DE202010011776U1 - Firing plant for cement clinker with pre- and post-calcinator - Google Patents

Abstract

Combustion plant (10) for the production of cement clinker from raw meal with
a raw meal preheater (14) consisting of one or more cyclone stages (14A-14E) for heating the raw meal,
a precalciner (16) in which the preheated raw meal is deacidified into hot meal and equipped with a precalciner burner (20),
a rotary kiln (18) in which the hot meal is fired into clinker and which is equipped with a rotary kiln burner (28), and
a clinker cooler to cool the fired clinker,
marked by
a Nachkalzinator (34) to which the hot meal of the lowest cyclone stage (14E) is applied, and
a Nachklalzinator (34) downstream cyclone separator (36) in which the hot meal from the Nachkalzinator (34) separated from the gas phase and then the rotary kiln (18) is abandoned, the exhaust air from the Nachkalzinator (34) and the downstream cyclone separator ( 36) is passed into the precalciner (16).

Description

The invention relates to a firing plant for producing cement clinker from raw meal with a raw meal preheater comprising one or more cyclone stages for heating the raw meal, with a calciner in which the preheated raw meal is deacidified into hot meal and which is equipped with a calciner burner, with a rotary kiln, in which the hot meal is fired to clinker and which is equipped with a rotary kiln burner, and with a clinker cooler for cooling the fired clinker.

In the production of cement clinker in drying plants, raw meal is preheated, residue dried, calcined, fired to clinker and then cooled. The energy supply for the material conversion in such systems is carried out by supplying fuel into the rotary kiln and in the calciner.

Air heated in the clinker cooler is partly fed to the rotary kiln as so-called secondary air and partly to the calciner as so-called tertiary air. The exhaust gases of the rotary kiln are passed through a rotary kiln inlet chamber to the calciner, flow through this and are discharged together with the exhaust gases generated in the calciner in the cyclone preheater.

The cyclone preheater consists of one or more floods and each flood of several, usually 4, 5 or 6 cyclone stages, which each act as a floating gas heat exchanger. The dried cement pipe meal is fed to the riser of the uppermost cyclone stage, passes through the cyclone stages from top to bottom and is passed from the penultimate (second lowest) cyclone stage into the calciner. The flour of the lowest cyclone stage is fed to the rotary kiln inlet chamber of the rotary kiln. Depending on the number of cyclone stages, the cyclone preheater heats the raw meal to 850 to 880 ° C.

Between the rotary kiln and the Zyklonvorwärmer the calciner is arranged. The raw meal is deacidified by using about 60% of the total fuel heat in the calciner to a CO ₂ content of 4 to 6% to hot meal. The combustion air is supplied as tertiary air via a tertiary air line from the clinker cooler to the calciner. The hot meal deacidified in the calciner is separated from the gas stream and slips through the rotary kiln inlet chamber into the rotary kiln.

The cylindrical rotary kiln comprises an inlet zone, a calcining zone, a transition zone, a sintering zone and an outlet zone. The rotary tube is slightly inclined in the longitudinal direction, so that there is a slight gradient of about 2-5% from the inlet zone to the outlet zone, normally 3-4%. The hot meal is fed to the rotary kiln in the inlet zone and then continuously fed through the rotating rotary kiln due to the slope. In the calcining zone, the residual deacidification of the hot meal takes place. The thermal conversion to cement clinker takes place in the sintering zone. In the rotary kiln, about 40% of the total fuel heat is used. The length / diameter ratio of such rotary kilns is about 11: 1.

Rotary kilns have large thermal wall losses. The furnace cylinder and especially the furnace lining are subject to high thermal and mechanical loads. The exact process data are dependent on the specific characteristics of the respective raw meal or the raw materials, the fuels used, as well as the different environmental conditions. The cooling of the falling from the rotary kiln with a temperature of 1350 to 1400 ° C clinker takes place in coolers of different types. The clinker is cooled with ambient air to 60 to 70 ° C above ambient air temperature.

