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another reactor design conundrum

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  • another reactor design conundrum

    The intent is to use a "mixing pump" to help disolve the CO2 fully. The question is... How will this affect the fluid dynamics of the system? Pressure, flow, etc... Any takers?

    CO2 H2O
    |o| |~|
    |v| |v|
    |0| |~|
    _|0|_|~|______________
    |~|~~~~~~~~~~~~|
    |~|~~~~~~~~~~~~|
    |~|~~~~~~~~~~~~|______
    |~|~~~~~~~~~~~~ < ~~~|
    |~|~~~~~~~~~~~~____ ~|
    |~|~~~~~~~~~~~~| | ~ |
    |~|~~~~~~~~~~~~| | ~ |
    |~|~~o~~~~~~~~~| | ^ |
    |~|~~~o~~~~~~~~| | ^ |
    |~|~~o~~~~~~~~~| | ^ |
    |~|~~~O~~~~~~~~| | ^ |
    |~|~~o~~~~~~~~~| | ^ |
    |~|~O~~~~~~~~~~| | ^ |
    |~O~~~~~~~~~~~~| | ^ |
    |~~~~~~~~~~~~~~| | ^ |
    |~~~~~~~~~~~~~~| | ~ |
    |~~~~~~~~~~~~~~| | ~ |
    |~~~~~~~~~~~~~~|__| ~ |______
    |~~~~~~~~~~~~~~|***********|
    |~~~~~~~~~~~~~~|***********|
    |~~~~~~~~~~~~~~~~ >*PUMP***|
    |~~~~~~~~~~~~~~~~ *********|
    |~~~~~~~~~~~~~~|_____________|
    |~~~~~~~~~~~~~~|
    _~~_________________
    |~|
    |V|
    H20
    Last edited by mulm; 09-09-2010, 04:49 AM. Reason: added quotes to "mixing pump"

  • #2
    What's a 'mixing pump' ? ;-)
    6' Planted Tank (72" x 18" x 20") - 4 x 30W T8 Tri-Phosphors - 2 x Eheim 2217 'Classic' canisters
    Flourite substrate - Ocean Runner OR-2500 + AM1000 - Tunze Turbelle Nanostream 6045
    6.8kg Catalina CO2 - Red Sea Pro regulator - Swagelok B-SS4-A metering valve - Vecton 600 UV

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    • #3
      In my case it would likely be an Eheim 1048... but any external pump could work.

      The idea is to augment the flow within the reactor to help mix the CO2 so to not rely solely on flow thru the system for dissolution of the CO2. The hope is that this will decouple CO2 injection efficiency (distribution within the tank asside) from filtration efficiency while keeping them inline and using the same "plumbing".
      Last edited by mulm; 09-09-2010, 02:30 PM.

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      • #4
        Ok, so what you mean is a pump *inside* the reactor itself (whilst there is still a seperate pump actually pushing water through the reactor).
        6' Planted Tank (72" x 18" x 20") - 4 x 30W T8 Tri-Phosphors - 2 x Eheim 2217 'Classic' canisters
        Flourite substrate - Ocean Runner OR-2500 + AM1000 - Tunze Turbelle Nanostream 6045
        6.8kg Catalina CO2 - Red Sea Pro regulator - Swagelok B-SS4-A metering valve - Vecton 600 UV

        Comment


        • #5
          Seems like overkill unless you're running a huge amount of bubbles into the reactor. Let physics do the work, keep it simple.

          Comment


          • #6
            scottward-
            Sorry...the ascii "drawing" is pretty bad. Unfortunately the forum strips out whitespace. The pump is outside of the reaction chamber and pumps water within from the bottom to the top. The inflow to the chamber would come from the return line from the filter/sump (in my case a 2215) thru the chamber to the tank.

            csmith-
            Suffice it to say that I am very familliar with the traditional reactor designs and other methods for injection. "Simple" or otherwise. Suppose the amount of bubbles is larger than the system's flow can dissolve alone and increased flow thru the system is not desired.
            Last edited by mulm; 09-09-2010, 01:17 PM. Reason: added more clarification to description

            Comment


            • #7
              I think putting the pump at the bottom is undesirable because it risks pulling
              bubbles down to near the exit. Some bubbles will prematurely escape the reactor.

              I believe increasing flow through the system (but keep the current inside the system
              at optimal level) is a key to better dissolving.

              Comment


              • #8
                nipat-
                Exiting bubbles is an issue with any increased flow and can be address with chamber length.


                What other adverse effects might this have on the system? Will it increase the pressure within the system? Over pressurization? Decreased flow thru the system?

                Comment


                • #9
                  Originally posted by mulm View Post
                  nipat-
                  Exiting bubbles is an issue with any increased flow and can be address with chamber length.
                  I don't think chamber length affects flow-rate in a significant way. Try imagining longer hose
                  and shorter hose (I'm not talking about 1 mile vs 1 foot hose, so let's say 1 foot vs 2 feet hose),
                  the difference is mainly caused by surface resistivity of the hose's surface.

                  But increasing the diameter does slow down the current in the chamber in a significant way:
                  http://www.1728.com/flowrate.htm

                  Flow rate = cross sectional area x velocity
                  Last edited by nipat; 09-09-2010, 02:55 PM.

                  Comment


                  • #10
                    nipat-
                    I think you are misunderstanding my reply. My statement about chamber length was in response to the concern about bubbles exiting before being disolved... That is...the longer the chamber the less likely this is to occur. This is a digression...

                    My interest is in what affect the "mixing pump" will have on the fluid dynamics of the system.

                    Comment


                    • #11
                      Originally posted by mulm View Post
                      nipat-
                      I think you are misunderstanding my reply. My statement about chamber length was in response to the concern about bubbles exiting before being disolved... That is...the longer the chamber the less likely this is to occur. This is a digression...

                      My interest is in what affect the "mixing pump" will have on the fluid dynamics of the system.
                      Then I think it's the same efficiency as placing it (the mixing pump) on top as Tom's.
                      But of course, it's just a speculation.
                      Last edited by nipat; 09-09-2010, 07:47 PM. Reason: Adding word ‘efficiency’ and some other little things

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                      • #12
                        I am fairly new to this site.... but isn't Tom's reactor internal and driven by a powerhead and venturi? Not following the connection.

                        Comment


                        • #13


                          http://www.barrreport.com/showthread...al-CO2-reactor

                          His design doesn't increase flow but is about bubble recycling like yours.
                          Last edited by nipat; 09-09-2010, 03:40 PM.

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                          • #14
                            Maybe my "drawing" is the problem here...

                            My design is an external inline reactor (very similar to the DYIs found all over the web; eg: Rex Grigg) with the addition of a pump that will be used to "mix" the water in the reaction chamber --NOT for pumping water into or thru the system. Placement of the pump is secondary in that its purpose is not to move water to and from the tank but to add hydraulic turbulence to the reaction chamber.

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                            • #15
                              Your drawing was clear enough.

                              I've had similar thoughts on reactor design. By recirculation the CO2 rich water within the reactor itself you could increase the overall flow within the reactor without increasing the conventional flow through it. I didn't see any reason to be concerned with any increase in hydrostatic pressure as any increase would simply be relieved through the exit back to the tank. An addition I would suggest incorporating a tube to scavenge any and all gas collecting at the top and recycling it back through the recirc pump to thoroughly smash the CO2 into the smallest bubbles possible to maximize the effectiveness. If the inlet and outlet of the recirc pump were kept as close to the top as possible you could reduce the amount of mist entering the effluent back to the tank.

                              Pat
                              Hard Hat by Day
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