Air cooling equipment with high performance and reliability

Abstract

Air cooling equipment (ACE) of traditional design -AVG and AVZ with a ribbed pipe heat exchange surface, have a number of important drawbacks due to the horizontal position of the 12-m tubes, as extensive experience in using them has shown: • • • • • sagging of the tubes and formation of a "dead" zone for heat-carrier overflow during operation and thawing of the tubes on shutting down, which subsequently results in important breakdowns; • • • • • the need for large areas for installing them and the use of fans with lower-speed electric motors and large rotors; • • • • • the decrease in cooling efficiency in the condensation mode; installation of heat-exchange sections in the shape of a "cabin" (zigzag) causes uneven distribution of cooling air flow and parasitic leaks;• • • • • uneven expansion of the tubes rigidly fixed to the collectors due to uneven distribution of media in the intra-and intertube spaces so that the tubes buckle or crack in the region of connection; the same effect is observed in the starting and transitional modes.The analysis of these drawbacks demonstrated the necessity of using ACE of more up-to-date designs for the newly constructed catalytic cracking plants (customer -TAIF -NK Co., general designer -VNIPIneft').Anod -Teploobmennyi Tsentr (TTs) Ltd. (Nizhnii Novgorod) is designing and manufacturing heat-exchange equipment for the energy, petrochemical, transport, and other branches of industry.This equipment is designed to operate with different media -any liquids and gases at pressures up to 20 MPa, temperatures up to 600C, and cyclic loading. The material of the heat-exchange surface are selected in consideration of the operating conditions, assigned life, and cost indexes.The new design of the heat-exchange surface -made of coils with a small bend radius (Fig. 1) -is based on the developments. This design has much better specifications than the straight-tube, plate, and ordinary coil designs. Let us consider its advantages.