KR800001112B1 - Method of calcinating pulverized raw material - Google Patents

Abstract

At least partial calcining of a preheated powder contg. lime occurs before the powder travels through an inclined rotating furnace for further heat treatment, by mixing the hot, partly calcined powder with a liq. or solid fuel in the upper end of the furnace so that a combustible gas is liberated which travels to a calcining chamber together with the exhaust gas from the furnace, in the calcining chamber, the preheated, uncalcined power is suspended in the gas mixt. and an inlet for a gas contg. O2 is provided so the combustible gas is ignited and the required degree of calcining obtd., the powder then travels to the furnace.

Description

Roasting method of powdered raw materials

1 is a schematic of a complete cement combustion apparatus.

2 is a schematic view of a modification in which the adjustment ring at the hearth end is replaced with a bulge.

FIG. 3 shows a variant detail of the FIG. 2 apparatus, showing the means for supplying the oxygen containing gas supplied to the roaster from a source other than the clinker cooler.

4 is a schematic view showing a modification of the rotary furnace in addition to the function as an oxygen-containing gas supply source to the roasting furnace.

The present invention relates to a method of at least partially roasting a raw material prior to feeding it to a rotary furnace for final roasting of preheated powdery raw materials, powders, in particular cement raw powder, containing lime, the final heat treatment such as sintering. It relates to a conventional cooling method of the outside of the furnace by the method and the cooling air.

The roasting method in the present invention releases CO ₂ from CaCO _3, and the method of the present invention is an endothermic step requiring supply of sufficient heat.

In the case where the raw material is a cement raw material powder, the final heat treatment method performed after the roasting treatment is a sintering process which is an exothermic process for producing a finished product of cement clinker. Therefore, in the sintering process, it is necessary to supply the optimum amount of heat in order to raise the temperature of the raw material to the sintering temperature and compensate for the heat loss.

According to the present invention, at least partially roasting the raw material prior to passing the lime preheated raw material through the inclined rotary furnace for final heat treatment in the furnace, at least partially roasting the raw material The high temperature raw material is mixed well with the solid fuel or the liquid fuel at the top of the furnace, and the raw material emits a combustible gas upon contact with the hot fuel, and the combustible gas passes through the roasting chamber together with the exposure gas. In this roasting chamber, pre-heated raw material which is actually unbaked is suspended in the mixed gas, and oxygen-containing gas is supplied to burn the combustible gas, and each particle of the preheated raw material is roasted to a desired degree. do. As a result, the partially roasted raw material particles are separated from the mixed outlet gas stream from the roasting chamber and supplied to the upper end of the furnace.

The above example is for generating a high temperature soot gas stream by burning a fuel and passing the hot gas through a raw material to be roasted. Therefore, according to the novel method of the present invention, as far as the raw material particles are concerned, the raw material particles are in a combustion position. That is, heat is generated at a position suspended in the combustible gas burning. As a result, the preheated raw material, oxygen and combustible gas are mixed very well, and the desired roasting is achieved at a relatively low temperature at almost the same temperature.

As described above, according to the present invention, the fuel supplied to the upper end of the furnace can use either a solid fuel or a liquid fuel. In the case of solid fuel, finely divided solid fuel such as pulverized coal is preferably used, but coarse coal and spherical fuel may be used. All of these solid fuels have the same effect when they are in contact with the fuel of the roasted solid, and produce flammable gas, so the fuel oil evaporates in a similar manner.

The oxygen-containing gas contains the atmosphere, or waste cooling air, which is preheated by use to cool the finished product, in particular in a rotary furnace. This method improves the economics of the calories in the process. Of course, the oxygen containing gas may also be a mixture of atmospheric and waste cooling air.

Oxygen-containing gas may be supplied to the roasting chamber through the furnace. Therefore, in order to perform heat treatment in the furnace, oxygen can be introduced into the lower end of the inclined rotary furnace in an amount more than that of the secondary combustion air necessary to assist combustion in the furnace, so that excess oxygen-containing gas is part of the exposure gas. As a result, it forms all or part of the oxygen-containing gas supplied to the roasting chamber through the hearth end.

