Question 1

Boiler mountings — device on the steam chest to prevent overpressure damage Name the device fitted to the steam chest whose purpose is to prevent explosions by automatically releasing steam when internal pressure exceeds a safe limit.

Accepted Answer

Introduction / Context:Boiler mountings are essential for safe operation. Among them, one device is specifically tasked with limiting pressure to avoid catastrophic failure by venting steam when pressure becomes excessive.Given Data / Assumptions:Steam chest connected to the boiler drum or shell.Standard spring-loaded or deadweight valve calibrated to a set pressure.Regular testing and sealing per regulations.Concept / Approach:A safety valve automatically opens when pressure exceeds the set value and recloses after pressure falls below a reseat point. It is distinct from indicating devices (pressure gauge, water level indicator) and from low-water protection (fusible plug) or maintenance fittings (blow-off cock).Step-by-Step Solution:Identify the hazard: excessive internal pressure.Match the function: automatic pressure relief.Select the correct device: safety valve.Verification / Alternative check:Boiler codes mandate safety valves as primary overpressure protection and specify relieving capacity sized to firing rate.Why Other Options Are Wrong:Water level indicator: indicates level; does not relieve pressure.Pressure gauge: measures pressure; does not control it.Fusible plug: protects against low water by melting; not overpressure relief.Blow-off cock: drains sludge/water; not automatic relief.Common Pitfalls:Confusing the fusible plug’s low-water function with overpressure protection; neglecting periodic testing of safety valves.Final Answer:safety valve

Question 2

Boiler types — applicability of the high-steam & low-water safety valve The combined high-steam and low-water safety valve is not used on which of the following boilers?

Accepted Answer

Introduction / Context:The high-steam and low-water safety valve is a combined device that both relieves overpressure and provides protection if water level becomes dangerously low. Its use depends on boiler construction and service. This question targets where it is generally not employed.Given Data / Assumptions:Cornish and Lancashire are stationary, internally fired, fire-tube boilers with ample shell water space.Cochran is a vertical, fire-tube boiler commonly fitted with simple safety valves.Locomotive boilers have distinct arrangements and operating dynamics (high vibration, varying water levels, separate low-water protection like fusible plugs).Concept / Approach:Locomotive boilers typically use spring-loaded safety valves for overpressure and fusible plugs for low-water protection, rather than the combined high-steam & low-water safety valve used on certain stationary shell boilers. Hence, the combined type is generally not applied to locomotive boilers.Step-by-Step Solution:Identify the combined valve's typical application: stationary shell boilers (e.g., Lancashire).Note locomotive practice: separate safety valves and fusible plugs; different mounting constraints.Conclude “Locomotive boiler” is the correct exclusion.Verification / Alternative check:Standard boiler texts list the combined valve with Cornish and Lancashire; locomotive sections emphasize Ramsbottom or Pop safety valves plus fusible plugs.Why Other Options Are Wrong:Cochran, Cornish, Lancashire: classic stationary types that may use the combined valve.Generic vertical fire-tube: context-dependent; many use simple safety valves but the question’s conventional exclusion remains the locomotive boiler.Common Pitfalls:Assuming one style of safety device suits all boilers; ignoring the specialized locomotive operating environment.Final Answer:Locomotive boiler

Question 3

Boiler protection on dangerously low water level — identify the device Name the device used to automatically extinguish the furnace fire when water level in the boiler falls to an unsafe limit.

Accepted Answer

Introduction / Context:Low-water conditions are among the most serious boiler hazards. A dedicated device exists to protect the furnace and heating surfaces when water level drops below a safe value, preventing metal overheating and potential failure.Given Data / Assumptions:Standard shell or fire-tube boiler with a furnace crown exposed to flame.Water level monitoring and safety devices installed.Concept / Approach:The correct device is the fusible plug, which melts at a predetermined temperature when it is no longer covered by water, releasing steam/water into the furnace to quench the fire and alert operators. Since “fusible plug” is not listed among the options provided, the correct selection here is “none of these.”Step-by-Step Solution:Identify the hazard: low water causes furnace plate overheating.Match the protective device: fusible plug (missing from the list).Therefore, among given choices, select “none of these.”Verification / Alternative check:Boiler mountings list includes: safety valve, stop valve, water-level gauge, pressure gauge, blow-off cock, and fusible plug—the last of which handles low-water hazards.Why Other Options Are Wrong:Blow-off cock: drains sludge/water, not automatic fire extinction.Stop valve: isolates steam line.Superheater/economiser: heat exchangers; no protective role for low water.Common Pitfalls:Confusing blow-off cock with an emergency dump; believing the safety valve responds to low water—it does not.Final Answer:none of these

Question 4

Engine performance terms — power developed inside the cylinder What do we call the power actually generated by the working fluid on the piston within the engine cylinder (as obtained from the indicator diagram)?

