#top condensing economiser

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Facts Related To The Top-notch Condensing Economizer

Condensing economizer-equipped boilers may achieve an overall efficiency of more than 90%. By lowering the temperature of the flue gas below its dew point, a condensing economizer can improve the efficiency of waste heat recovery and overall heat recovery by up to 10%.

Condensing Economizer offered by O'Brien Boiler Services Pty. Ltd. gets used for different purposes. 

direct and indirect contact. An indirect contact condensing economizer removes heat from the gasses by bypassing the hot flue gasses through one or more tubular heat exchangers or shell-and-tube heat exchangers. While achieving exit gas temperatures as low as 75°F, this economizer can heat fluids to a temperature of 200°F. The indirect contact economizer can heat water to a higher outlet or process supply temperature than the direct contact economizer. Condensed water vapour from the combustion of hydrocarbon fuels like natural gas or light oils must not caus e corrosion to the condensing Economizer. If the condensed water vapour is to be used as process water or discharged into the sewer system, it needs to be neutralized because it is acidic.

Utilizing a direct contact condensing Economizer, which consists of a vapour-conditioning chamber followed by a countercurrent spray chamber, is yet another method of recovering heat. A non-fouling heat transfer surface is provided by the cool liquid droplets that come into direct contact with the hot flue gas in the spray chamber. The liquid droplets condense, disentangle, and cool the stack gas.

With the best energy efficient boiler, changes in the system's operating parameters should be evaluated when deciding whether or not to install a condensing economizer. O'Brien is the best choice for such boilers. By preheating the boiler makeup water and lowering the amount of steam required by the deaerator, these economizers provide more steam for plant processes. If blowdown heat recovery provides the majority of the deaerator steam, the potential for energy savings decreases. If the turbine discharge is used to balance a low-pressure header, the condensing Economizer could also limit or decrease the energy produced by the backpressure steam turbine. 

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300+ TOP THERMAL POWER PLANT Objective Questions and Answers

THERMAL POWER PLANT Multiple Choice Questions :-

1. in steam power plant which of the following component needs more maintenance: a) Condenser b) Boiler c) Turbine d) Coal carrying system Ans: b 2. The pH value of the water used in boiler is: a) Unity b) 7 c) Slightly less than seven d) Slightly more than seven Ans: d 3. For the flue gas flow, tick the correct sequence: a) Boiler-Air preheater- economizer- ID fan- Chimney b) Boiler- ID fan -Air preheater- Economizer- Chimney c) Boiler- Economizer- Air preheater- ID fan- Chimney d) None of the above Ans: c 4. Hydrogen cooling employed in large thermal power plant alternator: a) Increases the insulation life b) Decreases the insulation life c) Does not affect the insulation life d) None of the above Ans: a 5. Hydrogen cooling is employed in: a) Turbo Generators only b) Water wheel Generators only c) Can b used in both turbo generators and water wheel generators d) None of the above Ans: a 6. The efficiency of the electro static precipitators will be of the order: a) 99.6% b) 90% c) 85% d) 80% Ans: a 7. Economizer is normally employed when boiler pressure exceeds: a) 70 kg/cm2 b) 50 kg/cm2 c) 30 kg/cm2 d) Can be used for all pressures Ans: a 8. The sizing of the generator in power plant is based on: a) Current carrying capacity ratings only b Insulation strength ratings only c) Both (a) and (b) d) None of the above Ans: c 9. Without Electro static precipitators: a) ID fan rating should be increased b) Economizer rating should be increased c) Chimney height should be reduced d) None of the above Ans: a 10. In thermal power plants the condenser used is of: a) Surface type b) Jet type c) Can be both surface type and jet type d) None of the above Ans: a

