4AE3 U12 C6 Review
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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</p> Signup and view all the answers

    What can be a consequence of ash accumulation in boilers?

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

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

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

    What is the effect of fireside deposits on steam production?

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

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

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

    What is the characteristic of acoustic cleaning systems?

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

    Why do retractable soot blowers retract when not in use?

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

    Where are air heater soot blowers typically located?

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

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

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

    What is the effect of fireside deposits on fireside temperatures?

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

    What is the primary benefit of in-service cleaning?

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

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

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

    What is the effect of fireside deposits on steam production?

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

    What is the characteristic of falling shot systems?

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

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