SK279403B6 - Method for oxidation of gases containing combustible and/or explosive components and device for carrying out this method - Google Patents

Abstract

A method for a combustible and/or explosive gases oxidation in which a gas is being led into a catalyst-containing reactor wherein it is heated up to a temperature necessary for the catalytic oxidation. The gas is kept at a temperature necessary for the catalytic oxidation, in a closed reactor, and is thus prevented from being flashed. A device for processing the above mentioned method includes a spheroidal catalyzer provided with a gas outlet and inlet as well as a controllable heating device. According to the invention, there is an enclosed heating chamber (3) arranged in front of the closed catalyst-containing reactor (4). Both the heating chamber (3) as well as reactor (4) are provided with heat transducers (32, 43, 44) which are connected, via a control unit (20), with the controllable heating device (31).

Description

Technical field

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

BACKGROUND OF THE INVENTION

In many manufacturing processes (for example, in some intermediate steps, in the manufacture of imitation leather, in painting, drying, etc.), such unusable gases and / or vapors are produced which contain flammable and / or explosive components. In many cases, it was necessary to discharge these gases in confined spaces that were already exposed to the risk of fire or explosion.

The removal of these gases can be handled by oxidation (incineration) in the simplest and least costly manner, but safety regulations prohibit the operation of hazardous fire hazards in areas or locations where this could cause 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 flash point and in a concentration range below the lower flammability limit. The Hungarian patent describes a method for the catalytic oxidation of such gases, but no guidance is given as to how gases containing flammable and / or flammable gases could be used. explosive components catalytic oxidize (even in areas at risk of fire or explosion) without this activity being dangerous due to the possibility of fire and explosion.

Various catalytic incinerators are known (for example, catalytic gas furnace SZIESTA), but they 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 can arise which can cause an explosion or fire).

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION It is an object of the present invention to overcome these drawbacks, as well as to provide a method and apparatus that allow the safe oxidation of gases containing various flammable and explosive components.

It has been the object of the 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 are provided shorter than necessary for the formation of flames, where temperature control prevents By overheating and appropriately selecting the rate of gas delivery to further propagate the flame generated in the confined space of the reactor as a result of potential damage, oxidation of flammable and / or explosive gases can also be performed in an area where there is a risk of fire and / or explosion.

Based on this knowledge, the problem has been solved by a method of oxidizing gases containing flammable and / or explosive components, in which the gas is introduced into a reactor containing a catalyst, where it is heated to the temperature required for catalytic oxidation using closed gas. a reactor in which the gas is maintained at the temperature required for catalytic oxidation and the temperature is prevented from reaching the temperature at which ignition occurs.

In apparatus for oxidizing gases containing flammable and / or explosive components, the apparatus comprising a reactor containing a catalyst, the reactor is provided with a gas inlet and outlet as well as a controllable heating mechanism. The apparatus according to the invention is characterized in that it comprises a closed reactor containing a granular catalyst, a closed heat chamber is arranged in front of the reactor, a heating mechanism is provided in the heating chamber, the heating chamber also contains catalyst and via a control unit with adjustable heating mechanism.

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

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 constitute one unit.

It is likewise advantageous if two heating chambers are connected in parallel.

BRIEF DESCRIPTION OF THE DRAWINGS

The following examples and the accompanying drawing illustrate the invention in more detail. The drawing of FIG. 1 is a schematic representation of a device according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The illustrated apparatus comprises a closed reactor 4 provided with an inlet 41 and a gas outlet 42. A granular catalyst is arranged in the reactor 4. The gas discharge 42 from the reactor 4 is connected in a gas-tight manner to the heat exchanger tubes 2 from which the oxidized gas flows to the stack 21.

The inlet to the shell side of the heat exchanger 2 is connected to a fan 1 into which the gas to be oxidized enters through the flame shutter 8 (for example a solenoid solenoid valve). The outlet from the jacket side is connected in gas-tight manner via two parallel connected heating chambers 3 to a gas supply 41 to the reactor.

4th

The heating chambers 3 are also filled with granular catalyst material (the type of which is expediently but not necessarily identical to the type of catalyst material used in the reactor 4). Pressurized electrical switch boxes 5 are connected to the heating chambers 5. Controllable heating mechanisms 31 of the heating chambers 3 are connected to the switch boxes 5, the heating mechanisms being adapted to extend into the bed of the granular catalyst.

