The by-product waste acid from sulfuric acid alkylation unit has a complex composition and strong corrosiveness, making its efficient regeneration crucial for reducing environmental treatment burdens and enabling sulfur resource recycling. Waste acid cracking and regeneration technologies have developed into two main routes, i.e., dry process and wet process, and are gradually evolving toward multi-unit coupling and integrated treatment of various sulfur-containing materials. The dry process can stably produce concentrated sulfuric acid with a mass fraction above 98%, but suffers from long process flow, high investment and energy consumption, and wastewater generation. In contrast, the wet process features compact process flow, efficient waste heat recovery, and zero wastewater discharge; however, it faces challenges such as insufficient removal of fine particulates, system clogging, and fluctuating product acid concentration. Therefore, balancing the stable production of high-concentration sulfuric acid with the low energy consumption and low emissions of the unit has become the core challenge in upgrading waste acid regeneration technology. To address these issues, this paper focuses on reviewing two new technologies, i.e., dry-wet coupling process and hydrogen sulfide - waste acid cracking and regeneration combined process. The former integrates dynamic wave scrubbing, coalescing demisting, steam reheating, and dry air condensation to achieve synergistic process gas purification, moisture control, and energy utilization. The latter enables coordinated treatment of waste acid and sulfur-containing materials such as hydrogen sulfide through acid gas heating, merging of two furnace gas streams, and sharing conversion-absorption system. Engineering operation results show that the dry-wet coupling process achieves an overall dust removal efficiency of up to 99.9%, produces sulfuric acid with a mass fraction exceeding 98%, and improves waste heat recovery efficiency by over 20%. The hydrogen sulfide - waste acid cracking and regeneration combined unit can be operated stably within a wide load range, and the waste acid treatment capacity and operation flexibility can be improved by adopting acid gas heating and sharing conversion-absorption system. This paper further compares the applicable scenarios, technical bottlenecks, and engineering performance of different technical routes, providing theoretical basis and engineering reference for selecting waste acid regeneration schemes, retrofitting existing units, and promoting the integrated utilization of multiple sulfur-containing materials.

 This paper lists the calculation formulas for crack width of concrete water tanks in Chinese standards GB/T 50010-2010 Code for Design of Concrete Structures, GB 50069-2002 Structural Design Code for Special Structures of Water Supply and Waste Water Engineering, American standard ACI 224R-01, and Saudi Arabian code SBC 304-AR/CR-2018, respectively. A comparative analysis of the differences in parameter values adopted by various national standards in calculating crack width is conducted, and the crack width limits under different environmental categories and exposure conditions are presented. Taking a project in Saudi Arabia as the example, this paper compares the strictness of these national standards in crack width calculation, and summarizes the crack control strategies and implementation key points of these countries from the perspectives of material selection and construction technology, aiming to provide reliable technical reference for the structural design of pool structures, the refined management and control of cracks, and the collaborative verification of multiple national standards in overseas engineering projects.

This paper systematically explores the principles and practical strategies for the planning and design of front plant area in petrochemical projects. Unlike the design of urban technology parks that emphasize visual impact, the design of front plant area in petrochemical projects primarily adheres to the core industrial design logic of "form follows function", aiming to create a simple, practical, efficient, and harmonious architectural image and spatial environment while meeting core functional requirements. Drawing on engineering experience, this paper focuses on key aspects such as overall layout, functional organization, traffic flow, safety measures, and landscape design in the front plant area. The goal is to develop a set of planning and design methods suitable for this specific type of area, providing reference for the optimized design of similar projects.

Hydrogen is an indispensable feedstock for petrochemical production. To recover hydrogen from CO-containing desorption gas and enhance the plant-wide hydrogen utilization efficiency, the process flow of the existing pressure swing adsorption (PSA) unit for CH₄ impurity removal was to be optimized. Based on the fundamental PSA theory and the current operational data, the unit's CO adsorption capacity was calculated, and the theoretical calculation formula for the adsorption time of the modified unit was derived. The results technically demonstrated the unit's capability to process CO-containing gas sources. An analysis of the additional costs and economic benefits after the modification shows that the modified unit could recover 17.9 million kg of hydrogen annually, generating a direct economic benefit of 40.9147 million yuan for the enterprise. The results demonstrate that this modification scheme is technically and economically feasible. It provides a reliable optimization approach for refining and petrochemical enterprises to maximize hydrogen resource utilization during initial operation stages, which is conducive to the green and low-carbon development of enterprises.

