DE2533142A1 - PLANT FOR THE PRODUCTION OF CEMENT IN THE DRY PROCESS WITH A PRE-CALCINATION CHAMBER - Google Patents

Description

PATENTANWÄLTE DIPL.-INQ. A. WEDDE DIPU-INQ. K. EMPL

Banks: Deutsche Bank No. 85/22 6O1 Bayer. Mortgage bank number 172/2OO2 Poetscheck Munich No. 47 392-S03

8 MUNICH 8O Schumannstr. 2 - Tel. (08O) 4710 * 7 Telearammei Patentwedde-Munich

July 24, 1975

File: P 7864

FIVES-GAIL BABOOGK

Paris / France

Plant for the production of cement using the dry process with a pre-calcining chamber

The invention "relates to plants for the production of cement in the! is heated, a between the preheater and the furnace "arranged precalcination chamber and a cooler for the Clinker.

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In the known systems of this type, the one originates in the precalcination chamber used secondary air generally from the cooler, thereby recovering some of the calories of the clinker is possible.

This air can be fed to the pre-calcining chamber through the furnace ”. This solution leads to the fact that in the furnace is introduced a very large excess of air in relation to the stoichiometric requirement of the furnace, which is expressed in a significant decrease in its performance, since the difference in the temperatures of the gases and of the material, which is the decisive parameter of the heat exchange, is greatly reduced.

Another solution is that the Vorkalzinierungskammer is supplied to the secondary air with the temperature of the outlet of the radiator, usually between 65O ⁰ and 800 G in a direction extending along the kiln line. Even if this solution is more satisfactory from a thermal point of view, it has the following disadvantages:

- For the equalization of the quantities and thus the distribution of the secondary air between the furnace and the feed line for the precalcination chamber it is essential to have one in the furnace circuit between it and the chamber To create additional flow loss through a throttle point, this can be achieved through a flap which has a variable Loss of flow in the secondary air causes the

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Quantities can be adjusted. This additional loss of flow in the exhaust gas circuit increases the performance for ventilation and the risk of silting up.

- Despite the presence of these additional flow losses in the circuit of the exhaust gases, and taking into account the need to limit their amount, there is little flow loss in the secondary air line permissible. The line must therefore have a large cross-section, approximately in the order of magnitude of the cross-section of the Furnace; this results in high costs, considerable heat losses through the walls and a limited speed of the air flowing through there, hence the risk of the dust carried along by the air being deposited. Because the gradient this line is very small, there is a risk that these deposits increase the flow loss and, over time, a change in the distribution of the amounts of air between the furnace and the precalcination chamber cause.

To avoid these difficulties, a third solution has been implemented; it consists in the fact that the cooler Air is taken at a much lower temperature in order to be able to convey it with the help of a fan. It is then no longer necessary to create an additional flow loss in the exhaust gas circuit, the air can with the desired Speed, so that dust

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Deposits are avoided and the amount of air between the furnace and the pre-calcining chamber is distributed through. Regulation of the blower or a slide in the line of the supplied air. However, these advantages are achieved at the expense of heat consumption, because when conveyed by a fan, the air taken from the cooler must not exceed ^{a temperature of 400 to 450 ° C.}

The solution according to the invention combines the advantages of the last two solutions: it allows a maximum Recovery of the calories of the clinker and a simple regulation of the supply of the furnace and the precalcination chamber Secondary air volumes.

According to the invention, air at high temperature extracted from the cooler is in the circuit to which this air is conveyed Fan arranged upstream heat exchanger, in which the air through indirect heat exchange is cooled by the secondary air that supplies the precalcination chamber, causing it to approximate the Temperature of the air leaving the cooler is brought.

The air supplying the precalcination chamber may be fresh air, in which case it will be in the heat exchanger cooled air is advantageously fed back into the cooler for the clinker.

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The air taken from the cooler for the clinker is preferably used as the secondary air, and in this case this Air at the outlet of the warm circuit of the heat exchanger subjected to additional cooling and in the cold The circuit of the same heat exchanger is carried out, where it is heated again before being introduced into the precalcination chamber will; The fan that ensures the flow of air is beneficial to the warm circuit of the heat exchanger downstream of the device for additional cooling.

