Approved FLY ASH SYSTEM OPERATION & CONTROL PHILOSOPHY_R1.pdf

Fly Ash O&M

1. VIDARBHA INDUSTRIES POWER LIMITED

RELIANCE INFRASTRUCTURE LIMITED
MUMBAI




2 X 300 MW COAL BASED POWER PROJECT
Butibori, Dist – Nagpur, Maharashtra




FLY ASH SYSTEM OPERATION & CONTROL PHILOSOPHY


DOCUMENT No: (REL-BGCPP-VEN-144-X-XXXXX) – R1




Note: Pls. provide the REL no. to this document




DEVELOPMENT CONSULTANTS PRIVATE LTD
MUMBAI

CREATIVE ASHTECH POWER PROJECTS PVT. LTD,
PUNE.

2. Project
2x300 MW COAL BASED POWER PROJECT
AT BUTIBORI, DIST NAGPUR,
MAHARASHTRA.
Doc. No: REL-BGCPP-VEN-144-X-XXXXX Rev. R1
Date: 17.03.2012 Page 1

DOCUMENT CONTROL SHEET

PROJECT : 2 X 300 MW Coal Based Power Project
CLIENT : Reliance Infrastructure Limited, Mumbai
DOCUMENT TITLE : FLY ASH SYSTEM OPERATION & CONTROL PHI LOSOPHY
DOCUMENT NO :
REL-BGCPP-VEN-144-X-XXXXX
REV NO : R1






ENDORSEMENTS :



01 17.03.2012 REV 01 A.G.D. A.G.D. S.S.
00 19.11.2010 First Issue SWJ A.K S.S.
Rev
No
Date Description
Initials Sign. Initials Sign. Initials Sign. Initials Sign.
Prepared by Reviewed by Approved by
Issue
Authorization

3. Plant

VIDARBHA INDUSTRIES POWER LIMITED
2X300 MW COAL BASED GROUP CAPTIVE POWER PLANT
MIDC BUTIBORI, DIST: NAGPUR, MAHARASTRA
Client

DEMECH POWER PROJECTS & INFRASTRUCTURE LTD.
3
rd
Floor, Supreme, Opp. Ozone Mall
ITI Road, Aundh
Pune-411007
Consultant


DEVELOPMENT CONSULTANTS LTD.
CONSULTING ENGINEERS
KOLKATA•MUMBAI•MADRAS•NEW DELHI


UNITED CONVEYOR CORPORAT ION (INDIA) PVT. LTD.
11, SHAKESPEARE SARANI (5TH & 6TH FLOOR)
KOLKATA- 700 071, INDIA.

Prepared By AR Scale: N/A
Checked By AR Date: 17/03/2012
Approved By AR Job No.: 70071-02
UCCI DOC NO. MI-70071-002 Rev: B


REVISION










REVISION
NO
DATE DESCRIPTION BY CHECKED APPROVED
A 25-10-10 Initial Submission DPB DPB GS
B 17-03-12 Revised Per CAPPPL
Comment
AR AR AR
FOR APPROVAL

OPERATING INSTRUCTION
FLY ASH DEPAC
®
AND NUVA FEEDER
®
PRESSURE SYSTEM, UNIT 1 & 2

4. .

MICRO

SAFETY NOTE
SOME SAFETY INFORMATION IS INCLUDED IN THESE OPERATING
INSTRUCTIONS. ADDITIONAL SYSTEM & EQUIPMENT SAFETY
INSTRUCTIONS ARE LOCATED UNDER THE “GENERAL INSTRUCTION”
TAB OF THE INSTRUCTIONS FOR ERECTION, OPERATION AND
MAINTENANCE MANUAL. SEE SPECIFIC EQUIPMENT INSTRUCTION
LITERATURE FOR DETAILED SAFETY INFORMATION.
OPERATING INSTRUCTIONS


FLY ASH
DEPAC
®
& NUVA FEEDER
®
PRESSURE SYSTEM
UNIT 1,2






H
G
F
E
C
B
A
REVISIONS
Initial Submittal
Revised Per CAPPPL
Comment














WRITTEN BY
APPROVED BY
DPB
GS
CONTRACT NUMBER(S)
70071-02
FORM NO. K-9881-55 (REVISED 5/26/08)


DRAWING NUMBER
MI-70071-002
Page 2 of 39
REV
A

UNITED CONVEYOR CORPORATION
(INDIA) PVT LTD
11, SHAKESPEARE SARANI (5
TH
& 6
TH
FLOOR)
KOLKATA 700071, INDIA
PLANT NAME
BUTIBORI THERMAL PO WER PROJECT, 2x300 MW
UNIT 1, 2
INDIA

D

5. Page 3 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION

TABLE OF CONTENTS

PART CONTENTS PAGE NO.
1. REFERENCE DRAWING LIST ......................................................................................... 5 
2. GLOSSARY ........................................................................................................................ 6  
3. SYSTEM DESIGN PARAMETERS ................................................................................... 9 
4. SYSTEM DESCRIPTION ................................................................................................. 10 
4A GENERAL OVERVIEW ......................................................................................... 10 
4A.1 DEPAC
®
ASH CONVEYING SYSTEM .................................................... 10 
4A.2 DETAILED SYSTEM DESCRIPTION OF DEPAC® SYSTEM ............... 11  
4A.3 DETAILED SYSTEM DESCRIPTION OF NUVA FEEDER
®
SYSTEM . 13 
4A.4 ASH STORAGE SILO FLUIDIZING ......................................................... 13 
4A.5 ESP FLUIDIZING SYSTEM ....................................................................... 14 
4B EQUIPMENT DESCRIPTION ................................................................................ 14 
4B.1 AIR COMPRESSOR .................................................................................... 14 
4B.2 BIN VENT FILTER ..................................................................................... 14 
4B.3 DEPAC VESSEL ......................................................................................... 15 
4B.4 NUVA FEEDER ASSEMBLY .................................................................... 15 
4B.5 FLUIDIZING AIR HEATER ....................................................................... 15 
4B.6 FLUIDIZING BLOWER .............................................................................. 15 
4B.7 SILO LEVEL DETECTOR .......................................................................... 16 
4B.8 SILO LEVEL TRANSMITTER ................................................................... 16 
4B.9 PRESSURE TRANSMITTER ..................................................................... 16 
4B.10 PRESSURE/VACUUM RELIEF VALVE .................................................. 16 
4C CONTROL FUNCTION DESCRIPTION ............................................................... 16 
4C.1 MAIN CONTROL PANEL .......................................................................... 16 
4C.2 OPERATOR INTERFACE .......................................................................... 17 
4C.3 SCREEN DISPLAY DESCRIPTION/OPERATION .................................. 17  
4C.4 MAIN............................................................................................................ 18 
4C.5 DEPAC & NUVA FEEDER SYSTEM........................................................ 18 
4C.6 DEPAC
®
SYSTEM ...................................................................................... 18 
4C.7 NUVA FEEDER
®
SYSTEM ........................................................................ 20 
4C.8 COMPRESSORS ......................................................................................... 21 
4C.9 ESP FLUIDIZING SYSTEM ....................................................................... 21 
4C.10 BIN FLUIDIZING SYSTEM ....................................................................... 21 
4C.11 ALARM ........................................................................................................ 22 
5. SYSTEM OPERATION .................................................................................................... 23 

6. Page 4 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
5A
 NORMAL (AUTOMATIC) OPERATION ............................................................. 23 
5A.1 OPERATOR SELECTIONS ........................................................................ 23 
5A.2 SEQUENCE OF EVENTS ........................................................................... 23 
5B CLEANOUT OPERATION ..................................................................................... 28 
5B.1 OPERATOR SELECTIONS – CLEANOUT MODE .................................. 28  
5B.2 SEQUENCE OF EVENTS – CLEANOUT MODE .................................... 29 
5C PLUGGED LINE MANUAL PURGE OP ERATION FOR DEPAC SYSTEM ..... 30  
5C.1 SEQUENCE OF EVENTS ........................................................................... 30 
5D ESP HOPPER FLUIDIZING ................................................................................... 30 
5E STORAGE SILO FLUIDIZING .............................................................................. 31 
6. SYSTEM SETTINGS AND ADJUSTMENTS ................................................................. 32 
6A GENERAL ............................................................................................................... 32 
6B INITIAL SETTINGS ............................................................................................... 32 
6B.1 SYSTEM PRESSURE SET POINTS FOR DEPAC
®
.................................. 32 
6B.2 SYSTEM PRESSURE SET POINTS FOR NUVA FEEDER
®
................... 33 
6C SETTING OF FLOW CONTROL VALVE ............................................................ 34 
7. ALARMS ........................................................................................................................... 35  
7A  ALARM DESCRIPTION AN D ACKNOWLEDGMENT ...................................... 35  
7B COMPRESSOR A / B / C FAIL ............................................................................. 35 
7C COMPRESSOR A / B / C WARNING ................................................................... 35 
7D COMPRESSOR A / B / C SHUTDOWN ................................................................ 35 
7E LOW CONVEYING AIR PRESSURE ................................................................... 35 
7F ROW AIR INLET VALVE FAILURE .................................................................... 36 
7G ROW DISCHARGE VALVE FAILURE (DEPAC SYSTEM) ............................ 36 
7H DEPAC TRANSMITTER ASH IN LET VALVE FAILURE .................................. 36  
7I EXCESSIVE PURGE TIME (DEPAC SYSTEM) .................................................. 36 
7J CYCLE TIME EXCEEDED (DEPAC SYSTEM) .................................................. 37 
7K CONVEYING TIME EXCEEDED (DEPAC SYSTEM) ........................................ 37  
7L CLEANOUT EXCEEDED (DEPAC SYSTEM) ..................................................... 37 
7M PLUGGED LINE (DEPAC SYSTEM) .................................................................... 37 
7N CONVEYOR HIGH PRESSURE (NUVA FEEDER SYSTEM) ............................ 38 
7O SILO HIGH LEVEL INDICATOR ......................................................................... 38 
7P OTHER ALARMS ................................................................................................... 38 
8. SPECIAL START-UP AND SHUT-DOWN PROCEDURES ......................................... 39 

7. Page 5 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION

PART 1
REFERENCE DRAWING LIST


Each of the drawings listed below contains a complete listing of all of the drawings used for this
contract by discipline:

Drawing Number Description

Process & Instrumentation Diagrams
M-70071-001 P&I Diagram - General Notes- Units 1 & 2 C&I Drawings
L-70071-001 General Notes & Legend- Units 1 & 2 Conveyor and Service Piping Drawings

C-70071-001 General Notes and Drawing Index- Units 1 & 2

8. Page 6 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
PART 2
GLOSSARY


Bin Vent Filter - The Bin Vent Filter consists of a housing that contains multiple
caged, bag type filters, and a differential pressure Transmitter
for monitoring the filter’s differential pressure across the filter
bags. The function of the vent filter is to vent the air (dust-free)
used for conveying and fluidizing from the bin to prevent over
or under pressurization of the Bin and maintain silo at or near
atmosphere pressure.

