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Strong Demand for High-Tech

Pumps for Green Technology: Geothermal, Solar Thermal, Biofuels and Small Hydropower

02.06.2009 | Editor: Dr. Jörg Kempf

Impressive dimensions: a Hermetic pump at a Spanish solar power station.
Impressive dimensions: a Hermetic pump at a Spanish solar power station.

The time is rapidly approaching when oil, gas and coal will no longer be able to satisfy worldwide demand for energy. In response, politicians are forcing the development of renewable and alternative sources of energy. As is the case in conventional process engineering, pumps have a crucial role to play.

According to a report in the German business journal Handelsblatt, governments worldwide have allocated $ 430 billion to green technology as part of their economic stimulus programs. This is a very impressive sum. A number of industries stand to benefit from the funding. Pump manufacturers who offer conventional designs and special adaptations which are tailored to the green market are some of the potential benefactors. At this year’s Achema, PROCESS took a closer look at the active players. This article focuses on pump systems which are specially designed for geothermal, hydropower, solar thermal and biofuel applications.

Pumps for geothermal systems

Uraca supplied a specially-designed injection pump for the geox hydrothermal-geothermal project in Landau (Western Germany). Geothermal water from a depth of 3000 meters is being used on this project to generate electricity and provide district heating. The pump is rated at more than 550 kW and is capable of injecting about 4800 liters of deep water per minute at outlet pressures up to 80 bar. High efficiency and the robust, proven design were two of the reasons why the 5-plunger pump was selected.

Pumps as turbines

Hydropower has been a useful source of energy for a very long time — in the past for milling grain and in today’s world for generating electricity. At the beginning of the year, KSB began shipping turnkey turbine systems for energy generation and recovery applications. If water flows backwards through a pump, the impeller runs in the reverse direction and the pump acts as a turbine. Pumps are operated as turbines to reduce differential pressure or to exploit head and flow constriction in a system.

KSB supplies hydropower solutions to generate energy from systems with 2.5–300 meters head and volume flows between 10 and 5000 l/s. According to the company, demand for small power generation systems has risen sharply in response to steep increases in energy prices.

In the past, the relatively high cost of turbines manufactured as one-off items or in low quantities has been an obstacle to efficient generation of power from small waterways. The pumps have up to 88% operating efficiency.

Pumps for solar thermal power generation

Up to this point, solar thermal power stations using parabolic trough technology have only been able to generate power when the sun was shining. Next-generation power stations solve this problem by using molten salt to store and transfer heat. Electricity generation continues for up to six hours after sunset or when the sky is overcast.

A new-generation solar thermal power station, the Archimede Project, is currently being built in Sicily for demonstration purposes. Parabolic mirrors focus the sun’s rays on pipes. Molten salt is heated to temperatures up to 580 °C in the solar collector which is located at the focal spot or focal line. The solar power station is designed to produce 5 MW of electricity, which would save around 7300 tonnes of CO2 compared to a conventional power station. Friatec-Rheinhütte was awarded a contract to supply GVSO vertical pumps (which are 6–8 meters in length) to circulate the molten salt. The pumps circulate the cool molten salt (280 °C) from a cold tank through the mirror array to a hot tank. The molten salt, which has been heated to 550 °C, flows through a heat exchanger (for steam generation) back to the cold tank. The vertical GVSO submerged pumps are made of high-grade stainless steel and have a special friction bearing which is lubricated by the medium. Power generation is scheduled get underway at the end of 2009.

Hermetic is also active in the solar power market and has already acquired some major contracts. The company was selected as the supplier of a six-stage pump with barrel-casing and external cooler (CAMKT 30/6 for hot water) for the Plataforma Solar de Almeria trial power station. The recirculation pump will be installed in the DISS (Direct Solar Steam) unit in the collector circuit. Hermetic was also chosen to supply three CNPK 200-200-300s with air coolers for the hybrid power plant in Kuraymat, Egypt (CCPP and parabolic trough solar power station, 150 MW). The pumps, which are rated at 615 kW (at 40 °C), have the world’s largest low-voltage canned motors. The test run was successfully completed in May.

