This paper presents an investigation into the carburization and mechanical property testing of the inlet tube in the radiation section of an SL-Ⅰ ethylene cracking furnace in a petrochemical enterprise during its service life. The testing encompasses observation of carburization degree, scanning electron microscopy (SEM) observation, tensile test at room temperature and high temperature durability test. The results indicate that for the 25Cr35NiNb+MA inlet tube of SL-Ⅰ cracking furnace, the most serious carburizing part is 4~6 m away from the bottom of the furnace, and the maximum carburizing layer thickness of the inner wall of the inlet tubes after 4, 6 and 8 years of service accounts for 35%, 70% and 100% of the wall thickness respectively. The yield strength of the inlet tubes with 4, 6 and 8 years of service decreased by 4%, 10% and 17% respectively compared with the new furnace tubes not in service. The tensile strength decreased by 15%, 18% and 32% respectively. Elongation after fracture decreased by 59%, 68% and 82% respectively. The high temperature rupture time of inlet tubes with 4, 6 and 8 years of service decreased by about 64%, 77% and 88% respectively. To address the issues of carburization and mechanical performance degradation, the paper provides operational recommendations for the inlet tubes in the radiation section of SL-Ⅰ type ethylene cracking furnace.

The reduction of diesel fuel as ethylene feedstock by enterprises have led to the trend of heavier feedstock for ethylene plants, posing severe challenges to the operation of the quenching system. Taking an 800 kt/a ethylene plant as an example, this paper investigates the impact of heavy feedstock on product distribution, heat balance of the quenching system and equipment operation. The results indicate that as the feedstock becomes heavier, the ethylene yield decreases; the total heat content of the cracked gas at the outlet of the Transfer Line Exchanger (TLE) increases; and the heat extraction from quench oil, section oil and quench water system increases significantly. The flow rates of heavy byproducts and internal recirculation streams within the quench system also show substantial increases. The adaptability verification of associated equipment needs to be performed.

Under the current trend of heavier and more diverse ethylene feedstock, it is of great significance to study the operation and performance of critical equipment such as cracking gas compressors and addressing operational bottlenecks for achieving long-term stable operation of ethylene plants. The compressor and steam turbine form a mechanical coupling relationship through the "driving-driven" mechanism. As the power source, the steam turbine together with the compressor, acting as the load, constitutes a "power-load" system. Their coordinated and stable operational state is a key factor determining the safety and economic efficiency of the process unit. Fluctuations in the steam turbine's rotation speed are directly transmitted to the compressor, leading to issues such as process parameter instability, mechanical damage to equipment and increased energy consumption. This poses significant threats to the operational stability and safety of the unit. This paper addressed the issue of rotation speed fluctuations observed in the steam turbine of a cracking gas compressor at an ethylene plant following a major overhaul. It analyzes the causes of the problem based on the abnormal phenomena, detailed the step-by-step troubleshooting process involving various corrective measures and ultimately identified the governor pilot valve as the root cause of the failure. Through in-depth research on the structure and operational mechanism of the pilot valve, it was discovered that poor lubricant flow conditions within the throttle valve led to oil fouling and sticking of the sliding valve. By adjusting the oil discharge hole regulating valve of the pilot valve and increasing the oil injection volume, the problem was resolved.

This paper presents research on the development of high-performance Ni/Al₂O₃ catalyst for the single-stage hydrogenation of heavy ethylene tar. The research fabricated an Al₂O₃ support with larger pore sizes and higher strength through a graded pore creation technique. Following zirconium modification and induced decomposition under varying atmospheres, the dispersion of the nickel component was significantly enhanced. In terms of the process, the solvent deasphalting combined with hydrotreating scheme was employed. Under an inlet temperatures of 120 ℃ and pressures ranging from 2.0 to 5.0 MPa, a 200-hour stability test was conducted. The results show that this catalyst exhibits superior catalytic activity and stability for deasphalted tar hydrotreating compared to direct hydrotreating, demonstrating strong potential for industrial application.

