CZ546989A3 - Oxidation process of gases containing inflammable and/or explosive components and apparatus for making the same - Google Patents

Description

The invention relates to a process for the oxidation of gases containing flammable and / or explosive components and to a device for carrying out the same.

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Numerous production processes (for example, in some intermediate steps, in the manufacture of imitation leather, in painting, drying, etc.) produce such unusable gases and / or vapors that contain flammable and / or explosive components. In many cases, these gases had to be discharged in confined spaces, which in themselves were exposed to the risk of fire or explosion.

The removal of these gases can be solved by oxidation (incineration) in the simplest and least costly manner, but safety regulations prohibit the operation of hazardous fires in areas where this could be the cause of a fire or explosion.

As is known, the oxidation of the gases takes place in the presence of the respective catalysts even at a temperature below the ignition temperature and in a concentration range below the lower flammability limit. The Hungarian patent describes a process for the catalytic oxidation of such gases, but no guidance is given as to how gases containing flammable or non-combustible gases could be used. Explosive components catalytically oxidize (even in areas at risk of fire or explosion) without this activity being a danger of fire and explosion ·

Various catalytic combustion devices (eg catalytic gas furnace SZIESTA) are known which, however, must not be used in areas at risk of fire and explosion, since combustion does not take place entirely without flames (so-called micro-flames are created which can cause an explosion or fire) ).

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the aforementioned drawbacks and to provide a method and apparatus that allow safe oxides; gas detectors containing various flammable and explosive components ©

It has been the object of the present invention that when the gas is fed to a closed reactor, the catalyst is arranged in such a way that free sections of the gas path shorter than that required to produce flames are provided, further by temperature control ee to prevent overheating and by appropriate selection of the gas supply rate, further propagation of flame generated in the enclosure of the reactor as a result of possible damage, oxidation of flammable and / or explosive gases can also be carried out in an area where there is a risk of fire and / or explosion ©

prevents it from reaching the temperature at which ignition occurs ©? / 5W 9 · · * 5 f f f f f f f f f f f f f f f f f f * · ««

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Based on this finding, the object of the present invention has been to provide a method for oxidizing gases containing flammable and / or explosive components by passing the gas into a reaction zone containing a catalyst in which it is heated to the temperature required for the catalytic reaction. led through a closed heating zone into a closed reaction zone, wherein the gas transport velocity is two to five times the combustion velocity of the flammable and / or explosive component exhibiting the highest combustion velocity; and, by controlling the temperature, the gas is maintained at a temperature required for the catalytic reaction, which is, however, lower than the temperature at which the gas ignites.

COMMON LAWYING OFFICE ALL ALL GREEN QUARTER CALENDAR AND PARTNERS

120 00 Prara 2, Hálkova 2 Czech Republic

In an apparatus for oxidizing gases containing flammable and / or explosive components, the apparatus comprising a reactor comprising a catalyst, the reactor is provided with a gas inlet and outlet as well as a controllable heating device. The apparatus according to the invention is characterized in that it comprises a closed reactor containing a granular catalyst, a closed hot chamber is provided upstream of the reactor, a heating device is provided in the heating chamber, the heating chamber also contains a catalyst, and in the heating chamber as well as the reactor. there are provided temperature sensors connected via a control unit to a controllable heating device.

In a preferred embodiment of the device according to the invention, the heating chamber is provided with an electric heating device, which is connected to the encapsulated switch cabinet and is provided with a pressure sensor as well as with an overpressure device in the switch cabinet.

In another preferred embodiment of the device according to the invention, the heat exchanger comprises one side connected upstream of the reactor and the other side downstream of the reactor. Preferably, the reactor, the heating chamber and optionally the heat exchanger form one unit.

It is also advantageous if two parallel connected heating chambers are provided ·

The following examples and the accompanying drawing illustrate the invention in greater detail. The drawing in FIG. 1 shows a schematic embodiment of the apparatus according to the invention.

The apparatus shown comprises a closed reactor 4 provided with an inlet 41 and a gas outlet 42. A granular catalyst is arranged in reactor 1. The gas discharge 42 from the reactor 6 is connected in a gas-tight manner to the heat exchanger tubes 6 from which the oxidized gas flows to the stack 21.

The inlet to the shell side of the heat exchanger 6 is connected to a fan 1 into which the gas to be oxidized enters through the flame shutter 8 (for example, an instantaneous solenoid valve). The outlet from the jacket side is connected in a gas-tight manner to the gas supply 41 to the reactor 6 via two heating chambers connected in parallel.

The heating chambers 2 are also filled with granular catalyst material (the type of which is expediently, but not necessarily identical, and the type of catalyst material used in the reactor 6). The heating chambers 2l are connected with pressurized electric switch boxes 2

Controllable electric heating O + devices 31 of the heating chambers 3 are connected to the switch cabinets 5, the heating devices being adapted to extend into the bed of the granular catalyst.

