4AE3 U11 C3 Review
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Questions and Answers

What is the definition of a watertube boiler according to the ABMA?

  • A boiler in which the tubes contain water and steam, the heat being applied to the outside surface (correct)
  • A boiler in which the drums and headers are connected by combustion gases-filled tubes
  • A boiler in which the tubes contain combustion gases and heat is applied to the inside surface
  • A boiler in which the heat is applied to the inside surface and combustion gases travel inside the tubes

    • What was a limitation of early watertube boilers?

  • The drums and headers were too small
  • The use of straight tubes restricted the location of heat transfer surface (correct)
  • The combustion gases were not hot enough
  • The use of bent tubes restricted the location of heat transfer surface

    • What advance in technology allowed boiler manufacturers to confidently install bent tubes?

  • Advances in burners and control systems
  • Advances in water treatment technology (correct)
  • Advances in welding methods
  • Advances in riveted construction

    • What was the result of using bent tubes in watertube boilers?

    <p>A reduction in the amount of refractory brickwork (B)</p> Signup and view all the answers

    What replaced riveted construction in watertube boilers?

    <p>Welded construction (C)</p> Signup and view all the answers

    What were the benefits of the development of modern watertube boilers?

    <p>They became increasingly safe to operate (B)</p> Signup and view all the answers

    Where is most steam produced in a watertube boiler?

    <p>In the tubes exposed to direct radiant heat of the furnace (C)</p> Signup and view all the answers

    What is the purpose of the internal feedwater pipe in a steam drum?

    <p>To raise the feedwater temperature to near the boiler saturation temperature (D)</p> Signup and view all the answers

    At what pressure does natural circulation become inadequate in a watertube boiler?

    <p>12.5 MPa (C)</p> Signup and view all the answers

    What is the purpose of the continuous blowdown pipe in a steam boiler?

    <p>To maintain proper dissolved solids levels (D)</p> Signup and view all the answers

    What determines the sophistication of the steam separating equipment required in a boiler?

    <p>The degree of dryness required (D)</p> Signup and view all the answers

    What is the main difference between the fluid in the downcomers and the fluid in the risers?

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

    What is the purpose of the chemical feed pipe in a steam boiler?

    <p>To introduce chemicals to the boiler to prevent scale formation and corrosion (C)</p> Signup and view all the answers

    Why do internal feedwater pipes discharge close to the downcomers?

    <p>To promote proper water circulation (D)</p> Signup and view all the answers

    What is the term for the condition that can occur when high concentrations of dissolved solids are present in a boiler?

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

    What is the purpose of the steam drum in a watertube boiler?

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

    What is the main difference between watertube boilers and firetube boilers in terms of the location of water and heat?

    <p>Watertube boilers have water on the inside of the tubes and heat on the outside, while firetube boilers have heat on the inside and water on the outside. (B)</p> Signup and view all the answers

    What is one of the advantages of watertube boilers over firetube boilers?

    <p>They can be brought to operating pressure and temperature quicker. (A)</p> Signup and view all the answers

    What is a disadvantage of watertube boilers compared to firetube boilers?

    <p>They have less water content and therefore must be tuned to respond quickly to changes in steam pressure. (D)</p> Signup and view all the answers

    What is the primary purpose of the bent tube design in watertube boilers?

    <p>To allow optimal placement of superheaters, reheaters, and other heat transfer components. (A)</p> Signup and view all the answers

    What is the purpose of the risers in a watertube boiler?

    <p>To transfer water or water/steam mixture between the steam drum and the mud drum. (C)</p> Signup and view all the answers

    What is the purpose of the downcomers in a watertube boiler?

    <p>To feed water to the furnace area. (A)</p> Signup and view all the answers

    Why do watertube boilers require higher quality water than firetube boilers?

    <p>Because they are more prone to corrosion and scaling. (B)</p> Signup and view all the answers

    What is the purpose of the water-cooled furnace in a watertube boiler?

    <p>To absorb more radiant heat from the fire. (B)</p> Signup and view all the answers

    What is the main difference between the boilers shown in Figures 1 and 2?

    <p>One is a packaged two-drum watertube boiler and the other is a once-through steam generator. (D)</p> Signup and view all the answers

    What is the result of the density difference between water and steam in a watertube boiler?

    <p>The denser water in the downcomers forces the less dense water/steam mixture upward through the risers. (A)</p> Signup and view all the answers

    What is the primary function of baffles in watertube boilers?

