Steam Boilers: Definition, Function & Classification

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Questions and Answers

In a Babcock & Wilcox boiler, what is the primary function of the mud box located below the down take header?

To collect and remove sediments from the water. (correct)
To regulate the flow of water into the boiler drum.
To preheat the water before it enters the water tubes.
To store excess water in case of fluctuating steam demand.

What is the arrangement of the water tubes in a Babcock & Wilcox boiler?

Inclined and connected at right angles to headers. (correct)
Horizontal and parallel to the boiler drum.
Coiled around the furnace for maximum heat absorption.
Vertical and directly connected to the firebox.

What is the purpose of the chain grate stoker in a Babcock & Wilcox boiler?

To preheat the incoming air for combustion.
To control the water level in the boiler drum.
To automatically feed coal into the furnace and remove ash. (correct)
To regulate the air supply to the furnace.

How are the super heater tubes arranged within the Babcock & Wilcox boiler?

In the combustion chamber underneath the boiler drum. (D) Signup and view all the answers

In a Babcock & Wilcox boiler, how is the water and steam drum typically supported?

Suspended from iron girders resting on iron columns. (C) Signup and view all the answers

What is the difference in function between the uptake and down take headers in a Babcock & Wilcox boiler?

Down take headers are responsible for water intake, while uptake headers collect the heated water and steam mixture. (A) Signup and view all the answers

In the superheater of a Babcock & Wilcox boiler, how is steam directed from the superheater tubes to the steam stop valve?

From the upper junction box to the T-tube in the steam drum, then to the steam stop valve. (B) Signup and view all the answers

How does the arrangement of water tubes contribute to the efficiency of heat transfer in a Babcock & Wilcox boiler?

The inclined arrangement of the tubes promotes natural water circulation, enhancing heat absorption. (B) Signup and view all the answers

What is the primary function of adjusting the speed of a chain grate stoker in a boiler system?

To ensure complete combustion of varying qualities of coal. (B) Signup and view all the answers

In a boiler's water circuit, what causes the water to flow upwards through the inclined water tubes?

Reduction in water density as it is heated. (A) Signup and view all the answers

What directs the path of hot gases within the boiler to maximize heat transfer to the water tubes?

An arrangement of baffle plates. (C) Signup and view all the answers

Why is rapid water circulation between the boiler drum and water tubes important for boiler operation?

It efficiently transfers heat and separates steam in the drum. (C) Signup and view all the answers

Where does the superheating of steam primarily occur in the described boiler system?

In the superheater tubes located in the combustion chamber. (D) Signup and view all the answers

What is the ultimate destination of the superheated steam after it leaves the superheater in the boiler?

It is directed to the prime mover to perform work. (D) Signup and view all the answers

Which component ensures a constant water level is maintained within the boiler drum?

Feed valve (B) Signup and view all the answers

In a scenario where superheated steam isn't needed, what pathway does the steam take from the steam space in a boiler?

It directly exits to the prime mover via the steam stop valve. (A) Signup and view all the answers

What happens to the water and steam mixture as it leaves the hottest sections of the water tubes?

It flows into the uptake header before reaching the boiler drum. (A) Signup and view all the answers

What is a key reason water tube boilers can achieve quicker steam generation compared to fire tube boilers?

They contain a lower ratio of water content to steam capacity. (A) Signup and view all the answers

Why are water tube boilers better suited for high-pressure applications compared to fire tube boilers?

Their design avoids having tubes inside the boiler drum, allowing for greater wall thickness relative to fire tube boilers. (D) Signup and view all the answers

How does the design of water tube boilers enhance the rate of evaporation compared to fire tube boilers?

By having a relatively large heating surface area due to the use of many small diameter tubes. (D) Signup and view all the answers

What characteristic of water circulation in water tube boilers minimizes sediment deposition on heating surfaces?

A more positive circulation compared to fire tube boilers. (B) Signup and view all the answers

What aspect of water tube boiler design allows for greater flexibility in fuel type and firing method?

Being externally fired, which allows the furnace size and proportions to be adjusted for any fuel. (A) Signup and view all the answers

How does the flow of hot gases in relation to the water tubes in a water tube boiler affect heat transfer efficiency?

