Математическая модель сварного пластинчатого теплообменного аппарата для колонны синтеза аммиака

Abstract

Plate heat exchangers (PHEs) are widely used in industry, and can be regarded to the compact heat exchange equipment. But the application of PHEs of standard plate-and-frame type is limited by temperature and pressure operating conditions. The design of welded PHEs allows widening the application range. In the present work the specially designed welded PHE is presented, which can be used for high pressures (up to 32 MPa) and temperatures (520 °С) in the ammonia synthesis column. It consists of the stack of round corrugated plates with diameter 626 mm, which are welded together to form a number of channels for cold and hot streams exchanging heat. The mathematical model of considered welded PHE is developed, which enables to perform the thermal and hydraulic design for specified process conditions and also rating calculations of the unit with determined parameters of its construction. The validity of the proposed relations and developed mathematical model is confirmed by comparison with the data of tests on welded PHE installed in ammonia synthesis column at industrial enterprise of ammonia production instead shell-and-tube heat exchanger. The use of welded PHE instead shell-and-tube unit enable to cut down the volume occupied by heat exchanger in high pressure shell of ammonia synthesis column and allows increase of the volume of catalyst. It leads to 15 % rise of ammonia output.