On the one hand, the switch boxes 1 are connected via a pressure regulating filter 2 to a (not shown) device providing pressurized air or inert gas, on the other hand, to an outlet line 6 provided with a solenoid valve 61.

Suitably, the reactor 6 and the heating chambers 2 are combined in one common unit to prevent heat losses.

The device according to the invention comprises a control panel 10 and a control unit 50 which are connected to each other, to the temperature sensors 43, 44 and 32 (e.g. temperature switches) connected to the heating chambers J, and to the pressure sensors 51 (e.g. pressure sensors). switches) connected to switchgear 2 ·

In the apparatus shown, the method according to the invention is carried out as follows:

The gas to be cleaned (oxidized) is sucked by the fan 1 through the flame shutter 8 and pushed through the jacket side of the heat exchanger 6 into parallel healed heating chambers J.

Here, the gas preheated in the heat exchanger 6 is heated by the electric heating means 31 (which is embedded in the granular catalyst material) to the temperature required for the catalytic oxidation (80 to 550 ° C, preferably 180 to 330 ° C). The gas from the heating chambers J enters the reactor 6, where the catalytic oxidation is completed. The oxidized gas stream (cleaned) flows through the heat exchanger tubes 6 to the stack 21, while countercurrently preheating the gas stream to be purified.

The gas transport velocity is chosen so that it is greater *, expediently two to five times, than the combustion rate of the most dangerous (ie having the highest combustion rate) gas (methane) ·

2 in the switch cabinet ^{86 with n} ^ í maintain pressure to them from outside, the possibility of danger of fire and explosion.

- 7 air could not penetrate. They must be purged with compressed air or inert gas before operation. · The prescribed overpressure (eg 100 Pa) is controlled by the respective SI device. · If the internal pressure in the switch box does not fall below the prescribed value (eg 50 Pa) during operation, automatically switches off the heating elements 31 ©

The switching on of the main switch is only possible after flushing of the switch boxes 5 while generating the corresponding overpressure. Only then can the fan 1 be started and then the electric heater is switched on. If the fan stops running, the electric heater switches off automatically ·

If the temperature of the catalyst bed exceeds the permissible value, the temperature sensors 43, 44 and 32 signal an operating fault at the control panel 10 and the control unit 20 which switch off the heating or, if necessary, the entire device.

Suitably, the failure-free condition of the electric heating devices is also checked by means of appropriate devices. Individual faults in the event of an operating fault are indicated on the control panel by acoustic and light signals. There are three reasons for the temperature to rise:

a) fan failure 1

b) damage to the control circuit

(c) increasing the concentration of pollutants.

In all three cases, the main switch will turn off the heating.

Since the flow resistance imposed by the apparatus and the catalyst bed therein is small (2000 to 3000 Pa), the chimney can act as a safety shutter. This is not a source of danger when blown.

b

In the process according to the invention and in the apparatus for carrying it out (with the known choice of catalyst bed material), it is possible to oxidize e.g.

Pollutant gas streams to purify a variety of gases} ¹ · no C / A automatic hydrocarbons, normal hydrocarbons, cyclic hydrocarbons, hydrocarbons containing oxygen, sulfur and nitrogen, hydrocarbon derivatives, carbon monoxide, hydrogen sulfide, mercaptans and ammonia ·

Apparatus (eg fans) and equipment (eg pressure switches, solenoid valves) provided in potentially explosive areas must, of course, be made in an explosion-proof design.

Suitably, the chimney 21 and the piping are provided with vibration dampers (not shown). The heating chambers 2, the reactor 6 and the heat exchanger 2 are expediently combined in one block by means of welded joints corresponding to the respective technological sequence and arranged on the respective base.

The oxidation of the contaminants contained in the gaseous stream to be cleaned takes place on the surface of the catalyst heated to a temperature below the ignition temperature without the appearance of flames, since in the granular catalyst material surrounding the device the free path length is shorter than critical value.

TV - <77

WO 061

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DETAILED DESCRIPTION OF THE INVENTION

The use of the method and apparatus for carrying out the process of the present invention is illustrated in greater detail by operating a catalytically oxidizing plant having a capacity of 1000 m _e h which is included in the process operation of a fine chemical plant.

The device according to the invention is located at the level of the plant roof in a space surrounded by numerous ventilation openings. The object of the device is to remove harmful as well as flammable and / or explosive gaseous components arising from the production of individual intermediates in the decomposition of the remains of the Grignard reagents.

In a part of the potentially explosive atmosphere, a reactor was assembled into a block with a heat exchanger and heating chambers, a fan equipped with an overpressure-protected terminal block and an explosion-proof motor, as well as appropriate measuring and action units connected to the required measuring circuits, cables and pipelines.

