Page 15 - Bosch Boiler House Component

Boiler house components | 15

Air preheating system APH

By means of this system the combustion air is pre-
heated and the flue gas temperature is reduced. The
efficiency is increased.

When installing a new steam boiler system with eco-
nomizer, air preheating is the ideal solution for increas-
ing efficiency, particularly in cases where the integra-
tion of a flue gas condenser is impractical for process
reasons. The Bosch air preheating system is available
for single-flame or double-flame tube boilers with
duoblock burners. The system is economically viable
from a boiler capacity of around five tonnes of steam
per hour. The fan can be installed on the top of the
boiler, this means that the compact system requires
little space for installation. Return-on-investment (ROI)
is generally achieved after 1.5 to 2 years.

Construction
In the Bosch system, a part of the heated feed water
flow is utilised for increasing the temperature of the
combustion air. The hereby cooled feed water
increases efficiency by further reducing the flue gas
temperature in the downstream, combined econo-
mizer.

Equipment level
The air preheating system consists of a three-way
valve, a combined flue gas heat exchanger and an
air-side heat exchanger. In comparison with conven-
tional two-circuit systems, it is now possible to omit
the circulation pump, the expansion vessel and various
electronic safety and control systems. This reduces not
only investment costs, but also the recurrent costs for Water/Condensate
maintenance and replacement parts. Steam
Flue gas
Benfits at a glance:
 Increased system efficiency 1 Steam boiler
 Reduced fuel consumption 2 Combustion air heat exchanger
 Reduced emissions 3 Fan
 Lower investment costs in comparison with 4 Combustion air
conventional solutions 5 Combined flue gas heat exchanger
 Lower maintenance and servicing costs 6 3-way valve
 Shorter period of amortisation 7 Feed water
 Superior quality standardised system from Bosch 8 Chimney
9 Temperature controller

Extremely simplified diagram