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drying spent grains

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  • drying spent grains

    we currently feed our spent mash to pigs. the pigs like the mash better when it is dry. any ideas on how to inexpensively dry spent mash?


  • #2


    No kidding............I have a few questions.......
    What's the size of your Brewery? 10Bbl? 15 Bbl? 50 Bbl?
    What heats the kettle? Direct Fire Gas? Steam?

    "The most inexpensive" method is to scavenge heat from the various heat sources in your brewhouse (hot water heater, brew kettle) and duct that dry heat under a false bottom with the grain on top. This is how our hops are dried, by the way.

    However, the grain needs to be spread thin (about 3" - 5" thick) so that air will pass through, and have this hot air blown up through it. You could dry grains while you are boiling, and fan the heat up through a screen under the grains. You could also run hot water heater natural gas exhaust ducts up into the heat collector as well.

    All of this is pretty exotic, and it depends on the size and waste energy output of your Brewery.


    • #3

      i have a 15 bbl direct fire brewhouse.

      do you propose that i some how get the mash up to the exhaust stacks for drying? or can i capture the exhaust heat and bring it down to the floor where we shovel the mash into steel tubs?

      thanks for the reply


      • #4
        Ya know.........


        It's ironic how topics come up. We were just talking about your situation in our Brewery with the thoughts of drying the mash for use in foods.

        Thinking about it, I'm not sure you could cost effectively dry the mash in your facility. My thought is that you would have to tumble it as well and that would take time. I think that just passing hot air through teh spent grain bed probably wouldn't work as it does in hop drying...........the hops are a lot lighter, dryer to begin with, and allows for more air movement.

        Somehow one would have to tumble the grains to expose more surface area to the hot air. However, scavenging heat off the brewkettle hot exhaust would be the best source. Hopefully, your burner is properly set and not producing a carbonizing flame. You could re-route the Clas B venting through a tumbler/'s hard to tell how without seeing your lay-out and process. However, tumbling 800 - 1100 lbs (dry.......wet weight?) of mash is no small feet. Routing the Class B venting and still maintaining an upward slope to the most conventient location for the dryer as well as not getting burrned on the venting could be design challenges.


        • #5
          Just a side question if you don't mind:

          How much are you getting from the farmers for your spent grain?


          • #6
            rudge75: we raise our own pigs north of town. in the past i've given it too cattle ranchers just to get it off my hands. its not all that hot a comodity around here.

            diamond Knot: i've considered what you're talking about before, but it seems like it may turn into a never ending hassle setting it up. unfortunately (or maybe fortunately) ive got too many things to do to set up a dryer/tumbler system. thanks for teh insight though.



            • #7
              How dry is "dry"

              I'm not an expert in the dietary preferences of pigs, but maybe it just needs to be a little drier, and not completely dry? (These animals do eat "slop", don't they?)

              How about leaving the grain in the tun to drain overnight? Or, if that's too stinky, drill out the bottom of your spent grain receptacle (55gal drums in my case) and allow them to drain that way? Or maybe install a crude false bottom in it?



              • #8
                Drying spent grains(malt)

                Can you not just turn on the steam to the jackets in the mash tun to dry? Should be dry in a short time
                Doug A Moller
                The Moller Brew House


                • #9
                  Drying Spent Grain

                  Unfortunately we don't have too much to add to this discussion as grain drying at this scale is not something we have a lot of experience with. The real experts in grain drying are the guys up at Alaskan Brewing Company. They've been drying all of their grain for years. If anybody knows somebody up there I'm sure they could be enlightening.

                  My gut feel is that if you have to add some apparatus for drying the grain the cost/effort/space required will kill the project. Some intermediate step like the draining spent grain buckets would probably be most feasible as long as BOD load in your waste water isn't a deal breaker.



