When 690 V voltage systems are driven by variable frequency drives, the unit shutdown caused by insulation breakdown of cables, electromagnetic interference and low frequency resonance of motors are analyzed. The insulation breakdown of cables can be solved by controlling system voltage or improving cable insulation. Low frequency resonance can be eliminated by changing the natural frequency of pumps or utilizing variable frequency motors. Electromagnetic interference can be prevented by using shielded cables with the shielding layer grounded at both ends. The short circuit breaking capacity of switches decreases in the 690 V voltage systems, and the decline in that of molded case switches is greater, while the fuses have extremely high short circuit breaking capacity. When the variable frequency drives match with the motor capacity, maximum load current is determined and the rated power of motors can be used for reference. Self-ventilated air cooling should be selected for the variable frequency motor of blowers and pumps.

B-type sleeve repair is a common repair method for long-distance oil and gas pipelines. Traditional B-type sleeve manual welding has many problems such as high labor intensity, high welding difficulty and low efficiency. This paper proposes a B-type sleeve automatic welding device based on laser tracking system. With the help of laser vision sensing technology, the automatic welding device uses laser vision sensor to collect the image information of welding process, extract weld position parameters, and track and control the welding process, so as to realize the automatic welding of B-Type sleeve. The welding test and the comparison with manual welding show that the B-type sleeve automatic welding device has the advantages of high welding efficiency, reliable weld bead quality and good appearance forming.

Low temperature multi-effect distillation with thermal vapor compressor (TVC-MED) is one of the most widely used thermal seawater desalination technologies. Its performance is affected by many factors such as TVC, evaporator and regenerator. In this paper, the process system model of 15-effect TVC-MED seawater desalination plant is established, and the effect of seawater feeding mode, excess heat recycle of concentrated brine and produced water, TVC extraction position and power steam conditions on the performance of seawater desalinization plant are analysed, which provides a theoretical basis for the subsequent process system design.

Vertical thermosiphon reboiler is important equipment widely used in chemical production to realize liquid vaporization. It has various structure parameters, and there are many factors to be considered in design. Taking a methanol recovery project as an example, this paper uses Aspen EDR to design and check two vertical thermosiphon reboilers satisfying the operation requirements while taking the vaporization rate, static pressure head, fouling thermal resistance and pressure drop of inlet and outlet pipelines of the reboiler into consideration. The results show that the design parameters of the two heat exchangers are within the recommended range or with little difference, so the design is reasonable. The design idea of this paper can provide reference for the design of other vertical thermosiphon reboilers.

The effects of earthquake action and wind load need to be considered in the design of reinforced concrete chimney. Whether the high self-supporting elevator steel structure matched with the chimney can safely stand still mainly depends on how to reasonably deal with various adverse working conditions controlled by wind load. In this paper, the finite element analysis software SAP2000 is used to analyze and simulate the load condition and deformation of self-supporting chimney, elevator steel structure and the composite structure that connects the two with connecting bar under wind load and earthquake action, and some suggestions are given through the comparison of relevant indexes.

Flare system is used to deal with the flammable gas discharged in refinery and chemical plant in accidents and the flammable gas leaked by equipment such as control valve or safety valve, so it plays a vital role in ensuring the safe production of units. At present, elevated flare is the most commonly used flare system. If the air enters the flare pipe network from the flare head and mixes with the flammable gas existing in the pipe network, explosive gas mixture will be formed, easily leading to backfire explosion accident when it meets with the ignition source. Flare system is the last defense for security of petrochemical enterprises, and its anti-backfire design, as a crucial link in the process design of flare system, will play an important role in the safe and stable operation of flare system as well as the energy saving and consumption reduction.

Electronic wiring technology uses electronic circuits to eliminate or replace physical wiring, that is, to eliminate the physical wiring of field instrument signals from field junction box to intermediate junction cabinet and then to I / O cards, and realize one-time conversion on electronic characteristic terminals to reduce corresponding cable connections. The advantages of electronic wiring technology include eliminating the wiring, shortening the progress and reducing the risks, flexibly handling late changes, and receiving active alarm. The engineering design of electronic wiring includes network design, protection and explosion-proof, hazardous area design, power supply, grounding and lightning protection. Combined with practical application in projects, this paper discusses the above contents in detail, which is helpful for engineers and technicians to understand and apply this technology.

