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INTRODUCTION PACKAGE POWER PLANT GENERAL Turbine Model MS-5000 is a single-shaft, simple cycle, generator drive unit.
The fuel used to start and operate the
gas turbine is indicated in the Equipment Data Summary. The gas turbine assembly consists of three basic components: the axial-flow compressor, the oombustion section, and the turbine. For major dimensions, weights and location of the turbine components refer to the Reference Drawing Section. The gas turbine unit has two main bearings which support the rotor.
Bearing No. 1 is located in the compressor inlet
casing and bearing No. 2 is located in the exhaust frame.
The
location of the bearings is shown on the Gas Turbine Arrangement drawing in the Reference Drawings Section. PRINCIPLES OF GAS TURBINE OPERATION The single rotor, which is a combined compressor/turbine rotor is initially brought to speed by a starting device described in the Equipment Data Summary.
Atmospheric air is then drawn into the
compressor and raised to a static pressure several times that of the atmosphere.
This high pressure air flows to the combustion
chambers where fuel is being delivered under pressure, and a high voltage spark ignites the fuel-air mixture.
Once ignited, combustion
will remain continuous in the air stream for as long as fuel is delivered to the combust.ion chambers.
The high pressure, high
temperature gases which are produced expand through the turbine and are exhausted to atmosphere.
If a heat recovery device has been
installed it will be indicated in the Equipment Data Summary.
In
such cases,. exhaust gases are used to preheat the air discharged from the compressor before it enters the combustion chambers.
Introduction
As the hot gases pass through the turbine, they cause the turbine to spin: thus rotating the compressor and applying a torque output to the driven generator and those accessories of the turbine which require it. PACKAGE POWER PLANTS The General
Electric Package Power Plant is a compact, self
contained power generating station.
It consists of four major
functional sub-assemblies each having the required accessories. These include the power gas turbine package, the generator package, and the generator auxiliaries package.
All these packages, as they
are called, are housed in trim all-weather enclosures referred to in this manual as compartments. These are designed to provide adequate thermal and acoustical protection. Necessary heating and lighting have been included. Contained in the control compartment is all the necessary equipment to provide normal control and indication functions. This compartment is located in line with the power/or turbine compartment, however it is mounted on its own base.
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/The power compartment is actually made up of two separated compartments:
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one contains the gas turbine; the other contains
the auxiliaries necessary to make the plant a self sufficient generating station.
One base supports these areas.
/The generator, the reduction gear and the generator cooling air system are contained in one compartment having its own base. Switchgear and
ex~iter
equipment is located in the generator
auxiliaries compartment which is located at the aft end of the power plant.
The switchgear includes the main breaker, generator
surge protection equipment, and instrument transformer9 and relaying devices.
The excitation equipment is a static (non-rotating) device.
These sit on their own base.
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TURBINE AND SUPPORTS TURBINE BASE The base upon which the gas turbine is mounted is a structural steel fabrication.
A lube oil storage tank within the forward end
supplies the lube oil for the gas turbine and its associated equip ment. An oil drain channel is constructed along the web of the left longitudinal I-beam.
The channel, extending from the oil tank to
the fabricated box at the aft end of the base, provides a passage for the lube oil header. The lube oil header carries lube oil to the No.2 bearing, load coupling and driven equipment.
The lube oil feed and drain connec
tions for these parts are made at the box. Finished pads on the bottom of the base facilitate its mounting on the foundation. TURBINE SUPPORTS ,....; I ,....;
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The forward end of the gas turbine is supported by a flexible plate that is welded to the base and bolted and dowelled to the air inlet casing. On each side of the-turbine shell is a rigid leg type support which is close-fitted on a support trunnion.
The leg-type supports
maintain the axial location of the turbine while the gib key main tains the lateral location. GIB KEY AND GUIDE BLOCK A gib key is machined on the lower half of the turbine shell. The key fits into a guide block which is welded to the turbine base. The
k~y
is bolted securely into the guide block and prevents lateral
or rotational movement of the turbine. The key and block arrangement permits axial movement due to thermal expansion.
TURBINE SECTION GENERAL The turbine section is where the high temperature gases from the combustion section are converted to shaft horsepower.
The power re
quired to drive the load package and the compressor is provided by the two-stage turbine rotor.
The first-stage, or high pressure wheel
and the second-stage, or low pressure wheel are bolted together to make up a single unit through which the first and second stage nozzles direct the
f~ow
of combustion gases.
These components, with
associated air seals and deflectors, are contained within the turbine shell. The forward section of the turbine shell forms the casing for the aft end of the compressor discharge and combustion sections.
The
aft section of the turbine shell forms the casing for the first and
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second-stage nozzles and the shrouds for the first and second-stage
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turbine rotors. Compressor fourth-stage extraction air is piped to cool the shell and then discharged at the aft end of the shell to cool the
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aft surface of the second-stage turbine wheel.
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FIRST-STAGE NOZZLE The first-stage nozzle assembly consists of airfoil-shaped partitions between an inner and outer sidewall.
The nozzle assembly
is divided into segments, with the segments fixed in a retaining ring assembly sustained in the turbine shell by a clamping ring. The nozzle ring and partitions are cooled by compressor dis charge air which is bled from the combustion chamber transition space.
The nozzle partitions are hollow with bleed holes drilled
in the trailing edge for cooling.
The cooling air circulates about
the sidewalls of the retaining ring into the hollow nozzle parti tions and out the bleed holes into the gas path.
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The design of the nozzle supporting arrangement permits re moval of the lower half of the nozzle assembly without removing the rotor assembly. SECOND-STAGE NOZZLE AND DIAPHRAGM The second-stage nozzle and diaphragm assembly is located be tween the first and second-stage turbine wheels. by a clamping arrangement in the turbine shell.
It is supported The assembly has
airfoil-shaped partitions between the inner and outer sidewall which direct the gas flow into the second-stage turbine buckets. M
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Insulating pipes are installed in the drilled partition holes to
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minimize the heat exchange between the nozzle partitions and the
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air flow to the turbine wheelspaces.
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The diaphragm assembly extends inboard from the nozzle assembly to the turbine rotor and divides the space between the two wheels into the high and low pressure turbine areas.
The diaphragm assembly con
tains the wheel cooling air deflectors and packing ring that provide the inner seal between the first and second-st:.age wheelspaces. The nozzle assembly and the diaphragm are both split into sep arate halves at their horizontal centerline for ease of maintenance. The lower half of the diaphragm assembly is located and supported on three radial dowel pins in the lower half of the nozzle assembly. Thus the lower halves of the two assemblies are handled as one during installation and removal, while the top halves are handled separately. The lower half of the nozzle and diaphragm assembly can be removed from the turbine shell without removing the rotor assembly. The second-stage nozzle and diaphragm assembly is positioned laterally in the turbine shell by eccentric pins installed in the top and bottom halves of the shell.
The eccentric pins are concealed
under the flange connection for the shell cooling air piping.
The
vertical position of the assembly is fixed by a set of ground clamps at the horizontal joint on each side of the turbine shell.
The re
taining pins are positioned to fit into machined cutouts on the aft outer sidewall ring of the nozzle.
The pins two in each half of the
shell, are located at about 44 degrees to the right and left side of the vertical centerline of the turbine shell assembly. The seal ring restricts air leakage and directs high velocity cooling air at the dovetail area of the second-stage wheel. -..
The
high valocity is developed when the air passes through the small holes drilled in the seal ring which is positioned opposite the dovetails. TURBINE ROTOR ASSEMBLY The turbine rotor assembly consists of the turbine-to compressor distance piece and the first and second-stage turbine wheels and buckets. The turbine wheel are forged of high temperature alloy steel. The second-stage wheel is forged with a stub shaft on which the journal and sealing surface is machined for the No. 2 bearing and its oil seal.