    <p>To separate the water in the steam drum from the two-phase steam/water mixture (D)</p> Signup and view all the answers

    What is the main difference between firetube and watertube boilers in terms of steam separation?

    <p>Firetube boilers have less need for steam separation equipment (D)</p> Signup and view all the answers

    How does a dry pipe separate steam from water?

    <p>By forcing the steam to make sharp turns (D)</p> Signup and view all the answers

    What is the purpose of a centrifugal (cyclone) separator?

    <p>To further dry the steam by separating water particles (B)</p> Signup and view all the answers

    What is the function of the chevron plates in a chevron dryer?

    <p>To force the steam to change direction and drop entrained water particles (B)</p> Signup and view all the answers

    What is the term 'setting' used to describe in modern boilers?

    <p>The walls that form the boiler and furnace enclosure (B)</p> Signup and view all the answers

    Why do firetube boilers have less need for steam separation equipment?

    <p>Because they have larger shells and more room in the steam space (C)</p> Signup and view all the answers

    What is the primary purpose of a steam separator?

    <p>To separate the steam from water (D)</p> Signup and view all the answers

    What is the advantage of using waterwalls in modern boilers?

    <p>They improve heat transfer, decrease heat loss, and reduce the need for insulation and refractory (B)</p> Signup and view all the answers

    Where are chevron dryers often situated in a boiler?

    <p>Directly below the steam outlet (B)</p> Signup and view all the answers

    What is the primary purpose of a watertube boiler furnace?

    <p>To produce a certain maximum amount of steam (B)</p> Signup and view all the answers

    What type of boilers are designed to accommodate single burners, multiple burners, fluidized beds, and stokers?

    <p>Watertube boilers (C)</p> Signup and view all the answers

    What is the purpose of refractory-lined tubes in fluidized bed boilers?

    <p>To withstand high temperatures (B)</p> Signup and view all the answers

    What is the function of the steam drum in a watertube boiler?

    <p>To separate water and steam (B)</p> Signup and view all the answers

    What type of construction is characteristic of watertube boiler furnaces?

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

    What is the purpose of the bent tubes in a watertube boiler?

    <p>To form a water-cooled furnace (D)</p> Signup and view all the answers

    What is the primary difference between A, D, and O-type boilers?

    <p>The shape of the tubes and drums (B)</p> Signup and view all the answers

    What is the function of the downcomers in a watertube boiler?

    <p>To return water to the mud drum (C)</p> Signup and view all the answers

    Why is the back wall of a D-type boiler often protected by refractory?

    <p>To protect it from radiant and convection heat (D)</p> Signup and view all the answers

    What is the purpose of the castable refractory lining the furnace floor in a watertube boiler?

    <p>To shield the mud drum from radiant heat (A)</p> Signup and view all the answers

    What is the purpose of the induced draft (ID) fan in an air heater?

    <p>To draw out the cooler flue gases (D)</p> Signup and view all the answers

    What is the characteristic of a natural circulation steam generating unit?

    <p>It uses only natural convection currents to circulate the boiler water (A)</p> Signup and view all the answers

    At what pressure is there no difference in density between steam and water?

    <p>22 090 kPa (A)</p> Signup and view all the answers

    What is the purpose of the air heater in the sub-critical, natural circulation power boiler?

    <p>To heat the air (C)</p> Signup and view all the answers

    What is the characteristic of a radiant steam generating unit?

    <p>It has a steam drum but no boiler bank (D)</p> Signup and view all the answers

    What is the purpose of the external downcomer in the sub-critical, natural circulation power boiler?

    <p>To enhance positive water circulation (A)</p> Signup and view all the answers

    What is the primary function of a steam generating unit?

    <p>To produce high-pressure, high-temperature steam (C)</p> Signup and view all the answers

    What is the purpose of the boiler section in a steam generating unit?

    <p>To extract heat from flue gas and transfer it to water (D)</p> Signup and view all the answers

    What is the main producer of steam in a steam generating unit?

    <p>Water walls (A)</p> Signup and view all the answers

    What is the purpose of superheaters in a steam generating unit?

    <p>To increase the temperature of steam above its saturation temperature (D)</p> Signup and view all the answers

    What is the primary function of the reheater in a steam generating unit?

    <p>To reheat the steam after it has performed work in the turbine (A)</p> Signup and view all the answers

    What is the purpose of reheaters in a steam generating unit?

    <p>To reheat exhaust steam from the high or medium-pressure turbine stages (B)</p> Signup and view all the answers

    What is the result of steam passing through turbine stages?

