Lanxess, a leading specialty chemicals company, focused on cost-efficient, tailor-made solutions for water treatment in power plants at the recently held annual “Chemistry in Power Plants” conference of VGB PowerTech in Koblenz city in Germany.

The company said it offers ion exchange resins and membrane elements for reverse osmosis (RO) from its own production facilities.

“An intelligent combination of these two technologies offers powerful solutions. Our longstanding experience gathered from numerous reference projects with our premium products from the Lewatit and Lewabrane series is the key to success. Our customers benefit from this whenever we deal with cooling water and water-steam cycles,” explained Jean-Marc Vesselle, head of the Liquid Purification Technologies (LPT) business unit of Lanxess.

ENERGY EFFICIENCY IS THE KEY

The new membrane elements of the Lewabrane RO ULP (Reverse Osmosis - Ultra Low Pressure) series was the highlight at the Lanxess booth in Koblenz. They are designed for an operating pressure of 7.6 bar. Compared with standard elements, a 40 per cent lower operating pressure is being applied, which results in significantly lower energy and thus lower operating costs. “The membrane with high water permeability and resulting high flow rates that we offer with Lewabrane RO ULP also makes an effective contribution to reducing the investment costs for water treatment,” stated Alexander Scheffler, who is responsible for the LPT membrane business at Lanxess.

Lanxess: tailoring its solutions

In addition, the ULP membrane is characterised by the highest hydrophilic surface of all Lewabrane types. This hydrophilicity contributes to the formation of a thin, protective water film on the membrane surface. As a result, the adsorption of organic substances to the membrane – that is, organic fouling – is reduced, the company said.

In addition, the ASD feed spacers used in the membrane elements, which create space for the flowing water between the membrane surfaces, reduce fouling. In this “Alternating Strand Design” (ASD), filaments of different thicknesses are used. They lead to an even water overflow and thus counteract organic growth. This results in lower operating costs, as fewer cleaning chemicals are required and longer intervals between cleaning operations are possible.

HAND IN HAND

The efficiency with which ion exchange resins and membrane elements from Lanxess can be used in combination has been proven for several years by the treatment of the boiler feed water for the large lignite-fired power plant Lippendorf near Leipzig in the Federal State of Saxony. The membrane elements of the Lewabrane RO B400 FR type used there are characterised by long service life, good permeate yield and salt retention along with low energy consumption. In addition, uncharged organic impurities are removed to a great extent, so that the TOC (Total Organic Carbon) value of up to 700 ppm in the raw water from an adjacent lake can be reduced to well below 0.01 per cent. Typically, TOC values of about 20 ppb are achieved in the RO permeate, which is far below the VGB/EU standard or the recommendation of the US Electric Power Research Institute of less than 100 ppb. The RO system produces up to 1,200 cubic metres of water per day for the water-steam cycle.

Also in Lippendorf, ion exchange resins from Lanxess›s Lewatit product range have been used to treat boiler feed water before and after reverse osmosis for around 15 years. Separate cation or anion exchangers are used in the demineralisation stage, while fine cleaning after reverse osmosis is carried out with a mixed-bed exchanger. At the end of the treatment process, the conductivity of the boiler feed water is below 0.06 µS/cm.

With sales of $8.93 billion in 2016 and about 19,200 employees in 25 countries, the company is currently represented at 75 production sites worldwide. Through ARLANXEO, the joint venture with Saudi Aramco, Lanxess is also a leading supplier of synthetic rubber.