387 replies to this topic

[pkhow]

This chlorate cell design will treble chlorate production with no current increase only an increase in supply
voltage. Most MMO electrode material can be used as Anode or cathode.
The advantage: Higher voltage (e.g.12v supplies) are more common and lower amperage simplifies both
wiring and connections.
Space 2 x un-connected electrodes between your anode and cathode they will become anodes on one
side and cathodes on the other. This is the equivalent to 3 cells in series and the spacing between them
can be adjusted to get the current you want. Another electrode can be added forming 4 cells as long as
the total voltage does not exceed 12v as current path around the edge will damage coating. Keeping electodes close reduces required voltage for each cell and helps with the efficiency.

[alany]

Will that actually work?

What's the mean free path of an ion in aqueous solution anyway? I'd imagine its bloody short. I've considered series reactors in the one current loop, the electrons themselves can be re-used in a sense multiple times, and make an easier load to build a supply for. However, I always assumed the liquid was too conductive for that to work without baffles or some way of reducing leakage around the stages to be very much smaller than through each one in series, essentially I believed it was such an engineering problem that it was easier to just have discrete isolated cells in series.

Running multiple isolated cells in series works fine, so in a sense you can get N-times as much product for the same number of Coulombs. However pushing those Coulombs around takes N-times the voltage, so the losses have gone up N-times too, for a total N-times more Watt-Hours.

The good thing for us Amateurs is you get N-times the product in the same time (or the same amount of product N-times faster). However you pay for it in terms of total energy use, so there is no free lunch, all that energy you get out so rapidly in the pyro has to be put in slowly and at terriable efficiency in the cells. The bad thing is you need to physically build N cells, wire them up and maintain them. For many electrode material is the biggest cost, and even one anode is a lot of work to make.

Edited by alany, 18 April 2006 - 03:31 PM.

[pkhow]

The most common design now used by small chlorine cell manufacturers use 11 or 13 electrodes.
The center electrodes is common and the outer 2 are connected together making Two parallel
cells each formed of 6 series reactors. Because they operate in very low salinity solution each
reactor requires close to 5volts requiring a supply of almost 30 volts. The resistive losses between
reactors is almost zero but they do suffer from leakage around the edges that can damage the
coating. To help reduce this the electrodes are supported in long slots down the body of the housing.
This should not be a problem under 12 volts..
My Power supply is 9v so by reducing the spacing of my 4 electrodes to 7mm I am able to get
over 20amps at less than 3v between each electrode.

[riptheory101]

I am interested in trying just for the challenge (And i like making everything iny my fireworks)


is there a common list of materials avaliable that would make the best cell for production of perc
and perhaps a detailed description of what has to be done

[fishy1]

I am interested in trying just for the challenge (And i like making everything iny my fireworks)
is there a common list of materials avaliable that would make the best cell for production of perc
and perhaps a detailed description of what has to be done

the anodes used in perc production arent really common, platinium is the best, lead oxides are also used.
everything else is pretty easy to get,

[riptheory101]

http://www.lycosesho.../...221 Micron"

is this suitable at all
which one is the best to get or does it matter

[alany]

Thin and expensive, but they would make perchlorate in fairly small cells.

[gilbert pinkston]

anyone know the erosion rate for Pt in a perchlorate cell under ideal conditions?
and what those conditions might be?
0.1cm x 10cm x 3.14 x 0.0001cm => 0.000314cm^3 x 20 (app. density)=>0.00628 grams of Pt
is that right? .....not much metal
might be better off buying a tenth ounce and hammering it out if you want to use Pt

[pkhow]

I don?t know about solid Pt but a Pt coat on a substrate, I would think would be similar to MMO coating with a almost Nil wear rate except in adverse conditions. It seems MMO can operate in very dilute solution if the oxide does not become heavily encrusted with crystalizing Product.

[pkhow]

Has any one had experience running a Chlor/Perchlorate cell well past the calculated run time. What I am interested to know is would repeated running of a solution in a perchlorate cell mean that it will end up reasonably pure.
PNK

[newtoolsmith]

Hi friends,

I did it!

Some month ago I prepared leadnitrate and coppernitrate from lead, copper and nitric acid. That was the easyer part.

The next step was made this week, as I prepared my first GSLD (Graphite Substrate Lead Dioxide) Anodes.

A spinning setup was build, similar to the ideas of wfvisser's homepage.

The first try failed because a thermofuse inside the motors windings actuated and the motor stopped spinning. I didnt realize because I sat down to eat something. The anode colected little bubbles and got holes in its coating. It was not so easy to disassemble the winding and solder the fuse out. I then decided to mount a cooling fan to the motors shaft. That works now.

The second try failed because I allowed the stup to run too long. The plating got too heavy and flew away short before I decided to stop the proces. F...!

The third try was really good. I let it run at 6 ampere for 30 minutes and the layer became approx 0,8mm thick and has no holes or cracks.

The fourth try did exacly the same.

