What is RTD? Residence Time Distribution ·Why We Study RTD? Staying in a reactor for different time length, reactants may have different reaction extent. For a non-ideal reactor,it is necessary to know how long each element stays in,besides the average one. 11
11 What is RTD? • Residence Time Distribution • For a non-ideal reactor, it is necessary to know how long each element stays in, besides the average one. • Why We Study RTD? • Staying in a reactor for different time length, reactants may have different reaction extent
Liquid flows continuously through a tank Volume flow rate vo m3.hrI Tank capacity I.m3 The average stay time t= Vo The question is:Are all elements stay in the tank for same length?--of course not. 12
12 • Liquid flows continuously through a tank 0 v V t = Tank capacity V∙ m3 Volume flow rate v0 m3·hr-1 The average stay time • The question is: Are all elements stay in the tank for same length? --of course not
·Now we have an example 13
13 • Now we have an example
Flow rate is ~20M persons per year Capacity is 1.3Billion The average stay time i= V1,300,000,000 Vo 20,000,000 =65years 14
14 Capacity is 1.3Billion Flow rate is ~20M persons per year 65years 20,000,000 1,300,000,000 0 = = = v V t The average stay time
Not every body lives for this length There must be an age distribution. How to know it? To record the longevity of every one...... Persons per year Record how many persons leave this world year by year for the 20 million born this year. Year This is a difficult job,100 years needed 15
15 Not every body lives for this length. There must be an age distribution. How to know it? To record the longevity of every one…… This is a difficult job, 100 years needed Year Persons per year Record how many persons leave this world year by year for the 20 million born this year