In order to discuss the structure, function and manufacturing key technology of gas distributor in fluidized bed reactor, this paper reviewed the basic structure and special characteristics of the distributor of hydrogenation reactor, refinery reactor and olefin polymerization reactor. Based on the review, it expatiates on the structure and manufacturing technology of three kinds of distributor commonly used in olefin polymerization reactors covering the circular flat hood distributor, the funnel-shaped combination distributor and the conical integral distributor. The structure and manufacturing technology includes the main structural features, design methods, precision forming of parts, assembly inspection and precision control of supporting and connecting structures. This can provide reference for the design and manufacture of reactor gas distributors.

As a solid-liquid separation equipment, the washing section of the rotary pressure filter directly affects product purity and production energy consumption, making it a critical link that constrains the efficient and low-energy operation of the equipment. Conventional washing section design overlooks the differences in cake washing efficiency among individual washing zones, resulting in low washing efficiency, high washing liquor consumption and uneven product quality. This problem is particularly prominent in large-scale plants such as purified terephthalic acid (PTA) plants. Considering the continuous operation characteristics of the rotary pressure filter, this paper systematically establishes a mathematical model of the washing process. A washing zone theory based on the rotary drum's rotational characteristics is proposed. Furthermore, an engineering optimization method for washing zones is constructed, which integrates multiple factors including process parameters, equipment configuration and operating conditions. This study can provide theoretical basis and technical reference for the design and operation optimization of washing sections in similar equipment.

Cross-wavy channel (CW-type) flow geometry optimization in plain surface heat exchangers plays a critical role in enhancing heat transfer performance while reducing flow resistance. However, traditional design methods struggle to comprehensively account for the integrated effects of high-dimensional structural and operational parameters; therefore, there is an urgent need to develop a novel optimization methodology. A comprehensive database was constructed, integrating the influences of structural and operational parameters, and a high-precision, cross-validation Gaussian surrogate model was developed to enable optimization design via a multi-objective optimization genetic algorithm. The method can effectively identify channel geometries and operational parameters featuring high heat transfer coefficients and low friction coefficients, providing a critical theoretical basis for the design and operation of CW-type plain surface heat exchangers.

This paper conducts a study on the inconsistent practices and overly conservative assessment results associated with the "algebraic sum of three principal stresses" criterion which is commonly adopted in domestic engineering design and based on elastic stress analysis. Taking the structure of an inclined nozzle on a pressure vessel cylindrical shell as a case study, elastic and elasticplastic analysis were carried out respectively with a comparative analysis of the evaluation results. The results show that the evaluation based on the "algebraic sum of the three principal stresses" of the total stress from elastic analysis exceeds the limit value by 22.5%, rendering the structure unqualified; but the evaluation by elastic-plastic analysis obtain a qualified result with a safety margin of approximately 85% remaining. It is demonstrated that the evaluation of this structure using the "algebraic sum of the three principal stresses" of the total stress based on elastic stress analysis leads to an overconservative design. Therefore, it is recommended to prioritize the adoption of elastic-plastic analysis methods and criteria for localized strain failure assessment in special complex structures, thereby achieving more rational and optimized design.

The fluid catalytic cracking (FCC) unit is a core unit in petrochemical production. The stable operation of its reactor-regenerator (R-R) system directly determines the overall production efficiency and economic benefits of the entire unit. During operation, the reactor-regenerator system utilizes cyclone separators to achieve efficient separation of the catalyst from the process gas, thereby preserving catalyst activity and maintaining the pressure balance across the R-R system. As the key equipment in this process, the long-term operation capability of cyclone separators significantly affects the stability and efficiency of the FCC unit. In actual operation, cyclone separators often experience a reduction in separation efficiency due to issues such as equipment wear, blockage, deformation and failure, which lead to a decline in separation efficiency and consequently constrain the long-term safe operation of the unit. To address these issues, this paper systematically analyzes the major bottlenecks encountered during the long-term operation of cyclone separators, and proposes targeted optimization and improvement measures. The aim is to provide theoretical reference and practical guidance for enhancing the operational performance of the reactor-regenerator system in fluid catalytic cracking units.

