Calculations-thermal

12/29/13 COAL BASED THERMAL POWER PLANTS

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This website will provide the most useful technical information about COAL BASED THERMAL POWER STATIONS

particularly for power engineers those are working in thermal power plants-Designed by Er.VENKAT DJ

COAL BASED THERMAL POWER PLANTS

18AUGUST2012

AVAILABILITY BASED TARRIF(ABT)

Availability Based Tariff (ABT) is a frequency based pricing mechanism

for electric power. The ABT falls under electricity market mechanisms to

charge and regulate power to achieve short term and long term network

stability as well as incentives and dis-incentives to market participants against

deviations in committed supplies as the case may be.

ABT Mechanism (Energy policy of India) is adopted in India (ABT Order

dated January 2000 of CERC) and in a few other countries for pricing bulk

power across various stakeholders. ABT concerns itself with the tariff structure for

bulk power and is aimed at bringing about more responsibility and

accountability in power generation and consumption through a scheme of

incentives and disincentives. As per the notification, ABT was initially made

applicable to only central generating stations having more than one

SEB/State/Union Territory as its beneficiary. Through this scheme, the Central

Electricity Regulatory Commission (CERC) looks forward to improve the quality

of power and control the following disruptive trends in power sector:

Unacceptably rapid and high frequency deviations (from 50 Hz)

causing damage and disruption to large scale industrial consumers

Frequent grid disturbances resulting in generators tripping, power

outages and power grid disintegration.

**The ABT scheme has now been expanded to cover the Intrastate systems as

well.

What is availability?

'Availability', for the purpose of the ABT Order means the readiness of the

generating station to deliver ex-bus output expressed as a percentage of its

related ex-bus output capability as per rated capacity.

How is availability calculated?

Availability of thermal generating station for any period shall be the

percentage ratio of average SOC for all the time blocks during that period and

rated Sent Out Capability of the generating station

Each day of 24 hours starting from 00.00 hours be div ided into 96 time

blocks of 15 minutes each.

Each generating station is to make advance declaration of its

capacity for generation in terms of MWh delivery ex-bus for each

time block of the next day. In addition, the total ex-bus MWh which

can actually be delivered during the day will also be declared in

case of hydro stations. These shall constitute the basis of generation

scheduling.

SCHEDULING

NAINI'SSLIDESHOW

2012 (10)

August 12 - August 19 (1)

AVAILABILITY BASED TARRIF(ABT)

August 5 - August 12 (1)

April 8 - April 15 (4)

January 29 - February 5 (4)

2011 (23)

CFPPARCHIVE

CFPP INDEX

POWER GENERATORS

THERMAL BOILERS

AIR PRE-HEATER

BOILER AUXILLARIES

BOILER DRUMS

TURBINE AUXILLARIES

GENERATOR TRANSFORMERS

Types of Safety Valves and its features

THERMALGALLERY

http://www.apepdcl.gov.in

http://www.apgenco.gov.in

http://www.apnpdcl.in

http://www.apspdcl.in

http://www.aptransco.gov.in

http://www.cea.nic.in

http://www.ntpc.co.in

http://www.powergridindia.com

http://www.recindia.nic.in

POWERWEBSITES

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By venkatdj at Saturday, August 18, 2012

While declaring the capability, the generator should ensure that the

capability during peak hours is not less than that during other hours.

The Scheduling as referred to above should be in accordance with

the operating procedures in force.

Based on the above declaration, the Regional Load Dispatch

Centre(RLDC) shall communicate to the various beneficiaries their

respective shares of the available capability.

After the beneficiaries give their requisition for power based on the

generation schedules, the RLDC shall prepare the generation

schedules and drawal schedules for each time block after taking

into account technical limitations and transmission constraints.

The schedule of actual generation shall be quantified on ex-bus

basis, whereas for beneficiaries, scheduled drawals shall be

quantified at their respective receiv ing points.

For calculating the drawal schedule for beneficiaries, the

transmission losses shall be apportioned in proportion to their drawals.

In case of any forced outage of a unit, or in case of any transmission

bottleneck, RLDC will rev ise the schedules. The rev ised schedules will

become effective from the 4th time block, counting the time block in

which the rev ision is advised by the generator, to be the 1st one.

I t is also permissible for the generators and the beneficiaries to rev ise

their schedules during a day, but any such rev isions shall be effective

only from the 6th time block reckoned in the manner as already

stated.