At the stub shaft end is a flange to couple the shaft
to the driven device.
The buckets have "pine tree" slots.
The individual components of the rotor assembly are pre-balanced and assembled so that the complete rotor assembly will require a minimum of correction.
The rotor assembly is dynamically balanced
with any required corrections carefully distributed to compensate for internal bending moments. The turbine rotor assembly is bolted to the pre-balanced com pressor rotor assembly.
This complete rotor assembly is again
dynamically balanced with any required corrections carefully dis tributed to compensate for internal bending moments.
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COMPRESSOR SECTION COMPRESSOR ROTOR The axial-flow compressor rotor assembly consists of 16 blade arid wheel assemblies and one blade and stub shaft assembly.
The
blade and stub shaft assembly and the blade and wheel assemblies are rabbeted and bolted together concentrically around the rotor axis.
The bolt holes are countersunk in the stub shaft, this machin
ing keeps the bolt heads and nuts flush with the wheel face and re If)
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duces windage loss.
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The stub shaft is machined, to provide the forward and aft
thrust
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faces and the journal for the No. 1 bearing assembly and the sealing
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surfaces for the No. 1 bearing oil seals, and the compressor low
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pressure air seal. The compressor rotor assembly is dynamically balanced before it is assembled to the pre-balanced turbine rotor assembly. pleted assembly is then dynamically balanced.
The balance
This com corr~ctions
are carefully and properly distributed so as to compensate for inter nal bending moments in the complete assembly. COMPRESSOR CASING The compressor casing encloses the compressor portion of the rotor and is divided into four sections: discharge.
inlet, forward, aft, and
All of these sections are split horizontally to facilitate
servicing. The inlet section directs the flow of outside air from the air inlet equipment into the compressor blading.
This section contains
the variable inlet guide vane assembly, the No.1 bearing assembly, and the low pressure air seals. The forward section of the compressor casing is downstream of the inlet section. through 3.
It contains the stator blading for stages 0
Bleed air from the 4th rotor stage (between the 3rd and
4th stator stages) can be extracted through four ports which are located about the aft section of the compressor casing. The aft section, downstream of the forward section, contains the stator blading for stages 4 through 9.
Bleed air from the lOth rotor
stage (between the 9th and lOth stator stages) can be extracted through four ports which are located in radial alignment with the ports used for 4th stage air extraction. The discharge section of the compressor casing, downstream of the aft section, contains the stator blading for stages 10 through 16, and exit guide vane stages 1 and 2.
A radially enlarged (bulk
head) portion of this section provides the mounting surface for the combustion chambers.
Ten air foil shaped support struts are secured
equidistantly about the ·aft surface of the bulkhead and angle inward to support the inner case assembly (inner barrel).
The space, be
This area is
of the combustion air supply. BLADING bases that fit into
dovetail shaped openings in the two-piece, semi-circular ring.
The
ring fits into a groove of the same shape machined in the compressor casing wall.
Locking keys prevent the rotating of the blade rings.
The rotor blades also have dovetailed bases of a wide angle design which fit into the matching dovetail openings in the wheels.
The
rotor blades are peened in place. VARIABLE INLET GUIDE VANES The variable inlet guide vanes (in conjunction with lOth stage air extraction) permit fast, smooth acceleration of the turbine without compressor surge (pulsation).
A hydraulic cylinder, mounted
on a base cross member, actuated the inlet guide vanes through a
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designed to decelerate the air flow and increase the static pressure
dovetail~shaped
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section outer shell, forms an annular air path that the high pressure
The stator blades have
p.
(1)
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tween the forward portion of the inner barrel and the discharge air passes through to enter the combustion section.
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large ring gear and multiple small pinion gears. vanes are set at 44° position.
At start-up, the
(They do not wait until turbine'speed
drops below 95%.) NOTE The 44° and 80° angles are measured between the chord line of the vane and a line perpendicular to the center line of the turbine. COMBUSTION SECTION GENERAL The combustion section consists of combustion chambers, fuel nozzles, flame detection equipment, spark plugs, and transition pieces. The combustion chambers are arranged concentrically around the axial-flow compressor and are bolted to the compressor discharge section bulkhead.
Air for combustion is supplied directly from the
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axial-flow compressor to the combustion chambers.
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the chambers through fuel nozzles that extend into each chamber's
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liner cap.
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Fuel is fed into
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As a protective measure on oil-fired units, a
fa~se
start drain
valve is installed in the drain line piping at the bottom side of the No.5 combustion chamber, the concentrical arrangement).
(the chamber at the lowest point of This normally open air-operated valve
prevents the accumulation of fuel oil in the combustion area and also in the turbine sections when a start signal is given and the turbine fails to start.
In the turbine section any accumulated fuel oil will
drain from the compressor discharge casing to this valve.
The valve
is automatically closed by compressor discharge pressure as the tur bine accelerates.
The valve diaphragm is protected against excessive
air pressure by a pressure regulating valve installed in the air piping to the valve operating mechanism.
COMBUSTION CHAMBERS The high pressure air flow from the compressor discharges into the annular space created by the aft end of the discharge casing and frame assembly and the forward section of the turbine shell.
Up
to this point, the air flow has been in an aft directionj now the air flow reverses.
The air enters the combustion chambers and flows
forward, entering the liner through holes and louvers in the liner wall.
A portion of the air reaches the head of the combustion
chamber and enters the liner cap and the turbulator nozzle.
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The air flow through the combustion chambers has three functions; to oXJidize the fuel, to cool the metal parts, and to adjust the ex tremely hot combustion products to the desired turbine inlet tempera
(1)
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ture.
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Combustion chambers, with the Turbulator System are designed to eliminate exhaust smoke air pollution during the operation of the gas turbine after the start sequence.
Lean primary combustion
followed by a "thermal soaking" assures that all soot is burned during combustion.
The Turbulator System accomplishes this aerodynamically
by stabilizing the lean combustion zone with a vortex generated by an air nozzle
~urrounding
the fuel nozzle.
Dilution of the combustion
products to turbine inlet temperature is delayed to allow consumption of any soot that was not burned in the combustion zone.
The burning
of this soot is accomplished by not injecting any air into the liner until the air reaches the downstream end of the combustion chamber. The combustion chamber liners and casings are not all identical in design nor interchangeable on different model series of gas tur bines.
However, on an individual turbine, with the exception of
combustion chamber No.5, the casings and cap and liner assemblies are all identical and are interchangeable.
An exception to this is
when there is special instrumentation. The combustion chamber casings have machined pads for mounting the spark plugs and flame detectors.
The casing liners have holes
through which the spark plugs and flame detector body projects.
The bolted on casing covers which support the fuel nozzle utilize two oversize bolts in the bolt circle to facilitate re positioning of the fuel nozzle when the fuel piping is installed. SPARK PLUGS Combustion of the fuel and air mixture is initiated by retract ing electrode type spark plugs.
The spark plugs, installed in two
of the combustion chambers, receive their power from the ignition transformers.
The chambers without spark plugs are fired with flame
from the fired chambers through interconnecting crossfire tubes. TRANSITION PIECES The transition pieces (fishtails) are the hot gas path link be tween the combustion chambers and the first stage nozzle. clamped to the forward side of the nozzle assembly.
They are
The nozzle
assembly is sealed at both its outer and inner periphery to prevent leakage of hot gases.
On the outer periphery of the nozzle, the
transition space is sealed by the turbine wheel shrouds, to which the nozzle assembly is clamped. 0'\
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On the inner periphery of the nozzle, the
transition space is sealed by seal segments installed between the nozzle inner sidewall and the first-stage nozzle support assembly. The nozzle assembly and its support arrangement hold the assembly
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in proper alignment in the gas path and make allowances for the effects
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of thermal growth.
