THE SLIDES EXPLAINS ABOUT THE DDCMIS(DITRIBUTED DIGITAL CONTROL SYSTEM AND MANAGMENT INFROMATION SYSTEM) SYSTEM USED IN POWER PLANT WITH THE PICTURE AND EXPLENATION.

1. By R.G.LOKKESH
(my sincere thanks to my father and his
colleagues for making this successful)

4. Firstly the pulverised coal(lignite) particles was sent to
the boiler from bunkers. the difference between coal
and the lignite is lignite contains more amount of
water and coal contains more amount of ash. In
thermal plants we are using lignite so to remove the
moisture content hot air is passed towards it(red line
in the dig) then as the water content is removed which
is the used to cluster the particles ,thus the particles
become again pulverised or break down to smaller
particles further. then it is again passed through mill
and then to the boiler furnace. The boiler oil is used
for lighting up furnace initially. There are 3 types of
oil used in power plants..

5. Volume of one unit mass of steam is thousand times that of
water. when water is converted to steam in a closed vessel the
pressure will increase. Boiler uses this principle.
1unit mass of steam=1000 m3 of water
The boiler is maintained in 1000deg.the blue colour line
indicate hot air from air preheater to supplied for burning the
coal and the red line indicates hot air for pulverising the coal
and removing moisture it will also take heat from the flue gas
but no aux equipments is needed as you can see the interaction
of two pipes in fig..a low pressure is maintained inside the
boiler so that the outer air will get sucked inside and hot air
from the boiler will not go outside.SH represents super heated
steam and RH represents reheated steam. then the steam is
collected in the drum and sent to the turbine(not shown)and
then the flue gas is sent through RAPH and then to electro
static precipitator to removes the fine particles like smoke and
dust and then through the chimney. This chimney will be made
of 220-320m height .As height increase the radius of unwanted
particles falling on to ground increases, so it is safe if we
increase the height. inside boilers water wall tubes were used
which will be like as shown in fig

6. RAPH is an rotating plate regenerative air preheater
which is used to collect heat from the flue gas and
then uses this heat to heat the atmospheric air and
sends it inside the boiler. This air preheater will be
round in shape and has a bisects in it in which at one
side of blade will absorb heat and as it was rotating
when it comes to other side the atmospheric air flows
over it and thus it absorbs heat(shown in fig).SCAPH
is steam coil air preheater used for same purpose.

8. Here FD(forced draft) fan is used to suck the air
inside and air filter is used. there are two types of fan
exist
1.forced draft fan
2.Induced draft fan
Forced draft fan is used to suck atmospheric air and
sent it to the furnace, so positive pressure is created.
But induced draft fan is used to pull out flue gas
from furnace to atmospheric air and thus it will
create negative pressure inside boiler.so when
compared to FD,ID will consume more power.

9. In the above fig you can see the inside view of boiler
air circuit. through filter then passes to dampers
(nothing but the valves for allowing the movement of
gas)[HLA 02]and then to SCAPH and then to air
preheater (RAPH).as it was earlier mentioned in
RAPH one side of rotating part will contain heat
absorbing material and absorbs heat from flue
gas(yellow line) since it is rotating and it moves to
other side and exchanges the heat with air(blue line)
and then to boiler.
in this fig two circuits have been shown and
the values are mentioned in it .

11.  This fig is nothing but the extension of the before
fig the flue gas circuit extension, which will
contain again an ID fan which sucks the flue gas
from the furnace and send it to chimney. again
you can see a yellow line going inside furnace
through RG fan which is flue gas is again sent for
reheating.

13. The super heated steam is first passed to the high
pressure turbine and then it is passed to reheater and
then only it is passed to intermediate and low pressure
turbine as they both are coupled each other, but the HP
is not coupled to IP and LP.the air from HP is passed to
reheater because the temperature will decrease below
350deg and pressure also decreases due to which the
steam may contain moisture so to remove the moisture
content the steam is again heated using reheater were
the steam is heated using flue gas. then after passing
through the turbines steam is condensed using cooling
tower .

14.  Remember the water coming out of condensor is
the demineralised water and it is passed through
the LP(low pressure) tank where the pressure of
the water is gradually increased by passing it
through 4 LP tank. Then from LP4 it passes to
Deaeration tank in which the oxygen and minerals
are removed.
Note: in the fig you can see that there is very slight
increase in temp .the temp at chimney is170deg and
temp at deaeration tank is 176deg ,so only the
pressure gets changed and then the stea, is passed to
HP tank where the pressure is further increased and
then sent to boiler.

16.  There wont be more explenation required for this
fig as you can able to understand. There will inlet
valves used and bypass inlet valves are used to
reduce the pressure acting. for example see if we
want to open the valve in the direction opposite to
the more pressure acting ,it is difficult but what if
we reduce the pressure so that there is only less
pressure difference exists. The same principle is
used here the bypass valves will be of smaller
radius so the water is allowed to pass through it
and the pressure gets decreased and once the
pressure difference gets small the inlet valve
having larger radius is opened.

