DE1251688B - - Google Patents

Description

GERMAN WjJWKm PATENT OFFICE

EDITORIAL

German class: 80 b-24/09

Number: 1 251 688

File number: R 40229 VI b / 80 b

1251 688 filing date: March 26, 1965

Open date: October 5, 1967

The invention relates to a method for producing cement clinkers from limestone and clay components.

For cement burning are used in modern machines, in shaft furnaces, on sintering belts as well as rotary kilns, around 800 kcal / kg clinker heat energy is required. From this heat input the greater part, namely around 450 to 480 kcal / kg, is required for the deacidification of the calcium carbonate of the raw materials. This amount of heat is used in the modern combustion machines are covered exclusively by high-quality fuels. Inferior Fuels such as oil shale, washing mountains and lignite have not been used until now. In the well-known heat-saving rotary kilns, the Acidification of the raw meal is carried out essentially in the furnace itself, while the exhaust gases are used to heat the raw meal from ambient temperature to about 900 ° C. in preheaters of various types, in which preheaters the endothermic effect of clay drainage and partial deacidification of the raw meal is also achieved.

When trying to use inferior fuels such as oil shale for burning cement clinker in the To use shaft furnace or on the sintering belt, it has been shown that about two thirds of the calorific value of these fuels in the preheating zone are lost as gas or as condensable hydrocarbons and that explosion and fire there is a risk in the downstream flue gas pipes.

For example by the German patent specification 564 947 is a method for burning cement Od. Like. Known using cheap types of coal and coke grit, but the work is carried out in two stages. The first stage is used for deacidification of the calcium carbonate content and the second stage for sintering, with at least the second stage serving for sintering on a traveling grate to be led. This means that the material to be fired inevitably undergoes intermediate cooling between the two Must be subjected to firing stages. From this it follows that after the treatment in the first Stage an intermediate transport with intermediate cooling and intermediate treatment takes place, whereupon finally the heat treatment can be carried out in the second stage. A continuous flow of material is therefore impossible.

The invention has the task of producing cement clinkers with the greatest possible utilization of inferior fuels and

Process for the production of cement clinker

Applicant: Rudolf Rohrbach,

Dotternhausen (Kr.Balingen, Württ.), Schömberger Str. 218

Named as inventor: Rudolf Rohrbach, Dotternhausen; Helmuth Reckmeier, Balingen

while avoiding intermediate treatment.

To this end, the invention is based on a method for producing cement clinkers from limestone and clay components using Oil shale, bituminous limestone or silt mountains as fuel in a special burning process zuT deacidification of the calcium carbonate content.

In such a method, the invention proposes that the heat requirement for the deacidification too more than 30% is covered with full utilization of the fuel and sintering takes place immediately afterwards.

According to the method according to the invention, it is possible to determine the total content of combustible components in the low-quality fuels, namely in oil shale, in bituminous limestone or in wash mountains for the deacidification of calcium carbonate in cement raw meal through use an oven suitable for calcination, e.g. B. a whirling furnace to be fully used, with the addition that special resources and special time required for the intermediate treatment are omitted and that finally the length of the rotary kiln is significantly reduced due to the elimination of the deacidification zone can be.

The raw meal deacidified in the whirling oven according to the invention therefore requires one for cooking much shorter kiln than would normally have to be provided for the same clinker output. At a A 70 m long rotary kiln with a modern design preheater is heated to around 900 ° C more or less partially deacidified raw meal in the rotary kiln, which is made with about 8% fuel oil (// "= 9800 WE / kg), based on the weight of the finished clinker, must be heated.

According to the method according to the invention, the approximately 30 m long deacidification zone of the rotary

709 650 / 3C0

oven in discontinuation. With the same output, a rotary kiln shortened from 70 to 40 m is sufficient, and only about 3% fuel oil (H _u = 9800 WE / kg), based on the clinker weight, has to be fed to the rotary kiln as fuel.

With your method according to the invention an additional advantage is connected to the extent that that with the individual areas of application higher heat consumption, but this is in any case due to inferior Fuels, namely oil shale, bituminous limestone or wash mountains, is covered and in Form of sensible warmth of the clinker, the whirling furnace burnout, the hot exhaust air of the rotary kiln and of the vortex furnace, as a particularly economical heat transfer medium for grinding drying, for the Preheating of the raw meal, for preheating the primary and secondary air from the rotary kiln and Vortex furnace can be used. If it is present in excess, it can also be used to generate steam in a particularly economical manner and electricity, a process that is completely inefficient when using high quality fuels.

