AT506459A2 - DEVICE AND METHOD FOR CLEANING CONTAMINATED EMISSION - Google Patents

Description

Apparatus and method for the purification of pollutant-containing exhaust gas

The invention relates to a device for cleaning polluted exhaust gas. It also has a method for exhaust gas purification with such a device to the object.

Such plants, with which in particular exhaust air is purified, which contain organic compounds such as solvents, are known (see EP 0472 605 B 1). The regenerators consist of vertical towers, wherein in the combustion chamber connecting the upper ends of the two Regeneratortürme, the organic compounds are burned in the raw gas to form the clean gas flowing through, for example, the first regenerator to heat it. When the raw gas is supplied to the first regenerator, it is preheated by its heated heat storage cup, the organic compound in the preheated raw gas is burned in the combustion chamber, and the heat storage mass of the second regenerator is heated by the hot clean gas. Then there is a change of the raw gas supply to the second regenerator, while the clean gas is withdrawn from the first regenerator, etc.

In the known device extending under the juxtaposed vertical Regeneratortürmen for supplying the raw gas or to remove the clean gas two tubes with a high throughput of such a cleaning device corresponding large diameter, which are connected via nozzles to an antechamber below the regenerators. At the openings of the two nozzles in the antechamber Absperxorgane are provided, each of which can be actuated by an actuator, which are formed by arranged below the tubes piston / cylinder units.

For alternate supply of the raw gas to the two regenerators four actuators with four shut-off valves are required in the known device. By arranged under each regenerator antechamber, which must have a sufficient height to ensure the function of the shut-off, as well as arranged under the tubes actuators, the known device has a considerable height and a corresponding weight. Also, a shaft or the like must be provided under each actuator to remove the same and its internals. Furthermore, the prechambers for actuating the shut-off devices under the towers form a dead volume which reduces the cleaning effect. An embodiment which has a minimized dead volume is described in DE 196 43 821 CI.

The object of the invention is to improve the cleaning performance of such a regenerative thermal post-combustion device while reducing the dimensions, the weight and the cost.

This is inventively achieved by the characterized in claim 1 device. In the subclaims 2-18 advantageous embodiments of the device according to the invention are shown. The claim 19 has an advantageous method for purifying exhaust gases with the inventive device for

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An article which is further configured by the measures of claims 20 to 22 in an advantageous manner.

According to the invention, at least two regenerators are normally provided, however, for example, a third regenerator may be present, the z. B. is purged with clean gas, while the two other regenerators alternately the raw gas is supplied.

In the apparatus according to the invention, the shut-off elements for the alternate connection of the lines connected to the regenerators with the RohgasZufuhrleitung and the clean gas discharge line are combined to form a single four-way valve with a rotatable cylindrical valve body.

The valve body is preferably formed by a partition which extends radially, ie diagonally across the cylindrical interior of the valve housing. In the circumferential direction of the valve housing, the raw gas supply line, the line to the one regenerator, the clean gas discharge line and the line to the other regenerator are preferably connected in succession. These four ports are each offset by approximately 90 ° in the circumferential direction on the peripheral wall of the valve housing.

Thus, a chamber is formed on each side of the partition wall in the valve housing, via a chamber, the raw gas flows from the raw gas supply line into the line to the one regenerator and the other chamber, the clean gas from the line from the other regenerator to the clean gas discharge line. • · · · 4 · · ·

Thus, the diversion of the gas flow in each chamber from one to the other connection as possible without pressure loss occurs, so turbulence is counteracted, the partition is concave on both radially extending, so the chambers facing sides. At the same time, the concave design counteracts a flow short circuit, i. H. an entry of raw gas from the raw gas supply line into the clean gas in the clean gas discharge line and vice versa in the valve housing.

The partition is preferably formed as a hollow body, d. H. it consists z. B. of two concave sheet metal walls, which are facing one and the other chamber and in each case a metal wall on both sides on the circumference, which connect the concave metal walls.

