JPH02273510A - Thermal cracking apparatus and method thereof - Google Patents

Abstract

PURPOSE: To completely progress a pyrolysis reaction by providing a gaseous stream stagnation apparatus with a flow passage for a gaseous stream around a central opening for passing gas from a main combustion chamber to a sub- combustion chamber and providing the apparatus with a diagonal downward nozzle for supplying secondary air to the main combustion chamber. CONSTITUTION: The sub-combustion chamber 15 is disposed above the main combustion chamber 1 of an approximately cylindrical shape and the stream of the gas contg. hazardous materials is introduced into the chamber 1 by an introducing aperture 3. The gas contg. the hazardous materials is combusted by a burner 4 disposed to direct flames toward the chamber above the introducing aperture 3. Further, the annular gaseous stream stagnation apparatus 20 disposed above the burner 4 is provided with the diagonally downward facing nozzles 10a, 10b which segment a central opening 7 having the diameter smaller than the diameter of the chamber 1 and a flow passage means 9 for the gaseous stream disposed around this central opening 7 for passing the stream of the gas from the chamber 1 to the chamber 15 and supply secondary air to the chamber 1. Consequently, the pyrolysis react is completely progressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is directed to the removal of aj, especially dioxin (dlox1r+s) and furan (furan) in gases such as exhaust gas.
This device consists of a roughly cylindrical main combustion chamber, an auxiliary combustion chamber placed above it, and a gas containing harmful substances. In order to introduce the flow with angular momentum into the main combustion chamber, at an angle to the tangent plane: 1: 11 parts of the introduced amount communicating with the combustion chamber and to burn the gas containing harmful substances. and a burner arranged to direct the flame into the main combustion chamber.

An annular gas flow retention device is disposed at 1-h of the burner, the gas flow retention device having a central opening for directing the gas flow from the combustion chamber 1 to the secondary combustion chamber. The central opening has a smaller diameter than that of the cylindrical main combustion chamber, and the gas flow retention device is provided with nozzle means directed obliquely downward.

[Prior art and problems to be solved by the invention] Substances with extremely harmful compositions such as dioxins and furans can only be economically decomposed at high temperatures into less problematic compounds. It can be disposed of by

For example, West German Patent Application Publication No.
edGermanPentApp! Ic
atlon) No. 3i2357B04 discloses a combustion device equipped with a burner using a fuel such as natural gas for thermal decomposition of such harmful substances. A combustion chamber with a large volume is required to ensure sufficient residence time for harmful substances to burn in the high temperature region. Such furnaces are correspondingly expensive and, moreover, the gas flow in the combustion chamber is turbulent and difficult to mix properly in order to ensure the desired pyrolysis. If the volume of the combustion chamber is reduced,
The residence time of harmful substances in the high temperature region is too short, and the decomposition reaction is not completed completely.

Therefore, the main object of the present invention is to eliminate these problems and to provide a device for thermally decomposing fluid harmful substances contained in gas, which is compact but allows the gas containing harmful substances to enter the combustion chamber. The object of the present invention is to provide an apparatus that ensures sufficient retention in the pyrolysis reaction and allows the thermal decomposition reaction to proceed completely.

Means for Solving the Problems In an apparatus of the type described at the outset, according to one aspect of the invention, the burner is operated with obliquely downwardly directed nozzle means supplying secondary air to the main combustion chamber. The above objectives are achieved by arranging the flame to flow toward the main combustion chamber above the introduction opening, and by partitioning the circulation means arranged around the central opening by the annular retention device. be done.