The thermal wall losses and the wear of the lining of the rotary kiln are substantial parts of the operating costs of a cement clinker burning plant. The higher the thermal wall losses, the higher the fuel energy consumption and thus the operating costs. The size of the rotary kiln also plays an important role here. The larger the size of the rotary kiln, the more lining mass is required and the higher the associated lining costs. But the lining wear increases with the size of the furnace, which leads to increased thermal wall losses and thus also to increase the operating costs. To counteract the Ausmauerungsverschleiß the rotary kiln must be maintained more frequently, which has a low temporal capacity utilization and thus also contributes to increase the operating costs.

The present invention is therefore based on the object of reducing the operating costs of a cement clinker burning plant.

According to the invention, this object is achieved in that the cement clinker firing with a Nachkalzinator, the hot meal of the lowest cyclone is abandoned, and with a Nachkalzinator downstream cyclone separator in which the hot meal from the Nachkalzinator is deposited from the gas phase and then fed to the rotary kiln equipped is. The previous calciner now acts as a precalciner.

The residual deacidification of the hot meal is not carried out in the rotary kiln, but takes place already in the arranged before the rotary kiln Nachkalzinator. The calcination zone needed in conventional rotary kilns is dispensable by the use of the post-calciner. This reduces the required length and thus the surface of the rotary kiln. The smaller surface of the rotary kiln reduces the thermal wall losses and associated operating costs of the cement clinker burning plant.

The post-calcinator is located between the rotary kiln inlet chamber and the precalciner. The rotary kiln exhaust gas flows directly into the Nachkalzinator. The hot flour of the lowest cyclone stage is not the rotary kiln, but the Nachkalzinator abandoned.

The hot meal is mixed in the Nachkalzinator with the rotary kiln exhaust gas, where it is completely deacidified. By a downstream cyclone stage, the residual deacidified hot meal is separated from the gas stream and fed via a hot meal pipe of the rotary kiln inlet chamber of the rotary kiln.

The completely deacidified hot meal tends increasingly to accumulate so that both the cyclone separator and the raw meal pipe between the cyclone separator and the rotary kiln inlet chamber have to be structurally adapted to the conveying condition of the residual deacidified hot meal.

The cyclone separator downstream of the postcalzinator therefore differs from the cyclone separators of the raw meal preheater (with the exception of the lowest cyclone stage) by a larger angle of the inflow spiral slope measured to the horizontal. The Einströmspiralenschräge has with respect to the horizontal at an angle of about 60 °, preferably 62 ° to 65 ° on.

The downstream of the Nachkalzinator cyclone preferably has a larger cone angle than the Zyklonabscheider the two to five lower stages of Rohmehlvorwärmers. The cone angle of the cyclone separator has an angle of more than 70 °, preferably 72 ° to 75 °, relative to the horizontal.

The diameter of the flour pipes must generally be selected as a function of the clinker throughput and the degree of separation of the cyclone separators used. In order to prevent buildup of the residual deacidified hot meal in the flour pipe between the rotary kiln inlet chamber and downstream of the Nachkalzinator Zyklonabscheiderstufe, the diameter of this flour pipe must be greater than the diameter of the flour pipes of the preheating stages.

In the firing system according to the invention, the raw meal is heated in a raw meal preheater consisting of one or more cyclone stages, deacidified the preheated raw meal in a precalciner to hot meal, the hot meal baked in a rotary kiln to clinker and cooled the fired clinker in a clinker cooler, the residual deacidification of the hot meal done in a Nachkalzinator.

The thermal energy for the residual deacidification is introduced into the system either by the rotary kiln burner or can be generated directly in the post-calciner by means of an additional post-calciner burner.

The fact that the rotary kiln does not need its own calcining zone reduces the length of the kiln. In systems without additional Nachkalzinatorbrenner results in a length / diameter ratio of the rotary kiln of about 8: 1. In systems with Nachkalzinatorbrenner results in a length / diameter ratio of the rotary kiln of about 7.5: 1.

The required combustion air (quartz air) for the Nachkalzinatorbrenner is like the tertiary air, Rekuperationsluft, which is fed via a quarti air line from the tertiary air line in the Nachkalzinator.

Both precalciner and postcalzinator can be used as a flow tube (tube calciner) (gas velocity around 14 m / s) with a vertically rising and substantially vertically sloping path, as a compact container (tank calciner) (gas velocity around 7 m / s) or as a hybrid of both ( eg compact container with subsequent flow tube).

