Division 39

United Kingdom

BAT is to reduce NO_X emissions from the melting furnace by using one or a combination of the following techniques:

Technique^f1	Applicability
A description of the techniques is given in Section 1.10.2.
(i) Combustion modifications
(a) Reduction of air/fuel ratio	Applicable to air/fuel conventional furnaces. Full benefits are achieved at normal or complete furnace rebuild, when combined with optimum furnace design and geometry
(b) Reduced combustion air temperature	Applicable only under installation-specific circumstances due to a lower furnace efficiency and higher fuel demand (i.e. use of recuperative furnaces in place of regenerative furnaces)
(c) Staged combustion: (f) Air staging (g) Fuel staging	Fuel staging is applicable to most conventional air/fuel furnaces. Air staging has very limited applicability due to its technical complexity
(d) Flue-gas recirculation	The applicability of this technique is limited to the use of special burners with automatic recirculation of the waste gas
(e) Low-NO_X burners	The technique is generally applicable. The achieved environmental benefits are generally lower for applications to cross-fired, gas-fired furnaces due to technical constraints and a lower degree of flexibility of the furnace. Full benefits are achieved at normal or complete furnace rebuild, when combined with optimum furnace design and geometry
(f) Fuel choice	The applicability is limited by the constraints associated with the availability of different types of fuel, which may be impacted by the energy policy of the Member State
(ii) Special furnace design	The applicability is limited to batch formulations that contain high levels of external cullet (> 70 %). The application requires a complete rebuild of the melting furnace. The shape of the furnace (long and narrow) may pose space restrictions
(iii) Electric melting	Not applicable for large volume glass productions (> 300 tonnes/day). Not applicable for productions requiring large pull variations. The implementation requires a complete furnace rebuild
(iv) Oxy-fuel melting	The maximum environmental benefits are achieved for applications at the time of a complete furnace rebuild

Table 29

BAT-AELs for NO_X emissions from the melting furnace in the domestic glass sector

Parameter	BAT	BAT-AEL
A conversion factor of 2,5 × 10^–3 has been applied for combustion modifications and special furnace designs and a conversion factor of 3 × 10^–3 has been applied for electric melting (see Table 2). However, a case-by-case conversion factor may have to be applied for specific productions.
The achievable levels depend on the quality of the natural gas and oxygen available (nitrogen content).
Parameter	BAT	mg/Nm³	kg/tonne melted glass^f2
NO_x expressed as NO₂	Combustion modifications, special furnace designs	< 500 – 1 000	< 1,25 – 2,5
	Electric melting	< 100	< 0,3
	Oxy-fuel melting^f3	Not applicable	< 0,5 – 1,5

Annotations

Footnotes

f1: A description of the techniques is given in Section 1.10.2.
f2: A conversion factor of 2,5 × 10^–3 has been applied for combustion modifications and special furnace designs and a conversion factor of 3 × 10^–3 has been applied for electric melting (see Table 2). However, a case-by-case conversion factor may have to be applied for specific productions.
f3: The achievable levels depend on the quality of the natural gas and oxygen available (nitrogen content).