Fill Depressuring Inventory Data

Calculate the wetted area based on this size.Then, Compare with the actual wetted area

HYSYSLiquid percent = 35.6 %Wetted height = (35.6 / 100) * 11.37Wetted Area = 96 ft2 (8.9 m2)

ACTUAL

Process System2

Checking the wetted area of this model, will result the wetted area is different with the actual wetted area The model volume is good enough but sometimes the wetted area is not match with the real condition.

ACTUAL Wetted Area = 155 ft2 ( 14.4 m2)

To be applied only if heat flux of 21.000 BTU/hr ft^1.64 orQ = : Q = 21000FA^0.82

Other cases , such as *)1. For system with adequate draining

and fire fighting do not exist, the heat flux is 34500 BTU/hr.ft^1.64 C1 = 34500

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

C2 is locked, we cannot use this value for jet fire and when fraction area 1.0 ( in small

CHECK !

Fill Depressuring HEAT FLUX of FireAPI521

Process System3

2. 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 0.82C2 = 1

3. For vessel with insulation, or covered by earth, the environment factor less than 1.0ex = 0.3

fraction area 1.0 ( in small system)

Double click the sub flow sheet of depressuring go to sub-flow sheet environment double click Duty spreadsheet

CHECKING HEAT FLUX Correlation

Process System4

Lets checking this spreadsheet after running

Sometimes, this wetted area is different with the actual data.

CHECKING HEAT FLUX Correlation after Running With input data heat flux of 21000 btu/ft^1.64/hr(POOL FIRE CASE).Unit is already consistent .

Sometimes, this wetted area is different with the actual data.

Process System5

different with the actual data.

With input data heat flux of 34500 btu/ft^1.64/hr(POOL FIRE DRAINAGE DO NOT EXIST). Unit is already consistent

With input data heat flux of 94500 btu/ft2/hr ( = 300 kW/m2)(JET FIRE CASE ).Unit is NOT consistent.

Process System6

1. JET FIRE consider less wetted area than pool fire.

2. Use one biggest equipment for the wetted area consideration

C2 = 1 for jet fire

With input data heat flux of 300000

Input C1 = 300 000 W/m2 instead of 94500 btu/ft2/hr

Process System7

With input data heat flux of 300000 W/m2( = 300 kW/m2)(JET FIRE CASE ) Unit is consistent.

Now ,,We GET the PROBLEM.

1. HYSYS Depressuring Utility does not have Jet fire case

2. The Wetted Area not match with the real condition

Process System8

Click view spreadsheet go to spreadsheet

Spreadsheet method

Unit area in m2, thereforeInput C1 = 300 kW/m2C2 = 1

Process System9

C2 = 1C3 = 1

Cannot be changed

Select connections page and delete Cell D8 for tank wetted area.

DELETE : tank wetted area D8

Back to spreadsheet

Process System10

Now, the wetted area can be revised based on actual data

Input = 1, FireAPI 521 method is Applied

VERYFY RESULT

View Historical Data

Wetted area match

Process System11

Wetted area match with the actual data

# Wetted Area = 14.4 m2# Duty = 300 x 1 x 14.4

= 4320 kW

In Hysys Depressuring utility, the model is only specified as one horizontal

or vertical vessel. Dimension of that single vessel, is back calculated

based on total liquid and vapour volume. Wetted area calculation is

difficult for horizontal vessel. It is very difficult to match wetted area and

liquid volume of vessel with wetted area and volume of a real system.

HYSYS also provided fire case of pool fire and doesnt have Jet fire case.

SUMMARY

Process System12

HYSYS also provided fire case of pool fire and doesnt have Jet fire case.

To overcome this problem, we can use spreadsheet method as explained

in this tutorial.

Process System13