Accepted Answer

Introduction / Context:Different power measures are used for engines: indicated, brake, and frictional power. Knowing their meanings is necessary for testing, design, and performance evaluation.Given Data / Assumptions:Mechanically measured indicator diagram (pressure–volume) or its modern equivalent.Steady-state operation at the test point.Concept / Approach:Indicated power (IP): power developed by the gas on the piston, computed from the indicated mean effective pressure (IMEP), cylinder dimensions, and speed.Brake power (BP): power available at the crankshaft as measured by a dynamometer.Frictional power (FP): the difference, FP = IP − BP, representing mechanical losses.Thus, the power asked for—the power actually generated in the cylinder—is the indicated power.Step-by-Step Solution:Obtain IMEP from the indicator diagram.Compute IP = (IMEP * L * A * N * k) / time (using consistent units).Recognize that IP precedes mechanical losses; BP is after losses.Verification / Alternative check:In tests, BP is always less than IP; their difference trends with lubrication, speed, and load, confirming the definitions.Why Other Options Are Wrong:Brake power: shaft output after losses.Frictional power: a loss term, not generated power.None/rated power: do not match the precise definition.Common Pitfalls:Using brake-specific fuel consumption (bsfc) with IP by mistake; mixing IMEP with BMEP.Final Answer:indicated power

Question 5

Boiler performance definitions — check the statement Is the following statement correct? “The ratio of heat actually used in producing the steam to the heat liberated in the furnace is known as equivalent evaporation from and at 100°C.”

Accepted Answer

Introduction / Context:Boiler performance uses several related terms—boiler efficiency, evaporation ratio, equivalent evaporation, and factor of evaporation. Mislabeling these can lead to wrong interpretations of tests and guarantees. This question asks you to validate a specific definition.Given Data / Assumptions:Heat balance across the boiler is well defined.Reference condition “from and at 100°C” is understood for equivalent evaporation.Concept / Approach:The ratio of useful heat added to the water/steam to the heat released by fuel is boiler efficiency. Equivalent evaporation is a different concept: it is the amount of water that would be evaporated from and at 100°C per unit time corresponding to the same heat transfer actually achieved. Hence, the statement equating the efficiency ratio to equivalent evaporation is incorrect.Step-by-Step Solution:Write efficiency: η_b = Q_useful / Q_fuel.Define equivalent evaporation: m_eq = Q_useful / 2257 kJ/kg (approximately, using latent heat at 100°C) per unit time.Conclude: the given statement misnames the ratio; the correct term is “boiler efficiency.”Verification / Alternative check:Acceptance codes and textbooks consistently distinguish between η_b (dimensionless) and equivalent evaporation (kg/h or kg/s).Why Other Options Are Wrong:“Correct” and other qualified variants: conflate two distinct quantities—one is a ratio, the other is a standardized mass flow.Common Pitfalls:Using equivalent evaporation as a percentage; ignoring superheat/unevaporated sensible heating when converting to equivalent terms.Final Answer:Incorrect

Question 6

Cornish boiler — typical overall length range Select the most typical range for the length of a Cornish boiler used in industry.

