DE102004023686B4 - Device for producing cement clinker - Google Patents

Abstract

Apparatus for producing cement clinker, comprising a dehydrator (2) in the form of a circulating traveling grate, a heated calciner (3) in the form of a rotary tube with an inclined axis of rotation, a rotary kiln (1) and a cooler (4),
- In which the exhaust gas of the rotary kiln is fed into the dehydrator
- And in which on the coats of calciner (3) and the rotary kiln (1) are mounted in a helical line cooling fins,
- around which in each case a fixed casing for forming helical collecting channels (1 ', 3') is arranged,
- Can be sucked on the entry of Calcinatorsammelkanals (3 ') cooling air, which is passed through the Calcinator- and the rotary kiln collecting channel and fed from here as heated air use of the heat recovery.

Description

The The invention relates to a device for the thermal treatment of Cement raw meal for the production of cement clinker with complete deacidification in the calciner and the Lowering the specific heat expenditure for the Clinker fire.

State of the art

Under Application of the different precalcinier processes, associated, relatively shorter rotary kilns, the Use of 5-6 stage cyclone preheaters as well as the most modern clinker coolers are today with such systems depending on the type and preparation fuel and fuel specific fuel requirements from about 2930-3140 kJ / kg Clinker reached.

As from the ZKG-10/89, p.510-514 is known, were precalcined with a 2-stage calciner in experiments Vorcalcinierraten of about 98% at temperatures below 850 ° C reached. The high degree of calcination was achieved without increasing the Temperature of the furnace feed, but with extension of the residence time to double in the passage through the two calcination stages.

The produce the best cyclone heat exchangers operated today the cement clinker with a specific heat input of approx. 3000 kJ / kg Clinker in exhausted Reduction potential of the specific heat expenditure. This general The opinion is represented by the BDZ / VDZ and also by the leading plant manufacturers. Other fuel systems for cement clinker are higher than the aforesaid value of about 3000 kJ / kg clinker.

Of the Disadvantage of the standard "cyclone heat exchanger" is that he his optimal performance only in the for the design of the gas speed specified sizing can reach the cyclone. When falling below the optimum gas velocity takes the degree of separation of the cyclones and thus the throughput from and the specific heat requirement rises. A disadvantage of the cyclone heat exchanger also that the diverse, branched streams of good a previously consuming homogenized raw meal in the heat exchanger is homogenized. This process is also known from the ZKG-1992 / Nr. 5 p. 225 under 2.1.3., In which u. a. means that the thermal efficiency the well-known cyclone preheater is reduced by internal dust cycles and throughput. Important is to note that the combustion process with the cyclone heat exchanger a Vorcalcinier method with over 300 ° C hot exhaust gases remains in which at temperatures below about 1040 ° C no total deacidification possible is.

Of the Heating system "waste gas utilization / raw material drying" is only optimal at full utilization of the heat supply and only in this case is the loss of exhaust gas from that in the combustion system spent thermal energy deducted.

adversely and problematic are further caking and the formation of deposits in the temperature range from about 850 ° C also for normal raw meal to the pre-melt phase range in all known preheater constructions. Especially Critical is the problem of buildup in the temperature range about 700-900 ° C at Na, K- and Cl- containing compounds.

By the DE 43 15 212 A1 and DE 43 15 212 C2 a method for the production of cement clinker is known in which the raw meal is completely calcined in the calciner by higher temperatures and only in the rotary kiln is sintered.

Furthermore, it is known in the production of clinker to produce from the starting materials or partially processed materials pellets (pellets, etc.) and to introduce them into the process. According to the DE 25 54 989 A1 This is done after preheating, before sintering. This solution is intended to enable sintering in a fluidized bed. According to the DE 44 33 049 C2 The wet raw materials are pressed into filter cake and then crushed into pieces smaller than 10 mm. These are now partially calcined and then introduced into the rotary kiln. The use of lumpy material results from the required comminution of the filter cake for processing.

