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| 2023, Vol. 35,No. 3 Published:25 September 2023 |
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Influence of Ratios of Ethane Feedstock on Cryogenic
Separation System of Ethylene Plant
Wu Xiang
2023, 35 (3):
1-4.
In an ethylene plant with ethane and propane
as the feedstock, the influence of different ratios of ethane feedstock on the
distribution of cracking products was investigated while the total ethylene
yield remained unchanged. The analysis shows that with the increase in ethane
feedstock, hydrogen and recycle ethane remarkably increased while other components
decreased to varying degrees. Based on this, the influence of different ratios of
ethane feedstock on the cryogenic separation in ethylene plant is studied. The
conventional adjustment methods for cryogenic separation system with different ratios
of ethane feedstock are summarized, and the power consumption of cracking gas
compressor, propylene compressor and ethylene compressor with different ratios
of ethane feedstock is compared with each other through process simulation.
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Fast
Start-up Strategy of Ethylene Plant with Near Zero Emission
Jiang Pengfei, Hong Kun, Zhang Le, Shen Guangming, Zhao Cong
2023, 35 (3):
5-12.
The optimization of the start-up process of ethylene plant is crucial to
reducing flare emissions. Before the cracking furnace is fed, the nitrogen
cycle of cracked gas compressor is used to start the pre-cooling of separation
cold zone, and the temperature in cold box and demethanization system is reduced
to -110～120℃.
A new ethane cracking furnace is installed to increase the steam generation
during the start-up, and the nitrogen pre-cooling is carried out at higher
pressure, so that the outlet pressure of the cracked gas compressor can reach
the allowable value of the feed to separation system without feeding materials.
While the pre-cooling time is shortened, the time required for pressurizing the
separation system is reduced, greatly reducing the flare emissions during the
start-up.
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Analysis of Factors Affecting Long-term Operation of C5 Separation
Unit and the Countermeasures
Zhou Zhaofang
2023, 35 (3):
13-16.
C5 fraction is
rich in diolefins, including isoprene, piperylene, and dicyclopentadiene. These
diolefins play an important role in fine chemicals. The extraction separation
system in a C5 separation unit of SINOPEC has shortcomings such as
short operating cycle, which seriously affects the economic benefits of the unit.
After comprehensive analysis and demonstration, it is concluded that the design
defects of process equipment, the chemical performance, the parameter control, the
poor quality of circulating solvent and the high content of free oxygen and
water in the system are the main factors restricting the length of operating
cycle. Technical research has been carried out to solve the above problems, and
good results have been achieved. The operation cycle of the extraction system
is greatly prolonged, the parameters of the system are within a reasonable
range, the loss rate of target products is low, and the switching cycle of equipment
is normal.
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Tail
Gas Recovery Process for Butadiene Extraction Unit by Acetonitrile
Pi Yuxi
2023, 35 (3):
17-20.
Butadiene
extraction process by acetonitrile is the main process for the production of 1,3-butadiene,
and the tail gas from the unit is directly vented to flare system. With the
rapid development of China’s chemical industry, the rational
use of tail gas can not only improve economic benefits, but also meet the
principle of sustainable development. In this paper, the recovery and
utilization of tail gas from the solvent recovery system in butadiene
extraction unit by acetonitrile is studied. The results show that the
improved tail gas recovery process can recover an additional 496 tons of C4 and recover 128 tons of acetonitrile loss each year.
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Application Analysis of Ethylene Delivery Technology for Steam
Cracking Unit
Shao Ming, Liang Zhaoyuan, Zheng Wenjing, Li Binrong
2023, 35 (3):
21-24.
This paper introduces the
ethylene distillation column - ethylene refrigeration compressor open heat pump
technology, the technology for direct delivery of ethylene products to downstream
units and the ethylene spherical tank/low-temperature ethylene tank technology applied
in the 800 kt/a steam cracking unit of a refining and petrochemical company, and
analyzes the combined application of these technologies. These technologies
have effectively improved the anti-fluctuation ability of the unit.
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Application
of Aerogel Insulation Technology in SS Pipelines of Ethylene Plant
Yang Fan, Yang Jianwei, Wang Junjie, Zhang Yue, Shang Yongfu
2023, 35 (3):
25-28.
The super high pressure steam (SS) pipelines of
the 220 kt/a ethylene plant at PetroChina
Dushanzi Petrochemical Company have been used for a long time, and the
insulation effect is poor. The overtemperature of pipeline surface causes
safety hazards to personnel in maintenance and inspection, and the great heat
loss is not conducive to the normal operation of cracking gas compressor. It is
necessary to replace the insulation material of some steam pipelines with
aerogel to eliminate the potential safety hazards and achieve the goals of
production increase and consumption reduction.
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Study on Influence of Depressurization Operation of Ethylene
Rectification Tower
Yang Liqing
2023, 35 (3):
29-32.
Through
investigating the influence of depressurization operation of the ethylene rectification tower in an ethylene
plant on overhead condenser, ethylene sphere tank, tower load and cooling
capacity recovery of cycle ethane, it is found that overhead condenser and
ethylene sphere tank are the main bottlenecks of the depressurization
operation. After revamping the overhead condenser and the ethylene sphere tank,
the ethylene rectification tower can be
depressurized to 1.63 MPa (G), saving the operating cost by 4.5 million yuan
per year. It is estimated that the revamping cost of 27 million yuan can be
recovered in nearly 6 years.
