Components of Thermal Power Plant (part 1):

Process description:  In  a tried and true thermal force station, a fuel is utilized to heat water, which gives off steam at high force. This in turn drives turbines to make power.  The force vigor of the steam produced is changed over into mechanical thrust with the assistance of turbine. The mechanical power is nourished to the alternator where the magnet is pivoted inside a set of stator winding & consequently power is prepared. The alternator used in thermal power plant is known as Turbo Generator in India about 70% of sum of  power is created by thermal power stations.

Thermal power plants are arranged by the sort of fuels utilized.

 

•  Solar thermal electric plants utilize daylight to heat  water, which is then used as thrust for turbine.

•   Fossil fuelled force plants might additionally utilize a steam turbine generator.

•   In incorporated steel factories, impact heater fumes gas is an easy souce to drive turbine.

•   Renewable energy plants may be fuelled by waste from sugar mills which basically used sugar cane, sewage solid waste, landfill methane etc.

•    Geothermal force plants use steam removed from blazing under the surface of earth.

•    Nuclear power plants utilize an atomic reactor's high temperature.

Layout of  the scheme is shown below.

 

How does Power is Generated In Thermal Power Plant:

To grasp the working of the Thermal Power Station plant, we can isolate the entire process into accompanying parts.


 

Boiler : . Boiler is an encased vessel in which water is warmed and coursed until the water is transformed into steam at the needed force. It is a relatively huge structure. The Boiler wall material  for the most part made of solid metal to with stand high temperature and force. The development of kettle shifts relying on the hotness exchange technique utilized. In an universal kettle, the heater has openings on the more level base for the curl powder to enter. Coal is blazed inside the burning council of boiler.the results of burning are just gases.these gases which are at high temperature vaporize the water inside the kettle to steam.some times this steam is further warmed in a superheateras . higher the steam force and temperature the more stupendous proficiency the motor will have in changing over the hotness in steam into mechanical function.  This is to guarantee that coal invests most extreme time before settling down and gets blazed totally. The external surface of the heater has many channels in which water goes through. This is the procedure in which high temperature is traded.

Classification of Boilers

 

Bolilers are classified as

Fire tube boilers : In fire tube boilers hot gases are passed through the tubes and water surrounds these tubes. Steam rate production is very less. In this since the water volume is more circulation is very poor.So they can't meet quickly the changes in steam demand. High pressures of steam are not

possible,maximum pressure is limited to 16.5kg/sq cm.The steam generated is contained with small amout of moisture.This type of boilers are not suited for big power plants. This type of boilers are safer as compared to water tube boiler because these involves lessr risk of explosion.

                                                              

Water tube boilers : In these boilers water is inside the tubes and hot gases are outside the

tubes.They consists of drums and tubes.They may contain any number of drums.Feed water enters the heater to one drum this water circles through the tubes joined outside to drums.hot gases which encompasses these tubes wil change over the water in tubes into

 steam.this steam is passed through tubes and gathered at the highest point of the drum. This type of boiler are very efficient and can work under very high pressure of 100kg/cm squre or more. since it is of light weight. so the drums store steam and water (upper drum).the whole steam is gathered. This type of boilers are suitable for big power plants.

 

 

                                                 Basic Boiler Schematic

 

Turbine : 

Steam turbines convert the energy acquired by the steam in to the mechanical energy. These turbines are couple with the alternators which produce the electrical energy from the mechanical energy. Two types of turbines are widely prevalent : impulse turbines and reaction turbines.

In the impulse turbines, steam expands at the nozzles and achieved kinetic energy is used to rotate the blades of the turbine. The blades change the direction of steam but not the pressure. Thus change in momentum can be accounted for rotation of the rotor. In the reaction turbines, steam is partially expanded on the nozzles and remaining expansion takes place during the flow over moving blades.

   Generally there are two or three sets of turbines at one go. All the enrgy stored in the steam cannot be obtained at one go from a single turbine. So, there are two or three sets of turbines located which are connected by a shaft. Now the high pressure steam enters into the first turbine, lets call it HP turbine. Once the expansion takes place, the pressure falls. Hence we need to use a turbine designed for lower pressure appropriate to the out coming steam. So the second turbine will be a medium pressure turbine (MP turbine).  

Further , in some cases a third turbine is also added to make more energy out of steam and this is called a low pressure turbine. The specifications of turbines are calclcuated during the plant design and later during operations, same ratings of steam pressure and temperature need to be maintained for optimum operation. 

