Power Plant Guruji

  Steam Turbine Wet Washing Washing Procedure : Turbine blades wet washing is carried out at condensate temperature around 100 deg C.  After shut down of Turbine, Turbine is allowed to cool to 100 deg C or if it is under shutdown then Turbine is heated up to 100 deg C.  Then Turbine is filled with 100 deg C condensate water through any of the Turbine casing drains or bleed lines. Later, the rotor is rotated slowly with barring gear for 3 to 5 hours & then the water will be drained.  This procedure is repeated for 3 to 4 times till you get clear water from drain. Wet steam is generally generated by injecting cold water in super heated steam.  This wet steam is allowed to enter into Turbine & keep the turbine speed around 500 to 1000 rpm depending on the Turbine speed or may be maintained around 10-20% speed.  Care should be taken for 100% removal of condensate water from wet steam.   Also there should not be variation in quality & tempe...

 1. What is the function of baffle plate in parallel flow type low level jet condenser? a) It keeps cooling water and exhaust steam from mixing b) It ensures proper mixing of cooling water and exhaust steam c) It collects condensate over it for extraction d) It helps condenser wall withstand the inside pressure Ans. b 2. Where is condensate extraction pump provided in case of low level parallel flow type jet condenser? a) At the bottom of the condenser b) At the top of the condenser c) Near the baffle plate d) Near the steam entry point Ans. a 3. Which of the following statements regarding low level counter flow type jet condensers is FALSE? a) Cooling water is broken into jets by perforated trays b) Condensate is collected at the bottom c) Steam is discharged near the bottom and moves upwards d) The air suction pump is placed near the bottom of the condenser Ans. d 4. Which of the following condensers is also called barometric condenser? a) Low level parallel flow type jet condens...

 1.Junction valve is used to ? a) Regulate flow of steam b) Regulate water supply c) Put off fire in the furnace d) Indicate water level in the boiler Ans. a 2. If the value of poisson's ratio is zero, then it means that ? a) The material is rigid b) The material is perfectly plastic c) There is no longitudinal strain in the material d) None of these Ans. a 3. Maximum heat is lost in the boiler due to ? a) Unburnt carbon  b) Flue gases c) Incomplete combustion d) Moisture in fuel Ans. b 4. Latent heat of vaporization at critical point is ? a) Less than zero b) Greater than zero c) Equal to zero d) None of the above Ans. c 5. The specific volume of water when heated at 0 deg. C is ? a) First increase and then decrease b) First decrease and then increase c) Increase steadily d) Decrease steadily Ans. d 6. The draught produced by steel chimney as compared to that produced by brick chimney for the same height ? a) Less b) More c) Same d) Can't determine Ans. b 7. For maximum disch...

 1. Main objective of boiler trial is ? a) To determine the generating capacity of the boiler b) To determine the thermal efficiency of the boiler, when working at a definite pressure c) To prepare heat balance sheet for the boiler d) All of the above Ans. d 2. Device used to put off fire in the furnace of the boiler, when the level of water in the boiler falls to an unsafe limit, is ? a) Safety valve b) Fusible plug c) Blow off cock d) Stop valve Ans. b 3. The shell of the cochran boiler is made hemispherical ? a) To provide maximum strength and space b) To withstand high pressure inside c) Both ( a ) and ( b ) d) None of these Ans. c 4. The dryness fraction of steam within a turbine is not allowed to fall below ? a) 0.5 b) 0.9 c) 0.95 d) 0.99 Ans. b 5. With increase in pressure ? a) Enthalpy of dry saturated steam increase b)  Enthalpy of dry saturated steam remains same c)  Enthalpy of dry saturated steam decreases d)  Enthalpy of dry saturated steam first increas...

