30-04-2011, 03:17 PM
PRESENTED BY:
MS. P. SAI REVATHI
ppt.ppt (Size: 3.21 MB / Downloads: 252)
ABSTRACT
The electricity requirements of the world including India are increasing at alarming
It is also now widely recognized that the fossil fuels and other conventional resources, presently being used for generation of electrical energy, ..
MAGNETO HYDRO DYNAMIC (MHD) power generation is a new unique method of power generation.
Michael Faraday (1832) conducted MHD experiments
The first successful power generation experiment, developed by Richard Rosa in 1959, generated 10 kW with a timber walled channel
In 1972 in Moscow, a large experimental facility, the "U-25," used a 250 MW natural gas combustor and generated 20 MW
When an electrical conductor is moved so as to cut lines of magnetic induction, charged particles in the conductor experience a force
. The negative charges tend to move in one direction, and the positive charges in the opposite direction.
In conventional steam power plants, the heat released by the fuel is converted into rotational mechanical energy by means of a thermo cycle and the mechanical energy is then used to drive the electric generator
Thus two stages of energy conversion
electrical energy is directly generated from hot combustion gases produced by the combustion of fuel without moving part
MHD generator is heat engine operating on a turbine cycle and transforming the internal energy of gas directly into electrical energy.
PRINCIPLE OF WORKING OF AN MHD GENERATOR…
The basic principle of MHD is just similar to dynamo except that the solid conductor of high electrical conductivity is replaced by a gas with comparatively low value of electrical conductivity
If the gas is heated to high temperature it gets converted into plasma and plasma is conductor of electricity.
HOW AN MHD GENERATOR WORKS?
electrically conducting gas at a very high temperature is passed at high velocity through a strong magnetic field
at right angles to the direction of flow
There by generating electrical energy. The electrical energy is then collected from stationary electrodes placed on the opposite sides of the channel
The current so obtained is direct current which can be converted into ac by an inverter.
On heating of a gas, the outer electrons escape out from its atoms or molecules.
The particles acquire an electric charge and the gases passes into the state of plasma
Air becomes highly ionized at temperatures of 5,0000 to 6,0000C
ANALYSIS:
induced emf depends on the velocity of plasma E=V.B
This is the well known Hall effect observed in solids and liquids, and also in gases under suitable conditions.
The output power per unit volume of such a system is given by
is the electrical conductivity of the gas and K is the load factor.
The load factor K is a measure of the emf E due to the flow of current through the circuit and is given by
K=
The recommended value of K=1/2 so the power output P per unit volume is given by
p= /4
ELECTRODE CONFIGURATION OF MHD GENERATOR
1. Segmented electrode configuration
2. Continuous electrode configuration
3.Hall generator
1. Segmented electrode configuration
electrode segments are separated by insulator segments
no current flowing in the direction
The electric field vector has a component both along the channel and across the channel.
2. Continuous electrode configuration
electric field is across the channel only
but he current has components along the channel as well as across it.
In this case the hall angle is minimized and thus the losses are reduced
3.Hall generator
the electrodes wrap up the channel all the way in segment.
The electric field becomes parallel to the channel axis
there cannot be any potential difference across the channel.
TYPES OF MHD GENERATORS
Open cycle MHD
Closed cycle MHD
Liquid Metal- Closed cycle MHD
Open cycle MHD
Closed cycle MHD
Closed cycle MHD with Liquid Metal
ADVANTAGES OF MHD GENERATOR
Since high temperatures are involved, operational efficiency is high
No moving part, so more reliable
no limitation to the size of the duct
Ability of reaching the full power level instantly
Conceptually these generators are very simpler.
The walls can be cooled below temperature of working gas
The more efficient heat utilization reduces the amount of heat discharged to environment and thus the cooling water requirements are reduced.
