Hydrogen energy is a crucial carrier for the growth of the energy system and its low-carbon transformation.Using natural gas as a carrier of hydrogen transport and the natural gas pipeline network for transportation i...Hydrogen energy is a crucial carrier for the growth of the energy system and its low-carbon transformation.Using natural gas as a carrier of hydrogen transport and the natural gas pipeline network for transportation is a significant step toward realizing large-scale and long-distance hydrogen transport.Hydrogen-mixed natural gas is mainly separated into hydrogen and natural gas by physical methods at present.High purity of hydrogen recovery,but the recovery rate is low.At the same time,compared with natural gas,liquefied natural gas is more economical and flexible.This study analyzes three typical cryogenic separation processes.The results show that the hydrogen separation efficiency and specific energy consumption increase and the liquefaction rate and energy consumption decrease as the hydrogen ratio increases.The energy consumption and specific energy consumption of C3-MRC are lower than the MRC and the cascade liquefaction processes.Besides,as the pressure increases in the C3-MRC liquefaction process,the liquefaction and hydrogen separation efficiency increase and subsequently drop.Different hydrogen content has the highest hydrogen separation efficiency and liquefaction efficiency under different feed gas pressure conditions.The total exergy losses of the C3-MRC are the least in different hydrogen fractions,which are 37.59%and 21.77%less in the 25%hydrogen fraction,and 37.89%and 21.37%less in the 30%hydrogen fraction.Moreover,the exergy efficiency of C3-MRC are 87.68%and 88.06%when the hydrogen fraction are 25%and 30%,higher than the other two processes,which implies that in 25%and 30%fractions,making it more suitable for separate the hydrogen by the cryogenic separation.展开更多
A detailed investigation of a thermodynamic process in a structured packing distillation column is of great impor- tance in prediction of process efficiency. In order to keep the simplicity of an equilibrium stage mod...A detailed investigation of a thermodynamic process in a structured packing distillation column is of great impor- tance in prediction of process efficiency. In order to keep the simplicity of an equilibrium stage model and the accu- racy of a non-equilibrium stage model, a hybrid model is developed to predict the structured packing column in cryogenic air separation. A general solution process for the equilibrium stage model is developed to solve the set of equations of the hybrid model, in which a separation efficiency function is introduced to obtain the resulting tri-diagonal matrix and its solution by the Thomas algorithm. As an example, the algorithm is applied to analyze an upper column of a cryogenic air separation plant with the capacity of 17000 m3·h-1. Rigorous simulations are conducted using Aspen RATEFRAC module to validate the approach. The temperature and composition distributions are in a good agreement with the two methods. The effects of inlet/outlet position and flow rate on the temperature and composition distributions in the column are analyzed. The results demonstrate that the hybrid model and the solution algorithms are effective in analvzin~ the distillation process for a a cryogenic structured packing column.展开更多
Nonuniform flow distribution along the radial direction usually exists in a Z-flow type radial flow adsorber,which will decrease the utilization of adsorbent and the switching time and may result in operating safety p...Nonuniform flow distribution along the radial direction usually exists in a Z-flow type radial flow adsorber,which will decrease the utilization of adsorbent and the switching time and may result in operating safety problems in cryogenic air separation.In order to improve the uniformity of the flow distribution along the radial direction in the adsorber,a differential equation is derived through pressure drop analysis in the Z-flow type radial adsorber with a cone in the middle of the central pipe.The differential equation determines the ideal cross-sectional radii of the cone along the axis.The result shows that the cross-sectional radius of the cone should gradually decrease from 0.3 m to zero along the axis to ensure that the process air is distributed uniformly in the Z-flow type radial flow adsorber and the shape of the cone is a little convex.The flow distribution without the cone in the central pipe is compared under different bed porosities.It is demonstrated that the proposed differential equation can provide theoretical support for designing Z-flow type radial flow adsorbers.展开更多
基金the Science and Technology Innovation Seedling Project of Sichuan Province,China(No.2021079)the School-Level Key Program of Chengdu Technological University,China(No.210518).
文摘Hydrogen energy is a crucial carrier for the growth of the energy system and its low-carbon transformation.Using natural gas as a carrier of hydrogen transport and the natural gas pipeline network for transportation is a significant step toward realizing large-scale and long-distance hydrogen transport.Hydrogen-mixed natural gas is mainly separated into hydrogen and natural gas by physical methods at present.High purity of hydrogen recovery,but the recovery rate is low.At the same time,compared with natural gas,liquefied natural gas is more economical and flexible.This study analyzes three typical cryogenic separation processes.The results show that the hydrogen separation efficiency and specific energy consumption increase and the liquefaction rate and energy consumption decrease as the hydrogen ratio increases.The energy consumption and specific energy consumption of C3-MRC are lower than the MRC and the cascade liquefaction processes.Besides,as the pressure increases in the C3-MRC liquefaction process,the liquefaction and hydrogen separation efficiency increase and subsequently drop.Different hydrogen content has the highest hydrogen separation efficiency and liquefaction efficiency under different feed gas pressure conditions.The total exergy losses of the C3-MRC are the least in different hydrogen fractions,which are 37.59%and 21.77%less in the 25%hydrogen fraction,and 37.89%and 21.37%less in the 30%hydrogen fraction.Moreover,the exergy efficiency of C3-MRC are 87.68%and 88.06%when the hydrogen fraction are 25%and 30%,higher than the other two processes,which implies that in 25%and 30%fractions,making it more suitable for separate the hydrogen by the cryogenic separation.
基金Supported by the Major State Basic Research Development Program of China(2011CB706501)the National Natural Science Foundation of China(51276157)
文摘A detailed investigation of a thermodynamic process in a structured packing distillation column is of great impor- tance in prediction of process efficiency. In order to keep the simplicity of an equilibrium stage model and the accu- racy of a non-equilibrium stage model, a hybrid model is developed to predict the structured packing column in cryogenic air separation. A general solution process for the equilibrium stage model is developed to solve the set of equations of the hybrid model, in which a separation efficiency function is introduced to obtain the resulting tri-diagonal matrix and its solution by the Thomas algorithm. As an example, the algorithm is applied to analyze an upper column of a cryogenic air separation plant with the capacity of 17000 m3·h-1. Rigorous simulations are conducted using Aspen RATEFRAC module to validate the approach. The temperature and composition distributions are in a good agreement with the two methods. The effects of inlet/outlet position and flow rate on the temperature and composition distributions in the column are analyzed. The results demonstrate that the hybrid model and the solution algorithms are effective in analvzin~ the distillation process for a a cryogenic structured packing column.
基金Supported by the Major State Basic Research Development Program of China（2011CB706501）the National Natural Science Foundation of China（51176164）
文摘Nonuniform flow distribution along the radial direction usually exists in a Z-flow type radial flow adsorber,which will decrease the utilization of adsorbent and the switching time and may result in operating safety problems in cryogenic air separation.In order to improve the uniformity of the flow distribution along the radial direction in the adsorber,a differential equation is derived through pressure drop analysis in the Z-flow type radial adsorber with a cone in the middle of the central pipe.The differential equation determines the ideal cross-sectional radii of the cone along the axis.The result shows that the cross-sectional radius of the cone should gradually decrease from 0.3 m to zero along the axis to ensure that the process air is distributed uniformly in the Z-flow type radial flow adsorber and the shape of the cone is a little convex.The flow distribution without the cone in the central pipe is compared under different bed porosities.It is demonstrated that the proposed differential equation can provide theoretical support for designing Z-flow type radial flow adsorbers.
