Transcript PowerPoint Template - Universitas Brawijaya

14/15 Fall semester
Petroleum and Gas
Processing(TKK-2136)
Instructor: Rama Oktavian
Email: [email protected]
Office Hr.: M.13-15, Tu. 13-15, W. 13-15, Th. 13-15, F. 09-11
Outlines
1. Hydroconversion
2. Hydrotreating
3. Hydrocracking
Catalytic reforming
Hydroconversion
Introduction
 Hydroconversion is a term used to describe all different
processes in which hydrocarbon reacts with hydrogen.
Hydrotreating
To describe the process of the removal of sulphur,
nitrogen and metal impurities in the feedstock by
hydrogen in the presence of a catalyst.
Hydrocracking
The process of catalytic cracking of feedstock to
products with lower boiling points by reacting
them with hydrogen.
Hydrogenation
aromatics are saturated by hydrogen to the
corresponding naphthenes.
Hydrotreating
Objectives of Hydrotreating
1. Removing impurities, such as sulphur, nitrogen and
oxygen for the control of a final product
specification or for the preparation of feed for
further processing.
2. Removal of metals, usually in a separate guard
catalytic reactor when the organo-metallic
compounds are hydrogenated and decomposed,
resulting in metal deposition on the catalyst pores.
3. Saturation of olefins and their unstable compounds.
Hydrotreating
HT are located before
the reformer,
hydrocracker and FCC
They are also
needed to adjust the
final product
specification for
various streams,
such as light naphtha,
kerosene and low
sulphur fuel oils
(LSFOs).
Role of hydrotreating (HT) in the refinery
Hydrotreating
Main role of hydrotreating
1. Meeting finished product specification.
 Kerosene, gas oil and lube oil desulphurization.
 Olefin saturation for stability improvement.
 Nitrogen removal.
 De-aromatization for kerosene to improve cetane
number.
Cetane number is the percentage of pure cetane in a
blend of cetane and alpha-methyl-naphthalene. The latter
matches the ignition quality of kerosene sample.
Hydrotreating
Main role of hydrotreating
2. Feed preparation for downstream units:
 Naphtha is hydrotreated for removal of metal and
sulphur.
 Sulphur, metal, polyaromatics and Conradson carbon
removal from vacuum gas oil (VGO) to be used as FCC
feed.
 Pretreatment of hydrocracking feed to reduce sulphur,
nitrogen and aromatics.
Hydrotreating
The main elements
of a hydrotreating
process
1. The liquid feed is mixed with hydrogen and fed into a
heater and then fed into a fixed bed catalytic reactor.
2. The effluent is cooled and hydrogen-rich gas is separated
using a high pressure separator.
Hydrotreating
3. Before the hydrogen is recycled, hydrogen sulphide can
be removed using an amine scrubber.
4. Some of the recycle gas is also purged
- To prevent the accumulation of light hydrocarbons
(C1–C4)
- To control hydrogen partial pressure.
Hydrotreating
5. The liquid effluent for the reactor is introduced to a
fractionator for product separation.
Hydrotreating
Operating Conditions
The operating conditions of the hydrotreating
processes
 pressure
 temperature
catalyst loading
feed flow rate
hydrogen partial pressure
Hydrotreating
Operating Conditions
Increasing hydrogen partial pressure improves the
removal of sulphur and nitrogen compounds and
reduces coke formation.
Higher temperatures will increase the reaction rate
constant and improve the kinetics. However, excessive
temperatures will lead to thermal cracking and coke
formation.
The space velocity is the reverse of reactor residence
time (y). High space velocity results in low
conversion, low hydrogen consumption and low coke
formation.
Hydrotreating
Operating Conditions
Hydrocracking
 Hydrocracking is a catalytic hydrogenation process in which
high molecular weight feedstocks are converted and
hydrogenated to lower molecular weight products.
 The catalyst used in hydrocracking is a bifunctional one. It
is composed of a metallic part, which promotes
hydrogenation, and an acid part, which promotes cracking.
 Hydrogenation removes impurities in the feed such as
sulphur, nitrogen and metals.
 Cracking will break bonds, and the resulting unsaturated
products are consequently hydrogenated into stable
compounds.
Hydrocracking
• It is mainly used to produce
middle distillates of low
sulphur content such as
kerosene and diesel.
• If mild hydrocracking is used,
a LSFO can be produced.
• It has been used to remove
wax by catalytic dewaxing and
for aromatic removal by
hydrogen saturation.
• This has been applied to the
lube oil plants and is gradually
replacing the old solvent
dewaxing and aromatic solvent
extraction.
Hydrocracking
Feeds and Products
• VGO is the main feed for hydrocrakers
Hydrocracking
Hydrocracking Catalysts
 The cracking function is provided by an acidic support,
whereas the hydrogenation–dehydrogenation function is
provided by active metals.
Hydrocracking
The following factors can
affect operation (product quality),
Hydrocracking
Process
yield (quantity), and the total economics of the process:
1. Process configuration: one stage (once-through or recycle) or
two stages
2. Catalyst type
3. Operating condition (depends on process objective)
- Conversion level
- Maximization of certain product
- Product quality
- Catalyst cycle
- Partial hydrogen pressure
- Liquid hourly space velocity
- Feed/hydrogen recycle ratio
Process Configuration
Hydrocracking
Simplified flow
diagram of one-stage
hydrocracking
process with and
without recycle
 In commercial hydrocrackers, a conversion of 40–80% of the feed can
be achieved.
 However if high conversion is required the product from the bottom of
the distillation tower is recycled back to the reactor for complete
conversion.
This configuration can be used to maximize a diesel product, and it
employs an amorphous catalyst.
Hydrocracking
Process Configuration
The catalyst in the first
stage has a high
hydrogenation/acidity
ratio, causing sulphur
and nitrogen removal
In the second reactor, the
catalyst used is of a low
hydrogenation/acidity
ratio in which naphtha
production is maximized
Conventional twostage hydrocracker
The effluent from the first stage reactor is sent to a separator and fractionator.
The fractionator bottoms are sent to the second reactor.