Compressor - A source of pressurized air used for conveying. This may be a
blower, compressor, or plant compressed air supply.

DEPAC® - Dense Phase Ash Conveying System. The UCC DEPAC
System is a fully automatic dense phase pneumatic conveying
system.

DEPAC® Vessel - A pressure vessel connected to the collection hopper that holds
a predetermined quantity of ash. During the conveying cycle,
this vessel is pressurized.

Discharge (Sheardisk)
Valve - A pneumatically operated valve that permits the ash and
transport air to exit the DEPAC vessel and enter the
conveying line.


Gates/Valves - The terms gate and valve are of ten used interchangeably. They
provide a means of shut off or isolation.

Hopper - Holds the collected dust that will be conveyed by this system.

I/O Modules - Input/output modules are slot mounted in a chassis,
communicate with the PLC via I/O modules, and are wired to
real world devices, such as push-buttons, limit switches,
indicating lights, solenoids, relays, etc.

Level Probe - DEPAC Vessel is equipped with a level probe that is activated
when the vessel is full with ash. There is also level transmitter
in Silo/Bin.

Nomenclature - The following terms below are used to describe the various
system pressures and their settings. The values are monitored
by the pressure transmitters/switches which are located on the
DEPAC Vessels, Air Receivers and NUVA FEEDER systems.
The initial settings are shown under Part “System Setting and
Adjustment”.

9. Page 7 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
NOTE: These are programmed set points that are
subject to adjustment based on actual system
conditions. These settings are to be changed
only when authorized by the UCC office or a
UCSC service engineer.

Conveyor Low Pressure - When this pressure is exceeded, it indicates that the supply air
pressure is adequate. When this pressure drops below or
initially does not exceed this pressure, it will initiate an alarm
and close all ash inlet valves.

Full Load Pressure
(For DEPAC System) - This is the pressure setting at which the system is designed to
operate and is the expected normal conveying pressure peak
during the conveying cycles.When conveying pressure reaches
5psig above Full Load, the pressurizing line valve closes to
avoid further overloading of line with ash. In addition, the
bypass valve opens, to increase air flow through the conveying
line to decrease the line load. When the pressure decreases to 5
psig below Full Load, the valves return to original positions. If
the pressure remains above 5 psig over Full Load for a preset
period, the line will be considered plugged.

Light Load Pressure
(For DEPAC System) - This is a percentage of the full load pressure, initially set at
75% of the full load pressure. When the peak conveying
pressure drops to or below this pressure, it signals empty
hoppers in that row. This is confirmed by filling the feeders
once again and conveying. If conveying air pressure is still
below the light load pressure setting, the conveying from that
row is considered complete; otherwise the conveying cycle is
to be repeated until two consecutive light load pressures are
reached.

No Load Pressure Normal
(For DEPAC System) - When the conveying pressure decays towards the end of the
cycle, this is the pressure set point that signals that the
conveying line is adequately clean. This pressure signals to
repeat the cycle, or to convey the next row provided light load
pressure is achieved. The conveying line may still have a layer
of ash on the bottom, 1/5 to 1/4 the pipe diameter.

No Load Pressure Cleanout
(For DEPAC System) - When the conveying line is to be cleaned out completely of
ash, twice the airflow of normal conveying is used. As the line
clears, the line pressure gradually decays. When the line
pressure drops below the set point, the conveying line is
completely clean of ash.

No Load Pressure
– Cleanout (For NUVA
FEEDER System) - This indicates the conv eyor system is conveying only material
that is presently being collected in the ash hoppers. When the

10. Page 8 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
pressure in the conveyor drops below this pressure, conveying
from that row is considered complete.

Full Load Pressure
(For NUVA
FEEDER System) - This is the pressure se tting at which the system is designed to
operate. When the pressure in the conveyor exceeds this
pressure, the NUVA FEEDER bottom gate will close to avoid
overloading the conveyor pipe with material. When the
pressure in the conveyor line drops below this pressure, the
bottom gate will reopen.

Conveyor High Pressure
(For NUVA
FEEDER System) - When the pressure in the conveyor exceeds this pressure for
several seconds or "spikes" above this pressure several times in
a specific time period, it will initiate an alarm and perform an
emergency stop.

Pressurising Air Valve - A pneumatically operated valve that permits transport air to
enter the DEPAC Vessel.

PLC - PLC stands for Programmable Logic Controller. The PLC
controls the ash handling system utilizing custom programmed
ladder logic. When the PLC program receives inputs from
switches, push-buttons, the key board, function keys, limit
switches, level controllers, etc. the PLC program will execute
the commands and energize the appropriate outputs according
to the program, such as indicating lights, solenoids, relays, etc.

Swing Disc valve - A pneumatically operated valve that separates the DEPAC
Vessel and NUVA FEEDER from the collection hoppers. This
is also located below the NUVA FEEDER.

11. Page 9 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
PART 3
SYSTEM DESIGN PARAMETERS

1. Plant Elevation, Above Mean Sea Level ........................................... 290m (951 ft)

2. Maximum Ambient Temperature Range ................ 8 °C to 48 °C (46 °F to 118 °F)

3. Ambient Temperature Used For System Design ................................ 35 °C (95 °F)

4. Average Barometric Pressure ........................................... 977.43 mbar (14.18 psia)

5 Electrical Service
 Motor .............................................................................. 415 VAC, 3 Ph, 50 Hz
 Control and Instrumentation ........................................... 240 VAC, 1 Ph, 50 Hz

6. System Design Capacity (Per Unit)
 ESP Field 1& 2 Fly Ash System .......................................... 62 tph (68.2 Ustph)
 ESP Field 3 to 8 Fly Ash System ......................................... 64.5 tph (71 Ustph)
 Air Preheater Ash System .................................................... 16 tph (17.6 Ustph)


7. Material Average Temperature
 ESP Fly Ash ............................................................................... 135 °C (275 °F)
 APH Fly Ash .............................................................................. 150 °C (302 °F)

8. Material Bulk Density
 ESP Ash and APH ash
- Volume ......................................................................... 750 kg/m
3
(47 lb/ft³)
- Structural ................................................................... 1600kg/m
3
(100 lb/ft³)

NOTE: The maximum capacity specified is sum of maximum capacity from the various
collection points for one Unit and in no way implies that this capacity will be
provided from all hoppers under any and all circumstances. Design capacity is
based upon the primary conveyor pipe routing shown on the contract drawings
for this project. The conveyor must be in good repair, installed, and operated
in accordance with the drawings and instructions. Any routing or piping
component changes will impact conveyor capacity.

12. Page 10 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
PART 4
SYSTEM DESCRIPTION

4A GENERAL OVERVIEW

NOTE: Before attempting to operate this system, read and understand the
operating instructions and individual equipment instructions. Read and
understand all of the safety instructions contained in the instruction manual
and review all drawings to become familiar with the equipment and its
operation.

Before attempting to operate, move, adjust, or maintain any equipment,
read UCC Instructions for Erection, Operation and Maintenance.

Only approved personnel should a ttempt to operate or maintain the
equipment as described in these operating instructions.

This DEPAC
®
and NUVA FEEDER
®
systems described in these operating instructions are
positive pressure pneumatic conveyors, designed to convey ash to a storage silo. These
instructions describe the operation of the system for Units 1 & 2. The Fly Ash DEPAC
System below the ESP hoppers is a dense phase pneumatic positive pressure conveying
system. The NUVA FEEDER system below the air heater hoppers is a lean / dilute phase
positive pressure conveying system.

Out of four (4) lines (Conveyor A, Conveyor B, Conveyor C and Conveyor D), three (3)
lines (A, B, and C or D) can be operated simultaneously.


4A.1 DEPAC
®
ASH CONVEYING SYSTEM

Ash is collected and stored in 64 DEPAC Vessels for each unit. One DEPAC
Vessel is installed below each hopper. When one set of DEPAC Vessels collects
ash, the other set connected to a common conveying line for the same field,
transports ash to the ash storage silo. Eight hours of ash is evacuated in six hours
from the hoppers. As the material is collected and stored in the silo, the conveying
air is vented to the atmosphere through a bin vent filter.

The DEPAC Vessels under the Electrostatic Precipitator (ESP) hoppers are of “Top
Discharge” type. In the first two fields, these vessels operate in “2-Parallel Mode”,
where two vessels are operating simultaneously, thus utilizing a common discharge
valve. In the remaining fields, four vessels are operating simultaneously in “4-
Parallel Mode” with a common discharge valve.
The ESP hoppers are equipped with a fluidizing system with fluidizing air heater for
proper feeding of ash in DEPAC Vessels.

The DEPAC system will be controlled by PLC.

The conveying air is supplied from three compressors ( 3x50%) located in the
Compressor Building. Air receivers collect, store, and distribute compressed air as
needed from the supplied compressors.

13. Page 11 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
Fly ash silos are equipped with a fluidizing system, fluidizing air heater,
vacuum/pressure safety relief valve, level instruments, and a bin vent filter for
exhausting conveying and fluidizing air to the atmosphere.

4A.2 DETAILED SYSTEM DESCRIPTION OF DEPAC® SYSTEM

Pressurizing air is taken from an air receiver located near the precipitator building
in ESP area. The receiver is charged by any two of the three oil free rotary screw
compressors. Two compressors are required to provide the air flow needed to
convey ash in three conveyors at a time. There is a total of four lines/conveyors
(three lines from ESP and one line from air heater). In Cleanout mode only one
line should be selected at a time. Other lines should not be under operation due to
high air requirement for the line under Cleanout mode.

There are two conveyor lines from ESP Field 1 and 2 named Conveyor A and
Conveyor B. The remaining fields are connected to another conveyor named
Conveyor C. Air heater hoppers, which are conveyed with a NUVA FEEDER
system, are connected to dedicated line Conveyor D. Conveyor A and Conveyor B
are designed to operate for six hours in an eight hour shift. Conveyor C is designed
to operate for three hours followed by Conveyor D for another three hours in an
eight hour shift.