In such devices, the gas containing the harmful substances to be decomposed is introduced through the introduction opening into the bottom of the main combustion chamber and becomes the primary gas for the burner. The first stage of combustion is carried out stoichiometrically or slightly less than stoichiometrically. 800' C to 1 produced by this combustion
A high temperature of 400@C is suitable for thermal decomposition of complex organic molecules such as dioxins and furans. The retention device prevents gas from leaving the main combustion chamber too quickly, and the downwardly directed nozzles in the retention device supply secondary air to the upper combustion chamber. The main purpose of this is to keep the combustion gases in the main combustion chamber longer. Furthermore, by supplying secondary air to the main combustion chamber, it is sufficiently over-aired to ensure complete combustion of all combustible constituent molecules, thereby reducing the amount of hydrocarbons and CO emissions can be kept extremely low. For discharging the exhaust gases from the main combustion chamber towards the chimney, the retention device is provided not only with a central opening, but also with a separate channel for the exhaust gases surrounding this central opening in the region of the walls of the combustion chamber. Long-term tests have shown that it is preferable to provide Since angular momentum is given to the gas flow,
The heavier constituent molecules tend to remain in the region near the walls of the combustion chamber, while the lighter gas constituent molecules tend to collect in the region near the axis of the combustion chamber. By providing a central opening in the retention device with surrounding channel means, the undesirable selective removal of lighter gas constituents is avoided. Preferably, the annular retention device includes a crosspiece between the central opening and the channel means, the crosspiece having an annular sector shape;
It coaxially surrounds the axis of the cylindrical main combustion chamber. These bars are connected to the outside (11a1) of the annular retention device by two or more support bars.The entire channel constituting the channel means has an annular fan shape.

According to another embodiment of the invention, a furnace is provided for pyrolyzing flowable hazardous substances contained in a gas, the furnace comprising a furnace wall assembled modularly by stacking annular sections. The furnace wall defines a substantially cylindrical main combustion chamber and an auxiliary combustion chamber arranged above the main combustion chamber. Between these combustion chambers an annular gas flow retention device is arranged, which delimits a central opening with a smaller diameter than the cylindrical main combustion chamber, and which also defines an annular furnace U section. One of them is the outer part of the retention device.

This pyrolysis furnace has a very simple configuration.

To be more specific, 6. Assemble the furnace in advance.
It is possible to use dicol and greatly reduce the time required to erect the furnace on site. By fitting and connecting with the
Another effect is that the same set of modifiers can be used to construct combustion chambers of different capacities, and the operating conditions used in boat fishing can be used to construct ideal furnaces for each. This is something that can be done.

[Example] A device for thermally decomposing pollutants contained in gas will be explained with reference to the figure.The figure shows a furnace equipped with 16 approximately circular combustion chambers.・The main combustion chamber is partitioned by an outer wall portion consisting of annular piece 2 that forms the wall surface of the furnace.The portion L% that forms the wall of the furnace
L2 has a substantially circular shape and is composed of several layers. In Figure 1, there is an inner layer 17 of seven refractory bricks, and two layers L8 and 19 surrounding the first layer of refractory bricks on the inside. 61, and since the sections of the furnace wall have a multilayer structure, it is necessary to use the most suitable materials for all areas of the wall of the combustion chamber5.
I can do things efficiently. As is well known, rock wool
A buffer material consisting of a buffer material consisting of The stress acting on the brick provides the first seal for the combustion chamber. The steel jacket itself constitutes another seal and there is no need to operate the device under negative pressure.2 This This eliminates the need for expensive suction ventilation equipment.

As shown in FIG.
The end surface 21 has an annular protrusion, that is, a protrusion 22, which defines an annular groove between the protrusions 22. As a result, the abutting sections are fitted together by the protrusion and the annular groove 1, ensuring proper sealing between these sections. (1σ) The wall sections 11 are of the same shape and can be connected in any way (such that they are lossy and form combustion chambers of the same diameter but different volumes). can.

Figure J (4) The device consists of an auxiliary combustion chamber 15 arranged at the 10th corner of a circular 1:combustion chamber, and a gas flow containing harmful substances into the 4-combustion chamber. ] Three combustion chambers are also provided with an inlet and an opening leading to the combustion chamber.
The equipment is operated with an excess of air, and the agitator gas depletes oxygen and functions as a combustion gas. ,
1: When there is no or insufficient oxygen in this gas flow introduced into the combustion chamber 1.
The rice may be mixed with the surrounding air. .

Introduced amount [-1 part] The axis 3a of the main combustion chamber is 1. 1) oriented in the radial force direction, i.e. extending in the 10-radial force direction -r'' is also acceptable, but it is also possible to wipe the inlet opening 3 into the main combustion chamber 1.
It is preferable to impart angular momentum to the gas flow introduced into the main combustion chamber at an acute angle (, , , with respect to I' and λ).

, complete angular momentum 1 goyo 1], make sure that the gas flow becomes turbulent and the gas components are well mixed in the main combustion chamber.
First, operational efficiency is optimized.

