In this article, I will share with you the components and working principles of cooling ponds and cooling towers.
Cooling of the condensate from the condenser is very essential since the water has to be reused in the cooling with the condenser.
The amount of cooling water used in a condenser is significant and there is a need to use the condensate from the condenser.
About a million gallons of water is needed per hour to aid in the cooling process of the condenser.
So, you now see the need for the reuse of the condensate in the condenser.
The condensate can’t be reused in the condenser again until it’s cooled and that is when the cooling ponds and cooling towers come in.
The cooling ponds and cooling towers facilitate the cooling of the condensate from the condenser.
Cooling ponds components and working principle;
From the word pond, the cooling pond is just an area dug deep and wide enough built to accommodate water from the condenser and facilitate its cooling.
The cooling ponds also do the function of storing the water that is going to be reused in the condenser.
They provide cooling of the condensate from the condenser mainly by evaporation and convection.
One of the components of the cooling ponds is the spray nozzles that are used to spray the condensate from the condenser into the cooling pond.
These nozzles increase the cooling rate of the condensate as it sprays and falls into the cooling ponds.
They discharge the water from the condenser under high pressure which also increases the distribution area of water as it falls into the cooling ponds.
Makeup water pump; this pump is needed to pump cold water into the cooling pond to replace water lost through evaporation and wind.
The cold water pump into the cooling pond also aids in the cooling of the condensate from the condenser.
Circulating pump; this pump is used to supply water to supply cold water from the cooling pond to the condenser
Working principle of cooling ponds;
Cooling ponds cool warm water from the condensate by the principle of evaporation and convection.
The condensate from the condenser is sprayed through nozzles over a large area of the pond, and the speed at which the condensate falls from the nozzles enables the water to interact with atmospheric air and be cooled by evaporation and convection.
Since a lot of water is lost through evaporation and windage makeup water is needed to replace the lost water thus that is where the make-up water pump is used.
Factors that increase the cooling efficiency of the cooling ponds;
For the cooling ponds to cool the condensate effectively these are some of the factors that the cooling ponds should meet;
The area and depth of the cooling pond; area of the cooling pond should be large enough to increase the surface area of evaporation. It should also be deep enough to accommodate more water from the condenser and the make-up water.
The cooling ponds being deep enough also aids in the cooling of the water since there will be enough air circulation within the pond and this will increase the efficiency of cooling.
The temperature of the water entering the pond; temperature of the water entering the pond is also one of the factors that affect the cooling efficiency of the cooling ponds.
If the condensate entering the cooling ponds is of high temperature then this means that the cooling rate of the water will be lower.
But if the condensate entering the cooling pond is of a lower temperature, the cooling rate of the condensate will be high.
The make-up water entering the cooling pond should also be cold to facilitate the cooling of warm water from the condenser.
Atmospheric temperature; the atmospheric temperature is also one of the factors that influence the cooling efficiency of the cooling ponds.
If the atmospheric temperature is too high this increase the efficiency of the cooling ponds since the evaporation rate will be higher.
But if the atmospheric temperature is lower, this will lower the cooling rate of the cooling pond since the rate of heat dissipation from the pond to the environment will be lower.
Wind velocity; velocity also affects the cooling rate of the cooling ponds.
When the warm water is being sprayed from the nozzles its cooling rate will be higher if there is a higher velocity of the wind.
The air stream from the wind will facilitate the cooling rate by increasing the evaporation rate.
A lower velocity of the wind will result in to decrease in the cooling rate of the condensate water.
The main disadvantage of high-velocity wind is that it leads to a large amount of water wastage by windage.
Relative humidity; the amount of moisture in the atmosphere also plays a big part when it comes to the cooling efficiency of the cooling ponds.
If the relative humidity is higher then there will be less evaporation taking place and this will decrease the cooling rate of the warm water from the condenser.
Lower relative humidity will increase the evaporation of water and this will result in to increase in the cooling efficiency of the pond.
The shape and size of spraying nozzles; the shape and size of the spraying nozzles also facilitate the cooling efficiency of the cooling ponds.
If the spray nozzle is larger then the volume of condensate water discharged from the condenser will be higher, the pressure will increase and this will lead to good water distribution over the pond which will eventually increase the rate of heat dissipation.
Smaller nozzles have a lower volume discharge and offer lower pressure and this will result in a lower rate of heat dissipation from the condensate being sprayed over the cooling pond.
The shapes of the spray nozzle also play a big part when it comes to the heat dissipation of the condensate.
Hollow-cones nozzle is the best shape when compared to saddle-shaped nozzle since they spray water in a large area and its penetration is the best.
Cooling Towers.
Cooling towers also aid in cooling the condensate from the condenser.
They are improved in their designs so that they provide efficient cooling more that the one provided by the cooling ponds.
They are called cooling towers because they have a built structure that is tall and stable that can handle the air used in cooling the condensate.
These built structures where the air is driven in either by a fan or natural flow of air is conical.
This allows the higher intake of air from the bottom of the tower and when the air exits the tower is discharged from the tower under high pressure due to the small opening of the tower at the top.
