In-Line Cleaning Of Tube-Shell Heat Exchanger With Acoustic Waves (16-Sep-2009)
Tube-Shell heat exchangers are a commonly seen piece of process equipment in the Chemical and other industries. The fouling of the heat exchanger causes reduction of the heat transfer efficiency, increase of energy consumption and un-wanted process shutdowns. In addition, when working in a corrosive environment the heat exchanger can have excessive metal loss because of the “under-deposit corrosion” from the particle deposits on the tube surface. Maintaining a clean surface in a tube-shell heat exchanger, or keeping the surface fouling to a minimum level, is vital for long-term operation. The cleaning of the tube-side heat transfer surface is particularly challenging, especially for those exchangers with many tubes and relatively small tube diameters. The elevated operation pressure and highly corrosive environment also bring additional challenges to the cleaning process.
IN-LINE CLEANING OF TUBE-SHELL HEAT EXCHANGER WITH ACOUSTIC WAVES
Tube-Shell heat exchangers are a commonly seen piece of process equipment in the Chemical and other industries. The fouling of the heat exchanger causes reduction of the heat transfer efficiency, increase of energy consumption and un-wanted process shutdowns. In addition, when working in a corrosive environment the heat exchanger can have excessive metal loss because of the "under-deposit corrosion" from the particle deposits on the tube surface. Maintaining a clean surface in a tube-shell heat exchanger, or keeping the surface fouling to a minimum level, is vital for long-term operation. The cleaning of the tube-side heat transfer surface is particularly challenging, especially for those exchangers with many tubes and relatively small tube diameters. The elevated operation pressure and highly corrosive environment also bring additional challenges to the cleaning process.
The existing methods used for exchanger cleaning all have disadvantages:
(1) Periodic cleaning with the process shutdown - time consuming and loss of valuable process on-line time.
(2) External vibration - it is with limited effectiveness because of the large number of tubes involved. It may also have some safety concern.
(3) Periodic large pulsation of the process gas passing through the tubes - limited by the process conditions (availability of the gas). In addition, this method does not work well for those tubes already plugged.
(4) Invasive cleaning methods (sand blasting, steam cleaning, soot cleaner, ultrasonic cleaning head, water picking, etc.) - cleaning job cannot be performed without the interruption of the operation, and/or could leave residues during/after cleaning which is not acceptable because of product contamination and the negative impact on the downstream process.
(5) Acoustic cleaning technology - existing technology only applied to the external tube surface of the heat exchanger, with one exception on the lower-pressure air pre-heater used in the Power industry which requires a relatively large tube diameter (when gas is in the tube side).
In addition, none of the above works for the highly corrosive environment which could damage the cleaning device quickly.
Therefore, it is desired to develop a non-invasive, on-line cleaning technology to clean the tube-side of the tube-shell heat exchanger, which does not interfere with the operation, does not have residues after cleaning, and is applicable to relatively small tube size (e.g., 1 inch in diameter), under elevated operating pressure and corrosive conditions. This paper documents the development and application of such a technology. The advantages of such a technology include (but not limited to)
prevent premature system shutdown for cleaning,
keep high heat transfer efficiency, save energy, and
reduce metal loss
A unique acoustic cleaner has been developed to clean the tube side of a tub...
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