Steam Conditioning Valves and Turbine Bypass Systems

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 (p1 = 10 bar) (p2 = 1 bar) 10bar 5,46bar 2,98bar 1,63bar 1bar Max. reduction of pressure by factor 0,546 per stage

Noise control by careful selection of pressure reduction Realistic Example: HP System: p1 = 125 bar, T1 = 560 C IP System: p2 = 32 bar, T2 = 340 C to 400 C. Stages Free Area Pressure Reduction Temperature Stage Enthalpie Mass n A [cm 2] p Stufe [bar(a)] T [ C] HD [kj/kg] M Punkt [t/h] 83 125,0 560,0 3502 280 1 105 125x0,79=98,8 549,7 3502 280 2 132 98,8x0,79=78,0 541,2 3502 280 3 167 78x0,79=61,6 534,3 3502 280 4 212 61,6x0,79=48,7 528,6 3502 280 5 291 48,7x0,79=38,5 524,1 3502 280 6 353 38,5x0,79=32,0 521,1 3502 280

Subcritical pressure reduction Easy to maintain by modular design Components for pressure reduction are made of solid materials Seat and plug nitrided or stellited 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. Efficient vaporization Short distances for vaporization Best conditions for temperature measuring No touching of internals by water Optimum for min. flow conditions <5% of max. flow Desuperheating close to saturation temperature possible (ca. 1 to 5 C superheated)

Pipe to stabilize the nozzle Water inlet 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 treatment- Friction test after 1000 strokes of stem (material 1.4057) Stem grinded (0,1 Ra) without coating - Smooth surface - Acceptable sealing and frictional behavior Stem PVD - coated (Al Ti N) - Good 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 - Excellent characteristics in the scratch test Stem coated, Plasma nitrided - Good sealing and frictional behavior - High corrosion protection - Good 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 Steam Conditioning Valve for process steam extraction Cooling from 490 C to 195 C (10 C superheated)

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)

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