Interview Questions In Boiler | Placement Questions In Mechanical Engineering | Placement Papers With Answers

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  • What is the differences between gas turbine and a steam turbine?

Gas turbine works on Bryton cycle where as steam turbine works Rankine cycle. Construction, operation of a gas turbine are entirely different to steam turbine. Gas turbine has a compressor to compress the combustion air, a combustion chamber to burn the fuel and a turbine section to extract the work for burning fuel. Steam turbine is just has a turbine section to extract the work from steam.

  • What is operating pressure?

The amount of pressure nearest the point of performing work at the output end of a pneumatic system. The system operating pressure is used to specify the capability of valves and actuators.

  • What are the safety valves? How many on each boiler?

A valve opening automatically to relieve excessive pressure, especially in a boiler.

There are normally two to six safety valves provided in the drum depending upon the capacity.

The super heater outlet will have one to three safety valves on either side of the boiler. There will be an electromatic relief valve on the super heater pipe in addition. This valve will be set at lower pressure than the lowest set safety valve on the super heater.

The reheater pipes both at the inlet and outlet side will also have safety valves which can range from two to eight both in the inlet and outlet of the reheater put together.

  • What is a sentinel valve?

Sentinel valves are simply small relief valves installed in some systems to warn of impending over pressurization. Sentinel valves do not relieve the pressure of the system. If the situation causing the sentinel valve to lift is not corrected, a relief valve (if installed) will lift to protect the system or component. If a relief valve is not installed, action must be taken quickly to secure the piece of equipment or system to reduce the pressure.

  • What is the function of Hydrogen seals work on a generator?

Provide a seal between the generator housings and rotor shaft to maintain the pressurized hydrogen gas inside the generator. Also, provides a trap-vent system to prevent the release of hydrogen into the turbine generator lube oil system and building atmosphere.

  • How is the excess discharge pressure prevented?

Pressure relief valves on the discharge side of each seal oil pump relieves back to seal oil system.

  • Which two seal oil pumps are driven from the same motor?

Main seal oil pump and re-circular seal oil pump; both are driven by Main seal oil pump motor.

  • When does Emergency Seal Oil Pump automatically start?

When its pressure switch senses Main Seal Oil Pump discharge pressure reduced to 78 PSI.

  • What is the consequence of not maintaining hydrogen (or air) pressure in generator casing at a value above atmospheric pressure when seal oil system is in service?

Failure to do so will cause excessive seal oil to be drawn into the generator.

Vision Gauge Digital Optical Comparator | Optical Comparator Measurement | Digital Optical Comparator Machine

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The Vision Gauge Digital Optical Comparator is "The Fastest, Easiest, Most Accurate Way to Compare a Part to a CAD File. Vision Gauge Digital Optical Comparators are very robust. They are perfect for both the shop floor and the Quality Control lab. Standard 12" travel X-axis stage with 0.5 micron resolution encoder and protective bellows around the 6" travel Y-axis column. All 3 axes (X, Y and Z) have high-accuracy crossed roller movements for optimal linearity and positional repeatability and high load carrying capability. Hard chrome plated X-axis stage, made of hardened tooling steel and with dual industry-standard dovetail grooves for easy part fixturing.

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Vision Gauge Digital Optical Comparators are complete, ready-to-run Windows-based solutions and  are  delivered network-ready. They are available in both horizontal and vertical configurations. They have industry standard dovetail mounting grooves for easy part fixturing.

Vision Gauge Digital Optical  Comparators are available  with transmitted (i.e. back) and / or reflected (i.e. front) illumination.  All  illumination  is  LED-based for very stable and repeatable illumination  conditions  over  a  very  long  life  (no  more  bulbs  to replace!). Furthermore, the illumination is programmable and computer-controlled. Everything is done through a single simple an d intuitive software interface.

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Vision Gauge Digital Optical  Comparators have power focus. They are available in industry standard 5X, 10X, 20X,  50X  and 100X  optical configurations.  They are available in both single and multi-mag configurations.

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Vision Gauge Digital Optical Comparators and extremely easy to use. They are a "drop in" replacement for traditional optical comparators. An optional high-resolution LASER module is also available for depth & height measurements. Motorized fixtures and extended travels are also available.

Benefits:

  • Produce a very high contrast image with very sharp edge profiles so that there is no problem viewing it in full daylight.
  • Are much more accurate
  • Allow the user to be much more productive and get more work done with a single machine
  • Have "Auto Pass / Fail"
  • Can compute and display the part’s deviation from nominal and compare it to bi-directional tolerances
  • Work directly with the CAD data so that no overlays / templates / Mylars are required
  • Can be used to collect images (either with or without the CAD data overlay and with or without annotations), measurements and data .
  • Can also carry out fully automated measurements (like a video CMM)
  • Have a smaller footprint and use less floor space
  • Can be moved much more easily and without requiring re-calibration (i.e. “rolling cart” configuration is standard)
  • Have a much greater optical depth of field, i.e. “everything is in focus all at once”
  • Have a longer optical working distance ( i.e. more clearance between the part and the lens)
  • Allow you to compare a part to its CAD data beyond the optical field-of-view ! (because the CAD data tracks the part and follows the stage motion )
  • Have LED illumination for very stable illumination over a 10 year life. No more bulbs to change

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