【Technical Field】
CROSS-REFERENCE TO RELATED APPLICATION
The present application claims the benefit of priority
to Korean Patent Application No. 10-2021-0082382, filed on
10 June 24, 2021, the entire contents of which are
incorporated herein as a part of the specification.
Technical Field
The present invention relates to a method for
preparing synthesis gas and aromatic hydrocarbons, and more
15 particularly, to a method for using pyrolysis fuel oil
discharged from a gasoline fractionator in a naphtha
cracking center (NCC) process as a raw material for a
gasification process and recovering aromatic hydrocarbons
in the pyrolysis fuel oil.
20
【Background Art】
A naphtha cracking center (hereinafter, referred to as
NCC) process is a process of cracking naphtha that is a
gasoline fraction at a temperature of about 950°C to
2
1,050°C to produce ethylene, propylene, butylene, and
benzene, toluene, and xylene (BTX) that are basic raw
materials for a petrochemical product.
In the related art, benzene, toluene, xylene, and
5 styrene have been prepared using raw pyrolysis gasoline
(RPG) that is a by-product produced in a process of
producing ethylene and propylene using naphtha as a raw
material, and pyrolysis fuel oil (PFO) has been used as a
fuel. However, since the pyrolysis fuel oil has a high
10 content of sulfur and a high carbon dioxide (CO2) emission
factor for use as a fuel without a pretreatment, the market
is getting smaller due to the environmental regulations and
a situation where sales are impossible in the future should
be prepared for.
15 Meanwhile, synthesis gas (syngas) is artificially
prepared gas, unlike natural gas such as naturally derived
gas, methane gas, or ethane gas that is ejected from the
land in oil fields and coal fields, and is prepared by a
gasification process.
20 The gasification process is a process of converting a
hydrocarbon such as coal, petroleum, or biomass as a raw
material into synthesis gas mainly composed of hydrogen and
carbon monoxide by pyrolysis or a chemical reaction with a
gasifying agent such as oxygen, air, or water vapor. A
3
gasifying agent and a raw material are supplied to a
combustion chamber positioned at the foremost end of the
gasification process to produce synthesis gas by a
combustion process at a temperature of 700°C or higher, and
5 as a kinematic viscosity of the raw material supplied to
the combustion chamber is higher, a differential pressure
in the combustion chamber is increased or atomization is
not smoothly performed, which causes deterioration of
combustion performance or an increase in risk of explosion
10 due to excessive oxygen.
In the related art, as a raw material for a
gasification process for preparing synthesis gas using a
liquid phase hydrocarbon raw material, refinery residues,
such as vacuum residues (VR) and bunker-C oil, discharged
15 from a refinery where crude oil is refined have been mainly
used. However, since the refinery residue has a high
kinematic viscosity, a pretreatment such as a heat
treatment or addition of a diluent or water is required to
use the refinery residue as the raw material for the
20 gasification process, and since the refinery residue has
high contents of sulfur and nitrogen, production of acidic
gas such as hydrogen sulfide and ammonia is increased
during the gasification process. Thus, in order to respond
to tightened environmental regulations, a need to replace
4
the refinery residue with a raw material having low
contents of sulfur and nitrogen has been raised.
Accordingly, a method for using the pyrolysis fuel oil
as a raw material for a gasification process has been
5 considered. However, in order to use the pyrolysis fuel
oil as the raw material for the gasification process, the
pyrolysis fuel oil should be heated to lower a kinematic
viscosity thereof, but it is difficult to satisfy a
kinematic viscosity condition for use of the pyrolysis fuel
10 oil as the raw material for the gasification process at a
flash point or lower due to a significantly high kinematic
viscosity of the pyrolysis fuel oil.
Therefore, the present inventors have found that when
the pyrolysis fuel oil (PFO) in the naphtha cracking center
15 (NCC) process is used as the raw material for the
gasification process, greenhouse gas emissions may be
reduced, operating costs of the gasification process may be
reduced, and process efficiency may be improved, as
compared with the case of using the refinery residue as a
20 raw material according to the related art, thereby
completing the present invention.
【Disclosure】
【Technical Problem】
5
An object of the present invention is to provide a
method for preparing synthesis gas by which greenhouse gas
emissions may be reduced, operating costs of a gasification
process may be reduced, and process efficiency may be
5 improved, as compared with the case of using a refinery
residue as a raw material according to the related art, by
using pyrolysis fuel oil (PFO) discharged in a naphtha
cracking center (NCC) process as the raw material for the
gasification process.