THERMAL POWER PLANT MCQs 11. Coal rank classifies coal as per its: a) Specific gravity b) Degree of metamorphism c) Carbon percentage d) Ash content Ans: d 12. Induced draft fans are used to: a) Cool the steam let out by the turbine in the thermal power station b) Cool the hot gases coming out of boiler c) Forces the air inside the coal furnace d) Pull the gases out of furnace Ans: d 13. Generally the speed of turbine generators employed in thermal power plants will be in the range of: a) 750 rpm b) 1000 rpm c) 3000 rpm d) 5000 rpm Ans: c 14. Large size thermal power plants will be: a) peak load plants b) Base load plants c) Can be operate either as peak load or base load plants d) None of the above Ans: b 15. The auxiliary consumption of thermal power plants will be in the range: a) 2-5% of plant power generated b) 8-10% of power generated c) 15-20% of power generated d) 20-25% of power generated Ans: b 16. Which of the following equipment is installed in steam power plant to reduce air pollution: a) Air filer b) HEPA filter c) Electro static precipitator d) All the above can be used Ans: c 17. Burning of low grade coal can be improved by: a) Pulverizing the coal b) Blending with high quality coal c) Oil assisted ignition d) All the above Ans: b 18. Equipment used for pulverizing the coal is: a) hopper b) Stoker c) Ball mill d) Electro static precipitator Ans: c 19. The percentage of carbon in anthracite is usually: a) More than 90% b) About 70% c) About 50% d) Below 40% Ans: a 20. for the same power the size of the turbine: a) Increases with speed b) Decreases with speed c) Constant irrespective of speed d) None of the above Ans: b THERMAL POWER PLANT Objective type Questions with Answers 21. Which type of coal has lowest calorific value? a) Peat b) Lignite c) Bituminous d) Anthracite Ans:b 22. Pipes carrying steam in thermal power plant are generally made of: a) Steel b) Cast iron c) aluminium d) Cobalt Ans: a 23. Economizer of boiler has main function of: a) Heat up the incoming water with excess steam b) Heat up the pulverized fuel by exhaust gases c) Heat up the incoming air by exhaust gases d) Heat up the incoming water by exhaust gases Ans: d 24. In a super heater: a) Pressure rises and temperature drops b) Temperature rises and pressure drops c) Temperature rises and pressure remains unchanged d) Pressure rises and temperature remains the same Ans: c 25. Steam turbine works on the principle of: a) carnot cycle b) brayton cycle c) rankine cycle d) None of the above Ans: c 26. The steam power plant efficiency can be improved by: a) Using large quantity of water b) Burning large quantity of coal c) Using high temperature and pressure of steam d) Decreasing the load on the plant Ans: c 27. As the size of the thermal power plant increases, the capital cost per kW of installed capacity: a) Increases b) Decreases c) Remains the same d) May increase and decrease Ans: b 28. Vacuum can be measured by using: a) rotameter b) pitot tube c) U tube manometer d) ventrimeter Ans: b 29. Electrostatic precipitator is installed between: a) Induced fan and chimney b) air preheater and induced fan c) Economizer and air preheater d) Boiler furnace and economiser Ans: b 30. Belt conveyors can be employed for transporting coal at inclination up to: a) 75 deg b) 60 deg c) 30 deg d) 15 deg Ans: c 31. In a shell and tube surface condenser: a) Steam passes through the tubes and cooling water surrounds them b) Cooling water passes through the tubes and steam surrounds them c) Steam and water mix to give condensate d) None of the above Ans: b 32. The purpose of Spray pond in Thermal power plant is: a) To deposit the ash coming out of the thermal power plant b) To cool the water coming out of condensate c) To remove the dissolved gases in the feed water d) None of the above Ans: b 33. For the forced draft the blower is located: a) At the top of the chimney b) Near the base of the chimney c) Near the base of the boiler d) None of the above Ans: c 34. It is important the heat the water before feeding to boiler because: a) The dissolved gases which corrodes the boiler are removed b) Thermal stresses arises due to the cold water entering the boiler can be reduced c) Some impurities carried by steam and condensate due to corrosion in boiler and condenser are precipitated outside the boiler d) All the above Ans: d 35. Which type of alternator is employed in thermal power plant? a) Salient type b) Non salient pole type c) Both can be used d) None of the above Ans: b 36. The indication to determine the incomplete combustion is: a) High percentage of carbon dioxide content in the flue gases b) High percentage of CO content in the flue gases c) High temperature of the flue gases d) All the above Ans: b 37. For the same drought required, the power of forced draught fan will be __ than the induced draught fan: a) Higher b) Lower c) The same d) May be more or less Ans: b 38. What are the combustible elements in the fuel: a) Carbon and hydrogen b) Carbon, hydrogen and ash c) Carbon, hydrogen and sulphur d) None of the above Ans: c 39. The efficiency of the thermal power plant is of the order: a) 15% b) 30% c) 50% d) 60% Ans: b 40. The coal which has highest ash content is: a) Lignite b) Coke c) Bituminous coal d) Peat Ans: a THERMAL POWER PLANT Questions and Answers pdf Download Read the full article