In the GB 874,818 A For example, a method and apparatus for producing low alkali cement is described. Raw material is processed into granules passed through a grate preheater divided into a drying chamber and a calcining hot chamber. Then the material enters the rotary kiln and from here into the cooler. The cooling air from the radiator is used for the burner and the drying chamber, the exhaust gases from the rotary kiln for the hot chamber. The use of granules serves to reduce the uptake of alkali parts by the raw material. The temperatures for drying and calcination in the hot chamber are in previously common areas, so that the calcination in front of the rotary kiln is not complete.

The granulation of cement raw meal for the production of cement clinker has hitherto been carried out for reasons of special procedures, the aspect of hydration and formation of deposits has not been considered. For those from raw material or Ze molded bodies are known from various synonymous terms, with granule being derived from the granulation production process. Other terms are pellets, moldings, briquettes and pellets. In the following, only the two terms granules and pellets are used.

Object of the invention

The The object of the invention is a device with a Fluidic throughput independence create an at least constant, or constantly optimal specific heat demand for the Clinker burning, even with considerable reduction of Brenngutdurchsatzes to accomplish.

Farther should prevent the segregation of the raw meal components and a Minimization of material caking and buildup in the heat exchanger and rotary kiln, even at temperatures of 1100 ° C and more in the calciner and Raw meals can be achieved with high alkali content.

The The object is achieved by the Characteristics of claim 1 solved.

After that be formed by the device of raw meal molded pellets or Granules of size 4 up to 20 mm in the dehydrator at temperatures of at least 600 ° C up to max. 750 ° 0 below treated mechanical movement. In the calciner is at temperatures from 1100 ° C and more the product totally deacidified. In a rotary kiln then the residual clinker formation takes place.

On the coats of calciner ( 3 ) and the rotary kiln ( 1 ) are mounted in a helical line cooling fins and around this one fixed shell for the formation of helical collecting channels ( 1' . 3 ' ) arranged. About the entrance at the Calcinator ( 3 ) Cooling air is sucked, fed into the calciner and the rotary kiln collecting channel and fed from here as heated air use of the heat recovery.

The Advantages of the new heat exchanger system across from since over 50 years old and the world's leading cyclone heat exchangers u. a. the noticeable heat energy savings opposite and those with the energy savings in the same percentage reduction of CO2 and NOX emissions. An important Process for environmental protection.

With the unbranched Gutführung into the sintering zone is a in all individual heat exchange phases thermally and chemically homogeneous Gutzustand achieved and remains the advantage of dividing the processes into small steps is maintained.

• – die strömungstechnische Durchsatzunabhängigkeit,
• – die Vermeidung von Entmischungen der Rohmehlkomponenten und interne Staubkreisläufe,
• – die größere Flexibilität in der Anlagenführung im Hinblick auf die Abnehmererfordernisse aber auch auf das Eigeninteresse des Betreibers,
• – die räumliche Anordnung der verschiedenen Anlagenteile vom Vorwärmer bis zum Kühler, hierdurch erfolgt die Gutführung ausschließlich durch Schwerkraft sowie durch mechanische Wirkprinzipien,
• – ein Anlagenkonzept mit erhöhter Flexibilität in der Betriebsführung zu schaffen, um auf die künftig qualitativ und quantitativ breiter gefächerten Anwenderanforderungen besser und kostengünstiger reagieren zu können,
• – die merkliche Ersparnis an Mahlenergie durch eine optimal grobe Mahlfeinheit des Rohmehls,
• – der Entfall eines Kühler-Abluftfilters,
• – der Entfall einer großen Klinker-Bevorratung mit den umfangreichen Transportmitteln zur Ein- und wieder Auslagerung des Klinkers, (dafür der direkte Weg des Klinkers vom Kühler in den Mühlen-Aufgabebunker), mit Wegfall der durch die Klinkerbevorratung vorweg entstehenden Brennstoffkosten,
• – der Entfall der umfangreichen Entstaubungseinrichtungen für Klinker-Transport und – Lagerung.

