TP2:Piping Networks and Packed Beds
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| Main subject | |
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| Important Concepts | |
| Next Module | |
| Compressible flow | |
Introduction
Most piping networks generally have pipes connected in parallel. For flow that branches into two or more parallel pipes that rejoin at a downstream junction, the following is true:
- Conservation of mass throughout the system. This is satisfied by requiring that the total flow into a junction is equal to the sum of the flows in each of the branches.
- The pressure drop (and hence viscous head loss) between any two junctions of a network must be the same for all branches.
A packed bed is a hollow tube, pipe, or other vessel that is filled with a packing material. The packing can be randomly filled with small objects like Raschig rings or else it can be a specifically designed structured packing. Packed beds may also contain catalyst particles or adsorbents such as zeolite pellets, granular activated carbon, etc.
The purpose of a packed bed is typically to improve contact between two phases in a chemical or separation process for achieving rapid mass and heat transfer, and particularly in the case of fluidized beds, catalytic chemical reactions. Packed beds can be used in chemical reactors, scrubbers, strippers, and absorbers.
Objective
To determine the flow rate in a parallel pipe network and to determine the pressure drop in a packed bed.
Learning Outcomes
- To show how to use conservation of mass and equal head loss in each path of a network to determine overall flow rate and flow rate in each branch.
- To show how to use the Ergun equation to predict pressure drop in a packed column.
- To explain the difference between interstitial velocity (Eq. 12.125) and superficial velocity (12.129) in the Ergun equation using the void volume ϵ.