STEAM TURBINE Details in Governor

SECTION0.0

RELIANCE SDM SYSTEM

RJN/EMIN/XXXX

1.0 INTRODUCTION

In petrochemical and refinery complexes, gas compressors

are extensively used. There are mainly three types of compressors

i.e centrifugal, reciprocating and screw. The centrifugal

compressors are used widely due to the high pressure and volume

delivered by them.

Prime mover for these centrifugal compressors can be

either electrical motor or steam turbine. Steam turbines are

preferable over the electrical motors where the steam is available.

It is easier to increase/decrease speed of steam turbine for load

control purpose where as electrical motors are fixed speed.

A governor is a device, which is used to control the speed

of the turbine. The mechanical governors are used for turbine

control of small pumps .An electronic governor measures the speed

of the machine and manipulates the steam flow to the turbine to

maintain it at the desired speed.

In some cases pumps (Boiler feed water/Lube oil) or fans

are also driven by steam turbines.

2.0 PRINCIPLE OF OPERATION:

CHECKEDHSG ENGINEERING & MAINTENANCE

INSTRUMENTATION

PAGE REV ISSUE

: 1 of 10: 00: 01

APPROVED BYDGS

SELF DEVELOPMENT MODULE ELECTRONIC STEAM TURBINE

GOVERNOR

DATE AUTHOR

: 09/03/2002: BSB

SECTION0.0

RELIANCE SDM SYSTEM

RJN/EMIN/XXXX

Turbine consists of a casing containing rotor and stator.

The steam passes through the stationary nozzles and is directed at

high velocity against the rotor buckets causing the rotor to rotate at

high speed.

The following events take place in the nozzles:

The steam pressure decreases.

The enthalpy of the steam decreases.

The steam velocity increases

The volume of the steam increases.

There is a conversion of heat energy to kinetic energy as the heat

energy from the decrease in steam enthalpy is converted into

kinetic energy by the increased steam velocity.

Steam at high pressure is allowed to expand through

stationary nozzles, the result is drop in the steam pressure and an

increase in steam velocity. In fact, the steam is issued from the

nozzle in the form of a high-speed jet. This high velocity steam is

applied to properly shaped turbine blades .It will change direction

due to the shape of the blade. The effect of this change in direction

of the steam flow is to produce an impulse force on the blade

causing it to move. The blades are attached to the rotor of a

turbine. The low-pressure steam comes out of the turbine.

Most commonly used turbines in industry are the backpressure

turbines.


INSTRUMENTATION

PAGE REV ISSUE

: 2 of 10: 00: 01

APPROVED BYDGS


GOVERNOR

DATE AUTHOR

: 09/03/2002: BSB

SECTION0.0

RELIANCE SDM SYSTEM

RJN/EMIN/XXXX

The two general types of governors used are the speed sensitive

governor and the pressure sensitive governor. Speed sensitive

governors are applied to all kinds of turbines.

Pressure sensitive governors are applied to back pressure and

extraction turbines in connection with the speed sensitive governor.

The speed sensitive governor (Steam Turbine Controller) may be:

a) Mechanical Governor

c) Electronic Governor

Mechanical Governors use the fly balls with speed adjustment by

the spring. The rotating motion revolves the fly balls causing

displacement of the connecting rod and thereby of steam inlet

valve. The speed of turbine increases till the spring tension force

balances the centrifugal force of the fly balls.

Electronic Governor uses the electronic module for controlling the

start up/shut down sequence and speed control of the turbine.

Steam inlet valve is in the form of a multi port valve, which is

hydraulically operated by the signal from electronic module.

Jamnagar Complex has the following installations of Steam Turbine

Controllers:

A) Woodward (WW505) for:

1) Wet gas compressors-2 nos in FCC


INSTRUMENTATION

PAGE REV ISSUE

: 3 of 10: 00: 01

APPROVED BYDGS


GOVERNOR

DATE AUTHOR

: 09/03/2002: BSB

SECTION0.0

RELIANCE SDM SYSTEM

RJN/EMIN/XXXX

2) Recycle gas compressors-2nos in VGO HT

3) Heat pump compressor in PRU

4) Coker gas compressor in Coker

B) Triconex Forced Draft Fan Steam Turbine Governor for:

FD Fan of Auxiliary Boilers –CPP 4 nos

C) Woodward PEAK 150 for:

Boiler Feed Water Pumps---3 nos

This SDM gives the details of the Wooward505 governor. Triconex

Governor and Woodward Peak150 Governor are covered in other

SDM.

3.0 Woodward Electronic governor WW505 is used for

controlling the steam turbine (prime movers for the gas

compressors) operation at Jamnagar refinery complex. Steam

turbines are used for driving the gas compressors in process plants.

The basic function includes load variation by controlling the speed

of rotation of compressor. The final controlled variable can be

discharge/suction pressure of compressor or flow through the

compressor.

Magnetic speed pickup probes measure speed of the turbine.


INSTRUMENTATION

PAGE REV ISSUE

: 4 of 10: 00: 01

APPROVED BYDGS


GOVERNOR

DATE AUTHOR

: 09/03/2002: BSB

SECTION0.0

RELIANCE SDM SYSTEM

RJN/EMIN/XXXX

Output of the Woodward governor controls steam input to turbine

and hence speed of the turbine.

The Startup, operation and shutdown of turbine is controlled by

Woodward make Steam Turbine Controller.