    <p>The pressure and temperature of steam decrease (A)</p> Signup and view all the answers

    What type of heat exchanger is a regenerative air heater?

    <p>Rotating wheel with corrugated metal plates (D)</p> Signup and view all the answers

    What is the direction of fluid flow in the steam generating unit compared to the direction of flue gas flow?

    <p>The opposite direction (B)</p> Signup and view all the answers

    What is the purpose of the economizer in a steam generating unit?

    <p>To preheat the feedwater before it enters the boiler (C)</p> Signup and view all the answers

    What is the benefit of using superheated steam in a steam generating unit?

    <p>It increases the amount of energy that can be extracted from each kilogram of steam (A)</p> Signup and view all the answers

    What is the purpose of the economizer in a steam generating unit?

    <p>To transfer heat from the flue gas to the feedwater (D)</p> Signup and view all the answers

    What is the benefit of using an air heater in a steam generating unit?

    <p>It improves the combustion efficiency of the fuel (D)</p> Signup and view all the answers

    What is the purpose of the air heater in a steam generating unit?

    <p>To extract heat from flue gas and transfer it to air (C)</p> Signup and view all the answers

    What is the order of heat transfer components in the flue gas flow?

    <p>Radiant superheater, convection superheater, reheater, economizer (A)</p> Signup and view all the answers

    What is the primary difference between a boiler and a steam generating unit?

    <p>A boiler is a single heat exchanger, while a steam generating unit consists of multiple heat exchangers (B)</p> Signup and view all the answers

    What type of heat exchanger is a recuperative air heater?

    <p>Simple shell-and-tube heat exchanger (A)</p> Signup and view all the answers

    What is the purpose of the steam drum in a steam generating unit?

    <p>To separate the steam from the water (D)</p> Signup and view all the answers

    What is the direction of the flue gas flow in the steam generating unit?

    <p>From the furnace to the stack (B)</p> Signup and view all the answers

    What is the benefit of the cross-counter flow design of the heat transfer components?

    <p>It improves the efficiency of the heat transfer process (C)</p> Signup and view all the answers

    What is the primary reason why early watertube boilers were less efficient than modern ones?

    <p>Straight tubes restricted heat transfer surface (D)</p> Signup and view all the answers

    What is the significance of bent tube technology in modern watertube boilers?

    <p>It permitted boilers to increase in size (B)</p> Signup and view all the answers

    What is the result of advances in water treatment technology in watertube boiler design?

    <p>Reduced need for refractory brickwork (B)</p> Signup and view all the answers

    What is the role of combustion gases in watertube boilers?

    <p>They transfer heat to the boiler water (B)</p> Signup and view all the answers

    What is the significance of codes in the development of watertube boilers?

    <p>They standardized design calculations and construction methods (C)</p> Signup and view all the answers

    What is the result of the development of welding methods in watertube boiler construction?

    <p>Stronger boilers (A)</p> Signup and view all the answers

    What is a major consequence of watertube boilers having less water content compared to firetube boilers of the same steaming capacity?

    <p>They can be brought to operating pressure and temperature quicker. (B)</p> Signup and view all the answers

    What is the primary reason why natural circulation is not sufficient for high-pressure boilers?

    <p>The density of steam and water becomes too similar (B)</p> Signup and view all the answers

    What is the primary reason why watertube boilers are more complex to design and construct than firetube boilers?

    <p>They need to accommodate higher steam pressures and temperatures. (B)</p> Signup and view all the answers

    What is the primary purpose of the bent tubes in watertube boilers?

    <p>To allow for optimal placement of superheaters and reheaters. (C)</p> Signup and view all the answers

    What is the purpose of the internal feedwater pipe in a steam drum?

    <p>To raise the feedwater temperature to near the boiler saturation temperature (D)</p> Signup and view all the answers

    Why are watertube boilers used in the oil and gas industry, pulp and paper industry, and electric power industry?

    <p>They can accommodate extremely high pressures and temperatures. (A)</p> Signup and view all the answers

    Why are steam separating equipment and chemical feed piping often located near each other in a steam drum?

    <p>To allow the chemicals to mix with the feedwater and circulate throughout the boiler (C)</p> Signup and view all the answers

    What is the primary function of baffles in watertube boilers?

    <p>To direct cooler inlet water to the downcomers (B)</p> Signup and view all the answers

    What is the primary reason why watertube boilers require higher quality water than firetube boilers?

    <p>They operate at higher temperatures and pressures. (B)</p> Signup and view all the answers

    What is the primary function of the continuous blowdown pipe in a steam boiler?