The capital costs of the MHD plants are low
The overall costs of MHD power generation are estimated to be lower (20%) than those of conventional power plants
construction is not limited by the working temperature of the gas inside the duct
Direct conversion of heat into electrical energy results in the elimination of gas turbine and both the boiler
The closed cycle system produces power, free of pollution
The size of the plant is considerably smaller than conventional fossil fuel plants
It can be started and put on the line within few seconds. It provides almost instantaneous standby power.
It can be used most economically as peak load plant
ACHIEVEMENTS
A 5-15 MW thermal input pilot plant is being set up in India at Tiruchirapalli. This plant uses fluidized bed combustion
A major effort was made in U.S.A use MHD as the conversion system in a nuclear electrical system for space craft.
The Department of Science and Technology of government of India has sponsored research and development programmes on coal based MHD power generation.
MHD conversion has also been considered for ship propulsion
PROBLEMS ENCOUNTERED IN DESIGN OF MHD
Seed material potassium attacks insulating materials and make them conducting
Electrode materials are chemically eroded by combustion of gases
Although the overall thermal efficiency is 60% against 40% for conventional thermal plant, additional investment in the magnet, generator, duct, compressors, scrubbers, seed recovery plant and DC to AC converters may increase the plant cost and it may be much higher than conventional plant.
Most of the problems are related to material problems caused by high temperature and highly corrosive and abrasive environment
Additional pictures
APPLICATIONS
1.) Power generation in space craft
2.) Hypersonic wind tunnel experiments
CONCLUSION
The threat of disappearing of the fossil fuels within few decades compel the human beings to search for new energy sources will last for a longer time. Extensive research is going on in different countries through out the world to find out the new resources to replace the conventional fossil one.
With the present research and development programmers, the non-conventional power resources play an important role in the power industry
The magneto hydro dynamic power generation is one of the examples of a new unique method of generation of electricity.
This power resource play a minor role presently and its use on a vast scale is yet to be confirmed as it is in its childhood stage. Man being optimistic should not leave the hopes on the success of this MHD generator as the technology took the man to moon which was a dream long time back, the same technology will help the human being to survive from the present crisis of power shortage.
MS. P. SAI REVATHI
ppt.ppt (Size: 3.21 MB / Downloads: 252)
ABSTRACT
The electricity requirements of the world including India are increasing at alarming
It is also now widely recognized that the fossil fuels and other conventional resources, presently being used for generation of electrical energy, ..
MAGNETO HYDRO DYNAMIC (MHD) power generation is a new unique method of power generation.
Michael Faraday (1832) conducted MHD experiments
The first successful power generation experiment, developed by Richard Rosa in 1959, generated 10 kW with a timber walled channel
In 1972 in Moscow, a large experimental facility, the "U-25," used a 250 MW natural gas combustor and generated 20 MW
When an electrical conductor is moved so as to cut lines of magnetic induction, charged particles in the conductor experience a force
. The negative charges tend to move in one direction, and the positive charges in the opposite direction.
In conventional steam power plants, the heat released by the fuel is converted into rotational mechanical energy by means of a thermo cycle and the mechanical energy is then used to drive the electric generator
Thus two stages of energy conversion
electrical energy is directly generated from hot combustion gases produced by the combustion of fuel without moving part
MHD generator is heat engine operating on a turbine cycle and transforming the internal energy of gas directly into electrical energy.
PRINCIPLE OF WORKING OF AN MHD GENERATOR…
The basic principle of MHD is just similar to dynamo except that the solid conductor of high electrical conductivity is replaced by a gas with comparatively low value of electrical conductivity
If the gas is heated to high temperature it gets converted into plasma and plasma is conductor of electricity.
HOW AN MHD GENERATOR WORKS?
electrically conducting gas at a very high temperature is passed at high velocity through a strong magnetic field
at right angles to the direction of flow
There by generating electrical energy. The electrical energy is then collected from stationary electrodes placed on the opposite sides of the channel
The current so obtained is direct current which can be converted into ac by an inverter.
On heating of a gas, the outer electrons escape out from its atoms or molecules.
