Training manual Steam turbine valve Tài liệu nhiệt điện

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Steam Turbine Valve

Oct, 2013
Steam Turbine Engineering Team 2

This document is the informational asset of Doosan Heavy Industries & Construction. Thus, unauthorized access, revision, distribution and copying of this document are strictly prohibited. 


Contents

1. Introduction of Turbine Valve
2. Valve Operation
3. Structure of Turbine Valve (MSV,
CV)
4. Disassembly Procedure (MSV, CV)
5. Structure of Turbine Valve (CRV)
6. Design Features
7. Valve test
8. Valve support
9. Maintenance of Main Stop Valve
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1.Introduction of Turbine Valve
1. Introduction of Turbine Valve
Turbine Control System

TBN Valve : Equipment for TBN Speed, Load, Flow control and TBN Protection

Main Steam Valve
- Main Stop Valve ( MSV )
- Control Valve ( CV )
- Reheat Stop Valve ( RSV )
- Intercept Valve ( IV )
- Actuating System
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1.Introduction of Turbine Valve
1.1 Function of the Turbine Valves
The main Function of Turbine Valves is protecting the turbine from the Turbine Overspeed, and
controlling the turbine load. That is, the Valves are equipments to controlling the speed, load and
steam flow of turbine.

1.2 Arrangement of the Valves
In order to protect the turbine from the Turbine Overspeed, there are two kinds of valve set. The
first is a set of Main Stop Valve (MSV) and Control Valve (CV) at the inlet of the Main Steam
Lead Pipe, and the second is a set of Reheat Stop Valve (RSV) and Intercept Valve (IV) at the
exit of the Reheater. So, MSV and CV are called as HP Valves, and the valve installed at the LP
or IP turbine is called as Combined Reheat Valve (CRV).
The arrangement of HP Valves and CRV is operating to the double protection circuit for
preventing the Turbine Overspeed. That is, For protecting the Turbine from the Overspeed, CV
and IV response first under Pre-Emergency condition, and MSV and RSV response as
secondary under Emergency condition. Also, MSV and RSV are closed individually when each
CV and IV is not working

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1.Introduction of Turbine Valve

Overspeed
OverspeedProtection
Protection
STEAM

SV

CV

HP

IV

RSV

1st Defence
2nd Defence
Overspeed
Overspeed Criteria
Criteria
1 st Defence To 110 % : Normal O.S
2nd Defence To 120 % : Emergency O.S
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2. Valve Operation

6

2. Valve Operation

7


2. Valve Operation

8


2. Valve Operation

9


2. Valve Operation

10


3.Structure of Turbine Valve
3.1 Main Stop Valve & Control Valve
3.1.1 Overview

MSV
FL O

W IN

MSV

CV
CV
FLOW
OUT

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3.Structure of Turbine Valve
3.1 Main Stop Valve & Control Valve
3.1.2 Section View

ACTUATOR
INR V/V

STUD
UPPER
HEAD

STRAINER
STEM
LEAK
OFF

COUPLING
CONNECTOR
UPPER

HEAD
STEM

CASING

BALANCE
CHAMBER

FLOW IN

CV CHEST

SEAT

INR V/V

MSV DISK
STEM LEAK OFF
PRESSURE
SEAL HEAD
COUPLING

CV DISK
SEAT
STEM

FLOW
OUT

ACTUATOR

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3.Structure of Turbine Valve
3.2 Main Stop Valve

BYPASS INNER VALVE
INNER VALVE BACK SEAT
INNER VALVE SEAT
MSV DISK
PRESSUER SEAL HEAD

STEM BACK SEAT
MSV STEM

FLOW IN

GUIDE BUSHING

FLOW
OUT
1ST LEAK OFF
2ND LEAK OFF
BYPASS INR V/V
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3.Structure of Turbine Valve
3.3 Control Valve
GUIDE BUSHING

2ND LEAK OFF

BALANCE CHAMBER

1ST LEAK OFF

CV STEM

CV INNER VALVE

FLOW IN
INNER VALVE SEAT
CV DISK

CV SEAT

FLOW
OUT

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4. Disassembly Procedure
4.1 Main Stop Valve Disassembly Procedure
②

②

③

④

③
①
①

15


4. Disassembly Procedure
4.2 Control Valve Disassembly Procedure
①②
①

②
④
①
③
②

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5.Structure of Turbine Valve (CRV)
5.1 Overview

IV Actuator
IV Yoke
Upper Head

FLOW IN

CRV Casing

RSV Yoke

W
OT
L
F U
O

RSV Actuator

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5.Structure of Turbine Valve (CRV)
5.2 Internal Parts

IV Coupling
IV Connector
IV Stem
IV Yoke
Strainer
Pressure
Seal
Head
RSV Stem

RSV
Coupling

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5.Structure of Turbine Valve (CRV)
5.3 Section View

IV Coupling
IV
Connector
RSV Stem
Balance
Chamber
Strainer
IV Disc
RSV Disc
Pressure
Seal
Head
RSV Stem
RSV
Coupling
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5.Structure of Turbine Valve (CRV)
5.3 Section View

IV Coupling
IV
Connector
RSV Stem
Balance
Chamber
Strainer
IV Disc
RSV Disc
Pressure
Seal
Head
RSV Stem
RSV
Coupling
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6. Design Features - Stem & Bushing
1 . Reduced Leak-off Flow
2. Apply Running Clearance preventing from sticking
between stem and bushing.
- Material Thermal Expansion
- Determine proper clearance
3. Nitriding process to prevent from oxidation buildup and have a good abrasion resistance.
4. Ni alloy steel is used for stem which has a high
creep strength and a low oxidation rate. It is expected
that this material will reduce the amount of stem
bending and extend the interval between required
cleaning of the stems.

Stem
Bush

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6. Design Features - Strainer
1 . The figure of Strainer

Steam Flow
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6. Design Features - Strainer
1 . The figure of Strainer

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6. Design Features - Strainer
1 . The figure of Strainer

Detail of Screen Mesh
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6. Design Features - Strainer
2. The figure of Strainer with foreign material

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