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Simple Ways To Save Energy

Simple Ways To Save Energy

Having visited this website, you will be aware of a great many DIY solutions to saving energy and water, but you can also make a difference to your electricity bills simply by changing your habits.

Switch Off

Our parents and grandparents were brought up to switch off the light when they left a room, but nowadays we have got into the habit of leaving lights switched on all over the house. Train yourself and your family to switch off unnecessary lighting. You only need a background illumination when watching TV; once you have settled down for the evening, perhaps just one or two table lamps are all you need for reading or playing games.

Stand-by Mode Many electrical appliances such as TV sets and music systems can be left on standby, so they can be reactivated using a remote control. The small lamp that indicates an appliance is in standby mode consumes an insignificant amount of electricity, but the cumulative effect represents wastage on a colossal scale. Unless you need to leave your equipment set up to record a program on TV or radio, try to remember to turn off these appliances at the socket.

Turn The Heating Down

Turning down the thermostat by 1° can save a great deal of money, and you probably won't even notice the difference in comfort.

Why not turn off the radiators in spare bedrooms that are infrequently used. If you need a gentle background heat in the room - to prevent condensation, for example - fit a thermostatically-controlled valve to the radiator.

Night Lights & Safety Lighting

If you have children, who are afraid to sleep in the dark, a special low-powered light fitting into a socket in the bedroom. This is a far more energy efficient than leaving a light burning on the landing. Similar fitting can provide low-level illumination on a landing in case someone needs to use the bathroom during the night. If that is not a practical solution, can you leave a table lamp or light are plugged into a timer that will switch off the lamp at dawn

Security lighting

Outdoor security lighting is essential if you want to identify a caller after dark. But don't install lighting that stays on permanently. Have a porch light that is activated by movement as the caller approaches the front door, and make sure the fitting has a dusk to dawn sensor that prevents the light coming on during daylight hours.

Boil Less Water

There is no need to fill the kettle each time you make a cup of tea or coffee. You can see the heating element inside older-style kettles and, provided there is enough water to cover the elements; you can't do any harm. If the element is concealed in the base, get used to using the measurements marked on the kettle to avoid overfilling it. Make sure the lid is fitted properly on the kettle will continue to boil without switching off.

You have to cover potatoes with water to boil improperly in a saucepan, but you can cook a steamer full of other vegetables on top of the same saucepan.

Cook More Efficiently

Instead of using the grill or hob, as well as the oven, to cook food, plan some meals so that you can use your oven to cook vegetables and meat at the same time.

A fan oven heats up faster than a conventional one, so don't switch your fan oven on to sin in order to bring it up to the temperature recommended in your cookbook. It can take as much as an hour to bake potatoes in the oven, but you can precook them in your microwave for about 10 minutes before putting them in your oven just to brown the skins.

Economise On Laundry

Most modern washing machines and detergents provide the opportunity to do the laundry on cool or fast program, which saves considerably on electricity.

Electric tumble dryers are a real boon, especially in the winter months. However, if you have the space in the garden, or even a balcony, hanging your washing on a clothes line in warm and windy weather could save you having to use your tumble dryer for up to 50 minutes per day.

