(b) A fixed bed adsorber of 0.88m in length was tested for removing water vapour from nitrogen, at the temperature and pressure of 301K and 593kPa, respectively. TABLE Q2 lists the adsorption data when 4A molecular sieves were used as the adsorbent. Other operating parameters include: - Molar velocity of the feed gas is 29.6kmolm2h1, with 1115ppm (by volume) of water vapour. - The initial water loading of the adsorbent is 1g per 100g of 4A sieves. The equilibrium loading of water on the 4A adsorbent is 0.186gH2O per g of solid. - Bulk density of the adsorbent bed is 44.5kgm3 (i) If the water concentration of no more than 9ppm was required at the outlet, what is the break-through time (tb) and equilibrium time (te) ? (2 marks) (ii) Use Equation Q2.2 and Equation Q2.3 to calculate the length of a second adsorber, which follows the above operating parameters but extends the breakthrough time to 2.5 times of the tb in (i). LUB=tsLe(tstb) (11 marks) Equation Q2.2 LESAqFb=cFQAtb