A manual knife gate is provided for isolation of each hopper. Each hopper is tied
into the conveyor branch line by Ash Inlet Valve and a DEPAC

vessel, which is an
integral part of the conveyor line.

Ash conveying rows are designated in P & I Diagrams. Three conveyors will be
started at a time. For Conveyor A, it will be started from Field 1; two vessels will
be filling while two others will be under conveying. After completion of
conveying, the system will shift to Field 2. Conveyor B, which is connected to the
remaining hoppers of Field 1 and 2, will convey in the same manner. At the same
time, Conveyor C will convey sequentially from Field 3 to Field 8. In each field (3
to 8), four vessels are conveying at a time while four are filling. After completion
of Conveyor C conveying, the NUVA FEEDER system which is connected to
Conveyor D, to be taken up.

During one conveying sequence, fly ash collected in the precipitator hoppers is
gravity fed into the DEPAC vessels. The ash, from hoppers, simultaneously fills
the group of vessels until a fill timer expires or a level probe is met. One vessel in
each conveying row is provided with a high level switch. This level switch is used
to close the Ash inlet valves and can also be used to set the fill timer of the vessel
during start-up or during plant operation. With all vessels (if not bypassed) in the
first row of the selective group filled with material, the Ash Inlet valves will close
on all vessels in the group. Once the limit switches prove that the DEPAC Inlet
valves are closed, there is a 3 second delay, then the vent valves close. After the
DEPAC inlet and vent valves have closed, there is a 3 second delay, then the
Conveying air valve will open. After this the fluidizing phase commences by
opening the Pressurizing valve while the DEPAC Inlet, vent, and discharge valves
remain closed. In normal operation, after opening of the Conveying air inlet valve
followed by Pressurizing valve the system waits for normal pressure. This pressure
is set very low (2 psig~), so almost immediately the discharge valve will open.
With all vessels (if not bypassed) in the first row of the selective group filled with
material, the ash is conveyed and discharged to the selected fly ash silo. At the silo,

14. Page 12 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
the air that is used to convey the material to the silo is vented to atmosphere
through the silo vent filter.

When the conveyor line pressure decays, at the end of a convey cycle, below the
NO LOAD – NORMAL set point, it signals that the conveyor line is adequately
clean to stop conveying. The air flow is then stopped and the already filled up
vessels under parallel mode repeat the conveying cycle. The conveyor line may
still have a layer of ash on the bottom, approximately 1/4 to 1/3 the pipe diameter.
The conveying cycles will occur repeatedly until a LIGHT LOAD condition
occurs or the Maximum Row Conveying Timer elapses. At this point, conveying
will switch to the next field connected to the same Conveyor, if it is not bypassed.

A high flow conveyor line cleanout capability is also provided to remove residual
ash that may accumulate in the vessels and conveyor line. Due to the low
conveying velocity of the DEPAC system and the ash characteristics, a buildup is
possible. Ash accumulation can cause extra restriction in the conveyor line. The
cleanout operation is accomplished by supplying twice the amount of air that is
required for normal conveying. As the line clears, the line pressure gradually
decays to below the NO LOAD – CLEANOUT set point. This indicates that the
conveyor line is completely clean of ash. The frequency and duration of this
cleanout will need to be determined in the field. Initially, once per shift for
approximately thirty minutes (to be decided at field) is recommended. The
Cleanout operation is to be performed prior to the system not being used or
shut down for a period of twenty-four hours or more.

When the conveyor line is partially plugged, build up occurs in the conveyor line,
slow ash removal from the vessel occurs, or the ash inlet gates are leaking(swing
disc valve), the conveyor line pressure will not decrease to the No Load pressure
for the full duration of the Maximum Transmitter Cycle Timer. If this condition
exists, the CYCLE TIME EXCEEDED alarm is activated and indicator
illuminated. Conveying air continues to flow and the ash conveying operation is
allowed to continue. When this alarm occurs and the condition persists, the
operator is to look for general trouble with the system. An Abnormal Stop may be
initiated by the operator, and ash build up is to be cleared from the conveyor line
by using the Cleanout Operation described in Section 5B

If the conveyor line pressure does not decrease to or below the Light Load pressure
set point for the full duration of the Maximum Row Conveying Timer, then the
CONVEYING TIME EXCEEDED alarm is activated and indicator illuminated.
Conveying for this row is not allowed to continue and the system will resume the
Sequence of Events as described in Section 5A for Normal Conveying Sequence.
The operator may initiate conveying from the row that caused the alarm as needed.

If the conveyor line pressure has remained more than 5 psig above FULL LOAD
for a duration greater than one minute (field adjustable), the conveyor line is
considered plugged. If this condition exists, the PLUGGED LINE alarm is
activated and indicator illuminated. When this alarm occurs, the Manual Purge
Sequence, described in Section 5C is to be performed. This manual sequence
utilizes purge air from the purge air header to clear plugs in the conveyor line.

15. Page 13 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION

4A.3 DETAILED SYSTEM DESCRIPTION OF NUVA FEEDER
®
SYSTEM

Ash is collected and stored in 8 Air Heater Hoppers. Eight NUVA FEEDER
assemblies convey ash from the 8 ash hoppers.

The conveying air is supplied from two (02) Air Receiver. A pressure transmitter
located in the DEPAC vessel, downstream of the Flow Control Valve, measures
the pressure for system control.

A NUVA FEEDER is located under each hopper. The NUVA FEEDER receives
material from the hopper and introduces it into a pressurized conveyor line. Here
the material is mixed with the conveying air and is transported to the silo. The
material is collected and stored in the silo, while the conveying air is vented to
atmosphere through the bin vent filter.

The NUVA FEEDER operates on a two minute time cycle that controls the filling
and emptying operations. Time is allowed for equalizing pressures between the
NUVA FEEDER and hopper, and also the NUVA FEEDER and conveying line. A
vertical swing disc gate is located both above and below each NUVA FEEDER to
transfer material to or from the NUVA FEEDER. It is a continuously loaded
conveying system, where at any time four NUVA FEEDER assemblies discharge
ash into the conveying line while four are under filling from hoppers.

4A.4 ASH STORAGE SILO FLUIDIZING

The storage silos are equipped with silo fluidizing systems. The fluidizing systems
assist with ash flow out of the silos. Fluidizing should be started at least 30
minutes prior to unloading ash from a silo.

Ash silo fluidization is accomplished by injecting air into the bottom of the silo,
through fluidizing elements, causing air to flow around and lift the ash particles.
This action creates space between the particles, which expands the ash mixture and
decreases the friction between particles. Fluidizing gives the ash fluid properties
and allows it to flow more readily and consistently at the silo discharge outlet.

The fluidizing air is injected into the ash through the fluidizer. A fluidizer is
composed of a fluidizing element sealed to the top of an air plenum. The air
plenum is a chamber that allows the fluidizing air to be supplied to the bottom of
the fluidizing element. The fluidizing element is a porous membrane that
distributes the fluidizing air uniformly along the surface of the fluidizer. The
fluidizing element also serves as a barrier between the ash and the fluidizer air
plenum, thus helping to prevent the ash from entering the fluidizing air supply
system.

The fluidizing assemblies are arranged on the silo bottom such that ash flows
naturally towards the discharge opening. Orifices and check valves are placed in
each of the diffusing air branch lines. The orifices control the amount of fluidizing
air to each fluidizing assembly, thus assuring an even distribution of air throughout.
The check valves prevent reverse flow so ash will not enter the piping arrangement.
Fluidizing air is heated to prevent condensation from entering the system. The air
heater controls should be initially set to energize below 135° C. The motor driven

16. Page 14 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
fluidizing blower is a positive displacement device. The back pressure regulator
will vent off excess pressure and prevent the blower relief valve from “chattering”.

The fluidizing system should be started at least 30 minutes prior to unloading and
be operated continuously while unloading is being performed.

4A.5 ESP FLUIDIZING SYSTEM

All ESP hoppers are equipped with fluidizing. The fluidizing system assists with
ash flow out of the hoppers. Fluidizing air is heated to prevent condensation from
entering the system. Fluidizing of all hoppers will remain on, while ash is
conveyed. If required, the operator can keep the fluidizing on throughout the shift.

4B EQUIPMENT DESCRIPTION

4B.1 AIR COMPRESSOR
The compressors create a positive pressure airflow in the conveying line, used to
transport ash from the DEPAC vessels and NUVA FEEDER assemblies to the Ash
Storage Silo. Three compressor packages are provided for this system. Two
compressor packages are capable of supplying enough conveying air for three
conveyor lines for one Unit. These compressor packages are positive displacement,
oil free, rotary screw units with integrated refrigerant dryers.

The compressor packages utilized on this system are networked together. In case of
failure of one Compressor, the standby will automatically start to meet the airflow
demand of the system.

4B.2 BIN VENT FILTER

A Bin Vent Filter is provided on top of the Ash Storage Silo for Units 1 & 2. The
purpose of the bin vent filter is to maintain the storage silo at or near atmospheric
pressure by permitting air to move in or out as conditions in the silo change. As the
dust laden air exits the silo it passes through the filter bags. This causes an ash cake
build-up on the outside of the filter bags. An automatic timing device actuates a
series of solenoid valves at preset intervals to permit a surge of high pressure air to
flow down through the bags in a reverse direction. This action flexes the bags and
dislodges the ash cake from the filter bags allowing it to drop down into the Ash
Storage Silo. Ideally, the differential across the filter bags should be low as
possible, yet high enough to prevent dusting. The actual differential obtained to
prevent dusting will vary and depend on actual job site conditions.

The bottom of this vent filter is open, and it sits over a corresponding sized opening
in the top of the Ash Storage Silo. A man grid is incorporated in this vent filter
design to prevent loose bags or maintenance personnel from falling into the Ash
Storage Silo.

CAUTION!!! WORKMAN SHOULD EXERCISE CARE WHEN
CHANGING BAGS TO ENSURE NOTHING DROPS
DOWN INTO THE SILO BELOW. DROPPED OBJECTS
OR MATERIAL CAN PLUG AND/OR DAMAGE SILO
UNLOADING EQUIPMENT.

17. Page 15 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
A differential pressure transmitter is connected between the bag filter compartment
and the clean air plenum. This differential pressure transmitter will indicate a dirty
bag condition.

