hydrocarbonengeneering 4 2007 intelligent condition monitoring

7/29/2019 HydrocarbonEngeneering 4 2007 Intelligent Condition Monitoring

1/5

IsW. ALICENT CONDITION MONITJRINGMatthias Sauter, LEWA GmbH, Germany, presents a new condition monitoring systerrthat provic'nc DIF+ oyrators witL 3 cl--r incimLLof pu-- nr--=+i-- ~ a - n e t s.


2/5

Figure 3. Accurate early error detection of the LEWA CMS.

Figure 4. Nuid valve leakage can be detected via impact sound.

Recognising error conditionsWith the increase of plant automation and maintenancepersonnel reductions, plant engineers will increasingly relyon automated equipment condition monitoring, especiallywhen handling hazardous fluids. International occupationaland environmental protection regulations are becoming morestringent and will be mandatory in the near future.

Financial considerations are always an important actor inthe selection and evaluation process. It is estimated that 70%of the pump operating costs are a result of expenses incurredduring unplanned downtimes. The initial cost of a pump can beinsignificant when compared with the cost of lost productiondue to pump failure. The output of an oil and gas industry plantis often valued at millions per day, making availability of centralcomponents such as pumps highly critical. This is one of thereasons why operators are recognising that pumps equippedwith a condition monitoring system are a possible key topreventing unplanned plant shutdown.

Pump maintenance is required at some point, but if plantoperators (with the aid of continuous monitoring)are able torecognise maintenance requirements at anearly stage and, ifnecessary, delay the maintenance process, they can continueproduction or longer and reduce the downtime by having onlyrequired parts available and not having to inspect all partsfor wear or damage, significantly ncreasing the plant's costeffectiveness.

In general, all the providers of monitoring and early errordetection systems have a similar problem when marketing theirproduct: they always mention the qualitative higher equipmentavailability and short period to amortise the monitoringequipment cost, but fail to provide quantitative evidence. Nopump manufacturer could relate the exact downtime costs

-- elay= outputs- Signals

Figure 5.LEWA CMS detects deviations from the reference, prime condition and thus reduces production downtimes. Moreover; this type of systemreduces the cost of mutine maintenance associated with extended service life and raises safety levels.

92 HYDROCARBONENGINEERING April2007


3/5

I Our Series 250 valves keep everythingunder control thanks to their modular designwith sizes up to DN 500, pressure-balanced,multi-staged plugs and noise-reducing rims.The wide range of valve materials mean evencorrosiveand erosive mediacan be controlledsafely and reliably at high pressure dropsand extreme operating temperatures.Dimensionsand flanges conform to the mostimportant industrial standards such asANSI,DIN, JIS, allowing SAMSON's control valvesto be used in applicationsworldwide.

SAMSONAG .MESS-UNDREGELTECHNKWeismiillarsde3 .60314Frankfurtam Main .GermanyPhone: +49694009-0.Fax:+49694009-1507E-mail:[email protected]:hiip://w.samm.de

to acustomer. Plantoperatorsare required to consider theirown financial situation andcan estimate,dependingontheprocess,what loss of production can cost. Fromthis estimatea plant operator can approximatethat asystem, esignedto prevent unplanneddowntimes,will pay for itself inashortspace of time.

Forexample, inNotwaythe malfunctioningof a COprocess pump, usedto pumpmorethan 90t of liquidcarbondioxide perhour back intodeeper rock layersduring liquidgasproduction, resutted indowntimecostsof approximatelyUS$6000/hr,ust intaxes. This occurred because Norway,which hasratified heKyoto Protocol, raisesa penalty taxif (3% is emitted intothe atmosphere.This exampleshowsthat incertain criticalsituations the amortisationon high costmonitoringsolutionstakes lessthan afew hours.CMS: the eyes and ears of theoperatorIntelligent conditionmonitoring systems (CMS)enableoperators to monitorcurrent operating conditions. Theseoperatingconditionsare then compared with the initiallyprogrammed'prime' conditions, which are those determinedwhen the pump is new. If the twoconditions indicateadeviation trend, it ispossible to conclude the future operatingconditionof a machineor plant. Appropriate physical valuesare additionally recordedand interpreted taking the currentoperatingconditions into consideration.

