SULZER TECHNICAL REVIEW 2/2002 74058

PETER A. BLOKJORIS RINGELBERG

SULZER TURBO-MACHINERY SERVICES

Since 1995, Sulzer Repco B.V. (a Sulzer Turbo-machinery Services company) is responsible forthe maintenance of all production-critical rotatingequipment of a major German fertilizer producer.Equipment upgrades and spare parts manu-facturing are included in the activities. At present,the relationship is formatted around a two-yearrenewable unit rate contract and has proven to bebeneficial for both parties.

In the midst of the nineteennineties, the operators of a

German fertilizer plant faced ma-jor problems in maintenance plan-ning and execution to their pro-duction-critical rotating equip-ment. Co-ordination and interfac-ing between the different OEMs,service companies and the in-house technical department wasfar from optimal. It was decided tooutsource maintenance responsi-bility to one company. Mainte-nance planning was kept in-house,as well as the day-to-day activities.

The target of the complete exercisewas to reduce the amount of trans-actional activities and to create asituation in which there was a sin-gle point of contact with respect torotating equipment maintenancefor the operator.

Maintenance Contract afterSuccessful TurnaroundAs a first step to a more formal re-lationship, it was understood thatexperience and confidence in aworking relationship and a trustbetween customer and Sulzer Rep-

Maintenance Contractat Fertilizer Plant

8 SULZER TECHNICAL REVIEW 2/2002

1 This air com-pressor train is sit-uated in a German

fertilizer plantwhere Sulzer Repco

is responsible forthe maintenance of

production-criticalrotating equipment.

2 Detail of the35-MW steam

turbine rotordriving a syn-

these gas com-pressor train.

co was eminent. As a prelude tothe contract, in 1995 a completeturnaround was awarded to Sulz-er Repco. This turnaround met thecustomer’s expectations. Furtherdevelopment of the relationshipwas a logical next step. After ex-tensive discussions with the cus-tomer, it was agreed that a contractwith fixed prices for predefinedactivities (unit rates) was appro-priate. Benefits for the customer ofthe selected format were increasedturnaround efficiency and pre-dictable costs. Based on all equip-ment manuals and a plant survey,Sulzer Repco built up all workscopes and prices. As part of thecontract, Sulzer Repco establishedmaintenance records of the equip-ment in order to chart the mainte-nance history and use this infor-mation to optimize future mainte-nance activities. The unit ratescontract for the first two-year peri-od was awarded in 1998.The production facility consists oftwo plants with identical equip-ment. In both plants the equip-ment covered by the unit ratecontract is one 13-MW steam-tur-bine-driven air compressor train(Fig. 1), one 13-MW steam-turbine-driven ammonia compressor trainand one 35-MW steam-turbine-driven synthese gas compressor

train (Fig. 2). For the two plantsone complete set of spare rotors isavailable. Plant shutdowns arescheduled every two years in away that at least 50% of the pro-duction capacity can be main-tained.

Tight Timeframe MetStarting 1995, every year – in closeco-operation with the customer –Sulzer Repco performed all sched-uled maintenance to the equip-ment covered by this unit ratescontract. Due to the tight time-frame activity planning, prepara-tion and execution are always con-sidered to be critical.The 2001 turnaround was plannedfor a six-week period and coveredamongst others a complete shopoverhaul for the two 13-MW steamturbines in the Netherlands(Fig. 3). This included renewal of

all labyrinths and the replacementof the last four stages of the sta-tionary blades as well as an on-siteoverhaul to the ammonia com-pressors including a rotor changeand a dry-gas seal renewal. As partof the rotor change, on one rotortwo wheels had to be repositioned.The turnaround also included abearing inspection to the 35-MWsteam turbine. It appeared that theaxial travel was out of its limits.After opening up the turbine, adamaged stuffing box was located.Within the given 6-week time-frame, a new stuffing box had tobe manufactured and installed.Furthermore, the turbine laby-rinths were renewed. At comple-tion of the overhaul, the plantcould be started without prob-lems.

Several Upgrades ImplementedParallel to the normal maintenanceactivities, upgrades in order to re-alize increased equipment efficien-cy or higher production output arewithin the scope of the contract.During the course of the contract,Sulzer Repco successfully realizedseveral upgrades to the plantequipment.The first upgrade was implement-ed on the main air compressor. Ademand for higher production re-sulted in an effort to increase the

SULZER TECHNICAL REVIEW 2/2002 9

3 After a complete shop overhaul,this 13-MW steam turbine is assembled and final checked.

4 In co-operation with SulzerHickham, Sulzer Repco manu-

factured and installed new weld-ed impellers to this high-pressure

synthese gas compressor.

CONTACTSulzer Repco B.V.Joris RingelbergMoezelweg 190NL-3198 LS Europoort Rt.The NetherlandsPhone +31 (0)181-282 052Fax +31 (0)181-282 002E-mail joris.ringelberg@sulzer.com

output of this compressor. Reduc-tion of the relatively high sealingclearances increased the through-put of this machine. Abradableseals with a reduced clearancewere installed. The result was a9.8% increase of efficiency. Oneyear later, this upgrade was imple-mented on the second plant aswell.The improved output of the aircompressor and, again, a demandfor more production made the sec-ond upgrade, to the steam turbine,necessary. Adjusting the steam

stalled during the scheduled main-tenance (Fig. 4). This process hadto be speeded up after one of theold impellers exploded during op-eration and caused a crash of thewhole synthese gas train. The ro-tors with the new welded im-pellers provide the expected per-formance characteristics.

Added Value to the Customer’sBusinessOver the last six years, Sulzer Rep-co invested in the relationshipwith the customer. The frameworkof this unit rates contract providesclear advantages such as transpar-ent cost calculations, predictablemaintenance budgets, shortenedoverhaul times and less transac-tional activities.Given the fact that plant availabil-ity for production as well as theproduction capacity itself have in-creased and maintenance activitiesalways have been performed inline with the customers’ expecta-tions, this unit rate contract hasproven to add value to the cus-tomer’s business.

turbines’ condensing point, thereplacement of the last four stagesof stationary blades and the in-stallation of oversized labyrinthsbrought the required result.A third upgrade was implementedon the barrel type synthese gascompressors. In the original de-sign, these compressors wereequipped with riveted impellers.Inspection revealed that these im-pellers showed aging marks. To-gether with sister company SulzerHickham, La Porte, Texas, newwelded impellers were reverse-engineered, manufactured and in-