Torque Converter & Hydraulic Ratchet System - 4th
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Transcript of Torque Converter & Hydraulic Ratchet System - 4th
INDUSTRIAL GAS TURBINE
Unit 304 – Starting Equipment
Topic:
4.2 – Torque Converter
4.4 – Hydraulic Ratchet System
Page 2
Learning Aim and Objective
To Understand the function of the Torque Converter as a
starting device.
Aim:
At the end of the lesson, you should be able to:
Explain the function and the operation of torque converter.
Explain the purpose of a Hydraulic Ratchet System.
Objective:
Page 3
4.2 – Torque Converter
Background of Torque Converter :
A Torque Converter is a modified
form of a Hydrodynamic Fluid.
Allows the Gas Turbine engine to
spin independently of the generator
or centrifugal compressor.
Page 4
4.2 – Torque Converter
To provide a method and apparatus to start up Electric
Generator or Centrifugal Compressor.
To multiply torque when there is a substantial difference
between input and output rotational sped.
Improved starting method for starting Generator. Especially a
generator driven by a single shaft gas turbine machine, such
as used in Cogent plants.
Improved starting method for starting compressors.
Especially, if the compressor is driven by a single shaft gas
turbine machine (used in liquefied natural gas plants).
Function of Torque Converter:
Page 5
Why used Torque Converter?
A specific problem with the single-shaft gas turbine is that
everything is connected mechanically on a single common shaft.
hence the starting device must start up not only the gas turbine
itself, but also the connected load. Everything must be started up
and accelerated simultaneously from rest continuously up to full
speed.
The added load produced by an electric generator (Co-Gen Plant)
in an unloaded state can be handled by a single-shaft gas turbine's
standard starting system, so they use torque converter just for
loading and unloading the electric generator anytime they want.
But not the inertia and aerodynamic loads associated with a large
centrifugal compressor (LNG plants). They use torque converter to
startup their Large Compressor.
Page 6
Location?
For LNG plants, a compressor starting torque converter
(CSTC) located between the gas turbine output shaft and the
compressor input shaft.
For Co-Gen plants, it is located between the gas turbine
output shaft and the generator input shaft.
Page 7
In normal torque converter, there are at
least 3 rotating elements:
Pumps
Turbine
Stator
4.2 – Torque Converter
Torque Converter Element:
Housing
Turbine output shaftLoad Coupling
Turbine
Stator
Pump
Stator output shaft
Page 8
4.2 – Torque Converter
Input
ShaftOutput
Shaft
Torque
ConverterLock-up
Device
Guide
Vanes
Page 9
4.2 – Torque Converter
Torque Converter Lock-up Device
Engage Disengage
Locking Device
Page 10
How Torque Converter work?
As the pump spins, the fluid is flung to the outside and
creating Vacuum which draws more fluid at the centre.
Continue…
Page 11
How Torque Converter work?
The fluid then enters the blades of the turbine from outside
which gave changes on the direction of the fluid before it exits
through the centre of the turbine.
This directional change of fluid makes the turbine to spin.
Continue…
Page 12
How Torque Converter work?
Since the fluid exits the turbine moving an opposite direction
of the pump. This is why a stator is placed in between the
turbine and the pump, just to counter flow the output fluid flow
out of the turbine .
Page 13
4.2 – Torque Converter
Stall – The prime mover apply power to the pump but the
turbine is not rotating. During this period, it produce maximum
torque multiplication (called Stall Ratio).
Acceleration – During this period, the load is accelerating
but there are still having a relatively large difference between
pump and turbine speed. Under this condition, the converter
will produce torque multiplication that is less than what could
be achieved under stall conditions.
Coupling – once in this phase, the fluid will be in reverse
direction and now rotate in the direction of the pump and
turbine.
Three stage of Operation:
Page 14
4.3 – Hydraulic Ratchet System
It is used as rotor-turning device, the purpose are:
To cool down the Rotor after turbine operation (periodic).
To assists the diesel or cranking motor in starting the Gas
Turbine.
To partially turn the rotor in 3-minute stroking intervals until it
complete 1 revolution for every half an hour. This to prevent
sagging happened to the rotor.
To provide additional torque to augment the power delivered
through the torque converter during the starting up from cold.
To assists in overcoming the “breakaway torque” demand of
the turbine rotor.
Used during maintenance outstages and inspections.
Page 15
Recap
Explain the function and the operation of torque
converter.
Explain the purpose of a Hydraulic Ratchet
System.
Page 16
Overview of Next Lesson…
Section „E‟ – Cooling System
Topic: Cooling air system & sealing air
Thank you for your Attention
Page 17
4.2 – Torque Converter
Operation of Torque Converter :
• The hydraulic fluid for the torque converter supplied by the
gas turbine lube-oil system.
• During the startup operation of the gas turbine, the torque
converter hydraulic fluid is drained and the mechanical lock-
up device is disengaged.
• When the gas turbine has reached rated speed, the torque
converter guide vanes opened to filledup the torque converter
with hydraulic fluid.
• Once the torque converter full with hydraulic oil, the speed of
the generator or large compressor start to increase until it has
the same speed as the input shaft speed.
Continue…
Page 18
4.2 – Torque Converter
Operation of Torque Converter :
•Once the two speeds has synchronous, the lock-up device will
be engaged and the torque converter hydraulic oil drained by
shutting up the guide vanes.
•In this condition, the power is transmitted only mechanically
with a very high efficiency.