Accepted Answer

Introduction / Context:Identifying realistic dimensional ranges helps distinguish classic shell boilers during design problems and site identification. The Cornish boiler, with a single internal furnace tube, has characteristic proportions different from the two-flue Lancashire boiler.Given Data / Assumptions:Traditional Cornish construction (single furnace flue inside a horizontal cylindrical shell).Industrial service at relatively modest pressures.Concept / Approach:Handbook values place Cornish boiler lengths roughly in the mid-single-digit metres up to about 7 or 8 m for common sizes, while Lancashire shells are often longer. Among the choices, 5 to 7.5 m matches conventional practice most closely.Step-by-Step Solution:Compare with Lancashire: typically longer and larger diameter.Eliminate too-short ranges (2–4.5 m) for industrial outputs.Select 5–7.5 m as the representative span.Verification / Alternative check:Old design tables and museum specifications show Cornish boilers commonly around 5–7 m long for moderate duties.Why Other Options Are Wrong:2–4.5 m or 3–5 m: undersized for standard installations.7–9 m: more typical of larger Lancashire units.9–12 m: uncommon for the classic Cornish form.Common Pitfalls:Confusing Cornish with Lancashire proportions; forgetting space for reversal chambers and brick settings.Final Answer:5 to 7.5 m

Question 7

Feedwater heat-recovery placement — where is the economiser located? In a conventional boiler flue-gas path, the economiser is generally installed between which two components?

Accepted Answer

Introduction / Context:An economiser recovers sensible heat from flue gases to raise feedwater temperature before it enters the boiler drum or economiser outlet header. Knowing its position in the gas path helps understand temperature profiles and heat-exchanger duty allocation.Given Data / Assumptions:Typical arrangement from furnace outlet: superheater/reheater → economiser → air preheater → chimney.Counterflow or mixed-flow heat exchange is assumed.Concept / Approach:The economiser must see sufficiently hot gas to be effective, but not so hot as to cause feedwater boiling or excessive metal temperatures—hence it is placed downstream of the superheater/reheater and upstream of the air preheater. The air preheater uses the remaining gas heat to warm combustion air before discharge to the stack.Step-by-Step Solution:Lay out the conventional sequence of gas-side components.Place the economiser between the last steam-side superheating stage and the air preheater.Confirm that this yields appropriate gas exit temperatures and feedwater rise.Verification / Alternative check:Plant heat balance diagrams consistently show this order; deviations are special cases (e.g., regenerative or condensing air heaters, or split-stream arrangements).Why Other Options Are Wrong:Between ID and FD fans: these are on different sides of the system; not a heat-exchanger placement.Air preheater and chimney: would underutilize gas heat for feedwater and overcool gases before air preheat.None/furnace–soot blower: not meaningful placements for the economiser unit.Common Pitfalls:Confusing economiser with air preheater roles; ignoring dew-point corrosion if gases are cooled too low after air preheater.Final Answer:last superheater or reheater and the air preheater

Question 8

Boiler performance terminology — choose the correct definition Is the following statement correct? “The amount of water evaporated from and at 100°C into dry saturated steam is called the evaporative capacity of a boiler.”

Accepted Answer

Introduction / Context:In boiler testing and performance comparison, two closely related terms are frequently confused: “evaporative capacity” and “equivalent evaporation from and at 100°C.” The wording in the prompt deliberately mixes them. This question checks whether you can distinguish the everyday capacity rating (actual kg/h produced under given conditions) from the standardized reference basis used for fair comparisons across different operating pressures and feedwater temperatures.Given Data / Assumptions:“From and at 100°C” refers to water at 100°C being converted to dry saturated steam at 100°C (atmospheric pressure).Evaporative capacity refers to the actual mass of steam generated per hour under the boiler’s working conditions.Standard practice uses a conversion via the factor of evaporation to express results on the “from and at 100°C” basis.Concept / Approach:Equivalent evaporation (EE) is a normalization concept. It answers: “If the same amount of heat that the boiler actually delivered were applied at the 100°C reference, how many kilograms would be evaporated per hour?” The evaporative capacity, by contrast, is the real, on-site steam production (kg/h) at the actual pressure, temperature, and feedwater conditions. Therefore, saying “from and at 100°C” defines equivalent evaporation, not evaporative capacity.Step-by-Step Solution:Define EE: EE = (actual enthalpy rise per kg) / (latent heat at 100°C).Define capacity: Capacity = actual steam flow rate (kg/h) delivered by the boiler.Compare definitions: “from and at 100°C” belongs to EE, not capacity.Hence, the statement is incorrect.Verification / Alternative check:In boiler trials, measured feedwater flow is multiplied by the factor of evaporation to convert to equivalent evaporation. Nameplates often quote both actual capacity (kg/h) and equivalent evaporation for marketing comparability.Why Other Options Are Wrong:Yes/conditional answers confuse the standardized basis with real operating output.Dependence on feedwater temperature is handled via the factor of evaporation, not by redefining capacity.Common Pitfalls:Assuming “from and at 100°C” is a generic phrase for any boiler output. It is strictly the reference-basis term equivalent evaporation.Final Answer:No

Question 9

Steam engine components — primary function of the piston Which statement best describes the main function of the piston in a reciprocating steam engine (with piston rod, crosshead, and slide valve)?

