he side reaction of coal indirect liquefaction unit may generate corrosive media such as small molecule organic acids. In order to ensure that the corrosion is controllable, a large number of stainless steel is used in the equipment of the unit, which will lead to a substantial increase in investment.This paper discusses the corrosion characteristics of carbon steel in different media through analyzing the on-site corrosion coupon test results. From the preliminary test results, it can be seen that the corrosion of light oil medium is mild, and there is a feasibility of using carbon steel. However, the corrosion of synthetic water medium is obvious, and carbon steel does not meet the requirements for long-term operation. The above conclusions can provide the basis for more reasonable material selection for the subsequent construction of coal indirect liquefaction units.

Aiming at the requirement of "design service life of pressure vessels" on the general layout of pressure vessel design as stipulated in TSG 21—2016, this paper traces the origin of this requirement, the reason for its formulation, the provisions formulated by the relevant standards for the implementation of this requirement, the implementation situation, as well as the existing confusion and problems. Then it proposes some suggestions for improvement.

In order to ensure the transportation safety of tankers, this paper studies the impact characteristics of the liquid in the tank during the braking process. The standard model was used to conduct numerical simulation analysis of the sloshing impact process of the liquid in the tanker body. The analysis indicates that the filling rate, filling medium and the external excitation have the most significant effect on liquid sloshing in the tank.The numerical simulation of the above three main influencing factors is carried out respectively.The results show that the impact force of liquid sloshing decreases with the increase of the filling rate. As the density of the filling medium increases, the sloshing impact force increases, and the viscosity of the filling medium has negligible effect on the sloshing impact force. With the increase of external excitation, the liquid sloshes violently;the time for the sloshing impact to peak is then advanced, and the sloshing impact force also increases.Finally, the validity of the simulation model is verified by scaling experiment. This study sheds light on how to ensure the safe operation of the hazardous chemical tankers.

As the main equipment accessory of screw compressor, the separation effect of the gas-oil separator directly affects the operational reliability and refrigerating effect of the compressor. This paper introduces the overview of the refrigeration system and the workflow of the compressor. Through studying the structure and principles of the oil-air separator, it identified the multiple factors affecting the effect of oil-gas separation.The above factors were analyzed in depth; corresponding measures were formulated and proposals were made to improve the separation efficiency of the oil-gas separator by applying multi-stage separation technology and combinational separation modes. These measures and recommendations have been taken and made to ensure that the refrigeration capacity of compressors could be improved; the energy saving could be achieved and the long-term stable operation of screw compressors could be guaranteed.

Aiming at the failure of the regeneration fan of a petrochemical aromatics complex unit, data analysis and classification investigation are carried out from the aspects of rapid changesin fan vibration, bearing failure and so on.Professional monitoring and testing techniques in both dynamic and static fieldsare utilized comprehensively to analyze and describe the occurrence and development process of bearing failure. Ultimately, it is determined that the abnormal shutdown of the fan is caused by issues concerning the installation quality of the bearing and the material of the retaining frame. This case indicates that ensuring compliant bearing installation methods and installation quality, as well as selecting the retaining frame material that meets the plasticity and toughness requirements, can effectively prevent fan bearing failures. This can provide reference for preventive maintenance and installation inspections of the equipment.

As the main core equipment, the operation of the heating furnace in petrochemical enterprises is directlyrelated to the safety in production and energy consumption of enterprises. Aiming at the many problems such as excessive flue gas CO content, high O2 content and poor combustion condition of the heating furnace in the operation process, this paper analyzes the causes of the problems and summarizes the methods of finding and solving the problems based on the test diagnosis and adjustment. This provides ideas for the daily management of heating furnace in petrochemical enterprises.

A catalytic cracking axial compressor unit of a certain company underwent abnormal shutdown due to the fracture of its moving blades during service. After the disassembly of the unit, the fracture surface of the blades was analyzed by using inspection methods such as macromorphology, chemical composition, microstructure, scanning electron microscopy, and energy dispersive spectroscopy. After analysis, it was found that the main cause of blade fracture was stress concentration at the corrosion pit on the outer arc surface of the blade under alternating stress, which led to fatigue crack propagation, resulting in blade fracture. By absorbing the experience and lessons learned from past cases of axial compressor blade fracture at home and abroad, corresponding measures and suggestions are proposed in such three aspects as operation management, overhaul quality and coating to preventblade fracture failure.

