Question 1

Rankine cycle efficiency of a good Steam

Accepted Answer

The Rankine cycle efficiency of a good steam power plant typically ranges from 35 to 45%. This efficiency is influenced by factors such as the steam pressure and temperature, and the efficiency of the turbines and other components.

Question 2

A simple Rankine cycle operates the Boiler at 3 MPa with an outlet temperature of 350°C and the Condenser at 50 kPa. Assuming ideal operation and processes, what is the thermal efficiency of this cycle?

Accepted Answer

The thermal efficiency of an ideal Rankine cycle can be calculated using the formula: $\eta = 1 - \frac{q_{out}}{q_{in}}$, where $q_{out}$ and $q_{in}$ are the heat rejected in the condenser and the heat added in the boiler, respectively. These values depend on the specific enthalpies at different points in the cycle, which can be found using steam tables for the given pressures and temperatures. Without performing the specific calculations here, the efficiency of a typical Rankine cycle under these conditions (high boiler pressure and temperature, and relatively low condenser pressure) would be expected to be in the range of 30-40%, making option C (27.7%) the most plausible answer given the options.

Question 3

On what basis are fire and water tube boilers are classified?

Accepted Answer

Fire and water tube boilers are classified based on the configuration of the tubular heating surface through which heat from the combustion gases is transferred to the water to generate steam.

Question 4

Cornish boiler is an example of which type of boiler?

Accepted Answer

The Cornish boiler is a type of fire tube boiler where hot gases pass through tubes and water surrounds them.

Question 5

Stirling boiler is an example of which type of boiler?

Accepted Answer

Stirling boiler is an example of a water tube boiler, where the water is contained inside the tubes and the hot gases pass around them.

Question 6

Which of these is a stationary boiler?

Accepted Answer

The Babcock-Wilcox boiler is a stationary boiler, designed for stationary installations such as power plants, where it is used for steam generation. Unlike locomotive or marine boilers, which are designed to be mobile and are used on trains and ships respectively, the Babcock-Wilcox boiler is intended for fixed installations.

Question 7

Which of these is a mobile boiler?

Accepted Answer

Locomotive boilers are specifically designed for use in locomotives, making them mobile by nature as they are built to provide steam power for train movement.

Question 8

Are boilers defined on the basis of heat source.

Accepted Answer

Boilers can be classified based on the heat source they use, such as gas, oil, electricity, or solid fuels.

Question 9

What is the steam pressure limit of natural circulation boilers?

Accepted Answer

Natural circulation boilers typically operate at a steam pressure limit of up to 180bar. Higher pressures may require forced circulation methods.

Question 10

Which of the given boilers operate above critical pressure?

Accepted Answer

Once-through boilers operate above critical pressure, where water is converted to steam in a single pass without recirculation.

Question 11

Which type of boilers are called drum-less boilers?

Accepted Answer

Positive forced circulation boilers are called drum-less boilers because they do not have a steam drum.

Question 12

Chances of sediments depositing inside the water tubes in the shell is less due to?

Accepted Answer

The answer of Chances of sediments depositing inside the water...

Question 13

Out of the given option choose the advantage that supports fire tube boilers?

Accepted Answer

The answer of Out of the given option choose the...

Question 14

Apart from feedheating, what should a plant have to obtain a gain in thermal efficiency?

Accepted Answer

The answer of Apart from feedheating, what should a plant...

Question 15

Which of the following needs to be incorporated to prevent the low pressure turbine exhaust wetness from being excessive?

Accepted Answer

Double reheat is used in steam turbines to reduce moisture content in the low-pressure stages by reheating the steam between turbine stages, thus preventing excessive exhaust wetness.

Question 16

What is the critical point of steam generation in a "once through" boiler?

Accepted Answer

The answer of What is the critical point of steam...

Question 17

In a typical layout of a 215MW reheat power plant, the feed in the boiler is at?

Accepted Answer

In a typical 215MW reheat power plant, the feedwater entering the boiler is preheated to a temperature of about 238 degrees centigrade. This preheating process improves the efficiency of the power plant by reducing the amount of fuel needed to convert water into steam at high pressure and temperature.

Question 18

The input to the low pressure feedwater heater is from?

Accepted Answer

The input to the low pressure feedwater heater typically comes from the drain cooler, where the water is pre-cooled before being fed into the heater for further temperature adjustment as part of the feedwater heating process in power plants.

Question 19

The best capable alternative source which can meet the future energy demand is

Accepted Answer

Nuclear power plants are considered a capable alternative for meeting future energy demands due to their high energy output and low greenhouse gas emissions compared to fossil fuels.

Quiz 1: Boiler Efficiency and Classification