Like an automobile radiator, the internals of heat exchangers require periodic cleaning and repair. It is important for exchangers and related components to be positioned to facilitate access to their internal parts.
For the shell and tube heat exchangers, the tubes and the interior of the shell can be cleaned in place with high-pressure steam or water and rodding devices. If the design of the exchanger permits, the tube bundle can also be removed for repair or cleaning.
Tube bundles and head and shell covers can be removed by built in fixed handling devices (e.g. davits, hitch points, pulling posts), fixed structures with trolley beams and travelling gantry cranes or by mobile equipment (e.g. cranes and hydraulic bundle extractors).
Following figures provide examples of tube bundle removal equipment. Considerable saving can be achieved if the plant is serviced by mobile equipment.
The use of tube bundle extractors eliminates the need for permanent tube bundle removal structures, with considerable saving to the plant. These mechanism weigh seven tons and are capable of pull forces greater than 500, 000 lbs.
The extractor is lifted into position by crane and clamped to the shell flange of the exchanger, which is stripped for bundle removal. Held in position by the crane, and balanced by the extractors levelling cage, the bundle is pulled out of its shell with pull rod attachments that use hydraulic force.
The whole unit is then lowered to grade and can be relifted onto a truck for offsite repair or cleaning. Following figure shows an elevated exchanger with the extractor and crane in position for tube bundle removal.
Following figure provides the details of hydraulic tube bundle extractor.