For additional information on the operation and maintenance of this Bin Vent Filter,
refer to the manufacturer's instructions.

4B.3 DEPAC VESSEL

Each ESP Hopper empties into a DEPAC vessel. The DEPAC vessel is a pressure
coded vessel that acts as an airlock. It receives ash from the low pressure hopper
and introduces it into the high pressure conveying line.

One DEPAC vessel in a group is equipped with a high level probe. Normally the
system will run in Probe mode. All vessels in a group fill until the level probe in the
group is reached, then all ash inlet valves close for the group of vessels. If the level
probe is not triggered by level switch, a back-up timer, initially preset (see
SECTION 5A.2) will close the inlet valves of all vessels of that group, superseding
the probe, to prevent overfilling.

4B.4 NUVA FEEDER ASSEMBLY
Each air heater hopper empties into one NUVA FEEDER assembly. Each NUVA
FEEDER receives ash from the hopper and introduces it into the high pressure
conveyor line. Above and below each NUVA FEEDER there are vertical swing
disc gates. These gates are designed for ash that does not need fluidizing.

Each NUVA FEEDER has a pressurizing valve that allows air from the auxiliary air
header to pressurize the NUVA FEEDER. The pressurizing air also replaces the
volume that is lost when material is discharged into the conveyor line.

Each NUVA FEEDER also has a vent valve that is located in the vent line between
the NUVA FEEDER and the hopper above. The vent valve allows the NUVA
FEEDER to equalize its internal pressure to that of the hopper above. It also allows
air that is displaced by the ash entering the NUVA FEEDER to be vented back into
the hopper.

4B.5 FLUIDIZING AIR HEATER

There is one electric air heater for each blower installed for heating the air supplied
by the Fluidizing Blower. Heating the air prevents moisture from condensing in the
ash in the storage silo/ESP hoppers.

4B.6 FLUIDIZING BLOWER
There are Silo Fluidizing Blowers installed to supply low pressure fluidizing air to
the fluidizing elements in the bottom of the Ash Storage Silo. There are also ESP
Fluidizing Blowers for fluidizing ESP hoppers. This air maintains the ash in a free-
flowing fluid-like state that allows it to empty out of the silo outlet hoppers and ESP
hoppers easily.

18. Page 16 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
4B.7 SILO LEVEL DETECTOR

A Silo Level Detector is located on the roof of the Ash Storage Silo. The level
detector is set to alarm when Ash Storage Silo reaches a high level.


4B.8 SILO LEVEL TRANSMITTER
A Silo Level Transmitter is located on the roof of the Ash Storage Silo. It continuously measures the ash level in the silo, allowing the operator to monitor the
silo usage.

4B.9 PRESSURE TRANSMITTER
A pressure transmitter is located on one DEPAC Vessel of each group of vessels.
This senses the air pressure in the conveying line. This information is used to
monitor the DEPAC System.

The NUVA FEEDER system also has a Pressure Transmitter to monitor the
pressure and control the system.

4B.10 PRESSURE/VACUUM RELIEF VALVE
The internal pressure of the Ash Storage Silo is constantly changing. This internal
pressure is affected by:


 Thermal expansion due to entry of hot ash or air

 Physical expansion due to material displacement

 Fluidizing air

 Removal of ash due to unloading

 Changes in ambient conditions

 Air being blown in by dry unloading spout venting systems

Compensation for this constant pressure variation is usually alleviated by air
flowing in or out through the silo vent filter. It is important that the internal
pressure of the Ash Storage Silo remain at or near atmospheric pressure. If the silo
vent filter is not physically capable of compensating for a change in silo pressure
(e.g., due to plugged vent filter bags), a secondary vacuum/pressure relief valve is
located on top of the Ash Storage Silo. This vacuum/pressure relief valve is capable
of passing large volumes of air inward to relieve a vacuum condition or outward to
relieve a pressure condition.

NOTE: Air discharged through the pressure relief valve is not filtered.

4C CONTROL FUNCTION DESCRIPTION

4C.1 MAIN CONTROL PANEL

The Main Control Panels contain the PLC, the I/O racks and I/O modules for the ash
handling system. The operator controls located on the front of this control panel are
described below.

19. Page 17 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
I/O POWER AVAILABLE signal

This signal indicates when the power to the PLC I/O modules is on.


EMERGENCY STOP Push Button
This soft “EMERGENCY STOP” button shuts down the conveying system
immediately, without a purge period. This is strictly an emergency operation.
Omission of the purge could result in a plugged or partially plugged line. After re-
starting, systems that may have been operating previously will not restart
automatically. It will be necessary to start them again. Soft “EMERGENCY STOP”
PB shall be configured in all HMI pages.

4C.2 OPERATOR INTERFACE
The Operator Interface consists of two LCD monitors. The Operator Interface
utilizes individual screen displays. Each screen display depicts a portion of the Ash
Handling System. System control is accomplished through these screens. The types
of operations that can be performed are explained on each individual screen display.
Operational control varies from screen to screen.


4C.3 SCREEN DISPLAY DESCRIPTION/OPERATION

Operation of the Ash System requires the use of different screens that depict certain
sections of the system. Moving from screen to screen allows the operator to set up
the systems and operate them in the preferred mode of operation. An alarm screen
is provided to record and display the history status of all equipment and system
failures. An alarm status indication is also provided on all screens, signifying the
number of active alarms. Display screens are used to operate and monitor the
DEPAC System and NUVA FEEDER System.

Buttons for switching from screen to screen are clearly indicated on each of the
display screens. The buttons are also used to make required selections and to start
and stop the system/equipment.

The Display Screens use different colors so that the status of the Pressure System
or equipment can be readily determined. The colors used and their meanings
are as follows:

 Red = On, open, operating or selected
 Green = Off, closed, not operating, not selected, or idle
 Yellow = Abnormal condition – warning
 White = Dynamic data.
 Cyan = Static data.
 Blue = Bypassed.
 Gray = Static Equipment

There will be separate screens for the Unit 1 and Unit 2 for Fly ash Pressure
Conveying Systems. The operator has the following system and alarm screens from
which to monitor and control the system.

20. Page 18 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
4C.4 MAIN

This screen is the entry screen for the control system. The operator may access any
other screen by pressing the appropriate button. There are three function keys
available on this screen and are described below. The operator may access this
screen at any time, from any screen, by pressing the appropriate button.

IMMEDIATE STOP
The Immediate Stop function initiated through the Operator Interface shuts the
conveying system down immediately through the logic, without going through a
purge cycle. This option should be used strictly as an emergency operation because
omission of the purge cycle could result in a plugged or partially plugged line.


4C.5 DEPAC & NUVA FEEDER SYSTEM

Screen allows the operator to make the following selections for the DEPAC &
NUVA FEEDER System: System Start, System Normal Stop, and System
Immediate Stop. The DEPAC & NUVA FEEDER System status descriptions and
indications are also shown. There are four (4) conveyors out of which three (3) can
operate at a time (Conveyor A, Conveyor B, Conveyor C followed by Conveyor D).
Individual selections are available for each Conveyor( total four conveyors).
The available selections are listed below.

SYSTEM: START
This command is used to start the DEPAC / NUVA FEEDER Conveying System.

SYSTEM: NORMAL STOP
This command is used to perform a “NORMAL STOP” for the system. This command is the preferred method for stopping the conveying system. Note, the
compressors will still be enabled, allowing the operator to commence with the silo
unloading system.

4C.6 DEPAC
®
SYSTEM
ABNORMAL STOP
This function is used for stopping the conveying system. When this function is
operated, if in filling, all Ash Inlet Valves will close at once. When this function is
operated in conveying, the system will close the Air Supply Valve immediately.
After a four minute delay, the Bin Vent Filter enable signal will de-energize. Use
this function if the system does not reach NO LOAD – NORMAL pressure set point
or if immediate line purging is necessary.

CLEANOUT START
This selection allows the operator to initiate the clean out of the conveyor line. The
Cleanout operation is a high flow line cleanout capability provided to remove
residual ash that may accumulate in the Ash Transmitters and conveyor line. The
high flow cleanout is accomplished by supplying twice the amount of air that is
required for normal conveying. Cleanout operation is not required after each
conveying sequence. The cleanout mode is intended to be used periodically to
remove residual ash that may accumulate in the Ash Transmitters and conveyor

21. Page 19 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
line or prior to the system not being used or shut down for a period of twenty-four
hours or more.

CLEANOUT STOP
This function is used for stopping the clean out operation at any time after it is
started. Normally the cleanout operation is stopped automatically after the
conveyor line is cleaned out, when the system pressure reaches its NO LOAD -
CLEANOUT set point or the Cleanout Run Timer elapses.

CONVEYING MODE: TIMER/PROBE
Selection of TIMER position will allow filling of the DEPAC vessels on a timer set
initially as described in PART 5. This time can be field adjusted for each row
during system start-up to suit the actual flow rate of ash for that precipitator row.

Selection of PROBE position will allow filling of the field DEPAC vessels until
the level probe on one vessel is reached. Then the Ash Inlet Valves for the entire
row will close. If the level probe is not triggered by a full Transmitter, a back-up
timer initially preset (see SECTION 5A.2) will close the Ash Inlet Valves for the
entire row. This back-up timer can be field adjusted for each row during system
start-up to suit the actual flow rate of ash for that precipitator field.

ROW: ON / OFF
This selection is used for bypassing individual rows. There is a separate selection
for each row. Selecting a row to be in OFF will keep the state of the individual
DEPAC vessel ON / BYPASS states but still bypasses all of the transmitters on
that row.

NOTE: If all Rows are bypassed, the system will not start and the Ash Inlet
valves will not operate. One of the Row ON / OFF switches must be set to ON
to allow the conveying of ash. If all rows are placed in OFF while the system is
operating and ash is being conveyed, a Normal Stop will be initiated.

Vessel group: ON / BYPASS (Hopper: On / Bypass)

These are toggle button selections for the DEPAC vessels.
This selection is used for bypassing individual group of DEPAC vessels connected
by common discharge valve. There is a separate selection for each group vessels
connected by common discharge. Selection of ON position will allow the vessel
group to fill and empty in the normal conveying cycle. Selection of BYPASS
position will bypass the vessel group. The Ash Inlet valves for the bypassed vessel
group will not be allowed to open for vessels filling. BYPASS mode only to be
selected, when a vessel is out of service or maintenance needs to be performed on
the vessel.


