The calculation of baffles inside pressur evessels has long been neglected. Many designers determine the thickness of baffle plates and the parameters of baffle stiffeners only based on their personal experience. Sometimes, the baffles are damaged because of insufficient thickness of plates or low parameters of the stiffeners. This paper introduces the calculatio nmethod of baffles which are welded directly tothe shell of pressure vessels and presents the detailed calculation process through examples so as to help readers make better use of this calculation method in the baffle design process.

Large high-pressure vessels are often needed to be used as reaction or storage vessels in petrochemical and aerospace industries. Being restricted by the material thickness and inhomogeneity of mechanical properties in the direction of wall thickness of single-layer cylinder, the structure of multilayered weld-shrunk cylinder; single-layer spherical head with good stress and economic efficiency are generally adopted. According to the pitch diameter formula, the wall thickness of cylinder is approximately twice that of the spherical head. However, due to the structural discontinuity of the joint between the cylinder and the spherical head, there are stress concentration and edge stress. Therefore, the ratio of wall thickness and the connection form are worth discussing. This paper analyzes several types of local connection structures and compares their finite element analysis results. Then it presents the optimization path for the local structure, which provides reference for the design of similar vessels.

Taking the revamping of a 1.1 MTA ethylene plant as an example, this paper introduces the process technical characteristics of the quench oil tower system for ethylene separation. It discusses the revamping scheme for the internals of the quench oil tower emphatically. After the application of a new type of high-throughput orthogonal wave tray, the problem of large increase of gas-liquid load in the pan oil section of the quench oil tower is solved successfully. This provides reference for the selection of revamping schemes for tower internals in similar devices in the future.

This paper introduces the tube burst of 0Cr18Ni10Ti tube bundle of a hydrocracking unit reaction effluent / low separation heat exchanger (E106A) in a refinery. Combined with the working conditions of the tube and shell side of the heat exchanger and the anti-corrosion measures, the tube burst samples are analyzed comprehensively by means of endoscopy, spectral material analysis, hardness performance analysis, metallography and scanning electron microscope analysis. The crystal was analyzed by adopting XRD and energy spectrum. The results show that there is NH₄Cl crystal in the inner wall of E106A heat exchanger tube bundle. When the amount of water injection is insufficient, the acid environment formed by hydrolysis of ammonium chloride improves the sensitivity of Cl^- stress corrosion cracking of austenitic stainless steel, which leads to transgranular stress corrosion cracking of the tube bundle of E106A heat exchanger. When the crack extends to a certain extent, the tube bursts. In view of the above corrosion cracking reasons, the corresponding anti-corrosion suggestions and measures are put forward from the aspects of process control and equipment material selection.

According to different shipping schedules, three dynamic calculation models of tank capacity required for uniform shipping schedule, semi-uniform shipping schedule and adjustable shipping schedule are established after taking the influence of seasonal and daily peak shaving and safety margin into consideration. Three models have been applied to calculate the required tank capacity for one LNG terminal. After comparing the results, it is obtained that the tank capacity required for uniform shipping schedule model which has the smallest degree of freedom in scheduling is the largest; the tank capacity required for free shipping schedule model which has the highest degree of freedom in scheduling is the smallest and the tank capacity required for semi-uniform shipping schedule model which has the moderate degree of freedom in scheduling is moderate. Therefore, it is recommended that each LNG terminal should arrange the shipping schedule reasonably according to the actual purchase plan and try to achieve independent shipping schedule operation model so as to reduce the number of storage tanks to be built and save investment.

There are two major problems in the operation and maintenance of the thread-locking ring heat exchanger: internal leakage and seizure during the assembly and disassembly of the thread-locking ring. None of the existing thread-locking ring heat exchangers can avoid the above two problems at the same time. Design improvements were made for the φ1 800 mm high-high pressure thread-locking ring heat exchanger in two steps. The first step is to improve the process, namely to exchange the medium between the tube side and shell side to make the tube side pressure greater than that of the shell side. The pressure difference was used for self-tight sealing, which mainly solved the problem of internal leakage. The second step is to use D-shaped bolts instead of the main thread connection to reduce the weight of the tube box by about 25% to 30%. After these improvements, the total weight and the cost of the original heat exchanger was reduced and the two major problems of internal leakage and seizure during assembly and disassembly of the thread-locking ring was solved.

Fouling of flue gas expander has been a tricky problem currently for the operation of the device. In this paper, the force acting on catalyst fine particles was analysed, and the sintering mechanism of catalyst fines was discussed. The influence of fines concentration, particle size and catalyst element composition on the fouling of flue gas expander was analysed. Meanwhile, the fouling process of catalyst particles in flue gas expander was further discussed. The conclusion is as follows: the key condition of fouling is the existence of high concentration of catalyst fine particles. Fine particle size, element enrichment and high temperature environment have made the molten compounds on the surface of fine particles, the high fines concentration and low flow rate in the local area of flue gas expander as well as the appropriate temperature range created conditions for the fusion compounds to be adhered, sintered and fouled in the flue gas expander.

