Upgrades to existing flat pan?

[Cloverland Maple]

I'm looking to do a few upgrades (by replacement) to the syrup pan. The upgrades would be to 304 stainless steel and possibly the design of the pan. We're contemplating constructing a new pan, or making a purchase, but wanted to get some feedback. I'm hedging my bet that several of you have upgraded from a similar set up. Looking for your suggestions and recommendations during this market research phase.

Some info to illustrate our current setup:

The current pan is a 3x7 flat pan over a wood fired arch. We boil in batches - usually 500<400 at a time. Our evaporation rate is about 25 gallons per hour. A 400 gal batch takes us 15-16 hours. When we pull the pan, we have 10-13 gallons of syrup. This is less than 1" depth across the entire pan. Obviously, we have to move fast when the syrup is to density as we boil to finish, and we have a system to pull the pan from the arch and then immediately draw the syrup.

I'd rather not have to make major modifications to the arch. I understand there are flue, continuous flow and flat pans. All else staying the same, which pan design would give us an increase to the evaporation rate? Would you change the style of pan? Are there added risks with different styles?

Note: Regarding overall efficiency, I'm in the beginning phase of building an RO system. I'll probably be asking a few questions in a separate thread.

Thanks!

Haynes Thompson

[berkshires]

I understand there are flue, continuous flow and flat pans. All else staying the same, which pan design would give us an increase to the evaporation rate? Would you change the style of pan? Are there added risks with different styles?

You probably know this, but just to get the conversation started...

Regarding pan styles:
- Flues will give you a big increase to the evaporation rate. Like double or triple the rate for a pan of a given size. Continuous flow will not.
- Continuous flow will allow you to draw off smaller batches of finished syrup with much more frequency. It will also produce slightly lighter syrup. It won't change a Dark/Robust into Golden/Delicate, but it might make a borderline syrup shift over the border into the next lighter grade.

As for modifying your existing pan, I'd think twice about it. Welding or soldering thin stainless is hard, and especially hard to do without warping it. On the other hand, a new pan the size of your arch will cost a lot. A compromise might be to add drop tubes to your existing pan. Trouble is, if you screw something up, there's no going back - you have to either make it work, or buy a new pan. Might not make sense to try this late in the game this season.

Other folks surely say more about continuous flow - I've only seen it done, never done it myself.

Good luck!

[Cloverland Maple]

Thanks for the feedback.

The stated increase to the evaporation rate with a flue style pan has my eyes getting big. Wow. That would be quite the improvement. We currently don't have a steam hood, although we have good upward draft; seems a hood might be needed with the increase to the evaporation rate. Does anyone have an experience with fabricating their own flue pan? With such an increase to the evaporation rate, it may be more cost effective to modify the arch to fit a smaller pan. Don't know for sure until I put pencil to paper...

And just to clarify, I don't have any intention of modifying the existing pan. The upgrade would be by replacement - just trying to figure out which is the best route.

Interesting factoid regarding the syrup grade with the continuous flow. The past several years we have only been able to produce Delicate syrup with the flat pan. It's been a little bit since we've even had rich taste.

[NhShaun]

If you are planning to build an RO, perhaps a continuous flow pan would be a good option compared to the flue pan. I used to batch boi before i had my flat continuous flow pans made, not sure If I could go back to the old ways at this point, at least not in the syrup pan.

[berkshires]

Thanks for the feedback.

The stated increase to the evaporation rate with a flue style pan has my eyes getting big. Wow. That would be quite the improvement.

Keep in mind that you don't want your whole pan to be flue-style. You still want a syrup pan that's flat (even if it has dividers, it's still basically flat). So the higher boil rate would only apply to your flue pan. The front pan would still see the same boil rate you get now over that area. In other words, just for an example, let's say you split things up exactly evenly with a back pan that's 3.5 x 3 and a front pan that's also 3.5x3. If they were both flat and you got your 25 gals/hr, you would be getting something like 12.5 GPH on each. If you then replaced the back pan with a flue pan and got 2 times the boil rate on that pan, you would then get 25 GPH on the back pan, and 12.5 GPH on the front pan. So you'd only actually wind up with a 50% improvement in boil rate.

Does that make sense?

[Cloverland Maple]

If they were both flat and you got your 25 gals/hr, you would be getting something like 12.5 GPH on each. If you then replaced the back pan with a flue pan and got 2 times the boil rate on that pan, you would then get 25 GPH on the back pan, and 12.5 GPH on the front pan. So you'd only actually wind up with a 50% improvement in boil rate.

Does that make sense?

Yes, it sure does. Thanks.

[Cloverland Maple]

If you are planning to build an RO, perhaps a continuous flow pan would be a good option compared to the flue pan.

Could you please explain why? I'm making an assumption that the RO can feed the flow at nearly the evaporation rate, if calibrated. We'll likely RO and store, albeit it would only be for a few hours.

I used to batch boi before i had my flat continuous flow pans made, not sure If I could go back to the old ways at this point, at least not in the syrup pan.

What are your reasons? Is your evaporation rate significantly better? Is it easier to manage? (I imagine it is easier to manage the gradient when thinking in terms of thermodynamics, but I've never used anything other than a flat plan). Pretend I know nothing.