PL154894B1 - Catalytical burner - Google Patents

Abstract

System for the combustion of organic gases mixed with air feeds the mixture through a reversion valve to a reactor which contains two layers of ceramic packing and two layers of catalyst. These catalytic layers are separated from one another, and part of the gas passing to the space between them is fed thorugh a third catalytic layer and removed from the reactor. Catalyst temperature is controlled by electric heaters, and if these cannot maintain the appropriate oxidation reaction temperature, the rate of removal gas is decreased.

Description

REPUBLIC POLAND PATENT DESCRIPTION 154 894 Additional patent to patent No.-- Int. Cl. ⁵ _BO id 53/36 Reported: 88 03 24 (P. 271406) Priority- GZYTELHIA GENERAL OFFICE PATENT Application announced: 89 and 02 RP Patent description opubłikooano: 1992 02 28

Creators of the invention: Jerzy Wojciechowski, Janusz Janas, Zygmunt Wysocki, Andrzej Rachwal

Authorized by the patent: Polish Academy of Sciences Institute of Catalysis of Surface Physicochemistry, Krakow (Poland)

CATALYTIC BURNER

The subject of the invention is a catalytic burner, i.e. a device for combustion of relatively high concentrations of organic compounds contained in the air.

Catalytic reactors are known which are used in catalytic gas purification processes. The new generation of this type of devices is based on the use of the catalytic gas purification method, described in Polish patent specification No. 126861. According to the above-mentioned method, the catalytic gas purification process is carried out using the reverse method, the oxidation catalyst is placed between two layers of heat-accumulating filling, while the heat needed for heating catalyst and, optionally, to sustain the afterburning process, is fed to the center of the catalyst bed.

The device according to Polish patent description No. 129862 consists of two identical cylindrical reactors, each of which has two chambers: - the so-called catalytic chamber in which there are two, concentric, cylindrical perforated grids, closed at the bottom with a bottom, forming a basket housing the catalyst bed and the lower - called a recuperation chamber - inside which there is a layer of ceramic filling.

From the bottom side, both reactors are connected by a collector supplying contaminated gas in a cyclical reverse way, one to one and then to the other reactor. At the same time, the purified air is discharged from the opposite reactor. The gas flow is changed by means of timed valves.

The reactors are connected at the top by a common manifold having a stub pipe, through which hot exhaust gases necessary to heat the catalyst to the temperature of the combustion reaction initiation are supplied. Alternatively, instead of hot exhaust gas, electric heating elements may be used to heat the catalyst layer, introduced into the central, empty part of the catalytic basket, called the heating chamber.

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According to Polish patent specification No. 129863, the catalytic gas purification process is carried out in a reversible reactor with the shape of a cylindrical body, inside which three perforated cylinders of different diameters are centrally mounted.

In the space formed by the two outer cylinders there is a bed of a suitable catalyst. A ring of perforated steel sheet, fixed horizontally in the center of the perforated cylinders, divides the reactor transversely into two chambers, the partition not close to the inner perforated ring. The space delimited by an inner cylinder is a heating chamber inside which electric heaters are placed.

Contaminated gases are directed by means of controllable reversing valves - either to the upper part of the device, then passing through the upper chamber with ceramic filling, upper catalytic chamber, heating chamber, lower catalytic chamber, lower chamber with ceramic filling and leaving the reactor in its lower part - or to the bottom of the device by passing through its individual elements in the opposite direction than before.

Another, simpler design is described in the Polish patent description No. 143752. The device for the catalytic purification of exhaust gases is in this case made in the form of one compact reactor with a cylindrical casing - which, however, fulfills the role of two reactors.

The interior of the apparatus is divided from the bottom by a vertical partition, tightly adjacent to the inner walls of the reactor, but not reaching the top cover of the reactor, into two identical spaces, connected in the upper part by a common heating chamber.

A series of symmetrical, horizontally arranged perforated sheets divide the two spaces into individual chambers. There is a layer of ceramic filling between the two lower perforated partitions; Above it - limited at the top by another perforated plate, there is a catalyst layer.

The upper part of the cylinder is closed with a cover in which there is a stub pipe for extracting hot gases. In the lower part of the reactor, below the level of the lowest perforated partition, there are inlet-outlet connectors - one on each side of the vertical partition - used to supply contaminated gases forced by the fan through the valve. The gases enter the lower part of the relevant half of the reactor through one of the nozzles, pass through the lower perforated partition, the layer of ceramic filling, the central perforated partition, the catalyst layer, the upper perforated partition, the heating chamber and penetrate from the top to the other, symmetrical half of the reactor, passing the individual layers in the opposite direction and cleaned - they leave the reactor through the second nozzle.

After a certain period of time, the length of which depends, inter alia, on the concentration of pollutants, the reversing valve changes the direction of the air flowing through the reactor.

This way of carrying out the process for cleaning the waste gases from combustible impurities, characteristic of reversible methods, is energy-saving and enables effective after-burning of impurities within a wide range of concentrations, typically 0.1 - 3 g of impurities in one m ^{3 of} air.

In the range of low concentrations of pollutants, the reactor temperature can be kept constant, and the periodic temperature increase - caused by a sudden, short-term increase in the concentration of combustible components - can be easily regulated (e.g. by using a hot gas vent, as in Polish patent No. 137515). When the concentration of organic compounds in gases from^labout^volthose transgressions^y j^ednak significantly limit value^andc^, out^gay^andc n^p. values of l^{0 g}/ m^3, in these Reverse catalytic converters are unstable and very difficult to regulate. There is a risk of overheating, which may deactivate the catalyst or even destroy the internal components of the reactor.

