I am always tweaking things in the brewery. Motivation for these changes vary, but usually start with a curiousity and snowball from there. This year’s updates have been related to an idea I’ve been sharing for recirculating mash systems. These types of breweries require recirculation that is quick enough to keep wort well mixed such that temperature readings are representative (minimal lag and stratification), heat exchange is effective (ideally somewhat turbulent flow), and mash solids (coagulated proteins, lipids, various grain material) suitably suspended to prevent scorching and other issues. At the same time, the draw/return rate from the mash lauter tun must be low enough as to not cause grain bed compaction, vectoring, etc.
My idea is not unique, but I haven’t seen it used by another homebrewer anyways. It involves a high flow rate “loop” in a breweries plumbing, which should prevent the formation of excess pressure across the grain bed (i.e. can work as a wort grant, essentially), and also allows higher flow rates in a HERMS coil or RIMS heater without requiring a high draw/return from the mash lauter tun. I don’t know exactly what to call this modified design. RIMS+loop and HERMS+loop?
Some brewers, myself included, have been reducing the wattage of their inline heater during the mash recirculation process. This remains as a good, common-sense idea, though I expect that with this kind of system you may not find that is necessary. I personally will be experimenting with gradually lifting the limiter I apply during mash recirculation.
Everything is perhaps best explained diagrammatically. Check out Figures 1 through 3 for plumbing and flow paths during mash recirculation, lautering, and whirlpool. The descriptions contain lots of extra details.
Next steps
This will surely require some optimization on my part. I expect that it is not suitable for most homebrewer pumps (e.g. smaller chugger or march pumps), though I could be wrong (I use a 1/2 hp sanitary centrifugal pump).
In terms of “dials to tweak” that I have with my brewery using this design, I now have a couple full port quick clean ball valves for my mash lauter tun and boil kettle return ports which should offer reasonable flow rate control. I also have VFD pump control which can control the flow rate and pressure of the pump-heater loop. There is also a small amount of flow rate control possible with the butterfly valves throughout my brewery – but not much!
I have some concern over the generation of excessive wort shear. I have not researched this sufficiently, but my understanding is that it can be damaging to wort quality in ways. Certainly it can disrupt coagulations of proteins and lipids, possibly allowing these materials to be carried further through the brewing process than might be ideal. Perhaps having impacts to beer stability or clarity. Whether proteins are actually degraded somehow seems unlikely to me with the forces that I would be generating… but not an expert here (yet).
I would very much like to incorporate one or two sight glasses to my revised plumbing. These are very useful in monitoring the brewing process (e.g. mash running clarity, flow rate), but I have not found a great placement for them yet.
I also have to make a new brew stand or modify my existing one to work with my new plumbing. Pump placement, spacing, support locations are all slightly different. I am leaning towards making a completely new stand from lumber in case I end up wanting to go back or something. The materials are very cheap and already on hand, so no issues there.
Balancing a loop like this would be tricky without some additional volume. It seems like an ideal scenario for a grant which could enable feedback from the mash/lauter output to automatically balance with the return flow to the top of the mash.
https://photos.app.goo.gl/3yh1XFtnFFkkLoZq9
Pardon the rough sketch. I’ve seen people use a small 1 gallon pot hanging directly off of the tri-clamp fittings as a neat integrated approach. A glass lid could provide viewing, and a small port could blanket CO2 if wort exposure was a concern.
Can you expand on what you mean by “balancing a loop” here? Do you mean it’ll be difficult to achieve my target mash draw/return rates?
Exactly that. If you allow wort to leave that RIMS loop into the top of the mash faster than the mash can freely drain out of the bottom then you’d risk compacting the mash or cavitating the pump. Ideally you could leave the mash drain fully open and restrict the flow back to the top and run without issue, but you don’t have a way to monitor the draining.
Please take this with several large grains of salt, I haven’t tested a system like this myself and I may be creating a problem that doesn’t actually exist in practice. I only know that even with my full screen BIABasket it is easy to out-flow the ability to drain, I worry about a traditional MLT where it is harder to monitor.
Oh! Well my thinking is that a fairly low pressure draw from the mash tun should exist with this kind of loop. And since the loop is closed the way it is – the only way to introduce more liquid is from the mash tun, and the only way to remove liquid is the mash tun return, throttling the mash tun return with a ball valve should be sufficient.
I have used recirculating breweries of some kind for last 5 years. Most recently I was getting away with throttling recirculation rate only with a combination of pump VFD and butterfly valves (which have very limited abilities in this respect). I expect I will get much better control with this, but it will take some experimentation for sure…
To add, it may be possible for me to implement PID with the the pump in order to sustain a specific pressure in the pump loop.
Success or fail, updates to come!
Awesome, can’t wait to see the results!
Regarding shear effects on wort there are probably two areas to consider.
First off is beta-glucan shear impact. If you are pumping mash (most probably not) shear can remove more beta-glucan from the mash. Shearing wort can change the glucan structures and increase wort viscosity, leading to slow lauter runoff. Sorry but I dont have the references available right now. Think it was a paper in Brauwelt International. https://www.brauweltinternational.com/index.php?inc=fachartikel
The other shear impact is on trub formation and whirlpool performance. This is a more macro/particulate level impact, where poor pipework design can break up the trub particles. You might get this in kettle to whirlpool piping or in kettle recirculation systems. I’ve seen a shocker in the home brew market where the kettle whirlpool inlet is an abrupt right angle bend. This is guaranteed to degrade trub particles, reducing wort clarity. Lower wort clarity means higher wort lipids and consequent reduced foam and flavour stability and reduced beer clarity due to more particulates.
An imperfect but useful guide to suitable pipework design is line velocity. Mash velocity should be about 1 metre/sec and wort velocity about 2 metre/sec. In both cases all bends should be long-radius to avoid high shear at the bends.
The 2 metre/sec guideline is widely used in the brewing,dairy and food industries. It protects the product from high shear but at the same time is fast enough to provide turbulent flow during cleaning. Usually the cleaning velocity will be the same as the product velocity.
I’m just putting my 40 litre brewery together. I’m using 10mm id tubing, because I have a lot of it, and because the fits the velocity requirement.
I’m planning a blog on my brewery build. Brewing science heavy. Big brewery tech heavy. Amateur metal worker. I’d love to link to your blog.
Thanks so much for this info Steve!
So based on what you are telling me, as long as I stay below 1 m/sec I should be OK. In my system that would translate to about 23 l/min flow rate. Should be easy enough to do.
What about shear forces in the pump itself, do those matter? I’m running at 30hz on my VFD for my mashing process in my test runs – which translates to 900 RPM IIRC. I use a centrifugal pump.
I do try to make smooth transitions in my plumbing using appropriate reducers and what have you. Mostly for CIP reasons, but good to know that also helps in the shear department.
Clarity has not been an issue since switching to this pump, which runs closer to full speed for whirlpooling and chilling. That may be near or above 2 m/sec I believe, will try to quantify better and possibly decrease that flow rate.
Would love to check out your blog when you have it ready.