Aiming at the leakage problem of alloy 825 heat exchange tube in high heat gas steam generator during its application, this paper performed finite element analysis on the expansion structure of the adhesion expansion and then provided the recommended expansion pressure for adhesion expansion. Taking the seam corrosion factors into account, the expanded joint structure of slotted expansion was designed. And through simulation and analysis, the proper expansion pressure and the degree of expansion were presented. These can provide reference for the expansion process of alloy 825 heat exchange tube.

For accurate evaluation of the safety of pressure vessels with complex structure containing defects beyond tolerance, this paper takes the alkylation reactor with planar defects beyond tolerance in the weld of the inclined pipe and cylinder as an example and makes qualitative and precise quantitative analysis of defects and failure modes by using new technologies such as the phased array. Combining with finite element analysis method, it also carries out research on fitness-for-service assessment. The research results indicate that the potential failure mode of the alkylation reactor was the elastoplastic fracture failure; the evaluation points were located in the safety zone of the failure evaluation diagram which was calculated by adopting conventional planar defect evaluation method. This study provides a scientific basis for the safe operation of the reactor and is of reference and significance for similar engineering projects.

For U-tubular or floating head heat exchangers with multiple tube passes, large temperature difference between inlet and outlet of tube pass, high pressure and tube-sheet clamped by channel flange and shell flange, leakage often occurs at the channel flange. Based on the analysis of flange sealing mechanism and the influence law of internal pressure, pass partition, channel temperature and circumferential temperature gradient on the gasket residual compression pressure, this paper expounds the inevitable causes of local leakage on the sealing surface of the channel flange of this kind of heat exchanger, and puts forward the preventive and remedial measures to prevent this kind of leakage accordingly. In particular, taking the successful anti-leakage design of a heat exchanger with harsh working conditions in engineering as an example, the paper introduces a complete set of preventive structure optimization design method.

In order to obtain high performance of the printed circuit plate heat exchanger for dry gas compressor, the mechanical properties of the stainless steel material 316L diffusion welded joints are investigated under different diffusion welding processes in working condition. The results confirm that the joint strength and toughness increase with the increase in welding temperature; when the welding temperature is higher than 1,060 ℃, the welding strength variation tendency is small; the joint yield strength and toughness increase with the increase in welding pressure; when the welding pressure is greater than 10 MPa, the joint mechanical properties change is small; with the extension of holding time, the strength changes slightly while the toughness increases. After comprehensive consideration, the process is optimized as follows: the diffusion welding temperature is 1,060~1,120 ℃, the welding pressure is 10~13 MPa, and the holding time is 60 min.

In this paper, the statistical analysis is carried out on unplanned shutdown failure of Sinopec's fluid catalytic cracking (FCC) units in the past three years. The results indicate that the unplanned shutdown caused by static equipment accounted for 19.64%, and the main influencing factors are wear, aging and cracking of anti-re-internal component, and stress cracking of high-temperature smoke ducts and expansion joints, corrosion and leakage of low-temperature parts, failure of special valves, etc. The unplanned shutdown caused by dynamic equipment accounted for 19.64%, and the main influencing factors are blade fractures, rotor imbalance, misalignment, and surge of large-scale units. Based on the analysis results, measures such as increasing the depth of inspection and maintenance of key parts, building a reliability database, and developing equipment online intelligent early warning technology are proposed to improve the long-term operation of the device.

Eulerian-Eulerian model was applied to conduct 3D CFD (Computational Fluid Dynamics) numerical simulation of the gas-liquid flow in the outlet pipeline of the heating furnace in hydrorefining unit. The distribution of the concentration field and velocity field of gas-liquid phase under the existing pipeline structure were studied and the optimization of the pipeline arrangement was proposed. The research results indicate that due to the different inertia forces of gas and liquid, a spiral flow was formed in the pipeline in the existing pipeline arrangement scheme after the gas-liquid flow changing multiple directions in the 3D space; by optimizing the arrangement scheme, the driving force along the radial rotationwas partially eliminated and the spiral flow of the fluid was reduced. The research results can provide guidance for the optimization of the arrangement scheme for the outlet pipeline of heating furnace.

