Division 19
United Kingdom
In order to reduce the emissions of NOx from the flue-gases of kiln firing and/or preheating/precalcining processes, BAT is to use one or a combination of the following techniques:
| A description of the techniques is provided in Section 1.5.2. | ||
| Techniquef1 | Applicability | |
|---|---|---|
| a | Primary techniques | |
| I. Flame cooling | Applicable to all types of kilns used for cement manufacturing. The degree of applicability can be limited by product quality requirements and potential impacts on process stability | |
| II. Low NOx burners | Applicable to all rotary kilns, in the main kiln as well as in the precalciner | |
| III. Mid-kiln firing | Generally applicable to long rotary kilns | |
| IV. Addition of mineralisers to improve the burnability of the raw meal (mineralised clinker) | Generally applicable to rotary kilns subject to final product quality requirements | |
| V. Process optimisation | Generally applicable to all kilns | |
| b | Staged combustion (conventional or waste fuels), also in combination with a precalciner and the use of optimised fuel mix | In general, can only be applied in kilns equipped with a precalciner. Substantial plant modifications are necessary in cyclone preheater systems without a precalciner. In kilns without precalciner, lump fuels firing might have a positive effect on NOx reduction depending on the ability to produce a controlled reduction atmosphere and to control the related CO emissions |
| c | Selective non-catalytic reduction (SNCR) | In principle, applicable to rotary cement kilns. The injection zones vary with the type of kiln process. In long wet and long dry process kilns it may be difficult to obtain the right temperature and retention time needed. See also BAT 20 |
| d | Selective catalytic reduction (SCR) | Applicability is subject to appropriate catalyst and process development in the cement industry |
Annotations
Footnotes
- f1
-
A description of the techniques is provided in Section 1.5.2.