SELECTION PROHIBITED
This status indication will flash, if the operator tries to start Cleanout System, when
the DEPAC system is in operation. Both systems cannot be operated
simultaneously.

22. Page 20 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
CLEANOUT ROW SELECT:

This selection allows the operator to select the row for cleanout mode. Only one
row can be running in the cleanout mode at any one time. The Row Selection
cannot be changed while the system is operating. The system needs to be off
(Normal Stop) before changing the row selection.

SYSTEM STATUS (ON / OFF / CONVEYING / PURGING)
Indicates the conveying status of the conveyor under operation.

ROW PRESSURE READOUT
Indicates the conveyor line pressure of the conveyor under operation as sensed by
the pressure transmitter located upstream of the ash transmitters. An individual
readout exists for each row.

CONVEYOR PRESSURE RANGE (LOW PRESSURE / NO LOAD-NORMAL /
NO LOAD-CLEANOUT/LIGHT LOAD / FULL LOAD / PLUGGED)

Indicates the conveying pressure status of the conveyor under operation. Low
pressure indication comes from Air receiver.

DEPAC
®
VESSEL ASH LEVEL HIGH
One Level switch in each group of DEPAC vessels is provided to signal HIGH
when the vessel is full.

4C.7 NUVA FEEDER
®
SYSTEM
NUVA FEEDER STATUS
This display shows each feeder on the conveying line, along with its current state.
An identifying letter will appear on the Feeder indicating which valve is operating,
along with the color code described above indicating its state. The feeder
indications are:
 T – Top Gate (Open/Closed)
 V – Vent Valve (Open/Closed)
 P – Pressurizing Gate (Open/Closed)
 B – Bottom Gate (Open/Closed)
 HI – Feeder Body High Level Indication


PRESSURE SYSTEM SETTINGS
This screen provides access to change the pressure system operation selections.
The operator may access this screen at any time, from any screen, by pressing the
appropriate button.

Selections that may be changed include the following:

CONVEYING MODE: PROBE – TIMER

23. Page 21 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION

This is a two-selection function, in which the normal position is “PROBE”. In the
“PROBE” position, the NUVA FEEDER assembly filling cycles are controlled by
the level probes in the feeder. When the feeder reaches a high level, the control
system closes the NUVA FEEDER top gate and begins the dump cycle. A timer
backup exists to close the top gate in the event of a level probe failure or lower than
expected ash production rates. Initial setting of this timer is 4 seconds (field
adjustable).

In “TIMER” mode, the NUVA FEEDER assemblies operate on a 2-minute timed
cycle. This cycle includes pre-set intervals for filling, pressurizing, venting, and
dumping.

SYSTEM STATUS (ON / OFF / CONVEYING / PURGING)
This will show the status of NUVA FEEDER conveyor. NUVA FEEDER: ON / BYPASS
These are toggle button selections for the NUVA FEEDER
In BYPASS position, it will disable the operation of all gates of NUVA FEEDER,
i.e. gates of that NUVA FEEDER in that row will be closed. In ON position, it will
operate normally.

NUVA FEEDER SYSTEM PRESSURE STATUS (LOW PRESSURE / NO
LOAD-CLEAN OUT / NO LOAD-NORMAL / FULL LOAD / HIGH
PRESSURE)
The indicators will show the condition of NUVA FEEDER conveyor line pressure
status which will appear on PLC system.

4C.8 COMPRESSORS

This screen allows the operator to make the following selections for the Air
Compressors: ON, Standby, OFF. The compressor status descriptions and
indications are also shown.

4C.9 ESP FLUIDIZING SYSTEM
This screen allows the operator to make the following selections for the Fluidizing
blower with heater: ON, Standby, OFF. The blower status descriptions and
indications are also shown.



4C.10 BIN FLUIDIZING SYSTEM

This screen allows the operator to make the following selections for the Silo
Fluidizing blower with heater: ON, Standby, OFF. The fly ash bin level and bin
unloading status descriptions and indications are also shown. The available
selections are listed below.

24. Page 22 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION


4C.11 ALARM

This screen provides a list of all the current and historical alarms received from the
DEPAC system. These alarms are listed with date and time at which they occurred.
From this screen the operator can acknowledge the alarms. The alarm screen uses
different colors to depict the status of the alarm. The colors used and their meanings
are as follow:
 Red = In Alarm mode, alarm has been initiated
 Yellow = In Alarm mode, alarm has been initiated and
acknowledged
 Black = Out of alarm mode, alarm has ended

The operator can only access this screen from the main screen.

25. Page 23 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
PART 5
SYSTEM OPERATION

NOTE: Before attempting to operate this system, read and understand the operating
instructions and individual equipment instructions. Read and understand all of
the safety instructions contained in the instruction manual and review all
drawings to become familiar with the equipment and its operation.

5A NORMAL (AUTOMATIC) OPERATION

The procedure to start the system for Unit 1 is as follows. Unit 2 will be similar to this.

5A.1 OPERATOR SELECTIONS
The following selections are made from the Operator Interface:

Conveying Compressor Selection (
On/Standby/Off): .................... ON (2 compressors)
(STANDBY 1
compressor)
DEPAC Conveying Mode (
Timer/Probe): ..................................... PROBE
NUVA FEEDER Conveying Mode (
Timer/Probe): ...................... PROBE
Cleanout Row Select (
A1/A2/A3/A4/B1/B2/B3/B4/C1/…/C12): ........ No Effect during
Conveying Row
Changeover
Conveyor 1A:
A1 A2A3 A4, Conveyor 1B:B1 B2B3 B4, Conveyor 1C:
C1 C2C3 C4C5 C6C7 C8C9 C10C11 C12,
Conveyor 1D: Single row only
Normal Path
Row On / Bypass: ...................................................................... ON for the desired
Rows
OFF for all other
Rows
Hopper On / Bypass: .................................................................. ON for the desired
Hoppers
BYPASS for all
other Hoppers
Silo Select (
Silo 1/Silo 2/Silo 3): .................................................... As Desired
Hopper Fluidizing Blower Select (
On/Standby/Off): .................... ON (2 numbers)
(STANDBY 1
number)

5A.2 SEQUENCE OF EVENTS
Selection of Silo will ready to OPEN the required Silo selection valves while other
valves will remain closed. This will also ready to turn ON the bin vent filter
pulsing system of that selected Silo. This will be enabled after initiation of START
button.

There are four START buttons, one for each Conveyor. A maximum of three
Conveyors can operate simultaneously. In normal operation Conveyor A, Conveyor
B, and Conveyor C should start at the same time. Conveyor A and Conveyor B are
designed for an operation of 6 hours in an eight hour shift. Conveyor C is designed

26. Page 24 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
for 3 hours. So, after 3 hours, when Conveyor C ash conveying is over, Conveyor
D is to be started.
Selection of START function at the PLC will initiate the conveying sequence and
“System On” will be illuminated in the HMI.

DEPAC CONVEYING:
For DEPAC conveying (i.e. Conveyor A, B, C) pressing START will initiate the ESP fluidizing blower and corresponding heater after the opening of its discharge
valve and selected DEPAC row fluidizing air header valve. This will also start the
preselected transport air compressors after the opening of their discharge valves if
not already started. Two compressors are to be operated for three conveying lines.

If adequate air pressure is confirmed by the pressure switch mounted on the
conveying air receiver, an initial line purge will begin.

The selected DEPAC branch isolation valve will OPEN, then the air line valves
(Conveying and Pressurizing) will OPEN to start the initial purging. The other
branch line valves are to be in closed position.

The initial line purge is intended to clear the row of any ash left over from previous
conveying cycles prior to conveying ash.

When the initial line purge begins, the conveyor line will purge for a minimum
duration of one minute (adjustable). After this time, the conveyor line pressure is
monitored. If the conveyor line pressure is not below the No Load – Normal
pressure set point, the purging operation will continue for an additional one minute
(adjustable) to allow the line pressure to drop below the no load pressure. If the
one minute is exceeded without reaching the No Load – Normal pressure setting,
the EXCESSIVE PURGE TIME alarm is activated. The operator must then initiate
an ABNORMAL STOP in which the conveying operation will not be allowed to
continue. The row that experienced excessive purge time should be cleaned by
high flow cleanout operation before commencing the next conveying cycle from
the same row conveyor.

If the conveyor line pressure drops below the No Load – Normal pressure set point,
the complementary branch line in Parallel mode will begin the initial purge like as
described above. After this, initial purging to be done in other branch lines of the
same Conveyor in the same way. When the initial purging is complete, the
conveying operation is initiated. At this time, a Maximum Row Conveying timer is
started. This timer is set for duration of Four hours twenty minutes for parallel
rows A1, A2 and parallel rows B1, B2, One hour forty minutes for parallel rows
A3, A4 and parallel rows B3, B4, One hour ten minutes for parallel rows C1, C2.
Timers for C3 to C12 are to be field set. If this time elapses, conveying will switch
to the other row, as long as it is not bypassed.

The DEPAC conveying cycle mainly consists of two phases, filling and conveying.

FILLING:
The conveying cycle starts after the conveying system has determined that a clear
path to the storage silo exists (initial purge is complete). With the Air Valves and
Discharge Valve closed and the vent valves of the selected vessels are open; the Ash

27. Page 25 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
Inlet Valves of the selected group of DEPAC Vessels in the row will open to allow
ash to enter the vessels. The DEPAC Vessels will continue to receive material from
the hopper, until the level probe signals “full” (or the backup timer has timed out).

The fly ash collected in the precipitator hoppers is gravity fed into the DEPAC
vessels. The Ash inlet Valves will close when the level probe on one vessel sensed
full in PROBE Conveying Mode or when a timer reaches its field adjustable set
point in TIMER Conveying Mode. For Field 1 and 2, timer is initially set for 50
seconds after the Ash Inlet Valve begins to open. For field 3 onwards the Ash Inlet
Valves will close when a timer reaches 30 seconds. The fill timers are to be field
adjusted for each row during system start-up to suit the actual flow rate of ash for
that precipitator field. When in PROBE Conveying Mode, if level probe in the
conveying group is not triggered by level switch, the back-up timer will close the
Ash Inlet Valves for the entire group to prevent over filling. After Filling,
Conveying will start for the filled vessels. The other set of complementary vessels
which are in Parallel mode, will be in Filling mode at that time and it will be ready
to convey. These filled up vessels will start conveying when the earlier group of
vessels’ conveying will be over.

