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using the Ergun equation for the case of a packed bed. The simulator mimics the operation of an actual VSA process in that control valves regulate the flows to/from a bed according to desired end-of-step conditions (eg. pressure, purity). It is important that an adequate number of finite volumes are used to calculate the breakthrough fronts to avoid numerical dispersion. The simulations conducted here were run with at least five nodes within the mass transfer zone and an axial discretisation level of 30 nodes (corresponding to a node spacing of 0.01 m), which was found to be adequate to resolve spatial profiles within the bed. The experimentally recorded adsorption isotherms for CO2 and N2 over a range of temperatures were fit to a Dual-Site Langmuir isotherm. The fitted parameters were calculated according to the following equations: n m1biPi m2diPi Eq.(1) Eq.(2) i Q Q b b exp 1i ;d d exp 2i i 0i RT i 0i RT 1 biPi bjPj 1 diPi djPj A three-step VSA cycle of adsorption/desorption/re-pressurization was considered for evaluating system performance (Figure 1). The initial and boundary conditions depend on the VSA cycle configuration. In our isothermal simulations, the boundary conditions for all the steps were based on flow through a valve according to the valve equation. In addition, three target pressures were maintained at cyclic steady state (CCS) conditions and since the valve settings were not known prior to cycle run, a form of the PID algorithm (control loop) was also used to update boundary conditions (valve coefficients) from cycle to cycle to ensure that the end of step bed pressures and product purity from the model achieves the required set points. In the first step, feed gas containing 10 % CO2/N2 at different flow rates: 0.2, 0.5 and 1 litre/minute at 300 K and 1.2 bar pressure enters the bottom of the bed. The CO2 front propagates through the bed and the nitrogen exits to the atmosphere through the top of the bed. 118PDF Image | Structured Zeolite Adsorbents for PSA Applications
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CO2 Organic Rankine Cycle Experimenter Platform The supercritical CO2 phase change system is both a heat pump and organic rankine cycle which can be used for those purposes and as a supercritical extractor for advanced subcritical and supercritical extraction technology. Uses include producing nanoparticles, precious metal CO2 extraction, lithium battery recycling, and other applications... More Info
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