Turbine

 

                             Turbine

    A Turbine is a rotary engine that converts the energy of a fluid or air into mechanical power, which can then be used to generate electricity .

                                      

         I.          Hot rolling procedure

       II.          Warm rolling procedure

     III.          Cold rolling procedre

MOT – Main oil tank

OVE –  Oil vapour  extraction fan

ACOP – Auxiliary oil pump

AOP – Auxiliary oil pump

Mechanical drive main oil pump

Electrical drive main oil pump

EOP – Emergency oil pump

Emergency oil pump driven by DC power source in case of failure of AC power for lubrication purpose only .

                                           Before Barring Run

1)      Run one oil pump [AOP or MOP]

2)     Ensure the flow of oil from overhead tank return through gauge glass .

3)     Start oil vapour extraction fan .

4)    Start jocking oil pump .

Hot well – Condenser

CEP – Condensate extraction pump

PRDS – Pressure reducing DE-superheater

PCV – Pressure control valve

PRDS – Parameter control valve

PRDS Parameters should be maintained

                                Pressure – 10 to 15 kg/cm²

                              Temperature – 300 to 350 ⁰C

 If the vacuum comes -0.2kg/cm² , charge gland steam to turbine by manually opening the gland steam control valve & put on auto made .

 Turbine rolling may be done

A.      Manually turbine rolling

B.     Semi – automatic turbine rolling

C.     Automatic turbine rolling

Hot rolling – When turbine casing temperature above 350 0C

Warm rolling – When turbine casing temperature between 150 ⁰C to 350 ⁰C 

Cold rolling – When turbine casing temperature below 150 ⁰C

O-A : - Control valve is opened slowly to rise the speed of turbine up to low idle speed of 1000 rpm  at a rate of 20 rpm/s .

A-B : - Hold time also called socking time of turbine . Turbine allowed to heat up for thermal expansion .

B-C :- After shocking time completed turbine is allowed to ramp up at a certain rate as advised by turbine manufactures .

C-D :- It is the critical speed zone of turbine . To avoid this zone , speed of the turbine is raised at faster rate [as shown 100 rpm/s]

D-R :- After passing critical zone , again turbine speed raised at a lower speed up to high idle speed . 

E-F :- This is called high idle speed , turbine is kept at constant speed for same time for socking .

F-G:- Turbine speed raised up to the rated speed at a certain rate [as 20 rpm/s].

JOP – Jacking oil pump

                   Turning gear Barring Gear

 It is the mechanism provided to rotate the turbine generator at a very low speed during starting or stopping .(i.e. turbine trip, shut down)

SSS clutch -rpm change  S – Synchro

                                           S – Self

                                          S – Shifting

   Hogging & Sagging is steam turbine

                      

       Sagging (-VE) * Bending of rotor shaft in down ward .

     Hogging (+VE)* Bending of rotor shaft is upward condition . 

Wheel chamber pressure

  Rapid opening and closing of the valve is known as chattering .

Simmering -  The valve is just about to open and has indefinite  contacts . An audible sound or visible escape of fluid between seat & disc at an inlet static pressure below the popping pressure and at no measurable capacity .

BOD – Biological oxygen Demand

   The dissolved oxygen consumed by microorganisms for breakdown organic matter so , oxygen level decreases & bacteria needs more oxygen to break down remaining organic matter.

   Oxygen needed by biological organism to break down organic material present in given water simple . When bacteria  break down all organic matter inside polluted water in the presence of oxygen already dissolved in water . 

    After consuming dissolve oxygen by bacteria , they needs more oxygen to break down remaining organic matter , for this microorganism demands for oxygen .

That’s why called BOD ?

 

BOD Level	Water Quality
1-2	Very good . There will not be much organic matter present in the water supply.
3-5	Fair . Moderately clean .
6-9	Poor . Some what polluted . Usually indicates that organics matter present and microorganisms are decomposing .
100 or more	Very poor . Very polluted . Contains organic matter .

 

 

 

Temperature [C]	Oxygen Solubility [mg/L]
0	14.6
5	12.8
10	11.3
15	10.2
20	9.2
25	8.6
100	0

 

 In a fixed volume of polluted water (1 liter) microorganisms consumed oxygen in a 5 days at  20 ⁰C  is called Biological oxygen Demand (BOD) .

COD – Chemical oxygen Demand

Water type	Expected COD
River	5-50 MG/LTR
Treated effluent & polluted river	25-250 MG/LTR
Primary / secondary effluent	250-750 MG/LTR
raw municipal sewage	500-1200 MG/LTR

    Sample preparation + Digestion of samples = sample for cod analysis

Chemical oxygen demand – COD

 Organic & bio waste contains : -

     Carboxylic acids , Aldehydes , Ketones , Alcohols , Carbohydrates , Biomolecules , Proteins , Amino acid , Soaps , Detergents , Oils , Fats , Cellulose , Polymers , Fibers , Plastics ETC .

