RU2665669C1 - Line for the shs powder refractory products manufacturing - Google Patents

Abstract

FIELD: technological processes.SUBSTANCE: invention relates to the SHS powder refractory products manufacturing. Line contains the SHS charge preparation device by means of the reagents mixing, rolling mill for the shaped billet manufacturing in the form of the SHS batch strip, reactor for the SHS performance in the SHS charge strip with the igniting device and obtained in the reactor SHS refractory products strip grinding device. Reactor for the SHS performance in the SHS charge strip is made with possibility of the strip movement inside it and in the form of rectangular open from the two opposite ends two-walled container, which outer walls form the body and are provided with the nozzle for the flowing gaseous refrigerant supply to the reactor in front to the combustion front propagation, and the inner walls are made perforated and form the reaction cup. Igniting device is equipped with the flame sensor and is placed at the SHS conducting reactor entrance with provision of the SHS charge strip continuous burning. SHS refractory products strip grinding device is made in the form of roller grinding mill with at least two rollers.EFFECT: enabling reduction of the SHS performance duration.5 cl, 5 dwg, 2 tbl

Description

The invention relates to the field of powder metallurgy, namely, to the production of refractory powder compounds by the SHS method.

It can be most effectively used to create automated enterprises for the production of refractory powder products with a continuous production cycle.

A well-known traditional industrial complex for the manufacture of refractory powder products, including [1, 2]: a device for compacting (tabletting) blanks, a batch reactor, an ignition device (electric coil); ball mill for grinding synthesis products (PS).

The disadvantage is that, despite the short duration of the synthesis process, which lasts only a few seconds, the total production time of refractory products can be tens of hours. This is due to the duration of the preparatory, intermediate and terminal operations. In particular, the cooling rate of PS can be 10 ^-4 -10 ^-3 deg / s) [3]. As a result of this, the cooling time of even a small reactor during the synthesis of 2.5 kg of the product is 1.5-2 hours and it can be started only two times per shift (with a synthesis time of several seconds) [4].

As possible options for the intensification of individual operations were also known, in particular: a carousel-type installation consisting of ten reactors, roller and screw SHS reactors.

In the "carousel" type installation, the charge is loaded in the first reactor, and the synthesis products are unloaded in the last reactor. The disadvantage is that continuity is ensured in the first and tenth reactors (at the stages of loading and unloading products), and the remaining reactors (from the second to the ninth are idling, as they carry out intermediate operations, mainly PS cooling In addition, the carousel line may stop in case of failure of ignition of the charge in the next reactor, since it is necessary to disassemble and replace the igniter.

In a roll-type SHS reactor, the charge is ignited and burned in the area between the rolls and the bunker with the charge, and in the screw reactor, inside the conical nozzle sleeve. The disadvantage is the difficulty of stabilizing the combustion front, which can lead to the spread of combustion in the hopper. In addition, the plants cannot work for a long time due to the heating of the rolls and nozzle insert under constant contact with high-temperature substrates (in particular, the combustion temperature of a mixture of a mixture of titanium and boron is 3190K).

Also known are devices for intensively performing certain technological operations: a rolling mill for the continuous production of a workpiece in the form of a profiled ("corrugated") strip; a heat-generating reactor (TGR) with cooling of the PS with gaseous refrigerant; roller grinding mill for continuous grinding of PS in the process of passing them in rotating rolls; model flow reactor. A common disadvantage of the devices is that, despite the reduction in the time for individual technological operations, they are not integrated into the general technological and production process for producing powder refractory compounds in continuous burning mode.

The analysis showed that devices for the implementation of the manufacturing process of refractory powder products by the method of self-propagating high-temperature synthesis in the continuous combustion mode were not identified.

Therefore, the main problem in this direction is the lack of development of an industrial complex for the automated production of powder SHS products with a continuous production cycle, for decades and the solution of which the present invention is directed.

The technical result in solving the technical problem is to reduce the time of the technological process for the possibility of using it when creating automated production facilities for the production of refractory powder products by the SHS method.

To solve this problem, a set of equipment for the production of powder refractory SHS products in continuous combustion mode includes a device for mixing a mixture of reagents, a rolling mill for manufacturing a profile billet in the form of a strip from a SHS charge, a reactor for the synthesis of a profile strip from a SHS charge into profile strip of synthesis products, roll grinding mill. The reactor for the synthesis of refractory products is made in the form of a rectangular double-walled container open from two opposite ends. The outer walls of the container form a housing and comprise a fitting for supplying a flowing gaseous refrigerant to the reactor; the inner walls of the container are perforated and form a reaction beaker. The reactor contains from the front end side a flammable device and a flame sensor, while all devices are interconnected by introducing a flowing gaseous refrigerant (flow reactor) into the production line of the reactor.