When designing and calculating the insulation layer thickness of petrochemical equipment and pipelines, the outer diameter of a cylindrical insulation layer can only be simplified to the implicit function form of D1·ln (D1/D0). However, the methods of solving for the outer diameter D1 of insulation layer by looking up charts or manually testing are time-consuming and laborious and has poor accuracy. Based on four mathematical methods including value-added root seeking method, bisection method, Monte Carlo method and Newton iteration method, the thickness of insulation layer can be accurately and efficiently solved combined with the VBA program or combination of new functions in Excel. In addition, the characteristics of iteration times and convergence speed of the four mathematical methods are compared, the selection table for double-layer insulation thickness is calculated by using Monte Carlo method. This provides excellent computational support for the thickness design of insulation layer of petrochemical equipment and pipelines.

For the extremely complex working conditions in VOCs transportation in subsea pipelines of a project, such as gas-liquid multiphase flow, acid corrosion (H?S 1400 ppmv), and large fluctuations in flow rate (10.35 to 111.32 t/h), this study proposes a coupled optimization approach that integrates flow assurance simulation with comprehensive economic study. Based on the multiphase flow simulation using a professional simulation software, a collaborative analysis on the flow assurance performance and economic feasibility of VOCs transportation in multiphase flow subsea pipelines is carried out incorporating third-order flow velocity constraint criteria (gas-phase flow velocity ≤ 18.3 m/s, inner wall shear stress ≤ 120 Pa, and erosional velocity ratio EVR < 1.0) and the minimum pressure requirements for pigging (≥ 1.0 MPaG). The results indicate that the combined scheme with a compressor outlet pressure of 1.0 MPaG and a DN500 pipeline offers the most cost-effective solution while satisfying the process and pigging requirements under acidic service conditions. This study provides theoretical support and engineering insights for the systematic optimization of subsea pipelines for VOCs with condensation phase change.

 This paper introduces the technical features of the 400 kt/a aromatics extraction unit of a company, and analyzes its technical optimization potential. By adding the process of producing C₈/C₉ mixed aromatics and the process of producing C₇/C₈/C₉ mixed aromatics, the processing cost of the unit can be reduced by 1.3182 million yuan and 12.0864 million yuan per year respectively, thus greatly improving the operational flexibility of the unit and enabling the company to choose appropriate production mode according to market demands or the principle of maximizing economic benefits. Two energy saving measures were implemented, including optimizing the steam consumption structure of the unit and recovering low-temperature heat from the raffinate extraction tower. Under the main design conditions for producing three benzene products, the processing cost can be reduced by about 3 million yuan per year. Two suggestions for further work were put forward, including recovering low-temperature heat from the unit's process condensate and optimizing the steam consumption structure of aromatics extraction unit in the refinery area. This research provides guidance and reference for similar units in refining and petrochemical integration enterprises.

This paper studies the condensation system of propylene recovery column in a propylene oxide unit, compares two process design schemes, and explores the feasibility of energy-saving optimization paths for the system. Scheme I is a conventional process flow, consisting of an overhead condenser, a reflux drum, and a discharge pump. In light of the fact that the overhead stream is mainly composed of propylene and liquid propylene is required as the refrigerant, the optimized Scheme II is proposed, which involves installing a compressor at the top of the propylene recovery column. This scheme increases the dew point temperature through compression, allows the overhead condenser to use circulating water for cooling, and installs a reflux drum and a discharge pump to complete the subsequent material conveying. A detailed comparative calculation of the two schemes was conducted using ASPEN simulation software. The simulation results indicate that Scheme II can significantly reduce the load of refrigerant system and effectively reduce the comprehensive energy consumption of the unit. It is concluded that Scheme II offers significant energy-saving benefits, providing a valuable reference for the modification of condensation systems in similar units.

