Process System2

SDV

SDV

SDV

SDV

SDV

SDV

SDV

SDV

BDVBDV

BDV

SDV

SDV

TO FLARE

TO FLARE

TO FLARE

1. Define the System

Process System3

1. Calculate each system volume inventory ; both piping and equipment.

LengthEquival

ent

Ratio

El. NPSPipe

Schedul

e

Internal

Diamete

r

Equivale

ntPiping

Volume

Vapour Liquid

From To Length fraction Volume

(ft) (ft) (inch) (inch) (ft) (ft3) (ft3)

3P-SDV-0013 5000-V-60 161.7 1.2 0.0 4 S40 4.026 199.17 17.607 0.8077 3.3859

5000-V-60 5000-PSV-V-60 3.3 1.3 0.0 2 S80 1.939 4.26 0.087 1.0000 0.0000

3"-300# Valve 4"-B1-PHL-100 16.4 1.3 0.0 3 S80 2.901 21.32 0.979 1.0000 0.0000

5000-V-60 5000-PSE-V-60 32.1 1.3 0.0 2 S80 1.939 41.71 0.855 1.0000 0.0000

5000-V-60 Reducer 3" x 2" 5.2 1.3 0.0 3 S40 3.069 6.82 0.350 1.0000 0.0000

Reducer 3" x 2" 3P-BDV-0016 10.2 1.3 0.0 2 S40 2.067 13.22 0.308 1.0000 0.0000

Reducer 3" x 2" 3P-PV-0023 3.7 1.3 0.0 3 S80 2.901 4.81 0.221 1.0000 0.0000

3"-GP-3P-022-BA1 VALVE 5.2 1.3 0.0 3 S40 3.069 6.82 0.350 1.0000 0.0000

2"-B1-BD-202 3P-PV-0022 16.1 1.3 0.0 2 S40 2.067 20.89 0.487 1.0000 0.0000

2"-B1-BD-202 VALVE 5.6 1.3 0.0 2 S80 1.939 7.25 0.149 1.0000 0.0000

5000-V-60 3P-SDV-0015 20.5 1.3 0.0 2 S80 1.939 26.65 0.546 0.0000 0.5465

5000-V-60 3P-SDV-0014 4.3 1.3 0.0 2 S80 1.939 5.54 0.114 0.0000 0.1137

Total 22.0543 4.0461

ID Length Orientation HLL NLL LLL Volume HLL NLL LLL Total

Tag Number Equipment Name Total HLL NLL LLLWetted

Area

Wetted

Area

Wetted

AreaArea

(ft) (ft) (ft) (ft) (ft) (ft3) (ft3) (ft3) (ft3) (ft2) (ft2) (ft2) (ft2)

5000-V-60HP TEST

SEPARATOR2.500 12.000 HORIZONTAL

2.00

0

0.75

0

0.50

0

62.9

95

54.18

3

15.74

68.812 71.849 36.811 29.174 104.065

Total63.0

0

54.18

3

15.74

68.812 71.849 36.811 29.174 104.065

Example : Piping Inventory Calculation

Example : Equipment Inventory Calculation

Process System4

Process System5

1. Adjust massflow of related stream

to achieve volume flow correspond to

inventory calculation

2. Mix those stream,

the result is as BASIS COMPOSITION

3. Balance it to initial pressure condition,

the result is as BASIS SIMULATION

Initial condition as follow :

# FIRE at design pressure or PAHH

# ADIABATIC at operating pressure

The higher the initial pressure,

the grater the flowrate load to

flare..

Because the time is set 15 minutes

No matter the initial pressure

Tool Utilities

4. Tool/ Utilities

or CTRL+U *)

*) want to know more HYSYS short cut ?

check in my blog : www.process-eng.blogspot.com

Article : useful HYSYS shortcut

http://www.process-eng.blogspot.com/http://www.process-eng.blogspot.com/http://www.process-eng.blogspot.com/

Process System6

Process System7

Process System8

Select horizontal vessel

Select stream re name to : FIRE CASESelect horizontal vessel

Automatically calculated

by HYSYS

But , You can manually

fill to apply some margin

of total inventory volume

HYSYS model the entirely

system volume as a vertical

cylinder with flat both

bottom and top.

