Air & Flue Gases System

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1.0 MODULATING CONTROL

1.1 FORCED DRAFT FANS PRESSURE CONTROL

The F.D. fans pressure control loop is designed to maintain the pressure

downstream regenerative air heaters at the proper value feeding the combustion airheader in order to match primary (tempering to mill resuction duct), secondary (to

coal burners) and tertiary (additional air firing to AAF nozzles) air flow demand.

The combustion air pressure set point (bases on boiler demand) is compared via

high/low selecting logic to minimum and maximum pressure limits, then the

resulting valve is compared to header pressure value and through the controller sets

the demand for F.D. fans inlet control damper.

The operator has a biasing capability to shift the combustion air pressure set point

curve up or down of the established curve based on boiler test.

The F.D. fans damper position demand is actually the average demand for each of

the two fans; the operator can settle a bias in order to balance the incidental

mismatch between the two fans.

If one fan is on manual or forced, the fan on automatic compensates for the fan not

participating in the control.

Thus, the bias is continuously calculated when on or more fans are on hand.

When the last is released to control (auto mode and no for cement), the bias is

released to the operator at the value, if any, that is actually between the fans.

To determine the error between demand and the individual fan, the fan control vane

pitch position is compared to the individual fan biased demand; during normal

operation, the two are kept equal through a high reset proportional plus integral

controller.

In case a F.D. fan motor is off and the other F.D. fan is in service, the control

damper related to the fan not in service automatically closes.

Proper firing action are performed according to the request from Burners

Management System and Air & Flue Gases functional groups that force F.D. fans

control dampers at proper position, that are:

Fully open/closed to perform fan start/stop sequence

Fully open for natural draft requirement

1.2 REGENERATIVE AIR HEATER COLD END TEMPERATURE CONTROL

The regenerative air heater cold end temperature control is designed to maintain a

good relation between the combustion air and flue gases temperature to avoid the

last one falls below the dew point temperature, thus the acids in the flue gases

cannot be condensed and the extensive corrosion effect on heating surfaces of the

regenerative air heater will be reduced.

The above control loop is simple feedback control loop, based on the method to

raise the raise the air temperature at regenerative air heater inlet by means of steam


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coil air heater (S.C.A.P.H.) and consequently the flue gases temperature will

approximately increase of the same amount.

Set point is function of boiler load (i.e. SH steam flow) corrected evaluating fuel

(i.e. oil and/or coal) partition.

The operator has a biasing capability to shift the combustion air temperature set

point curve up or down of the established curve based on boiler test.

One of the above control loop for each regenerative air heater is provided.

1.3 S.C.A.P.H. CONDENSATE TANL LEVEL CONTROL

The furnace draft pressure control is designed to provide the proper exhausting

force for flue gases through the boiler, acting on I.D. fans control dampers.

When I.D. fans are properly balanced with F.D. fans, the furnace pressure will be at

the desired operating pressure.

The I.D. fans are controlled by a feedforward plus feedback control which is thencorrected by any deviation of furnace pressure from set point.

The furnace pressure signal is compared to the desired to the desired furnace

pressure set point to develop the furnace pressure error.

The feedforward for I.D. fans dampers position demand is developed from a

program based on the air flow demand (i.e. F.D. fans dampers position demand,

taking into account F.D, fan motors), by using this signal the I.D. fans can respond

to load changes at the same time that F.D. fans do.

This feedforward program is trimmed by integral and proportional action resulting

from any furnace purser error.

The integral and proportional action are separated so that when furnace pressure

effort exceeds a certain deadband, proportional action becomes significant to

rapidly adjust program, to return furnace pressure to the desired value.

Then this corrected program becomes the I.D. fans load demand (i.e. I.D. fans

dampers position).

The I.D. fans damper position demand is actually the average demand for each of

the two fans; the operator can settle a bias in order to balance the incidental

mismatch between the two fans. If one fan is on manual or forced, the fan on

automatic compensates for the fan not participating in the control.

Thus, the bias is continuously calculated when one or more fans are on hand.

When the last is released to control (auto mode and no forcement), the bias isreleased to the operator at the value, if any that is actually between the fans.

To determine the error between demand and the individual fan, the control vane

pitch position is compared to the individual fan biased demand; during normal


controller.

In case a I.D. fan motor is off and the other I.D, fan is in service, the control damper

related to the fan not in service automatically closes.

Proper firing action are performed according to the requires from Burners

Management System and Air & Flue Gases functional groups that force I.D, fan

dampers at proper position, that are: Fully open/closed to perform fans start/stop requence


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Fully open for natural draft requirement, if both I.D. fan motors are off

Because of mater fuel trip and/or loss of flames and/or rapid loss of forced draft, the

negative pressure in the furnace and in flue gases ducts may result in a large

increase, due to:

Sudden reduction of flue gases temperature in the first two cases In large increase of negative pressure at the I.D. fan suction in the last one

This action may occur mach faster than the regular on line furnace draft control,

therefore a separate high speed subsystem for implosion protection, based on the

characterized furnace pressure signal evaluated by three separated wide range

furnace pressure transmitters is p[provided downstream the A/M control stations so

that it cannot be overridden by the operator.

1.5 RECIRCULATING GASES FANS PRESSURE CONTROL

The R.G. fans pressure control is designed to maintain the pressure at the proper

value feeding the cold gases header in order to match cold gases tempering to mills

resuction duct and C.G.R. nozzles flue gases flow demand.

The cold gases pressure set point (based on boiler demand) is compared via

high/low selecting logic to minimum and maximum, pressure limits, then the

resulting value is compared to header pressure value and through the controller sets

the demand for R.G. fans inlet control damper.

The operator has a biasing capability to shift the cold flue gases pressure set point

curve up or down of the established curve based on boiler test.

The R.G. fans damper position demand is actually the average demand for each of

the two fans; the operator can settler a bias in order to balance the incidentalmismatch between the two fans.

If one fan is on manual or forced, the fan on automatic compensates for the fan not

participating in the control.

Thus, the bias is continuously calculated when one or more fns are on had.

When the last is released to control (auto mode and no forcement), the bias is

released to the operator at the value, if any, that is actually between the fans.

To determine the error between demand and the individual fan, the fan inlet control

damper position is compared to the individual fan biased demand; during normal


controller.

In case R.G. fan motor is off, the related control damper automatically closed.Both R.G. fans control dampers automatically close in case of boiler purge.


Management System and Air & Flue Gases functional groups that force R.G. fans

control dampers at proper position that are:

Fully open/closed to perform fan start/stop sequence

Fully closed for natural draft.

1.6 AFTER BURNING GRATE AIR FLOW CONTROL

The A.B.G. air flow control is designed to maintain the air at the proper value in

order to match the flow demand.


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The air flow set point (based on boiler load, i.e. SH steam flow) is compared to the

related air flow value and through the controller sets the demand for the related

A.B.G. air control damper.

The operator has a biasing capability to shift the air flow set point curve up or down

of the established curve based on boiler test.

Two of the above control loop are provided, one for each section of the A.B.G.


Management System that force the A.B.G. control dampers at proper position, that

are:

Partially open (approx. 30% -to be defined-) too perform furnace purge

sequence

Last position for five minutes if the combustion air flow is below the purge

rate at the time of the trip, waiting time for purge

Fully open for natural draft requirement

2.0 BINARY CONTROL

2.0.00 FORWORD

The air & flue gases system is structure as follows:

Functional group: The operator puts in or out of service a complete lime of

air and flue gases circuit consisting of the related Regenerative Air Heater (in

the hereinafter paragraphs will be called as R.A.H.), I.D. fan, F.D. fan and

relevant automatic dampers with a single command, if the functional group is in

auto mode.Facilities to put in service each line separately or both lines in sequence are

provided according to line selection.

Functional subgroup: the operator puts in or out of service an eequipment

and its associated items (dampers..). Each sequence is simplified, i.e.

interruption facility is not available and the sequence is forced to manual in case

of step failure (see typical command logic description). The following

functional subgroups are provided, one for each line:

Regenerative air heater functional subgroups: the operator puts in or out of

service the selected R.A.H. and relevant automatic dampers with a single

command if the functional subgroup is in auto mode. I.D. fan functional subgroup: the operator puts in or out of service the

selected I.D. fan and relevant automatic dampers with a single command

if the functional subgroup is in auto mode.