    <p>To remove dissolved solids from the boiler water (B)</p> Signup and view all the answers

    What is the primary benefit of watertube boilers having better water circulation compared to firetube boilers?

    <p>They can respond more quickly to changes in steam pressure. (C)</p> Signup and view all the answers

    Why do watertube boilers typically have a higher heat transfer rate than firetube boilers?

    <p>Because radiant heat transfer occurs at a greater rate than convective heat transfer (C)</p> Signup and view all the answers

    What is the purpose of the dry pipe in steam separation?

    <p>To separate the water from the steam by making sharp turns (C)</p> Signup and view all the answers

    What is the term for the condition that can occur when high concentrations of dissolved solids are present in a boiler?

    <p>Foaming (D)</p> Signup and view all the answers

    What is the primary purpose of the risers in a watertube boiler?

    <p>To allow for the circulation of steam and water between the drums. (C)</p> Signup and view all the answers

    What type of separators are used in larger plants to further dry the steam?

    <p>Cyclone separators (C)</p> Signup and view all the answers

    What is the primary disadvantage of watertube boilers compared to firetube boilers in terms of maintenance and repair?

    <p>They are more difficult to repair and maintain. (A)</p> Signup and view all the answers

    What is the primary purpose of the risers in a watertube boiler?

    <p>To produce steam in the boiler (C)</p> Signup and view all the answers

    What is the purpose of the chevron plates in a chevron dryer?

    <p>To force the steam to rapidly change direction (C)</p> Signup and view all the answers

    What is the term used to describe the walls that form the boiler and furnace enclosure?

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

    Why do steam drums and mud drums have internal mechanisms such as feedwater, blowdown, and chemical feed piping?

    <p>To facilitate proper circulation and removal of dissolved solids (D)</p> Signup and view all the answers

    What is the primary reason why watertube boilers are more flexible in design than firetube boilers?

    <p>They have a more modular design. (D)</p> Signup and view all the answers

    What is the advantage of using waterwalls in modern boilers?

    <p>They improve heat transfer and reduce heat loss (B)</p> Signup and view all the answers

    What is the primary consequence of the density difference between water and steam in a watertube boiler?

    <p>It forces the less dense water/steam mixture upward through the risers. (B)</p> Signup and view all the answers

    What is the primary advantage of using internal feedwater piping in a steam boiler?

    <p>It prevents thermal shock and promotes proper water circulation (A)</p> Signup and view all the answers

    What is the purpose of the centrifugal force in a cyclone separator?

    <p>To fling water and entrained water particles to the outside of the separator (C)</p> Signup and view all the answers

    What is the primary function of the steam separating equipment in a steam drum?

    <p>To separate the steam from the steam/water mixture (A)</p> Signup and view all the answers

    What is the characteristic of the steam generated in larger plants?

    <p>It is dry and contains very little water (A)</p> Signup and view all the answers

    What is the purpose of the rectangular opening in a cyclone separator?

    <p>To allow water and steam to enter the separator (B)</p> Signup and view all the answers

    What is the result of the water and entrained water particles impinging on the surfaces of the chevron plates?

    <p>They drop back to the boiler water (A)</p> Signup and view all the answers

    What is the primary reason for the design of watertube boiler furnaces to accommodate single burners, multiple burners, fluidized beds, and stokers?

    <p>To accommodate different fuel types and combustion setups (B)</p> Signup and view all the answers

    What is the purpose of the water-cooled furnace in a watertube boiler?

    <p>To protect the mud drum from radiant heat (C)</p> Signup and view all the answers

    Why do watertube boilers need larger furnaces to accommodate the combustion air requirements?

    <p>To ensure the velocity of the combustion products is not so great that combustion continues outside of the furnace (A)</p> Signup and view all the answers

    What is the primary difference between A, D, and O-type boilers?

    <p>The shape of the tubes and drums (D)</p> Signup and view all the answers

    What is the purpose of the castable refractory lining the furnace floor in a watertube boiler?

    <p>To protect the mud drum from radiant heat (B)</p> Signup and view all the answers

    What is the primary function of the steam generating unit's auxiliary equipment?

    <p>To handle fuel, draft, and ash removal (A)</p> Signup and view all the answers

    What is the characteristic of a watertube boiler furnace?

    <p>It is internally fired (B)</p> Signup and view all the answers

    Why do fluidized bed boilers need very tall furnaces and refractory-lined tubes?

    <p>To accommodate the specific combustion requirements of fluidized bed boilers (C)</p> Signup and view all the answers

    What is the purpose of the boiler section in a steam generating unit?

