Know Your Thermal Powerplant.Part 2

The first part (Know Your Thermal Powerplant) received quite a good feedback and I got a few suggestions and queries from my readers for the second part.
        One of them was by Sumedha who suggested the idea of combining all the pics that I used into a single picture so that it can be shared more.So here it is.

           And from another of my friends Mohi I received a few queries which he requested me to answer here so that it benefits others too.All the questions asked by him are here followed by my answers

Q.At what time in a year the plant would be running at full capacity?
A.The plant always strives to be run at full capacity irrespective of the time of the year.The points on which the load of a plant depends is
1.Internal wellness of the plant like availability of all the equipment
2.Availability of coal.For example in the recent times when some companies lost their mines to the government and their plants had to be shutdown.
3.The schedule assigned to it by a load dispatch center.Looking at the conditions of the Grid a certain load is assigned to every power plant.It has to follow it.

Q.Normally how many units are operated simultaneously?
A.If a plant has 4 units all the 4 units are run simultaneously except when there are problems like the above mentioned points.

Q.What are the number of Breakdowns in a month on an average?
A.It depends on how well made(erected and commissioned) the unit is.Also it depends on the operation of the unit.For example a unit  may have had 3 outages in 12 months(0.25/month) and another may have had 15 outages in 12 months(1.25/month)

Q.What is the source of water?
A.Rivers or if a plant is located near a sea shore its sea.

I thank sumedha for her suggestion and Mohi for the questions.

Know Your Thermal Powerplant.

70% of India's Power is generated by Coal based Thermal Power Plants and yet majority of the general public knows very little about them.

One of the comments that I got related to my previous post about Powerplant(Power Engineers) was how it helped a person know what goes on inside a powerplant. That got me thinking.I know of many people who have no idea of what a thermal powerplant does and how it does what it does.So here I am dedicating an entire post about a thermal powerplant.This is essentially for people who have zero idea about a thermal powerplant.

Q-What does a Thermal Powerplant do?
A-Generate electricity

Q-What is the fuel used?
A-Coal or Gas (This post is about a Coal based Thermal Power Plant)

Let me start with a few pictures.The plant that I will be talking about is a 250MW Unit.

This is a typical Thermal Power Station.What do you see? People who have no idea are, maybe wondering what those buildings house.Let us see, in different pictures some of the  parts.

That building houses the Boiler. A few questions now.

Q.What purpose does a boiler serve?
A.A boiler is where steam is generated.

Q.Why is steam required in a Thermal Power Limited?
A.Because steam is the main driving medium.It is the medium which drives a turbine.

Q.Why does a turbine needs to be driven?
A.Because turbine shaft drives or rotates a shaft inside the generator

Q.Why does a shaft needs to be driven inside a generator?
A.This has a long and a bit complicated answer but lets just get a basic idea.Just know that if you rotate a conductor inside a magnetic field,current begins to flow inside the conductor.So we have a magnetic field already created in a generator.Only thing we have to do is to rotate a conductor in that magnetic field.This is achieved by the generator shaft.This is how current is generated.(The turbine shaft and generator shaft are coupled.When turbine shaft rotates the generator shaft rotates.The turbine shaft is rotated by steam.Steam is produced by a boiler)

Q.How is water heated in boiler to produce steam?
A.By burning coal.

This is the turbine building.It houses the steam turbines and other equipment like pumps etc

These are the chimneys.Now a simple thing needs to be explained.When coal is burned in a boiler furnace,products of combustion are produced.These transfer the heat to water and then they have to be removed.These are sucked out by a set of fans known as Induced draft fans.They suck the gas and eject it out through the Chimneys.

There are other fans like forced draft fans which provide the air needed for combustion in furnace.

Now let me make this clear, coal is not burned as it is.It first crushed into a fine powder, as fine as the talcum powder used in our homes.And Primary Air fans are the fans which lift the coal powder and throw it in the furnace.

This is how coal is transferred to the boiler.From these conveyors coal(size is normal here) falls into the mills( also called crushers or pulverizers) where it is finely crushed.From here,as I mentioned before,Coal powder is lifted by primary air fans and then taken to the furnace where it burns.

Many people draw blank faces when this description comes up.This is nothing but the capacity of a plant.This 1000MW is actually the sum of 4 units of 250MW each. It is generally written as 4x250 MW Power Station. Let me explain what it really means.At any given point of time of the plant's running it produces 250MW of power.So it is not 250MW per hour or per month.
(MW is Mega Watt)

And these are Cooling Towers not chimneys. These are used to cool water.

I hope I have made at least a few things clear for the people who had no idea about a powerplant.If there are any questions I would love to answer them.

Power Engineers.The Unsung Heroes.

Its 2 am in the night. A group of engineers are looking intently on the monitors in front of them. Their faces, tense. Everything must go according to the procedure. No deviations. No mistakes allowed. The plant is being started, technically called a light up and should be done according to the schedule. The shift in charge is yelling instructions. There is constant ringing of the desk phones. To an outsider it is utter chaos.

               Power engineers are one of the most underappreciated engineers. Barely anyone outside the industry ever hears of them. The dedication and work they do goes unnoticed.

               In a power plant there are various departments like operation, Control and Instrumentation, Maintenance, Chemistry etc. A plant runs with the cooperation of all the departments. But it is the operation Department which oversees the day to day running of the plant. Operation engineers work in shifts. There are three shifts including night shifts. That in itself is quite difficult for the human body to adapt. Then there is the matter of responsibility of running huge machines like turbines, pumps and compressors. The biggest pump, for example, in a 600MW unit is a Boiler Feed Pump which is a 12MW machine. That means, it is of the same power as of 150 hatchback cars of 100Horsepower.Also it is equal to the power capacity of 6 locomotive engines. One can imagine the might of this machine and the responsibility attached to running it.

    With huge machines come maintenance problems. Giving permission, technically called a permit, to other Departments for resolving issues is a very critical task. The permit giver who is an Operation engineer must ensure that the concerned machine is isolated and won’t affect other machines, processes and most importantly the personnel involved in the maintenance. Apart from all these there are hundreds of parameters to keep an eye on. The operation engineer should know the range of these parameters, he/she should know what is an abnormal value, at what value the machine stops (technically called a trip) and at what value it is harmful for the machine.

    Running a plant of 600MW is no small task. If the plant trips then 600MW is being suddenly removed from the grid. A grid is nothing but a network of power generators and consumers of electricity. So when 600MW is suddenly removed the whole grid is shaken up. So utmost care has to be taken to avoid tripping of a running plant.

  As can be seen from the above examples Operation Engineers have a very responsible job and it involves split second decision making. They deserve much more recognition than what the society gives them.