chemical reaction engineering lecture reactor design 3
- 1. PKC2070 Unit III Isothermal Reactor Design Lecture 3 Reactor Design-1
- 2. Space time & Space velocity • Just as the reaction time t is the natural performance measure for a batch reactor, • so are the space-time and space-velocity the proper performance measures of flow reactors
- 3. • A space-time of 2 min means that every 2 min one reactor volume of feed at specified conditions is being treated by the reactor. OR 0.5 times of reactor volumes of feed at specified conditions are being fed into the reactor per min. • A space-velocity of 5 hr-1 means that five reactor volumes of feed at specified conditions are being fed into the reactor per hour. OR Every 0.2 hr one reactor volume of feed at specified conditions is being treated by the reactor.
- 4. • Now we may arbitrarily select the temperature, pressure, and state (gas, liquid, or solid) at which we choose to measure the volume of material being fed to the reactor. • Certainly, then, the value for space-velocity or space-time depends on the conditions selected. If they are of the stream entering the reactor, the relation between s and τ and the other pertinent variables is
- 5. • It may be more convenient to measure the volumetric feed rate at some standard state, especially when the reactor is to operate at a number of temperatures (non-isothermal). • If, for example, the material is gaseous when fed to the reactor at high temperature but is liquid at the standard state, care must be taken to specify precisely what state has been chosen. The relation between the space-velocity and space-time for actual feed conditions (unprimed symbols) and at standard conditions (designated by primes) is given by
- 6. Residence time • Time spent by molecules inside the reactor • Represent in the form of residence time distribution E(t)
- 7. Reactor Differential Algebraic Integral The GMBE applied to the four major reactor types (and the general reaction A B) CSTR Batch NA t PFR FA V Reactor Mole Balances Summary
- 8. Reference Chapter-5 Octave Levenspiel, Chemical Reaction Engineering, 3rd edition OR Chapter-1 H. Scott Fogler, Elements of Chemical Reaction Engineering, 4th edition