Cooling tower design, any experts?

[Finfan]

Hi everyone, I work on an oil refinery and have recently been asked to evaluate and improve the cooling water system on our gas oil Hydrodesulphurisation plant, I haven't had much to do with cooling water systems but have quickly got myself up to speed.
In order to evaluate the current towers as a first step I will compare heat load and cooling range with the manufacturers specs, problem is we have 2 tower units of which both have seperate returns from the process at different temperatures and the water falls into a common pond beneath the towers so is the only way for me to gather data to take manual temperature readings of the water leaving each unit? Or is there a way to evaluate heat load and cooling range using the common cooling water pond outlet temperature?
I have all other info flows, temperatures etc and can calculate the heat load going to each seperate unit but with the common pond below I cannot get the water temperature leaving each tower unit (should I just do this manually?)
Sorry for the long winded question but I just can't get my head round this (more of a chemistry man) thanks very much for any help.

Steve

 

[Harold53]

Finfan :
You should get a copy of the ATP 105 issued by the Cooling Tower Institute. There are the basis for the evaluation of a cooling tower, but anyway you will have some problems because of your installation.

 

[CoCooler]

You must know that we can evaluate the heat evacuated from a wet cooling tower by two mays. the first from the way "water" the second from "air". Try to see the merkel's equation it's the best way to understood very well how it can help you resolving your problem.In the case of a dry cooling tower the problem is very simple to get the temperatures. The best approximation is to have the temperature by a simple thermometer, if the temperature is less than 40 °C, and than a simple conduction calculation.