Diesel Power Station

An alternator requires the mechanical energy as input further it is converted into electrical energy by it. In case of diesel power station, diesel engine acts as a prime mover which obtains its energy from a liquid fuel known as diesel oil and converts this energy into mechanical energy further which is provided to the alternator which is mounted on the same shaft as that of diesel generator. In case of diesel engine heat required for combustion of fuel is obtained by compression of air in the engine cylinder and then the fuel is injected in engine cylinder. The main difference between diesel power station and steam power station is that, in diesel power station, mechanical energy is generated using direct combustion of fuel under use, and in case of steam power stations first combustion of fuel under use is utilized to convert water into steam and then the steam at high pressure and temperature produces the mechanical energy. Diesel power plants are more advantageous than any other heat engine in the view of initial cost, quick starting and stopping time also, it doesn't require any warming up period. Therefore stand by losses are not present and hence has found increasing applications either as continuous or as a peak source of electric power.

Diesel Power Station (Source - Doosan.com)

Although steam power stations and hydroelectric power plant are invariably used to generate bulk power at cheaper costs, yet diesel power stations are finding favour at places where demand of power is less, sufficient quantity of coal and water is not available and the transportation facilities are inadequate. This plants are also standby sets for continuity of supply to important places such as hospitals, radio stations, cinema houses and telephone exchanges.

Block Diagram of Diesel Power Station

Essential element of Diesel Power Plant :-

1. Engine:- Engine is the main component of the diesel power plant, which develops mechanical power. Generally engine is directly coupled to the alternator. Internal combustion engine are used. An internal combustion engine is that produces power by burning fuel inside a combustion chamber within the engine. The fuel burns and the burnt fuel expands to do work on the moving part inside the cylinder called piston. This movement of piston rotates the flywheel and the engine is directly coupled with the generator. The gases after the expansion inside the chamber is exhausted into the atmosphere and passes through a silencer in order to reduce the noise.
2. Fuelling System:- It consists of storage tank, strainers, fuel transfer pump and all day fuel tank, heaters and connecting pipe work. To make the oil free from impurities it is passed through the strainers.The fuel oil is supplied at the plant site by rail and road. Heaters for oil may be required in winter season to heat the oil. Fuel is fired into the engine through fuel filter and fuel injection pump.
3. Air Intake System:- This consists of air filters, ducts and super charger.This system supplies necessary air to the engine for fuel combustion. It consists of ducts/pipes for the supply of fresh air to the engine manifold. Filters are provided to remove dust particles from the atmospheric air which is intended to supply to engine. 

   

   Air Intake System

4. Exhaust System:-  Exhaust system includes connecting ducts and silencers. This system leads the engine exhaust gas outside the building and discharges it into atmosphere. A silencer is usually incorporated to reduce the noise level. The exhaust system of the diesel power station performs three functions. First system, the exhaust system routes the spent combustion gases away from the engine, where they are diluted by the atmosphere. This keeps the area around the engine habitable. Second the exhaust system confines and routes the gases to the turbocharger, if used. Third, the exhaust system allows mufflers to be used to reduce the engine noise.
5. Cooling System:- Cooling system includes water circulating pumps, cooling towers or spray ponds and water filtration plant. The heat released by burning of fuel in the engine cylinder is partially converted into work. The remainder part of the heat passes through the cylinder wall, piston, rings etc. and may cause damage to the system. In order to keep the temperature parts of engine within the same operating limits, cooling is provided.
6. Lubricating System:- Lubricating system includes the oil pumps, oil tanks, filters, coolers, purifiers and connecting pipe work. Lubrication system reduces the friction of moving parts and reduce the wear and tear of the engine parts. The lubrication oil is drawn from the lubrication oil tank by the pump and is passed through filter to remove impurities. The clean lubrication oil is delivered to the points which require lubrication.

   

   Lubricating System (Source-IGNOU)

7. Engine Starting System:- Engine starting system includes storage battery compressed air tanks, self starters etc. The function of starting system is to start the engine from cold condition. The system enables the engine to route initially while starting until the firing starts and the unit runs on its own power.
8. Governing System:- The function of the governing system is to maintain the speed of the engine constant irrespective of the load on the plant. This is done generally by varying fuel supply to the engine according to the load. 