 1. Which of the following statements is FALSE about double-pass condensers? a) The water flows in one direction through some tubes and returns through the remainder b) Exhaust steam flows through the tubes, while cooling water passes over the outer surface of the tubes c) It is a type of surface condenser d) Cooling water doesn’t come in contact with the exhaust steam Ans. b 2. Which of the following statements is False about steam condensers? a) Jet condensers are cheaper than surface condensers b) Cooling water comes direct contact with the exhaust steam in jet condensers c) Cooling water does not come in direct contact with exhaust steam in surface condensers d) Jet condensers are further classified into single-pass and double-pass condensers Ans. d 3. Which of the following statements is TRUE about single-pass condenser? a) It is a type of jet Condenser b) The flow of water is in one direction only c) The water flows in one direction through some tubes and returns through the ...

 Q 1. What are the difference between c onvective superheaters and r adiant superheaters? Ans.  Convective superheaters receive heat from flue gases. Radiant superheaters are placed in the furnace. The wall tubes of radiant superheater receive heat from the burning fuel through radiant process. Radiant superheaters are usually used where the steam is to be raised to a high superheat temperature. Q 2. What is the function of  a steam separator? Ans.  The function of a steam separator is to reduce the wetness of the steam by removing the water particles from the steam before it enters the steam turbine or engine. It is installed on the main pipe delivering the steam as close as possible to the engine. Q 3. T ypes of steam separator? Ans.  On the basis of principle of operation steam separators are classified into baffle or impact type, reverse current type and centrifugal type. There is a loss of heat in the steam pipe after the steam leaves the boiler which produ...

 1 . What is the maximum working pressure of a Lancashire boiler? a) 10 bar b) 12 bar c) 14 bar d) 16 bar Ans. d 2. In Lancashire boiler, an arrangement is made so that burning coal and ashes do not enter the furnace tubes. What is that arrangement called? a) Low brickwork fire bridge b) Ash-filter c) Filtering mesh d) Furnace separator Ans. a 3. How many fire tubes (Furnace tubes) does a Lancashire boiler has? a) One b) Two c) Three d) Four Ans. b 4. What is the function of dampers in Lancashire boiler? a) They control the flow of hot gases to the chimney b) They regulate the fire in the furnace c) They control the flow water to the boiler d) They control the steam going out of the boiler Ans. a 5. Which of the following is the correct range of the diameter of shell for a Lancashire boiler? a) 1 to 2 m b) 2 to 3 m c) 3 to 4 m d) 4 to 5 m Ans. b 6. Which of the following statements is TRUE about Lancashire boiler? a) The length of its shell is about 10 m b) It has a steam capacity ...

 Q 1, What is  Boiler Accessories? Ans.  Boiler accessories are auxiliary plants that help in proper operation of the boiler and also increase its efficiency. Feed pumps, injector, superheater, air preheater, economizer, superheater are some commonly used boiler accessories. Q 2. Purpose of boiler feed pump used in boiler? Ans.  Feed pump is used to deliver feed water to the boiler. Reciprocating pump and rotary pump are the commonly used feed pumps. Reciprocating pump is classified into single acting and double acting pump. Q 3. In single and  double acting reciprocating pump,  water is displaced by? Ans.  In a double acting reciprocating pump, water is displaced by both side of the piston. This is the reason why water is discharged in each stroke. In case of single acting pump water is displaced be only one side of the piston and hence water is discharged in alternate strokes. Q 4. Injector is used in which type of boiler? Ans. Injector is used to fe...

 1 . Which of the following is NOT a feature of a good boiler? a) Light in weight b) Steam production rate should be as per requirement c) Capable of quick starting d) Water and gas circuits should be such as to allow maximum fluid velocity Ans. d 2. What is lagging? a) The formation of steam bubbles on the surface of water b) Blocks of asbestos or magnesia insulation wrapped on the outside of a boiler shell c) The deposit of medium to extreme hardness occurring on water heating surfaces d) Heat insulation material Ans. b 3. According to boiler terminology, the removal of the mud and other impurities of water from the lowest part of the boiler is termed as _____ a) lagging b) blowing off c) waste removal d) foaming Ans. b 4. Which of the following according to boiler terminology, is the term used for the deposition of medium to extreme hardness occurring on water heating surfaces because of undesirable condition in the boiler water? a) Refractory b) Foaming c) Scale d) Lagging Ans....