This paper presents the principles of mechanical decoking and compares the advantages and disadvantages of mechanical decoking technology with the traditional steam-air decoking method. Taking the application of mechanical decoking technology in the vacuum furnace of the atmospheric and vacuum distillation (II) unit in one petrochemical company as an example, the paper expatiates onthe operation steps of mechanical decoking. Flow and pressure tests are carried out on all lines of the furnace tubes during the decoking process of this vacuum furnace. And the results show that after mechanical decoking, the average decrease in radiation temperature at the fire box top of the vacuum furnace is 58.3 ℃; the average decrease in surface temperature of the furnace tube is 10.3 ℃; the average decrease in feed pressure of the branch of the furnace tube is 0.20 MPa, and the fuel gas consumption (standard state) is decreased by 333 m3/h.The above results indicate that mechanical decoking is effective and it eliminates the bottleneck of the vacuum furnace operation. This can ensure the long-period safe and stable operation of the vacuum furnace.

The overhead coking problem of the coke tower is a chronic problem forall coke towers indelayed coking units. The traditional coke cutter can remove the coke from the straight section of the coke tower relatively cleanly. However,to remove coke from the top elliptical head of the coke tower requires the release of the interlocking of the coke removal procedure.With the lifting of the drill pipe, the operation method of interlocking release is extremely unsafe for the entire coke removal system and the operators. And the coke at the top elliptical head cannot be cleaned thoroughly. Aiming at the above problem, one petrochemical refinery has developed a reverse blowing coke cutter to ensure the safety of operators and hydraulic coke removal equipment. Since its commissioning, the equipment has been running well so far, which has provided guarantee for the safe and long-cycle production of the coke tower.This paper introduces the components, working principle, design calculation, and practical application of the reverse blowing coke cutter. It is hoped that this canprovide reference for the coke cleaning operation in other similar devices.

The shutdown overhaul and revamp of refining and chemical plants is complex system engineering with arduous tasks, time constraints, and a large amount of on-site cross operations and resource allocation. It has always been a difficulty for enterprise management.Based on the management experience of a mega enterprise in shutdown overhaul in the past 10 years, a cooperative working mechanism of "Headquarters-Sub headquarters" is established. According to the principle of "70% preparation, 30% implementation" and from the four stages of " Planning-Preparation-Implementation-Summary", thispaper summarizes a set of effective and standardized shutdown overhaul management system that adapts to the characteristics of refining and chemical enterprises, and gives full play to management performance through digital applications. This provides experience for reference for shutdown overhaul and revamp of refining and chemical plantsin the future.

The volume of the LNG storage tanks built in China has developed from 160,000 m3 to 270,000 m3. So the welding workload of the storage tank is large, especially the welding of the 9% Ni steel inner tank, which is the key link in the construction of the LNG storage tanks and the requirements for welding quality are also very high. At present, the annular seam adopts submerged arc automatic welding, which realized the mechanization of welding, yet the longitudinal seam adopts electrode arc welding, which not only has high labor intensity, but also has low welding efficiency. Therefore, it is an inevitable trend to develop efficient and stable longitudinal seam automatic welding process technology. This paper presents the longitudinal seam automatic welding technology of LNG storage tank from the aspects of welding method selection, welding equipment development, welding groove design, welding performance test, engineering application and so forth. This can provide reference for the technicians engaged in LNG storage tank welding.

Most of the various media in the petrochemical units are flammable, explosive, high-temperature and high-pressure medium. If there is any problem with the quality of the project, it is very likely to lead to safety accidents. Therefore,ensuring the construction project quality of the petrochemical units is crucial to the smooth operation of the device. And ensuring the welding quality of process pipelines for conveying various media is an important part of it. How to improve the production efficiency and welding quality of process pipe welding is an urgent technical challenge.In order to improve the welding quality and efficiency of the process pipeline of the 8.8 million tons/year residual oil hydrogenation unit, one international engineering project adopted the new technology of all-position automatic welding. Combining the application example of this project, this paper comprehensively expounds the key process points of all-position automatic welding from such aspects as the current situation of all-position automatic welding technology, the development of welding equipment, the performance test of different materials, the key points of operation process, quality requirements, efficacy comparison and engineering application. This technology has not only been well applied in international engineering, but also popularized and applied in many domestic engineering projects, which has effectively promoted the innovation and development of process pipeline welding technology.

Aiming at the problem of weld cracking during hydrotesting of the equipment at a natural gas station, failure analysis of the welds was carried out by macro-morphological and physicochemical tests.The results show that there are such quality problems as root overlap and root incomplete fusion in the girth weldwith unequal wall thickness, and under the combination of hydrotest stress and residual stress, the weld defect starts to crack from the internal surface and extends to the outer wall. According to the causes leading to weld cracking, suggestions including optimizing the groove design, strengthening quality control during construction, and carrying out internal visual inspection and surface non-destructive testing of key welds were put forward, which can provide reference for preventing the failure of welds with unequal wall thicknesses.