RU2225752C1 - Reactor for synthesis of hydroxylamine sulfate - Google Patents

Abstract

FIELD: chemical mechanical engineering for performing heterogeneous processes. SUBSTANCE: proposed reactor is provided with coil-type heat exchangers, cantilever shaft located inside reactor short of reaching its bottom and drive consisting of reduction gear and electric motor; reactor is also provided with gas distributing unit mounted in its lower portion. Reactor is additionally provided with heat-exchange jacket, static mixing unit with support for bearing and six propeller-type blades secured on support of coil-type heat exchanger on one side and on support of bearing on other side. Reactor includes cage-type mixer, foam suppressor and longitudinally detachable coupling with sprayer and frequency control converter of drive. Six propeller-type blades are smoothly distributed over perimeter of reactor and are mounted at angle of 23-31 deg. relative to horizontal plane towards flow of reaction mixture fed from beneath through gas distributing unit. EFFECT: increased productivity; improved quality of hydroxylamine sulfate. 6 cl, 7 dwg,1 tbl

Description

The invention relates to chemical engineering, in particular to apparatus for carrying out heterogeneous processes, and can be used in the synthesis of hydroxylamine sulfate in the production of caprolactam in the chemical industry.

A well-known reactor for carrying out reactions in heterogeneous media (gf-tv). (Ushakov VG Modern directions of designing equipment with mixing devices. - M .: Chemical and petroleum engineering, 1985, No. 3, p.3-5) .

The reactor is equipped with two mixers: three-blade and louvered-sheet, mounted on a cantilever shaft and connected through a rigid coupling with a drive from the gearbox and electric motor. In addition, it uses a half-tube heat exchange shirt, a baffle plate and a coil heat exchanger. During the synthesis of hydroxylamine sulfate, chemical processes in this reactor are unstable, the required conversion and the rate of formation of hydroxylamine sulfate are not ensured due to the large loss of reagents in the flue gas. This is explained by the imperfection of the design of the internal elements of the reactor and, as a result, the productivity of the reactor decreases and the quality of hydroxylamine sulfate deteriorates.

Closest to the invention is a reactor containing a vertical housing with a lid and a bottom located along the axis of the housing, a shaft with agitators fixed coaxially on it one below the other, the upper of which has vertically arranged blades, and the lower one is inclined, a gas distributor, an inlet fitting and the output of raw materials and reaction products, in addition, the reactor is equipped with a conical adapter, mixers are made of different diameters, decreasing towards the bottom, and a gas distributor is located in the lower part of the reactor (Auth. certificate. No. 1813559 , 01 J 10/00, 1991).

The disadvantage of this invention is the low quality of the obtained products and reduced productivity while reducing the conversion of reagents due to imperfections in the design of the reactor and, as a consequence, insufficient mixing of the reagents. The objective of the invention is to increase the productivity of the reactor and the quality of hydroxylamine sulfate by improving the design of the reactor.

This object is achieved in that the known hydroxylamine sulfate synthesis reactor equipped with coil heat exchangers, a cantilever shaft located inside the reactor and not touching its bottom, a drive consisting of a gearbox and an electric motor, and a gas distribution device installed in the lower part of the reactor, additionally contains a heat exchange jacket, static mixing device with a support for the bearing located in it and six propeller-type blades fixed on one side on a support of a coil heat exchanger, and on the other hand on a support for a bearing, a cage mixer, antifoam and a longitudinally detachable coupling with a spray, installed respectively in the lower, middle and upper parts of the reactor, and a frequency-control drive converter; however, six propeller-type blades are uniformly distributed around the perimeter of the reactor and are installed at an angle of 23-31 ° to the horizontal plane to meet the flow of the reaction mixture supplied from below through the gas distribution device. In addition, the gas distribution device is made in the form of a pipe with a diameter of 150 mm with side openings with a diameter of 6 mm in an amount of 300 pieces. and fixed in the lower part of the reactor at a distance of 550 mm from its bottom. The sprayer is used to irrigate the spherical part of the reactor with sulfuric acid, which is fed through the pipe of the upper cover of the reactor, and the frequency-control converter for starting the reactor for 1-2 hours to ensure a given speed of the cage mixer and antifoam, as well as two coil heat exchangers are attached to the bottom the reactor by welding with additional supports on the side surface of the reactor, using pipes with a diameter of 100 mm, assembled in 12 turns, and the heat transfer jacket of the reactor is divided into sections and provided with a separate input nozzles coolant in 3 pieces.