The anodes are placed parallel with 25mm distance from center to center. A 4mmx24mm bar of stainless stell is placed between them. The top sides are sealed with two compoments silikone. The working length is 20cm so the anodes area is around 110cm?. The cathode area is almost exactly the same.

The bath has 1,8 litres and containes 600g NaCl.

I use a PC power supply, it runs 21A @ 4,85V through the cell.

The only thing I am wondered about is the very strong chlorine smell!!!!!!!!

I even thurts when breathed in unfortunately!

Much hydrogen is formed at the stainless cathode, it builds up a lot of foam.

The chlorine bubbles are much less then the hydrogen but I really want to drcrease further!!

Any ideas?


(photos will follow)


MfG
newtoolsmith

[newtoolsmith]

It's me again!

Here the photos are:

First picture shows the GSLD plating setup. You cant see the power supply as it is used for the PercCell now. On the rear side a shunt is mounted, that gives 60mV voltage drop at 6A current. The motor went too hot and I added a small fan to it using hot melt glue.

The white paddle, attached to the sliding copper contact under the motor, prevents the liquid from rotating to much. The rotation of the graphite rod tends the liquid to rotate too and then it tends to leave the glass.



The first GSLD Anode failed in preparation as I told above.



Now the cell works and produces lots of foam on the one hand and many many small clouds of a white precipitant. What will this be? NaClO3 already? Electrolysis started only two hour before.

The left ,ultimeter shows the cell voltage: 4,94V. The right multimeter (by far the better one used for the small voltage)shows the voltage drop over the shunt: 47,8mV. This means a current of 19,92A because the shunt used here gives 60mV@25A. The shunts are class 1.5 - that means very precise.



The cell closeup shows the foam and the PPTE clouds. On the bottom of the beaker you can see the arrangement of the two GSLD Anodes and the SS cathode.




Short after taking theese pictures I touched the cell to see if its still warm. I did this because I boiled the NaCl solution to dissolve all the salt quickly and used the solution soon. I almost burnt my hand! The temperature rised up to 72?C and seems to stabilize somewhere around 75?C. A mercury-thermometer is added now.


I started with 600g NaCl wich will produce little over 1kg NaClO3 and then almost 1,2kg NaClO4.

This will need 2500 amperehours to form the chlorate and another 831 amperehours to form the perc if the efficiency is 55%.

In summary the cell will have to run for (2500Ah+831Ah)/20A= 166,6hours, that are seven days @55%.

If the efficiency is 80% the runtime is only 104,1hours, a little more than four days.

Assuming an power supply efficiency of 75% it will need 22kWh of electrical energy when the cell efficiency is 55%. The cost will then be around 4,50€. At 80% cell efficienca the cost will be only 3€.


Lets hope and see.


EDIT: This is the first time my links work the way I want them to!


MfG
newtoolsmith

Edited by newtoolsmith, 29 September 2006 - 12:53 PM.

[Valec]

Some time ago, I tried electrolysis to produce perchlorate. I had nearly the same numbers calculated for my setup, but I've been using graphite electrodes which dissolved in the time between 21 to 23 kWh completely - as perchlorate started to form, I think. So I cancelled the process at this time and got about 800g of KClO3 finally.
Seems like the 55% percent calculations better fit reality of simple setups.

Edited by Valec, 29 September 2006 - 07:38 PM.

[leosedf]

Hey newtoolsmith great work!
I need to construct something similar to your cell.
Can you give me more info about your anodes? Where did you got them?

Edited by leosedf, 29 September 2006 - 08:28 PM.

[newtoolsmith]

Hi friends,

here are the first results after 16 hours runtime:

It looks not very good.

Inside the cell a brownish precipitate occured. I fear this will be the result of anode corrosion. The top section of the anodes is uncovered and silicone sealed but the electrolyte will find its way...

The cathode looks unchanged.

The current didnt change much.

This morning I had to add 100ml of NaCl solution. I would really like to add some HCl but doing this would decrease the pH value and chlorine would bubble out again. Did anyone manage this problem?



I think a new ( bigger ) construction has to follow. I got a 10 litre bucket this morning...

@leodself:

The anodes were made following exactly wouters instructions as described here:

GSLD Anode preparation with spinning setup

The graphite rods are cheap welding equipment. They are used to remove steel by melting it in the electric arc and blow it away with compressed air. Called "Fugenhobel" in germany but I dont know the english name or where to buy them. You can find them in the ESAB online catalogue.

The rods are 8mm in diameter and 305mm long. After plating about 22cm are covered with PbO2 and you can use about 20cm.

The diameter is then almost 10mm and gives a aerea of 60cm?. The two anodes provide 120cm? and so they can be used up to 24 ampere.



The next step will be to do a test on fully coated ceramic substrate PbO2 anodes. I will try to remove the glaze of a piece of tile, paint it with a PbO2/water slurry and do the electroplating again. This will give a really large aerea and little holes are not critical as the substrate is inert. Conductive paint containing silver will give the electrical connection.

I will let you know...

MfG
newtoolsmith