JPS6230812B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the direct feeding of fine-grained material, preferably cement raw material, into a light burning zone, in particular with partial secondary air taken from a cooler. The present invention also relates to a method for light roasting by mixing with exhaust gas from a high-temperature region, and a device related thereto.

Characteristics of the known technical solution For better preparation of the clinker combustion process of the raw material in a rotary kiln with an upstream heat exchanger, the light calcining of the raw material is carried out in a separate light calcining reactor. It is well known that this method is implemented within The light firing reactor is equipped with one or more fuel injection devices. By supplying fuel or heat energy into the light firing reactor, it is possible to achieve up to 90% decarburization of the charged raw material. Further heat treatment of the pre-light calcined material is then carried out in a sintering reactor, e.g.
It is carried out in a rotary kiln, while
The exhaust gas from the rotary kiln and light firing reactor is
Used for preheating raw materials.

From German Patent No. 2510312 it has become known that the decarburization is not carried out in a special light firing reactor, but in the gas channel between the rotary kiln and the subsequent heat exchanger system. There is.
In this case, the required combustion air is fed from the cooler via the rotary kiln and a separate gas line to the connecting line and mixed there.

According to DE 2 416 528 A1, the light burning of the material takes place in conical and cylindrical light burning reactors, in which the furnace exhaust gases are likewise mixed with cooling air. Mixing takes place.

This device has the disadvantage that, due to the mixing of the furnace exhaust gas with the secondary air, a low oxygen concentration is present during the combustion of the fuel in a separate light firing reactor.

From DE 24 36 079 A1 it has become known to operate one of the double-flow preheaters with the exhaust gases of the rotary kiln and the other preheater with the exhaust gases of the light firing reactor. There is. In this case, the light firing reactor is only supplied with partial secondary air as combustion air, so that the combustion conditions of the fuel in this region are improved. However, this device suffers from the complicated start-up conditions of the light roasting device. Because, due to insufficiently preheated partial secondary air,
This is because it must be activated.

In order to improve the degree of light baking of the material in the light baking reactor, it is known from German Patent Publication No. 2724654 that the light baking process is carried out in two stages.
It has become publicly known. In this case, it is possible and advantageous to charge different fuels. In this case, the disadvantage is that the combustion process is separated or interrupted in the case of difficult-to-combust fuels by means of an interposed separator, which slows down the overall light combustion process. and require a greater construction height of the equipment.

From German Patent No. 2 344 583 a light firing reactor is known which consists of a number of chambers.
The reactor is such that its lowest chamber is supplied with turbid air from a condenser. Near the upper end of the uppermost chamber, a furnace exhaust gas conduit is tangentially joined to the light burn reactor. This tangential gas supply has the task of transporting the pre-light calcined material from the light calcining reactor.

When using low-performance fuels in light firing reactors, the construction height of the reactor becomes relatively large. This is because the fuel requires a long combustion distance.

It is known from British Patent No. 960,863 to carry out light calcination of the material in a light calcination reactor which is designed as a swirled bed reactor. In this case, a portion of the secondary air from the cooler is used as combustion air in the light firing reactor. The hot exhaust gas coming out of the sintering mechanism is mixed with the exhaust gas from the light firing reactor before the inlet into the cyclone preheater.

This invention is disadvantageous because by means of the swirled bed reactor as a light baking reactor only a slight degree of light baking of the material is achieved. This is because at higher degrees of light burning, the material tends to seize and this becomes a disturbance within the reactor.

According to German patents 79961 and 81433, it is known that a light firing reactor designed as a cyclone is arranged in the lower part of the shaft preheater and is connected directly to the rotary kiln via a furnace entry channel. It's summery. The material is charged into the reactor from above, by means of a throttle or the like, against the furnace exhaust gas, and leaves it downward likewise via a corresponding throttle. In the cylindrical part of the light firing reactor, a supply line for highly heated secondary air and a tangentially offset burner for ignition are provided.

By arranging an additional stage as a light firing reactor,
The construction height of the preheater is increased. Therefore, additional construction costs as well as additional costs arise due to the transportation equipment for the materials.

