Converting lautering under gravity to VFD controlled wort pumping

[tringali]

Try Single Infusion Mashing

The VFD's are a good idea and will help but have you tried doing a single infusion mash in your lauter tun instead of mashing in your kettle and transfering? A SIM will simplify your life, shorten your work day and may actually improve your beer. If you can, give it a go. If it works out well for you, take the rakes out of the lauter tun because you certainly won't need them.

[dick murton]

Amit, you certainly can find standard sieves in India with no problem. They are used in many industries. They will guide you to a crush that is appropriate. The more I read about what you're doing, the more I'm convinced that it's your crush that is giving you issues. You just and simply cannot adjust a mill by a hand analysis. The "muck" on top of a lautered bed is normal. It has the potential to bind, but if you stir the top half of the bed as you lauter, you can keep most of the fines in suspension or integrated into the depth of the bed. Agree with all of this, but still consider the current centrifugal pump is likely to be a major part of the problem. Have a look at Reeves Stephenson in Edinburgh. they do hand held shaker boxes. If you want to use ASBC mesh sizes, you should be able to buy some, and replace the "wrong" mesh sizes withe new, or add new meshes by getting someone to make up additional sieves. I did this myself before a trip and checked the results against a plansifter type system myself before i went out (to India oddly). The key to using handhelds is to use a consistent number of shakes in each direction, and in he same sequence


Dick, I would not think of recirculating mash through the pump as a means of mixing. ( I am not proposing to use a pump like this - exactly the opposite as I have seen the damage high speed / high sheer pumps do to mash ) Most of these have a mash mixer paddle that precludes the use of a pump for recirculation. The paddle and the bottom heat combine to form a very efficient and thorough mixing pattern that keeps heat very even throughout the mash. By a "large" diameter pump, I'm thinking somewhere around 6-8 inches. The German forms of this use Hilge pumps. You can bet the Chinese don't use anything near as high quality. The flow rate that I'm used to seeing will empty the mixer into the lauter in about 7-8 minutes. It's quite fast, but with a large impeller it's not very high RPM. And again, no damage.

BrewinLou, if you have an enclosed grant you like and it works for you, then by all means carry on! I'm just saying that if I had a choice, it wouldn't be for a grant. 4 times in 8 years is an unacceptable failure rate for me. The cost of replacements, time, lost product would have me install a VFD for the same price. It's less equipment at a lower price. I don't like moving wort around any more than necessary (especially with a pump) and a VFD seems to be the gentlest, cheapest, easiest way to do it.

I hope my responses show up - bold text. If not I will resubmit

[gitchegumee]

Amit, you certainly can find standard sieves in India with no problem. They are used in many industries. They will guide you to a crush that is appropriate. The more I read about what you're doing, the more I'm convinced that it's your crush that is giving you issues. You just and simply cannot adjust a mill by a hand analysis. The "muck" on top of a lautered bed is normal. It has the potential to bind, but if you stir the top half of the bed as you lauter, you can keep most of the fines in suspension or integrated into the depth of the bed.

Dick, I would not think of recirculating mash through the pump as a means of mixing. Most of these have a mash mixer paddle that precludes the use of a pump for recirculation. The paddle and the bottom heat combine to form a very efficient and thorough mixing pattern that keeps heat very even throughout the mash. By a "large" diameter pump, I'm thinking somewhere around 6-8 inches. The German forms of this use Hilge pumps. You can bet the Chinese don't use anything near as high quality. The flow rate that I'm used to seeing will empty the mixer into the lauter in about 7-8 minutes. It's quite fast, but with a large impeller it's not very high RPM. And again, no damage.

BrewinLou, if you have an enclosed grant you like and it works for you, then by all means carry on! I'm just saying that if I had a choice, it wouldn't be for a grant. 4 times in 8 years is an unacceptable failure rate for me. The cost of replacements, time, lost product would have me install a VFD for the same price. It's less equipment at a lower price. I don't like moving wort around any more than necessary (especially with a pump) and a VFD seems to be the gentlest, cheapest, easiest way to do it.