Accepted Answer

Introduction / Context:A classical steam engine converts the thermal/pressure energy of steam into mechanical work by means of a piston–cylinder arrangement, a valve gear, and a crank mechanism. Each part has a distinct function; mixing them up leads to diagnostic and design errors. This question focuses on the piston’s true role in the system.Given Data / Assumptions:Cylinder receives steam alternately on either side of the piston.Piston is connected to the crosshead via a piston rod; the crosshead runs in guides.Valve gear (e.g., D-slide valve) controls admission, cut-off, release, and compression events.Concept / Approach:Pressure acting on the piston face produces a force. With constrained motion, the piston translates linearly; via the rod, crosshead, and connecting rod, this becomes rotary motion at the crank. The essence is energy conversion from steam to mechanical work at the piston face; other components transmit or control this motion but do not perform the conversion itself.Step-by-Step Solution:Steam pressure p acts over piston area A → force F = p * A.Linear motion does work W = ∫ F dx during the stroke.This work is transmitted through the piston rod to the crosshead and then to the crank.Therefore, the piston’s primary function is converting steam energy to reciprocating mechanical work.Verification / Alternative check:Indicator diagrams quantify work as the area enclosed by the p–V loop; that work is physically produced at the piston face as it traverses the stroke.Why Other Options Are Wrong:Guiding and preventing rod bending is the job of crosshead guides.Motion transfer is primarily by the piston rod; it is not the piston’s defining function.Admitting/exhausting steam belongs to the valve gear, not the piston.Automatic lubrication is not a piston function.Common Pitfalls:Attributing the valve’s timing duties to the piston or assuming the crosshead’s guiding role belongs to the piston itself.Final Answer:To convert steam pressure/heat energy into reciprocating mechanical work transmitted through the rod

Question 10

Economiser benefit — is a 15–20% coal saving claim reasonable? Evaluate the statement: “There is about 15 to 20% saving of coal when an economiser is fitted in the boiler flue-gas path.”

Accepted Answer

Introduction / Context:An economiser is a feedwater heater that recovers sensible heat from hot flue gases. By preheating feedwater, the boiler needs less fuel to raise the water to saturation and, if applicable, to superheat it. Many textbook problems summarize the benefit as “on the order of 10–20% fuel saving,” depending on site conditions. This item asks you to judge whether a 15–20% saving is plausible.Given Data / Assumptions:Flue gases exit the boiler at a temperature high enough to transfer additional heat to feedwater.Feedwater enters below saturation temperature (common in practice).Economiser effectiveness is reasonable (not extremely fouled or bypassed).Concept / Approach:Fuel saving arises because the enthalpy rise required in the evaporator and superheater is reduced by the economiser’s contribution. The percentage saving depends on stack temperature, feedwater inlet temperature, flow rate, and excess air. In many standard references and solved examples, savings of roughly 10–20% are cited for well-designed retrofits, making the 15–20% figure a reasonable rule-of-thumb for exam purposes.Step-by-Step Solution:Let Q_in be fuel heat input and Q_useful the heat delivered to water/steam.With an economiser, a portion Q_econ is recovered from flue gases.Fuel saving ≈ Q_econ / Q_in_baseline, often falling in the mid-teens percent for practical cases.Hence, “about 15–20%” is acceptable as a rounded estimate.Verification / Alternative check:Heat-balance worksheets show significant drop in stack loss and fuel rate after raising feedwater, supporting mid-teens percent improvement when the baseline had high stack temperatures and cool feedwater.Why Other Options Are Wrong:“False” denies widely documented savings in appropriate conditions.Other qualifiers (superheat, draught, deaeration) are not prerequisites, though they may influence magnitude.Common Pitfalls:Expecting exactly 15–20% in every plant. Real savings vary (often 8–18%); the question accepts the typical textbook range.Final Answer:True

Question 11

Condenser terminology — definition of vacuum State whether the following is correct: “The condenser vacuum is the difference between atmospheric pressure and the absolute pressure in the condenser.”

