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Process Department
SSE-06COMPARATIVE STUDY OF THE USE OFVISUAL FLOW, INPLANT AND OTHER SIMULATORS IN THE RELIEF SYSTEM
DESIGN
Invensys User Group Series, Houston, October 15-16
Copyright © 2012. Inelectra SACA.- All rights reserved
Prepared by: Pedro CeballosRevised by: Edgar Alfonso / Carmelo Trezza / María Pereira / Fernando Azuaje
Content
• DA-1/ DA-2/ VDU Relief System Hydraulic Evaluation
• Relief System Hydraulic Evaluations
• Comparison of Simulators
• Relief Systems
• Conclusions
• Relief System Components
• Installing a pressure relief device, lines and means for transport and disposal of the relief fluid in gaseous phase, liquid or both.
• It is used when the presence of liquid, toxic properties or other factors would make it dangerous to discharge into the atmosphere
Relief Systems
Definition:
Standards Applicable to Relief Systems:
API 520 I. Sizing, Selection, and Installation of Pressure-Relieving Devices in Refineries. Part I—Sizing and Selection
API 520 II. Sizing, Selection, and Installation of Pressure-Relieving Devices inRefineries. Part II—Installation
API 521. Pressure-relieving and Depressuring Systems
API 526. Flanged Steel Pressure Relief Valves
API 537. Flare Details for General Refinery and Petrochemical Service
API 576. Inspection of Pressure-relieving Devices
Relief Valves
Discharge Lines
KnockOut Drum
Flare
KnockOut Drum Pumps
Subheaders
Header
Protected Equipments
Relief System Components
KnockOut Drum
Relief System Hydraulic Evaluations
P2= 0 psig
DPtip= 3 psig
DPsello= 2 psig
P1= ? psig
(Set pressure)
(Backpressure)
Relief Valve
Flare
Criteria to define the relief valve type:
Conventional: BP/SP<10%
Balanced: 10%<BP/SP<30%
Pilot:30%<BP/SP<75%
(%) =BP Backpressure (psig)SP Set Pressure (psig)
DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation
Description:
Project: Deep Conversion
Location: Puerto La Cruz Refinery
Engineering: Detail
UnitsInvolved:
DA-1/DA-2 (Atmospheric Distillation Units)VDU (Vacio Unit)
Flare Type: Ground Flare
Darwin LNG; Australia
DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation
* Validate the results obtained during the basic engineering of hydraulic calculations associated with the main header of Ground Flare Relief System and DA-1/DA-2/VDU referred to in the Deep Conversion Project of Puerto La Cruz.
Main Objective:
* Compare the use, advantages and disadvantages of simulators available in the Company (INELECTRA) for Relief Systems Analysis (VISUAL FLOW, INPLANT, Aspen Flare and Superchems).
Secondary Objective :
* Pressure of 10 psi at Ground Flare.
* In the General Electric Power Failure DA-1, DA-2 and VDU discharge simultaneously.
* Maximum speed (Mach): Discharge Line: 0.75 / Header-SubHeader: 0.50.
* Backpressure criteria: Conventional: 10% / Balanced: 30% / Pilot: 75%.
Design Basis:
DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation
Relief System Design :Main Contingency: General Electric Power Failure
Total Relief Load: 782392 lb/h
Size Head: 42’’
Equipment InvolvedDA-1: Atmospheric TowerDA-2: Atmospheric TowerVDU: Vacuum Tower
GroundFlare
DA-2
DA-1
VDUTRAIN 1 & 2
42’’
DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation
Relief System Scheme:
VISUAL FLOW Simulation:
DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation
DA-1 Tower
DA-2 Tower
VDU Towers
INPLANT Simulation
DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation
DA-1 Tower
DA-2 Tower
VDU Towers
Aspen Flare Simulation
DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation
DA-1 Tower
DA-2 Tower
VDU Towers
SuperChems Simulation
DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation
SIMULATOR PARAMETER PSV-05391-A PSV-05391-B PSV-05391-CSP= 30 psig SP= 31.5 psig SP= 31.5 psig
BASIC ENG.(SUPERCHEMS)
Outlet Line Mach Nro 0.169 0.169 0.169Backpressure (psig) 21.5 21.5 21.5Back P / Set P (%) 71.5 68.1 68.1
DETAIL ENG.(VISUAL FLOW)
Outlet Line Mach Nro 0.192 0.192 0.192Backpressure (psig) 15.4 15.4 15.7Back P / Set P (%) 51.3 48.8 49.8
Results. General Power Failure (DA-2 Tower)
DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation
SIMULATOR PARAMETERPSV-04416A PSV-04416B PSV-04416C PSV-04416D PSV-04416E PSV-04416FSP=30psig SP=31.5psig SP=31.5psig SP=31.5psig SP=31.5psig SP=31.5psig
BASIC ENG.(SUPERCHEMS)
Outlet Line Mach Nro 0.191 0.191 0.191 0.191 0.191 0.191Backpressure (psig) 21.9 21.9 21.9 21.9 21.9 21.9Back P / Set P (%) 73.1 69.6 69.6 69.6 69.6 69.6
DETAIL ENG.(VISUAL FLOW)
Outlet Line Mach Nro 0.216 0.214 0.214 0.313 0.313 0.313Backpressure (psig) 15.0 15.3 15.3 14.7 14.7 14.6Back P / Set P (%) 49.9 48.6 48.6 46.6 46.6 46.5
Results. Cooling Water Failure (DA-1 Tower)
Elbow 90° 90 deg. 1 Weld. 90 deg angleElbow 45° 45 deg. Standard (R/D=1), all typesT branch Used as elbow. Standard, screwed
T run Run through tee. Screwed
Elbow 90° Long-Radius (R/D=1.5), all typesElbow 45° 45 deg. Long radius (R/D=1.5), all typesT branch Used as elbow. Standard, flanged/welded
T run Run through tee. Flanged/welded
Origin of differences (Basic Eng. – Detail Eng.)