Pumps for production of green fuel

As a result of the global political consensus to replace fossil fuels and reduce carbon dioxide emissions, new biofuel production plants continue to go on stream around the world. First-generation biofuels (biodiesel and bioethanol) made of high-grade natural products (oils, sugar and starch) are already being produced in large volumes. These biofuels are normally blended with conventional fuels. Second-generation BtL (Biomass to Liquid) fuel production utilizes the entire plant including stalks and chaff as feedstock. Two technologies are currently available: an enzymatic cellulose-based wet process and the Fischer-Tropsch process (Germany is a leader in this technology). Biomass is converted under high pressure and temperature into synthetic gas. Synthetic fuels are then produced from the gas in the downstream process. Forecasts indicate that BtL will satisfy up to 20% of total fuel demand by 2030 depending on the level of government subsidies.

Manufacturers of pump systems and similar equipment have the opportunity to exploit a high-growth market which has significant future potential and which cannot be effectively addressed with off-the-shelf solutions. The media is corrosive and/or abrasive, and the processes run at high temperature and pressure.

Pumps made by the German manufacturer Bran+Luebbe are currently running at a number of biofuel plants around the world. The company supplies standard metering pumps and complete metering systems for biodiesel and bioethanol applications as well as special pumps which are used in the conversion of biomass into biofuel (BtL). ProCam and Novados membrane pumps are ideal for biofuel production applications. ProCam pumps are suitable for simple applications at pressures up to 10 bar and flow rates up to 500 l/h. Novados pumps are the solution of choice for higher pressures and in particular for flow rates up to 2000 l/h, an important consideration in large-scale biofuel plants.

Lewa is also very active in the biofuel market. The company worked along side of experts from the scientific, engineering and research communities on the development of new techniques for producing 2nd generation biofuels. The company’s diaphragm dosing pumps are very rugged. They are readily adaptable to different process conditions and fluid properties, and they have been installed at a number of pilot and test plants. Lewa is supplying circulation pumps for Fischer-Tropsch synthesis and diaphragm pumps to boost reactor pressure at the world’s first commercial BtL plant. Coming up with a customer-specific solution which is able to withstand the harsh process conditions (T >200 °C and pvap >50 bar) has been very challenging.

KSB is developing pumps which address the ecological issues in biofuel production. Metallic pumps with shaft seals are deployed to handle the feedstock, e.g. soy oil or rapeseed oil. However, special pumps are needed to handle/recover methanol to comply with air pollution regulations. The company recommends pumps without shaft seals (canned motor pumps or pumps with magnetic couplings) for these applications. The pumps used at the washing columns must be made of high-grade materials. In some cases, the pumps are exposed to hydrochloric acid. Super duplex cast steel is a good choice, because it is resistant to all types of media that contain chlorides. Glycerin applications are particularly challenging for pump designers. Salts, which can make up to 35% of the medium by weight, precipitate out during the process, and they can be present in crystalline form. Non-clogging pumps are resistant to abrasion. If necessary, duplex steel can be put through a second heat treatment process to further reduce wear.

Pumps for high density solids

Putzmeister specializes in pumps which are designed for high density solids. Systems designed to handle biomass are designed to operate for more than 160,000 hours. The pumps have been used to handle renewable feedstock (e.g. grass and corn silage and silage mixed with slurry), food past its use-by date, food waste and bio waste from recycling garbage cans as well as high temperature conversion for production of methane. Pumps designed for high-density solids made by this manufacturer have been installed at more than 60 biogas plants.

Conclusion: Green technology gives pump manufacturers another excellent opportunity to enhance their profile as problem resolution experts worldwide. Specially modified high-tech pumps are often needed for these applications, and international low-costs producers are not able to deliver the goods.

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