Question 1

Benson boiler: average operating pressure range and representative value.  Select the most commonly cited average operating pressure for a Benson boiler used in exam practice (options in bar).

Accepted Answer

Concept Benson boilers are designed for very high pressure operation (often at or above the water critical pressure of ≈221 bar). In many standard MCQs, the representative average operating pressure is taken as about 200 bar among the discrete options provided. Clarification Actual installations may operate around or above the critical pressure; however, within the choices given, 200 bar is the conventional key. Final Answer 200 bar

Question 2

Natural draught definition: verify the correctness of the statement.  Statement: A draught produced by a chimney due to the density difference between hot gases inside the chimney and the colder outside air is called natural draught.  Choose the cor…

Accepted Answer

Concept Natural draught arises from the density difference between hot flue gases in the chimney and cooler ambient air. This buoyancy effect creates a pressure difference that draws combustion air through the furnace and expels gases through the stack—without fans. Contrast Induced draught: fan draws gases out. Forced draught: fan pushes air in. Final Answer True

Question 3

Aim of compounding in steam engines: identify the principal objective(s).  Compounding splits the total expansion across multiple cylinders (HP→IP→LP) to improve performance.  Choose the best statement describing the aim.

Accepted Answer

Concept The primary aim of compounding is to reduce the temperature range within any single cylinder by spreading expansion across stages. This limits cylinder condensation and improves efficiency. About the other statements Sharing the overall expansion does lessen the per-cylinder expansion ratio (Option A), but the core aim is thermal (condensation control). Reduction in stroke length (Option B) is not a fundamental aim; it is design-dependent and not guaranteed. Final Answer To reduce the temperature range in each cylinder and thus reduce condensation

Question 4

Loeffler boiler classification: verify the circulation method.  Statement: The Loeffler boiler is a water-tube boiler that uses forced circulation of water/steam to avoid salt deposition in evaporator tubes.  Choose the correct option (True/False).

Accepted Answer

Concept The Loeffler boiler is a high-pressure water-tube boiler employing forced circulation. It superheats steam and uses a portion of that superheated steam to evaporate/feed the water externally, thereby preventing salt deposition in the main evaporator tubes. Final Answer True

Question 5

Crosshead function in a reciprocating steam engine: fill in the missing part correctly.  The function of a crosshead is to guide the motion of the __________ and prevent it from bending, while transmitting force to the connecting rod.  Choose the co…

Accepted Answer

Concept The crosshead maintains straight-line guidance of the piston rod and prevents it from bending under side thrust, while providing the joint to the connecting rod for rotary conversion at the crank. Final Answer piston rod

Question 6

Piston rod function: identify the correct role in a reciprocating steam engine.  Select the statement that correctly describes the function of a piston rod.

Accepted Answer

Concept The piston rod connects the piston to the crosshead, transmitting reciprocating motion. Guidance and bending control are duties of the crosshead (Option A), energy conversion occurs in the cylinder by piston expansion work (Option C), and exhaust timing is controlled by the valve gear (Option D). Final Answer To transfer motion from the piston to the crosshead

Question 7

Locomotive boiler dimensions: select the typical length of the boiler shell (approximate).  Choose the most commonly cited shell length among the options provided.

Accepted Answer

Concept Standard references for classic locomotive boilers cite a typical shell length ≈ 2 m (order of a couple of metres) with multi-pass fire-tubes and a large grate area for high, fluctuating steam demand in traction service. Final Answer 2 m

Question 8

Boilers classification: identify the correct combined statement about common boiler types  Check each named boiler against its family (fire-tube or water-tube) and firing arrangement.  Choose the correct option.

Accepted Answer

Given facts • Lancashire is a classic fire-tube boiler with two large furnace/flue tubes. • Typical fire-tube units (Cornish, Lancashire, locomotive, Scotch marine) are internally fired (furnace within the shell). • Babcock & Wilcox is a water-tube boiler (water/steam in tubes, hot gases outside). Concept/Approach Identify each boiler type by where the water/steam flows and where the furnace is placed. Result All three statements (a), (b), and (c) are correct, so the best choice is all of the above.

Question 9

Steam engines: effect of wire drawing (throttling during valve events) on the indicator diagram and work done  Assess whether throttling (wire drawing) reduces the diagram area and thus the indicated work of the engine.  State whether the statement …

Accepted Answer

Given statement Wire drawing (throttling through ports/valves) decreases the area of the indicator diagram and hence reduces work per cycle. Concept Wire drawing lowers the mean effective pressure (MEP) during admission/exhaust due to throttling losses; reduced MEP directly reduces the area enclosed by the pressure-volume (P–V) indicator diagram. Step-by-step logic • Losses at admission/exhaust → reduced pressure trace.• Reduced P–V area → lower indicated work per cycle. Final Answer True — area decreases and indicated work reduces

Question 10

Reciprocating steam engine: conversion of steam's thermal energy into mechanical work  Confirm the basic working principle — heat in steam is converted into piston reciprocation and then shaft work.  State whether the statement is true or false.

Accepted Answer

Working principle Steam expands against the piston producing a to-and-fro motion, which the mechanism converts to rotary work on the crankshaft. Thus the engine converts thermal energy of steam into mechanical energy. Final Answer True — heat energy in steam → piston to-and-fro motion → work

Question 11

The governing of steam engines keep the engine speed constant according to the changing load conditions

Accepted Answer

Yes

Question 12

Lancashire boiler is

Accepted Answer

all of these

Question 13

A device in which some portion of waste heat of flue gases is recovered to heat the air before it passes to the furnace for combustion purpose, is knwon as

Accepted Answer

air preheater

Question 14

The efficiency of the plant __________ with the mechanical draught.

Accepted Answer

increases

Question 15

The evaporative capacity of a boiler is defined as the evaporation of 15.653 kg of water per hour from and at 100° C.

Accepted Answer

No

Question 16

The chimney draught varies with

Accepted Answer

all of these

Question 17

The ratio of the __________ to the volume at cut-off is called expansion ratio.

Accepted Answer

swept volume

Question 18

In water tube boilers, the water passes through the tubes which are surrounded by flames and hot gases.

Accepted Answer

Yes

Question 19

The maximum heat loss is a boiler occurs due to

Accepted Answer

dry flue gases

Question 20

A Tandem type compound engine requires a larger flywheel.

Accepted Answer

True

Steam Boilers and Engines Questions