The circulating screw compressor in the C₄ full hydrogenation unit plays a vital role in the reliable operation of the unit. It can effectively improve the material utilization efficiency and reduce the losses of C₄ components and hydrogen in the purge gas. The compressor may shut down due to faults existing in the oil circuit system, liquid injection system, instrument system or sealing system. This paper analyzes the causes of the compressor failure, puts forward corresponding countermeasures, and thoroughly investigates the impacts of different switching conditions on material loss and product quality after shutdown. The conclusions are drawn as follows: both the scheme of interrupting hydrogen make-up by the circulating compressor and the scheme of interrupting hydrogen make-up while halting the recovery of the first-stage purge gas will markedly raise hydrogen consumption and purge gas loss. Although recovering the first-stage hydrogenation purge gas by lowering operating pressure can reduce material consumption to a certain extent, the mitigation effect is limited and the improvement is insignificant. All the above schemes can maintain the stable operation of the unit. During design, the operational requirement of controlling the switching time within 0.5 hours should be considered to ensure that the second-stage full hydrogenation system can maintain normal circulation while ensuring product quality unaffected.

The tenon tooth structure of the moving blades in a newly designed flue gas expander fails to meet the strength margin requirements. To further investigate the stress characteristics of the flue gas expander tenon teeth and optimize the structural design, this paper systematically analyzes the specific effects of factors such as tenon tooth axial width, rotational speed, tenon tooth geometric parameters and aerodynamic forces on the strength of the tenon tooth region based on the stress distribution of the rotor blade tenon teeth of the flue gas expander under actual operating conditions as calculated by ANSYS software. Particular attention is paid to investigate the stress concentration phenomenon in the tenon tooth region. The results show that reducing the rotational speed, increasing the tooth tip inclination angle β and increasing the tenon tooth fillet radius R can significantly reduce the maximum concentrated stress in the tenon tooth, while the tenon tooth axial width L and the tooth base inclination angle γ have no significant effect on the maximum concentrated stress. Optimizing the load-bearing state of the tenon teeth by considering maximum concentrated stress as well as four stress indicators including tensile, bending, compressive and shear stress can provide technical support for reliability analysis in the design of rotor blades for flue gas expander.

This paper investigates the dynamic characteristics of tilting-pad bearings and their influencing factors, aiming to eliminate unstable vibration during the operation of the material suction fan in vertical milling and boring equipment. A solving method based on linear superposition of pad performance is adopted to analyze pressure distribution features, dynamic characteristic coefficients and frequency responses under two lubrication models of starved lubrication and flooded lubrication. The results show that with the increase of load, the stiffness coefficients of the tilting-pad bearing rise and the damping effect is enhanced, while the vibration absorption capacity of the system declines, making the bearing system prone to severe vibration response. Under the starved lubrication model and reduced oil supply conditions, both the stiffness and damping coefficients of the bearing decrease with rising rotational speed, resulting in poor dynamic performance. For the starved lubrication model, the damping ratio first rises and then falls as the rotational speed increases, and gradually stabilizes after reaching a certain rotational speed. The findings provide a theoretical basis for vibration response analysis, optimal design and fault diagnosis of tilting-pad bearings and material suction fans.

Based on the Reliability-Centered Maintenance (RCM) methodology, fault mode analysis and risk level evaluation of key components are carried out on the basis of structural information, monitoring data and historical fault records of reciprocating acid gas compressors. Maintenance strategies are proposed in accordance with the assessment results to reduce failure frequency and cut maintenance costs. For major failures such as valve damage, joint detachment and hydrogen sulfide leakage, risk levels are determined from four dimensions covering economy, environment, safety and maintenance. Among these, failures of the sealing gaskets, discharge valves and suction valves are rated as medium risk, for which a periodic replacement maintenance strategy is recommended. All other components are classified as low risk, and an operational strategy combining routine maintenance with vibration condition monitoring is proposed. Meanwhile, corresponding inspection and maintenance strategies are formulated based on the risk reduction principle and logical decision analysis method. This assessment method enables a comprehensive trade-off among the compressor's economic performance, environmental protection, safety level and maintainability, thereby achieving optimal overall performance. It provides an important reference for developing cost-effective maintenance strategies.

