What is a forced draft system?
Forced draft: When air or flue gases are maintained above atmospheric pressure. Normally it is done with the help of a forced draft fan. Induced draft: When air or flue gases flow under the effect of a gradually decreasing pressure below atmospheric pressure. Draft is said to be zero in this system.
What is the reason for poor performance of forced draft cooling tower?
of water. For atmospheric and natural draft towers, the economics of pumping water are still very important. This means that the ground area must be so selected as to keep the height down, while not dropping the unit rates so low that performance becomes poor.
Which tower is most efficient forced draft or induced draft Why?
Counterflow (induced draft) systems are considered the most efficient of the two. Crossflow (forced draft) towers distribute hot water perpendicularly to the air flow, while counterflow towers distribute hot water directly into the air flow.
What is the advantage of forced draft cooling tower?
Comparison Between Forced Draft And Induced Draft Cooling Tower
| Advantages | Disadvantages |
|---|---|
| Forced draft – Axial fan | |
| Low absorbed capacity Easy maintenance Dry air stream drive | Higher noise level |
| Forced draft – Centrifugal fan | |
| Low noise level Easy maintenance Dry air stream drive | Higher absorbed capacity |
What is the difference between forced and induced draft?
Forced-draft fans focus the pressure and volume at the outlet of the fan to push air through a system, creating positive air pressure. Industrial induced draft fans operate by focusing the pressure and volume at the inlet of the fan to pull air through a system.
What does induced draft mean?
: a draft produced by a suction steam jet or fan on the stack side of a furnace.
How does an induced draft fan work?
An induced-draft burner uses a blower to pull air into the burner, and through the combustion chamber and heat exchanger. The fan then pushes the flue gases out through the vent. This creates negative pressure in the furnace, and may create positive or negative pressure in the venting systems.
How does a natural draft work?
Natural Draft is thermal draft. It occurs when heated gases expand. A given volume of hot gas will weigh less than an equal volume of the same gas at a cool temperature. Currential Draft occurs when high winds or air currents across the top of a chimney create a suction in the stack and draw gases up.
Why we prefer artificial Draught in modern boilers?
In modern commercial boilers, more value of draught is required to increase the heat transfer co- efficient and hence the thermal efficiency. So, artificial draught is must to use to overcome the flow resistance offered by large flue passages.
What are the limitations of chimney Draught?
LIMITATIONS : (1) The maximum pressure available for producing natural draught by chimney is hardly 10 to 20 mm of water under the normal atmospheric and flue gas temperatures. Draught is the pressure difference which causes a flow of air or gases from one point to another point in the boiler system.
What are the advantages of forced Draught system?
Advantages of Artificial or Mechanical Draught It increases the rate of combustion by which low-grade fuel can also be used. It reduces the smoke level and increases the heat transfer co-efficient no flue gases side thus increases the thermal efficiency of the boiler.
What is the function of boiler chimney What are the limitations of chimney Draught?
air for combustion and removes the burnt products from the system. flow of hot gases through the boiler, economizer, preheater and chimney require a difference of pressure. air and discharging the gases through the chimney to atmosphere is known as draught.
Is a Draught?
The noun draught is pronounced exactly like draft, and it also shares most of the same meanings. A cold burst of wind, a swig or a serving of a drink, the act of pulling a heavy load, and the depth of a ship below the surface of the water: each of these can be called a draught.
What is meant by natural Draught?
Also found in: Wikipedia. the draught produced by the atmosphere flowing, by its own weight, into a chimney wherein the air is rarefied by heat.