Functions of Boiler Accessories on a steam boiler

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Boiler Accessories: These are the devices which are used as integral parts of a boiler and help in running efficiently.

  • Feed pump
  • Super heater
  • Economiser
  • Air Preheater
  • Injector

Accessories Descriptions:

       1. Feed pump

It is used to deliver water to the boiler. A feed pump may be of centrifugal type or reciprocating type. But a double acting reciprocating pump is commonly used as a feed pump.

      2. Super heater

It is an important devices of a steam generating unit. Its purpose is to increase the temperature of saturated steam without raising its pressure. It is generally an integral part of a boiler and is places in the path of hot flue gases from the furnace.

Advantages:

  • Steam consumption of the engine is reduced.
  • Losses due to the condensation in the cylinders and steam pipes are reduced.
  • Efficiency of the steam plant is increased.

      3. Economizer

An Economizer  is a device used to heat feed water by utilizing the heat in the exhaust flue gases before leaving through the chimney.

Advantages:

  • There is about 15-20% of coal saving
  • It increases the steam raising capacity of a boiler
  • Its prevents formation of scale in boiler water tubes, because the scale now formed in the economiser tubes, which can be cleaned easily.

Schematic diagram of a boiler plant

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Competitive Exam Questions for Mechanical Engineers

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Competitive Exam Questions for Mechanical Engineers:

Bangladesh Power Development Board (BPDB)

  1. What is the deviation of Ideal Rankine Cycle and Actual Rankine Cycle?
  2. List of main components of Steam power plant.
  3. Advantages of gas turbine over steam turbine.
  4. Draw the schematic diagram of combined cycle power plant.
  5. Draw the T-S Diagram of Vapor-Compression cycle.

Rural Power Company Limited (RPCL)

  1. What is Octane and Cetane number?
  2. What is Boiler? Differentiate fire tube and water tube boiler.
  3. What is Newtonian and Non-Newtonian fluid?
  4. Write down the viscosity in MLT and derive the unit in MKS, CGS, and SI System.
  5. Why Flywheel is an essential part of the engine?
  6. Write down the four laws of Thermodynamics.
  7. What is COP and Ton of refrigeration?
  8. What is stress and strain? Draw the stress-strain curve for Non-Newtonian alloys
  9.  What is volumetric efficiency?
  10. Meaning of SOHC, VVTI, VTEC, ABS
  11.  Differentiate between Closed, Open and Isolated System.
  12. What is knocking in I.C. Engine? What is the effect of Knocking?

Titas Gas Transmission & distribution Company Limited (TGTDCL)

  1. Difference between pump, compressor, blower and fan
  2. What is volumetric efficiency?
  3. What is Ton of Refrigeration?
  4. Write the second Law of Thermodynamics with Example.
  5. What is Carnot Cycle
  6. What is closed cycle Gas turbine and draw the , P-V diagram and T-S Diagram of Closed cycle gas turbine
  7. What is VVTI?
  8. What is Reynolds Number? What is the significant of Reynolds Number?
  9. What is Nusselts Number?
  10. What is Centrifugal pump and write the different parts of the Centrifugal pump and the Performance curve of Centrifugal Pump.

Bangladesh Agricultural Development Corporation (BADC)

  1. What is Chocking in Compressor?
  2. What will be effect if Advancing Spark time in SI Engine?
  3. Which Compressor is used in Aeroplane Engine?
  4. Write Boyle Law.

Bangladesh Steel & Engineering Corporation (BSEC)

  1. Differentiate between Impulse and Reaction Turbine. What is staging in turbine?
  2. What is draft tube in Hydraulic turbine?
  3. Draw the block diagram of Vapor compression refrigeration system and the P-V , T-S Diagram
  4. What are the characteristics of good refrigerant? Why sub-cooling is necessary in refrigeration system.
  5. Write down the major and minor losses in pumping system
  6. Write down the second law of thermodynamics with practical examples.
  7. Differentiate between CI and SI Engine
  8. Why flywheel is used in IC Engines?
  9. What is CCPT (combined cycle power plant) . What’s type of cycle use in CCPT?
  10. What is the other name of joule cycle? Draw the p-v diagram of a joule cycle?
  11. What is cavitation? What happen when it occurs?
  12. Why use lubricant and lube oil? When you should change lube oil?
  13. Name the Types of bearing?

Bangladesh Bank (Assistant Director- Mechanical)

  1. What is Ton of refrigeration?
  2. What are Jigs and Fixtures?
  3. Write down the Major lathe operations.
  4. What is the significance of Reynolds number?
  5. What is the Significance of Mach Number?

Dhaka Power Distribution Company Limited (DPDC)

  1. Write down the important components of air conditioning.
  2. Draw the P-V diagram of Otto and Diesel cycle and show their process in the diagram.

Dhaka WASA (D-WASA)

  1. What is Absolute Pressure?
  2. How many chips formation in metal cutting? Write the name of the chips formation.

Others Sample Exam Questions

  1. The Purposes of Heat treatment.
  2. Difference between ABS and TCS
  3. 1st Law of Thermodynamics
  4. What is refrigeration?
  5. Write down the Ohm’s law
  6. Difference between IC Engine and Steam Engine
  7. Why cutting fluid used?
  8. What is EFI?
  9. Describe- a) Compression ratio b) Poision ratio c) Volumetric efficiency d) Piston displacement
  10. Difference between motor and pump.
  11. Difference between impulse turbine and reaction turbine
  12. Difference between supercharge and turbocharger
  13. Advantages and disadvantages of LPG in using a CAR..

Important Abbreviations for Mechanical Engineering

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Important Abbreviations for Mechanical Engineering:

  1. DOHC– Double Overhead Camshaft
  2. SOHC– Single Overhead Camshaft
  3. HCCI– Homogeneous Charge Compression Ignition
  4. ABS– Anti lock Braking System
  5. VTEC– Variable Valve Timing and lift Electronic Control
  6. VVT-i– Variable Valve Timing with Intelligence
  7. VVTL-i– Variable Valve Timing and Lift with Intelligence
  8. i-VTEC– Intelligent Variable valve Timing and lift Electronic Control
  9. ACT– Air Charge Temperature
  10. MFI– Multi port Fuel Injection
  11. CFI– Continuous Fuel Injection
  12. DGI– Direct Gasoline Injection
  13. PFI– Port Fuel Injection
  14. ECM– Electronic Control Module
  15. EEC– Electronic Engine Control
  16. EFI– Electronic Fuel Injection
  17. EMI– Electromagnetic Interference
  18. SBS– Supercharger Bypass Solenoid
  19. HCM– Heating Control Module
  20. GPS– Global Positioning system
  21. VECI– Vehicle Emission Control Information
  22. VES– Variable Effort Steering
  23. VTSS– Vehicle Theft Security System
  24. VTA– Vehicle Theft Alarm