Sizing of Safety Valves for Flashing Multiphase Flow – ISO ...€¦ · Mass flow rate through...

Sizing of Safety Valves for Flashing Multiphase Flow –ISO 4126 and state of knowledgeProf. Dr. Jürgen Schmidt, CSE-Institut (Pfinztal)

CSE-Institute – Competence Center for Process- and Plant Safety [email protected]

CENTER OF SAFETY EXELLENCE, JOSEF-FRAUNHOFER-STR 9, 76434 PFINZTAL WWW.CSE-INSTITUT.DE

Cyrogenic Safety – HSE Seminar, CERN, Geneva 2016

Sizing of Safety Devices

22.09.2016 PROF. DR. JÜRGEN SCHMIDT | CSE-INSTITUT, PFINZTAL

youngmotivatedambitious

talentedintelligent

Workshop for safety valve performance tests

Classical Experiment (Test rig) Modern CFD calculation

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2

CFD Simulation of High Pressure Safety Valves


Challanges:

Real Gas Properties

Dynamic Spring / Mass System (moving grids)

Moving Critical Pressure Ratio

Nitrogen 400 bar

PhD Thesis Arend Beune,TU Eindhoven, NL, 2009

Analysis of high pressure safety valves

3

CFD Simulation of High Pressure Safety Valves


Mach [-] Pressure [bar] Temperature [K]

Gehäuse

Entrance

Valvedisc

Nitrogen 400 bar

A. Beune, J. Kuerten, J. Schmidt: Num. calculation and experimental validation of safety valve flows at pressure up to 600 bar, AIChE J., 02/2011

4

1) Numerical simulation (e.g. CFX, Fluent …)Complex valve geometry (details of valve geometry necessary; moving system)3D choking phenomenon (changeable locations)Local properties lacking(phase distribution, momentum/heat/mass transfer

2) Simplified ModelingConsidering a safety valve as an ideal nozzle(frictionless flow / adiabatic system)⇒ all effects of property data / flashing catched !Correction by a discharge coefficient(contraction / redirection of flow, frictional effects, heat exchange)⇒ mainly geometrical effects

Sizing of Safety Devices - Basic Approaches


Not yet an option for industrial purpose 1

23

Chokingarea

5

Mass flow rate through safety valve

Sizing equation:

Discharge coefficient to be determined experimentally by valve manufacturer

Critical flow in the narrowest cross section depending on inlet flow conditions

Sizing of Safety Valves - Fluiddynamic Basics


, ,nozzlem SV d mQ K Q= ⋅

Discharge coefficient

pb

p0

Throat“th”T0

Qm,nozzle

Inlet“0”

Pressure

pth = pcrit

Nozzle length

6

Consider:(1) Phase change (HEM)(2) Real gas effects (EOS gas / liquid)(3) Boiling delay (empirical HNE-DS)(4) Slip (empirical)(5) Degassing (empirical)…

Numerical solution: dependent on EOS (SRK, RK, PR …)

Analytical solution:

Sizing Methods – Nozzle Mass Flow Rate


0

**

1 p

th p

C v dv

η= −∫

Flow coefficient(dimensionless mass flow rate):

dimensionless specific volume of two-phase flow

0

0

( ) 1 1pv Nv p

ω

= − −

Omega Methods (API, ISO, HNE-CSE)N Non-equilibrium factor

Diener / Schmidt 1998 / 2001 / 2004

𝑣𝑣∗

7


Compressibility coeffizient

Boiling delay faktor

Critical pressure drop

HNE-CSE (Homogeneous Non-Equilibrium Consistent set of Sizing Equations)

