in bord book it is written that CaCl2 can not be used to dry NH3 in haber’s process since it formsCaCl2.8NH3 but it is byproduct itself

dear neha 
kindly elaborate your query , 
let me to exaplain the haber’s process . 
its a industrial process to prepare ammonia , when 1 mole of n2 and 3 mole of h2 react at 500 degree celsius temp and 200-900 atm pressure in presence of iron catalyst molybdenium , it gives ammonia 
and reaction 
N2 +3h2 = 2 nh3 ( this is not equal but reversible sign ) 
here delta h = -92 KJ 
hope it clears now 
if not , kindly tell me where u have doubt 
regards