Energy Recovery

[pubbrewer]

Does anyone have experiences with waste heat recovery from kettle exhaust stacks or direct fired/ boiler flues. I have heard some points that New Belgium Brewing in Colorado is on top of this but lack details and looking for others that may have retrofitted existing systems from brewpub to midsized micro's. Seems to be the most amount of excessively wasted btu's that could be used for water heating or energy producing through thermal electric generators to keep utilities cost down. I was at a solar conference and came across www.hi-z.com here in San Diego that does some of this.

Thanks for you input and contact info.

Sincerely, Dean Roueau San Diego Brewing Company

[Moonlight]

Sierra Nevada recovers kettle heat, and a presentation on the system was given at last summer's MBAA technical meeting in Chico..

[crassbrauer]

If I'm not mistaken, Sierra Nevada's system is German. Germans are the ones to look to for energy recovery for breweries. See Steinecker, Huppmann, Kaspar-Schulz and the rest of the gang for this.

[Alex T]

hi,

yes, steinecker, etc do heat recovery systems for kettles. in essence they are shell and tube heat exchangers with the vapour from the kettle passing through the hot side, water on the other side.

you need to work out the energy you will save by doing this - in essence take the

(kg of water you evaporate) x (heat of vapourisation, about 2260kj/kg)

this is the energy you can recover during your boil. i would assume you recover about 85% of this heat, as some of the kettle vapour will condense before it hits the heat exchanger. the condensed kettle vapour goes to drain.

with regards to steam boilers, depending on the size, they can be fitted with what's called an "economiser" on the exhaust flue which is typically used to preheat the boiler feed water.

don't know if this helped, but maybe just explains the principle...

cheers,

alex

[gitchegumee]

I studied a German model for kettle exhaust heat reclamation called "vapor recompression". It's a way to add a little energy to extract lots more. Many breweries take advantage of it: http://www.mbaa.com/TechQuarterly/Ab...7/tq87ab08.htm

The "Hi-Z" thermoelectric method doesn't amount to much; the amount of electricity generated is miniscule and it is quite expensive to install.

[crassbrauer]

saving energy

Yes, thermal and mechanical recompression of the steam from wort boiling are possible in breweries, but mechanical is used mostly. The process involves actually increasing the pressure of the steam up to about 1.2 - 1.4 bar and using it to heat something in the brewery, like the wort or whatever else. One way to utilize it would be to have two external calandrias one of which is hooked up to steam from the boiler and the other to the compressed vapor from the wort. After the wort reaches boiling, part of the energy recovered from boiling can actually be used to keep the boil going, i.e. the compressed vapor travels opposite the boiling wort through the second calandria, giving up its energy and then being sent to the waste water treatment plant as liquid, or even through another heat exchanger beforehand to capture the rest of its heat. This method reduces brewery emissions by about 95 %. These only pay for themselves for larger breweries.

As Alex pointed out, however, a shell and tube heat exchanger known as a kettle vapor condenser can be used to capture some of the energy of wort boiling that would normally be lost out into the air. The steam rising from wort boiling is simply sent through tubes around which water is sitting. The only disadvantage is that the area around the brewery doesn't smell so nice, since less of the steam makes it out of the wort kettle. Every brewery should have one, in these days of high energy prices and environmental awareness...

Also as Alex mentioned, Economizers are good, too. As the steam/condensate mix returns to your boiler it is sent through a heat exchanger, capturing some of the heat from the returning steam/condensate for the steam going out.

There are a lot of ways to save energy in a brewery. Europeans do it out of necessity. Energy prices are high here. Plus, there are fewer breweries in the US of a sufficient size (either really big ones or small ones, hopefully that'll change!) that can really make these methods pay for themselves.

[arcangel]

heat recovery

Does anyone have experiences with waste heat recovery from kettle exhaust stacks or direct fired/ boiler flues. I have heard some points that New Belgium Brewing in Colorado is on top of this but lack details and looking for others that may have retrofitted existing systems from brewpub to midsized micro's. Seems to be the most amount of excessively wasted btu's that could be used for water heating or energy producing through thermal electric generators to keep utilities cost down. I was at a solar conference and came across www.hi-z.com here in San Diego that does some of this.

Thanks for you input and contact info.

Sincerely, Dean Roueau San Diego Brewing Company

I have experience of heat recovery from the copper. The best approach is to use a direct heat exchanger, i.e. a fine water spray in a column up which the vapour travels. As an example, if the evaporation of the copper length is 10%, a volume of water equivalent to 70% of the brew length can be recovered at around 200 degrees F. The water flowing from the condenser can be used directly for washdown, the only contaminant being hop oils, or cash washing. If liquor is required to be heated, the paraflow could be used to use the heat from the condenser. The advantage of direct condensers is that they are more compact than the indirect types and still retain efficiency when fouled. I have one customer who ran one for 10 years with no apparent loss of efficiency until that day when the hops choked it completely. During that time he confessed he had not cleaned it!

For boiler flue gas, again you can use water sprays to recover heat. When it comes to indirect heat exchangers, known as economisers, you may have dewpoint problems. This can cause corrosion, especially with liquid fuels that may contain a percentage of sulphur. Heavy fuel oils that not only contain sulphur but sometimes significant amounts of vanadium can be really problematic. Vanadium acts as a catalyst converting sulphur dioxide into sulphur trioxide, which with the help of some moisture, forms sulphuric acid.

Do find someone who can give you good advice.

Regards
Arcangel

[JoeV]

Refrigeration?

In the winter I use the waste heat from the glycol chiller and walk-in cooler for heating.