In some cases, to align the peripheral speed of the rolls of the rolling mill with the burning speed of the strip PS, the rolls of the rolling mill are configured to control their rotation speed.

In those cases when it is necessary to regrind PS, the roll grinding mill contains four rolls arranged in pairs one after another.

In those cases when it is necessary to intensify the process of grinding PS, at least one of the rolls of the grinding mill is made with the possibility of changing the speed of its rotation.

In cases where it is necessary to place the PS (in the form of pieces) in the feed hopper before feeding the rolls of the grinding mill, intersecting grooves or protrusions are made on one of the rolls of the rolling mill;

If it is necessary to re-ignite the charge without disassembling the reactor, the igniting device contains a container with an igniting composition and a metering device connected to it using valves, moreover, an oxidizing fluoride (mainly chlorine trifluoride or bromine trifluoride) is used as an igniting composition in pulse mode.

The significance of the signs that provide a solution to the problem is due to the following reasons:

- the synthesis and cooling of substrates in a flow reactor ensures synchronization of all technological operations with each other, which is a prerequisite for the manufacture of powder refractory substrates in continuous burning mode and the development of automated production with a continuous technological cycle;

- the formation of a compacted shaped workpiece in the form of a strip from the SHS mixture and the safety of the profile during product synthesis during its movement inside the reactor cavity, as well as the presence of perforated holes on the inner walls of the reactor, make it possible to cool the synthesized strip from the side of its upper and lower surfaces;

- the placement of the flame sensor on the input side of the reactor and the presence of a device that controls the speed of rotation of the rolls provides a change in the feed rate of the rolled plate depending on the burning speed of the compacted charge strip in the reactor, which prevents the spread of the combustion process in the feed hopper by supplying a signal to the device for controlling the rotation speed rolls of a rolling mill;

- the implementation of the grinding mill four-roll ensures the intensification of the process of grinding PS due to re-rolling

- the use of a chemical method of ignition of the charge provides remote (without contacting with the charge) initiation of the SHS process.

The essence of the proposed solutions are illustrated by drawings, where:

in FIG. 1 shows a sequence diagram of technological operations of an intensive technological process and the use of a set of equipment with a continuous production cycle;

in FIG. 2 shows the caliber of rolls of a rolling mill for the continuous production of billets in the form of profiled ("corrugated") strips;

in FIG. 3 is a diagram of a model flow reactor for studying the completeness of combustion of profiled thin plates (billets) from a mixture of SHS components when they are cooled with refrigerant (nitrogen);

in FIG. 4 shows a view of blocks from a set of profiled (“corrugated”) plates with extinguished central plates;

in FIG. Figure 5 shows a block from a set of profiled ("corrugated") plates (without a central plate) before and after burning.

1 - charge SHS; 2 - a hopper for loading the SHS mixture from a mixture of titanium + boron components; 3 - rolls of a rolling mill; 4 - laminated strip of SHS charge; 5 - igniter; 6 - flame sensor (shown conditionally by an arrow); 7 - a reaction beaker; 8 - fitting; 9 - reactor vessel; 10 - rolled strip of the SHS charge in the process of combustion and cooling with nitrogen; 11 - rolls of the grinding mill; 12 - pieces of a strip of synthesized product; 13 - crushed powder strip PS; 14 - conveyor (shown conventionally in the form of a dashed arrow; 15 - the final powder product.

In FIG. 2 the following designations are accepted: 16 - roll gauge, 17 - protrusions; 18 - hollows; 19 - inclined faces; D is the diameter of the rolls along the protrusions; d is the diameter of the rolls along the troughs; h _g - horizontal clearance; hн - inclined clearance.

In FIG. 3 adopted the following notation:

5 - igniter; 7 - a reaction beaker; 8 - fitting for supplying refrigerant; 9 - reactor vessel; 20 - a block from a set of "corrugated" plates (blanks); 21 - the Central plate; 22 - output fitting.

In FIG. 4 the following notation is accepted:

4 ₁ - view of the central plate with the extinction of the combustion process at the point of contact with the stacking block of "corrugated" plates of the rolled SHS charge; 4 ₂ - view of the central plate with the extinction of the combustion process at a distance of 10-20 mm from the stacked block of "corrugated" plates.

