High efficient separation of H2/CH4 using ZIF-8/glycol-water slurry: Process modelling and multi-objective optimization

Hydrogen (H₂) is expected to play a vital role in future global energy system. The efficient and low-energy consumption process for H₂/CH₄ separation from hydrogen rich industrial off-gas is still a key challenge. The absorption-adsorption process for H₂/CH₄ separation using ZIF-8/glycol-water slurry is a promising alternative technique due to its high separation efficiency, mild operation conditions and continuous operation mode. We proposed two process configurations: a decompression desorption process A to obtain 99.5 mol% H₂; and a process B combined with decompression and H₂ stripping desorption to attain 99.99 mol% H₂. The detailed process modelling and multiple objective optimizations for two processes are conducted to determine optimal operation conditions, stream characteristics, and unit energy requirements. Results show that the H₂ recovery ratio and total unit energy consumption reaches 99.70% and 0.3876 kW·h/Nm³ for Process A; 99.47% and 0.4608 kW·h/Nm³ for Process B, respectively. It indicates the novel process can simultaneously achieve high purity and high H₂ recovery with low energy consumption.     

Physical aging,high temperature and water vapor permeation studies of UV-rearranged PIM-1 membranes for advanced hydrogen purification and production

Ultraviolet (UV)-rearranged PIM-1 membranes have been shown to exhibit superior gas separation performance for H₂/CO₂ separation. The long-term aging studies of up to 100 days were investigated and revealed that the UV-rearranged PIM-1 membranes are much more stable than the original PIM-1 membrane. By positron annihilation lifetime (PAL) analyses, a constant decrease of o-Ps lifetime during physical aging of all membranes was observed, while o-Ps intensity changed sparingly. Compared to pure gas tests, the UV-irradiated PIM-1 membrane shows considerably enhanced separation performance in mixed gas tests with and without CO under high temperatures. Although the UV-rearranged PIM-1 membranes reveal deteriorating gas separation performance under humid feed conditions due to the effect of water vapor induced plasticization, the overall gas separation performance still outperforms most literature data. The successful validation of the separation performance for the UV-rearranged PIM-1 membranes under similar industrial testing conditions may possibly suggest the great potential of this type of membrane for the purification and production of industrial hydrogen.     

CO2-selective membranes for hydrogen purification and the effect of carbon monoxide (CO) on its gas separation performance

Industrial hydrogen production may prefer CO₂-selective membranes because high-pressure H₂ can therefore be produced without additional recompression. In this study, high performance CO₂-selective membranes are fabricated by modifying a polymer–silica hybrid matrix (PSHM) with a low molecular weight poly(ethylene glycol) dimethyl ether (PEGDME). The liquid state of PEGDME and its unique end groups eliminate the crystallization tendency of poly(ethylene glycol) (PEG). The methyl end groups in PEGDME hinder hydrogen bonding between the polymer chains and significantly enhance the gas diffusivity. In pure gas tests, the membrane containing 50 wt% additive shows CO₂ gas permeability and CO₂/H₂ selectivity of 1637 Barrers and 13 at 35 °C, respectively. In order to explore the effect of real industrial conditions, the gas separation performance of the newly developed membranes has been studied extensively using binary (CO₂/H₂) and ternary gas mixtures (CO₂/H₂/carbon monoxide (CO)). Compared to pure gas performance, the second component (H₂) in the binary mixed gas test reduces the CO₂ permeability. The presence of CO in the feed gas stream decreases both CO₂ and H₂ permeability as well as CO₂/H₂ selectivity as it reduces the concentration of CO₂ molecules in the polymer matrix. The mixed gas results affirm the promising applications of the newly developed membranes for H₂ purification.     

Evaluation of energy integration aspects for IGCC-based hydrogen and electricity co-production with carbon capture and storage

Integrated Gasification Combined Cycle (IGCC) is a power generation technology in which the solid feedstock is partially oxidized with oxygen and steam to produce syngas. In a conventional IGCC design without carbon capture, the syngas is purified for dust and hydrogen sulphide removal and then sent to a Combined Cycle Gas Turbine (CCGT) for power generation. Carbon capture technologies are expected to play an important role in the coming decades for reducing the greenhouse gas emissions. In a modified IGCC design for carbon capture, the syngas is catalytically shifted to maximize the hydrogen level and to concentrate the carbon species in the form of carbon dioxide which can be later captured in a pre-combustion arrangement. After carbon dioxide capture, the hydrogen-rich syngas can be either purified in a Pressure Swing Adsorption (PSA) unit and exported to the external customers (e.g., chemical industry, PEM fuel cells) or used in a CCGT for power generation.     

高炉余能余热驱动的内可逆闭式布雷顿热电冷联产装置火用经济性能分析

用有限时间热力学理论研究恒温热源条件下由一个内可逆闭式布雷顿热机循环和一个内可逆四热源吸收式制冷循环组成的高炉余能余热驱动的热电冷联产装置的火用经济性能,导出热电冷联产装置的利润率和火用效率与压气机压比的关系。利用数值计算,分析热电比和吸收式制冷循环总放热量在吸收器和冷凝器之间的分配率对利润率与火用效率关系的影响,并研究联产装置各种参数对最大利润率及相应火用效率特性的影响。