[Amit]

I was going off the assumption he only had one speed for his rakes. I could be wrong.

Phil, I have never used a vfd for the run off, I have seen them used, but I have a hard time even thinking of giving up our Specific Mechanical grant for one. Not to thread jack, I fail to see how our grant aerates wort. The wort flow slowly into the bottom of the grant, high switch turns on the pump, low switch trips before the grant is empty. Ours is a sealed grant with a balancing line going up to the top of the mash tun. Not seeing a lot of cooling with hot wort entering a hot grant. Our float switch has malfunctioned maybe four times in eight years due to not being turned on, and wort shorting the sensors in the housing, easy fix.

BrewinLou, Your assumption is right we have one fixed speed for rakes. I stop the rakes post transfer else it won't allow the bed to settle and use it only while sparging and rest it again. Your system sounds similar to ours, what are your run off times? How long does it take to lauter? Do you get any particles escaping the bed? How wide is the opening gap on the filter plate? I have two butterfly valves (check first pics) one from the lauter and other opens into the grant. I use any one of them to control the flow into the grant while keeping the other fully open. The grant also functions like a whirlpool later on, the wort is released near the bottom so no aeration problems here as well. Pipe size would be based on 32 DIN so approx 35.16 mm o.d.

Amit

[Amit]

This system appears to be a knock-off of a typical 10hl German-style system. I've installed and used this type of system many times. I believe that rakes are unnecessary and expensive in a small system like this. Especially used with a plow for grain-out. Last system I installed like this, I removed the plow bar. Manual grain-out is easy enough and the few......throttle the discharge, further damaging sweet wort. I just don't see any reason for a grant.

Hope this helps!

Phil, 2 hours is brilliant time but so far we have only managed to come down to 8 and closest we have been able to. I will try out your technique of slowing the rakes instead of stopping them all together after transfer but thats post VFD installation as there isn't any on the system right now.

We cant switch to kettle or to vorlauf, This isn't something built in the brewhouse, wort needs to be collected batch wise in the grant on gravity and transferred. The vorlauf is possible only by using the tap on the lauter pipe. This we use to collect the cloudy wort in the bucket and dump them back in the lauter. We do it three times 20 x 3 = about 60 Liters. We then slowly open the valve for letting the wort into the grant.

However I am planning to extend a line from the lauter pipe (as stated in the previous drawing in red) and connect to the pump inlet to make the switch to vorlauf and kettle possible. This way I can use the pump to slowly send the wort directly into the lauter for vorlauf and into the kettle for collecting. Given that the mesh opening is 1 mm wide would this be possible without actually collapsing the bed? If I were to redesign the mesh what would you suggest be the best specification for open area % and gap width for lautering faster using a VFD controlled pump and not slowly on gravity?

We finally got our new mill last Sunday, Its a German grain crusher 2 roll mill. Setting the gap is easy and I only aim to press the grains, I am getting most of the grains intact with the husk which separates easily upon rolling between finger so I am assuming this to be a decent crush under dry milling conditions.

I have used ASBC screens at Heriot Watt, but it isn't something I will be able to find locally but will try to get my hands on if possible or get it made.

The bed is fluffy in the beginning but compacts as we keep lautering, at the end thou I have noticed a layer of muck above the bed surface which I know is the fines from milling but is this acceptable? How much of fines are acceptable? Of what I have read, this layer of fines leads to greater differential pressure across the bed and so is it avoided at all costs or is it something brewers have to live with especially when dry milling?

I dislike using grants either, after a while the wort in the grant applies back pressure and lautering get even slower. To find out the pressure difference using a manometer, Will I need two tubes one from the bottom of the screen and the other from above the screen?


Amit.

[Amit]

You have a couple of major problems as I see it.

Firstly, and possibly most importantly, you are using a centrifugal pump to move mash around. Assuming this has a similar impeller design as a convention beer transfer pump, you will be severely dmaging the grain particles, smashing them up into extremely fine particles, which will contributs to a set bed. I assume you are using a centrifugal pump for both recirculation in the mash heating phases, and also in the mash transfer. You need slow speed pumps - I believe some people have used peristaltic pumps with great success, and these are probably more practical than buying special low speed open impeller pumps.

