Device for incinerating waste gas

Abstract

A device for incinerating waste gases has a combustion chamber, burner for burning waste gas in the combustion chamber, and a tubular conduit extending substantially vertically from the combustion chamber so that products of combustion of the waste gas in the combustion chamber travel vertically upwardly through the tubular conduit, the tubular conduit being composed of a plurality of tubular elements located one above the other and arranged relative to one another so as to form a gap between each two neighboring tubular elements for introducing air into an interior of the tubular conduit through the gaps.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to devices for incineration of waste gases.

[0002] There is a frequent need in the oil and gas industry to dispose of flammable gases. This is usually necessary because small quantities of gas are either not economical to process or are toxic and must be neutralized. The most common means for eliminating these gases is to burn them in the atmosphere using a flare stack. This device typically is formed as a tall pole with an open diffusion flame anchored at the top. The orange color of the flame and the intermittent presence of black soot are evidence that the combustion process is not particularly efficient with this type of apparatus. The efficiency can be further adversely affected by the presence of ambient winds. Some parts of a diffusion flame are relatively cool and the residency time of the combustibles in the flame can be quite short. Under some conditions, certain chemical species may not undergo complete thermal decomposition and oxidation. This can lead to the release of toxic substances, for example hydrogen sulphide, into the atmosphere. The results are obnoxious odors and an unsightly flame, both of which have become the targets of environmental groups and government regulatory agencies.

[0003] It is known that efficient burners are used in industrial incinerators. However, the combustion chamber in these devices is typically lined with a glass or ceramic refractory liner in order to protect the chamber walls from the high temperature corrosive gases. Some methods of minimizing the heat transfer from hot exhaust gases to the surrounding duct walls for the purpose of minimizing the emitted infrared radiation from a war ship are proposed in U.S. Pat. No. 4,355,507 and Canadian patent no. 1,134,827. These methods employ the well known phenomenon of film cooling.

[0004] It is believed that improvements in waste gas incinerating devices are both desirable and achievable via the appropriate application of similar film cooling techniques.

SUMMARY OF THE INVENTION

[0005] Accordingly, it is an object of present invention to provide a device for incinerating waste gases, which avoids the disadvantages of the prior art.

[0006] In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in a device for incinerating waste gases, comprising a combustion chamber; means for burning waste gas in said combustion chamber; and a tubular conduit extending substantially vertically from said combustion chamber so that products of combustion of the waste gas in said combustion chamber travel vertically upwardly through said tubular conduit, said tubular conduit being composed of a plurality of tubular elements located one above the other and arranged relative to one another so as to form a gap between each two neighboring tubular elements for introducing air into the interior of said tubular conduit through said gaps.

[0007] In accordance with another feature of the present invention, the tubular elements have different diameters such that a tubular element with a greater diameter is located above a tubular element with a smaller diameter to form the gap therebetween.

[0008] In accordance with another feature of present invention, the tubular elements of the tubular conduit are formed so that the gaps are open outwardly so that the air can be introduced through the gaps from outside inwardly into each of the tubular elements.

[0009] In accordance with still a further feature of present invention, means is provided for the forced supply of air through the gaps between said tubular elements.

[0010] In accordance with still a further feature of present invention, an additional tubular enclosure is arranged around the tubular conduit so that air is supplied first in a space between the tubular conduit and the tubular enclosure and then travels through the gaps into the interior of the tubular conduit.

[0011] In accordance with still another feature of present invention, each of the gaps is subdivided in a circumferential direction by a plurality of partitions which serve to connect the tubular elements with one another and also to straighten the flow of air entering the gaps.

[0012] In accordance with still a further feature of the present invention, the partitions of one gap are circumferentially offset relative to the partitions of the other gap to form offset slots therebetween.

[0013] The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is a view schematically showing a device for incinerating waste gas;

[0015] FIGS. 2 and 3 are views showing two modifications of the inventive device for incinerating waste gas; and

[0016] FIG. 4 is a plan view of the inventive device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A device for incinerating waste gases shown in FIG. 1 has a combustion chamber which is identified as a whole with reference numeral 1. It can be provided with a plurality of burners which are identified with reference numeral 2 and can be formed from known commercial burners which are used for burning gases. A number and location of the burners 2 in the combustion chamber 1 is selected in accordance with the type and volume of waste gas to be incinerated and other related parameters.

[0018] The device for incinerating waste gases is further provided with a tubular conduit which is identified as a whole with reference numeral 3. The tubular conduit 3 extends vertically upwardly from the combustion chamber 1. It is to be understood that the combustion chamber 1 is open into the interior of the tubular element 3. For example a grate 4 can be arranged between the combustion chamber 1 and the tubular conduit 3 to permit the products of combustion of the waste gas to flow vertically upwardly from the combustion chamber 1 into the tubular conduit 3.

[0019] In accordance with the present invention, the tubular conduit 3 is composed of a plurality of tubular elements 5. The tubular elements 5 are shown as cylindrical tubular elements. However, of course, they can also have another cross-section, while then only being necessary to comply with the main requirement to have a peripherally closed wall. In accordance with the present invention, the tubular elements 5 have different diameters. In particular the diameters of the tubular elements increase vertically upwardly, so that the tubular element with a smaller diameter is located lower, and the tubular element with the greater diameter is located higher, correspondingly. The tubular elements 5 are arranged relative to one another so that a gap 6 is formed between two neighboring tubular elements. The combustion chamber 1 is provided with an auto ignitor 7 which is known in the art.