Close Your Curtains

Fitting effective draught excluders is covered elsewhere on this site,but even draught-proofed windows can sap the warmth from a room. Close your curtains or blinds at dusk to reduce heat loss. Good quality lined curtains work best, especially if there is a closed pelmet across the top of the window.

Buy And Use Appliances Wisely

When buying new electrical appliances, look for labelling that provides information on the energy efficiency. Also, choose appliances that suit your personal lifestyle. As a single person, you can probably function very well with energy efficient compact fridges, dishwashers and ovens. Buy a slow cooker that uses a trickle of electricity during the day in order to have a meal ready when you get home.

A big family will use less energy and water by installing a large washing machine, instead of having to use a smaller appliance perhaps once or twice a day to keep up with the laundry.

Using an electric toaster every morning is more energy efficient and switching on your cooker grill and toast the bread.

Use Your Mobile Phone Alarm

A plug in alarm radio beside your bed uses a small amount of electricity day and night, simply to illuminate the clock face. To wake you up in the morning, use a mobile phone, which has an alarm facility that switches on the phone at the time you set. Alternatively, by a simple battery-operated alarm clock.

Christmas Illuminations

More and more we seem to be adopting the American custom of putting up extensive outdoor decorations at Christmas. It would be a pity to dispense with them altogether; but if you were to calculate the running cost of a house full with electric 'fairy' lights, you may think twice about it.

For more help and advice on how you can save money on your fuel bills call our office on 0131 538 3640

Read More Here: Simple Ways To Save Energy

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300 TOP POWER PLANT Engineering Objective Type Questions and Answers

