Hydrogen recovery factor

Using the membrane performance listed in Table 7.2, the required membrane surface areas for the two modules have been calculated for the OA scheme, adopting a Hydrogen Recovery Factor (HRF) of 70%. The effect of inlet pressure and H2 permeance on the membrane smface area is reported in Fig. 7.6 for the first and second modules. The membrane surface area required to achieve the fixed HRF under the conditions dictated by the heat and material balance was calculated using a one-dimensional, steady-state model assuming a steam sweeping ratio of 50%. 

Finally, when a membrane reactor was employed in open architecture configuration along with a catalyst effectiveness factor of 0.6, the hydrogen recovery factor was evaluated as a function of the membrane permeation surface. The results are shown in Fig. 11.6. 

Ihe hydrogen recovery factor (HRF) is defined as the mole ratio of permeated Hj to Hj contained in the input strearrr. fit the case of tttetrtbrane reactors, the H2 producible inside of the module also has to be accounted far. Iherefore, for a water gas shift membrane reactor, HRF is defined as the mole ratio of permeated H2 to H2 + CO in the errtering syngas. 

Figure 13.7 Hydrogen partial pressure as a function of nondimensional membrane area in membrane module with sweep gas for two different hydrogen recovery factors (HRF).

CO conversion as a function of hydrogen recovery factor (HRF) in WGS tests with a Pd membrane reactor comparison with thermodynamic (TD) equilibrium values. (After Pinacci et ai, 2010.)... 

Performance of the membrane reactor will be evaluated in terms of methane conversion ( ch4 )> permeation ratio (PR) and hydrogen recovery factor (HRF), which are defined as follows ... 

Because of the considerable uncertainties in all the assumptions made, this projected hydrogen cost should not be rigorously compared with the cost projections we have made for the other processes discussed in this paper. Moreover, we have not reworked Knoche and Funk s economics to conform with the guidelines of Table 1. (The assumptions they made were an 80% stream factor, utility financing, 12 % capital recovery factor, and mid-1976 dollars.)... 

The total cost of electrolytic hydrogen from currently available technology is summarized in Table G-6. This table assumes a 14 percent capital cost-recovery factor, and presents the total cost (variable, capital, and O M) associated with the assumed fueling facility. The delivered cost of grid electricity is assumed at 7 cents/kWh. Total costs are in the range of 6.50/kg. 

The cost of hydrogen was estimated by considering the capital costs, capital recovery factor, the operating expenses of the refueling station, the cost of utilities (fuel and electricity), and the cost of catalysts. The natural gas cost was assumed to be 5/ GJ on a higher heating value (HHV) basis, and the electricity cost was assumed to be 70/kWhr. The efficiency of the system (75% on a LHV basis) was used to determine the required amount of natural gas. A capacity factor of 90% for plant utilization was used. The capital recovery factor was determined as 13.1%, assuming 10% interest rate over 15 years. 

Membrane modules are arranged in parallel banks to achieve required capacity. Because economy of scale is not a factor they are used primarily for small- to medium-capacity hydrogen recovery from refinery and petrochemical offgases. 

Within the Production section, there are hyperlinks to detailed analyses of the six hydrogen production options included in H2Sim. Figure 9.3 illustrates the natural gas reformation option. This screen also illustrates the default model results. Key assumptions on each production page include capital, operation and maintenance, and fuel costs, thermal efficiency of the process, interest and discount rates, construction time, plant life, and capacity factor. While some of the assumptions are specific to that production option, changes to assumed interest or discount rates apply to the entire model. Any shaded boxes, such as capital recovery factor, cannot be changed by the user, but will change as other variables (in this case discount rate) do. With the exception of... 

The reduction completion is controlled through the titration of the basic solution of the trap after the reduction this leads to the determination of a HCl recovery factor nHci(i)/nHci(2) where nHci(i) is the experimental amount of trapped hydrogen chloride and iihci(2) the calculated amount. For the first set of catalysts, a recovery factor of about 0.5 was obtained, meaning that a part of chloride was not trapped or remained onto the catalyst surface the second assumption is in agreement with the detected presence of excess chloride by EDS measurements (vide infra). For the second set of catalysts, the hydrogen flow rate was increased from 20 to 40 mL.min, thus leading to a recovery factor of 0.92. 

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