    <p>To convert water to steam (D)</p> Signup and view all the answers

    What is the primary reason for the design of watertube boilers to produce a certain maximum amount of steam?

    <p>To ensure the furnace has adequate volume to burn the amount of fuel needed to produce the steam (A)</p> Signup and view all the answers

    What is the primary difference between a primary and secondary superheater?

    <p>The order in which they receive steam from the steam drum (C)</p> Signup and view all the answers

    What is the result of the density difference between water and steam in a steam generating unit?

    <p>Natural circulation becomes inadequate (D)</p> Signup and view all the answers

    What is the purpose of the bent tube design in watertube boilers?

    <p>To accommodate the burners that penetrate the waterwall (C)</p> Signup and view all the answers

    What is the primary advantage of watertube boilers over firetube boilers?

    <p>They offer more design flexibility (C)</p> Signup and view all the answers

    What is the primary purpose of the reheater in a steam generating unit?

    <p>To minimize the chance of condensation in the low-pressure turbine (D)</p> Signup and view all the answers

    What is the characteristic of a steam generating unit with a reheater?

    <p>It reduces the chance of condensation in the low-pressure turbine (D)</p> Signup and view all the answers

    What is the primary reason why heat leaving through a chimney represents a loss in efficiency?

    <p>It is wasteful of fuel and money (D)</p> Signup and view all the answers

    What is the purpose of the economizer in a steam generating unit?

    <p>To extract heat from the flue gases (A)</p> Signup and view all the answers

    What is the primary benefit of using superheated steam in a steam generating unit?

    <p>It increases the overall plant efficiency (C)</p> Signup and view all the answers

    What is the primary function of the air heater in a steam generating unit?

    <p>To transfer heat to the air (C)</p> Signup and view all the answers

    What is the primary purpose of the air heater in Figure 14?

    <p>To heat the air for combustion (B)</p> Signup and view all the answers

    What is the characteristic of a sub-critical steam generating unit?

    <p>It operates at pressures below the critical pressure of water and steam (A)</p> Signup and view all the answers

    What is the purpose of the external downcomer in Figure 14?

    <p>To completely shield the downcomer from the heat of combustion (B)</p> Signup and view all the answers

    What is the difference between a natural circulation and a forced circulation steam generating unit?

    <p>The method of circulating boiler water (C)</p> Signup and view all the answers

    At what pressure is there no difference in density between steam and water?

    <p>22 090 kPa (C)</p> Signup and view all the answers

    What is the purpose of the induced draft (ID) fan in the air heater?

    <p>To discharge the flue gases up the chimney (C)</p> Signup and view all the answers

    What is the primary reason for the placement of the economizer inlet at the location where the flue gas is the coolest?

    <p>To reduce the thermal shock of relatively cool water entering the hot steam drum (C)</p> Signup and view all the answers

    What is the primary difference between the flow of water/steam and the flow of flue gases in the heat transfer components?

    <p>The flow of one is always counter to the flow of the other (C)</p> Signup and view all the answers

    What is the primary function of the wheel in a regenerative air heater?

    <p>To transfer heat from the flue gas to the combustion air (D)</p> Signup and view all the answers

    What is the primary benefit of preheating the combustion air in the air heater?

    <p>It improves the combustion efficiency and assists in the burning of most fuels (D)</p> Signup and view all the answers

    What is the primary purpose of the radiant superheater and the reheater in the steam generating unit?

    <p>To heat the steam to a higher temperature (C)</p> Signup and view all the answers

    What is the primary direction of fluid flow in the steam generating unit compared to the direction of flue gas flow?

    <p>Opposite direction (D)</p> Signup and view all the answers

    What is the primary function of the cross-counter flow design in the heat transfer components?

    <p>To maximize the heat transfer between the fluids (A)</p> Signup and view all the answers

    What is the primary purpose of the windbox in the steam generating unit?

    <p>To mix the combustion air with the fuel (A)</p> Signup and view all the answers

    What is the primary reason for the placement of the superheaters in the steam generating unit?

    <p>To heat the steam to a higher temperature after it leaves the steam drum (C)</p> Signup and view all the answers

    What is the primary function of the forced draft (FD) fan in the steam generating unit?

    <p>To draw in combustion air from the atmosphere (B)</p> Signup and view all the answers

    At what pressure is forced circulation required for boilers?

    <p>20 MPa (B)</p> Signup and view all the answers

    What is the characteristic of a supercritical steam generating unit?

