Transcript
A PRESENTATION ON
STEAM POWER PLANT
BY:ANKIT RAJEEE,6th sem100210722421CT Institute of technology, jalandhar
INDEX
CHAPTER NO.
CONTENT PAGE NO.
1. INTRODUCTION
2. CLASSIFICATION OF STEAM POWER PLANT
3. LAYOUT OF A MODERN STEAM POWER PLANT
4. SELECTION OF SITE FOR STEAM POWER PLANT
5. COAL HANDLING SYSTEM
6. COMBUSTION SYSTEM
7. ASH HANDLING SYSTEM
8. BOILER
9. FEED PUMPS
10. ECONOMIZER
11. AIR-PREHEATER & SUPERHEATER
INTRODUCTION OF STEAM POWER PLANT
• In india 65% of power is generated by steam or thermal power plant.
• A steam power plant converts the chemical energy of the fuels into mechanical/electrical energy.
video of steam power plant
CLASSIFICATION OF STEAM POWER PLANTS
The steam power plants may be classified as follows:
1.Central stations.
2.Industrial power stations or captive power stations
1) Central stations : These stations is meant for general sale to the customers who wish to purchase it.
2) Industrial power stations : This type of power station is run by a manufacturing company for its own use & its output is not available for general sale.
RANKINE CYCLE PROCESS & LAYOUT
LAYOUT OF A MODERN STEAM POWER PLANT
Description about layout of steam power plant
• The layout of a modern steam power plant comprises of the following four circuits :
1). Coal and Ash handling system
2). Air and gas Circuit
3.) Feed water and Steam flow circuit
4.) Cooling Water circuit
Components of a modern steam power plant:
1. Boiler 2. steam turbine
3. Generator 4. condenser
5. Cooling towers 6. circulating water pump
7. Boiler feed pump 8. wagon tippler
9. Crusher house 10. coal mill
11. Induced draught fans 12. Ash precipitators
13. Boiler chimney 14. Forced draught fans
15. Water treatment plant 16. Control room
17. Switch yard
Essential requirements of steam power plants
1. Reliability
2. Minimum capital cost
3. Minimum operating & maintenance cost
4. Capacity to meet peak load effectively
5. Minimum losses of energy in transmission
6. Low cost of energy supplied to the consumers
7. Reserve capacity to meet future demands
8. Simplicity of design
9. Use of automatic equipment
SELECTION OF SITE FOR STEAM POWER STATION
• The following points should be taken into consideration while selecting the site for a steam power station:
1. Availability of raw material 2. Nature of land
3. Cost of Land 4. Availability of water
5. Transport facilities 6. Ash disposal Facilities
7.Availability of labour 8. Size of the plant
9. Load centre 10. Public problems
11. Future extensions
COMBUSTION SYSTEM general Aspects:
The combustion equipment is a component of the steam generator. Since of heat is the combustion of a fuel, a working unit must have, whatever, equipment is necessary to receive the fuel & air, proportioned to each other & to the boiler steam demand, mix, ignite, and perform any other special combustion duties, such as distillation of volatile from coal prior to ignition.
Basic requirements :
1. Through mixing of fuel & air.
2. Ready & accurate response of rate of fuel feed to load.
3. Practical distillation of volatile components of coal.
4. Adequate control over point formation & accumulation of ASH, when coal is the fuel.
ASH HANDLING SYSTEM
• Burning of pulverized coal in the furnace results in the generation of large quantity of ash . This ash constitutes of 80% fly ash and 20% bottom ash. Fly ash is one of the residues generated in combustion, and comprises the fine particles that rise with the flue gases.
