Brewery Ventilation! 2

[fineartsnyc]

Hi All, I'm designing an exhaust system in brewery warehouse. does anyone know the recommended air changes? my concern is the elevated level of carbon dioxide.
Thanks

 

[Drazen]

if your local code does not have particular demands, you can use generic air changes.

i doubt high level of co2 can be practical issue. co2 diffusion takes place only through PET, but that is quite slow process.

how do you plan for make up air? what you certainly need is filtering of any kind of supply air.

 

[fineartsnyc]

Thank you Drazen. the project located in NYC. the floor area is 5600 SF. i'm using 12 ACH.
1- The heated supply air would be from One rooftop gas fired make up air with VFD and co2 sensor
2- The exhaust thru 3 sidewall propeller fan.

 

[Drazen]

12 ach looks extremely large to me, i had in mind something like 0.2-0.3 ACH...

why would you want so many air changes?

if warehouse contains lot of PET bottles, be cautious with gas fired heaters, PET is very flammable stuff.

 

[fineartsnyc]

Do you think 0.3 ACH is enough? The fermentation process produces a large amount of CO2.

 

[EnergyProfessional]

maybe ask the owner if they have data on CO2 production. I'm sure it is documented somewhere. Or a brewing association has guidelines on ventilation.

i think you have a valid concern with CO2, you might get above 1000 ppm (not sure).

Drazen: why is gas fired bad for flammable products? His "burner" will be in the RTU it sounded like. That RTU likely only will discharge 100-120°F... the same a hydronic coil or nay other heater would. I would understand your concerns if the actual gas-fired unit heater would be int eh space and directly blowing on the bottles, but can't imagine it being that hot unless they put the unit heater right by the bottles.

 

[fineartsnyc]

The Make-up air is on the roof.

 

[Drazen]

fineart,

let us be clear to not waste time on vague assumptions - you clearly specified the space as a warehouse.

is it warehouse of finished products or something else?

 

[fineartsnyc]

sorry. It's a Brewery (production of beer)

 

[chicopee]

Your OP should have been posted in the Local Exhaust Ventilation forum. The threshold limit value (TLV) for CO2 is 5000 ppm ( ppm means parts of CO2 per million parts of fresh air by volume or better stated for example 5000 cu.ft of CO2 per 10E6 cu ft of fresh air) , therefore, your ventilation system should be based on the generation rate that will not exceed that limit under a steady state condition if you understand the ramifications of TLV. By ramification, I mean that the TLV is based on a eight hour work exposure and some employees could be exposed to contaminant levels to more or less than 8 hours which will alter the acceptable contaminant levels.

The American Conference of Governmental Industrial Hygienists use the metric system in their concentration levels and when dealing with parts per million or billion it would be for gaseous contaminants; for solid contaminant levels, the ACGIH express the units in mg/cu.meter so you have to be careful with units when you want to determine air flow in CFM. The ideal equation of state for CO2 is also used. The analysis starts on a mass basis and ends up in volume in the english system. BE CAREFUL ABOUT THE UNITS.

The difficulty is to determine the generation rate of CO2 in the fermentation process. I guess you can use the chemical reaction formula that we were all exposed in high school biology to have a ball park figure in order to have an initial estimate on the amount of fresh air into your brewery.

The attachment involves an elementary analysis as a way to figure out the amount of fresh air. The assumption made is a constant generation rate of the contaminant (CO2 in your case) which we know is not the case with batch process involved in brewing beer. Also the fermentation room volume does not mean the entire cubical volume since the breathing zone to which employess are under is basically limited to their work environment height that would take care of the CO2 property being heavier than air. You probably could install CO2 detectors to initiate and stop the exhaust system instead of having it run continuously.

 

[fineartsnyc]

456.3587 Total pounds of co2 released per day at full capacity. please help how many Air changer per hour required to be exhausted.

 

[Compositepro]

Your understanding of "significant figures" reveals something of your engineering skills. Please consider this a constructive comment.

 

[chicopee]

Per day means what? 4Hrs,8Hrs, 24Hrs of continuous fermentation. Please state the time that it takes to complete the fermentation that produces CO2 during the batch process.

 

[MintJulep]

The CO2 generation is not likely produced uniformly throughout the space.

So why ventilate the entire space based on a localized space?

Vent at the source with local make-up. Ventilate the bulk of the space for comfort.

 

[fineartsnyc]

Per day means 24 hours of continuous fermentation.  > 95% of the CO2 produced during fermentation is released in the first 4 days.

 

[chicopee]

Based on the information that I provided you, you'll need a ventilation rate of at least 33,845 cu.ft./hr under steady state conditions. Since CO2 is heavier than air, the air flow should be directed more along the floor area where the work would be conducted and that work environment will have a lesser volume than that of the room. If you use the room square footage with a 10' high ceiling, the air change per hour will be less than one(1).

 

[pipesnpumps]

This conversation focuses on CO2, but there are so many more variables.. There is steam, there is the amount of combustion air drawn into the room if it is a direct fired boil kettle. There are chemical fumes from cleaning (caustic, phosphoric acid, possibly iodine).

Treat it like you would a kitchen / food prep area. Exhaust part of hte air from down low to get the CO2, exhaust part from near ceiling, to draw out steam/water vapor, and VOCs from hops, yeast, grains.



Real world knowledge doesn't fall out of the sky on a parachute, but rather is gained in small increments during moments of panic or curiosity.