GPE has been supplying TEMA R and C class, removable and fixed type heat exchangers to various industries such as Oil & Gas, Refineries, Petrochemicals, Fertilizers, Steel, Defense, Renewable Energy etc. since its inception.
So far GPE has supplied more than 200 critical heat exchangers as a part of its various process packages. As a strategic decision, we are now targeting standalone specialized fabricated equipment, to widen our product range. Our knowledge of manufacturing modular process plants (where heat exchangers were often supplied) has helped us provide optimized designs by clearly understanding the needs of the end-user.
Recently, we have exported 9 shell and tube heat exchangers to be used in a kerosene processing plant. The customer was located in USA and the end user was in Middle East. The below table provides an overview of the process details of these exchangers.
Reasons behind selecting AES / BKU TEMA type:
- a) AES is suitable for the rigorous duties associated with high temperatures and pressures.
- b) To facilitate the shell side cleaning.
- c) Temperature difference between fluid in the shell and fluid in the tubes is very high. Eg. For Sr. No. 1 (OH-Liquid Feed Exchanger) inlet temperature of kerosene at shell side is 40°C whereas inlet temperature of hydrocarbon flowing through tubes is 218 °C. This higher than normal range of temperature difference causes thermal expansion in shell, tubes, tubesheet and other corresponding welded components. In general, the greater the temperature change, the higher the level of stress that can occur. This difference in thermal expansion causes the vibrations which eventually damages the equipment. To mitigate the problem, we used following options:
Floating Head Design – AES: This type meets the expansion problem by having one stationary tubesheet, and one free to move – “float” – back and forth as the tubes expand and contract under the influence of temperature changes. Also this design was perfectly suitable for volatile fluids such as Kerosene. This design also helped us to keep a lower shell dimeter (which resulted in to a lower price) by providing higher surface area compared to the other “pull through” options like AET or BET.
“U”-Tube Design – BKU: In the “U” -tube exchanger, the shape of the tubes takes care of differential expansion. As the name implies, the tubes have a “hairpin” shape, with both ends fastened to one tubesheet. This “U” bend design allows each tube to expand and contract independently.
Construction of heat exchangers: All the tube to tubesheet joints were expanded and seal welded. Before proceeding with tube to tubesheet welding on job, we pre-qualified welders as per the approved WPS. Two runs of welding were done out of which the first was kept autogenous to ensure proper fusing . We also conducted a mockup test for tube to tubesheet joints as described in ASME Sec VIII Div. I Nonmandatory appendix A and TEMA. (This destructive test was performed on a group of representative tubes rolled into a sample section of tubesheet).
Third party inspection was done by TUV-Nord. Final hydrotest was witnessed by the end-user.