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HEAT TRANSFER EQUIPMENT

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DESIGN OF HEAT EXCHANGERS

  • Classification based on primary mechanism
  • Heat exchangers
  • Condensers
  • Evaporators
  • Classification based on functional point of view
  • Heater
  • Cooler
  • Exchanger

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Heat exchangers

  • Design Equation

Q = Uo A ΔTm

  • Estimation of LMTD
  • Estimation of ΔTm
  • Estimation of Ft
  • Estimation of shell diameter
  • Estimation of individual heat transfer coefficient
  • Estimation of overall heat transfer coefficient
  • Estimation of pressure drop

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Estimation of equivalent diameter

  • For double pipe heat exchanger

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Estimation of equivalent diameter

  • For double pipe heat exchanger

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Estimation of equivalent diameter

  • For shell and tube heat exchanger with triangular pitch arrangement

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  • For shell and tube heat exchanger with square pitch arrangement

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Estimation of cross flow area shell

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Estimation of Uo

  • Overall heat transfer coefficient

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Estimation of Pressure drop

  • At shell side

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  • At tube side

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Estimation of pressure drop

  • Pressure drop in terms of liquid head

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  • Pressure drop in annulus

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STHE COMPONENTS

  • Shell
  • Tubes
  • Tube sheet
  • Baffles
  • Shell nozzles
  • Rods and spacers
  • Pass partition plates

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Design of Condenser

  • Condensation outside vertical tubes

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Design of Condenser

  • Condensation inside vertical tubes

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Design of Condenser

  • Condensation outside horizontal tubes

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MASS TRANSFER EQUIPMENT

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Design of Distillation column

Overall material balance equation

F = D + W

Individual material balance equation

FXF = DXD + WXW

Relative volatility

α = Vapor pr of MVC/ Vapor pr of LVC

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Design of Distillation column

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  • VLE data

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  • Mc-Cabe Thiele method

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Design of Distillation column

  • Different feed condition
  • Feed entering as cold liquid

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  • Feed entering at its boiling point/ saturated liquid

q = 1

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Design of Distillation column

  • Feed entering as mixture of liquid and vapor

q = x

  • Feed entering as saturated vapor

q = 0

  • Feed entering as superheated vapor

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Design of Distillation column

  • Number of theoretical stages = N – 1
  • Actual plates/stages = Theoretical stages/ Plate

efficiency

  • Height =
  • Estimation of column diameter

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Design of Absorption column

  • Estimation of packing height

Z = HTU X NTU

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Design of Absorption column

  • Column C/S area

C/S area = Gas flow rate / Operating velocity

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  • Diameter

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Design of Absorption Column

  • Number of plates required

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Design of Evaporator

  • Overall Material Balance Equation

F+S = V+P+C

F = V + P

  • Solute Material Balance Equation

FXF = PXP

  • Steam required

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Design of Evaporator

  • Heat transfer area

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  • Estimation of downtake area

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Design of Evaporator

  • Area between the tubes

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  • Area of tube sheet

Thickness of hemispherical head

t = PD/4fJ

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Design of Evaporator

  • Area between the tubes

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  • Area of tube sheet

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  • Area of evaporator AE= 1.1 x Area of tube sheet

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Design of Evaporator

  • Diameter of Evaporator

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  • Height of Evaporator

H = 3 x Tube Length

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MECHANICAL DESIGN OF PIPING SYSTEM

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PIPING SYSTEM

  • Wall thickness

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  • Schedule Number

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Factors considered for Piping System

  • Choice of materials and sizes
  • Effects of temperature level and temperature changes
  • Insulation
  • Thermal expansion
  • Freezing
  • Supports needed
  • Maintenance and inspection
  • Ease of installation
  • Pumps and lines
  • Safety – Design factors & Valves

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Pipe Sizing

Type of Fluid

Reasonable velocity in m/s

Water or fluid similar to water

1 to 3

Low pressure steam (25 psig)

15 to 30

High pressure steam (100 psig and up)

30 to 60

Air at ordinary pressure (25-50 psig)

15 to 30

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Optimum pipe diameter

  • For carbon steel pipe

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  • For stainless steel pipe

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Pumping Power Required

  • Brake power required in kW is expressed as

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Pumping Power Required

  • Hydraulic power required

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  • Brake horsepower required

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Pressure loss in pipe fittings

Fitting or Valve

K, Number of velocity Heads

Number of equivalent pipe diameters

45° standard elbow

0.35

15

45° long radius elbow

0.2

10

90° standard radius elbow

0.6 – 0.8

30 - 40

90° standard long elbow

0.45

23

90° square elbow

1.5

75

Tee entry from leg

1.2

60

Union and coupling

0.04

2

Sharp reduction (Tank outlet)

0.5

25

Sudden expansion (Tank inlet)

1.0

50

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Pressure loss in pipe fittings

Fitting or Valve

K, Number of velocity Heads

Number of equivalent pipe diameters

Gate valve

Fully open

0.15

7.5

¼ open

16

800

½ open

4

200

¾ open

1

40

Globe valve

Fully open

6

300

½ open

8.5

450

Plug valve – open

0.4

18