F.D. fan functional subgroup: the operator puts in or out of service the

selected F.D. fan and relevant automatic dampers with a single with a

single command if the functional subgroup is in auto mode.

Drive level: at this level the operator commands each device individually.

Interlocks among different devices will always be guaranteed.

2.1.00 AIR 7 FLUE GASES SYSTEM FUNCTIONAL GROUP


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This functional group commands the start-up and shut-down of the air & flue gases

system in sequential mode, provided the functional group is selected in auto mode.

The functional group is put in auto mode by the operator, via the auto/manual

selection command; it is forced to manual in the following cases:

Natural draft (after natural draft the functional group is released to

automatic mode) After start-up or shut-down sequence end, if the functional group status

changes

At line selection (pulse-type command).

2.1.01 AIR FLUE GASES SYSTEM SELECTION

The operator chooses among following possibilities which line has to be put in or

out of service:

Only line 1 in or out of service

Only line 2 in or out of service Both lines in or out of service; line 1as first, followed by line 2

Both lines in or out of service; line 2 as first, followed by line 1

The above mentioned selections are commanded form keyboard by depressing the

selection push-button.

The initial selected sequence cannot be changed until sequence itself has been

completed or has failed.

2.1.02 AIR 7 FULE GASES SYSTEM START-UP SEQUENCE

The operator starts the sequence from keyboard by issuing the start command or

from conventional control panel interface by depressing the start push-button,provided the functional group has been selected on auto mode and line selected.

When the operator selects both lines to be put in service, the start-up sequence of

the second line automatically starts when the first line start-up is complete.

Each sequence step takes place if the following permissive is satisfied:

Waiting time for purge not present

a. The 1st step commands the air and flue gases system amperes opening. It is takes

place if the following permissives are satisfied:

R.A.H. 1(2) start permissives present (i.e. guide and support bearings

cooling water flow adequate)

All the related devices are available

At least one of the following conditions present:

air & flue gases line 1(2) selected

air & flue gases line 1and 2 (2 and 1) selected

air & flue gases line 2and 1 (1 and 2) selected and line 2 start-up

sequence end;

In this case the step is performed but the command is skipped.

The relevant commands are set to fans and

R.,A.H.s shut-off dampers individual drive levels, to fans control amperes and

to secondary and tertiary air control dampers


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b. The 2nd step commands the R.A.H. start-up. It takes place after checking the

completion of the 1st step within the proper che3ck time, that is:

At least one air flow path open OR the other air and gases line in service

The relevant command is sent to the functional subgroup R.A.H. start-up

sequence.

c. The 3rd step commands the related I.D. fan start-up. It takes place after checking

the completion of the 2nd step within the proper check time, that is :

R.A.H. in service

The relevant command is sent to the functional subgroup I.D. fan start-up

sequence.

d. The 4th step commands the related F.D. fan start-up. It takes place after checking

the completion of the 3rd step within the proper check time, that is:

I.D. fan in service

The relevant command is sent to the functional subgroup F.D. fan start-up

sequence.

e. After completion of the 4th step the air and flue gases line start-up sequence is

complete. If air & flue gases lines 2 and 1 (1 and 2) are selected, line 2(1) start-

up permissive mist be satisfied, in order to start the second sequence as soon as

the first one ends.

Therefore, at time 1(2) start-up sequence end, the alarm start up line 2(1)

require and on permissives will be issued in any of the following cases: Line 2(1) start-up permissives not present

Waiting time for purge

Functional group selected on manual mode

2.1.03 AIR & FLUE GASES SYSTEM SHUT-DOWN SEQUENCE

The operator starts the sequence from the keyboard by issuing the stop command or

from conventional control panel interface by depressing the stop push-button,

provided the functional group has been selects on auto mode and line selected.

Then the operator selects both lines to be stopped, the shut-down sequence of the

second line automatically starts when the first line shut-down is complete.Each sequence step talks place if the following permissive is satisfied:


a. The 1st commands the F.D. fan shut-down. It takes place if the following

permissives are satisfied:

All functional subgroups relevant to line 1 (2) in automatic mode

At least one of the following conditions present:

air & flue gases line 1(2) selected

air & flue gases line 1and 2 (2 and 1) selected

air & flue gases line 2and 1 (1 and 2) selected and line 2 shut-downsequence end.


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The relevant command is sent to the functional subgroup F.D. fan shut-down

sequence.

b. The 2nd step commands the I.D. fan start- down. It takes place after checking the

completion of the 1st step within the proper check time, that is:

F.D. fan motor off

The relevant command is sent to the functional subgroup I.D. fan start-down

sequence.

c. The 3rd step commands the related R.A.H start-down. It takes place after

checking the completion of the 2nd step within the proper check time, that is:

I.D. fan motor off.

The relevant command is sent to the functional subgroup R.A.H. start-down

sequence.

d. After completion of the 3rdh step the air and flue gases system start-down

sequence is complete.

If air & flue gases lines 2 and 1 (1 and 2) are selected, line 2(1) start-up

permissive mist be satisfied, in order to start the second sequence as soon as the

first one ends.

Therefore, at line 1(2) start-down sequence end, the alarm start down line

2(1) require and on permissives will be issued in any of the following cases:

Line 2(1) start-up permissives not present

Waiting time for purge

Functional group selected on manual mode

2.1.04 AIR & GASES SYSTEM COUNTING

To satisfy at least one air path open permissive, required by first air and flue

gases equipment start-up, command provided to perform all shut-off and control

dampers opening as follows:

From air and flue gases functional group: if no air and flue gases line is in

service both R.A.H.s inlet and outlet air and flue gases dampers, both F.D.

fans dampers, all secondary and tertiary air dampers are required to open.

From I.D. fan functional subgroup: if the other I.D. fan is not in service bothF.D. fans dampers, secondary and tertiary air dampers are required to open.

From F.D. fan, functional subgroup: if the other F.D. fan is not in service

the dampers of other F.D. fan, secondary and tertiary air dampers are

required to open

After least one air path open permissive is satisfied when all the hereinafter

conditions occurs:

All shut-off dampers of one R.A.H. are fully open

Shut-off damper of one F.D. fan fully open and related control damper not

closed

At least 3 mill air paths open


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2.2.00 REGENERATIVE AIR HEATER SYSATEM FUNCTIONAL SUBGROUP

This functional subgroup commands the start-up and shut-down of the R.A.H. and

the automatic dampers in sequential mode, provided the functional subgroup is

selected in auto mode.

The functional subgroup is put in auto mode by the operator, via the auto/manualselection command; it is forced to manual in any of the following cases:

R.A.H. trip

After start-up or shut-down sequence end if the functional subgroup status

changes

Natural draft (after natural draft the functional group is released to auto)

Two of the above mentioned functional subgroups are provided, one for each

R.A.H.

2.2.01 REGEENERATIVE AIR HEATER 1 START-UP SEQUENCE


from conventional control panel interface by depressing the start push-button, or the

sequence is also automatically started by a logic signal generated at higher

hierarchical level.



a. The 1st step commands the selected R.A.H. 1 bearings oil pumps motor start

and shut-off dampers opening; it takes place if the following permissives are

satisfied: All the related devices are available

R.A.H. 1 start permissives present (i.e. guide and support bearings

cooling water flow adequate

The relevant commands are sent to the individual drive levels R.A.H. 1 guide

bearing oil pump, R.A.H. 1 support bearing oil pump, R.A>H. 1 damper

upstream S.C.A. P.H. 1, Air damper at R.A.H. 1 outlet, Flue gases damper

at R.A.H. 1 inlet and R.A.H. 1 damper downstream ESP 1

b. 2nd step commands the selected R.A.H. 1 motor starting; it takes place after

checking the completion of the 1st step within the proper check time, that is: R.A.H. 1 damper upstream S.C.A.P.H, 1 open

Air damper at R.A.H. 1 outlet open

Flue gases damper at R.A.H. 1 inlet open

R.A.H. 1 damper downstream ESP 1 open

R.A.H. 1 guide bearing lubricating oil temperature adequate OR related

pump in service

R.A.H. 1 support bearing lubricating oil temperature adequate OR related

pump in service

The relevant command is sent to the individual drive level R.A.H. 1 motor.