[0020] While FIG. 1 shows a general schematic view of the inventive device for incinerating waste gases, FIGS. 2 and 3 show further different embodiments of the inventive device. FIG. 2 shows the device for incinerating waste gases in accordance with the present invention, which is preferably used in a field remote from urban areas. As can be seen from FIG. 2 the gaps 6 between the tubular elements 5 are retained open to the outside. During the operation of the device shown in FIG. 2, the waste gas is burned by the burners 2 in the combustion chamber 1 and the products of combustion flow upwardly into the tubular conduit 3. During upward movement of the products of combustion, air is aspirated through the gaps 6 between the tubular elements 5 as a consequence of the low static pressure that exists inside the tubular conduit 3. Each tubular element is fitted along its lowermost edge with a peripherally oriented external tube 5′ that promotes structural rigidity of the tubular element and also provides a well rounded inlet for the air entering gap 6.

[0021] The tubular conduit 3 protects the combustion process from ambient winds. It also removes the combustion process from public view. The entrained ambient air both protects the innerwalls of the tubular conduit 3 from the hot corrosive gases and also convects away the heat radiated from the hot gases to the inner walls, and thereby it is not necessary to provide a refractory liner as in known devices. Entrained ambient air also ensures well-ventilated and efficient combustion. Also, the resulting combustion products are diluted by ambient air before they exit the device. This aspect of the invention, in conjunction with the fact that the gases inside the conduit achieve significant vertical velocity, results in lower ground-level concentrations of combustion products than for an equivalent conventional flare stack. This is important from both a regulatory point of view and from the standpoint of minimizing odours. The device shown in FIG. 2, because of its open slots 6, of course produces some noise, and therefore, it is not recommended to be used in urban areas.

[0022] In contrast, the device shown in FIG. 3 is recommended for urban areas. The device shown in FIG. 3 substantially corresponds to the device shown in FIG. 2, but in addition it has means for forced supply of air which is identified with reference 8. The means for forced supply of air can be formed for example as a centrifugal air blower. Additionally a tubular enclosure 9 is provided which surrounds the tubular conduit 3 so as to form a peripheral space therebetween.

[0023] During the operation of the device shown in FIG. 3, air is forcedly supplied by the centrifugal blower 8 into a space between the tubular enclosure 9 and the tubular conduit 3, and then air flows through the gaps 6 into the interior of the corresponding tubular elements 5 of the tubular conduit 3, with the results which were previously explained herein in connection with the device shown in FIG. 2. Since the device is provided with the enclosure 9 it does not generate excessive noise and, therefore, can be used in urban areas.

[0024] FIG. 4 shows the structure of the gaps 6 between the tubular elements 5. As can be seen from this drawing, each gap is subdivided into a plurality of slots which adjoin one another in a peripheral direction. The subdivision of the gap 6 into slots 10 is performed by partitions 11. The partitions 11, in addition to the subdivision of the gaps 6 into the slots 10, serve for connection of the two adjoining tubular elements 5 with one another. They are preferably formed as connecting ribs. These partitions reduce the adverse effect of cross winds on the flow entering the gaps 6.

[0025] As can be also seen from FIG. 4, the slots 10 of different gaps 6 are offset relative to one another in a peripheral direction. This provides a more efficient distribution of air supply into the interior of the tubular conduit 3.

[0026] Complete thermal decomposition and oxidation of noxious substances require that the combustible be maintained above a threshold temperature for a minimum duration. The required temperature and duration depend on the substances being burned. With the present invention it is possible to control the temperature history and residency time of the substances being combusted by an appropriate selection of the size and position of the entraining slots 10 relative to one another, and the overall heights of the conduit 3.

[0027] It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

[0028] While the invention has been illustrated and described as embodied in device for incinerating waste gas, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

[0029] Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

Claims

1. A device for incinerating waste gas, comprising a combustion chamber; means for burning waste gas in said combustion chamber; and a tubular conduit extending substantially vertically from said combustion chamber so that products of combustion of the waste gas in said combustion chamber travel vertically upwardly into said tubular conduit, said tubular conduit being composed of a plurality of tubular elements located one above the other and arranged relative to one another so as to form a gap between each two neighboring tubular elements for introducing air into the interior of said tubular conduit through said gaps.

2. A device as defined in claim 1, wherein said tubular elements have different diameters such that a tubular element with a greater diameter is located above a tubular element with a smaller diameter to form said gap therebetween.

3. A device as defined in claim 1, wherein said tubular elements have a cross section other than circular.

4. A device as defined 1, wherein said tubular elements of said tubular conduits are formed so that said gaps are open outside so that the air is aspirated through said gaps from outside inwardly into each of said tubular elements.

5. A device as defined in claim 1, wherein the number, size and position of said gaps are chosen so that the wall temperature of the tubular elements does not exceed a specified value.

6. A device as defined in claim 1, wherein the number, size and position of said gaps are chosen so as to provide the maximize possible dilution of the combustion products before said products exit said tubular conduit.

7. A device as defined in claim 1, wherein the number, size and position of said gaps are chosen so as to ensure the combustion products exceed a specified temperature for a specified duration before said products exit said tubular conduit.

8. A device as defined in claim 1; and further comprising means for forced supply of air through said gaps between said tubular elements.

9. A device as defined in claim 1, wherein an additional tubular enclosure is arranged around said tubular conduit so that air is supplied first in a space between said tubular element and said tubular enclosure and then travels through said gaps into an interior of said tubular conduit.

10. A device as defined in claim 1, wherein each of said gaps is subdivided in a circumferential direction by a plurality of partitions which form a plurality of slots and also serve for connecting said tubular elements with one another.

11. A device as defined in claim 1, wherein the partitions of one gap are circumferentially offset relative to the partitions of the other gap.