equipment design basis

8/18/2019 Equipment Design Basis

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1.1 Equipment design basis

1.1.1 Colums, Vessels and Reactors

1.1.1.1 Design pressure• Factors like pumps shut-off conditions, pressure drops in recycle loop etc. should be

considered for fixing design pressure. Pump shut-off shall be calculated at 1.25 x rated

head + max. suction pressure.

Equipment which could have to bear the shut-off pressure of a pump in case of a valve

closing (either control valve or block valve) is designed for the following pressure:

Design pressure = Design pressure of the suction vessel + liquid height at vessel !! at

pump suction + "#$ % of pump differential pressure&

• hen operating pressure is less than or e!ual to 1"" kg#cm$, design pressure shall be

e!ual to normal operating pressure plus 1" % &min. 2." kg#cm$'. hen operating pressureis more than 1"" kg#cm$, design pressure shall be e!ual to normal operating pressure plus

5 % &min 1" kg#cm$'.

• (ll steam handling # condensate )essels shall be designed for full )acuum conditions also.

• (ll )essels # columns sub*ect to internal pressure should be designed to ithstand a

minimum external pressure of ".15 kg#cm$ abs.

• inimum design pressure for e!uipment connected ith flare header should be

.5 kg#cm$g.

•

/pecial consideration should be gi)en &for )acuum design' to the design of )esselnormally sub*ect to internal pressure and connected to a compressor suction or e*ectors.

'ull vacuum will be specified for isolable equipment containing fluid having a vapour

pressure lower than atmospheric pressure at ambient temperature&

'or equipment subect to pressure and temperature swings the magnitude and frequenc*

of these swings will be given on the specification sheet&

hen several pieces of equipment are protected b* the same relief valve each piece of

equipment will be designed at least for the pressure imposed b* the discharge conditions

of the relief valve in case of emergenc*&

'or fractionation columns the reference design pressure is taken as that at the bottom of the column&


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1.1.1.2 Design temperature

• 0esign temperature for unfired pressure )essels and interconnecting piping ill in

general be e!ual to maximum anticipated operating temperature plus " if )essel

operates beteen 3ero to 4"" and 2 if )essel operates abo)e 4"".

6f it operates belo 3ero degree temp. 7689/:; should follo his on philosophy.

• onditions like steam-out &for handing out )essel to maintenance' ill be considered

hile specifying design temperature.

• For )essels operating at ambient temperature, he column internals can be trays or packing. Preferred type of trays shall be a )al)e tray

&stainless steel'.

'or operating temperatures below ,. minimum operating temperature / $. or

minimum ambient temperature&

0he effect of autorefrigeration due to depressuri1ation to atmospheric pressure will be

taken into consideration (!23 s*stems for e4ample)&

'or feed5effluent e4changers of reaction sections + #$. to be added to ma4& operating

temperature to take into account the temperature profile modification at low capacit*&

1.1.1.3 Liquid residence time

;esidence time is defined beteen lo li!uid le)el and high li!uid le)el.

Service Residence time

;eflux = 1" minutes

olumn feed = 15 minutes on flo control

or 1" minutes on cascade le)el#flo control

;eboiling by heater = 1" minutes on feed to heater

;eboiling by thermosiphon = 1" to " seconds

Product to storage = 5 minutesProduct feeding another unit = 15 minutes on flo control

or 1" minutes on cascade le)el#flo control

Feed surge drum = " minutes if diam ? 1.2 m

2" minutes if 1.2 m ? diam ? 1. m

15 minutes if 1. m ? diam

6n the case of pumps ensuring se)eral ser)ices such as reflux and li!uid distillate to storage,

the residence time of the corresponding )essel ill be hiche)er is greater from the abo)elist.


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1.1.1.4 Vessels speciications

• @essels ill be si3ed according to inside diameter and 2 = 1 elliptical heads or

hemispherical heads. >op co)er flanged if 60 ?A B"" mm.

• onnections ill be flanged.

• 24-inch manays are currently specified.

inimum inside diameter shall be 2" inches for 60 CA B"" mm.

7arger si3e ill be specified hen re!uired to accommodate internals.

6n trayed columns, manays ill be pro)ided abo)e the top tray, at the feed tray and belo

the bottom tray. ( manay ill be pro)ided at any tray ith remo)able internals.

inimum numbers of manay = 1 manay e)ery


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• ;e!uirement of broad e!uipment specification=

Folloing are the constraints in transportation and handling of hea)y e!uipment=

a' aximum eight of e!uipment4"" >

b' aximum diameter including no33les # pro*ections 4.5 etre

c' aximum length o)erall

25 etre

d' For 06E and splitters, it ill be acceptable to ha)e more than 25 m

• For small diameter toers &ø ≤ ""', toer internals should be remo)able from one end

and to be cartridge type. Pro)ide flanges here necessary along toer.

equipment design basis

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