Major Components of Diesel Engine

To supply the diesel power station it is worth to know about the diesel engine i.e., its construction and working.

1. Cylinder:- It is the part of diesel engine in which combustion of fuel is taken place and power is developed. Therefore it is known as heart of the engine. Cylinder has consists of valves through which air and fuel are admitted and exhaust gases are discharged.
2. Piston:- Power developed by the burning of the fuel is transmitted by the piston to the crank shaft. Distance travelled by the piston from one end to another end is known as. Gas tight seal is required between piston and cylinder liner which is provided by the engine oil lubricated piston rings. 
3. Connecting rod and crankshaft:- Connecting rod mechanically connects the piston and crankshaft which transfers the mechanical power developed by the piston to the crankshaft. Thus mechanical power generated can be taken out from the crankshaft. 
4. Fuel Nozzle:- Fuel is delivered by the fuel nozzle in fine spray under pressure in diesel engines.  It mainly consists of fuel pump, fuel line and the injector.
5.  Camshafts:-  Camshaft is driven from the crankshaft by a timing gear on a chain. It mainly operates the intake valve and the exhaust valve through cam, cam followers, pushrods and rocker arms. 
6. CrankCase:- Crankcase holds the cylinder, piston and crankshaft.
7. Flywheel:- Fluctuations of the cyclic variations in speed is reduced by flywheel. It stores energy during power stroke and releases during the other stroke. Thus a constant torque is obtained at output.

HydroElectric Power Station

Energy is required for the overall progress. The natural resources of any country may be large but they can only be turn into wealth  if they are developed, used and exchanged for other goods. This cannot be achieved without energy. The hydro sources are used to generate electrical energy where water resources are available in large quantity.

Adam Beck Complex

A generating station which utilizes  the potential energy of water at a high level for the generation of electrical energy is known as hydroelectric power station. The energy of water utilized for hydroelectric power generation may be kinetic or potential. Kinetic energy of water is its energy in motion and is a function of mass and velocity while potential energy is a function of the difference in level of water is between two points. In either case the availability of water is a basic requirement. For this purpose water collected in natural lakes and reservoirs at high altitudes may be made use of or water may be artificially stored by constructing dams across flowing streams. Hydro power is considered to be a renewable energy source because it uses the continuous flow of water to rotate the turbine. 

Working 

Layout of Hydroelectric Power Station

In hydroelectric power generation, the water either stored in dam or flowing is made to fall on the turbine blades. The kinetic or potential energy of water rotates the turbine blade. The turbine is coupled with alternator or DC generator. The kinetic or potential energy of water is converted into mechanical energy. We know the basic law that mechanical energy can be converted into electrical energy. Implicating this law the mechanical energy from turbine is converted into electrical energy by the alternator. The generated electrical energy is fed to the transformer and busbar section of the power plant. Then this is stepped up and transmitted to substations via transmission lines. This is the most basic( conversion of some form of energy into mechanical energy and then its converted into electrical energy by alternator/generator) of any power plant either its nuclear/thermal or hydro, etc.

Main function or selection criterion for erecting hydroelectric power plant

1. Quantity of water available :- Water is the primary requirement of hydroelectric power plant and the availability of huge amounts of water has the most important and greater impact in the generation of electric power. The availability of water can be estimated by using various method, for example by measuring the stream flow over a period as long as possible. By collecting and analysing the previous records of rainfall and minimum and maximum quantity of water available during the year. The losses which may occur  due to evaporation and percolation  is calculated and the net volume of water available for power generation can be determined.
2. Storage of Water :- We know that the rain does not fall all the time throughout the year (fun fact). So its necessary to store the water by building a dam in order to ensure the availability of water throughout the year for power generation.Storing water has many advantages. The storage helps in equalizing the flow of water so that any excess quantity of water at a certain period of the year can be made available in times of very low flow in the river.
3. Head of Water :-Availability of head of water has considerable effect on the cost and economy of the power generation. The topography of the area selected for installing the power station is responsible for the available water head.
4. Cost and type of land :- The bearing capacity of the ground should be adequate to withstand the weight of heavy equipment to be installed. The cost of land available for power plant must be available at reasonable cost. And last but not least the selected should be away from earthquake centers.
5. Near to load centers :- Owing to minimize the transmission cost the site selected for hydroelectric power station should be located near to load centers. 
6. Transportation facility :- For the transportation of machinery and equipments the power station should be efficiently connected with rail and road. 