Accepted Answer

Introduction / Context:Vacuum readings in steam surface or jet condensers quantify how far below atmospheric the condenser absolute pressure has been reduced. Correct interpretation of vacuum is essential for diagnosing condenser performance and turbine/engine back-pressure losses.Given Data / Assumptions:Atmospheric pressure p_atm is the local barometric pressure.Condenser absolute pressure p_abs is the sum of partial pressures of steam and non-condensable gases.Vacuum gauges are typically calibrated in “centimetres or millimetres of mercury” or “bar/kPa below atmosphere.”Concept / Approach:By definition, condenser vacuum V is the difference between local atmospheric pressure and the absolute pressure existing in the condenser space: V = p_atm − p_abs. This expresses how much of the atmospheric pressure has been “removed.” A higher vacuum (larger difference) means a lower absolute back pressure on the exhaust side, improving cycle efficiency.Step-by-Step Solution:Write the relationship: V = p_atm − p_abs.Recognize that p_abs includes steam and air partial pressures.Hence the statement as given is correct.Verification / Alternative check:Indicator diagrams for condensing engines show the back-pressure line below the atmospheric line by an amount corresponding to the indicated vacuum.Why Other Options Are Wrong:Disagree and conditional variants conflict with the standard definition.“Gauge minus absolute” is not a meaningful expression for vacuum.Common Pitfalls:Forgetting that p_atm varies with weather and altitude; vacuum must always be referenced to local barometric pressure.Final Answer:Agree

Question 12

Indicator diagram factor — relation between actual and theoretical mean effective pressures Given pa = actual mean effective pressure, pm = theoretical mean effective pressure, and K = diagram factor, which relation is correct?

Accepted Answer

Introduction / Context:Real engine indicator diagrams deviate from the ideal theoretical diagrams due to throttling, wire-drawing, heat losses, and valve timing. The diagram factor K captures the ratio of the actual diagram area to the theoretical diagram area, and thus relates actual to theoretical mean effective pressure (MEP).Given Data / Assumptions:pm is computed from a theoretical cycle for the same boundary conditions.pa is obtained from the measured indicator diagram.Diagram factor K = actual area / theoretical area.Concept / Approach:Since MEP is proportional to the diagram area for a given cylinder, K scales the theoretical MEP to match reality. Therefore, actual MEP equals theoretical MEP multiplied by the diagram factor.Step-by-Step Solution:By definition: K = Area_actual / Area_theoretical.MEP ∝ diagram area (for fixed stroke and bore).Thus, pa = K * pm.Select the matching expression: pa = pm × K.Verification / Alternative check:Worked examples compute pm from an idealized cycle and then multiply by K (often 0.7–0.9) to obtain pa before calculating indicated power.Why Other Options Are Wrong:pa = pm/K inverts the effect, implying pa > pm for K Sum or ratio forms lack basis in the definition of K.Common Pitfalls:Treating K as an additive correction rather than a multiplicative factor derived from area ratios.Final Answer:pa = pm × K

Question 13

Surface condenser operation — do condensate and cooling water mix? Choose the correct statement regarding a surface condenser used with a steam engine or turbine.

Accepted Answer

Introduction / Context:Condensers remove latent heat from exhaust steam so it can be condensed to water, lowering the back pressure and increasing cycle efficiency. Two common types are surface condensers and jet (mixing) condensers. Knowing which type mixes the fluids determines whether condensate can be reused as boiler feed without extensive treatment.Given Data / Assumptions:Surface condenser uses a tube bundle and shell arrangement.Cooling water flows in tubes; steam condenses on the shell side (or vice versa in some designs).Condensate is recovered without contamination.Concept / Approach:In a surface condenser, steam and cooling water do not mix; heat transfer occurs across a solid tube wall. This preserves condensate purity for return to the boiler. In jet condensers, by contrast, steam and cooling water mix directly, producing a single water stream at an intermediate temperature that cannot be returned to the boiler without treatment.Step-by-Step Solution:Identify condenser type: “surface” implies a heat-exchange surface separates the fluids.Therefore, mixing does not occur; condensate remains separate.Answer: False — they are kept separate.Verification / Alternative check:Plant P&IDs show separate condensate extraction pumps and cooling-water circuits for surface condensers, confirming no mixing.Why Other Options Are Wrong:Statements claiming “True” describe jet condensers, not surface condensers.Common Pitfalls:Confusing the two condenser types or assuming “surface” simply means “exposed surface” rather than “separated by a heat-transfer surface.”Final Answer:False — they are kept separate across tube walls

