Online Thermal Power Plant Test

Air heaters are indeed used in power plants to heat the air that is used for the combustion of coal. This is because heating the air before it enters the combustion chamber helps to increase the efficiency of the combustion process. By preheating the air, the coal can burn more efficiently, resulting in a more effective transfer of heat energy to produce steam, which in turn drives the turbines to generate electricity. Therefore, the statement that air heaters are used in power plants to heat the air used for coal combustion is true.

Pulverized coal refers to coal that has been broken down into fine particles. This process involves grinding the coal into a powder, which increases its surface area and allows for more efficient combustion. Pulverized coal is commonly used in power plants as it burns more efficiently and produces less pollution compared to larger coal particles.

All of the options mentioned contribute to the improvement of efficiency in a Rankine cycle. Reheating of steam at an intermediate stage increases the efficiency by increasing the average temperature at which heat is added to the steam. Regeneration, which involves using the steam that has already expanded in the turbine to heat the boiler feed water, reduces the amount of heat that needs to be supplied from an external source, thus improving efficiency. Lastly, the use of high pressures allows for a higher temperature difference between the heat source and the heat sink, resulting in improved efficiency.

Power plants using coal work closely on the Rankine cycle. The Rankine cycle is a thermodynamic cycle that is commonly used in power plants to generate electricity. It involves the conversion of heat energy from the combustion of coal into mechanical work, which is then used to drive a turbine and produce electricity. The Rankine cycle consists of four main processes: heating the working fluid, expanding the fluid in a turbine, condensing the fluid back into a liquid, and compressing the liquid back to its initial state. This cycle is well-suited for coal-fired power plants as it allows for efficient energy conversion.

The statement is true because when the flue gas is cooled to a temperature below the dew point, moisture in the gas condenses and forms acidic droplets. These droplets can cause corrosion in the air pre heater tube. By limiting the cooling of the flue gas to a temperature above the dew point, the formation of acidic droplets can be minimized, reducing the chances of corrosion.

In a power plant, coal is commonly transported from the storage place to boilers using V-belts. V-belts are a type of flexible belt that are specifically designed to transmit power efficiently between two rotating shafts. They are commonly used in industrial applications, including power plants, due to their high strength and durability. V-belts provide a reliable and efficient method of transporting coal from the storage area to the boilers, ensuring a steady supply of fuel for power generation.

The statement "Steam coal is not suitable for steam boilers" is false. Steam coal, also known as thermal coal, is specifically designed for use in steam boilers. It has high carbon content and is able to generate a high amount of heat when burned, making it ideal for producing steam in boilers. Therefore, steam coal is indeed suitable for steam boilers.

A gas turbine power plant is suitable as a peak load plant because it can be quickly started and stopped, allowing it to respond rapidly to fluctuations in electricity demand. Gas turbines have a high ramp rate, meaning they can quickly increase or decrease their power output to match the changing load requirements. This makes them ideal for meeting peak demand periods when electricity consumption is at its highest. Additionally, gas turbines have a relatively low capital cost compared to other power plant technologies, making them a cost-effective option for meeting short-term peak demand.

The statement suggests that the still process is used for removing sulphur dioxide from flue gases. This means that the still process is an effective method for eliminating sulphur dioxide from the gases emitted by industrial processes. The correctness of this statement implies that the still process is a reliable and commonly used technique in industries to reduce the emission of sulphur dioxide, which is a harmful pollutant.

In a silver oxide cell, depolarization is the process of reducing the silver oxide back to silver. This reduction reaction occurs at the cathode, where the silver ions in the silver oxide gain electrons and form solid silver. Therefore, the depolarization process is indeed accompanied by the formation of oxide of silver, making the statement true.

A perfect heat absorber is also a perfect radiator because an object that can absorb all incoming heat without reflecting or transmitting any of it would also emit all the absorbed heat without any loss. This means that it would radiate heat at the maximum possible rate, making it a perfect radiator as well.

Bituminous coal is considered as superior quality of coal because it has a higher carbon content and lower moisture content compared to other types of coal. It also has a higher energy content and burns more efficiently, making it a preferred choice for industrial and domestic use. Additionally, bituminous coal produces less smoke and emissions when burned, making it a cleaner option compared to other types of coal.

The efficiency of a thermal power plant improves with the use of high steam pressures. When high steam pressures are used, the temperature of the steam increases, which in turn increases the thermal efficiency of the power plant. This is because higher steam pressures result in more efficient heat transfer, allowing the plant to generate more electricity with the same amount of fuel. Additionally, high steam pressures also reduce the amount of steam required to produce a given amount of electricity, resulting in lower fuel consumption and improved overall efficiency.

Live storage of coal in a power plant refers to the storage of coal that is enough to meet the plant's demand for a continuous period of 24 hours. This means that the power plant has enough coal readily available and accessible for combustion to generate electricity without interruptions or delays. This ensures a smooth and continuous supply of coal for the power plant's operations, preventing any disruptions in power generation.

A ball mill is a type of equipment used for pulverizing coal. It consists of a rotating cylinder filled with steel balls that grind the coal into a fine powder. The coal is fed into the cylinder through a hopper, and the balls inside the mill crush and grind it into the desired size. The pulverized coal is then used as fuel in burners to generate heat or electricity. A stoker, on the other hand, is a device used to distribute coal into a furnace, while a burner is a mechanism that ignites and burns the pulverized coal. Therefore, the correct answer is ball mill.