Major Components of Hydroelectric Power Station 

Reservoir , Dam, trash rack, forebay, surge tank, penstock, spillway are some some of the important component of hydroelectric power station. The power house itself has prime movers and generators in addition to the above mentioned components.

1. Reservoir :- The purpose of reservoir is to store water which may be utilized to run the prime mover to produce electrical power. It is the basic requirement of hydroelectric power station. A reservoir store water during the rainy season and supplies the same during dry season.

   

   Reservoir - Taum Sauk Hydroelectric Power Station

2. Dam :- A dam may be considered as a large storage bay where water is stored to provide water head. Dam is a barrier; it is built of concrete or earth or rock fill.  

   

   Upper Wardha Dam

3. Trash Rack :- The purpose of trash rack is to prevent entry of debris or material which might damage the wicket gates and the turbine runners or mean checking of nozzles of impulse turbine.

   

   Trash Rack

4. Forebay :- The forebay is similar to reservoir but it is built in small manner. It serves as a regulating reservoir storing water temporarily when load on the plant is increased or reduced. In short it may be considered as the enlarged body of the water just before the intake. 
   
5. Surge Tank :- To protect the penstock from abnormal pressure surge tank is open at the top and is located near the beginning of the penstock. When the load is steady on the alternator, turbine run swiftly and there is no surge in the flow water through penstock. It can be understood by considering that, when the load is steady the quantity of water flowing through the penstock is sufficient to drive the turbine and meet the load demand. However when the load on the alternator increases or decreases suddenly the governor has to close the gates of the turbine to reduce or increase water supply to the turbine but due to certain time lag the water pressure in the penstock increases or decreases, this may damage the penstock. For avoiding this abnormal condition the surge tank is provided to maintain the flow of water and the pressure in the penstock by increasing or decreasing the water level.



Surge Tank and Penstock

6. Penstock :- It is a conduit system which controls the flow of water and for taking water from the intake and forebay to the turbine. The penstock pipes are generally of steel for high and medium head plants, they may be of concrete in low head plants. The diameter and cross sectional area of penstock pipe is dependent on the velocity of water and pressure of water. It is a gate or an enclosed pipe which delivers water from valve house to power house ( hydro turbines ).

Nuclear Power Station

Modern world requires large quantity of power at cheap cost. Industrialization and the gradually increasing living standard of human beings has increased to such an extent that the required energy becoming thrice in decade. Nowadays this required demand of power is fulfilled by major contribution of fossil fuels such coal, oil, etc. The studies had estimated and proved  that stock of these fossil fuels will no longer be sufficient and available to fulfill the very fast increasing demand of energy as the reserves of these resources in the world are limited and these will be exhausted soon.With the vision of increase in demand power, an important source of prosperity. For this we need to understand the atomic physics.

Modern World Electricity Requirement - A view from Shanghai

 Atomic Physics

An atom is the smallest particle of a chemical element that can exist. An  atom can be visualized as the tiny solar system of which the the matter is composed. An atom consists of positively charged nucleus surrounded by number of negatively charged electrons. The nucleus contains two types of particles, namely protons and neutrons. Each proton carries unit positive charge while neutrons are uncharged or neutral particles.A normal atom is generally electrically uncharged due to the fact that the number of electrons on the orbits is equal to the number of protons in the nucleus. Thus any addition of electron to the neutral atom makes atom, negatively charged. While recombination of electron to an atom it absorbs energy. Similarly any subtraction of electron will make the atom positively charged, while liberating an electron from atom it releases some energy.This is the most basic of Nuclear Power Generation which we should learn proficiently if we want to gain knowledge of Nuclear Power Station. 

Nuclear Fission

When an unstable heavy nucleus is bombarded with high energy neutrons then it splits into two elements of lower mass number. It also releases huge amount of energy with separation of two or three neutrons at high speed ( 2 × 10⁷ m/sec ). This process is known as fission and the two elements which have separated due to fission have smaller mass number and called as fission products.The fission is always associated with the release of tremendous amount of heat energy which is very important for power development.

