Neutralizer-Scrubber of acidic fumes & gases

[Lou]

I will test it in a few weeks after I'm back from paternity leave.

We will take a weighed piece of copper of known surface area, say 4"X4"X1/4" and load into 500 mL 70% w/v nitric acid, so that it is strictly a NO2 forming reaction. We will weigh the copper piece every five minutes, 12 X, until an hour has passed. This will determine the moles of NO2 formed. You can approximate the volume from the ideal gas law, or correct it as appropriate.

We will measure volumetric output from the exhaust port with our anemometer. We will take a 1 L sample of gas and conduct analysis for ppmv of NO2.

 

[Viy]

Have arrangements been made to provide a unit for testing? I see from this thread that there are members willing to do this for you.

4metals - I think that Noxx volunteered to test the new and improved version of this scrubber.
I am not into gold-filled or sterling refining, so I am no help there.

I am very sorry you did not find opportunity to test the device. Your participation in the debate, as in the air purification specialist and opponent, gave me ability quickly to upgrade design of the device (see Fig.). I am convinced that as a result of your tests, the Kit can be done even better and easier to use.
The device is ready to ship and "is waiting" of your decision. Of course, it's not necessary to return the kit. Everything is free.

I will ship Noxx another Kit for testing (everything free) when I get necessary component parts, that I've already ordered.

Please, reconsider your decision.

Sincerely, Viy

 

[glorycloud]

Do you accept "trade-ins" on unused older versions like the one I purchased? 8)

 

[Viy]

Viy,

I'm willing to give it a shot. If you're willing to ship your system to Canada free of charge I will test it in various conditions.

Thank you for your participation in the discussion of the design of neutralizer-scrubber to capture vapors and gases at refining.
During the discussing design of Neutralizer, opinion of GRF was unanimous: for safety reasons, the exhaust after the motor must be removed from the work area.
It was felt that the proposed Device replaces a fume hood in professional workshops. It is not right. Nothing can be better and safer to work in a fume hood. In my opinion, the device is an additional tool for refiners-professionals. For example, what if fume hoods are busy, but it is necessary to process a small batch of scrap, or perform procedures not associated with neutralization NOx but requiring exhaust vent (see below)?
I made a modification (see pic.) and have already experienced hydrodynamics of neutralizer in air-water system at extreme loads. In my opinion, depending on options, represented design is suitable for both amateurs and professionals. By degree of process safety there may be various options of the design (e.g. 2-3).
The modified device consists of two identical interchangeable sections (conditionally basic and supplementary), connected by a transparent plastic reinforced flexible hose. At peak load, when the reaction can get out of control at a unskilled service or violation of technology, brown gas will be visible in the connecting hose. Then the second additional section begins to absorb gases and to «support» the first one.
Moreover, alkalinity falls in both apparatuses at different speeds. Let's say you did not do a simple test with indicator paper and did not check alkalinity in both sections of the neutralizer.
Later on at process it was found that concentration of alkali in the first section is low, it does not work well and is visible brown gas in the connective flexible hose. In this case, neutralization of vapors and gases will occur in the second, additional section of the neutralizer.
For economical use of lye, the primary and secondary unit can be interchanged. In addition, the alkaline solution can be exchanged for new in one apparatus only.
Neutralizer has two motor sections (see pic). One of them is provided with a 5 or 10-m the flexible hose. During operation, it can be removed outdoor. To overcome resistance of 10 meters of corrugated flexible hose, it was necessary to install a more powerful motor (7a instead 2a). Due to the vacuum in the system, when operating the motor at full power and / or temperature conditions, it can cause collapse of 5-Gal bucket of durability 90 mil. It is not dangerous and easy to remove, if you put the motor section in an additional bucket (bucket-in-bucket). Note collapse does not occur at lower workloads.
So, if you:
- Load the reactor above the permissible loading
- Are not able to manage the process of metal dissolution at Refining
- Did not pay attention to that concentration of lye solution in both sections of the neutralizer is already below the minimum
Then fumes will go into the motor compartment of the device, which is on the outdoor. Of course, the motor will not be able to operate a long time in an acidic environment and gradually (not directly) has to stop. Therefore, an additional reserve motor section is provided. It's advisable to install this section next to the Device. Why?
Unfortunately, members of the GRF did not notice that the neutralizer is a universal unit. For example, when using the Device (not in a fume hood), refiners would be able:

- Process filings in Muriatic acid to remove iron
- Precipitate metal with zinc in platinum and palladium refining
- Capture sulfur dioxide gas at sodium metabisulphite treating
- Boil (!) sweeps in concentrated lye to remove abrasive material
- If you replace lye solution for acidic one, in some cases refiners would be able to work with ammonia at washing of diamonds from silver oxide without the hood.
Experienced Refiners can continue this list.
In addition, at refining some type of Gold waste (e.g., Gold filled nylon filters) there is a characteristic smell of nitro compounds. Then you should use the motor compartment, remote from the working space.
Thus, the two motors can be operated alternately depending on the task. Motor blocks can be switched using 3/4 in. PVC Slip Ball Valve, mounted on one sections of the neutralizer (see. pic).
What if there was a power failure. This problem is solved by using UPS. In our case, you need to purchase, for example, "APC BR1500G Back-UPS Pro with BR24BPG External Battery Pack" or simply "APC BR1500G Back-UPS Pro 1500VA 10-outlet Uninterruptible Power Supply". Then during a power failure, 7a motor will continue to run for at least 10-15 minutes. That's enough to dilute the reaction mixture in twice with cold water and prevent the gas emission after stopping the motor. (Since the reactor is under a weak vacuum, it is not dangerous to open it).
The device is ready to ship and I wait your decision. Of course, it's not necessary to return the kit. The Device and shipping are free.

