Ultrafiltration for process water recovery

Thermal power plant Prunerov II

With an output of 750 MW, Prunerov II is the largest thermal power plant in the Czech Republic. It is owned and operated by ČEZ, which is the largest electricity producer in the Czech Republic and is also among the top 10 electricity producers in Europe.

The entire power plant has been undergoing modernization since 2012. The supply of ultrafiltration (UF) from MEGA is another of the technologies that lead to a reduction in the ecological and economic demands of the power plant operation.

Challenge

Extremely warm periods in recent years, in which the groundwater level dropped significantly, were the impetus for investment in equipment to provide a second source of boiler feed water and ensure continuity of the power plant’s operation.

Ultrafiltration as a solution

Until now, the only source for cooling water production has been groundwater treated by clarification, sand filtration and reverse osmosis. The new, backup source for cooling water production is now river water. MEGA has integrated river water treatment into the existing treatment technology to produce process water. River water, after treatment at the existing coagulation plant, is now subjected to a high-quality de-ironing and de-manganisation process and subsequently purified on four ultrafiltration units. The quality of the ultrafiltrate meets the required parameters for final treatment on the existing reverse osmosis plant.

Ultrafiltration unit parameters

The installed ultrafiltration technology contains four units of ten modules, with a total maximum output of 100 m³/h of ultrafiltrate. The average system yield is 95 %. Normal operation is in 3+1 mode, i.e. three lines are operating and one is in stand-by mode. This makes it possible to ensure continuous operation.

Compliance with the required quality of the output water from the UF was verified by a guarantee test. The water samples were analyzed by an independent accredited laboratory.

Continuity of operation ensured

Thanks to the installation of the ultrafiltration station, the operation of the power plant is independent of temperature fluctuations and groundwater levels. This is particularly helpful during the summer months when there is no need for forced unplanned shutdowns.

The installation process

The installation and putting the units into operation took place within six months, with the plant operating without any extended downtime. We installed the ultrafiltration station instead of no longer used technology and at the same time, we used some of its parts. As part of the integration of the ultrafiltration technology, the control of the sand filtration technology was modified to achieve optimum parameters for the entire technological line.

Monitoring and service

The installed ultrafiltration units are fully automatic (integration into the existing control system using the existing electrical and measurement and regulation elements) and, except for routine maintenance, do not require operator intervention.

It simply works

Based on the results of intensive in-house testing and the first months of operation, the power plant operator has confirmed that the ultrafiltration units we have installed meet these requirements:

• reliability,
• easy operation and integrated monitoring,
• reduced operating costs,
• continuous water treatment with the required parameters.