Showing posts with label replacement. Show all posts
Showing posts with label replacement. Show all posts

Thursday, November 17, 2016

Shell and Tube Heat Exchanger Refurbishment

shell and tube heat exchangers tube bundle removed for refurbish
Two shell and tube heat exchangers getting refurbished
at industrial site. Tube bundles have been removed.
Shell and tube heat exchangers are regularly employed throughout industrial and commercial sites as a means of producing heated or cooled fluids. They consist of a pressure vessel and an internal tube bundle. The flow paths of the pressure vessel and the tube bundle are isolated from one another, giving a shell and tube heat exchanger four nominal connections.

  • Vessel inlet
  • Vessel outlet
  • Tube bundle inlet
  • Tube bundle outlet
Most often, the subject process fluid to be heated or cooled will flow through the pressure vessel, contacting the surface of the tube bundle contained within. If the heat transfer fluid flowing through the tubes is warmer than the process fluid in the vessel, heat will conduct through the tube wall into the process fluid, increasing its temperature. If the fluid in the tube bundle is cooler than the process fluid in the vessel, the process operates in the reverse fashion. Construction details of shell and tube heat exchangers can vary, but the basic operating scheme remains constant.

The lack of moving parts and ruggedly constructed nature of shell and tube heat exchangers tends to grant them a good measure of longevity for most applications. Regardless of any exceptions to that statement, there will eventually come a time when refurbishment or replacement is needed. If the pressure vessel is serviceable, or can be made so with a reasonable amount of cost, replacing the tube bundle may be the main element of an operation aimed at returning the heat exchanger to like new service.

Tube bundles are just that, bundles of tubes. With the right set of dimensional information and specifications, an identical fabrication can be purchased and put in place. It is not always necessary to revisit the original manufacturer. If drawings are still on file for the unit, sufficient information can be gleaned from them to produce a replacement tube bundle that will provide rated performance.

Ordering up a replacement tube bundle is not complicated, but the operation can be smoothed out through contact with involvement of an experienced engineer that can make sure all the necessary information is on hand and step you through the process. 

Tuesday, September 20, 2016

Replacing Heat Exchanger Tube Bundles

heat exchangers outdoors at oil refinery
Heat exchangers of many sizes are used throughout industry
Heat, a well recognized energy component of countless industrial processes. Heat exchangers are employed to move or transfer heat between two media, and are available in a wide variety of designs and configurations. They are manufactured from materials and in forms to accommodate the specific performance requirements of each process, machine, or operation.

The shell and tube heat exchanger is one common type of this heat transfer device that can be found in many commercial buildings and industrial plants. The unit is comprised of a vessel, or shell, with an array of tubes contained within. One fluid will flood the shell, encompassing the tubes through which a second fluid passes. The contact between the fluid within the shell and the outer surface of the tubes facilitates the transfer of heat energy between the two media. Applications for shell and tube units typically involve two liquids or one liquid and steam. They are not suitable for applications involving air streams.

Eventually, all heat exchangers need either major overhaul or replacement. Tubes tend to deteriorate faster than the shell, so replacement of the tube bundle can breathe extra life into a heat exchanger. Original documentation provided with the unit, plus a physical inspection, should provide all the information needed to have a new tube bundle manufactured. Numerous sources are available for replacement tube bundles, with the original manufacturer being only one potential source.
The replacing of a heat exchanger is also a good time to examine the performance delivered by the existing unit. Was it a limiting factor in the operation of the process? If so, perhaps this may be an opportunity to build in some headroom. Whatever the case, recognize that bringing in a product specialist with experience and knowledge will provide the beneficial leverage you need to get the job done right and finished on time.