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Before the compressor discharge air flows into the combustion chamber, it must first pass around the transition pieces.
This en
counter affords an exchange of heat; cooling the transition pieces and preheating the combustion air.
BEARINGS GENERAL The gas turbine unit has two main bearings, one located in the inlet casing and the other located in the exhaust frame, both support the compressor/turbine rotor.
The No. I bearing assembly actually
contains three bearings; loaded thrust, unloaded thrust, and journal. The No. 2 bearing assembly contains only a journal bearing.
The
bearing assembly consists of oil seal assemblies, an oil ring and
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the housing which surrounds the assemblies, with the assemblies keyed to the housing to prevent their rotating with the shaft.
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LUBRICATION
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The main turbipe bearing are pressure-lubricated by lube oil supplied from the lube oil header.
The lube oil from the header
flows through branch lines to an inlet in each bearing housing. The high pressure oil feed piping, when practical, is run within the low pressure tank drain line, or drain channels, as a protective meausre.
This is referred to as double piping.
The reason for this
is that in the event of a high pressure pipe leak, oil will not be sprayed on associated equipment and create a hazardous condition. When the lubricating oil enters the housing inlet, it flows into an annulus around the bearing liner.
From the annulus the oil
flows through machined holes in the liner to the jounal bearing. Lubricating oil is prevented from escaping along the turbine shaft by oil seals. The drain oil, returns through passages in the bearing housing, then into the drain line to the oil tank. OIL SEALS AND SEAL RING Oil seals control the flow of oil along the shaft.
The seals
consist of labyrinth packings of teeth assembled at the extremities
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of the bearing assemblies.
The compressor and turbine shaft is
machined smooth at these extremities.
This machining enables a
specified
clea~n
surface.
The oil seals are designed with double rows of packing with
an annular space
ce to be established between the seals and the shaft between~them
into which pressured sealing air is
admitted to prevent the lube oil from spreading along the shaft.
The-
air that returns to the oil tank, with the drain oil, is vented to atmosphere. The oil seal ring, is a shaft riding type which functions as a miniature bearing in controlling the amount of the thrust bearing oil spreading along the shaft. EXHAUST SECTION GENERAL The gas turbine combustion gases are discharged into the exhaust plenum where they are diffused and exhausted through a stack to at mosphere, or to other accessory equipment, depending upon the gas turbine application. i..-l , ..-l
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The exhaust plenum is bolted to the
end of the turbine com
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partment and is mounted on the aft end of the turbine base. The
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plenum, lined with sound absorbent material, encloses the exhaust
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fra,me, gas diffuser, and turning vanes. The exhaust £rame is bolted to, and supported by, the aft flange of the turbine shell.
The frame supports the No. 2 bearing assembly
and the gas diffuser and turning vanes.
The frame
isolated from
the plenum by segmented expansion ,joints installed between, the plenum and the exhaust frame support ring, and between the plenum and rear of the inner drum of the turning vane fabrication.
The expansion
joints permit growth due to thermal conditions in both radial and longitudinal directions. When exhaust silencing is used, the rectangular duct silencing assembly
bolted to the exhaust plenum.
The assembly contains
several flow splitters, which are made up of acoustic panels, for sound attenuation.
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ENCLOSURES G~NERAL
The enclosures used with a gas turbine package are built for all-weather conditions, and are designed to simplify maintenance and provide thermal and acoustical insulation.
They are heated and
lighted for convenience and for optimum performance of the installed equipment.
Enclosures consist of frames, panels, doors, and a
thermally insulated roof section, with welded frame structures pro viding the support for these parts.
The hinged panels are thermally
insulated and secured by bolts, the doors are held closed by latches. Gaskets between these parts and the frame maintain a weather-tight condition.
The hinged side panels of the turbine enclosure allow
easy access for inspection and maintenance. ACCESSORY AND TURBINE COMPARTMENTS These compartments are ventilated by a vaneaxial duct type fan mounted in the base transverse I-beam, in a position below the turbine compartment and aft of the inlet plenum.
Ventilating fan
motor (88BA) is started when the gas turbine fires, and continues to run after turbine shutdown to remove residual turbine heat.
The
fan shuts off when accessory compartment temperature drops to a level that causes the heaters to start up.
Air is drawn into the
accessory compartment (by the ventilating fan)
through three ducts
in the accessory compartment roof, two at the forward end and one at the aft end on the left side.
This air is forced into the
turbine compartment by the ventilating fan and then exits through two ducts in the aft portion of the turbine compartment roof. Heaters located in the accessory and turbine compartments maintain minimum temperatures of SO°F and 20°F respectively.
The
two heaters in each compartment are mounted on the forward bulkheads and are regulated by a thermostat (26HA) in the accessory compart ment and a temperature controller (26HT) in the turbine compartment. 1-12
In the event
excessive temperature in the turbine compartment,
the temperature controller (26BA) will sound an alarm. Turbine installations with CO certain additional safeguards.
fire protection systems require 2 The ventilation openings are fi tted
with CO 2 latch operated dampers. When the CO system is a.ctivated, 2 the latches release, allowing the dampers to close by gravity, thus preventing the escape of CO , 2 LOAD GEAR/GENERATOR COMPARTMENT The load gear area and the generator area are separated by a partial partition (across the top of the compartment) with a nor mally open CO
operated door in the center. The frontal area of the 2 generator effectively seals off the balance of the compartment's gross section.
This partitioning is done so as to provide a seal
able area for the load gear for effective CO
2
utilization.
Ambient air enters the generator package at the collector end through a protected opening in the roof.
This air passes through
filters and is drawn through to the plenum chamber in the base, and into the generator fans.
Air is forced by the fans into the air gap,
and around behind the stator core. After the air has passed through the generator, it picks up additional heat from the reduction gear casing and from the gas turbine exhaust plenum.
It is then discharged from the generator
package through exhaust louvres below the enclosure roof and directed upward through outlet silencers to atmosphere. When the generator operating temperature is below minimum the air is recirculated back into the plenum chamber in the base.
A
controlled damper monitors this function. GENERATOR AUXILIARIES COMPARTMENT The generator auxiliaries compartment is a base mounted, walk in, weatherproof, metal enclosure, which provides space for the generator excitation system, generator circuit breaker, potential
and current transformers, compartment heating and
venti1~tion
systems,
and electrical connections. Natural air convection is used for
~enti1ating o
the enclosure so
the inside temperature is no more than 10 C above the external temperature when the gas turbine-generator is loaded.
All ventila
tion louvers are of a filtering type which exclude fine wind-driven snow and sand. The compartment is
provided with electric space heaters to
prevent condensation of moisture from the air when the gas turbine generator unit is not operating.
Lights are provided to allow in
spection and maintenance of the equipment. CONTROL COMPARTMENT When a control compartment is supplied (packaged power plants only), it is similar in construction to the other compartments of the turbine.
Ventilation for this compartment is provided for by
an air conditioning unit.
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HYDRAULIC SUPPLY SYSTEM GENERAL The hydraulic supply system is comprised of two separate supply systems whose only common point is the gas turbine's lube oil system which is a supply source for hydraulic fluid.
One system supplies
high pressure fluid to operate the hydraulic ratchet (rotary actuator) M
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and starting clutch.
The other system is used to supply high pressure
fluid for operating the actuator on the variable inlet guide vane control ring.
The two systems are shown in the Hydraulic Supply
Schematic Piping Diagram. HYDRAULIC RATCHET SYSTEM The ratchet system consists of a custom-designed rotary actuator, ratchet/clutch control valve subassembly, ratchet/clutch pump assembly, and starting clutch.
