SAACKE energy efficiency
Optimizing efficiency
Identifying potential
Flue gas loss
<
= 10%
Steam
Energy losses increase operating costs and place stress on the
environment. That is obvious. Fuel costs rise and today it is more
important than ever to use fossil fuels responsibly – not least of all
from an ecological point of view.
A modern firing plant therefore has to extract as much power as
possible from the available fuel – every quantum of fuel must be
exploited as thermal energy. A prerequisite for this is a high degree
of efficiency.
For this reason increase of efficiency plays a decisive role in the
modernization of firing plant.
But how can one determine what energy losses are avoidable and,
above all: how can one minimize these losses?
How can optimal efficiency be achieved so as not to give away any
energy?
Cooling down at every
burner start
<
Radiation Loss
= 0.35%
<
0.25%
=
Steam losses
<
= 0.6%
Feed water
Blow-down loss
Blow-off loss
Heat losses of firing plants
The factors
The two decisive factors for flue gas loss are
•the flue gas temperature and
•the air surplus.
Mainly various types of heat losses negatively influence efficiency.
The following diagram illustrates this:
To be able to exploit the energy used through the fuel, optimization measures have to be taken particularly with regard to flue gas
losses.
The hotter the flue gas is, the more energy it contains. This means
hot flue gas gives off considerable unexploited energy to the
environment – and provides for a direct heat loss. Therefore, the
lower the flue gas temperature, the lower the heat loss – and the
better the efficiency of the firing system.
© SAACKE GmbH 2012
SAACKE GmbH | Head Office in Bremen: Südweststrasse 13 | 28237 Bremen | Germany | Tel.: +49 421 6495 0 | Fax: +49 421 6495 5224
International contact details: www.saacke.com | e-mail: [email protected]
0-0750-0023-02
The second factor, the air surplus, is the difference between the
actually set and the theoretically required combustion air volume. A
low air surplus is necessary to ensure stable and low-emission
combustion.
With modern
2.4
Boiler Efficiency
Rate firing plants it is between 8 % and
15 %. If the air surplus is too high, however, valuable unexploited
.
.
heat is lost.= (mfw - mbd) · (h – hfw)
ηb
· 100
.
mF· LHV
SAACKE is intensively involved in efficiency increase of industrial
firing plants. We would be glad to offer you a calculation of the
potential for cost and emission reduction by means of the SAACKE
Energy Efficiency Calculator – and then implement the appropriate
measures for you.
in %
Air ratio λL
Calculation of flue gas loss
1.00
18.0
=
Xf
(
A
21 - O2,dry
16.0
in %
)( )
+ B · ϑf – ϑa
1.15
1.20
1.25
1.30
1.35
1.40
1.45
1.50
380°C
15.0
Flue gas loss in %
ηb = 100% – Xf% – 2%(max)
1.10
17.0
2.5 Determination of the Boiler Efficiency Rate
theloss
Flue
Gas
The from
flue gas
can
beMeasurements*
estimated with the help of the Siegert
formula.
1.05
360°C
340°C
14.0
320°C
13.0
300°C
12.0
280°C
260°C
11.0
240°C
10.0
220°C
9.0
200°C
180°C
8.0
160°C
7.0
in %
140°C
6.0
120°C
5.0
100°C
4.0
3.0
=
Xf
ϑf =
ϑa =
O2,dry =
2.0
flue gas loss
flue gas temperature in °C
combustion air temperature in °C
O2 value measured in the dry flue gas in vol. %
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
Measured O2 in dry flue gas in % by vol.
Flue gas loss according to Siegert formula
A and B: constants
110
HFO
Nat. gas Liquid gas Town gas
A
0.68
0.69
0.66
0.63
0.63
B
0.007
0.007
0.009
0.008
0.011
108
106
Firing system efficiency in %
hF in %
EL fuel oil
* Calculation basis: 1st German Immission Control Act (1. BImSchV)
The above-mentioned parameters are inputted in this formula
directly or indirectly.
Natural gas combustion
104
Oxygen content = 1%
Oxygen content = 3%
102
Oxygen content = 5%
100
98
96
94
92
90
The following figure shows a selection of results of the Siegert
formula.
In addition to flue gas losses, energy losses of fans or radiation
losses of the boiler also have a significant impact. All loss factors
can be minimized, as a whole or individually.
Rules_2011.inddhere
inhalt19
88
25
50
75
19
100
125
150
175
200
225
Waste gas temperature in °C
Improvement of firing plant efficiency by means of condensing appliance
technology
14.12.11 11:10
A brief excerpt from our portfolio
• Minimization of auxiliary energy, such as by using variable
speed motors
• Highly efficient secondary heating surfaces (air pre-heater,
economizer)
• Minimization of air surplus by means of
CO- / O2-control
• Service or process water heating
(condensing appliance technology)
• Optimization of mode of operation and control parameters
• Minimization of startup losses by means of burner start with
prepurging sequence
For further information, please visit: www.saacke.com
© SAACKE GmbH 2012
SAACKE GmbH | Head Office in Bremen: Südweststrasse 13 | 28237 Bremen | Germany | Tel.: +49 421 6495 0 | Fax: +49 421 6495 5224
International contact details: www.saacke.com | e-mail: [email protected]
0-0750-0023-02