The air experiment results of three nitrogen cycle compressors with high speed and low flow rate showed obvious differences in performance. By comparing the structural parameters, it's found that there existed a big difference in the front clearance size of the impellers. The size has a significant influence on the performance of compressors. In order to study the influence of clearance on performance, numerical simulation of the three-dimensional flow field CFD method has been adopted for the over current fluid part of the compressor. The results indicate that the pressure ratio increased obviously when the clearance value was smaller, and the reason for the changed pressure ratio was that the reduction of clearance value would influence the distribution of static pressure coefficient inside the impeller; when the clearance value was small, the tip clearance flow had less interference on the flow field inside the blade, and the efficiency of the whole machine would also be improved. Different clearance values resulted in different tip clearance flow which would change the surface load distribution of different blade heights. The above research results are of great significance to improve the structure and performance of the fans in the later period.

Aiming at the problem of the axial displacement of the reaction feed pump in the residue hydrogenation unit which was larger than normal or even exceeded the total clearance of the thrust bearing, it was considered after check and analysis that this problem was related to low pump flow rate. The reason is the wear and tear of the internal parts, resulting in the increase of internal reflux, which led to the decrease of pump flow as well as the rise of inter-segment pressure. This destroyed the balance of the axial force, causing the thrust bearing to bear very large axial force, which resulted in large axial displacement.

Combining with the actual operation of the high-speed pumps in refining and chemical enterprises, this paper expounds the application of high-speed pumps in refining and chemical enterprises. It introduces the start-up operation of high-speed pumps and analyzes the causes of daily failures. Aiming at various failures, corresponding measures are taken. This can ensure the smooth operation of high-speed pumps, thus the operation objectives of high-speed pumps with safe and stable production, long-term operation of the pumps with full load and quality products in enterprises can be achieved.

Aiming at the problem of greatly shortened operation cycle of the ethane cracking furnace in an ethylene plant, this paper analyzed from the production process and it was found that the upstream ethane-rich gas contained impurities such as coke powder and amine liquid which were carried into the radiant coil. Due to the heavy components in the ethane-rich gas, coke was easily formed near the thermocouple at the furnace outlet, which resulted in inaccurate temperature indication. Mechanical analysis on the furnace tube indicates that the metal distribution on the inside surface of the radiant tube was abnormal. The mechanical performance test shows that the remaining service life of the radiant tube was only two years. It’s better to renew the radiant coil from the economic point of view, and the cracking furnace operates normally after the radiant coil has been renewed.

By introducing the working principles of the double pipe crystallizers and the development of the standard Double Pipe Crystallizers in Petrochemical Industry, this paper analyzed the reasons and necessity for the revision of the standard and put forward the basic principles for the revision of the standard. It elaborated the whole process of the revision of the standard and made necessary explanation about the main contents and terms of the revision of the standard.

Desulfurization unit has the most corrosion problems in natural gas purification plant. The corrosion mechanisms can be mainly divided into two categories, i.e., H₂S-CO₂-H₂O corrosion and RNH₂-H₂S-CO₂-H₂O corrosion. As austenitic stainless steels are gradually used in the equipment and pipelines of desulfurization units, problems caused by H₂S-CO₂-H₂O corrosion are partially alleviated. However, with the deterioration of the gas sources, the chloride ion content in the amine solution increases, which makes the corrosion risk less visible and more prominent. In this paper, a corrosion flowsheet was drawn based on the desulfurization process, and typical corrosion cases were selected according to the corrosion mechanisms. By using hardness testing, laboratory analysis, microscopic observation, etc., the root causes of corrosion were dissected. And the measures and suggestions for corrosion alleviation and control were proposed in order to improve the anti-corrosion experience of enterprises and ensure the smooth operation of the devices.

Two feed gas reciprocating compressors (25-K-111A/B) in a 40 × 10³Nm³ / h hydrogen production plant of a petrochemical enterprise in Fujian Province has periodic equipment failures during normal production and operation, so it is only necessary to switch the standby machine for alternate maintenance regularly to maintain safe production. Aiming at the above problem, this paper analyzed the causes of the failures and eliminated the failures through recalculating the unit performance parameters under multiple working conditions in combination with the production and operation conditions. The results show that the hydrogen production unit deviated from the original designed main operating conditions after it had run for a long time under liquid feed conditions. Besides, the two multi-condition compressor units configured in the process flow couldn’t meet the requirements of long-term operation under the condition of liquid feeding. During the operation of the compressor under this working condition, the key performance parameters such as the crosshead pin load reversal angle deviated from the requirements of the unit design, resulting in damage to the main components of the body. After comparison and selection, the whole machine was returned to the factory and was repaired as it was; two skid-mounted small flow compressor units were added to meet the liquid feeding conditions for hydrogen distribution. This solution not only solved the unit failure accurately, but also optimized the process flow. This case can provide reference for solving the problems of similar equipment in hydrogen production plants.