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c. After completion of the 2nd step, the R.A.H. 1 sequence is complete.

The signal of the R.A.H. 1 in service is generated when all the following

conditions are satisfied:

At least one R.A.H. 1 motor running

R.A.H. 1 damper upstream S.C.A.P.H. 1 open

Air damper at R.A.H. 1 outlet open

Flue gases damper at R.A.H. 1 inlet open

R.A.H. 1 damper downstream ESP 1 open

2.2.02 REGENERATIVE AIR HEATER SHUT-DOWN SEQUENCE

The operator stats the sequence from keyboard by issuing the stop command or

from conventional control panel interface by depressing the stop push-button, or the


hierarchical level.

Each sequence step takes place if the following permissive is satisfied: Waiting time for purge not present

a. The 1st step commands the R.A.H. 1 dampers closing; it takes place if at least

one of the following permissives is satisfied

The other R.A.H. in service

Both I.D. fans motor off

The relevant commands are sent to the individual drive levels R.A.H. 1 damper

atS.C.A. P.H. 1 inlet, Air damper at R.A.H. 1 outlet, Flue gases damper at

R.A.H. 1 inlet and R.A.H. 1 damper downstream ESP 1

The relevant requirements are set to R.A.H. 1 dampers, and it will be effective

only if the R.A.H. 1 is not the last in service; that means, according to NFPA

rules, the last R.A.H, will be stopped with open dampers.

b. The 2nd step commands the selected R.A.H. 1 motor starting; it takes place after

checking the completion of the 1st step within the proper check time, i.e. the

following permissive is satisfied:

R.A.H. 1 damper (i.e. upsteream S.C.A.PH. 1, outlet air, inlet flue gases

and downstream ESP) closed

Both I.D. fans motor off AND R.A.H. 2 not in service

The relevant command is sent to the individual drive level R.A.H. 1 motor.

The R.A.H. 1 shut-down command is memorized to allow the completion of the

R.A.H. 1 shut-down sequence without expecting the R.A.H, 1 motor off signal,

which will be available after several hours (up to 20 hours), when the R.A.H. 1

has been cooled.

The R.A.H. shut-down memory (running for cooling) is set in the following

cases:

The stopping request comes from logic and at least one of the two

R.A.H. 1 motors is running;


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The operator tries to stop the R.A. H. 1 motor A and all the following

conditions are present:

R.A.H. 1 motor A is running;

R.A.H. 1 gas outlet temperature is not lower than minimum;

the above mentioned R.A.H. 1 motor shut-down permissive is satisfied.

Once the running for cooling signal is active, the motor will be automatically

stopped as soon as R.A.H. 1 gas outlet temperature becomes lower than

minimum (or cooling time has been expired).

The R.A.H. running for cooling memory is reset (and the running for cooling

signal deleted) in the following cases:

When the R.A.H. 1 start is required again;

When R.A.H. 1 motor shut-down permissive disappears (the running for

cooling memory can be set only if such permissive is present);

If during cooling time, both R.A.H. motors are stopped for 30 s (e.g. in

case of R.A.H. trip).After cooling time has expired the running for cooling signal disappears, in

order to have the permissive to start the R.A.H. motors again.

c. The 3rd step commands the R.A.H, 1 bearings oil pumps motors stopping; it

takes place after checking the completion of the 2 nd step within the proper check

time, that is:

R.A.H. 1 running for cooling OR both R.A.H. 1 motors off

The relevant commands are sent to the individual drive levels R.A.H. 1 guide

bearing oil pump and R.A.H., 1 support bearing oil pump.

d. After comp0letion of the 3rd step, the R.A.H. 1 shut-down sequence is complete

2.2.03 R.A.H. 1 MOTOR SELECTION

The choice of the R.A.H. 1 motor as operating or as stand-by duty ius selected by

the operator through the keyboard.

The operator can select one R.A.H. 1 motor running and the other one as stand-by

or can choose manual selection and in this case both pumps can be remotely started

by the operator. Motor selection cannot be changed during functional subgroup

start-up.

2.2.04 R.A.H. 1 MOTOR

a. Start

The operator starts R.A.H. 1 motor issuing the related command from keyboard;

it also automatically starts by a logic signal generated at higher hierarchical

level, if selected.

If selected as stands-by, the R.A.H. 1 motor is also started automatically in case

of failure of the other motor.

The motor starts if the following permissives are present:

The other motor is nor selected OR the other motor is in failure


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The other motor has been off for 15 s (to be defined), in order to allow

centrifugal clutch disengaging

R.A.H. 1 guide bearing lubricating oil temperature adequate (OR at least

one guide bearing lubricating oil pump in service)

R.A.H. 1 guide bearing cooling water flow greater than minimum

R.A.H. 1 support bearing lubricating oil temperature adequate (OR at leastone support bearing lubricating oil pump in service)

R.A.H. 1 support bearing cooling water flow greater than minimum

Natural draft not required.

b. Stop

The operator stops the R.A.H. 1 motor by issuing the related command from

keyboard; the R.A.H. 1 motor also automatically stops by a logic signal

generated at higher hierarchical level. If the R.A.H. 1 gas outlet temperature is

lower than minimum, the motor is stopped at once, other wise the stoppingrequest is stored in the running for cooling memory, described at functional

group shut-down sequence (2nd step).

The motor stops if the following stop permissive is present:

R.A.H. 1 motor shut down permiossive, described at functional group

shut-down sequence (2nd step)

c. Protection stop

The R.A.H. 1 motor A is forced to stop in any of the following cases:

When R.A.H. 1 motor A failure signal occurs;

When R.A.H. 1 trip signal occurs.

Two of the above the drive (motor A and motor B) are provided for each R.A.H.

2.2.05 R.A.H. 1 MOTOR FAILURE AND TRIP

The R.A.H. 1 Motor failure signal is generated when R.A.H. 1 is service and any

of the following conditions occurs:

R.A.H. 1 rotation loss (see the following 2.2.06)

R.A.H. 1 motor start failure

This signal will provide to start the R.A.H. 1 stand-by motor; if within 30 secondthe trip conditions (i.e. rotation loss or motor trip) are not deleted by the start-up of

the stand-by motor the R.A.H. 1 trip signal occurs.

The conditions causing the trip are memorized and alarmed. After the condition

causing the trip returns to a non trip status, the memories are reset by the operator

depressing the appropriate reset push-button via keyboard.

2.2.06 R.A.H. 1 ROTATION LOSS DETECTION

R.A.H. 1 rotation switches monitoring is active when at least one R.A.H. 1 motor is

running. When rotation loss is detected, the running motor(s) is (are) declared infailure, as described in the previous 2.2.05


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Rotation loss detection is performed as follows:

1. If a rotation switch has been closed for at least 5 s (to be

defined):

At once, an alarm is given to the operator (switch closed too long);

If the other rotation switch is nor detected within one revolution time (sincethe last detection it), rotation loss is detected;

2. If a rotation switch is nor detected with one revolution (since

the last detection of it):

At once, an alarm is given to the operator (switch closed too long);

If the other rotation switch is not detected within one revolution time (since

the last detection of it), rotation loss is detected;

So, in the first case rotation loss is detected not later than half a revolution time

after R.A.H. stopping, while in the second case rotation loss is detected not later

than one revolution time after R.A.H. stopping. In any case, if only one limit switchis out of order, an alarm is given to the operator, but the rotation loss is not

declared.

2.2.07 R.A.H. 1 SUPPORT BEARING LUBRICSAYTING OIL PUMP MOTOR

SELECTION

The choice of the R.A.H. 1 support bearing lubricating oil pump as operating or as

stand-by duty is selected by the operator through the keyboard.