During the start-up process of the sulfur recovery unit,operators found rumbling noises inside the medium-pressure steam superheater and evaporator for incinerator and there was vibration on the platform railings of the equipment top. To find out the causes of the equipment vibration, the vibration data of the burner, tail gas incinerator, medium-pressure steam superheater, evaporator for incinerator, platform ladders, railings, top pipes, and silencers were measured at start-up. After analyzing the vibration of the medium-pressure steam superheater and the evaporator for incinerator, it was concluded that the excessive vibration of the silencers releasing steam was its main vibration source, and the vibration could be eliminated through technical renovation and the combustion could be optimized. Meanwhile, the secondary vibration sources could be eliminated.

The designed service life of the furnace tubes in recycle hydrogen furnace in high-pressure hydrocracking unit is generally 100,000 hours. However, due to different working conditions, the replacement cycle of the furnace tubes may differ greatly from the designed service life. The furnace tubes in recycle hydrogen furnace in the high-pressure hydrogenation unit of certain petrochemical company has been running for a total of 140,000 hours. In this paper, the remaining service life of the furnace tubes is evaluated through on-site testing, chemical composition analysis and mechanical property test of the furnace tube samples, and then reasonable operation indexes were set and scientific arrangement of furnace tube replacement time was determined. In addition, guidance was presented for the safe operation of the unit in the future.

Atmospheric and vacuum distillation unit is the leading unit of crude oil processing in refineries. Its long-term stable operation capacity determines the "safe, stable, long-term, full capacity and excellent" operation of refineries. With the worsening trend of crude oil processing in refineries, the corrosion of equipment and pipelines in atmospheric and vacuum distillation units, especially in the low-temperature part of the atmospheric column top system, has become a difficult problem and pain point in the industry. This paper analyzes the root causes of corrosion of atmospheric column top system, systematically expounds the comprehensive design technology of corrosion control from multiple angles such as material design, process anti-corrosion, on-line desalination, corrosion monitoring and detection, and puts forward effective anti-corrosion strategies which can ensure the stable operation of atmospheric and vacuum distillation unit effectively.

Axial compressor is the core equipment of catalytic cracking unit. From June to August 2020, the blade fracture accidents occurred in three axial compressors of certain company, resulting in shutdown, which had a great impact on production. Through analysis, it is found that the main reason for the blade fracture is that the compressor deviated from the design operating conditions or there was stress concentration of the blade itself. Micro-cracks occurred during long-term operation, and the cracks continued to expand and eventually led to fatigue fracture. After that, the blade detection was strengthened, and the cracked blades were replaced preventively, which has improved the operation reliability of the compressors and achieved good results.

Post-weld residual stress is caused by uneven temperature distribution of weldments during welding and weld metal's expanding with heat and contracting with cold, so residual stress is inevitable during welding. The purpose of post-weld heat treatment is to eliminate the post-weld residual stress in the welded joints. The tensile strength, yield strength and toughness of welded joints are related to the temperature and insulation time of post-weld heat treatment. Taking the chromiummolybdenum heat-resistant A335-P11 steel as an example, this paper tests three different post-weld heat treatment times (675 ℃×3 h, 675 ℃×4.6 h, 675 ℃×7 h) of welded joints made of this material. It analyzes the effects of different post-weld heat treatment insulation time on the performance of welded joints. The analysis results indicate that extending the insulation time of the post-weld heat treatment has little effect on the performance of the welded joints.

To ensure even mixing of the medium in wax solution tank, mechanical agitation was transformed into rotary jet mixing to solve the problems of mechanical agitation and improve the stirring effect. This paper introduces the principles and structures of mechanical agitation and jet mixing, and makes a comparative analysis of them. The results indicate that jet mixer can achieve all-round and full-coverage stirring and mixing with higher mixing efficiency and better mixing effect. Compared with mechanical agitation, jet mixing can avoid such problems as seal leakage, reducer damage and motor failure, reduce safety and environmental protection risks and maintenance costs and realize energy saving and consumption reduction of the equipment. This can ensure the continuous and smooth operation of lubricating oil device effectively. Through practical application, it is proved that jet mixing can meet the requirements for use.