Chain Reaction

We already discussed on the above paragraph that how fission take place so now we will discuss about the Chain Reaction. When a slow moving neutron is bombarded on the fuel rods which splits the atom into two parts usually negatively charged electron and two or three neutrons.Each fission ed nucleus ejects two or three neutrons which again hit the remaining fuel and accelerate the splitting process. While separating the electrons, energy is released by the atom. If this process is continuous then it is known as chain reaction.

Working of Nuclear Power Station

Nuclear Power Station (Tarapur)

In nuclear power plant, Uranium U²³⁵ or Thorium T²³² takes the place of oil, coal and gas to be the fuel used to heat water and produce steam.A nuclear reaction (Chain Reaction) occurs when Uranium atom splits into smaller particles in a chain reaction that produces large amount of heat.The heat producing fission process is controlled in reactors. The core of the reactor contains the Uranium fuel. The fission process take place within the fuel assemblies in the reactor and fuel is shaped and located in such a manner that the heat production within the reactor is uniform.The reaction is controlled by control rods.Control rods, located inside the fuel assembly are made of material which absorb neutron. In addition to control rods, operator use Boron dissolved in the coolant to absorb neutrons to the fission process. The nuclear energy released by fission heats the water or coolant that flows through and the fuel assemblies. In nuclear plants the coolant prevents the core of the reactor from becoming excessively hot and also carries heat energy from the reactor to steam turbine. In nuclear power plant, a vessel known as a pressure keeps the primary side at high temperature to prevent the boiling yet allowing water temperature to reach 500℃. Heat from the primary side water is transferred to the secondary through the steam turbine. Since the secondary water is at a lower pressure than the primary side, the secondary side water boils and steam become steam which rotates the steam turbine.

Main Components of Nuclear Power Station

Nuclear Reactor

1. Reactor Core :- The reactor core is that part of nuclear power plant where fission chain reaction is made to occur and where fission energy us liberated in the form of heat for operating power conversion equipment. The core of the nuclear reactor consist of an assembly of fuel rod, control rod, coolant and moderator. The fuel element are made of plates or rods of Uranium or Thorium.
2. Reflector :- A  reflector is usually a plate around the core to reflect back some of the neutrons that leak out from the surface of the core.It is generally made of same material as the moderator.
3. Control rods :- It is also known as control mechanism used to start the nuclear chain reaction when the reactor is started from cold. The chain reaction should be maintained at steady state condition at the required level. It is also use to shut down the reactor automatically under emergency condition.
4. Moderator :- The moderator is a material which reduces the kinetic energy of fast neutron to slow neutron and this is done in a fraction of second.The function of moderator is to increase the probability of reaction.
5. Coolant :- The main purpose of coolant in the reactor is to transfer the heat generated in the reactor to heat exchanger where steam is generated.
6. Shielding :- The reactor is a source of intense radiation activity and these radioactive produced are very harmful to human life. Hence the reactor is shielded. The common radiation from the reactors are α rays, β rays, γ rays and fast electrons.

Geothermal Energy Sources

Hot Spring

Geothermal energy is clean and sustainable source of energy. Heat obtained from the earths crust can be used in many ways, from large power station to relatively small pumping system.Resources of geothermal energy is found in shallow ground to hot water and hot rock found few miles beneath the earth.
The energy present in the earth's crust which is in the form of heat such energy is called geothermal energy.
The uppermost crust up to 10 km or so of the earth's crust constitutes a potentially useful and almost inexhaustible source of energy.

Heat Extraction

In the above  representation of geothermal energy, at depth of 5-10 km or so lies impermeable magma and the magma are impermeable crystalline rocks which are overloaded by pockets of permeable rock . This localized pockets are founded by the fracture zone or faults around which some relative motion of rock has occurred.
Water is circulated along with the fault lines and moves in the earth's interior path. It is heated by permeable rock or layer which is in term heated by conduction of heat from the magma. The hot water comes out through another fault and forms a hot spring.
Availability of Geothermal Energy:-

Depending on the temperature and depth of the the permeable rock the natural hydro thermal systems can be divided into three categories:

1. Dry Steam System:- The temperature of permeable rock is very high. The whole of the water is converted into steam which is converted into steam which gets superheated by the time comes out on surface.
2. Wet Steam System:- The temperature of permeable rock is not very high.By the time water comes out on the surface only a part of it is get converted into steam therefore the eruption gives a water-steam mixture. 
3. Hot water System:- The temperature of permeable rock is rather low, therefore the surface eruption provides hot water. 