    <p>It does not have steam or mud drums (D)</p> Signup and view all the answers

    What is the flow of feedwater in a supercritical steam generating unit?

    <p>It flows through the economizer, waterwall section, convection superheater, and radiant superheater (A)</p> Signup and view all the answers

    What is the term for the pressure at which the density of water and steam is equal?

    <p>Critical pressure (C)</p> Signup and view all the answers

    What is the characteristic of an once-through steam generator (OTSG)?

    <p>It does not have a steam drum and uses forced circulation (A)</p> Signup and view all the answers

    What is the advantage of using forced circulation in boilers above 12.5 MPa?

    <p>It is advantageous for efficiency or design reasons (C)</p> Signup and view all the answers

    What is the characteristic of steam produced in an OTSG?

    <p>Wet and low-pressure (A)</p> Signup and view all the answers

    What is the primary function of the in-bed tubes in an FBC steam generator?

    <p>To absorb radiant heat and heat conducted directly from the bed particles (B)</p> Signup and view all the answers

    What is the advantage of FBC steam generating units in terms of emissions?

    <p>Lower furnace temperatures reduce NOX production (C)</p> Signup and view all the answers

    What is the purpose of the fluidizing air nozzles in an FBC boiler?

    <p>To provide combustion air to the bed (A)</p> Signup and view all the answers

    What is the characteristic of a circulating fluidized bed boiler?

    <p>The flue gas carries burning fuel through the boiler to the dust collector (B)</p> Signup and view all the answers

    What is the primary advantage of OTSGs over natural circulation boilers?

    <p>No internal recirculation (B)</p> Signup and view all the answers

    What is the purpose of the refractory in an FBC boiler?

    <p>To protect the boiler walls from heat (A)</p> Signup and view all the answers

    What is the primary reason for the use of FBC steam generating units?

    <p>Suitability for a wide range of fuels (A)</p> Signup and view all the answers

    What is the characteristic of the burning bed in an FBC steam generator?

    <p>It behaves like a suspended fluid (D)</p> Signup and view all the answers

    What is the purpose of the limestone in an FBC steam generator?

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

    What is the minimum pressure above which forced circulation is required in boilers?

    <p>20 MPa (D)</p> Signup and view all the answers

    What is the characteristic of a supercritical steam generating unit?

    <p>It does not have steam or mud drums (C)</p> Signup and view all the answers

    In a supercritical steam generating unit, where does the feedwater flow from?

    <p>Economizer to the waterwall section (C)</p> Signup and view all the answers

    What is the term used to describe the pressure at which the density of water and steam is equal?

    <p>Critical pressure (B)</p> Signup and view all the answers

    What is the advantage of using forced circulation in boilers above 12.5 MPa?

    <p>Increased efficiency (B)</p> Signup and view all the answers

    What type of steam generator is a supercritical steam generating unit?

    <p>Once-through steam generator (OTSG) (A)</p> Signup and view all the answers

    What is the primary advantage of the bubbling bed FBC boiler over the circulating fluidized bed boiler?

    <p>Easier control of combustion at low firing rates (B)</p> Signup and view all the answers

    What is the primary reason why OTSGs do not require steam drums?

    <p>The entire mass of water entering is turned to steam (C)</p> Signup and view all the answers

    What is the primary function of the in-bed tubes in an FBC steam generator?

    <p>To absorb radiant heat from the burning bed (C)</p> Signup and view all the answers

    What is the primary advantage of fluidized bed combustion steam generators over other steam generating units?

    <p>Suitability for a wide range of fuels (A)</p> Signup and view all the answers

    What is the primary purpose of the refractory in an FBC boiler?

    <p>To protect the boiler from the high temperatures of the burning bed (A)</p> Signup and view all the answers

    What is the primary characteristic of the burning bed in an FBC steam generator?

    <p>It behaves like a suspended fluid (C)</p> Signup and view all the answers

    What is the primary benefit of the wet steam produced by an OTSG?

    <p>It carries dissolved solids and feedwater impurities away from the boiler (C)</p> Signup and view all the answers

    What is the primary purpose of the limestone added directly to the bed in an FBC steam generator?

    <p>To reduce SOX emissions (C)</p> Signup and view all the answers

    What is the primary difference between a bubbling bed FBC boiler and a circulating fluidized bed boiler?

    <p>The way the burning bed is maintained (B)</p> Signup and view all the answers

    What is the primary benefit of the high recirculation rate in natural circulation boilers?

    <p>It improves the steam quality (B)</p> Signup and view all the answers

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