VAHTERUS NEWS 1/2013<strong>WIDE</strong> <strong>OPERATION</strong> <strong>RANGE</strong><strong>SETTLED</strong> <strong>THE</strong> <strong>DECISION</strong>ON STEAM GENERATORACQUISITIONA few years back Pori Energia Oy, a companyresponsible for the energy supply in thecity of Pori and its surroundings in westernFinland, was facing a decision. A thermalpower station supplying process steam foran industry client was nearing its end, and thestation’s oil based steam production would bereplaced with steam produced with renewableenergy, mainly with wood chips, in a powerplant 4,7 kilometers away.What Pori Energia Oy needed was Europe’slongest continuous vacuum steam pipe connectedto a transforming station, where the processsteam is made with power plant steam. Thetwo-year planning and construction project wascompleted in December 2012 and Pori EnergiaOy started supplying steam for Boliden Harjavalta’scopper electrolysis in the beginning of 2013.After long assessments, it was a plate and shellheat exchanger and more specifically <strong>Vahterus</strong>’steam generator that was chosen for the process.After the first weeks’ of production, constructionengineer Ari Aittamäki from Pori Energia Oy is satisfiedwith the results.-The minimum load has been reached, Aittamäkiexplains with content. – And even thoughwe had agreed on a minimum capacity of 30%from the nominal capacity, we have reached evenlower figures. All in all, the heat exchanger’s wideoperation range and adjustment possibilities areof great importance to us, says Aittamäki. PoriEnergia Oy has yet to try out the other end of theuse area, the maximum load.-We are trying to figure out where we could runthe steam at high load for a short time. This waywe would see the steam generators maximum,explains Aittamäki.The steam leaves the Aittaluoto power plantat +205C. At the transforming station, the heatis transferred to the industrial plant’s pipelines,where the temperature and pressure are lower.As the main component, <strong>Vahterus</strong> supplied PoriEnergia with a 13 MW steam generator, a condensatereceiver and a condenser pre-heater. For anindustry traditionally utilizing mainly shell andtube heat exchangers, the choice required a lotof thought.-We made a specified list of the pros and consand compared the findings, explains Aittamäki.One of the most important criteria was the wideoperation range of the <strong>Vahterus</strong>’ plate and shellheat exchanger. – Adjustability and the minimumload were the main reasons why we chose theplate heat exchanger and why we were confidentabout its functionability.-Of course the choice also had to be secure,long lasting and as maintenance free as possible.People-made machinery have the tendency toencounter issues sooner or later – <strong>Vahterus</strong> alsooffers maintenance service and many things canbe fixed within a couple of days. The lifecycles of<strong>Vahterus</strong>’ units seem credible, summarizes Aittamäki.New method for repairing andcleansing <strong>Vahterus</strong>’ fully weldedplate heat exchangers<strong>Vahterus</strong> has developed a new methodfor repairing fully welded plate heat exchangers.The plates of the heat exchangercan now be repaired withouthaving to change the entire plate pack.The method, which has now also beensuccessfully tested, is similar to the onethat has previously been used for shelland tube heat exchangers. The repair offully welded plate & shell heat exchangerscan be done by <strong>Vahterus</strong>’ personnelbut later on also by the end-user with thehelp of <strong>Vahterus</strong>’ instructions.By enhancing the possibilities for repair,also the cleansing method of theplate pack has been further developed.More specifically, <strong>Vahterus</strong> has developeda structure that allows the end-user to carryoutmechanical cleansing easier thanbefore. Overall, new heat exchangers cannow be designed so that if needed, bothrepairing and cleansing can be done.In most cases, repairing and cleansingbecome timely when circulating fluidscontain a lot of impurities or if it is suspectedthat the process may break theheat exchanger’s heat exchange surface.People at <strong>Vahterus</strong> are happy to providemore information on the new plate heatexchanger structure allowing repairingand cleansing.When choices were being made, the lowerprice of the investment of course also had a roleto play. The steam generator had to be fitted inthe old thermal power center, in a space reservedfor the boiler. A compact unit fit the purpose well.-The fact that the installation is lighter andneeds less space, made the decision easier.Expanding the space would not have been possible.At the start of the project Pori Energia also hadto think about the possibility of fouling, whichcould be caused by possible impurities in the circulatingfluids. Maintenance solutions were foundtogether with <strong>Vahterus</strong>.-The old boilers will be kept as reserve. Whenheat exchange solutions are made for years ahead,a lot of things can happen in the long run. At alltimes, we still need to ensure supplies to our customers,says Aittamäki.-Our assumption and wish is that the newinstallation provides us with a long-term solution,functioning for the first 30 years without anyfurther actions.With the experience of a 100-year-old energyproducer, Pori Energia Oy produces electricity, districtheat and process steam for the Pori region. Inaddition to Boliden Harjavalta, Pori Energia suppliesprocess steam to UPM’s Seiku mill and Corenso’scartong production from its Aittaluoto power plantin the center of Pori city. In the north of the city,Pori Energia has a joint power plant with localindustry. From the plant, electricity and steam aresupplied to Sachtleben Pigments Oy.Around ten similar steam applicationsalready in useTo date, <strong>Vahterus</strong> has supplied its customersmore than ten similar steam generators that functionby the steam-to-steam principle.According to <strong>Vahterus</strong>’ Key Account ManagerValtteri Haavisto, the applications have workedexceptionally well. For the units supplied to PoriEnergia, innovative product development at<strong>Vahterus</strong> was done according to the customer’sneeds. These developments will also be of use toother customers.-We cleared out the functions and made theunits smaller. Especially the condensate’s preheatersare now very functional and compact,says Haavisto. Moreover, during the project, newsolutions to tackle the customer’s challenges withcontamination and repairability, were developed.10
VAHTERUS NEWS 1/2013Ari AittamäkiPori EnergiaThe steam generator had to be fittedin the old thermal power center, in aspace reserved for the boiler.The compact <strong>Vahterus</strong> unit fit thepurpose well.11
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