Secondly, you really don't have enough rakes in the lauter. "Conventional wisdom" is that lauters should have a bit over 1 rake per square metre - which immediately means yours is under raked. However, there is another problem. These figures are valid for large lauters, say 5 metre diameter. This ratio of rakes to surface area allows the raking tracks to be say one inch apart, but without turning the bed. You need more rakes, but because of the small area being unraked at any one time, there is a risk of turning the bed, particularly if the rotation speed is too fast. I seem to remember the stated optimum rake speed gives 12.5 rakes / sq metre / hour.

The flights on the rakes are very steep. You may find this is causing the bed to turn, rather than loosening the bed up. I haven't measured them, but from memory, I have seen somewhere about an angle of 7 - 9 degrees, not what appears to be closer to 30 degrees.

You need to slowly vary the height of the rakes throughout the runoff as well, so the flights do not track at a single level

The liquor to grist ratio is very thin, and means you cannot sparge very much. I suggest you move to something close to 2.5 to 3.0: liquor to grist, and increase the sparge volume.

And the agitator speed may be so high that it is smashing the grain to pieces. The blade needs quite a high surface area but comparatively low peripheral speed.

Hope this helps

Thanks Dick,

About the rakes, they are non adjustable, and remain at a fixed place and run at fixed speed. Like you said, they turn the bed and not actually cut to make channels. We use the rakes for a min while batch sparging and transferring

The actual reason for using a thin grist is the heating mechanism in mash/kettle which is electric heating coils (30kw rating in all) which are not separated from the mash by a screen. As a result, lower grist liquor ratio causes caramelization to occur and mash to burn on the heating coils. Keeping the mash in motion while heating by using the pump and agitator help avoid sticking of mash onto the heating coil surface.

The agitator has a good surface area probably an anchor design, the speed is high when we begin to add grist but once we add it all the speed gradually slows down.

[dick murton]

Phil

re mash liquor ratio - no problem if this ratio works best for this design. I think if using a centrifugal pump, then a thin mash would be highly beneficial to reduce the grain gamage, and if thickening up the mash then a different pump would be even more beneficial. I say more beneficial, because if I understood the process correctly, the pump is used to recirculate in the mash mixer, as well as the mash mixer - so giving more time for the pump to damage the grain. So for my education, for a system this size, what do you consider a large diameter impeller, and what flow rate do you reckon you are running at?

I assumed that rakes were considered essential because of the stirred mash, knocking all the air out, so the grain bd is not kept separated to the same extent as a (non sitted) single mash tun operation - hence the comments about probably being under-raked.

Cheers

[BrewinLou]

I was going off the assumption he only had one speed for his rakes. I could be wrong.

Phil, I have never used a vfd for the run off, I have seen them used, but I have a hard time even thinking of giving up our Specific Mechanical grant for one. Not to thread jack, I fail to see how our grant aerates wort. The wort flow slowly into the bottom of the grant, high switch turns on the pump, low switch trips before the grant is empty. Ours is a sealed grant with a balancing line going up to the top of the mash tun. Not seeing a lot of cooling with hot wort entering a hot grant. Our float switch has malfunctioned maybe four times in eight years due to not being turned on, and wort shorting the sensors in the housing, easy fix.

[gitchegumee]

This system appears to be a knock-off of a typical 10hl German-style system. I've installed and used this type of system many times. I believe that rakes are unnecessary and expensive in a small system like this. Especially used with a plow for grain-out. Last system I installed like this, I removed the plow bar. Manual grain-out is easy enough and the fewer parts inside, the better. But if you have the rakes, I think you should use them. Even if unnecessary, you can use them to your advantage. The way I use them, the rakes are on full speed for mashing in on single infusion recipes and also on full speed if I'm transferring mash from mash mixer (as in a program mash). Upon filling the lauter, I turn down the rakes to very slow speed. About 1/2 to 1/4 RPM. (Note that many VFDs have a maximum "turndown" on how slow the unit will work properly--especially in high-torque applications like this) Allow a rest--~10 minutes. Perform vorlauf--~10 minutes. Switch to kettle with a very slow transfer to avoid screen blinding. Add very hot sparge (82C) when the grain bed is ~8cm from liquid surface. Increase runoff rate after about 45 minutes and when the runoff starts to dilute with hot water (making the viscosity much less). Slow the rate for the last 15 minutes of lauter to avoid trub, but still collect wort until about 2 degrees P. I aim for 2 hours for total run-off time.

