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CONDENSER PUMP for centrifugal chilled water system

CONDENSER PUMP for centrifugal chilled water system

CONDENSER PUMP for centrifugal chilled water system

(OP)
I have an existing centrifugal chilled water system for two blocks for residential complex where two chillers of 600ton*2(one duty one standby) with two cooling towers placed for block A and 530 ton*2 for block B. the system has passed 12 years. there is a common issue for both block. the position difference between chiller’s condenser and cooling tower around 80 meters. It means the only length of suction pipe between cooling tower and suction nozzle of condenser pump is 80 meter(260ft). The condenser pump(end suction) placed near the chiller, now operation had been facing from the commissioning time the following issues
1. The air is trapping on suction pipe, when open gauge port air is strongly drawing into the pipe, but it is working inefficient way from long time.
2. Both condenser pumps in the block A and the block B are, rated with 55 KW (35-meter head), in continuous operation throughout year even though at low ambient of winter season. After switching off the condenser pump, air immediately trapping to the suction line and overflowing the CT sump, and very hard to release the air from system and approximately takes six hours to back the system into the operation. so, the operators will not switch off the system until any breakdown happened. Clear-cut energy waste through this eccentric situation.

In the lights of these experience with this system, now I am thinking to do some retrofits with new thoughts and fresh head calculation. My plan is below,
Relocate the cooling tower to the above the roof of pump room, then could be reduce the pump head and save more energy, but it is more expensive, complicated and hard to take the structural assurance of the slab. Etc.

So, I planned to install more efficient new Grundfos pump (inline vertical) near the cooling tower. By which, I can reduce the suction pipe’s length as 15 meters. The NPSHA will be improved and 10 ft higher than the design pump. Primarily, I prepared an isometric drawing of condenser water circuit. re-calculated the pump head with same flow rate which comes with 37 kw with 22-meter head (70 ft). the existing pump head is 35 meters with 55 KW. This is the planning and progress so far. If any comment , suggestion or advice really would be appreciated.

RE: CONDENSER PUMP for centrifugal chilled water system

(OP)
the current plant design hand sketch


RE: CONDENSER PUMP for centrifugal chilled water system

(OP)
new design by relocating the pump near to the cooling tower

RE: CONDENSER PUMP for centrifugal chilled water system

The rooftop is an idea, but having experienced a basin failure in a rooftop CT once I am not a big fan of that.
Move the pumps closer to the towers, but ...
Where is all of the air coming from? Is that much being entrained in the towers without enough settling time? Or are there line leaks?

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy

RE: CONDENSER PUMP for centrifugal chilled water system

It's a bit difficult to understand why the existing pump set up acts like it does, but without some decent drawings and levels it's not easy.

Either your existing pumps are designed badly or you've made an error in your new calculation as the length of piping seems to remain the same and hence head and power should be similar. I assume you're using the same pipes?

Equally if you have issues with stopping the pumps now, then I can't see why this would get any better with your new arrangement.

But we don't have much data here.

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

RE: CONDENSER PUMP for centrifugal chilled water system

(OP)
LittleInch :I strongly believe that the consultant did the wrong. When overlook the piping layout, the contractor (at the construction time) put the piping in serpent way, lot of curves, elbows etc. even though there is having enough space to strait the pipe. But they did a good thing that they oversized the pipe. 1750 gpm is design flow, one chiller duty and on is standby. Then one pump is required at full load. Suction pipe size is 10inch, and the suction/discharge header throughout around 70 meters equally sized 16inch.
10inch head loss 1.4 ft/100 and 16-inch head loss 0.18 ft/100. I attached the head calculation. Please review it

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