Basic Components of Power Plant

Basic components of power plant

1. Basic Components of Power Plant Group Members: Hassan Ilyas 19013323-030 Hassan Shabbir 19013323-015 Ali Abbas 19013323-001

2. Compressors Compressor is the mechanical equipment which is used toincrease the pressure of the air by reducing its volume. Theyare somehow similar to the pumps both increase thepressure and both transport the fluid through their pipes.

3. Types of compressor on the basis

4. Positive Displacement: The compressors which compresses the air by the displacement of amechanical linkage reducing the volume. Reciporcating Compressor: These compressors use the piston driven by the crankshaft. They can beeither stationary or portable. It can be single staged or multistage and canbe driven by the electric motors or internal combustion engines as well.They are made for intermittent duty.

5. Reciprocating Types Single Acting Compressor: Compressor which compresses the air in one direction only having singlepiston . Double Acting Compressor: It also has just one cylinder but is pipe up such way that its capable of takingin discharging fluids from both ends and hence increases the efficiency. Multistage Compressors: Multistage compressor is simply the compression of the fluid in two or morecylinders instead of one cylinder.

6. 2. Rotary Compressor These compressors does not have any reciprocating motion in fact it hasrotating motion with screws, scrolls, and vanes rotating along side a shaft. Screw compressors: A type of gas compressor that uses a rotary type positive displacement.They are used in place of piston comp where large volume of aircompression is needed and without intermittence. It has a pair of helicalrotors where it traps air, as the rotor rotates in the cylinder. The malerotor and female rotor are being built inside the cylinder for compression.They are generally used in large industrial areas.

7. Scroll/Spiral Compressors: A scroll compressor has one fixed scroll which remains stationary all thetime with another orbiting scroll which rotates through the use of swinglink . When this happens, the pockets of the air are pushed slowly to thecenter of scrolls due to the movement of the rotating scroll causing thereduction of the volume and hence increase in the pressure. Vane Compressor: Rotary vane compressor consists of a rotor with a number of blades inserted inradial slots in the rotor. As the rotor turns, blades slide in and out of the slotskeeping contact with the outer wall of the housing. Thus, a series of increasing anddecreasing volumes is created by the rotating blades. They can be either stationaryor portable, can be single staged or multistage driven by electric motors.

8. b) Rota Dynamic Compressors Compression is carried out by a rotating element which is impartingvelocity to the flowing air or gas and hence developed desiredpressure , and compression is achieved by the dynamic action of rotor. Two major types of dynamic compressors Centrifugal Compressors Axial compressors

9. Centrifuge Compressors: They use a rotating disk or impeller in a shaped housing to force the gasto the rim of the impeller, increasing the velocity. A diffuser or divergentduct converts the velocity energy to pressure energy. Application: Used in stationary service in industries such as oil refineries, chemical andnatural gas processing plants, small gas turbine engines also can be usedin l.C engines as supercharger and turbocharger.

10. Axial Flow Compressors: Axial flow compressors are dynamic compression that use arrays of fanlike airfoils to progressively compress a fluid. They are used where highflow rates or a compact designs are required.The arrays of airfoils are set in rows, usually as pairs: one rotating and onestationary . These rotating airfoils are known as blades transport andcompress the fluidThese compressors can have high efficiency of up to 90%.

11. Cooling Tower A cooling tower is a heat rejection device. It works by bringing air and water into contact to cool the water and release unwanted heat into the atmosphere. Cooling towers are useful in industrial processes because industrial equipment tends to generate tremendous amounts of heat. Facilities need reliable ways to dissipate that heat to keep their working environments cool and reduce the risk of breakdowns and fire.

12. Types of cooling tower: 1. Natural Draft: Natural draft cooling towers utilize no mechanical drivers or fans to create air flow through the cooling tower. This cooling tower takes advantage of the difference in ambient air densities below and above the tower. Air flow is created as the denser air at the bottom of the tower travels to a lower pressure area above the tower. These towers are inexpensive but can only be installed outdoors. Also, these towers have lower reliability as they are more affected by ambient wind and temperature changes.

13. 2. Mechanical Draft: These towers use either single or multiple fans to generate air flow through the tower. Mechanical draft cooling towers are more reliable and stable than natural draft towers since air flow can be manipulated according to the cooling load required. Mechanical draft cooling towers can be further classified as forced or induced draft.