The basic idea of the present invention can differ from the previous one in many cases In the cement industry generally used working method can be realized in a particularly favorable manner that one is not from one as possible homogeneous raw meal from the oral components of the raw mixture, e.g. B. Limestone and clay, runs out, but according to the invention the method is carried out in the following way:

The floating gas preheater for the raw meal, which is upstream of the rotary kiln, does not work

■ homogeneous raw meal with a lime standard (KSt) of 95 ± 5 is supplied, but only a ground one

ι limestone.

According to H.Kühl, "Zement-Chemie", Vol. II, p. 280, the lime standard of a Portland cement is used (1951 edition), understood:

KSt = IOOCaO

2.8 SiO ₂ + 1.1 Ai ₂ O ₃ 4- 0.7 Fe ₂ O ₃ '

lets burn in order to realize the inventive idea in this way.

The invention also proposes that the fluidizing furnace essentially for deacidification of the Limestone required amount of heat if the fuel contained in the fuel-containing clay component is not sufficient for complete deacidification, from a solid, liquid or gaseous fuel supplied at the same time as this component is delivered.

After a further process step, sintering takes place in a rotary kiln.

The invention also proposes that only part of the limestone powder is common in the whirling furnace Burned with dusty oil shale, bituminous limestone or washed mountains and deacidified and then the whirling furnace burn-up together with that to achieve a KSt 95 ± 5 required additional limestone powder on a preheater of known design, the rotary kiln is upstream, or is abandoned on the rotary kiln itself.

Another suggestion is that part of the limestone powder in the whirling furnace together with dusty oil shale, bituminous limestone or washing mountains is burned and deacidified and that the vortex furnace burn-up is given up in one of the intermediate stages of the heat exchanger, However, the remaining limestone powder required to achieve a KSt 95 ± 5 is transferred to the entrance step the heat exchanger is abandoned.

It is therefore possible to use a raw meal made from limestone and a fuel-containing mineral component, e.g. B. oil shale, to be heated directly in a whirling furnace to about 900 ° C. The Limestone content can be limited to the amount that can be deacidified by the fuel-containing mineral component.

The remaining limestone content, which is necessary to achieve a KSt of 95 ± 5, can according to the whirling furnace can be added to the partially deacidified raw meal in a cyclone stage and the deacidification process in the rotary kiln can be completed. It however, it is also possible to use all of the limestone powder together with the fuel-supplying component to give up the vortex furnace, whereby additional fuel must be added to the vortex furnace, to complete the deacidification.

A particularly interesting variant is the addition of the required fuel requirement in the form of granular oil shale, for example in the grain size 4 to 7 mm. The granular component is discharged separately via the threshold usually present in the whirling furnace and, after cooling and grinding, can be used as a hydraulic additive or as a hydraulic binder use.

Between the process applications described in the two previous sections are various intermediate stages possible, in the form that, for. B. a partially deacidified raw meal in a vortex oven is abandoned together with the remaining limestone powder requirement in an intermediate stage of a heat exchanger or the partially deacidified raw meal is entered directly into the rotary kiln.

The invention also proposes that bituminous limestones deacidified in a burning process in the vortex furnace and the burnup together with the

where CaO, SiO ₂ , Al ₂ O ₃ and Fe ₂ O ₃ mean the percentages of these components with which they are contained in the material in question.

After passing through the preheater, the heated and optionally partially deacidified limestone powder is immediately known per se in a whirling furnace Design swirled at the same time as the fuel-containing, dust-milled component, thereby intimately mixed and fired further, with a KSt of the finished mixture of preferably 95 + 5 results. In this vortex furnace, the thermal energy of the fuel-containing component, namely oil shale, bituminous limestone or washing mountains, used to carry out the deacidification process initiated in the preheater. The burned-out mixture is sent directly to the rotary kiln (supplied. The dusty exhaust gases emerging from the vortex furnace get together with the Exhaust gases from the rotary kiln in the heat exchanger connected upstream of this rotary kiln. Of course you can a single cyclone or a similar combustion chamber can be used instead of the vortex furnace, in the flammable dust in suspension

