4AE3 U12 C6 Review
112 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary purpose of routine fireside cleaning in modern steam generators?

  • To reduce the production of steam
  • To increase the temperature of the steam
  • To reduce the flow of combustion gases
  • To maintain boiler efficiency and steaming capacity (correct)

What is the effect of soot and ash deposits on heat transfer surfaces in boilers?

  • They increase the boiler efficiency
  • They reduce the heat transfer rate (correct)
  • They increase the heat transfer rate
  • They have no effect on the heat transfer rate

What can be an indication of poor heat transfer performance in boilers?

  • High flue gas temperatures and a reduction in steam production (correct)
  • Low flue gas temperatures
  • Low firing rate
  • High steam production

What can be used to maintain flue fireside cleanliness in boilers?

<p>Soot blowers, periodic water washing, or mechanical cleaning (D)</p> Signup and view all the answers

What can be a consequence of ash accumulation in boilers?

<p>Restricted flow and impeded heat transfer (B)</p> Signup and view all the answers

What is the primary maintenance aspect of heat transfer surfaces in boilers?

<p>Surface cleanliness and good flue gas flow (A)</p> Signup and view all the answers

What is the primary purpose of soot blowers in fireside cleaning?

<p>To permit in-service fireside cleaning (C)</p> Signup and view all the answers

What is the effect of increased fireside deposits on boiler operation?

<p>Lower boiler efficiency and higher flue gas temperatures (C)</p> Signup and view all the answers

When is it necessary to perform out-of-service cleaning?

<p>During the annual or semiannual scheduled outages (B)</p> Signup and view all the answers

What is the purpose of a chemical treatment in fireside cleaning?

<p>To remove corrosive compounds from the boiler (B)</p> Signup and view all the answers

What is the effect of fireside deposits on pressure differential across heat transfer surfaces?

<p>It increases the pressure differential (C)</p> Signup and view all the answers

What is the primary concern when introducing water during cleaning?

<p>Ensuring the water is introduced with great care (A)</p> Signup and view all the answers

What is the advantage of in-service fireside cleaning?

<p>It reduces the need for out-of-service cleaning (D)</p> Signup and view all the answers

What is the purpose of visual examination of deposit patterns during an outage?

<p>All of the above (D)</p> Signup and view all the answers

What is the result of heavy fireside deposits on draft loss?

<p>It increases draft loss (B)</p> Signup and view all the answers

What is the effect of fireside deposits on steam production?

<p>It decreases steam production (B)</p> Signup and view all the answers

What is the primary purpose of continuous in-service cleaning in boilers?

<p>To optimize the boiler's heat transfer efficiency and availability (B)</p> Signup and view all the answers

What is the most common method of in-service fireside cleaning in boilers?

<p>Soot blowers (B)</p> Signup and view all the answers

What is the purpose of the poppet valve in soot blowers?

<p>To introduce dry, high-pressure steam into the lance (C)</p> Signup and view all the answers

What is the advantage of using air as a soot blowing medium?

<p>It is compact, simple in construction, and relatively inexpensive (A)</p> Signup and view all the answers

What is the purpose of acoustic cleaning systems in boilers?

<p>To knock ash off boiler tubes with acoustic energy (C)</p> Signup and view all the answers

What is the characteristic of acoustic cleaning systems?

<p>They operate continuously in successive short cycles (D)</p> Signup and view all the answers

What is the purpose of rapping systems in boilers?

<p>To remove deposits from the heating surfaces without additional cleaning medium (A)</p> Signup and view all the answers

What is the effect of the rapping system on the heating tube bundles?

<p>It shakes off the material buildup (C)</p> Signup and view all the answers

Why is it important to drain the condensate from the soot blower lance?

<p>To prevent erosion from moisture or condensate (C)</p> Signup and view all the answers

What is the advantage of using steam as a soot blowing medium in larger boilers?

<p>It is available whenever the boiler is in service (A)</p> Signup and view all the answers

What is the primary advantage of pneumatic rapping systems over other methods?

<p>They enable higher impact energies (B)</p> Signup and view all the answers

What is the purpose of the falling shot system in boilers?