The coding rules of material coding system in petrochemical industry are briefly introduced. Taking a joint venture project as an example, this paper discusses the application of non-standard material coding in engineering project based on the requirements of the joint venture project for material coding, and explains and analyzes the actual problems. From the point of view of material control and management, this paper focuses on the three aspects of manual identification, BOM module and SITE module of Marian system, and gives valuable feasible solutions and specific practical operation, providing reference for the future material control and management.

The steam produced by boiler fuel combustion has a very important role in industrial thermal power plants. Predicting the amount of steam produced according to the working conditions of boiler is conducive to the real-time monitoring of boiler combustion efficiency. Useful features of the boiler data are extracted by preprocessing and feature engineering, a variety of machine learning algorithm models are constructed for the extracted features, and the multiple models are merged. The results show that the fused model of multiple machine learning algorithms is superior to the single model in accuracy, and the root mean square error of steam predicted by the fused model is 0.106, providing important reference for the real-time industrial monitoring of boiler combustion efficiency.

Multi-effect evaporation is a commonly used energy-saving process in industrial production. However, in actual engineering design, few people have proposed the exact design method for the effective heat transfer temperature difference distribution of each effect. In practice, the temperature difference of each effect is generally realized through self balance. Accordingly, the operation controllability in production is poor, and problems such as pressure fluctuation, liquid flooding or mist entrainment are easy to occur. This paper takes the problems occurred during the start-up of an ethylene oxide plant as an example, analyzes the reasons and effect of the operating pressure deviation from design value from two aspects of process design and control operation, gives solutions to the problems and optimizes the design, greatly improving the operation stability of the plant.

Vertical thermosyphon reboiler is a kind of heat exchanger installed at the bottom of distillation tower to vaporize the bottom products. Due to the limitation of thermosyphon on pressure loss, thermosyphon reboiler is usually directly connected to the tower or with the shortest connection. The difference of material and temperature between reboiler and tower will lead to different thermal expansion, which will affect the thermal stress of equipment and the external load of nozzle. Taking a chemical plant as an example, the stress of thermosyphon reboiler and distillation column as well as the support and nozzle load were simulated and analyzed by CAESARII software, and the design modification scheme was proposed according to the analysis results.

Spent acid treatment unit is featured by large pipe diameter, high temperature and extremely low allowable stress on equipment nozzle. With the compact layout of the unit, it is unable to absorb the thermal expansion displacement of the pipeline through natural compensation, so expansion joints need to be installed in the pipeline system to reduce the pipeline stress. This article introduces the relevant standards and applications of expansion joints, and lists the common types of expansion joints and the types of absorption displacement. Taking the typical pipeline system in the unit as an example, this article compares the design schemes of expansion joints. It is concluded that the use of single gimbal hinged expansion joint in pairs is superior to the use of double tied expansion joint in reducing the equipment nozzle stress. The calculation of blind plate force and the design of expansion joint piping support are discussed.

Under the background of global economic integration, the domestic market is limited. To achieve long-term development, state-owned enterprises must go abroad and compete with world-class enterprises on the same stage. To be a world-class company, the extensive management methods left over from the farming society must be changed. Taking procurement as the starting point, this article analyzes the normal practice and problems in the procurement activities of state-owned enterprises, and puts forward the concept of lean procurement, which aims to improve the quality and efficiency and promote the development of state-owned enterprise procurement activities.

This paper sorts out the characteristics of labor outsourcing in accordance with relevant local laws and judicial cases, and by comparing the distinguishing features of labor outsourcing and labor dispatch, finds out that the keys to make a distinction between labor outsourcing contract and labor dispatch contract lie in the subject matter of contract, the settlement method and the ownership of direct management right. By analyzing a typical case of labor outsourcing, it is concluded that clear contractual stipulation and thorough management mechanism can effectively cut down the risk and improve the quality of labor outsourcing. Starting with the necessity of labor outsourcing, this paper suggests that the legislature or government departments should issue relevant laws and/or regulations to make systematic provisions on non-typical labor relations.

With the coming of the age of carbon neutrality, the new green industry dominated by hydrogen energy has increasingly become the mainstream. China has vigorously supported and promoted the construction of hydrogen station. Facing the demands of building hydrogen stations in multiple regions at the same time, it is particularly important to explore a multi-project management mode suitable for hydrogen station projects. Based on the theory of multi-project management and combined with the practical experience in hydrogen station projects, this paper points out the main problems in the construction of hydrogen station. By optimizing resource allocation, adopting standardized design and modular procurement and improving construction quality management, high efficiency collaborative management of the project group can be achieved, providing references for the management of hydrogen station projects in the future.