UNDERSTANDING

COAL-FIRED THERMAL POWER

PLANTS

COAL THE SOLID FOSSIL FUEL

THE BASICS OF

COAL-FIRED THERMAL

POWER PLANTS

CALACA

COAL-FIRED THERMAL

POWER PLANT

Plant Name: BATANGAS Coal Fired Thermal Power Plant

Location: SAN RAFAEL, CALACA, BATANGAS

CALACA

COAL-FIRED THERMAL POWER PLANT

CALACA

COAL-FIRED THERMAL POWER PLANT

PLANT GENERAL

Type of Plant Unit System (one Boiler to one Turbine)Unit Output 300MWCondenser Cooling System SeawaterAuxiliary Steam System Taken from another

unit/from own boilerElectricity for start-up Taken from Transmission Line via Station Transformer

CALACA

COAL-FIRED THERMAL POWER PLANT

Turbine Plant

Type of Turbine Reheat Condensing TurbineMaximum Continuous Rating 300 MWRated Speed of Turbine 3600 RPM

Steam Conditions

Pressure at MSV inlet flange 170 ATGTemperature at MSV inlet Flange 538ºCTemperature at Reheats Stop Valve inlet flange 538ºC

CALACA

COAL-FIRED THERMAL POWER PLANT

FLOW CONDITIONS AT 300 MW

Main Steam 923 T/HReheat Steam 768 T/HFeed Water 923 T/H

CHEMICAL ENERGY

HEAT ENERGY

The Coal Handling SystemDelivered from abroad by 65,000-tonner (PANAMAX-size) ocean-going vessel that docks at the Coal Jetty

1. UNLOADING EQUIPMENT transfers coal from vessel to RECEIVING CONVEYOR SYSTEM

2. RECEIVING CONVEYOR SYSTEM transports coal to STOCKYARD VIA ITS STACKER

3. STOCKYARD is where the coal is temporarily stored and sprayed with water to avoid spontaneous combustion when necessary

4. RECLAIMER transfers coal from Stockyard to DISCHARGING CONVEYOR SYSTEM

5. DISCHARGING CONVEYOR SYSTEM transports coal to the COAL BUNKER/SILO

6. COAL BUNKER/SILO to COAL FEEDER, then to MILL or COAL PULVERIZER

7. COAL PULVERIZER to FUEL BURNER

UNLOADING EQUIPMENT

RECEIVING CONVEYOR SYSTEM

RECLAIMER

COAL BUNKER

COAL FEEDER

PULVERIZERSFUEL

BURNER

FURNACE SYSTEMFUNCTION: Where the actual burning of the coal takes

place.

Pulverized burning is the method used of Firing or Coal Burning, wherein, coal is first pulverized then blown into the furnace and actual burning takes place in mid-air of a STEEL BOX.

The System consists of these equipments:

1. MILL is a machine used for grinding the coal to proper size2. EXHUASTER is a fan that blows the coal into the Furnace3. BURNERS are openings in the steel box where the coal enters

the Furnace

Forced Draft Fan

FUNCTION: In order to burn the coal and convert it to heat, there should be a supply for large amounts of air. An AIR COMBUSTION is supplied by FORCED DRAFT FANS. Part of the air (primary air) goes to the MILLS picking up the powdered coal. The rest of the air (secondary air) after passing through the AIR PREHEATER enters the FURNACE through the DAMPERS ( controlled openings).

AIR PREHEATERFUNCTION: Equipment that utilizes some of the heat going to waste up the stack to heat the secondary air before it is blown into the fire in the FURNACE.

Gas or Oil Torch

FUNCTION: Supplies the heat which brings the temperature in the Furnace up to the ignition temperature or the point at which the coal will burn.

Induced Draft FanFUNCTION: Installed just before the STACK to draw the flue gas out of the FURNACE.

ASH HANDLING

EQUIPMENT

Precipitator removes the fly ash from the flue gas by electrostatic means (polarization plates/stages).