POWER PLANT Engineering MCQS :-

1. The commercial sources of energy are (a) solar, wind and biomass (b) fossil fuels, hydropower and nuclear energy (c) wood, animal wastes and agriculture wastes (d) none of the above Ans: b 2. In India largest thermal power station is located at (a) Kota (b) Sarni (c) Chandrapur (d) Neyveli Ans: c 4. The percentage O2 by Weight in atmospheric air is (a) 18% (b) 23% (c) 77% (d) 79% Ans: b 5. The percentage 02 by volume in atmosphere air is (a) 21% (b) 23% (c) 77% (d) 79% Ans: a 6. The proper indication of incomplete combustion is (a) high CO content in flue gases at exit (b) high CO2 content in flue gases at exit (c) high temperature of flue gases (d) the smoking exhaust from chimney Ans: a 7. The main source of production of biogas is (a) human waste (b) wet cow dung (c) wet livestock waste (d) all above Ans: d 8. India's first nuclear power plant was installed at (a) Tarapore (b) Kota (c) Kalpakkam (d) none of the above Ans: a 9. In fuel cell, the ______ energy is converted into electrical energy. (a) mechanical (b) chemical (c) heat (d) sound Ans: b 10. Solar thermal power generation can be achieved by (a) using focusing collector or heliostates (b) using flat plate collectors (c) using a solar pond (d) any of the above system Ans: d 11. The energy radiated by sun on a bright sunny day is approximately (a) 700 W/m2 (b) 800 W/m2 (c) 1 kW/m2 (d) 2 kW/m2 Ans: c 12. Thorium Breeder Reactors are most suitable for India because (a) these develop more power (b) its technology is simple (c) abundance of thorium deposits are available in India (d) these can be easily designed Ans: c 13. The overall efficiency of thermal power plant is equal to (a) Rankine cycle efficiency (b) Carnot cycle efficiency (c) Regenerative cycle efficiency (d) Boiler efficiency x turbine efficiency x generator efficiency Ans: c 14. Rankine cycle efficiency of a good steam power plant may be in the range of (a) 15 to 20 per cent (6) 35 to 45 per cent (c) 70 to 80 per cent (d) 90 to 95 per ceut Ans: b 15. Rankine cycle operating on low pressure limit of p1 an 1 high pressure limit of p2 (a) has higher the renal efficiency than the carnot cycle operating between same pressure limits (b) has lower the"nal efficiency than carnot cycle operating between same pressure limit? (c) has same thermal efficiency as carnot cycle operating between same pressure limits (d) may be more or less depending upon the magnitude of p1 and p2 Ans: a 16. Rankine efficiency of a steam power plant (a) improves in summer as compared to that in winter (6) improves in winter as compared to that in summer (c) is unaffected by climatic conditions (d) none of the above Ans: b 17. Carnot cycle comprises of (a) two isentropic processes and two constant volume processes (b) two isentropic processes and two constant pressure processes (e) two isothermal processes and three constant pressure processes (d) none of the above Ans: b 18. In Rankine cycle the work output from the turbine is given by (a) change of internal energy between inlet and outlet (b) change of enthaply between inlet and outlet (c) change of entropy between inlet and outlet (d) change of temperature between inlet and outlet Ans: b 19. Regenerative cycle thermal efficiency (a) is always greater than simple Rankine thermal efficiency (b) is greater than simple Rankine cycle thermal efficiency only when steam is bled at particular pressure (c) is same as simple Rankine cycle thermal efficiency (d) is always less than simple Rankine cycle thermal efficiency Ans: a 20. In a regenerative feed heating cycle, the optimum value of the fraction of steam extracted for feed heating (a) decreases with increase in Rankine cycle efficiency (b) increases with increase in Rankine cycle efficiency (c) is unaffected by increase in Rankine cycle efficiency (d) none of the above Ans: b 21. In a regenerative feed heating cycle, the greatest economy is affected (a) when steam is extracted from only one suitable point of steam turbine (b) when steam is extracted from several places in different stages of steam turbine (c) when steam is extracted only from the last stage of steam turbine (d) when steam is extracted only from the first stage of steam turbine Ans: b 22. The maximum percentage gain in Regenerative feed heating cycle thermal efficiency (a) increases with number of feed heaters increasing (b) decreases with number of feed heaters increasing (c) remains same unaffected by number of feed heaters (d) none of the above Ans: a 23. In regenerative cycle feed water is heated by (a) exhaust gases (b) heaters (c) draining steam from the turbine (d) all above Ans: c 24. Reheat cycle in steam power plant is used to (a) utilise heat of flue gases (b) increase thermal efficiency (c) improve