Embodiments of the invention are explained below with reference to the drawings. Show it:

1 a schematic diagram of a combustion system according to the prior art;

2 a schematic diagram of a combustor according to the invention using Rohrkalzinatoren without Nachkalzinatorbrenner;

3 Sectional view ( 3A ) and plan view ( 3B ) of the Nachkalzinator downstream cyclone separator;

4 a schematic diagram of a combustor according to the invention using Rohrkalzinatoren with Nachkalzinatorbrenner;

5 a schematic diagram of a combustor according to the invention using Behälterkalzinatoren without Nachkalzinatorbrenner;

6 a schematic diagram of a combustor according to the invention using Behälterkalzinatoren with Nachkalzinatorbrenner;

7 a schematic diagram of a combustor according to the invention using hybrid calcinators without Nachkalzinatorbrenner;

8th a schematic diagram of a combustor according to the invention using hybrid calciners with Nachkalzinatorbrenner.

In 1 is a schematic diagram of a combustion plant 10 imaged according to the prior art. The raw meal is processed via a raw meal 12 the highest level 14A a 5-stage cyclone preheater 14 given up. In the cyclone preheater, the raw meal is heated to 850 to 880 ° C. The preheated raw meal of the second lowest cyclone stage 14D becomes a calciner 16 given up. In the calciner 16 The raw meal is removed by the exhaust gases from a rotary kiln 18 , as well as a calciner burner 20 further heated and calcined to hot flour. The required combustion air is called tertiary air via a tertiary air line 24 from the kiln outlet head 22 and thus from the clinker cooler into the calciner 16 guided. From the calciner 16 is used as hot meal in the lowest cyclone stage 14E where it is separated from the gas stream and then the rotary kiln inlet chamber 26 of the rotary kiln 18 is abandoned. In the rotary kiln 18 the hot meal is remuxed and fired to clinker. The required thermal energy is thereby from a rotary kiln burner 28 provided. The required combustion air is via the connection shaft 30 between radiator and oven outlet head 22 supplied to the rotary kiln. The clinker leaves the firing system 10 over the connection shaft 30 and is then cooled in a clinker cooler (not shown) to about 60-70 ° C above ambient temperature.

2 and 3 show the scheme of a combustor according to the invention 10 , The hot flour of the lowest cyclone stage 14E will not be the rotary kiln 18 abandoned, but is in a Nachkalzinator 34 mixed with the rotary kiln exhaust gases and there residual acidified. The residual deacidified hot meal is then placed in a cyclone separator 36 deposited from the gas phase and the rotary kiln inlet chamber 26 of the rotary kiln 18 given up. The exhaust air from the Nachkalzinator 34 and the downstream cyclone separator 36 gets into the precalciner 16 directed. Since the fully deacidified hot meal is prone to build up, the angle of the inflow spiral slope α and the cone angle β in the additional cyclone separator 36 larger than the cyclone separators 14A - 14E of the cyclone preheater 14 , Also the flour pipe 38 from the cyclone separator 36 to the inlet chamber 26 of the rotary kiln 18 For this reason, it has a larger diameter than the flour tubes of the cyclone preheater 14 , The thermal energy for the residual deacidification of hot meal in Nachkalzinator 34 is in this embodiment of the rotary kiln burner 28 provided.

The 3A and 3B make a view ( 3A ) and a plan view ( 3B ) of the additional cyclone separator 36 In order to prevent build-up of residual-acidified hot meal, the Einströmspriralenschräge has an angle α of 65 ° and the outlet cone of the cyclone an angle β of 75 ° relative to the horizontal.

It is possible, the Nachkalzinator 34 with its own burner 40 equip. 4 shows such a clinker burning plant 10 with an additional Nachkalzinatorbrenner 40 , The required combustion air (quartz air) is recuperation air from the clinker cooler and is via a pipeline 42 from the tertiary air line 24 the postcalzinator 34 fed.

The firing systems of 5 and 6 essentially correspond to the firing systems of the 2 and 4 , The difference between the respective firing systems is that pre- and Nachkalzinator 16 . 34 not as tube calcinators but as container calciners with a gas velocity of approx. 7 m / s. In 5 is the Nachkalzinator 34 designed without own Nachkalzinatorbrenner. The required heat energy is exclusively from the rotary kiln burner 28 provided. In 6 is the Nachkalzinator 34 By contrast, with its own Nachkalzinatorbrenner 40 equipped so that the additionally required for the residual deacidification thermal energy directly in Nachkalzinator 34 can be generated.

