2 stage HX partitioning

[dirtfish]

I am getting a new 10 square meter 2 stage heat exchanger direct from the manufacturer in China and trying to determine how it should be partitioned. I will run city water through the first stage and cold liquor through the second. The city water will be supplied from a hose bib and the cold liquor will be transferred from the CLT in our walk in via a 1 hp pump with VFD.

We will have a 7 barrel kettle and are planning for ~200 gallon cast out volume. The CLT will be 250 gallons.

I think these are the specs for temperature and flow rates for wort and water that I will have:
Wort in: 200 F
Wort out: 70 F to 65 F
Wort flow rate: variable 0 gpm to 50 gpm
Wort volume: 200 gallons

Stage 1 water flow rate: max 0.1 gpm (we have a small meter/water supply...)
Stage 1 water temp: max 85 F

Stage 2 water flow rate: variable 0 to 50 gpm
Stage 2 water temp: 38 F
Max volume of stage 2 water: 250 gallons

Can anyone suggest the partitioning that I will need? My pumps are supposed to provide max 75 gpm flow rate, but what are realistic rates for chilling?
Thanks!

[dick murton]

Don't bother with a split PHE. A single stage PHE using chilled water at that temperature will be fine providing the PHE is scoped properly. You will be wating valuable heat if you fit a two stage PHE


Having said the above, I do suggest from my recent experience of a Chinese supplier (please see comments elsewhere in this section from me about Chinese suppliers) is to spend the extra and go to a US supplier and get a US or European, e.g. GEA or Alfa Laval PHE. The Chinese one I have had recent experience of is more than four times the size physically of a GEA PHE sized for similar duties. I am convinced this is because the wort inlet and outlet are on the same side of the PHE and the cooling water inlet and outlet is on the other side, and so the two liquids don't fill the PHE plates. So heat transfer is extremely poor. It also means that cleaning will be extremely poor, leading to potential infection build up.

Don't forget you will need spares at some stage, new seals or new plates. If you get them from a US or European supplier, then you can be pretty sure of getting them, and of the correct quality. The seals provided elswhere in the brewery I am referring to - well lets just say I would throw them out as soon as possible, so I don't trust the PHE seals either. And the seals are glued in, whereas the European (and presumably the US ones) will be clip in gaskets - glue free.

And finally - you need to be able to clean the PHE at effective flow rates. Again, the sheer size of the Chinese one means I would put money on it being uncleanable.