Worksheet 7 Recycle and Purge

__________________________  _  CHE112P Names: _________________________ Sec: _____ 

Worksheet 7:_________  Recycle and Purge

Problem Solvng 1! Pure Pure "ro "ro"a "ane ne #C #C $H%& 'rom 'rom El Paso Paso s dehy dehydr drog ogen enat ated ed cata cataly lytc tcal ally ly n a contnuous "rocess to obtan "ro"ylene #C $H(&! )ll o' the hydrogen 'ormed s se"arated 'rom the reactor e*t gas +th no loss o' hydrocarbon! ,he hydr hydroc ocar arbo bon n m*tu m*ture re s then then 'rac 'ract ton onat ated ed to gve gve a "rod "roduc uctt strea stream m contanng contanng %% mole- "ro"ylene "ro"ylene and 12 mole- "ro"ane! "ro"ane! ,he other stream. +hch s 7/ mole- "ro"ane and $/ mole- "ro"ylene. s recycled! ,he one0 "ass converson n the reactor s 2-. and 1/// kg o' 'resh "ro"ane are 'ed "er hour! nd #a& the kg o' "roduct stream "er hour. and #b& the kg o'  recycle stream "er hour!

a. Draw the the complete complete diagram diagram and and write the balance balanced d equation equation..

b. For a basis of 1000 kg/h of fresh propane, propane, specif specif amounts amounts that are a!ailable. a!ailable.

c. "alculat "alculate e the kg of product product stre stream am per per hour. hour.

d. "alculat "alculate e the kg kg of recc reccle le stream stream per per hour. hour.

e. #hat is the recc reccle le to to fresh fresh feed ratio$ ratio$

2! Ethylene o*de s "roduced by burnng ethylene and an undesred sde reacton s the com"lete combuston o' ethylene! 2C2H3 4 52  2C2H35 C2H3 4 $52  2C52 4 2H25 



,he 'eed to the reactor contans $ moles o' ethylene "er mole o' o*ygen! ,he sngle0"ass converson o' ethylene s 2/- and yelds 6/ moles o'  ethylene o*de 'or every 1// mole o' ethylene consumed n the reactor! ) com"le* se"araton system s used so that ethylene and o*ygen may be recycled to the reactor. +hle carbon do*de and +ater are dscarded and ethylene o*de s "ackaged and sold! )ssume a 1// moleh 'eed rate o'  ethylene to the reactor! 8etermne the re9ured recycle rate to 'resh 'eed rate rato!

a. Draw the complete diagram.

b. For a 100 mole/h feed rate of ethlene to the reactor. Determine the required reccle rate to fresh feed rate ratio.

$! ethanol s synthes;ed 'rom carbon mono*de and hydrogen n a catalytc reactor! ,he 'resh 'eed to the "rocess contans $2!/ mole- C5. (3!/- H 2

and 3!/- N 2! ,hs stream s m*ed +th a recycle stream n a rato  mole recycle1 mole 'resh 'eed to "roduce the 'eed to the reactor. +hch contans 1$!/ mole- N2! ) lo+ sngle0"ass converson s attaned n the reactor! ,he reactor e
a

Draw the complete diagram and write the balanced equation.

b

%pecif the basis and the amount of the species a!ailable.

c

"alculate the production of methanol per hour &mol/h'.

d

"alculate the molar (ow rate and composition of purge stream.

e

"alculate the single pass and o!erall con!ersion of ").