Hot gases flow at right angles to the water tubes, promoting more effective heat transfer. (A) Signup and view all the answers

For a power plant requiring a specific power output, how does the space requirement of a water tube boiler compare to that of a fire tube boiler?

A water tube boiler occupies less space than a fire tube boiler for the same power output. (A) Signup and view all the answers

Why are water tube boilers considered easier to maintain compared to fire tube boilers?

All parts are easily accessible for cleaning, repairing, and inspection. (A) Signup and view all the answers

A manufacturing plant is considering replacing its old boiler system. Which factor would DISCOURAGE them from choosing a water tube boiler?

The need for a system that can be easily adapted for mobile applications. (C) Signup and view all the answers

What is the PRIMARY reason for equipping boilers with mountings and accessories?

To ensure efficient functioning, easy maintenance, and most importantly, safety. (C) Signup and view all the answers

Which of the following is NOT a primary function of boiler mountings?

Increasing the boiler's thermal efficiency. (B) Signup and view all the answers

Why are boilers required to have at least two water level indicators?

To provide a redundant system in case one fails. (C) Signup and view all the answers

Which of the following is the MOST likely consequence of using impure feed water in a water tube boiler?

Formation of scales inside the water tubes, leading to overheating and bursting. (B) Signup and view all the answers

A remote lumber mill needs to replace a boiler and requires ease of on-site assembly due to limited infrastructure. Which boiler type characteristic would be MOST beneficial?

Easy dismantling and quick erection at the site. (B) Signup and view all the answers

Compared to fire-tube boilers, water-tube boilers generally have what DISADVANTAGE regarding initial cost?

Significantly higher initial cost. (C) Signup and view all the answers

What is the primary function of a fusible plug in a boiler system?

To automatically shut off the fuel supply when the water level is critically low. (B) Signup and view all the answers

Why is superheated steam preferred in thermal power generation?

To avoid condensation and corrosion of turbine parts. (D) Signup and view all the answers

Where is the manhole typically located on a boiler, and what is its purpose?

On the top of the boiler for internal inspection and cleaning. (D) Signup and view all the answers

Which of the following best describes the function of a mud box in a boiler system?

To collect sediment and impurities from the boiler water. (C) Signup and view all the answers

What is the primary function of a steam separator?

To remove water particles from the steam. (A) Signup and view all the answers

Where is a steam separator typically installed in relation to a steam turbine?

Very close to the steam turbine. (C) Signup and view all the answers

What is the main purpose of boiler accessories like economizers and air preheaters?

To improve the overall efficiency of the boiler system. (A) Signup and view all the answers

How does an economizer contribute to improving boiler efficiency?

By preheating the feed water using waste heat from flue gases. (C) Signup and view all the answers

What is the main purpose of a steam trap?

To discharge condensed water from steam lines without releasing steam. (A) Signup and view all the answers

What is the primary benefit of using an air preheater in a boiler system?

It recovers heat from exhaust gases to warm intake air, accelerating combustion. (C) Signup and view all the answers

How does the superheater increase the temperature of steam?

By supplying additional heat from flue gases. (B) Signup and view all the answers

What is a key characteristic of the steam pressure during the superheating process?

It remains constant because of the continuous flow from the boiler steam space (A) Signup and view all the answers

An air preheater is installed between which two components in a typical boiler system?

The economizer and the chimney. (A) Signup and view all the answers

Why is it important to maintain the water level above the fusible plug in a boiler?

To prevent the fusible metal from melting and prematurely extinguishing the fire. (A) Signup and view all the answers

A power plant engineer notices excessive water accumulation in the steam pipes. Which accessory should be inspected first to address this issue?

The steam trap, for proper drainage. (B) Signup and view all the answers

Which of the following best describes the arrangement of a bypass pipe in relation to a steam trap?

It branches off from the main steam pipe line and allows condensed water to be discharged. (C) Signup and view all the answers

Flashcards

Babcock and Wilcox Boiler

A type of water tube boiler with specific components for steam generation.

Water and Steam Drum

The main component that contains water and steam, suspended from girders.