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Zhang X.-B.,Zhejiang University | Chen J.-Y.,Zhejiang University | Yao L.,Hangzhou Hangyang Co. | Huang Y.-H.,Shanghai JiaoTong University | And 2 more authors.
Journal of Zhejiang University: Science A | Year: 2014

With the rapid growth in demand for industrial gas in steel and chemical industries, there has been significant emphasis placed on the development of China's large-scale air separation technology. Currently, the maximum capacity of a single unit has been able to attain 120 000 Nm3/h (oxygen), and the specific power consumption of 0.38 kWh/m3. This paper reviews the current state-of-the-art for large-scale cryogenic air separation systems being deployed in China. A brief introduction to the history and establishment of the large-scale cryogenic air separation industry is presented. Taking the present mainstream large-scale air separation unit operating at 60 000 Nm3/h (oxygen) as an example, the technological parameters and features of the involved key equipment, including a molecular sieve adsorber, air compressor unit, plate-fin heat exchanger, turbo-expander and distillation column are described in detail. The developing 80 000-120 000 Nm3/h air separation processes and equipment are also introduced. A summary of the existing problems and future developments of these systems in China are discussed. © Zhejiang University and Springer-Verlag Berlin Heidelberg 2014.

Wang W.,Zhejiang University | Guo J.,Zhejiang University | Zhang S.,Hangzhou Hangyang Co. | Yang J.,Zhejiang University | And 2 more authors.
Computers and Chemical Engineering | Year: 2014

A numerical plate-fin heat exchanger (PFHE) model was proposed to investigate the hydrodynamic characteristics of a full-size PFHE by using the porous media approach. Based on the model, effects of the fluid dynamic viscosity and perforated fins on flow distribution and pressure drop of the PFHE were studied. The results showed that flow distribution of the PFHE was improved by increasing the fluid dynamic viscosity or adding perforated fins in each fin channel, but at the cost of an increased pressure drop. Therefore, the relationship between flow distribution and pressure drop was further analyzed under various Reynolds numbers. Based on the results, a correlation among flow distribution, pressure drop, and Reynolds number was derived. Finally, two strategies, the fin channel-based strategy and the header-based strategy were proposed and numerically verified to improve flow distribution of the PFHE. Our results indicate that the first strategy is better than the latter one. © 2013 Elsevier Ltd.

Deng H.,Zhejiang University of Technology | Zhang S.,Zhejiang University of Technology | Zheng Y.,Hangzhou Hangyang Co.
Paiguan Jixie Gongcheng Xuebao/Journal of Drainage and Irrigation Machinery Engineering | Year: 2012

To establish a basic theory system and design method for a new type of annular U-diaphragm in hydraulic diaphragm pumps, the relation between U-diaphragm deflection and deformation quantity was analyzed by using the nonlinear analysis function in finite element software Ansys. A thin, hollow, double shell U-diaphragm finite element model with geometry and material nonlinear character was established for the annular U-diaphragm used in the prototype of hydraulic diaphragm pump. The deflection of the U-diaphragm model was analyzed under different compression and stretch displacements when the displacements of the supported end were fixed, the displacements of the free supported end were prescribed and the pressure loads were applied on both sides of the U-diaphragm. The computed displacements of deflection were fitted by using differential evolution method where the correct fitting curves were determined by controlling mean square error and correlation coefficient and so on. The U-diaphragm movement was clarified and an empirical relation for the deflection was obtained, eventually a theoretical formula for camber working volume was given. All the results above will provide a theoretical basis for working mechanism and design optimization of an annular U-diaphragm.

Xu Z.,Zhejiang University | Zhao J.,Zhejiang University | Chen X.,Zhejiang University | Shao Z.,Zhejiang University | And 4 more authors.
Separation and Purification Technology | Year: 2011

In this paper, an automatic load change (ALC) system of cryogenic air separation process is developed to automatically and rapidly respond to the changing product demand from customers. In this automatic load change system, a two-layer framework integrated with nonlinear steady-state optimization and nonlinear model predictive control is designed. Nonlinear steady-state optimization based on homotopy- based backtracking method is performed offline to obtain optimal operating points at various load demands. Nonlinear regression models between optimal operating point and load demand are fitted, which can be easily evaluated online to avoid computational effort and convergence problem. To overcome the pronounced nonlinearities caused by load change, an operating trajectory linear parameter varying (LPV) model is identified to represent the nonlinear dynamic behavior of air separation process. A nonlinear model predictive control (MPC) based on LPV model is designed to drive air separation process rapidly to the optimal operating point of target load demand. Under this framework, material and energy balances of air separation process is actively established during the load change, and load transition time can be shortened. Industrial application results show that oxygen release ratio and unit electric consumption of air separation process are reduced by the implementation of ALC system. © 2011 Elsevier B.V. All rights reserved.

