RU2004492C1 - Method for production of calcium carbide - Google Patents

Description

action with coke, forming at temperatures of 2200-2300 ° С a melt of calcium carbide.

Calcium carbide is accumulated in the lower zone of the furnace and periodically drained through the discharge channel 7 with the shutter 8 pushed back to the finished product receiver (not shown in the diagram).

Example 1. The choice of the frequency of the heating current was justified by a series of experiments in which power sources with a frequency range of both industrial frequency and including a set of machine and lamp generators manufactured by the industry operating at allowed frequencies of 0.008 were used; 0.066; 0.44; 5.28 and 13.56 MHz.

In the table. Figure 1 shows the results of processing coke mash with a grain size of 10-25 mm in a cylindrical chamber with a diameter of 100 mm placed in the inductors of high-frequency power sources operating at the indicated frequencies. Under equal experimental conditions (in particular, the supplied power and heating time), as follows from the table. 1, the maximum temperatures of 2200-2300 ° C required for the process were obtained at frequencies of 440 kHz - 5.28 MHz.

Frequencies below this range are not sufficient for heating coke having weak ferromagnetic properties, and frequencies above this limit are not known to be very effective for induction heating. Therefore, the frequency range of the supply current of 0.44-5.28 MHz is recommended for the implementation of the method.

EXAMPLE 2 To determine the effect of fineness of limestone calcined under the conditions of induction heating treatment, a mixture of limestone and coke was prepared in a weight ratio of 1: 0.75, respectively. Tests were carried out on a plant with a capacity of 0.5 kg / h.

Under constant coarseness of pieces of coke (10-25 mm) and other other equal conditions, different fractions of limestone 0-5 were used; 0-10; 0-15; 0-20; 0-25; 0-30 mm.

As a response parameter characterizing the quality of the obtained calcium carbide, the displacement (volume of dry acetylene, secreted by 1 kg of calcium carbide) was determined.

The results of the performed determinations are given in table. 2.

It can be seen that expanding the range of fineness of the pieces of limestone leads to a gradual deterioration in the quality of calcium carbide. When the size of the pieces of limestone lying in the range of 0-20 mm. calcium carbide obtained corresponding to the standards (calcium carbide, GOST 1460-81) of the highest, first and second grades. For larger classes of lime, the quality 5 of the resulting product does not fit the requirements of the standard.

Based on the studies performed, a limestone size limit of 0–20 mm is recommended.

PRI me R 3. Limit values

Coke sizes were determined on the basis of research results, in which a peculiar mechanism of induction heating of coke of various sizes was established.

The essence of this mechanism is that in the magnetic field of the inductor arise as closed currents flowing along a circuit formed by adjacent

0 to each other by coke particles, as well as local currents with a zone of action bounded by coke grains taken separately. The role of each of the induced types of currents in the overall level of heat generation depends on the size

5 particles and bulk resistance of the coke charge.

With an increase in particle size, the resistivity of coke mounds increases (due to the increase in porosity) and prevails in generation

0 heat becomes the effect of local currents.

On the contrary, the high packing density of the mound of small classes of coke provides it with maximum conductivity and increases the intensity of closed currents. However, taking into account that the absolute value of the resistivity of such a coke charge is relatively high, the efficiency of its heating is much lower in comparison with the larger coke. The foregoing is confirmed by the data in Table. 3, which shows the dependence of the final heating temperature of coke of various sizes at the same power supplied from a high-frequency generator5 with a frequency of 5.28 MHz.

The described mechanism of induction heating of the coke charge explains the results of induction heating of a mixture of coke of various sizes with a known

0 given example.

The mixture of limestone and coke was heated on a bench unit under conditions similar to the description given in Example 2. The mixture was heated, containing in all experiments known to the same size 0-20 mm and coke of different sizes. The mass ratio of lime to coke in the mixture was 1: 0.75.

The results of heating the received mixtures are given in table. 4

From the above table. It can be seen that when using coke with a particle size of 0-5 and 5-10 mm, the level of heating of the mixture to a total of 420 and 1040 ° C was achieved, which is not enough to implement the method.

Coke, lying within the size range of 10-25 mm, provides heating of the mixture to predetermined temperatures of 2000 ° C or more.

It is also seen that a further increase in the size of coke reduces the heating efficiency due to an increase in the porosity of the mixture.

Thus, the boundaries of the optimal size of coke mixed with lime are 10–25 mm.

The following is an assessment of comparable methods for producing calcium carbide.

The preparation of calcium carbide by the proposed method was performed on a bench installation under the conditions described in experiment 2. Comparison of the obtained calcium carbide was carried out for pieces with a particle size of 25-50 mm. Comparative data are given in table. 5.

The data in Table 5 indicate higher values of all indicators characterizing the proposed process for producing calcium carbide.

(56) Kuznetsov A.A. Calcium carbide production. M .: Goskhimizdat, 1950, p. nineteen.

Heating current frequency

MHz

0.00005

0.008

0,066

0.44

5.28

13.56

Table 1

Final heating temperature, ° С

50.0 320.0

800.0 2300.0 2200.0 1350.0

table 2

Table 3

Table 4

Table 5

Continuation of the table. 5

Claims (1)

SUMMARY OF THE INVENTION METHOD FOR PRODUCING CALCIUM CARBIDE, comprising mixing lime with coke and heat treatment of the resulting mixture, characterized in that Zuaa before & ZAAA Zone-o® - GaizV & m ffCt t 3®as & & Tii P & About Skoksom It is known that coke is taken with a particle size of O - 20 and 10 - 25 mm, respectively, and the thermo-oo-waste of the mixture is carried out in the induction furnace at a frequency of the electromagnetic field of the inductor of 0.44 - 5.28 MHz.