External Fire Load CalculationReference API 520(Determination of Relief Load Required for External Fire Case)

Vessel Tag Number & Service 92C2 Toluene Column

Input Values Environmental FactorEnvironmental factor …….…… 0.075 1. Bare Vessels………………………… 1.0

2500.0 2. Insulated Vessels with 1" (25 0.3Latent Heat (BTU/Ib)……………… 120 1.5" (38mm) ………………….. 0.2

2" (50mm) …………………… 0.15Calculated Values 3" (75mm) ………………….. 0.10Heat absorbed by vessel (BTU/h 962,923 4" (100mm) & greater 0.075

3. Underground Storage…………… 0Relief Required (Ib/hr)…………… 8,024 4. Earth covered Storage above gr 0.03Relief Required (kg/hr)…………… 3,640

Calculation Formula (English units)

Q =

Where,Q = Heat Absorbed by the Vessel exposed to the External Fire

A = Area exposed to the fire (Height considered from grade is within 25ft)

Total Wetted Area (ft2)……….…………….

21,000 F A0.82

F = Environmental Factor (or insulation correction factor) - Refer to above table

Pressure Safety Valve Sizing CalculationReference API 520(Sizing for Gas or Vapor Relief)

PSV Tag number…………………………92PSV7/8/9PSV Location …………………………… 92C2 Toluene Column Overhead

Case Description ……………………… Fire Steam Air Condenser Power Reflux Reboiler TubeFailure Failure Failure Failure Failure

Service Conditions

Required Flow (kg/hr) …………... 42,850 253,582 343,995 338,873 53,453

Set Pressure (kPag) ………………… 350 350 350 350 350

Percent Overpressure ……………… 21% 16% 16% 16% 16%208 179 191 179 220

Fluid Molecular Weight (MW)… 101.8 92.2 95.8 92.2 107.8

Specific Heat ratio (k)..………… 1.06 1.05 1.08 1.05 1.04

Compressibility factor (Z)……… 1.0 0.9 0.9 0.9 0.9

Back Pressure (kPag) ……………… 5 45 105 95 151.0 1.0 1.0 1.0 1.0

0.860 0.860 0.860 0.860 0.860

Specific Heat Coefficient (C*)…… 239.9 239.0 241.5 239.0 238.2% BP 20% 29% 41% 39% 23%

Calculated Values85.720 508.835 675.199 679.979 103.96313.287 78.870 104.656 105.397 16.114

Calculation Formula (Metric units) __________

W / ( T Z ) Reference API 520 (page 3)A = ----------------- / -----------------

\/ MW

Where,

* C = Calculated Specific Heat Coefficient (Based on API 520, Figure 2, page 4)

Temperature at Relief (oC)………………….

Back Pressure correction (Kb)…………….Effective Coefficient of Discharge (Kd)……

Required Orifice Area (cm2)…………….Required Orifice Area (in2)………………

(C P1 Kd Kb)

P1 = (Set Pressure (barg) + 1.033)+ OverpressureT = (Temp at Relief (oC) + 273.15)

Kd = Effective Coefficient of Discharge, Obtain from Vendor data sheets

Kb = 1 for 50% or lower backpressure. For above 50%, refer to API 520

Pressure Safety Valve Sizing CalculationReference API 520(Sizing for Steam Relief)

PSV Tag number………………………….. 91PSV71PSV Location ………………………………Cyclar Steam Drum 91V4

Service Conditions * Superheat Correction Factor

Required Flow (lb/hr) …………...… 82,500 1. Saturated Steam……… 1.00

Set Pressure (psig) ……………………… 800 2. For superheated steam refer to Table

Percent Overpressure …………………… 10% in API 520 - Part I

0.9751.001.00 *

Calculated Values1.836

Calculation Formula (English units)

WA = ------------------------ Reference API 520 (page 34)

Effective Coefficient of Discharge (Kd)……Correction Factor (KN)………………….Superheat Correction Factor (KSH)………

Required Orifice Area (in2)………………

51.5 P1 Kd KN KSH