The device for performing this additional cooling can consist of a steam boiler in which the Calories given off by the air are used to generate steam.

This additional cooling can also be achieved by injecting water into the air flow, by adding fresh air, by indirect heat exchange with a fresh air flow, which is then advantageously used in the cooler for the clinker or by direct heat exchange with the unfired and cold material.

In the circuit of the air taken from the cooler is the heat exchanger a dedusting device is connected upstream.

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Three non-limiting exemplary embodiments are shown in the drawing and are described in more detail below.

Show it:

1, 2 and 3 are diagrams of systems according to the invention.

The plant according to lig. 1 consists essentially of one Rotary kiln 10, a precalcination chamber 12, a partially shown cyclone preheater 14 and a cooler for the clinker 16.

The raw material is first heated in the preheater 14 with the help of exhaust gases from the furnace and the precalcination chamber, then at least partially calcined in chamber 12, before it is introduced into the kiln, where, if necessary, the calcination is completed and the clinker manufacture he follows. The clinker leaving the rotary kiln is cooled by fresh air in the cooler 16.

A burner 18 supplies the necessary for the furnace 10 Calories; as secondary air, it uses part of the warm air leaving the cooler. The other part is used as Secondary air used in the precalcination chamber.

A fan 20 conveys the warm air from the cooler to the precalcination chamber ο This high temperature air extracted from the heater cap of the stove is blown through before it passes through

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the fan cooled. Two heat exchangers 22 and 24 connected in series are used for this purpose.

The heat exchanger 22 enables an indirect heat exchange between two fluids and has two independent circuits, one of which (the warm circuit) is flowed through by warm air emerging from the cooler. The heat exchanger is a dedusting cyclone 26 upstream to avoid the risk of wear and tear on the heat exchange surfaces and clogging of the circuit of the heat exchanger. The other circuit (the cold circuit) of the heat exchanger 22 is of air supplied by the blower 20 flows through it, which in this way before its entry into the precalcination chamber is heated.

The heat exchanger 24 can be designed for indirect heat exchange, with the cold circuit of this heat exchanger that is, cold air, taken from the atmosphere, flows through it and then, as shown, in the cooler is used.

Thanks to this arrangement, the air flowing through the fan has a sufficiently low temperature that the Fan is not damaged and the temperature of the air supplied to the precalcination chamber remains relative high.

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Apart from the thermal losses, this is the temperature of the secondary air fed into the precalcination chamber equal to the temperature of the air exiting the cooler 16, reduced by the temperature drop T in the heat exchanger 24.

If, for example, T is assumed to be 100 ° C., the temperature of the air at the outlet of the cooler being 77O ⁰ C, and if a temperature of 4-0O ⁰ C is prescribed in the area of the fan, the following temperatures result at the characteristic points of the Cycle:

- Inlet of the warm circuit of the heat exchanger 22

... 77O ⁰ C.

The outlet of the warm circuit of the heat exchanger 22

... 50O ⁰ C.

- Outlet of the heat exchanger 24 ... 400 ⁰ C.

- The cold circuit outlet of the heat exchanger 22

... 67O ⁰ C.

By means of a slide 28, the amount of secondary air feeding the precalcination chamber and therefore the distribution of the Air from the cooler 16 'can be regulated between this chamber and the furnace.

The temperature drop T can be regulated to adjust the temperature To keep air in the area of the fan at a target value, for example by regulating the amount of Cooling fluids.

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The heat exchanger 24 can be replaced by a steam boiler which generates water vapor at low pressure, around from the decisive large temperature difference with the good heat exchange coefficient of the water Use. To draw.

In the case of a modification, the heat exchanger can be omitted, with additional cooling by diluting the air flow is carried out with the aid of a cold fluid. This cold fluid can be air or atomized water; in the latter case the heat of evaporation cannot be recovered, but in operation the amounts of water are much smaller than when a steam boiler is used, and thus the investment costs are lower.