Its purpose is to rotate the gas turbine rotor
during startup, cooldown, and maintenance inspection.
During startup,
it is used as a breakaway device to reduce the power requirements of the starting device.
During cooldown, the ratchet turns the turbine
rotor at specified cycles to prevent bowing of the turbine rotor and protect the turbine bearings from thermal damage.
When the rotor has
to be turned for inspection and maintenance, the ratchet sequence is actuated by means of, a jogging pushbutton. The rotary actuator (ratchet) is a component of the torque converter and starting device.
~ear
assembly for the turbine's starting
The actuator is connected to the shaft of the starting gear
by one-way ratchet clutch.
The actuator consists of two rack
assemblies with double-ended, hydraulic cylinders. the outer race of the ratchet clutch.
These racks engage
The ratchet clutch is a caged
roller-type over-running device which slides on rotation in one direction and locks in the other. As shown in the piping diagram, the actuator is interconnected by tubing to the ratchet/clutch control valve subassembly_
The
subassembly consists of the following main components: 1. Sequence Valve (VPR-6) - This valve maintains the proper
hydraulic pressure from the ratchet/clutch pump assembly
for reliable actuation of the starting jaw clutch.
CAUTION Maladjustment in the pressure setting of this valve can result in damage to the jaw clutch mechanism.
Refer to the Schematic Piping
Drawing - Device Summary for the correct setting.
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2. Pressure relief valve (VR-6) - This valve is used to relieve any over-pressure of the ratchet/clutch pump output.
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3. Starting clutch solenoid valve (20CS) - This valve is a three-way solenoid device which is
energiz~d
to engage the
starting clutch. 4. Ratchet stroke solenoid valv~ (20HR) - When energized, this four-way valve actuates the power stroke in the rotary actuator and, when de-energized,
rese~s
the stroke.
5. Limit switch (33HR)- This switch ,is a single pole, double break, double throw device which controls the power supply to actuate the ratchet stroke solenoid valve (20HR).
The
switch is operated by a hydraulic cylinder. 6. Hydraulic actuating cylinder for limit switch - This double acting cylinder is operated by oiJk ported off the cylinders of the rotary actuator at the extreme end,. of-the strokes. Its rod is connected to the limit switch. 7. Pressure switch (63HR) - This switch is installed in the subassembly tubing downstream of the 20HR solenoid valve. It senses oil pressure at the power side of the rotary actuator and resets the alarm timer.
Failure to sense this
pressure and reset the timer, actuates an alarm in the annunciator panel.
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8. Starting clutch check valve - This valve is installed upstream of the 20CS starting clutch solenoid valve and is used as added protection for the starting clutch in the event the VPR-6 sequence valve fails. Operating oil pressure for the hydraulic ratchet system is maintained by the ratchet/clutch pump assembly.
This is mounted on the
turbine base under the accessory gear pedestal and is driven by a dc motor (88HR).
The pump takes its supply from the turbine's
main lube oil header.
The ratchet system cannot operate without
the lube oil system pressure first becoming established.
A pressure
relief valve (VR-3), built into the pump, is bypassed by the VR-6 relief valve. STARTING CLUTCH ASSEMBLY The starting clutch assembly is mounted on the outboard end of the main accessory gear shaft inside the coupling guard.
The clutch
is used to connect the starting equipment to the gas turbine.
The
clutch is comprised of a stationary jaw clutch hub, keyed to the accessory gear shaft, and a sliding jaw clutch hub, which slides on the splined end of the starting device shaft.
Two parallel,
horizontally~
oriented, hydraulic cylinders are actuated by the starting clutch solenoid valve,
(20CS) and move the sliding clutch hub into engagement
with the stationary clutch hub.
When the gas turbine reaches a pre
determined speed, the solenoid valve (20CS) is de-energized by the l4HR speed relay and dumps the hydraulic oil to drain. When the gas turbine reaches self-sustaining speed, the torque at the driving jaws then reverses·.
As a result, the sliding clutch
hub is forced out of engagement by the force of internal springs and the gradual slope of the back side of the clutch jaws.
The sliding
clutch hub is held in its disengaged position by the internal springs. HYDRAULIC RATCHET SYSTEM OPERATION The rotary actuator (ratchet) cannot turn the gas turbine rotor unless the starting clutch is engaged.
Engagement is maintained
through the circuitry of the hydraulic ratchet system when the turbine is in the startup mode.
The starting clutch. can be disengaged manually
by operating the rotary actuator while the starting clutch solenoid valve (20CS) is
~e-energized.
The operation of the hydraulic ratchet system is electrically controlled by signals from the turbine electric control panel.
Its
function as a breakaway device is controlled by the starting circuits of the gas turbine; as a cooldown device, its operation is controlled by the stop and cooldown circuits; and as a jogging device, its operation is controlled by a jog switch (43HR) which usually is located
g
at some convenient point where the turbine shaft can be seen.
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When operating as a breakaway device during turbine startup ) and after lube oil pressure has been established, the ratchet system is put into continuous operation by the turbine control circuitry until the zero-speed realy (14HR) drops out. w~en
the ratchet pump motor is energized, the tW~_~.9.1s;n9i~'!..C!lNes l~ and'-'20HRr~'i)c:irt oiito thecylind~rs of the st~~-ting clutch and -
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the power stroke side of the rotary actuator.
After starting clutch
engagement, the ratchet (rotary actuator) turns the turbine rotor approximately 45 degrees during the power stroke. At the end of the power stroke, a piston ring in the ratchet actuating cylinder uncovers a port to pressurize the actuating cylinder for the limit switch (33HR).
Stroking of this cylinder
causes the limit switch to de-energize the 20HR solenoid valve via the turbine control system.
This, in turn, causes the actuating
cylinder to move in a reset str.oke. At the end of this reset stroke, a piston ring in the ratchet cylinder uncovers another port to reset the 33HR limit switch acutating cylinder.
This action resets the limit switch, causing
the control system to energize the 20BR solenoid valve for the next power stroke.
The cycling of the ratchet system continues until the
zero-speed relay (14HR) drops out.
This, in turn, de-energizes the
ratchet pump motor (SSHR), ratchet stroke solenoid valve (20HR), and starting clutch solenoid valve (20CS) to secure the ratchet
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circuit.
The rotary actuator (ratchet) clutch over-runs continuously
as the starting means operates. When the ratchet system is used as a cooldown device, the operation is similar to that during startup breakaway except that the 20HR solenoid valve is actuated only once every three minutes by the 2HR timer in the turbine control panel.
Each stroke of the ratchet
turns the turbine rotor about 45 degrees (1/8 revolution).
With a
three-minute setting of the cycling timer, the rotor is turned approximately two and one-half revolutions per hour. When the hydraulic ratchet is used as a jogging device, the stroking is controlled manually by the operator by means of a "jog" control switch (43HR).
Under manual control, the stroke will stop
at any point in its travel by releasing the jog switch.
Upon return
to automatic control, as in its function as a cooldown or breakaway device, the jogging stroke will reset to the
r~atraced
position,
and normal stroking will resume as cycled by the 33HR limit switch. VARIABLE INLET GUIDE VANE ACTUATING SYSTEM In order to prevent possible pulsation in the gas turbine during acceleration and deceleration, variable inlet guide vanes are installed in the aft end of the turbine's inlet casing. vanes, in conjunction with control
o~
The variable
the tenth-stage compressor
bleed air (see Air Systems), permit rapid and smooth turbine starts and shutdowns without compressor surge. The variable inlet guide vane actuating system is comprised of the main hydraulic pump, hydraulic manifold assembly ~Ji'h1o:~Julic oil filter, low hydraulic pressure alarm switch (63HQ), inlet guide vane solenoid valve (20TV), guide vane actuator control valve (FCV-l), limit switch (33TV) and hydraulic actuating cylinder. The main hydraulic supply pump is driven directly off of the accessory gear and pumps oil from the lube oil system to the hydraulic supply manifold.
