Anti-boil for HERMS?

[n87]

Hi All,

I just got a HERM-IT HERMS tube and was wondering if anyone uses a solution that raises the boiling temp of your HERMS liquor. Simply, I am a little paranoid of the element boiling itself dry.

I can see advantages and disadvantages of this
Good:
Help avoid element boiling dry
Faster heatup, especially at the higher temps (Mash out)

Bad:
Possible scorching if the liquor gets too hot (main reason I moved from RIMS)


So does anyone do this or have any other information regarding it?
Does anyone know of an anti-boil recipe that wont react with stainless or get burnt to the element?

 

[n87]

As an addition to this, I dont use the HERMS liquor for any other purpose (it doesn't get drained till after most of the cleaning is done at the end)

 

[mtb]

Cooking oil? Boil temp is 300C

 

[2cranky]

Oil might work really well.
We have a heat transfer press at work. It uses a rotating drum full of oil with an element.
Maintains very even temperature around 203c. The thing is made and sealed under vacuum though.

 

[2cranky]

But I would think cooking oil would leave a residue on the element. Maybe a silicone oil would work better.

 

[n87]

If I did go with some form of oil, i would need to put a separate on the element so it doesnt get so hot that it would start scorching the wort and melting bits (glands for the coil are plastic, and Silicone rubber melts around 300 [quick google search]). Currently there is a PID controlling it, but it measures the wort output.

Followup question on this branch, what temperature would be the ideal upper limit to avoid scorching, de-naturing of enzimes and boiling of the liquor?

 

[Adr_0]

What about glycol?

Generally boiling is an issue if you have a small volume HERMS vessel AND control on wort return, with a low recirculation rate. But a small HERMS vessel is undoubtedly the best way to get a good mash response (good ramp rate and reduced/no inherent overshoot).

The HERM-IT if used with a keg King or March pump should be able to get in the 6-8lpm range but temperatures in the HERM-IT tank would be in the 90-100°C range. There is enough flow, coil surface area and the HERM-IT vessel is small, so the heat can be removed quickly enough to prevent too much temperature gain in the return wort.

Make sure your mash tun/grain bed is comfortable with 6-10lpm and don't choke the flow. Try to minimise tube length between the coil and mash tun.

 

[Adr_0]

Oh yeah... And don't use integral control. Some psycho ranted and raved about this and even wrote a self-indulgent Wiki on PID control - but the guy is a wacko.

 

[n87]

What about glycol?

Generally boiling is an issue if you have a small volume HERMS vessel AND control on wort return, with a low recirculation rate. But a small HERMS vessel is undoubtedly the best way to get a good mash response (good ramp rate and reduced/no inherent overshoot).

The HERM-IT if used with a keg King or March pump should be able to get in the 6-8lpm range but temperatures in the HERM-IT tank would be in the 90-100°C range. There is enough flow, coil surface area and the HERM-IT vessel is small, so the heat can be removed quickly enough to prevent too much temperature gain in the return wort.

Make sure your mash tun/grain bed is comfortable with 6-10lpm and don't choke the flow. Try to minimise tube length between the coil and mash tun.

Thanks,
I have a KK pump, but if i do anything other than a light beer, the grain bed doesnt allow a flat out flow, which i guess is why the liquor was boiling.
I had thought of glycol, i just have to see how it plays with stainless and the element, and all the other bits that it comes in contact with

 

[Adr_0]

Thanks,
I have a KK pump, but if i do anything other than a light beer, the grain bed doesnt allow a flat out flow, which i guess is why the liquor was boiling.
I had thought of glycol, i just have to see how it plays with stainless and the element, and all the other bits that it comes in contact with

If I were you I would be considering the mash tun/grain bed as this is your root problem. The reason I say this is with a low pump flowrate you are much more likely to be overheating the return wort, AND you'll suffer from slow ramp rates.

I'm not sure what geometry options are available for your mash tun but a good false bottom with a bit of standoff distance from the drain point is a must.

Once you sort that out, remove any Integral control as this will keep your liquid boiling and result in overshoots. Proportional only means it will cut right back once it hits setpoint.

I'm assuming your vessel for the HERMIT is only in the 2-4L range and is not 10L or more...

 

[n87]

If I were you I would be considering the mash tun/grain bed as this is your root problem. The reason I say this is with a low pump flowrate you are much more likely to be overheating the return wort, AND you'll suffer from slow ramp rates.

I'm not sure what geometry options are available for your mash tun but a good false bottom with a bit of standoff distance from the drain point is a must.

Once you sort that out, remove any Integral control as this will keep your liquid boiling and result in overshoots. Proportional only means it will cut right back once it hits setpoint.

I'm assuming your vessel for the HERMIT is only in the 2-4L range and is not 10L or more...

Regarding the overheating return wort, im not sure I follow. I have the PID controlling based off the exit temp from the HERMIT. the only time I have seen it get overheated is if I stop the pump, and that would be less than 1l.

