Wood-fired pasteurizer, plus ancillary loads

[mapratt]

Hi, everyone - I have an odd requirement. I'm starting a dairy, and need to run a pasteurizer every day or two. I have 60 acres of forest - more wood than I can ever use.

I also, of course, have other needs:
- domestic hot water
- in-floor heat for the cheese-make room (room is basically 9x21, though it's narrower at one end)
- possible implementation of under-floor heat in the old house (currently heated via efficient fireplace insert i put in a year ago, or in-wall electric heaters, which I hope to never turn on again). Some portions of the house are not well-served by the fireplace insert. House is ~1000 sq ft in size, not currently insulated at all (lots of work to do here). This house will ultimately be office / food prep space; "the" house will be straw bale / timber frame / cob,and will be too far away to be served by anything I put in place here.

I've been thinking I would put in a wood boiler (I like the Froling but haven't priced anything yet) and a big thermal store, and either dip into that with exchange coils or with circulating the water directly, as makes sense, for the different applications. I need to build a shed for all this, and wood storage, and some other equipment (compressors / pumps for the milking equipment, etc.)

The pasteurizer is a stainless steel vessel that has a jacket. Water of different temperatures is circulated to heat, then chill, the milk inside the vessel. The pasteurizer need to bring the milk up to 145 degrees for 30 minutes, then I'll circulate chilled water to quickly get it back to a cooler temperature for the next step.

My pasteurizer person is asking for incoming hot water temperature to be ~180.

I'm working with a contractor for the pasteurizer construction (taking a used restaurant steam kettle and making it into a pasteurizer); he looked at my energy system design. I had put in there that I ballparked 50k for PV array, etc. He read that as 50k for the boiler implementation. He thought that should cover it.

But if I need to spend 50k to figure out how to burn wood to heat water for the pasteurizer (the other uses are ancillary to the base requirement), then I have the wrong design.

Thoughts? I know I haven't provided enough info, but the operation doesn't exist yet and it's a bit difficult to guess...

 

[in hot water]

Consider some solar thermal also. In your area there are state and various fed programs to help with the cost. In addition to the federal solar tax credit I know some farms and greenhouses that have received USDA grant $$.

If you package some solar with the wood you may qualify for these incentives. Best to contact a local solar installer to get the lowdown, and maybe your accountant or CPA.

This dairy magazine has an article on of a solar dairy project. Solar Today and SolarPro magazine have articles on solar farms also.

www.progressivedairy.com/index.php?...your-dollar&catid=48:new-technology&Itemid=74

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[mapratt]

Thanks, yes, I did / am looking at solar, but this is the rainy part of Oregon and I'm not sure I can keep the heat up during the winter months?

I'm working with a company on the PV system; we looked at solar but it looked a bit expensive - given I was planning the boiler. If the boiler is nonsense then solar, ok, but ... winter looms ...

 

[mapratt]

(And thank you for the link!)

My earlier reply may not have been completely coherent...

I'm in the act of applying for incentives for implementing a PV array with battery and generator backup, as there is a fairly significant requirement for electric power even if I solve heat-generating power requirements in another way - to start pumps, to cool things down, to run fans, to run temperature recorders, even just for the lights (220 lumens required!).

But generating heat from electricity is very, very expensive and I have 60 acres of woods...

Solar thermal is what I meant, when I said we have considered solar for heat; that's what we nixed at least temporarily due to my wish to heat w/ wood. Not clear that even with incentives it would make sense.

We're also going to look for incentives for biomass heat.

And I have a stream that should be viable to help generate electric during the rainy / sunless winter months.

But the concept of 50k for boiler and thermal store just sounded like an unexpectedly large amount of money to me?

 

[in hot water]

It sounds like you are doing good research. With any energy project you need to define the loads, how much energy will be required, cost of your energy including fuel for heat and electricity.

Then see which technologies work out best for your application, every project is different.

Solar would be hard pressed to replace 100% of your energy be it PV or thermal.

If you do need a lot of DHW or heat, solar thermal does have a better conversion 50% or more compared to 15- 18% from solar PV.

There are some solar simulation programs that could help with the number crunching. They take in to account your loads, location, size of the array, etc.
RETscreen.net is a freebie that is fairly easy to understand and use.

The program provides your SF (solar fraction). SF is the % of the load that the solar would cover on a yearly basis.

Remember solar does not need a bright sunny day to exchange energy. Todays high efficiency vacuum tube collectors work amazingly well on overcast days.

Solar with a wood back up could be a good mix. Find a local solar contractor that is passionate about hydronics and solar to share some ideas and option.

Wood heat is a great option but does take some work to provide the fuel and keep the equipment clean and running well. Solar is virtually maintenance free.

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[shortline]

Marilyn, at least you found this forum before you purchased. I ordered before finding all this experience. Your needs are beyond my residential needs. One thing I've gleaned from this forum is that quality feedstock for a downdraft gasification wood boiler is critical. A two year preparation of your stove wood is necessary. Your requirements are more industrial sized. Maybe something like this wood gun boiler set up for pellets http://cgi.ebay.com/Wood-Gun-E500-G...aultDomain_0&hash=item2a0a2e0108#ht_736wt_689 would be the way to startup, and once you got your manufacturing processes running smoothly, you could pull off the pellet feeder and use stove wood out of your woodlot management program. If 500 BTU/hr will meet your load requirements you won't need as much heat storage to startup -- as pellets are more like oil or gas. Cheaper to store heat preburn as opposed storing it post burn.

 

[mapratt]

Thanks, Shortline! This is a good site ;-).

The challenge actually is that my requirements are kind of small - this is a very small, farmstead / artisanal sheep dairy / cheese-making operation. The pasteurizer will be in the 40-to-60-gallon range and will probably only be used 3x/week. The space heating requirements are mostly met by the fireplace insert in the house; new requirements are relatively insignificant. For now, there is 1 person living on site, and my cleaning requirements are low 'cause sheep poop can be swept up. Not doing cows, so don't need lots of high-pressure hot water spraying everywhere. Other space heating requirements are too far away to take advantage of what I build in here.

I've poked at other sites and further at this site and the links folks have provided (thank you everyone!), and do think 50k is a completely outrageous figure to be thinking about for what I want. I really should be able to get it done for a lot less, should be 'way less than half that. I'm getting used equipment in other areas, re-purposing things, finding inexpensive ways to do other things (like a walk-in refrigerator for $2500 ;-), so I'm not afraid of the concept of re-purposing tanks for hot water storage, for instance.