fume scrubber vacuum pump

[bigpagoda]

Hello all,
I am beginning to devise plans for a multi-stage fume scrubber similar to the one posted by phildreamer (I think). I am using a 2000ml reaction chamber but may want to go up one day. I will be using 6" PVC approximately 66 inches high with a fogging atomizer in the top above the packing in the first two stages.(but I don"t know what to use) I am thinking I should go with a 3 CFM diaphram style pump so it will hold up better under the corrosive fumes- Or should i just cheap out and buy a used one and let it burn up. I am going to have the vacuum exhaust into the air stream from my fume hood just before it goes outside to help diffuse any residual vapors. I've looked at a lot of posts about fume scrubbers but am still not sure if my plans are on the right track.
To clarify what I am asking:
1. is a diaphram style pump the best way to go.
2. How am I sure 3cfm is the right size
3. What do I use for packing
4. does any of what I said sound right
Any recommendations or observations would be appreciated.
Thanks

 

[fishstick]

I use a diaphragm style high pressure self priming pump and and spray nozzzle (the pump is connected to an on/off switch). I simply suck the gas to a collection vessel and turn on the mist. The rate at which you mist depends on the gas you create. Nitrogen dioxide is incredibly reactive with water. Simple experiment put 200 ml of water in a 1 L flask, pump in NO2 gas and seal the flask - then swirl flask and observe the water absorb the gas. After you observe that, that may determine how to set up your "scrubber"

My point is how you set up your vessel really is up to your imagination/needs but what's important is:

1) vacuum pressure - to keep the gas being "sucked in" to the vessel and not allowing it to escape. I can't say 10 CFM, 100 CFM, etc. because I don't know what the volume of gas is you will create. YOU need to determine the wt of product, whether that is 20 grams, 200 grams or 2,000 grams because the if you design a system to solve for the gas for 100 gm production run and then do more, your vessel even if correct will fail.
2) correct sealant - to ensure no gas can escape when it's in vessel.

To me, nitrogen dioxide gas gets a bad rep on this board as it is seen as a villian and needs to be neutralized, etc. In a way, it's ironic that the board is about precious metal recovery when the the nitrogen dioxide can be recovered as well. How? (see below)

3NO2 + H2O(l) ---> 2 HNO3 (aq) + NO(g)

Nitric acid is formed by reacting NO2 with water (in scrubber vessel). The NO produced by this disproportionate reaction reacts with air to form more NO2 which, in tern, reacts with water. Most of the nitric acid produced can be reacted with ammonia to form ammonium nitrate for use as a fertilizer.

***personally, I use a 100 PSI, 4L/min pump and suck the gas into a 5 gallon bucket with 1) hand held vacuum and 2) 100 CFM HVAC in-line fan. I then mist water from the bucket to the gas and recycle that route. Afterwards, I neutralize with NaOH to 8-10 and discard down the drain - since I do small runs and don't create enough to liquid in the bucket to make a decent amount of fertilizer --- BUT I could***

Hope that helps

 

[pwm97128]

I am using a water trap to absorb NO2 from Poor Man Nitric reactions. I plan to store the scrubber solution until I have a gallon or so and then reduce the solution by 2/3s or more using evaporation.

My estimates are that the Scrubber Solution will be 5-8% before evaporation. Hopefully the resulting solution will be 20% HNO3 and suitable for use with Silver.

I recognize this will be a dirty solution and highly variable in strength.

Are there any obvious flaws to my proposed process?

Using evaporation, will the yield expected be significantly less than projected?

Other than peroxide, should I add anything to the water in the trap to increase the recovery of NO2 from the reaction?

Thank you for your suggestions and comments.

 

[Yggdrasil]

I am using a water trap to absorb NO2 from Poor Man Nitric reactions. I plan to store the scrubber solution until I have a gallon or so and then reduce the solution by 2/3s or more using evaporation.

My estimates are that the Scrubber Solution will be 5-8% before evaporation. Hopefully the resulting solution will be 20% HNO3 and suitable for use with Silver.

I recognize this will be a dirty solution and highly variable in strength.

Are there any obvious flaws to my proposed process?

Using evaporation, will the yield expected be significantly less than projected?

Other than peroxide, should I add anything to the water in the trap to increase the recovery of NO2 from the reaction?

Thank you for your suggestions and comments.

Your first objective should be to make sure the output is free from fumes and toxic gases.
Most scrubbers use among other NaOH for that and that will ruin the captured Nitric.
Howe much and how often are you scrubbing?

 

[justinhcase]

I find the KNF Corrosion-resistant PTFE/FFPM flow path pumps to be best.
New they are over my budget, but if you keep your eyes open on eBay you will find them going for as little as £100.
Worth every penny as they will last for years even within our highly corrosive environment.
https://knf.com/en/uk/solutions/laboratory-equipment/details/laboport-n-8403-ft4018

 

[pwm97128]

I use less than 10 pounds of nitrate a month in recovery and refining. I do not have access to concentrated Nitric Acid.

 

[stella polaris]

I am using a water trap to absorb NO2 from Poor Man Nitric reactions. I plan to store the scrubber solution until I have a gallon or so and then reduce the solution by 2/3s or more using evaporation.

My estimates are that the Scrubber Solution will be 5-8% before evaporation. Hopefully the resulting solution will be 20% HNO3 and suitable for use with Silver.