10
【Technical Solution】
In one general aspect, a method for preparing
synthesis gas and aromatic hydrocarbons includes: supplying
a pyrolysis fuel oil (PFO) stream containing PFO and a
15 pyrolysis gas oil (PGO) stream containing PGO to a
distillation tower as a feed stream (S10), the PFO stream
and the PGO stream being discharged in a naphtha cracking
center (NCC) process; and supplying a lower discharge
stream from the distillation tower to a combustion chamber
20 for a gasification process and supplying an upper discharge
stream from the distillation tower to a BTX preparation
process (S20).
【Advantageous Effects】
6
According to the present invention, the pyrolysis fuel
oil (PFO) and the pyrolysis gas oil (PGO) in the naphtha
cracking center (NCC) process are pretreated and used as
the raw material for the gasification process, such that
5 greenhouse gas emissions may be reduced, operating costs of
the gasification process may be reduced, and process
efficiency may be improved, as compared with the case of
using the refinery residue as the raw material according to
the related art.
10 In addition, light pyrolysis fuel oil generated during
the process of pretreating the pyrolysis fuel oil (PFO) and
the pyrolysis gas oil (PGO) are used as raw materials for
preparing BTX together with the raw pyrolysis gasoline
(RPG), such that production of the BTX may be increased.
15
【Description of Drawings】
FIG. 1 is a process flow diagram for a method for
preparing synthesis gas and aromatic hydrocarbons according
to an exemplary embodiment of the present invention.
20 FIG. 2 is a process flow diagram for a method for
preparing synthesis gas and aromatic hydrocarbons according
to Comparative Example 1 of the present invention.
FIG. 3 is a process flow diagram for a method for
preparing synthesis gas and aromatic hydrocarbons according
7
to Comparative Example 2 of the present invention.
FIG. 4 is a process flow diagram for a method for
preparing synthesis gas and aromatic hydrocarbons according
to Comparative Example 3 of the present invention.
5
【Best Mode】
The terms and words used in the description and claims
of the present invention are not to be construed limitedly
as having general or dictionary meanings but are to be
10 construed as having meanings and concepts meeting the
technical ideas of the present invention, based on a
principle that the inventors are able to appropriately
define the concepts of terms in order to describe their own
inventions in the best mode.
15 The term “stream” in the present invention may refer
to a flow of a fluid in a process, or may refer to a fluid
itself flowing in a pipe. Specifically, the “stream” may
refer to both a fluid itself flowing in a pipe connecting
respective apparatuses to each other and a flow of a fluid.
20 In addition, the fluid may refer to a gas or liquid, and a
case in which a solid substance is included in the fluid is
not excluded.
In the present invention, the term “C#” in which “#”
is a positive integer represents all hydrocarbons having #
8
carbon atoms. Therefore, the term “C8” represents a
hydrocarbon compound having 8 carbon atoms. In addition,
the term “C#-” represents all hydrocarbon molecules having
# or fewer carbon atoms. Therefore, the term “C8-”
5 represents a hydrocarbon compound having 8 or fewer carbon
atoms. In addition, the term “C#+” represents all
hydrocarbon molecules having # or more carbon atoms.
Therefore, the term “C10+” represents a hydrocarbon
compound having 10 or more carbon atoms.
10 Hereinafter, the present invention will be described
in more detail with reference to FIG. 1 in order to assist
in the understanding of the present invention.
According to the present invention, there is provided
a method for preparing synthesis gas (syngas) and aromatic
15 hydrocarbons. The method for preparing synthesis gas and
aromatic hydrocarbons may include: supplying a pyrolysis
fuel oil (PFO) stream containing PFO and a pyrolysis gas
oil (PGO) stream containing PGO to a distillation tower 50
as a feed stream (S10), the PFO stream and the PGO stream
20 being discharged in a naphtha cracking center process (S1);
and supplying a lower discharge stream from the
distillation tower 50 to a combustion chamber for a
gasification process (S3) and supplying an upper discharge
stream from the distillation tower 50 to a BTX preparation
9
process (S4) (S20).
The synthesis gas is artificially prepared gas, unlike
natural gas such as naturally derived gas, methane gas, or
ethane gas that is ejected from the land in oil fields and
5 coal fields, and is prepared by the gasification process.
The gasification process is a process of converting a
hydrocarbon such as coal, petroleum, or biomass as a raw
material into synthesis gas mainly containing hydrogen and
carbon monoxide by pyrolysis or a chemical reaction with a
10 gasifying agent such as oxygen, air, or water vapor.
Specifically, in the present invention, the synthesis gas
may contain hydrogen and carbon monoxide. A gasifying
agent and a raw material are supplied to a combustion
chamber positioned at the foremost end of the gasification
15 process to produce synthesis gas by a combustion process at
a temperature of 700°C or higher, and as a kinematic
viscosity of the raw material supplied to the combustion
chamber is higher, a differential pressure in the
combustion chamber is increased or atomization is not
20 smoothly performed, which causes deterioration of
combustion performance or an increase in risk of explosion
due to excessive oxygen.
