# Depopulating Fumes



## Liquidau (Nov 15, 2022)

I’ve seen lots of scrubber designs and suggestions for fume hood scrubbing of acid fumes, but can’t find anything about capturing and treating the fumes coming off a PCB depopulating machine. 

Can an expert please weigh in and advise the general design specs for this? Thanks in advance.


----------



## Yggdrasil (Nov 15, 2022)

Liquidau said:


> I’ve seen lots of scrubber designs and suggestions for fume hood scrubbing of acid fumes, but can’t find anything about capturing and treating the fumes coming off a PCB depopulating machine.
> 
> Can an expert please weigh in and advise the general design specs for this? Thanks in advance.


What size are you talking about?
Gas or electric heating?


----------



## kurtak (Nov 15, 2022)

Most of the fumes coming off of circuit boards when heating them to depopulate them are likely in the forum of dioxins & furans & you should be able to destroy them by running them through an after burner (rather then a scrubber)

Temp & retention time & oxygen need to be considered to insure the destruction of the dioxins & furans

other wise (I believe but could be wrong) activated carbon column for scrubbing 

Kurt


----------



## stoneware (Nov 15, 2022)

Liquidau said:


> I’ve seen lots of scrubber designs and suggestions for fume hood scrubbing of acid fumes, but can’t find anything about capturing and treating the fumes coming off a PCB depopulating machine.
> 
> Can an expert please weigh in and advise the general design specs for this? Thanks in advance.


The fumes coming off PCB boards during Pyrolysis are flammable, during the world war when uel was rationed the gas produced from a gasifier was used to operate bus's, tractors and automobiles.

Coal gas

Charcoal.

The residue ( ASH ) left behind after Pyrolysis is what your after.

Here's a report paid for by Uncle Sam.

This handbook has been prepared by the Solar Energy Research Institute under the U.S.

Department of Energy Solar Technical Information Program. It is intended as a guide to the design, testing, operation, and manufacture of small-scale [less than 200 kW(270 hp)] gasifiers. A great deal of the information will be useful for all levels of biomass gasification.

The handbook is meant to be a practical guide to gasifier systems, and a minimum
amount of space is devoted to questions of more theoretical interest.


----------



## stoneware (Nov 15, 2022)

Wikipedia, Wood Gas is a fuel gas that can be used for furnaces, stoves, and vehicles. 

During the production process, biomass or related carbon-containing materials are gasified within the oxygen-limited environment of a wood gas generator to produce a combustible mixture. 

In some gasifiers this process is preceded by pyrolysis, where the biomass or coal is first converted to char, releasing methane and tar rich in polycyclic aromatic hydrocarbons.


----------



## Yggdrasil (Nov 15, 2022)

stoneware said:


> The fumes coming off PCB boards during Pyrolysis are flammable, during the world war when uel was rationed the gas produced from a gasifier was used to operate bus's, tractors and automobiles.
> 
> Coal gas
> 
> ...


I do not think he pyrolize it, just heat for depopulation, they are foul smelling but not very combustible fumes.
The reason I asked him about how much and how he heat the “depopulator” is that if it is gas/fuel heated one can use a fan and feed it back into the burner and extend the exhaust and such get enough heat retention time and air to decompose them properly.
We’ll have to wait until he chimes in again.


----------



## Liquidau (Nov 15, 2022)

Thanks for the quick answers, guys, I posted and then barely had time to get to the lab and make a coffee!

It is an electric heating depopulating machine, 220vac, a horizontally mounted cylinder of about 3 ft diameter (1m) x 4 ft (1.3m) long. It heats the entire boards to between 259C and 300C, thereby melting the solder, and the chips (and everything else) fall off by gravity and are collected in sized screens at the base. 
So not hot enough to cause pyrolysis but from what I’ve read here and there, not the sort of fumes you want to take in.


----------



## Yggdrasil (Nov 15, 2022)

Liquidau said:


> Thanks for the quick answers, guys, I posted and then barely had time to get to the lab and make a coffee!
> 
> It is an electric heating depopulating machine, 220vac, a horizontally mounted cylinder of about 3 ft diameter (1m) x 4 ft (1.3m) long. It heats the entire boards to between 259C and 300C, thereby melting the solder, and the chips (and everything else) fall off by gravity and are collected in sized screens at the base.
> So not hot enough to cause pyrolysis but from what I’ve read here and there, not the sort of fumes you want to take in.


How much do you depopulate a day?


----------



## Liquidau (Nov 15, 2022)

I will only be receiving it in 2 weeks. It is rated for 100-200 kg of boards per hour, so I expect to do 500-1000 kg/day initially, then probably ramp up to 1,500 or so. 
This is located within a warehouse with a 15 ft ceiling, and perhaps 10 ft from an outside wall.


----------



## Yggdrasil (Nov 15, 2022)

Liquidau said:


> I will only be receiving it in 2 weeks. It is rated for 100-200 kg of boards per hour, so I expect to do 500-1000 kg/day initially, then probably ramp up to 1,500 or so.
> This is located within a warehouse with a 15 ft ceiling, and perhaps 10 ft from an outside wall.