All that said, I always set my mill to a known screen profile on ASBC screens. Judging malt crush by hand won't work. You really should have screens if you are changing malt vendors. And contrary to Dick (I know I'm stepping out of line here!) I like a higher liquor/malt ratio in difficult to lauter mashes. Reason being that a thinner mash, lautered slowly, has a better opportunity to set up a tall, fluffy filter bed. And less sparge is required. Thick mashes tend to compact easier for me. That's double trouble--as the bed compacts, the tendency is to compact more (think DE filtration). Again with apologies to Dick, I have used relatively large diameter, closed impeller centrifugal pumps for mash transfer (ALWAYS on VFD and run relatively slow) to transfer mash from the mixer to the lauter without any noticeable damage to the mash. My experience with these systems is that there is a paddle in the mash mixer, so recirculating mash in the mixer during heat wouldn't be an issue.

I endorse the idea of a manometer at screen level to monitor the bed suction. This is your primary key to lauter rate. Suction shouldn't be more than about 5cm difference between screen suction and mash level. Pull the sweet wort with slow VFD pump directly from the lauter bottom and discharge to kettle. This speed will need to be increased as lautering proceeds, as the kettle level increases and puts some back pressure on the pump, as the mash temperature rises, sugar decreases, viscosity decreases, and your screen suction delta pressure decreases. Use a paddle to spread the mash bed top even. The rakes may not do the job perfectly. I think that grants are an excuse to aerate hot wort and get rid of them whenever I can. The float switches fail at the worst times (when you're not looking), the high pump speed thrashes your sweet wort, the sweet wort sits and cools unevenly, and many installations throttle the discharge, further damaging sweet wort. I just don't see any reason for a grant.

Hope this helps!

[BrewinLou]

Can you take a pic of your grant in relation to your lauder tun? Is there a throttling valve on the grant? What size pipe? Your mill gap sounds quite tight at least for our system. Have you tried rice hulls to see if it makes a difference in run off time? If your rakes are spinning too fast try turning them off for long periods during the runoff, once it is mixed thoroughly you may not need them as much as you think. Can you raise and lower your rakes? Thanks

[dick murton]

You have a couple of major problems as I see it.

Firstly, and possibly most importantly, you are using a centrifugal pump to move mash around. Assuming this has a similar impeller design as a convention beer transfer pump, you will be severely dmaging the grain particles, smashing them up into extremely fine particles, which will contributs to a set bed. I assume you are using a centrifugal pump for both recirculation in the mash heating phases, and also in the mash transfer. You need slow speed pumps - I believe some people have used peristaltic pumps with great success, and these are probably more practical than buying special low speed open impeller pumps.

Secondly, you really don't have enough rakes in the lauter. "Conventional wisdom" is that lauters should have a bit over 1 rake per square metre - which immediately means yours is under raked. However, there is another problem. These figures are valid for large lauters, say 5 metre diameter. This ratio of rakes to surface area allows the raking tracks to be say one inch apart, but without turning the bed. You need more rakes, but because of the small area being unraked at any one time, there is a risk of turning the bed, particularly if the rotation speed is too fast. I seem to remember the stated optimum rake speed gives 12.5 rakes / sq metre / hour.

The flights on the rakes are very steep. You may find this is causing the bed to turn, rather than loosening the bed up. I haven't measured them, but from memory, I have seen somewhere about an angle of 7 - 9 degrees, not what appears to be closer to 30 degrees.

