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Design Challenge of the Month, Year, or Whatever

04/20/2017 4:44 PM

Here is the Challenge: Without introducing a completely different measurement method, such as differential pressure through an orifice, $$$ mass flow meter, etc. how can existing setup be improved to allow less corrections for changes in liquid level during water displacement, and at the same time re-design #1 bubbler (also the condensate receiver vessel) such that condensate will drain off to another vessel using a convenient overflow tube.

Final receiver vessel will have means of at least manually discharging the accumulated condensate periodically, while still under pressure (not more than approximately 35" H2O head) to condensate pump supply vessel (coffee can). I envision a clear PVC pipe with caps at top and bottom, a plate divider in the middle, the overflow hook tube (inverted asymmetric U) passing through the plate, and a pressure equalizing tube passing through with openings of this tube in the upper and lower head spaces of the new revised #1 bubbler.

Would it be easier (perhaps) to suspend the collector jar (from load cell) instead of resting on balance pan, to reduce displacement height?

Existing Setup:

1. You are presented with a gas evolution flow from an electrolysis experiment where gas flow is more or less proportional to current between the electrodes.

2. The gas is bubbled through a cylindrical vessel, #1 bubbler, then proceeds to another jar, #2 bubbler, where the gas bubbles at the bottom, then forces water out through a tube in the bottom to a collecting jar resting on a load cell. the load cell records mass over time, and processor calculates flow rate once per measurement cycle. measurement cycle can be set from one second up to 60 seconds, or more, depending on the buffoon programming it. #1 bubbler is about 0.75 L volume, with about 30% free board most of the time. #2 bubbler is a 1.5 L vessel with lid on it having ports and fittings, sealed, etc. Level in #2 changes as water moves and is weighed.

3. It has been observed from the data log, that apparent flow rate varies downward (after a stall sequence at the beginning where the bubble jars pressurize slightly) over a number (about ten or so) measurement cycles, until #2 bubbler is nearly empty, and the collector jar is nearly full (and scale reads 0.600 Kg.) at which point a dodgy solenoid valve opens and dumps gas pressure, allowing the collector jar to siphon back to the bubbler #2. Measurement cycles then re-initialize, while data log remains active on the same file (to conserve file names).

4. Variation in pressure from start of major cycle to 0.600 Kg point is considered to be the measurement of meniscus in #2 bubbler to the top of the delivery tube to collector jar (atmospheric pressure in collector jar). Variation range: 25" H2O increasing to 28" H2O. Obviously, with higher gas flow rates there will be changes in dynamic pressure due to tube impedance, but this is constant during each set of measurements prior to the "dump".

5. The gas coming from the reactor includes whatever water vapor from the warm to hot reactor (within 10 C of boiling at times). We are going to introduce an air-cooled condenser to dry out the gas stream to hold minimal water. All condensate formed will, unfortunately be carried in the gas tube to #1 bubbler.

Picture of the existing set-up: Pending (will be sent tomorrow if possible).

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Guru

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#1

Re: Design Challenge of the Month, Year, or Whatever

04/20/2017 10:23 PM

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Guru

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#2

Re: Design Challenge of the Month, Year, or Whatever

04/20/2017 11:31 PM

James: if the condensate pump supply vessel is a coffee can,,

Is the collector jar a urine specimen bottle ?

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#3
In reply to #2

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 9:11 AM

beverage bottle, we were going to use a #0 beet can, but it was a bit large.

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#11
In reply to #3

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 12:54 PM

Canned potatoes. You can whip 'em, but they can't be beet.

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#4

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 9:53 AM

Is there a way of controlling the Air time input before the pressure dump?

what is the back charge pressure?

Without pictures it is hard to comprehend current set ups.

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#6
In reply to #4

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 10:55 AM

The way it works is this: water displacement by gas flowing from reactor. Each measurement of mass displaced can be set in the program (by me) from 1 second up to about 60 seconds, maybe more, but what is the point of going even higher?

The pressure dump takes place because the collector has received several measurements worth, and is reaching 600 mL mark, and needs to empty. This 600 gram mark is where the program tells the solenoid to open, and this dumps any accumulated pressure in the reactor, #1 bubbler, and #2 bubbler as there is a 3/8" ID tubing connection between the three.