Claims (3)

ground clay component to the preheater of the internal combustion engine, e.g. B. a rotary kiln, or the rotary kiln itself for the production of cement clinker is abandoned (Fig. 2). Three exemplary embodiments of the method according to the invention for producing cement clinkers are explained below with reference to the drawing. In the drawing, FIG. 1 shows a plant for the production of cement clinker in a schematic representation, and FIG. 2 shows an embodiment modified from FIG. 1. Embodiment 1 In the system according to FIG. 1, 10.2 t of 91% limestone powder 5 are fed to the first cyclone stage 4 of a 4-stage heat exchanger for the production of 10t cement clinker. When passing through the cyclone stages 3, 2 and 1, the limestone powder is heated further up to 900 ° C and reaches the whirling furnace 7 via the downpipe 6. The limestone is deacidified in the vortex furnace 7 and, together with the combustion residue of the oil shale, which acts as a clay component, passes through the cyclone 11, in which the hot exhaust gases from the vortex furnace 7 are separated from the raw meal, through the pipe 9 into the rotary furnace 10. The hot exhaust gases from the The vortex furnace goes through the pipeline 12, 13 into the cyclone stage 1. Embodiment 2 A rotary kiln that produces 10 t of clinker per hour is supposed to have a raw meal made of 10.2 t of 91% limestone and 6.21 of oil shale with a heating power of 1100WE / kg, which has previously been heated in a vortex furnace directly upstream of the rotary kiln to 950 ° C until complete deacidification. Since the heat of combustion of the 6.21 oil shale introduced as a clay component in the cement raw meal is not sufficient to cover the heat requirements of the process, a further 3.3 IOe WE per hour are added to the fluidized bed by adding 3 t of oil shale with a grain size of 3 to 6 mm per hour to the fluidized bed to be abandoned. This oil shale also has 1100 WE heating power. Heat receipts of (6.8 -I- 3.3) · IO «WE = 10.1 · 10» WE are then offset by heat expenditure of the same amount. These are made up of the following four heat quantities: 1. Heat losses in the vortex furnace 0.4 · IO ⁶ WE 2. Warming the raw materials of
Room temperature to about 920 ° C 4.0-10 «HS 3. Complete deacidification at about 900 ° C 3.7 · 10 <s WE 4. Heating of 10,000 m ^{3 of} exhaust air from the clinker cooler from 350 to 950 ° C 2.0 ■ 10 »WE The raw meal, ground to cement fineness, is continuously removed from the whirling furnace by means of the exhaust gas flow discharged upwards, separated by a cyclone and fed to the rotary kiln, while the oil shale serving as additional heating over the discharge threshold of the vortex furnace in the usual way Way is deducted. In the present example, you can use those used as additional heating t replace oil shale, for example, with 500 kg of fatty coal with a heating power of around 6600 to WE, in which case, of course, there is no discharge of small pieces of burnt oil shale. Embodiment 3 In the plant according to Fig. 2 of finely ground clay 5 the uppermost cyclone 4 of a 4-stage cyclone heat exchanger is supplied for the purpose of production of cement clinker 10 1 per hour 3.0 1 per hour. After preheating in cyclone 4, this clay is further heated in cyclones 3 and 2 and the constitutional water chemically bound in it is expelled. In the last cyclone stage 1 , this clay is intimately mixed in a whirling motion with the amount of deacidified limestone powder that is required for a good cement with KSt 95 ± 5. This component is formed from 12.8 1 of finely ground bituminous limestone 6, which was up to de-acidification thermally pretreated in the fluidized furnace 7 and 8 after deposition in the cyclone is fed via the downcomer 9 of the cyclone stage. 1 From the cyclone stage 1 , the ready-mixed raw meal, which has been preheated to approximately 950 ° C., passes directly into the rotary kiln 10 for the purpose of sintering into cement clinker. Patent claims: 1. Process for the production of cement clinkers from limestone and clay components using oil shale, bituminous limestone or silt mountains as fuel in a special burning process to deacidify the calcium carbonate portion, characterized in that, that the heat requirement for deacidification is more than 30% with full utilization of the fuel supplied is covered and the sintering takes place immediately afterwards. 2. The method according to claim 1, characterized in that the upstream of the rotary kiln Floating gas preheater of known design is abandoned exclusively limestone powder and that this heated and optionally partially deacidified limestone powder coming from the preheater immediately afterwards z. B. fed to a vortex furnace and dn this with the for the achievement of a KSt preferably of 95 + 5 minerals required mixed whirling where the added component consists of oil shale, bituminous limestone or wash mountains exists (Fig. 1). 3. The method according to claims 1 and 2, characterized in that in the vortex furnace essentially the amount of heat required to deacidify the limestone, as far as that in the fuel-containing one The fuel contained in the clay component is not sufficient for complete deacidification, from a solid, liquid or gaseous feed simultaneously with this component Fuel is delivered.