04(Equipment Sizing)

8/13/2019 04(Equipment Sizing)

1/26

Equipment Sizing

Preliminary Equipment Sizing forCapital Cost Estimation


2/26

The Need for Equipment Sizing

Before one can carry out capital costestimates on process equipment, the

process engineer must carry out apreliminary sizing of the equipment.

Although each process will have some

unique pieces of equipment there aresome general categories applicable tomost designs


3/26

Equipment Types

Towers

Heat Exchangers

InstrumentationTanks

Vessels

Pumps

Compressors

Fired Heaters

Others


4/26

Towers

Size (height anddiameter),Pressure,Temperature

Number and Types of TraysHeight and Type of Packing

Materials of Construction

Unique Characteristics, SwagedColumns


5/26

Heat Exchangers

Type;Vapour-Vapour,Vapour-Liquid,Condenser,Vapourizer,Evaporators

Process Duty, Area, Temperature andPressure for all streams

Type, Shell and Tube, Air-Cooler, Tube andTube etc. Cooling Towers

Number of Shells and and Tube passes



6/26

Instrumentation

Pressure, Temperature, Flow and Level

Analytical, Gc, IR etc

Computer Control, Central orDistributed


7/26

Tanks

Type of Tank and Service, StandardAPI, Floating roof, Blanketed etc.



8/26

Vessels including Reactors

Height/Length,Diameter,Orientation

Pressure, Temperature



9/26


10/26

Compressors

Actual Inlet FlowRate,Temperature,Pressure,Driver

Type,Shaft PowerType of Compressor, Centrifugal, Singleor Multi-Stage,Reciprocator



11/26

Fired Heaters

Type,Tube Pressure,TubeTemperature,Duty,Fuel



12/26

Other Equipment

Filter,Blenders,Mixers, Kneaders

Centrifugal Separators,Crystallizers

Crushers and Grinders,Dust Collectors

Electrostatic Precipitators

Conveyors

(This is by no means an exhaustive list)


13/26

Sizing Procedures - Towers

Flow Sheet Simulators such as PRO/II and HYSYS have built in sizing

routines for most type of mass transferdevices such as Fractionation Towersand Liquid-Liquid Extraction Towers.

Unique devices such as Rotating DiskContactor would require a specificprocedure.


14/26

Towers Continued

For Fractionations, the designer mustdetermine the number of theoretical

stages required for a certain reflux andboil-up rate in order to achieve therequired separation. The appropriate

type of Mass Transfer device must bechosen, I.e. Trayed Tower, PackedTower etc.


15/26

Towers Continued

If a trayed tower is selected, the type oftrays must be specified, bubble-cap,

seive or valve trays. For packed towersthe type of packing must be selected.

There are many types of towers, Simple

Absorbers, Rectified Absorbers,Reboiled Strippers, Steam Strippers etc.


16/26

Heat Exchangers

The most common type of heatexchanger is the shell and tube. Shell

and tube exchangers come in manyconfigurations, however as in the casewith fractionators most simulators suchas HYSYS can carry out a rigourous

exchanger design. Condensers andThermosyphon Reboilers are tediouscalculations best done by a computer.


17/26


18/26

Instrumentation

For the purpose of preliminaryestimates instrumentation is usually

costed simply as a factor of majorcapital.

Instrumentation (Process Control) has

become increasingly more sophisticatedand costly.


19/26

Instrumentation continued

Although a factor approach may besuitable for a preliminary estimate, a

better definition is required for adefinitive estimate. Some units have avery sophisticated plant-wide

supervisory control which is based oncomplex computer technology.


20/26


21/26

Vessels

This category covers a wide range ofequipment from reactors to flash drum,

overhead accumulators, flare drumsetc. Some of this equipment can bereadily sized by heuristic residence time

considerations. Reactor design can bea simple residence time consideration,or a very complex design problem.


22/26

Vessels continued

CSTRs are usually a relatively simplevessel with an agitator, although heat

removal problems may complicate thedesign. Other reactors are considerablymore complex, for example catalytic

fluid bed cracker reactors andregenerators, and trickle phasereactors.


23/26

Pumps

The major concern with pump sizing isselecting the particular type of pump for

the service. Although centrifugal pumpsare the most common, other types areoften required, reciprocating, gear

pumps and so on. You will be providedwith a spread-sheet for the sizing ofpumps.


24/26

Compressors Expanders

Flowsheet simulators such as HYSYS haveroutines that are to be used for sizingcompressors (and expanders).

One common error that students in thedesign course make is specifying acompressor to move liquid. Compressors are

used for vapour, pumps for liquids.Compressors can be destroyed by slugs ofliquid in the feed.


25/26

Fired Heaters

This is a relatively complex sizingproblem, and fortunately we dont have

to deal with it in the design exercise.Direct fired reboilers are notuncommon, particularly in the

petroleum industry, however we haveavoided the need for such a unit in thedesign project


26/26

Others

There are a great deal of unitoperations that fall into this category,

all with their own unique sizingprocedures. Solids handling is a fairlybroad field, as is the equipment used

for bioseparations.

04(Equipment Sizing)

Documents

Transcript of 04(Equipment Sizing)