ABT brings about enhanced grid discipline

Economically viable power with right pricing

Promote competition and efficiency

Encourage use of Merit Order Dispatch / Economic Dispatch in India

Addressing grid disturbance issues

Gaming and avoiding the same

Requires special meters, remote metering with open protocols and

communication mechanisms to read meters timely

Software that is comprehensive to do calculations, address

regulatory issues and modifications as per different Regulatory

Commission requirements.

Interface options to various stakeholders in the ABT mechanism

online to enable effective implementation and benefits to all

Capability of power producers to be able to control their cost of

production as well as flexibility in operations

ABT FEATURES

9AUGUST2012

ENERGY & POWER CONVERSIONS

Power & Heat Units

1 MW = 1,000 kW

1 kW = 1,000 Watts

1 kWh = 3,412 Btu

1 kWh = 1.340 Hp hours

1,000 Btu = 0.293 kWh



By venkatdj at Thursday, August 09, 2012

1 Therm = 100,000 Btu (British Thermal Units)

1 Million Btu = 293.1 Kilowatt hours

100,000 Btu = 1 Therm

1 Watt = 3.412 Btu per hour

1 Horsepower = 746 Watts

1 Horsepower hr. = 2,545 Btu

Heat & Energy Units1 KJ = 1,000 Joules

1 MJ = 1,000 KJ

1 MJ = 1,000,000 Joules

1 KJ = .239005 Kilocalories

1 Joule = 0.23901 Calories

1 Calorie = 4.184 Joules

1 Kcal/Kg = 1.8 Btus/lb.

1 Million Btu = 252 Megacalories

1 Btu = 252 Calories

1 Btu = 1,055 Joules

1 Million Btu = 1,055 Megajoules

1 Btu/hour = .2519 Kilocalories/hour

1 Btu/lb. = 2.3260000 KJ/KG

1 Btu/lb. = 0.5559 Kilocalories/KG

Power Generation Units1 MWe = 1,000 kW

1 MWh = 3,600 MJ

1 MWt (thermal energy) = Approximately 1,000 kg. steam/hr.

Natural Gas Units

1 Cubic foot of natural gas = 1,020 Btu (approx)

1 Therm = 100,000 Btu

1 Decatherm = 10 therms

1 Decatherm = 106 Btu

1 Decatherm = 1,000 cubic feet of natural gas (approx)

1 Decatherm = 0.974 Mcf at 1,026 Btu per cubic foot

1 Mcf = 1.026 MMBtu (approx)

1 Mcf = 1.026 Decatherm (approx)

1 MMBtu = 106 Btus

Mass Units1 Metric ton = 1,000 KG

1 Metric ton = 0.9071847 short tons

1 Metric ton = 1.016047 long tons

1 Metric ton = 2,204.622 pounds (lb.)

Temperature

C = (F 32)5/9

F = (9/5)(C)+32

11APRIL2012



By venkatdj at Wednesday, April 11, 2012

SUPERCRITICAL BOILER

Supercritical Boiler

1. Operating Pressure > 225 Kg/Cm2, It Is Called A Supercritical Boiler.

2. The Most Techno-Economical Parameters For Supercritical Plants

Envisaged Are:

Main steam Pressure @ SH outlet is 250 Kg/Cm

540 Deg.C Main Steam Temperature At Sh O/L.

566 Deg.C Hrh Temperature At Rh O/L.

3. Improvement In Cycle Efficiency for above Parameters Is Of The Order Of

3%.

4. There Are Two Types Of Water Walls Arrangements In The Case Of Once

Through Boiler:

A) Spiral Wound WW.

B) Vertical Ribbed WW.

5. Most Of The Once Through Boilers In The World Are With Spiral Wound

WW. This Arrangement Has The Advantage Of Equal Heat Absorption

By All The Steam Generating Tubes.

The Disadvantage Of This Arrangement Is That The Tubes Are Not

Self-Supporting. Hence, Extra Supports Are Provided To WW For This

Arrangement.

Typical Materials Used For Super critical Boiler

Elements Of Boiler Material

Economizer

Carbon Steel

Water Wall Low Alloy Ferritic Steel

Pressure Vessels

(Separator, Drain Tank) Low Alloy Ferritic Steel

Sh Tubes (Heating Area) Austenitic Steel

(Tp347h / Tp321h)

Sh Tubes (Non-Heating Area) Medium Alloy Steel

(T91)

Main Steam Pipe Medium Alloy Steel

(P91)

HRH Pipe Medium Alloy Steel

(Scmv28)

START UP IN THERMAL PLANTS

COLD START1) After Capital overhaul.

