TY - BOOK
T1 - NOx from cement production - reduction by primary measures
AU - Jensen, Lars Skaarup
PY - 1999
Y1 - 1999
N2 - This thesis comprises an investigation of the mechanisms involved
in forming and reducing NOx in kiln systems for cement production.
Particularly the mechanisms forming and reducing NOx in calciners
are dealt with in detail, as altered calciner design and operation
are most applicable to controlling NOx emission by primary
measures. The main focus has been on elucidating NOx formation and
reduction mechanisms involving reactions of char, and on
determining their relative importance in calciners.The first three
chapters give an introduction to cement production, combustion and
NOx. In modern cement production processes cement is typically
produced by thermally treating a mixture of limestone and clay
minerals in kiln systems consisting of a rotary kiln and a
calciner. Clinker burning at a temperature of about 1450 °C takes
place in the internally fired rotary kiln and calcination, which
is the most energy demanding process, takes place at lower
temperature in the calciner. When dealing with NOx from solid fuel
combustion it is important to consider reactions of volatile
contents and char separately.Chapter 4 presents an overview of NOx
from cement production. Thermal NOx dominates from rotary kilns,
while NOx formation from fuel-N and reduction of NOx take place in
calciners. NOx formation in the rotary kiln is mainly governed by
the necessary clinker burning temperature and is not very amenable
to control, while net NOx formation in calciners depends strongly
on calciner design, calciner operation, fuel properties and on the
NOx level from the rotary kiln. The low-NOx calciner types
presently marketed are based on combinations of reburning, air
staging and temperature control and seem equivalent in their
ability to restrict NOx formation. If fuels with a significant
volatile content (> 25%) are used, net reduction of kiln
NOx typically takes place in calciners, whereas net NOx formation
takes place when low-volatile fuels (
AB - This thesis comprises an investigation of the mechanisms involved
in forming and reducing NOx in kiln systems for cement production.
Particularly the mechanisms forming and reducing NOx in calciners
are dealt with in detail, as altered calciner design and operation
are most applicable to controlling NOx emission by primary
measures. The main focus has been on elucidating NOx formation and
reduction mechanisms involving reactions of char, and on
determining their relative importance in calciners.The first three
chapters give an introduction to cement production, combustion and
NOx. In modern cement production processes cement is typically
produced by thermally treating a mixture of limestone and clay
minerals in kiln systems consisting of a rotary kiln and a
calciner. Clinker burning at a temperature of about 1450 °C takes
place in the internally fired rotary kiln and calcination, which
is the most energy demanding process, takes place at lower
temperature in the calciner. When dealing with NOx from solid fuel
combustion it is important to consider reactions of volatile
contents and char separately.Chapter 4 presents an overview of NOx
from cement production. Thermal NOx dominates from rotary kilns,
while NOx formation from fuel-N and reduction of NOx take place in
calciners. NOx formation in the rotary kiln is mainly governed by
the necessary clinker burning temperature and is not very amenable
to control, while net NOx formation in calciners depends strongly
on calciner design, calciner operation, fuel properties and on the
NOx level from the rotary kiln. The low-NOx calciner types
presently marketed are based on combinations of reburning, air
staging and temperature control and seem equivalent in their
ability to restrict NOx formation. If fuels with a significant
volatile content (> 25%) are used, net reduction of kiln
NOx typically takes place in calciners, whereas net NOx formation
takes place when low-volatile fuels (
M3 - Book
BT - NOx from cement production - reduction by primary measures
ER -