• A station using low grade fuel has to deal with large quantities of ash. Handling of ash includes :
1. Its removal from the furnace.
2. Loading on the conveyers and delivery to the fill or dump from where it can be disposed off by sale or otherwise.
ASH HANDLING CHARACTERISTICS
A good ash handling plant should have the following characteristics :
1. It should have enough capacity to collect the large amount of ash that may be produced in a station.
2. It should be able to handle hot and wet ash effectively and with good speed.
3. The plant should not cost much.
4. The operation charges should be minimum possible.
5. The operation of the plant should be noiseless as much as possible.
6. The plant should have high rate of handling.
7. The plant should be able to operate effectively under variable load conditions.
8. Commonly used equipment: belt conveyor, Trollies or rails cars etc.
ASH HANDLING EQUIPMENTS:
• The commonly used equipment for ash handling in large & medium size plants may comprise of:
1. Bucket elevator
2. Bucket conveyor
3. Belt conveyor
4. Pneumatic conveyor
5. Hydraulic sluicing equipment
6. Trollies or rail cars etc.
CLASSIFICATION OF ASH HANDLING SYSTEM :
The modern ash-handling system are mainly classified into four groups :
1). Mechanical Handling system: This system is generally employed for low capacity power plants using coal as fuel.
2.). Hydraulic system: In this system ash is carried with the flow of water with high velocity through a channel & finally dumped in the sump.
3). Pneumatic system: This system can handle abrasive ash as well as fine dusty materials such as fly ash.
4). Steam jet system: In this case steam at sufficiently high velocity is passed through a pipe & dry solid materials of considerable size are carried along with it.
FLY ASH DISPOSAL SYSTEM
• Burning of pulverized coal in the furnace results in the generation of large quantity of ash . This ash constitutes of 80% fly ash and 20% bottom ash. Fly ash is one of the residues generated in combustion, and comprises the fine particles that rise with the flue gases.
Fly Ash SystemESP
HOPPER
TRANSMITTER VESSEL
FLY ASH SILO
SPOUT/ASH CONDITIONER
CLOSE/OPEN TRUCK
USES OF FLY ASH
• For road construction
• Cement production
• Stabilization of soft soils
• Mine reclamation
• Mineral filler in asphaltic concrete
• Bricks
MAIN PARTS OF ASH DISPOSAL SYSTEM 1. ELECTROSTATIC PRECIPITATOR (ESP)
2. HOPPER
TRANSMITTER VESSEL
BOILER
Boiler is an apparatus to produce steam.
Thermal energy released by combustion of fuel issued to make steam at the desired temperature and pressure.
The steam produced is used for:
1). For generating power in steam engines or steam turbines.
2). Heating the residential and industrial buildings.
3). Performing certain processes in the sugar mills, chemical and textile industries.
BOILER PROPERTIES
a). Safety: The boiler should be safe under the operating conditions.
b). Accessibility: the various part of boiler should be accessible for repair & maintenance.
c). Capacity: Should be capable of supplying Steam according to the requirements.
d). Efficiency: Should be able to absorb a maximum amount of heat produced due to burning of fuel in the furnace.
e). It should be simple in construction.
f). Its initial cost and maintenance cost is low.
g). It should be capable of quick starting and loading.
CLASSIFICATION OF BOILERS
• According to what flows in the TUBE :
a). FIRE TUBE
b). WATER TUBE
a). FIRE TUBE BOILERS
b). WATER TUBE BOILERS
Comparison between Fire-tube & water-tube boilers
S no.
Particulars Fire tube boilers Water tube boilers
1. Mode of firing Internally fired Externally fired
2. Rate of steam production
lower Higher
3. construction Difficult Simple
4. transportation Difficult Simple
5. Treatment of water Not so necessary More necessary
6. Operating pressure Limited to 16 bar Under high pressure as 100 bar
7. Floor area More floor area Less floor area
8. Shell diameter Large for same power Small same power
9. explosion Less More
10. Risk of bursting lesser More risk
MERITS OF WATER TUBE BOILER OVER FIRE TUBE BOILER :
a). Generation of steam is much quicker due to small ratio of water content to steam content . This also helps in reaching the steaming temperature in short time.
b). Its evaporative capacity is considerably larger and the steam pressure range is also high.
c). Heating surfaces are more effective as the hot gases travel at right angles to the direction of water flow.
d). The boiler can be easily transported and erected as its different parts can be separated.
e). The combustion efficiency is higher because complete combustion of fuel is possible as the combustion space is much larger.
f). All parts of the water tube boilers are easily accessible for cleaning, inspecting and repairing.
