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Unfired pressure vessel classifications
Unfired PressureVessel
Drums Storage vessel Reactor Columns Separators Exchangers
Surge drum
Accumulator
Resin & filter
Storage
Atmospheric
Pressure
Radial flow
Axial flow
Radial & axial
Single bed
Multi bed
Fractionation
Distillation
Separation
Liquid-solid
Liquid-liquid
Gas-liquid
Gas-solid
Filter
Reboiler
Evaporator
Condenser
Cooler
Plate
Catalyst drum
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Heat exchangers
What are they for..
For exchanging heat, of course.
Most importantly, to recover and reuse generated heat,rather than merely exchanging heat
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Heat exchangers
How do they work..
By transferring the heat from a hot medium to anothercolder medium, without mixing the fluids
In most exchangers, heat is transferred by means ofconduction through the fixed walls of the exchangers
This process relies on the thermal conductivity of a solidmaterial and those of the fluids
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Heat exchangers
How do they work..continued
When designing exchangers, consider the following;
Thermal conductivity of tubes
Corrosion resistance
Heating surface areasTurbulence of fluid must be as high as possible becausethermal conductivity of fluid varies in direct proportionto the fluid turbulence
Fluid flow rate
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Heat exchangers
How do they work..continued
Generally, the thermal conductivity of a substance is lowerwhen it is in vapor phase or gas phase, than when it is inliquid phase
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Heat exchangers
Figure 6.1: Heat exchanger nomenclatures
How do they look like..
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Heat exchangers
Figure 6.1: Heat exchanger nomenclatures
How do they look like..
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Heat exchangers
How do they look like..
Figure 6.2: Heat exchangerclassifications, as per TEMA
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Heat exchangers
How do they look like..
Shell & tube bundle exchangers
The most widely used type of exchangers
A bundle is enclosed inside a shell
Fluids never come into contact with each other Tubes are attached to tubesheet by welding, brazing, or
rolling
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Heat exchangers
How do they look like..
Shell & tube bundle exchangers
Baffle plates
For causing the fluid flow inside the shell side to come into
contact with as much tube surface as possible, hence moreheat transfer will take place
They also provide support to the tubes
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Heat exchangers
How do they look like..
Shell & tube bundle exchangers
Fixed tubesheet
Both ends of the tube bundle are rigid little expansion of
the tubes Used when temperature difference between two fluids is
small
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Heat exchangers
How do they look like.
Figure 6.6: Tube passesarrangements
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Heat exchangers
How do they look like.
Figure 6.7: An exampleof a tubesheet
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Heat exchangers
How do they work..
Reboilers
Installed at bottom of columns
Used to provide boilup for distillation and similar towers
They generate pressure required to push the vapor up the column Vapor pressure generated must overcome pressure drop inside
column
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Heat exchangers
How do they look like..
Reboilers
Figure 6.8: Varioustypes of reboilers
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Heat exchangers
How do they work..
Reboilers
Kettle type
Tube bundle inside an oversize shell which provides large
vapor space above the bundle This large vapor space is where liquid and gas phases are
separated and then withdrawn separately
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Heat exchangers
How do they look like..
Reboilers
Kettle type
Figure 6.9: A kettle type reboiler
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Heat exchangers
How do they work..
Reboilers
Thermosyphon
The fluid will circulate at a rate which the pressure lossesin the system are just balanced by the availablehydrostatic head
The driving force for circulation round the system is thedifference in density of the cold liquid at the bottomcolumn base and inlet piping, and the hot two-phase fluid
in the upper exchanger tubes and outlet piping Top tubesheet at same level as liquid level inside tower
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Heat exchangers
What are they for..
Evaporators
To remove solvent by vaporization from solids that are notsoluble
Used to produce concentrated liquid
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Heat exchangers
How do they work..
Evaporators
Circulation of flow may be natural or forced with pumps
Forced circulation evaporators are for viscous and foulingservices but also more expensive
Most evaporators use natural circulation
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Heat exchangers
How do they look like..
Evaporators
Figure 6.10: A few types of evaporators
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Heat exchangers
How do they look like..
Evaporators
Figure 6.11: Other examples of evaporators
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Heat exchangers
What are they for..
Condensers
To reduce vapor temperature to the point of condensationi.e. vapor transforms into condensate
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Heat exchangers
How do they work..
Condensers
When freezing can occur, condensation is normallyperformed on the shell side to prevent clogging
When condensing mixtures whose lighter components aresoluble in the condensate, tube side condensation ispreferred because drainage is less complete and allowscondensation to take place at higher temperatures
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Heat exchangers
Figure 6.12: Varioustypes of condenser
How do they looklike..
Condensers
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Heat exchangers
How do they look like..
Condensers
Figure 6.13: A badly clogged seawater condenser
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Heat exchangers
What are they for.. exposed tube bundles
Air coolers
Cooler when a hot fluid is cooled to a lower desiredtemperature by transfer of heat to water
Air cooler when a hot fluid is cooled by air
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Heat exchangers
How do they work.. exposed tube bundles
Air coolers
Since air is not as good as water in removing heat, theprocess of exchanging heat is further enhanced byinstalling fins outside the tubes
The process fluids flows through finned tubes and coolingair is blown across them with fans
Air cooler is easier to maintain than water cooler becauseair is not corrosive and unlikely to foul
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Heat exchangers
How do they look like.. exposed tube bundles
Air coolers
Figure 6.14: Two types ofair coolers
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Heat exchangers
How do they look like..
Plate heat exchangers
Figure 6.15: A plate heat exchanger being serviced
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Heat exchangers
How do they look like..
Plate heat exchangers
Figure 6.17: Fluid flow inside a plate heat exchanger
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Heat exchangers
How do they look like..
Figure 6.18: Various tubefins constructions
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Heat exchangers
How do they look like..
Figure 6.19: Various tube fin attachment constructions
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