Advanced Technologies of Preventive …

1 Hitachi Review Vol. 51 (2002), No. 5 137 Advanced Technologies of Preventive maintenance forThermal Power PlantsOVERVIEW: Although thermal power generating facilities are aging, flexibleoperation in response to changes in the demand for electrical power isrequired. To extend the life and manage the maintenance of those facilities, Advanced Preventive maintenance technology is important. For that reason,Hitachi has been grappling with nondestructive inspection, life assessmenttechnology, rationalization technology for scheduled inspections of theboilers, steam turbines, gas turbines and other machinery used in thermalpower generation to strengthen Preventive maintenance and increase theefficiency of maintenance . Recently, we have been developing products andservices for Advanced support for maintenance and preservation throughthe use of IT (information technology) and network technology, going beyondwhat has previously been Shimomura, Dr.

2 IshitokuShigeo Sakurai, Dr. HiroseINTRODUCTIONIN recent years, startup and shutdown operations havebecome frequent in aging thermal power generationfacilities, and Preventive maintenance technology hassteadily been increasing in importance from theviewpoints of extending the scheduled inspectioninterval and strengthening the independent managementof facilities. Furthermore, concerning preservation ofthe global environment as well, there is also a strongdemand for the reduction of CO2 emissions throughimproved generation efficiency and fuel conversionin existing such circumstances, Hitachi is going beyondthe application of new technology that has beendeveloped for new power plants to old facilities, andhas taken up the challenge of developing our ownpreventive maintenance with these Advanced Technologies andproducts, Hitachi is making use of IT, which hasdeveloped rapidly in recent years, to provide globalservices that contribute to life-cycle cost minimizationfor power generation facilities (see Fig.)

3 1).Fig. 1 PreventiveMaintenanceSolutions forThermal PowerPlants Provided is makingfull use of IT toprovide the newestpreventivemaintenance systemsand services forthermal load dispatching officeHead officeThermal power plantsPower demand adjustmentPower companiesPower generationThermal power plantsPower generationPlant monitoring serviceRemote Monitoring CenterAnswer CenterHITACHIB oilerTurbineGeneratorControllerOrdinary householdsCALS: continuous acquisition and life-cycle supportLarge-demand customersCALS technology answering serviceInformation to customers (subscribers) via the InternetInternetAdvanced Technologies of Preventive maintenance for Thermal Power Plants 138 Here, we describe the latest technology for thepreventive maintenance of thermal power OF IT TO PREVENTIVEMAINTENANCE OF THERMAL POWERPLANTSH itachi is proceeding to add intelligence in a widerange of fields by making use of IT and the proprietaryknowledge we have accumulated in various industrialareas with the objective of being the customers BestSolutions Partner by offering new the field of Preventive maintenance for thermalpower plants, too.

4 We have taken up the challenge ofusing IT and network technology to provide servicesfor the support of Advanced maintenance andpreservation that go beyond what has been availableto the customer in the the increasingly severe demands on theoperation of aging thermal power plants, typified byextension of the period for scheduled inspections andDSS (daily start-up and shut-down) operations, thereis increasing need to know the quantitative state of thefacilities, such as by monitoring operation at times oftransition and knowing the deterioration state ofequipment, in addition to the regular monitoring ofoperation. There is also a demand for the provision ofperformance evaluation technology for life-cycle costminimization, as well as the provision of operationmethods that use such technology to optimizeefficiency and the provision of operation datamanagement services.

5 To meet that demand, Hitachiis developing services which make use of IT, such asplant monitoring services and engineering example of an engineering service, a means ofproviding information over the Internet is illustratedin Fig. 2. In that service, subscribing customers canget speedy answers to technical questions via theInternet by directly accessing the Answer Center WebSite set up by the Thermal Power PreventiveMaintenance Department, a process that previouslyrequired waiting for written responses. It is alsopossible to access information on the latest operationand maintenance technology and improvements in realtime. This service can be provided to overseascustomers as well as to domestic power MAINTENANCETECHNOLOGY FOR THERMAL POWERPLANTSIn an environment of deregulation, there has beenlittle progress in the construction of new thermal powergeneration.

