The achievement and performance of SINOPEC’s ethylene production in 2024 are introduced and analyzed briefly from the aspects of safety and environmental protection, feedstock and operation optimization, energy saving and consumption reduction, technology research, long-term operation and maintenance, and some suggestions and attentive points on SINOPEC’s ethylene production in 2025 are put forward.

This article summarizes the development of CNPC ethylene business in 2024, including the completion of indicators such as ethylene production, ethylene yield, diene yield, processing loss rate, and fuel & power energy consumption of various ethylene production enterprises, as well as the completion of raw material optimization, long-term operation, maintenance, and technological transformation measures. The key work arrangement for the long-term optimization operation of the company's ethylene plant in 2025 has been proposed.

Reducing the unplanned shutdowns of plants is the key to the competitiveness of chemical enterprises. Refining and petrochemical enterprises have strict requirements for management on the unplanned shutdowns of plants. This paper mainly discusses the specific methods for reducing the unplanned shutdowns of ethylene plant from the aspect of systematic management improvement, including improving the hidden danger management and the risk control system, and improving the risk assessment and the scientific decision-making management system. A risk control system with prevention and control as the main focus and with full participation is established through standardized management, including standardized management on large compressor units, standardized management on cracking furnaces, and standardized management on rotating equipment, static equipment, electrical and instrumentation disciplines.

In view of the fracture leakage accident of the circumferential welded joint of a styrene multiple heat exchanger in a petrochemical plant under service conditions, the cause of the accident was determined combined with theoretical discussion through crack morphology observation, simulation heat treatment test for small workpieces, microstructure observation, hardness test and other test methods, some improvement schemes were proposed, and a good result was obtained. The root cause of the leakage during operation of the equipment is that the existing local post-welding heat treatment process can not completely eliminate the welding residual stress of this thick plate structure. During the service of the equipment, the working stress is superimposed on the high circumferential residual stress, and the local stress exceeds the breaking strength of the material itself, resulting in transverse cracks, which cause penetration along the thickness direction and eventually lead to leakage accidents. The overall post-welding heat treatment process with better temperature field uniformity can eliminate residual stress, reduce joint hardness, enhance ductility, improve its cracking resistance under harsh working conditions, and avoid the occurrence of such leakage accidents.

In ethylene plants, volatile hydrocarbons and dissolved gases are stripped from process water in process water stripper and sent to quench water tower. The stable operation of process water stripper can effectively ensure the stable operation of ethane feed saturator and steam standby generator. During practical operation, due to factors such as instrument failures and process fluctuations, there is a loss of pressure in the process water stripper, which seriously affects the stable operation of the process. This article proposes some effective measures against the loss of pressure in process water stripper, analyzes the reasons for the loss of pressure, and proposes some process improvement measures to ensure the stable operation of process water stripper.

Currently, manual monitoring is adopted for the monitoring of most pumps in the petrochemical industry, and vibration, temperature and acceleration are mainly monitored. However, this monitoring method has severe limitations, such as limited monitoring time. Real-time monitoring of equipment operation cannot be achieved by manual monitoring, especially in petrochemical enterprises with a large number of pumps. Therefore, it is difficult to detect the early failures of equipment, thus increasing the probability of equipment accidents. This article introduces an online monitoring technology for pumps, which can be used to detect the early failures of pumps and provide effective support for preventing equipment accidents.

The tower kettle pump of the cooling system in a butadiene extraction unit automatically shut down during normal operation. Through the analysis and study on the process operation status, sealing structure, material and lubrication of the pump, this paper finds out the reasons for the shutdown of the tower kettle pump of cooling system, and puts forward some effective improvement methods, thus prolonging the operation cycle of the pump and improving the continuity and stability of unit production.

