RU177268U1 - REACTOR FOR PRODUCING Aryl Carboxylic Acids - Google Patents

Abstract

The utility model relates to reactors for carrying out liquid-phase heterogeneous chemical-technological processes of aromatic hydrocarbon oxidation with nitric acid and can be used in the production of terephthalic, trimesinic, phthalic, isophthalic, benzoic, naphthalenedicarboxylic acids at elevated temperature and pressure. A reactor for liquid-phase oxidation of aromatic hydrocarbons acid is a vertical cylinder made of anticorrosive material, with fittings for input initially o hydrocarbon and oxidizing agent, exhaust gas outlet, draining the reaction mass, for the sensor of the maximum level of the reaction mass, for the pressure recording device, for the selection of the raw product and the thermowell for temperature control, equipped with a jacket to create the required temperature regime. The technical effect of the liquid-phase oxidation reactor is achieved by in the lower part of the switchgear reactor, with a corrosion-resistant nozzle placed on it, which ensures efficient mixing of the reagents, feeding under pressure, and contributes to faster achievement of high values of the conversion of aromatic hydrocarbon and increase the yield of the corresponding arylcarboxylic acid. The technical effect is also achieved by simplifying the design of the reactor by eliminating the use of mixing devices, which increases the safety of the process, significantly reduces the cost of maintaining the reactor and makes it possible to carry out technological process in continuous mode. 1 ill., 2 tab.

Description

The utility model relates to reactors for carrying out liquid-phase heterogeneous chemical-technological processes of aromatic hydrocarbon oxidation with nitric acid and can be used in the production of terephthalic, trimesinic, phthalic, isophthalic, benzoic, naphthalenedicarboxylic acids at elevated temperature and pressure.

Known capacitive reactor for liquid-phase oxidation of hydrocarbons at elevated temperature and pressure of a horizontal type (patent RU 2108856 C1, IPC6 B01J 10/00). The reactor contains a horizontal cylindrical body, divided into chambers by vertical partitions, pipelines for inputting initial products, withdrawing oxidate, supplying oxidizing gas, withdrawing secondary oxidation vapors, introducing and withdrawing circulating reaction mass, devices for cooling the reaction mass, a collector for circulating secondary oxidation vapors with one or more injection devices. The disadvantage of this device is the design complexity, metal consumption, significant energy consumption.

Known reactor for the liquid phase oxidation of organic compounds in wastewater at high temperature and pressure (US patent 4229296). The reactor consists of a hollow vertical cylindrical body with fittings for the entrance of the reactants and the output of the product and gases. The simplicity of this design will not provide sufficient phase mixing for the process of liquid-phase oxidation of aromatic hydrocarbons with nitric acid, which is a disadvantage of this device.

The closest to the proposed solution to the problem of liquid-phase oxidation of hydrocarbons with nitric acid is the design of a reactor (autoclave) of a capacitive type, placed in an electric furnace (Copyright certificate SU 1669529 A1). The reactor consists of a housing, a removable cover, on which a neck is installed for introducing the shaft of the mixing device into the reaction space of the autoclave, a housing of a screw multilayer tubular heat exchanger is attached to the neck, on which a multi-stage mechanical seal of the shaft of the drive mechanism of the stirring device is installed, the lid has a fitting for loading reagents and unloading of finished products

The use of a capacitive type reactor for liquid-phase oxidation with nitric acid at high temperatures and under pressure using a mixing device has several disadvantages, namely: the difficulty of compaction of the shafts of the stirrers operating in aggressive environments, elevated temperatures and pressures, considerable duration and complexity associated with the frequency of the process.

The basis for the creation of the reactor was the task of developing a simpler and more technologically reliable design that would allow a continuous high-performance and safe process of liquid-phase oxidation of aromatic hydrocarbons without the use of dynamic mixing devices.

The technical effect of the reactor for liquid-phase oxidation of aromatic hydrocarbons with nitric acid is achieved by the fact that the reactor is a vertical cylinder made of anticorrosive material, equipped with fittings for the inlet of the initial hydrocarbon and aqueous solution of nitric acid, outlet of gases, draining the reaction mass, for the sensor of the maximum level of reaction mass, for a pressure recording device, for raw product selection, a thermowell for temperature control, equipped with a jacket to create Parts Required temperature at the bottom of the reactor is provided with a distribution device, which nozzle is located.

The dispenser provides efficient mixing of reactants continuously supplied under pressure. The use of the nozzle contributes to the faster achievement of high values of the conversion of aromatic hydrocarbon and increase the yield of the corresponding arylcarboxylic acid.

This increases the productivity of the reactor and allows to simplify its design by eliminating the use of mixing devices, which significantly reduces the cost of maintaining the reactor. The reactor is designed using corrosion-resistant materials resistant to aggressive media (dilute nitric acid) at high temperatures up to 200 ° C and pressures up to 20 bar created in the process.

The proposed reactor is easy to operate, makes it possible to carry out the process in a continuous mode, which increases productivity, reduces energy losses due to interoperational cooling of the reaction mass or depressurization and allows to achieve a high yield of the target product.

A prototype reactor is currently manufactured and tested.

In FIG. 1 shows a general view of the reactor.