In FIG. 5 adopted the following notation:

5 ₁ - view of a block from a set of "corrugated" plates before burning; 5 ₂ is a view of a block from a set of "corrugated" plates after burning.

Table 1 shows, for comparison, the time of PS grinding operations in the manufacture of refractory powders using discrete (standard) technology (in a ball mill) and technology with synchronized (by introducing a feed through reactor) intensive operations.

Work on the process of FIG. 1 with a continuous production cycle and the use of a set of equipment for its implementation are carried out as follows:

The mixed charge 1, placed in the hopper 2, is fed by gravity to the rolls 3 of the rolling mill, compressed into a shaped strip 4, which is initiated by the igniter 6 (shown conditionally) before entering the reactor. When the profiled strip 4 approaches the reactor, the flame sensor 5 is turned on and the ignited charge strip is fed into the through cavity of the reaction cup 7, where the charge components are synthesized. At the same time, refrigerant (nitrogen) is supplied through the nozzle 8 into the cavity between the walls of the reactor vessel 9 and the reaction vessel 7. Through the perforated walls of the reaction vessel 7, the refrigerant is supplied to the rolled ignited strip of synthesis products 10 moving inside the reactor and cools it. Then, the cooled strip of SHS products is fed into the rolls of the grinding mill 11 (in Fig. 1, the strip is previously destroyed into pieces 12). When passing through the rolls of the grinding mill 11, the cooled strip of synthesis products under the influence of sealing and shear loads is crushed into a powder product. If it is necessary to increase the degree of grinding, the peripheral speeds of the rolls of the grinding mill 11 and (or) are mismatched by re-passing the crushed products through the rolls of the rolling mill (for example, in a four-roll mill). The crushed powder SHS product 15 is supplied for further use (for example, for dispersion into fractions).

If the burning speed of strip 10 is exceeded relative to its rolling speed in rolls 3 (V _mountains > V _ol ), the burning of strip 10 propagates towards the hopper 2. In this case, the flame sensor 5 (shown in Fig. 1 by an arrow) detects a high-temperature combustion front and transmits a command to a device for controlling the speed of rotation of the rolls 3 of the rolling mill (not shown in Fig. 1), which equalizes the rolling speed to prevent the transition of combustion to the hopper 2.

To simplify the process of destruction of the strip 10, it contains intersecting protrusions of the undersized charge (formed by grooves on the roll 3 of the rolling mill) or thinned intersecting grooves (formed by the protrusions on the roll 3 of the rolling mill). In addition to this option, the broken strip can be fed to a conveyor located between the rollers 3 of the rolling mill and the rollers 11 of the grinding mill or in an intermediate tank.

The operation of the model reactor of FIG. 2 is carried out as follows:

Through the nozzle 8, refrigerant (nitrogen) is supplied and at the same time (or with some delay) the central plate 21 is ignited from the igniter 5. The refrigerant is blown between the walls of the reactor vessel 9 and the reaction cup 7, then enters the reaction cup 7 from the front end side, while the purge block 20 and the Central plate 21 is carried out towards the spread of the combustion front (combustion in the oncoming refrigerant stream). In the process of burning unit 20, the refrigerant also cools the reaction cup 7.

Test results.

To assess the effectiveness of the proposed device in table 1 shows the results of comparative tests to estimate the time for the implementation of the operations of cooling and grinding PS using discrete and intensive technologies.

According to the results of the analysis of the efficiency of technological operations, it follows that in the case of combining intensive technological operations with each other (synchronization among themselves), it can provide a reduction in the technological and production cycle by at least 10 times.

The test results are given in table. 2 show that with a reduction in cooling time and PS grinding time, the duration of the technological cycle can be reduced by at least 10 times, which makes it possible to create automated production with a continuous production cycle.

However, due to the fact that the combustion of the rolled strip 10 occurs with its simultaneous cooling with a purged refrigerant (nitrogen), that is, with a decrease in the combustion temperature, tests were carried out in the model reactor of FIG. 2 by assessing the completeness of combustion of the composition of TiB ₂ depending on the intensity of its cooling during the synthesis. The tests were carried out with varying the mass of the charge unit 20 and the flow rate of the refrigerant (nitrogen).

During the tests, the flow rate of the refrigerant was changed from 0.5 g / s (i.e., practically without blowing) to a value leading to the extinction of the central plate 21 (the extinction of the blocks 20 after their ignition from the central plate 21 did not occur). The view of the blocks from the set of "corrugated" plates (without a central plate) before and after burning is shown in FIG. four.