The operator can select one R.A.H. 1 support bearing lubricating oil pump running

and the other one as stand-by or can choose manual selection and in this case both

pumps can be remotely started by the operator.

2.2.08 R.A.H. 1 SUPPORT BEARING LUBRICATING OIL PUMP MOTOR

a. Start

The operator starts R.A.H. 1 support bearing lubricating oil pump motor by

issuing the related command from keyboard; it also automatically starts, if

R.A.H. 1 support bearing lubricating oil temperature is high, in any of the

following cases:

If the pump is selected, by a logic signal generated at higher hierarchicallevel:

If the pump is selected, when R.A.H. 1 is running;

If the pump is selected as stand-by, in case of failure of the other pump.

The pump starts if any of the following permissives is satisfied:

The other pump is nor selected;

The other pump is in failure.

b. Stop


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The operator stops the R.A.H. 1 support bearing lubricating oil pump motor by

issuing command from keyboard; it also automatically stops if any of the

following cases:

When R.A.H. 1 support bearing oil temperature is lower than minimum

for 60 s;

By a logic signal generated at higher hierarchical level

The motor stops if at least one of the following strop permissives is present:

Lubricating oil temperature lower than minimum for 60 s;

Other pump in service;

Both R.A.H. 1 motors off.

c. Protection stop

For each pump, the related R.A.H. 1 support bearing lubricating oil pump

failure signal is generated when any of the following conditions occurs: Pump motor start failure (e.g. electrical overload);

Low delivery pressure for 3 s with pump motor running for 5 s.

The conditions causing the failure are memorized and alarmed. After the

condition causing the failure returns to a non failure status, the memories are

reset by the operator depressing the appropriate reset push-button via keyboard.

Each R.A.H. 1 support bearing lubricating oil pump motor is forced to stop

when the following condition arises:

Pump failure

Two of the above drive are provided

2.2.09 R.A.H. 1 GUIDE BEARING LUBRICATING OIL PUMP MOTOR SELECTION

The choice of the R.A.H. 1 guide bearing lubricating oil pump as operating or as

stand-by duty is selected by the operator through the keyboard.

The operator can select one R.A.H. 1 guide bearing lubricating oil pump running

and the other one as stand-by or can choose manual selection and in this case both

pumps can be remotely started by the operator.

2.2.10 R.A.H. 1 GUIDE BEARING LUBRICATING OIL PUMP MOTOR

a. Start

The operator starts R.A.H. 1 guide bearing lubricating oil pump motor by

issuing the related command from keyboard; it also automatically starts, if

R.A.H. 1 guide bearing lubricating oil temperature is high, in any of the

following cases:

If the pump is selected, by a logic signal generated at higher hierarchical

level:

If the pump is selected, when R.A.H. 1 is running;

If the pump is selected as stand-by, in case of failure of the other pump.


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The pump starts if any of the following permissives is satisfied:

The other pump is nor selected;

The other pump is in failure.

b. Stop

The operator stops the R.A.H. 1 guide bearing lubricating oil pump motor by

issuing command from keyboard; it also automatically stops if any of the

following cases:

When R.A.H. 1 guide bearing oil temperature is lower than minimum

for 60 s;

By a logic signal generated at higher hierarchical level

The motor stops if at least one of the following strop permissives is present: Lubricating oil temperature lower than minimum for 60 s;

Other pump in service;

Both R.A.H. 1 motors off.

c. Protection stop

For each pump, the related R.A.H. 1 guide bearing lubricating oil pump

failure signal is generated when any of the following conditions occurs:

Pump motor start failure (e.g. electrical overload);

Low delivery pressure for 3 s with pump motor running for 5 s.

The conditions causing the failure are memorized and alarmed. After thecondition causing the failure returns to a non failure status, the memories are


Each R.A.H. 1 support bearing lubricating oil pump motor is forced to stop

when the following condition arises:

Pump failure

Two of the above drive are provided

2.2.11 R.A.H. 1 DAMPER UPSTREAM S.C.A.P.H.

a. Open

The operator opens the damper by issuing the related command from keyboard,

it also automatically opens by a logic signal generated at higher hierarchical

level.

No permissive is required.

b. Protection open

The damper is forced to the position when the following condition occurs:

Natural draft required


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c. Close

The operator closes the damper by issuing the related command from keyboard,

it also automatically closes by a logic signal generated at higher hierarchical

level. The damper closes if at least one of the following permissive is present:

R.A.H. 2 in service Both I.D. fans motor off

If R.A.H. 1 is not in service, the damper also closes (pulse command) when it

has been opened in order to provided the open flow path.

Any of the above permissives and additional stop condition shall be enabled by

Waiting time for purge nor required.

d. Protection close

The damper is forced to the closed position when the R.A.H. 1 trip signal occurs

enabled by Closing permissive satisfied AND Natural draft not required.

2.2.12 AIR DAMPERAT R.A.H. 1 OUTLET

a. Open



level.No permissive is required.

b. Protection open



c. Close



level. The damper closes if at least one of the following permissive is present: R.A.H. 2 in service






d. Protection close


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2.2.13 FLUE GASES DAMPER AT R.A.H. 1 INLET

a. Open



level.


b. Protection open



c. Close




R.A.H. 2 in service






d. Protection close



2.2.14 R.A.H.1 DAMPER DOWNSTREAM ESP

a. Open



level.


b. Protection open



c. Close


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R.A.H. 2 in service






d. Protection close



2.3.00 I.D. FAN SYSTEM FUNCTIONAL SUBGROUP

This functional subgroup commands the start-up and shut-down of the related I.D.

fan and the automatic dampers in sequential mode, provided the functional

subgroup is selected in auto mode.

The functional subgroup is put in auto mode by the operator, via the auto/manual

selection command; it is forced to manual in any of the following cases:

Related I.D. fan trip After start-up or shut-down sequence end, if the functional subgroup status

changes


Two of the above mentioned functional subgroup are provided, one for each I.D.

fan.

2.3.01 I.D. FAN START-UP SEQUENCE


from conventional control panel interface by depressing the start push-button, thesequence is also automatically started by a logic signal generated at higher

hierarchical level.



a. The 1st step commands the I.D. fan 1 control oil system and cooling air

fan system start-up; it takes place if the following permissives are

satisfied:


At least one R.A.H. in service


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The relevant commands are sent to the individual drive levels I.D. fan 1 control

and lubricating oil pump and I.D. fan 1 cooling and sealing air fan.

b. The 2nd step commands all the dampers opening; it tasks place after checking

the completion of the 1st step within the proper check time, that is:

I.D. fan 1 start-up permisives satisfied (i.e. I.D. fan 12 lubricating oil and

cooling air auxiliary subsystem in service with oil pressure adequate for

start), or fan motor already running


The relevant commands are sent to fans and R.A.H.s shut-off dampers

individual drive levels and to fans control dampers and secondary and tertiary

air control dampers

c. The 3rd step commands the I.D. fan 1 dampers closing; it takes place after


At least one air flow path open

I.D. fan 2 dampers open

In order to avoid control damper opening at 3rd step end, the related command is

saved in a dedicated memory, that is reset incase of sequence manual selection

or at the end of the sequenced, when the control damper is released to auto.

The relevant commands are sent to the individual drive levels I.D. fan 1

suction damper, I.D. fan 1 discharge damper and to I.D. fan 1 controldamper, they are effective only if fan motor is not running.

d. The 4th commands the I.D. fan 1 motor start; it takes place after checking the

completion of the 3rd step within the proper check time, that is:

I.D fan 1 start-up permissives satisfied (i.e. I.D. fan 1 lubricating oil and

cooling air auxiliary subsystems in service with oil pressure adequate for

start.

I.D. 1 fan control damper closed

I.D. 1 fan suction damper closed

I.D. 1 fan discharge l damper closed

If the fan motor is already running, no permissive is required.

The relevant command is sent to the individual drive level I.D. fan 1 motor.

e. The 5th step commands the I.D. fan 1 suction and discharge dampers opening; it

takes place after checking the completion of the 4 th within the proper check

time, that is:

I.D. fan 1 motor has been running for 30 s.

