Investigation into the Distribution of Erosion-Corrosion in the Furnace Tubes of Oil Refineries

Crude oil is one of the most important sources of energy in the world. To extract its multiple components, we need oil refineries. Refineries consist of multiple parts, including heat exchangers, furnaces, and others. It is known that one of the initial operations in the refineries is the process of gradually raising the temperature of crude oil to 370 degrees centigrade or higher. Hence, in this investigation the focus is on the furnaces and the corrosion in their tubes. The investigation was accomplished by reading the thickness of the tubes for the period from 2008 to 2020 with a test in every two year, had passed from their introduction into the work. Where the thickness of more than one point was measured on each tube in the same row and the corrosion rate was extracted for three furnaces, starting from the area of ​​heat transfer by radiation to the heat transfer area of ​​the convection in three different operating units. It was found that the highest percentage corrosion value between the standard tube thickness and the thickness of conduction position was 37% with the conduction zone, and 31% with radiation zone. There, the tubes specification was tested. Five percent Cr-0.5 Moly and the temperature of radiation zone was 578 °C to 613 °C and the stack temperature was 410 °C to 450 °C. So, the results show that the maximum erosion occur at the convection zone.

AGE-RELATED CHARACTERISTICS OF ANATOMICAL STRUCTURE AND PANCREAS GROWTH IN THE RACCOON DOG INHABITING THE RADIONUCLIDE CONTAMINATED TERRITORY OF THE BELARUSIAN SECTOR OF THE EXCLUSION ZONE

The objective of the study was to determine the age-related anatomical features and patterns of growth of the pancreas of the raccoon dogs in the zone of removal of the anthropogenic load of the exclusion zone. For the research 4 age groups were used. The terminology of the described structures of the pancreas was brought into compliance with the International Veterinary Anatomical Nomenclature. For the first time it was found that for the raccoon dog, living in a radiation zone, the linear and weight parameters of the pancreas growth depend on age.

Influence of Laser Power and Scanning Speed on the Formation of Single Tracks Formed by Laser Cladding

One of the well-known methods for increasing wear resistance, especially for friction pairs, is surfacing wear-resistant materials on the working surfaces of mating parts [1, 2, 3]. Less expensive grades of steel can be used as the main material in the manufacture of parts, and the surfacing materials in this case must have increased characteristics: mechanical, corrosion and radiation resistance, heat resistance, wear resistance; good anti-friction properties, i.e. more expensive [4, 5]. This significantly reduces the cost of manufacturing or repairing parts, especially in mass production, since cheap grades of steel are used for their manufacture [5, 6]. Improvement of parts by gas powder laser cladding is carried out in shipbuilding, energy, oil and gas and mining industries, in the aviation industry and others. Note that although the method of coating appeared a long time ago, various methods of applying surfaced coatings are still being developed and refined [5,6]. In gas powder laser cladding, coatings are obtained by forcing the powder flow directly into the laser radiation zone [7, 8]. The powder particles are heated in the laser radiation zone and fall on the treated surface (substrate). It is known that the powder particles melt only after they hit the substrate [3, 4], but at the same time the surface layer of the base metal melts. After heating and melting the substrate, a liquid melt bath is formed, which, along with the molten powder, contains a significant part of the base metal components [7, 8]. The intensity of saturation of the surfacing metal with the substrate components is characterized by the proportion of the base metal in the cross section of the track, which is determined by the mixing ratio [9, 10, 11]. It is equal to the ratio of the area of the melted substrate to the sum of the areas of the melted substrate and the track as a percentage and depends on the cladding modes, which is determined after metallographic studies of the structure of protective coatings [8].