An offshore FPSO project carries out separation, purification and liquefaction processes for natural gas extracted from offshore sources, so as to produce, store and transport liquefied petroleum gas (LPG) outward. The FPSO uses ship loading pumps for loading operations. After the loading is completed, the outgoing pipelines are purged using the overhead gas from LPG storage tanks. Once the purging is finished, the gaseous and liquid phase LPG in the system is promptly recovered. This paper examines the purging and recovery operation of an LPG vapor recovery compressor in the project, introduces the purging and recovery processes for the outgoing pipelines, and proposes some measures for ensuring the safe operation of the compressor. HYSYS simulations are performed to model the outlet temperature of the vaporizer and calculate the leakage rates under heat exchanger tube rupture scenarios, providing theoretical guidance for similar LPG loading operations.

Against the background of "dual carbon" goals, the operation and management of petrochemical enterprises is undergoing transformation and upgrading from "physical assets" to the dual-drive of "digital assets + physical assets”. Digital delivery has gradually become a standard configuration for large-scale projects such as integrated refining and chemical plants and LNG receiving terminals. However, there is still a lack of unified definition of the connotation scope, pricing base and pricing method of digital delivery cost, leading to frequent disputes during cost estimation, contract negotiation and payment. Based on a systematic review of the connotation and composition of digital delivery cost in the petrochemical industry, this paper compares two mainstream models taking the engineering cost and the basic design and detailed design fee as the pricing base, respectively. It demonstrates the rationality of using the basic design and detailed design fee as the pricing base, and proposes a dynamic rate model of "engineering design correlation coefficient + multi-dimensional characteristic coefficient + scenario adjustment coefficient", providing a reference for the quota revision in the petrochemical industry, the investment decision-making of enterprises, and the bidding and quotation of engineering companies.

 This paper introduces the current status of digital delivery for the telecommunications discipline in petrochemical projects. Taking AVEVA E3D as an example, it analyzes the existing problems in the application of the 3D model-centered digital delivery system in telecommunications engineering. Finally, the 3D modeling software AVEVA E3D and the database-driven design software EPLAN are respectively adopted to generate engineering drawings that meet the basic delivery requirements, laying a research foundation for the further development of digital delivery tools in the future.

During the execution of foreign-funded chemical EPC projects by domestic engineering companies, design quality has become one of the key factors determining the success or failure of projects. Many common problems have emerged in practices, e.g., the design deliverables fail to fully meet the contractual requirements, the process quality management for design documents is lacking, the discipline leads lack overall planning and management capabilities, inadequate attention is paid to 3D models and digital delivery, and the management and control of project meetings are not given due emphasis. To address these problems, this paper proposes some systematic solutions, including continuously deepening contract review to integrate the technical requirements into the whole design process to ensure the compliance of deliverables with contractual terms, prioritizing 3D modeling and multi-disciplinary collaboration to ensure the consistency between the 3D models and the on-site entities, conducting specialized research on key and difficult issues in project design through thematic discussions and expert evaluations, implementing a form-based mechanism for phased model reviews, and reforming traditional review methods by integrating professional reviews, information-based inspections and whole process quality supervision to optimize the whole process management. This paper aims to provide practical guidance for improving design quality management in foreign-funded chemical EPC projects and help domestic engineering companies enhance their international market competitiveness.

 With the increasing complexity and informatization level of enterprise personnel management, higher requirements have been put forward for employee attendance management. Traditional attendance management mostly rely on manual labor and cannot timely grasp the attendance situation of employees. Data such as leave and business trip records cannot be linked with attendance in real time, resulting in more information silos. It is difficult to support efficient personnel management. Based on BEX5 platform, this article designs and implements an intelligent, automated and integrated enterprise attendance management system. The system realizes full process management of leave application and approval, establishes an intelligent rule engine for complex office scenarios in multiple locations, provides one click attendance confirmation management, and automatically forms multi-dimensional comprehensive statistical report on employee attendance. This system can effectively reduce human error rates, provide guarantees for improving enterprise management efficiency and better leveraging personnel value, and help enterprises promote digital transformation.