Chilled water pipe sizing?

[monkey spanners]

Just like some opinions on a project i am working on.

Have got a ice builder fitted with two pumps feeding a plate heat exchanger and a milk cooling tank.
Pipe run to each is about 20 meter total.

The tank is about 21,000 litres and has two cooling plates with 1 1/2" connections and the plate heat ex. is a two stage job with mains water on first stage and iced water on the second stage. Its a big floor standing one with 2" connections.

The water pumps are about 1.2kw and have 1 1/4" outlets, and i think max flow of 550 L/m.

My plan is to feed the plate heat exchanger with 1 1/2" abs pipe. The outlet of this pump would go to a three way valve so that the pump can be switched between heat exchanger and tank so that once milking is finished all the cooling water can be diverted to the tank and the parlour washing water isn't cooled as it passes through milk side of the heat ex.

I plan to feed the tank with 2" abs, from the other pump and the also the heat exchanger one depending on the position of the three way valve, hence bigger pipe. The 2" pipe would be reduced to 1 1/2" as it is tee'd to the two cooling plates in the tank.

In the opinion of the milking parlour fitters these pipe sizes are too big and will slow down the flow/cooling :confused:

Seems to me the less pumping losses due to pipework the better :) Also there is a provision for extending the parlour in the future so possibly a bigger pump could be fitted to feed the plate cooler. The last one of these i did of this sort of size we fed the plate heat exchanger with 2" pipe at the insistance of the Parlour fitter (different company) and on this site the milk would drop into the tank at between 2.5 and 3.5c

Just like some opinions what you think.

Cheers Jon :)

[chemi-cool]

Hi Jon,

Can you make a drawing of your idea?

I am in the milk cooling business for the past 25 years.

I have seen many ways to cool milk but after installing meters to check energy absorbed, I always go back to DX as the fastest and most economic.

I work closely with the biggest milk tanks manufacturer here, http://www.mgt.co.il/bulk.asp

[monkey spanners]

Hi Chemi,

The milk tank and ice builder are secondhand and made by Packo, the plate cooler is new and much bigger than the one where the tank was previously fitted.
On the previous site one pump fed one side of the tank only and the other did the other side of the tank and the plate cooler, with a ball valve in the pipe feeding the plate cooler to shut when not milking.

My plan was to get as much ice water through the plate cooler during milking as the plate cooler is so big, hence the three way valve. And feeding both the plates from common pipework would get the best out of the other pump during milking. When milking is finished both pumps would feed into the same 2" pipe to the tank.

Previously during milking it had one pump on one side of the tank and in effect half a pump on the other side/half on the plate cooler.
With my piping plan it will have half a pump on each side of the tank during milking and one pump on the plate cooler.

With the valve i was looking at using it could be set to plate cooler only, plate cooler and tank, and tank only. So in effect it could be set to feed the same as before if needs be.

I was wondering more if you think i am going over the top with the pipe sizes, or even if i am if it would make the system less efficient?

I will try and work draw out a plan of the system either tomorrow or over the weekend.

Cheers Jon

[chemi-cool]

Hi Jon,

Pipe size should the same size as the pump outlet and inlet. Plastic pipes have less friction then steel pipes so it seems OK.

Packo makes these weird cooling systems but they seems to work OK.

The way to check the energy efficiency is work out how many watt electricity per liter of milk.

Systems with PHE are usually come with a small operative [200L to 400L] and a temperature [outlet of the PHE] controlled inverter that operates the pump.
In this way you ensure that the milk entering the tank is 4°C.
If this system not present you just have to relay on the size of the PHE and water supply temp.

[surfacehilly]

monkey spanner hi dont know about milk , but would suggest a gate valve to slow the flow in case you freeze the plate gaskets you can then adjust as you feel fit