I recognize this will be a dirty solution and highly variable in strength.

Are there any obvious flaws to my proposed process?

Using evaporation, will the yield expected be significantly less than projected?

Other than peroxide, should I add anything to the water in the trap to increase the recovery of NO2 from the reaction?

Thank you for your suggestions and comments.

Just got an crazy idea when reading this.

NO2 is a little magnetic. Could it be possible to drag down the NO2 into the water, with neodynium magnets? Perhaps a flat low channel were the water flows over the magnets?

 

[Yggdrasil]

Just got an crazy idea when reading this.

NO2 is a little magnetic. Could it be possible to drag down the NO2 into the water, with neodynium magnets? Perhaps a flat low channel were the water flows over the magnets?

Interesting thought, but the question is how it behaves when in the water and how strong magnets are needed.

 

[stella polaris]

It should behave like in the scrubber I think. Strength of magnets needed should be based on the length of the channel.

 

[Yggdrasil]

It should behave like in the scrubber I think. Strength of magnets needed should be based on the length of the channel.

I would believe a cross section magnetic field would be more suitable and let the channel go horizontally with a small amount of water in the bottom.
With a retention time of 9 seconds it do not have to be very long, if this works.

 

[stella polaris]

Yes, horizontally or almost is what I meant. magnets the whole way. Perhaps a little test could be easy done, in a glass pipe, just to see if magnets would attract the fumes.

 

[stella polaris]

if flowing water the distance between the gas and the magnet can be hold on minimum. Or you have a rack of magnets just under the surface.

 

[ólom]

I use a diaphragm style high pressure self priming pump and and spray nozzzle (the pump is connected to an on/off switch). I simply suck the gas to a collection vessel and turn on the mist. The rate at which you mist depends on the gas you create. Nitrogen dioxide is incredibly reactive with water. Simple experiment put 200 ml of water in a 1 L flask, pump in NO2 gas and seal the flask - then swirl flask and observe the water absorb the gas. After you observe that, that may determine how to set up your "scrubber"

My point is how you set up your vessel really is up to your imagination/needs but what's important is:

1) vacuum pressure - to keep the gas being "sucked in" to the vessel and not allowing it to escape. I can't say 10 CFM, 100 CFM, etc. because I don't know what the volume of gas is you will create. YOU need to determine the wt of product, whether that is 20 grams, 200 grams or 2,000 grams because the if you design a system to solve for the gas for 100 gm production run and then do more, your vessel even if correct will fail.
2) correct sealant - to ensure no gas can escape when it's in vessel.

To me, nitrogen dioxide gas gets a bad rep on this board as it is seen as a villian and needs to be neutralized, etc. In a way, it's ironic that the board is about precious metal recovery when the the nitrogen dioxide can be recovered as well. How? (see below)

3NO2 + H2O(l) ---> 2 HNO3 (aq) + NO(g)

Nitric acid is formed by reacting NO2 with water (in scrubber vessel). The NO produced by this disproportionate reaction reacts with air to form more NO2 which, in tern, reacts with water. Most of the nitric acid produced can be reacted with ammonia to form ammonium nitrate for use as a fertilizer.

***personally, I use a 100 PSI, 4L/min pump and suck the gas into a 5 gallon bucket with 1) hand held vacuum and 2) 100 CFM HVAC in-line fan. I then mist water from the bucket to the gas and recycle that route. Afterwards, I neutralize with NaOH to 8-10 and discard down the drain - since I do small runs and don't create enough to liquid in the bucket to make a decent amount of fertilizer --- BUT I could***

Hope that helps

Could you send a picture? Do not quite understand.

 

[andu]

Now this is interesting, magnets could even deviate a laser, if it was strong enough.
Do you have proper strong magnets? they get stronger if you have one on the other side, and some electrical current might amplify their strenght considerably. There is so much energy getting wasted all around that if you cared you could power them with "green energy" depending how strong you need them.

note: Idk exactly how a scrubber should work but can't the gas be circulated thru water completely? I haven't yet had the need for this headache but day will come.

 

[ólom]

I am using a water trap to absorb NO2 from Poor Man Nitric reactions. I plan to store the scrubber solution until I have a gallon or so and then reduce the solution by 2/3s or more using evaporation.

My estimates are that the Scrubber Solution will be 5-8% before evaporation. Hopefully the resulting solution will be 20% HNO3 and suitable for use with Silver.

I recognize this will be a dirty solution and highly variable in strength.

Are there any obvious flaws to my proposed process?

Using evaporation, will the yield expected be significantly less than projected?

Other than peroxide, should I add anything to the water in the trap to increase the recovery of NO2 from the reaction?

Thank you for your suggestions and comments.

How do you make a water trap for the AR?

 

[Yggdrasil]

How do you make a water trap for the AR?

Vacuum that suck the gas through a liquid.

 

[ólom]

Vacuum that suck the gas through a liquid.

Thank you! How do I create a vacuum in a container so that the gas does not suck out?

 

[Yggdrasil]

Thank you! How do I create a vacuum in a container so that the gas does not suck out?

I think I have already posted a way to do this.
But check the OPs way of doing it.

 

[ólom]

I think I have already posted a way to do this.
But check the OPs way of doing it.

Ok.