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Steam Conditioning Valves and
Turbine Bypass Systems
„The love of invention never
stops“
Carl Friedrich Benz (1844 – 1929)
Technology from
Germany changed
plant construction
for generations.
The gas power plant of Bochum Verein was the most advanced of
its time (1902)
Living Values ​for over 90 years
Taking responsibility
A passion for technology
Count on experience
1919 – BOMAFA Armaturen GmbH
Development, Manufacturing, Service
2012 – BOMAFA India
Manufacturing and Service for India
BOMAFA Group
2010 – H+G Maschinenbau GmbH
Precise machining of large
1988 – asfa Antriebssysteme GmbH
Development of actuator systems
Today the BOMAFA Group is
one of the leading suppliers
for special valve solutions in
Germany
Each BOMAFA valve comprises the
experience of over 1000 projects worldwide
Customized HP-IP-LP systems for
the steam generation of tomorrow
HP Turbine Bypass Systems for
the latest 1000 MW
powerplants
IP Bypass Valves
LP Turbine Bypass
Systems for large steam
volumes
Precise steam conditioning
valves for processing industries
(Ethanol, Pulp and Paper,
Chemistry, Steal…)
Variety of BOMAFA Valves
HP Gate
Valves
HP WIV
Valves
Dump Tubes
Desuperheater
Efficiency through BOMAFA Know-How
Safe pressure reduction and highest controllability
Precise desuperheating close to saturated steam
Solutions for unique applications
„Customized steam conditioning
valves pay for themselves in a
short period of time. They
prevent steam losses,
vibrations, noise and water
hammer. Precise steam cooling
to 5 ° C over saturated steam is
possible.
BOMAFA develops such valves
for 90 years“
Turbine Bypass Valves (HP - IP - LP)
field of application
Taking over of the steam in case of Turbine Trip, start up and shut down condition
Bypassing of the steam to the next lower intermediate system or to the condenser
Turbine Bypass Valves are responsible for the pressure reduction as well as the temperature reduction in
the same value as the turbine
Pressure reduction and desuperheating
in a cyclic process of a Power Plant with single re-heater
1->2 Pressurerizing of the fluid (Pump)
2->3 Heating, Vapourization,
Superheating
3->4 Expansion in the HP Part of the
Turbine, generation of technical Energy
3->4’ Pressure reducing HP Bypass mode
4’->4 Desuperheating, HP Bypass mode
4->5 Isobaric reheating
5->6 Expansion in the LP Turbine,
generation of technical Energy
5->6’ Pressure reducing in LP Bypass mode
6’->6 Desuperheating in LP Bypass mode
6->1 Condensation
Steam conditioning and
turbine bypass valves
Actuator
Inlet
Pressure reduction
Desuperheating
Outlet
Principles of pressure
reduction
Connected systems with pressure
differences have balancing ambition
Leading values are the pressure P1,
P2, temperatures T1, T2 and the
connecting area A.
The medium flow goes from system 1
to system 2 with the velocity v
Depending on the pressure difference between the 2
systems, the velocity develops respectively.
For steam:
subcritical (p2/p1 > 0,546)
critical (p2/p1 = 0,546)
overcritical(p2/p1 < 0,546)
Noise control by careful
selection of pressure
reduction
Example:
Pressure vessel
Atmospheric pressure
10bar
5,46bar
(p1 = 10 bar)
(p2 = 1 bar)
2,98bar
Max. reduction of pressure by factor 0,546 per stage
1,63bar
1bar
Noise control by careful
selection of pressure
reduction
Realistic Example:
p1 = 125 bar, T1 = 560 °C
p2 = 32 bar, T2 = 340 °C to 400 °C.
HP System:
IP System:
Stages
Free Area
Pressure Reduction
TemperatureStage
n
A [cm
pStufe [bar(a)]
83
105
132
167
212
291
353
125,0
125x0,79=98,8
98,8x0,79=78,0
78x0,79=61,6
61,6x0,79=48,7
48,7x0,79=38,5
38,5x0,79=32,0
1
2
3
4
5
6
2]
Mass
T [°C]
Enthalpie
HD
[kJ/kg]
560,0
549,7
541,2
534,3
528,6
524,1
521,1
3502
3502
3502
3502
3502
3502
3502
280
280
280
280
280
280
280
MPunkt [t/h]
Subcritical pressure
reduction
Easy to maintain by
modular design
Seat and plug nitrided
or stellited
Components for
pressure reduction are
made of solid materials
Complete
controlability over
all stages
Inlet
Subcritical multistage
pressure reduction
Pressure reduction with
motive steam extraction
Valve closed
Pressure reduction with
motive steam extraction
Valve opened by 5% –
extraction of motive steam
Pressure reduction with
motive steam extraction
Vave opened by 20%
Pressure reduction with
motive steam extraction
Valve opened by 100%
Desuperheating – Motive steam
A motive steam assisted desuperheating will be selected for critical applications - cooling
close to saturated vapor, small volume of flow or continuous operation.