TYPES OF FIRE TUBE BOILERS
• There are mainly five types of fire tube boilers :
1). Simple vertical boiler
2). Cochran boiler
3.) Cornish boiler
4). Lancashire boiler
5). Locomotive boilers
1). SIMPLE VERTICAL BOILER
• It consist of a cylindrical shell, the greater portion of which is full of water & remaining is the steam space.
• At the bottom of the fire box is grate on which fuel is burnt and the ash from it falls in the ash pit.
• A simple vertical boiler is self-contained & can be easily transported.
2). COCHRAN BOILER
• It is one of the best types of vertical multi-tubular boiler, and has a number of horizontal fir tubes.
• Cochran boiler consist of a cylindrical shell with a dome shaped top where the space is provided for steam.
3). CORNISH BOILER
It consists of a cylindrical shell with flat ends through which passes a smaller flue tube containing the furnace.
• The products of combustion pass from the fire grate forward over the brickwork bridge to the end of the furnace tube.
4). LANCASHIRE BOILER
• This boiler is reliable, has simplicity of design, ease of operation & less operating & maintenance costs.
• It is commonly used in sugar-mills & textile industries where along with the power system & steam for the process work is also needed.
5). LOCOMOTIVE BOILERS
About Locomotive boilers :
• Locomotive boiler is a horizontal fire tube type mobile boiler. The main requirement of this boiler is that it should produce steam at a very high rate. Therefore, this boiler requires a large amount of heating surface and large grate area to burn coal at a rapid rate. In order to provide the large heating surface area, a large number of fire tubes are setup and heat transfer rate is increased by creating strong draught by means of steam jet.
• ADVANTAGE :
a. Large rate of steam generation per square metre of heating surface. To some extent this is due to the vibration caused by the motion.
b. It is very compact.
c. The pressure of the steam is limited to about 20 bar.
WATER TUBE BOILERS ARE CLASSIFIED AS :
1). Horizontal Straight tube boiler
There are two types of Horizontal straight tube boiler:
a. Longitudinal drum
b. Cross drum
there are three types of cross drum boiler :
1. two drum
2. four drum
3. three drum
2). Bent tube boiler
There are one type of bent tube boiler :
a. Low head three drum
BOILER PERFORMANCE
1). Evaporative capacity :
It can be expressed in terms of :
a. kg of steam/hr
b. kg of hour/hr/m2 of heating surface
c. kg of steam/kg of fuel fired
2). Factor of Evaporation
• It is defined as the ratio of the heat received by 1kg of water at the working conditions to that received by 1 kg of water evaporated from and at 100 degree.
FEED PUMP
The feed pump is a pump which is used to deliver feed water to the boiler. It is a desirable that the quantity of water supplied should be at least equal to the evaporated and supplied to the engine.
Two types of pumps which are commonly used as feed pumps are :
1. Reciprocating pumps
2. Rotary pumps
ECONOMISER
• An economiser is a device in which the waste of heat of the flue gases is utilised for heating the feed water.
• Economiser are mainly two types:
a. Independent type
b. Integral type
About economiser
• The above figure shows that an independent type vertical tube economiser. It is also called Green’s economiser.
• It is employed for boilers of medium pressure range upto about 25 bar.
• It consists of a large no. of vertical cast iron pipes p which are connected with two horizontal pipes, one at the top & the other at the bottom.
• Advantage:
overall efficiency of the plant is increased.
AIR PREHEATER & SUPER HEATER
AIR PREHEATER :
The function of the air preheater is to increases the temperature of air before it enters the furnace. It is generally placed after the economiser ; so the flue gases pass through the economiser & then to the air.
• Degree of heating depends upon :
1. type of fuel
2. type of fuel burning equipment
3. rating at which the boiler & furnace are operated
About Air preheater
• There are three types of air preheater:
1. Tubular type
2. Plate type
3. Storage type
• This pic shows that a tubular type air preheater.
Super heater
• The function of a super heater is to increase the temperature of the steam above its saturation point.
• Superheated steam has the following advantages:
1 steam consumption of the engine or turbine is reduced.
2. Efficiency of the steam plant is increased.
• There are two types of super heaters:
1. convective super heater
2. Radiant super heater