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Sizing of Steam Boilers
I have read all the steam boiler sizing threads that I could find on this forum and the general consensus is boilers are sized at 1000 BTU’s/Gallon usage.
I have been getting some conflicting advice from consultants versus installers. Hoping that actual users here can give me some advice on real world distilling schedules and what is really needed steam wise.
My equipment:
135 gallon Still with steam jacket and direct steam injection (Arnold Holstein)
265 gallon Mash tun / cooker with steam jacket and direct steam injection (Bavarian Brewery Technologies)
320 gallon Hot water tank, steam jacketed and direct steam injection (Bavarian Brewery Technologies)
At this point I see myself mashing in one week as I have 3 fermenters that hold 2 spirit runs each. The following week running the still (6 runs). So basically, either I will need capacity to heat 585 gallons for cooking and 455 gallons the alternating week for spirit runs.
What do you feel the correct boiler size would be for this scenario?
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12 Replies
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We had similar questions.
Size not to what you have now, but what you will have in a few years. The cost of the unit is relatively small compared to the cost of the installation, commissioning, design of the piping, etc. Regardless of boiler size, you’ll still need traps, check valves, trap test valves, condensate return pump, water softener, etc. So…. go a little bigger on the boiler piece which will “future proof” you somewhat. With that size of the sprit still, you may find a stripping still could reduce your labor significantly.
The switching cost to go bigger will far outweigh the initial cost today. Run a 3″ steam header to the still and stub out some drops at places where future things might go.
We ended up with a 1,000,000 BTU boiler, probably 3x what we need today. Aldrich. I’d recommend that size for you as well, as it can handle what you have and a stripping still.
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So the main question for you is do you want to be able to run these pieces of equipment concurrently? Also what are the sizes of the inlets for the steam on the equipment.
Typically for a hour long or shorter heat-up, you are looking at 1,000-1,200 BTUs per gallon. And a boiler HP is equal to 33,475 BTUs
If you don’t care about running them all at the same time you can size based on your largest piece of equipment (not my recommendation). 320,000-384,000 BTUs or roughly 10HP
Since you pretty much have the same amount of work/cost depending on the boiler size it makes sense to size for your working equipment (Still and Mash tun) 400,000-480,000 BTUs or 13-15 HP
Or all equipment, or plan for future growth if going bigger in the future and just have the burner turned down to you initial equipment sze.
If you need any help coming up with a steam piping diagram for use as an installation drawing, I have worked as a mechanical systems design engineer for the past 14 years and can get you set up with what you would need, along with a materials list to help get you pricing on the installation.
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Thank you – I am thinking along the same lines. 750K to run all now, 1mil to add some in the future.
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Thank you – The 13-15HP does not take into account heating of the hot water tank if I need to mash/cook and distill concurrently, correct?
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That’s correct.
Depending on how much you would be looking to expand, it might make more sense to go bigger. If you want to jump on the call, let me know.
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15hp, or 20hp if you need a little upside.
You should be feeding your HLT hot water from your condensers or mash cooler to conserve energy. And you wouldn’t be heating the HLT concurrently, so exclude that from your maximum demand calculation.
We run a 1200 gallon hlt that’s fed from our mash tun cooling jacket water. Steam coils in the tank are only for temp control. Keeping this tank hot saves us significant time on the heat up stage for mashing. Tank brought to temp by the morning for mashing. This time of year our water is 50f, great for mash cooling, awful for heat up time in a mash tun.
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Careful with staging production with the direct steam, those steam eductors can easily consume 100% of all the steam you generate, regardless of how large the boiler is. If you are heating up the still, and you open that direct steam injection valve full open, you’ll stall the still heat up.
It’s great if the only thing you are doing is mashing, you can push more heat than is possible with a jacket.
We ran direct steam for a few years, mashing and distilling at the same time required a little bit of a balancing act.
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That is a great point, direct steam is a totally different means of heating much faster but requires additional steps to ensure the steam is clean, and also the feedwater to the boiler will not prematurely deteriorate your system.
All of what I said earlier was talking only to steam jacketed equipment, with a condensate return system.
With direct steam you have to be sure to balance the BTU input directed at each piece of equipment. This takes a properly sized piping system and as @Silk City Distillers a balance of operations taking place.
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Thank you – the HLT is supplemented from the still condenser to recapture that hot water. The mash cooker is steam injection only so the HLT is essential to get it up to temperature. The mash cooker is jacketed for cooling from a glycol chiller, so no heat recapture there.
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Thanks – the use of boiler chemicals is out of the question so the incoming water hardness / balance is an issue, as well as filtering the steam.
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Are your lines run in stainless steel? Also are you maintaining a high water temp in your boiler to drive off excess oxygen?
Just want to make sure you don’t end up with iron oxide in your final product.
Do you want to use the direct steam injection? or is it just an accessible feature of your equipment?
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Supply lines are all Stainless Steel, condensate return lines are copper. Yes I will need direct steam injection in the cooker.
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