Due to the hollow design, the weight of the partition is reduced, whereby the Ümschaltzeit the four-way valve can be reduced, so the time in which the partition can be moved from one to the other end position.

A further significant reduction in the switching time of the four-way valve can be achieved in that the valve body is driven by a pneumatic rotary drive, wherein the drive axis of the rotary drive is preferably connected axially to the axis of rotation of the valve body.

By means of the pneumatic rotary drive, the switching time for actuating the four-way valve can be reduced to less than one second, preferably 0.1 to 0.5 seconds, which largely prevents short-circuit losses, ie the entry of raw gas into the clean gas discharge line. · · ---- · · · · · · · · · · · · · · ·

become. It should be noted that the switching time of the valve for alternately supplying the raw gas to the one or the other regenerator, ie the time in which the four-way valve remains in one or the other end position, usually more than a minute, in particular is about two to five minutes.

Preferably, a seal is provided between the peripheral walls of the partition and the inside of the bulkhead of the valve housing to seal the valve body circumferentially with respect to the valve housing. The seal may for example be formed by a over the entire width of the partition extending sealing strip, which cooperates with a sealing body of the same length on the inside of the valve housing, for example, that the sealing body serves as a stop for the sealing strip.

The sealing body may, for. B. made of silicone, viton or graphitized ceramic fiber. The sealing strip preferably has a spring plate so that it does not damage the sealing body when it stops.

For the same reason, the pneumatic rotary actuator, which operates the four-way valve, is equipped with a cushioning system.

To seal the valve body or the partition wall in the axial direction, a coaxial disc is provided on each side of the valve body or the partition wall, which is spaced from the peripheral wall of the valve housing with a sealing gap in the tolerance range, ie, for example, half a millimeter or less. 6 ··· 6 ···

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In this case, a sealing lip extending over the circumference of the valve housing may be provided on the valve housing and / or the disk in order to further seal this gap.

Furthermore, a connection can be provided on at least one outer wall of the valve housing in order to supply sealing air to the gap between the disk on the valve body or the partition wall and the adjacent outer wall of the valve housing. Thereby, a gas outlet from the raw gas region of the valve body is prevented by the gap between the disc and the peripheral wall of the valve housing in the adjacent clean gas area.

The sealing air has to a pressure which is greater than the pressure of the raw gas supplied via the raw gas supply line to the valve. With the sealing air so also the entry of raw gas is prevented in the clean gas discharge line.

Also, in order to pressurize the gap between the disc on the partition wall and the outer wall on the other side of the valve housing with sealing air, preferably in the partition wall and each disc, a passage for the sealing air from the gap provided with the sealing air port to the gap between the opposite disc of the partition and the valve housing outer wall provided.

The temperature in the combustion chamber and thus the temperature of the heat storage mass adjacent the combustion chamber of the regenerator is preferably at most 1000, preferably at most 900 "Celsius. At a high

Concentration of pollutants in the raw gas, however, there is a risk that this temperature exceeded and thus 7 • t ♦ · · · · ♦ · «• ♦ · · · · ♦« f · · ·

For example, the insulation or the heat storage mass is damaged.

To prevent this, a bypass line is preferably provided, which is preferably connected to the raw gas supply line between a fan and the four-way valve and opens directly into the combustion chamber, so that cold raw gas can be supplied to it. D, h. in excess of energy in the combustion chamber, raw gas is fed from the main blower via the bypass line into the combustion chamber for cooling the same, in order to prevent the predetermined combustion chamber temperature is exceeded.

The control for reducing the supply of crude gas via the bypass line to the combustion chamber when the predetermined combustion chamber temperature is exceeded, however, is preferably carried out delayed. Ie. the excess energy is not discharged directly into the clean gas, but stored by the delayed control of the control valve, which is provided in the bypass line, in the heat storage mass of the regenerator. As a result, the energy efficiency of the system is increased with changing concentration of pollutants.