 

 

Pulverizer : 

To generate the massive amount of heat which is required instantaneously , a lot of coal is to be burnt. If chunks of coal is used, very less surface area of coal is exposed and it takes a lot of space to burn enough coal chunks for required power. As a result, to overcome this problem, coal is pulverized into powder which is as smooth as talc. Now this powder is blown into the boiler. Thus, as  powder has a very higher surface area compared to chunks of coal, very large amount of coal can be burnt instantaneously in less volume efficiently. This is the underlying interesting fact for using of a pulveriser.

Super heater:

The greater part of the advanced boliers are having superheater and reheater arrangement. steam is super heated in order to make it hold more energy and transfer it to the turbine superheater is a segment of a steam-producing unit in which steam, after it has left the boiler drum, is warmed above its immersion temperature.  The flue gases vacating the heater are utilized to superheat the steam.  The superheater may comprise of one or more stages of tube banks organized to successfully exchange hotness from the items of combustion. The.

Economizer: The water entering into the heater must have somewhat temperature  in order to save heat & fuel. In this way, the high temperature flue gasses after leaving the super heater is utilized to heat the water in the economizer. Economizer is located between the passageways from the boiler to the chimney .the utilization of economiser results in sparing in coal utilization. However it needs extra space on floor region.

Air pre heater : 

The air utilized for burning of the coal is preheated by the flue gases in order to take greatest high temperature from the gases before they diffuse into the environment. It is additionally to guarantee that the unwarmed air ought not meddle with legitimate burning inside the boiler. It is intended to high temperature air preceding a different process for instance, burning in an evaporator) with the essential target of expanding the thermal productivity of the procedure. As a result, the vent gases are additionally passed on to the vent gas stack (or fireplace) at a more level temperature, permitting streamlined outline of the movement framework and the pipe gas stack. It additionally permits control over the temperature of gases leaving the stack.

Condenser :

 As discussed earlier, the job of condenser is to turn the steam from the turbine into water and thereby reducing the amount of water required for each cycle. There are many types of condensers. The familiar ones are Jet type and Surface type. In the jet type , the cooling water and the steam are mixed and the resultant steam water mixture is drawn outside. Surface type uses a different circuit for both and the steam is converted into water and cooling water turns hot. The surface type are the widely prevalent ones.

DEAREATER: It is utilized to uproot air from water which is ensnared in the water particles. It is extremely paramount part on the grounds that the captured air impact air drum severely.

         

BOILER FEED PUM (B.F.P.): It is the

heaviest drive in the plant & supply water to kettle drum from dearator.

ECONOMISER:

In this pipe gases trade high temperature to the water to build framework effectiveness, causes safeguarding in fuel utilization (5 to 10%). Economizer tubes are made up of steel either smooth or secured with blades to expand the high temperature exchange surface territory.

 CEP:

Cep is pump used to flow condensate water in the food cycle way up to deaerator with force of 20 kg/cm^2. It is a multi-stage (8-stage) pump. ( Answered by Daneshwar Prasad Verma ) c.e.p. pump is utilized to concentrate the consolidated water from the sizzling great and supply to the deareater in the wake of passing through l.p. heater& economizer,so that high force steam in the chamber could be created.(answered by Eesha)c.e.p. pump is utilized to concentrate the dense water from the blazing great and supply to the deareater in the wake of passing through l.p. heater& economizer,so that high force steam in the chamber might be made.

Provided that Cep outings,

1)water in hotwell of surface condenser will gather, therefore decreasing vacuum in surface condenser.

2)vacuum continues decreasing as water continues amassing (get closer to barometrical force)

3)turbine will excursion because of high fumes force

4)plant close down.

As we can see from above, when Cep excursions, plant could close down. That is the reason as a rule there will be more than 1 Cep in a force plant for extra reason if the 1st one quit meeting expectations

Boiler feed pump:

Boiler feed pump is used to feed water to steam generator boiler drum at desired pressure and temperature. Generally 2 Turbine driven boiler feed pumps (1 Working & 1 Standby) & 1 Motor driven boiler feed pump is used for 1 unit. Function of feed extraction pump in a feed system for boiler and steam turbine




How an auxiliary feed system works ?

The extraction pump is used to draw water from a condenser which is under vacuum. The pump also provides the pressure to deliver the feed water to the de-aerator or feed pump inlet. Extraction pumps are usually of the vertical shaft, two stage, centrifugal type.

These pumps require a specified minimum suction head to operate and, usually, some condensate level control system in the condenser. The first-stage impeller receives water which is almost boiling at the high vacuum conditions present in the suction pipe. The water is then discharged at a slight positive pressure to the second-stage impeller which provides the necessary system pressure at outlet.