To assess the completeness of combustion, the products of synthesis in burned blocks 20 and in plates 21 (in the zone of extinction of the combustion process) were used as the analyzed samples. Assessment of the completeness of the process was carried out according to the results of chemical (average values from two definitions) analysis. The calculated values of titanium corresponding to the stoichiometric ratio of titanium diboride determined by chemical analysis of boron are also given there. The test results are shown in table 2.

Note. Dashes in the table indicate that this parameter was not determined

The test results showed that with an increase in the consumption of HA, the combustion process on the plate (experiment 8) may stop. In FIG. 4 ₁ , 4 ₂ shows the appearance of extinguished, central plates. The extinction of the plate 4 ₁ occurred at the point of contact with the block 20, and the plate 4 ₂ at a distance of 2 cm from the block 20.

As follows from FIG. 4, with intensive heat removal, the grain size is visible even visually. Nevertheless, the results of chemical analysis indicate that the final product is mainly titanium diboride, and the deviation in the PS content is comparable with the amount of impurities in the initial product and is within the measurement error. This may indicate that the completeness of combustion is ensured, practically, at any value of the flux XA, that is, at any burning rate of the rolled plate 10 (up to extinction). In addition, the extinction of the fuel cells indicates that the cooling conditions of the PS correspond to the conditions realized in the study of structural macrokinetics by "quenching" of the burning sample, where the extinction rate of the samples is 10 ³ -10 ⁴ cm / sec. Therefore, it can be considered that the model flow reactor of FIG. 3 can be used to study the process of structure formation of synthesis products.

The results of studies on the assessment of the combustion completeness confirmed the possibility of synthesizing refractory compounds not only in sequential mode, but also in parallel mode, including on individual thin plates, which expands the boundaries of research and the application of intensive SHS technologies.

Thus, the proposed solution under the conditions of the described examples confirms the possibility of manufacturing powder refractory SHS compounds with a continuous production cycle.

The use of a technical solution will make it possible to create an automated production facility for the production of powder refractory compounds in continuous burning mode and reduce the time of the technological process.

Bibliography

1. V.K. Prokudina, V.I. Ratnikov, V.M. Maslov, I.P. Borovinskaya, A.G. Merzhanov, F.I. Dubovitsky. Titanium carbide technology. In: Combustion processes in chemical technology and metallurgy. Ed. A.G. Merzhanova, Chernogolovka, 1975, p. 136-141.

2. Grinding titanium carbide in ball mills / V.M. Bunin, B.I. Torbov, V.M. Maslov, L.F. Mikulinskaya // Research of hard alloys: Thematic collection of scientific papers. - M., Metallurgy, 1991, - p. 92-97.

3. A.G. Merzhanov. Self-propagating high-temperature synthesis and powder metallurgy: unity of purpose and competition of principles. In the book. Combustion processes and synthesis of materials. Ed. V.T. Teleps, A.V. Khachoyan. Chernogolovka, publishing house ISMAN, 1998, p. 70-121.

4. A.G. Merzhanov. Problems of technological combustion. In Sat: Combustion processes in chemical technology and metallurgy. Ed. A.G. Merzhanova, Chernogolovka, 1975.

Claims (5)

1. A line for the manufacture of powder refractory products of SHS, containing a device for preparing a mixture for SHS by mixing reagents, a rolling mill for manufacturing a profile billet in the form of a strip from a charge for SHS, a reactor for conducting SHS in a strip of a charge for SHS with an igniting device and A device for grinding the SHS refractory product strip obtained in the reactor, characterized in that the reactor for conducting SHS in the SHS charge strip is configured to move the strip inside it and in the form of a double-walled container, open from two opposite ends, whose outer walls form a body and are equipped with a fitting for supplying a flowing gaseous refrigerant to the reactor towards the propagation of the combustion front, and the inner walls are perforated and form a reaction cup, while the ignition device is equipped with a flame sensor and placed at the inlet to the reactor for conducting SHS with ensuring continuous burning of the strip from the mixture for SHS, moreover, a device for grinding the refractory strip All SHS products are made in the form of a roll grinding mill with at least two rolls. 2. The line according to claim 1, characterized in that at least one of the rolls of the roll grinding mill is configured to change its rotation speed. 3. The line according to claim 1, characterized in that intersecting grooves or protrusions are made on one of the rolls of the roll mill. 4. The line according to claim 1, characterized in that at least one of the rolls of the roll mill is configured to change its rotation speed. 5. The line according to claim 1, characterized in that the ignition device comprises a container for the ignition composition and a metering device connected to it by means of valves.

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