The relevant commands are sent to the individual drive level I.D. fan 1 suction

damper and I.D. fan 1 discharge damper.


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f. The 6th step releases the I.D. 1 control damper in auto; it takes place after

checking the completion of the 5th step within the proper check time, that is:

I.D. fan 1 suction damper open

I.D. fan 1 discharge damper open

The relevant requirement is sent to I.D. fan 1 control damper

g. After completion of the 6th step, the I.D. fan 1 start-up sequence is complete

The signal of the I.D. fan 1 in service is generated when all the following conditions

are satisfied:

I.D. fan 1 motor running for 30 s

I.D. fan 1 suction damper open

I.D. fan 1 discharge damper open

I.D. fan 1 start-up permissives satisfied (i.e. I.D. fan 1 lubricating oil and

cooling air auxiliary subsystems inservice).

2.3.02 I.D. FAN SHUT-DOWN SEQUENCE


from conventional control panel interface by depressing the stop push-button, the


hierarchical level.

Each seque3nce step takes place if the following permissive is satisfied:

Waiting time for purge nor present.

a. The 1st step commands I.D. fan 1 control damper closing; it takes place if atleast one of the following permissives is satisfied:

Both F.D. fans off

The other I.D. fan in service

In order to avoid control damper opening at 1st step end, the command is saved

in a dedicated memory, that is reset incase of sequence manual selection or at

the end of the sequenced, when the fan motor has been stopped for 30s (at this

point, if the other I.D. fan is service, forcement in the analog control section

keeps the control damper closed).

The relevant requirement is sent to I.D. fan 1 control damper, and it will be

effective only if the I.D. fan 1 is not the last inservice; that means, according to

NFPA rules, the last I.D. fan will be stopped with dampers open.

b. The 2nd step commands the I.D. fan 1 suction and discharge dampers closing; it

takes place after checking the completion of the 1st step within the proper check

time, that is:

I.D. fan 1 control damper closed (or the other I.D. fan not in service).

As per the above control damper this command will take place only if the other

I.D. fan is still running.


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The relevant commands are sent to the individual drive level I.D. fan 1 suction

damper and I.D. fan 1 discharge damper.

c. The 3rd step commands the I.D. fan 1 motor stop; it takes place after checking

the completion of the 2nd step within the proper check time, that is:

I.D. fan 1 suction and discharge dampers closed (or the other I.D. fan notinservice).

The relevant command is sent to the individual drive level IO.D. fan 1 motor.

d. The 4th step commands the I.D. fan 1 control oil system and cooling air fan

system stopping; it takes place after checking the completion of the 3 rd step

within the proper check time, i.e. the following permissive is satisfied:

I.D. fan 1 motor oil and cooling air stop permissive.

Such permissive is issued when the following condition is verified:

I.D. fan 1 motor off for 30 s

The relevant commands are sent to the individual drive levels I.D. fan 1 control

and lubricating oil pump and I.D. fan 1 cooling and sealing

The oil pumps and air fans stop commands are memorized to allow the

completion of the I.D. 1 shut-down sequence without expecting the pumps and

fans motors off signals, which will be available after several minutes (up to 1

hour), when the I.D. 1 bearing and hydraulic and bearing rooms have been

cooled.

The oil pumps shut-down memory (running for cooling) is set inset in thefollowing cases:

The stopping request comes from logic (functional subgroup or I.D. fan

trip) and at least one of the two I.D. fan 1 oil pump motors is running.

The operator tries to stop the I.D. fan 1 oil pump A (B) motor and all the

following conditions are present:

I.D. fan 1 oil pump motor A (B) stop permissives satisfied; I.D. fan 1 bearing temperatures are not lower than minimum; I.D. fan 1 oil pump motor A (B) is running; I.D. fan 1 oil pump motor B (A) is not running (or it is in failure).

Once the running for cooling signal is active, the pump motor will be

automatically stopped as soon as I.D. fan 1 beating temperatures become lower

than minimum (or cooling time has been expired).

The oil pump shut-down memory (running for cooling) is reset (and the running

for cooling signal deleted) in the following cases:

When any oil pump start is required again;

When I.D. fan 1 control oil and cooling air stop permissive disappears

(the running for cooling memory can be set only if such permissive ispresent);


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In case of IU.D, fan control oil request (for natural draft the running

for cooling memory can be set only if such request is not present);

If, during cooling time, both oil pump motors are stopped for 30 s.

The air fans shut-down memory (running for cooling) is set in the following

cases: The stopping request comes from logic (functional subgroup or I.D. fan

trip) and at least one of the two I.D. fan 1 air fan motors is running;

The operator this to stop the I.D. fan 1 air A (B) motor and all the

following conditions are present:

I.D. fan 1 oil pump motor A (B) stop permissives satisfied; I.D. fan 1 Hydraulic and bearing rooms temperatures are not lower than

minimum;

I.D. air fan 1 motor A (B) is running;

I.D. air fan 1 motor B (A) is not running (or it is in failure).

Once the running for cooling signal is active; the fan motor will be

automatically stopped as soon as I.D. fan 1 hydraulic and bearing rooms

temperatures become lower than minimum (or cooling time has been expired).

The air fans shut-down memory (running for cooling) is reset (and the running

for cooling signal delet4d) in the following cases:

When any air fan start is required again;

When I.D fan 1 control oil and cooling air stop permissive disappears

(the running for cooling memory can be set only if such permissive ispresent);

If, during cooling time, both air fan motors are stopped for 30 s.

e. After completion of the 4th step, the I.D.fan 1 shut-down sequence is complete

Therefore, as above explained , if the I.D. fan 1 is the last one to be shut-down,

it will be stopped with the suction and discharge shut-off dampers open and the

control damper modulated to avoided excessive furnace pressure transients.

2.3.03 I.D. FAN 1 MOTOR

a. Te operator starts the I.D. fan 1 motor by issuing the command from the

keyboard or from conventional control panel interface by depressing the

start push-button, it also automatically starts by a logic signal generated

at higher hierarchical level. The motor starts if the following permissives

are present:

I.D. fan 1 control oil permissives re present:

I.D. fan 1 control oil flow adequate

At least on I.D. fan 1 cooling air fan in service

At least one R.A.H. in service I.D. fan 1 shut-off and control dampers closed


22/38

Natural draft nor required

Waiting time for purge not required

At least one air flow path open

b. Stop

The operator stops the I.D. fan 1 motor by issuing the command from the

keyboard or from conventional control panel interface by depressing the stop

push-button, it also automatically stops by a logic. Signal generated at higher

hierarchical level. The motor stops if the following permissives are presents;


I.D. fan 1 shut-off and control dampers closed (if it is the first I.D. fan to

be stopped) or both F.D. fans off (in that case because it is the last I.D. fan

to be stopped, the dampers position will not be considered).

c. Protection stop

The I.D. fan 1 is forced to stop for I.D. fan 1 trip signal

2.3.04 I.D. FAN 1 TRIP

The I.D. 1 Trip signal is generated when any of the following conditions:

I.D. fan 1 left or right motor bearing temperature very high

I.D. fan 1 motor winding 1 or 2 or 3 temperature very high

I.D. fan 1 motor left or right bearing vibration (displacement or average

speed) very high

I.D. fan 1 casing vibration (displacement or average speed) very high I.D. fan 1 local emergency

Implosion protection enabled (i.e. all fuels of and furnace purge completed)

and furnace pressure lower than175 mm w.c (to be defined)

I.D. fan 1 left or middle or right bearing temperature very high

I.D. fan 1 motor electrical overload.




2.3.05 I.D. FAN 1 SUCTION DAMPER

a. Open

The operator opens the damper by issuing the command from keyboard, it also

automatically opens by a logic signal generated at higher hierarchical level. The

damper opens of one of the following permissives is present:

I.D. fan 1 motor has been running for 30 s and at least one air flow path

is open

I.D. fan 1 motor off

b. Protection open


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The damper is forced to the open position when the Natural draft condition

occurs.

c. Close

The operator closed the damper by issuing the command from keyboard, it also

automatically closes by a logic signal generated at high hierarchical level. The

damper also closes when following condition occurs:

I.D. fan 1 not in service and the other I.D. fan is in service (pulse).