In the combustion chamber mixing means are preferably provided to generate a turbulent flow. These mixing devices are used in particular for mixing the raw gas entering from the bypass line into the combustion chamber with the hot combustion gas.

The heat storage mass of the regenerators is arranged substantially horizontally, preferably in such a way that it is at an angle 8 ······· · of less than 30 °, preferably 1 to 10 °, in particular 2 to 6 °, relative to the horizontal rises from the combustion chamber facing away from the end of the combustion chamber towards. This will ensure that the heat storage bodies that make up the heat storage pool will stay together.

The heat storage medium preferably consists of extruded, ceramic heat storage bodies with a prismatic cross section and channels extending parallel to the prism longitudinal axis. These heat storage bodies are described in EP 472 605 Bl in detail. They have a high thermal stability and can be made for example of porous cordierite.

Preferably, an electric heater is provided for the primary heating of the combustion chamber, which is provided in the bottom and / or the side walls in the combustion chamber. With this electric heater, the combustion chamber is heated to its operating temperature of, for example, at least 750 "C before raw gas is supplied to the combustion chamber.

In contrast to the prior art, this reduces the energy loss that is required to heat the combustion chamber to the operating temperature so that the exhaust gas purification can be carried out.

Namely, according to the prior art, a gaseous or liquid fuel is used, which, mixed with combustion air, is blown into the combustion chamber with a blower. Thus, the combustion air must be additionally heated, which causes a significant energy loss of about 30%. 9 9 • • • • • • • • •

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The fuel used for direct injection into the combustion chamber may be, for example, a gaseous fuel such as natural gas or propane or a liquid fuel such as fuel oil or a liquid biofuel.

Preferably, a device for direct fuel injection into the combustion chamber is provided for secondary heating. D. h., If the combustion chamber has been brought to the required operating temperature with the electric heater, if the pollutant concentration in the raw gas is too low, the operating temperature can be maintained by directly fuel, ie injected without combustion air into the combustion chamber, which is burned with the air contained in the raw gas.

Due to the substantially horizontal arrangement of the heat storage mass of the regenerators, the device according to the invention has a relatively small height. It can thus be arranged in an example box-shaped support frame, which is preferably provided with an outer lining. In this case, the four-way valve is disposed in the one end face of the box facing end portion, and the 3rennraum in the other end face facing end portion. The entire device can thus be designed, for example, as a container transportable.

Below, this invention is explained in more detail by way of example with reference to the accompanying drawings. In each case schematically show:

Figure 1 is a perspective view of the device with transparent dargstelltem housing for the regenerators and the combustion chamber;

Figure 2 is a radial section through the four-way valve;

Figure 3 is an axial section through part of the lateral seal on one side of the four-way valve of Figure 2; and

Figure 4, arranged in a box-shaped support frame device in perspective representation in longitudinal section.

According to FIG. 1, the device has a housing 1 in which two regenerators 4, 5 formed from heat storage masses 2, 3 and a combustion space 6 are arranged, which connects the regenerators 4, 5 at one end to one another.

The pollutant-containing exhaust gas or crude gas to be purified is supplied via the raw gas supply line 7, which is provided with a blower 8. The purified waste gas or clean gas is discharged into the open air via the clean gas discharge line 9 designed as a chimney.

For alternately supplying the raw gas to the one regenerator 4 or 5 and for removing the clean gas from the other regenerator 5 and 4, a four-way valve 10 is provided, to which the RohgasZufuhrleitung 7 and its intermediate piece 7 'on the fan connected. For this purpose, the four-way valve 10 is connected to the end of the regenerators 4, 5 facing away from the combustion chamber 6 via the line 11 or 12 with the one or other regenerator 4 or 5. 11 11 ·· ·· ·· · · · · · · · · · · ·

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In the bottom of the combustion chamber 6, an electric heater 13 is provided with the combustion chamber 6z. B. can be heated to 800 ° C.

