RU2001938C1 - Plant for thermal noncatalytic cracking of hydrocarbons in absence of hydrogen - Google Patents

Abstract

Use in the petrochemical industry for the production of ethylene and other lower olefins, in particular in tube furnaces of thermal non-catalytic cracking of hydrocarbons in the absence of hydrogen. Summary of the invention, in a plant containing a pyrolysis furnace with convective and radiant chambers and with a coil-reactor installed in the center of the radiant chamber, including vertical pipes, adjacent of which are connected by upper and lower cams, installed outside the reactor generating steam pressure pulses the gas mixture in the reactor, the device and the damping device installed at the outlet of the reactor, an oxidizer receiver is installed, the device is connected through the generating pressure pulses of the gas-vapor mixture to each upper jar of the reactor, and the device generating pressure pulses of the gas-vapor mixture is made in the form of a distributing valve including a cylindrical body with radial holes around the perimeter and with upper and lower covers, through which passes the shaft located in the housing and connected to the electric motor a rotor collar, in which a cutout is made with a width equal to the diameter of the radial hole in the valve body and with the bottom edge located under the radial hole of the valve, and the upper cover of the valve body is equipped with a nozzle for introducing oxidant from the receiver, the upper part of each upper channel of the reactor having an injection nozzle oxidizer from the control valve 5 il.

Description

The invention relates to thermal non-catalytic cracking of hydrocarbons in the absence of hydrogen, in particular to tubular pyrolysis furnaces. The plant can be used in the petrochemical industry to produce ethylene and other lower olefins.

The pyrolysis furnace is known, which contains two parallel radiant chambers and a common convective chamber located above them. In the convection chamber there are sections for convective heating of raw materials and steam, and in the center of the radiant chambers vertical reaction coils connected to the convection section are installed in one row along the side walls heating raw materials and with quenching-evaporation apparatus. During the pyrolysis of hydrocarbon feeds in the known pyrolysis furnace, the pyrogas outlet temperature is maintained at a relatively high temperature of about 850 ° C, which causes a rather intense coc-correlation on the inner surface of the tubes of the reaction coils. In the pyrolysis of heavy raw materials such as atmospheric gas oil, this drawback is exacerbated.

The pyrolysis furnace is also known, which contains a convective and radiant chamber with a coil-reactor installed in the center of the radiant chamber, including vertical pipes adjacent to which are connected by upper and lower cams. The inlet of the reactor coil is connected to a piston or membrane-type mechanical device generating pressure pulses, and to the outlet, to a damping device made in the form of a hollow cylindrical chamber.

Due to the presence of the pulse generating device pressure in the reaction volume, pressure pulsation of the reacting vapor-gas mixture with a certain frequency and amplitude takes place. This reduces the growth rate of coke deposits on the walls of the reactor. The presence of a damping device connected to the reactor outlet smooths out pressure pulsations of the vapor-gas mixture at the reactor outlet to ensure normal post-treatment of the pyrolysis products.

However, the known pyrolysis furnace has significant disadvantages. First, the pressure pulses of the vapor-gas mixture generated at the inlet of the reactor are subject to inevitable and natural attenuation as the mixture passes through the reactor. As a result, in the output part

reactor, where, due to the high temperature, the most intense coke deposition takes place, the amplitude of the pressure pulsations will be so small that it will not provide the desired effect. To ensure the optimum amplitude at the outlet of the reactor, its value at the inlet must be so high that this necessitates the introduction of design measures related to work under pressure. As a result of this, the coke yield during pyrolysis of straight gasoline and gas oil in a known furnace is rather high — 0.4 and 0.6 wt%, respectively, for the passed feedstock. Secondly, any kind of mechanical devices, including piston and membrane, connected directly to the reactor volume, are characterized by low reliability in operation, which is due to

exposure to heat, erosion and corrosion. This results in long downtimes of the pyrolysis furnace and significant repair costs.

The aim of the invention is to provide

plants with high operational reliability by reducing coke formation on the walls of the pyrolysis furnace coil reactor.

The problem is solved in that

installation for thermal non-catalytic cracking of hydrocarbons in the absence of hydrogen, containing a pyrolysis furnace with convective and radiant chambers and with a coil-reactor installed in the center of the radiant chamber, including vertical pipes adjacent to which are connected by upper and lower cams, installed outside the reactor generating pressure pulses of the vapor-gas mixture in re

the device and the damping device installed at the outlet of the reactor; it is equipped with a receiver with an oxidizing agent connected through a device generating pulses of pressure from the vapor-gas mixture

each upper jaw of the reactor, while generating pressure pulses of the vapor-gas mixture, the device is made in the form of a distributing valve, including a cylindrical body with radial

holes along the perimeter and with upper and lower covers, through which the shaft of the rotor located in the housing and connected with the electric motor passes, in which a cut is made with a width equal to the diameter

a radial hole in the valve body and with a lower edge under the radial hole of the valve, and the upper cover of the valve body is equipped with a fitting for introducing oxidant from the receiver, the upper part of each reactor

equipped with a nozzle for introducing an oxidizing agent from a distribution valve.

In the proposed, according to the invention, the design of the thermal cracking unit in the reaction volume of the coil-reactor is distributed along the length and discrete in time serves metered volumes of air or oxygen (i.e., oxidizing agent). At the points of entry of the oxidizing agent, microexplosion occurs, which generates pressure pulses of the vapor-gas mixture uniformly distributed along the entire length of the reactor coil, which helps to reduce coke formation on its walls. Due to the absence of mechanical devices for generating pressure pulses in the high temperature zone, the operational reliability of the installation is increased, thereby reducing downtime and repair costs.