The back charge pressure is also being recorded, and unless some line plugs up (and pops the lid off the reactor at 28 psig), there is usually only pressure measured in the range of about 15 kPa, to 30 kPa. (2-4 psig).

You can see the picture in my reply to my post.

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#5

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 10:28 AM

As promised earlier, a photograph of the existing flow meter. It may or may not be attached to a laptop computer by means of a USB cable, and does include its own SD card for data recording.

See #1 bubbler at the right, strapped to a weighed can, #2 bubbler (displacer) with wood blocks clamping down the lid, the small 12 V solenoid valve (without flyback clipper on it) shown at far left lower, and the red collector jar on a load cell platform. Obviously, hoses are a bit long, and there is a lot of offset in height between bubblers and collector, so I might work on that a bit this weekend. Clipper is presently attached to solenoid valve.

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#9
In reply to #5

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 12:44 PM

Would it make sense to dump the gas pressure with every measure cycle, so that each cycle is done under the exact same conditions each time?

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#19
In reply to #9

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 2:07 PM

No, actually I lose about 5-10 measurements as "trash" where it registered no mass change while charging system pressure back to the flow point.

I am starting to think I need two load cells, one for #2 bubbler/collector #2, and one for #3 bubbler/collector #1.

That way, using an air switch (2x5 port) flow could transfer from one to the other as displacer, other as collector, and oscillate, never actually dumping, but continually going through measurement cycles. I have some more cogitating to do in this regard, and a considerable build and re-program if that is the answer.

After further review, that idea of starting over every measurement cycle would absolutely work, if the cycle were triggered by the 0th, or 1st droplet from the delivery tube (actually the first change in mass over 0.001 Kg, should suffice. Thanks for the inspiration.

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#7

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 11:00 AM

Float the discharge into the bubbler. Then the liquid level in the vessel is immaterial.

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#8
In reply to #7

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 11:11 AM

I suppose you mean float the condensate off to another sealed vessel at the same head pressure?

You see why I really, really need the "Flatulizer" now?

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#10
In reply to #8

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 12:45 PM

I am a natural born " Flatulizer"

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#12
In reply to #10

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 12:58 PM

I suppose for Bill we will need to upsize the unit from 500ml/rev to something around the cubic hectare size.

Still think we're missing the party game market.

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#14
In reply to #12

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 1:07 PM

You realise of course that a 'cubic hectare' is a six-dimensional volume, yes?

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#16
In reply to #14

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 1:19 PM

Are you saying that Bills production will fit into only three dimensions?

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#17
In reply to #16

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 1:44 PM

Well.... I suppose that is a bit a bit conservative....

Here, how's about we just drop the 'hectare' metric altogether and pop him directly in Hilbert Space.

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#18
In reply to #17

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 2:05 PM

I suppose you're right. I was thinking it might be the gateway to practical interdimensional travel.

The shipboard atmospheric analyzers have checked the environment in dimensions 7 thru 9 and reports,"The air is OK, but it smells a bit...."

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#20
In reply to #18

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 2:07 PM

OUCH, My feeling.

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#15
In reply to #12

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 1:07 PM

Oh, come on, flatulence is funny...

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#21
In reply to #12

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 2:08 PM

I agree. Flatulizing per fartnight?

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#23
In reply to #21

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 2:14 PM

No, I think the unit should be the pong, the standard pong being the volume produced by one standard navy bean. The pong could then be both imperial and metric at the same time.

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#24
In reply to #23

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 2:15 PM

While that would be a metric, trust me, the result is far from Imperial Trumping.

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#25
In reply to #24

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 2:18 PM

Interesting that there are no good answers to this thread.

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#13

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 1:00 PM

"how can existing setup be improved to allow less corrections for changes in liquid level during water displacement"

I do not see a back flow on any of the lines.

May be able do get more consistent readings and less corrections if back flow discharge is one direction.

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#22
In reply to #13

Re: Design Challenge of the Month, Year, or Whatever

04/21/2017 2:09 PM

The delivery tube is the back flow tube when the #2 bubbler is vented. Of course, I can incorporate pressure and temperature log to #2 bubbler to allow flow correction.

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