¡ Improved heat economy ¡ Widely adjustable flame shape ¡ Easy change-over between fuels ¡ Suitable for alternative fuels

MAIN FEATURES • Robust design • Low primary air consumption • Adjustable swirl • Adjustable air nozzle area • Central fuel injection D U O F L E X Nozzleopen Application The DUOFLEX burner fires rotary kilns with pulverised coal or coke, oil, natural gas or any mixture of these fuels. The burner may be fitted with extra ducts for secondary fuels such as plastic chips, wood chips, sewage sludge, etc. 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. Design The burner is based on a novel...

ratio - and consequently the degree of swirl - is also adjustable. These adjustments offer wide scope of shaping the flame. Process and function 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 carbon monoxide (CO) and nitrogen oxides (NOx). If relevant, the burner must be able to handle alternative fuels without requiring change of its original...

4 discharge and one with vanes or tangential slots for swirl air. Swirl is controlled by adjusting the swirl air amount (or the ratio between axial air and swirl air). This can be done in two ways, by dampers installed in the ducts upstream of the burner or – more effective - by adjusting the air nozzle areas. Most modern multi-channel burners therefore have adjustable air nozzles. If all the primary air is supplied by one primary air fan, momentum and swirl cannot be adjusted independently. Adjusting the swirl air nozzle will also change the pressure at the axial air nozzle and vice versa. To...

5 Momentum control, example: Calciner kiln, 7000 tpd Burner output: 118 MW Max. momentum: 8,7 N/MW (at 12,5% PA) Momentum required: 5 N/MW 1. Reducing nozzle area: Air flow: 8195 m3/h (6,9% PA) Air pressure: 278 mbar Power consumption: 80 kW Savings by reducing nozzle area instead of pressure: Power: 22 kW Fuel: 2,4% PA y 2,4x0,75= 1,8 kcal/kg clinker y 12,6 Mcal/24h 2. Reducing nozzle pressure: Air flow: 11120 m3/h (9,3% PA) Air pressure: 140 mbar Power consumption: 102 kW Primary air fan 0 50 150 200 250 300 0 2,5 5 7,5 10 12,5 15 17,5 20 22,5 100 mbar, kW Flow 1000 m3/h Increased air flow...

Since good flame formation 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 requires a momentum of minimum 1400 - 1600 % m/s dependent on fuel type. A flame momentum below this range will result in too long a flame, high kiln shell temperatures above the burning zone and in the kiln...

7 Alternative fuels In order to explore the economical opportunities on the waste market to the maximum a high degree of freedom is desired when adjusting the kiln feed rates of various alternative fuel types. On the other hand stands the request that the heat input to the kiln shall remain stable, that the firing of the fuels must not have a negative impact on the clinker quality and that the coating profile in the kiln remains unchanged. The combination of the quest for optimum flexibility and the desire to maintain steady kiln operation conditions puts high demands to the kiln burner which...

Duoflex Traditional burner 100 0 10 20 30 40 50 60 70 metres 200 300 400 MAX/MIN oC DUOFLEX Kiln shell temperature Traditional burner 10-05-252 www.zerodesign.dk DENMARK FLSmidth A/S Vigerslev Allé 77 DK-2500 Valby Copenhagen Tel: +45 36 18 10 00 Fax: +45 36 30 18 20 E-mail: [email protected] USA FLSmidth Inc. 2040 Avenue C Bethlehem, PA 18017-2188 Tel: +1 610-264-6011 Tel: +1 800-523-9482 Fax: +1 610-264-6170 E-mail: [email protected] INDIA FLSmidth Ltd. Capital Towers 180, Kodambakkam High Road Nungambakkam Chennai 600 034 Tel: +91 – 44-52 191234 Fax: +91 – 44-2827 9393 E-mail: [email protected]...