Browsing by Author "Nordio, Maria"
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Item Comparison between carbon molecular sieve and Pd-Ag membranes in H2-CH4 separation at high pressure(2020-10-30) Nordio, Maria; Melendez, Jon; van Sint Annaland, Martin; Pacheco Tanaka, D. Alfredo; Llosa Tanco, Margot; Gallucci, Fausto; Tecnalia Research & Innovation; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSFrom a permeability and selectivity perspective, supported thin-film Pd–Ag membranes are the best candidates for high-purity hydrogen recovery for methane-hydrogen mixtures from the natural gas grid. However, the high hydrogen flux also results in induced bulk-to-membrane mass transfer limitations (concentration polarization) especially when working at low hydrogen concentration and high pressure, which further reduces the hydrogen permeance in the presence of mixtures. Additionally, Pd is a precious metal and its price is lately increasing dramatically. The use of inexpensive CMSM could become a promising alternative. In this manuscript, a detailed comparison between these two membrane technologies, operating under the same working pressure and mixtures, is presented. First, the permeation properties of CMSM and Pd–Ag membranes are compared in terms of permeance and purity, and subsequently, making use of this experimental investigation, an economic evaluation including capital and variable costs has been performed for a separation system to recover 25 kg/day of hydrogen from a methane-hydrogen mixture. To widen the perspective, also a sensitivity analysis by changing the pressure difference, membrane lifetime, membrane support cost and cost of Pd/Ag membrane recovery has been considered. The results show that at high pressure the use of CMSM is to more economic than the Pd-based membranes at the same recovery and similar purity.Item Effect of sweep gas on hydrogen permeation of supported Pd membranes: Experimental and modeling(2019-02-08) Nordio, Maria; Soresi, Serena; Manzolini, Giampaolo; Melendez, Jon; Van Sint Annaland, Martin; Pacheco Tanaka, D. Alfredo; Gallucci, Fausto; Tecnalia Research & Innovation; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSMembrane reactor processes are being increasingly proposed as an attractive solution for pure hydrogen production due to the possibility to integrate production and separation inside a single reactor vessel. High hydrogen purity can be obtained through dense metallic membranes, especially palladium and its alloys, which are highly selective to hydrogen. The use of thin membranes seems to be a good industrial solution in order to increase the hydrogen flux while reducing the cost of materials. Typically, the diffusion through the membrane layer is the rate-limiting step and the hydrogen permeation through the membrane can be described by the Sieverts’ law but, when the membrane becomes thinner, the diffusion through the membrane bulk becomes less determinant and other mass transfer limitations might limit the permeation rate. Another way to increase the hydrogen flux at a given feed pressure, is to increase the driving force of the process by feeding a sweep gas in the permeate side. This effect can however be significantly reduced if mass transfer limitations in the permeate side exist. The aim of this work is to study the mass transfer limitation that occurs in the permeate side in presence of sweep gas. A complete model for the hydrogen permeation through Pd–Ag membranes has been developed, adding the effects of concentration polarization in retentate and permeate side and the presence of the porous support using the dusty gas model equation, which combines Knudsen diffusion, viscous flow and binary diffusion. By studying the influence of the sweep gas it has been observed that the reduction of the driving force is due to the stagnant sweep gas in the support pores while the concentration polarization in the permeate is negligible.Item Techno-economic evaluation on a hybrid technology for low hydrogen concentration separation and purification from natural gas grid(2021-07-01) Nordio, Maria; Wassie, Solomon Assefa; Van Sint Annaland, Martin; Pacheco Tanaka, D. Alfredo; Viviente Sole, José Luis; Gallucci, Fausto; Tecnalia Research & Innovation; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSHydrogen can be stored and distributed by injecting into existing natural grids, then, at the user site separated and used in different applications. The conventional technology for hydrogen separation is pressure swing adsorption (PSA). The recent NREL study showed the extraction cost for separating hydrogen from a 10% H2 stream with a recovery of 80% is around 3.3–8.3 US$/kg. In this document, new system configurations for low hydrogen concentration separation from the natural gas grid by combining novel membrane-based hybrid technologies will be described in detail. The focus of the manuscript will be on the description of different configurations for the direct hydrogen separation, which comprises a membrane module, a vacuum pump and an electrochemical hydrogen compressor. These technological combinations bring substantial synergy effect of one-another while improving the total hydrogen recovery, purity and total cost of hydrogen. Simulation has been carried out for 17 different configurations; according to the results, a configuration of two-stage membrane modules (in series) with a vacuum pump and an electrochemical hydrogen compressor (EHC) shows highest hydrogen purity (99.9997%) for 25 kg/day of hydrogen production for low-pressure grid. However, this configuration shows a higher electric consumption (configuration B) due to the additional mechanical compressor between the two-stage membrane modules and the EHC. Whereas, when the compressor is excluded, and a double skin Pd membrane (PdDS) module is used in a single-stage while connected to a vacuum pump (configuration A5), the hydrogen purity (99.92%) slightly decreases yet the power consumption considerably improves (1.53 times lower). Besides to these two complementary configurations, the combination of a single membrane module, a vacuum pump and the electrochemical compressor has been also carried out (configuration A) and results show that relatively higher purity can be achieved. Based on four master configurations, this document presents a different novel hybrid system by integrating two to three technologies for hydrogen purification combined in a way that enhances the strengths of each of them.