The motive steam is taken after the first pressure reduction stage and passed through a
nozzle. There it is accelerated by the design of the nozzle together with the injected water
and mixed. This procedure requires only very short evaporation distances.
Optimum for min. flow conditions
<5% of max. flow
•
•
•
Efficient vaporization
•
Best conditions for temperature measuring
•
No touching of internals by water
•
Desuperheating close to saturation
temperature possible (ca. 1 to 5 °C
superheated)
Short distances for vaporization
Water inlet
Pipe to stabilize
the nozzle
Direct motive steam
injection
Two-substance nozzle
for optimized mixing of
steam and water
Motive Steam
Desuperheating
BOMAFA valve with
motive steam
desuperheating
6 Stages
Leakage Class V
Pressure Seal
Body made of F
91
Desuperheating – Radial Desuperheater
Radial desuperheaters are based on the principle of pressurized atomization. By their design
with up to 21 nozzles, they are particularly suitable for the injection of large water loads.
The individual nozzles are connected with a ring line. The injection of water is controlled via
a separate valve and the spring load of the individual nozzles.
•
Optimized for the injection of large water
loads
•
High controllability by spring loaded nozzles
•
Easy exchange of single nozzles possible
•
No touching of internals by water
Radial Desuperheater
Special Topic
Avoidance of corrosion
Corrosion of components during operation, particularly at higher temperatures
Corrosion during downtime
Corrosion due to external influences (seawater, aggressive environment, …)
Active Protection
(Avoid the emergence of corrosion on site)
Avoid outdoor installation
Preservation of valve during downtime
Passive Protection
(What the manufacturer can do)
Provide components in aggressive environments with
coatings
Surface treatmentFriction test after 1000 strokes of stem (material 1.4057)
Stem grinded
(0,1 Ra) without coating
Stem PVD - coated (Al Ti N)
- Smooth surface
- Good sealing and frictional
behavior
- Acceptable sealing and
frictional behavior
- High corrosion protection
- Good characteristics in the scratch
test
„Inductive Coat“
( Nickel based alloy )
- Inhomogeneous sight
- Excellent sealing and frictional
behavior
- Excellent corrosion protection
Stem coated, Plasma nitrided
- Good sealing and frictional
behavior
- High corrosion protection
- Good characteristics in the
scratch test
- Excellent characteristics in the
scratch test
Source: MPA Universität Stuttgart (2010): FORSCHUNGSVORHABEN AiF-Nr. 15722N / VGB-Nr. 317, „Optimierung von
Spindelabdichtungen in Armaturen […]“. S. 111 ff.
Special Projects
BHEL – 660 MW
Project (India)
LP Bypass Valve
Capacity: 900 t/h steam inlet
Desuperheating: 431 t/h of water
injected by 18 spring loaded
nozzles
Cooling to 155 °C
Material 1.4903
LP Bypass Valve
South America:
HP Bypass-valves
for the Ethanol
Industry
Capacity: 0,5 - 4 t/h incl. water
Pressure Reduction: from 64 to
12 bar a
Cooling from 490°C to 195 °C
(10 °C superheated)
Steam Conditioning Valve
for process steam
extraction
Rhein Paper
Germany
Special design for
precise desuperheating
Capacity: 0,2 - 2 t/h incl. water
Pressure: 16 – 17 bar a
Cooling to 240 °C
(33 °C superheated)
Venturi desuperheater DN 50 !
BOMAFA –
Worldwide Service
BOMAFA Service is available
worldwide.
Our engineers cooperate
closely with local partners to
guarantee smooth service
works and to easily cope with
special conditions on site.
Local Service Centers:
Asia (Thailand, India, China)
Europe (Germany)
South America (Brasil)
We are looking forward to you!
www.bomafa.de