When the raw gas is supplied from the raw gas supply line 7, 7 'with the four-way valve 10 via the line 11 to the regenerator 4, the organic or other combustible pollutants are burned in the raw gas in the combustion chamber 6, whereby the heat storage mass 3 in the other regenerator 5 is heated by the hot clean gas, which is supplied via the line 12 and the four-way valve 10 of the clean gas discharge line 9. After a switching time of, for example, three minutes, the four-way valve 10 is switched so that the raw gas is supplied via the line 12 of the heated heat storage mass 3 of the regenerator 5 and the clean gas via the line 11 via the four-way valve 10 of Clean gas discharge line 9, etc. Thus, with the four-way valve 10, the raw gas supply line 7, 7 'and the clean gas discharge line 9 can be alternately connected to one or the other line 11 or 12 and thus to the one or the other regenerator 4, 5.

The four-way valve 10 has a rotatable cylindrical valve body 14, which is formed according to Figure 2 by a rotatable about the axis 15 partition 16 which extends radially through the interior of the valve housing 17.

To the valve housing 17 are circumferentially circumferentially successively offset by an angle of about 90 ° at the connection 22, the crude gas supply line 7, 7 ', at the terminal 23, the line 11 to the one regenerator 4, at the connection 24, the clean gas discharge line 9 and the connection 25, the line 12 is connected to the other regenerator 5. 12 · • · · · · · · · · · · · · · · · · ·

By the partition 16, the interior of the valve housing 17 is separated into the two chambers 18, 19, wherein in the end position shown in Figure 2 of the valve body 14 via the one chamber 18, the raw gas from the raw gas port 22 via the port 23 into the conduit 11 the one regenerator 4 flows and via the other chamber 19, the clean gas from the line 12 (terminal 25) from the other regenerator 5 to the clean gas discharge line 9 (port 24).

In the other end position, the valve body 14 is rotated counterclockwise by 90 ° so that the raw gas (port 22) flows into the line 12 (port 25) and the raw gas from the line 11 (port 23) to port 24.

Thus, the diversion of the gas flow in each chamber 18, 19 takes place from one to the other port 22 and 23 or 25 and 24 as possible without pressure losses, the partition wall 16 at both radially extending, so the chambers 18, 19 facing sides are concave.

The partition 16 is formed as a hollow body, d. H. it consists of two concave sheet-metal walls 28, 29 and in each case a connecting portion 26, 27 on the circumference, which connect the metal walls 28, 29 with each other.

The actuator for the four-way valve 10 is formed by a connected to the rotation axis 15 of the partition 16 pneumatic rotary actuator 31 which is flanged to the valve housing 17 according to FIG. • · • · 13

At the connecting portion 26, 27 of the partition 16 each have a sealing strip 32, 33 is provided, which cooperates with arranged on the inside of the peripheral wall 30 of the valve housing 17 sealing body 34 to 37, to which the sealing strip 32, 33 abuts (Figure 2). The sealing strips 32, 33 are designed as a spring clip. The sealing bodies 34 to 37 are each provided between two adjacent terminals 22 to 25.

To seal the partition wall 16 in the axial direction is on both sides of the partition wall 16 a coaxial with the axis of rotation 15 disc 38, 38 'is provided, in Figure 2, the disc 38 can be seen, the z. B. is flanged with screws 39 to the partition wall 16, and in Figure 3, the disc 38 '.

As can be seen in FIG. 3, a blocking air connection 42 is provided on the outer wall 41 of the valve housing 17 adjacent to the disk 38 'in order to blow sealing air into the gap 40 between the disk 38' and the outer wall 41. This prevents that raw gas can pass through the gap 43 from the valve body 14 into the gap 43 and from there into the clean gas. The gap 43 is additionally sealed by a ring seal 4 4 on the inside of ümfangswand the valve housing 17.

Instead of the sealing air, it is also possible to provide an extraction for the gap 43 in order to prevent the raw gas from passing through the gap 43 into the clean gas. In this case, the extracted sealing air is supplied to the raw gas before the fan 8.

