hot gas expander replacement
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Enhanced Process EfficiencyHot gas expander replacement
With increasing operational problems and the declining reliability of a 30-year-old
expander, for which the OEM was no longer in a position to offer the necessary
technical support, the customer decided to have the work carried out by a qualified
third party. Following a competitive bid procedure, MAN PrimeServ was entrusted
with this demanding assignment.
Enhanced Process Efficiency Technical complexity and tight schedule
Project goals
Inordertokeepcostsaslowaspossiblebyeliminat-
ing costly alterations to pipework and foundations,
thenewunithad tobeadapted to theexistingpro-
cess and constructional infrastructure. Themachine
was required tobeupgraded to the latest technical
standards, with the focus on reliability in particular.
Process modifications performed by the operator
further required an increase in the unit thermal effi-
ciencytoallowtheretentionof theoriginal2,300kW
electricdrivemotor.Adeliveryperiod“nottoexceed
12months”withamaximumplantoutagetimeofsix
weekswasanabsoluterequirement.
The MAN PrimeServ solution
The original expander was a two-stage unit with a
separateaxialbearing.Thistypeofexpanderdesign
conceptwasnewtoMANPrimeServ.
Already the first preliminary investigations showed
thatitwouldbedifficulttomodifytheexistingcasing
toaccommodatethenewrotatingandstatorcompo-
nents.Thetimerequiredforsuchmodificationswould
alsofarexceedthespecifiedoutagetime.Thechosen
solution was, therefore, based on a new, cast cas-
ing.Thecasinginterfaceswiththeprocessequipment
and the foundation had to remain the same, which
presented a major design challenge. The original
two-stagedesignwith a separate axial bearingwas
retained,basedonasolidforgedrotorwithfour-seg-
mentradialbearings.
Additionallymoderninstrumentationforbearingtem-
perature,rotorvibrationandspeedmonitoringaswell
as online power measurement was to be installed.
The unit instrument rack was also mounted on the
base frame. In order to demonstrate the increased
efficiency, a torque meter was integrated into the
systembetween thenewexpanderand theexisting
aircompressor.
Project results and customer benefit
Customer'sspecificationsposedamajorengineering
challenge,whichhadtobesolvedwithinanextremely
tighttimeframe.Thetwo-stageconcept,usingstandard
aerodynamic technology (blading and flow channels)
wascomplexwithcorrespondinglyhigh risk factors,
especially considering the contractual efficiency
guarantees.Amajor factor inmaintaining thespeci-
fiedplantdowntimewasMANPrimeServ’s ability to
carry out high-speed balancing and mechanical
testing of the complete unit at the company-owned
facilitiespriortodelivery.Despitethetechnicalcom-
plexityandtheextremelytightschedule,thenewunit
was delivered on time, installed and commissioned
withinthespecifiedsix-weekplantdowntime.
The installationof thenewexpander,combinedwith
othersystemandprocessmodificationsnotincluded
intheMANPrimeServscopeofsupply,hasresulted
in major operational and economic benefits for the
user.Thecustomernowoperatesamodern,state-of-
the-artmachinewithsignificantly improvedefficiency
andhighreliability.Thecarefullyplannedretentionof
the interfaces with the existing process equipment
allowedallplantmodificationstobecarriedoutcost-
effectivelyandwithanabsoluteminimumofproduc-
tiondowntime.
New expander in operation
Original expander prior to the rebuild State-of-the-art production of expander blades
Works assembly of the new expander with the cast lower half casing and the newly designed two-stage expander rotor with separate axial bearing
Fully assembled new expander package with instrument rack, ready for dispatch
Technical Data
Inletpressure bar 3.47
Inlettemperature °C 460
Dischargepressure bar 1.02
Massflow kg/h 48,690
Gascomposition 92.7%N2,7.2%O2,0.05%SO2,tracesH2O,SO3,H2SO4
Withtheselectedbladestagedesignthenetpowerattheguaranteepointis2,300kWwithanisentropicefficiencyof79.9%.Thedischargetemperatureis298°C.
x /m
100,000
150,000
200,000
250,000
300,000
350,000
0 0.025 0.050 0.075 0.100 0.125 0.150 0.175
StaticpressurePs/Pa
Calculation of static pressure at stator and rotor blades
MAN Diesel & Turbo Schweiz
8005Zurich,Switzerland
Phone+41442782211
Fax +41442782261
mtprimeserv@man.eu
www.mandieselturbo.com
24/7Hotline:+492086929000
MANPrimeServ–aservicebrandofMANDiesel&Turbo
Alldataprovidedinthisdocum
entisnon-binding.Thisdataservesinformationalpurposesonlyandisespeciallynotguaranteedinanyw
ay.Dependingonthesubsequentspecificindividual
projects,therelevantdatamaybesubjecttochangesandw
illbeassessedanddeterminedindividuallyforeachproject.Thisw
illdependontheparticularcharacteristicsofeachindividual
project,especiallyspecificsiteandoperationalconditions·Copyright©
MANDiesel&
Turbo·D02081037E
NPrintedinG
ermanyG
MC-OBH06100.5
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