Question 14

Boiler mountings — principal purpose of the steam stop valve What is the principal function of a boiler steam stop valve located at the outlet of the steam drum/shell?

Accepted Answer

Introduction / Context:Boiler mountings are mandatory devices required for safe operation. Among them, the steam stop valve provides positive isolation of the boiler from the steam header and allows controlled admission when starting up. Correctly identifying its purpose distinguishes it from other mountings and accessories.Given Data / Assumptions:Standard shell or water-tube boiler with a main steam outlet.Separate devices exist for blow-down, overheat protection (fusible plug), superheating, and condensers.Concept / Approach:The steam stop valve controls and isolates steam flow. During start-up, it is opened cautiously to warm the main; during shutdown or maintenance, it is closed to isolate the boiler. Other listed duties belong to different mountings or accessories and must not be confused with the stop valve’s role.Step-by-Step Solution:Map functions to devices: blow-off → blow-down valve; low-water fire protection → fusible plug; superheat → superheater; vacuum → condenser system.Stop valve’s function: control and isolation of steam flow.Therefore, option (a) is correct.Verification / Alternative check:Operating procedures specify cracking open the stop valve for line warming and closing it for isolation; both confirm its control/isolation role.Why Other Options Are Wrong:(b), (c), (d), and the extra condenser option describe other equipment, not the stop valve.Common Pitfalls:Calling any valve on the boiler a “stop valve.” Only the main outlet isolation and control valve is the steam stop valve.Final Answer:control the flow of steam from the boiler to the main pipe and to shut it off completely when required

Question 15

Condenser mixture of gases — computing total condenser pressure from partial pressures In a steam condenser, the partial pressures are: steam = 0.06 bar and air = 0.007 bar. What is the total condenser pressure?

Accepted Answer

Introduction / Context:Exhaust spaces in condensers often contain a mixture of saturated steam and non-condensable gases (air, dissolved gases released from feedwater). Understanding how partial pressures combine to determine the total back pressure is key to evaluating condenser performance and turbine/engine efficiency.Given Data / Assumptions:Steam partial pressure p_steam = 0.06 bar.Air partial pressure p_air = 0.007 bar.Ideal-gas behavior for the gas mixture; total pressure equals sum of partial pressures.Concept / Approach:Dalton’s law of partial pressures states that the total pressure of a mixture of non-reacting gases equals the sum of the partial pressures exerted by each component. In a condenser, saturated steam coexists with air; the absolute back pressure is the sum of their partial pressures. Lowering the air content (via effective air extraction) reduces the total back pressure and improves plant efficiency.Step-by-Step Solution:Write total pressure: p_total = p_steam + p_air.Insert values: p_total = 0.06 + 0.007.Compute: p_total = 0.067 bar.Therefore, the condenser pressure is 0.067 bar.Verification / Alternative check:At p_steam = 0.06 bar, the saturation temperature is around 36–37°C. The small additional air partial pressure raises total back pressure slightly, matching practical observations.Why Other Options Are Wrong:0.06 or 0.007 bar: each ignores the other constituent.0.053 bar: subtracts instead of adding.0.600 bar: off by an order of magnitude.Common Pitfalls:Confusing gauge with absolute pressure, or forgetting that even a small air partial pressure materially increases total back pressure.Final Answer:0.067 bar

Question 16

Steam plant components — identify the device A vessel into which exhaust steam from an engine or turbine is led and condensed to water for reuse is called a:

