In Boiler the Primary fuel used is Pulverized Coal.

After burning of Pulverized Coal in Boiler the Residue in the form of Ash is generated.

80-85% of Generated Ash is carried with Flue gas and about 15-20% of is collected in the Bottom of the Furnace.

Fly ash having a size of about 1mm, in Flue gas is separated and collected in Electrostatic Precipitator, where as Bottom ash with a size of 25 mm, is collected in Bottom Ash hoppers below the Furnace.

Ash Handling System is for the Collection, Handling and Disposal of this Ash.

Introduction

BASIC DESIGN CRITERIA

Sr. No Description Design Basis Qty / Unit (TPH)

1 Coal Indonesian Bituminous

2 MCR Coal Consumption (worst coal), TPH per unit 342

3 Design Ash content (worst case) 15%4 Ash Content Variation (%) 14%5 Total design Ash qty per unit 51.36 Design bottom ash qty per unit 20% 10.26

7 Design fly ash qty per unit 80% 418 Plant Load factor 85%

9 Total Fly ash qty per day per unit (avg.)

(= 342 x 0.15 x 0.8 x 0.85) 836TPD

10 Total Fly ash qty per day for 5 Units   4180 TPD

Block Diagram

Furnace

Buffer Silo

Ash Pond

Fly Ash Slurry Sump

Fly Ash Silo

Bottom Ash Slurry

Sump

Bottom Ash

hopper

ESP

Recovery Tank

Clarifier

Sludge Pit

Flash Mixer

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Basic Arrangement

• Evacuation, Transportation and Disposal of Fly Ash is in two stages.

• Capacity of Fly Ash Handling System is 100 TPH.

• Fly Ash Handling System is common for all 5 units.

• Fly Ash Handling System is designed to evacuate the ash generated in a shift of 8 Hrs from the Ash hoppers in about 4 Hrs.

Fly Ash System

ESPHoppers24 Nos

ESPHoppers24 Nos

ECO. Hoppers

6 Nos

APH Hoppers

4 Nos

Buffer Hopper4 NosA1/2 - B1/2 Fly Ash Silo

3 Nos1500 T each

To Closed Tanker

To Open Truck

Fly Ash Receiving

TankFA Water Pump3 Nos (2W + 1S)295m3/hr

Vacuum Pumps3 Nos (2W + 1 S)2980 m3/hr

From Other Units

FA Water Tank, Cap. 382cumFrom

makeup Water

Transport Air Compressor4 Nos (3W + 1S)6500 m3/hr

FA Seal Water Tank

Cap 67cum

HMDC Water Pump4 Nos (3W + 1S)35 m3/hr

FA Slurry seal water pumps2 Nos (1W + 1S)30 m3/hr

Atmosphere

Air Lock Tank

8 Nos

Flow Ejector2Nos / Silo

Service Water

To Slurry Pumps

From Clarifier

Recovery Water Tank

485 m3

Clarifier

Sludge Pit

Fly Ash Slurry Sump50 m3 each

Fly Ash Slurry Pump6 Nos (4W + 2S)330 m3/hr

Ash Pond I

Ash Pond II

Recovery Water Pump2 Nos (1W + 1S)900 m3/hr

Sludge Pump2 Nos (1W + 1S) 25 m3/hr

Chemical Dosing

Partial Flume

Flash Mixer

From FA Seal Water

Tank

Stilling Pond

To FA Water Tank

Hoppers

• There are 48 no. of ESP Hoppers,4 no. of APH hoppers and 6 no of Eco. Hoppers.

• Each Fly Ash hopper is provided with One no. Electro-pneumatic operated Material Handling Valve

Vacuum Settings for Ash Evacuation from Hoppers* >260 mm Hg (Vacuum) Requirement For Hopper Open Command.* <160 mm Hg (Vacuum) Requirement For Hopper Close Command.* >450 mm Hg (Vacuum) Line Chocked Command is released.* >500 mm Hg (Vacuum) Vacuum Breaker valve opens.

Buffer Hoppers

Reverse Pulse Jet type Bag filters are used to separate Fly ash from Air Ash mixture. These are placed on top of Buffer silo and are cleansed continuously during operation by pulsating air.

Differential Pressure Across Bag Filter:* >1000 mmWC – Indicates Bag Filter is Chocked.* <100 mmWC – Indicates Bag Filter is Damaged.

Air lock Tanks are used to Transport FA to Silos by Dry Pneumatic Pressure Conveying System. Two Air lock Tanks are provided per Buffer Hopper.

When one Air Lock Tank is under Loading the other will be Unloading.

From Air cooled fluidising blowers

Using Vacuum Pumps, Vacuum is generated.

Ash From Hoppers

To Dry Fly Ash Silo

Bag Filter

Buffer Hopper

Air Lock Tank

Bottom Ash System

• Capacity of BA system is 90 TPH

• The Free falling ash from Boiler Furnace will be collected in W shape water impounded Hopper for periodic removal.

• Removal is once in a shift of 8 hrs. per unit.

• Quenched BA having over sized clinkers get crushed in the Clinker Grinder.

• BA mixed with water forms BA Slurry which is conveyed to BA Slurry sump through Hydro-ejector.

• BA would be removed once in a shift of 8 hrs in approximately 60 min. including flushing for 12 min.

