Shell and tube heat exchangers are mostly of single tubesheet structure, and both sides of tubesheet contact with the medium respectively. Once the connection between the tubesheet and the tubes fails, the medium will leak. An isolation cavity is set between the inner and outer tubesheets in the double tubesheets heat exchanger, which can effectively solve such problems. This paper deals with the analysis of many key points with engineering design examples, such as occasions of double tubesheets application, calculation of inner and outer tubesheets thickness, factors for determining the length of the isolation cavity, and tubesheets manufacturing, connection between tubesheets and heat exchange tubes, pressure test, etc. The paper also provides optimization and improvement measures to better the design and manufacturing quality.

The Eulerian-Lagrangian two-fluid model was used to study the fluidization characteristics of the turbulent bed by numerical simulation. The pressure, solid holdup, particle velocity and particle size distribution of the bed were studied. The results show that the central pressure gradually decreases along the axial height, while the solid holdup gradually decreases along the axial elevation, showing a “ε”-type distribution. Accordingly, the bed is divided into a bottom dense phase zone, a middle transition zone, and a top dilute phase zone. In the dilute phase region, the core-annular-structure gradually decreases along axial direction until it disappears. Besides, the axial velocity of the particles fluctuates in the radial direction, which in the central zone is generally greater than that at the wall, and the position where the particles falling moves from side wall to the center. The average particle size gradually decreases along the axial axis, and the particle diameter distribution of the dilute phase zone is relatively uniform.

This paper used Pro/E software to perform 3D modeling of the structure and fluid model of the SWX static mixer. Based on the FLUENT module of ANSYS Workbench, the paper made research and analysis. Numerical simulations of flow field, velocity field, pressure field and heat transfer characteristics were carried out to study the fluid flow characteristics and mixing mechanism in static mixers. The results show that due to the existence of the mixing unit, when the fluid flows in the axial direction, the velocity differentiation of uniform fluids occurs. The maximum axial velocity of the fluid is about 1.3 times that of the radial velocity and 1.7 times that of the circumferential velocity. It shows that the fluid is blocked by the mixing unit to produce radial and circumferential movement, which causes the fluid to continue to be dispersed, divided and reorganized. The fluid has basically reached a steady state after passing through the third and fourth mixing units and the segmentation of the velocity region is also relatively stable. In addition, the level of fluid flow and the number of mixing unit groups affect the pressure drop in the mixerdirectly; finally, the comparative analysis confirmed that the static mixer has strong heat transfer characteristics. These provide a reference basis for the application, design and installation of the SWX static mixer.

In recent years, as petrochemical enterprises have further shortened the construction period of petrochemical projects, construction units must continue to innovate construction processes under the premise of ensuring quality and safety to improve construction efficiency, reduce construction costs and increase market competitiveness of enterprisesin order to meet the requirements ofbusiness environment and seek better development. Taking a petrochemical company's onsite assembly welding and installation of isopentane tower in 200kt/a isomerization unit as an example, this paper makes a comparative analysis from the aspects of construction organization and cost covering process flow, site use, supporting material input and workload, construction machinery and labor input and construction period, safety and quality assurance and so forth. This is done to explore safe, economical, and efficient construction processes suitable for the characteristics of the project, which can provide reference for the construction of similar projects.

Delayed coking units are important units for refineries to choose inferior raw materials in order to reduce the processing cost of raw materials. Coke cooling overflow and blowout water storage tank (D2403) is one of the keyatmospheric storage tanks in the unit. Theconstruction quality of the storage tank is directly related to its service life. Based on the specific installation engineering practice of D2403, this paper analyzes and studies the related technologies for installation construction of steel vertical storage tanks. It also studies the method and steps for installation construction and related processes principles. These provide reference for further improvement of the construction quality of storage tanks. Meanwhile, these have certain reference significance for the safe use of storage tanks.

This paper compared the toxicity upgrading of commonly used medium and analyzes the reasons for the upgrade. It pointed out the difficulties and problems caused by the toxicity upgrading, and gave suggestions on revision of relevant standards and regulations.

Theemulsification research results of the Claus fan lube oil show that there are two main reasons for the emulsification of KG301 lube oil: one is that the sealing gasket of the lube oil tank is gradually aging, so the water phase of the heat exchanger enters the oil tank, which results in the emulsification of the lube oil in the water; the second reason is the degradation of the lube oil after long-term use. Aiming at the aging problem of the sealing gaskets, new gaskets have been developed and the aged ones have been replaced. Two countermeasures have been taken to deal with the problem of lube oil degradation: one is to add new lube oil regularly; the other is to develop cheap and high-quality lube oil and prepare for practical application tests. Meanwhile, the chemical composition of in-service lube oil is analyzed continuously and regularly to ensure the sealing performance of the lube oil system. The emulsification problem of Claus fan lube oil was solved successfully, and the purpose of reducing costs and increasing efficiency was achieved.