The invention also includes an apparatus for heat treatment of powdered raw material containing lime by a novel method. The apparatus of the present invention has an upper end connected to a raw material preheater and a roaster, and a lower end composed of an inclined rotary furnace connected to a heat treatment finished product cooler, so that the apparatus can be mixed with at least partially roasted freshly input raw material. Means for supplying the solid or liquid fuel to the upper end of the furnace, and means for supplying the oxygen-containing gas to the roaster. The device is particularly useful for converting cement raw powder into cement clinker.

At the upper end of the light rotary furnace there may be provided a means for forming at least a partially coagulated mass of raw material at the inlet, wherein the fuel supply means is open inside the furnace. The agglomeration forming means serves to agglomerate the material for effectively mixing the fuel and the roasted hot raw material and thereby the release of the gaseous fuel.

One example of the means for forming agglomerates in the furnace inlet consists of an adjustment ring which protrudes from the furnace inner wall and regulates the furnace diameter downflow, in which the fuel supply means is opened inside the furnace. Another example is composed of outwardly expanding portions provided in the furnace wall at a position where the fuel supply means is opened inside the furnace.

An example of an apparatus for carrying out the method of the present invention will be described with reference to the accompanying drawings.

FIG. 1 illustrates a rotary furnace 1 with a rotary ring 2 supported by a roller capable of rotating idler (not shown) on the base three. In addition, the rotary furnace is equipped with a combustion engine 4, an adjustment ring 5, a backflow preventing capacity 5 of the roasted raw material powder, a fuel supply means 6 and a roasted raw material powder supply pipe 7.

The rotary furnace 1 has its lower end connected to the axial clinker dropping chute 8 through which the clinker passes through the known base grate clinker cooler 9. In addition, the activator 8 serves to convey cooling air from the clinker cooler 9 back into the furnace with the falling clinker to act as secondary combustion air in the furnace.

The inclined rotary furnace 1 has an upper end thereof connected to the ascending tube 10, and at the same time, the lower end of the elevating tube is provided with a tube 12-gap apparatus for supplying oxygen-containing gas in a waste cooling air state from the clinker cooler 9 via the dropping chute 8. Is designed to configure the axial roaster 11. The associated riser 10 and roaster 11 open upward into a cyclone 13 of variation, which includes the cyclones 13, 14, 15 and 16 of the four worlds, and the associated riser 10, 17, 18 and 19 and the raw material. Along with the feed pipes 7, 20, 21, 22 and 23 forms a part of the raw material powder preheater in a cycle form, the feed pipe 23 serves to feed the raw material powder to the preheater. The gas is exhausted through the whole apparatus by means of an exhaust blower 24 whose pressurized part is connected to the dust settler 25 and whose lower part is connected to the year indicated by 26.

2 illustrates the same apparatus as the description of FIG. In this case, however, the rotary furnace 1 is provided with a bulge 5 'instead of 5 adjusting rings for braking the material in the furnace, and the tube 12' is connected to the other end of the cooler cooler as opposed to the tube 12 according to FIG. . It is a base rotating type with a central drum 27, equipped with a planetary cooling tube 28, and is provided with a rotating ring 29 supported by a roller (not shown) which can be rotated and rested on the base 30. have.

3 is a variant detail of the device of FIG. 2. The bamboo roaster 11 is equipped with an oxygen-containing gas supply pipe 12 ″ from a source other than the clinker cooler on one side thereof. This tube has a regulator 31 which controls the supply of a mixture of fresh air or an oxygen containing gas from various sources, preferably a preheated gas mixture.

During operation of the apparatus according to FIG. 1, fuel is supplied by the supply means 6 to the aggregate of the raw material powder at the roasted high temperature between the backflow prevention ring 5a and the adjustment ring 5. The heat contained in this agglomerate causes the fuel to evaporate or be released as a gas, which is passed through the roaster 11 without being entrained and burned in the hot outlet gas. This is because the exposure gas does not contain oxygen. In the roaster 11 the hot gas is mixed with the raw powder via the passages identified by reference symbols 23, 19, 16, 22, 18, 15, 21, 17, 14, 20, and the temperature gradually rises. Only when the gas mixture comes into contact with the oxygen-containing gas introduced into the tube 12 is the combustible gas combusted and the roasting takes place, after which the roasted raw powder is introduced into the furnace 13 for final introduction into the furnace 1 through the tube 7. It is separated from the gas flame.

