STEAM POWERPLANT

steam power plant

A __________is a facility designed to generate electricity through the use of steam as the primary working fluid.

principles of thermodynamics

It operates based on the__________, utilizing the conversion of heat energy into mechanical work and subsequently into electrical energy

boiler, a turbine, a condenser, and a generator

The primary components of a steam power plant include a ______, _________, ________, and a_____

Boiler

The ________ is responsible for heating water to generate steam. This is typically achieved by burning fossil fuels (such as coal, oil, or natural gas) or by using nuclear energy. The generated steam is at high pressure and temperature.

boiler

It acts as the heart of the power generation process, converting heat energy into high-pressure steam that drives turbines to produce electricity.

Heat Transfer Efficiency

______________ are designed to maximize heat transfer from the combustion process to the water, ensuring that the heat generated is efficiently utilized to produce steam. This efficient heat transfer contributes to overall plant efficiency and reduces fuel consumption.

Steam Generation Control

____________ precisely control the steam pressure and temperature, providing a consistent supply of steam to the turbines. This control is essential for maintaining stable and efficient power generation

Steam Quality Assurance

_________ remove impurities from the water and maintain the purity of the steam, preventing corrosion and damage to the turbines and other components. This ensures the longevity and reliability of the power plant.

Fuel Flexibility

__________ can be designed to utilize various fuel sources, including coal, natural gas, oil, or even biomass. This flexibility allows power plants to adapt to changing fuel.

Co-generation Potential

__________ can be combined with other systems to provide co-generation, producing both electricity and heat simultaneously. This efficient use of energy reduces overall fuel consumption and environmental impact.

❑Periodical cleaning of boilers

❑Periodical soot blowing

❑Proper water treatment program and blow down control

❑Draft control

❑Excess air control

❑Percentage loading of boiler

❑Steam generation pressure and temperature

❑Boiler insulation

❑Quality of fuel

Factors Affecting Boiler Performance

Maximum Continuous Rating (MCR)

___________ - Steam boilers rated output is also usually defined as MCR this is the maximum evaporation rate that can be sustained for 24 hours and may be less than a shorter duration maximum rating.

Boiler Rating

_____________- Conventionally, boilers are specified by their capacity to hold water and the steam generation rate. Often, the capacity to generate steam is specified in terms of equivalent evaporation (kg of steam / hour at 100°C). Sample: The equivalent of the evaporation of 1 kg of water at 100 °C to steam at 100 °C.

Combustion efficiency

______________ - is the effectiveness of the burner only and relates to its ability to completely burn the fuel. The boiler has little bearing on ______________. A well designed burner will operate with as little as 15 to 20% excess air, while converting all combustibles in the fuel to useful energy.

Thermal efficiency

_____________ - is the effectiveness of the heat transfer in a boiler. It does not take into account boiler radiation and convection losses.

Boiler efficiency

___________ - the term _________ is often substituted for combustion or thermal efficiency. True _________ is the measure of fuel to steam efficiency.

Fuel to steam efficiency

________________ - is calculated using either of the two methods (input output method and heat loss method) see attached pdf file for sample computations

Boiler turndown

____________- is the ratio between full boiler output and the boiler output when operating at low fire. Typical _____________ is 4:1.

Primary air

__________ - That part of the air supply to a combustion system which the fuel first encounters.

Secondary air

____________ - The second stage of admission of air to a combustion system, generally to complete combustion initiated by the primary air. It can be injected into the furnace of a boiler under relatively high pressure when firing solid fuels in order to create turbulence above the burning fuel to ensure good mixing with the gases produced in the combustion process and thereby complete combustion.

Stoichiometric

___________ - __________ air is that quantity of air, and no more, which is theoretically needed to burn completely a unit quantity of fuel.

'Sub-stoichiometric'

_____________ refers to the partial combustion of fuel in a deficiency of air

Balanced draught

___________- The condition achieved when the pressure of the gas in a furnace is the same as or slightly below that of the atmosphere in the enclosure or building housing it

Gross calorific value (GCV)

__________ - The amount of heat liberated by the complete combustion, under specified conditions, by a unit volume of a gas or of a unit mass of a solid or liquid fuel, in the determination of which the water produced by combustion of the fuel is assumed to be completely condensed and its latent and sensible heat made available.

Net calorific value (NCV)

______________ - The amount of heat generated by the complete combustion, under specified conditions, by a unit volume of a gas or of a unit mass of a solid or liquid fuel, in the determination of which the water produced by the combustion of the fuel is assumed to remain as vapor

Carbon monoxide (CO)

_____________ - Produced from any source that burns fuel with incomplete combustion, causes chest pain in heart patients, headaches and reduced mental alertness.

