Paper Technology International 2020 - Journal - Page 26

PAPERTECHNOLOGYINTERNATIONAL
Reference project – 80% of natural cooling for a year with river water
Schoellershammer PM6 control rooms cooled with riverwater
Planned concept
One big project where BM Green Cooling has utilized natural
cooling is in the paper mill of Schoellershammer, located in the
city of Kreuzau, Germany. Schoellershammer PM6 has its control
rooms mainly cooled with natural cooling, but it also has mechanical
cooling installed in the event of redundancy, as described earlier.
The system concept is designed so that medium
temperatures to the control rooms of 16°C flow and 20°C return
can be operated. The system components used were specifically
designed and constructed to be generous for these high medium
temperatures.
In the control rooms within the new PM 6 building, the
installed power units and electronics create a significant heat load.
Without air conditioning, temperatures well above the specified
values would arise within a few minutes. This would result in the
power electronics failing. To cool the individual control rooms in an
energy-efficient manner, special water-cooled cooling cabinets were
installed in the control rooms. Their registers and pipes have an anticorrosive coating to minimize the effects of aggressive gases.
A great advantage at this temperature level is no energy
is wasted in dehumidifying the air in the switch rooms and that the
system’s energy consumption is very low thanks to the river water
cooling operating mode, approx. 5425 h/a. The entire installed,
mechanical cooling generation has a cooling capacity of 786 kW. As
one circuit of a chiller is redundant, so an effective cooling capacity
of 655 kW is available. This redundancy ensures operational
reliability for 365 days of operation. The entire cooling system is
housed in a machine room, containing all 3 chillers, heat exchangers
for river water cooling and all associated pumps, as well as control
elements that are required for the cold generation.
One of the main goals of the new paper machine project
for Schoellershammer was energy efficiency, and so energy
efficiency was carefully considered in every step of the planning.
Therefore, also the control room cooling was thought from a green
point of view. BM Green Cooling was chosen as a partner after
successful previous projects addressing the cooling requirements of
Schoellershammer.
To achieve optimum energy efficiency, the automation
also needs to be up to the task, so that the most efficient part of
the system is always used and the system always provides the
right amount of cooling power. The project was closely designed
together with technical experts for the customer, and the controlls
were designed with Siemens S7 throughout. The cooling system
was seamlessly and bi-directionally integrated into the Distributed
Control System for the customer.
The heat exchanger for river water cooling heats the
riverwater by 4 Kelvin. The heated water is then made available for
production. This is the main operating mode of the system. If the
river water is too warm, the system switches to the free cooling or
mechanical cooling mode, depending on the outside temperature.
The river water cooling mode is operated for approx. 5425
h/a (62%). The free cooling mode is approx. 1304 h/a (15%) and
only when the river water and the outside temperature are too high
do the chillers still run for approx. 2031 h/a (23%) depending on
the load. At the same time, these 3 operating modes guarantee
complete redundancy of the technologies to one another. The dry
coolers, specially designed according to customer requirements,
were installed on a steel frame above the refrigeration center. Every
single one of the 30 installed EC fans can be opened individually.
Figure 4: Original natural cooling concept diagram
for Schoellershammer.
Figure 5: Dry coolers feature
openable fans to enable cleaning
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