World Cement - November 2018

accepted standards, such as the European best available

technique (BAT). Inefficiencies are identified and

improvement measures are recommended according

to the level of detail and quality of the information

gathered. Some relevant outcomes from VDZ’s energy

reviews are presented below.

Thermal energy consumption

In order to assess the performance level of a cement

plant with respect to its thermal energy consumption, a

comparison with BAT and reviewer performance indicators

is made. The BAT performance level without using AFs,

mentioned in the European BAT reference document

(BREF) for the cement industry, is 2900 – 3300 MJ/t

clinker for a 3000 tpd kiln.

This level should be seen as a

performance level that can be achieved under optimum

conditions in a short term performance test. The European

BREF also states that on a yearly level the energy demand

can be 160 – 320 MJ/t clinker higher because of heating up

and shutting down the kiln, unplanned kiln stops, etc. This

results in a BAT range on a yearly level of 3160 – 3320 MJ/t

clinker (using 3000 MJ/t clinker as a basis). Experience

shows that the use of AFs, depending on their physical

and chemical properties, often leads to an increase in the

fuel energy demand of cement kilns. Based on process

modelling, the relation between fuel energy demand

and AF ratio was determined.

The AF mix that was taken

as a basis comprises several typical AFs being used in the

cement industry. The modelling – as well as the European

BREF document – considers a precalciner kiln with a

five-stage preheater. Furthermore, data from the CSI’s

Getting the Numbers Right (GNR) database have been

considered. It has to be highlighted that a careful and

methodical assessment is required when comparing real

plant data with BAT, as plant specific conditions must be

taken into account. Figure 1 shows data from kiln lines

that VDZ was asked to review. As production capacity also

influences the specific energy demand, the figure only

depicts kilns of the same size, in this case with production

capacities of about 3000 tpd. Similar schemes are also

available for other kiln capacities (e.g. 1500 and 5000 tpd).

The diagram shows that most of the kiln lines reviewed

had a fuel energy demand higher than the BAT range,

which uncovers potential for optimisation. The following

factors can be related to these potentials:

Technological factors (type of equipment and

equipment design).

Operational factors (thermal substitution rate, kiln

instability, coating formation, blockages, refractories,

and frequent kiln starts and shutdowns for process

reasons, etc.).

Maintenance factors (kiln seal condition,

preheater and calciner condition, kiln stops due to

malfunction of equipment, and lack of calibration of

instrumentation, etc.).

Quality factors (fuels, raw materials and raw

mix chemical and physical properties, and LSF

fluctuation).

Mined raw materials travel along extensive transport routes.

Overland and pipe conveyors are an energy efficient, reliable

and environmentally friendly way of transporting the commodi-

ties over long distances to the plant or storage area. We

customise the curved belt conveyors to overcome any challen-

ging topographical circumstances. This minimises the transfer

points and the number of systems and reduces investment,

operational and maintenance costs.

For more information visit

www.beumergroup.com

SOME THINK

RAWMATERIAL

TRANSPORT

REQUIRES A

COMPLEX INFRA-

STRUCTURE.

WE THINK

DIFFERENT.