Thesis - Oztek_Muzaffer_T_200508_MA

3.4. U-Tube Hydriding Reactor
The U-tube that was used for scaled up experiments was filled with approximately
190 grams of LaNi 5 and then the flow of 2% (v/v) H 2 :He at about 9 atm was fed into it.
The flow out of the reactor was restricted to about 200 mL.min -1 by a pressure relief
valve. The valve maintained the pressure within the reactor, while allowing a slow flow.
The gas chromatogram of multiple injections is given in Figure 35. The single peaks over
the first 20 minutes were helium peaks, represented by empty circles. Hydrogen was not
observed in the effluent because it reacted with LaNi 5 . When LaNi 5 could not absorb any
more H 2 , hydrogen peaks started to show (filled circles). The percent hydrogen values in
the effluent were calculated using peak area ratios of H 2 and He. The breakthrough curve
was plotted as a function of time (Figure 36).
The U-tube reactor successfully removed the hydrogen from the H 2 -He stream
and allowed the passage of He only. The amount of hydrogen retained in the reactor at
the time of saturation was calculated from material balance. The amount of helium
leaving the system was calculated using flowrate and time
V He (mL) = flowrate (mL.min -1 ) x time (min)
which was equal to the amount of He that entered the system. Since the composition of
the entering gas mixture was known, the amount of H 2 entered was calculated using
V Hydrogen = V He x (20/80)
and converted to the amount and then weight percent hydrogen in the LaNi 5 .
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