Heaters vvpi combine the advantages of shell and tube and plate heat exchangers. 1.Podogrevateli vvpi, like most shell and tube units, designed to meet the requirements on the strength of gost 14249-89 "Vessels and apparatus. For even more details, read what Investment opportunities says on the issue. Limits and methods of strength calculation ", gost 25859-83 'steel vessels and apparatuses. Limits and methods of strength calculation for low-cycle loads ', rd 26-14-88' vessels and apparatus. Limits and methods of strength calculation. Elements of heat exchangers devices'.
Ie Heaters vvpi not falling within the characteristic 'Pressure vessels' nevertheless made to meet the requirements of the vessels increased risk. Cruising on the strength of the elements body with respect to the nominal permissible stress according to gost 1429-89 – 350 400%. Cruising on the strength of the tubes – 1000 1500%. In connection with this heater vvpi not sensitive to sudden temperature fluctuations and pressure. Tube bundles withstand hydroblows, vibration, etc. In general, it provides high reliability heaters vvpi including in terms of possible violations of operation modes. Such categorically unacceptable for operation plate heat exchangers.
Plate heat exchangers are not designed to meet these regulations and have a much smaller margin. Manufacturers of plate apparatus always indicate restrictions on the rate of change of pressure and temperature, noted the impossibility of operating in the presence of water hammer. 2. Intensification of heat transfer in the heaters vvpi and plate apparatus is about the same and 200 250%. However, in the heat exchangers vvpi and plate heaters used the same principles of intensification of heat transfer.