Shellside Impingement Protection

Impingement devices are often used in tubular equipment to protect the tubes from erosion due to fluid impingement at the shell inlet nozzle. One 

Sometimes tubes are omitted from the tube bundle in order to provide space for an impingement plate. The impingement plate in this case is generally a circular or rectangular plate located a short distance from the row of tubes and secured by various means. A modification of this type is to form the plate and surround the bundle with it as a partial shroud. Omitting tubes from the tube bundle has many advantages, especially when inlet nozzle velocities are very high or when tubes must be omitted from the baffle windows in order to prevent problems associated with tube vibration. 

Two other methods are sometimes used to provide impingement protection, One method utilizes the first two rows of tubes adjacent to the nozzle for impingement protection. The tubes are plugged and rods are sometimes inserted through the tubes to prevent excessive tube movement in the event of a tube being cut sufficiently to allow movement. The other method replaces the first two rows of tubes adjacent to the nozzles with rods of the same diameter at the tubes. Both of these methods are effective and inexpensive in the common materials of construction. 

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Impingement. When the heating fluid enters the shell at a high velocity, an impingement plate should be provided to protect tubes from damage. Vapor belts (Fig. 15.10g) are sometimes used to reduce shellside inlet velocities. 

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