In the furnace 1 this material particle which has not already been completely roasted is subjected to final roasting, and in some cases the completely roasted material is continuously sintered to form the finished clinker product. The clinker is exemplified by one grate cooler via the axial clinker drop chute 8 but is passed through another form of clinker cooler 9. The rotary cooler type as shown in FIG. 2 shows that a planetary cooling tube is installed.

As shown in FIG. 1, the oxygen-containing gas is generated in the cooler 9 and passed to the roaster 11 via the chute 8 and the tube 12. When roasting the raw material powder, the amount of combustion air required is about twice as large as that required for the sintering of the roasted raw material in the next step, so that the amount of gas flowing upward through the chute 8 is precisely equal to 1/3. Silver passes through furnace 1 and two-thirds should be carefully measured and carefully sized so that gas passages pass through pipe 12 to roaster 11.

To minimize the tube 12 of FIG. 1 extremely, the apparatus shown in FIG. 2 is preferred. Oxygen-containing gas, which makes up about two-thirds of the waste cooling air, is taken at the end of the clinker cooler remote from the junction with the furnace, and the clinker cooler is rotatable, with the air displaced via a relatively short pipe 12 '. It is passed through the desired 11th. The other third of the waste cooling air is passed to rotary furnace 1 via chute 8.

As shown in FIG. 3, the regulator 31 installed in the tube 12 ″ may be used to control the amount of oxygen-containing gas sent to the roaster 11. Although the gas is assumed to be fresh air, it is possible to reduce the heat losses of the stationary phase by using gas mixtures from various sources, preferably gas mixtures in a preheated state.

The drawback of the FIG. 1 apparatus is that it has to be equipped with a wide and long tube 12 carrying waste cooling air at a distance longer than the length of furnace 1.

FIG. 2 is an improved apparatus in this respect because it shortens the length of this tube (12 'in FIG. 2) by a length substantially corresponding to the horizontal length of the clinker cooler.

The device according to FIG. 4 is a further refinement, at least in view of the above problems. This is because all the tubes 12 (or 12 ') are removed. However, other means must be taken to ensure the oxygen-containing gas is delivered to the roasting. In the apparatus of FIG. 4, the secondary combustion air of the amount more than required to assist the combustion maintained at the end of the combustion engine 4 with oxygen is introduced from the clinker cooler 9 to the lower end of the inclined rotary furnace 1 via the drop chute 8. The roasted raw powder conveyed through 1 is sintered to a cement clinker.

As described above, in the operation of the rotary furnace 1, in contrast to the operating example of the rotary furnace, the gas passing through the adjusting ring 5 helps to burn fuel added to the inlet end from the feeder 6 in the roaster 11. It will contain a sufficient amount of oxygen.

However, in the example of FIG. 4, oxygen is present in agglomerates of the roasted raw powder at the point where combustible gas occurs, i.e., the rotary furnace 1 between rings 5 and 5a, so that a part of the gas is discharged from the bend of the tube 20. It is dangerous because it burns in advance before reaching the roaster 11 in contact with the preheated raw powder.

In any case, this early combustion of the gas is not good, because in such a case the furnace bends too hot and the structure and the surrounding materials cannot be produced normally. For this reason, it is considered that the apparatus of FIG. 1 or the apparatus of FIG. 2 is more preferable.

Claims (1)

At least partially roasting the raw material containing lime prior to passing it through the inclined rotary furnace for final heat treatment in the furnace, the at least partially roasted hot material supplied to the furnace at the top of the furnace. A mixed contact with a solid or liquid fuel which releases combustible gas upon contact with the raw material, the combustible gas passing through a roasting chamber together with an exposure gas, the mixed preheated raw material in the unbaked state in the roasting chamber. Suspended in gas and then supplied with an oxygen-containing gas to combust the combustible gas, roast each of the preheated raw material particles to a desired degree, and then partially discharge the raw material particles that are partially roasted from the roasting chamber. A method of roasting powdery raw materials, characterized in that the separation is carried out in a feed to the upper end of the furnace.

Images