2) After Annual overhaul.



By venkatdj at Wednesday, April 11, 2012

3) After any major rectification work like H2 leakage / T-G Bearing High Vibrations

/ Stator winding fault / Rotor earth fault.

WARM START

1) After LTSH, SH Re heater tube leak rectifications.

2) After H2 leakage - Rectification, After Auxiliaries like PA Fan / CW

pump motor rewinding.

3) Reserve shutdown due to High frequency, CW Sump level (River

level) problem.

4) Electrical faults like Surge Capacitor failure / Rotor earth fault /

Stator Earth fault / GT Buchholzs.

5) Coal shortage.

HOT START

1) Economizer tube failure.

2) Water wall tube failure.

3) Turbine impulse line leakage.

4) MS-Valves heavy gland leak.

5) Generator X-r bushing oil leaks.

6) Gland cooler gasket failure (leakages in condensate flow path) ,

Turbine lube oil cooler leaks.

7) Cable flash over of Unit bushes / UAT etc.

8) Small maintenance works on feed water line, de-Aerator etc. /

small fire hazard

9) Start up after fictions tripping (Governing System trouble / I&C

trouble.

10) Start up after trip out due to Mal-operation human error /

Instrument error or relay / Protection, Momentary drum level / draft

/ vacuum.

10APRIL2012

The Health Risks of Burning Coal for Energy

Nitrogen oxides (NOx):

Nitrogen oxide plays a major role in the formation of ground-level ozone

(or smog) in summer and contributes to fine particulate matter (or soot). Both

smog and soot are linked to a host of serious health effects. Nitrogen oxide also

harms the environment, contributing to acidification of lakes and streams (acid

rain) and the haze that often shrouds our national parks and scenic v istas.

Mercury (HG):

Mercury can cause severe nervous system problems in humans and

wildlife. Especially vulnerable are developing fetuses, babies and children.

Eating fish is one of the primary ways people ingest mercury, which

accumulates in the tissues of fish and other animals. Texas is home to five of the

nation's top 10 mercury emitting power plants.



By venkatdj at Tuesday, April 10, 2012

Sulfur dioxide (SO2):

Sulfur dioxide contributes to the formation of microscopic particles

(particulate pollution or soot) that can be inhaled deep into the lungs and

aggravate respiratory conditions such as asthma and chronic bronchitis,

increasing cough and mucous secretion.

Carbon dioxide (CO2) and Global Warming:

Carbon dioxide does not directly impair human health but is the most

significant greenhouse gas that contributes to global warming. The dangers of

global warming include disruption of global weather patterns and ecosystems,

flooding, severe storms and droughts. A warming climate will also extend the

range of infectious diseases.

DUST REDUCTION METHODS IN THERMAL PLANTS

The major methods used in coal mines and thermal plants to control dust

pollution are

Ventilation

Water sprays

Dust collectors

I). Ventilation: The ventilation methods provide the best use of air in the vicinity of

workers and in the vicinity of dust sources. There are different methods

1. Dilution Ventilation:

In this method it is used to provide more air and dilute the dust.

Most of the time the dust is reduced roughly in proportion to the

increase in air flow, but not always.

2. Displacement Ventilation :

In this method it is used to use the airflow in a way that confines the

dust source and keeps it away from workers by putting dust downward of

the workers.

II).Water Sprays :

There are 3 methods

1. Wetting :

By wetting of the coal adequate dust pollution can be controlled. Due to

wetting the dust particles stay attached with surface of coal material.

2. High pressure sprays:

This method improves spray by raising the water pressure which may

further causes to raise the efficiency per unit use of water. In this case there is a

chance to get reduced 30 to 40% dust pollution?



By venkatdj at Tuesday, April 10, 2012

3. Foam:

For dust control foam may be better than water. It provides dust

reductions upto 20% to 60% compared to water. Foam also can produce

similar results at lower water use that is the amount of water needed to make

the foam is less than the equivalent water spray. Only drawback is high cost.

III).Dust Collectors : The dust collectors play a vital role in dust reduction in mining and

coal plants of thermal power plants. Dust collectors range from low-volume

filtration to high volume wet collectors is used in various locations such as

conveyor areas, tunnels, crusher areas and bunker areas. For dust collectors

properly designed to trap respirable dust, the filtration efficiency is usually

quite high in the range of 90-95%.

