RU2126713C1 - Apparatus for synthesis of organochlorine silanes in fluidized bed - Google Patents

Abstract

FIELD: heat-mass transfer apparatuses for conduction of processes in fluidized bed; may be used in organosilicon industry for production of organochlorine silanes by direct synthesis from silicon-containing contact mass under the influence of alkyl chlorine in fluidized bed, and in other industries for conduction of processes with use of fluidized bed. SUBSTANCE: apparatus includes vertical body having sections in the form of cylinders and truncated right and reversed cones; gas distributor and heat exchanger installed inside body; means for supply of raw materials and discharge of synthesis products. Body consists of successively installed three sections, and lower one is in the form of truncated reversed cone with an angle of inclination of generator to vertical axis of 5-7.5 dwg; the middle section is in the form of cylinder whose height-inner diameter ratio is 0.8-1.3; the upper section is in the form of truncated right cone whose height-total height of lower and middle sections is 2-4; ratio of inner diameters of lower and upper end faces of cone equals 0.8-1.2, inner diameter of cylinder section-inner diameter of body lower end faces equals 1.2-2. EFFECT: higher productivity of apparatus and selectivity of synthesis process. 1 dwg, 1 tbl

Description

 The present invention relates to heat and mass transfer apparatus for carrying out processes in a fluidized bed and can be used in the organosilicon industry for the production of organochlorosilanes by direct synthesis from a silicon-containing contact mass under the influence of alkyl chloride in a fluidized bed, as well as in other industries for carrying out processes using a fluidized bed.

 The direct synthesis of alkylchlorosilanes is carried out by reacting a finely dispersed contact mass, consisting of silicon, copper and other catalysts and promoters, with chloralkyl in a fluidized bed when heated.

 Developments in the hardware design of this process, as a rule, were aimed at balancing dynamic and thermal conditions throughout the entire volume of the case in order to optimize its use.

 Known column-type apparatuses having a vertical cylindrical body, which is equipped with a nozzle located at the bottom for supplying a fluidizing gas, a gas distribution grid, a heat exchanger, usually a tube, a nozzle for loading solid material, means for removing gaseous products and unloading the spent contact mass (Gelperin N . I. Fundamentals of fluidization technology. - M.: Chemistry, 1967, p. 57).

 With such a constructive implementation of the apparatus, it is not possible to ensure uniformity of the fluidized bed both in the height of the apparatus and in its cross section.

A known apparatus for the synthesis of alkylchlorosilanes in a fluidized bed, also having all of the above structural elements, the body of which has the shape of a truncated inverse cone (SU 167829, 1965)
A common drawback of these devices is that when using an ultrafine contact mass (particle size 50 - 140 microns), it is not possible to create a uniform fluidized bed and temperature field over the entire height of the reactor vessel and its cross section. Regulation of the temperature reaction is difficult, there is a great danger of sintering of the contact mass in the upper part of the housing due to the appearance of stagnant zones. The instability of the thermal regime leads to reduced selectivity of the synthesis process.

 Closest to the proposed invention in technical essence is a fluidized bed reactor for exothermic reactions in a gas-solid system (SU, patent, 990071, class B 01 J 8/18, 1983, prototype), for example, for the synthesis of alkylsilanes.

 The reactor consists of a vertically arranged cylindrical body with nozzles for supplying and discharging the starting materials and synthesis products. A lattice-type gas distributor is located in the lower part of the casing, and in its cavity a heat exchanger made of pipes, the pipes of which are made in the form of field pipes and are combined into a package using bridges made of strip steel.

 The disadvantage of this apparatus is that the cylindrical shape of its body contributes to the deterioration of the uniformity of the fluidized bed, a decrease in the speed of movement of gas-phase components and the pressure of synthesis. These destabilization processes occur due to a decrease in the total volume of gas-phase components as a result of synthesis reactions. Two chloromethyl molecules give one dimethylchlorosilane molecule. The total volume of gas becomes insufficient to create a full fluidized bed in the upper part of the reactor, stagnant zones appear. As we know, a decrease in the rate of movement of gas-phase components and synthesis pressure helps to reduce the rate of reactions. In addition, lattice type gas distributors allow contact mass to fall into the sublattice zone and the possibility of sintering it.

 The technical task of the invention is to increase the productivity of the apparatus and the selectivity of the synthesis process.