Vapour Turbine Cycle

Vapour Turbine Cycle

Recently in Geothermal plants heat exchanger and vapour turbine cycle have been proposed for generation. The geothermal hot water is used to heat for low boiling point fluids (Propane/Freon). This fluid expands in turbine which drives the generator. The fluid is condensed and reused to form a closed circuit system in vapour turbine cycle system. The low enthalpy geothermal water can also be profitably used.
It should be noted that electricity generated by California based Geothermal Power Plants(USA) is almost half of electricity generated by Geothermal Power Plants.

Geothermal Electricity Plant - California (USA)

Geothermal energy is also used for heating purposes.There are many examples of direct using of geothermal energy for heating purposes as for drying out fish, to heat greenhouses, for improving oil recovery, fish farms, etc. Around the world, people also used hot spring for relaxation and rest.

Advantages:

Geothermal energy has many advantages as follow:

1. Reliability:- Unlike other Non Conventional energy sources such as Wind, Tidal and Solar, Geothermal energy is reliable as it provides constant power.
2. Geothermal energy is environment-friendly. There is a very less or we can say no pollution is produced by Geothermal Plant. Although fumes are not produced while drilling the earth. Therefore there is no adverse effect on environment.
3. The pollution can be reduced somewhat by increasing use of Geothermal as well as other non conventional energy sources which is caused by use of many conventional fuels like oil, coal, etc.
4. Geothermal energy has many application. For instance it can be used to generate electricity as well as for providing heat to home and businesses. 

Magneto Hydrodynamic Generation (MHD)

Magnetohydrodynamic is the branch of science which deals with the study of physics background of conducting plasma.The electrical energy is obtained from high temperature conducting plasma, highly intense magnetic field.

MHD Generator

Suppose  charge particle "q" moves with a velocity of "v" right angle to the magnetic field, it means two plates p as shown, then magnetic force is given by,

If this charged particle q is replaced by a mass of ionized gas with same velocity v then positive ions accelerates toward upper plate and negative ions to the lower plate.

If this plates are connected externally through resistance  then current start flowing through resistance thus electrical power is generated by extracting the mechanical power of ionized gas.

This is the principle of Magnetohydrodynamic generation called direct form of generation  from heat without the necessity of any accessories as in Steam Power Plant.

Working principle of Magnetohydrodynamic Generation

There are two types of cycle in Magnetohydrodynamic generation:

1. Open cycle MHD generation
2. Closed cycle MHD generation.

1. Open Cycle MHD generation

Open Cycle MHD Generation

In above figure you can see that open cycle MHD generation consisting of a MHD generator resembles shape of a  rocket engine. Coal or natural gas is burned into combustor to produce hot gases. The hot gases is then seeded with alkaline metals ( cesium or potassium ) to increase electrical conductivity of of the gas. This gas then enters into a MHD generator which is rocket engine shaped in which gas expands and electrical power is generated by accelerating gas ions towards electrode and strong magnet. 

          Air preheater is used to preheat the air which is used as input hot air to the combustor. Later on seed material is recovered from the gas and next on Nitrogen and Sulphur is extracted from the gas to avoid air pollution and then flue gases are exhausted to the atmosphere with the help of stack. The output of MHD generator which is surrounded by the huge magnet is in the form of DC and then that DC is converted into AC with the help of inverter.

2. Closed Cycle MHD generation         

         

Closed Cycle MHD Generation

• HX1& HX2 - Heat exchanger 1 & 2
• S.T. - Steam Turbine
• CP - Compressor Product
• P - Removal of Nitrogen and Sulphur
• CS - Cessium injection

          Closed cycle MHD generation consist of three distinct part but interlocked with each other. In figure, at very left side heating loop in which air, coal and steam is used to be converted into gasifier form at a temperature of 520℃ and this heated gas is then fed to the combustor in which Argon gas is heated. The combustor product passes through the air preheater which preheats the air and then fed as input to the combustor. After air preheater removal of Nitrogen and Sulphur from the flue gases to decrease the air pollution and then this gas is exhausted to the atmosphere through stack.

