Kiln Gas Bypass Systems 2

Kiln gas bypass systems 2

Maximum efficiency and reliability

Main features The key to good performance Dual layer dip tube All bypass systems are not created A dip tube eliminates short-circuiting - Quench chamber with dual equal. At the take-off point from of quench air directly to the outlet of layer dip tube the kiln system, a properly designed the chamber. The dip tube ensures quench mixing chamber is critical for that the complete amount of quench - Quench air inlet flap valve the highest performance efficiency air always enters the gas swirl and and minimum interference to stable mixes with the kiln gas. As the dip - Control scheme for kiln operation. FLSmidth has developed tube is exposed to the cold quench maximum stability such a chamber through a number of air on the outside and the hot kiln gas - Special lining design in innovative design features. Kiln gas on the inside, it is designed as a dual transition pipe section bypass systems have traditionally only cone system with a thermal insulation been used in regions where the local between the two steel sections This - Constant force support system raw materials are naturally high in ensures long lifetime of the compo- chloride, sulfur or alkalis. The growing nents. By keeping the inside hot, the - Multiple layout possibilities use of alternative fuels and other risk of sticky buildups on the inside materials is also increasing the input is minimised. of chloride to kiln systems to the point that may require a bypass in order to Quench air inlet flap valve maintain process stability or product The quench air inlet flap valve offers quality. control of the inlet velocity, which enables the swirl and the mixing of FLSmidth has extensive experience with hot gas and cold air to be optimised the design and use of kiln bypass in a wide capacity span. The flap valve systems. While the fundamental is operated with an electrical linear principles of a bypass system have not actuator. changed, state-of-the-art technology and design tools have been incorpor- ated to improve bypass efficiency Bypass system quench chamber and maximise reliability. Most projects today will at least have the space for a future small chloride bypass (less than 10%) with respect to use of alternative fuels and materials. 3

System control system, which eliminates the need Reduced off-gas volume The flow rates of the quench air and for a thermal expansion joint on the Good mixing allows operation with mixed gas after the quench chamber transition pipe without stressing the high exit temperature from the mixing are measured continuously, so that structure of the riser duct. chamber so that a higher proportion the exact amount of gas extracted from of the cooling may be provided by the kiln system is known at all times. Superior mixing of hot kiln gas water instead of air. In this way the Control loops will maintain flow stability and cold air volume of gas to be treated by a filter so that the burning zone conditions Superior mixing of hot gas and cold air installation and later discarded is greatly of the kiln, notably oxygen level and is created by the inlet flap and the dip reduced. This can be translated into temperature, remain constant despite tube for a wide capacity span. Good reduced investment and/or operational any operational disturbances. mixing is synonymous with an even costs (kWh per kg gas removed) for temperature profile, which is one of the the quench air blower, filter, bypass Thermal insulation in transition pipe overall criteria for optimum operation fan, ductwork and stack. To keep the surface of the transition of the chamber. Local areas with high pipe before the quench chamber hot, temperatures and increased stickiness Reduced risk of build ups in it is equipped with a highly insulating of dust are effectively avoided. It also transition pipe lining design. This effectively reduces eliminates the problem of having The special lining concept and no any potential for buildup in this area. surface areas exposed to either higher requirement of a thermal expansion or lower temperatures than anticipated, joint in the transition pipe generates Constant force support system which could create structural failure a hot and smooth surface that greatly The complete quench chamber is on hot areas and severe condensation reduces the risk of getting buildups supported in a constant force spring on cold surfaces. in this critical area.

CFD stream lines CFD temperature map Layout Arrangements Typical bypass system FLSmidth offers a number of different control scheme solutions for bypass installations to fit specific plant requirements and layout. The traditional arrangement Controller with spray tower and fabric bag filter is shown in the schematic.

Other system types could

H O include: Optional 2 Cyclone - Small systems without the spray tower and only bleed air cooling - Systems that return the de-dusted gas back to the preheater, calciner, clinker cooler, or raw mill system - Systems with return of coarse dust fractions from the inlet section of the filter back to the kiln system - Systems with cyclone to catch coarse dust fraction for return back to the kiln or cement grinding systems

Full or partial kiln bypass systems are available for both new and existing plant installations, supported by a full process design assessment based on the type of kiln and the raw fuel and materials analyses. Complete supply is available from FLSmidth with all the required equipment and controls.

FLSmidth’s solutions for kiln gas bypass systems are further examples of the commitment to being the preferred partner and leading supplier of equipment and services to the global cement industry.

or warranties (express or implied), and information and data contained in this brochure are for general reference only and may change at any time. www.flsmidth.com C 01-11 400-9-ENG

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