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Lautering with racks - what's the best technique?

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  • Lautering with racks - what's the best technique?

    I have a 24 hl lauter tun with speed controlled racks.

    When I bought the brewhouse I was totally unexperienced with racks. In a book I read one should activate the racks during sparging.

    What I do at the moment: I pump the mash into the lauter tun, I let it rest there a bit and start the lauter pump, when I see only a little bit of wort on the grain bed I stop the lauter pump, open the valve for the sparging water and activate the racks, when the lauter tun is filled with enough water I close the valve for the sparging water, then I stop the racks, I let it rest a bit then I activate the lauter pump again.

    Are there any brewers out there who also work with racks? Can you tell me if this what I do is advisable or not? Are there other techniques? How dou you use your racks?

    I am not sure what speed I should adjust to get the highest efficiency.

    Best regards, Daniel

  • #2
    I got a very fruitful private message from Dick Murton I would like to share with others:



    dick murton dick murton is offline
    Registered User
    Join Date
    Oct 2002
    Location
    Tadcaster, Yorkshire, UK
    Posts
    1,210
    Re: Lauter tun ops - resolved?
    Typically for any lauter tun or traditional British mash tun, the grain bed is never allowed to dry out except after the required amount of sparge has been added.

    Preheat the LT using sparge water (77 – 79 C), running to drain if you have sufficient in tank to be able to do this. Flood the lauter tun plates so they are covered with perhaps 1 cm hot water (again, use sparge water.) If you don’t have spare water to preheat, simply cover the plates with hot sparge water. Try to ensure that it is at 77 – 79 before running into the tun.
    Transfer the mash and rake slowly to spread the grains bed evenly. Some people like to let the bed settle for a minute or two before recirculating, others will start recirculating immediately the mash transfer is complete. Recirculate until reasonably clear. Try not to recirculate more than the volume of water below the false floor. If you transfer more, you will simply transfer strong wort to the top of the lauter, and increase the concentration of, what is effectively the very first sparge. In large brewery operations, the time spent recirculating is critical, but in a small setup, a few extra minutes won’t make any real difference to overall brewhouse output per day.
    I suggest you don’t rake at all during the first wort runoff, that is until you start sparging. Start raking at slow speed when you start sparging. Sparging should start when there is almost no water / wort left lying above the grain bed. Do not allow the grain bed to start drying out.
    The sparge and runoff rates should be matched to maintain a few centimetres of water on top of the grain bed.
    Start the runoff at about ½ to ¾ the final rate. The faster you can run off at the start, the slower you can run off towards the end of runoff, providing you don’t allow the bed to compact and blind.
    Raking should be fast enough to help keep the bed porous, but not so fast that that it allows large amounts of flour etc to be washed through. The wort should remain bright.

    I have taken the following from a talk I did a few years ago in India

    • Target cycle time according to loading
    • 1 outlet per square metre, distributed evenly
    • 3 + rakes / sq metre
    • Cutting speed
    – Fast enough to cut bed in acceptable time
    – Slow enough to cut bed, and not move it
    – Equivalent to 12.5 rakes / m2 / hr
    • Sparge rate must be
    – Equal to or slightlyfaster than runoff rate
    – Evenly spread to prevent holes forming in bed
    • Underplate jetting to clear debris
    • Differential pressure or manometer to determine bed condition

    • Spray / jet with CIP supply to drain – to pre-heat LT
    • Underlet to cover plates – prevents blinding
    • Transfer mash – slow deep raking to spread mash
    • Allow to settle (no raking) – turbulence stops
    • Vorlauf at approx 4.25 hl / m2 - underlet volume
    • First worts fixed at approx 4.25 hl / m2 - approx 25 % total volume
    • Rake if DP rises / manometer level drops

    • Runoff speed - programmed increased during second worts
    • Raking controls used to maintain runoff rate
    – Raking gear descends if flow not maintained
    – When flow restored, rakes return to original position
    – Runoff stopped if set bed routine initiated

    • Sparge volume must minimise drain down volume
    • Deep bed rake during 3rd worts
    • PG when volume in kettle - circa 1o P
    • Discharge grains
    • Under plate jet to remove residues

    Hope this helps
    dick

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