In order that the sealing air can also be blown into the gap between the opposing disk 38 of the partition wall 16 and the opposite valve housing outer wall or the air can be sucked into this gap, passages 45 are provided between the sheet metal walls 28 in the two disks 38, 38 ' and 29 are provided.

The heat storage masses 2, 3 of the regenerators 4, 5 are arranged according to FIGS. 1 and 4 on a carrier 46.

In this case, a bypass line 47 is connected to the intermediate piece 7 'of the crude gas supply line 7 between the blower 8 and the four-way valve 10, which extends below the support 46 to the combustion chamber 6.

The bypass line 47 opens into distributed in the combustion chamber 6 arranged vertical bars 48 which are provided with outlet openings 49 for the raw gas, which are distributed over the length of the spars 48.

At the spars 48 wings 50 are preferably attached, for example made of temperature-resistant steel preferably dependent, forming the mixing devices 51 to increase the turbulence in the combustion chamber 6 for better combustion.

If the raw gas has a high concentration of combustible pollutants, cold gas can be supplied directly to the combustion chamber 6 with the bypass line 47. With the cold, supplied via the bypass line 47 raw gas can thereby be prevented exceeding the predetermined temperature of the combustion chamber, for example, 900 ° C.

On the other hand, for example, nozzles 52 for direct injection of a gaseous or liquid fuel are provided in the end wall of the combustion chamber 6, in order to achieve the required 9 × 15 for operation in the device

Not to fall below the combustion chamber temperature, if the concentration of combustible pollutants in the raw gas is too low.

The heat storage mass 2,3 of the regenerators 4/5 consists of extruded ceramic parallelepipedic, block or block-shaped heat storage bodies 53 which have parallel to the longitudinal axis extending channels with a hydraulic diameter of 2 to 12 mm. Such heat storage body with rectangular, so generally prismatic cross section and parallel to the prism longitudinal axis extending channels are described in EP 472 605 B 1 in more detail.

The carrier 46 is formed so that the heat storage mass 2,3 of the generators 4,5 formed from the storage bodies 53 with respect to the horizontal at an angle α of, for example, 5 ° from the mouth of the lines 11,12 in the regenerators 4,5 to the Combustion chamber 6 increases towards. This ensures that the heat storage body 53 remain permanently with their front sides together.

According to Figure 4, the entire device is arranged in a support frame 54 which is provided with an outer lining, not shown. The four-way valve 10 are arranged with the main blower 8 in the one end portion 55 in the support frame 54, the regenerators 4,5 and the combustion chamber 6 in the middle portion 56, while the other end portion 57 as z. B. accessible via a door control room with control cabinet, in which, inter alia, the means for injecting the fuel through the nozzles 52 may be provided. The entire device 16 can thus be designed as a portable container.

Claims (21)

