New scrubber design

[jeneje]

I have built a new scrubber system, It consists of three stages.The bottom stage house’s the soda ash solution, the second stage house’s the packing and the third (top) is the mist spray. I Made a mold ¾” wide and ¾” inch deep, I then used NP1 to form the gaskets use between the sections. To lock the sections in place I used snap fasteners (like the ones used on the old style tool boxes) The boxes are made out of ¾” inch plywood and lined with 1 once fiberglass. My question is what type of packing should I use. I have
Considered ping-pong balls, is there another type that will work better
Or am I good here. Any suggestion would be appreciated.

Thanks
Ken

 

[Geraldo]

Hose clamps are a common "ghetto" packing material in packed columns.

Industrially, little shaped metal pieces called "Raschig Rings" are typically used. These can be purchased, but I am not sure about small quantities. Possibly a manufacturer would be willing to send you some samples?

Another alternative is to use some sort of "structured" packing scheme. This could include things like stainless steel pot scrubbers (pulled apart a bit so it isn't too dense). If you can find it, there are also urethane sponges that are extremely "open cell" or "open weave" - they look like very coarse scrubbing pads or blocks. Of course, these types of packing will cause a bigger pressure drop in your column compared to the hose clamps, but provide a lot more wetted surface area for contact (e.g. higher efficiency). It depends on your column size, design and how much draft you have available through the column.

Best Regards, Gerald

 

[glondor]

I always thought a roll of orange plastic construction/snow fence would make good packing. Just roll it tight enough the hole in the center is closed.

http://www.google.com/imgres?hl=en&sa=X&biw=1000&bih=650&tbm=isch&prmd=imvns&tbnid=KCmklBDRsYEs7M:&imgrefurl=http://jinxu01.en.made-in-china.com/product/EownibmHqGpD/China-Safety-Fence-3.html&docid=SYnNN4GAqJysoM&imgurl=http://image.made-in-china.com/2f0j00TeJtWMQhvfgV/Safety-Fence-3.jpg&w=558&h=600&ei=p7blTr3VIsrqOY--sL0E&zoom=1&iact=hc&vpx=92&vpy=214&dur=11727&hovh=233&hovw=216&tx=105&ty=256&sig=112520310646214166277&page=1&tbnh=129&tbnw=120&start=0&ndsp=15&ved=1t:429,r:10,s:0

 

[jeneje]

Hose clamps are a common "ghetto" packing material in packed columns.

Industrially, little shaped metal pieces called "Raschig Rings" are typically used. These can be purchased, but I am not sure about small quantities. Possibly a manufacturer would be willing to send you some samples?

Another alternative is to use some sort of "structured" packing scheme. This could include things like stainless steel pot scrubbers (pulled apart a bit so it isn't too dense). If you can find it, there are also urethane sponges that are extremely "open cell" or "open weave" - they look like very coarse scrubbing pads or blocks. Of course, these types of packing will cause a bigger pressure drop in your column compared to the hose clamps, but provide a lot more wetted surface area for contact (e.g. higher efficiency). It depends on your column size, design and how much draft you have available through the column.

Best Regards, Gerald

Good morning Gerald, I have a question for you? What do you mean by "how much draft you have" I should not have any, except for the 4" exhaust pipe at the top. Also should i incorporate a pressure gage inside the scrubber.

Thanks
Ken

 

[4metals]

You don't say how deep the packing bed will be but if its 3 feet you're looking at close to 60 gallons. You don't specify how the fume gets into the scrubber, is there a duct entering the bottom? Finally the pump inside the sump is not a good idea as the scrubber is an extreme chemical environment and the pump should be outside for maintenance.

Scrubber packing has been discussed quite a bit on the forum, search "tower packing" and you will get some answers.

 

[jeneje]

You don't say how deep the packing bed will be but if its 3 feet you're looking at close to 60 gallons. You don't specify how the fume gets into the scrubber, is there a duct entering the bottom? Finally the pump inside the sump is not a good idea as the scrubber is an extreme chemical environment and the pump should be outside for maintenance.

Scrubber packing has been discussed quite a bit on the forum, search "tower packing" and you will get some answers.

Hello 4metals thanks for replying, The packing bed will be 3 feet high, the tower is 16 inchs wide 24 inchs deep. There is a 4" duct at the bottom left side of the middle section to allow the fumes to enter the scrubber by a blower on the left side of the fume hood. As for the sump pump, setting it inside the scrubber seemed like the right place for it to me. So now i need to look at options for removing the scrubbing solution out and return it to the mist nozzles.

Thanks

 

[Barren Realms 007]

You don't say how deep the packing bed will be but if its 3 feet you're looking at close to 60 gallons. You don't specify how the fume gets into the scrubber, is there a duct entering the bottom? Finally the pump inside the sump is not a good idea as the scrubber is an extreme chemical environment and the pump should be outside for maintenance.

Scrubber packing has been discussed quite a bit on the forum, search "tower packing" and you will get some answers.

Hello 4metals thanks for replying, The packing bed will be 3 feet high, the tower is 16 inchs wide 24 inchs deep. There is a 4" duct at the bottom left side of the middle section to allow the fumes to enter the scrubber by a blower on the left side of the fume hood. As for the sump pump, setting it inside the scrubber seemed like the right place for it to me. So now i need to look at options for removing the scrubbing solution out and return it to the mist nozzles.

