Distributor erosion

Distributors Carbon steel, top distributor externally lined with 1 in. ( 2 cm) thick erosion-resistant refractory... 

Ladder and spray distributors rely on pressure for their action. They provide a large gas flow area but a somewhat limited liquid flow area they are light and cheap but are sensitive to corrosion, erosion, and to a certain extent plugging. They are most suitable for high gas/liquid ratio applications. 

The distributor perforations are a high-velocity area and are likely to deteriorate in service, particularly if the service is corrosive or erosive. Correct material selection is therefore important. 

Impingement of high-velocity jets issuing from distributor perforations on column walls and other internals should be minimized. Cases have been reported (215, 410) in which such impingement caused severe corrosion in other situations, it may also cause mechanical damage and erosion. 

In order for manufacturers to specify or design a distributor correctly, they must be provided with concise information on the service its plugging, corrosive, erosive, and foaming tendencies and of any requirements which may affect distributor selection or design. 

Plugging and erosion in spray distributor nozzles that have been in service often occur at the nozzle spirals (109) and may be invisible from outside. It is best to water-test these distributors during the shutdown such a test will also reveal internal leakage. However, this is not always practical. Alternatively, a sample of nozzles (about one in five) should be dismantled and inspected. Even better, these nozzles can be rigged and water-tested outside the column. 

Note 2 — If erosion is suspected, omit baffle or replace with a perforated distributor pipe with horizontal holes. Avoid tangential Inlets. 

All parts of the fluidized bed unit are subject to erosion by the solid particles. Heat transfer tubes within the bed or freeboard are particularly at risk and erosion here may lead to tube failure. Erosion of the distributor may lead to poor fluidization and areas of the bed becoming deaerated. 

To prevent severe erosion by jet impingement of internals such as heat exchanger tubes, one must know how far a vertical jet issuing from a distributor such as a perforated plate will penetrate into a fluidzed bed. This knowledge is also required to prevent piercing by jets of the surface of shallow beds. Blake et al. [58] reviewed the correlations and data available in the literature for the penetration depth of upward jets into fluidized beds. They proposed the following correlation ... 

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