<p>To remove ash deposits from the tube surfaces (D)</p> Signup and view all the answers

Why are explosives sometimes used in in-service cleaning?

<p>To remove large deposits that cannot be dislodged by conventional methods (D)</p> Signup and view all the answers

What is the purpose of retractable soot blowers in the radiant zone of the boiler?

<p>To clean heat transfer surfaces (D)</p> Signup and view all the answers

Why do retractable soot blowers retract when not in use?

<p>To prevent overheating and damage (D)</p> Signup and view all the answers

What is the primary cause of slag buildup in the radiant zone of the furnace?

<p>Molten ash coming into contact with cool furnace walls (C)</p> Signup and view all the answers

How do short retractable wall blowers remove ash deposits?

<p>By using a jet of superheated steam or air (D)</p> Signup and view all the answers

What is the purpose of the long retractable soot blower?

<p>To clean the radiant and convection heating surfaces (C)</p> Signup and view all the answers

Why do long retractable soot blowers hang from a carriage outside the boiler furnace?

<p>To prevent overheating and damage (D)</p> Signup and view all the answers

What is the purpose of the inner tube in the long retractable soot blower?

<p>To convey steam to the nozzle (B)</p> Signup and view all the answers

What is the primary function of the chains and reduction gear mechanism in a stationary soot blower?

<p>To rotate the lance and clean more area (D)</p> Signup and view all the answers

Where are air heater soot blowers typically located?

<p>Over the top of the heat exchange surface (B)</p> Signup and view all the answers

What is the minimum boiler load required for stable combustion during soot blowing, according to ASME BPVC Section VII?

<p>50 percent (B)</p> Signup and view all the answers

What is the purpose of the hopper in a falling shot cleaning system?

<p>To collect the ash particles and shot (B)</p> Signup and view all the answers

What is the advantage of not requiring a supply of air or steam for the operation of falling shot cleaning?

<p>It reduces the steam consumption of the soot blowers (C)</p> Signup and view all the answers

What is the primary function of the distributing chamber in a falling shot cleaning system?

<p>To recycle the iron shot (D)</p> Signup and view all the answers

What is the purpose of the pneumatic conveying system in a falling shot cleaning system?

<p>To return the shot to the top distributing chamber (A)</p> Signup and view all the answers

What happens to the ash particles that are removed by the shot in a falling shot cleaning system?

<p>They are recycled with the shot (C)</p> Signup and view all the answers

What is the advantage of using falling shot cleaning in small plants?

<p>It does not affect the turbine steam supply (B)</p> Signup and view all the answers

What is the purpose of the control screen for soot blower sequencing and operation?

<p>To sequence the soot blowers and alert the operator of stuck blowers (B)</p> Signup and view all the answers

What is the purpose of the sealing arrangement in the soot blower system?

<p>To prevent steam from escaping (B)</p> Signup and view all the answers

What is the function of the drive motor in the soot blower system?

<p>To push the soot blower lance into the furnace (A)</p> Signup and view all the answers

How does the linkage connected to the carriage function in the soot blower system?

<p>It opens the soot blower poppet valve (D)</p> Signup and view all the answers

What is the purpose of the rollers on the inner support in the soot blower system?

<p>To support the lance (B)</p> Signup and view all the answers

Why is it important to maintain steam flow to the soot blower until it is fully retracted?

<p>To prevent the lance from overheating (D)</p> Signup and view all the answers

What is the purpose of the two opposed nozzles at the tip of the retractable soot blower lance?

<p>To emit a jet of superheated steam or compressed air (A)</p> Signup and view all the answers

Why is it important to adjust the soot blower so that it does not impinge directly upon tubes?

<p>To prevent the tubes from eroding (A)</p> Signup and view all the answers

In which zones of the boiler are stationary non-retractable soot blowers typically used?

<p>Convection zones, such as the economizer, generating bank, and air heater (C)</p> Signup and view all the answers

How are the lance tubes held in place in stationary soot blowers?

<p>With bearings (B)</p> Signup and view all the answers

What is the purpose of sequencing the use of multiple soot blower units in a boiler?

<p>To move the ash and soot to a specific point in the boiler for removal (B)</p> Signup and view all the answers

What is the primary consequence of soot and ash deposits on heat transfer surfaces in boilers?

