Comparison of the stripper configurations before and after the revamp
Ifpexol stripper (1524 mm ID)
Water wash stripper (1524 mm ID)
Original
Modified
Original
Modified
Packing type
Conventional
Koch-Glitsch’s high-capacity
Conventional
Koch-Glitsch’s high-capacity
Bed h eight (mm)
6,000
5,500
6,000
5,500
Dis tributor type
Tubular
156 trough distributor
Tubular
166 low flow distributor
Flow mechanism
Pressurised
Gravitational
Pressurised
Gravitational
Metha nol consumption (normalised basis) Freq uency of distributor blowbacks
1
0.48
1
0.48
Weekly
Eliminated
Monthly
Eliminated
Table 1
with Koch-Glitsch’s proprietary high-capacity wire gauze packing and decreasing the bed height by about 500 mm. Although counterintuitive (as removing packing in a low-ef- ficiency scenario yields fewer chances for the phases to interact), Koch-Glitsch was confident that the combination of packing replacement and the finely tuned liquid distribu - tion would offset the decrease in bed height. When considering the design of a trough distributor, each transition of the liquid flowing downwards from the feed pipe to the first packing layer must be thoroughly assessed. In the case of Koch-Glitsch trough liquid distrib - utors, the liquid is received by a pre-distribution channel, which equalises and disperses liquid from the feed pipe into a parting box located underneath. Adequately sized holes along the parting box proportionally distribute the liquid into each trough according to their respective sizes. Depending on the operational range required and the expected distribution quality throughout the design range, a few different design configurations can be provided for the final liquid delivery mechanism after the troughs under the parting box. In this case, orifices on the side of the
troughs facing towards a splash baffle (Model 156) were chosen for the Ifpexol stripper. For the WW stripper, given the lower liquid flux expected at turndown conditions, the analysis showed that one additional stage of equalisation was required. Therefore, the perforations on the troughs were guided towards sec- ondary troughs with narrower dimensions (Model 166) that would allow for a healthier and more equalised liquid head throughout the operational range. Figure 2 shows a com- parison between the two designs of troughs utilised in lieu of following the original design approach of using identical liquid distributors. Results Table 1 shows a comparison between the original and modified design for the strippers. The results after the mod - ifications were markedly positive, reducing the methanol make-up by more than 50%, finally achieving the targets for methanol usage as per the licensor’s design values, which is one of the most significant advantages of the pro - cess (see Figure 3 ).
Before modi cations
After modi cations
Days
Figure 3 Methanol-to-gas feed ratio before and after the modifications
12
www.digitalrefining.com
Revamps 2025
Powered by FlippingBook