The reactor for liquid-phase oxidation of aromatic hydrocarbons with nitric acid is a vertical cylinder pos. 1, made of titanium, with fittings for entering the source of hydrocarbon pos. 2 and oxidizing agent pos. 3, gas outlet pos. 4, draining the reaction mass pos. 5, for the sensor of the maximum level of reaction mass pos. 6, for a pressure recording device pos. 7, for the selection of the product - raw pos. 8 and thermowell pos. 9 for temperature control, equipped with a jacket pos. 10 to create the required temperature regime with fittings for the inlet (pos. 11) and the outlet of the coolant (pos. 12), in the lower part of the reactor for efficient mixing of the reactants without the use of a mechanical mixing device, a switchgear pos. 13 with the nozzle located on it, pos. 14, made of titanium, which provides a developed phase contact surface with a continuous supply of starting reagents.

With the exception of fittings for the inlet and outlet of the coolant, the inlet of toluene and for the device of the maximum level, which are made of steel 12X18H10T, the material for the remaining fittings is titanium grade VT1-0.

Let us consider the operation of the reactor using the example of liquid-phase oxidation of toluene to produce benzoic acid.

In the reactor pos. 1 high-pressure metering pump through the nozzle pos. 3 serves the estimated amount of a 10-15% solution of nitric acid and the flow of coolant in the shirt pos. 10 heat the reactor to a temperature of plus 170-190 ° C. Then the high-pressure metering pump through the nozzle pos. 2 with a certain flow rate serves the estimated amount of toluene.

After the calculated amount of toluene is fed into the reactor, the temperature and pressure in the reactor have reached the operating parameters (P = 20 ÷ 22 kgf / cm ² , T = plus 170 ÷ 190 ° С), the reactor is put into continuous operation. To do this, without stopping the supply of toluene, the supply of a 10-15% solution of nitric acid to the reactor is started with a metering pump at a certain flow rate. The temperature of the reaction mixture in the reactor is maintained by controlling the temperature of the coolant supplied to the jacket of the reactor.

To exclude clogging, the product line is equipped with electric heating. The temperature on the surface of the pipeline is maintained at least 130 ° C.

The resulting reaction mass from the reactor is then fed to the selection of the target product. Thus, the proposed reactor implements a flow diagram of the liquid phase oxidation process.

The essence of the proposed reactor model is illustrated by the following examples.

Example 1

The oxidation of an aromatic hydrocarbon with diluted nitric acid is carried out in a batch mode reactor at a temperature of 190 ° C and a pressure of 20-22 bar. 42.4 g of aromatic hydrocarbon was charged into the reactor. Received 17.7 g of product. The process was carried out for about 4 hours.

Example 2

The aromatic hydrocarbon is oxidized with diluted nitric acid in a continuous reactor with a nozzle — Rashig rings (titanium, 8 × 8 × 1.5 mm) at a temperature of 190 ° C and a pressure of 20-22 bar. 186 g of aromatic hydrocarbon was charged into the reactor over 9 hours. Received 167 g of product, an average of 18.5 g / hour.

The results are presented in the table.

From a comparison of examples 1 and 2, it can be seen that during continuous operation, productivity increased approximately 4 times.

Example 3

The aromatic hydrocarbon is oxidized with diluted nitric acid in a continuous reactor with a nozzle — Rashig rings (titanium, 8 × 8 × 1.5 mm) at a temperature of 190 ° C and a pressure of 20-22 bar. The process was carried out for about 7 hours. The ratio of aromatic hydrocarbon reagents: nitric acid 1: 3.15 mol.

Example 4

The oxidation of an aromatic hydrocarbon with dilute nitric acid is carried out in a reactor in continuous operation without packing at a temperature of 190 ° C and a pressure of 20-22 bar. The process was carried out for about 7 hours. The ratio of aromatic hydrocarbon reagents: nitric acid 1: 3.15 mol.

The results are presented in the table.

A comparison of examples 3 and 4 shows that the presence of a nozzle in the reactor leads to an increase in the yield of arylcarboxylic acid.

It was experimentally established that due to the proposed reactor design due to its compactness and simplicity of the device:

- increased production safety,

- the probability of emergency depressurization of the reactor is reduced, in contrast to a reactor (autoclave) of a capacitive type, where the weak point is the seal of the mixing device,

- due to the continuous production of the required arylcarboxylic acids, the productivity of the reactor is increased in comparison with a capacitive type reactor, which ultimately allows to reduce energy costs, raw material costs, as well as to reduce the metal consumption of the apparatus.

The entire claimed combination of design features contributes to the achievement of a technical result and ultimately solves the problem.

Claims (1)

    A reactor for liquid-phase oxidation of aromatic hydrocarbons with nitric acid, consisting of a vertical cylinder made of anticorrosive material, with fittings for the input of the initial hydrocarbon and oxidizer, the outlet of gases, the discharge of the reaction mixture, for the sensor of the maximum level of the reaction mixture, for the pressure recording device, for selection product - raw and thermowell for temperature control, equipped with a jacket to create the required temperature and switchgear at the bottom hour a reactor with a nozzle made of anticorrosive material located on it, which ensures the development of a developed phase contact surface with continuous supply of initial reagents

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