These are the different types of cooling towers used in cooling the condensate;
- Atmospheric cooling tower.
- Natural draught cooling tower.
- Forced or induced draught cooling tower.
1. Atmospheric cooling tower.
An atmospheric cooling tower uses air from the atmosphere to cool the condensate from the condenser.
It contains louvers where the warm water from the condenser falls and flows to the catch basin.
This is how an atmospheric cooling tower works; the condensate from the condenser is made to fall on the louvers that are arranged in series.
The louvers allow water to fall and splash as the air passes through the louvers to cool the condensate.
By the time the condensate reaches the catch basin, it’s effectively cooled by the stream of air passing through the louvers and the heat lost by conduction on the louvers.
As the condensate flows through these louvers a stream of atmospheric air that passes through the louvers aid in cooling the condensate.
The disadvantage of using such a cooling tower is that they provide lower cooling capacity and this makes them unsuitable for large plants.
They are being used in small power plants like the diesel power plant.
2. Natural draught cooling tower.
A natural draught cooling tower is kinda similar to an atmospheric cooling tower except for the fact that the condensate from the condenser is sprayed in the cooling tower.
I will share with you how it works but for now, there are some details about this cooling tower that you have to know.
A natural draught cooling towers can be made of timber, concrete or steel depending on the requirements of the design.
It contains a sprinkling unit that sprays the condensate from the condenser to be cooled in the cooling tower.
A pump is used to pump the condensate from the condenser so that it’s sprayed under higher pressure, this increases the cooling rate of the condensate.
A makeup water pump is also provided to aid in replacing the water lost through evaporation.
The air used in cooling the condensate is driven by a natural means, there are opening provided at the base of the tower that allows air to enter the tower.
This cooling tower should be placed in a well-ventilated space to allow the free flow of air within the cooling towers.
This is how a natural draught cooling tower works; the condensate from the condenser is pumped to the ring troughs nozzles with are situated near the bottom of the tower.
The ring troughs are connected to the pipe that takes water from the condenser and are raised in the cooling tower.
This is to allow a considerable height that the condensate will fall from to maximize the interaction of air and the condensate.
As the warm water from the condenser is sprayed through the nozzles air enters the tower via the openings that are provided at the bottom of the tower.
The air rises as the condensate falls from the ring troughs nozzles situated a little higher in the cooling tower.
As the cold air rises it comes in contact with falling condensate that is in form of droplets and it takes up the heat from it and this facilitates the cooling.
The air exits the cooling tower through the top opening of the tower as hot air.
Makeup water is added into the catch basin to replace the amount of water that was lost through evaporation.
Towers that are needed to withstand large air pressure are made up of concrete.
The advantages of using this tower are that it has a low cost of maintenance and they have a large capacity.
3. Forced draught cooling tower.
The force draught cooling tower uses a fan to cool the condensate from the condenser.
A fan that provides air to cool the condensate is installed at the bottom of the tower.
This is how the force draught cooling tower works; the condensate from the condenser is sprayed in the cooling towers via the spray nozzles. The warm water falls in form of droplets on the filling stats that are provided in the cooling tower.
The fan forces air into the cooling tower that rises cooling the water on the filling slats and the one falling from the spray nozzles.
The filling slats are provided to increase the surface area of cooling when the water falls on them.
This ensures that there is efficient cooling of the condensate.
The hot air exits the cooling tower from the top opening provided by the tower.
Factors affecting the cooling of condensate in a cooling tower;
These are some of the factors that affect the cooling efficiency of the cooling towers;
Size and height of the cooling tower; a big tower provides a higher cooling rate than a small tower.
The big tower will provide a large area where the condensate will interact with the air thus maximizing the cooling efficiency.
A tall tower will also contribute to the maximum cooling of the condensate since the cold air will be used to the maximum as it raises the tower.
The velocity of air entering the cooling tower; an air of high velocity entering the tower will provide a higher cooling rate of the condensate than air flowing into the tower with a lower velocity.
The temperature of the condensate; if the temperature of the water coming out of the condenser is higher the cooling rate of the water will be lower compared to when the condensate has a lower temperature.
The temperature of the air entering the cooling tower; if the temperature of the air entering the cooling tower is higher the cooling rate of the condensate will be lower.
But if the air entering the cooling tower is of a low temperature the cooling rate of the condensate from the condenser will be higher.
The humidity of air; the air entering the cooling tower should be low humidity to allow maximum cooling of the condensate.
Also, the relative humidity of the atmosphere plays a big part when it comes to the cooling efficiency of the towers.
If the atmosphere has a higher relative humidity this means evaporation will be at the minimum and cooling the condensate will be very ineffective.
Accessibility of air to various parts of the cooling tower; if the air entering the tower is evenly distributed within the tower this will allow maximum cooling of the warm water from the condenser.
But if some parts of the cooling tower can’t access the air entering then the cooling rate of the condensate will be lower.
Thanks for reading, if you have any questions about the cooling towers you can leave your comment. See you in my next article.
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