The manifold controls the flow,
and regulates the pressure of the hydraulic fluid.
( to sump or to line) fhe output of
the manifold is fed through a filter and channeled to the inlet guide vane solenoid valve (20TV).
Actuation of the 20TV valve supplies
hydraulic pressure to operate the variable inlet guide vane actuator. The speed of the
~ctuator
is governed by temperature and pressure
compensated flow control valve (FCV-I).
When the 20TV valve is
energized, the guide vanes are opened to permit maximum air flow through the turbine compressor.
When the valve is de-energized,
the vanes are closed and the air flow through the turbine is
minimized~
The rotable shaft of each individual inlet guide vane extends through the compressor casing and is geared to a circumferential inlet guide vane control ring on the compressor.
Rotation of this
control ring varies the chord angle of each individual inlet guide vane in the compressor.
Thus, the inlet air flow of the turbine
changes asa function of the inlet guide vane angle position.
A
linear electro-hydraulic actuator is connected to the control ring through a connecting link. The startup and shutdown iogic sequence control requires that the inlet guide vane control ring be at the closed position before the turbine is fired and remain in this closed position until the turbine is at speed.
The pickup of the high-speed realy (14HS)
energizes the turbine compressor inlet guide vane solenoid valve (20TV) which actuates a hydraulic cylinder to open the vanes to their normal operating position for loading.
Similarly, the shutdown and
trip logic sequence requires that the inlet guide vanes be returned to their closed position when the turbine is tripped and when the 14HS relay drops out in the decelerating cycle.
A limit switch (33TV)
on the inlet guide vane control ring to indicate turbine control panel when the guide vanes are in a closed position. Thus, the inlet guide vanes are operated with the same permissive sequence as the tenth-stage compressor bleed valves, which are also reuqired for pulsation protection of the turbine. CAUTION ,,,"
Under no circums:tances should the turbine be started if the inlet guide vanes are
t.
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not in the closed position before firing. Similarly, the inlet guide vanes must be in their closed position before the turbine decelerates to or below the speed specified in the Control Specification.
NOTE For detailed information pertaining to the installation, maintenance and operation of the equipment described in this section, refer to the Equipment Publications section of this manual. Refer to the Control Specifications Control System Settings and Operating Sequences for the specified settings of the inlet guide vane position and the limit switches. 0'1
I
For the electrical
control circuitry and logic sequence of
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the hydraulic supply system, refer to
l.()
the Turbine Elementary Diagram.
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COOLING SYSTEM GENERAL The cooling system is a pressurized (closed} system which has been designed to accommodate the heat-dissipation
require~ents
of
the lube oil system, the atomizing air system, and the starting diesel engine.
Included in the system is the coolant cooling module
which is located above the accessory compartment, the shaft-driven water pump, valves, and miscellaneous control and protective devices. Refer to the typical cooling system schematic attached. COOLANT COOLING MODULE The coolant cooling module is a fabricated assembly which is installed above the accessory compartment. with interconnecting piping.
It contains two tanks
A liquid level gage and low level
alarm switch (7lWL) is installed in tank number 2.
The liquid level
gage can be read from the inside of the accessory compartment. o
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III
Pressurization of the tanks from an external source is not required to assure proper operation of the water system.
This
system, which h.as a 13 psig pressure cap on the fill connection, normally operates at a slight positive pressure.
This occurs when
the liquid in the system expands with the increase in temperature during turbine operation.
A vacuum valve is also built in as part
of the pressure cap to relieve the vacuum should the pressure of theosystem drop below atmospheric pressure as the coolant cools. The module is divided into three sections which serve as plenums for the six fans which are driven in tandem by electric motors (88FC-l, 2 and 3).
The finned tube heat exchangers are
installed in the sidewalls of the module. The coolant from the tanks is circulated through the lube oil and atomizing air heat exchangers to pick up the heat rejection of these systems.
The coolant then circulates through the coolant
air heat exchangers where it is cooled by the air which is induced
through the coolant-to-air heat exchangers and out the roof by the fans.
The cooled coolant is then returned to the tanks.
The
interconnecting piping between the finned tube heat exchangers and the tanks is self-contained in the module. The power plant has been designed to operate normally with both finned tube heat exchangers in operation.
However, within
certain limitations, operation of the power plant is permissible on one heat exchanger while the other heat exchanger is shut off for maintenance. The coolant cooling module is designed for year round operation using 52% mixture of ethylene glycol by volume for protection to -40 F.
The maximum ambient temperature of 105 F is the limitation
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of the capability of the system with low pressure atomizing air.
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COOLANT PUMP During turbine operation, the coolant is circulated by the centrifugal pump which is driven off one of the shafts of the accessory gear.
This pwnp utilizes pump discharge coolant for
cooling the mechanical shaft seal.
The seal coolant is cleaned by
a centrifuging-type abrasives separator. SHUT-OFF VALVES Shut-off valves are provided in the piping so that the diesel engine, the coolant side of the lube oil cooler, and each coolant-to air heat exchanger may be isolated for maintenance.
For equipment
protection, no shut-off valves are provided in the suction or discharge piping of the pump.
If this pump requires maintenance, it
will be necessary to drain the coolant from the system. PRESSURE AND FLOW REGULATING VALVES The coolant circuit for the lube oil cooler has a temperature actuated valve (VTR-l) installed in the coolant intake line to the oil cooler.
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This valve, which controls coolant flow, has a manually
operated device which can override the thermal element.
This manual
override device should be used only when the valves thermal element is inoperative, but machine operation is required. Lube oil feed header temperature is sensed by the valve (VTR-l) which controls the flow of coolant through the cooler to maintain the lube oil temperature at a predetermined value.
This regulator
automatically controls flow of the medium passing through its valve by responding to temperature changes affecting the bulb.
The bulb
contains a thermo-sensitive liquid which vaporizes when heated. Pressure thus generated in the bulb is transmitted through the capillary tube to the bellows which positions the valve plug to control the flow of coolant through the lube oil cooler and the valve. valve VTR-l is closed during turbine startup when the oil is cool and the total output from the pump flows through a loop which bypasses the cooler.
It will start to open as the sensed oil temperature
approaches the control setting.
Coolant flow is then through both
the cooler and bypass loop in varying quantities until, at some high ambient temperature, VTR-l is fully open.
With VTR-l fully
open, the flow through the cooler and bypass loop will become constant, and if the ambient temperature increases further, the N
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lube oil header temperature will increase above the control setting of VTR-l • The coolant circuit for the atomizing air cooler has a temperature actuated valve VTR-2 installed in the atomizing air system.
The operation of this valve is analogous to that of VTR-l
described above except that the bulb of the valves thermal system senses atomizing air temperature.
Valve VTR-2 has a small bypass
orifice drilled into the valve body to assure that the pre-cooler is "flooded" at all times. Pressure regulating valves VPR-7 and VPR-8, which are located in the diesel engine coolant piping, are used to prevent over pressurization of the diesel engine cooling system. ANTIFREEZE AND RUST INHIBITOR During cold weather, there is danger that coolant will freeze
and gamage the component parts of the cooling system.
To protect
against possible freezing of the coolant, it is necessary to use a commercial type antifreeze solution in the system. When antifreeze is used, its manufacturer should be consulted for recommendations regarding length of time between changeouts, the need for corrosion-inhibitor additives, the dangers involved in adding antifreeze to an existing coolant, and other precautions.
