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What is the Coal Handling System and What is Its Consist ?

What is the Coal Handling System and What is Its Consist ?

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Coal Handling System in Thermal Power Plant

 

 

The initial process in coal based thermal power plants is coal handling. The function of coal handling plant in thermal power plant is to receive, process, store, feed the coal bunkers consistently over entire life of the power plant. Coal is transported in thermal power station either by railways, roadways or rope ways.

 

Coal Handing Plant In Thermal Power Plant Consist of Following Process in Sequence

 

1.Unloading process

This process involves unloading of coal from BOBR (Bogie Open Bottom Discharge) and Box type wagons. Unloading of BOBR wagons done in Track Hopper and for BOX types wagons unloading of coal is achieved by Wagon Tipler.

 

2.Feeding Process

This process involves continuous or control flow of coal to meet the requirement of coal in bunker. Various types of feeder are used for this process in coal handling plant depending upon the capacity of conveyor belt. In CHP the Paddle feeder/ Apron Feeder/ Belt Feeder/ Reversible Belt Feeder/ Vibrating feeder are commonly used.

 

3.Screening Process

This process involves screening of fine, coarse and wet coal. To achieve the vibrating screen/ Roller screens are used in coal handling plant.

 

4.Crushing Process

This process involves crushing the coal to a size as per requirement of thermal power stations prior to pulverization. Ring granulator type crusher is generally used in coal handling plant to crush the coal.

 

5.Stacking & Reclaiming Process

In stacking process crushed coal are stored in a yard. This process is generally used when boiler bunker level is full.

In reclaiming process the stored coal are reclaimed for sending to boiler bunkers. This process is used when boiler bunker level is low.

 

6.Bunkering Process

This process involves maintaining the level of boiler bunkers. From the conveyor belt coal is discharging into bunkers with the help of tripper trolly.

 

Basic Coal Flow Diagram of Coal Handling Plant in Thermal Power Plant

 

Equipment’s of coal handling plant in thermal power plant

 

1.Track Hopper

They are used to store the coal unloaded by BOBR wagons. The length of track hopper is approx. 210 meter long. Track hopper is made from reinforced cement concrete (RCC) hopper, steel gratings which covering the RCC hopper and two parallel rail track at the center of the hopper.

 

2.Wagon Tippler and Side Arm charger

Wagon tippler are used to unloaded the BOX type wagons into coal hopper. They have a rail table mounted on a rotary support structures which can lift and tilt wagons to an angle of about 135 degree.

 

3.Hydraulic Truck Unloader

The function of hydraulic truck unloader is to unload the coal from truck. They are generally used in coal handling plant where facility of wagon tippler and Track hopper are not available

 

4.Paddle Feeder/ Plough Feeder

 

5.Conveyor System

 

6.Suspended Magnet

 

7.Inline Magnetic Separator (ILMS)

They are provided for continuous and automatic extraction and discharge of tramp magnetic pieces from the point where coal being discharged from conveyors.

 

8.Roller Screens/ Vibrating screens

They are used for screening of fine, coarse and wet coal. The fine coal sizes are less than 20mm.

 

9.Flap Grate

They are provided in transfer chute to channelize the route of coal. They are equipped with electrically operated actuators.

 

10.Rack and Pinion Gate

Rack and pinion gates are used generally to block the coal flow route require during maintenance work. It consists of a gate frame, blade, rack, pinion gear, shaft bearings and a manual or powered shaft drive.

 

11.Crusher

 

12.Belt Feeder/ Reversible Belt Feeder

They are provided with full length impact idlers for absorbing the impact of falling material from crusher.

 

13.Stacker Cum Reclaimer

 

14.Traveling Tripper Trolley

They are used to feed the coal into bunker continuously. The tripper shall have provision for dropping coal both sides of conveyor into the bunker.

 

15.Coal Sampling Unit (CSU)

The function of CSU is to collect the sample of coal at regular interval of time

 

16.Dust Extraction (DE) System

DE system is an air quality improvement system used in coal handling plant to improve breathable air quality and safety by removing dust particle from the air/environment. It works on the basic formula of collection, separation and filtration.

 

17.Dry fog dust separation (DFDS) system

They are used to control the fine dust particle produced during the coal flow. DFDS system uses high pressure of air (about 3-4 bar) and low pressure of water (about 2-3 bar), which generates dry fog and being sprayed at the point of dust generation. The spray angle covers 30 to 90 degree.

The nozzle of DFDS system are fitted at discharge and tail side of conveyor belt.

 

18.Belt scale

Belt weigh scale are used for measurement of coal flow rate and quantity.

Other equipment’s like pneumatic system, hydraulic system, thruster brake, monorail with hoist, pumps, compressors etc are used in coal handing plant.

Generally E and F grade coal are received in thermal power stations, Grades of coal and their respective calorific value are listed below.

 

Typical coal flow diagram of coal handling system in thermal power plant

 

Types of plant maintenance done in coal handling plant

 

1.Preventive maintenance

It involves the systematic inspection of equipment where potential problems are detected and corrected in order to prevent equipment failure before it happens. Maintenance schedule is based on a time or usage trigger.

 

2.Breakdown Maintenance

Breakdown maintenance is maintenance performed on equipment that has broken down and is unusable.

 

3.Corrective maintenance

It is a maintenance task performed to identify, isolate, and rectify a fault so that the failed equipment/ machine/ system can be restored to their original operation condition.

 

4.Predictive Maintenance (condition monitoring)

It is a maintenance involve regularly monitoring the status and operational capacity of the equipment or machine by knowing the values of certain variables (temperature, vibration, power consumption, sound, etc).

 

5. Shutdown maintenance

It is maintenance that can only be performed while equipment is not is use.