<p>Reduced heat transfer rate (D)</p> Signup and view all the answers

Why is routine fireside cleaning essential in modern steam generators?

<p>To maintain boiler steaming capacity and efficiency (B)</p> Signup and view all the answers

What is the effect of ash accumulation on gas flow in boilers?

<p>Ash accumulation restricts gas flow (C)</p> Signup and view all the answers

What is the primary indication of poor heat transfer performance in boilers?

<p>High flue gas temperatures and a reduction in steam production at a given firing rate (A)</p> Signup and view all the answers

What is the result of a gradual buildup of fireside or waterside deposits in boilers?

<p>Reduced heat transfer performance (D)</p> Signup and view all the answers

What is the primary purpose of maintaining flue fireside cleanliness in boilers?

<p>To maintain boiler efficiency and steaming capacity (D)</p> Signup and view all the answers

What is the primary effect of fireside deposits on boiler operation?

<p>Lower boiler efficiency due to reduced heat transfer (A)</p> Signup and view all the answers

During a major outage, what is typically done to the furnace water walls?

<p>They are washed with high-pressure water (C)</p> Signup and view all the answers

What is the primary consideration when deciding between in-service and out-of-service cleaning?

<p>The amount of out-of-service time required (D)</p> Signup and view all the answers

What is the result of increased draft loss through the boiler, economizer, superheater banks, or air heaters?

<p>Heavy fireside deposits (D)</p> Signup and view all the answers

What is the purpose of soot blowers in solid fuel-fired units?

<p>To remove ash and soot from heat transfer surfaces (B)</p> Signup and view all the answers

What is the effect of fireside deposits on fireside temperatures?

<p>They increase fireside temperatures (C)</p> Signup and view all the answers

What is the primary benefit of in-service cleaning?

<p>Reduced downtime (A)</p> Signup and view all the answers

What is the purpose of a chemical treatment during a major outage?

<p>To reduce corrosion (A)</p> Signup and view all the answers

What is the effect of fireside deposits on steam production?

<p>They decrease steam production (B)</p> Signup and view all the answers

What is the primary consideration when introducing water during cleaning?

<p>The potential for corrosive compounds to form (D)</p> Signup and view all the answers

What is the primary reason for using steam as a soot blowing medium in larger boilers?

<p>It is available whenever the boiler is in service (C)</p> Signup and view all the answers

What is the purpose of the poppet valve in soot blowers?

<p>To introduce dry, high-pressure steam into the lance (D)</p> Signup and view all the answers

Why is it important to drain the condensate from the soot blower lance?

<p>To prevent erosion from moisture or condensate (A)</p> Signup and view all the answers

What is the advantage of acoustic cleaning systems?

<p>They require less energy than other soot blowing operations (B)</p> Signup and view all the answers

What is the purpose of rapping systems in boilers?

<p>To remove deposits from the heat transfer surfaces (A)</p> Signup and view all the answers

Why are soot blowers in radiant zones designed to withstand more heat than those in convection zones?

<p>Because they are subjected to higher temperatures (C)</p> Signup and view all the answers

What is the effect of increased fireside deposits on boiler operation?

<p>Decreased pressure differential across heat transfer surfaces (B)</p> Signup and view all the answers

What is the primary advantage of using air as a soot blowing medium?

<p>It is compact and simple in construction (A)</p> Signup and view all the answers

What is the purpose of the wave generator in acoustic cleaning systems?

<p>To produce a series of sound-induced pressure fluctuations (D)</p> Signup and view all the answers

What is the characteristic of acoustic cleaning systems that allows them to operate continuously?

<p>They operate in successive short cycles (A)</p> Signup and view all the answers

What is the primary advantage of using explosives for in-service cleaning in boilers?

<p>It can dislodge larger deposits that cannot be removed with conventional methods (B)</p> Signup and view all the answers

What is the purpose of the jet at the end of the lance in a short retractable wall blower?

<p>To blast superheated steam or air against the slag deposits (A)</p> Signup and view all the answers

What is the characteristic of falling shot systems?