To investigate the effects of increasing combustion air temperature on the temperature distribution within the furnace, this paper employs CFD simulation technology to conduct a comprehensive simulation of the furnace chamber in a large-scale ethylene cracking furnace. Through analysis of several characteristic planes, it is concluded that progressive increases in combustion air preheat temperature under constant total power input to the cracking furnace chamber result in gradual elevation of flame temperatures in bottom burners, a modest rise in overall furnace temperature and essentially stable average temperatures at the furnace outlet. The findings of this study indicate that raising the combustion air preheat temperature can reduce fuel gas consumption, thereby achieving energy conservation and emission reduction.

The safety and stability of the power system are the foundation for the safe operation of equipment. Research into enhancing the reliability is of great importance for ensuring the long-term operation of equipment. This paper presents a practical case of ethylene plant shutdown caused by power grid fluctuation, detailing the power outage process and analyzing the causes of the failure from such aspects as primary equipment and protection configuration. The analysis indicates that the primary causes of the outage were the main transformer capacity failing to meet N-1 requirements, unreasonable regional stability control configurations and wiring errors during the instrumentation power supply transformation. Based on this, further analysis was conducted on management weaknesses. Then targeted solutions and control measures were proposed.

The normal operation of the convection section of cracking furnace in ethylene plant is one of the important factors affecting the long-term operation of cracking furnace. The convection section operates under complex conditions, making it prone to leaks with their locations and causes varying. A statistical analysis was conducted on corrosion-induced leaks occurring in the convection section of a cracking furnace of a petrochemical company in recent years. And the typical leak cases were analyzed in detail by means of macroscopic morphology inspection, energy spectrum and scanning electron microscope inspection, sample physical and chemical inspection and other methods. The results indicate that leaks in the convection section were primarily caused by corrosion perforation resulting from abnormalities in the dilution steam system, feedstock system, and other external factors. Based on the analysis results, the preventive measures against the abnormalities in the dilution steam system and feedstock system were proposed to prevent the corrosion of the convection section furnace tubes. This also provided guidance for the operation and preventive maintenance of the cracking furnace in the future.

With the continuous development of the ethylene industry, the trend toward lighter feedstock has become prominent, making ethane cracking for ethylene production a focus of industrial manufacturing. As the core of cracking furnace simulation, the accuracy of cracking reaction kinetic models is crucial for ethylene production process simulation. The paper provides a comprehensive review of the methods, advantages and disadvantages, accuracy and application directions of different types of kinetic models for ethane cracking reactions. It particularly highlights the research progress and computational accuracy of both commercially available software utilizing mechanistic models and the recently developed quantum chemical calculation-based mechanistic models, thereby guiding the selection of kinetic models for different scenarios.

The paper introduces the layout, types, and characteristics of low-nitrogen oxides (NO_x) burners in ethylene cracking furnaces. Based on these three aspects and combined with the combustion principles and operational features of low-NO_x burners, it conducts an in-depth study to summarize operation and maintenance practices and precautions suitable for this category of burners. Meanwhile, aiming to address typical operation and operation-related issues of low NO_x burners in existing in-service units, it puts forward improvement measures from the aspects of design, operation and maintenance. These measures have resolved the current practical problems effectively, overcoming the operational bottlenecks in low-NO_x burners. This can provide technical support for achieving long-term operation of low-NO_x burners in cracking furnaces.

As a critical piece of equipment in ethylene cracking units, the structural design reliability of the steam drum has a decisive impact on the long-term safe operation of the entire plant. This paper systematically analyzes the structural configurations of the internal gas-liquid separation devices within high-pressure steam drums for large ethylene cracking furnaces. It clarifies the key requirements for separation efficiency and pressure drop, with a focused discussion on the influence mechanism of the structural parameters of the wire mesh demister on separation performance. Meanwhile, corresponding optimized design solutions are proposed for key components such as the boiler feedwater distribution device, supports for large-diameter, long-cylinder steam drums, and manhole structures. Furthermore, essential maintenance points for the safe operation of steam drums are summarized. Based on the structural and design optimizations, the operational reliability of the high-pressure steam drum has been enhanced. This provides effective technical support for the stable operation of the ethylene plant.

Based on the analysis of data generated from COILSIM simulations of ethylene cracking furnace operations, a system has been established to correlate cracking products with the market prices of final ethylene products and by-products. An integrated optimization model has been developed. The model enables economic-oriented simulation of ethylene cracking furnace operations and optimize the ethylene feedstock composition and furnace operating parameters, achieving energy conservation, reduced consumption and maximized economic benefits.