Starting the Turbine (Automatic) : Turbine speed is raised

gradually to the operating speed by ramping. Speed is held at

intermediate set points called low idle and high idle. The timings

and ramp rates are user configurable. Turbine vendor normally sets

these during commissioning.

Critical Speeds: During start up, turbine passes through the speeds

at which vibration of the turbine may increase beyond dangerous

levels. So it is essential to cross these speeds as quickly as possible.

The speed ramp rate is configured to be very high in these ranges

of speed.

Operation of Turbine:

Figure 1 shows the schematic of a Turbine Control loop for

controlling the compressor load:


INSTRUMENTATION

PAGE REV ISSUE

: 5 of 10: 00: 01

APPROVED BYDGS


GOVERNOR

DATE AUTHOR

: 09/03/2002: BSB

SECTION0.0

RELIANCE SDM SYSTEM

RJN/EMIN/XXXX

PID loop is implemented in Turbine controller. It receives the

Turbine speed input from magnetic speed pickups. Remote set

point is available from DCS, which gives the command to increase

or decrease the Turbine speed depending on the compressor

loading.

Stopping of the Turbine: After Turbine Stop Command is issued

the Turbine is stopped in a controlled manner with speed ramping

to zero at a configured ramp rate.


INSTRUMENTATION

PAGE REV ISSUE

: 6 of 10: 00: 01

APPROVED BYDGS


GOVERNOR

DATE AUTHOR

: 09/03/2002: BSB

Programmable Logic Controller

(Compressor logics)

Woodward 505 Turbine Controller

Start Turbine

Stop Turbine

Remote set point Enable

Remote set point from DCS

To Turbine Steam Inlet Valve (Hydraulic Governor)

Turbine Speed signal from field

SECTION0.0

RELIANCE SDM SYSTEM

RJN/EMIN/XXXX

Various parameters such as ramp rates, timings are

configured during commissioning of the Turbine and recorded in

Configuration Worksheet. Changing of parameters is password

protected and should be carried by competent persons only with

proper approval.

4.0

For Further details of Woodward505 refer following sections

of “Woodward Digital governor for extraction steam

turbines” Volume-1 & 2

Refer to the following sections in the WW505 manual:

Sr.No Topic Section No

1 Starting features

Turbine start

2-1

4-5 Vol.1

2 Electrical connections 3-7 Vol.1

3 Speed sensor inputs 3-12 Vol.1

4 Basic control overview 4-1 Vol.1

5 Speed control

Speed set point

4-15

4-18 Vol.1

6 Emergency shutdown/Controlled shutdown 4-44 Vol.1

7 Over speed test function/procedure 4-45/6-11

Vol.1

8 Configuration procedures 5-1 Vol.1CHECKED

HSG ENGINEERING & MAINTENANCEINSTRUMENTATION

PAGE REV ISSUE

: 7 of 10: 00: 01

APPROVED BYDGS


GOVERNOR

DATE AUTHOR

: 09/03/2002: BSB

SECTION0.0

RELIANCE SDM SYSTEM

RJN/EMIN/XXXX

9 Configuration Worksheet A-3 Vol.1

10 Trips and alarms 6-29/6-30

Vol.1

11 Service Mode Procedures 4-1 Vol.2

12 Hardware specifications A-3 Vol.2

13 System faults/diagnostics 6-1 Vol.2

5.0

For Triconex Governor TRI-SEN TS310 refer to the following

sections:

Sr.No Topic Section Title and number

1

Basics

Control Actions

Function configuration

Turbo machinery

controller Extraction

/Admission operation

Section3

Section4

Section5

2 Installation ,


INSTRUMENTATION

PAGE REV ISSUE

: 8 of 10: 00: 01

APPROVED BYDGS


GOVERNOR

DATE AUTHOR

: 09/03/2002: BSB

SECTION0.0

RELIANCE SDM SYSTEM

RJN/EMIN/XXXX

System Description

Hardware

Installation

Operating functions

Maintenance

Spare parts

Specification

Configuration

Configuration,

Operation, and

Maintenance

Section2

Section3

Section4

Section5

Section6

Section7

Section8

Section9

6.0

For Woodward Peak 150 governor refer to the following sections of

the Instruction Manual “PEAK150 DIGITAL CONTROL FOR STEAM

TURBINES”

Sr.No Topic Section Title and number

1

Control Description

Wiring

Functional Description

Operating procedures

Digital Control for Steam

Turbines

Chapter 3

Chapter 4

Chapter 5

Chapter 6


INSTRUMENTATION

PAGE REV ISSUE

: 9 of 10: 00: 01

APPROVED BYDGS


GOVERNOR

DATE AUTHOR

: 09/03/2002: BSB

SECTION0.0

RELIANCE SDM SYSTEM

RJN/EMIN/XXXX

Programming

Service Menus

Configuration Menus

Functional Block Diagram

Modbus communications

Trouble shooting

Replacement and Repair

Procedures

Program mode worksheet

Chapter 7

Chapter 8

Chapter 9

Chapter 10

Chapter 11

Chapter 12

Chapter 13

Chapter 14


INSTRUMENTATION

PAGE REV ISSUE

: 10 of 10: 00: 01

APPROVED BYDGS


GOVERNOR

DATE AUTHOR

: 09/03/2002: BSB

Documents

STEAM TURBINE Details in Governor