CONVEYING:

At the signal from the level probe (or backup timer), the Ash Inlet valves close,
followed by closing of vent valves, stopping ash accumulation in the vessels. Once
these are proven closed, Conveying air valve opens, then Pressurizing Air Valve
opens, introducing compressed air through the fluidizing disc. The compressed air
will fluidize the ash and help push the ash out of the DEPAC Vessel. Then the
Discharge valve opens. In normal operation, after opening of the Conveying air inlet
valve followed by Pressurizing valve the system waits for normal pressure. This
pressure is set very low (2 psig~), so almost immediately the discharge valve will
open. The time delay between any two consecutive valve openings is 3 to 5 seconds
(field adjustable).

As the pressure in the conveyor line rises, the ash begins to move down the
conveyor line. A normal conveying cycle will see the maximum pressure shortly
after the Air Supply Valve opens. As ash is removed from the DEPAC vessels, the
line pressure gradually decays. When all the material from the DEPAC vessels is
conveyed and the conveyor line clears itself of material, the conveyor line pressure
decreases to its No Load – Normal pressure set point.

After the Minimum Convey time elapses, a Maximum Cycle timer is started. The
timer is set for the remaining duration of the Cycle Time (approximate cycle time
is 3 minutes). During the maximum transmitter cycle time, the conveyor line
pressure is monitored. The minimum convey time, which is slightly less than the
Cycle time, is to be set, to suit site condition.

If the conveyor line pressure decreases to No Load pressure or below during the
maximum cycle time, Conveying and Pressurizing Valve will close followed by
(after 2 seconds) closing of the Discharge valve. The conveyor line may still have a
layer of ash on the bottom; typically up to 1/4 to 1/3 the pipe diameter. The
complementary vessels in Parallel will now start Conveying and these vessels will
go in Filling mode.

28. Page 26 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
If the conveyor line pressure remains above the No Load pressure setting for the
full duration of the maximum cycle time, the CYCLE TIME EXCEEDED alarm is
activated and the “Cycle Time Exceeded” indicator is illuminated. Although this
condition exists, conveying of this cycle is allowed to continue. This condition
may clear itself. If the condition persists, it may indicate, 1) a partially plugged
conveyor line, 2) build up in the conveyor line, 3) slow ash removal from the Ash
Transmitters, or 4) Leakage in ash discharge valves. Buildup can be removed by
initiating a Cleanout Cycle as described in Section 5B. If this condition is left
unchecked, system capacity will be impacted. If No Load – Normal pressure set
point cannot be achieved; ABNORMAL STOP must be initiated by the operator to
stop the conveying cycle.

The conveying sequence will continue to convey ash in the above manner until all
the connected hoppers are emptied. When conveying pressure reaches the Full
Load High, the pressurizing line valve closes to avoid further overloading of line
with ash and the bypass valve opens, so that total air passes through conveying line
to decrease the line load. Then when the pressure decreases to 5 psig below Full
Load, the valve positions come back to its original condition.
If the pressure remains higher than 5 psig above Full Load for a preset period
(approximately 60 seconds), the line will be considered PLUGGED. This condition
will initiate an alarm. The conveyor system will pause in its current state and keep
pressure upstream on the plug in an attempt to break the plug using the high
pressure transport air.

If the blockage does not break free from the high upstream pressure, the operator(s)
must take immediate action. The conveyor system should be stopped and the purge
air system should be utilized to break the plug. See Section 5C for details of the
conveyor line purge connections.

When all the hoppers in the operating row are emptied, the maximum conveying
pressure in the cycle is decreased. If the maximum conveying pressure in the
previous cycle is at or below the “Light Load Pressure”, the Light Load Indicator
will illuminate at the operator interface. Once the light load pressure is achieved, it
signals empty hopper in that row. This is confirmed by filling the hopper once
again and conveying. If conveying air pressure is still below the light load pressure
setting, the conveying from that row is considered complete otherwise the cycle is
to be repeated subsequently to get two consecutive light load pressures and a Final
Line Purge will be initiated. Light Load Pressure, to be achieved for both groups of
complementary vessels, running parallel .The Light Load indication will go off and
Final line Purge will illuminate. If “Light Load” is not reached, the system will go
to the other row after the “Maximum Row Conveying Timer” is exceeded.

During the final line purge, the conveyor line will purge for a minimum duration of
one minute and the system will switch to the next conveying row.


NUVA FEEDER CONVEYING:
This will also start preselected two numbers transport air compressors after opening
of its discharge valves, if not operating already.
For the startup, the branch conveying air line valves for NUVA FEEDER system
will open to make the entire line through for discharge air up to silo.
When adequate pressure is available, the “Initial Purge” indication will illuminate.

29. Page 27 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION

At the end of the 3 minutes initial line purge, the “Initial Purge” indication will turn
off and conveying will begin.

Ash is fed from each of the ash hoppers into the conveyor line via a NUVA
FEEDER. NUVA FEEDER operates as follows:

The vent valve is opened to equalize the NUVA FEEDER internal pressure with
that of the hopper. After a short delay, the top gate will open to begin filling the
NUVA FEEDER.

While the four NUVA FEEDER assemblies are filling, the other four NUVA
FEEDER assemblies will be emptying into the conveyor line and vice versa. The
conveying line remains almost uniformly loaded due to this sequential discharge of
ash from NUVA FEEDER. The NUVA FEEDER assemblies operate on a 120
second cycle. This means that in a 120 second time span, an individual NUVA
FEEDER will have filled once and emptied once. The timer can be field adjusted
to suit the actual flow rate of the ash.

As material enters the NUVA FEEDER, the air that is displaced is vented though
the vent valve back into the hopper. The vent valve remains open until the “fill”
portion of the cycle is complete. When the “fill” portion of the cycle is complete,
the vent valve closes.

When a NUVA FEEDER begins the discharge portion of its 120 second cycle, the
pressurizing air valve opens for a set period of time to raise the NUVA FEEDER
internal pressure just slightly higher than that of the conveyor line. The bottom
gate then opens and material is discharged into the conveyor line. The pressurizing
valve remains open throughout the entire discharge portion of the 120 second
cycle. As ash is discharged from the NUVA FEEDER, air from the pressurizing
valve enters the NUVA FEEDER to replace the volume displaced by the
discharged ash.

During the discharge portion of the cycle, the material in the NUVA FEEDER is
fed into the conveyor line. If the flow of material into the conveyor line exceeds
the designed capacity of the system, the conveyor line pressure will rise above the
“Full Load” set point and the “Full Load” indication will illuminate. This will
automatically close the bottom gate to stop the feed of ash. As the line clears, the
pressure will drop below the “Full Load” value. When this happens, the bottom
gate will reopen and the “Full Load” indication will be removed. This cycling
under Full Load control is normal operation and indicates that the conveyor is
working at its rated capacity. If supply air pressure decreases to a preset value at
any time while the system is conveying, the system will alarm “Low Conveying
Air Supply Pressure” and the bottom gate will close to stop the feed of ash.
Conveying will be allowed to resume only when adequate supply air pressure is
available. After the “discharge” portion of the 120 second cycle is complete, the
NUVA FEEDER bottom gate will close and the entire 120 second NUVA
FEEDER cycle will repeat itself, beginning with the feeder filling operation. Note
that the fill cycle will initiate and the second NUVA FEEDER will begin to empty
after the second NUVA FEEDER is full.

The NUVA FEEDER fills and empties strictly on a timed basis. The timers can be
field adjusted to suit the actual flow rate of the ash. After the timed “discharge”

30. Page 28 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
portion of the cycle is completed, the bottom gate will close and the entire NUVA
FEEDER cycle will repeat itself, beginning with the timed feeder filling operation.

When the conveying pressure comes down to No Load – Cleanout for a full cycle
i.e. for 2 munities, this indicates that the NUVA FEEDER assemblies are no longer
filling fully. All NUVA FEEDER top gates are then closed and the bottom gates
are opened according to the NUVA FEEDER cycle timer. This 120 second
“NUVA FEEDER clean out” will empty the ash from all NUVA FEEDER
assemblies on that row before shut down is initiated.

The system will initiate a final line purge. Upon completion of the final line purge,
the system will be stopped.

To shut down the system, select the NORMAL STOP function from the PLC. This
will initiate shut down procedure described as follows:

 If filling, close all ash discharge valves at conveying line.
 Convey cycle is allowed to complete.
 Final line purge cycle is allowed to complete.
 Close the Air Inlet Valve.
 Close the Branch Line Ash Valves.
 “System On” indicator will no longer illuminate.
 The control system will not shut down the Bin Vent filter so that the filter can
remain in operation for silo unloading operations.

NOTE: IF THE “ABNORMAL STOP” OR “IMMEDIATE STOP”
FUNCTIONS OF ANY DEPAC ROW WAS INITIATED
DURING THE CONVEYING OPERATION, THE OPERATOR
IS TO INITIATE A CLEANOUT OPERATION ON THAT ROW
BEFORE RESUMING TO NO RMAL CONVEYING. THE
CLEANOUT OPERATION IS REQUIRED TO ENSURE THAT
THE CONVEYOR LINE IS ADEQUATELY CLEARED PRIOR
TO INITIATING NORMAL CONVEYING.


5B CLEANOUT OPERATION
This operation is for DEPAC system only.
5B.1 OPERATOR SELECTIONS – CLEANOUT MODE

Conveying Compressor Selection (
On/Standby/Off): ..................... ON (2 compressors)
STANDBY (1
compressor)
Conveying Mode (
Timer/Probe): ................................................... No Effect
Cleanout Row Select (
A1/A2/A3/A4/B1/B2/B3/B4/C1/…/C12): ........ As Desired
Conveying Row Changeover
Conveyor 1A:
A1 A2A3 A4, Conveyor 1B:B1 B2B3 B4, Conveyor 1C:
C1 C2C3 C4C5 C6C7 C8C9 C10C11 C12,
Conveyor 1D: Single row only.
No Effect

31. Page 29 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
Row On / Bypass: ...................................................................... ON for the desired
Rows OFF for all
other Rows
Hopper On / Bypass: .................................................................. No Effect
Silo Select (
Silo 1/Silo 2/Silo 3): .................................................... As Desired
Hopper Fluidizing Blower Select (
On/Standby/Off): .................... No Effect

NOTE: ONLY ONE ROW OF THE CONVEYING SYSTEMS CAN BE
SELECTED AT A TIME TO BE IN THE “ON” POSITION FOR
THE CLEANOUT OPERATION. THE OTHER ROWS WILL
NOT BE OPERATED.

