1 03/06/2015franck delacroix - ademe an efficient combustion device leading also to very low nox...

04/18/23 Franck DELACROIX - ADEME1

An efficient combustion device leading also to very low NOx emission levels

Franck DELACROIX

ADEME (French Agency for energy and environment management)

BAT co-ordinatorEGTEI (Expert Group on Techno Economical Issues) agency leaderSOx, NOx and N2O emissions of industrial processes

“The flameless oxidation mode” :


NOx emission reduction : Primary techniques Optimal choice of the burner and its operating conditions Staged combustion

• Air staging

• Gas staging (reburning) Recirculation of combustion products

• Internal

• External Etc...

Energy efficiency and NOx emission reduction


Energy efficiency : example of regenerative burners



Air preheat temperature

(°C)

NOx (mg/Nm3 – O2 3% -

dry gases)

100 – 200 Below 400

300 Up to 450

400 Up to 600

500 Up to 800

700 Up to 1500

800 Up to 2300

900 Up to 3500

1000 Up to 5300

Possible indicative influence of air preheat on NOx emissions

5,0

22

16

ON

T

69090exp

T

10.6

dt

NOd



First generation of regenerative burners with very high NOx emission levels Studies have been realized mainly in Japan, Germany and USA, Several manufacturers have commercialised new types of burners, Industrial demonstrations have been mainly validated in Asia, European references at quite small scale.

Principle of these new burners :

the „flameless combustion mode“


THE FLAMELESS OXIDATION MODE : principle 1/2

oxidising air and fuel gas injected separately with high injection speeds,recirculations of the combustion products to the burner high temperature of the recirculated combustion products (> 1000°C) used to initiate and maintain this mode of “combustion”.

AIR

GAZ

Recirculation

Recirculation

AIR

GAZ

Recirculation

Recirculation

Process heat

I II

III

Air

Gas

Combustion products


THE FLAMELESS OXIDATION MODE : principle 2/2

combustion distributed throughout the volume of the combustion chamber, relative homogeneity (temperature and composition) in the combustion chamber, the flame can then no longer be seen,

Explaining why experts of this field speak about :

THE FLAMELESS OXIDATION OR COMBUSTION MODE


How to characterize the FLAMELESS OXIDATION MODE

and explain the low NOx emission level ?


The INTERNOx project

Three years project started in October 2000 Partners : Gaz de France, Arcelor/IRSID, Stein-Heurtey and supported by ADEME

Containing the following phases : - Technological survey,

- Study of the heating equipments,- Design of pre-dimensioning tools dedicated to slab furnaces,- Study at semi-industrial scale,- Validation of the simulation tools,- Preparation of a demonstration project at industrial scale.


Main goals of the study

Energy savings• Improvement of energy efficiency• Optimisation of processes

Pollution reduction• CO2

• NOx• Noise

Product quality Process reliability


Burner characterization

• WS GmbH (Germany)• North American Manufacturing Co (US)• NFK (Japan)• Etc


NOx : Influence of the main operating parameters

0

100

200

300

400

500

600

700

800

900

1000

1000 1050 1100 1150 1200 1250 1300 1350 1400

T furnace (°C)

NO

x (m

g/m

3(n)

@ 3

% O

2)

0

100

200

300

400

500

600

700

800

900

1000

0 100 200 300 400 500 600 700

Thermal input (kW)

No

x (m

g/m

3(n

) @

3%

O2)

0

100

200

300

400

500

600

700

800

900

1000

0,7 0,9 1,1 1,3 1,5 1,7

Air ratio

No

x (m

g/m

3(n

) @

3%

O2)

0

100

200

300

400

500

600

700

800

900

1000

40 50 60 70 80 90

Exhaust gases through burner

No

x (m

g/m

3(n

) @

3%

O2)


Main conclusions of the burner tests

Very Low NOx burners commercially available : NO <300 mg/m3(n) and η > 75% whatever the operating conditions,

Strong influence of the air-fuel ratio on NOx emissions, Influence of the furnace temperature on NOx and combustion

efficiency Low effect of thermal input on NOx Strong influence of the percentage of exhaust gases through

the burner on the combustion efficiency Design tools necessary to implement this new combustion

technique (product quality, efficiency, …)


Other studies of the heating equipmentDetailed measurements in the flame

Parameters followed

• temperature

• species

• velocity

• heat transfers

Reference operating conditions

• thermal input = 200 kW,

• preheated air = 1000 °C

• furnace temperature = 1300 °C

• air / fuel ratio = 1,1


Study of the heating equipmentDetailed measurement in the flame – main results

Fields of the mean temperatures

Chemiluminescence emission of the OH* radical

Fields of CO concentration and mean temperatures

m i n m a xm i n m a xm i n m a x


Simulation of the flameless combustion mode

Pre-dimensionning of slab reheating furnaces

Existing software has been adapted by the Polytechnic Faculty of Mons and IRSID to simulate the installation of burners working in the flameless combustion mode into any area of a furnace.

Considering the stationary regime, this tool showed that :- a decrease in fuel consumption by 8,5% can be expected installing this new type of burner in the preheating zone of an existing furnace instead of conventional burners,- the design of a new furnace only fitted with this kind of burner could increase the productivity by 17% and decrease the fuel consumption by 14% .


Simulation of the heating equipment and representation simplification

CFD approach has been chosen The methodology employed is:

• to pre-select the sub-models used to represent the industrial burners • to validate them with the detailed in-flame measurements

■ Simplification : accuracy/calculation-time compromise, in relation to the detailed model,

Conclusions implemented to simulate the test furnace at semi-industrial scale in the dynamic regime


Test at semi-industrial scale and validation of the tools

Objectives:• to validate the modeling tools developed in parallel• to assess the performance of the flameless-oxidation burners in

conditions close to an industrial furnace• to acquire a technical expertise to scale up this technology in the

industry


The combustion efficiency is over 85% in the reference operating conditions

The pulsed regulation mode is very good for the burners control (in terms of heating quality and NOx emissions)

The burners enable to achieve a very good thermal homogeneity These tests represent a very useful database for the validation and

the specification of the simulation tools limits

Test at semi-industrial scale and validation of the tools


Soaking zone

Heating zone

Billets entrance

Billets exit

Objectives : production capacity increase, while improving efficiency and reducing NOx emissions.

Existing slab reheating furnace

CFD assessments showed that the installation of two pairs of 3MW burners upstream the heating zone gives the most interesting results

Preparation of a demonstration project at industrial scale


Preparation of a demonstration project at industrial scale

Mean temperature fields

Example of simulation for the reheating furnace


Conclusions & perspectives 1/2

Regenerative burners used in the flameless combustion mode are high-performance systems allowing to significantly increase the productivity as well as reduce the CO2 emissions,

Measurements have also shown that low NOx emissions can be achieved ( below 300 mg/m3(n) at 3% of O2), whatever the operating conditions,

Several manufacturers are now offering this type of burner, Industrial demonstrations in Europe, in various sectors especially

metallurgy, should appear in the coming months, The design tools developed in the framework of the INTERNOx project ,

but also a better understanding of the combustion phenomena enable guarantees to be given regarding the performances and heating quality of the products,

It is very likely that this new combustion mode will also be used, in the short or medium term, in other industrial sectors such as ceramics, glass-making, petrochemicals, gas turbines or industrial boilers.


Conclusions & perspectives 2/2

In the medium term, it will be thus a concern less during the BAT determination process, as it will no more be necessary to make a trade-off between energy efficiency, productivity and NOx emission reduction...


Thank you for your attention

1 03/06/2015franck delacroix - ademe an efficient combustion device leading also to very low nox...

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