Thermal Power Station superheater and reheater coil energy saving
ISO 3834 Certificate
Boiler Superheater and Reheater in Thermal power plant
1. A thermal power station is a power station in which heat energy
is converted to electric power. In most of the places in the world
the turbine is steam-driven.
2. Water is heated,turns into steam and spins a steam turbine which
drives an electrical generator. After it passes through the
turbine, the steam is condensed in a condenser and recycled to
where it was heated; this is known as a rankine cycle.
3. The greatest variation in the design of thermal power stations
is due to the different heat sources; fossil fuel dominates here,
although nuclear heat enery; solar heat energy, biofuels and waste
incineration are also use.
4. Some prefer to use the term energy center because such
facilities convert forms of heat energy into electrical energy.
5. Certain thermal power stations are also designed to produce heat
energy for industrial purpose, or district heating, or desalination
of water, inaddition to generating electrical power.
Superheater and reheater Description
1. Superheaters and reheaters in utility boilers increase the
temperature of saturated or near-saturated steam in order to
increase the thermodynamic efficiency of the power cycle or to
provide the desired process conditions.
2. In general terms, they are simple single-phase heat exchangers
with steam flowing inside the tubes and flue gas passing outside
the tubes, generally in crossflow.
3.The key criteria in the design of these heat exchangers are:
- Limiting tube metal temperatures to below acceptable values to meet
allowable stress and corrosion - erosion limits
- Controlling steam outlet temperatures within the specified level
over the range of boiler operationg conditions
- Maintaining pressure drop on the steam side within allowable
limits(especially for high-pressure subcritical boilers)
What is use of a reheater in a thermal power plant?
1. High pressure steam is expanded in turbine, moisture content of
exhaust steam increases, which creates problem at exit end blades.
2. So reheat type turbine is most commonly used for large capacity
turbine using high pressure steam. Steam after expanding at HP
Turbine is sent to boiler for further heat addition or reheat.
3. This steam is called as cold reheat. Cold reheat is heated at
reheat is then sent to IP/LP Turbine where it expands further.
4. Single and double reheat turbines are commonly used for power
generation.
Differences
| Type | Advantages | Disadvantages | Supporting method |
| Pendant-type | 1.Firm structural support | 1. Flow blockage by condensed steam 2. Needs slow restart to purge
the water that accumulates in the bottom. | supported from above |
| Inverted-type | 1.Proper drainage of the condensed steam | 1. Lack the structural rigidity, especially in high speed gas flow | Supported from below |
| Horizontal -type | 1. Proper drainage 2. Good structural rigidity. | 1. They do not view the flam directly so they are mainly from the
convective type | Usually supported in the vertical gas ducts parallel to the main
furnace. |
Tube connection
