Thermacracking

Question 1

Why are coking units a thing?

Answer 1

Because the “bottom of the barrel” stuff has become a problem in refineries, their market has been decreasing, so they need to be processed to useful products

Coking units cover these heavy hydrocarbon mixtures into solid coke and lower-boiling products which serve as feedstocks to other units

Question 2

What is Coking

Answer 2

It is a severe thermal cracking process where one of the end products is primarily carbon (coke).

Question 3

What has been happening in recent years w.r.t coking.

Benefits (2)

Answer 3

it has been used to prepare coker gas oils streams suitable for hydrocracker feedstocks and high-quality coke.

This reduces refinery yield for the heavy residual fuel. Also reduces metal content of the catalytic cracker feedstocks

Question 4

What is thermal cracking
4 types of thermal cracking

Answer 4

Heat and pressure break down and rearrange the hydrocarbon molecules

1. Delayed coking
2. Flexicoking
3. Fluid coking
4. Visbreaking (not coking)

Question 5

What happens in delayed coking

Answer 5

Heaters rasie the feedstock temp above the coking point. But the feedstock is at high velocities that coking happens later on. Coking happens on the coking drums (an insulated drum).

Question 6

How is fresh liquid added in delayed coking

Answer 6

either directly to the furnace or to the fractionator