g l g l

v, 0

2

0 ,0 ,0 0 0 ,0 ,0

0 0

x v cp p T v vN

v v hω

∆

⋅ ⋅ ⋅ −= + ⋅ ⋅

g l0 l

v, 0

a

,0 ,0,0 0 0 2

( v v )N x cp p T ln

h∆ η

− = + ⋅ ⋅ ⋅ ⋅

1

( ) ( ) ( ) ( )ηωηωηωωη −⋅⋅−⋅−+ 1 2 + 2+ 1 2 0 2222 ln =

( )( )2 ph

1ln 1 1C

1 1 1

ω ω ηη

ωη

⋅ − − −

= ⋅ − +

Dimensionlessmass flow rate

HNE-CSE method – Mass Flow Rate

Na

N

8

HNE-CSE Method – Graphical Solution


J. Schmidt, " Sizing of nozzles, venturis, orifices, control and safety valves for initially subcooled gas/liquid two-phase flow – the HNE-DS method”, Forsch. Ingenieurwes. (2007) 71: 47–58

η

C

2.0=rp Water 73.0=sη

critC

1. 2. 3. 4.

critη

1.00

Analytical solutionof possiblecritη

0.000.75 0.50 0.25 0.000.00

0.25

0.50

0.75

1.00

9

Valve Sizing ISO 4126-10

22.09.2016 PROF. DR. JÜRGEN SCHMIDT | CSE-INSTITUT, PFINZTAL 10

Fluid ConditionValve Inlet

Definition ofSizing CaseCauses for Pressure Deviation

Pressure Relief: Bottom/DomeLevel Swell (Foam / Viscosity)

Mass Flow Rateto be Discharged

Heat Input:Fire / External heating / Chem. ReactionReaction System:Tempered / hybrid / gassyMass Flow Quality at Valve InletEnergy to be Discharged

SizingSafety Valve

SafeValve Function

Valve with Bellow / Friction damperChattering / Futtering ?

SeeISO 4126-7Dichargeable

Valve Mass FluxCritical Mass Flow Rate

Safety Valve Installation in Practice


Deviation of Valve Installations from Standard Requirements

ISO 4126-9„… total pressure drop to the valve inlet does not exceed 3 %of the set pressure”

15 % of SV installations not in accordance to the 3 % rule

> 3 % < 3 %

Evaluation of valve installations in industrial plants

Inlet Pressure Loss

80 372 SVs1 550 SVs2 4 000 SVs3 13 049 SVs4

1. Kumana, Z. & Aldeeb, A. Analysis of Pressure Relief System Deficiencies. in 17th Annual Int. Symp. October 28-30 157–165 (2014).2. SMITH, D., BURGESS, J. & POWERS, C. Relief device inlet piping : Beyond the 3 percent rule. Hydrocarb. Process. 59–66 (2011).3. Köper, O. & Westphal, F. Database-supported documentation and verification of pressure relief device design in chemical plants. J. Loss Prev. Process Ind. 16, 73–79 (2003).4. Berwanger, P. C., Kreder, R. A. & Lee, W.-S. Analysis identifies deficiencies in existing pressure relief systems. Process Saf. Prog. 19, 166–172 (2000).

15,6 % 18,0 %12,0 % 8,2 %

EuroValve (CSE)European Programon Evaluation of SafetyValve Stability (BASF, Bayer, …) Fluttering / Chattering

Development of Valve Stability Criteria(3% rule will exchanged)

SmOP (CSE)Smart OverpressureProtection Devices adapt Valve Openingon Process Conditions

Current Activities / Research Gaps


> 10 HzDarby, R. & Aldeeb, A. A.: The dynamic response of pressure reliefvalves in vapor or gas service. Part III: Model validation.J. Loss Prev. Process Ind. 31, 133–141 (2014).

CSE High Pressure Test Faciltiy


Low PressureBuffer Vessel150 bar36 m / 24 m70 m3

High Pressure Tower700 bar / 3400 barBuffer Vessel

Installation QI/2017

CSE High Pressure Test Faciltiy


Stickstoffspeicher

Stickstoffpuffer

Wasserpuffer

Speisung 11 m

SV N 2

Feed line11 m

700 bar

700 bar

3.400 bar

Gas Buffer of 700 and 3400 bar Part

CSE-INSTITUT.DE

Research and Education in Process and Plant Safety

Sizing of Safety Valves for Flashing Multiphase Flow – ISO ...€¦ · Mass flow rate through...

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