condenser performance (d) reduce loss of heat Ans: b 25. Mercury is a choice with steam in binary vapour cycle because it has (a) higher critical temperature and pressure (b) higher saturation temperature than other fluids (c) relatively low vapourisation pressure (d) all above Ans: d 26. Binary'vapour cycles are used to (a) increase the performance of the condenser (b) increase the efficiency of the plant (c) increase efficiency of the turbine Ans: b 27. A steam power station requires space (a) equal to diesel power station (b) more than diesel power station (c) less than diesel power station Ans: b 28. Economiser is used to heat (a) air (b) feed water (c) flue gases (d) all above Ans: b 29. The modern steam turbines are (a) impulse turbines (b) reaction turbines (c) impulse-reaction turbines (d) none of the above Ans: c 30. The draught which a chimney produces is called (a) induced draught (b) natural draught (c) forced draught (d) balanced draught Ans: b 31. The draught produced by steel chimney as compared to that produced by brick chimney for the same height is (a) less (b) more (c) same (d) may be more or less Ans: b 32. In a boiler installation the natural draught is produced (a) due to the fact that furnace gases being light go through the chimney giving place to cold air from outside to rush in (b) due to the fact that pressure at the grate due to cold column is higher than the pressure at the chimney base due to hot column (c) due to the fact that at the chimney top the pressure is more than its environmental pressure (d) all of the above Ans: b 33. The draught produced, for a given height of the chimney and given mean temperature of chimney gases (a) decreases with increase in outside air temperature (b) increases with increase in outside air temperature (c) remains the same irrespective of outside air temperature (d) may increase or decrease with increase in outside air temperature Ans: a 34. The draught produced by chimney of given height at given outside temperature (a) decreases if the chimney gas temperature increases (b) increases if the chimney gas temperature increases (c) remains same irrespective of chimney gas temperature (d) may increase or decrease Ans: b 35. For forced draught system, the function of chimney is mainly (a) to produce draught to accelerate the combustion of fuel (b) to discharge gases high up in the atmosphere to avoid hazard (c) to reduce the temperature of the hot gases discharged (d) none of the above Ans: b 36. Artificial draught is produced by (a) induced fan (b) forced fan (c) induced and forced fan (d) all of the above Ans: d 37. The draught in locomotive boilers is produced by (a) forced fan (b) chimney (c) steam jet (d) only motion of locomotive Ans: c 38. For the same draught produced the power of induced draught fan as compared to forced draught fan is (a) less (b) more (c) same (d) not predictable Ans: b 39. Artificial draught is produced by (a) air fans (b) steam jet (c) fan or steam jet (d) all of the above Ans: d 40. The artificial draught normally is designed to produce (a) less smoke (b) more draught (c) less chimney gas temperature (d) all of the above Ans: d 41. For the induced draught the fan is located (a) near bottom of chimney (b) near bottom of furnace (c) at the top of the chimney (D) anywhere permissible Ans: a 42. The pressure at the furnace is minimum in case of (a) forced draught system (b) induced draught system (c) balanced draught system (d) natural draught system Ans: c 43. The efficiency of chimney is approximately (a) 80% (b) 40% (c) 20% (d) 0.25% Ans: d 44. The isentropic expansion of steam through nozzle for the steam initially superheated at inlet is approximated by equation (a) pvls=C (b) pv1126 = C (c) pv1A = C (d) pv = C Ans: a 45. The ratio of exit pressure to inlet pressure for maximum mass flow rate per unit area of steam through a nozzle when steam is initially dry saturated is (a) 0.6 (6) 0.578 (c) 0.555 (d) 0.5457 Ans: b 46. The ratio of exit pressure to inlet pressure of maximum mass flow rate per area of steam through a nozzle when steam is initially superheated is (a) 0.555 (b) 0.578 (c) 0.5457 (d) 0.6 Ans: c 47. The critical pressure ratio of a convergent nozzle is defined as (a) the ratio of outlet pressure to inlet pressure of nozzle (b) the ratio of inlet pressure to outlet pressure of nozzle (c) the ratio of outlet pressure to inlet pressure only when mass flow rate per unit area is minimum (d) the ratio of outlet pressure to inlet pressure only when mass flow rate = c Ans: d 48. The isentropic expansion of steam through nozzle for the steam initially dry saturated at inlet is approximated by equation. (a)pv = C (b)pv1A = C (c)pv1i = C (d)pv Ans: d 49. The effect of considering friction losses in steam