The time for the heat exchange from Guteintritt in the preheater to Gutaustritt in the rotary kiln is compared to the cyclone heat exchanger over a thousand times higher. As a result, a more compact design and construction of the new system with much smaller volume conversions and thus low construction costs are possible and also reduce the radiation losses. The significant saving of heat energy is achieved by lowering the exhaust gas temperature, considerably increasing the heat exchange time in the preheater and in the calciner, and by reducing the cooler losses through the pipe cooler. In addition to saving heat energy, the specific electrical energy requirement is also reduced. The main advantages are summarized:

• - the flow-throughput independence,
• The avoidance of segregation of the raw meal components and internal dust cycles,
• - the greater flexibility in plant management in terms of customer requirements but also the self-interest of the operator,
• - The spatial arrangement of the various parts of the system from the preheater to the radiator, thereby the Gutführung takes place exclusively by gravity and by mechanical principles of action,
• - to create a plant concept with increased operational flexibility, in order to be able to react better and more cost-effectively to the future qualitatively and quantitatively broader user requirements,
• The noticeable saving of grinding energy by an optimally coarse grinding fineness of the raw meal,
• The omission of a radiator exhaust filter,
• - The elimination of a large clinker storage with the extensive means of transport for loading and unloading of the clinker, (for the direct route of the clinker from the cooler in the mill-task bunker), with the elimination of the costs incurred by the clinker storage fuel costs,
• - The elimination of extensive dedusting facilities for clinker transport and storage.

According to a preferred embodiment according to claim 2 is to prevent the formation of deposits in the calciner ( 3 ) The inner wall with approach-reducing material, such as ceramic material or high temperature resistant special steel, lined or this consists of this material.

Examples

The invention is diagrammatically illustrated in the appended drawings, and described in more detail below. Opposite the general be The custom is followed by the rotary kiln 1 because only 10% of the total heat demand through the fuel input Q1 5 is supplied, also referred to as a secondary furnace. The calciner 3 with 90% fuel content via fuel input QII 6 is accordingly used as a primary oven 3 designated.

In the 1 illustrated plant for the production of cement clinker contains a rotary kiln 1 and is with a dehydrator 2 and a calciner 3 provided as a heat exchanger. The dehydrator 2 is designed in this case as a traveling grate for gentle treatment of the compacts until their curing. The fuel inputs take place with 5 in the rotary kiln 1 and 6 in the calciner 3 , That from the calciner 3 , a rotating, inclined heat exchanger, coming good is in the rotary kiln 1 , the kiln exhaust directly into dehydrator 2 guided.

The 2 shows an opposite arrangement of the system parts 1 and 4 ,

The 3 shows a rotary cooler 4 to 13 from the patent DE 43 00 011 C2 with integrated crushing device.

The 4 shows the components required for heat recovery of the jacket radiation losses, such as the helically mounted on the jackets, snail-shaped sheets (which may also be individual wings) and the fixed, non-co-rotating jacket of the hot air collecting ducts 3 ' and 1' ,

The 5 shows the cross section. The collection channels are free in the area of the respective role stations for the free access of the stations down, this right picture 5 (Air passage in hatched area). From the mill or dryer fan is via the open collecting channel 3 ' , on this left picture 5 (shaded area), fresh air sucked in and over the collecting channel 1' supplied from the heat recovery system of raw meal drying or other heat recovery.

1

Rotary kiln = Secondary oven

1'

Collecting channel too 1

2

dehydrator

3

calciner = Primary oven

3 '

Collecting channel too 3

4

tube cooler

5

Fuel input QI

6

Fuel input QII

Claims (2)

Device for producing cement clinker comprising a dehydrator ( 2 ) in the form of a circulated traveling grate a heated calciner ( 3 ) in the form of a rotary tube with inclined axis of rotation, a rotary kiln ( 1 ) and a cooler ( 4 ), - in which the exhaust gas of the rotary kiln is fed into the dehydrator - and in the coats of the calciner ( 3 ) and the rotary kiln ( 1 ) in a helical line cooling fins are applied, - around which in each case a fixed shell for the formation of helical collecting channels ( 1' . 3 ' ), wherein - via the inlet of the calciner collection channel ( 3 ' ) Cooling air can be sucked, which is passed through the calciner and the rotary kiln collecting channel and fed from here as heated air use of the heat recovery. Device according to Claim 1, characterized in that, in order to prevent buildup in the calciner ( 3 ) the inner wall with approach-reducing material, such as ceramic material or high temperature resistant special steel, lined or consists of this.