The combination of known reactor devices in combination with the proposed additional reactor designs gives it new properties that allow efficient synthesis of hydroxylamine sulfate, which indicates that the proposed technical solution meets the criteria of the invention.

Studies of the synthesis of hydroxylamine sulfate (GAS) in the reactor showed that the chemical processes in it are unstable, the content of nitric oxide and hydrogen in the exhaust gas exceeds the permissible norms and reduces the conversion and the rate of formation of the GAS, because there is an unsatisfactory dispersion of gas in the liquid, gas separation at the shaft of the mixers and injection of gas jets through the liquid layer. This is due to the wrong choice of type of mixer, mixing parameters and imperfection of reactor designs.

To eliminate these drawbacks, the three-blade and louvered-sheet stirrers were replaced with a static mixing device and a stand mixer, the lower bearing support was excluded, and a frequency-control converter was used to start and put the reactor into operation. In addition, a device for uniform distribution of the initial components of the reaction mixture, an acid sprayer, etc. are used.

The schematic diagram of the reactor and its devices is illustrated by drawings, where Fig. 1 shows a reactor, and Fig. 2 is a section along AA in Fig. 1 indicating the inclination and fastening of the propeller-type blades. Gas synthesis reactor includes:

1 - reactor vessel;

2 - heat exchange shirt;

3 - coil heat exchanger;

4 - cantilever shaft;

5 - static mixing device console type;

6 - support for the bearing;

7 - bearing;

8 - propeller-type blades;

9 - support mounting coils;

10 - stand mixer;

11 - antifoam;

12 - longitudinally detachable coupling;

13 - a sprayer;

14 - drive from the gearbox and engine;

15 - frequency-control converter;

16 - gas distribution device.

The reactor operates as follows. At the inlet of the reactor from below, through a gas distribution device 16, a reaction mixture (nitrogen oxide and hydrogen) is fed to fill the reactor up to 80 wt.% Of the maximum volume. To start and put the reactor into operation (judged by the reaction temperature), a frequency-regulating converter 15 is put into operation with a drive from the gearbox and electric motor 14 and, using a longitudinally detachable coupling 12 connecting the motor shaft and cantilever shaft 4, include an antifoam 11 and stand mixer 10. Then the mixture is intensively mixed by means of a static mixing device of cantilever type 5 with propeller type blades 8, which are fixed on one side of the coil support 9, and on the other They are supported by a bearing 6, with a bearing 7. The blades of propeller type 8 are distributed evenly around the perimeter of the reactor, mounted at an angle to the horizontal plane and directed towards the flow of the reaction mixture. This contributes to intensive mixing of the reaction mixture due to turbulence in the flow and uniform distribution of the catalyst throughout the reactor. (The dimensions of the cantilever shaft, its diameter, as well as the installation distances of the cage mixer, static mixing device, antifoam and clutch were determined empirically and are not shown conditionally in the drawings).

After the reactor enters the mode, the frequency-control converter 15 is turned off and the set number of revolutions of the mixing devices 10 and 11 is supported by the drive from the gearbox and electric motor 14 (the switch is not shown conditionally). To reduce the gas phase, an antifoam 11 is used, which is installed at a certain height on the cantilever shaft 4. The synthesis reaction of the HAS is exothermic (occurs in the presence of sulfuric acid on a platinum catalyst). To maintain the specified modes of heat transfer using coil heat exchangers 3, which are attached to the bottom of the reactor and have additional supports on the side surface of the reactor. To remove excess heat, a heat exchange jacket 2 is used, which is divided into sections with separate coolant inlet pipes. The gases released during the synthesis process are discharged through the pipe with the outlet gas pipe, and the finished product through the outlet pipe. To wash the catalyst from the inner surface of the reactor, a sprayer 13 is used; for this, sulfuric acid of a given concentration is supplied through the pipe of the reactor lid.

