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System components
9
Systemlösung – 6 720 885 509 (2018/03)
2.3
4-draught boiler system
2.3.1
Description of 4-draught boiler system
The basis of a 4-draught steam boiler is a 3-draught
boiler from which a part of the smoke tubes is
separated. The hot flue gases of the CHP module
(in the design for external flue gas utilisation) are lead
through this separate smoke tube field, the so-called
fourth draught, and are used for steam generation.
Fig. 3 Positioning of fourth draught in reversing chamber
[1]
Second draught
[2]
Third draught
[3]
Flue gas
[4]
Fourth draught
Due to different pressure ratios on burner and waste
heat side, and for avoiding back coupling, both flue gas
paths have to be clearly separated on the flue gas side.
This separation concerns, besides the boiler and
possibly existing economisers, also the flue gas routing
via 2 separate chimneys.
The auxiliary units required for a 4-draught steam boiler,
such as e.g. water treatment, feed water degassing
system, fuel supply, pumps etc. will not be treated
further in this document, because their requirements
concerning sizing and installation do not differ from a
conventional boiler system.
Especially, it has to be observed that the installation
location of the feed water control valve is between the
two economisers, in order to increase economic viability
and to save steam for heating up the feed water. In
addition, it is recommended to equip the feed water
container with an overflow device.
This ensures that an unwanted activation of the pressure
relief valve at the feed water container is prevented
during waste heat recovery of the CHP module in the flue
gas heat exchanger (ECO2) with at the same time very
low to no steam generation. Both points are shown in
the hydraulics (
Æ
chapter 3.4, page 34).
6 720 819 535-03.1T
1
2
3
4
By dividing the third draught, the amount of
steam generated by waste heat is limited for
the total output of the boiler
(
Æ
chapter 3.3.3, page 24).
Содержание CHP CE 1200 NE
Страница 43: ...43 Systemlösung 6 720 885 509 2018 03 Notes ...
Страница 44: ...Subject to technical modifications ...