FI95875B - Method and apparatus for oxidizing gases containing flammable and / or explosive components - Google Patents

Description

95875

Method and apparatus for oxidizing gases containing flammable and / or explosive components

The invention relates to a method and an apparatus for oxidizing gases containing fire-5 and / or explosive components.

Numerous processes (e.g., media production, artificial leather production, varnishing, drying, etc.) generate useless gases and / or vapors that contain flammable and / or explosive components. In many cases, these gases must be released in enclosed spaces which are in themselves flammable and explosive.

The removal of these gases can be solved most simply and most advantageously by oxidation (incineration), however, the instructions in the standards prohibit flammable activities in rooms or places where this could cause a fire or explosion.

It is known to oxidize the individual gases in the presence of the corresponding catalysts also at temperatures below the flash point and in the concentration range below the lower flammability limit. HU 171 795 proposes a solution for the catalytic oxidation of such gases, but does not show how flammable gases and explosive gases could be catalytically oxidized (be in fire and explosion hazardous spaces) without this activity being flammable and explosive.

Various catalytic heaters 30 are known (e.g. catalytic gas-latest SZIESZTA), but these should not be used in fire and explosion hazardous areas, as combustion does not take place completely without a flame (so-called micro-flames can be generated which can cause an explosion or fire).

The object of the present invention is to overcome the above-mentioned drawbacks and to develop a method and an apparatus which enable the safe oxidation of gases containing various flammable and explosive components.

The invention is based on the finding that in the case where gas is introduced into a closed reactor and a corresponding catalyst is provided so as to ensure shorter free spacing than required for flame formation and in addition temperature control prevents overheating and gas feed rate the spread of flames due to possible damage, the oxidation of flammable and / or explosive gases can also be carried out in a flammable and / or explosive atmosphere.

Based on this finding, the proposed task 15 was solved by a method for oxidizing gases containing flammable and / or explosive components, introducing the gas into a reactor containing a catalyst, bringing it to the temperature required for catalytic oxidation, and using a closed reactor according to the invention. temperature, and preventing the temperature from reaching the ignition temperature of the gas.

In an apparatus for oxidizing gases containing flammable and / or explosive components, the apparatus 25 comprises a catalyst-containing reactor, the reactor is provided with a gas supply line and an exhaust line and a controllable heating device, the device having a closed reactor containing a granular catalyst. mio, a heating device placed in the heating chamber, also for heating. the heating chamber contains the catalyst and the heating chamber and the reactor contain temperature sensors which are connected to the controlled heating device via a control unit.

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 a control cabinet with a closed structure and is equipped with a device for guaranteeing the overpressure of the control cable and a pressure sensor.

In another preferred embodiment of the device according to the invention, it comprises a heat exchanger, one side of which is connected in front of the reactor and the other side downstream of the reactor. It is advantageous if the reactor, the heating chamber and possibly also the heat exchanger are assembled in the same unit.

Finally, it is advantageous to provide two heating chambers connected in parallel.

The invention will be explained in detail below by means of exemplary embodiments and a drawing. Figure 1 shown in the drawing is a schematic diagram of a device 15 according to the invention.

The device shown has a closed actuator 4 provided with a gas supply line 41 and a degassing line 42. A granular catalyst is arranged in the reactor 4. The gas outlet line 42 of the reactor 4 is connected to the gas-20 tightly in the pipes of the heat exchanger 2, through which the oxidized gas leaves the chimney 21.

The jacket-side inlet of the heat exchanger 2 is connected to a fan 1, into which the gas to be oxidized (e.g. methane-air mixture) enters the flame arrestor 8 (e.g. solenoid-25 valve with a quick shut-off). The outlet on the jacket side is gas-tightly connected to the gas supply line 41 of the reactor 4 via two parallel heating chambers 3.

The heating chambers 3 are also filled with a granular catalyst material (which, however, may not be of the same type as the catalyst material used in the reactor 4). Connected to the heating chambers 3 are pressurized electric control cabinets 5. Connected to the control cabinets 5 are controlled heating devices 31 of the heating chambers 3, which are arranged to extend into the granular catalyst bed.

The control cabinets 5 are connected on the one hand to a device for producing compressed air or neutral gas (not shown) by means of a pressure control filter 7, and on the other hand to an outlet line 6 with a solenoid valve 61.

The reactor 4 and the west chambers are suitably assembled in the same unit to reduce heat loss.

The device has a control panel 10 and a control unit 20, which are connected to each other and to temperature sensors 43, 44 and 10 32 connected to the reactor 4 and heating chambers 3 (e.g. thermal switches) and pressure sensors 51 (e.g. pressure switches) connected to control cabinets 5.

The device according to the invention is implemented with the device shown in the following manner.

