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Tips for the operator

Slow steaming and turbocharger cut-outWhen vessels with 2-stroke engines are run in “slow steaming”mode, turbocharger cut-outs are a very viable option for furtheroptimizing fuel consumption and improving part load operation.

Text: Rolf Baechi

One of the major challengesglobal shipping has to con-tend with is the price of fuel,which has increased by a

factor of 7 in recent years. The mosteffective option for reducing fuel costs isto reduce vessel speed and subsequentlyrun the main engine at reduced loads fora longer period of time. Slowing thespeed of, for example, a large containervessel by 20 % can result in a fuel savingof up to 50 %. Many shipowners aretherefore operating their vessels in thisso-called “slow steaming” mode andthereby reducing their fuel costs consid-erably.

There is an additional method thatcan be used during slow steaming to further optimize fuel consumption andimprove part load operation of a 2-strokeengine with two or more turbochargers,and that is to “cut out” one of the turbo -chargers. Many shipowners have eitheralready installed such systems or are inthe process of doing so for the additionalbenefits and further cost saving thisoffers.

Exhaust gas receiver

Main engine

Shaft motorgenerator

Turbochargers

Exhaust gasboiler

Steam for heating services

Example of a cut-out arrangement (principle drawing).

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Tips for the operator

Basically, two methods can be usedfor ABB turbocharger cut-outs:1. The so-called “fixed cut-out”, in which

the rotating and bearing parts areremoved and the gas, air and oil linesare disconnected where applicable.

2. The so-called “flexible cut-out”. Here,no parts are removed from the turbo -charger and flexible valves areinstalled in the gas and air lines. Asthe oil line to the turbocharger is notdisconnected, external sealing air isneeded, making modifications neces-sary.

Note: To prevent costly damage, it isstrongly recommended that the fol-lowing turbocharger work is carriedout exclusively by an authorized ABBTurbocharging Service Station.– Fixed cut-out: Removal of rotating

and bearing parts from ABB turbo -chargers, as well as their proper con-servation and safe storage.

– Flexible cut-out: Modification of theaffected turbo charger, for examplerequiring external sealing air withsealing kits.

Recommended procedurefor customers

1. Contact the engine builder:– Ask for detailed instructions on

“slow steaming” and turbochargercut-out operation for your particularengine and turbocharger. Theseshould be strictly adhered to.

– Ask which one of the 2, 3 or 4 mainengine turbochargers should be cutout.

– Consider also the emissionsrequirements of the InternationalMarine Organisation (IMO), includ-ing the above mentioned EIAPPCertificate.

2. Contact your local ABB TurbochargingService Station:– Ask for a quote, supplying the ves-

sel’s name and turbocharger serialnumber (e.g. HT number).

– Fix the time, date and place whereABB is to perform its part of thecut-out procedure for the mainengine turbocharger, as recom-mended by the engine builder.

In either case, the turbocharger cut-out restricts engine operation at higherloads, requiring engine modifications. Inaddition, the Engine International Air Pol-lution Prevention (EIAPP) Certificate forIMO engines needs to be updated; here,the shipowner has to work closely withthe engine builder and the ClassificationSociety.

ABB does not design or supply blank-ing devices for permanent use. Exhaustgas and charge air receivers are pressur-ized reservoirs and as such are subjectto specific regulations. Kindly contactthe engine builder for advice in connec-tion with this.

Please contact anauthorized ABB Turbo-charging Service Stationwhenever consideringturbocharger cut-outs.

Example of an upgrade kit for the sealing air supply.

Rolf BaechiClaims ManagerTechnical Service