Nuclear energy is not considered a non-conventional source of energy because it is a well-established and widely used source of power generation. Non-conventional sources of energy refer to those that are alternative and environmentally friendly, such as tidal, geothermal, and wind energy, which are renewable and have minimal impact on the environment. Nuclear energy, on the other hand, relies on the process of nuclear fission, which involves the use of radioactive materials and can have significant environmental and safety concerns.

Slow neutrons are very efficient in causing fission of uranium 235 because they have a higher probability of being captured by the uranium nucleus. When a slow neutron is captured by a uranium 235 nucleus, it becomes unstable and splits into two smaller nuclei, releasing a large amount of energy in the process. This is known as nuclear fission. Fast neutrons, on the other hand, have a lower probability of being captured by the uranium nucleus, making them less efficient in causing fission. Therefore, slow neutrons are indeed very efficient in causing fission of uranium 235.

Superheated steam is always at a temperature higher than the saturation temperature corresponding to a steam pressure because superheating involves heating the steam above its saturation point. Saturation temperature is the temperature at which steam and water coexist in equilibrium at a given pressure. By further heating the steam beyond this point, it becomes superheated and its temperature increases. This process is commonly used in power plants to increase the energy efficiency of steam turbines.

Coal used in power plants is commonly referred to as steam coal. This is because steam coal is primarily used to generate steam, which is then used to drive turbines and produce electricity in power plants. Steam coal has a high carbon content and is specifically chosen for its ability to efficiently produce heat and steam when burned. Other types of coal, such as charcoal, coke, and soft coal, may have different properties and uses, but steam coal is specifically used in power generation.

As steam expands in a turbine, its specific volume increases. This means that the volume occupied by a unit mass of steam increases. As the steam expands, it takes up more space per unit mass. This is because the pressure decreases as the steam expands, causing the steam to occupy a larger volume. Therefore, the specific volume of the steam increases as it expands in the turbine.

The burning of low grade fuel can be improved by blending it with better quality fuel, using oil assisted ignition, or pulverizing it. Blending with better quality fuel helps to enhance the combustion efficiency and reduce emissions. Oil assisted ignition provides a more efficient and complete combustion process. Pulverizing the fuel increases its surface area, allowing for better mixing with air and more efficient combustion. Therefore, any of the above methods can improve the burning of low grade fuel.

The heating value of Indonesian coal is approximately 5000-6500 kcal/kg. This means that when the coal is burned, it can release this amount of energy per kilogram. The heating value of coal is an important factor in determining its quality and suitability for various applications, such as power generation or industrial processes. Higher heating values indicate that the coal has a higher energy content and can produce more heat when burned. Therefore, the correct answer is 5000-6500 kcal/kg.

The correct answer is 110 kg/cm2 to 170 kg / cm2. This range of steam pressures is commonly used in thermal power plants. It is important to have a high enough steam pressure to generate sufficient energy to drive the turbines and produce electricity. However, excessively high steam pressures can lead to safety concerns and equipment damage. Therefore, the range of 110 kg/cm2 to 170 kg / cm2 strikes a balance between generating enough power and maintaining safe operating conditions.

Wet steam enters the superheater of a boiler. The superheater is a component in the boiler that is responsible for further heating the steam to increase its temperature and energy content. Wet steam refers to steam that still contains some moisture or water droplets. By passing through the superheater, the wet steam is heated to a higher temperature, causing the moisture to evaporate and resulting in superheated steam, which is dry and contains no water droplets.

The critical pressure of water is the pressure at which water transitions from a liquid to a gas phase. It is a specific point where the properties of water change significantly. The correct answer, 213.8 kg/cm2, represents the critical pressure of water, indicating that at this pressure, water will undergo a phase change from liquid to gas.

The statement is false because air from the air preheater is not sent to the forced draft fans. The air preheater is a device used to heat the air before it enters the furnace, while the forced draft fans are used to supply the combustion air to the furnace. The air from the air preheater is typically sent to the primary air fans, which then supply the preheated air to the furnace.

Water is supplied to a boiler at more than the steam pressure on the boiler. This is because in order for water to be converted into steam, it needs to be heated to a temperature higher than its boiling point at atmospheric pressure. By supplying water at a pressure higher than the steam pressure on the boiler, it ensures that the water will reach a temperature necessary for it to convert into steam.

The statement is false because in an economizer, the heat of flue gases is used to preheat the feedwater, not to reheat the steam. The purpose of an economizer is to increase the efficiency of a boiler system by recovering heat from the flue gases before they are expelled into the atmosphere. This recovered heat is then used to preheat the feedwater, reducing the amount of fuel needed to raise the temperature of the water to its boiling point. Reheating the steam, on the other hand, is typically done in a separate process called steam superheating.

The pressure of steam in the condenser is much less than the pressure. This is because the condenser is designed to reduce the pressure of the steam and convert it back into a liquid state. The steam enters the condenser at a high pressure and temperature, and as it comes into contact with the cool water or air in the condenser, it loses heat and condenses into water. This condensation process causes the pressure of the steam to decrease significantly, resulting in a much lower pressure in the condenser compared to the initial pressure of the steam.

Water gas is a mixture of carbon monoxide (CO), nitrogen (N2), and hydrogen (H2). It is produced by reacting steam with a carbon-based fuel, such as coal or natural gas, in a process called gasification. The reaction produces carbon monoxide and hydrogen gas, along with small amounts of nitrogen. Water gas is used as a fuel and as a raw material for the production of chemicals such as methanol and ammonia.