The development of new, environmentally friendly technologies for heating and cooling residential and commercial premises is one of the key challenges for many energy companies around the world. The use of the energy of the sun, sea tides and currents, wind and heat obtained from the bowels of the earth, to one degree or another, has proven its practical benefits, efficiency and profitability.
The sea has great potential as a source of energy. Attention of experts from one of the largest French energy companies Engie, which develops and implements projects, including those using alternative sources, was attracted by the idea of using the thermal energy of the Mediterranean Sea to heat and cool buildings. One such development was the Thassalia geothermal power plant. Seawater from the port of Marseille is pumped to chillers for cooling and to heat pumps for heating buildings in the downtown area.
Similar facilities are already in operation (for example, a company project Engie in Paris on the River Seine), but the €35 million Thassalia offshore geothermal power plant is the first of its kind in Europe to use salt water for both heat and cooling. At the same time, the needs of buildings with an area of 500 thousand m are provided2 in the new urban development project Euroméditérranée.
Eco-city Euroméditérranée is located on 480 hectares in the heart of Marseille (between the commercial port, the Old Port and the railway station), where large-scale housing, public buildings and social infrastructure facilities (museums, theaters, schools, hospitals, etc.) are being built. as well as landscaping. Thanks to the construction of a geothermal plant, which will reduce greenhouse gas emissions by 70%, electricity consumption by 40% and water consumption by 65%, the eco-city received the status of HQE (High Quality Environment) — a facility with a high-quality environment.
The development of the Thassalia power plant project began in 2010 and combined the experience of two subsidiaries Engie Coffley and Climespace. The French division of the concern was chosen as the equipment supplier KSB. Commissioned in 2014, the station was inaugurated on October 17, 2016.
Rice. 1. MegaCPK seawater pumps
The main task of the project was to organize and ensure the functioning of the heating and cooling systems of the Euroméditérranée buildings. It is innovative for several reasons. Firstly, the station supplies the buildings with heat and cold, while in France the two systems are separated. Secondly, the thermal energy of the sea is used and, finally, this is the first European project for the engineering support of an eco-city of this magnitude.
KSB pumps play a central role in the operation of the station and its distribution network. Sea water is taken at a depth of 7 m at an average temperature of 14–24 °C. KSB pumps (Fig. 1). made of special corrosion-resistant material.
Rice. 2. Specifications of KSB grades
Each unit with a capacity of 720 m3/h is equipped with a powerful energy-efficient motor and frequency control system. The problem of corrosion formation when pumping warm sea water was extremely relevant in the implementation of this project, since the temperature of the sea water taken in summer could reach 25 °C. Therefore, the parts of the pump that come into contact with the pumped medium were made of a special Noridur alloy.® (duplex stainless steel), which has high corrosion and abrasion resistance and is used when pumping chemically aggressive liquids such as warm sea water, concentrated acids and pumped media in flue gas desulphurization processes (Fig. 2).
For the same reason, KSB’s Isoria Butterfly Valves, which perform the shut-off and regulation functions of the seawater supply, are protected by a Halar corrosion coating. Gate valves with a diameter of 50 to 700 mm are equipped with manual and pneumatic drives. Sea water is fed to cooling chillers and heat pumps that produce cold and hot water at the same time. It should be noted that additional gas boilers complete the overall design to ensure continuity of plant operation under all conditions.
Rice. 3. MegaCPK cooling circuit pumps
After processing in a geothermal plant, the thermal energy is supplied to the Euroméditerranée buildings for heating or air conditioning systems through heating circuits with a hot water temperature of 60 °C (Fig. 4) and cold supply circuits (5 °C) (Fig. 3). Since the length of the network was 3 km, it was necessary to use powerful pumping units that would work effectively in heating and cooling systems. Each of the two circuits is equipped with four of the latest KSB MegaCPK pumps (8 units in total) with a capacity of 160 and 355 kW. When choosing these units
not only their ability to provide the required pressure was taken into account, but also high performance at a changing speed of rotation of the impeller. The efficiency of the MegaCPK pump remains consistently high (about 84%) at both 1500 rpm and 1750 rpm.
Rice. 4. Pumps MegaCPK heating circuit
In addition to pumps of this series, the company KSB supplied Etanorm pumps (power 75 kW, capacity 650 m3/h) and Etaline for heat exchangers and recirculation. 150 manually or pneumatically operated Boax B series centric butterfly valves in a range of diameters DN from 100 to 600 mm.
Marine geothermal energy has a number of advantages over traditional thermal energy, primarily from an environmental point of view. Centralized production of cold and heat helps to reduce the greenhouse effect. On the financial side, the price of generated heat energy is about 10% lower compared to decentralized systems, and changes in electricity and gas tariffs are less sensitive.
Moreover, pumps are system components that consume large amounts of electricity, and the use of high-tech KSB pumps will provide great savings potential. In this way, the inhabitants of the Euroméditerranée eco-city will be able to fully appreciate the work of heating and air conditioning systems based on the use of the latest marine geothermal technologies.
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Company KSB (KSB)
Source: Company KSB (KSB)