Sieverts Law Hydrogen Leakage through a Reactor Wall

Illustration 3.4 Sievert s Law Hydrogen Leakage through a Reactor Wall 

As a consequence of tiris process, the equilibrium solid-phase concentration C is no longer related linearly to gas pressure but depends instead on the square root of p. The linear relation (Equation 3.7), C = Sp, must conse-quentiy be replaced by the expression 

Expression 3.11b is known as Sievert s law and can be used to calculate the permeation rate of diatomic gases through metals. 

The example considered here involves a tubular reactor made of steel that is to be used in the high-pressure hydrogenation of hydrocarbon vapor. The vessel is 3 m long, has an internal radius of 5 cm, and is to be operated at a pressure of 100 afm and a temperafure of 45(HC. The permeability P at this temperature has a value of 8.4 x 10 cm (STP) cm/cm s atm.  

We wish to calculate the wall thickness required to keep hydrogen losses within reasonable bounds. The reader may recall that a similar configuration and process had been considered in Illustration 1.2 to derive the diffusion rate through a hollow cylinder. That rate was given by the expression 

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