When design and selection personnel are faced with a shell and tube heat exchanger, the corrosiveness, viscosity, and operating pressure of the medium directly affect the material selection and flow rate settings for the tube side and shell side. If the chloride ion content in the medium exceeds 200 mg/L, ordinary carbon steel or 304 stainless steel may undergo pitting corrosion, and in this case duplex steel tube bundles are recommended. Confirmation of these parameters is the basis for subsequent calculations, but deviations often occur under actual working conditions.
For corrosive media, carbon steel, stainless steel, or duplex steel can be selected separately for the tube side and shell side. For high-viscosity media, the shell side should adopt a baffle structure to enhance turbulence, with the flow rate controlled at 0.5~1.5 m/s; for low-viscosity media, the tube side flow rate can be set at 1~3 m/s. When the operating pressure is higher than 2.5 MPa, the tube sheet thickness and flange rating need to be checked. The QXZ-100 model provides multiple material combinations for easy matching according to medium characteristics.
After determining the materials and flow rates, the heat exchange area needs to be calculated based on the system heat load, with a 10%~20% safety margin reserved. If the heat load fluctuates greatly, the margin can be appropriately increased or a detachable structure can be used for later adjustment. The above parameters are for reference in selection calculations, and actual use needs to be combined with the system heat load and safety margin.