Parameters of lipid and oxidative-antioxidant status in persons aged 18-23 from radiation-contaminated areas under conditions of moderate physical activity

Background and Study Aim. There is a significant amount of data on the stressful effects of exercise, which contain conflicting results. Some publications testify to the adaptive processes and the benefits of optimized exercise for various physiological systems, some deny such an effect. Much controversial is the question of combination the physical exercises of different intensity with other stressors. The purpose of the study: to analyze the parameters of lipid metabolism and oxidative-antioxidant system in persons aged 18-23 who lived in territories with different radioecological status, under conditions of moderate physical activity during exercise. Material and Methods. There were examined 50 students from relatively ecologically clean areas (control group) and 50 students from the IV radiation zone (experimental group). The radiation zone is selected by the dosimetry of soil contamination with 137Cs isotopes after the Chornobyl catastrophe. Age of the examined is 18-23 years. Within the framework of the experimental group there were formed two subgroups: the main group for physical training classes (without signs of morphological-functional disorders) and the group for therapeutic physical training classes (TPTC, persons with signs of vegetative-vascular dystonia syndrome). For the control and experimental main group, classes contained all the planned exercises due to the standard curriculum. The program included a combination of aerobic and strength exercises of moderate intensity. For students with signs of vegetative-vascular dystonia, teachers used specially designed therapeutic exercise complexes. The first analysis of parameters was carried out the day before physical training classes, the second one – immediately after the class. Results. Higher levels of total cholesterol and its lipoprotein fractions (LDL-C and HDL-C), triglycerides, oxidative stress index are detected in the experimental group compared to the control group. At the same time lower levels of sulfhydryl groups (SH) were marked. The absence of statistically significant changes in the analyzed parameters in the control group and the experimental therapeutic group after physical exercises is shown in the study. There were evident tendencies of ceruloplasmin level increase in the control along with the absence of such trends in persons with signs of vegetative-vascular dystonia syndrome. This led to the formation of a significant difference between groups for this antioxidant. There is a significant increase in cortisol level and oxidative stress index in the main group of students from radiation contaminated areas. Conclusions. Potentiation of various stress factors in persons who experienced the prolonged exposure to Chornobyl accident reduces the adaptive potential of homeostatic systems. This eliminates the optimization of lipid metabolism and oxidative-antioxidant system through moderate exercise. Exercise therapy does not cause a pronounced stress effect.

Analysis of Tensile Properties of N80Q Steel and 80SH Steel

During heavy oil production, the performance of casing varies with temperature in the service environment. The tensile test of N80Q Steel and 80SH Steel were carried out to evaluate the mechanical properties during the service. The results indicated that the grain size of 80SH steel was relatively uniform and the grain boundary was relatively obvious compared with N80Q steel. A qualitative analysis was performance by relating the tensile properties with different temperature. The results showed that the yield strength, the tensile strength and elongation of N80Q and 80SH steels decreased with increasing temperature, but the degree of decline was limited. The observation of the tensile fracture revealed that the characteristics of the radiation zone of N80Q steel were obvious compared with 80SH steel at 20°C.

Analysis of the Radiation Dose in UV-Disinfection Flow Reactors

UV-disinfection reactors may appear in a variety of forms, but it is useful for all types to identify the inflow and outflow zones (those in which the fluid approaches or, respectively, recedes from the radiation source) and the direct radiation zone (in which the flow occurs along the UV lamp). Due to the spatial variability of the velocity field and the radiation intensity, the radiation doses received in different zones of a reactor differ. In this work, theoretical considerations regarding functions describing the variability of UV radiation doses in flow reactors are presented. The most basic parameter of a UV-disinfection reactor is the minimal time required by the fluid to pass through the reactor. Such time depends on the maximum fluid velocity in the reactor. Based on the theoretical analysis of this phenomenon, the doses in different zones of the reactor have been compared for laminar and turbulent flows. The result of the analysis states that UV-disinfection reactors should be designed in such a way to deliver the required amount of radiation to the point at which the fluid velocity is the highest. The other main conclusion resulting from this comparison yields that the most effective in terms of disinfection is the direct radiation zone, whereas the influence of the inflow and outflow zones is negligible.