Liu J.,Zhejiang University | Zhang S.,Zhejiang University | Zhou Z.,Hangzhou Hangyang Co.
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2015

The effect of fluid flow and heat transfer caused by fins in plate-fin heat exchanger is investigated, and then a new kind of fins, called shark gill fin, is proposed. The main functions of this kind of fins include enlarging fluid turbulence effect, changing flow direction in the same layer of fins, promoting fluid flow among channels, decreasing fluid temperature difference in the same cross-section and finally promoting heat exchange efficiency. The temperature, velocity, pressure and turbulence field under twelve conditions are analyzed by changing cocking-up structure and opening size in shark gill fin and finally, the distribution of fluid flow, temperature, dynamic pressure and turbulent intensity under steady state conditions are achieved. It can be concluded that when the opening size is 1 mm, the fluid velocity difference can reach by 47.38%, the temperature difference can reach by 0.7 ℃/m, the turbulent intensity difference can reach by 0.816%. When cocking-up structure is 10°, the fluid turbulent intensity can reach by 3.162%, the temperature difference can reach by 1 ℃/m. The results demonstrate that, in view of fluid flow, the effect of opening size is more important than cocking-up degree while, in view of temperature field, the opening size is less important than the cocking-up degree, besides, the cocking-up degree has less effect on fluid velocity and dynamic pressure. ©, 2015, Journal of Mechanical Engineering. All right reserved.

Shi P.,Zhejiang University | Wang Q.,Hangzhou Hangyang Co. | Xu Y.,Zhejiang University | Luo W.,Zhejiang University
Materials Letters | Year: 2011

Corrosion behavior of copper bulk with grain size of 48 nm prepared by inert gas condensation and in situ warm compress (IGCWC) technique was investigated in 0.3 wt.% ammonia solution. The nanocrystalline (NC) Cu sample displayed an active-passive-transpassive behavior with the formation of duplex passive films but without stable passive regions in potentiodynamic polarization process. NC Cu exhibited slightly inferior corrosion resistance when compared with coarse-grained (CG) Cu. It could be explained by both the higher grain boundary density that could accelerate corrosion reactions and the loose passive film formed on the surface of NC Cu that couldn't provide effective protection. © 2010 Elsevier B.V. All rights reserved.

Liu J.,Zhejiang University | Zhang S.,Zhejiang University | Zhou Z.,Hangzhou Hangyang Co.
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2014

The improved structure of fluid channel and its influence on heat exchange of plate-fin heat exchanger (PFHE) in super large air separation equipment are investigated. A new kind of channel structure is proposed in which fluid flow is changed in M-shape. Using this new channel, flow distance in exchanger can be extended, turbulent performance can be increased and finally the heat exchange efficiency can be enhanced. The corresponding relationship between turning positions and fluid distribution including fluid velocity, dynamic pressure and turbulent performance are analyzed. The fluid flow both in traditional channels and the improved channels are investigated using commercial software, Fluent. It can be found that fluid turbulent performance can be improved significantly in improved channels. In compare with the traditional channels, the heat exchange efficiency of plate-fin heat exchanger with improved channels can be enhanced by enlarging internal turbulent flow. © 2014 Journal of Mechanical Engineering

Luo W.,Zhejiang University | Xu Y.,Zhejiang University | Wang Q.,Hangzhou Hangyang Co. | Shi P.,Zhejiang University | Yan M.,Zhejiang University
Corrosion Science | Year: 2010

Effect of grain size on corrosion of bulk nanocrystalline copper was investigated using potentiodynamic polarization measurements in 0.1. M NaOH solution. Bulk nanocrystalline copper was prepared by inert gas condensation and in situ warm compress (IGCWC) method. The grain sizes of all bulk nanocrystalline samples were determined to be 48, 68 and 92. nm using X-ray diffraction (XRD). Results showed that bulk coppers displayed an active-passive-transpassive behaviour with duplex passive films. From polycrystalline to nanocrystalline, grain size variation showed little effect on the overall corrosion resistance of copper samples. © 2010 Elsevier Ltd.

Chen G.-Z.,Hangzhou Hangyang Co. | Lin X.-F.,Hangzhou Hangyang Co.
Huaxue Gongcheng/Chemical Engineering (China) | Year: 2010

The conversion of packing hydrodynamic characteristics of air-water system from normal conditions to air separation conditions is the key to the design of packed columns in air separation, for it is hard to obtain hydrodynamic data under the condition of -200°C. The computing method of the Bain-Hougen formula and the SRP (II) model, combining with the Spiegel's liquid holdup can educe the flooding point and the pressure drop to predict the hydrodynamics of the packing. The experimental result at normal condition of 750Y metal packing shows that this method can well predict the hydrodynamics of the packing. The forecast of the flooding point and the pressure drop in air separation shows that the design of air separation column based on hydrodynamic data under normal conditions is a little conservative.

Yuan S.,Hangzhou Hangyang Co. | Lou P.,Hangzhou Hangyang Co. | Lu J.,Hangzhou Hangyang Co.
Paiguan Jixie Gongcheng Xuebao/Journal of Drainage and Irrigation Machinery Engineering | Year: 2015

The structural characteristics of a V-shaped throttling orifice are analyzed to evaluate its throttle performance. In doing so, four performance indices are proposed, namely the slope of equivalent hydraulic diameter, dV2, ratio of equivalent throttling section areas, k, cavitation numbers, σ2A1in and σ2A1out at the smallest throttling section A2A. Homogeneous design is introduced into the structural design of V-shaped throttling orifice, and then the values of four evaluation indices of 16 design cases are calculated. Entropy analysis is applied into the study on throttle performance of these orifices, and then the orifice structure is optimized to achieve the best throttle performance. Compared with the initial structure of the orifice, the optimized one has an improved throttle performance. ©, 2015, Editorial Department of Journal of Drainage and Irrigation Machinery Engineering. All right reserved.

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