Pump Bearing Bracket Cooling water lines

[planck121]

Hello,
I have come across a recent pump installation (picture attached), where basically there is one port the cooling water piping is connected too however there is a T valve and the outlet lines go to two different headers Cooling water inlet and cooling water outlet. I do not understand how such a system works, since it is supplying inlet and outlet from the same port. If anyone has had experience with such a system would appreciate your thoughts.

Thanks

 

[1gibson]

Looks to me like a bad piping drawing. Both lines go somewhere around there, then they connect to something, then you're done, right?

 

[planck121]

1gibson, It is not bad piping, there is one input port into the bearing housing as seen in the picture, however there are two lines that are connected via the T/valve going into this port. One of the lines (top one) goes to the cooling water outlet header and the bottom line goes to the cooling water inlet header. The question is how does such a system work in terms of regulating the water flow through the bearing jacket using one part for both inlet and oulet.

 

[bimr]

You don't say what type of pump or the application, so it is difficult to understand.

Attached are some standard drawings of cooling systems. Maybe the schematics will assist you.

Heinz P. Bloch'a book, "Practical Machinery Management for Process Plants" states that bearing cooling is rarely needed and is more trouble that what it is worth. Maybe the cooling system is not working.

 

[planck121]

Bimr thanks for the API cooling water plans. I am quite familiar with those plans in this case it would be something of a plan K. The pump is a between bearing pump running boiler feed water. However the question remains on how can the given connection shown in the picture circulate water since both the inlet and outlet connections to the bearing housing are at the same port. The connections to the seal cooler are a different issue and are clear. But the connection into the bearing jacket at one port does not make sense unless somehow the t valve was directing the inlet and outlet flow from the bearing housing something I have never seen prior in my experience.

 

[JJPellin]

This looks like a system with a deliberate bypass to control the flow of cooling water from inlet to outlet of the bearing housing. But, I am having a hard time determining this from the picture. I would consider this for an installation where the cooling water source was very cold (potentially below dew-point). I would do this to limit the over-cooling of the off line pump bearing housings to avoid condensation in the bearing housings. If the bearing housing gets too cold they can regulate the flow of some of the supply right back to the return without passing through the housing.

Are the cooling lines for the bearing housing in parallel with the cooling lines to the seal coolers or in series? If they are in series, they could not pinch on the cooling water to the housing without limiting the cooling water flow to the cooler. There is no downside to over-cooling the seal cooler.

Some of our boiler feed water pumps in the boiler house use demineralized water for cooling. This water is ice cold and could easily cool the bearing housing so cold that moisture from the air would condense in the oil system.

That would be my best guess for the reason for this arrangement. Without a schematic of the entire piping system, I am making some assumptions that could be false.



Johnny Pellin

 

[planck121]

Thank you Folks for the good input. I did finally call the vendor up in Europe to try to understand what they had done with the cooling water design. Basically, there are two concentric pipes going into the same port. The inner pipe prvides the cooling water inlet to the bearing housing and there outer pipe redirects the flow out of the bearing jacket. The T arrangement directs the outward flow to the oulet cooling water system. The system also acts to provide some heat transfer during colder winter months, but ofcourse the entire system is heat traced for very cold outdoor ambiet temp. Thats basically how the system works.

 

[JJPellin]

Another possibility occurred to me when I looked at the picture again. There seems to be an extra fitting in the tubing line on the bottom. In our very cold environment, I would expect this to be an orifice for the purpose of maintaining some minimum flow from supply to return to prevent freezing. But, once again, I still can't seem to understand the overall piping configuration from this one picture.

Johnny Pellin