Concept: Separating Condensible and Non-Condensible Gases

Context: Condensation of H2O: Pure H2O vs. H2O in air

Today: Increase total P at constant T – Red PathsMap Landmarks & Labels – Green

Lecture 30: Decrease T at constant total P – Blue Paths

EngrD 2190 – Lecture 31

Prelim 3: Tuesday 11/23, 7:30-9:30 p.m., 245 Olin Hall.Graphical Modeling for Mass Balances - Part 2:

translating thermodynamic maps: T-(x,y) to x-y, for example.operating lines for multistage absorbers and strippersoperating lines for multistage distillationphase maps for pure substances - separating condensible vapors

from non-condensible vapors.design using single-stage and countercurrent multi-stage units -

may include use of T-(x,y), P-(x,y), H-(x,y)and ternary diagrams.

Open book, open notes, open exercise solutions.Bring a calculator and a ruler. Graphing calculators are allowed. Laptops allowed as for Prelim 1.

Practice exercises: 4.40, 4.47, 4.48, 4.58, 4.59, 4.69, 4.70, 4.77, 4.81and 4.109. Solutions are posted.

100°C 100°C 100°C

Recap from Lecture 30

Pure H2O

Pure H2O (no air)

Decrease Tat constant P

200°C100°C

1

23

4

5

Recap from Lecture 30

15.3 atm 15.3 atm 15.3 atm

pressure measured –agrees with P-T phase map

Pure H2O

Pure H2O (no air)

liquid+vapor

solid+vapor

solid+liquid

Decrease Tat constant P

12

3 45

1

2 3

Increase total Pat constant T

4

5

Pure H2O (no air)liquid

Decrease Tat constant P

1234

5

Increase Pat constant T

1

2

path slope 1

slope 1

34

tie line at 200°C

vertical path;liquids are Incompressible. 5

Pure H2O (no air)

Decrease Tat constant P

200°C100°C

1

23

4

5

Increase Pat constant T

1

23

4

5

H2O + air

from P-T phase map

1 atm5 atm

atm 5

)atm 1(20

2080

vapormols OH vapormols total

OH2

total 2

PP

atm 05

)atm 1(6.1

6.180

vapormols OH vapormols total

OH2

total 2

PP

1 atm50 atm

open valve,drain liquid

1 atm50 atm

H2O+air

liquid+vapor

solid+vapor

solid+liquid

Decrease Tat constant total P

12

3

4 5

Increase total Pat constant T

1

2 3 4

5

10

5

50

H2O + airliquid

Decrease Tat constant P

12

3 45

tie line at 61°C

tie line at 18°C

Increase total Pat constant T

1

2 path slope 13

10

10tie line at 100°C

4

5

partial of H2O

H2O + airDecrease Tat constant P

200°C100°C

12

34

5

Increase total Pat constant T

1

23 4

5

partial

partial