Thank you again. I look forward to hearing from you very soon.
Sincerely,
Viy

 

[Barren Realms 007]

There is a device made called an automatic vent that is used in plumbing that you might want to check on incorporating into your system to keep from creating such a vaccume that will collapse your buckets.

 

[Viy]

-how is that one going to efficiently remove all NOx gasses when there isnt even a tight seal between the coffee pot and the above chamber _1.JPG

I agree that the reactor design of $10 looks ridiculous, but it is thought over. Do not forget that the system is under a weak vacuum. At processing, you can open silicone plug, add chemicals or stir. Gases can not go out the reactor, and air can enter only. It is possible, that additional air, which is sucked through the reactor leaks, helps oxidation NO in NO2 in flexible hose. Unfortunately, here I am not an expert.

 

[Topher_osAUrus]

-how is that one going to efficiently remove all NOx gasses when there isnt even a tight seal between the coffee pot and the above chamber _1.JPG

I agree that the reactor design of $10 looks ridiculous, but it is thought over. Do not forget that the system is under a weak vacuum. At processing, you can open silicone plug, add chemicals or stir. Gases can not go out the reactor, and air can enter only. It is possible, that additional air, which is sucked through the reactor leaks, helps oxidation NO in NO2 in flexible hose. Unfortunately, here I am not an expert.

You are using silicone for the seal? Or another type of epoxy/resin?

http://www.engineeringtoolbox.com/silicone-chemical-resistance-d_1879.html

There it states that silicone is conditionally resistant to nitric acid at only 10% concentration, and at "concentration" (I'm going to assume azeotrope) it is not resistant. So at that point you could very well experience failure. Maybe not the first run, or the 5th, but eventually, it will give way.

 

[Viy]

I will test it in a few weeks after I'm back from paternity leave.

We will take a weighed piece of copper of known surface area, say 4"X4"X1/4" and load into 500 mL 70% w/v nitric acid, so that it is strictly a NO2 forming reaction. We will weigh the copper piece every five minutes, 12 X, until an hour has passed. This will determine the moles of NO2 formed. You can approximate the volume from the ideal gas law, or correct it as appropriate.

We will measure volumetric output from the exhaust port with our anemometer. We will take a 1 L sample of gas and conduct analysis for ppmv of NO2.

I totally agree. We'll have to get input and output concentrations NO2 at standard test conditions and compare them with Maximum permissible concentration NO2 in indoor air. This data may be used in the future.
I think for testing, the base model of neutralizer is suitable: one reactor, one apparatus, and one motor compartment. Of course, I could ship full Kit designed for refiner-dilettantes. Let me know about your opinion.
Because a motor used in the design, does not have a exhaust pipe (see pic), I will fasten funnel as air sampler (see pic). Please evaluate how it will be convenient to take air samples or give suggestions how do it.
Notify me your shipping address via private message. Of course, all free of charge. You should return nothing.

Thank you very much in advance

 

[Viy]

You are using silicone for the seal? Or another type of epoxy/resin?

http://www.engineeringtoolbox.com/silicone-chemical-resistance-d_1879.html

There it states that silicone is conditionally resistant to nitric acid at only 10% concentration, and at "concentration" (I'm going to assume azeotrope) it is not resistant. So at that point you could very well experience failure. Maybe not the first run, or the 5th, but eventually, it will give way.

Please understand: the system is under vacuum. Silicone stopper is in air, not in acid and even not in its steam. The plug is washed by air. Maximum that maybe is change silicone color on yellow.
If you are seeking my advise, make refining process under weak vacuum: you can manage the process without its stop (add chemicals by parts, stir, take sample).

 

[Palladium]

God knows i'm trying to be constructive in my responses to this thread, but..........
I swear i can't wait to see what you stick on this thing next! :mrgreen:

 

[Lou]

Also send instructions on scrubbing solution (concentration, volume used, etc.)

We can test with plain caustic, peroxide then caustic (nitric duty only, as halides catalyze peroxide decomposition per Cl<Br<<I), and reductive mixes. Of those, plain caustic performs the least.

We can also use what I consider to be the gold standard in NOx scrubber solution, BioNox Solver. That solution I like better than the NaOH/NaHS solution we used to use.

 

[glorycloud]

Hmmmm. I want to try and setup my air "purification" system so that I can run this material
in AR. The only way I will attempt this indoors (as is the claim of the seller) is because
I will do it in a warehouse with 30 foot ceilings. I'm having trouble reading and understanding
the "instructions" though. I have reached out to the seller for help. I'm not interested in setting
this "air purifier" system up incorrectly and attempting it's use indoors without knowing that it
is hooked up right!

I really do hope that it will work as described here and on ebay. It would help me refine some other
material that I have as well. 8)

 

[glorycloud]

OK, the seller did email me the updated instructions for the scrubber that was shipped to me
that finally make sense of what I received. Let me try and get it assembled and functional soon.

 

[Damien]

What was the outcome? Any?

 

[glorycloud]

I decided to send off this e-scrap to tndavid who graciously refined it for me.

I still have this unused scrubber here. Just waiting to get brave and try it out. :lol:

 

[Damien]

Will you all help me with the physics/math for redesigning this scrubber?

 

[Damien]

I think I understand how it works, so if 8 seconds contact time is required, what about this system but a 55 gallon drum with 3-5 tall cylinders inside, draw the fumes through each one in a row, one by one?

 

[Damien]

The vacuum to be replaced, with a proper pump/blower...

Fumes go from processing unit, to 55 gallon drum, enters first cylinder, bubbles up, moves to second cylinder, bubbles up, moves to third, bubbles up, and exits the drum via vent cap, where testing of fumes can take place.

The drum becomes the scrubber unit.