Fill volume of liquid

Based on NLL or HLL

HHL result worst case.

Still remember the heat input ?

Example : Q = 21000FA^0.82

The wetted area based on

HLL bigger than NLL.

(The greater the wetted area

the greater the heat input

rate to vessel)

keep as it is

HYSYS will adjust vessel size both Diameter and Height so that both

the total and liquid volume are correct correspond to the input value.

Is it difficult to achieve that volume ? As a matter of fact, it is not.

vessel size is not equal with the actual wetted area.

Now, at this stage we will skip this problem this will need long explanation

I will include it in another tutorial

Process System9

Select : Fire API 521

To be applied only if heat flux of 21.000

BTU/hr ft^1.64 or

Q = : Q = 21000FA^0.82

For fire case :

Heat Loss = None

no heat loss should be

assumed in fire case

simulation for worst case

For fire case :

Heat Loss = None

other cases , such as *)

1. Jet fire , the heat flux is 95,500

BTU/ft2/hr.

C1 = 95,500

2. For small system, the fraction

area exposed by fire is 1.0 instead

of 0.82

C2 = 1

3. For vessel with insulation, or

covered by earth, the environment

factor less than 1.0

ex = 0.3

Now, at this stage we will skip those other problem this will need long

explanation I will include it in another tutorial

*)check in my blog for detail explanation : www.process-eng.blogspot.com

Article : fire case heat input rate

http://www.process-eng.blogspot.com/http://www.process-eng.blogspot.com/http://www.process-eng.blogspot.com/

Process System10

Select : Musoneilan

Fill Cf = 1

Fill Pb = 0

See table below !, it shows the result of

sensitivity test for each vapor flow

equation method.

For initial value, Pb =0

,

the value should be updated based on

flareNet study result.

# Pb has no significant effect for other

vapor flow equation.

See table below !

Parameter Unit Musoneilan Fisher Supersonic, (Cv in inch2) Subsonic, (Cv in inch2)Pb psig 0 25 50 0 25 50 0 25 50 0 25 50Cv USGPM ( 60f, 1psi)4.044 4.052 4.126 8.400 8.406 8.406 0.102 0.1019 0.102 0.102 0.1038 0.109Peak flow lb/hr 4210 4217 4292 4190 4193 4193 4191 4204 4204 4201 4264 4423

The method selection has no significant effect to the result (peak flow)

Now, you can choose one of the method with no worry about the result,

In my opinion, Musoneilan is the most simple and easy to be used.

-critical condition

It is critical flow factor, generally the

value close to 1.0

Cf = 1 for worst case of peak flow

The back pressure has significant effect only for SUBSONIC method

Process System11

This equation show ; the back

pressure has effect to the

depressuring result,,

Do you know,,

Why the back pressure has effect only for

subsonic method ? *)

In sub critical condition, the flowrate

through control valve , nozzle, orifice,

etc., ,will depends on the differential

pressure between inlet and outlet.

In critical condition, the flowrate through

control valve , nozzle, orifice, etc., ,will

only depends on the inlet pressure.

*)check in my blog : www.process-eng.blogspot.com

Article : critical - subcritical

MUSONEILAN

Cf 0.9 0.95 1

Flow 4202.545 4205.035 4205.123

Cv 4.486085 4.252576 4.040034

SENSIVITY test result

Fill Cf = 0.9 -1.0

There is no worry about the result ^_^

http://www.process-eng.blogspot.com/http://www.process-eng.blogspot.com/http://www.process-eng.blogspot.com/

Process System12

Fill PV work : 50 % for FIRE CASE

PV Work Term Contribution refers to

the isentropic efficiency of the process.

