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A few questions on Boilers

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On 11/26/2019 at 7:59 PM, Backset said:

As I have been trying to educate myself on boilers, a few questions have come to fruition that I can't seem to find an answer for. I was hoping some folks who have been down the road of purchasing a boiler would know the answers. 

#1: Is a blow down separator necessary? From my understanding it seems like an integral part for maintaining safety within the still house/boiler room. 

#2: What is the ball park installation cost of a boiler? We are looking at a 60 HP boiler.

#3: Opinions on Sellers or ? These are the two manufacturers we have narrowed it down to. I like that Sellers doesn't need any chemical treatment, but I like the footprint and the 5:1 turndown of the Aldrich better, vs. the 3:1 turndown on the Sellers.



#2 I got a quote for $47k for the 50bhp Sellers H-series installed from their local rep.  I expect their 60hp is ~10% more with similar installation costs.

#3.  Sellers H-series for direct steam injection.  You MUST soften the water well to prevent scaling, but you don't need to add chems to reduce O2 & raise pH as there is no ferrous metal in the H-series boiler.

I agree the limited turndown on the Sellers is a headache.  Aldrich got my consultant's "thumbs up" as well.   I must say the Miura's look very fine, but I would imagine corrosion could be a problem if you run them with RO-water and no chems.


There are broadly 3 classes of steam ...


and if you think you can put in a screen and convert plant steam to culinary steam, then you are on the wrong side of the FDA.


The FDA approved chems seem to cost  4x or more than typical boiler chems.   Given the high blow-down rates on DSI systems, the chem cost is significant over time.

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The watchman unit noted is simplex and redundancy is needed as in 2 pumps. When a single pump system fails, you are DOWN.

This requires that you have a receiver AND a return station which is an extra expense and an extra point of failure when both can be done in one package as I have shown for small systems.

Receivers are not controlled in the same way return stations are. They are set up differently. You also need isolation capability on each pump [both electrical and mechanical] of a duplex unit so you can run on one if you have to. The best thing is to get the OEMs and return station-receiver builders into some kind of accord on dimensions that are practical in the field which would not really be that hard as I have also shown working with Silver State Stainless on recent projects. They were happy to build to a higher outlet dimension with no problems at all. It just has to be asked for. The simpler things can be kept, the more reliable they will be. Redundancy is just as it sounds and Mechanics like it six ways to Sunday. For sure it can be done as you are describing, but this would not be my choice or recommendation.

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14 hours ago, Skaalvenn said:

Not sure if I'm following this all correctly, but we just have our condensate plumbed into a receiving tank with a float switch that then pumps it back to the condensate tank next to the boiler?  Same unit that Silk posted an image of.

Our still is against a wall, and the tank is on the other side of the wall, so it's about as explosion proof as you can get.



You can see here what we are dealing with.  Note the messy floor around all that stuff. 


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Sorry to be late responding, I don't log on that often these days...

Regarding the OP:

item 1) blow down separators, there are several "blow down" points on a boiler, so more info is needed to give a thorough answer. Having said that, the purpose of a separator is to separate the flash steam from the remaining liquid and give each of them a safe (not in your face) place to vent up (steam) or drain (liquid).  Most distillery boilers are really small capacity (relatively speaking) and low pressure so the amount of flash is less of a concern.

item 2) Install cost. Local codes vary widely and they will significantly impact cost.  Rough rule of thumb the same as the new boiler cost.

item 3) I'm not familiar with either brand but a quick look at their web pages and they both seem fine.  The 3-pass, wet-back fire-tube (scotch marine) design is rock solid.  properly matching the boiler to the process load and properly sizing the distribution piping is very important. If the boiler is over-sized for the load even the highest turn-down ratio burner will not correct the issue.  Don't walk but run away from anyone who touts that any boiler requires no water treatment.  This is simply untrue regardless of your source-water circumstance, including RO.  Even if your system & piping are properly cleaned & passivated prior to service and you get a very high % condensate return, (hint these are important) there will be make up water required.  There will also be periods that the boiler is turned off.  Both of these situations require scale & corrosion inhibitors (water treatment).  Modern H2O treatment can be food grade & kosher and will pay for itself in extending the life of your equipment.  If you ever see red rust in the condensate of a boiler system you have (or eventually will have) big problems.

Edited by Beach Time

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