Accepted Answer

Introduction / Context:Accurate component naming in a steam plant is essential. The device that collects exhaust steam and turns it back into water under vacuum is not the boiler or preheater; it is the condenser. Correct identification helps in understanding the Rankine cycle and the roles of each item.Given Data / Assumptions:Exhaust steam leaves the prime mover at low pressure and enters a vessel.Inside, heat is removed, causing condensation.Condensate is recovered for boiler feed.Concept / Approach:A steam condenser maintains sub-atmospheric pressure by condensing steam and extracting non-condensables. This lowers back pressure and increases net work output. The boiler, economiser, preheater, and deaerator have different locations and purposes in the cycle.Step-by-Step Solution:Map function to component: condense steam → condenser.Other devices either generate steam (boiler) or preheat fluids (economiser for feedwater, preheater for air/steam) or remove dissolved gases (deaerator).Therefore, the correct choice is steam condenser.Verification / Alternative check:Rankine cycle diagrams place the condenser between the turbine/engine exhaust and the feedwater pump, consistent with the description.Why Other Options Are Wrong:Boiler: generates steam, not condense.Preheater/economiser: heat exchangers for steam/air or feedwater, but not for phase change of exhaust.Deaerator: strips dissolved gases; not the main condenser.Common Pitfalls:Using “preheater” loosely for any heat exchanger; each device has a specific duty in the plant.Final Answer:steam condenser

Question 17

Boiler feed line fitting — which valve is placed between the feed pump and the boiler shell? Identify the valve installed on the boiler inlet to control and prevent backflow of feedwater to the pump.

Accepted Answer

Introduction / Context:Proper arrangement of valves in the feedwater line is crucial for safety and operational control. The valve at the boiler inlet must allow feedwater entry while preventing backflow toward the pump and permitting isolation for maintenance.Given Data / Assumptions:A feed pump delivers water under pressure to the boiler.A non-return and throttling function is required at the boiler connection.Other mountings (safety, stop, blow-off) serve different locations and purposes.Concept / Approach:The feed check valve is a combined stop and non-return valve placed at the boiler inlet. It prevents reverse flow if pump pressure falls and allows the operator to regulate or isolate the feed. In contrast, a blow-off cock is at the bottom for periodic blow-down, and the steam stop valve is on the steam outlet, not the feed line.Step-by-Step Solution:Identify function: control + non-return on feed line → feed check valve.Map other devices: blow-off (bottom drain), steam stop (main steam outlet), safety valve (over-pressure relief).Hence, option (b) is correct.Verification / Alternative check:Standard boiler codes and textbooks show a check/stop valve at the boiler feed connection, often near the shell or drum nozzle.Why Other Options Are Wrong:Blow-off: used for sludge/mud removal and level maintenance, not for feed isolation.Steam stop: on steam side, not feed side.Safety valve: pressure relief, unrelated to feed control.Common Pitfalls:Describing any valve near the boiler as a “stop valve.” The feed check valve is specifically on the feedwater line with non-return action.Final Answer:feed check valve

Question 18

Locomotive boiler draught production: In a locomotive-type multi-tubular fire-tube boiler, which device is primarily responsible for creating the draught (the pressure difference that draws air through the firebox and gases through the tubes)?

Accepted Answer

Introduction / Context:Draught is the small but crucial pressure difference that pulls combustion air through the grate and moves hot gases through boiler heating surfaces. In stationary plants it is often produced by tall chimneys or mechanical fans, but the situation is different in locomotives.Given Data / Assumptions:Boiler type: locomotive, multi-tubular, fire-tube.Operation: moving vehicle with limited stack height.Available energy source on board: exhaust steam from cylinders.Concept / Approach:Because a locomotive cannot carry a tall chimney to generate natural draught, it uses the kinetic energy of exhaust steam discharged through a blast pipe (steam jet) into the smokebox. The jet entrains flue gases, creating a low pressure region that pulls gases from the firebox through the tubes, thereby sustaining strong combustion even at high firing rates.Step-by-Step Solution:Identify draught need: continuous flow of air and gases through grate and tubes.Recognize geometric limitation: short stack height on locomotives limits natural draught.Use of exhaust: high-velocity steam jet from cylinders is directed up the stack.Effect: jet entrains gases, lowers pressure in smokebox, producing draught.Verification / Alternative check:Locomotive schematics show a blast nozzle and petticoat pipe; draught strength correlates with engine exhaust flow (faster running → stronger draught).Why Other Options Are Wrong:Centrifugal/ID fans are not standard on traditional steam locomotives; space, power supply, and maintenance make them impractical on vintage designs.Chimney alone is too short to produce adequate draught on a locomotive.“None of these” is incorrect because the steam jet is the established method.Common Pitfalls:Assuming all boilers rely on tall chimneys; forgetting that moving stock uses exhaust energy for draught.Final Answer:steam jet