Moreover, double-flow preheating systems with light baking stages are already known. In this case, either preheater is not followed by a light firing reactor whose material is simply fed into one system;
Nor are the preheated materials of both systems fed into one reactor.

Object of the invention The object of the invention is to eliminate the above-mentioned drawbacks and to improve the light burning process and at the same time reduce the construction costs.

DESCRIPTION OF THE NATURE OF THE INVENTION The object of the invention is to provide a method which is generally applicable, even in the case of the use of solid fuels and fuels of low calorific value, with the achievement of uncomplicated starting conditions and long combustion distances. It is an object of the present invention to provide a method and apparatus for light-burning fine-grained materials, preferably cement raw materials, to a high degree of light-burning.

According to the invention, this task is achieved by distributing the partial secondary air directly in one stream and the hot exhaust gases from the combustion zone preferably in two partial streams for light combustion. Solved by being supplied. The partial secondary air enters the light burning zone tangentially as tertiary air. In this case, the partial secondary air is converted into a swirling flow into which the preheated material and fuel are charged. A partial stream of the hot exhaust gas is led from the sintering zone axially from below into the light burning zone, so that the intensive mixing is delayed and only takes place gradually. A second exhaust gas partial flow from the sintering zone is added to the gas and material mixture at the end of the light burning zone and, with simultaneous post-burning, is continued for separation and sintering. sent.

By introducing this partial gas into the light firing area,
Best light burning is ensured, in particular, by intensive mixing of the material and fuel with oxygen and sufficient air.

Secondly, the axially fed partial exhaust gases, due to their high heat content, serve to support the light burning process. A portion of the material moves downward in the swirling flow and is charged into the sintering zone.

By regulating the furnace exhaust gas into two partial streams, the possibility of regulating the material charge is simultaneously achieved.

The supply of fuel can take place at one or several points in the light burn zone, or the fuel may be charged to the partial secondary air before it enters the light burn zone.

The apparatus of the present invention consists of a multistage cyclone preheater, a light baking reactor, a rotary kiln, and a cooler. The light firing reactor is preferably formed as a vertical shaft. The shaft is provided with a conical section of reduced or expanded cross-sectional area and a cylindrical section. The light calcining reactor is connected to the inlet channel of the rotary kiln via a constriction in the form of a reduced cross-sectional area. A post-baking reactor is connected to a reactor channel, which leads to a cyclone separator. Before this cyclone separator, a material conduit is led to the inlet of the rotary kiln. A gas line enters tangentially into the lower part of the light firing reactor for the supply of partial secondary air. In this area, the fuel and material inlets are arranged. A partial gas line for the exhaust gas from the sintering zone is led from the furnace inlet channel into the upper part of the light firing reactor. In this partial gas conduit there is a control element.

In the case of double-flow operation, light baking takes place in two stages arranged one behind the other. Furnace exhaust gas and partial secondary air are divided into light baking stages. Starting from the penultimate preheating stage in both material flow directions, the material is charged to one light baking stage. A portion of the material is removed from this stage and charged via a separator and a conduit to a second light sintering stage from which it reaches the sintering zone.

DESCRIPTION OF EMBODIMENTS The present invention will now be described in detail with reference to FIGS. 1 to 3 of the accompanying drawings showing embodiments thereof.

As shown in FIGS. 1 and 2, the high temperature furnace exhaust gas coming out of the rotary kiln 12 is transferred to the furnace inlet guide groove 9.
is divided into two substreams within the region of . A partial stream of the furnace exhaust gas is fed to a shaft-shaped light firing reactor 1 which is provided with an axially conical and cylindrical widening or narrowing of cross-sectional area. Light firing reactor 1 is flowed through by this partial flow, preferably axially from below to above, and in the lower region by partial secondary air fed tangentially. However, this partial secondary air is converted into a swirling flow by the tangential connection of the partial secondary air conduit 4. In this case, the partial stream of furnace exhaust gas has a higher vertical velocity than the partial secondary air fed to the light firing reactor 1. Preferably, the material fed into the upper part of the partial secondary air inlet is carried upwards in a swirl by the oxygen-rich partial secondary air and, by simultaneous fuel supply, is lightly burned. be done. In this case, a portion of the light calcined material is separated from the gas stream and fed through the constriction section 2 of the light calcining reactor 1, through the inlet cone 15 and via the inlet channel of the furnace to the sintering section. .

