Page 107 - Impiantistica industriale

correlation with speed. The positive result of all tests
In plot 1 we can see the performance of the he- confirmed that Flowserve seal
ating rods. The heating rods need to implement
additional energy into the cavity up to a test speed “technology can be safely
of 28.350 rpm, as the inner energy, produced by operated at multiphase CO
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the seal due to windage, is not sufficient to keep conditions for turbomachinery
the cavity at 210 °C. That changes, as the seal is
operated at trip speed of 29.768 rpm, where the
heating rods turn off, as the inner energy of the seal Flowserve FLS is undoubtedly a pioneer in this field
is high enough to keep the cavity at 210 °C by the and the Gaspac seal was designed to meet the
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seal’s windage. actual sCO requirements according to Flowserve
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design standard and based on existing experience
To simulate a prolonged, pressurized stop of the in CO pump & compressor industrial applications,
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compressor at ambient to cold housing tempera- where Flowserve cumulated experiences in sCO 2
tures, the inboard seal cavity was fully flooded with applications for pilot projects.
liquid CO during static conditions. After the static The seal shows overall stable and repeatable per-
2
test sequence, the seal was started up until the li- formance, with a very low leakage level which is
quid phase changed into transient / supercritical- fundamental for the Close Loop Process to mini-
CO . Beside the seal performance, also the star- mize emission and reducing refilling needs. At the
2
tup torque was measured to indicate the impact same time, the low leakage reduces risk of ice for-
of liquids and potential ice formation at the primary mation on the primary-vent-side, improving seal
vent. reliability, as well minimizes seal system complexity.
The extensive DGS test campaign included seve-
The start/up sequences were several times repea- ral operational and transient conditions at the most
ted. The torque development during start/up was severe scenario for a dry gas seal, such as liquid
stable, uncritical and comparable to the startup phase CO @ DGS. The positive result of all tests
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measurements at sCO condition. confirmed that Flowserve seal technology can be
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safely operated at multiphase CO conditions for
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Conclusions turbomachinery.
The Gaspac seal test data available are being
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analyzed by FLS and are of extreme importance to
The high demand from the emerging renewable validate numerical calculation programs and ther-
energy industry, utilizing sCO , is closely related to mal models for the prediction of seal performance
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the availability of high-end shaft sealing solutions for high temperature turbomachinery, where the
for the turbomachinery equipment. DGS techno- DGS is a key element to ensure efficiency, safety
logy development was driven in the past mainly by and reliability for emerging renewable energy indu-
Oil& Gas Industry – i.e. higher operating pressures - stry.
but it is a key partner also for the success of energy The test highlighted the robustness and reliability
transition process. of the Gaspac® seal under extreme conditions, le-
The paper gave a brief insight regarding analytical aving surprising scope for subsequent even more
& design process and final performance testing of severe tests. The seal Gaspac nimbly supported
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a DGS for a sCO Re-compression Closed Brayton both temperatures of around 300°C, peripheral ve-
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Cycle (RCBC) pilot plant. locities in excess of 200m/s, and pressures greater
The conducted test campaign mirrored as close as than 200bar, but most importantly, the Gaspac
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possible the operational conditions in the compres- seal has been proven to withstand all these con-
sors and provided needed information and perfor- ditions at simultaneous ensuring an unpreceden-
mance results to close the gap between analytical ted and unique reliability in the market not at the
studies and real application testing, allowing to expense of emissions and consumption that were
improve knowledge and experience for both Com- have nevertheless proved predictable and further
pressor and DGS OEMs. reduced thanks to the new construction design.

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Impiantistica Italiana - Luglio-Agosto 2022 101