                  • #10
                    Spent grains

                    Here in Oregon we grow a lot of mint. And for years no one seemed to know what to do with the spent mint after pressing or the mint straw that had to be collected from the fields each year. Finally, not too many years ago, two markets were discovered and expanded for these previously worthless byproducts. Today I pay $13 for a yard of mint compost made from the spent mint (superior to bark for landscaping because it actually puts nutrients back into the soil, and it smells good too), and the mint straw is now bundled, sold, and shipped to Japan. Is it possible there is another market out there that could be developed to make a profit from spent grain?
                    Banjo Bandolas
                    v- 541-284-5500


                    • #11
                      I was a brewer at Alaskan until very recently and I have to say that they did it right. Alaskan dries almost 24/7 and it takes a fair amount of fuel. They start the drier with diesel and then once it is hot (700F) they start adding dry grain to continue the fire. They utilize the heat off this 1500F fire through the use of a fan that pulls the hot air through a huge drum with many chambers in it. The wet grain is added to the drum and once it passes through (takes about 30 min) it is down to almost no moisture. Then we ship it back down south. You can see this is just one reason why it is expensive to brew in AK.
                      I imagine one could try to make a makeshift drum out of a 55 gallon drum and have a fan sucking hot air through it (from some sort of fire) and have the grain added at intervals into the drum. Although I imagine unless you had a burn chamber the heat loss would be too great. I don't think it would be economical in anyway to look at purchasing a grain dryer though. Sorry not much help.


                      • #12
                        Do you have a flat roof?

                        I give about 200# of spent grain a week (not nearly as much as y'all) to a friend of mine who has pigs and horses. We cart it over and dry it on his roof by spreading it out about 2" thick on a tarp. He rakes it once and its dry in a day. If you have enough space (and brew-monke... sorry, assistants) it'd be cheaper than an air dryer.


                        • #13
                          why dry?

                          We've been feeding our pigs spent grain for 6 years. Not only do we not dry it, we add spent yeast, ends of old kegs, fruit from our fruit beers, and anything else that lies around long enough. They like it wet, the wetter the better. What they reallydon't like is processed feed - especially hog pellets. Mind you, our pigs are on pasture, which may change their attitude to real food. As another note, we also feed wet grains to dairy cows and sheep, and they all eat them wet just fine. The only things we've noticed is that if the grains start to get stinky, only the pigs will eat them, and most of the animals prefer less roasted malts. So (I hate to change this to a farming list, but...) maybe you should vary the pigs diet a bit more, put them on pasture and add some other brewery by-products to the mix! They are a bit like humans, needing variety or they get bored and picky.

                          By the way, spent grain also composts beautifully, as long as it's turned regularly and preferably mixed with other, drier materials. Trub, for example, or uneaten hay/straw...

                          Nice to know that someone else is farming and brewing!

                          Crannóg Ales
                          Canada's Certified Organic, on-farm microbrewery


                          • #14
                            Spent Grain alternative market - Hog Fuel?

                            I've done a little research on another possible use for spent grains.
                            The fact that Alaskan brewing actually uses dried spent grain as a hog fuel to heat their drying system got me thinking. There are a lot of different factories out there that use hog fuels (wood chips, etc.) to heat their boliers or whatnot. Alaskan says they had the BTU value of their dried spent grain evaluated and gave me the following numbers - Brewers Dried Grain with 10% moisture has a net BTU value of 5,000 BTU/pound.
                            This is very close to the BTU value for wood chips. Perhaps it would be worthwhile checking with local manufacturers to see if they would be willing to buy your spent grains or at least haul them off for free.
                            Banjo Bandolas
                            v- 541-284-5500


                            • #15
                              Spent Grain as Fuel

                              Did they mention how many BTU's it takes to dry the grain in the first place? This would determine if burning the stuff makes sense from an energy standpoint.

                              There was a talk at the CBC the last time it was in Seattle looking at various ways to deal with brewery waste in an efficient manner. They suggested growing mushrooms in the spent grain. Apparently this not only gives the mushrooms a good growth medium, it also makes the spent grain more suitable for animal feed as it is broken down further in the process.

                              So if you have a mushroom farm around perhaps you could ask them if they were interested.