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Nanjing, China

Sun J.,China University of Petroleum - Beijing | Feng X.,China University of Petroleum - Beijing | Wang Y.,China University of Petroleum - Beijing | Deng C.,China University of Petroleum - Beijing | Chu K.H.,Honeychem
Energy | Year: 2014

Centrifugal pumps are widely used in cooling water systems to transport cooling water to its users. They are installed in the header line of the feed pipe, constituting a main pump network. The pressure head of the main pumps must be large enough to satisfy the pressure heads of all coolers. The pressure drop of parallel branch pipes must be balanced by reducing the opening of valves for some coolers, incurring an energy penalty on some pumps. To attain energy savings, this paper proposes an auxiliary pump network whereby auxiliary pumps are installed in parallel branch pipes. A superstructure-based mathematical model is developed to optimize the total cost of the main and auxiliary pump networks. The optimal number of auxiliary pumps and their installation locations are determined by solving the model with a simulated annealing algorithm. The effectiveness of the model is tested by a case study based on the cooling water network of a refinery. © 2014 Elsevier Ltd. Source


Yang M.,China University of Technology | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Honeychem | Liu G.,China University of Technology
Energy | Year: 2014

Introducing purification devices into hydrogen systems can enhance the extent of hydrogen reuse. However, the economic performance of a purification device depends on its appropriate placement within a hydrogen system. Based on some established graphical methods, this paper explores the influences of the feed concentration on the purification proces. s. A simple and systematic graphical method is proposed for identifying the OPP (optimal purification process) by extending the well-known pinch technology method. The proposed method can determine the OPP with the minimum feed flow rate and minimum tail gas flow rate under the condition of maximizing the HUS (hydrogen utility savings). The corresponding feed streams of the OPP also can be identified easily in the purification polygon. Furthermore, the conception of minimum separation work is used to compare different purification processes. A realistic case study is used to illustrate the applicability of the proposed method. Three different scenarios are analyzed and the results show that notable reductions in the minimum separation work consumption can be achieved (22%, 34% and 16% for the three scenarios). © 2014 Elsevier Ltd. Source


Chu K.H.,Honeychem
Journal of Water Process Engineering | Year: 2014

Adsorption is an important process for arsenic removal from drinking water supplies. Fixed bed column processes are the preferred mode of operation owing to their simplicity and proven performance. Mathematical models can facilitate the design and optimization of fixed bed adsorbers. For systems exhibiting linear isotherm behavior over the relevant concentration range, their performance can be predicted using models that are amenable to analytical solutions. The predictive utility of an asymptotic solution of the homogeneous surface diffusion model (HSDM) and an approximate solution of a linear driving force model (LDFM) under linear isotherm approximation was evaluated in this study. A previously published pilot test on arsenic breakthrough in a fixed bed adsorber of polymer-supported nanoparticles was modeled. Model parameters were estimated on the basis of some easily determined batch measurements. The pilot test yielded 27,000 bed volumes at 10. μg/L arsenic. The two analytical solutions predicted 24,200 and 27,100 bed volumes. Despite the simplicity of the HSDM and LDFM solutions, their predictions agreed well with the experimental data. These analytical solutions are very straightforward, easy to apply, and provide acceptable modeling power. © 2014 Elsevier Ltd. Source


Yang M.,China University of Technology | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Honeychem | Liu G.,China University of Technology
Industrial and Engineering Chemistry Research | Year: 2014

Introducing purification devices into hydrogen systems can enhance the extent of hydrogen reuse. The economic performance of a purification device depends on its appropriate placement within a hydrogen system. This work presents an improved version of a previously published graphical method for integrating purification processes in hydrogen systems. A mathematical method is deduced for calculating the maximum hydrogen utility savings potential of a hydrogen system with purification reuse. The improved graphical method is able to handle the constraints of concentration and flow rate of a purification process when targeting the maximum hydrogen utility savings. The proposed method can be used for analyzing purification processes with any feed concentration. The graphical method is tested on two case studies. © 2014 American Chemical Society. Source


He C.,China University of Petroleum - Beijing | Feng X.,China University of Petroleum - Beijing | Chu K.H.,Honeychem | Li A.,Liaoning Datang International Fuxin Coal To SNG Co. | And 2 more authors.
Chinese Journal of Chemical Engineering | Year: 2014

We have developed a process model to simulate the behavior of an industrial-scale pressurized Lurgi fixed-bed coal gasifier using Aspen Plus and General Algebraic Modeling System (GAMS). Reaction characteristics in the fixed-bed gasifier comprising four sequential reaction zones - drying, pyrolysis, combustion and gasification are respectively modeled. A non-linear programming (NLP) model is developed for the pyrolysis zone to estimate the products composition which includes char, coal gases and distillable liquids. A four-stage model with restricted equilibrium temperature is used to study the thermodynamic equilibrium characteristics and calculate the composition of syngas in the combustion and gasification zones. The thermodynamic analysis shows that the exergetic efficiency of the fixed-bed gasifier is mainly determined by the oxygen/coal ratio. The exergetic efficiency of the process will reach an optimum value of 78.3% when the oxygen/coal and steam/coal mass ratios are 0.14 and 0.80, respectively. © 2014 Chemical Industry and Engineering Society of China (CIESC) and Chemical Industry Press (CIP). Source

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