In the related art, as a raw material for a
gasification process for preparing synthesis gas using a
10
liquid phase hydrocarbon raw material, refinery residues,
such as vacuum residues (VR) and bunker-C oil, discharged
from a refinery where crude oil is refined have been mainly
used. However, since the refinery residue has a high
5 kinematic viscosity, a pretreatment such as a heat
treatment or addition of a diluent or water is required to
use the refinery residue as the raw material for the
gasification process, and since the refinery residue has
high contents of sulfur and nitrogen, production of acidic
10 gas such as hydrogen sulfide and ammonia is increased
during the gasification process. Thus, in order to respond
to tightened environmental regulations, a need to replace
the refinery residue with a raw material having low
contents of sulfur and nitrogen has been raised. For
15 example, among the refinery residues, a vacuum residue may
contain about 3.5 wt% of sulfur and about 3,600 ppm of
nitrogen, and bunker C-oil may contain about 4.5 wt% of
sulfur.
Meanwhile, pyrolysis fuel oil (PFO) discharged in a
20 naphtha cracking center process that is a process of
cracking naphtha to prepare petrochemical basic materials
such as ethylene and propylene is generally used as a fuel.
However, since the pyrolysis fuel oil has a high content of
sulfur for use as a fuel without a pretreatment, the market
11
is getting smaller due to the environmental regulations and
a situation where sales are impossible in the future should
be prepared for.
Accordingly, a method for using the pyrolysis fuel oil
5 as a raw material for a gasification process has been
considered. However, in order to use the pyrolysis fuel
oil as the raw material for the gasification process, the
pyrolysis fuel oil should be heated to lower a kinematic
viscosity thereof, but it is difficult to satisfy a
10 kinematic viscosity condition for use of the pyrolysis fuel
oil as the raw material for the gasification process at a
flash point or lower due to a significantly high kinematic
viscosity of the pyrolysis fuel oil.
Accordingly, the present invention is intended to
15 reduce greenhouse gas emissions, to reduce operating costs
of a gasification process, and to improve process
efficiency, as compared with the case of using a refinery
residue as a raw material according to the related art, by
developing a pretreatment process (S2) for using the
20 pyrolysis fuel oil (PFO) stream containing PFO and the
pyrolysis gas oil (PGO) stream containing PGO that are
discharged in the naphtha cracking center process as the
raw materials for the gasification process. In addition, a
light PFO stream discharged in the pretreatment process
12
(S2) is recovered to prepare aromatic hydrocarbons, such
that production of the aromatic hydrocarbons may be
increased.
According to an exemplary embodiment of the present
5 invention, the raw pyrolysis gasoline (RPG) stream
containing RPG, the pyrolysis fuel oil (PFO) stream
containing PFO, and the pyrolysis gas oil (PGO) stream
containing PGO may be discharged in the naphtha cracking
center process (S1).
10 Specifically, the naphtha cracking center process is a
process of cracking naphtha containing paraffin, naphthene,
and an aromatic compound (aromatics) to produce ethylene,
propylene, butylene, and benzene, toluene, and xylene (BTX)
used as petrochemical basic materials, and the naphtha
15 cracking center process may be largely composed of a
cracking process, a quenching process, a compression
process, and a refining process.
The cracking process is a process of cracking naphtha
into hydrocarbons having fewer carbon atoms in a cracking
20 furnace at 800°C or higher, and may discharge cracked gas
at a high temperature. Here, the naphtha may be subjected
to a preheating process with high pressure water vapor
before entering the cracking furnace, and then, the
preheated naphtha may be supplied to the cracking furnace.
13
The quenching process is a process of cooling the
cracked gas at a high temperature, for suppressing a
polymerization reaction of hydrocarbons in the cracked gas
at a high temperature discharged from the cracking furnace,
5 recovering waste heat, and decreasing a heat load in a
subsequent process (compression process). Here, the
quenching process may include primary cooling of the
cracked gas at a high temperature with quench oil and
secondary cooling with quench water.
10 Specifically, in the primary cooling, the cracked gas
may be supplied to a gasoline fractionator to separate
light oil containing hydrogen, methane, ethylene, propylene,
and the like, the raw pyrolysis gasoline (RPG), the
pyrolysis fuel oil (PFO), and the pyrolysis gas oil (PGO)
15 from the cracked gas. Thereafter, the light oil may be
transported to a subsequent compression process.
The compression process may be a process of producing
compressed gas having a reduced volume by elevating a
pressure of the light oil under a high pressure for
20 economically separating and refining the light oil.
The refining process is a process of cooling the
compressed gas which is compressed with a high pressure to
a cryogenic temperature and then separating components in
stages by a boiling point difference, and may produce
14
hydrogen, ethylene, propylene, propane, C4 oil, raw
pyrolysis gasoline (RPG), and the like.
