Coal Handling Plant

e‐Learning Series                                                                                        Damodar Valley Corporation

Coal Handling Plant

Coal Handling PlantThe purpose of the Coal handling plant in a thermal power plant is toProcess raw coal & insure against the irregular supply of coal which isdependent on many players in the Supply chainThe function of a CHP is to receive, process, store ,feed the Coalbunkers consistently over the entire life of the Power plant.Coal is received from mines in the form of lumps, the sizes varyingfrom 100mm to 350mm, in two types of wagons through Rail; BOBRmeaning Bogie Open Bottom Rapid discharge & BOXN meaning BogieOpen High Sided Side discharge WagonBOBR wagons are unloaded in Track Hoppers & BOXN Wagons areunloaded by Wagon tipplers.Coal is then supplied to the crusher house through Roller screens orVibrating feeders to sieve the coal before feeding to the crusher; 20%of the coal that is received is already <20mm size so this is separated &only larger lumps are fed to the CrusherThe crusher breaks the lumps to sizes<20mm which is the input size tothe coal Pulverizers

Introduction

Coal Handling Plant

The crushed coal is fed to the conveyors in the crusher house throughBelt feeders; Coal is either directly fed to the coal bunkers or to theStacker/Reclaimers for stocking when the bunkers are full;The stacking is done to insulate the plant against the erratic supply ofcoal;CERC allows stocking of 1 ½ months stock of coal for Pit head plantsIn case of non receipt of wagons the coal from the stock pile isreclaimed through the Stacker/ Reclaimers & fed to the coal BunkersTo increase redundancy certain Plants also have Emergency reclaimHoppers near the Crushed coal Stock pile where the dozers are used tofeed coal to the bunkers when the Reclaimers breakdown.Coal is conveyed by means of conveyor Belts in the coal handlingplant

Introduction

Coal Handling Plant

Typical Coal Flow Diagram - CHP

Coal Handling Plant

STOCKYARD

TRACK HOPPER

Crusher House

CHP Control Room

PH

DS Pump House

S&T Control Room

CHP Pump HouseCHP

MCC

Roo

m

STOCKYARD

STOCKYARD

STOCKYARD

Typical Layout of a CHP

Coal Handling Plant

Key Equipments in CHP

Wagon Tippler, Side Arm ChargerTrack HopperStacker Re-claimer Paddle FeederApron FeederHydraulics for S/R, WT, SAC, PFCrusherLT SwitchgearPLC SystemVVVF DrivesLocomotive & Pay loaders

Coal Handling Plant

Weigh Bridge (In-motion Pit-less)

Purpose : To weigh the coal wagons on receipt before unloading into the Track Hopper

Coal Handling Plant

Types of Wagons

BOXN wagons unloaded through Wagon Tipplers BOBR wagons unloaded

through Track Hoppers

Coal Handling Plant

Typical GA of Wagon Tippler

Coal Handling Plant

Wagon tippler & Side arm charger

Side Arm Charger

Wagon Tippler

Dust Suppression system

Coal Discharge direction

WT Control Room

Coal Handling Plant

Wagon tippler

Purpose:To dump coal from BOXN wagons into the underground hopper from where it is transported to the Crusher House.Typical unloading cycle for wagons is approx 3 min i.e. 20 wagons can be unloaded from the Wagon Tippler

Coal Handling Plant

Apron Conveyor/Feeder

Purpose: to reduce direct impact on the conveyor below the Wagon tippler 

Coal Handling Plant

Apron Conveyor/Feeder

Coal Handling Plant 

Side Elevation of Track Hopper

Coal Handling Plant 

Sectional elevation of Track Hopper

Coal Handling Plant

Track Hopper

Purpose: For unloading Coal from BOBR(Bogie open Bottom Rapid discharge)Wagons to Hoppers underneath; This system is preferred to the Wagon tippler asthe evacuation time is less (2 ½ Hrs compared to 5 Hrs for Wagon tippler); A rakeof 58 Wagons could be unloaded in 3 placements in a250m TH within 2 1/2 Hrs

Coal Handling Plant

Paddle Feeder

Table

Cable reeling drumImpact Idlers

Coal Tray

Track Hopper

Curved Paddle Blades

Cable reeling drumImpact IdlersWheels for movement of the Paddle feeder

Purpose: to scoop the raw coal from the table below the Track hopper to therespective conveyor; generally two feeders are provided on each side within aTrack hopper ; when not in use they are parked on either side;