This result is achieved due to the fact that the apparatus for the synthesis of alkylchlorosilanes in a fluidized bed includes a vertical housing containing sections having the shape of a cylinder and a truncated forward and reverse cones, with a gas distributor installed inside, a heat exchanger also equipped with means for loading and unloading the contact mass, supply chloralkyl and the output of synthesis products, the body consisting of three sequentially installed sections, the lower of which has the shape of a truncated inverse cone with an angle of inclination of brazed to the vertical axis 5-7.5 ^o , the average has the shape of a cylinder, the ratio of the height of which to the inner diameter is 0.8-1.3, the upper has the shape of a truncated straight cone, the ratio of the height of which to the sum of the heights of the lower and middle sections is 2 -4, the ratio of the inner diameters of the lower and upper ends of the casing is 0.8-1.2, the ratio of the inner diameter of the cylindrical section to the inner diameter of the lower end of the casing is 1.2-2.

 In FIG. 1 shows a General view of the apparatus. The apparatus comprises a housing 1, consisting of a lower section 2 having the shape of a truncated inverse cone, a middle cylindrical section 3 and an upper section 4 having the shape of a truncated straight cone. The geometric parameters of the sections are interconnected by the above ratios. A gas distributor 5 is installed in the lower part of the housing 1, connected to a gas supply manifold 6. A heat exchanger 7 is installed inside the housing, connected to a means for supplying a heat carrier 8. A separator 9 is installed in the upper part of the apparatus. unloading of the contact mass 11, 12.

 The device operates as follows. The contact mass, for example, consisting of silicon powders, copper catalyst and promoters, is loaded into the apparatus using means 11. Through a gas supply manifold 6 and a gas distributor 5 serves a fluidizing reagent - chloralkyl vapor. As a result of this, the contact mass is loosened, a fluidized bed is created, heat and mass transfer processes occur with the formation of alkyl chlorosilanes. The reaction products pass through a separator 9 and are removed from the apparatus, after which they are sent to the condensation system.

 The device may additionally contain other structural elements, devices that do not change the technical nature of this solution.

Tests of the proposed device were carried out in series on a model installation using apparatus mock-ups of three different heights. As a result, it was found that, regardless of the specific geometric dimensions of the apparatus, the results change significantly when the size ratios change, and the nature of the changes is preserved when the apparatus height changes. The table shows data showing the effect of the claimed ratios of geometric parameters on the productivity and selectivity of the direct synthesis of methylchlorosilanes using silicon fractions of 250 μm (KP1) and 140 (KP2)
The following conventions are used in the table:
α is the angle of inclination of the generatrix of the cone of the lower section to the vertical axis;
h -height _NK lower tapered section;
h _c - the height of the cylindrical section;
h _vk - the height of the upper conical section;
d _c - the inner diameter of the cylindrical section;
d _{N. tor} - the lower inner end diameter of the apparatus;
d _V.tor - the upper inner end diameter of the apparatus.

Declared ratios:
α = 5-7.5 ^o ; h _c / d _c = 0.8 - 1.3; h _v.k / (h _n.k + H _c ) = 2-4; d _{N. tor} / d _{V. tor} = 0.8-1.2; d _c / d _n.tor = 1.2-2.

 From the above data it follows that the apparatus for the synthesis of alkylchlorosilanes in a fluidized bed, having a housing, the geometric parameters of which correspond to those described above, works with higher productivity than the prototype, while achieving increased selectivity of the synthesis process. The uniformity of the temperature field over the entire volume of the apparatus body (confirmed by the data of constant monitoring using a variety of temperature sensors) indicates the absence of stagnant zones and the optimal use of usable volume. The device is also characterized by reduced material consumption.

 Analysis of known sources of information did not allow to identify solutions containing features that are consistent with those described in this application, ensuring the achievement of an identical result, which suggests the proposed solution meets the criterion of "inventive step". Positive bench test results make it possible to ensure that the proposed solution meets the criterion of "industrial applicability".

Claims (1)

The apparatus for the synthesis of alkylchlorosilanes in a fluidized bed, comprising a vertical housing with a gas distributor installed inside, a heat exchanger, also equipped with means for supplying raw materials and outputting synthesis products, characterized in that the housing consists of three sections installed in series, the lower of which has the shape of a reverse truncated cone with the angle of inclination of the generatrix to the vertical axis 5 - 7.5 ^o , the average has the shape of a cylinder, the ratio of the height of which to the inner diameter is 0.8 - 1.3, the top has the shape of a straight line a truncated cone, the ratio of the height of which to the sum of the heights of the lower and middle sections is 2 - 4, the ratio of the inner diameters of the lower and upper ends of the casing is 0.8 - 1.2, the ratio of the inner diameter of the cylindrical section in the inner diameter of the lower end of the casing is 1.2 - 2.

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