Outside the part of the area at risk of explosion, a control unit of data important in terms of traffic management, along with processors, information elements and start-ups was modified in the control room. switch-off switches.

The energy transfer elements and the process control microprocessor are arranged in an electric cell on the ground floor.

The technology used is a set of 27 sub-steps, which lasts 21 hours and is carried out in three autoclaves, each having a volume of 4.5 m. In the first 4.5 hours, 16 kg of tetrahydrofuran and 18 kg of methylene chloride (dichloromethane) were fed uniformly into the catalytically oxidizing reactor (adiabatic temperature increase of 215 ° C). No gas leaks between 4.5 and 5 hours, 20 kg of tetrahydrofuran, 18 kg of ethylene and 16 kg of toluene arrive at the reactor from 5 to 6 pm (adiabatic temperature increase of 145 ° C). From 4pm to 9pm it leaves the autoclave and 32 kg of methanol and iV sw - bQO & i come into the catalytic reactor.

8b kg toluene (adiabatic temperature rise 183 ° C). The venting of the autoclaves is connected to the suction branch of the ventilator while being protected against fire. Furthermore, a device for supplying the air required for oxidation is connected to the suction port of the fan.

The reactor heating chamber contains 2 x 100 turf of HPS-II / 13 catalyst (manufactured by KOPORC Budapest), modified as spoke wheels and consisting of palladium on a cordierite support. In the reactor space for the catalytic oxidation, there are 100 pounds of MPS-II / 7 catalyst (manufactured by KOPORC Budapest) in the form of spheres formed of palladium on an alumina support.

To test the functionality prescribed for safety reasons, the overpressure-protected terminal box is purged with nitrogen several times for five minutes, the drain valves are closed.

When a preset overpressure of 100 Pa is reached, the fan may be actuated. When the sensors indicate a pressure in the reactor corresponding to a prescribed flow rate, heating may be involved. After reaching the minimum temperatures prescribed for each location of the plant (for gas supplied to the heating chamber: 150 ° C, for gas supplied to the reactor: 220 ° C, for gas leaving the reactor: 200 ° C), a gas mixture is possible fed from the autoclaves to the reactor. Once the prescribed temperatures have been reached, the degree of reaction of the components of the exhaust air leaving the autoclave is at least 99%.

The gas mixture coming from the autoclaves, after mixing with the air required for oxidation, is blown through the fan through the casing side of the heat exchanger into the heating chamber with electric heating.

On the shell side of the heat exchanger, a gaseous stream is conducted in countercurrent with the cleaned hot gaseous stream, thereby heating. In a heating chamber with continuously controlled heating, the gaseous stream is heated to a temperature necessary for the effective operation of the catalyst. The thermal content of the gaseous stream coming from the autoclaves is released to a lesser extent in the heating chamber, for the most part in the reactor space. The heating elements connected to the temperature sensors, together with the corresponding switches, ensure a uniform temperature in the reactor space (i δ ° C) throughout the process. When the permissible temperature is exceeded, the operation of the entire system is automatically stopped by means of the built-in safety devices.

Claims (6)

PATENT CLAIMS A process for the oxidation of gases containing flammable and / or explosive components, wherein the gas is directed to a reaction zone containing a catalyst in which it is heated to a temperature necessary for the catalytic reaction, characterized in that the gas is led through a closed heating zone into a closed reaction zone wherein the gas transport velocity is two to five times the combustion velocity of the flammable and / or explosive component having the highest combustion velocity, the length of the free gas path in the heating zone and reaction zone is shorter than the critical value due to the use of granular catalyst material the heat is maintained at the temperature required for the catalytic reaction, which, however, is lower than the temperature at which the gas ignites. Apparatus for oxidizing gases containing flammable and / or explosive components, comprising a controllable heater, a pressure and / or velocity boosting unit, and a catalyst comprising a reactor having a feed line (gas line), characterized in that: comprising a closed, granular catalyst comprising a reactor (4), in advance of which a closed heating chamber (3) is provided, and temperature sensors (32, 43, 44) associated with the heating chamber (3) and the reactor (4) connected via a control unit (20) with an adjustable heater (31). Device according to claim 2, characterized in that the heating chamber (3) is provided with a heating element (31) which is connected to the closed switch box (5) and the switch box (5) is provided with a device providing pressure overpressure as well as pressure sensor (51). Device according to claim 2 or 3, characterized in that it comprises a heat exchanger (2), one side of which is connected between the pressure and / or speed increase unit (1) and the heating chamber (3), and the other side is connected between the reactor (4) and the chimney (21). - 10 Device according to claims 2 to 4, characterized in that the reactor (4), the heating chamber (3) and optionally the heat exchanger (2) form a single unit. Device according to claims 2 to 5, characterized in that it comprises two heating chambers (3) connected in parallel to each other.