Cooling Tower Query 1

[Yomahuta]

I am a fresh engineer at a thermal power station, and I have noted that the range (delta of inlet and outlet temperatures of water) of cooling tower varies on different days of month i.e. sometimes the range is 3 degrees C and sometimes it is 7 degrees C. What could be the reason behind this? The condenser receives steam at almost constant 44-46 degrees C steam after last stage of turbine. But the inlet water of circulating water pump entering the condenser is different at times. Anyone can link me to any relevant doc?

 

[RVAmeche]

Does this help you?

https://spxcooling.com//wp-content/uploads/TR-016.pdf

 

[EdStainless]

Use your system data to track this.
You will want actual steam flow, cond in and out temps, ambient temp, ambient humidity (if this is a wet tower), and of course tower in and out.
Yes, some of these temps should be the same, but it is good to check if your DCS reports them as being the same (cond out and tower in).
Then start applying the basic thermal performance math. Just build a model in excel.
Your system will not meet the theoretical calculations, but there will be an offset.
This offset should stay constant.

I used to do this with condensers all of the time.
Using real data usually landed within 10% of the design calculations.
By tracking this they could tell what it was deviating more and they knew that either something wasn't working correctly or there were fouling issues.


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P.E. Metallurgy, consulting work welcomed

 

[Yomahuta]

@RVAmech:

Thanks for the reply, so it means if at times the demand is less or plant is at low power, the range will be high cause of more heat rejection in condenser and this can even become larger in winters due to decreased wet bulb temperatures right?

 

[Yomahuta]

@EDStainless:

Thanks for the reply. I plan on making one model in excel. Got any sample spreadsheets to start with?

 

[EdStainless]

I have stayed away from cooling towers.
If you read up at the cooling tower institute, you will find that very few new towers are performance tested (maybe 1/3).
And of those half do not meet the design criteria.
But yes, changes in weather and plant load will both impact the thermal performance.

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P.E. Metallurgy, consulting work welcomed

 

[pierreick]

Hi,
Probably good to study the document attached.
Pierre

 

[LittleInch]

Put simply, if your process conditions change, e.g. amount of steam, air temperature and humidity and flow of cooling water, then the delta T will change also.

By how much depends on how those different parameters interact with each other.

There's not a simple one line answer to this.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Yomahuta]

I got it. Thanks to all of you!

 

[bimr]

Cooling tower performance is tied to ambient wet bulb conditions (weather related). Higher wet bulb temperatures occur in the summer when higher ambient and relative humidity occurs. Initial system design and proper system maintenance are critical to be certain the cooling tower is providing the desired cooling.

The local power company here installed supplemental cooling towers that are only used on hot summer days so that they could generate more power on those hot days.

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