Cooling high-horsepower motors with water cooled heat exchangers 1

[NISHANT BHARDWAJ]

We manufactures heat exchanger & i have a chance to get a very big project in one of the prominent oil company in India.
Below (in blue fonts) is the mail of a client i got in today morning. Please help me to understsnd what exactly they want from us & how we can help them. It would be a very great help if you'll reply us with some solution.
CLIENT MAIL
"Sir

As per discussion held with you on phone regarding “Design, Supply & Installation of water cooling heat exchanger for 1820 KW CW Pump Motor”. We are looking after for the best solution to overcome the high winding temperature rise of the CW Pump Motors.



Most of the motors are running at a winding temperature between 135 to 148 deg C (with existing air heat exchanger) which is much higher than the recommended temperature i.e. 120 deg C. It is requested to discuss with your design team and provide a budgetory offer for the “Design, Supply & Installation of water cooling heat exchanger for 1820 KW CW Pump Motor” along with the following detail:-

1. Quantity of cooling water required.

2. Pressure of cooling water required.

3. Protection for water leakage or water leakage detection sensor, if any.

4. Size of the piping required for inlet and outlet.


Thanks.

 

[edison123]

The starting point would be how many KW they want to dissipate.

Muthu

http://www.edison.co.in

 

[ashtree]

You also need inmformation like:
1) What is the quality of the "cold" water stream. This may impact on materials of construction, style of heat exchanger, any pre-treatment requirements. It may also impact on the quantity of water that will be used in and by the system.
2) What is the temperature of stream. This will have a big impact on the type and style of the heat exchanger and size.
3) Are there restrictions on footprint.
4) How is the heat to be dissapated from the water eg: cooling tower, released to the environment. This could have a huge impact on the cost and design of the system.

If you are sitting in a heat exchganger manufacturing company, someone there should already know this.


Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[RRaghunath]

The problem seems to be high winding temperature of the existing 1820kW CW pump motors. No mention what is causing the temperature to exceed the limit of 120degC. It could be
* simple fouling of heat exchanger tubes (air-to-air type I suppose) or it can be that
* the shaft mounted fan has some issues and unable to deliver air in adequate quantity at rated pressure.
It seems there are no. of such 820kW motors in operation and they are planning common air-to-water heat exchanger to cool the air that enters individual motor (air-to-air) heat exchanger. This suggests that the pumps are in confined space with inlet air temperature higher than the design rating.
Hope the above understanding is of help. All the best!

 

[NISHANT BHARDWAJ]

Thanks R Raghunath for your reply.
Temperature is rising due to the high environment temperature in Delhi. Client is asking us to replace their air to air cooled heat exchanger to water cooled heat exchanger which has much more efficiency than air to air cooled. We need to set cooling tower for water supply.
I have some understanding in to it but picture is not much clear in my mind. There are numbers of cw motor placed in oil plant with air to air cooled heat exchanger. If we successfully implant water to air cooled heat exchanger & results come in our favor than we might get order to replace all their heat exchanger with water to air cooled heat exchanger.

I am not a technical person & not have much knowledge of physics but we have a workshop where we manufacture shell & tube heat exchanger. So you must have understood what are the problems i am facing through.
Can you help us in this project. I guess you have better understanding in this field. Can you provide me your email id?
Please go through the attached drawing of their existing motor with heat exchanger for better understanding.
Thank you.

 

[Skogsgurra]

A few simple questions:
1. Is the motor overloaded? I may be tempting to "adjust" the overload protection and then find out that motor windings get hot. If that is the case, I'm not so sure that more cooling helps in the long run. There are always hot spots where the increased cooling doesn't really help.
2. Is it in southern India? I had problems with ambient temperature there. Made bearings run extremely hot. And windings, too.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[Skogsgurra]

Sorry, got a long phone call before I hit "Submit" button. RR seems to have answered your questions in the meantime. Delhi shouldn't be too hot - or is it? Never been there.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[crshears]

Pretty well all of the pertinent questions needing answers have already been posted by others, so I won't repeat them.

However:

We have a workshop where we manufacture shell & tube heat exchanger.

That being the case, how can your firm do this without having either in-house or contracted support to answer these types of technical questions?

Maybe it is just me, but I would expect you to have access to better local resources than to have to pose such questions here.



CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[RRaghunath]

Nishant Bharadwaj,
The motor is Crompton Greaves make with CACA cooling. CACA stands for "Closed Air Circuit Air". The internal air of motor casing exchanges its heat to the external air through the heat exchanger. There is separate fan/blower to circulate the internal air and a seperate fan to force the external air through the heat exchanger. The first one is with standalone motor, whereas the latter is motor axis mounted.
If the client interest is to modify each motor cooling system from CACA to CACW, I think it is appropriate to contact Crompton Greaves or partner with them as it could involve some modifications to the motor.
Other alternative I can think of is to have a common air-to-water heat exchanger and duct the cooled air to the air inlet of the existing heat exchanger of individual motors. This will require minimum work on the existing motors and addresses the basic problem of inlet air temperature being high in the area.

 

[edison123]

Maybe it is just me, but I would expect you to have access to better local resources than to have to pose such questions here.

Yup, this site is not for free consulting & design services.

Muthu

http://www.edison.co.in

 

[petronila]

Nishant

High temperature in the winding is associated with factors that might include, Overload, ambient above 40 C (or intake air cooling hot), blocked vent ducts, improper fan installation (external fans turning on wrong direction), harmonics or unbalanced power supply voltages, excessive loss in the stator core (above 5 wats/pound), incorrect cooling design, amng others. But, if most of all motors are running at 138-148 deg C my suggestion is to verify some of the factors listed above that are common to all motors (i.e Power voltage supply, ambient, intake cooling air) before make any change in the heat exchanger.

Best Regards

Petronila