As described above, in the quenching process in the
naphtha cracking center process (S1), the raw pyrolysis
5 gasoline (RPG), the pyrolysis fuel oil (PFO), and the
pyrolysis gas oil (PGO) may be discharged. In general, the
pyrolysis fuel oil (PFO) contains about 0.1 wt% or less of
sulfur and about 20 ppm or less of nitrogen, and when it is
used as a fuel, sulfur oxides (SOx) and nitrogen oxides
10 (NOx) are discharged during a combustion process, and thus,
environmental issues may be raised. However, in a case
where the pyrolysis fuel oil (PFO) is used as a raw
material of synthesis gas, the environmental issues are
quite small.
15 Accordingly, in the present invention, the above
problems may be solved by pretreating the pyrolysis fuel
oil (PFO) and the pyrolysis gas oil (PGO) by the
pretreatment process (S2) and using them as the raw
materials for the gasification process for preparing
20 synthesis gas, and greenhouse gas emissions may be reduced,
operating costs of the gasification process may be reduced,
and process efficiency may be improved, as compared with
the case of using the refinery residue as the raw material
for the gasification process according to the related art.

【CLAIMS】
【Claim 1】
A method for preparing synthesis gas and aromatic
hydrocarbons, the method comprising:
5 supplying a pyrolysis fuel oil (PFO) stream containing
PFO and a pyrolysis gas oil (PGO) stream containing PGO to
a distillation tower as a feed stream (S10), the PFO stream
and the PGO stream being discharged in a naphtha cracking
center (NCC) process; and
10 supplying a lower discharge stream from the
distillation tower to a combustion chamber for a
gasification process and supplying an upper discharge
stream from the distillation tower to a BTX preparation
process(S20).
15
【Claim 2】
The method of claim 1, wherein a ratio of a flow rate
of the upper discharge stream from the distillation tower
to a flow rate of the feed stream to be supplied to the
20 distillation tower is 0.01 to 0.2.
【Claim 3】
The method of claim 1, wherein a ratio of a flow rate
of the upper discharge stream from the distillation tower
56
to a flow rate of the feed stream to be supplied to the
distillation tower is 0.1 to 0.2.
【Claim 4】
5 The method of claim 1, wherein a kinematic viscosity
of the lower discharge stream from the distillation tower
at the time of supply to the combustion chamber is 300 cSt
or less, and
wherein a flash point of the lower discharge stream
10 from the distillation tower is higher than a temperature at
the time of supply to the combustion chamber by 25°C or
more.
【Claim 5】
15 The method of claim 1, wherein a temperature of the
lower discharge stream from the distillation tower at the
time of supply to the combustion chamber is 20°C to 90°C.
【Claim 6】
20 The method of claim 1, wherein the lower discharge
stream from the distillation tower passes through a fourth
heat exchanger before being supplied to the combustion
chamber.
57
【Claim 7】
The method of claim 1, wherein the PGO stream contains
70 wt% or more of C10 to C12 hydrocarbons, and
the PFO stream contains 70 wt% or more of C13+
5 hydrocarbons.
【Claim 8】
The method of claim 1, wherein a flash point of the
PGO stream is 10 to 50°C, and
wherein a flash point of the PFO stream is 70 to 200°C.
10
【Claim 9】
The method of claim 1, wherein a kinematic viscosity
of the PGO stream at 40°C is 1 to 200 cSt, and
wherein a kinematic viscosity of the PFO stream at
15 40°C is 400 to 100,000 cSt.
【Claim 10】
The method of claim 1, wherein a raw pyrolysis
gasoline (RPG) stream containing RPG discharged from the
20 naphtha cracking center (NCC) process is supplied to the
BTX preparation process.
【Claim 11】
The method of claim 1, wherein the PGO stream is a
58
lower discharge stream discharged from a lower portion of a
first stripper after supplying a side discharge stream
discharged from a side portion of a gasoline fractionator
in the naphtha cracking center process to the first
5 stripper, and
wherien the PFO stream is a lower discharge stream
discharged from a lower portion of a second stripper after
supplying a lower discharge stream discharged from a lower
portion of the gasoline fractionator in the naphtha
10 cracking center process to the second stripper.
【Claim 12】
The method of claim 11, wherein the lower discharge
stream from the gasoline fractionator is discharged at a
stage of 90% or more of a total number of stages of the
15 gasoline fractionator, and
wherein the side discharge stream from the gasoline
fractionator is discharged at a stage of 10% to 70% of the
total number of stages of the gasoline fractionator.
20 【Claim 13】
The method of claim 1, wherein a reflux ratio of the
distillation tower is 0.01 to 10.