Let's talk about the steam cracker, which is the heart of the petrochemical plant. This is the main unit that produces most of the petrochemicals in the plant. Okay, so steam cracker. Remember that we will be using naphtha as a raw material, and

what we want to do is obtain the most amount of ethylene, propylene, ethylene, and butane. Okay, so how do we do this? We're going to be using two main stages. The first one will be high in temperature and average in pressure.

Some even state the compression stage is a stage per se, but I actually prefer to group it into the second part, which is the cold stage. The cold stage must be high pressure, low in temperature. The main idea is to produce lots of olefins,

which must have double bonds in their carbon chains. The typical feedstock is naphtha, and it will be fuel oil, or even natural gas.  Even chemical processes exist to convert heavier components into more useful materials. So you have CₓHᵧ, which you don't know, you don't care. You're going

to have water and oxygen, and what you want to do is maximize ethylene, ethane, acetylene. Hydrogen gas is a byproduct.  These are selected carbon materials. Methane...well, technically you don't want that, but that's a byproduct. This is pro-

pylene.  This is what you want the most. This is what you want.  Ethane, propane. Propane production is also very important.  Butane has a double bond. Hexane...technically this is benzene. Some carbon leftovers, heavy oils, and so on.

Important parts right here. Let me highlight the important ones: This is the most important. Secondly, will be this one right here. Third will be these guys right here, and lastly, this one and this one right here.

Going as natural gas or to find petroleum gases. These can be used as seen gas, and this is benzene. If you want to separate that, you want to take away the carbon solid material (coke) and the heavy oils must be removed. Record temperatures that inform us...

between 700 to 800 Celsius. The reaction is pretty complex because we are producing a lot of material. In Iran, so it will be of no use to state each individual kinetic and individual material, because you're using bulk material chemistry. So just assume that...

you're getting this material. Talking about the structure, we've got the hot section. You have little furnaces—technically not furnaces, but they are the reactors which are producing the olefins—then you have the compression, quenching, and this is the cold section.

What you want is low temperature and plenty of distillation towers in order to remove the ethane, butane, propane, methane, and so on. Talking about that, let me show you this image. So this is a steam cracking unit in Wilton, in the northeast...

of England. You can see there are plenty of towers. What are those towers? Well, first I want you to answer this question: Is this the hot section or the cold section?  Since these are the distillation columns, therefore this must be the cold section. Okay, so this is the cold...

Section one: This tower separates C4 from C16 mixtures.  These are volatile materials. First, remove all C3 material.

Next, the depropanizer removes C3.  This leaves C1 and C2. We'll discuss C1-C3 in more detail later, but the main concept is shown here.

Then, the deethanizer separates C2 hydrocarbons.  C1 and C2 will be removed here.

This removes ethane, ethylene, and acetylene. Next is the demethanizer, which separates methane.

Stage 5, the splitter, separates propane from propylene (propylene has a double bond, propane has single bonds).

Stage 6 separates ethylene from ethane (ethylene has double-bonded carbons).

Plenty of separations, especially between C1, C2, C3, and C4 materials. These are the units; again, this is just an overview. Okay, so let's see how it goes. We've got a pyrolysis furnace; those are here and here. You have fuel because you

must increase the temperature. You have water; remember that this is steam cracking, and you get naphtha. You got here; there is reaction, then you bring the material here. There will be some more, let's say, cooling, and then you scrub the waste oil. Remember that we're going

to have some oils, and we are going to remove all other materials. Then we also have this C2, C3, C4, which are recycled. So remember, from here we're going to have these materials. This saturates—what we imply with 'saturates' is that this is a

same propane and butane materials. Okay, very important: we are going to apply the same pyrolysis, then we're going to clean these (scrubbing), and then now that we're ready, we are going to compress this. We compress this; we separate the light materials, which typically are hydrogen

gas, carbon monoxide, and the C1, C3 materials; some C3, C4. What shall we go down? And then we've got a washer. Essentially, what we want to do is to remove all the leftover material. We dry them, and we have only C1 versus C3.

We've got the demethanizer, which will take away methane. Here we have C2, C3. We have the de-ethanizer here. We have C2 cut and C3 cut. And the important part is that we need to ensure that we remove the... Here it goes, the

Ethane goes to the splitter. This splitter has a double bottom and triple-bonded material.  It goes down to the acetylene tower. From the acetylene, we separate and settle. This stripper recycles material here.

Remember, this is C2 material. Acetylene (C≡C) is topping still, and then we have pure ethylene (C=C). Remember, this is 60% of the material we use in petrochemicals. Now let's get back to the nicely separated C2 from the C3 cut.

You'll see here that we have C3, and from here C3 and C4. So we are...

mixing these C3 and C4.  This is going to have C4 here. This C3 cut is deeper. This will have the single-bonded three-carbon molecule, and you have propylene here. The C3 splitter ensures that...

propylene is purified, and all the material is recycled. Now, talking about C4, it goes directly here, and we purify C4 and بوتان (butane) at the end. These are very important. This is the double-bonded butene, and...

this will be the single-bonded butane. All leftover material will be saturates.  Before C2, C3, and C4 go back to pyrolysis, all this gets recycled, and technically, the yield increases. Okay, this was just an overview.

Make no worries, we're going to see this part by part. Actually, we're going to separate this into the hot section, called section A, and so on. Okay, this is a cycling sent. You've got your feed, furnace, steam, leftover material, cleaning, compression, caustic soda for cleaning.

And then you've got like gases. You've got the secondary method: is gasoline, ethylene, ethane. It's exactly the same, just a different arrangement. Important part right here: to detect and be sure that you can separate the hot section from the cold section. Okay, so now let's go more technical; let's

strip this process and let's see why it's so interesting and why do we get that many olivines from it. [Music]

Steam Cracker - Overview (Lec031)

Steam Cracker - Overview (Lec031)