Blow down

_____________- The removal of some quantity of water from the boiler in order to achieve an acceptable concentration of dissolved and suspended solids in the boiler water

Perfect combustion

_______________ - The complete oxidation of the fuel, with the exact theoretical (stoichiometric) amount of oxygen (air) required

Wet Steam Saturated

_____________- steam which contains moisture

Dry Steam

__________- Either saturated or superheated steam containing no moisture.

Superheated Steam

__________ – steam heated to a temperature above the boiling point or saturation temperature corresponding to its pressure.

Oxygen trim

____________- sensor measures flue gas oxygen and a closed loop controller compares the actual oxygen level to the desired oxygen level

Heat transfer mediums

_____________ - there are different types of heat transfer medium (steam, hot water and thermal oil). Steam and Hot water are most common and it will be valuable to briefly examine.

Thermic Fluid

_____________- is used as a heat transfer mechanism in some industrial process and heating applications. ____________ may be a vegetable or mineral based oil and the oil may be raised to a high temperature without the need for any pressurization.

Hot water

__________- Water is a fluid with medium density, high specific heat capacity, low viscosity and relatively low thermal conductivity. At relatively low temperature e.g. 70°C - 90°C, ____________ is useful for smaller heating installations.

Steam, sensible heat, enthalpy, steam

______________ - When water is heated its temperature will rise the heat added is called ___________ and the heat content of the water is termed its ________. The usual datum point used to calculate enthalpy is 0°C. When the water reaches its boiling point, any further heat input will result in some proportion of the water changing from the liquid to the vapor state i.e., changing the __________.

'latent heat of evaporation', “saturation condition”

The heat required for this change of state is termed the ___________ and is expressed in terms of a fixed mass of water. Where no change in temperature occurs during the change of state, the steam will exist in equilibrium with the water. This equilibrium state is termed ____________.

'superheated', compressible

Saturation conditions can occur at any pressure, although at each pressure there is only one discrete temperature at which saturation can occur. If further heat is applied to the saturated steam the temperature will rise and the steam will become __________. Any increase in temperature above saturated conditions will be accompanied by a further rise in enthalpy. Steam is useful heat transfer medium because, as a gas, it is _________. At high pressure and consequently density, steam can carry large quantities of heat with relatively small volume.

Turbine

_________: The high-pressure steam from the boilers is directed into a ________. The ____________is designed with blades that are turned by the force of the steam’s high-speed flow. As the steam flows through the ________, its high-pressure energy is converted into rotational mechanical energy

Generator

__________: The turbine is connected to a _______, which consists of coils of wire within a magnetic field. As the turbine spins, it turns the rotor of the ________, creating a moving magnetic field. This movement induces an electric current in the wire coils, ultimately producing electrical energy.

Condenser

____________: After passing through the turbine, the steam is directed to the ________. Here, the steam is cooled and condensed back into water, releasing its latent heat. This process allows for the efficient reuse of the water in the boiler, reducing water consumption and increasing overall efficiency.

Cooling System

______________: Steam power plants require a _______________ to dissipate excess heat from the condenser. This can involve cooling water from nearby water bodies, cooling towers, or other heat exchange methods.

Conventional steam power plants

______________: These plants use fossil fuels, such as coal, oil, or natural gas, to heat water and create steam.

Nuclear steam power plants

_____________: These plants use nuclear fission to heat water and create steam.

Geothermal steam power plants

_______________: These plants use geothermal energy to heat water and create steam.

Solar thermal power plants

_______________: These plants use solar energy to heat water and create steam.

Waste heat steam power plants

_______________: These plants use waste heat from other industrial processes to heat water and create steam

Low Initial Cost

Less Land Required

Fuel Flexibility

Easy Installation

Scalability

Steam power plants have a number of Advantages, including:

✓ ___________: Economical setup compared to other power plants.

✓ ___________: Can be installed in smaller areas compared to hydroelectric plants.

✓ ___________: Can use coal, natural gas, oil, or biomass. They are relatively inexpensive to build and operate.

✓ ___________: Can be set up near fuel and water supplies.

✓ ___________: They can be used to generate electricity on a large or small scale.

Low Efficiency

Environmental Impact

High Running Costs

Water Requirements

Noise Pollution

Steam power plants have a number of Disadvantages, including:

❖ ___________: Overall efficiency is around 29% to 41%.

❖ ___________: Air pollution from fossil fuels contributes to climate change.

❖ ___________: Fuel and maintenance costs are high.

❖ ___________: Needs a large water source.

❖ ___________: Can be noisy during operation.