5B.2 SEQUENCE OF EVENTS – CLEANOUT MODE

The cleanout operation is to be initiated with the conveying system stopped. The
flow control valves will be set to have a higher differential pressure (than Normal
conveying) across the orifice in the flow control station. When the conveying air
supply pressure is proven adequate, the Row Air Inlet Valve will open for the row
that is in Cleanout. All Ash Inlet Valves in that row will remain closed. The
system will allow air to flow through the conveyor line at the cleanout air flow rate.
It is done with double the air required during normal conveying i.e. 200%, out of
which 100% air through pressurizing line and 100% air through conveying line.

As the line clears, the line pressure gradually decreases to or below the NO LOAD
– CLEANOUT pressure set point to indicate the conveyor line is completely clean
of ash. When the conveyor line pressure decreases to or below the NO LOAD –
CLEANOUT pressure set point, the system will automatically sequence through
the cleanout shutdown procedure. When shutdown is complete, the “CLEANOUT
ON” indicator will no longer illuminate indicating that the row selected for
Cleanout operation is completely cleaned out of ash. If any other conveying row is
intended to be cleaned out, the same procedure needs to be followed for that row.

A Cleanout Run timer (initially set for 30 minutes) initiates a cleanout shutdown
procedure if the pressure does not drop below the NO LOAD – CLEANOUT
pressure set point within the allotted time. The cleanout sequence can also be
stopped any time after it is started, by selecting CLEANOUT STOP.

Normally the cleanout operation is stopped automatically after the conveyor line is
cleaned out, when the system pressure reaches its NO LOAD - CLEANOUT set
point or when the Cleanout Run timer elapses.

UPON COMPLETION OF ALL CLEAN OUT OPERATIONS AND BEFORE
RESUMING CONVEYING THE CONTROL VALVE WILL
AUTOMATICALLY RESET FOR A DIFFERENTIAL PRESSURE FOR
NORMAL CONVEYING ACROSS THE ORIFICE ON THE FLOW CONTROL
STATION.

32. Page 30 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
5C PLUGGED LINE MANUAL PURG E OPERATION FOR DEPAC SYSTEM

5C.1 SEQUENCE OF EVENTS

The manual purging is accomplished by using the conveyor line purge air
connections. The purge air headers are tapped from the main conveying air supply
line downstream of the air receiver. Hence, the purge air headers are always
pressurized whenever the conveying compressors are running.

The purge connections are located at strategic points on the conveyor to facilitate
cleaning of a plugged conveyor. The isolation valves are opened and the high-
pressure purge air will break up the plug and allow it to be pushed down the
conveyor line.

The manual cleanout should start nearest the Silo and continue back along the
conveyor line towards the DEPAC

Ash Transmitters until the plug is cleared. Only
one purge air connection is to be used at a time. After purging at a connection is
complete, the manual isolation valve to the purge air header is to be closed. When a
plug is cleared, all manual isolation valves are to be closed.

Manual cleaning of conveyor line plugging can be carried out as described above
keeping conveying from other conveyor undisturbed. The conveyor line pressure is
to be monitored while the manual purge sequence is being carried out. When a
plug is cleared, the pressure will decrease, and the operator will have indication
that the manual purge was successful.

If the conveyor line pressure drops below Full Load Pressure, the “PLUGGED
LINE” alarm will clear. If the conveyor line pressure returns to Full Load High or
above, the plug formation may not have completely cleared or it has reformed. The
Manual Purge Sequence is to be attempted again to break up the plug formation.
Once the Plugged Line alarm clears, conveying continues. If the line pressure
continues to decrease to the “NO LOAD” value, the conveying sequence will
continue to the next row.

NOTE: AFTER THE CONVEYOR LI NE IS CLEARED AND BEFORE
RESUMING CONVEYING, ENSURE THAT ALL PURGE LINES
HAVE BEEN DISCONNECTED FROM THE CONVEYOR
LINES TO ENSURE ASH DO ES NOT ENTER THE PURGE
HEADER.

5D ESP HOPPER FLUIDIZING

Pressing the DEPAC System START command at the operator touch panel will start the
Fluidizing Blower with Air Heater after the opening of its discharge valve, provided it is in
Auto mode. In Test mode, separate blower “Start”, at field, will start the selected blower
with heater and “Stop” will stop the same.

The branch header valves on Hopper fluidizing open for those fields only, which are
selected for ash evacuation.

The ESP hopper fluidizing system supplies air to the fluidizing elements located near the
hopper outlet.

33. Page 31 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
Fluidization is accomplished by forcing air to flow around and lift the ash particles. This
action creates space between the particles, which expands the ash mixture and decreases the
friction between particles. Fluidizing gives the ash fluid-like properties and allows it to
flow more readily and consistently at the hopper discharge outlet.

Flow orifices and check valves are placed in each of the fluidizing air branch lines. The
flow orifices control the amount of fluidizing air to each fluidizing assembly, thus assuring
an even distribution of air throughout. The check valves prevent reverse flow so ash will
not enter the piping arrangement.


5E STORAGE SILO FLUIDIZING

Pressing the “Start” command at the operator touch panel will start the Fluidizing Blower,
and Air Heater.

The silo fluidizing system supplies air to the fluidizing elements located at the bottom of
the storage silo as well as the bin outlet hopper.

Fluidization is accomplished by forcing air to flow around and lift the ash particles. This
action creates space between the particles, which expands the ash mixture and decreases the
friction between particles. Fluidizing gives the ash fluid-like properties and allows it to
flow more readily and consistently at the silo discharge outlet.

Flow orifices and check valves are placed in each of the fluidizing air branch lines. The
flow orifices control the amount of fluidizing air to each fluidizing assembly, thus assuring
an even distribution of air throughout. The check valves prevent reverse flow so ash will
not enter the piping arrangement.
Fluidizing should be started at least 30 minutes prior to unloading ash from a silo.

34. Page 32 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
PART 6
SYSTEM SETTINGS AND ADJUSTMENTS


6A GENERAL

All safety valves, regulators, pressure transmitters, etc., should be set for the values called
for on the control drawings and should be changed only by qualified personnel.

Be sure all manually operated valves are positioned as called for on the P & I D or in the
operating instructions.

Review all drawings to become familiar with the operation of equipment and systems,
read and understand all literature regarding safety equipment and read and understand the
operating instructions before attempting to operate any of the equipment or systems.

A “Parameter Set Up” screen will provide access for adjustment of several timers, air flow
set points and system pressure set points. The “Parameter Set Up” screen is to be
password protected for access by a Qualified Technician only. Adjustments to any of the
system settings are to only be made by a Qualified Technician.

6B INITIAL SETTINGS

CONVEYOR LOW PRESSURE:
[Set at 4.2 kg/cm
2
(60 psig)].
This is indicated by the pressure switches on the air reservoirs. When this pressure is
exceeded, it indicates that the air supply pressure is adequate. When the pressure in the
conveyor air supply header drops below or initially does not exceed this pressure, it will
initiate an alarm and close all open Ash Inlet Valves, if they are open. If conveying air
pressure is low when the operator initiates a start command at the beginning of a
conveying cycle, the system conveying sequence will not continue.

6B.1 SYSTEM PRESSURE SET POINTS FOR DEPAC
®


FULL LOAD PRESSURE:
[For Unit 1: Approximately 2.1 kg/cm
2
(30 psig) for Field 1 & 2 and 2.2 kg/cm
2

(31 psig) for remaining fields. For Unit 2: Approximately 2.6 kg/cm
2
(37 psig) for
Field 1 & 2 and 2.5 kg/cm
2
(36 psig) for remaining fields]

This is the expected normal conveying pressure peak during the conveying cycles.
The operator is not required to set this parameter.
When conveying pressure reaches 5 psig above Full Load, the pressurizing line
valve closes to avoid further overloading of line with ash and the bypass valve
opens, increases air passing through the conveying line to decrease the line load.
When the pressure decreases 5 psig below Full Load, the valve positions return to
their original condition.
If the pressure remains higher than 5psig above Full Load, for a period of 60
seconds, the line will be considered plugged.

35. Page 33 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
LIGHT LOAD PRESSURE:

This is a percentage of the full load pressure. It is initially set at 75% of the full
load pressure. When conveying air pressure peak does not exceed this pressure, it
signals empty hoppers in that row. This is confirmed by filling the feeders once
again and conveying. If conveying air pressure is still below the light load pressure
setting, the conveying from that row is considered complete, otherwise the cycle to
be repeated subsequently to get two consecutive light load pressure.

NO LOAD - NORMAL PRESSURE:
[Field set at approximately 0.21 kg/cm2 (3 psig)] When the conveying pressure decays towards the end of the cycle, this is the pressure set point that signals that the conveying line is adequately clean to repeat
the cycle or to convey the next row provided light load pressure is achieved. The
conveying line may still have a layer of ash on the bottom, 1/5 to 1/4 the pipe
diameter.

NO LOAD - CLEANOUT PRESSURE:
[Field set approximately 0.14 kg/cm2 (2 Psig)] When the conveyor line is being cleaned out completely of ash, twice the airflow of
normal conveying is used. As the line clears, the conveyor line pressure gradually
decays. When the conveyor line pressure drops below this set point, the conveyor
line is completely clean of ash (approximately 30 minutes).

SETTING OF FLOW CONTROL VALVE:

Flow control valve stations orifice pressure drop are to be 0.07 kg/cm
2
[1 Psig] in
normal conveying. It will be 0.28 kg/cm
2
[4 Psig] in CLEANOUT mode.

6B.2 SYSTEM PRESSURE SET POINTS FOR NUVA FEEDER
®


FULL LOAD PRESSURE:
[For Unit 1; 1.5 kg/cm
2
(22 Psig); For Unit 2; 1.8 kg/cm
2
(26 Psig)]

This is the pressure setting at which the system is designed to operate. When the
pressure in the conveyor exceeds this pressure, the NUVA FEEDER diffuser feeder
will close to avoid overloading the conveyor pipe with material. When the
pressure in the conveyor line drops below this pressure, the diffuser feeder will
reopen.

No Load - Clean Out:
[For Unit 1; 0.95 kg/cm
2
(13.5 Psig) For Unit 2; 1.05 kg/cm
2
(15Psig)]

The pressure in the conveyor line which results the conveyor system is conveying
only material that is presently being collected in the ash hoppers. When the
pressure in the conveyor drops below this pressure, branch line transfer or system
shut down is initiated.