A further partial stream of the furnace exhaust gas is fed into the upper region of the light burning zone via a partial gas line 5. Due to the gas flow and the intensive mixing of the materials, a light burn takes place in the area of the light burn channel 6, which connects the light burn reactor 1 to the cyclone separator 7. are doing. From light baking reactor 1,
The transition portion to the light-burning guide groove 6 is formed by the cone 3. In the cyclone separator 7, the pre-baked material is separated from the gas stream and fed to the sintering section via a material conduit 8, while the gas stream is passed through a cyclone preheater 16 for preheating the material. guided into.

For regulating the combustion conditions in the light firing reactor 1, a control element 10 is arranged in a partial gas line 5 into which a partial flow of the furnace exhaust gas is conducted. By means of this control element 10, a division of the furnace exhaust gas flow takes place. A bypass line 11 is arranged in the lower region of the partial gas line 5 or in the area of the inlet channel of the furnace. Thereby, for the application of this method in the preparation of cement raw materials with a high content of harmful elements, the furnace exhaust gas is
It can be removed from the area of the inlet channel 9 or the partial gas line 5 of the furnace. The material inlet conduit 14 for the preheated material is preferably arranged in the region above the inlet of the partial secondary air conduit 4 . The fuel inlet 13 is arranged in the region of the inlet of the partial secondary air conduit 4 into the light firing reactor 1 so that the fuel can flow directly into the light firing reactor 1 and/or into the partial secondary air conduit 4. During, before this partial secondary air conduit 4 flows into the light baking reactor 1,
arranged to be loaded.

The device according to the invention, shown in FIG. 3, consists of a double flow preheater having a cyclone preheater 16. Material conduit 23 connects cyclone stages 19 and 20
from there into the light baking reactor 21. These material conduits 23 preferably enter in the region of the tangential connection of the partial secondary air conduit 4 as well as the fuel inlet 13 . The light baking reactor 21 is
It is connected to the inlet channel 9 of the furnace via a conduit.
A separator 18 is downstream of the light firing reactor 21 in the direction of the gas flow. The output of the separator 18 is connected via a material conduit 24 to a light burn reactor 22 . This material conduit 24 flows into the light burn reactor 22 analogous to the material line to the light burn reactor 21 . A separator 17 is downstream of the light firing reactor 22 in the direction of the gas flow. The material conduit 25 from the separator 17 terminates in the inlet region to the rotary kiln 12.

The charged raw materials, after preheating in the cyclone preheater 16, are first charged together into the light calcining reactor 21. A partial stream of furnace exhaust gas is fed into the light firing reactor 21 from below in the axial direction.
Partial secondary air from the cooler is fed tangentially to the light firing reactor as tertiary air. In this area, the required fuel supply also takes place. A portion of the lightly calcined material from the light calcining reactor 21 directly reaches the rotary kiln 12 via the furnace inflow guide groove 9 downwardly. The remaining material passes into a downstream separator 18 and is fed from there via a material conduit 24 to a light baking reactor 22 . The light baking reactor 22 is the light baking reactor 2.
It is arranged similarly to 1. The material separated through the separator 17 is charged to the rotary kiln 12.

The essential advantage of the method and apparatus of the invention is that it can be very well utilized even in light burn reactors and the heat of the fuel.
The heat of the rotary kiln exhaust gas is also to be achieved. Light firing reactors and post-reaction channels ensure the required residence time of the material.

Partial gas introduction to the furnace exhaust gas, long combustion path and strong mixing of fuel and oxygen with sufficient preheated air allow good combustion of even hard and low-performance fuels.

The light firing reactor with preheater and cooler according to the invention allows uncomplicated starting and operating criteria. At the same time, the share of light firing reactor and fuel can be adjusted respectively depending on the operating conditions.