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Optimization
Measures for Quenching System during Short-term Shutdown of Ethylene Plant
Wang Chuang, Ding Yukui, Zhang Mingcan, Nuermaimaiti•Sullidan, Liu Minzhuan
2023, 35 (3):
33-34.
In 2022, the 220 kt/a
ethylene plant at PetroChina Dushanzi
Petrochemical Company faced some problems such as the relocation of
control room and the operation bottleneck of cracking gas compressor. The
company overcame the adverse factors affecting the quenching system and tried
to stably operate the quenching system with materials, reducing the startup and
shutdown time of the ethylene plant and achieving good effect.
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Discussion on Piping Design
of Ultra-high Pressure Steam Lines Going to the Main on Pipe Rack
Zhou Fan
2023, 35 (3):
35-39.
Generating ultra-high
pressure steam is an important way to recover the energy of ethylene cracking
furnace. The ultra-high pressure steam line going to the main on pipe rack has
become one of the important lines in cracking furnace area due to its high
temperature and pressure and special material. Taking the heavy oil furnace in the
cracking furnace area of a newly-built ethylene plant as an example, this paper
introduces the layout ideas of the ultra-high pressure steam lines going to the
main on pipe rack, the pipe rack design and the precautions, and discusses the
layout scheme of muffler. Through the comparison between two valve group layout
schemes, it is concluded that the second scheme is more convenient for the
operation, inspection and maintenance of valves on the platform and can save
investment. Therefore, the second scheme is finally determined as the first
choice.
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Anti-corrosion Technology for
Quench Water and Dilution Steam Systems in Ethylene Plants
Wang Junda
2023, 35 (3):
40-43.
To
solve the problems such as increased energy consumption, shortened operating
cycle and pipeline blockage caused by the corrosion leakage of dilution steam system
in ethylene plant, this paper identifies the root causes of the corrosion of quench
water and dilution steam systems through technical research and experience
summary, and establishes anti-corrosion technological processes and monitoring
analysis standards to guide the unit in strengthening equipment operation
management, improving corrosion monitoring and detection effectiveness,
optimizing process anti-corrosion measures and eliminating corrosion hazards, so
as to ensure the long-term operation of critical equipment in the quench water
and dilution steam systems.
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Analysis of Factors
Affecting Long Cycle Operation of Butadiene Plant and the Countermeasures
Zu Guoying, Wang Jinzhu, Chen Gang, Zhan Chunzhi, Halimire·Karemulati
2023, 35 (3):
49-51.
The butadiene plant in the old area of PetroChina
Dushanzi Petrochemical Company has been in operation since August 1995. It was
forced to shut down due to polymerization problem after only less than half a
year of operation, and it was shut down four times in 1997. Long cycle
operation of the plant has been a difficult problem to solve. After technical
research and transformation, the operation cycle of the plant was gradually
extended to one year and finally reached four years. In this paper, the factors
affecting the long cycle operation of butadiene plant are analyzed, and the
best methods for extending the operation cycle are investigated, so as to increase
the load of the plant and ensure the safe and stable operation of the plant.
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Standardized Transformation
Schemes for SL-Ⅱ Ethylene Cracking
Furnaces
Gao Xiaolei
2023, 35 (3):
52-56.
Combined with the overall plan of
cracking furnace, the original design of cracking furnace and the actual
situations on site, this article introduces how to implement the standardized
transformation of radiation coil, radiation section lining, radiation section
steel structure, convection coil, convection section steel structure and
convection section lining of two SL-Ⅱethylene cracking furnaces,
explains the application scope and implementation of different standardized
transformation schemes, and discusses the scientific nature, rationality and feasibility
of the transformation schemes.
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Cause Analysis of Corrosion
Leakage of Convection Tubes in Ethylene Cracking Furnace
Zhang Guodong, Chen Qi, Bai Taotao, Wang Mingming, Ding Shaohui
2023, 35 (3):
57-60.
The corrosion of convection
tubes in ethylene cracking furnace is introduced in this paper. The appearance
of corrosion leakage location, furnace tube material, metallography,
microstructure and scale layer are inspected. The causes of corrosion are
analyzed based on the inspection results. It is concluded that the corrosion
leakage is resulted by the condensate in convection section and the sulfur
element in naphtha, and some measures for operation optimization and process
modification are proposed.
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Comparative Analysis of High and Low Temperature Methanation Catalysts
for Ethylene Plant
Huang Bowei, Liu Minzhuan, Yang Juping, Jia Zhe, Jia Yuexian
2023, 35 (3):
61-64.
The
CO-containing crude hydrogen separated from cold box system is purified in the methanation
reactor of the 220 kt/a ethylene plant of PetroChina Dushanzi Petrochemical
Company by nickel-based catalysts at 288～323℃ to remove the CO in crude hydrogen. The hydrogen from the reactor is
cooled, dried and dehydrated before being sent to downstream users. This paper
introduces the use of high temperature catalyst in the methanation reactor of
this ethylene plant, compares and analyzes the performance of high temperature
catalyst with that of low temperature catalyst, and lists the advantages and
disadvantages of these two catalysts. The comparison of the impact of these two
catalysts on energy consumption shows that low temperature catalyst has better
energy-saving effect.
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Supervisor: China petrochemical corporation