A 1.0 Mt/a ethylene plant was modified during its overhaul in 2019 to expand its capacity to 1.1 million tons per year. After capacity expansion, the plant has been continuously operated at high load. The heat exchange capacity of quench water heat exchanger could not meet the production requirements when the temperature of circulating water was high in summer and during the feeding and unloading of cracking furnace. The kettle temperature and top temperature of quench water tower were too high, so that some heavy hydrocarbons and water entered the cracking gas compressor system through the top of the quench water tower, increasing the operating load of the compressor and intensifying the risk of coking in compressor impeller channel. By increasing the heat exchange area of quench water heat exchanger, the problem of insufficient heat exchange capacity of the heat exchanger in summer and during the feeding and unloading of cracking furnace was solved, the operation cycle of the plant was prolonged, and good effect was achieved.

At present, portable ultrasonic flow meter is used for the cooling water flow meter of circulating water cooler in the 220 kt/a ethylene plant in Dushanzi. Because it has been used for many years, the probe is aged and the measurement accuracy and sensitivity are poor. Comparing the monitoring data of the portable ultrasonic meter with the measurement data displayed by DCS in May 2023, it is found that the monitoring results of the portable ultrasonic meter are about 66.7％ higher than the actual values. As a result, the circulating water consumption of the circulating water cooler of the plant increases by 9.32％ compared with the design value, which seriously affects the operation energy consumption of the plant. In order to scientifically control the circulating water consumption, the operation data of the circulating water heat exchanger under the current production conditions are collected, including material components, material inlet and outlet temperature/pressure, circulating water inlet and outlet temperature/pressure, etc. Aspen Hysys software is used to simulate the circulating water consumption of each water cooler, find out the deviation points, optimize the control, and achieve the purpose of improving the quality and efficiency.

Steam curtains are used for avoiding fire and explosion accidents in ethylene plants resulting from the ignitions of the released flammables by steam cracking furnaces. Currently, there are few references related to the methods for determing the design parameters of steam curtains. In this paper, the method for determining and adjusting the design parameters based on the release and dispersion scenarios of the flammables is put forward by studying the air entrainment and dilution effects of the steam jet from a steam curtain nozzle on the flammable cloud. It is shown that the method proposed by this paper connects the design paramaters of steam curtains with the selected release and dispersion scenarios, and it is conducive to proposing design paramters meeting the dilution performance required by the selected scenarios.

Regular coke burning is required for cracking furnaces of ethylene plants during operation, and coke burning gas settling tank is the core equipment of cracking furnace. This article takes a coke burning gas settling tank, which was put into use in 1994, as an example. During long-term use, the internal components of the coke burning gas settling tank were seriously eroded and corroded, failing to settle and separate coke particles, and the surface of equipment and the ground were polluted. In order to solve this problem, a cyclone coke burning gas settling tank was used to improve the removal rate of coke particles, remarkably improving the surrounding area of the coke burning gas settling tank.

Binary refrigeration compressor is the critical equipment of ethylene plant. This paper mainly analyzes the causes of the vibration of steam turbine of binary refrigeration compressor in ethylene plant, and uses condition monitoring software to determine through frequency and map analysis that the fundamental causes of vibration are the poor dynamic balance of rotor and the high exhaust temperature. By taking some measures such as replacing the spare rotor after returning to the plant for dynamic balance and using continuous water spray to control the exhaust temperature, the abnormal vibration of the steam turbine is eliminated, and the installation and commissioning of the binary refrigeration compressor are carried out as planned.

The silica analysis index of steam condensate in condenser (E-131) of cracking gas turbine is high and exceeds the standards, not only causing the silica index in the boiler water supply main pipe to reach the high limit, but also directly resulting in the silica index of ultrahigh pressure steam produced by No. 6 and No. 7 furnace steam drum higher than 20 μg/L. This indicates that there is trace leakage in the internal tube bundle of E-131 and a small amount of circulating water in the tube side enters the condensate in the shell side. The condensate in E-131 is cut out of the boiler water supply system, cut into the temporary new pipeline and directly sent to the flash tank of the utilities. After the maintenance and leakage elimination of condenser E-131, the silica index of the condensate returned to normal.