nozzle for the same pressure ratio leads to (a) increase in exit velocity from the nozzle (6) decrease in exit velocity from the nozzle (c) no change in exit velocity from the nozzle (d) increase or decrease depending upon the exit quality of steam Ans: b 50. The effect of considering friction in steam nozzles for the same pressure ratio leads to (a) increase in dryness fraction of exit steam (b) decrease in dryness fraction of exit steam (c) no change in the quality of exit steam (d) decrease or increase of dryness fraction of exit steam depending upon inlet quality Ans: a 51. In case of impulse steam turbine (a) there is enthalpy drop in fixed and moving blades (b) there is enthalpy drop only in moving blades (c) there is enthalpy drop in nozzles (d) none of the above Ans: c 52. The pressure on the two sides of the impulse wheel of a steam turbine (a) is same (b) is different (c) increases from one side to the other side (d) decreases from one side to the other side Ans: a 53. In De Laval steam turbine (a) the pressure in the turbine rotor is approximately same as in con¬denser (b) the pressure in the turbine rotor is higher than pressure in the con¬denser (c) the pressure in the turbine rotor gradually decreases from inlet to exit from condenser (d) none from the above Ans: a 54. Incase of reaction steam turbine (a) there is enthalpy drop both in fixed and moving blades (b) there is enthalpy drop only in fixed blades (c) there is enthalpy drop only in moving blades (d) none of the above Ans: a 55. Curtis turbine is (a) reaction steam turbine (b) pressure velocity compounded steam turbine (c) pressure compounded impulse steam turbine (d) velocity compounded impulse steam turbine Ans: b 56. Rateau steam turbine is (a) reaction steam turbine (b) velocity compounded impulse steam turbine (c) pressure compounded impulse steam turbine (d) pressure velocity compounded steam turbine Ans: c 57. Parson's turbine is (a) pressure compounded steam turbine (b) simple single wheel, impulse steam turbine (c) simple single wheel reaction steam turbine (d) multi wheel reaction steam turbine Ans: d 58. For Parson's reaction steam turbine, degree of reaction is (a) 75% (b) 100% (c) 50% (d) 60% Ans: c 59. Reheat factor in steam turbines depends on (a) exit pressure only (b) stage efficiency only (c) initial pressures and temperature only (d) all of the above Ans: c 60. The value of reheat factor normally varies from (a) 0.5 to 0.6 (b) 0.9 to 0.95 (c) 1.02 to 1.06 (d) 1.2 to 1.6 Ans: c 61. Steam turbines are governed by the following methods (a) Throttle governing (b) Nozzle control governing (c) By-pass governing (d) all of the above Ans: d 62. In steam turbines the reheat factor (a) increases with the increase in number of stages (b) decreases with the increase in number of stages (c) remains same irrespective of number of stages (d) none of the above Ans: a 63. The thermal efficiency of the engine with condenser as compared to without condenser, for a given pressure and temperature of steam, is (a) higher (b) lower (c) same as long as initial pressure and temperature is unchanged (d) none of the above Ans: a 64. In jet type condensers (a) cooling water passes through tubes and steam surrounds them (b) steam passes through tubes and cooling water surrounds them (c) steam and cooling water mix (d) steam and cooling water do not mix Ans: c 65. In a shell and tube surface condenser (a) steam and cooling water mix to give the condensate (b) cooling water passes through the tubes and steam surrounds them (c) steam passes through the cooling tubes and cooling water surrounds them (d) all of the above varying with situation Ans: b 66. In a surface condenser if air is removed, there is (a) fall in absolute pressure maintained in condenser (b) rise in absolute pressure maintained in condenser (c) no change in absolute pressure in the condenser (d) rise in temperature of condensed steam Ans: a 67. The cooling section in the surface condenser (a) increases the quantity of vapour extracted along with air (b) reduces the quantity of vapour extracted along with air (c) does not affect vapour quantity extracted but reduces pump capacity of air extraction pump (d) none of the above Ans: b 68. Edward's air pump (a) removes air and also vapour from condenser (b) removes only air from condenser (c) removes only un-condensed vapour from condenser (d) removes air alongwith vapour and also the condensed water from condenser Ans: d 69. In a steam power plant, the function of a condenser is (a) to maintain pressure below atmospheric to increase work output from the primemover (b) to receive large volumes of steam exhausted from steam prime mover (c) to condense large volumes of steam to water which may be used again in boiler (d) all of the