Mechanical design for height of a formaldehyde fixed bed reactor


Fixed bed reactor filled with silver catalyst converts methanol into formaldehyde by oxidation. To construct the reactor, mechanical design is required for the construction engineers. General design details and data like volume of reactor, number of tubes, type of catalyst packing and process conditions are used to develop mechanical design. For instants, below we have some data developed by process design engineers, that can be used for developing the mechanical design of the reactor. 
  • Catalyst : Silver
  • Length of reactor : 5 m 
  • Diameter of reactor : 2.4 m 
  • Catalyst form : crystalline granular form 
  • Height of tube : 4 m 
  • Inlet stream temperature and pressure : 149.6 °C and 28.0 psi 
  • Outlet stream temperature and pressure : 343 °C and 25.0 psi
  • Material of construction : carbon steel
Mechanical design includes adding the safety parameters to data values, determining the structural supports, manhole provisions, flange fittings etc to the reactor. Corrosion allowance, reactor height and head thickness are computed here. Shell thickness will be increased more than the actual design to provide the corrosion allowance and similarly pressure shocks caused by pressure fluctuation are considered during designing the head section. Crown radius and knuckle radius are calculated to determine the height of the ellipsoidal head of the reactor. Mechanical design solver given below calculates the height of a formaldehyde fixed bed reactor.