The damper closed if all the following permissives are satisfied:

I.D. fan 1 off OR I.D. fan 1 control damper closed;

Both F.D. fan motors off OR I.D. fan 2 in service;

Waiting time for purge not required.

2.3.06 I.D. FN 1 DISCHARGE DAMPER

a. Open



damper opens of one of the following permissives is present:

I.D. fan 1 motor has been running for 30 s and at least one air flow path

is open

I.D. fan 1 motor off

b. Protection open

The damper is forced to the open position when the Natural draft condition

occurs.

c. Close

The operator closed the damper by issuing the command from keyboard, it also

automatically closes by a logic signal generated at high hierarchical level. The

damper also closes when following condition occurs:

I.D. fan 1 not in service and the other I.D. fan is in service (pulse).

The damper closed if all the following permissives are satisfied:

I.D. fan 1 off OR I.D. fan 1 control damper closed;

Both F.D. fan motors off OR I.D. fan 2 in service;


2.3.07 I.D. FAN CONTROL AND LUBRICATING PUMP SELECTION

The choice of the pump as operating or as stand-by duty is selected by the operator

through the keyboard.


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The operator can select one pump running and the other one as stand-by or can

choose manual selection and in this case both pumps can be remotely started by the

operator.

Pump selection cannot be changed during functional subgroup start-up

2.3.08 I.D.FANCONTROL AND LUBRIUCATING PUMP A MOTOR

a. Start

The operator starts the I.D. fan 1 oil pump A motor by issuing the related

command from keyboard. It also automatically starts in any of the following

cases:


level;

If the pump is selected as stand-by, in case of failure of the other pump;

In case of I.D. fan control oil request (for natural draft) and the other

pump is not in service.

The pump motor starts if all the following permissives are present:

The other pump is not selected (OR the other pump is in failure);

I.D. fan 1 lubricating oil tank level adequate.

b. Stop

The operator stops I.D fan 1 oil pump A motor by issuing the command from

keyboard; it also automatically stops by a logic signal generated at higher

hierarchical level or after I.D. fan 1 trip (time delayed). If the I.D. fn 1 bearingtemperatures are lower than minimum OR the other pump is in service (and not

in failure), the motor is stopped at once, otherwise the stopping request is stored

in the running for cooling memory, described at functional group shut-down

sequence (4th step).

The motor stops if at least one of the following permissives is present:

Functional group is not in start-up AND I.D. fan 1 control oil and

cooling air stop permissive (described at functional group shut-down

sequence 4th step) is present AND I.D. fan control oil request (for natural

draft) is not present;

The other I.D. fan 1 oil pump is in service AND not in failure.

c. Protection stop

For each pump, the related I.D. fan 1 oil pump failure signal is generated

when any of the following conditions occurs:

Pump motor start failure (e.g. electrical overload):

Low delivery pressure for 15 s with pump motor running for 5 s


condition causing the failure returns to a non failure status, the memories arereset by the operator depressing the appropriate reset push-button via keyboard.


25/38

Each I.D. 1 oil pump motor is forced to stop when at least one of the following

conditions arises:

I.D. fan 1 lubricating oil tank very low level;

Pump motor start failure (e.g. electrical overload);

Low delivery pressure with pump motor running for 20 s.Therefore, in case of low delivery pressure with pump motor running:

Low control oil pressure alarm is issued without time delay,

The stand-by pump is switched-on additionally only 15 s after oil

pressure drop (in order to avoid automatic actions for transient pressure

loss);

If delivery oil pressure is still low, 5 s after (i.e. 20 s after pressure

drop), the previously running pump is automatically stopped;


drop), the stand-by pump is automatically stopped too.

For each I.D. fan, two of the above drive are provided.

2.3.09 I.D. FAN 1 AIR COOLING AND SEALING AIR FAN MOTOR SELECTION

The choice of the I.D. fan 1 air cooling fan as operating or as stand-by duty is a

selected by the operator through the keyboard.

The operator can select one I.D. fan 1 air cooling fan running and the other one as

stand-by or can choose manual selection and in this case both fans can be remotely

started by the operator.

Air fan selection cannot be changed during functional subgroup start-up.

2.3.10 I.D. FAN 1 AIR COOLING AND SEALING FAN MOTOR

a. Start

The operator starts the I.D. fan 1 air cooling fan A motor by issuing the related


cases:

If the air fan is selected, by a logic signal generated at higher

hierarchical level;

If the air fan is selected as stand-by, in case of failure of the other air

fan.

.

The air fan motor starts if all the following permissives are present:

The other air fan is not selected (OR the other pump is in failure);

b. Stop

The operator stops I.D fan 1 air cooling fan motor by issuing the command

from keyboard; it also automatically stops by a logic signal generated at higher

hierarchical level or after I.D. fan 1 trip (time delayed). If the I.D. fan 1

hydraulic and bearing room temperatures are lower than minimum OR the otherair fan is in service (and not in failure), the motor is stopped at once, otherwise


26/38

the stopping request is stored in the running for cooling memory, described at

functional group shut-down sequence (4th step).


Functional group is not in start-up AND I.D. fan 1 control oil and

cooling air stop permissive (described at functional group shut-downsequence 4th step) is present

The other I.D. fan 1 air fan is in service AND not in failure.

d. Protection stop

For each pump, the related I.D. fan 1 cooling air fan failure signal is

generated when any of the following conditions occurs:

Cooling air fan motor start failure (e.g. electrical overload);

Low delivery pressure for 3 s with cooling air fan motor running for 5 s.

The conditions causing the failure are memorized and alarmed. After thecondition causing the failure returns to a non failure status, the memories are


Each I.D. 1 Cooling air fan motor is forced to stop when the following

conditions arises:

Cooling air fan motor start failure (e.g. electrical overload);

Therefore, in case of low delivery pressure with fan motor running:

Low Cooling air pressure alarm is issued without time delay,

The stand-by fan is switched-on additionally only 3s after air pressure

drop (in order to avoid automatic actions for transient pressure loss);

If delivery oil pressure is still low, 5 s after (i.e. 20 s after pressuredrop), the previously running pump is automatically stopped;

No fan is automatically stopped.

For each I.D. fan, two of the above drive are provided.

2.4.00 F.D FAN SYSTEM FUNCTIONAL SUBGROUP

This functional subgroup commands the start-up and shut-down of the related F.D.

fan and the automatic dampers in sequential mode, prodded the functional subgroup

is selected in auto mode.


selection command; it is forced to manual in the following cases:

Related F.D. fan trip

After start-up or shut-down sequence end, if the functional subgroups status

changes


Two of the above mentioned functional subgroup are provided, one for each F.D.

fan.

2.4.01 F.D.FAN START-UP SEQUENCE


27/38


from conventional control panel interface by depressing the start push-button, the


hierarchical level.



a. The 1st step commands the F.D. fan 1 control oil system start-up; it takes place if

the following permissives are satisfied:


F.D. fan 2 not in start-up

At least on E.A.H. in service

At least one I.D. fan in service

The relevant command is sent to the individual drive level F.D. fan 1 control

oil pump.

b. The 2nd commands all the dampers opening; it takes place after checking

completion of the 1st within the proper check time, that is:

F.D. fan 1 start-up permissives satisfied (i.e. control oil pressure adequate

for start) or fan motor already running




The relevant commands are sent to fans and R.A.H.s shut-off dampers

individual drive levels and to fans control dampers and secondary and tertiaryair control dampers.

c. The 3rd step commands the F.D. fan 1 dampers closing ; it takes place after


F.D. fan 2 air path open

F.D. fan 1 start-up permissive satisfied (i.e. control oil pressure adequate)

In order to avoid control damper opening at 3rd step end, the related command is

saved in a dedicated memory, that is reset incase of sequence manual selection

or at the end of the sequence, when the control damper is released to auto.