The switch boxes 5 are connected on the one hand through a pressure regulating filter 7 with a (not shown) mechanism which provides overpressure with the supplied compressed air or inert gas, on the other hand with an outlet line 6 provided with a solenoid valve 61.

To some extent, the reactor 4 and the heating chambers 3 are combined in a single unit to prevent heat loss.

The device according to the invention comprises a control panel 10 and a control unit 20 which are connected to one another, to the temperature sensors 43, 44 and 32 (for example temperature switches) connected to the heating chambers 3 and to the pressure sensors 51 (for example pressure switches). connected to switch boxes 5.

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 2 into the parallel connected heating chambers 3.

Here, the gas preheated in the heat exchanger 2 is heated by the electric heating mechanism 31 (which is embedded in the granular catalyst material) to a temperature necessary for catalytic oxidation (80 to 550 ° C, preferably 180 to 330 ° C). From the heating chambers 3, gas is supplied to the reactor 4 where the catalytic oxidation is completed. The oxidized gas stream (cleaned) passes through the heat exchanger tubes 2 to the stack 21, while countercurrently preheating the gas stream to be purified.

The gas transport velocity is selected so that it is greater, preferably two to five times, than the combustion rate of the most dangerous (i.e. having the highest combustion rate) gas (methane).

Switchgear 5 must be kept under positive pressure to prevent air from entering the outside of the fire and explosion hazard. They must be purged with compressed air or inert gas before operation. The prescribed overpressure (e.g. 100 Pa) is controlled by the respective mechanism 51. If during operation the internal pressure in the switch box falls below the prescribed value (e.g. 50 Pa), the mechanism 51 automatically switches off the heating mechanism 31.

It is only possible to switch on the main switch after flushing the switch boxes 5 while generating the corresponding overpressure. Only then can the fan 1 be started, followed by electric heating. 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 to the control panel 10 and the control unit 20, which switch off the heating or, if necessary, the entire device.

The failure-free condition of the electrical heating mechanisms 31 is also monitored by means of appropriate devices. Individual defects or operating faults are signaled on the control pulse 10 by audible 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 placed by the device and the catalyst bed therein is small (2000 to 3000 Pa), the stack can act as a safety shutter. This is not a source of danger when blown.

The process according to the invention and the apparatus for carrying it out (with the known choice of catalyst bed material) can be oxidized, i. j. purify a variety of gases, gaseous streams containing polluting (e.g. aromatic) hydrocarbons, normal hydrocarbons, cyclic hydrocarbons, hydrocarbons containing oxygen, sulfur and nitrogen, hydrocarbon derivatives, carbon monoxide, hydrogen sulfide, mercaptans and ammonia.

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

The duct chimney 31a is provided with vibration dampers (not shown) to some extent. The heating chambers 3, the reactor 4 and the heat exchanger 2 are purposefully combined into one block by means of welded joints corresponding to the respective technological sequence and arranged on the respective base.

The oxidation of the pollutants contained in the gas 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 the free path length is shorter than critical in the granular catalyst material surrounding these mechanisms. Value.

Claims (6)

PATENT CLAIMS A method for oxidizing gases containing flammable and / or explosive components, wherein the gas is fed to a reaction zone containing a catalyst in which it is heated to a temperature necessary for catalytic oxidation, characterized in that the gas is passed through a closed heating zone into a closed reaction zone wherein the transport rate is two to five times the combustion rate of the gas having the highest combustion rate, the length of the free gas path in the heating zone as well as in the reaction zone is shorter than the critical value due to the use of granular catalyst material; but which is below the temperature at which the gas ignites. Apparatus for the oxidation of gases containing flammable and / or explosive components, comprising a reactor containing a catalyst, said reactor being equipped with a gas inlet and outlet as well as a controllable heating mechanism, characterized in that it comprises a closed catalyst containing the reactor (4) before providing a closed heating chamber (3) and thermal sensors (32, 43, 44) associated with the heating chamber (3) and the reactor (4), which are connected via a control unit (20) to a controllable heating mechanism (31). Device according to claim 2, characterized in that the heating chamber (3) is provided with an electric heating mechanism (31) which is connected to a closed encapsulated switch box (5) and the switch box (5) is provided with an overpressure mechanism as well as a pressure sensor (51). Device according to claims 2 and 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 reactor (4) and chimney (21). 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) which are connected in parallel to each other.