You need to slowly vary the height of the rakes throughout the runoff as well, so the flights do not track at a single level

The liquor to grist ratio is very thin, and means you cannot sparge very much. I suggest you move to something close to 2.5 to 3.0: liquor to grist, and increase the sparge volume.

And the agitator speed may be so high that it is smashing the grain to pieces. The blade needs quite a high surface area but comparatively low peripheral speed.

Hope this helps

[Amit]

Before you even start to talk about lautering regimes and their problems, let's go back to basics.

What does you grist consist of? Malt only? Or are you using any cereals such as rice or maize?

Do you mill your own malt, or get it in pre-ground?

Is it local malt or from the US, UK, or Germany for example?

What is your mashing regime - grist to liquor ratio, temperatures, times, how do you mix the mash liquor with the grist. Do you transfer from a mash mix vessel, or simply mash into the same vessel you are using for lautering?

I suggest a photo of the rakes themselves might be useful, along with photos of the mash mixing vessel if you have a separate one. If you have a separate mash mixing vessel, what sort of pump do you use to transfer the mash?

How many rakes are there, and what is the surface area of the mash separation vessel?

Dick,
I have answered the questions in blue and some more photos attached

What does you grist consist of? Malt only? Or are you using any cereals such as rice or maize? - Malt only - Wheat for hefe - no adjuncts are used

Do you mill your own malt, or get it in pre-ground? We are milling our own

Is it local malt or from the US, UK, or Germany for example? The barley is imported but malted locally - The malt is not excellent but its not that bad either Sometimes its imported from Australia, sometimes from Argentina .. I noticed that the grain size always varies and accordingly we change our gap settings

What is your mashing regime - grist to liquor ratio, temperatures, times, how do you mix the mash liquor with the grist. Do you transfer from a mash mix vessel, or simply mash into the same vessel you are using for lautering? Step up infusion - 52 - 20mins, 65 - 70min, 72 - 15mins, mash out at 78- 5mins, we have a mash cum kettle which has an agitator but I also use the pump for vertical circulation in the tank. Later on, transfer to Lauter. Grist ratio is 1:4.2

I suggest a photo of the rakes themselves might be useful, along with photos of the mash mixing vessel if you have a separate one. If you have a separate mash mixing vessel, what sort of pump do you use to transfer the mash? We have a centrifugal pump (above picture)

How many rakes are there, and what is the surface area of the mash separation vessel? 3 bed cutters on either side of the shaft, total 6. Our mash separation area would be 7013 cm²,

My question is I have been supplied with a plant which lauters on gravity.. Collecting in the grant..transferring to kettle etc etc..With the current mashing regime even on 3 hl plant capacity, It takes 12 - 14 hours for a brew.
However our production demands are increasing every month, and we need to figure out a way to cut down the time hence this idea to reduce the brewing time to switch from gravity to pump suction obviously not with the current filter plate as its def not meant for the purpose as the open gap is 1 mm in size this allows lot of trub to flow through even on gravity

.

[Amit]

"Rakes is a problem, especially when we sparge, they spin too fast... "
What about putting a VFD on the rakes then?

Yes we have ordered for 2 VFD's ... One for rakes the other for the pump in the picture

[dick murton]

Before you even start to talk about lautering regimes and their problems, let's go back to basics.

What does you grist consist of? Malt only? Or are you using any cereals such as rice or maize?

Do you mill your own malt, or get it in pre-ground?

Is it local malt or from the US, UK, or Germany for example?

What is your mashing regime - grist to liquor ratio, temperatures, times, how do you mix the mash liquor with the grist. Do you transfer from a mash mix vessel, or simply mash into the same vessel you are using for lautering?

I suggest a photo of the rakes themselves might be useful, along with photos of the mash mixing vessel if you have a separate one. If you have a separate mash mixing vessel, what sort of pump do you use to transfer the mash?

How many rakes are there, and what is the surface area of the mash separation vessel?

[timbro81]

"Rakes is a problem, especially when we sparge, they spin too fast... "
What about putting a VFD on the rakes then?