5 replies to this topic

[mahnaya]

Dear All,

I have to solve the issue, please guide me
"Plate heat exchanger is to cool circulating fresh water from 48.7 deg C to 40.5 with sea water of 37 deg C inlet to cooler and out is received 45.8 deg C. please guide me for using Cooling Tower arrangement instead of sea water, This cooling tower(existing) is design to cool down 50 deg C water to 40 deg C. Is this proposed arrangement will be feseable, and how to check step wise?(flow rates and pressures are same for capacity/ requirement)"

[Art Montemayor]

Mahnaya:

Please don’t be lazy and simply quote sections of the written problem you were given to resolve. What happens is what has resulted in your case:

• You state you are cooling fresh water with seawater; then you mention a cooling tower. This is very confusing and makes no sense as you have tried to take a stated problem and edited it ineptly to something that is difficult to interpret.
• You don’t state what, specifically, you want to do. You ask for guidance and fail to tell us what direction or what you specifically want to do. You are like a stranger in a land who asks for directions, but doesn’t state where he wants to go.
• What do you want to check? This, again fails to state what your problem is.

What you (and all other students who think a minimum of work input in enough to obtain an answer) should do is to maximize your own effort in stating the problem before you in clear, concise, and accurate language. Do not rely on simply copying your problem and “pasting” it in your thread, then walking away from it expecting to receive the magic answer within a day or two. Our Forum doesn’t do homework. We will help you, but you must contribute the largest share of the workload: the accurate and specific explanation of what the problem is.

If you follow my recommendations you will find that in the process of working and struggling to define what the problem is and how to best communicate it, you will start to understand better what the problem really is and possibly even discover that you have total grasp of the problem and possible even some answers. These possible answers and any doubts regarding what you interpret can be handled easily here in the Forum. By resorting to this method you will discover that you can, indeed, not only understand what the problem is but also possibly resolve it on your own. Confidence and self-esteem will follow on future problems.

Please explain your problem in a concise, detailed and accurate manner and what you have done so far to try to arrive at a solution.

Await your reply.

[mahnaya]

Dear Art Montemayor

Thank you very much for such a nice direction, one can follow to get direction.
Which I understand, I tried to sum up my statement in a small and simple words, which created confusion, I appreciate and thank full that you are the only one out of 62 who didn’t just visited, and closed by thinking ”fool Post”. Sorry, if you find difficulty, because I am not so good in English and newly entered in process engineering field. Let me explain,
We are operating with closed loop cooling water circuit. Temperature of closed loop circuit (in 40.5 out 48.7 deg C) is being controlled with once through sea water supply 37 and once through return 45.8 deg C). in absence of sea water (during TA), Package cooling tower is relocated (data sheet shows supply temp. 40 return 50 and capacity 350m3/hr).
Now go back to Plate exchanger, 8 exchangers in parallel (each 2000m3/hr capacity), each can be isolated, are designed to run this circulation. My question is “ Whether one plate exchanger will work efficiently with relocated cooling tower for cooling 340 m3/hr closed circuit flow (for few condensers)”
Once again sorry for inconvenience.

Regards,
Mahnaya

[djack77494]

Dear Art Montemayor

Thank you very much for such a nice direction, one can follow to get direction.
Which I understand, I tried to sum up my statement in a small and simple words, which created confusion, I appreciate and thank full that you are the only one out of 62 who didn't just visited, and closed by thinking "fool Post". Sorry, if you find difficulty, because I am not so good in English and newly entered in process engineering field. Let me explain,
We are operating with closed loop cooling water circuit. Temperature of closed loop circuit (in 40.5 out 48.7 deg C) is being controlled with once through sea water supply 37 and once through return 45.8 deg C). in absence of sea water (during TA), Package cooling tower is relocated (data sheet shows supply temp. 40 return 50 and capacity 350m3/hr).
Now go back to Plate exchanger, 8 exchangers in parallel (each 2000m3/hr capacity), each can be isolated, are designed to run this circulation. My question is " Whether one plate exchanger will work efficiently with relocated cooling tower for cooling 340 m3/hr closed circuit flow (for few condensers)"

mahnaya,
I also am having difficulty in trying to understand what it is you seek. My best guess as to what you are saying is:
1) You have a once through sea water system that supplies water at 37C to eight plate heat exchangers. Return temperature is 45.8C.
2) Circulating cooling water flows through the other side of the plate exchangers. Supply temperature is 40.5C and return temperature is 48.7C.
3) You also have available, but not in use, a package cooling tower that can cool 350m3/hr of cooling water from 50C to 40C.
4) Based on the above, if your sea water system is down all 8 of your plate exchangers would be idle, so I do not understand why you are asking about using one of the plate exchangers.
5) The question, it would seem to me, should be whether or not you can bring the package cooling tower online to use during your TA.
6) The answer to 5 seems to be "No" because there appears to be an extreme mismatch between your needs (2000m3/hr x 8) and what the cooling tower can provide (350m3/hr).

The answer, of course, could be totally different if my understanding is not correct. If that is the case, please try to clarify your situation.
Doug

[mahnaya]

5) The question, it would seem to me, should be whether or not you can bring the package cooling tower online to use during your TA.
6) The answer to 5 seems to be "No" because there appears to be an extreme mismatch between your needs (2000m3/hr x 8) and what the cooling tower can provide (350m3/hr).


Dear Doug,
You understand 100% correct from pt. 1 to 4, I have to clear final pt. One exchanger is being considered to run with package cooling tower, while the other side will be operative for very low load, ~341 m3/hr (only critical equipments), with same circulating pumps, Is it possible? and how to check?

Regards,
Musharraf

[djack77494]

You understand 100% correct from pt. 1 to 4, I have to clear final pt. One exchanger is being considered to run with package cooling tower, while the other side will be operative for very low load, ~341 m3/hr (only critical equipments), with same circulating pumps, Is it possible? and how to check?

Musharraf,
I am at least as confused as I was before. If my understanding of points 1-4 was correct, then you have described an indirect cooling water system. Sea water cools cooling water - cooling water is the utility of interest and is presumably accepting rejected process heat. The plate exchangers are the equipment in common between the sea water and cooling water systems, and do not participate (directly) in process heat removal.

My understanding is that the sea water system will be totally down. So there will be no fluid on one side of any of the eight plate exchangers. So why would they be in service; what would they be doing? Hopefully you can understand the area of my confusion and straighten me out. Initially, I had thought you sought to replace one of the eight exchangers with the package cooling tower, but your latest post suggests otherwise, leaving me in my confused state.
Regards,
Doug