Thus, using a gas distribution device fixed at a given height, we achieve a uniform distribution of the starting reagents throughout the reactor volume, using a static mixing device, we ensure intensive mixing and uniform distribution of the catalyst suspension throughout the volume of the liquid phase. Using a stand mixer and antifoam, fixed at a given height of the reactor, we exclude the funnel formation of the liquid phase and reduce the entrainment of gases and catalyst, which increases the conversion of the reactants and the reaction rate and, accordingly, increases the productivity of the reactor, as well as improves the quality of hydroxylamine sulfate. The use of an acid sprinkler increases the safety of HAS synthesis and reduces catalyst losses. In addition, the use of a shortened shaft excluded the lower bearing (replaced by the middle one), which reduced the number of accidents and reactor shutdowns associated with a rupture of the bottom of the reactor. The use of a longitudinally split coupling increased the reliability of the drives, and the use of a frequency-control converter ensured a smooth start-up and shutdown of the reactor and reduced the time required to enter the reactor mode and increased the efficiency of its operation and production as a whole. Using a jacket to cool the reactor with separate sections and coolant inlet pipes allows for repair work without shutting down the reactor. In addition, the use of coil heat exchangers located in the liquid phase increased the heat transfer surface, and their attachment to the bottom and side surface increased the rigidity of the reactor structure.

Testing of the reactor was carried out in the synthesis shop of GAS ZAO Kuibyshevazot in 3 square meters. 2002, the table below shows the performance of the proposed reactor and prototype for a given ratio of nitric oxide and hydrogen 1: 1.78, the mixture in the reactor in the amount of 18000 t / h and 15% sulfuric acid in the amount of 1700 t / h.

The table shows the advantage of the proposed reactor.

The introduction of reactors is scheduled for 4 square meters. 2002, in the GAS synthesis workshop for the production of caprolactam of Kuibyshevazot CJSC, (Togliatti). The economic effect of the introduction of 2 million rubles per year.

Claims (6)

1. The synthesis reactor of hydroxylamine sulfate, equipped with coil heat exchangers, a cantilever shaft located inside the reactor and not touching its bottom, a drive consisting of a gearbox and an electric drive, and a gas distribution device installed in the lower part of the reactor, characterized in that it further comprises a static exchange jacket a mixing device with a support for a bearing located in it and six propeller-type blades fixed on one side to a coil heat-bearing support ennika, and on the other hand on the bearing support, cage mixer, antifoam and longitudinally detachable coupling with a spray mounted respectively in the lower, middle and upper part of the reactor, and the frequency-drive converter, with six propeller-type blades distributed evenly the perimeter of the reactor and installed at an angle of 23-31 ° to the horizontal plane towards the flow of the reaction mixture supplied from below through a gas distribution device. 2. The reactor according to claim 1, characterized in that the gas distribution device is made in the form of a pipe with a diameter of 150 mm with side openings with a diameter of 6 mm in an amount of 300 pieces and fixed in the lower part of the reactor at a distance of 500 mm from its bottom. 3. The reactor according to claim 1 or 2, characterized in that the sprayer is used to irrigate the spherical part of the reactor with sulfuric acid, which is fed through the pipe of the upper cover of the reactor. 4. The reactor according to any one of claims 1 to 3, characterized in that the frequency-control converter is used when starting the reactor for 1-2 hours to ensure a predetermined number of revolutions of the stand mixer and antifoam. 5. The reactor according to any one of claims 1 to 4, characterized in that two coil heat exchangers are attached to the bottom of the reactor by welding with additional supports on the side surface of the reactor and coil pipes 100 mm in diameter, assembled in 12 turns. 6. The reactor according to any one of claims 1 to 5, characterized in that the heat exchange jacket is divided into sections equipped with separate pieces of coolant inlet in an amount of 3 pcs.

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