Producing petroleum - number of chemical plants needed??

[Quax]

Hi there,

I have a question regarding the petro industrie I started with eptroleum gas production just recently. Right now I'm running one refinery, three chemical plants converting heavy to light oil, and eight (8!) chemical plants converting light oil to petroleum gas. However, even with this setup, I can barely run two chemical plants producing plastic (one of them alway having a little downtime to wait for full petroleum) and one sulphur plant. See picture below. Not to mention theat the two storage tanks wont even start to become filled with petroleum ...



Am I doing anything wrong here? Why do I need such a big amount of chemical factories for just three factories using petroleum?

[Acarin]

Try this layout, and if you really want tanks as buffers/visual indicators of fluid levels, don't put them in the direct flow. Place them to one side, so that any consumers (eg the plastics plants) can draw directly from the supply rather than having to go through the tanks.

http://imgur.com/1C68CJA

Original source post: https://www.reddit.com/r/factorio/comme ... inery_for/

[Koub]

On a side note, i'd be surprised you need that much plastic right at the beginning of your oil industry. With 2 plastic refineries running full speed, you'll be able to produce 2 advanced circuits per second through 22 level 2 assembling machines. Do tou really need that much ?

[Quax]

@ Acarin: Thanks, will give it a try this evening. I basically thought that it would be a good idea to feed buffers from the chemical plants as I assumed there would be a wast overproduction of Petroleum in the beginning. I thougt that four chemical plants producing Petroleum would be by far enough for the beginning, and wanted to build up stock for later production purposes. However it seems I was wrong ...

@ Koub: you're right, it might be enough running two plastic plants. However, I wanted to sole the Basic issue with producing Petroleum before expanding and then getting stuck. Actually, I only have set up my red circuit production in order to produce blue science, so I have plenty of red circuits available. However, talking about Expansion, I Need to understand the Petroleum production Basics beforehand.

[Koub]

Every 5 seconds, you turn 10 Crude oil into 1 heavy, 4.5 light and 5.5 petroleum
Every 5 seconds, you turn 4 heavy into 3 light
Every 5 seconds, you turn 3 light into 2 petroleum

So every 20 seconds, you get 4 heavy, 18 light and 22 petroleum
out of the 4 heavy, you get more 3 light (1 chem plant for heavy cracking)
out of the 18+3=21 light, you get 14 more petroleum (7 chem plants for light cracking)
in total, you get 14+22=36 petroleum from 40 crude

You have your ratios : 1 chem plant for heavy cracking + 7 for light cracking. Needs as input water + 2 crude per second, and you get 1.8 petroleum per second, which is about half needed to feed a plastic chem plant running full time (uses up to 3 petroleum a second)

[Quax]

Thanks for the maths .. these are ugly numbers, though

[Acarin]

...and that is why I use Productivity Modules throughout my oil-based processes. Yes, it slows them down a little (offset in some cases by the use of Speed Module-equipped beacons), but the saving in crude usage racks up: 20% more products from the crude, +20% more gas from the cracking, +20% more sulfur/plastic from the gas, +20% more acid from the sulfur, etc.

By the time you total up all of the bonuses, you can produce a (relatively) high number of end products from a low input of crude. What you will lose in this type of build is speed, so you either need to accept a slower rate of production, or build more plants to produce the same things, or find a way to use beacons and speed modules to boost the speed back up.

[Fushigidane]

What noone seems to have pointed out yet is that refineries take time to process oil too. You have plenty of chemical plants but not enough refineries to feed them.

[SilverWolfJC]

I created an account just to address this math.
Because this is purely about producing petroleum with 0 excess of heavy or light, I am going to ignore the quantity of oil/water input and petroleum output.

Using advanced oil processing you are producing 1 Heavy & 4.5 Light every 5 Seconds, this is the excess byproduct we want to eliminate
Heavy oil cracking turns 4 Heavy into 3 Light every 5 seconds
Light oil cracking turns 3 Light into 2 Petroleum every 5 seconds


We'll start off with 1 heavy cracking plant and 1 light cracking plant and add more when we have excess
Let's run through this in 5 second intervals:

• After 5 seconds, we have 1 Heavy, 1.5 Light. Since we had 4.5 Light, 3 has been used to make 2 more petroleum. 1 Heavy is not enough for our plant, so it's doing nothing
• After 10 seconds we have 2 Heavy, 3 Light. We added 4.5 to 1.5 and our 1 light cracking plant took 3, leaving us with 4.5 + 1.5 - 3 = 3, which is enough for a second light cracking plant to run simultaneously. So let's scratch that and imagine we have 1 heavy cracking plant and 2 light cracking plants.
• After 10 seconds we have 2 Heavy, 0 Light. With 2 light cracking plants working simultaneously. The 2nd one received enough light oil to run. And 2 heavy is still not enough for our heavy cracking plant to run.
• After 15 seconds we have 3 Heavy, 1.5 Light. Sadly, only 1 light cracking plant is needed at this point and our heavy cracking plant still does not have enough. The 1 light cracking plant has subtracted 3 from out 4.5 income, giving us 1.5 light leftover
• After 20 seconds we have 0 Heavy, 0 Light. Finally, our heavy cracking plant has taken 4 Heavy and will produce 3 Light after 5 seconds. Our 2 light cracking plants have taken the 6 light oil we had stored up at this point.
• After 25 seconds we have 1 Heavy, 1.5 Light. Our heavy cracking plant has produced 3 Light and our 2 light cracking plants have taken 6. 4.5 + 3 - 3 - 3 = 1.5
• After 30 seconds we have 2 Heavy, 0 Light. Both of our light cracking plants are running again and have taken the 6 light oil we would have had.
• After 35 seconds we have 3 Heavy, 1.5 Light. Only one light cracking plant is needed at this point.
• After 40 seconds we have 0 Heavy, 0 Light. Both light cracking plants are running and our heavy cracking plant finally has enough too.
  After 45 seconds we have 1 Heavy, 1.5 Light. At this point, we've come a full loop.

Going through that step by step, I surprised even myself. I predicted we would need 3 light cracking plants for when the heavy cracking plant finally produced 3 more but that was not the case. This is all numbers though. I have yet to try this out in practice and verify that it runs smoothly.

In conclusion, 1 Heavy cracking plant and 2 Light cracking plants should be all you need to produce purely petroleum, not a 1 to 7 ratio

[DaveMcW]

1:1:2 is correct for 1 refinery. (Heavy cracking at 25% and light cracking at 87.5%)
4:1:7 is correct for 4 refineries. (Everything at 100%)