DUOFLEX
Improved heat economy Widely adjustable flame shape Easy change-over between fuels
Main fea f eatu tures res Robust design Low primary air consumption Adjustable swirl Adjustable air nozzle area
Application
Design
The The DUO DUOFL FLEX EX burn burner er fire firess rorotary kilns with pulverised coal or coke, coke, oil, oil, natur natural al gas gas or any mixmixture of these fuels. The burner may be fitted with extra ducts for secondary fuels such as plastic chips, wood chips, sewage sludge, etc.
The The bur burne nerr is is bas based ed on a nov novel el concept featuring a central duct for gase gaseous ous and and liq liquid uid fuel fuelss placed inside an annular coal duct which is surrounded by two concentric ducts that form two primary air channels, one for radial air and one for axial air.
Standard types are available for any fuel combination and a maximum capacity ranging from 20 to 250 MW, catering for even the largest of rotary cement kilns.
The two air flows are mixed before being injected via the conical air nozzle. The two outer ducts form a very rigid supporting structure, minimising deflection of the
Central Central fuel in jection Suitable for alternative alternative fuels
AXIAL AIR
AXIAL AIR
SWIRL AIR
SWIRL AIR
COAL
COAL
COOL AIR
COOL AIR
OIL
s m e t s y s n l i K
Primary air change by adjusting nozzle area
OIL
The burner nozzle is adjustable both vertically and horizontally
burner pipe and ensuring long refractory life. The primary air is supplied by a high pressure fan that yields a maximum pressure of 250 mbar. The air nozzle area can be adjusted within the range 1:2. The axial/radial axial/rad ial air ratio - and consequently the degree of swirl - is also adjustable. These adjustments offer wide scope of shaping the flame.
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Process and functi on From a process point of view, a burner used for heating the burning zone of a rotary cement kiln must fulfil the following requirements: The burner must be able to fire coal, coke, fuel oil and natural gas or any mixture thereof, ensuring complete combustion, low excess air and minimum formation of
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•
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carbon monoxide (CO) and nitrogen oxides (NOx). If relevant, the burner must be able to handle alternative fuels without requiring change of its original design. In this way, way, only minor modifications modificat ions to meet the special requirements must be necessary. The burner must produce a short, narrow, strongly radiant flame, as this is a condition for good heat transfer from the flame to the material in the sintering zone of the kiln. Flame formation must be conducive to a dense, stable coating on the refractory in the burning zone of the kiln as well as a nodular clinker with low dust content and correctly developed clinker phases. The burner must use as little primary air as possible
without compromising stability during normal or upset operating conditions. Primary air is basically false air, in other words air that has not been used for clinker heat recuperation recuperat ion while passing through the clinker cooler. The primary air is usually expressed as a percentage of the stoichiometric combustion air needed to burn the amount of fuel fired through the burner.
Flame momentum The crucial parameter of flame formation is the primary air momentum which may be expressed as the primary air percentage (per cent of stoichiometric air requirement) multiplied by the injection velocity. Consequently, if the velocity is doubled, the primary air percentage may be reduced to half.
Traditional burner with damper DUOFLEX with adjustable nozzle area 100%
10%
n o 90% i t p m u 80% s n o c 70% r e w o 60% P
8%
r i a 6% y r a m4% i r P 2%
50% 50%
Traditional burner with damper DUOFLEX with adjustable nozzle area
0% 60%
70%
80%
90%
100%
50%
Momentum
60%
70%
80%
90%
100%
Momentum
Effect of nozzle area control versus traditional damper control
The primary air consumption will normally be in the range of 6-8 per cent, corresponding to a primary air momentum of approximately 1250 - 1780 per cent m/s. The adjustable air nozzle is ideally suited for adapting the momentum to the conditions for attaining the best flame shape. The burner in a rotary kiln functions as an injector, the purpose of which is to draw the secondary air coming from the cooler into the flame in order to make the fuel burn as close as possible to the centre line of the kiln. This This explains why the momentum of the burner is the parameter that determines flame formation. A higher momentum means faster mixing and a shorter and hotter flame. Divergent feeding of fuel and primary air should be avoided as it inevitably leads to wider flames and higher temperatures on the inner surface of the burning zone. Good coating
formation is only possible if the inner surface is cold enough for the liquid to solidify upon contact. The use of a narrow flame in a cement rotary kiln is extremely important since a divergent flame that impinges upon the
lining will strip off the coating, resulting in very high kiln shell temperature and short refractory life. Flame impingement upon the material charge will increase the evaporation of sulphates, which usually leads to increased coating formation in the kiln riser duct.
Since Since good good flame flame format formation ion in the kiln permits operating with very little excess air and without the formation of CO, a burner operating with correct flame momentum despite the higher flame temperature will result in less formation of NO than a low momentum burner operating with more excess air. Practical experience has shown that the formation of a strong, stable, short and narrow flame requir requires es a moment momentum um of miniminimum 1400 - 1600 per cent m/s. A flame momentum below this range will result in too long a
flame, flame, high high kiln kiln shell shell temper temperaatures above the burning zone and in the kiln back end as well as unstable kiln operation with a too long and cold burning burning zone thereby permitting undesirable clinker crys crysttal growth. The two different kiln temperature profiles, before and after introducing the DUOFLEX burner, clearly show the huge effect on both coating formation and kiln shell temperature. No lining lining repair repairss were were made made while while exchanging the two burner installations.