Question 19

Draught economics comparison: The ratio of the energy required to produce artificial draught (expressed as head or J per kg of flue gas) to the mechanical equivalent of the extra heat carried away per kg of flue gases when natural draught is used is…

Accepted Answer

Introduction / Context:Plant designers often compare natural draught (chimney) with artificial draught (fan or steam-jet) on an energy basis. The key question is whether the mechanical or electrical energy spent on artificial draught is justified by the heat saved that would otherwise be lost with a high-temperature chimney plume.Given Data / Assumptions:Artificial draught requires input energy (fan power per kg of flue gas), expressed as J/kg or equivalent head.Natural draught generally entails higher stack temperatures, increasing heat loss in flue gases.Comparison is made per unit mass of flue gas for a fair basis.Concept / Approach:The defined ratio contrasts the input energy for artificial draught with the saved heat that would have been carried away under natural draught. In boiler engineering shorthand, this ratio is referred to as the efficiency of the fan system with respect to draught economics. A value well below 1.0 indicates that spending a little mechanical energy saves a lot of chimney heat loss, making artificial draught an efficient choice.Step-by-Step Solution:Let E_mech = energy required by the fan per kg of flue gas.Let E_loss = extra heat carried away per kg in natural draught operation.Define ratio R = E_mech / E_loss.Interpretation: smaller R → more attractive fan draught.Verification / Alternative check:Typical fan powers are modest compared to heat rates, so artificial draught commonly improves overall plant efficiency and control.Why Other Options Are Wrong:Efficiency of the chimney: pertains to performance of a stack, not a comparison between fan input and chimney heat loss.Boiler efficiency and power of the boiler: relate to fuel-to-steam conversion or output, not draught production comparison.Specific draught coefficient: not a standard term for this ratio.Common Pitfalls:Confusing thermodynamic boiler efficiency with draught-system economics; ignoring that the ratio is per unit mass of flue gas.Final Answer:efficiency of the fan

Question 20

Steam engine facts — choose the correct statement: Which of the following statements about steam engines is correct?

Accepted Answer

Introduction / Context:Objective questions often test common misconceptions about engine layout, operating pressure ranges, and condensing practice. Here we examine three assertions and identify whether any is correct.Given Data / Assumptions:Comparison between horizontal and vertical reciprocating steam engines.Possibility of sub-atmospheric cylinder pressure in condensing engines.Use of compounding (multi-stage expansion) with or without condensers.Concept / Approach:We evaluate each statement against standard engineering practice:1) Layout: Vertical engines save floor area compared with horizontal engines of similar output, so a horizontal engine usually requires more floor space, not less.2) Cylinder pressure: Condensing engines commonly exhaust to a condenser under vacuum, so cylinder pressure can fall below atmospheric near exhaust; the claim that it is not allowed is false.3) Compounding: Many compound engines are specifically paired with condensers to exploit larger expansion ratios efficiently; the blanket statement that they are generally non-condensing is false.Step-by-Step Solution:Check (a): false; vertical layout is more compact in plan area.Check (b): false; condensing produces sub-atmospheric back pressure.Check (c): false; compounding and condensing are often combined.Therefore none of the listed statements is correct → choose “none of these”.Verification / Alternative check:Historical plant layouts and textbooks consistently cite vertical engines for reduced footprint and condensing for efficiency gains through lowered back pressure.Why Other Options Are Wrong:Option (d) “all of the above” cannot be true because each individual statement is false.Options (a), (b), (c) are individually refuted by standard practice.Common Pitfalls:Applying internal-combustion engine intuition to steam engines; forgetting the effect of condensers on exhaust pressure and the typical pairing of compounding with condensing.Final Answer:none of these

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