Coal Handling Plant

Paddle Feeder

Cable reeling Drum

Table

Conveyor

Idlers

Curved Blades

Coal Handling Plant

Vibrating Screen

Grizzly Feeder/Vibrating Screen

Coal Handling Plant

Roller Screen

Purpose: Sieving the coal to reduce unnecessary loading on the Crusher; By sieving, the smaller particles (<20mm) are directly fed bypassing the crusher; 

Boiler Tube Failures

Roller Screen

Coal <20 mm size is collected in this hopper & fed on the crushed coal conveyor after the crusher; typically 20‐25% of ROM is collected in this hopper

Coal >20mm is now fed to crusher ; typically 75‐80% of the coal received goes to the crusher

Drive motors for the Rollers

Coal Handling Plant

Ring Granulator

Purpose : To crush Raw coal (size 350mm) to  < 20mm size which is stored in coal bunkers to be fed to Coal Pulverizers. 

Coal Handling Plant

Ring Granulator

Boiler Tube Failures

Drive Pulley

Generally used for feeding the coal from the crusher to the conveyors; these are used to increase the redundancy/flexibility of the conveying system. 

Belt Feeder

Coal Handling Plant

Stacker/Re-claimer

Purpose: To stack the coal after filling the bunkers for future use &reclaim the coal when the coal supply is irregular

Coal Handling Plant

Bucket Wheel Stacker/Re-claimer

Counter Weight

Operators Cabin

Bucket wheel for reclamation

Conveyor Belt

Carriage

Rail

Coal Handling Plant

Typical Conveyor Belting System

Purpose: To convey Coal continuously between the Transfer Points &ultimately to the coal storage silos.

Coal Handling Plant

Typical Conveyor gallery

Purpose: For providing weather proof housing & maintenance space for the conveyorbelting

Boiler Tube Failures

Conveyor Belt

Conveyor

Idlers

Boiler Tube Failures

Conveyor Pulley

These are the drivers of the conveyor Belts; the prime mover is a motor attached through Fluid coupling so that the starting current of the motor is restricted;

Pulley

Plummer Block

Drive Shaft

Rubber Lining

Coal Handling Plant

Impact idlers; they reduce the impact on the conveyor belts thereby increasing longevity; generally used on the tables of the paddle feeders in Track Hoppers or under the coal chutes.

Normal conveyor Idlers ; they are the supporting rollers for the conveyor belt on which the coal laden conveyor belt glides.

Conveyor Idlers

Coal Handling Plant

Metal detectorDetect non magnetic metal pieces & 

heavy iron pieces 

Removal/Detection of Metal Particles

ILMS : Inline Magnetic SeparatorRemove tramp iron & other magnetic 

materials 

Coal Handling Plant

PAY LOADER

Purpose : to stack coal in the stockpile area to be reclaimed by the Stacker/Re‐claimer 

Coal Handling Plant

Dust Suppression

• As the coal Handling plant is prone to fugitive dust it is mandatory to install dust suppression systems in the CHP

• Spraying system: sprinklers are used in the stockpile area to  suppress the dust ; the mechanism is simple; fine atomic particles of water are sprayed on the stock pile & this acts as a blanket 

• DFDS: dry fog dust suppression system: this is used typically at transfer points & hoppers; The  water is sprayed in conjunction with compressed air & these particles adhere to the dust & settle down 

• Dust Extraction system: This is used in Bunker silos where the coal is fed from conveyors & falls from a height; The unsettled dust is sucked through fans installed on the roof through bag filters or cyclonic  separators & the  heavier dust particles are fed back to the bunkers                     

Coal Handling Plant

Dust Extraction System

Coal Handling Plant

Coal Trivia

• Coal provided the energy which fueled the Industrial Revolution of the 19th Century and also launched the electric era in the 20th Century

• Coal provides 26.5% of global primary energy needs and generates 41.5% of the world's electricity

• Total Global Hard Coal Production - 5845Mt (2008e)• Primary source of energy for India; accounts for 55% of Energy

need• Hard coal reserves of India 246 bn Tonnes & proven reserves of

92 bn tonnes; third largest producer of coal• Commercial coal Mining in India started in 1774 in Raniganj

coal field by M/S Sumner & Heatly of East India Company• Indian Coal production - 490 Mt

Coal Handling Plant

Grades of coal

Coal Handling Plant

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