Air preoxidation and Fe-catalyzed cooperative effect for preparation of high-performance coal-based granular activated carbon: Enhancing low-concentration CH4 recovery and utilization

Integrated vacuum pressure swing adsorption and Rectisol process for CO2 capture from underground coal gasification syngas

An improved vacuum pressure swing adsorption process with the simulated moving bed operation mode for CH4/N2 separation to produce high-purity methane

Methane recovery from low-grade unconventional natural gas by the integrated mode of the conventional/improved vacuum pressure swing adsorption processes

Vacuum pressure swing adsorption process with carbon molecular sieve for CO2 separation from biogas

ZSM-5 zeolites with a high Si/Al molar ratio are commercially available sorbents with a high specific surface area, well-developed microporous structure, good hydrophobic properties, and water resistance, which would be safer and more efficient sorbents to deal with the recovery of flammable methane gas from coalbed gas, shale gas, etc. In this article, ZSM-5 zeolites are used as sorbents, matched with the multicolumn vacuum pressure swing adsorption (VPSA) process with the simulated moving bed (SMB) operation mode to separate CH4/N2 for high-purity methane production. Based on the process design, five-column, six-column, and seven-column VPSA experimental apparatuses have been set up in the laboratory, which are operated with the SMB mode at a fully automatic control platform. According to experimental results, it is found that the switching time of inlet and outlet stream ports can be shortened, and the column number may be also reduced in the proposed VPSA process with ZSM-5 zeolites as sorbents. High-purity methane product gas (99% CH4) can be obtained continuously from 30–60% CH4 feed gas with an above 90% methane recovery efficiency and 1.06–1.64 mol/kg/h methane productivity at 250 kPa and ambient temperature by the developed VPSA process with ZSM-5 zeolites. Compared with our previous work using activated carbon sorbents, the separation performance of CH4/N2 by ZSM-5 zeolites is improved obviously, having a broad prospect for the recovery of low-grade methane gas from unconventional natural gases.

Optimization and analysis of a VPSA process for N2/CH4 separation

Carbon dioxide removal from flue gas with a two-stage vacuum pressure swing adsorption (VPSA) process, which uses activated carbon (AC) beads as the adsorbent, was investigated both theoretically and experimentally. First, single-column VPSA experiments were studied for CO2/N2 separation with high CO2 feed concentration. Then, a two-stage VPSA process composed two columns for each stage was designed, and the effects of different parameters were investigated. The first-stage VPSA unit operates with a four-step Skarstrom cycle, which includes feed pressurization, adsorption, blowdown, and counter-current purge with N2. For the second-stage VPSA process, a cycle with feed pressurization, adsorption, pressure equalization, blowdown and pressure equalization was employed. With the proposed two-stage VPSA process, a CO2 purity of 95.3% was obtained with 74.4% recovery. The total specific power consumption of the two-stage VPSA process is 723.6 kJ/kg-CO2, while the unit productivity is 0.85 mol-CO2/kg·h.

Separation of carbon dioxide in flue gases from the combustion equipment is one of the most serious concerns for industries and especially for the power plants which are the main producers of this pollutant gas. From the various separation methods, vacuum pressure swing adsorption (VPSA) process is attracted interest due to its lower energy consumption and high efficiency. A VPSA process was studied for the separation of a mixture of CO2/N2 (80% N2 and 20% CO2). Experiments were performed in an eight-step, four-bed setup using zeolite 13X and carbon molecular sieve (CMS) as adsorbents. Experimental measurements by the bench-scale system have been obtained in a pressure range of 2.7–4.7 bar, cycle times of 360–600 s, the product flow rate of 1–3 (lit/min), and temperature 30 °C. The effects of pressure, cycle time, and product flow rate were investigated. With using 560 s for a cycle time at 3.7 bar, the maximum purity of 97.6% was obtained for zeolite 13X adsorbent.

Energy and productivity efficient vacuum pressure swing adsorption process to separate CO2 from CO2/N2 mixture using Mg-MOF-74: A CFD simulation

A layered-bed vacuum pressure swing adsorption (VPSA) process with a hybrid packing of Cu(I)AC and Cu(I)Y adsorbents was developed to recover CO from a low-concentration syngas mixture (2.4%CH4–32.3%CO–1.0%CO2–46.0%H2–18.3%N2). Prior to performing a sequential separation VPSA process design, the statical adsorption equilibrium isotherms of pure CH4, CO, CO2, H2, and N2 on two dissimilar improved copper-supported adsorbents of Cu(I)AC and Cu(I)Y were first determined under four different temperature values (293.15, 303.15, 313.15, and 323.15 K) with pressures up to 500 kPa. The experimental adsorption equilibrium data of the pure component were then proved to be well fitted by a Langmuir isotherm model. Further, multicomponent breakthrough curves were separately measured by experiments and simulations with a fixed-bed adsorption mathematical model to obtain a successful prediction for multicomponent adsorption dynamics and equilibrium. On the basis of these, a pilot-scale multibed VPSA simulation work with...

A comparative study of multi-objective optimization with ANN-based VPSA model for CO2 capture from dry flue gas

The effects of a poorly packed bed on the pressure vacuum swing adsorption (PVSA) process were in- vestigated experimentally and theoretically by a five-step two-bed PVSA system. At first, the adsorption dynamics of a zeolite LiX bed for air separation (78 mol% N2, 21 mol% O2 and 1 mol% Ar) was studied at various adsorption pressures and flow rates. In breakthrough results, the effect of adsorption pressure on variations in bed temperature was greater than that of the feed flow rate. A combined roll-up of Ar and O2 by N2 propagation was observed and the roll-up plateau reached about 4 mol%. The fluid dynamic behavior of the poorly packed bed was simulated at each step in the PVSA process. The pressure and velocity profiles in the non-isobaric steps were clearly different from those of a normally packed bed. The two-bed PVSA process using one poorly packed bed with additional 1% void volume in feed end of bed could produce a purity of 92.3 mol% O2 from air, which was almost 1% purity lower than the PVSA with normal two beds. Even small asymmetry between beds, due to poor bed packing, could greatly reduce the product purity in the PVSA process.

Design and experiment of high-productivity two-stage vacuum pressure swing adsorption process for carbon capturing from dry flue gas

Hydrogen is a vital resource in the fight against climate change, and it has the potential to revolutionize the energy sector. Our research focused on optimizing the production of high-purity hydrogen using coke oven gas (COG), a valuable hydrogen source in the steel industry. By leveraging advanced artificial neural networks (ANNs), we can predict the performance and exergy efficiency of a 6-bed 12-step vacuum pressure swing adsorption (VPSA) process accurately and efficiently. The Pareto fronts were addressed by combining the evolutionary algorithm with ANNs, and the effects of operating parameters were discussed in detail. Importantly, we found that our VPSA process can achieve a hydrogen purity of 99.99% with 45.2% exergy efficiency. We also demonstrated that using ANNs can significantly enhance VPSA process optimization, making it a valuable tool for extracting high-purity hydrogen from COG.

Vacuum pressure swing adsorption for producing fuel cell grade hydrogen from IGCC