The firing systems of 7 and 8th essentially correspond to the firing systems of the 2 and 4 , or the 5 and 6 , The only difference between the respective firing systems is that pre-and Nachkalzinator 16 and 34 not designed as pure tube and Behälterkalzinatoren. In 7 is the Nachkalzinator 34 thereby formed without own Nachkalzinatorbrenner. In 8th is the Nachkalzinator 34 By contrast, with its own Nachkalzinatorbrenner 40 equipped, so that additionally required for the Restentsäuerung thermal energy in this embodiment, directly in Nachkalzinator 34 can be generated.

LIST OF REFERENCE NUMBERS

10

Cement clinker burning plant

12

raw meal

14

cyclone

14A

1st stage of the cyclone preheater

14B

2nd stage of the cyclone preheater

14C

3rd stage of the cyclone preheater

14D

4th stage of the cyclone preheater

14E

5th stage of the cyclone preheater

16

precalciner

18

Rotary kiln

20

Vorkalzinatorbrenner

22

Kiln outlet head

24

Tertiary air duct

26

Rotary kiln inlet chamber

28

Rotary kiln burner

30

Transition shaft

34

Nachkalzinator

36

cyclone

38

Flour pipeline

40

Nachkalzinatorbrenner

42

Quartiärluftleitung

Claims (11)

Burning plant ( 10 ) for the production of cement clinker from raw meal with a raw meal preheater ( 14 ) consisting of one or more cyclone stages ( 14A - 14E ) for heating the raw meal, a precalciner ( 16 ), in which the preheated raw meal is deacidified into hot meal and which is treated with a precalciner burner ( 20 ), a rotary kiln ( 18 ), in which the hot meal is burned to clinker and with a rotary kiln burner ( 28 ) and a clinker cooler for cooling the fired clinker, characterized by a Nachkalzinator ( 34 ) containing the hot meal of the lowest cyclone stage ( 14E ) and a Nachkalzinator ( 34 ) downstream cyclone separator ( 36 ), in which the hot flour from the Nachkalzinator ( 34 ) separated from the gas phase and then the rotary kiln ( 18 ), whereby the exhaust air from the Nachkalzinator ( 34 ) and the downstream cyclone separator ( 36 ) in the precalciner ( 16 ). Combustion plant according to claim 1, wherein the rotary kiln ( 18 ) has a length / diameter ratio of about 8: 1. Combustion plant according to claim 1, wherein the post-calcinator ( 34 ) with a Nachkalzinatorbrenner ( 40 ) is equipped. Combustion plant according to claim 3, wherein the rotary kiln ( 18 ) has a length / diameter ratio of about 7.5: 1. Combustion plant according to claim 3 or 4, wherein the required combustion air for the post-calciner burner ( 40 ) Recuperation air from the clinker cooler is, which via a quartiair ( 42 ) in the post-calcinator ( 34 ) to be led. Combustion plant according to one of the preceding claims, wherein precalciner ( 16 ) and post-calcinator ( 34 ) are designed as Rohrkalzinatoren. Combustion plant according to one of claims 1 to 5, wherein precalciner ( 16 ) and post-calcinator ( 34 ) are designed as Behälterkalzinatoren. Combustion plant according to one of claims 1 to 5, wherein precalciner ( 16 ) and post-calcinator ( 34 ) are each designed as a hybrid of tube and Behälterkalzinatoren. Firing installation according to one of the preceding claims, wherein the inlet spiral bevel of the Nachkalzinator ( 34 ) downstream cyclone separator ( 36 ) has an angle of more than 60 °, preferably of between 62 ° and 65 °, with respect to the horizontal. Firing plant according to one of the preceding claims, wherein the cone angle of the Nachkalzinator ( 34 ) downstream cyclone separator ( 36 ) is more than 70 °, preferably 72 ° to 75 °, relative to the horizontal. Combustion plant according to one of the preceding claims, wherein the diameter of the flour pipeline ( 38 ) between post-calcinator ( 34 ) and rotary kiln inlet chamber ( 26 ) is greater than the diameter of the flour pipes of the cyclone preheater ( 14 ).

Images