Methanol to olefins (MTO) process is the bottleneck connecting the upstream and downstream processes of coal to olefins, and methanol superheater is a very critical heat exchange device in MTO process. Aiming at the abnormal noise and leakage of the U-shaped tube bundle methanol superheater in the SHMTO process, this paper analyzes the causes of abnormal noise from the vibration spectrum, and analyzes the causes of leakage from the corrosion of the tube bundle.It is concluded that the reasonfor theabnormal noise caused by vibration is the unreasonable design of the heat exchanger structure, and the reason for the leakage is the corrosion of carbon steel caused by impurities in the crude methanol, especially at higher temperatures. Aiming at the above reasons, the heat exchanger was revamped and the high-temperature heat exchange medium was replaced. The revamped methanol superheater has been running continuously at full load for more than 12 months, and it is operating in good condition without any abnormal noise caused by vibration or leakage.

As a new type of heat exchanger with high heat transfer coefficient, the spiral wound heat exchanger has been widely used in industrial fields in recent years.The article introduces the application of the spiral wound heat exchanger in pyrolysis gasoline hydrogenation plant of a Refining and Chemical Company, and analyzes the advantages and disadvantages during the operation. After being put into production, the plant has further realized energy conservation and environmental protection, making the second-stage hydrogenation reaction process more simple and convenient.the plant can save 1.89 million yuan in operating costs every year, and the economic benefits are significant.

To solve the dispute of corrosion mechanism of stainless steel in high sulfur environment of desulfurization unit in natural gas purification plant, and the problem that there is no unified standard to provide a basis for corrosion monitoring in engineering application, this paper investigates the corrosion status of stainless steel in desulfurization unit. Meanwhile,it analyzes the distribution of stainless steel in desulfurization unit and the corrosion influencing factors in sulfur environment, and makes a comparison based on the results of field corrosion investigation of desulfurization unit. And then the paper infers the potential corrosion mechanism of stainless steel material. According to the corrosion mechanism, it puts forward the appropriate process control measures and inspection and detection strategies. The corrosion hazard caused by point corrosion and chloride stress corrosion cracking has brought severe test to the long-term operation of the unit. Effective management and control of the corrosion status of stainless steel through optimized design and material selection, process medium control and effective inspection strategies can ensure the safe and stable operation of the desulfurization unit in high sulfur environment.

This paperanalyzed the causesfor the biomass leakage in the second section of preheating pipeline in convection section of pyrolysis furnace instandby process. It highlighted the corrosion mechanism of the feed elbow in the second section outlet pipeline of preheating convection section of pyrolysis furnace under the conditions of operation, coke burning and standby. The process operation scheme was optimized. The paper also proposed the measures for continuous feeding of dilution steam into the outlet pipeline of the second section of feeding preheating when the pyrolysis furnace is in the states of standby and coke burning.

The abnormal wall thickness of a liquid ammonia tank was detected and analyzed by means of TFM and EMAT in this paper during the periodic inspection. At first, the characteristics of the two detection techniques, the status of inspection and detection are introduced. Then, EMAT is used to quickly identify the abnormal thickness area, and the cause of abnormal wall thickness is preliminarily determined. Furthermore, TFM is used to accurately detect the specific distribution, echo size and morphology of defects. Finally, according to the detection results, the author determines that the defect is a non-metallic inclusion in the steel plate forming intermittent band structure during rolling. Through the detection and analysis of the banded structure of the base metal described in this paper, it is helpful for the engineers to diagnose the difficult defects in the actual inspection.

The lean amine liquid pump in a unit is a highspeed pump, and the large amount of foaming oil in the oil tank leads to the continuous decrease of oil pressure during the operation of the equipment, causing great hidden dangers to the safe operation of the equipment, the oil pressure drop was not improved before the foaming condition was eliminated, and the oil pressure returned to normal after the foam was eliminated, judge the reason of oil pressure drop is that the foam produced in the lubricating oil is too much and is not easy to burst. Through the analysis of the relationship between temperature, oxidation, pH value and foaming tendency, foam stability, the harm of oil pressure drop caused by foaming was solved, and the improvement measures for operation and maintenance were put forward.

When the equipment needs thermal insulation for a long time or/and postwelding heat treatment (PWHT) at higher heating temperature, the actual properties of skirt material will be reduced if the skirt cylinder needs PWHT with the equipment. Through analysis, it is considered that when the tempering parameter P is large, the skirt material should be subjected to simulated PWHT or the test sample to verify that the actual properties of skirt material can meet the properties. Local PWHT can also be considered to reduce thermal insulation time.In the case where all the axial stresses of the skirt cylinder are all compressive stresses, the possibility of using the lower heating temperature system used in the intermediate stress relief heat treatment for local postweld heat treatment can be considered if necessary.