The very very easy easy adjust adjustmen mentt of the nozzle area and the different air flows, helped by clear position indicators, make it possible to find and maintain any precise setting during operation as well as between the different production campaigns. The DUOFLEX burner normally operates with 6 - 8 per cent primary air but is designed for maximum 10 per cent. This will in all cases provide the kiln operator with with the neces necessar saryy "tool" "tool" to quickly stabilise any upset conditions.
DUOFLEX
Traditional burner Kiln shell temperature DUOFLEX Traditional burner
MAX/MIN o
C
400
300
200
100 0
10
20
30
40
50
60
70 metres
Data in this brochure is intended intended for preliminary preliminary project planning only. Manufacturer reserves the right to modify equipment details details and/or specif cificati ications ons witithout hout notice.
DENMARK F.L.Smidth & Co. A/ S Viger Vigersle slev v Allé 77, 77, DK-2500 Valby Valby, Copenhage Copenhagen n Te Tel: +45 +45 - 36 18 10 00 Fax: +45 - 36 30 18 20 Internet: Internet: http:// http:/ / www.flsmidth.com w.flsmidth.com Cement Projects Division Fax: +45 - 36 30 18 20 Products Division Fax: +45 - 36 17 47 24 Parts & Services Division Fax: +45 - 36 44 11 19 USA Fuller Company 2040 Avenue C, Bethlehem, Pennsylvania 18017-2188 Te Tel: +1 +1 - 610-2 610-264 64-601 -6011 1 Fax: +1 - 610-264-6170 F.L.Smidth subsidiaries: BRAZIL F.L.Smidth Comércio e indústria Ltda. Te Tel: +55 +55 - 11-532 11-532-850 -8500 0 Fax: +55 - 11-533-9612 FRANCE F.L.Smidth-Fuller F.L.Smidth-Fuller S.A. Te Tel: +33 +33 - 1-4944 1-4944-680 -6800 0 Fax: +33 - 1-4308-5099, +33 - 1-4308-5188
GERMANY F .L.S .L.Smidth-Fu -Fulle ller Gm GmbH Tel: Tel: +49 - 211-591-038 Fax Fax: +49 +49 - 211 211-593 -593-223 -223 INDONESIA FLS Indonesia-Fuller Indonesia Tel Tel:: +62 +62 - 21-25 21-251-27 1-2738 38 / 2739 2739 Fax: +62 + 62 - 21-251-2740 ITALY F.L.Smidth & C. Italiana S.r.L. Tel Tel:: +39 +39 - 35-46 35-46 83 11 Fax: +39 - 35-46 08 38 J APAN F.L.Smidth & Co. J apan Ltd. Tel: +81 - 3-3578-0541 Fax: +81 - 3-3578-0548 MEXICO F.L.Smidth-Fuller Mexico, S.A. de C.V. Tel: +52 - 836-33150 Fax: +52 - 836-33421 PAKISTAN FLS Pakistan (Pvt.) Ltd. Tel Tel:: +92 +92 - 51 51 29 29 31 31 95 95 Fax: +92 - 51 29 31 96 PHILIPPINES F.L.Smidth & C o. A/ S Tel Tel:: + 63 63 - 2-824 2-824-767 -7676 6 Fax Fax: +63 +63 - 2-824 2-824-767 -7676 6 P. R. OF OF CHINA CHIN A F.L.Smidth & Co. A/ S Tel Tel:: 86 - 106 106 467 467707 7070 0 Fax Fax: 86 - 106 106 467 467707 7071 1 SOUTH AFRICA Fuller Fuller-F F.L.Smidth .L.Smidth (PTY) Ltd. Ltd.
F.L.Smidt idth & Co. Co. (S (SA) (PTY) Ltd. Te Tel: +27 +27 - 11-47 11-470-97 0-9700 00 Fax: +27 - 11-475-7665 11- 475-7665 SPAIN F.L.Smidth & Cia Española, S.A. Te Tel: +34 +34 - 1-634 1-634-90-0 -90-00 0 Fax: +34 - 1-636-11-50 THAILAND Mr. Per Mejnert Kristensen c/o c/ o Mitsiam International, Limited Limited Te Tel: +66 +66 - 2-285 2-285-102 -1020 0 Fax: +66 - 2-285-1968-9 2- 285-1968-9 TURKEY F F.L.Smidth & C o. A/ S Liaison Office O ffice Tel: +90 - 212-251-13-31 Fax: +90 - 212-251-62-82 212-251-62- 82 UNITED KINGDOM F.L.Smidth-Fuller Ltd. Tel: +44 - 181-686-2422 Fax: +44 - 181-681-7229 Licensees/ Licensees/ joint ventures ventures INDIA Larsen & Toubro Ltd. (Licensee) Cement Machinery Division, Powai Works Tel: +91 +91 - 22-57 22-57814 81401 01 Fax: +91 - 22-5783437 A member of the F.L.SMIDTH.L.SMID TH-FULLER FULLER ENGINEERING GROUP