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COOLING AND SEALING AIR SYSTEM The cooling and sealing air system is comprised of air actuated compressor bleed valves, a solenoid actuated air control valve, an air filter and various fittings, piping, and internal passageways. In operation, cooling and sealing air is developed at three locations; the fourth compressor stage, the tenth compressor stage,
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and the compressor discharge.
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Tenth stage air is piped externally through bleed valves to the
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exhaust plenum.
Z
zle vanes to cool the vanes, the aft surface of the first stage wheel
I
This air is also fed through the second stage noz
rim, and the forward surface of the second stage wheel rim, a portion of the tenth stage air is used at the #1 and #2 bearing assemblies to provide an air pressure seal for bearing lube oil. On certain machines, fourth stage air is also piped externally through bleed valves to the exhaust plenum. this
On all machines, however,
air is also piped both directly and through the turbine shell
and support struts
to the aft surface of the second stage wheel.
This air cools the portion of the shell surrounding the first and second stage nozzles and wheels and also cools the support struts which are in the hot gas exhaust stream. Compressor discharge air is channeled internally to the forward surface of the first stage wheel and through the blades of the first stage nozzle.
This air is also piped externally through a filter
and air control valve (20CB) to the actuating pistons of the bleeQ valves. At turbine startup (and at speeds below 85%) valve (20CB) vents the discharge air to atmosphere, the bleed valves are open, and tenth-stage air (or fourth and tenth-stage air) is vented to the exhaust plenum (an aid in the elimination of compressor surge). When the turbine exceeds 85% speed, a signal from the control sys tem actuated valve (20CB).
Compr,essor discharge air is then routed
to the bleed valve actuators to close the valves and stop compressor bleed to the exhaust plenum. Those gas turbines which burn oil as a fuel, will utilize compressor discharge air to activate the control piston of the false start drain valve in the fuel oil system.
Applications
which require atomizing of the fuel oil use compressor discharge air as the source of air for atomization.
Atomized air operates
the control piston of the false start drain valve.
5
/-~"p.
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6-2
STARTING EQUIPMENT STARTING SYSTEM - 500 HP DETROIT DIESEL ENGINE The diesel starting system is comprised of the following equipment and sub-systems: (1)
diesel engine (a) (b) (c) (d) (e)
C\ M
air supply system exhaust system fuel syst.em water system throttle system
(2)
torque converter (a) converter oil system
(3)
diesel starter, 88DS
(4)
tachometer and generator
(5)
solenoids 20DT, 20DV and (valve) 20DA
(6)
pressure switches 63DM and 63QD
(7)
relief valve VR-13
DESCRIPTION
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The diesel is a 12 cylinder, 2 cycle engine with a speed rating of 2300 RPM.
The engine draws air from the accessory compartment
through two filters to the engine intakes.
The intake housings are
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equipped with dampers operated by solenoid 20DT to admit or stop air flow to the engine. exhaust stack.
Exhaust gases are piped to the turbine
Overboard drains are provided to bleed condensation
from turbine exhaust gases
ove~oard
to avoid injecting water into
the engine. The diesel fuel tank is built into the turbine base so that the engine may be operated
without the fuel forwarding system
running--refilling the base tank is a manual operation.
A high
lift pump, driven by one of the cam shafts, pumps fuel from the base tank to a small cannister mounted on the side of the engine. An overflow drain allows excess fuel to return to the tank.
The
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main fuel pump draws fuel from the cannister through a strainer, and pumps it through a filter to the fuel headers.
The fuel in
jectors draw fuel from the headers as required and excess flow (used to cool the injectors) is returned to the cannister. The engine draws coolant from the unit water system.
A pump
on the engine pumps water through the oil coolers and the water jacket to the thermostat housings.
Until the engine reaches
normal operating temperature, the thermostats route the water through a recirculation line to the pump inlet.
At normal
temperature, the thermostats route the water back to the unit system.
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The engine is equipped with a mechanical speed limiting ,governor and a two position throttle operator controlled by
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solenoid valve 20DA.
with 20DA deenergized the engine runs at
idle speed. When 20DA is ener9ized, the valve ports oil to operate the throttle cylinder for full power. A small pump driven from a cam shaft supplies oil for cylinder operation and at the end of the cylinder stroke, the oil flow returns to the engine pan over relief valve VR-13.
When the throttle is in the full
power position, the engine speed is limited by the governor. When the engine is "tripped" with the throttle in the full power position, the throttle does NOT reset - the next engine start will be made with the throttle full open. While this is an acceptable mode of starting, it is not recommended for indiscriminate use. The engine drives a torque converter that is arranged to drain back to the unit lube tank on shut-down. The engine is started with the converter empty (no load). A converter charge pump driven by an engine cam shaft supplies lube oil to fill and pressurize the converter loop--until the loop is pressurized, the converter cannot absorb or transmit power.
Loop pressure
is controlled by an orifice on the converter discharge.
The
charge pump draws oil from the unit tank and the suction line is primed through a check valve from the start-up lube pump.
7-2
o
The charge pump is protected from excessive priming pressure by a relief valve back to the tank.
The converter used with this
engine is a constant input power device--the input power to the pressurized converter is only a function of input speed and does not vary with gas turbine speed.
Even with the starting clutch
disengaged, the converter draws design horsepower at design input RPM. OPERATION For engine start-up, 33CS must be picked-up and 20DT and 20DV must be energized before the diesel starter, 88DS, can be energized.
When the engine starts, 63DM is picked up by engine
fuel pressure to secure 88DS.
When the engine lube pressure picks
up 63QD, 20DA is energized to accelerate the diesel to full speed. Converter output breaks away the unit (with help from the ratchet) and accelerates the unit to firing speed which is "load governed" by the unfired unit--crank speed is not adjustable*.
After the
unit is fired, the converter output continues to supply starting power until the unit becomes self-sustaining.
At self-sustaining
speed, the converter output is zero and the starting clutch automatically opens and drops out 33CS which deenergizes 20DA. The engine returns to idle speed for a timed cooldown cycle and is then secured by deenergizing 20DV and 20DT. In the event of any malfunction, the engine is automatically secured by deenergizing 20DA, 20DV and 20DT. *On some units, a 20TV valve is supplied to limit crank speed by delaying the the converter.
p~wer
absorption of
This system is used only to ~
enhance firing reliability.
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------------------------------------
.. ----.-~--..
..
AIR INLET EQUIPMENT The air supply for the turbine flows through a duct assembly prior to entering the compressor.
The duct assembly contains an air
silencer and a trash screen. The air silencer, consisting of a number of acoustical panels, forms a section of the duct assembly and attentuates the high fre quency sounds created by the compressor blading.
The trash screen
prevents the entrance of foreign objects into the compressor. Installations which have an inlet house arrangement may have filters or evaporative coolers (humidifiers) installed in the inlet house.
The equipment used depends on the site conditions.
The in
let house is always installed upstream of the air silencer. The construction of the inlet house is such that the side panel openings will permit the installation of either filters, screens or evaporative coolers.
The inlet air duct assembly is bolted to an
opening in the inlet house. provided in the inlet house.
A screened pressure relief door is The air flow entering through the door
bypasses the inlet filters, screens, and evaporative coolers (if used).
The opening of the relief door is actuated by a pressure
drop (approximately 2 inches of water) across the filters, screens, or coolers.
The common cause of a pressure drop is fouled filters
and icing.
For ease of service and maintenance, a door is provided
in the inlet house.
GEARS ACCESSORY GEAR ASSEMBLY The accessory gear assembly is a gear box coupled directly to the turbine rotor and is used to drive the turbine-driven accessory devcies.
The accessory gear, located at the aft end of the accessory
compartment, contains the gear trains necessary to provide the proper gear reductions to drive the accessory devices at required speed with the correct torque values. Mounted on the exterior of the casing is the turbine overspeed trip which can mechanically dump the oil in the trip circuit, shutting down the gas turbine unit when the speed of the first stage turbine exceeds the limit as prescribed in the Control Specifications.