Header Inside Diameter 42’’:
K(12”)=1.247
K(12”)=0.217
Fittings (Basic Eng.):
DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation
Fittings (Detail Eng):
Basic Eng.: Detail Eng. (Piping Classs) 40’’ 41.188’’
SIMULATOR PARAMETER PSV-04416A PSV-04416B PSV-04416C PSV-04416D PSV-04416E PSV-04416FSP=30psig SP=31.5psig SP=31.5psig SP=31.5psig SP=31.5psig SP=31.5psig
VISUAL FLOWOutlet Line Mach Nro 0.216 0.214 0.214 0.313 0.313 0.313Backpressure (psig) 15.0 15.3 15.3 14.7 14.7 14.6Back P / Set P (%) 49.9 48.6 48.6 46.6 46.6 46.5
INPLANTOutlet Line Mach Nro 0.209 0.209 0.209 0.209 0.209 0.209Backpressure (psig) 15.9 15.9 15.9 15.9 15.9 15.9Back P / Set P (%) 52.8 50.3 50.3 50.3 50.3 50.3
ASPEN FLAREOutlet Line Mach Nro 0.209 0.212 0.211 0.210 0.210 0.210Backpressure (psig) 16.3 15.9 16.1 16.1 16.1 16.1Back P / Set P (%) 54.4 50.4 51.0 51.2 51.3 51.1
SUPERCHEMSOutlet Line Mach Nro 0.210 0.210 0.210 0.210 0.210 0.210Backpressure (psig) 15.0 15.0 15.0 15.0 15.0 15.0Back P / Set P (%) 50.1 47.7 47.7 47.7 47.7 47.7
Results. Cooling Water Failure (DA-1 Tower)
DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation
SIMULATOR PARAMETER PSV-05391-A PSV-05391-B PSV-05391-CSP= 30 psig SP= 31.5 psig SP= 31.5 psig
VISUAL FLOWOutlet Line Mach Nro 0.192 0.192 0.192Backpressure (psig) 15.4 15.4 15.7Back P / Set P (%) 51.3 48.8 49.8
INPLANTOutlet Line Mach Nro 0.185 0.185 0.185Backpressure (psig) 16.2 16.1 16.1Back P / Set P (%) 54.1 51.0 51.0
ASPEN FLAREOutlet Line Mach Nro 0.185 0.185 0.186Backpressure (psig) 16.3 16.3 16.3Back P / Set P (%) 54.3 51.9 51.7
SUPERCHEMSOutlet Line Mach Nro 0.187 0.187 0.187Backpressure (psig) 15.8 15.8 15.8Back P / Set P (%) 52.6 50.1 50.1
Results. General Power Failure (DA-2 Tower)
DA-1/ DA-2/ VDU Relief SystemHydraulic Evaluation
Comparision of Simulators
Mounting the Model:
VISUAL FLOW INPLANT ASPEN
FLARE SUPERCHEMS
Allows change the method of thermodynamic YES YES YES NOAllows added viscosity experimental data. NO YES NO NOEasy to add components and uses them when performing the simulation on other computers NO YES YES NO
Allows to create pseudocomponentes with PM>1000 NO YES NO YES
Allowsto add over 50 pseudocomponentes in a line YES NO YES YES
Allows to add pipes to the library YES YES YES NOAllows to copy valves and equipments YES YES YES NOAllows to enable and disable lines and equipments NO YES YES NOEase of data entry YES YES YES NO
Comparision of Simulators
Simulator Flexibility:
VISUAL FLOW INPLANT ASPEN
FLARE SUPERCHEMS
Evaluation of the pressure drop at the entrance of the safety valve YES NO NO YES
Can simulate various scenarios (contingencies) with a single run YES NO YES NO
Sizing Relief Valves YES YES YES YESSizing Relief Headers YES YES YES YESAllows isometric drawings YES NO NO NODynamic Evaluation of Fire Contingency NO NO NO YESRadiation Evaluation NO NO NO YESIt takes into account energy losses to the environment NO NO YES YES
Comparision of Simulators
Results Report:
VISUAL FLOW INPLANT ASPEN
FLARE SUPERCHEMS
Getting quick results (duration of the run) YES YES YES NOReports the pressure drop in each segment / fitting YES YES NO YESCalculation of relief temperature YES NO NO NOEasy to calculate backpressure on PSV YES YES YES NO
General recommendations for use of simulators according to the case study
Case Simulator
Simulation of gas reliefVISUALFLOWSuperchems
Simulation of viscous liquid relief Inplant
Simultaneous evaluation of several cases where contingency is involved one relief valve
VISUALFLOW Aspen Flare
Quick estimate of the backpressure INPLANT
Evaluation of the pressure drop at the entrance to the relief valveVISUALFLOW Superchems
Evaluation of Fire event when multiple loads are involved (dynamic simulation)
Superchems
Evaluation of heat loss to the environmentSuperchems, AspenFlare
Comparision of Simulators
* The diameters established for the main header (42"), for DA-1 subheader (42") and DA-2 subheader (30") during basic engineering are according with the design basis.
Conclusions
* It should verify that the fittings on the pipes do not create an excessive pressure drop avoid unnecessary overdesigns.
* According to the system under study, each relief systems simulator offers particular advantages, among them are the INPLANT by the facilities in the model assembly and VISUAL FLOW for flexibility and good results.
Thanks for your attention!!