Recovery hydrogen

Typical Hydrogen Membrane Performance in Refining Applications 

Process Stream Primary Separation Feed Purity (%) Permeate Purity (%) Recovery (%) 

Source From Scott K., Handbook of Industrial Membranes. 2nd ed. Elsevier Science Publishers, Oxford, 1998, 297. 

Overview of Fuel Cells Capacity and Potential Application Areas 

Type of Fuel Cell (FC) Acronym Cell Output Temperature Range (°C) Field of Application Special Features 

Maximum moles of hydrogen produced. While the hydrogen yield represents the overall accomplishment of hydrogen production on the basis of COD removal, a more detailed analysis of hydrogen recovery is needed to understand system performance. For a specific substrate, the number of moles of hydrogen produced, ,a, is 

We can now explore where hydrogen losses occur by calculating the recoveries based on Coulomic efficiency and moles of hydrogen recovered in the cathode chamber. 

Coulombic hydrogen recovery (Coulombic Efficiency). The moles of hydrogen that can recovered based on the measured current, ncE, is calculated as 

We see from eq. 8-9 that ncE is the total moles of electrons recovered in the circuit divided by 2. Also, is the total moles of electrons that could be produced by complete oxidation of the substrate divided by 2. The hydrogen Coulombic recovery, rcE, is therefore equal to the Coulombic efficiency as the value of 2 cancels out. 

Cathodic hydrogen recovery. Now that we know the number of moles of hydrogen that we should recover based on the measured current, we can examine how much of the hydrogen we actually recovered from this current as 

As previously mentioned, the first widespread commercial application of membranes in GS was the separation of hydrogen in the ammonia purge stream, by using Permea Prism T systems. Hydrogen recovery is applicable to several processes, divided into three main categories  

In the ammonia process, the purge stream, almost clean and free of condensable vapours, consists of a mixture of hydrogen, nitrogen, methane and argon, delivered at a high pressure (136bar). It is, thus, the ideal application for the membrane technology, since 

H2/light Ethylene Cryogenic PTMSP PMP Pilot plant 

O2/N2 Air separation Cryogenic Silicon rubber Plant installed 

N2/CH4 Nitrogen Cryogenic Silicon rubber Pilot plant 

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Some large-scale enrichments (adsorbate consisting of >10 20% of feed) examples include hydrogen recovery, methane enrichment, and oxygen enrichment from air. 

When hydrogen recovery is unsafe or otherwise impractical it is vented into the cell room or tank house. The light weight and high diffusion rate of hydrogen and good cell room ventilation have made this an accepted practice. 

Hydrogen Hydrogen recovery was the first large commercial membrane gas separation. Polysulfone fiber membranes became available in 1980 at a time when H9 needs were rising, and these novel membranes qiiickly came to dominate the market. Applications include recovery of H9 from ammonia purge gas, and extraction of H9 from petroleum crackiug streams. Hydrogen once diverted to low-quahty fuel use is now recovered to become ammonia, or is used to desulfurize fuel, etc. H9 is the fast gas. 

Assume that 1 kmol of gas occupies 22.4 m3 at standard temperature and pressure (STP). For stage-cut fractions from 0.1 to 0.9, calculate the purity of hydrogen in the permeate, the membrane area and the fractional hydrogen recovery for a single-stage membrane. 

Figure 10.16 Trade-offs for permeate concentration, membrane area and hydrogen recovery for Example 10.6.

Gas separation through membranes achieved commercialization after the introduction of the Prism process by Monsanto a decade ago. Originated for hydrogen recovery, high area membrane equipment is now used for other gases, notably C02 [1]. Hydrogen, carbon dioxide, and other components are now being removed from mixtures on an industrial scale [2, 3],... 

Buxbaum, R.E., High Flux Metallic Membranes for Hydrogen Recovery and Membrane Reactors, Proceedings of2007 U.S. DOE Hydrogen Annual Merit Review Meeting, Arlington, VA, May 2007. 

Mehra (2) [Named after the inventor] A gas separation process utilizing absorption in a solvent at moderate pressures. Developed by Advanced Extraction Technologies and applied to hydrogen recovery, nitrogen rejection, and recovery of natural gas liquids. 

Metal Hydride Process for Ammonia Purge Gas, The metal hydride process will be illustrated using the case of hydrogen recovery from an ammonia purge gas stream generated during ammonia manufacture. 

Figure 15. Applications map for hydrogen recovery process A, ammonia purge gas B, refinery stream C, coal conversion recycle gas D, ethylene plant cracked gas E, FCC minus gas...

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