Done byDone by::

Esraá HajjeyahEsraá Hajjeyah

Supervised bySupervised by::Prof. M.FahimProf. M.Fahim

Eng. Yusuf IsmailEng. Yusuf Ismail

OutlinesOutlines

• Distillation Column T-103.

• Refrigeration Cycle.

1.Distillation ColumnT-(103):

Objective: To separate propylene from propane and produce high purity of propylene as the desired product.

Assumptions

1-Tray spacing= 0.8 m2-Percent of flooding at maximum flow rate=85%3 -Percent of downcomer area of total area=12%

4 -The hole area =10% the active area.5-weir height=50 mm

6-Hole diameter=5 mm7-Plate thickness=5 mm

1. Collect the system physical properties.

Design procedure:

2 .Calculate liquid - vapor flow factor.

w vLV

w L

LF

V

WV = vapor mass flow rate, Kg/s

WL = liquid mass flow rate,

Kg/s

v = vapor density, Kg/m3

L = liquid density, Kg/m3

Select trial plate spacing from 0.15m to 1m. 3

2n (m )

v

VA

u

V = volumetric flow rate, m3/s

vu

= flooding at maximum flow rate, m/s

3 . (m /s)

3600

w

v

V M WtV

(m/s) %v fu flooding u

4. Calculate the net area required.

5. Calculate total column cross sectional area.

2 (m )1 %downcomer area of total area

nc

AA

6. Calculate the column diameter.

*4 (m) c

c

AD

7. Calculate number of holes.

2 (m ) %downcomer area of total area *d cA A

Where

dA = cross sectional area of downcomer , m2

n c dA A A Where

nA = net area, m2

2a c dA A A Where

aA = active area, m2

10%*h aA A

hA =hole area, m2

Area of one hole = 2*

4 hd

Where

Number of holes = Ah / area of one hole

8. Calculate height of the column.

(Plate spacing X actual number of trays)c cH D

9. Calculate thickness of the column.

Pr

0.6i

c cJ

t CSE P

Where

ct = column thickness, in

P = maximum pressure, psi

ri = column radius, in

= stress of metal, psi

JE = joint efficiency

S

10. Select the material of construction.

11. Select the material of insulation.

12. Estimate the cost of the equipment.

Results:

Type Tray column

Type of tray Sieve tray

Diameter (m) 6.43

Number of Trays 180

Tray Spacing (m)0.8

Number of Holes 125673

Height (m)158

Reflux Ratio 8.34

Material of Construction

Caron steel

Insulation Glass wool

Cost ($) 2,030,800

Discussion:

• From the original propylene process, the distillation column was simulated in hysys using 50 plates with propylene purity of 99.5%.

• At that number of plates two main problems were exists

1) The reflux rate was very high and this was affecting the diameter of the column.

2) Very high duty on the condenser

• To solve this problem I increased number of trays.

# of plates VS. diameter & height

0

2

4

6

8

10

12

14

0 20 40 60 80 100 120 140 160

# of plates

diam

eter

0

20

40

60

80

100

120

heig

ht

2.Refrigeration Cycle:

• Refrigeration is the process of removing heat from an enclosed space, or from a substance, and rejecting it elsewhere for the primary purpose of lowering the temperature of the enclosed space or substance and then maintaining that lower temperature.

• In the refrigeration cycle a substance, called the refrigerant, is compressed, cooled, and then expanded.

• A refrigerant is a compound used in a heat cycle. This fluid boils at a very low temperature enabling it to evaporate and absorb heat.

• Common industrial refrigerants are: -Ammonia -Propane -Ethane -Freon.

• These substances are used as refrigerants because of their very low boiling points at atmospheric pressure.

• There are many types of refrigeration cycles that used in industries. The single refrigeration cycle is the simple type. Improvements on the simple cycle are made to get lower temperatures.

HYSYS simulation for refrigeration Cycle

• In our plant the refrigeration cycle is needed to provide a very cold refrigerant as the utility stream for the condensers in the three distillation columns used in the propylene process.

Objective:

• From HYSYS, the temperatures of the outlet streams of these three condensers are negative, so to reach this low temperature we need to add refrigeration cycle section.

• The lowest temperature was reached using ethane at atmospheric pressure was -88.73°C.

Assumptions:

1) Simple cycle was simulated using ethane as the refrigerant.

2) Three streams of refrigerant were needed for each condenser.

3) Three evaporators were used and these evaporators are equivalent to the condensers of the distillation columns

4) Two flow sheets were designed for the refrigeration cycle . One with expander and the other one with valve.

Discussion:

Using a valve or an expander will produce the same required results for temperature of the refrigerant streams, so the only difference between the two flow sheets is in the cost of the equipments used.

A) For the first flow sheet using valve

Total cost = $ 353,600

B) For the second flow sheet using expander

Total cost = $ 1,288,800

Thank you for listening