The most probablefault sourcesof processdiaphragmpumpsare hetypical wear parts(Figure2): the fluid valvesonthe suctionand pressureside, thedynamic seals (e.g.pistonseal) inthe hydraulicdrive, and the diaphragm. Thesecomponentsaremonitored continuously bythe CMS.FluidvalvesDependingonthe fluid beingpumpedandthe operatingcondiiions, thefluid valves aresubject to varying degreesofwear. Inthecourse of time, backflowwill occur, reducingpumpefficiency. Furtherwear will result inbasic fluid valvemalfunction; for example, if a valve isunable to open andclose correctly, flow reduction or stoppage will result.Malfunction can also occur without wear if, for example,sediment suspension caused by insufficientflow rate restrictsvalve movement.

Inorder to ascertain the conditionof the pump head,the impactsound of the fluid valves and the pressure in thehydraulic chamber is measured and evaluated. The pressuresignal curve graphically displays the pump's hydraulicprofileand providesanexperienced engineer with valuableinformationontheconditionof the pumphead. Ifa fluidvalve leaks, the compression and decompressionspeedchanges. However,a significant change inthe pressurecurve only occurs after a leakageof approximately 10%, i.e.when the amount of fluid backflow reduces pumpefficiencyby 10%.The impact sound signal is moresensitive:Measurementof the impact sound events in the pumphead can becomparedwith thework carried out byanexperienced pumpengineer who is able to detect noiseatthe pump head via a stethoscope. Leakage ratesas low as1% cansignificantly change the impactsound signals, whichare evaluated with the aid of a computer (Figure4). At higherpressure, thesignal sensitivity is greater and consequentlythe detectable leakage rate issmaller.The concept of theLEWA CMS is based onasingle, centrally mountedimpactsoundsensor. The central location of the impact soundsensor enables identification of suction and dischargevalve


4/5

NEW NAME.SAME COMP VY. Found events assisting in prompt identificationof potential

problems.Hydraulic leakageHydraulic leakage between the pressurised hydraulic chamberand the hydraulic reservoir is continuously checked, e.g. viathe pistonseal. If hydraulic leakageoccurs, thediaphragmreaches its rear contact surface earlier than in the primecondition. Therefore, the time for the leakageas well as theduration of thecharacteristic pressure loss at theend of thesuction stroke is extended. The lengthof this time window canbeevaluated with theaid of a computer.DiaphragmThe diaphragm isalso a wear part and has to be replaced atregular intervals. Moderndiaphragm pumps are equippedwith a sandwich diaphragm with two diaphragm layers. Ifoneof thediaphragms isworn anddamaged, the pump remainshermetically sealed and can continueto be operatedfora limited period. Possible damageto a diaphragm layer isdisplayed by increasedpressure inthediaphragm intermediatespace. This increasedpressure s sensed by a pressureswitchor pressure ransmitter and signalled to the LEWACMSPrime condition programmingonsite In 2006, Onyx IndustrialServices, Inc.The LEWA CMS (Figure 5) monitors the operating parameterswith the following sensors: becameVeolia ES IndustrialServices, Inc.An impact sound sensor, mounted to the front of the

pump head.A pressuresensor which records the pressure in thehydraulic chamber.

Veolia ES lndustrial Services i s a fu l l service, turn-keyprovider o f industr ial cleaning, mechanical andmaintenance services, and environmental wastemanagement solutions. Veolia ES Special Servicesgroup delivers emergency response, high hazard

An inductive position sensor as the trigger signal at thecrank mechanism.A pressureswitch for diaphragm monitoring.The numerouspossibleoperatingconditions of process

diaphragm pumps (varyingfluids, delivery pressuresand flowrates) result invarious physical phenomenaduringoperation.

