whirlpool boiling / 500 litre cooling

[leem]

I'm looking for some advice as I'm just setting up a 500 litre system.
For heating the boiler I have 2 x 5kw elements plus a 24kw gas burner. When I upgrade to 3 phase soon I will add electric elements to reduce the use of the gas burner. My main concern here is scorching the wort which I've read a lot about and so I have this idea to gently whirlpool the boiler whilst heating to the boil. My theory is that circulating the wort will reduce wort contact time with the electric elements and so reduce scortching the wort.
Does anyone have any experience of this or am I worrying about nothing or barking up the wrong tree.

My other issue is cooling 500 litres of hot wort. My tap water temperature here in SW France is around 24C in summer so cooling with a counter flow or plate chiller direct from the mains water would work quickly in the winter only (10C water temp). So if I cool from a cold water tank how do I calculate how much cold water I need at what temperature to cool the wort quickly & what is my best method? Physics was never my strongest subject at school (a long time ago)!

Any advice would be greatly appreciated.

[razzman]

Hi Leem, in short, I think you are barking up the wrong tree with regards to the elements. I say that because I did use a RIM system for a few years and always ended up with a coating of sugars on the element after mashing. So regardless of what you do with the wort in the kettle you will always get a build up on the elements.
As for your cooling question, yes you can still cool regardless of the temperature of your tap water but the water temp will govern your final wort temp into the fermenter. There are a couple of things I do that can help your process.
1. Keep the summer brewing for ales etc, so the pitching temp is up around mid - low 20's.
2. Conversely, do your larger and pils etc, for winter brewing where you can cool the wort close to 10 degrees.
3. I can't work out how much cooling water you need, I suggest an on line calculator.
4. I suggest running the wort outlet of the chiller back into the kettle to help cool the wort a lot faster, also using a pump within the kettle if you have one (like a Braumeister) will crash the cooling temperature.

[brewfun]

When I upgrade to 3 phase soon I will add electric elements to reduce the use of the gas burner. My main concern here is scorching the wort

The thing that governs scorching is heat density. The more surface area your elements have, the less scorching is an issue. Generally electric elements create a lot of convection in a kettle and don't cause scorching. That said, hot break proteins can get wrapped onto the elements and be a source of some scorching. Simply skimming any large chunks of hot break early in the boil will help.

My other issue is cooling 500 litres of hot wort. <edit> So if I cool from a cold water tank how do I calculate how much cold water I need at what temperature to cool the wort quickly & what is my best method? Physics was never my strongest subject at school (a long time ago)!

The basic formula is 3.966 btu is the energy to change 1 liter of water 1 degree Celsius. To save time, we can round that to 4 btu. If we calculate what you'll need for a lager, you should be set.

To chill to 10C for a lager:

100 to 10 C = 90 C
500 liter x 90 C x 4 = 180,000 btu

In most commercial setups, it's ideal to chill with the same amount of water you will need for a batch of beer. So, for demonstration's sake, let's assume that you need 700 liters returned to your hot liquor tank. Next, let's say you want the water to go in at 70 C

Now, it's a simple matter of reversing the above numbers. So for 700 liters:

180,000 btu / 700 = 257.14 btu/liter
257.14 / 4 = 64.3 C heat gained per liter.
70 - 64.3 = 5.7 C 

Setting your cold liquor to 6 C should give you plenty of chilling power and the right amount of hot returned to brew with.

[leem]

Thanks guys for the advice, I thought the whirlpooling may be a bit OTT, the cooling calculations are very helpful thank you.

Decided on a 1000 litre capacity cold tank which I'll dump ice into to cool the water to around 10C & then run through a big plate chiller & recirculate the wort through the chiller back to the boiler.

Thinking longer term, what would be the best method to cool 700 litres of water electrically? The 1000 litre cold water tank will be well insulated & at the most I'll be brewing every 4 days. I'd also like to use the same cooler for chilled water through cooling jackets on the fermentors with temperature controllers & a pump/motorised valves.

Cheers

[brewfun]

Thinking longer term, what would be the best method to cool 700 litres of water electrically? The 1000 litre cold water tank will be well insulated & at the most I'll be brewing every 4 days. I'd also like to use the same cooler for chilled water through cooling jackets on the fermentors with temperature controllers & a pump/motorised valves.

You'll want a glycol chiller with enough power to chill your water and fermenters.

If your cold tank isn't jacketed, you may want to rig up a stainless or aluminum chilling coil inside the tank.