The
overspeed bolt which actuates the trip upon overspeed, is installed in the main shaft. During startup, the acCessory gear transmits torque from the· starting device to the gas turbine.
The gear is lubricated from
the pressurized bearing header supply and drains by gravity to the lube oil reservoir. The gear casing is split at the horizontal plane into an upper and lower section for maintenance and inspection purposes.
Inter
connected shafts are arranged in a parallel axis in the lower casing. with the exception of the lube oil pump shaft, all the shaft center lines are located on the horizontal joint of the casing. The starting clutch assembly is located at the outboard end of the main accessory gear shaft.
It is set on the horizontal joint
of the casing and is used to connect the starting device to the gas turbine rotor.
The clutch is automatically disengaged when the gas
turbine has reached self-sustaining speed and the starting device shuts down.
Additional descriptive information on the clutch is
presented in this section under Hydraulic Supply System. The main lubricating oil pump is located on the inboard wall of
the lower-half casing. the lower drive gear.
It is driven by a splined quill shaft from The pump consists of two steel gears which
run in a figure a-shaped cavity in the wall of the accessory drive gear casing.
The pump suction and discharge passages are cored.to
openings on the bottom surface of the casing.
The pump gears are
contained in babbitt-lined cast-iron bushings which are located at r-~
the ends of the pump cavity. LOAD GEAR The load gear is a speed-reducing device which couples the gen erator rotor to the turbine. support at this location.
It serves as the main generator
The turbine rotor is connected to the
load gear pinion by a flexible coupling.
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Lubrication of the gear
C l
is accomplished with oil from the lube oil system.
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NOTE For additional information pertaining to the maintenance and operation of the accessory gear, refer to Gears in the Equipment Publications section of this volume.
Refer to Generator
Data for information on the load gear.
..~.
COUPLINGS GENERAL The basic functions of the flexible gear-type couplings used on this turbine are to:
(a) connect two rotating shafts in order
to transmit torque from one to the other,
(b) compensate for all
three types of misalignment (parallel, angular, and a combination of both), and (c) compensate for any axial movement of the shafts so that neither exerts an excessive thrust on the other. Parallel misalignment is when the two connected shafts are parallel, but not in the same alignment.
Angular misalignment
occurs when the centerlines of two shafts intersect.
Combined
misalignment occurs when the shafts are neither parallel nor in alignment.
Axial movement is when one or both shafts are displaced
along their axis (centerline). The couplings used on this turbine are to connect the accessory drive gear with the turbine shaft and the turbine shaft with the load equipment. ACCESSORY GEAR COUPLING This coupling is a continuously lubricated, flexible gear-type device.
It employs a hub of male teeth fitted at each end of a
distance piece.
The teeth mesh with the female ones of a sleeve at
each end to transmit torque.
The male teeth are crowned and can
slide fore and aft within the female spline. three types of misalignment.
This allows for all
The sleeve at the accessory gear end
is bolted to a flange (hub) which has been shrink-fitted to the accessory gear shaft.
The sleeve at the turbine end is bolted
directly to the turbine shaft. LOAD COUPLING This coupling is also a continuously lubricated flexible, gear type coupling.
With the same general design as the accessory gear
coupling. piece.
However, the male teeth are machined into the distance
The sleeves are bolted directly into the flange of the
turbine shaft and the load equipment shaft. LUBRICATION Whenever gear-type flexible couplings are used, lubrication is a major contributor to their longevity.
In the continuous lubri
cation-type coupling, lube oil from the turbine's bearing header is discharged coupling.
through nozzles into an annular groove in the
The oil then flows through holes drilled in the coupling
and then through the teeth and over the snap-ring oil retainer. It is important that the oil is discharged into the groove and not the teeth since the correct operation will result in a con tinuous flushing action through the teeth.
The oil is then caught
by the coupling guards and returned to the lube oil tank in the turbine base. TOOTHWEAR During the initial operation period of gear-type couplings, minor imperfections will be smoothed out and the working surfaces will take on a polished appearance.
Under continued normal con
ditions of operation, the rate of wear will be small. Tooth-wear-pattern can provide maintnenace information calling for action.
An abnormally wide wear pattern in the axial direction
is indicative of excessive running misalignment.
The greater the
misalignment the greater the wear rate, since the number of teeth in contact decreases with increasing angularity. Abrasive wear, characterized by short scratch-like lines or marks on the surface of the teeth, indicates that the lube system is not clean and oil is carrying particles into the coupling teeth. Corrosive wear
indicative of lubricant contamination or
highly active additives.
Surface fatigue, characterized by the
removal of metal and the formation of cavities, may indicate tor sional oscillations in the coupled system.
STATION AUXILIARIES AND SERVICES PACKAGE POWER PLANT LIGHTING Lighting and convenience outlets (ac) as well as emergency and dc lighting circuits are provided in the various compartments along with a provision for the addition of outdoor lighting circuits. Available circuits are shown on the One Line Diagram included in the Reference Drawings Section of this
boo~
and on the Motor Control
Center elementaries which are furnished to the purchasers of General Electric Co. Gas Turbines. BATTERY AND CHARGER In Order to provide the dc power necessary for control pur poses and emergency conditions, the power plant is equipped with a battery and a battery charger.
The battery charger is powered
from an ac bus, and therefore, ac power is required during stand by periods to maintain the battery at full charge.
The battery
and battery charger are located in the control package. M t.rl
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WARNING
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~
To avoid electrical shock, all personnel should be cautioned about the exposed termi nals of the battery.
When servicing the
cells do not allow battery acid to come in contact with the skin or clothing. FIRE INDICATION Both power block and package units have the same type of system to indicate fire and/or CO
system activation. The only 2 difference being the location of the annunciator. The power block has the annunciator located in the control house and the package power unit has the annunciator located in the control compartment. In either case, the alarm is located in the accessory compartment.
8-7
)
CO 2 FIRE EXTINGUISHING SYSTEM GENERAL The carbon dioxide (C0 2 ) fire extinguishing system extinguishes fire by reducing the oxygen content of the air in the compartment from an atmospheric normal of 21 percent to less than 15 percent, (an insufficient concentration to support combustion).
The CO
is 2 supplied from a group of high pressure cylinders to a distribution system which conducts the CO 2 through pipes to discharge nozzles located in the various compartments of the gas turbine package. The release mechanism which opens the CO 2 cylinders and initiates the discharge of CO 2 is located at the cylinder group. This mechanism is automatically actuated by an electrical signal from the heat sensitive fire detectors which are strategically located in the various compartments of the unit.
The system may
also be manually actuated in the event of an electric power failure. Actuation of the CO trip the turbine.
system, either electrically or manually, will 2 Two separate systems are used; initial discharge
and extended discharge.
Within a few seconds after actuation,
sufficient CO 2 is piped from the initial discharge system into the compartments of the machine to rapidly build up an extinguishing concentration.
This concentration is maintained for a prolonged
period of time by the gradual addition of more CO
2
from the ex
tended discharge system. If the CO
system is to be effective, the compartment panels 2 must be in place and the compartment doors closed. There is suffi cient CO
2
in the system to compensate for leakage through ventilation
openings and unavoidable cracks in the package lagging, but there is not enough to allow for uncontrolled escape of CO panels or doors.
WARNING CO
2
in a concentration sufficient to ex
8-8
2
through open
tinguish fire, creates an atmosphere that will not support Ii
It is extremely
hazardous to enter the compartments after the CO
system has been discharged. Any 2 one rendered unconscious by CO should be 2 rescued as quickly as possible and revived immediately with artificial respiration. The extent and type of sa
guards and
sonnel warnings that may be necessary must be designed to meet the particular re quirements of each situation.