         Heated Argon gas is fed to the MHD generator which resembles rocket engine shape surrounded by the huge magnet.

         During the expansion of the Argon gas into MHD generator, conversion of mechanical energy into electrical energy take place and then converted into 3Ø AC with the help of inverter. The speed of the gas is slowed down with the help of diffuser and then heat of the gas is utilized in heat exchanger 2 and water get get converted into steam. Steam is partially used to drive compressor and partially used to generate electrical power with the help of alternator. The Argon gas is recycled and fed back to heat exchanger 1 through the compressor and intercooler.

Thermal Power Station

In thermal power station the heat energy of coal is converted into mechanical energy and then this mechanical energy is converted into electrical energy.It is also known as Steam Power Station. Boiler is the heart of thermal power station. The main equipment of thermal power station is boiler and it has three main inputs namely: coal (fuel of thermal power station), air (for combustion of coal) and water for producing steam.
This topic will cover:-

Thermal Power Station

• Selection criteria of site for thermal power station
• Coal Handling Plant
• Working
• Condenser 
• Cooling Tower
• Ash Handling Plant

Selection criteria of site for thermal power station:- 

While installing the thermal  power station this point should be taken in consideration.

1. Availability of Coal :The power station should be installed near coal mines. Coal is the primary requirement of thermal power station for the generation of electricity. A thermal power station of 400 MW capacity requires 5000 to 6000 tons of coal per day. Nearer to coal mines reduces the transportation cost. 
2. Space requirement :Quite large space is required by the thermal power station up to 3 to 5 acres per MW for installing equipment, machinery, coal storage, ash disposal, staff colony etc. And the land available for power plant must be available at low cost also it should have sufficient bearing capacity for holding the heavy equipment's, to withstand the load of machinery.  
3. Availability of water :Water is the secondary requirement of thermal power station. In thermal power station water is required for many purpose. But the two main purposes are, firstly for conversion into steam for steam turbine and secondly for condenser. It is also required for drinking purpose for staff colony. Therefore the plant should be located near the resources of water such as rivers, ponds, lake, canal, etc.
4. Ash disposal facilities:20 to 40% of ash is produced of total weight of coal i.e. 1500 to 2000 tons per day. So it becomes a problem for handling ash. It becomes a more serious problem as it comes out in the hot condition and is highly corrosive. Therefore, large space is required for the disposal of large quantity of coal. Nowadays the ash from the power plants is used for many industrial process such as for making bricks, cement and more. Therefore disposal problem does not arise.
5. Transportation facilities:We can say this point is not very important and also important. Because every power plant is built near coal, water resources. Power plants should have the transportation facility such as road and rail for transportation of materials and machinery. ( But nowadays the materials and machinery are built on site.)  
6. Away from populated area:Due to burning of huge amount of coal thermal power plant produces smoke and fumes.This pollutes the environment. Hence plant should be located at considerable distance from populated area.
7. Near to load center:This is a common point for all the power station. Power station should be located near to load center to minimize the transmission cost of electrical energy. 

Coal Handling Plant: 

Coal Handling Plant

As huge amount of coal is required for the generation of electricity; it is required to store coal in storage plant. Storage of coal avoids the shortage in case of failure of failure of transportation and other abnormal conditions.

Working :

Working is same. Firstly, in the boiler the coal is burnt and heat is utilized to convert the water into steam. Flue gases after the combustion of coal are released to atmosphere through chimney. Flue gases are passed through the super heater, economizer and air preheater before releasing to atmosphere.

Working Thermal Power Plant

• Superheater: The steam produced in the boiler is impure. That means it contains some impurities in it such as moisture. Hence wet steam is passed through superheater to dry and superheat. Superheater also helps to increase the efficiency of the plant.     
• Economizer: The heat lost in the process is recovered in economizer to heat the feed water.
• Air preheater: In economizer the heat lost is not entirely recovered. Therefore air preheater is employed to recover some of heat in the flue gases. This helps to increase the steam capacity per square meter of the boiler.
• Steam Turbine: The superheated steam obtained from the superheater is fed to the low pressure steam turbine. The steam expands in the high pressure turbine. Therefore steam attains higher velocity. The potential energy of steam is converted into kinetic energy due to pressure and internal energy.
• Alternator: The mechanical/kinetic energy obtained from steam turbine is converted into electrical energy.

