PEi November 2004

EquipmentRoundup

Water success at Rijnmond energy centerRaw water with high and variableamounts of total dissolved solids, totalsuspended solids and periodic oil con-tamination, were just some of thechallenges facing engineers as theydesigned the water treatment systemat Rijnmond Energy Center in theNetherlands. Meeting the challengeshead on, the team of Bechtel-Enka andUSFilter designed and constructed asuccessful treatment plant that hasbeen producing high quality watersince November 2003.

The 1288 m3/h system suppliesclarified cooling tower water and highpurity boiler feed water at the new gasfired plant. The first plant built in theNetherlands by an independent powerproducer, Rijnmond will be one of themost efficient power facilities inEurope.

The raw water supply for the plantcomes from a canal on the tidal MaasRiver. The total dissolved solids (TDS)level in the canal can fluctuate widelydepending on the season, the tidesfrom the Rhine, and the amount ofwater from the North Sea that ends upin the Maas River. In fact, the conduc-tivity of the water ranges between3000 and 10 000 mS/cm and changesbetween these extremes within a mat-ter of days. The raw water intake is 20 m from a petroleum unloading pierin the Shell Oil Refinery. The ships and barges pulling in and out of thedock to support the unloading, stir upthe bottom of the river.

“These conditions created anincredible challenge to us in designingthe pretreatment portion of the sys-tem,” said Bill Willersdorf, director ofcorporate projects at USFilter in theUS.

Four packaged steel clarifier sys-tems were coupled together to handlea substantial flow rate, 1000 m3/h, tofeed the cooling tower for the 790 MWcombined cycle power plant.

Meeting the challenge The raw water treatment includesintake screening and pretreatmentconsisting of the four clarifiers and

particulate and oil-absorbing cartridgefilters. The high purity water treatmentportion of the system consists of dualcartridge filters, two trains of double-pass reverse osmosis (RO) systemsand two CDI-LX continuous elec-trodeionization systems with IP-LXmodules from Ionpure Technologies.Other equipment includes a pre-coat condensate polishing system,

chemical feed systems, solids dewa-tering systems, and associatedpumps, tanks and controllers.

The intake screening system fromUSFilter Envirex Products removesrubbish and debris such as grass,seaweed and plastic bags from 27 m3/min of brackish water from thecanal.

Tom Patterson, Rijnmond Energy

Center project manager at Bechtel-Enka said, “USFilter combined a lot ofthe technologies it offers and coordi-nated with a number of suppliers inNorth America and Europe. Its successin this effort has contributed to theoverall success of the Rijnmondplant.”

Besides handling the difficult intakewater, the treatment plant also had to

CDI system skid

n Reader Reply No 50 n

EquipmentRoundup

be designed with environmental con-siderations in mind. Due diligence wasfollowed to protect the environment.In Europe, companies are self-report-ing, which means that they, ratherthan regulatory agencies, are respon-sible for ensuring that the environ-mental protections are in place.

Another design consideration wasthe fact that the power plant had toexport steam to Shell’s Pernis refin-ery, located next door. The treatment

system had to meet normal plantwater needs for the majority of theyear and then ramp up production forsteam host mode. The system isdesigned to operate as two indepen-dent high purity trains, with one trainremaining on standby until needed.

The CDI system skids at Rijnmondare high-flow, multiple-module sys-tems consisting of 25 IP-LX modulesper skid with a capacity of 85 m3/heach.

Exceeding specificationsThe water treatment plant was startedup in various stages beginning inNovember 2003, with the processcompleted in April 2004. Intergen, aShell-Bechtel venture, declared com-mercial operation of the plant on June20, 2004.

Water quality from the high purityRO/CDI system is exceptional, withconductivity averaging less than 0.07mS/cm. The sodium concentration in

the RO/CDI product water is about 5 parts per billion (ppb) and the silicaconcentration is below 3 ppb. Thesystem’s performance significantlyexceeds the water quality specifica-tions, which require conductivity ofless than 0.10 mS/cm and sodiumand silica concentrations of less than10 ppb.

Reader Reply Number 201

Table 1. Water quality specifications and product waterquality November 2003 - May 2004

Parameter Range Specification

Conductivity (µS/cm)Raw Water 2000 to 10 000 8580 max1st Pass RO Product Water 30 to 120 NA2nd Pass RO Product Water 3.5 to 4.5 NACDI-LX Product Water 0.06 to 0.09 < 0.010

Silica (ppm)Raw Water 5 to 12* 23 maxCDI-LX Product Water 0.001 to 0.005 < 0.010

Sodium (ppm)Raw Water 38 to 590* 1770 maxCDI-LX Product Water 0.003 to 0.007 < 0.010

*Range in table was provided in the contract specifications.

The location of the energy centre presented many factors for consideration