above Ans: d 70. In a regenerative surface condenser (a) there is one pump to remove air and condensate (b) there are two pumps to remove air and condensate (c) there are three pumps to remove air, vapour and condensate (d) there is no pump, the condensate gets removed by gravity Ans: b 71. Evaporative type of condenser has (a) steam in pipes surrounded by water (b) water in pipes surrounded by steam (c) either (a) or (b) (d) none of the above Ans: a 72. Pipes carrying steam are generally made up of (a) steel (b) cast iron (c) copper (d) aluminium Ans: a 73. For the safety of a steam boiler the number of safety valves fitted are (a) four (b) three (c) two (d) one Ans: c 74. Steam turbines commonly used in steam power station are (a) condensing type (b) non-condensing type (c) none of the above Ans: a 75. Belt conveyer can be used to transport coal at inclinations upto (a) 30° (b) 60° (c) 80° (d) 90° Ans: a 76. The maximum length of a screw conveyer is about (a) 30 metres (b) 40 metres (c) 60 metres (d) 100 metres Ans: a 77. The efficiency of a modern boiler using coal and heat recovery equipment is about (a) 25 to 30% (b) 40 to 50% (c) 65 to 70% (d) 85 to 90% Ans: d 78. The average ash content in Indian co als is about (a) 5% (b) 10% (c) 15% (d) 20% Ans: d 79. Load center in a power station is (a) center of coal fields (b) center of maximum load of equipments (c) center of gravity of electrical system Ans: c 80. Steam pressure in a steam power station, which is usually kept now-a-days is of the order of (a) 20 kgf/cm2 (b) 50 kgf/cm2 (c) 100 kgf/cm2 (d) 150 kgf/cm2 Ans: d 81. Economisers improve boiler efficiency by (a) 1 to 5% (b) 4 to 10% (c) 10 to 12% Ans: b 82. The capacity of large turbo-generators varies from (a) 20 to 100 MW (b) 50 to 300 MW (c) 70 to 400 MW (d) 100 to 650 MW Ans: b 83. Caking coals are those which (a) burn completely (b) burn freely (c) do not form ash (d) form lumps or masses of coke Ans: d 84. Primary air is that air which is used to (a) reduce the flame length (b) increase the flame length (c) transport and dry the coal (d) provide air around burners for get¬ting optimum combustion Ans: c 85. Secondary air is the air used to (a) reduce the flame length (b) increase the flame length (c) transport and dry the coal (d) provide air round the burners for getting optimum combustion Ans: d 86. In coal preparation plant, magnetic separators are used to remove (a) dust (b) clinkers (c) iron particles (d) sand Ans: c 87. Load carrying capacity of belt conveyor is about (a) 20 to 40 tonnes/hr (b) 50 to 100 tonnes/hr (c) 100 to 150 tonnes/hr (d) 150 to 200 tonnes/hr Ans: b 88. Method which is commonly applied for unloading the coal for small power plant is (a) lift trucks (b) coal accelerators (c) tower cranes (d) belt conveyor Ans: b 89. Bucket elevators are used for (a) carrying coal in horizontal direction (b) carrying coal in vertical direction (c) carrying coal in any direction Ans: b 90. The amount of air which is supplied for complete combustion is called (a) primary air (b) secondary air (c) tertiary air Ans: b 91. In ______ system fuel from a central pulverizing unit is delivered to a bunker and then to the various burners (a) unit (b) central (c) none of the above Ans: b 92. Under-feed stokers work best for _______ coals high in volatile matter and with caking tendency (a) anthracite (b) lignite (c) semibituminous and bituminous Ans: c 93. Example of overfeed type stoker is (a) chain grate (b) spreader (c) travelling grate (d) all of the above Ans: d 94. Where unpulverised coal has to be used and boiler capacity is large, the stoker which is used is (a) underfeed stoker (b) overfeed stoker (c) any Ans: b 95. TravelUng grate stoker can burn coals at the rates of (a) 50—75 kg/m per hour (b) 75—100 kg/m per hour (c) 100—150 kg/m per hour (d) 150—200 kg/m2 per hour Ans: d 96. Blowing down of boiler water is the process (a) to reduce the boiler pressure (b) to increase the steam temperature (c) to control the solid concentration in the boiler water by removing some of the concentrated saline water (d) none of the above Ans: c 97. Deaerative heating is done to (a) heat the water (b) heat the air in the water (c) remove dissolved gases in the water Ans: c 98. Reheat factor is the ratio of (a) isentropic heat drop to useful heat drop (b) adiabatic heat drop to isentropic heat drop (c) cumulative actual enthalpy drop for the stages to total is isentropic enthalpy heat drop Ans: c 99. The value of the reheat factor is of the order of (a) 0.8 to 1.0 (b) 1.0 to 1.05 (c) 1.1 to 1.5 (d) above 1.5 Ans: c 100. Compounding of steam turbine is done for (a) reducing the work done (b) increasing the rotor speed (c) reducing the rotor speed (d) balancing the turbine Ans: c Read the full article