The gas to be cleaned (oxidized) is sucked in by a fan 1 through a flame arrestor 8 and forced from the jacket side of the heat exchanger 2 into parallel heating chambers 3.

Here, the gas preheated by the heat exchanger 2 is heated by electric heating devices 31 (immersed in 20 granular catalysts) to a temperature necessary for catalytic oxidation (80 to 550 °, preferably 180 to 330 °). From the heating chambers 3, the gas enters the reactor 4, where the catalytic oxidation is then completed. The flow of oxidized (purified) gas exits 25 through the pipes of the heat exchanger 2 to the chimney 21, whereby the flow of the gas to be purified is preheated upstream.

The feed rate is then chosen to be higher than the combustion rate, preferably two to five times the combustion rate of the most dangerous (methane) gases (which have the highest combustion rate).

. The control cabinets 5 must be kept under overpressure so that no air can enter it from the outer fire and explosion hazard area. Before use, they are flushed with compressed air or neutral gas. The devices 35 51 check that a certain overpressure (e.g. 100 Pa) exists 5 95875. If the internal pressure of the control cabinet 5 drops below a predetermined value (e.g. 50 Pa) during operation, the heating devices 31 are immediately switched off by means of the device 51.

5 It is only possible to switch on the main switch after the control cabinets 5 have been flushed and a corresponding overpressure has developed. Only then can fan 1 be started and then electric heating. If fan 1 stops, the electric heating is automatically switched off 10.

If the catalyst bed temperature exceeds the allowable value, then devices 43, 44, and 32 signal a malfunction to control panel 10 and unit 20 and turn off the heating and, as needed, the entire plant.

15 It is also appropriate to monitor the proper condition of the electric heating devices 31 by means of corresponding means. Individual faults, malfunctions are indicated on the control panel 10 by acoustic and light signals. The rise in temperature can be due to three reasons.

20 a) fan 1 stops b) control circuit failure c) increase in the concentration of pollutant components The main heating switch is switched off in all three cases.

25 Since the flow resistance of the apparatus and the catalyst bed therein is low (2000 - 3000 Pa), the chimney can be given the character of a fracture plate. In the event of an exhaust, it does not indicate any source of danger.

With the process and device 30 according to the invention, it is possible (by a choice of catalyst bed in a manner known per se) to oxidize or purify a wide variety of gases, e.g. aromatic, normal, cyclo- and hydrocarbons, permanent sulfur and nitrogen-containing, hydrocarbon derivatives, carbon monoxide, air streams containing hydrogen sulphide, mercaptan 35 and ammonia impurities.

t · «6 95875 α Devices (eg fans) and accessories (eg pressure switches, solenoid valves) arranged in an explosive atmosphere must, of course, be made explosion-proof.

5 The chimney 21 and the pipelines shall be suitably equipped with vibration dampers (flexible pipe sections) (not shown). The heating chambers 3, the reactor 4 and the heat exchanger 2 are expediently assembled by welded joints in accordance with the prior art 10 into one block and arranged in a corresponding rack.

The oxidation of the impurity components in the gas stream to be cleaned takes place on the surface of the catalyst at a temperature raised to the ignition temperature, without the presence of flames, because the free travel in the granular catalyst surrounding the device is shorter than the critical value.

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Claims (6)

A process for the oxidation of gases containing flammable and / or explosive components, wherein the gas is fed to a reactor containing a catalyst and thus brought to a temperature required for catalytic oxidation, characterized in that a closed reactor is used. , the gas pours in the denser area at a temperature, is required for catalytic oxidation, and prevents the gas from reaching ignition temperature. 2. An apparatus for oxidizing gases containing flammable and / or explosive components comprising a reactor containing a catalyst, the reactor being provided with an inlet pipe and an outlet pipe for the gas and with a controllable heating device, characterized in that: the apparatus comprises a closed reactor (4) containing a granular catalyst and prior to which a closed heating chamber (3) is provided, and that the heating chamber (3) and the reactor (4) contain temperature detectors (32, 43, 44). ), which are connected to a controllable heating device (31) via a control unit (20). Device according to claim 2, characterized in that the heating chamber (3) is provided with an electric heating device (31) which is connected to a closed control cabinet (5) and that the control cabinet (5) is provided with an overpressure guaranteeing device. and a pressure detector (51). 4. Apparatus according to claim 2 or 3, characterized in that it comprises a heat exchanger. (2), where one section (side) is connected before reactor (4) and the other after reactor (4). Device according to any of claims 2-4, characterized in that the reactor (4), the heating chamber (3) and possibly also the heat exchanger (2) are assembled into a unit. I · 4 9 95875 Device according to any of claims 2-5, characterized in that it has two heating chambers (3) which are connected in parallel. 1 · • ·