Methods generally implemented in thermal plants

Location Method implementedCoal transportation Wagons covered with tarpaulins

Wagon tippling Spraying water

Conveyor streams Dust collectors and sprinkling water

Crusher houses Dust collectors

Bunkers Dust collectors

Coal yards Sprinkling water

COMPARISON OF VARIOUS SYSTEMS:

DUST CONTROL METHOD

Effectiveness

(Low is10-30%, Moderate

is 30-50%, High is 50-75%)

Cost and draw

backs

Dilution Ventilation Moderate High

Displacement ventilation Moderate to high Moderate

Wetting Moderate Low

Foam Moderate High

Water high pressure

sprays

Moderate Moderate

Dust collectors Moderate to high Moderate to

high

4FEBRUARY2012

DESIGN REQUIREMENTS FOR CHP

The sizing and selection of the vital equipment i.e.,

crushers,screens,paddle feeders etc. covered under the system shall be

based on the following characteristics of coal and operation conditions :

1. Two conveyors must be established (1W,1S) for smooth running

of plant.

2. Simultaneous running of both conveyors at rated capacity is

essential.



By venkatdj at Saturday, February 04, 2012

3. Round the clock operation of coal handling plant is essential.

4. Coal delivered to the power station shall be of size :300 mm &

below (Occasionally 1-2% coal of 400 mm lumps may be allowed.

5. H.G.I of the coal shall be between 45 to 65.

6. Moisture content in coal will vary between 12% to 15% (For design

purpose 20% is considered)

7. The coal may have max of 20% of shale and sand stone.

8. For volumetric computation the bulk density of coal shall be taken

as 800 Kg/M3

9. All hoppers and tunnels provided with 2 No. sump pumps

(1W+1S)

10. The coal unloading ysystem shall be capable of unloading the rake

within time.

11. The wagon tipplers shall be "ROTA SIDE " type and the angle of

tippling is 150deg by giving 60 deg angle to the side of the wagon

for emptying the coal contents into the hopper.

12. The tippler designed to allow passage of BROAD GAUGE (1676

mm) track over tippler table.

13. The Wagon tippler hopper shall have capacity of 3 wagons i.e.180

tons .

14. The steel grating of mesh size 300mm X 300mm over wagon

tippler hopper.

15. Belt Weigher shall be designed for a range of 20% to 120% of

rated capacity.

16. RING GRANULATORS type crusher shall be provided for sizing the

input coal to (-) 20mm (from 300mm).

31JANUARY2012

COAL CONVEYOR BELT-PROTECTION

The coal conveyor belts in coal handling plant of thermal plants are

protected by following ways

1). PULL CHORD (Manually Reset type) :

This is a emergency stop switch shall be located on both sides of

belt conveyors at a a spacing of 20 Mtr. along the walkways for the entire

length of conveyor for emergency stopping of conveyor.

2). SWAY SWITCH :

This switch is of self resetting type and it shall be provided at a

spacing of 45 Mtr to limit belt sway to permissible extent.

3).ZERO SPEED SWITCH:

This switch is non-contact 9Proximity ) type electronic switch.

4). CHUTE BLOCKAGE SWITCH :



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By venkatdj at Tuesday, January 31, 2012

This switch is of proven type and it shall be provided at a suitable

height on each leg of the conveyors discharge chute, Vibrating Screens

by pass chutes ,Crusher feeding chutes ,Tripper discharge and feeding

chutes nearest skirt boards.

Chute blockage switch shall trip the feeding conveyor in case of

chute blockage and protect the feeding conveyor equipment.


DESIGN OF STOCKPILES

The stockpiles of coal will have adequate storage power plants for few days and the coal

consumption shall be based on the Heat rate and Average GCV of coal received.

PLANT LOCATION COAL STOCK (Requirement)

PIT HEAD 15 Days

LOAD CENTERS 30 Days

COASTAL 30 Days


BELNDING OF COAL

In any coal fired power plants the blending of "Ingenious coal" and

"Imported coal" can be done in following ways

A).We can convey Indian coal through one stream and Imported coal

through another stream which will get mixed while falling into coal

bunkers.

B). We can stock Indigenous and Imported coal layers in

stockyard.Before feeding by using dozers we can blend and feed to the

bunkers.

C).We can use one mill is separately for Imported coal and then adjust

the mill parameters to achieve the optimum heat load of the burners.



TANISHAAQUA

venkatdj

i am an Electrical engineer having an 11 years of real time experience in power generating company and i opt to create own knowledge base

whenever i get new areas of technical experience.

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