A reversible process should have a

value of 100% and an isenthalpic

process should have a value of 0%

For gas-filled systems 80% to 100%

For liquid filled systems 50% to 70%

Recommended value

-

will result in greater peak flow rate

A higher isentropic efficiency results in a lower final temperature.

A lower isentropic efficiency results in a higher final peak flow rate

More liquid more interaction between

liquid and vapor. decrease isentropic

efficiency

For small system inventory

( small vessel model) more friction

between fluid and the vessel wall

decrease isentropic efficiency

Process System13

Set depressuring time = 15 minutes *)

Considering of the maximum reduction

of the vessel stress, vessel with thickness

less than 1 inch, generally requires

faster depressuring rate.

Consideration of limiting flare

capacity, the depressuring time longer

than 15 minutes may be applied

The longer the depressuring time, the higher the depressuring load

Fill initial value

Set final pressure = 100 psig

Or 50 % design pressure *)

HYSYS will adjust the Cv value to

achieve final pressure (e.g.100psig) at

depressuring time (e.g. 15 min)

-100 psig for thickness less than 1 inch

-and 50% DP for more

*)check in my blog : www.process-eng.blogspot.com

Article : basic depressuring - why 15 minutes?

Depressurized from design pressure*)

http://www.process-eng.blogspot.com/http://www.process-eng.blogspot.com/http://www.process-eng.blogspot.com/

Process System14

MAX. FLOW for

fire case

MAX. Cv

MIN. System

Temperature

(during

depressuring)

MIN. outlet RO

Temperature

(during

depressuring)

Result in peak flow to flare = 10740 lb/hr

Max Cv = 16.63

Process System15

Process System16

HYSYS Tool / Utilities

or CTRL+U *)

2nd step

3rd step

1ST step

Fill all of data similar with FIRE CASE

except that volume of liquid

based on LLL

LLL mean lower liquid increase

isentropic efficiency will result in

lower final temperature

(see page 12)

Lower liquid lower flashed vapor

formed from liquid phase will

result in shorter depressuring time

Select stream BASIS SIMULATION

Process System17

Select : Adiabatic

No heat input

Select : None

HYSYS does not

account for any heat

loss

During a fire case the vessel is covered

with flame. In this case, heat loss to the

surrounding atmosphere determined by

taking a normal atmospheric temperature

is generallynot correct as the vessel's

surrounding temperature is very high.

You should use no heat loss, select

Can be applied if the fluid temperature is

lower than the environment temperature.

I suggest you to use DETAILED model

for accurate calculations

IF ONLY you know what to do :- )

this option,,suusahhh cuuukkk).

Heat Loss Parameter:

except for system which is the fluid temperature lower

than environment , NONE model should be applied (for

lower final temperature)

I suggest you to use SIMPLE heat loss

model for accurate calculations.

Use default values except the AMB

temperature.

Process System18

See page .10 about Pb

Fill CV as FIRE CASE result

Cv = 16.63 see page 14

Cf = Cf in accordance with

FIRE CASE

Cf 0.9 1.0

Process System19

Fill 100% for worst case

For gas-filled systems 80% to 100%

For liquid filled systems 50% to 70%

For small system, or liquid filled

system, engineering adjustment

should be used. The lower efficiency

shall be used for accurate calculation

Process System20

TRIAL depressuring time

to meet final pressure 0 psig

HYSYS will calculate final

pressure based on depressuring

time

In some cases, the final pressure

0 psig).

lower pressure.

The fact, the fluid is released to flare. The pressure of the system is correspond

to the back pressure . Therefore, the final pressure is slightly above atmospheric

condition

Depressurized from

operating pressure*)

Process System21

Required adiabatic

depressuring time

Min Temperature

outlet RO

Min Temperature

In the system

Adiabatic peak flow

Process System22

Process System23

Select File

Select :

# Temperature

# Pressure

# Mass Flow

VIEW strip chart

Depressuring profile

VIEW result in Table

Depressuring data

Process System24

also click PERFORMANCE/ STRIP CHARTS

An example : show table