In FIG. 1 and 2 show a installation with longitudinal and transverse sections of a pyrolysis furnace; in FIG. 3 - valve distributor, longitudinal section; in FIG. 4 is a section AA in FIG. 3; in FIG. 5 - upper kalach coil of the reactor, section.

A thermal cracking installation includes a pyrolysis furnace, which comprises a convection chamber 1 with a feed and steam heating section 2 located therein, a radiant chamber 3 connected to a convective chamber 1 by a chimney 4. In the center of the radiant chamber 3, a coil is installed along its longitudinal axis reactor 5, including vertical pipes 6 connected by upper and lower cams 7. In the upper cams 7 nozzles are made 8. Outside of the radiant chamber 3. a damping device 9 is placed, connected to the outlet of the coil-reactor 5 and representing oboj hollow cylindrical chamber. The installation also contains a valve-distributor 10 located outside the pyrolysis furnace 3, an oxidizer receiver 11, and a drive electric motor 12. The valve-distributor 10 is made in the form of a cylindrical body 13 with upper 14 and lower 15 covers. In the covers 14 and 15, central holes 16 and 17 are made with sealing assemblies 18 and 19. In addition, in the top cover 14 there is a peripheral hole 20 connected to the oxidizer receiver 11. In the cylindrical body 13, radial holes 21 are made along the perimeter with the same pitch, connected by pipelines 22 with nozzles 8. Inside the cylindrical body 13 coaxially without lateral charge a rotor 23 is placed, the lower axis 24 of which is installed in the sealing assembly 19 of the central hole 17 of the lower cover 15, and the upper drive shaft 25 is sealed the flange assembly 18 of the central hole 16 of the upper cover 14. The shaft 25 is connected to the drive motor 12. The upper end surface of the rotor 23, the cylindrical body 13 and the upper cover 14 form a receiving chamber 26. A vertical cutout 27 is made in the body of the rotor 23, whose lower edge is located

below the bottom edge of the radial holes

21 in a cylindrical housing 13, and the width

equal to the diameter of the radial hole 21.

Installation works as follows.

5 Raw materials, e.g. straight fuel gasoline

and water vapor in an amount of 50% by weight of the feed is fed to the convection heating section 2 of the pyrolysis furnace, where the gas-vapor mixture is heated to 500-600 ° C. Then the vapor-gas mixture is fed into the coil-reactor 5, where due to the heat burned in the radiant chamber 3 of the fuel gas, it is heated to 800-850 ° C, and the products obtained as a result of decomposition of the raw material are sent for cooling. The flue gases produced by burning fuel gas are sent through a chimney 4 and a convection chamber 1 to a chimney. The oxidizing agent (oxygen or air) vis receiver oxidizing agent 11 is served in

0 receiving chamber 26, from which it enters both the cutout 27 of the rotor 23 and through the opposite cutout, a radial hole 21 and a pipe into one of the nozzles 8. When a portion of the oxidizing agent is fed into the reaction zone

5, microexplosion occurs, which causes a pressure jump in the vapor-gas mixture. Due to the rotation of the rotor 23 with the help of a drive motor 12, the oxidizing agent is alternately supplied to all nozzles 8 in the upper

0 kalach 7 of the coil-reactor 5. Providing a continuous pulsation of the pressure of the vapor-gas mixture in the coil-reactor 5. Pressure pulsations prevent the deposition of coke on the inner surface of the pipes 6

5 of the reactor coil 5. The amplitude and frequency of the pressure pulsations are controlled by the rotational speed of the rotor 23 and the pressure of the oxidizing agent in the receiver 11. To eliminate the negative effect of pressure pulsations

0 gas-vapor mixture for the subsequent processing of pyrolysis (quenching, washing, compression, separation, etc.) at the outlet of the coil-reactor 5, a damping device 9 is installed.

5

Thus, the implementation of this invention in industry will reduce the growth rate of coke deposits on the walls of the pyrolysis reactor, reduce downtime and repair costs.

(56) U.S. Patent

No. 3274978, class 122-356, 1966.

Claims (1)

The claims INSTALLATION FOR THERMAL NON-CATALYTIC CRACKING OF HYDROCARBONS IN THE ABSENCE OF HYDROGEN, containing a pyrolysis furnace with convective and radiant chambers and with a coil-reactor installed in the center of the radiant chamber, including vertical pipes adjacent to which the upper and lower pressure pulses are connected mixtures in the reactor, a device and a damping device installed at the outlet of the reactor, characterized in that, in order to increase operational reliability those furnaces by reducing coke formation on the walls of the reactor tubes, the apparatus is equipped with an oxidizing receiver coupled through pressure generating pulses. US Pat. No. 4,271,007, cl. C 10 G 9/16, 1981 neither a steam-gas mixture device with each upper jaw of the reactor, while the pressure-generating pulse of the gas-vapor mixture device is made in the form of a distributor valve including a cylindrical body with radial holes around the perimeter and with upper and lower covers through which the shaft located in the body passes and a rotor associated with an electric motor, in which a cut is made with a width equal to the diameter of the radial hole in the valve body, and with the location of the lower edge under the radial hole of the valve, and the upper cover of the valve body provided with a fitting for introducing an oxidizing agent from the receiver, the upper part of each top of the reactor having a nozzle for introducing an oxidizing agent from a distribution valve. VSL VÜXXLLArVÜxVVU Q XX / VVSLLLLLL Fie. 1 dode steam Raw materials Pyrogas Water vapor Raw materials. Residant Oxidant 26 W FIG. 2. I, 18 Ik K 2 / I C-1 Oxidizer 8 Snake Fig.Z 73 22 eleven tpt / e5