SU1081400A1 - Method of thermal treatment of loose material - Google Patents

Abstract

A METHOD FOR THERMOX1M1CHICAL TREATMENT OF A BULK MATERIAL in a furnace in a dense layer with a circulation zone in the lower part created by a jet of heat transfer medium, characterized in that, in order to improve the quality of material processing, they carry out multiple circulation of material through a pulsed heat transfer unit using a section of a section using a section of a section of a section using a pulsed heat transfer system. or block the outlet of the furnace with a frequency of 0.0008113 Hz.

Description

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Frequency jitter / tee hole j Hz

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0, & 5 The invention relates to the thermal and chemical treatment of bulk materials by a gas stream primarily for drying, calcining and metallization, and can be used in the metallurgical, chemical, food and other sectors of the national economy. The heating of a granular material in a shaft is known, connecting vertically located chambers connected by diaphragms. Flue gases pass from bottom to top sequentially through all vertical conical chambers. The velocity of the gases varies as it grows in the diaphragms and decreases in the chambers. The vertical gas pipe and connecting ducts ensure that the mixture is heated to a predetermined temperature by adjusting the residence time of the particles in each conical chamber. The disadvantages of this heating are the complexity of adjusting the velocity of the flue gases and the temperature of the material in the chambers, the construction of the device is complicated by installing exhaust gas pipelines of vapor, bypass and connecting ducts. The closest to the invention in technical terms is the method of thermochemical processing of this material beam in a dense layer with a circulation zone in the lower part of the furnace. The material is processed by chambers that are located one on another. Bulk material through the boot device enters the chamber. Gas is supplied through the nozzles, at certain flow rates of which circulation zones are formed in the chambers. Particles of the material (grain, coke, iron concentrate, etc.), treated with a gas stream, are transported with it through openings in the diaphragms installed in the lower part of each chamber. The finished product gets into the copying or onto the G2 1 conveyor. A disadvantage of the method is the difficulty of the operative control of the thermochemical treatment process itself in the cascade apparatus, since if there are several circulation zones, it is necessary to coordinate the material release rates from one chamber to another. all the chambers were constantly filled in (, especially when the physicomechanical properties of the material were changed: humidity, grain size, and others). In addition, the presence of vertically arranged chambers complicates the structural design of the device and as a result of the passage of particles of several chambers, the amount of destroyed material increases, which leads to a decrease in the quality of the finished product. The aim of the invention is to improve the quality of material processing. This goal is achieved by the fact that according to the method of thermochemical processing of bulk material in a furnace in a dense layer with SOHOPI circulation in the lower part of a heat carrier jet, the material is circulated multiple times by pulsating heat carrier supply with a frequency of 113 to 695 Hz, or shut off oven outlet with a frequency of 0.0008-113 Hz. The essence of the method is that the particles of the bulk material under the action of a gas jet (at a gas velocity above 40 m / s) circulate multiple times (more than twice) along the internal surface of the circulation zone, which allows an increase in the degree of material processing compared to its one-time processing in the circulation zone, excluding the creation of fairly complex cascade or the placement of several successively installed devices with single circulation zones. Thus, changing the number of passages of particles of the circulation zone, i.e. regulating ..- their residence time in it, and thus in the device itself, can be quickly controlled by the degree of material processing by gas, especially when the physicomechanical properties of the raw material loaded into the device (humidity, size, etc.) are unavoidable in practice. In turn, the multiple circulation of particles in the circulation zone is ensured by intermittent release of bulk material through an outlet in the bottom of the apparatus. Firstly, this can be achieved by pulsating gas supply (heat carrier, reducing agent) to the nozzle with a frequency of 3-695 Hz. The specified frequency range follows from the following. Since the flow rate of the discharge of bulk material during the formation of a circulation zone above the outlet opening is determined by the frequency of formation and destruction of dynamically unstable vaults above the circulation zone, the frequency of formation and destruction of vaults must correspond to the frequency of flow of the material. To determine the same frequency range of destruction and the formation of dynamically unstable arches, use the following relationship,. ,, l) - the frequency of destruction and formation of dynamically unstable arches, Hz g - acceleration of gravity 9.81 R - radius of the mounting hole, m; d — particle diameter, m; F (/ u | -) is the coefficient of the shape of the code; / U- is the coefficient of internal friction of bulk material. In the case of using fine granular material (c1,001 m) and an outlet orifice of a considerable size (F 0.3 m), a further increase in the diameter of the orifice is impractical, it causes a sharp increase in the velocity and gas flow rate to form a circulation zone of such large size, t . at a high flow rate of material V 1 17 9.81 .0.15 Gy..yL .1 / 0.001 Taking dx to 0.75 (. average value for most bulk materials), we get F (o) o, 49. . When the material being processed is through a small hole (Φ 0.01 m, a hole of a smaller diameter cannot be used, because particles of the material can circulate in the circulation zone and not enter the outlet), i.e. at low flow rate {p (.; |), У9.810.005 0.001 1 - °. “. v -...- In order to provide longer processing of the material in the circulation zone, it is necessary to shut off the outlet with a frequency of 0.0008-113 Hz. During the experiments it was found that when metallizing iron ore materials at a temperature of 1000 ° C and their residence time in a stationary state (if the hole is blocked) for 20 minutes, particles stick together and stable arches are formed that prevent the finished product from being ejected through the hole. Thus, the minimum frequency of blocking the outlet corresponds to the specified period of time, and hence 0.00083 Hz. The maximum frequency of the outlet overlap corresponds to the minimum flow rate of the bulk material, and consequently, the minimum frequency of destruction and the formation of dynamically unstable vaults, i.e. 113 Hz, and justified above. The drawing shows the dependence of the degree of drying of wet coke on the frequency of blocking the outlet. The experiments were carried out on coke with a moisture content of 12–13%, a fraction of 1.0–, mm on a flat model with dimensions of 400 mm fx 20 mm. The temperature of the heated air is 300 C. From the graph it can be seen that in the low-frequency region the overlapping of the outward opening, namely during repeated circulation of the coke particles, its degree of drying increases from 7 to 21%. Example. Metallization of the gravitational-magnetic concentrate takes place at 900 ° C in the apparatus under the conditions of the formation of a circulation zone in a dense layer of the outlet. Hydrogen is used as reducing gas. Experiments were carried out with a single, double, three, four and twelve compasses 510814006

particles in the circulation zone. According to the (by a known method) with the three variants of the second variant, the process is provided with metallization of circulation. The results of the experiment carried out in cascade instrumentation are given in Table. 1 and 2.

Table 1

Consumption .. gas-reducing agent

The degree of metallization concentrate,%

The frequency of blocking the outlet, Hz

Plant capacity, t / h

Gas consumption5, 3

5.3 73

59

0.0008

4.2

4.3

table 2

Claims (1)

METHOD OF THERMOCHEMICAL REV. WORKS OF BULK MATERIAL in the furnace in a dense layer with a circulation zone in the lower part created by the heat carrier jet, characterized in that, in order to improve the quality of the material processing, the material is repeatedly circulated by either pulsating heat carrier flow with a frequency of 113695 Hz, or by shutting down furnace outlet with a frequency of 0.0008113 Hz. SU. „, 1081400 The frequency of overlapping holes, Hz 1 1081400 2