STEAM BLOW-OUT
Click Here to visit Us
https://www.egyptrol.com/
EGYPTROL View of Commissioning Process
Commissioning is the art of making all the elements of a system play together,
for the first time!
2
2
Steam Blow
3
3
Standard Commissioning Process
What is Commissioning? RTR
&
Performance
The process of assuring that all systems Test
TOAC
and components of an industrial plant are Start Up & 6 7
Planni
Plant tuning
ng
designed, installed and tested to meet 1 5
design requirements and can be operated
2 4 Steam Blow-
and maintained according to the contract Mech.,
3 out
Elec., I&C Commissioni
ng
specifications, standards and operational Erec.
Completion Pre
(ECC) Commissioning
requirements.
4
4
Steam Blow Out
1) Objective
2) Methodology
3) Engineering
4) General Safety Requirements
5) Steam Blow-out Methods & Procedures
6) System Cleanliness
7) A Case study
5
5
Steam Blow Out Objectives
To remove from plant critical systems steam piping prior to start-up:
o Construction Debris
o Scales
o Rust
o Loose Material
o Construction Leftovers
o Oil
o Weld Spatter…etc.
Remove debris to meet equipment (Turbine) OEM criteria for accepting steam.
Failure to remove debris may cause damage to turbine blades, valve internals…. 6
6
Methodology
Steam is blown with enough velocity to ensure sufficient cleaning force
Planning
Piping system is divided into different paths (steam blow phases)
Disturbance factors (K) for each path are calculated during engineering
OEM definition of Target Plate specification (Material, size LxWxH)
Verification
Disturbance factors (K) are verified during execution
OEM defines steam purity criteria for his equipment (Target Plate / Color)
7
7
Engineering
Factors that need to be considered during
Engineering phase:
o Disturbance Factor (K)
o Steam Blow-out method
o Pipe Sizing and Design
o Pipe Routing
o Steam Conditions
o Noise Level
o Thermal Cycling
o Stress analyses for temporary Pipework
and Equipment
o Water Quenching 8
8
Engineering
(K) of a particular design is calculated using the following formula:
Disturbance Factor (K) = (Vb / Vmcr) x (Fb / Fmcr)2 > 1.3
Where
o Vb = specific volume at steam blowing condition
o Vmcr = specific volume at maximum load condition
o Fb = steam mass flow rate at blowing condition
o Fmcr = steam mass flow rate at maximum load condition
o The desired ratio is 1.3 for continuous blowing
9
9
General Safety Requirements
Operations shall be organized and performed by
expert personnel.
“Exclusion Zones" to be defined, barricaded by fence,
evacuated and guarded for the duration of the steam
blow-out activity.
“STEAM BLOWING IN PROGRESS" signs to be posted.
Direct communication is required with the CCR for all
parties involved.
The steam Blow-out procedure to be understood by
all concerned parties before proceeding with the
blow-out.
All personnel working in close proximity to the area
should wear ear protection. 10
10
Steam Blow-out Methods & Procedures
1) Puffing or Shock blow 2) Continuous blow
• Steam generator pressure is • Pressure and temperature calculated
raised to the calculated pressure for (K) to be reached and conditions
• Sacrificial valve is opened are maintained for three hours,
including thermal cycling
• Steam velocity is reached, but for
• No pressure drop, with time
a short period of time
• High pressure drop, with time • Completion time: App. 5 to 7 days
• Completion time is incalculable • No operating valve is required
• Quick operating valve is required 11
11
Puffing Procedure
Quick operating valve (sacrificial valve)
open/close time < 10 second.
Start at low pressure value, then
increase pressure values to reach the
required pressure level.
First few steam blows are conducted
without target plates until steam color
becomes clear.
Preliminary target plates are placed to
verify steam cleanliness.
Final target plate is placed once
preliminary target plates are
acceptable.
Blowing continues until pits are
acceptable to turbine manufacturer. 12
12
Continuous Procedure
Continuous operation of boiler until K
Factor is reached
Pressure is maintained during the
blow-out.
K Factor (1.2 – 1.7)
Boiler load may reach 50%.
Thermal cycling is applied in order to
improve the cleaning process.
13
13
Cleanliness
The Cleaning Force Ratio (K) is used to evaluate if
satisfactory blow conditions are obtained.
Steam line cleanliness is also determined by the
condition of target plates.
Sample guidelines state the allowable quantity
and size of particle impacts on the target to be:
o no impact with a size > 1 mm
o less than 4 impacts with a size > 0.5 mm
o less than 10 impacts with a size > 0.2 mm
14
14
Thank You
15
15