36. Page 34 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
CONVEYOR HIGH PRESSURE:

Initially field set at 1.9 kg/cm
2
[27.5 Psig] for Unit 1 and 2.17 kg/cm
2
[31 Psig] for
Unit 1. If the pressure remains above this point for ten seconds (field adjustable), or
“spikes” above this point four times in ten seconds (field adjustable), system will
shut down.

6C SETTING OF FLOW CONTROL VALVE

The settings will be as indicated in P &I Ds.

37. Page 35 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION

PART 7
ALARMS

7A ALARM DESCRIPTION AND ACKNOWLEDGMENT

When an alarm occurs, an alarm banner on the Operator Interface will display the most
recent alarm, and the new alarm(s) will be added to the alarm list on the Alarm History
screen.

The alarm will be recorded along with its time of occurrence and status, re: in alarm, or
acknowledged on the Alarm History Screen.

The alarm condition will remain until the condition that caused the alarm is corrected or the
system is shut down. If the system is restarted and the alarm condition was not corrected,
the alarm will be activated again.

The following Ash System conditions are alarmed audibly and displayed on the Operator
Interface.

7B COMPRESSOR A / B / C FAIL
This alarm indicates that compressor is not being ON. No ON feedback received.

7C COMPRESSOR A / B / C WARNING

This alarm indicates that there is a general fault at the compressor which does not need
immediate shutdown. The specific warning is displayed on the Elektronikon compressor
control panel on the affected compressor. The operator should find the causes of warning
and correct as necessary during system dwell period when the compressors are not
running.

7D COMPRESSOR A / B / C SHUTDOWN

This alarm indicates that there is a major fault in the compressor and it takes immediate
shutdown. The specific fault is displayed on the Elektronikon compressor control panel on
the affected compressor. Standby compressor will automatically start to take care of the
system air demand. The operator should find the causes of abnormal condition and correct
as necessary before restarting the compressor.

7E LOW CONVEYING AIR PRESSURE

When the pressure downstream at the air receiver is below a set pressure, this alarm
indicates the existence of this condition. The pressure is sensed by a pressure switch
mounted on the air receiver of the conveying air system of each unit. Possible causes
include compressor failure, pipe break, or excessive air usage at other areas. The operator
should check and correct the abnormal condition. The Ash Inlet valves will be closed.
The conveying operation will not start if the pressure is below the minimum acceptable
value.

Possible causes for this alarm are as follows:

38. Page 36 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
 Incorrectly positioned or leaking gate
 A severe system leak
 Faulty pressure switch
 Purge Air header valve left open ( for DEPAC only)
 Air receiver relief valve, condensate drain valve, or blow off valve stuck open

7F ROW AIR INLET VALVE FAILURE
When the system logic requires these air cylinder operated valves to open or close, and if
the valves fail to fully open or fully close in 10 seconds or loses an open signal, the alarm
is activated to indicate the existence of this condition. The affected system will shut down
for operator action in this alarm condition. All valves will be closed, and the system
operation will not be allowed to be restarted until the alarm condition is cleared.

Possible causes for this alarm are as follows:
 Mechanical failure of the valves or their actuator.
 Mechanical failure of the valve position switch.
 Loss of compressed air to the air cylinder operators of the valves.
 Electrical failures in the control system, loose wiring connections, faulty solenoid, etc.

7G ROW DISCHARGE VALVE FAILURE (DEPAC SYSTEM)
When the system logic requires these air cylinder operated valves to open or close, and if
the valves fail to fully open or fully close in 10 seconds or loses an open signal, the alarm
is activated to indicate the existence of this condition. The affected system will shut down
for operator action in this alarm condition. All valves will be closed, and the system
operation will not be allowed to be restarted until the alarm condition is cleared.

Possible causes for this alarm are as follows:
 Mechanical failure of the valves or their actuator.
 Mechanical failure of the valve position switch.
 Loss of compressed air to the air cylinder operators of the valves.
 Electrical failures in the control system, loose wiring connections, faulty solenoid, etc.

7H DEPAC TRANSMITTER ASH INLET VALVE FAILURE
When the system logic requires these air cylinder operated valves to open or close, and if
the valves fail to fully open or fully close in 10 seconds, the alarm is activated to indicate
the existence of this condition. All Ash Inlet valves in that row will be closed to stop
conveyor line filling. The convey cycle will be allowed to be completed. The system will
undergo a NORMAL STOP in the row that has the failing Ash Inlet valve. Conveying will
continue on the other row if it is selected to ON.

Possible causes for this alarm are as follows:
 Mechanical failure of the valves or their actuator.
 Mechanical failure of the valve position switch.
 Loss of compressed air to the air cylinder operators of the valves.
 Electrical failures in the control system, loose wiring connections, faulty solenoid, etc.

7I EXCESSIVE PURGE TIME (DEPAC SYSTEM)

39. Page 37 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
When the Excessive Purge Timer elapses, this alarm is activated. This indicates that the
conveyor line pressure during the Initial Air Purge has not decreased to or below the NO
LOAD – NORMAL set point one minute after the Minimum Purge Time of one minute.
An Abnormal Stop can be selected.

Possible causes for this alarm are as follows:
 Materials build up inside the pipe line.
 Insufficient airflow to adequately purge conveyor line

7J CYCLE TIME EXCEEDED (DEPAC SYSTEM)

When the conveyor line pressure is greater than the no load pressure for the full duration
of the Maximum Transmitter Cycle Timer, this alarm is activated. Conveying air
continues to flow and the ash conveying operation is allowed to continue. An Abnormal
Stop can be selected. The operator should attempt to clear the conveyor line as discussed
in Section 5B.

Possible causes for this alarm are as follows:
 Materials build up occurring inside the pipe line.
 Partial plugging of the conveyor line
 Slow ash removal from the Ash Transmitters

7K CONVEYING TIME EXCE EDED (DEPAC SYSTEM)

When the conveyor line pressure does not decrease to or below the Light Load pressure set
point for the full duration of the Maximum Row Conveying Timer, this alarm is activated.
Conveying for this row is not allowed to continue and the system will resume the
conveying sequence as in Section 5A. The operator may initiate a Normal Stop then
initiate conveying from the row that caused the alarm as needed until the Light Load
pressure set point is reached.

Possible causes for this alarm are as follows:
 Hoppers are not empty
 Material build up occurring inside the pipe line
 Partial plugging of the conveyor line
 Slow ash removal from the Ash Transmitters

7L CLEANOUT EXCEEDED (DEPAC SYSTEM)
When the Cleanout Run Timer elapses, ( initial setting 15 minutes) this alarm is activated.
This indicates that the conveyor line pressure did not decrease to or below the NO LOAD
– CLEANOUT pressure setting to cause the automatic shut down of the cleanout
operation. The operator can initiate another cleanout operation to attempt further cleaning
of the conveyor line.

Possible cause for this alarm is as follows:
 Material built up inside the pipe line has set up and hardened, losing its flow abilities.

7M PLUGGED LINE (DEPAC SYSTEM)
When the conveyor line pressure exceeds the pre-set value for one minute, this alarm is
activated. This indicates a plugged conveyor line. The Silo Selection Valves will remain


40. Page 38 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION
in their current state. The system will not allow any further feeding of ash into the
conveyor line. The operator should remove the plug as discussed in Section 5C.

Possible causes for this alarm are as follows:
 Changes in material characteristics due to the presence of moisture change in coal
properties, etc.
 Pressurizing air valve is passing.

7N CONVEYOR HIGH PRESSURE (NUVA FEEDER SYSTEM)

When this alarm is received, the pressure in the conveyor has exceeded the “Conveyor
High Pressure” setting. If the pressure remains above this point for ten seconds (field
adjustable), or “spikes” above this point four times in ten seconds (field adjustable), the
following will occur:

 The system is shut down immediately without a NUVA FEEDER cleanout or final line
purge.
 The condition will be alarmed.

7O SILO HIGH LEVEL INDICATOR
This indicates the ash silo is full of ash. As soon as this indication is sensed, all conveying
lines leading to the alarmed silo initiate a NORMAL SHUTDOWN. Unless the silo is
emptied and the high level indication is eliminated, conveying cannot be resumed to that
silo.

7P OTHER ALARMS

 Instrument air pressure LOW
 Vent filter differential pressure HIGH
 Pulse Jet panel FAIL (no ON feedback)
 Silo fluidizing blower FAIL (no ON feedback)
 Silo fluidizing heater OVER temperature (heater temperature is very high)
 Silo fluidizing heater discharge air pressure LOW
 ESP fluidizing blower FAIL (no ON feedback)
 ESP fluidizing heater OVER temperature (heater temperature is very high)
 ESP fluidizing heater discharge air pressure LOW

41. Page 39 of 39 MI-70071-002 B UNITED CONVEYOR CORPORATION

PART 8
SPECIAL START-UP AND SH UT-DOWN PROCEDURES

This DEPAC ash conveyor has been designed to handle fine, dry, free flowing ash. Once the
boiler has reached continuous normal operation, the temperature of the flue gases should be high
enough to maintain the ash temperature such that it is dry and free-flowing.

When the boiler is started up, the temperatures that exist in the boiler are raised gradually over a
period of time. Moisture may accumulate in the hoppers of the ash system due to condensation.
Collection of the ash in the presence of this moisture will cause formation of lumps in the ash and
will prevent free flow. To prevent these conditions, the following procedure should be followed.

Before starting the boiler, the DEPAC system should be placed into operation. The conveyor
should be run continuously during the warm-up period of boiler operation. The continuous
conveyor operation will remove ash as fast as it is deposited, minimizing the soaking up of water
that might be present. When the temperatures have been stabilized and only dry ash is being
collected, the system may be stopped for short periods of time.

During the warm-up period, frequent and periodic checks should be made of the DEPAC vessels.
This inspection should be continued for a day or two after normal system operation has been
established.

The following items should also be checked during this start-up period:

 Compressed air supply must be available and properly adjusted.
 All operating units should be lubricated and checked for operation.
 All hoppers and DEPAC vessels should be checked for debris or crusted and caked ash.
Foreign material must be cleaned out before start-up.

When the boiler is shutdown, the system should continue to be operated until all ash hoppers have
been completely emptied of ash. All hoppers should then be checked for debris, crusted or caked
ash, and foreign material. All hoppers should be cleaned out, as required, to be ready for the next
start-up operation.