Condenser:

Condenser

The cooling water is generally passes through number of closed tubes and steam surrounds the tube called condenser. Non mixing type of condenser is generally used universally.

Cooling System:

Natural Draft Cooling Tower

1. Cooling Tower:- In cooling tower the amount of water which is large is divided in smaller quantities practically of the size of drops.These water droplets fall from a height of 8 to 10 meters to the bottom of cooling tower. The splitting of water helps to cool water quickly. The water from the base of cooling tower is pumped back to the condenser and same cycle is repeated.There are two types of cooling tower: a) Natural Draft Cooling b) Forced draft cooling
2. Spray Pond:- In this system water is circulated in closed loop and is used again and again. The water is cooled by both convection and evaporation.

Ash Handling Plant:

Ash Handling Plant

The ash storage plant is located 15 KM away from the power station. In ash handling plant the ash is removed from the coal and then delivered to the ash storage plant. Also ash is distributed to industries for various purposes such as for making bricks and cement.

In this way electricity is generated in Thermal Power Station.

 

Transmission

After the electrical power is been generated it is needed to transfer the electrical energy  for utilization. But the generated electrical energy can not be directly utilized at consumer level as the power generated is of very high magnitude around 15 kV or 17.5kV in general . So we employ, Transmission and Distribution system. In this post we will cover the basics of Transmission system.

Transmission System

Transmission line

The transmission system is simply defined as the transfer/transportation of electrical power generated in generating station to substation over a long distance. "Transmission System" is a broad term which directly refers to "Transmission Line." The basic remains same that electrical energy is transported from one place to another. Although "transmission line" is precisely defined as, " the transfer of electrical energy from generating station to substation in bulk." Generated electricity is in the form of 3Ø supply which is step up in power substation. Then it is stepped down in distribution substation to utilization level. 

Standard transmission voltages are:

400kV, 220kV, 132kV, 66kV, 33kV, 11kV.

Normal voltages of primary transmission are:

132kV, 220kV, 400kV.

Different transmission system:

1. Overhead transmission system
2. Underground cable system

Overhead transmission System:

Overhead Transmission line

We can easily view this system around us. This system is mostly used transmission system. Its consist of a bare conductor supported by the supporting structure and insulator. The high voltage conductors are not covered with any type of insulation. The supporting structure maintain clearance between ground and conductor and the insulator provide insulation between conductor and supporting structure. As the transmission voltage level increases, the height of supporting structure has to be increased to provide more clearance between ground and conductor.

Underground cable transmission system:

Underground Transmission line

Electrical power is also transmitted by underground cables but it is not widely used. In underground cable system one or two or more conductors are bunched together but are properly insulated from each other. Underground cables are provided with lead sheet and armouring, this helps to prevent the cable from moisture and mechanical damage. The thickness of insulation among the conductors and between conductors and earth is increased if the voltage of transmission system increases.

How to generate Electricity ?

There are different sources of energy so electricity can be generated by many different methods. In this modern world, the demand of electricity is increasing continuously if one want to keep up the pace with other people he/she has to find alternative methods of generating electricity which should be effective, cheap, pollution free, reliable.  As we have already learnt about constituents of Power System in previous post, today we will cover the Generation part of the Power System. Even the vegetables we eat regularly also generate Electricity like Lemon, Potatoes, etc.

Chandrapur Super Thermal Power Station, India
Asia's 2nd Largest Thermal Power Station

Anyone who as deep knowledge of sources of energy, working of components and a good will to do it can generate Electricity. If you have enough heat and money you can plant a Power Station. The objective is that there's no limitations and boundaries to generate electricity.

The main function of the generating station is to convert some form of energy into electrical energy. In this post we will deal with various method of generating electricity.