Another advantage is that the invention can be installed both for single-flow preheaters and for double-flow preheaters;
Also, both branches can be activated uniformly. In this case, despite the long reaction path achieved, the construction height of the cyclone preheater is not exceeded.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the apparatus of the present invention, FIG. 2 is a longitudinal cross-sectional view of an embodiment with a modified light baking reactor, and FIG. FIG. 1, 21, 22... Light firing reactor; 2... Squeezed part; 3... Conical part; 4... Partial secondary air conduit; 5... Partial gas conduit; 6... Reaction guide groove;
7...Cyclone separator; 8...Material guide groove; 9...
...Furnace inlet channel; 10...Adjustment mechanism; 11...Bypass conduit; 13...Fuel port; 18...Separator; 19, 20...Cyclone stage; 23...Material conduit.

Claims (1)

Claims: 1. A heat treatment method for fine-grained material, preferably cement raw material, in particular for light burning by direct supply of partial secondary air and mixing with exhaust gas from a sintering zone, comprising: The high temperature furnace exhaust gas from the sintering zone is divided into two sub-streams, the partial secondary air from the cooling zone is converted into a swirling flow by tangential feeding into the light sintering zone, and at the same time the high temperature A partial flow of the furnace exhaust gas passes through the swirling flow axially from below upwards into the central region with a greater vertical velocity, in this case together with the upward movement of the material simultaneous fuel supply and A subsequent intensive mixing causes a light burning of the material, after which a second partial stream of high-temperature furnace exhaust gas is supplied, and another intensive mixing causes a subsequent light burning of the material, which is subsequently introduced together. The sintered material is separated from the gas stream and fed to the sintering zone, while
The gas stream preheats the material, and a portion of the material is separated from the gas stream after light calcination and fed to the sintering zone, and the partial stream of high temperature furnace exhaust gas is adjustable. How to do it. 2 In the case of double flow, the high-temperature furnace exhaust gas and the partial secondary air are divided into the respective light firing reactors, and the material separated from the penultimate preheating stage in the direction of the material flow in both cases is combined. The material which is charged into one light roasting stage and separated therefrom is fed to the second light roasting stage with a higher degree of light roasting, and the light roasted material of this second stage is directly fed into the second light roasting stage. or alternatively, the material reaches the sintering zone via a separating stage, in which case the supply of material into both light sintering stages lies in the region of the partial secondary air supply. The method according to claim 1. 3 In particular, in a heat treatment apparatus for cement raw materials, which has a multi-stage cyclone preheater, a light baking reactor, a rotary kiln, and a cooler,
The light firing reactor 1 is formed as a vertical shaft having a section with a conically reduced or enlarged cross-section and a cylindrical section, which is connected through a constriction in the form of a reduced cross-section. It is connected to the furnace inflow channel 9 and ends in the reaction channel 6 in the upper part, and a partial secondary air pipe 4 is tangentially connected in the lower part of the light firing reactor 1. , in this area a fuel inlet 13 as well as a material inlet 14 are arranged, and the partial gas line 5 starting from the furnace inlet channel 9 terminates in the upper area of the light firing reactor 1. A device featuring: 4. Claim 3, in which the constricted part 2 and the conical part 3 are connected to the reaction chamber of the light baking reactor 1.
Apparatus described in section. 5. Claim 3 or 4, in which the adjustment mechanism 10 is arranged in the upper region of the partial gas conduit 5
Apparatus described in section. 6. Device according to claim 3, 4 or 5, characterized in that a bypass line (11) is arranged in the region below the partial gas line (5) or in the area of the furnace inlet channel (9). 7. Apparatus according to any one of claims 3 to 6, wherein the cyclone separator 7 is connected to the furnace inlet channel 9 via a material conduit 8. 8 A fuel inlet 13 is provided at one or more points in the light burn reactor 1 above the inlet of the partial air conduit 4 into the light burn reactor 1 and/or into the partial secondary air conduit 4. , which is located before the inlet into the light firing reactor.
Apparatus according to any of paragraphs. 9 Equipped with a double-flow preheater and a light firing reactor, the light firing stage consists of two light firing reactors 21 and 22, which are connected to separate high temperature furnace exhaust gas supply and tertiary air supply and During the supply of fuel, in the direction of material flow, a material conduit 23 flows from the cyclone stages 19 and 20 into the light burn stage 21 and a material line 24 flows from the separator 18 into the light burn reactor 22. 7. A device according to any one of claims 3 to 6, which is connected in sequence so as to perform the following steps.