Slotted impingement plates for heat exchangers

Abstract

Impingement plates for shell and tube heat exchangers are positioned between the inlet openings and the tubes with the surfaces of the impingement plates being normal to the flow path of the liquid entering the shell from the inlet openings and having a plurality of openings through which a portion of the liquid passes before contacting the tubes. The openings can be formed as elongated parallel slots that are positioned parallel to the tubes and function to enhance the fluid flow, especially in the area that is immediately downstream from the impingement plates, thereby reducing fluid stagnation, fouling and tube erosion and prolonging the useful life and time in service between maintenance shut downs.

Description

FIELD OF THE INVENTION[0001]The invention relates to impingement plates for shell and tube heat exchangers.BACKGROUND OF THE INVENTION[0002]Fluid heat exchangers are widely used in the industry. One common heat exchanger is known as a shell and tube heat exchanger and includes a cylindrical housing or shell encompassing a bundle of tubes. In this type of heat exchanger, heat from a first fluid flowing through the tubes is transferred to a second fluid flowing through the housing, as a result of the second fluid flowing in contact with the outer surfaces of said tubes. The second fluid enters the shell through a nozzle and is directed initially to an impingement plate which deflects and redirects the second fluid to flow toward and about the outer surfaces of said tubes, as generally disclosed in U.S. Pat. No. 3,938,588.[0003]The inlet fluid initially has a high velocity and dynamic force when it impacts on the impingement plate. In many conventional shell and tube type heat exchange...

AI Technical Summary

Benefits of technology

[0009]The improved impingement plate of the present invention for use in a shell and tube heat exchanger are positioned between the inlet openings and the tubes, the surfaces of the plates being normal to the flow path of the liquid entering the shell from the inlet openings and are provided with a plurality of openings through which a portion of the liquid passes before contacting the tubes. In one aspect of the invention, the openings are formed as elongated parallel slots and the impingement plate is positioned so that the slots are parallel to the tubes. The openings enhance the fluid flow, especially in the area that is immediately downstream from the impingement plates. This improved fluid flow prevents fluid stagnation by allowing a portion of the pressurized liquid to pass through the plate, the majority being diverted around the periphery of the plate to prevent tube erosion, and therefore avoids unnecessary shut downs of the heat exchanger for service.

Problems solved by technology

In many conventional shell and tube type heat exchangers the impingement plate adjacent the inlet nozzle protects the tubes from direct impact of the high velocity inlet fluid, but often creates operational problems when fluid flowing downstream of the impingement plate has reduced velocity due to the vortex effect of fluid motion at the sides of the impingement plate.

This results in fouling accumulation on surfaces of the tubes, particularly in the region designated herein as “fouling area” immediately downstream from the conventional impingement plate.

Such fouling retards heat transfer to tubes in that area and furthermore may create a corrosive environment on the outer surfaces of said tubes.

If the fouling and corrosion becomes severe enough, eventually the heat exchanger must be completely shut down and retubed.

This accumulation inhibits heat exchange with the fluid flowing within tubes by reducing the ability of the in-flowing fluid to freely circulate around these tubes and thus reduces the efficiency of the heat transfer.

Also, this fouling may cause corrosion on the surfaces of these tubes.

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