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The possibility of increasing the thermal efficiency of plate cross-flow heat exchangers is examined. The design of the corrugated heat-exchange plate design with different slope angles of the troughs relative to the direction of movement of the heat carriers is analyzed.Plate heat exchangers with a sectional body and cross-flow movement of the heat carriers are being increasingly widely used in the oil refining industry of many countries in the world. Compablock heat exchangers (Alfa Laval) are the best known equipment of this type; with high thermohydraulic efficiency and compactness, they are successfully replacing traditional shell and tube heat exchangers, which have a 2.5-3 times greater heat-exchange surface area and are 3-5 times heavier.The sectional body of these heat exchangers consists of flat, thick-walled steel elements. In Compablock heat exchangers, corrugated square plates made of corrosion-resistant metals and alloys are used as the heattransfer elements. The trough angle of slope to the direction of movement of both heat carriers moving in the perpendicular (cross) direction relative to each other are the same and equal to 45° (see Fig. 1a).A design for a cross-flow plate heat exchanger was developed at UkrNIIkhimmash and has a number of advantages in comparison to the Alfa Laval units. The side walls of the sectional body are in the form of cylindrical shell elements, which reduced the weight of the unit as a result of the decrease in the thickness of the walls of the body. In addition, the cylindrical elements of the walls form collecting chambers for input and output of the heat carriers, and their cross section is in the form of a segment that ensures uniform distribution of the heat carriers over the entire width of the heat-exchanger channels, and consequently, efficient use of the heat-exchange surface.We know from experience in using heat exchangers that in 95% of the cases, the heat carriers differ from each other both in the flow rate and in the thermophysical properties, which certainly causes the difference in their heat-transfer coefficients α. We also know that heat-transfer coefficient k, and consequently also the heat-exchange surface area, are primarily determined by the smaller of the two values of α. Regulating the level

Approaches to selecting construction and gasket materials for developing new and modernizing existing oil refinery equipment and the results of corrosion-electrochemical studies are presented.Materials for building vessels and equipment are selected based on their suitability for the design, compliance with standards and norms, and assimilation in the industrial plant. In turn, the suitability of a material is determined by the resistance to overall corrosion, corrosive cracking, hydrogen sulfide embrittlement, point-pitting and crevice, intercrystallite, structurally selective, and other types of corrosion, structural strength at a given temperature, manufacturing processability of the equipment, and economy.There are two approaches to selecting construction materials in developing equipment designed to operate with aggressive media -European and American [1][2][3]. According to the European approach, the selected construction, welding, and gasket materials must ensure a defined lifetime with the minimum number of breakdowns, i.e., high reliability of the equipment. This naturally affects the cost of the equipment, since more alloyed structural materials are selected as the basic materials. The American approach consists of selecting the cheapest construction materials, even if the reliability of the equipment is lost, but costs for unscheduled repair of the equipment are included in project estimates and a given operating life is simultaneously guaranteed. The lifetimes are 20 years for towers, 30 years for reactors, 20 years for tanks, 20 years for heat-exchanger bodies, 5 years for carbon steel tube banks, and 10 years for stainless steel tube banks.The developer using the least expensive materials obtains exemptions [3].UkrNIIkhimmash Co. uses both approaches in practical selection of construction, welding, and gasket materials, giving preference to guaranteeing operability for a given lifetime, since breakdown of a reactor, tower, heat exchanger, or tank not only involves repairing the structure and correspondingly shutting down the unit and manufacturing less product, but also possible environmental damage and fire hazards. For this reason, experience in operating existing equipment, the work by VNIIneftemash, Lenneftekhim, VNIIkhimmash, and other organizations, and the results of corrosion studies are the basis in developing equipment according to the basic designs of Shell, Axens, ABB,. In recent years, customers of the developed equipment have been stipulating a maximum corrosion rate of construction materials of 0.1 mm/year.

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