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There are many enrichment setups posted lately which got me thinking. Circuits? Logistic network? What if I only have 40 good Uranium? We're going in circles. The product shall go in circles!

See the attachment.

From the top chest U-238 is loaded onto the inner ring of the belt. => This fills the belt all around and stops at the underground belt at the end.

The centrifuges take from the belt and output to the outer ring. There will be U-235 and U-238 on the outer ring. If no centrifuge takes it, it will also flow to the underground belt on the lower left and is sorted at the end. Excess U-235 goes to the chest and U-238 is recirculated to the inner ring. There it takes priority over the U-238 of the upper chest. This solves the sorting problem.

Now, here's the trick: This setup recirculates U-235 in a short path. Each centrifuge has a pair of inserters. One that outputs the items and the other that immediately takes them back in. If you only have 40 U-235, you put them in the top left centrifuge and those 40 will recirculate there forever. Only the excess goes to the next centrifuge and then to the next. If all are filled up it will output to the chest. This way the whole setup will fill up over time and everyhing runs nice and dandy.

You can simply extend this setup to the right for a very long time and add beacons all around.

The inserters on the bottom are probably not necessary. They improve robustness in case something goes wrong and a centrifuge loses a handful of ore but I've not tested if that actually does happen. One nice effect of these extra inserters is that they cause the ore to go around in heaps which is nice to look at.

Each centrifuge will take up to 80 uranium: machines reserve 2x items on normal speed.

Also, there is one really usefull thing you should use circuits for: to make sure that the enrichment only works until you have around 1:20 ratio for U-238 vs U-235 as you don't want all of your low uranium converted

solntcev wrote:Each centrifuge will take up to 80 uranium: machines reserve 2x items on normal speed.

True in the later stage, but one effect helps in the beginning while the U-235 ore is only on the top half:
Once a Centrifuge reaches 40 U-235 the inserter will grab U-238 and lets some of the U-235 pass to the next centrifuge in line. This makes startup simple and efficient.

Once the ore reaches the bottom, the centrifuges fill up.

Zool wrote:Also, there is one really usefull thing you should use circuits for: to make sure that the enrichment only works until you have around 1:20 ratio for U-238 vs U-235 as you don't want all of your low uranium converted

You could add this condition to the inserter at the U-238-chest.

On second thought, you could just limit the output chest to a few stacks. Supply of U-238 should be no problem and U-235 demand doesn't suddenly surge because the reactors always use the same amount of fuel. Also there's no reason to keep a large inventory.

I basically use this kind of setup. Personally I don't give a damn about "needlessly" tying up 40 U-235 per centrifuge, U-235 is only scarce BEFORE you have enrichment. Once you have enrichment you have all the U-235 you can eat. If you urgently need some fuel cells just after starting up enrichment you can manually steal 40 U-235 from a centrifuge.

BlakeMW wrote:U-235 is only scarce BEFORE you have enrichment. Once you have enrichment you have all the U-235 you can eat.

So true! U-235 to fuel cell has a multiplicator of 10. After the output chest was filled with U-235 I didn't see the setup running again ever when I was walking by. I guess that these centrifuges could feed a few dozen reactors.