Regarding my setup, a picture tells 1000 words. I have just uploaded a butload of pics here: https://aussiehomebrewer.com/media/albums/n87s-brew-rig.1473/
Also a write up here: https://aussiehomebrewer.com/threads/n87s-rig-rundown-pic-heavy.95696/

simply, its a 1v system with a 56l malt pipe ~400mm diameter, ~400mm height.
300mm false bottom with ~48cm2 worth of holes underneath to drain back into main kettle.
generally ~12kg grain, tho the other night it had 19kg

I have been wanting to get a false bottom with more open area (this one I estimate at ~8%) but trying to find one that has any decent stats on it is impossible or way too expensive

The HERMIT is a 300mm 4" pipe, so ~2l

 

[Adr_0]

Sorry, low flow will equally higher HERMIT vessel temperature and slow ramp rates. Very low flow could cause some oscillation and overshoot in the wort return, but you won't get any in the mash tun.

In your pics, is the false bottom the second photo, with the cleaning title? I'm probably missing something but how does the 300mm diameter false bottom fit in a 400mm diameter pot?

Cleverbrewing should have some that match which look like being in the 20-30% open area range which should get you 3-5x slower velocity at the holes for a given flowrate. You could just put this straight on top of your existing false bottom and plug the hole with a plug and nut. https://www.cleverbrewing.com.au/false-bottom-domed.html

If you want to replace it you may have to buy some perforated sheet with a tighter hole spacing - hopefully something like a 5-6mm pitch with 3-3.2mm holes - and weld and cut into shape with a good 3-4" of legs on the bottom. Something like that should give you 20-25% open area. You could alternatively use some SS bar with coarse mesh screen in a similar arrangement to get up around 30-50% open area. Or bars with a BIAB bag.

 

[Adr_0]

Although I guess 19kg on 300mm diameter is still a lot of grain... my 50L setup was 450mm diameter but still never got up to using 19kg so I can't really claim any experience at those weights.

 

[n87]

300mm fits inside 400mm with 50 my on all sides
Apparently this is an ideal size false bottom for that pot as it evens out the flow through the grain bed. There are a few write ups on this, and I think Palmer has it in his book too.
The false bottom is domed, which I think is the answer you are looking for , it just sits on the bottom over the holes. The feet on the malt pipe have been put in such a place that the bolt heads keep the false bottom in the center.

 

[Adr_0]

Gotcha.

I'm guessing that the 50mm gap basically means that flow around the outside of the bed then has to come in past another 50mm of grain, reducing preferential flow down the walls of the malt pipe?

I'm still thinking that 48cm2 over a total diameter of 40cm diameter (1250cm2) is not a lot of area to flow through, so the velocity on each hole is going to be pretty high and with 19kg of grain there will not be a lot of space between the hulls. Any idea what your actual flowrate was with 19kg?

Would a 400mm domed false bottom from the link above and some silicone tubing from http://geckooptical.com/silicone_tubing.htm to give a seal around the edges be better? This would be ~250cm2 of flow area vs your current ~50cm2 so you should have a lot more room for increasing flow, while the seal around the edges should reduce preferential flow along the malt pipe walls.

 

[n87]

The 50mm around is to make the freeloading wort work a little harder as you mention.

I get what you are saying about increasing the size of the false bottom, but I expect I will be losing some efficiency by not ringing the grain as evenly, just to increase my flow rate.
When I get some moneys, I will continue my hunt for the perfect false bottom... know anyone with an English wheel?

 

[klangers]

Boiling water is a fantastic way to heat the coil as the amount of turbulence creates a very high heat transfer rate. It also is self-limiting through boil off. I'd strongly avoid going for an oil or glycol arrangement, as while you'll get a higher temperature gradient, there will be more boundary layer effects. I don't think the risk of having a mini deep fryer running is justified. Boiling dry is an easy problem to fix.

 

[Adr_0]

Boiling water is a fantastic way to heat the coil as the amount of turbulence creates a very high heat transfer rate. It also is self-limiting through boil off. I'd strongly avoid going for an oil or glycol arrangement, as while you'll get a higher temperature gradient, there will be more boundary layer effects. I don't think the risk of having a mini deep fryer running is justified. Boiling dry is an easy problem to fix.

Fair call - for example, topping up with water from the kettle.

You're bang on - the heat transfer coefficient goes through the roof with boiling water.

 

[Adr_0]

The 50mm around is to make the freeloading wort work a little harder as you mention.

I get what you are saying about increasing the size of the false bottom, but I expect I will be losing some efficiency by not ringing the grain as evenly, just to increase my flow rate.
When I get some moneys, I will continue my hunt for the perfect false bottom... know anyone with an English wheel?

The flowrate only really needs to be high during ramps - and then backed right back during rests.

And you shouldn't be boiling during rests... only as you ramp and come up to the 70-80°C mash temperatures. If you do start to boil, make sure you have a hole in your vessel to provide relief so that it doesn't over-pressure with steam.

 

[n87]

There is a little hole in the top of the HERMIT to relieve the pressure, so that's fine.
Also, the 19kg grain bill is pretty much the max I can physically fit in the malt pipe, most of the time it is less than 12kg.

This has given me a few things to think about, will have to adjust a couple of things with my process.