District Heating •In Copenhagen, Denmark
Dr. techno A. K. Bak, Managing Director
Johannes Hansen, Engineer, District Heating Service
The Copenhagen Lighting Department
District heating service was started in Copenhagen in 1925, after electricity production had
been centralized in a new plant and the boiler
plants of the old power houses, therefore, became.
available for the supply of heat. Two small warm-water systems were established, but soon other
customers requiring a higher temperature than
could be supplied through warm water wanted
service, and it was decided then that further development should utilize steam distribution. The
existing boilers in the old power houses were for
only kg/cm2 ( 170 psig) pressure and back pressure
operation, therefore, could not be established.
In 1933 one of the old plants had to be ,ex-tended, and for the first time combined power-heat
generation was established by installing boilers for
45 kg/cm2 (640 psig) pressure and 400 C (752 F)
steam temperature and 7000 kw in back pressure
At the end of the last war new generating
capacity for electric supply was needed. An investigation was made to determine if the new plant
should be combined with a further development
of the district heating system. As a result of the
investigation it was decided that combined power-heat generation and district heating should be
developed as fas as possible, that warm water
distribution should be used where possible, that
a new power station for combined operation should
be erected, and that the existing main generating
station should be modernized and changed to combined operation.
The main reasons for this decision were that
the increasing costs of fuel made combined operation more attractive, and that Denmark has to
import practically all fuels needed, which makes
their saving of some importance.
Heat is now supplied from three stations: ( 1) a
new maintenance station, Svanemollevaerket, built
recently and designed specifically for power-heat
generation, ( 2) another main generating station, H.
C. Orsted Vaerket, an older station now being
modernized with high-pressure boilers and back-pressure turbines, and ( 3) an older plant serving
peak load purposes both for electricity and district
A flow diagram for the new station, Svanemollevaerket, is shown in Fig. I. Steam conditions at
the high-pressure-turbine throttles are 110 kg/c1Il2
and 510 C (1562 psig and 950 F). The steam
Flow diagram. Steam and warm water distrihution.
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" It.~ul.ti"g fl"l'""t"".
t c""•.~~,,'" 1''''" 1'.
/I. I''''M''''''~ i ~-,"J",..,..t ,._", "......I.,t."'I_~t<uoIt. t. ••
,------,,...+---,z' : ~~;..:."::,,,d'::.-::td,";;;(~.t~
.. Hu/.u di.'r,d M.'~.
,. W",.", ....,., ,.,. di6lntf ~/i~
.. :",':;"....::.:"'- d,,,t,,'.., _,i""
I" Oill,.,~ ,,- 1,-,., tN'ruf"li" 9
FIG. I-Flow Diagram. Steam and Warm-Water
temperature was limited to this value as, at the
time of making the decisions, materials for higher
temperatures were not readily available in Europe.
Reheating was not deemed feasible for this special
design. Two back-pressure turbines totalling
60,000 kw are installed. The back-pressure can be
varied between 8 and 15 kg/cm2 (114-213 psig)
depending upon the requirements of the heating
system. At those pressures the steam will still have
a superheat suitable for the heating system. The
back-pressure steam not being used for district
heating, for feed-water heating, and for the
evaporation of make-up water is utilized in low-pressure turbines of which there are two, totalling
42,000 kw. Besides three extraction points for
feed-water heating- these machines also have two
extraction points for heating the circulating water
of the warm-water district heating system. At full
turbine load the first heater gets steam at a maximum of 0.8 kg/cm2 abs ( 11. 4 psi abs), which makes
it possible to heat the circulating water to about