This additional cooling can also be achieved in that the air is brought into contact with the unfired and cold material, as is illustrated in FIG. In this variant, the outlet of the warm circuit of the heat exchanger 22 is connected to the lower end of a vertical duct 34, the upper end of which is connected to the inlet of a cyclone 36; the outlet of this cyclone is connected to the suction side of the blower 20. Part of the unfired material to be processed is introduced into line 34 at A and the other part into preheater 14 ^{at A 1.} The line 34 and the cyclone 36 represent a heat exchanger in which the air is cooled by the material suspended in the air stream. in the

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Cyclone 36 separates the heated material from the air stream and then introduces it into the preheater. That way Cooled air flows through the fan 20, is then reheated in the heat exchanger 22 before it reaches the precaizing chamber 12 is supplied.

In the modification according to FIG. 3, the flows out of the cooler 16 for the clinker exiting air through a heat exchanger 30, where it takes some of its calories through indirect Gives heat exchange to the fresh air, which is used as secondary air in the Yorkalzinierungskammer 12 will. At the outlet of the heat exchanger 30, the cooled air is returned to the cooler 16. The one in the chamber 12 The secondary air used is conveyed to the chamber 12 by a fan 32 connected upstream of the heat exchanger.

For example, the secondary air with the aid of the radiator of removed air can be heated to 67o C ⁰ having a temperature of 77O ⁰ O of 20 °, which air leaves the heat exchanger 30 at about 120 ⁰ O.

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Claims (1)

-, 2533U2 Dipl.-iüo. K. i £ I /. i ^J L
Munich Schumannstrasse 2 July 24, 1975 File: P 7864 Claims ο) Plant for the production of cement in the dry process with a furnace, a preheater, in which the unfired material is heated by the exhaust gases from the furnace, with a pre-calcining chamber arranged between the preheater and the furnace and with a cooler for the clinker, those used in the combustion chamber and the furnace Secondary air is heated by the calories of the clinker, characterized in that it has a heat exchanger with indirect heat exchange with two independent circuits, which of one warm fluid or «, a cold fluid is flowed through, and in which the used in the precalcination chamber Secondary air is heated with the help of air of high temperature, which the cooler for the clinker with the help of a fan downstream of the heat exchanger has been removed ο - 12 509887/0785 2.) Attachment after. Claim 1, characterized that the secondary air feeding the precalcination chamber is fresh air, which with the help of a Fan is removed from the atmosphere and fed into the cold circuit of the heat exchanger, and that the out The air exiting the warm circuit of the heat exchanger is fed back into the cooler for the clinker. 3.) Plant according to claim 1, characterized in that the feeding the precalcination chamber Secondary air is the air extracted from the cooler for the clinker, which after passing through the warm circuit of the Heat exchanger flows through a device in which it is subjected to additional cooling, and then is fed into the cold circuit of the same heat exchanger, which ensures the flow of air Fan connected upstream of the cold circuit of the heat exchanger and preferably the additional cooling device is downstream. 4.) Plant according to claim 3, characterized in that the additional cooling device for the air consists of a steam boiler in which the calories given off by the air are used to carry water vapor to generate low pressure. ο) system according to claim 3 »characterized that the additional cooling of the air - 13 5 09887/0785 2533U2 takes place through indirect heat exchange with fresh air, which is then fed into the cooler for the clinker., 60) System according to claim 3, characterized in that the additional cooling of the air is provided done by injecting water into the air stream. 7.) Plant according to claim 3, characterized in that that the additional cooling by mixing fresh air with the ^ m cooler for the clinker extracted air takes place. 8.) Plant according to claim 3 »characterized that the additional cooling of the air by direct heat exchange with at least one part of the unfired material takes place » 9.) Plant according to claim 8, characterized in that it has a vertical line, the lower end of which is connected to the outlet of the warm circuit of the heat exchanger and the upper end End connected to the inlet of a cyclone, the outlet of the cyclone being connected to the suction side of the öebläses is, and that part of the unfired material is introduced into this conduit so that it is in suspension is held in this air flow and is carried along by this to the cyclone, where it is separated from the air flow and then fed to the preheater. - U. -509887/0785 10.) Plant according to claim 1, characterized that a dedusting device in the circuit of the air extracted from the cooler for the clinker is connected upstream of the heat exchanger. 509887/0785