14. Forced Draft: This type of cooling tower uses fans or blowers to force air into the cooling tower. Air flow has high entrance velocity as it is being forced by the blower. As it passes through the tower, air flow slows down. Thus, performance is less stable compared to induced draft towers due to recirculation. Forced draft cooling towers are used in indoor applications where high static pressure is a concern.

15. Induced Draft: T hese have their fans located at the top that draws (or induces) air from the air intake louvers at the bottom or sides of the tower. Contrary to forced draft cooling towers, this arrangement has low entrance and high exit velocity, which results in reduced recirculation. These types of cooling towers are widely used in industrial plants requiring stable performance.

16. 3. Hybrid Draft: Its operation is the same as natural draft towers, but equipped with fans for air flow. Hence, they are also referred to as fan-assisted natural draft cooling towers. The fans in this setup have lower horsepower compared to forced and induced draft fans. Because of the additional draft, there is no need to construct a tall tower which may be economically impractical for a given application

17. Turbines A turbine is rotating part which converts kinetic energy of working fluid into useful mechanical energy or electrical energy. Types of turbine: The 4 types of turbines are- Water turbines Steam turbines Gas turbines Wind turbines

18. Water Turbines This type of turbines is used in hydroelectric powerplants that have water as their working fluid.First of all, millions of litres of water is collected in the dam. More the height of the dam, the more pressure. The highly pressurized water is then made to flow via a large pipe called a  penstock.The turbine is located at the end of the penstock from where the pressurized water strikes the blades of the turbine at high velocity making it rotate. This turbine is connected to a generator which generates electricity. Water turbines are classified into 2 types- Impulse type Reaction type

19. Impulse T urbines: Impulse turbines basically work on Newton’s 2nd law. In impulse turbines, the number of elliptical half-sized buckets are fitted instead of blades on the rotor hub. When water strikes the buckets at high speed, the rotor starts rotating. In short, the kinetic energy of water gets converted into rotational mechanical energy! Thus electricity is generated when one end of the turbine shaft is connected to the generator ! Example  – Pelton turbine

20. Reaction Turbines: The turbine blades or the impeller blades are designed in such a way that a force is generated on one side when water flows through it just like an airfoil. The force produced by an airfoil is responsible for the lift of an airplane. Similarly here, that force makes the blades rotate. Example  – Kaplan turbine Different types of turbines have their own ideal operating conditions. For eg .

21. Pelton turbines are preferred where a low discharge rate can be obtained & high head(80-1600m) is available. Kaplan turbines require a high discharge rate along with low or medium head(2-70m). Francis turbine work on medium flow rate & medium head. Francis turbine is a combination of impulse & reaction turbines. Francis turbines are the most widely used turbines because they offer the highest efficiency & could also work in a wide range of operating conditions.

22. 2. Steam Turbines Steam Turbines are used in nuclear & thermal powerplants  where water is heated to form steam & then flowed through turbines to produce electricity. Alike water turbines, steam turbines are also classified into impulse & reaction types but the arrangement & design is different. All the modern steam turbines are a combination of impulse & reaction type.

23. 3. Gas Turbines Gas turbines are not only used in powerplants for generating electricity but also for propelling airplanes & helicopters. Gas turbines as a whole system has an axial compressor at the inlet. These are sets of rotating blades which suck a huge amount of air & compress it which also increases the temperature. This air is then supplied to the combustion chamber. Fuel is added into the combustion chamber & ignitor ignites the fuel. Thus a large amount of exhaust gases are produced which are made to flow through turbines.

24. 4. Wind Turbines Wind turbines are a boon to mankind- affordable, clean & sustainable! The working of wind turbine is same as other turbines. The rotor has 3 blades & are designed in such a way that when wind flows straight through them, they start rotating. The only problem here is wind turbines rotate at a very low RPM. The low RPM doesn’t produce electricity of required frequency & that is why we require a gearbox which increases the speed of the shaft. The output shaft is then connected to the generator. The 3 primary types of wind turbines are – Horizontal-axis wind turbines (HAWT) Savonius vertical-axis wind turbine ( Savonius VAWT) Darrieus vertical-axis wind turbine ( Darrieus VAWT)