PRODUCTION • PROCESSING • HANDLING
The project is characterised by big numbers – meaning a lot of engineering, plot space, transportation, construction, materials, energy consumption and maintenance
of four trains, each train responsible for processing the sour and sweet gasses into sweet gas, ethane, LPG and NGL. Zooming in on the shell and tube heat exchangers, the original design consisted of four treated gas coolers, four inlet gas coolers and one gas heater per train. All together, these 36 heat exchangers amounted to a combined weight of 1,704,400kg. Just imagine the plot space they would have taken up, the energy consumption required, the costs for the materials needed to fabricate them, installation and spares for maintenance, the costs of transportation and the impact on the environment. Te three heat exchangers are the treated gas cooler, cooling the gas after the treatment, the inlet gas cooler, cooling the gas before it enters the next phase in the process and the gas heater that is situated in a later stage in the process, for heating the gas before entering the condensate drum. Because of the scope of this project, alternative solutions can have an enormous impact. Luckily the new owner was very interested in alternative
Treated Gas Cooler TEMA type Tube length (mm) Shell ID (mm) Weight each shell (kg) Shells per unit Total weight 4 trains (kg) Shells required 4 trains
Conventional CEU 7,315 1,450 36,192 4
579,000 16
Inlet Gas Cooler TEMA type: Tube length (mm) Shell ID (mm) Weight each shell (kg) Shells per unit Total weight 4 trains (kg) Shells required 4 trains
solutions and decided to grant BHT the chance to do so for the thermal and mechanical design, purchasing of materials, manufacturing, inspection, pressurising and delivery of the before-mentioned heat exchangers. BHT’s engineers are trained to optimise the design, taking the overall process into consideration. For the treated gas coolers and the inlet gas coolers
BHT’s engineers immediately saw ways to reduce the number of shells. Basically they started from scratch, asking themselves questions such as, “What is the most convenient solution regarding pressure drop, logarithmic mean temperature difference (LMTD) and an optimal heat transfer coefficient?” By utilising all their thermal engineering skills they were able to greatly optimise the design of the treated gas cooler and the inlet gas cooler. Te number of shells was reduced by 50%, resulting in a weight saving of more than 35%. All this was achieved taking into consideration a vibration-free design that can be handled at site. Te new design has, in comparison to the design from the datasheet, a total weight reduction of ≈ 600,000kg, which greatly reduces the total cost price and plot space. Besides the low cost price this weight reduction also generates the following benefits:
l Less steel structure/foundation (40% less foundation work. Te number of foundations are
Alternative CFU 9,500 1,430 46758 2
373,000 8
Conventional CFT
7,315 1,450 65,127 4
1042,000 16
Alternative CFS
9,500 1,600 81,400 2
651,000 8
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The tables show the technical differences between the treated gas cooler and inlet gas cooler
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