weight) for flow velocity range of 2–5 m/s. Series of experiments are performed on pilot plant test loop to obtain head loss in pipe bend. Results obtained from experimental design reveal that flow velocity is found as a dominating parameter as compared to solid concentration and proportion of additive. Probability plot reveals that the experimental data follows the 95% level of confidence.