The relevant commands are sent to the individual drive level F.D. fan 1

discharge damper and to F.D. fan 1 control damper, they are effective only if

fan motor is not running.

d. The 4th step commands the F.D. fan 1 motor starting; it takes place after

checking the completion of the 3rd step within the proper check time, that is:

F.D fan 1 control damper closed

F.D fan 1 discharge damper closed

F.D fan 1 start-up permissives satisfied (i.e. control oil pressure adequate for

start)



28/38

The relevant command is sent to eh individual drive level F.D. fan 1 motor.

e. The 5th step commands the F.D. fan 1 discharge damper opening; it takes place

after checking the completion of the 4 th step within the proper check time, that

is:

F.D. fan 1 motor has been running for 30 s.

The relevant command is sent to the individual drive level F.D. fan 1 discharge

damper.

f. The 6th step releases the F.D. fan 1 control damper in auto; it takes place after

checking the completion of the 5th step within the proper check time, that is:

F.D. fan 1 discharge damper open

The relevant requirement is sent to F.D. fan 1 control damper.

g. After completion of the 6th step, the F.D. fan 1 start-up sequence is complete.

The signal of the F.D. fan 1 in service is generated when all the following

conditions are satisfied:

F.D. fan 1 motor running for 30 s

F.D. fan 1 discharge damper open

F.D. fan 1 at least one control oil pump in service.

2.4.02 F.D. SHUT-DOWN SEQUENCE

The operator starts the sequence from keyboard by issuing the stop command or

from conventional control panel interface by depressing the start push-button, the


hierarchical level.



a. The 1st step commands F.D. fan 1 control damper closing

No specific permissive required.

In order to avoid control damper opening at 1st step end, the command is savedin a dedicated memory, that is reset incase of sequence manual selection or at

the end of the sequence, when the fan motor has been stopped for 30s (at this

point, if the other F.D. fan is in service, a forcement in the analog control

section keeps the control damper closed).

The relevant requirement is sent to F.D. fan 1 control damper, and it will be

effective only if the F.D. fan 1 is not the last in service; that means, according to

NFPA rules, the last F.D. fan will be stopped with dampers open.

b. The 2nd step commands the F.D. fan 1 discharge damper closing; it takes place

after checking the completion of the 1st step within the proper check time, that

is:


29/38

F.D. fan 1 control damper closed (or the other F.D. fan not in service)

As per the above control damper this command will take place only if the other

F.D. fan is still running.

The relevant command is sent to the individual drive level F.D. fan 1 discharge

damper.

c. The 3rd step commands the F.D. fan 1 motor stopping; it takes place after


F.D. fan 1 discharge damper closed (or the other F.D. fan not inservice)

The relevant command is sent to the individual drive level F.D. fan 1 motor.

d. The 4th step commands the F.D. fan 1 control oil system stopping ; it takes place

after checking the completion of the 3rd step within the proper check time, that

is:

F.D fan 1 motor off for 30 s

The relevant command is sent to the individual drive level F.D. fan 1 control

oil pump.

After completion of the 4th step, the F.D. fan 1 shut-down sequence is

complete

Therefore, as above explained, in case the F.D. fan 1 is the last one to be shut-

down, it will be stopped with the discharge damper open and the control damper

modulated to avoid excessive air pressure transients.

2.4.03 F.D. FAN 1 MOTOR

a. Start

The operator start the F.D. fan 1 motor by issuing the command from the

keyboard or from conventional control panel interface by depressing the start

push-button, it also automatically starts by a logic signal generated at higher

hierarchical level. The motor starts if the following permissives are present:

F.D. fan 1 shut-off and control dampers closed At least one R.A.H. in service


F.D. fan 1 control oil pressure adequate for fan start


Natural draft not required

F.D. fan 2 shut-off damper open

F.D. fan 2 control damper not closed

b. Stop


30/38

The operator stops the F.,D fan 1 motor by issuing the command from the


push-button, it also automatically stops by a logic signal generated at higher

hierarchical level. The motor stops if the following permissives are present:

Wait time for purge not required

F.D. fan 1 shut-off and control dampers closed (if it is the first F.D. fanto be stopped) or the other F.D. fan is already stopped (in the case because it

is the last F.D. fan to be stopped, the dampers position will not be

considered)

c. Protection stop

The F.D. fan 1 is forced to stop for F.D. fan 1 trip signal.

F.D. fan 1 also forced to stop at least one of the following conditions arised:


2.4.04 F.D. FAN 1 TRIP

The F.D. Fan 1 Trip signal is generated when any of the following conditions

occurs.

F.D. fan 1 left or right motor bearing temperature very high

F.D. fan 1 motor winding 1 or 2 or 3 temperature very high

F.D. fan 1 motor left or right bearing vibration (displacement or

average speed) very high

F.D. fan 1 casing vibration (displacement or average speed) very high

F.D. fan 1 local emergency stop Implosion protection enabled (i.e. all fuels off and furnace purge

completed) and furnace pressure higher that + 125 mm w.c.

Furnace pressure higher that = 650 mm w.c. (to be defined)

F.D. fan 1 left or middle or right bearing temperature very high

F.D. fan 1 motor electrical overload.



depressing the appropriated reset push-button via keyboard.

2.4.05 F.D. FAN 1 DISCHARGE DAMPER

a. Open



damper opens if any of the following permisives is present:

F.D. fan 1 motor has been running for 30s

F.D, fan 1 motor off

b. Protection open


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The damper is forced to the position when Natural draft confection occurs.

c. Close

The operator closes the damper by issuing the command from the keyboard, it

also automatically closes by a logic signal generated at higher hierarchical level.The damper also closes when the following condition occurs:

F.D. fan 1 not in service and the other F.D. fan is in service (pulse)

The damper closed if the following permissives are present:

F.D. fan 1 off or F.D. fan 1 control damper closed;

F.D. fan 2 dampers open OR both I.D. fan motors off;


2.4.06 F.D. FAN 1 CONTROL OIL PUMP SELECTION

The choice of the pump as operating or as stand-by duty is selected by the operator

through the keyboard.

The operator can select one pump running and the other one as stand-by or can

choose manual selection and in this case both pumps can be remotely start5ed by

the operator.

Pump selection cannot be changed during functional subgroup start-up.

2.4.07 F.D. FAN 1 CONTROL OIL PUMP A MOTOR

a. Start

The operator starts the F.D. fan 1 oil pump A motor by issuing the related


cases:


level;

If the pump is selected as stand-by, in case of failure of the other pump;

In case of F.D. fan control oil request (for natural draft or damper

opening) and the other pump is not in service.

The pump motor starts if all the following permissives are present:

The other pump is not selected (OR the other pump is in failure);

I.D. fan 1 lubricating oil tank level adequate.

b. Stop

The operator stops F.D. fan 1 oil pump A motor by issuing the command from

keyboard; it also automatically stops by a logic signal generated at higher

hierarchical level or after I.D. fan 1 trip (time delayed).


F.D. fan 1 not running for 30 s (and no F.D. fan 1 control oil request)

The other F.D. fan 1 oil pump is in service AND not in failure.


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c. Protection stop

For each pump, the related F.D.. fan 1 oil pump failure signal is generated

when any of the following conditions occurs:

Pump motor start failure (e.g. electrical overload): Low delivery pressure for 15 s with pump motor running for 5 s




Each F.D. 1 oil pump motor is forced to stop when at least one of the following

conditions arises:

F.D. fan 1 lubricating oil tank very low level;

Pump motor start failure (e.g. electrical overload); Low delivery pressure with pump motor running for 20 s.

Therefore, in case of low delivery pressure with pump motor running:

Low control oil pressure alarm is issued without time delay,

The stand-by pump is switched-on additionally only 15 s after oil

pressure drop (in order to avoid automatic actions for transient pressure

loss);


drop), the previously running pump is automatically stopped;

If delivery oil pressure is still low, 5 s after (i.e. 25 s after pressuredrop), the stand-by pump is automatically stopped too.

For each F.D. fan, two of the above drive are provided.

