fire relief dynamic study
TRANSCRIPT
Name : Fire Relief Rate Study (Semi-Dynamic Approach)Version: 1.3Description This spreadsheet uses sequential flashing results from commercial simulation
software to calculate relief valve flow rate during external fire. This calculation is done for wetted vertical and horizontal vessels when flow through relief valve orifice is sonic (critical) based on API and other published articles
Producer: Saeid Rahimi M.Publishing Date: 28-Feb-2013Publisher:
No of sheets: 2Content:
AboutFire Relief Study based on Sequential Flashing Method
Reference:Relief Rate Calculation; External Fire (Part-2), Published on www.chemwork.orgSizing, Selection, and Installation of Pressure Relieving Devices in Refineries, API-520, 8th Edition, Dec 2008Pressure-relieving and Depressuring Systems, API-521, 5th Edition, Jan 2000
Revision History :Version Description of Changes Date 1.0 Produced for personal library 15-Aug-20071.1 Revised by adding different vessel orientations 23-Oct-20091.2 Modified for publishing on web 9-Sep-20111.3 Revised according to the users feedbacks 28-Feb-2013
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This spreadsheet is copyright 2011, The Chemwork Spreadsheet Page, www.chermwork.org. The information contained herein may not be retransmitted, copied, or electronically posted without the expressed written consent of its owner. You may use this spreadsheet for personal or professional use only.
PROJECT : DATE :
PROJ. NO.: BY : S.Rahimi
CLIENT : REV : 30-Dec-99
UNIT : DOC NO.:
Fire Relief Rate Study for Wetted Vessels (Sequaential Flashing Method)
Input Data
Relief Valve Set Pressure psig 176.4
Overpressure % 21.0
Total Backpressure psig 20.0
Effective Discharge Coe (Kd) --- 0.975
Backpressure Coefficient (Kb) --- 1.000
Combination Corr. Factor (Kc) --- 1.000
Fire Heat Input Rate Btu/hr ft2 21000
Insulation Factor --- 1.000
Vessel Dimesnsion
Vessel Orientation ---- Vertical
Vessel Head Cap type ---- Elliptical
Vessel Diameter m 1.0
Vessel Length m 3.0
Liquid Level Height m 1.0
Calculaion Results
Relieving Pressure psia 228.1
Critical Pressure psia 133.7
Vessel Cylinder Volume m3 2.36
Calculation Validity Cehck --- Valid
0 508.5 157.6 0.79 399 4.45 500829 3178 1444 0.8025 451.6 89.8 1.094 326.6 0.1249
5 500.2 147.7 0.76 379 4.34 490875 3323 1511 0.7888 469.1 95.2 1.094 326.6 0.1269
10 492.6 138.8 0.73 359 4.22 480151 3459 1572 0.7751 484.8 100.3 1.095 326.7 0.1286
15 485.8 131.0 0.70 339 4.10 468604 3577 1626 0.7621 498.6 105.0 1.097 326.9 0.1298
20 479.6 124.0 0.67 319 3.97 456349 3680 1673 0.7495 511.1 109.3 1.099 327.1 0.1305
25 474.1 117.8 0.63 299 3.83 443342 3764 1711 0.7378 522.3 113.3 1.101 327.3 0.1307
30 469.1 112.2 0.60 279 3.69 429700 3830 1741 0.7267 532.6 117.0 1.104 327.6 0.1305
35 464.5 107.1 0.56 259 3.54 415480 3879 1763 0.7163 541.9 120.5 1.107 327.9 0.1298
40 460.3 102.5 0.52 240 3.39 400689 3909 1777 0.7063 550.6 123.7 1.110 328.3 0.1286
Maximum Relief Valve Size 0.1307
Vap (wt% )
r (kg/m3)
l (btu/lb)
V(m3)
Mass (kg)
A(m2)
Q (btu/hr)
w (lb/hr)
W (kg/hr)
Z(--)
T (F)
M(--)
Cp/Cv(--)
C(--)
Aorifice
(in2)
in2
0 5 10 15 20 25 30 35 40 450.1200
0.1220
0.1240
0.1260
0.1280
0.1300
0.1320
Liquid Vaporized (wt%)
AO
rific
e A
rea
(in2
)