Therefore,the system concept stipulatesthat during initialstartup of the new or overhauled pumpa 'prime condition'has to be programmedand saved. Duringsubsequentoperation, thecurrent condition is compared with this 'primecondition'.The operator sets system sensitivity, i.e. whichlevel of deviation results ina warning or error message.Thesystem recognises three operatingconditions: 'Operation OK','Warning' and 'Error'.

response, in land & offshore mar ine d iv ing and ROVservices, abatement an d remediat ion services. Wepride ourselves on being a safety leader in the industrywhere "our values drive our words and our actions'.'Veolia ES lndustr ial Services has 65 office locationsthroughout the US and Canada an d 4,200 mployeeswork ing hard t o provide effective, cost-savingsolutions for ou r customers.

CommunicationThe newly developed PCconnection makes it possible tocommunicate the monitoringsystem parameters to a centralprocessor maintenancecontrolsystem. An explosion proofversion isalso available for application in hazardousareas.Datatransfer via intranet or internetof up to 32 LEWA CMSdevices can beconnected to a central PCvia an RS485orEthernet interface. Inaddition wireless remotedata canbetransferred via GPRS,GSM or UMTSstandards (Figure 6).

Communication between the PCand the LEWA CMSoccurs viaan XML based bus protocol. Control of the CMSdevice iscarriedout at the PC bythe CMS controlprogram.Remotecontrol occurs via aneasy to operate interface hatprovidesall thefunctions of the LEWA CMSmembranekeypad. The remote control allows the user to view, online,any error messages aswell asthe current measured pressureand impact sound.

Visit www.VeoliaES.com t o learn ab out our serviceor t o contact us for more information.

Turning waste into a resourcewww.VeoliaE5.com

QVEOLIAENVIRONMENTALSERVICES


5/5

lnternet;PAlarm mail

r r '-4 b..*. '-..

Figure 6. PossibleCMS connections.

Figure 7. TheXML compatibledata format makes if possible to openmeasuringdata files that have been downloaded from CMS direct&withMSExcel at a PC. Noadditionalor specialsoftware formeasuredvalueanabis is required,

TheXML compatible data format makes it possible oopen downloaded measuringdata filesdirectlywith MSExcelat a PC. Noadditional, specialsoftware for measuredvalueanalysisis required (Figure7).An Excelmacro isprovidedto ensureuser friendlyoperation. The macrodisplaysthe measureddata files in aconcisemanneron varioussheetsenablingthe operator toassess theconditionof a machineat a glance.

A userwho requiresmore detailscanview the pump'sindicatordiagramon urther Excelsheets.The indicatordiagram iseffectively the pump'selectrocardiogram(ECG).Just as a doctor usesanECGto determinethe conditionof and possiblerisks to a patient's heart, an experiencedortrained engineercan, by meansof the indicatordiagram,judge theconditionof the pumps.

Selection of possible CMSconnections to higher-level control units.

The measured data records can be emailed andenabling remote diagnosis at the LEWA factory or any otherexperienced facility. If changes occur at a pump, a LEWAspecialist can be contacted at any time via lnternet to providea qualified analysis.ConclusionThe LEWACMS for processdiaphragmpumpsenables themonitoringof potentialpumpfaults. Byprogressing rom a'preventive' (fixedservice intervals) o a 'conditionoriented' maintenanceprocedure t is possible to cutmaintenancecostswithout increasingthe riskof unplanneddowntimes.This results in importantadvantagesfor theoperator:

Production ossesare reduced,since downtimescan bescheduled and replacementparts madeavailable.Potential failures are recognisedat an early stage,allowing plannedaction insteadof unplannedreaction.Parts only have to be replacedwhen their conditiondemands it.Oriented maintenancedue to clear and accurateconditiondiagnoses.

' Cooperation with the pump supplier's service departmentis optimised.The LEWACMS is a measuringanddiagnosistool which

enables theacquisitionof data relating to the operationalquality of the plant. Dataand evaluationscanbe transferreddirectly to a PC andsubsequentlymadeavailableto a globalaudiencevia lntranetor Internet.

A major differenceto other monitoringsystems is that theLEWACMSdoes not report after a damagingevent, but useserror messagesto warn operators inadvanceof potentialwear. This provenfield technologyconsiderably reducesproductiondowntimes. 3

hydrocarbonengeneering 4 2007 intelligent condition monitoring

Documents