1. A device for purifying polluted exhaust gas by regenerative thermal afterburning with at least two heat storage masses (2, 3) containing, via a combustion chamber (6) interconnected regenerators (4, 5), a Rohgaszufuhrleitung (7 , 7 ') and a clean gas discharge line (9) and actuated by actuators shut-off devices, with which the raw gas supply line (7, 7'). and the clean gas discharge line (9) can be connected alternately to a line (11, 12) which is connected to the one or the other regenerator (4, 5) on the side opposite the combustion chamber (6), characterized in that the shut-off elements for alternating connection of the lines (11, 12) connected to the regenerators (4, 5) with the raw gas supply line (7, 7 ') and the clean gas discharge line (9) in a single four-way valve (10) with a rotatable cylindrical valve body ( 14) are summarized. 2. Apparatus according to claim 1, characterized in that the actuator for the four-way valve (10) by an on the valve body (14) axially mounted pneumatic rotary drive (31) is formed with cushioning. 3. Device according to claim 1 or 2, characterized in that the valve body (14) is designed as a hollow body. • · • · 18 4. Device according to one of the preceding claims, characterized in that the valve body (14) by a partition wall (16) is formed, which extends radially through the cylindrical interior of the valve housing (17). 5. Device according to one of the preceding claims, characterized in that in the Omfangsrichtung of the valve housing (17) successively the crude gas supply line (7, 7 '), the line (11) to the one regenerator (4), the clean gas discharge line (9) and the Line (12) to the other regenerator (5) are connected. 6. The device according to claim 5, characterized in that the connections (22 to 25) for the raw gas supply line (7, 7 '), the line (11) to the one regenerator (4), the clean gas discharge line (9) and the line ( 12) are arranged offset to the other regenerator (5) in the circumferential direction by 90 °. 7. The device according to claim 4, characterized in that the dividing wall (16) is concave on both sides to minimize the pressure loss and to limit the flow short circuit. 8. Apparatus according to claim 4 or 7, characterized in that for sealing the partition wall (16) in the axial direction on both sides of the partition (16) a disc (38, 38 ') and on the outer wall (41) of the valve housing (17 ) a sealing air connection (42) for supplying blocking air into the gap (40) between the outer wall (41) and the adjacent disc (38 ') or a suction for sucking the air from the gap (40) is provided. 9. Apparatus according to claim 8, characterized in that a passage (45) through the partition wall (16) of the one gap (40) between the disc (38 ') and the valve housing outer wall (41) on one side to the gap between the disc and the valve housing outer wall on the other side of the valve housing (17) is provided. 10. The device according to claim 2, characterized in that the partition wall (16) on the circumference with a sealing bodies (34 to 37) on the inside of the peripheral wall (30) of the valve housing (17) cooperating sealing strip (32,33) is provided. 11. The device according to claim 1, characterized in that to the crude gas supply line (7, 7 ') into the combustion chamber (6) opening bypass line (47) is connected. 12. The device according to claim 1, characterized in that in the combustion chamber, a mixing device (51) is arranged to increase the turbulence. 13. The apparatus of claim 11 and 12, characterized in that the mixing device (51) in the combustion chamber (6) for mixing the from the bypass line (47) into the combustion chamber (6) entering the raw gas are provided. 14. The device according to claim 1, characterized in that the heat storage mass (2, 3) of the regenerators (4,5) is arranged so that they relative to the horizontal at an angle (a) of less than 30 °, preferably at most 10 ° to the combustion chamber (6) increases. 15. The apparatus of claim 1 or 13, characterized in that the heat storage mass (2, 3) of extruded ceramic heat storage bodies (53) is formed with prismatic cross section and parallel to the prism longitudinal axis extending channels. Eat. Apparatus according to claim 1, characterized in that for the primary heating of the combustion chamber (6) an electric heater (13) in the combustion chamber (6) is provided. 17. The device according to claim 1, characterized in that for secondary heating of the combustion chamber (6) a device for direct fuel injection into the combustion chamber (6) is provided. 18. Device according to one of the preceding claims, characterized in that it is arranged in a support frame (54). 19. A method for purifying exhaust gases with a device according to one of the preceding claims, characterized in that when a predetermined combustion chamber temperature is exceeded, the combustion chamber (6) is supplied directly raw gas. 21 • · • · • · · · · · · · · · 20. The method according to claim 19, characterized in that in the bypass line (47), a control valve is provided, which is controlled to reduce the raw gas supply to the combustion chamber (6) when the predetermined combustion chamber temperature is exceeded delayed. 21. The method according to claim 19 or 20, characterized in that the combustion chamber (6), before it is supplied to raw gas, is heated to operating temperature. 22. The method according to any one of claims 19 to 21, characterized in that in the combustion chamber (6) a gaseous or liquid fuel is injected without external combustion air. Patent Attorney Dipl.-Ing. Michael Babeluk A-1150 Vienna, Marlaftllftr Oort ·! 39/17 TW .: (* 431) 1 (219194 toe (+4) 1) M2 M 333