Thanks

On your solution holding tank that your scrubber drains into build a drin on the side of it. Install a diaphram pump on the drain line with a ball valve between the pump and the tank, this is so you can turn the valve off to service the pump, always leave this valve fully open when the pump is running to prevent the pump from loosing it's prime and to prevent cavitation of the pump when it is running. Install a 2nd valve and a pressure guage leaving the pump going to the spray nozzel to regulate the flow of your fluid thru the sprayer and do away with the regulator. The nozzel desighn we used in our evaporation colums that were used to heat up our fluids to evaporate water were made like cork screws.

 

[4metals]

I like to use "True union" ball valves on scrubber pumps, they allow complete removal of the pump for service while retaining liquid levels in the sumps.



The nozzles barren describes are also called spiral nozzles and they are excellent as they don't clog easily.

 

[jeneje]

thanks 4metals & barren, I am going to use the ball valve, i think it will work better for my setup. I built a 2 x 5 x 16 inch deep box to use for my holding tank, i don't know how to figure volum of water but i think it will work. I am taking it down in the morning to be fiberglassed. Will post a pic tommorow nite.

Thanks
Ken

 

[4metals]

To figure volume of water multiply the length by the width by the depth (all in inches) to get cubic inches.

divide by 231 to get US Gallons

If it is available use a vinyl ester resin it holds up to the acid better.

 

[jeneje]

good morning all, I am almost there with my new setup. how do i figure out how many ping-pong balls i will need. The measurements are 24" X 32" x 16" the volume in the area is 53 gallons but i can't find any count of balls for a gallon. How ever i did find on ebay 840 balls for $56.00 i think that is a fair price. Any help here would be greatful.

Thanks
Ken

 

[niteliteone]

Just a rough guess, but I think around 3,500 should fill it prety full :shock:
It's bedtime so I could be off a few.

Tom C.

 

[jeneje]

Just a rough guess, but I think around 3,500 should fill it prety full :shock:
It's bedtime so I could be off a few.

Tom C.

Thanks niteliteone,

Ken

 

[Dr. Poe]

To figure volume of water multiply the length by the width by the depth (all in inches) to get cubic inches.

divide by 231 to get US Gallons

If it is available use a vinyl ester resin it holds up to the acid better.

For round tanks, use Pi times the radius squared, times the height.

 

[Geraldo]

Good morning Gerald, I have a question for you? What do you mean by "how much draft you have" I should not have any, except for the 4" exhaust pipe at the top. Also should i incorporate a pressure gage inside the scrubber.

Thanks
Ken

Sorry Ken, I missed this until now. "Draft" is the common term for how much air flow you have through your tower. Basically - how much "suction" your fan can support. Everything that you put into the column (like packing) causes a pressure drop (a resistance to flow) which either lowers air flow or requires more power from your fan.

I think pressure gages are good ideas. If you measure pressure drop across the scrubber, this will tell you when the scrubber is starting to get buildup or plugging - it is good practice and provides good diagnostic information.

Best Regards, Gerald

 

[jeneje]

Hello all, I have been busy these past few days and wanted to post a few pics up tonite. Note that i'm not finished but 95% done. I still have a few things to do like finish the piping, hardware and glass window on the fume hood, It will be completed by this Friday. I have completly redesigned my lab to work in both summer and winter, I took my 10 x 12 shed and insulated it, installed OSB on the walls, painted it and then begain to design my scrubber system and fume hood. I also added a nice work bench and even carpet on the floor. Its not state of the art but i think it will for what i do.

Every thing i built out of 3/4 plywood, the scrubber on the right has been fiberglassed, the fume hood on the inside has two coats of white gelcoat. The extension on top of the hood holds a 4" pipe with a Y to suck the fumes out of the retainer as the hood vent draws the fumes up through the main vent.

The blower system on the left i made using a gas furnace my mother inlaw gave me to scrap that still worked. The return at the bottom holds a mist filter to remove any droplets that are carried through the piping system. On the right side at the bottom I install a 12" x 12" return air vent to help with fresh air to the motor.

Thanks For all the help and this forum i have learned a lot and now it time to make something of this.

Ken

 

[jeneje]

Good morning Gerald, I have a question for you? What do you mean by "how much draft you have" I should not have any, except for the 4" exhaust pipe at the top. Also should i incorporate a pressure gage inside the scrubber.

Thanks
Ken

Sorry Ken, I missed this until now. "Draft" is the common term for how much air flow you have through your tower. Basically - how much "suction" your fan can support. Everything that you put into the column (like packing) causes a pressure drop (a resistance to flow) which either lowers air flow or requires more power from your fan.

I think pressure gages are good ideas. If you measure pressure drop across the scrubber, this will tell you when the scrubber is starting to get buildup or plugging - it is good practice and provides good diagnostic information.

Best Regards, Gerald

Thanks Gerald, How and where would you install a pressure gage?

Ken

 

[Geraldo]

Thanks Gerald, How and where would you install a pressure gage?

Ken

Hi Ken,

I would install a differential pressure gauge (two inlet ports) and measure the pressure drop across the packed area of your scrubber column.

Most commercial "fume hoods" don't have any such thing, despite some of them having gas scrubbing. On the other hand, every gas scrubbing, absorption or contact tower I have ever seen has differential pressure and flow. Small towers might just have one differential pressure drop measure. Larger units will have differential pressure for every section of the tower (every absorption module, for example). Some of these towers have 100's of sections, and yes, they have 100's of pressure measurements.

Best Regards, Gerald

 

[4metals]

To properly measure what's going on inside a scrubber a Magnehelic is used to measure the differential pressure. http://www.dwyer-inst.com/Products/Product.cfm?Group_ID=26&sPageName=Ordering