<p>They use small steel balls to remove deposits (B)</p> Signup and view all the answers

What is the purpose of the carriage in a long retractable soot blower?

<p>To hang the soot blower outside the boiler furnace (B)</p> Signup and view all the answers

What is the primary cause of slag buildup in the radiant zone of the furnace?

<p>Ash contained in the fuel may melt in the high temperature (A)</p> Signup and view all the answers

Why are pneumatic rapping systems recommended for heavy deposits?

<p>They enable higher impact energies and have a better cleaning effect (B)</p> Signup and view all the answers

What is the purpose of the internal feed tube in the long retractable soot blower?

<p>To convey steam from the poppet valve to the outer tube (D)</p> Signup and view all the answers

What is the result of the falling shot on the ash deposits in the boiler?

<p>The ash deposits are removed from the tube surfaces (B)</p> Signup and view all the answers

What is the purpose of the retractable blower in the radiant zone of the boiler?

<p>To remove slag deposits from the heat transfer surfaces (B)</p> Signup and view all the answers

What is the primary concern when using explosives for in-service cleaning in boilers?

<p>The proper training and certification of operators involved in explosive procedures (C)</p> Signup and view all the answers

What is the primary reason for rotating the lance in a stationary soot blower?

<p>To clean substantially more area than a non-rotating lance (B)</p> Signup and view all the answers

Where are the nozzles situated in an air heater soot blower?

<p>Over the top of the heat exchange surface (D)</p> Signup and view all the answers

What is the minimum boiler load required for stable combustion during soot blowing, according to ASME BPVC Section VII?

<p>50% of the boiler capacity (C)</p> Signup and view all the answers

How are the iron shot or pellets recycled in a falling shot cleaning system?

<p>They are pneumatically conveyed back to the distributing chamber (B)</p> Signup and view all the answers

What is the purpose of the control screen for soot blower sequencing and operation?

<p>To sequence the operation of the soot blowers (C)</p> Signup and view all the answers

Why is it necessary to ensure furnace pressure is below atmospheric during soot blowing?

<p>To prevent blowback through inspection doors and other openings (A)</p> Signup and view all the answers

What happens to the large ash particles that are removed by the shot in a falling shot cleaning system?

<p>They are broken up into fine particles and carried away by the flue gas (D)</p> Signup and view all the answers

What is the primary advantage of falling shot cleaning over other methods of cleaning?

<p>It does not require a supply of air or steam for operation (A)</p> Signup and view all the answers

What is the purpose of the distributing chamber in a falling shot cleaning system?

<p>To distribute the iron shot or pellets to the tubes (C)</p> Signup and view all the answers

What is the primary purpose of the hopper in a falling shot cleaning system?

<p>To collect the ash particles that are removed (B)</p> Signup and view all the answers

What is the primary function of the pinion gear in the soot blower drive system?

<p>To push the lance into the furnace (A)</p> Signup and view all the answers

What is the purpose of the forward position limit stop in the soot blower system?

<p>To prevent the lance from moving too far into the boiler (A)</p> Signup and view all the answers

Why is it necessary to maintain steam flow to the soot blower until it is fully retracted?

<p>To prevent the lance from overheating (A)</p> Signup and view all the answers

What is the purpose of the chain and sprocket arrangement in the soot blower system?

<p>To rotate the lance during the cleaning cycle (A)</p> Signup and view all the answers

What is the effect of impinging directly upon tubes with the soot blower?

<p>The tubes will be rapidly eroded (D)</p> Signup and view all the answers

What is the purpose of the bearings in stationary soot blowers?

<p>To hold the lance tube in place (B)</p> Signup and view all the answers

What is the purpose of sequencing the use of multiple soot blower units in a boiler?

<p>To allow the ash and soot to be moved to a specific point in the boiler for removal (C)</p> Signup and view all the answers

What is the purpose of the rollers on the inner support in the soot blower system?

<p>To assist in supporting the lance (C)</p> Signup and view all the answers

What is the effect of moisture in the blowing medium on the erosion of tubes?

<p>It increases the rate of erosion (D)</p> Signup and view all the answers

What is the purpose of the limit switch in the soot blower system?

<p>To shut down the drive motor (C)</p> Signup and view all the answers

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser