Heat exchangers are located within the conventional process unit plot plan, close to related equipment, to support economic pipe runs, flexibility, process requirements and operator and maintenance access.
Support of equipment (e.g. air coolers or vertical reboilers) can also
influence the heat exchanger location. Horizontal Shell and tube heat exchangers should be positioned so that the channel end faces the auxiliary road or maintenance access way for tube bundle removal with adequate space provided at the front end of the
exchangers for bonnet removal.
- Exchangers having cooling water from underground to channel shall have the anchor at the channel end.
- Anchor locations for exchangers without underground piping
connections shall be determined by piping flexibility,
- Horizontal reboiler anchor location depends on relationship of vessel (anchor 1 end only)
- Locate thermosiphon reboiler supports to minimize differential
expansion. When one reboiler is used consider supporting reboiler from vessel. Support for more than one reboiler may be a structure. Check with vessel department for method of support before supporting 2 or more reboilers from Vessel.
- When possible support thermosiphon reboilers independent of
platform to improve maintenance and operation accessibility Exchangers can be located as single items, in pairs ( this is the most common application) or in larger groups when no intermediate control is required between the shell and tube streams.
The single and paired installation is shown below. Paired exchangers may operate in series, parallel or dissimilar services; grouped exchangers operate only in series or parallel.
Following diagram shows the sample of parallel and series xchanger
installations. Paired or grouped exchangers should be spaced to allow a minimum of 18 inch (450 mm) between the outside of adjacent channel or bonnet flanges to facilitate access to flange bolts for maintenance.
Space should be provided on either side of paired exchangers and at both ends of grouped exchangers for control and operator access.
Following figure shows a structure mounted installation and its required access areas.
Horizontal exchangers may be stacked to a preferred maximum top shell centreline elevation of 12 ft (3600 mm) from grade or platform as shown below. Stacking of exchangers above this height may require platforming for access to channel and bonnet flanges and fixed handling devices.
Horizontal shell and tube exchangers may be located at grade or elevated in steel or concrete structures when process requirements or space availability dictates.
Support for horizontal exchangers as shown below is by saddles attached to concrete piers for grade mounted installations and by saddles attached to steel frames in elevated installations.
When possible, support should be inline for common foundation design. If process requirements permit, shell and tube exchangers can also be mounted in a vertical position, supported by lugs and tower nozzles in a tower-supported installation, within concrete or steel structures, and by concrete piers.
An important feature to remember when working with tower supported vertical reboilers, not requiring springs is shown below.
- The layout designer must set the reboiler support lug elevation 1 in / 25 mm above the platform steel, and not at the steel elevation.
- Before maintenance, the 1 inch / 25 mm gap will be shimmed, thereby enabling the reboiler load to be carried by the platform steel during maintenance turnaround.
- The nozzle and channel flange will be unbolted and the channel section removed.
- The tube bundle is then ready to be removed.