Energy needs often require the combustion of gaseous or liquid hydrocarbons in an air stream, albeit at lower temperatures than in flame burners, to avoid the formation of nitrogen oxides and reduce heat losses.

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In such cases, however, it is not possible to use classic reversible reactors for the reasons given above.

The design of the reversible catalytic converter according to the present invention enables the stable combustion of organic compounds in the air at high or even very high concentration of these compounds. The catalytic burner according to the invention has the shape of a metal cylinder, divided by an internal partition into two catalytic-regenerative chambers acting as heat regenerators.

H each catalytic-regeneration chamber, viewed from the bottom, includes the following components: a load-bearing perforated barrier, a layer of ceramic filling, a perforated barrier, a layer of a catalyst used in catalytic gas purification processes, and possibly a perforated barrier.

In the upper part of the reactor, on its cover, there is a cylinder inside which a catalyst bed used in KOG (catalytic gas purification) processes is placed.

The air, together with organic compounds, is fed cyclically to one of the catalytic-regenerative chambers, and then partially circulates through the second catalytic-regenerative chamber, and partially flows out through the upper catalyst bed. After changing the direction of flow, forced by the reversing valve, the polluted air is fed to the second chamber and passes through the reactor in the opposite direction as before, partially circulating in the reactor system and partially flowing out through the outlet of the cylinder installed in the upper part of the reactor.

Internal circulation of part of the gases through both chambers - with the cyclically changing direction of the flow of these gases - allows the utilization of part of the heat generated in the process of burning pollutants. Heaters mounted in the upper part of the cover are used to heat the catalyst bed at the start of the installation, and to maintain the set temperature in the catalyst layers.

The device according to the invention is shown in an exemplary embodiment in the attached drawing. It consists of a metal cylinder 1, divided inside by a vertical partition 2 into two symmetrical parts. The baffle defines two identical catalytic-regenerative chambers, and in which there are layers of ceramic filler 5, 6 in the shape of balls, rings, & ^ra or other text, and the catalyst used in the process of combustion gases 7 and 8.

In the lower part of the chambers 3 and 4 there are stubs 20, 21 connecting the individual chambers with the reversing valve 9, which directs the gas stream pumped by the fan 10 cyclically to the catalytic-regeneration chamber 3 or 4.

On the reactor cover 11 there are electric heaters 13 and a cylinder 12 with a diameter smaller than the diameter of cylinder 1. Inside the smaller cylinder 12 there is a bed of catalyst 14 used in gas purification processes, placed on a perforated plate.

Valve 15 regulates the flow of air supplied from the outside, valve 16 regulates the flow of circulating gases through the catalytic-regeneration chambers, and valves 17 and 18 regulate the flow rate of the gas stream through the catalyst bed 14. Port 19 allows for the conduct of an air stream with a very high concentration of combustible compounds or even clean fuel for the catalyst bed 14, if its temperature is sufficient for the catalytic combustion process to take place.

Example. The catalytic burner according to the invention has been tested in practice for the combustion of organic solvent vapors contained in the air. The intensity of the air flow amount to ^two 00 m ³ / h.

The concentration of organic solvents, mainly methanol and acetone, ranged from ^{5 to 25} g ^{/ m3} . ^In government ZENI umożhwrto ^d s ^p a! Ting s organic vapors of ^p rawności.ą ^EJ above 99%. No nitrogen oxides were found in the combustion products.

The catalytic burner according to the invention enables the oxidation of chemical compounds in the air at their relatively high concentration, from a few to several dozen^się^hush thundersⁿand¹ m³ air.^P.roces spatanró starting in the burner wedtag wynai.azku ma cha stable, without sudden overheating or sudden drops in reaction speed.

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The catalytic burner can be used to purify exhaust gases with a high concentration of impurities subject to catalytic conversion. It can also be used to burn various organic compounds, intentionally dosed into the air stream fed to the device, acting then as a catalytic burner producing hot exhaust gases.

Claims (1)

Patent claim Catalytic burner for catalytic combustion of organic compounds with a relatively high concentration in the air stream, characterized in that it consists of a metal cylinder (1) divided in half by a vertical metal wall (2) dividing the cylinder interior into two identical catalytic-regenerative chambers (3) and (4), which have layers of ceramic filling (5) and (6) and two layers of catalyst (7) and (8) used in catalytic gas purification processes, preferably of spherical shape, the chambers (3) and ( 4) in the lower parts, they connect with stubs (20) and (21) with the reversing valve (9) and then with the fan (10) forcing air with organic compounds into the reactor, while in the upper part of the cylinder (1) on its cover (11) ) there are heaters (13) and a cylinder (12), in which cylinder there is a layer of catalyst used in catalytic gas purification processes (14), with the upper part of the cylinder (12) gas outlet together with the valve (17) cooperating with the next valve (18) and regulating the amount of gases flowing through the catalyst bed (14) to the outside, while the valve (15) regulates the amount of air flowing into the reactor, and the valve (16) regulates the amount of gases circulating through the catalytic-regeneration chambers (3) and (4, and the additional inlet (19) allows the introduction of additional air with a high concentration of combustible components or combustible gas or vapors of organic compounds into the stream of gases flowing through the catalyst layer (14). 154 894 154 894 Department of Publishing of the UP RP. Circulation 100 copies. Price PLN 3,000