Then I'd expect that you will need to run a full scrubber column of kinds.
There are many here with this kind of insights.
Did you read the fume hood/scrubber threads?


----------



## Liquidau (Nov 15, 2022)

Yes, but as mentioned at the start, everything I've seen is for acid fumes/refining/NOx/SO2, which typically involves bubbling the emissions into NaOH solutions, also H2O2, activated charcoal, etc. My lab fume hood is a good quality Labconco. I'm looking to ensure proper control of any gasses coming off of this depopulator.


----------



## stoneware (Nov 15, 2022)

Liquidau said:


> Thanks for the quick answers, guys, I posted and then barely had time to get to the lab and make a coffee!
> 
> It is an electric heating depopulating machine, 220vac, a horizontally mounted cylinder of about 3 ft diameter (1m) x 4 ft (1.3m) long. It heats the entire boards to between 259C and 300C, thereby melting the solder, and the chips (and everything else) fall off by gravity and are collected in sized screens at the base.
> So not hot enough to cause pyrolysis but from what I’ve read here and there, not the sort of fumes you want to take in.


Do you refine the solder.


----------



## Yggdrasil (Nov 15, 2022)

Liquidau said:


> Yes, but as mentioned at the start, everything I've seen is for acid fumes/refining/NOx/SO2, which typically involves bubbling the emissions into NaOH solutions, also H2O2, activated charcoal, etc. My lab fume hood is a good quality Labconco. I'm looking to ensure proper control of any gasses coming off of this depopulator.


If you use a fan to push the gases through a column with spray jets and balls/fillers it should be good,maybe.. 
Correct me if I'm wrong guys.


----------



## Liquidau (Nov 15, 2022)

stoneware said:


> Do you refine the solder.


I'm open to it, but don't care about it at this time, so i'm not focusing on that. The solder will be collected and either sold or refined down the road.


----------



## stoneware (Nov 15, 2022)

Liquidau said:


> I'm open to it, but don't care about it at this time, so i'm not focusing on that. The solder will be collected and either sold or refined down the road.


The attached document maybe of interest to you, lead free solder.


----------



## kurtak (Nov 16, 2022)

Yggdrasil said:


> If you use a fan to push the gases through a column with spray jets and balls/fillers it should be good,maybe..
> Correct me if I'm wrong guys.


He is NOT dealing with acidic fumes (as I mentioned yesterday) he is dealing with non-acidic gasses (dioxins & furans &/or other "gasses")

IMO - the best way to destroy those gasses is an afterburner - MAYBE - activated carbon column (dry filter/scrubbing) 

Afterburner &/or carbon column could be mounted directly over the depopulating device (less floor space) 

Wet scrubber would require a blower to blow fumes/gasses over to the wet scrubber (more floor space) 

Kurt


----------



## Yggdrasil (Nov 16, 2022)

kurtak said:


> He is NOT dealing with acidic fumes (as I mentioned yesterday) he is dealing with non-acidic gasses (dioxins & furans &/or other "gasses")
> 
> IMO - the best way to destroy those gasses is an afterburner - MAYBE - activated carbon column (dry filter/scrubbing)
> 
> ...


I noticed yesterday, but will a scrubber not remove the gases by absorbing them and thus keeping them out of the exhaust system?
An afterburtner would of course be the best path, but might be more expensive to run?
Won't an afterburner also need a fan?


----------



## stoneware (Nov 16, 2022)

Liquidau said:


> I will only be receiving it in 2 weeks. It is rated for 100-200 kg of boards per hour, so I expect to do 500-1000 kg/day initially, then probably ramp up to 1,500 or so.
> This is located within a warehouse with a 15 ft ceiling, and perhaps 10 ft from an outside wall.


I see other issues, if the depopulator machine is not CSA approved your insurance policy could be voided and this could possibly affect your lease.

That out of the way, what does the manufacture recommend.




.


----------



## Liquidau (Nov 16, 2022)

The supplier makes a wide range of equipment for pcb recycling, from grinding up boards to sorting and sieving to incinerating and refining. So they have spray towers with UV catalysts, and activated carbon as well. 
I’d like to properly and safely manage the fumes coming off of this depopulator. Since dioxins aren’t water soluble, looks like activated carbon and/or incineration are the way to go. I would appreciate confirmation of this and advice on whether my IC chips incinerator can be used here by piping in these fumes to it, or should a separate incinerator be used for this….?


----------



## Yggdrasil (Nov 16, 2022)

Liquidau said:


> The supplier makes a wide range of equipment for pcb recycling, from grinding up boards to sorting and sieving to incinerating and refining. So they have spray towers with UV catalysts, and activated carbon as well.
> I’d like to properly and safely manage the fumes coming off of this depopulator. Since dioxins aren’t water soluble, looks like activated carbon and/or incineration are the way to go. I would appreciate confirmation of this and advice on whether my IC chips incinerator can be used here by piping in these fumes to it, or should a separate incinerator be used for this….?


Temperature and retention time is the factors that count I think.
I do not have the numbers for that, but maybe someone can share?


----------

