Chemical Engineering - Industrial Organic Chemistry

Full exam

INDUSTRIAL ORGANIC C HEMISTRY – EXAM 21/0 2/2018 Consider a stream ������̇ composed by methane ( 30% ), n -hexane ( 20% ), n -octane ( 30% ) and n -decane ( 20% ) which is treated with the following downstream process: The inlet stream comes to the process at ������0= 500 � and �0= 4 �������� , it exchanges heat in the second flash and then it is fed to the first flash, which is operated at �������1= 3 �������� . Then the liquid stream �1̇ coming from the first flash is fed to the second flash, which is operated at �������2= 1 �������� . Con sidering the following assumptions: • Negligible pressure drops in the whole process scheme. • The equilibrium conditions are reached in each flash. • Vapour can be treated as an ideal mixture of ideal gases. • Liquid can be treated as an ideal mixture with neglig ible Poynting correction. • �������4 can be treated as an incondensable compound. Evaluate: 1. The state of the feed ������̇ before entering in the second flash. 2. The temperature of the first flash, as well as its extent of vaporization and the composition of the liquid stream �1̇ considering that the molar fraction of methane in the vapour phase is 0.7 3. The temperature of the second flash and its extent of vaporization , considering that ������������2 is 5° � above the minimum all owable temperat ure for the flash operating conditions. 4. The temperature of the feed ������̇ at the exit of the second flash ( ������1). 5. The state of the feed ������̇ entering in the first flash 6. The thermal duty �̇ of the first flash. Thermodynamic data log 10(�°(������))= �− � ������+ �; ������= [�]; �°(������)= [�������� ] � � � �������4 − − − �6������14 4.00266 1171 .530 −48 .784 �8������18 4.04867 1355 .126 −63 .633 �10������22 4.07857 1501 .268 −78 .670 ������������� [� (�������� �) ⁄ ] ������������� [� (�������� �) ⁄ ] Δ������������������(������������������������ ) [� ��������⁄ ] �������4 − 35 .8 − �6������14 195 .6 143 .3 31573 �8������18 255 .7 175 .9 41495 �10������22 313 .3 233 .1 51392