6 Furthermore, load conditions have recentlybecome severe, including operation according tovarying load (middle load operation), etc., and thereis an accelerating trend of material damage. To copewith that problem, Hitachi is promoting thedevelopment and application of Preventive maintenancetechnology for boilers, steam turbines, gas turbines,and other core Technologies of thermal power plants,as described in the following maintenance Technology for BoilersApplication of the latest development technologyThe conventional techniques for nondestructiveinspection of boiler materials and parts include PT(liquid penetrant testing), MT (magnetic particletesting), and UT (ultrasonic testing), among types of inspection, however, have problemssuch as.

7 (1) difficulty of inspecting narrow gapped areas,(2) requiring a large amount of associated work, and(3) difficulty of lifetime diagnosis or can predictquantitative damage cope with these problems, Hitachi has beendeveloping various kinds of scheduled inspectionrationalization technology to achieve lower-cost,timely inspection by reducing the preparation workand to achieve fast, highly accurate inspection byemploying Advanced inspection equipment withoutdirect contact. The main diagnostic points anddiagnosis technology are shown in Fig. 3. Theserationalized Technologies are already being applied inactual these Technologies , ELFOSS UT (electronicfocus sector scan ultrasonic testing), which canFig. 2 Mechanism for Providing Technical Information via questions from customers can be answered quicklyand the latest information can be provided over the (contract holder)Hitachi Group Answer CenterInternet Rapid reply to technical questions Provision of the latest operations and maintenance technology Provision of information on improvementsHitachi Review Vol.

8 51 (2002), No. 5 139evaluate internal defects in the welds of main pipes, isdescribed below:ELFOSS UT can evaluate defects contained inwelds and in narrow nozzle stubs by electronicfocusing and sector scanning techniques. A majorfeature of this device is that the scanning range of theUT probe is smaller than that used in the conventionalUT method, so the defect size and location can bedetermined results of ELFOSS UT inspection of a plate(100-mm thick) butt weld that contains an artificialdefect are shown in Fig. 4. The defect detected by thenondestructive method matches well with the defectas confirmed by cross-section examination. With suchan excellent defect detection capability, this equipmentis being applied to precise inspection of importantareas, such as the welds of main inspection rationalization technologyThe various types of nondestructive inspectionequipment shown in Fig.

9 3 are all capable ofquantitative evaluation of defects, and can also becalled rationalized Technologies with respect toshortening inspection time for schedule addition to such higher performance of theinspection equipment itself, rationalization technologysuch as for shortening the preparation time forinspection is also example, in the furnace of coal-fired boilers,fused ash adheres to places such as the bends in theheat exchange pipes that are suspended from the topof the furnace. Such ash may grow to form hardclinkers. Because it is very dangerous if those clinkersfall inside the furnace, they should be removed beforeinstalling the scaffolding and performing the inspectionand repair work at the time of scheduled removal of the clinkers in this way requires muchtime and that reason, we turned attention to WJ (waterjet) technology, and developed a special nozzle thatproduces several times the force of the conventionalnozzle.

10 Using this nozzle reduces the time requiredfor clinker removal significantly, and the time fromthe shutdown of a plant to the beginning of inspectionand repair can be greatly maintenance Technology for SteamTurbinesLifetime diagnosis of steam turbinesFor high-temperature components of aging steamturbines, accurate Preventive maintenance andFig. 3 MainDiagnostic Pointsand hasdeveloped inspectionequipment that iscapable of non-destructive,quantitativeevaluation of all ofthe pressurecontainment parts ofthe 4 ELFOSS UT results of inspecting a sample butt weld that contains aninternal defect show that the defect size and location can bedetected pipesDrumCoolerHeaderHeat exchange tubesWater-wall tubesBurnerFuel pipeEMAT: electromagnetic acoustic transducer*.