Division 33

United Kingdom

In order to reduce/minimise thermal energy consumption, BAT is to use a combination of the following techniques:

	Technique	Description	Applicability
a	Applying improved and optimised kiln systems and a smooth and stable kiln process, operating close to the process parameter set points, through: I.. process control optimisation II.. heat recovery from flue-gases (e.g. use of surplus heat from rotary kilns to dry limestone for other processes such as limestone milling) III.. modern, gravimetric solid fuel feed systems IV.. maintenance of the equipment (e.g. air tightness, erosion of refractory) V.. the use of optimised grain size of stone	Maintaining kiln control parameters close to their optimum values has the effect of reducing all consumption parameters due to, among other things, reduced numbers of shutdowns and upset conditions. The use of optimised grain size of stone is subject to raw material availability	Technique (a) II is applicable only to long rotary kilns (LRK)
b	Using fuels with characteristics which have a positive influence on thermal energy consumption	The characteristics of fuels, e.g. high calorific value and low moisture content can have a positive effect on the thermal energy consumption	The applicability depends on the technical possibility to feed the selected fuel into the kiln and on the availability of suitable fuels (e.g. high calorific value and low humidity) which may be impacted by the energy policy of the Member State
c	Limiting excess air	A decrease of excess air used for combustion has a direct effect on fuel consumption since high percentages of air require more thermal energy to heat up the excess volume. Only in LRK and PRK the limitation of excess air has an impact on thermal energy consumption. The technique has a potential of increasing TOC and CO emission	Applicable to LRK and PRK within the limits of a potential overheating of some areas in the kiln with consequent deterioration of the refractory lifetime

Technique

Description

Applicability

Applying improved and optimised kiln systems and a smooth and stable kiln process, operating close to the process parameter set points, through:

I..

process control optimisation
II..

heat recovery from flue-gases (e.g. use of surplus heat from rotary kilns to dry limestone for other processes such as limestone milling)
III..

modern, gravimetric solid fuel feed systems
IV..

maintenance of the equipment (e.g. air tightness, erosion of refractory)
V..

the use of optimised grain size of stone

Maintaining kiln control parameters close to their optimum values has the effect of reducing all consumption parameters due to, among other things, reduced numbers of shutdowns and upset conditions.

The use of optimised grain size of stone is subject to raw material availability

Technique (a) II is applicable only to long rotary kilns (LRK)

Using fuels with characteristics which have a positive influence on thermal energy consumption

The characteristics of fuels, e.g. high calorific value and low moisture content can have a positive effect on the thermal energy consumption

The applicability depends on the technical possibility to feed the selected fuel into the kiln and on the availability of suitable fuels (e.g. high calorific value and low humidity) which may be impacted by the energy policy of the Member State

Limiting excess air

A decrease of excess air used for combustion has a direct effect on fuel consumption since high percentages of air require more thermal energy to heat up the excess volume.

Only in LRK and PRK the limitation of excess air has an impact on thermal energy consumption.

The technique has a potential of increasing TOC and CO emission

Applicable to LRK and PRK within the limits of a potential overheating of some areas in the kiln with consequent deterioration of the refractory lifetime

BAT-associated consumption levels