Search

EP-4155257-B1 - METHOD FOR PRODUCING SYNTHESIS GAS

EP4155257B1EP 4155257 B1EP4155257 B1EP 4155257B1EP-4155257-B1

Inventors

  • HWANG, SUNG JUNE
  • KIM, TAE WOO
  • KI, Sik
  • LEE, SUNG KYU

Dates

Publication Date
20260506
Application Date
20211212

Claims (12)

  1. A method for preparing synthesis gas, the method comprising: supplying a cracked gas stream discharged from a cracking furnace of a naphtha cracking center (NCC) process to a gasoline fractionator; supplying a side discharge stream of the gasoline fractionator to a first stripper, operating the first stripper under conditions in which a first steam stream is supplied, and separating a PGO stream including a pyrolysis gas oil (PGO) from a lower portion; splitting a lower discharge stream from the gasoline fractionator into a reflux stream and a supply stream, supplying the supply stream to a second stripper, and operating the second stripper under conditions in which a second steam stream is supplied, and separating a PFO stream including a pyrolysis fuel oil (PFO) from a lower portion; and supplying a mixed oil stream of the PGO stream and the PFO stream to a combustion chamber for a gasification process, wherein the following Equations 1 and 2 are satisfied: G ≥ 0.5 , G = GS / GF F ≤ 0.035 , F = FS / FF wherein GF is a flow rate in kg/h of the side discharge stream from the gasoline fractionator, GS is a flow rate in kg/h of the first steam stream, FF is a flow rate in kg/h of the supply stream, and FS is a flow rate in kg/h of the second steam stream.
  2. The method for preparing synthesis gas of claim 1, wherein G is 0.5 to 2.
  3. The method for preparing synthesis gas of claim 1, wherein F is 0.001 to 0.035.
  4. The method for preparing synthesis gas of claim 1, wherein a temperature of the side discharge stream from the gasoline fractionator is 120°C to 180°C, and an operating pressure of the first stripper is 0.5 kg/cm 2 g to 3 kg/cm 2 g.
  5. The method for preparing synthesis gas of claim 1, wherein a temperature of the lower discharge stream from the gasoline fractionator is 150°C to 300°C, and an operating pressure of the second stripper is 0.6 kg/cm 2 g to 3.1 kg/cm 2 g.
  6. The method for preparing synthesis gas of claim 1, wherein each pressure of the first steam stream and the second steam stream is 2 kg/cm 2 g to 20 kg/cm 2 g.
  7. The method for preparing synthesis gas of claim 1, wherein the mixed oil stream has a kinematic viscosity at the time of supply to the combustion chamber of 300 cSt or less, and the mixed oil stream has a flash point higher than a temperature at the time of supply to the combustion chamber by 25°C or more.
  8. The method for preparing synthesis gas of claim 1, wherein the temperature of the mixed oil stream at the time of the supply to the combustion chamber is 20°C to 90°C.
  9. The method for preparing synthesis gas of claim 1, wherein a content of C6- hydrocarbons in the PGO stream is 0.1 wt% or less, and a content of C8 and C9 hydrocarbons in the PFO stream is 3 wt% or more.
  10. The method for preparing synthesis gas of claim 1, wherein the PGO stream has a flash point of 40 to 70°C, and the PFO stream has a flash point of 65 to 190°C.
  11. The method for preparing synthesis gas of claim 1, wherein the PGO stream has a kinematic viscosity at 40°C of 5 to 220 cSt, and the PFO stream has a kinematic viscosity at 40°C of 250 to 70,000 cSt.
  12. The method for preparing synthesis gas of claim 1, wherein the lower discharge stream from the gasoline fractionator is discharged from a stage at 90% or more relative to the total number of stages of the gasoline fractionator, and the side discharge stream from the gasoline fractionator is discharged from a stage at 10% to 70% relative to the total number of stages of the gasoline fractionator.

Description

[Technical Field] Technical Field The present invention relates to a method for preparing synthesis gas, and more particularly, to a method for preparing synthesis gas which allows pyrolyzed fuel oil (PFO) from a naphtha cracking center (NCC) process to be used as a raw material of a gasification process. [Background Art] Synthesis gas (syngas) is an artificially prepared gas, unlike natural gas such as spontaneous gas, methane gas, and ethane gas, which is released from land in oil fields and coal mine areas, and is prepared by a gasification process. The gasification process is a process of converting a hydrocarbon such as coal, petroleum, and biomass as a raw material into synthesis gas mainly composed of oxygen and carbon monoxide by pyrolysis or a chemical reaction with a gasifying agent such as oxygen, air, and water vapor. A 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 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 performed well, so that combustion performance is deteriorated or a risk of explosion is increased due to excessive oxygen. Conventionally, as a raw material of 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 from refinery where crude oil is refined were mainly used. However, since the refinery residue has a high kinematic viscosity, a pretreatment such as a heat treatment, a diluent, or water addition is required to be used as the raw material of the 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, and thus, in order to respond to tightened environmental regulations, a need to replace the refinery residue with raw materials having low contents of sulfur and nitrogen is raised. Meanwhile, a pyrolysis fuel oil (PFO), which is a byproduct discharged from a naphtha cracking center (NCC) process which is a process of preparing petrochemical basic materials such as propylene, is generally used as a fuel, but since the sulfur content is a high level for using the oil as a fuel without a pretreatment and a carbon dioxide (CO2) emission coefficient is large for use as a fuel, the market is getting smaller due to the environmental regulations and a situation where sales are impossible in the future should be prepared. Thus, though a method of replacing the raw material of a gasification process with the pyrolysis fuel oil was considered, in order to use the pyrolysis fuel oil as the raw material of a gasification process, the pyrolysis fuel oil is heated to lower a kinematic viscosity, but the kinematic viscosity of the pyrolysis fuel oil is high, so that it was difficult to satisfy the kinematic viscosity conditions for use as the raw material of the gasification process at a flash point or lower. Accordingly, the present inventors completed the present invention based on the idea that when the pyrolysis fuel oil (PFO) of the naphtha cracking center (NCC) process is used as the raw material of 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 conventional refinery residue as a raw material. US 2021/0087479 A1 discloses an integrated method and apparatus for catalytic cracking of heavy oil and production of syngas. A cracking-gasification coupled reactor having a cracking section and a gasification section is used as a reactor in the method. A heavy oil feedstock is fed into a cracking section to contact with a bed material in a fluidized state that contains a cracking catalyst, a catalytic cracking reaction is conducted under atmospheric pressure to obtain light oil gas and coke. The coke is carried downward by the bed material into a gasification section to conduct a gasification reaction to generate syngas; the syngas goes upward into the cracking section to merge with the light oil-gas, and is guided out from the coupled reactor and enter a gas-solid separation system. Oil-gas-fractionation is performed to a purified oil-gas-product output from the gas-solid separation system to collect light oil and syngas products. [Disclosure] [Technical Problem] An object of the present invention is to provide a method for preparing synthesis gas which may reduce greenhouse gas emissions, reduce operating costs of a gasification process, and improve process efficiency, as compared with the case of a conventional refinery residue as a raw material, by using the pyrolysis fuel oil