Fly Ash Silo

where fine ashes from the KOPPERS of ECONOMIZER. AIR HEATER and ELECTROSTATIC PRECIPITATOR (ESP) extracted by vacuum pump are collected. From there the moistened ash is transported to the ash Pond by trucks. Fly ash can be recycled in the manufacturing of cement.

Clinker Hopperinverted cone-shaped BOTTOM ASH COLLECTOR.

From there the moistened ash is transported to the ASH POND by trucks.

Ash Tank/Binwith conveyor collects slag or bottom ash from the FURNACE proper.

Ash Pondoutdoor disposal area where the fly and bottom ashes

are transported and collected. It consists of perimeter embankment with drainage facilities, regulating reservoir, sedimentation basin and neutralization pit (where waste water is collected and neutralized before discharge into the sea.

HEAT ENERGY

STEAM ENERGY

Boiler

Steam Drum

a. To receive the water and start the circulation by admitting the water to the tubes.b. Supply water surface for steam separation as the mixture of water and stream arise from the tubes and collecting space for steam above the water level .c. to provide an outlet for the steam on its way to the turbine.d. To provide the water column connecting to determine water level and a place to install a boiler pressure safety valve.

FUNCTION: Consisting of one steel drum connected by a number of steel tubes and placed in the furnace so that the hot gases have to pass through the bank of tubes on their way to stack.

Generating Tubes placed directly in the path of the hot flue gases leaving the furnace ,these tubes receive the water from the drum and discharge the mixture of steam and water into the steam drum. In advanced designs, water walls have taken the place of generating tubes.

Water Walls characteristic feature of modern furnace design wherein the generating tubes are utilized not only as walls protecting the furnace walls but serve as important part of the boiler heating surface.

Water Circulation Pumps to force water to circulate in a boiler in order to avoid ‘’hot

spot’’ problems .

Super Heater

Mud Drumwhere boiler impurities are collected and drained through valves.

FUNCTION: Equipment consisting of steel alloy tubes placed in the gas path where the steams after it leaves the drum is further heated to a temperature higher than that associated with the pressure at which it is produced .

STEAM ENERGY

MECHANICAL ENERGY

Turbine

1. First Stage/High Pressure Stage Steamissuing from the nozzle pushes against the blades andcauses the shaft to turn. The steam gives up some of its energy in turning the blades and leaves the first stage at lower pressure and temperature .

FUNCTION: For more complex than a windmill, it consists of stationary and rotating blades mounted on a common shaft and arranged in stages.

2. Second stage /Intermediate Pressure Stage activated by the same steam and gives up some more energy in turning the blades here.

3. Third Stage/Low Pressure stage the same steams enters this stage at a lower temperature and pressure .1/3 of steam energy is given up in the three stages and leaves the third stage as Exhaust Steam .

FUNCTION: Regulates the speed of the turbine or generating unit by either closing or opening the governing valves automatically whenever necessary.

FUNCTION: Function is to close in case of emergency to cut the supply of steam into the turbine.

FUNCTION: are SUPERHEATERS which reheat the steam after it has been through the high pressure turbine and before it passes through the rest of the turbine .Part of he turbine Located in the das path of the furnace near the SUPERHEATER .

GOVERNING SYSTEM

MAIN STOP VALVE

REHEATERS

A large hallow box attached to the exhaust opening of the turbine .In this box are installed rows of small tubes though which cooling Water is circulating causing the conversion of the exhaust Steam back into water for reuse in the boiler (cold reheat ).In the process a vacuum is created which will make the turbine operate more efficiently by providing less resistance to the exhaust steam in its way out.

1.Cooling Water –treated sea water use to condense steam .Slightly heated after performing its work ,this water is then returned to the sea through an open discharge channel.

2.Evactor -pump use for removing excess air leakage from Condenser .Air in the condenser can cause a loss of vacuum (air occupies space ) and use decrease the cooling of the exhaust steam (air will blanket some of the tubes and not allow steam to contact the tubing).

CONDENSER

Schematic

Diagram