18.  In this in right side corner ,you can see a turbine
connected to rotor part of generator. normally
the rotor will have 2 poles and which can able to
rotate at 3600 rpm for 2min and the speed of
rpm changes as per number of poles. here the
two poles are created by the electro magnets
which are excited by using dc so that poles wont
be changing.

21. an important thing to remember is there are totally
two types f water is used in the total circuit.
1.demineralised water – steam in boiler
2.Ordinary water – cooling purpose in cooling tower

23. Generator is ac motor. in this rotor will have
magnetic poles on it and stator will have conducting
conductors. Here armature will not be kept in rotor
because it is difficult to pass the current through
brushes in the rotor.
as you can see in this fig that stator part
is being under maintenance.. and you can see the
conducting conductors are laminated.

27. Inside a generator hydrogen gas was filled to reduce
the heat produced in the current carrying conductors.
Since hydrogen is explosive in air it is sealed inside
and protected by oil.

30. Here you can see three buses main bus-A,B and transfer bus.
you can see isolator (689-A,689B,689-C,689-D,breakers(652)
and earthers(689-E1,E2,E3) and GT-1 refers generator 1. There
are 1 isolators and 1 earthers for each bus and a breaker. Since
breaker is connected at main line single breaker is enough.
blue colour light lightning near the breaker indicates that
spring is charged as the breaker used was spring mechanism.
Isolator is one which also used to isolate the circuit but it can
be used only after the breaker is open,because breakers
doesnot have any protecting elements like oil and anyother
medium to cease the arc. Breakers are also used for the same
purpose but it will work only when it gets signal from relay
and it has oil as medium to quench arc. the continous spark is
called arc. Transfer bus can be used when one bus is at fault.
but if we use the transfer bus then the protecting circuits
used for faulted buses has to be changed to transfer bus. The
two switches(blackcolour) at the last are used for this purpose.
It has 3 modes normal,inter,protected. when it is connected in
inter it is connected to transfer bus.

34. Fault locator is an device used to find the point on the line
at which fault had occurred.
There are totally two methods are used to find it,
1.Impedance method
2.Travelling wave method

37.  OPEN CONDITION  CLOSED
CONDITION

38.  Isolator is one which also used to isolate the circuit
but it can be used only after the breaker is open,
because breakers doesnot have any protecting
elements like oil and anyother medium to cease the
arc.
Types of isolator:
 1) Double Break Isolator
2) Single Break Isolator
3) Pantograph type Isolator.

40.  When an fault occurs ,the circuit breakers are opened
but there will be some charge stored in the dielectric
medium(air)between the conductors and so when
anyone touches it the line ground fault occurs.so the
earthers are used and the charge will get disharged to
ground.so when circuit breakers are opened the
earthers are also opened.
as you can see a metallic bar at which one end is
connected to the transmission line and the other end is
connected to metallic structure, since the mettalic
structure will itself acts as ground, since it is directly
connected to ground.

42. Circuit Breaker: circuit breakers are used to isolate the faulty line when the relay
circuit senses the fault.
Types of circuit breaker:
 According to their arc quenching (rapid cooling) media the circuit breaker can
be divided as:
 1) Air circuit breaker
 2) Oil circuit breaker
 3) Vacuum circuit breaker
 4) SF6 circuit breaker
 According to their services the circuit breaker can be divided as:
 1) Outdoor circuit breaker
 2) Indoor circuit breaker
 According to the operating mechanism of circuit breaker they can be divided
as:
 1) Spring operated circuit breaker
 2) Pneumatic circuit breaker
 3) Hydraulic circuit breaker
 According to the voltage level of installation types of circuit breaker are
referred as:
 1) High voltage circuit breaker (> 72 kV)
 2) Medium voltage circuit breaker (1-72 kV)
 3) Low voltage circuit breaker (< 1 kV)

43. T shape breakers are shown in fig and they has an special
advantage, since they are in T shape, the distance
between the further most ends are more and the
potential difference is also divided so the formation of
arch gets reduced and SF6 is used in medium.
Here is the link: https://youtu.be/GSh0f94JwaA
Watch this, it is an animated working principle of
automated circuit breaker and no need of relays.in this
they uses bimetallic strip which expands and contracts
for opening and closing of circuit breaker.

44.  Cooling tower  Vertical pump

45.  Cooling towers are in the shape of hyperbolic because it
will cause natural air circulation. The middle part of the
the cooling tower will have low pressure and the bottom
and top most will have high pressure. remember these
pressure is created by atmospheric air (i.e) the atmospheric
air outside will be going inside the tower due to low
pressure region created in the middle due to which high
pressure region is created at bottom and top ends of the
cooling tower. since atmospheric air flows from down to
upside and the hot water is falling down from upside to
down side,thus the hot water and air is flowing in counter
direction so natural cooling takes place and these air will
absorb the heat and flow to the atmosphere again through
the top. Also it takes only very less amount of cement and
concrete is needed. a vertical pump is used in the cooling
tower raising up the water to that height.