I have recently visited a couple of craft breweries and they have both had Grants. How do you use then and what do the do for homebrewing?
Liquid from the mash tun is drained into the grant using gravity, the liquid is then pumped from the grant. This keeps the pump from compacting the grain bed.
Then what? One tour guide, if I understood him correctly, said that they recirculated from the grant back to the mash tun several times before transferring to the kettle. Sounds like sparging.
Same thing, from what I understand. When they recirculate the wort (probably like RIMS or HERMS), they use a gravity fed grant so the pump won’t create too much suction on the false bottom of the mash tun and compact the grain bed.
Stevefry, That recirculation is also known as Vorlauf. That is the process of taking the initial runoff that has a lot of ‘fines’ from the grain bed and recycles them onto the top of the bed where they are filtered out of the wort. The velocity of flow diminishes as you move away from the drain and into the bed. It is the velocity that has the ability to move fines. Where the flow velocity of low enough, no more fines will be moved into the wort runoff.
You only want relatively clear wort in the kettle since those fines from the grain bed can add astringency to the wort.
Hmmm, this didn’t really answer the question as to what a grant is/does. I’ve always kinda wondered myself…
Right, the vorlauf answer was regarding the question by stevefry.
As already mentioned, the purpose of a grant is to prevent the head at the bottom of the grain bed to get too low. If the difference between the head on the top and bottom of the bed is too large, it can cause the bed to compact and plug. Many of you have seen the ‘gooseneck’ outlets on historic mash tuns in large breweries. Those outlets are also a measure to help reduce that head difference imposed on the grain bed.
With a grant in place, a pump intake can be inserted there and it will just pump the grant dry instead of applying a suction on the bottom of the bed when a pump intake is connected directly to the tun.
A grant is not really needed. The pressure at the bottom of the grain bed can be regulated by throttling the tun outlet valve. Even if a pump is attached to the tun outlet (like with RIMS or HERMS), the pressure at the bottom of the bed can be reduced by closing the discharge valve on the pump to limit the flow rate.
Including a sightglass (manometer) that is ported to the bottom of the grain bed enables the brewer to avoid placing too much head difference on the bed. By monitoring the head in the sightglass, you will know when to throttle either the outflow valve or the pump.
I thought it was another way to get free money from the govt?!
Nicely done!