2.5.00 R.G. FAN SYSTEM FUNCTIONAL SYBGROUP

This functional subgroup commands the start-down of the R.G. fan and the

automatic dampers in sequential mode, provided the functional subgroup is selected

in auto mode.


selection command; it is forced to manual in the following case:

Related R.G. fan trip

After start-up or shat-down sequence end, if the functional subgroup status

changes


Two of the above mentioned functional subgroups are provided, one for each R.G.

fan.

2.5.01 R.G. FAN START-UP SEGQENCE

The operator starts the sequence from keyboard by issuing the start command orfrom conventional control panel interface by depressing the start push-button.


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The R.G. fan also automatically starts from signal by higher hierarchical level, i.e.

start-up required by B.M.S.; in this case the priority is given to R.G. fan A, if

after 10 s no R.G. fan is in service or R.G. fan A start-up sequence is not in

progress, it tries to start R.G. fan B.

Each sequence step takes place if the following permissive is satisfied: Waiting time for purge not present

a. The 1st step commands the R.G. fan 1 dampers closing; it takes place if the

following permissives are satisfied


At least one air and flue gases line in service in service

The relevant commands are sent to the individual drive levels R.G. fan 1

suction damper, R.G. fan 1 discharge damper and to R.G. fan 1 control

damper, they are effective only if fan motor is nor running.

b. The 2nd step commands the R.G. fan 1 motor starting; it takes place after

checking the completion of the 1st step within the proper check time, that is:

R.G. fan 1 suction damper closed

R.G. fan 1 discharge damper closed

R.G. fan 1 control damper closed


The relevant command is sent to the individual drive level R.G. fan 1 motor.

c. The 3rd step commands the R.G. fan 1 suction and discharge dampers opening; ittakes place after checking the completion of the 2 nd step within the proper check

time, that is:

R.G. fan 1 motor has been running for 30 s.

The relevant commands are sent to the individual drive level R.G. fan 1 suction

damper and R.G. fan 1 discharge damper.

d. The 4th step releases the R.G. fan 1 control damper in auto; it takes place after

checking the completion of the 3rd step within the proper check time, that is:

R.G. fan 1 suction damper open

R.G. fan 1 discharge damper open

The relevant requirement is sent to R.G. fan 1 control damper.

e. After completion of the 4th step, the I.D. fan 1 start-up sequence is complete.

The signal of the R.G. fan 1 in service generated when all the following conditions

arte satisfied:

R.G. fan 1 motor running for 30 s

R.G. fan 1 suction damper open

R.G. fan 1 discharge damper open


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2.5.02 R.G. FAN SHUT-DOWN SEQUENCE


from conventional control panel interface by depressing the stop push-button, the

sequence is also automatically started by a logic generated at higher hierarchical

level.



a. The 1st commands R.G. fan 1 control closing; it takes place if at least one of the

following permissives is satisfied:

No mills in service

The other R.G. fan in service

The relevant requirement is sent to R.G. fan 1 control damper.

b. The 2nd step commands the R.G. fan 1 suction and discharge dampers closing; it

takes place after checking the completion of the 1st step within the proper check

time, that is:


The relevant commands are sent to the individual drive levels R.G. fan 1

suction damper and R.G. fan 1 discharge damper.

c. The 3rd step commands the R.G. fan 1 motor stop; it takes place after checking

the completion of the 2nd

step within the proper check time, that is: R.G. fan 1 suction and discharge dampers closed

The relevant command is sent to the individual level R.G. fan 1 motor.

d. After completion of the 4th step, the R.G. fan 1 shut-down sequence is complete

2.5.03 R.G. 1 MOTOR

a. Start

The operator start the R.G. fan 1 motor by issuing the command from thekeyboard or from conventional control panel interface by depressing the start

push-button, it also automatically starts by a logic signal generated at higher

hierarchical level. The motor starts if the following permissives are present:

R.G. fan 1 shut-off and control dampers closed

At least one air and flue gases line in service

d. Stop


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The operator stops the R.G. fan 1 motor by issuing the command from the


push-button, it also automatically stops by a logic signal generated at higher

hierarchical level. The motor stops if the following permissives are present:

R.G. fan 1 shut-off and control dampers closed

No mill in service (or the other R.G. fan in service)

C. Protection stop

The R.G. fan 1 Trip signal is generated when any of the following conditions

occurs:

2.5.04 R.G. FAN 1 TRIP

The R.G. Fan 1 Trip signal is generated when any of the following conditions

occurs:

Both F.D. fans motor off

R.G. fan 1 motor electrical overload




2.5.05 R.G. FAN 1 SUCTION DAMPER

a. Open


automatically opens by a logic signal generated t higher hierarchical level. The

damper opens if one of the following permissives is present:

R.G. fan 1 motor has been running for 30 s

R.G. fan 1 motor off

b. The operator closes the damper by issuing the command from keyboard, it also

automatically closes by a logic signal generated t higher hierarchical level.

The damper R.G. fan motor is off OR if the following permissives are present:


No mills in service (or the other R.G. fan in service)

c. Protection close

The damper is forced to closed for R.G. fan 1 trip.

2.5.06 R.G. FAN 1 DISCHARGE DAMPER

a. Open


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automatically opens by a logic signal generated t higher hierarchical level. The

damper opens if one of the following permissives is present:

R.G. fan 1 motor has been running for 30 s

R.G. fan 1 motor off

b. The operator closes the damper by issuing the command from keyboard, it also

automatically closes by a logic signal generated t higher hierarchical level.

The damper R.G. fan motor is off OR if the following permissives are present:


No mills in service (or the other R.G. fan in service)

c. Protection close

The damper is forced to closed for R.G. fan 1 trip.

2.6.00 AUXILIARY AIR FANS

2.6.01 AUXILIARY AIR FAN SELECTION

The choice of the auxiliary air fan as operating or as stand-by duty is selected by the

operator through the keyboard.

The operator can select one auxiliary air fan running and the other one as stand-by

or can choose manual selection and in this case both auxiliary air fans can be

remotely started by the operator.

2.6.02 AUXILIARY AIR FAN 1 MOTOR

a. Start

The operator starts the auxiliary fan 1 motor by issuing the related command

from keyboard; it also automatically starts if the other one fails and it had been

selected as stand-by operation

The fan motor starts if any of the following permissives is present:

The other fan is not selected;

The other fan is failure.

b. Stop

The operator stops the auxiliary fan motor by issuing the command from

keyboard; it also automatically stops after 30 s that auxiliary air fan motor is

running and the discharge damper is closed. The motor stops if at least one of

the following permisives is present:

The other auxiliary air fan is in service

No burner in service.

c. Protection stop


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For each fan, the related auxiliary air fan failure signal is generated when any

of the following conditions occurs:

fan motor start failure (e.g. electrical overload):

Low delivery pressure for 3 s with fan motor running for 5 s




Each auxiliary air fan motor is forced to stop when the following conditions

arises:

auxiliary air fan motor start failure (e.g. electrical overload).

Low auxiliary air pressure alarm is issued without time delay,

The stand-by fan is switched-on additionally only 3 s after air pressure

drop (in order to avoid automatic actions for transient pressure loss); No fan is automatically stopped.

Two of the above drive are provided.

2.6.03 AUXILIARY AIR FAN 1 DISCHARGBE DAMPER

a. Open


automatically opens when is required the auxiliary air fan 1 starts.


b. Close

The operator closes the damper by issuing the command from keyboard, it also

automatically closes when auxiliary air fan 1 stops. The damper closed if the

following permissive is present:

Auxiliary air fan 1 motor off

Two of the above drive are provided.

2.6.04 AUXILIARY AIR FAN 1 BY-PASS DAMPER

a. Open

The operator opens the damper by issuing the command from keyboard and the

following permissive is present:

Both auxiliary air fan motor off

b. Protection open

If at least one burner is in service, the damper is forced to open in any of thefollowing cases:


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Auxiliary air pressure very low

No auxiliary air fan in service (30 s delayed)

c. Close

The operator closes the damper by issuing the command from keyboard and atleast one of the following permissive is present:

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Date post:	05-Apr-2018
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Air & Flue Gases System

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