
Full Flex Diesel Cracking Unit (cracks anything to Diesel) - No Trucks.
As a continuation on my efforts from my post on cracking Naphtha and Fuel Gas in the same Cracking Unit, I've developed what may well be the ultimate in Cracking flexibility. Feed in Heavy Oil, Naphtha, Fuel Gas, Hydrogen and Oxygen in any combination and if it can crack, it will crack (e.g. if you don't provide any Hydrogen it obviously can't crack Heavy Oil).
( Blueprint: https://coigame.com/Blueprint/3833 )
Earlier I had dismissed loopback, but after further experimentation I found narrow sets of condition where loopback seems to be stable, thus eliminating the need for a water loopback.
The first is keeping the loopback pipe extremely short, ideally 1 segment. It's possible to use a longer pipe, but you have to prefill it with hydrogen or something which is annoying.
The second leverages building buffer sizes, and requires the somewhat paradoxical combination of features used in ways not intended:
- "Trucks CAN IMPORT cargo" must be set, this increases the internal buffer sizes from like 3 or 8, to 40.
- Truck import should be prohibited in reality. Ideally by using a Logistic Zone with no trucks in it.
Actually nothing goes horribly wrong if truck import is permitted, it's just a waste of truck labor. Also this is designed to be turned on without interference from trucks, truck deliveries can put it in an unstable state that require additional truck deliveries to correct. So just paint a logistic zone over the Cracking Unit before building it.
Now here's an example of where this works brilliantly.
In a new Tight Spot playthrough I decided to store Heavy Oil in a tank farm (burning the light oil).
Once I'd researched cracking, I was using nearly precisely 36 diesel as produced by Distil II. So I simply bulldozed my entire Distil setup, built 2 electrolyzers to produce 8 hydrogen and a full flex Cracker to live off the stored Heavy Oil for a while.
You need 9 Hydrogen to crack 24 Heavy Oil, but I loop back in the 6 Fuel Gas together with electrolyzer Oxygen, so the Cracker runs on about 88% Heavy Oil and 12% Fuel Gas, nearly perfectly consuming the 8 hydrogen.
Furthermore, I subsequently injected Fuel Gas from digesting Sludge from Wastewater processing, further stretching the Heavy Oil slightly.
Once I had drained the Heavy Oil tanks, I built a new Distil I+II+III setup, exporting some Naphtha to make Rubber (etc), and used the same unit to crack everything to Diesel, resulting in a production breakdown like this:
At this time I was making roughly 45 Diesel from roughly 34 Crude Oil (contrast Distil II, making 36 Diesel out of 60 Crude Oil). To achieve this level of Crude Oil conversion without flexible cracking, would require 3 Cracking Units and 24 extra workers, and while not prohibitive, on Tight Spot it's not that easy to spam workers. The Full Flex Cracker only needs about 35 kW (on average) to run the Pipe Balancers.
That is the setup roughly maxed out with the Cracking Unit running at roughly 100% uptime, though it goes a bit higher if more Diesel comes from Distill II and Heavy Oil Cracking due to more Naphtha and Fuel Gas going to other recipes.
In this playthrough I've been running the Full Flex Cracker for around 70 years without it suffering a single hiccup in spite of having all sorts of challenges thrown at it, like dramatically changed input ratios, power cuts cutting off the hydrogen, oxygen depletion due to fertilizer etc. It has been 100% stable the entire time, and freed from the tyranny of truck deliveries its internal buffers fluctuate at the same levels they had on day 1.