It is
recommended that personnel be adequately trained as to the proper action to take in case of such an emergency. PACKAGE POWER PLANT Should a
re occur in one of the compartments of a Package
Power Plant, one of the £ire detectors (heat sensitive electrical U'") U'")
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switches) will close its contacts and complete the electrical circuit to energize a Derby Release (45CR). When the Derby Release is energized, weighted arms on the two weighted head cylinders will drop to open the valves on these two cylinders and start the discharge of liquid CO into the cylinder mani
2
(at a normal pressure of 750 psia)
Id and piping system.
The pressure devel
oped in the manifold by CO
from the weighted head cylinders will 2 open the valves on the pressure operated cylinders and permit them also to discharge into the manifold and piping system. The system is provided with two identical sets of CO cylinders.
2
storage
One set, considered the main set, will provide pro
tection for any unit in a Power Block. The second set of cylinders is a back-up set which will also provide protect£on for any unit in a Power Block when the first set is discharged or being re A manual selector switch (43CR) which is located next to the CO
lIed.
2 storage cylinders, selects the set of cylinders to be in service.
8-9
The CO
flow rate from the cylinders is controlled by the 2 orifices in the discharge nozzles of the initial and extended discharge system.
The nozzles are installed in each of the com
partments of the unit.
The size of the orifices in the initial
discharge nozzles will permit a rapid discharge of CO initial discharge cylinders to quickly build
from the 2 up an extinguishing
concentration. The orifices in the extended discharge nozzles are smaller and will permit a relatively slow discharge rate from the extended discharge cylinders in order to maintain tration over a prolonged period of time.
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extinguishing concen
ro
l-
By maintaining the ex
re: I
tinguishing concentraiton, the likelihood of a fire reigniting is
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minimized.
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8-10
ATOMIZING AIR 'iYR'PEM OISTILLATE 01 fJ Ftm L
A "low-pressure" atomizing air system is furnished with gas turbines which burn distillate oil fuels.
t::'l~en
The atomizing air is
from the discharge of the turbine's axial-flow compressor and is v.....
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boosted to a pressure equal to approximately 1 1/2 times the
co~b
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ustion chamber pressure by a compressor mounted on, and driven by a
• r-
shaft in the turbine accessory gear.
co
shaft-driven compressor is delivered to the oil fuel nozzles in the
M 0 0
turbine combustion system.
I
In
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~
The atomizing air from t!1e
'l'he fuel nozzle!'> are designed such as
to produce a high velocity air jet concentric wi th the fuel stetu'! which results in breaking up the fuel into very small droplets that enhance rapid and complete combustion. tillate oil) machines,an
at(~izing
arrangement is incorporated.
air
On dual fuel (gas and dis by-~ass
and oil
nn7~le
pur~e
This Part of the atomizing ,'11 r s"<;U:P1
functions when the gas turbine is operating 100 percent on nas fuel.
At turbine startup, a starting atornizinq air system is required until the accessory gear driven compressor is at sufficient speed to furnish the required flow and pres.sure for fuel atomizing.
This
system is connected through a check valve, in parallel with the main system, to a manifold from.which the air is distributed to the oil fuel nozzles.
The atomizing air: system includes the followina items of equip roent:
(See the Schemat.ic Piping Diagrams - Atomizing Air)
1) Air cleaner (separator) 2) Atomizing air pre-cooler 3) Temperature switch 26AA.
Atomizing Air System equipment-(Cont'd)
,
4) Atomizing Air Compressor (main-accessory gear driven)
5) Differential Pressure Switch
6) Pulsation Snuboer
7) Atomizing Air Manifold
, I
8) Starting atomiztng air (booster) compressor/or blower Belt- driven units; units)
b~
diesel starting engine
motor-1riven~
for diesel start
in-line coupled for electric start
\
9) Relief valve VR-:12
10) Check valve (st~rting atomizing air system)
II} Unloading valve (diesel start units, only)
In operation, compreissoL discharge air is piped through the air
~
e~
cleaner to remove any dirt that may be picked up by the gas turbine axial-flow compressor.
r
The dirt is carried away by two air lines
and disposed of through the exhaust plenum.
The cleansed air is
piped through an air pre-cooler (air-to-water heat eKchanger) inlet of the main air compressor.
~
L
to the
(
C
~
The air temperature in the dis
charge line from the pre-cooler is monitored by
I
C
a temperature
c
,
switch 26M which actuates an alarm if the temperature rises above a present level.
Also, this air temperature is sensed by a temp
erature bulb of a temperature regulating valve VTR-2.
This valve
regulates the flow of cooling water through the pre-cooler to main tain a set of air temperature. System).
(See Description of Cooling Water
The cooled air enters the accessory gear driven air comp
ressor which boosts the pressure and discharges it through a snubber to the atomizing air manifold.
The snubber dampens
...;~
..
the pulsations created by the air compressor, and the manifold distributes the air evenly to the ten fuel nozzle assembl
s.
A
differential pressure switch (63AD) is installed across the inlet and discharge of the air compressor.
After the starting sequence is
completed, this switch Will operate an
annunciator alarm if the
pressure rise across the air compressor should drop to a point which would result in poor atomization of the fuel.
However, operation of
this switch will not shut down the turbine. . 0'\
icc
I
During startup, when the shaft-driven air compressor is not
I !...-! 10
delivering sufficient air for proper
:0
furnished by a blower (booster compressor) which is belt-driven by
to
I
atomizatio~1
Z
the die
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electric motor on electric start units.
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I~
atomizing air is
engine on diesel start units, and by a directly coupled
When the shaft-driven
compressor has reached sufficient speed in the startup sequence its output will be greater than the output of the starting air compressor and a check in the discharge line of the starting air system will close.
The discharge pressure of the starting air compressor is then
relieved through a relief valve which protects the compressor from pumping against a dead head and becoming overheated.
The reI
valve is set to relieve at the approximate point where the main system pressure overcomes the starting system pressure and closes the check valve. On diesel start units, an unloading valve is incorporated into the discharge piping of the starting air booster compressor to pro tect the compressor (which is belt-driven by the diesel engine)
from
pumping against a dead pressure head and becoming overheated during the diesel cooldown period when the engine is at idle speed.
The
unloading valve is a three-way, normally open, hydraulically operated The valve is closed by diesel lube oil pressure when the diesel is at operating speed, and opened (by a spring) when the diesel is at idle speed.
At idle speed, the discharge of the
starting air compressor is vented through the open unloading valve to atmosphere.
9
AMERclone (6" AMERclone Type tlGIt Tube Design 6 Assemblies) The AAFAMERclone is a high efficiency dry centrifugal dust collector . .
of the multiple cyclone type.
It is designed to carryon the
cle~ning
operation continuously with a minimum of maintenance. Air flow through this tube is different from any other higb-efficiency centrifugal collector.
Air enters tangentially through tbe inlet cone J
which has a speci'ally designed slot that maintains uniform distribution of the entering air.
This tangential air inlet provides the swirling motion
necessary to throw the dust particles to the outer
perim~ter
of. the tube.
Acceleration takes place in the cone, then remains constant from there to the bleed-off for the secondary circuit.· There is no increase in velocity and dust concentration.
The clean air travels out through the end of the
tube without changing direction, and 10% of the primary air circuit - plus the collected dust - is bled off and disposed of. Tube inspection should be made periodically for indication of wear and accumulations.
Accumulation of dust on the tubes will usually be an
indication of condensation taking place, especially when handling elevated temperatures.
Plugging of primary or secondary tubes will
the operating efficiency of the unit.
American Air Filter Co. umisville, Ky•
.~.
seriou~ly
affect