Aiming at the issues encountered during the operation of the SL-Ⅱ ethylene cracking furnace (F-02102) of a petrochemical company, including aging of radiant section tube, short operation cycles, low feed load and inferior thermal efficiency, the CBL (China Northern Furnace) gas cracking technology was adopted to carry out the retrofit. The core of the retrofit was to replace the radiant section furnace tubes with 2-1-1-1 type four-pass configuration, optimize and adjust the convection section tube bundles, and support the upgrade of relevant auxiliary systems. After the retrofit, the cracking furnace can flexibly process a variety of feedstocks including ethane-rich gas, liquefied petroleum gas (LPG) and light naphtha. Its operation cycle is greatly extended from less than 70 days to 90~100 days, the feed load is increased to 110% of the original design capacity, the flue gas outlet temperature drops remarkably, and the thermal efficiency rises above 94%. All technical and economic indicators meet or exceed the retrofit targets, bringing favorable economic benefits to the enterprise.

Based on the characteristic analysis results and the concept of inherent safety, a hierarchical supervision route is systematically established for pressure vessels that have reached their design service life (over-limit vessels for short). The route consists of pre-assessment screening→safety assessment→alteration of usage registration→risk assessment→risk level assignment→classified supervision. Concurrently, four sufficient conditions for over-limit vessels to enter the safety assessment procedure are defined. For typical scenarios that may arise after safety assessment, this paper adopts the risk matrix method and establishes a risk assessment model for over-limit vessels, thereby achieving quantitative evaluation of risk levels under different operating conditions. And based on the assessment results, differentiated supervision strategies are proposed for over-limit vessels with distinct risk levels. The proposed supervision route and strategies can provide systematic references and practical foundations for safety supervision and risk management of over-limit pressure vessels.

The equipment integrity management system refers to the policies, strategies, objectives, plans and activities for enterprise equipment integrity management, as well as the procedures and organizational structures necessary for the planning, implementation, review and continual improvement of the aforesaid elements. This system has been widely applied in Sinopec's refining and petrochemical enterprises. Based on the summary and reflection of the system development and operational control practices, this paper systematically expounds the common problems encountered in each management elements, conducts an in-depth root-cause analysis of these problems, proposes corresponding solutions and response strategies and further offers recommendations for system establishment and effective operation. These can serve as a reference for improving the equipment integrity management system and ensuring its effective operation.

The 4M150 reciprocating compressor, as China's first domestically developed model with the maximum piston force (1,500 kN), has filled the technological gap in large-thrust reciprocating compressors in China. With the accumulation of installed units and operating hours, frequent detachment of the Babbitt metal layer on the main bearing bushes has occurred in multiple compressors, severely compromising the normal operation of the equipment. Through systematic analysis, it has been confirmed that coaxiality deviation in the bearing bore is the primary cause of localized overload and subsequent Babbitt alloy detachment. After adopting specially designed eccentric bearing bushes, the equipment has operated continuously for over 8,000 hours without recurrence of similar failures, verifying the effectiveness of the solution. According to incomplete statistics, similar problems have occurred in models like 4M125 since 2017 and were resolved using the same solution. However, as late as 2021, most failure cases still repeatedly went through the cycle of "analysisbearing replacementreoccurrence of failure" (averaging 2.3 bearing replacements per case), exposing gaps in the industry-wide knowledge transfer and sharing mechanism. This paper further discusses the fundamental causes of bearing bush failures and proposes improvement suggestions.