The particles acquire an electric charge and the gases passes into the state of plasma
Air becomes highly ionized at temperatures of 5,0000 to 6,0000C
ANALYSIS:
induced emf depends on the velocity of plasma E=V.B
This is the well known Hall effect observed in solids and liquids, and also in gases under suitable conditions.
The output power per unit volume of such a system is given by
is the electrical conductivity of the gas and K is the load factor.
The load factor K is a measure of the emf E due to the flow of current through the circuit and is given by
K=
The recommended value of K=1/2 so the power output P per unit volume is given by
p= /4
ELECTRODE CONFIGURATION OF MHD GENERATOR
1. Segmented electrode configuration
2. Continuous electrode configuration
3.Hall generator
1. Segmented electrode configuration
electrode segments are separated by insulator segments
no current flowing in the direction
The electric field vector has a component both along the channel and across the channel.
2. Continuous electrode configuration
electric field is across the channel only
but he current has components along the channel as well as across it.
In this case the hall angle is minimized and thus the losses are reduced
3.Hall generator
the electrodes wrap up the channel all the way in segment.
The electric field becomes parallel to the channel axis
there cannot be any potential difference across the channel.
TYPES OF MHD GENERATORS
Open cycle MHD
Closed cycle MHD
Liquid Metal- Closed cycle MHD
Open cycle MHD
Closed cycle MHD
Closed cycle MHD with Liquid Metal
ADVANTAGES OF MHD GENERATOR
Since high temperatures are involved, operational efficiency is high
No moving part, so more reliable
no limitation to the size of the duct
Ability of reaching the full power level instantly
Conceptually these generators are very simpler.
The walls can be cooled below temperature of working gas
The more efficient heat utilization reduces the amount of heat discharged to environment and thus the cooling water requirements are reduced.
The capital costs of the MHD plants are low
The overall costs of MHD power generation are estimated to be lower (20%) than those of conventional power plants
construction is not limited by the working temperature of the gas inside the duct
Direct conversion of heat into electrical energy results in the elimination of gas turbine and both the boiler
The closed cycle system produces power, free of pollution
The size of the plant is considerably smaller than conventional fossil fuel plants
It can be started and put on the line within few seconds. It provides almost instantaneous standby power.
It can be used most economically as peak load plant
ACHIEVEMENTS
A 5-15 MW thermal input pilot plant is being set up in India at Tiruchirapalli. This plant uses fluidized bed combustion
A major effort was made in U.S.A use MHD as the conversion system in a nuclear electrical system for space craft.
The Department of Science and Technology of government of India has sponsored research and development programmes on coal based MHD power generation.
MHD conversion has also been considered for ship propulsion
PROBLEMS ENCOUNTERED IN DESIGN OF MHD
Seed material potassium attacks insulating materials and make them conducting
Electrode materials are chemically eroded by combustion of gases
Although the overall thermal efficiency is 60% against 40% for conventional thermal plant, additional investment in the magnet, generator, duct, compressors, scrubbers, seed recovery plant and DC to AC converters may increase the plant cost and it may be much higher than conventional plant.
Most of the problems are related to material problems caused by high temperature and highly corrosive and abrasive environment
Additional pictures
APPLICATIONS
1.) Power generation in space craft
2.) Hypersonic wind tunnel experiments
CONCLUSION
The threat of disappearing of the fossil fuels within few decades compel the human beings to search for new energy sources will last for a longer time. Extensive research is going on in different countries through out the world to find out the new resources to replace the conventional fossil one.
With the present research and development programmers, the non-conventional power resources play an important role in the power industry
The magneto hydro dynamic power generation is one of the examples of a new unique method of generation of electricity.
This power resource play a minor role presently and its use on a vast scale is yet to be confirmed as it is in its childhood stage. Man being optimistic should not leave the hopes on the success of this MHD generator as the technology took the man to moon which was a dream long time back, the same technology will help the human being to survive from the present crisis of power shortage.