There are two types of coking processes: delayed coking and fluidized-bed coking. Delayed coking involves heating feedstock in drums to allow cracking reactions to complete over a long residence time, producing coke as a byproduct. Fluidized-bed coking is continuous and spray-feeds pitch into a bed of hot coke particles at higher temperatures and pressures than delayed coking, resulting in more liquid products and less coke yield.

1. There are 2 types of coking 1. Delayed Coking 2. Fluidized-bed coking
Delayed Coking:
1.It is a semi-continuous type of coking.
2.In this heated charge is transferred to large soaking drums where a long residence
time is provided to complete the cracking reation.
3.Here the feed is atmospheric residuum.
4.It is introduced into the fractionator and heated
5.The lighter products are removed from the side
6.The remaining bottom products along with the recycle stream from the coking drum,
are shifted to the furnance where they are further heated.
7.The outlet temperature of the furnance varies from 480 – 505 (deg C).
8.From the furnace, the heated materials are transferred to one of a pair of coking and
soaking drums.
9.The cracking reactions continue in the drum and go to completion after a long time.
10.From the top of the soaking drum, the cracked products go to the fractinator and
coke is deposited on the inner surface of the drum.
11.For continuous operation 2 drums are used. When one is in use, the other is being
cleaned. The temperature in the coking drum varies from 415 – 450 (deg C) and the
pressure from 1.68 to 5.76 atms.
12.The overhead products from the coking drum, go to the fractionator where naptha
and gas oil are removed as products.

3. The preheated fresh feed and recycle material are transferred to the furnance.Recycling
carries heat to the furnance and converts further the heavy fractions.
Fluidized-Bed Coking:
1.It is continuous process.
2.In this pitch is sprayed into a fluidized-bed of hot coke particles. The use of a fludized
bed requires shorter contact time than delayed coking and also coking reactions are carried
out at higher temperatures here.
3.The yield of coke is less but the yields of other liquid products are more.
4.In this process 2 vessels are used. First one is a reactor and the second one is a burner.
5.By burning a portion of coke in the burner, heat is generated and this heat is transferred
to the reactor by transfer of coke particles from the burner to the reactor.
6.In the reactor, coke particles remain present in the fluidized form. At the bottom of the
reactor, steam is introduced to keep the bed fluidized.
7.The pitch coming from the bottom of a vacuum tower, at around 260 to 370 (deg C) is
injected directly into the reactor.
8.The temperature in the reactor varies from 480 – 570 (deg C) and the pressure is nearly
atmospheric.
9.At these conditions, the incoming feed is partly vapourised and partly deposited on the
fluidized coke particles.
10.Since heat is supplied by the circulating coke particles, no further preheat arrangment is
required for the feed.

4. The hot pitch on the surface of fluidized coke particles, breaks and vapourises
And leaves as a residue. This residue later on dries to form coke. The vapor products
Go to a cyclone, where most of the entrained coke is removed.
The temperature in the bed of the burner varies from 590 – 650(deg C). The pressure
In the burner varies from 1.34 to 2.7 atmospheres.