According to the energy available from other sources to rotate the turbine, power stations are classified as:
Classification of Power Stations :-

• Thermal Power Station (T.P.S.)
• Hydro Electric Power Station (H.P.S.)
• Nuclear Power Station (N.P.S.)
• Diesel Power Stations, etc (D.P.S.)

The natural resources of any country may be large but they can only be turned into wealth if they are
developed, used and exchanged for other goods. This cannot be achieved without energy.

Note:- Click on the links given above to learn generation of electricity by different methods. For example click on "Thermal Power Station" to learn about Steam/Thermal Power Station.

Electrical energy is emphasized because apart from prime mover , alternator combination a modern generating station employs several auxiliary equipment and instruments to ensure cheap, reliable and continuous service.

The electrical energy produced by the generating  station is transmitted  and distributed with the help of conductors to various consumers.

Types of Energy

Energy is the key input to drive and improve the life cycle. It's a gift of the nature to the mankind in various forms. The consumption of energy directly proportional to the progress and modernization of mankind. The continuous increase of population, improvement in standard for living, industrialization and the increase in demand of energy is expected to be more in near future. It is believed that at this rate of using fossil fuels, coal, natural gas, etc. there will be no energy at all.

There are two types of Energy:-

• Conventional Energy 

• Non Conventional Energy

Conventional Energy Sources

Conventional energy sources

• Oil - 40 %        

• Natural Gas - 22.5 %

• Coal - 23.3 %                 

• Hydroelectric - 7.0 %

• Nuclear - 6.5 %

• Biomass & others - 0.7 %

Non Conventional Energy Sources

Non Conventional Energy Sources

Fossil fuels supply most of the energy consumed today. They are relatively concentrated and pure energy sources, technically easy to exploit, and provide cheap energy. Presently

Conventional Energy from coal, natural gas and petroleum, hydel power are used abundantly at present. Except hydel power, the sources of thermal power i.e. other conventional energies are non renewable in nature. But the sources of non-conventional energy are flow-resources. There is no anxiety for their exhaustion. However the reserves of fossil fuels are limited.

To meet the future energy demands and to give quality and pollution free supply to growing and today's environment conscious population, the present world attention is to go in for natural, clean and renewable energy sources. These energy sources capture their energy from on going natural processes, such as geothermal, solar, wind, flowing water and biological process. 

Most form of energy, other than geothermal and tidal power ultimately come from the Sun. Some forms of energy such as rainfall and wind power are considered short term energy storage. Renewable energy is energy from a source that is replaced rapidly by a natural process and is not subjected to depletion in a human timescale.

Note:- The figures provided above about of Oil, Coal, etc may vary to date. As dependent on various websites, articles, books, the existence or capacity/storage of aforementioned sources of energy maybe different. 

Power System

Energy plays a vital role in day to day life of human being for overall development of the country and the world. We know different forms of energy such as wind, solar, thermal, etc. Our dependency on energy is such that without it our life become somewhat cumbersome. For instance, if electricity goes off for a minute we stigmatize the Power Supply Authority.

Electrical Power System 

• Generation 
• Transmission
• Distribution

Electrical Power System-Generation, Transmission and Distribution

We need to understand that there aren't so much storage of coal, natural gas, so we had to move on Non Conventional Energy Sources e.g. wind, tidal, solar. 

There are various uses of Electrical Energy in different fields such as for domestic purpose, where it is used for heating, cooking, refrigeration, light etc. Also it is used in industries, commercial complexes, irrigation purposes, etc.

To satisfy everyone's need, supply utilities provide electrical energy via a network which is known as Power System. 

As Law of Conservation states, energy can neither be created nor be destroyed, it can be converted from one form to another; power stations converts some of energy into electrical energy.
It mainly consist of two parts, one is turbine and other is alternator for example, turbine converts s\some form of energy into Mechanical form and then alternator converts it into Electrical form. The generated electricity is in the form of 3Ø which is step up in power station. Then it's transmitted to by transmission line over a long distance and then it's stepped down in distribution substation to utilization level. The step up and step down process is done by transformer. 
After that electrical energy is distributed to different consumers.

Meaning of few technical words:-

• Step Up:- Increasing the magnitude of voltage without change in frequency by transformer.

• Step Down:- Decreasing the magnitude of voltage without changing its frequency by transfromer