Inorganic waste such as : -

 Alkali , Metals , Metal salts , Sulfates , Nitrites , Ammonia , Acidic Compounds ETC .

Chemical oxygen demand – COD . It is measure of capacity of waste water to consume oxygen during the oxidation of organic , inorganic & bio waste by using strong oxidizing agent .

 Like : - Acidified potassium chromate .

1.      Black Titration

2.     Sample Titration

Blank Titration –

    25 ml of distilled water containing no oxidizable waste in conical tank  +  25 ml k₂cr₂o₂ in acid medium = [ 0 ]

        =  Full 25 ml of k₂cr₂o₇ remained in conical flask .

Role of H₂SO₄ :-       

        K₂CR₂O₇ + 4H₂SO₄ – K₂SO₄ + CR₂(SO₄)₃ + 4H₂O + 3[O]

    Sulfuric acid make K₂CR₂O₇  to behave as an oxidizing agent , release nascent oxygen , which further oxidizes the waste in sewage water .

  Role of AG₂SO₄ :-

      AG₂SO₄ acts as a  catalyst , helps in oxidizing both organic / bio (carboxylic acids , aldehydes , ketones , alcohols , carbohydrates , biomolecules , proteins , amino acids , soaps , detergents , oil , fats , cellulose , polymers , fibers , plastic ) + Inorganic (alkali , metals , salts , sulfates , nitrates , ammonia , acids compounds , ETC ) waste .

Role of HgSO₄ : -

   H₂SO₄  Mercuric sulfate prevents the interference or precipitation of the catalyst AgSO₄ as AGCL , since  waste water will contain chloride ion .

HGSO₄ + 4CL – [Hgcl₄]^2-  an water insoluble complex . so free Cl ^– is not available for precipitation of the catalyst is safe .

V₁ – Volume of FAS (Ferrous ammonium sulfate)  used in Blank Titration 

V₂  - Volume of FAS (Ferrous ammonium sulfate) used in sample Titration

COD as mg O2 √L = (A-B)* M* 800 / ml sample

Where A = ML FAS used for blank   

            B = ML FAS used for sample

           M = Molarity of FAS , and

          8000 = n , equivalent weight of oxygen * 1000 m/l

     Steam turbine is a mechanical device that extract kinetic energy from pressurized steam & convert it in to useful work . i.e. rotary motion .

Throttle valve

Stage of turbine = Moving blade + Fixed blade

Turbine consists of several set of blades  (1) Fixed blade on casing

                                                                         (2) Moving blade on rotor

 Turbine  (1) Impulse Turbine

                 (2) Reaction Turbine

 Nozzle :- Pressure – Decreases

                  Velocity – Increases

  Impulse turbine works on Newton 2^nd  law . The resulting motive force is due to change in movement gives rotation to the turbine shaft .

                   F = M * A

Reaction turbine work on Newton’s 3^rd  law for every action , there is an equal and opposite reaction .

                                             Compounding

      To reduce the rotational speed of turbine , multi staging is done multiple set of nozzles and moving blades are fixed in series called compounding .

1.      Pressure compounding

2.     Velocity compounding

3.     Pressure – velocity compounding

Compounding of Impulse turbine &  Compounding of reaction turbine 15 stage of turbine .

Steam from boiler enters to turbine . If the expansion of steam and entire pressure drop of steam from boiler pressure to condenser pressure takes place in single stage only . Then steam velocity entering in to turbine could be very high will make the turbine rotor to run at very high speed (up to 30,000 rpm) loss of kinetic energy in single stage turbine is 10 %  to 12 % .

                  Pressure Compounding

       The total pressure drop of the steam does not takes place in a single stage nozzle , But is equal divided in all row of fixed blade which works as nozzle .

                               

                                   Velocity compounding

   Pressure drops in only one set on nozzle , but the velocity drop takes place in different stages of the moving blades .

                                              

                Pressure – velocity compounding

     Pressure drop takes place at different nozzle sets and velocity drop takes place at different moving blade sets .

                                       HOGGER  or Ejector

                           

     PRDS – Pressure reduce DE super heater

      A Turbine PRDS is a device that reduces the pressure and temperature of steam in a turbine bypass line . A PRDS ensures optimal conditions for turbine operation by removing excess pressure and heat . It also protects downstream equipment like the superheater, reheater , and  turbine .

 Pressure – 11 kg / cm ²

 Temperature – 220 ⁰ C to 250 ⁰ C

Nozzle – Pressure reduce

               Velocity increases

Air + steam released to atmosphere by HOGGER

 HOGGER is an open cycle .

Ejector is a closed loop cycle .

During HOGGER taken in line  (A) Steam valve open

                                                      (B) Air valve open

For line out HOGGER  (A) Air valve close

                                       (B) Steam valve close

    HOGGER used for quick evacuation of non condensable  gas while  Ejector used for maintaining the vacuum .

                          

                              

     Thank you

                                 

                             

Suvendu Singha & Mamata  &  Nishan