BALP4 Nos(3W + 1S)290 m3/hr

BAHP3 Nos(2W + 1S)380 m3/hr

BA seal Pump2 Nos(1W + 1S)90 m3/hr

BA Slurry Sump

BA Water Seal Tank Tank

Cap. 600 CM

Cap. 45 CM

Clinker Grinder2 Nos (1W + 1S)

BA Slurry Pump6 Nos (3W + 3S)515 m3/hr

From make up water

From Surge tank

Service water

Ash Pond Ash Pond I II

46 m3 each

ASH

Bottom Ash Flow

Hydro Ejectors

Bottom Ash Hopper82.4 TGross Cap: 127 m3

BA Overflow Tank

Cap 25m3

Settling Tank

Surge

Tank

BA Overflow Pump 2 Nos (1W +1 S)

Sludge Pumps2 Nos (1W+1S)Cap 25 m3/hr

ELECTRICAL SUPPLY

The supply for the system comes from 6.6kv Station Aux. SWGRs.

It includes:

• 6.6KV Supply for Transport Air Compressor.• 6.6 KV / 415 V, 2000KVA Main Plant Area Transformer• 6.6 KV / 415 V , 2000 KVA Silo Area Transformer • 6.6 KV / 415 V, 500 KVA Recovery water Pump House Transformer

Water Requirement For System

• Makeup water will be taken from CW Headers using Four Make Up Pumps • Make up water will be added in the Fly Ash water tank and Bottom Ash Water

Tank.

• Fly Ash Pumps are provided in FA water Pump House for supplying water to Feed Ejectors near the Silo.

• HMDC Pumps and FA Slurry Seal Water Pump take suction from FA Seal water tank. • Water requirement for Sealing in BA System is taken care of from BA Seal Tank. • For water requirement in BA Hopper and for slurry conveying, BALP and BAHP pumps are provided which take suction from BA Water Sump. • Total water requirement for BA is estimated to be 427Cu.M/h.

• Total Water requirement for FA is estimated to be 569 Cu.M/h.

• Bottom Ash of All Five Units and Un-utilised Fly Ash will be disposed in Ash Pond.

• Total 143 Hectors of Land is Identified as Ash Disposal Area.• 72 Hector of this land is planned to be utilised for Ash Pond.• Ash Pond is in two Stages.• Initially Ash Dyke is of 6Mtr, and further will be raised by 3m each in three

phases.• The Final height of ash dyke is envisaged to be 15 m.• The size of the ash pond is so designed that if 100% of all the ash

generated is deposited in the pond, it will take 6 years to fill it completely.

ASH POND

Sr No Description Unit BA Slurry Pump

FA Slurry Pump

BA Overflow

Pump

1 Manufacturer Indure Make

2 Type Centrifugal Flooded Suction

3 Rated Capacity

M3/hr 515 330 145

4 Head Mwc 45 55 33

5 Rated Speed rpm 1030 1070 1180

6 Max. Speed rpm 1133 1177 14167 Min. Speed rpm 557 589 944

Sr No. Description Transport Air Compressor

1 Manufacturer Atlas Copco

2 Model ZA – 6M – 200

3 Type Oil Free Screw

4 Capacity 6625 m3/hr

5 Min. Discharge Pressure

2 Kg/cm2

6 Discharge temp 160o C to 180o C

7 KW Input Required 341 KW

Sr No. Description Unit Vacuum Pumps

1 Type Liquid ring Type

2 Make NASH (USA) / Siemens

3 Type Of Coupling

Direct Drive

4 Capacity m3/hr 2800

5 Pressure kg./cm2 14

6 Average Tonnage Rate

TPH 56

Sr No.

Description Unit Ash Disposal Jet Pump

1 Location Below Clinker Grinder

2 Max. size of ash particles to be handled

mm 25 for Botom Ash01 for Fly Ash

3 Design Rate for ash conveyance

TPH 30 below Bottom Ash hopper

4 Water Quality Sea Water

5 Pump Flow m3/hr 225

6 Head mwc 16.5

7 Nozzle FlowNozzle: 102 mm X 28

mm

m3/hr 158

8 Head mwc 82

Sr No Description

Unit BAHP Water Pump

BALP Water Pump

BA Seal Water Pump

Sludge Pump

1 Manufacturer

Mather & Platt Pumps Ltd

2 Type HSC ESTD Multistage

3 Model 150 / 200 DST

PN ISO 29

100 /125 IPB

4 Rated Capacity

M3/hr 380 290 90 25m3/hr

5 Head Mwc 111 20 127 10mwc

6 Rated Speed

rpm 1488 1480 1475 1430

7 Efficiency at rated speed

% 82 85 77

Sr No

Description Unit FA Water Pump

HMDC Water Pump

FA Seal Water Pump

Recovery Water Pump

1 Manufacturer

Mather & Platt Pumps Ltd

2 Type HSC ESTD Multistage VT

3 Model 150 / 200 DST

ET ISO 26

RN 65 X 7 CH

12 VMF

4 Rated Capacity

M3/hr 295 35 30 900

5 Head MWC 109 54 78 35

6 Rated Speed rpm 1485 2920 1415 1485

7 Efficiency at rated speed

% 80 65 73 84

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