Nozzle Movement Calculation

Nozzle Movement Calculation

MODULE - 3

Contents

Objective

Various Equipments

Distillation Columns– Information required to calculate nozzle growth– Manual calculation for skirt growth

Exchangers

Stacked Heat Exchangers

Centrifugal Pumps

Compressors

Contents

Reboilers

Storage Tanks

Air-coolers

Objective

Objective of this presentation is to understand basis of nozzle movement calculation .

Basis of nozzle movement

Generally all the displacements are calculated at shell-nozzle junction for all equipments unless otherwise specified in project specification.

Temperatures for calculating nozzle growth are as per the respective line temperatures taken from line-list.

Following informations are required for nozzle movement calculation for columns.

– skirt height, skirt thickness,type of material and type of insulation.

– Shell diameter, nozzle projection(In case displacement is to be calculated at face of nozzle flange).

– Temperature profile (To be given by process engineer).Incase profile is not given it may be constructed using line-list temperatures– Based on temperature of outlet nozzles of tower (as per Fluor

standard)– Based on temperature of all the nozzles which can affect

temperature profile of vessel.

Columns

Column

Inlet lines having size greater than 3” only need to be considered.

Foundation Settlement

Spread Sheet For Column

Columns

Skirt growth calculation

Determine the value of :

Using chart no.1 get the value of “F”

Calculate T’ using:

T= Temp. at top of the skirt

T’= Average temp. of the skirt

Ta= Ambient temperature ( 70 Deg F )

t

kh

a''

'

a

TTT

T)( FT

T-TT

Columns

t= thickness of skirt in inches

h=height of skirt in inches

k=1.0 for skirt fully insulated

k=1.7 for skirt firebrick insulated

k=2.7 for skirt not insulated

F=Temperature correction factor

Using the calculated average temperature determine the growth of the skirt.

Columns

Using the calculated average temperature of zones determine the growth of the nozzles located in respective zones.

For intermediate points between known temperatures , use a straight line interpolation to calculate temperature.

Exchanger

Exchanger dimensions, materials,anchor and nozzle locations are taken from vendor drawings.

Average temperatures of shell and channel sections are calculated from inlet and outlet temperatures.

Horizontal movements:– for the nozzle located in shell region, average

temperature of shell is taken and for nozzles located in channel section, shell average temperature is taken till shell-channel junction, and after that channel average temperature is taken.

Exchanger

Vertical movement– is calculated using the average temperature of the

region where nozzle is located.– The growth of saddle is ignored in the calculation of

nozzle movement.

Since the nozzle loads and moments are calculated at the nozzle-shell junction the nozzle movements are also calculated at the same point.

Spread sheet for exchanger

Stacked Heat Exchanger

First of all average temperature for shell side and channel side is calculated for both the heat exchangers.

For lower heat exchanger movements are calculated exactly in the same manner as in case of single heat exchanger.

For upper heat exchanger guidelines differ from project to project.

Spread sheet for stacked heat exchanger(UE-1)

Stacked HE

IOL-PRISM-project

Stacked Heat Exchanger

For calculating Vertical movement:– As per UE-1 – Vertical movements for all the nozzles on upper

heat-exchanger is same. Movement for nozzle on shell side is calculated and for others same value is superimposed.

– As per imperial-oil and Baton-Rouge – vertical movements for both the nozzles on channel

and shell section are calculated separately.

Stacked Heat-Exchangers

For calculating Horizontal movement:– As per Ue-1 – Horizontal movements for nozzles located on upper

heat exchangers are equal to the corresponding nozzles on lower heat-exchanger provided both the nozzles are located at the same distance from anchor.

– As per Imperial-oil– Movement on channel side nozzle is equal to

corresponding nozzle on lower heat-exchanger, while for nozzle on shell side back calculation is made.

Centrifugal pumps

Pump dimensions, configuration and nozzle locations are taken from the vendor’s drawings.

Temperatures are normally taken from operating temperatures on the line-list.

The point of zero movement is at the support of the pump casing . This point is usually the intersection of the centerline across the top of the pedestals and the centerline of the pump shaft(for centerline mounted).In some cases(foot mounted) the support point is at the bottom of casing and hence this is zero point.

Centrifugal pumps

From the point of zero growth calculate the thermal movements of the nozzles.

Generally, pump is modeled as rigid element with piping and point of zero movement is taken from API 610 for different type of arrangements:Side-suction Side-dischargeEnd-suction Top-dischargeTop-suction Top-discharge

Compressors

Compressor dimensions, configuration and nozzle locations are taken from vendor the drawings.

Temperatures are normally taken from operating temperatures shown on line-list.

Determine the anchor point from vendor’s drawing.

Based upon nozzle locations, a judgment assumption is made as to which expansions are to be based on an average temperature and which are to be based on the operating temperature of connecting nozzle.

Compressors

However the final nozzle displacements are to be taken from the vendor drawings or are to be approved by the pump vendor.

Vertical Reboilers

Reboilers may be supported from the adjacent vessel or from independent structures from grade.Most of the Reboilers supported from the independent structures from grade are placed on spring supports.

The horizontal reboiler support location depends upon its relationship to the vessel. The support location for the reboiler taken from the vessel is closer to the tangentline of the vessel in elevation.

Vertical Reboilers

Nozzle displacements for the inlet and outlet nozzles to the vessels are not calculated but the reboiler is modeled in stress package together with the vessel.It is recommended that the nozzle displacements for the other nozzles on the shell of reboiler be taken from this model itself by modelling them at their respective location.

Storage Tanks (API 650)

Vertical displacements are calculated from the foundation top where the tank rests to the nozzle centerline.Horizontal displacements are calculated from the tank centerline.The average temperature of inlet and outlet line from Line list is considered for the calculation.

If any foundation settlement values are provided by Civil Department those have to be considered too.

Air Coolers

For air-coolers Header -Box is modeled and temperature to be taken for analysis depends upon configuration. For example:

Single pass where Inlet is on one side and outlet on the other, respective temperatures to be considered.

Double pass where Inlet and outlet are located on the same side , temperature of the inlet nozzle will be the governing temperature.