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Zhang J.,China University of Petroleum - Beijing | Zhang J.,Beijing Key Laboratory of Process Fluid Filtration and Separation | Xu C.,China University of Petroleum - Beijing | Zhang Y.,China University of Petroleum - Beijing | And 2 more authors.
Journal of Natural Gas Science and Engineering | Year: 2016

Liquefied natural gas (LNG) cryogenic submerged pumps are important transmission devices in LNG terminals and filling stations. In this study, the impeller of a two-stage LNG submerged pump was designed by the quasi-3D hydraulic design method based on the S1 and S2 relative stream surfaces theory. In the design procedure, the finite element method (FEM) with a quadrilateral nine-node element was adopted for the S1 stream surfaces calculation, and the quasi-orthogonal method was used for the average S2 stream surface calculation. The flow field was obtained by the iterative computations of S1 and S2 stream surfaces. Given a reasonable velocity moment distribution along streamlines considered cavitation, the blade drawing was realized by iterating the camber lines and circulation equations on an average S2 stream surface. Moreover, a steady numerical simulation of the designed pump was conducted. The simulation result showed that the head of the designed pump was 260.15 m and the efficiency was 62.82% at the designed flow rate condition. The net positive suction head required (NPSHr) at the conditions with 0.9 Q0, 1.0 Q0 and 1.1 Q0 were, respectively, 1.69 m, 2.54 m and 3.12 m, which met the industrial needs. Furthermore, both the cavitation and hydraulic performance of an impeller designed by the method presented in this study were better than those of an impeller which was designed by the two-dimensional method. © 2015 Elsevier B.V. Source


Yang J.,Taiyuan University of Technology | Sun G.,China University of Petroleum - Beijing | Sun G.,Beijing Key Laboratory of Process Fluid Filtration and Separation | Zhan M.,China University of Petroleum - Beijing | Zhan M.,Beijing Key Laboratory of Process Fluid Filtration and Separation
Powder Technology | Year: 2015

The separation efficiency of cyclones is closely related to the inlet velocity, and the maximum-efficiency inlet velocity (MEIV) maximizes the separation efficiency. In current separation models, particles centrifuged on the wall are considered captured, and their further motions are no longer considered. We propose that particles centrifuged on the wall impact the wall and then rebound. If the energy in these particles is sufficient, they will rebound into the upward gas flow. Within the fast upward gas flow, particles quickly move into the vortex finder and escape from the cyclone. A faster inlet velocity imparts more energy to the particles. Therefore, an excessive inlet velocity causes rebounded particles to escape, decreasing efficiency. The particle motion discussed above is the reason for the MEIV phenomenon, which is different from previous explanations. Newton's law and the hard sphere model were used to describe the particles' motion. Taken together, a new approach to forecast MEIV was established. The effects of various particle characteristics on the MEIV of cyclones, which have not been considered by previous models to forecast the MEIV, are taken into account in this new approach. We observed good consistency between the prediction of the new model and experimental data. © 2015 Elsevier B.V. Source


Zhao H.,China University of Petroleum - Beijing | Zhao H.,Beijing Key Laboratory of Process Fluid Filtration and Separation | Jiang T.,China University of Petroleum - Beijing | Jiang T.,Beijing Key Laboratory of Process Fluid Filtration and Separation | And 2 more authors.
Energy | Year: 2015

The CCHP (combined cooling, heating, and power) system, especially combined with the SOFC (solid oxide fuel cell), has great potential for improving energy utilization efficiency. Therefore an integrated SOFC-CCHP system, fueled by COG (coke oven gas) which contains large amount of hydrogen, has been designed and proposed in this paper. The flue gas exhausted from the HRSG (heat recovery steam generator) is used for heating and the latent heat of water exhausted from the ST (steam turbine) is used for cooling achieved by a single-effect lithium bromide absorption chiller. Based on the corresponding models, the evaluations of the system performance are carried out aided by Aspen Plus process simulator. The calculation results indicate that the electrical efficiency of the SOFC can reach over 60% while the total power efficiency and the overall system efficiency of SOFC-CCHP system are about 70% and 90% respectively. Furthermore, the effect of several operating parameters including fuel flow rate, hydrogen content of COG, fuel utilization factor and operating pressure are investigated and analyzed on the proposed system performance. This research lays a good foundation for the designing of the proposed integrated SOFC-CCHP system, which would be an efficient utilization option of COG. © 2015 Elsevier Ltd. Source


Gu X.,China University of Petroleum - Beijing | Gu X.,Beijing Key Laboratory of Process Fluid Filtration and Separation | Song J.,China University of Petroleum - Beijing | Song J.,Beijing Key Laboratory of Process Fluid Filtration and Separation | Wei Y.,China University of Petroleum - Beijing
Powder Technology | Year: 2016

In order to get further insight into the dynamic property of the vortex, pressure signals at various axial, radial and circumferential positions in a gas-solid cyclone were measured by multi-input dynamic pressure transducer. By adopting probability density function, standard deviation, and power spectral density methods, the characteristics of the pressure signals were analyzed and discussed. Experimental results show that there are two dominant frequencies (about 71 Hz and 179 Hz) of the pressure fluctuation in the gas flow: the former (about 71 Hz) is related to the quasi-forced vortex rotation; the latter (about 179 Hz) is related to the swing of the quasi-forced vortex core. The particle strands motion in the gas-solid flow reduces the dispersion of pressure fluctuation, mitigates the off-axis phenomenon of the core to some extent, and adds a dominant low frequency (0.31 Hz-0.86 Hz) which gets higher with the increase of inlet solids loading. The experimental results can provide insight into the pressure fluctuation in a gas-solid cyclone separator. © 2016 Elsevier B.V. Source


Zhang H.,China University of Petroleum - Beijing | Zhang H.,Beijing Key Laboratory of Process Fluid Filtration and Separation | Li Z.,China University of Petroleum - Beijing | Li Z.,Beijing Key Laboratory of Process Fluid Filtration and Separation | And 2 more authors.
Energy Conversion and Management | Year: 2015

A novel electricity-heating cogeneration system (EHCS) which is equipped with an absorption heat pump (AHP) system to recover waste heat from exhaust steam of the steam turbines in coal-fired thermal power plants is proposed to reduce heating energy consumption and improve the utilization of the fossil fuels in existing CHP (Combined Heat and Power) systems. According to the first and second thermodynamic law, the changes of the performance evaluation indicators are analyzed, and exergy analyses for key components of the system are carried out as well as changes of exergy indexes focusing on 135 MW direct air cooling units before and after modification. Compared with the conventional heating system, the output power increases by about 3.58 MW, gross coal consumption rate and total exergy loss respectively reduces by 11.50 g/kW h and 4.649 MW, while the total thermal and exergy efficiency increases by 1.26% and 1.45% in the EHCS when the heating load is 99,918 kJ at 75% THA condition. Meanwhile, the decrement of total exergy loss and increment of total exergy efficiency increase with the increasing of the heating load. The scheme cannot only bring great economic benefits but also save fossil resources, which has a promising market application potential. © 2015 Elsevier Ltd. All rights reserved. Source

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