VGB POWERTECH 10 (2019)

Heat storage systems
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l 2013
(2013)
Table 2. Data of Münster pressurised
water storage).
Height
Diameter
28 m
10 m
Storage capacity 8,000 m 3 /
up to 545 MWh
Max. temperature 120 °C
GKM water heat storage system
Grosskraftwerk Mannheim AG (GKM) is
a joint-venture power generation plant of
RWE, EnBW, and MVV [19]. The CHP units
of GKM are generating 50 Hz power for the
public electricity network, 16.7 Hz railway
power for DB Energie (German railways),
and district heat for the MVV utility company.
F i g u r e 11 shows the Mannheim
district heat system which is fed with heat
from the GKM plant.
Based on thorough investigation and comparative
analyses which were carried out
in order to identify the options for operational
optimisation of the CHP units in the
GKM, the decision was taken to install a
non-pressurised district-heat storage unit.
F i g u r e 12 shows a simplified process
flow diagram of the GKM water heat storage
system.
The centrepiece of the system is the storage
tank based on the “System Dr. Hedsource:
Stadtwerke Münster
Fig. 8. Münster pressurised water storage.
around the world. Further R&D activity focusing
on the improvement of such systems
is advisable.
Thermal storage/water and steam/
Ruths’ storage system
In most of the technical applications being
used internationally for thermal energy
storage, water and steam are the primary
media. The Ruths’ storage system (F i g -
u r e 7) has been in use for decades now,
mainly in power plants, industrial plants,
and locomotives.
The Ruths’ steam storage system is characterised
by:
– simple construction/easy to integrate in
power plants,
– water/steam system (well known),
– positive long-term experience,
– high temperature range (up to 300 °C),
– good capacity (MW),
limited volume (MWh),
– sliding pressure,
– periodic official pressure tests necessary,
and
– relatively high investment costs.
Thermal storage/pressurised water
Pressurised water is used in many technical
applications for the purpose of storing
thermal energy. This type of storage has
been in use all over the world for decades.
F i g u r e 8 shows an example plant with
four storage tanks that is operated by the
Münster municipal utility (Germany).
Ta b l e 2 lists a selection of technical data
of this plant.
Fig. 10. Water heat storage tank
in Linz/Austria.
F i g u r e 9 shows a simplified process flow
diagram. This type of storage is often used
for power plants, industrial plants and
smaller businesses and is characterised by:
– simple construction/easy to integrate in
power plants,
– water/steam system (well known),
– positive long-term experience,
– relatively high temperature range,
– complicated system integration,
– periodic official pressure tests necessary,
and
– relatively high investment costs.
Thermal storage/non-pressurised water
Systems used in thermal energy storage
applications often operate with water under
ambient pressure conditions. This type
of storage has been in use worldwide for a
long time. There are two major types: dualtank
and single-tank systems. F i g u r e 10
shows an example plant with one storage
tank in Linz, Austria.
Applications based on the “System Dr. Hedbäck”
are commonly used in power plants
and large district-heat systems [18]. They
are characterised by:
– simple construction/easy to integrate in
power plants,
– water/steam system (well known),
– positive long-term experience,
– restricted temperature range (< 100 °C)
– atmospheric pressure,
– large volumes (up to 50,000 m 3 per
tank),
– high capacities (up to 300 MW and
1,500 MWh per tank)
– easy system integration, and
– reasonable investment costs.
boiler 1
Mannheim
destrict heat supply line
boiler 2
destrict heat
return line
boiler 3
district heat extension
district heat concentration
district heat lines
Heidelberg
Fig. 9. Process flow diagram of a pressurized water storage.
Fig. 11. Mannheim district heat system.
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