In the illustrated example, a 3 fμm burner 4 (schematically shown) directs the ax 4b into the main combustion chamber 1 at the introduction opening 3 in order to burn out harmful substances. 2) Yo・)
It is arranged as follows. These three burners are equally spaced around the periphery of the main combustion chamber.
+7, but use one burner or more than one burner 1. It should be understood that this may be the case. Barb-4 at gland, '1a slightly above 1
14. While facing towards the enemy, the stiffness also makes an acute angle to the contact surface. The gas is extended by l'5 and increases its angular momentum. By shedding the burner toward the L side of the inlet opening, all of the gas flow passes through the flame. It is ensured that either the flag or fl.

As shown in Figure 1, an annular TF gas flow retention device? 4+
:20 is -main combustion chamber 1,! : Located above the banner/1 between the egg and the combustion chamber 15. 1.1. The combustion chamber 1 and the auxiliary combustion chamber 15 are separated from each other by #1. The retention device 2 (-) has a central opening, 7, which has a smaller diameter than the diameter of the cylindrical main combustion chamber 1 and allows the gas flow to pass from the main combustion chamber to the sub-combustion chamber, and a central opening. A flow path means is defined by a flow path 9 arranged around the flow path 7. In the furnace shown, the annular furnace wall section 5 constitutes the outer part of the retention device, the inner part of which is composed of webs 6 each having the shape of an acute sector, which are joined together. This results in an annular retention device having a central opening 7. The crosspiece 6 between the central opening 7 and the flow path 9 surrounding it has a substantially trapezoidal cross section (see FIG. 3) with side surfaces that converge downward. This shape is ideal as a housing for accommodating the secondary air nozzle 10a110b because it prevents the angle between the downwardly directed nozzle and the side surface of the crosspiece from becoming too flat.

In the retention device the channel means are arranged around a central opening, in the illustrated example a channel 9 between the crosspiece 6 and the inner wall 8 of the combustion chamber.

Retention device! 20 further includes secondary air, preferably 15
It has obliquely downwardly directed nozzle means 10a, 10b for feeding into the main combustion chamber 1 at an angle α of .degree. In the illustrated example (see FIG. 3), nozzle 10a is tangentially inward, whereas nozzle 10b is tangentially inward,
These nozzles are oriented outwardly to increase the angular momentum of the secondary air passed through it to the main combustion chamber, and these nozzles direct the angular orientation of the gas flow in the main combustion chamber. Almost directed. These nozzles are not directed towards the axis 1a of the combustion chamber, but away from it. This not only creates an optimal residence time for the combustion of the gas in the combustion chamber, but also creates a desirable downward stirring flow for the gas that is to be stirred in the combustion chamber. By directing the secondary air supply diagonally downward, rapid flow of gas toward the chimney is avoided.

The outwardly directed secondary air supply nozzle 10b extends substantially tangentially to the center circle inscribed in the crosspiece 6,
Gas flow through channel 9 is retarded, whereas similarly extending inwardly directed nozzles 10a retard gas flow through the intercenter lower. All these nozzles are oriented in the same direction as the burner 4, either clockwise or counterclockwise with respect to the axis 1a of the combustion chamber. This further increases the angular momentum in the combustion chamber, increasing the mixing action and correspondingly better combustion conditions.

The annular retention device 20 further includes a support bar 13 that supports the bar 6.
(Figure 2). The support bar 13 separates the channels 9 from each other, and the arched bar 6 defines a secondary air conduit between the central opening 7 and the channel 9 surrounding it. . The support crosspiece 13 defines a conduction path 12 for supplying secondary air to the conduction path 11 of the crosspiece 6. In this configuration, the secondary air supply nozzles may be arranged along the entire circumference of the crosspiece.

If desired, the secondary air may contain other substances of concern for environmental pollution, in the form of liquids or solid particles. This may be particularly advantageous if gases containing harmful substances in higher concentrations than the exhaust gases are to be detoxified, for example.

It is also possible to send the ash together with the secondary air into the main combustion chamber, in which case after it has passed it is removed from the bottom of the combustion chamber as an inert glassy medium. . Vitrified ash does not contain water-soluble substances and can be disposed of without problems. Thus, this device is used not only to treat exhaust gases, but also to treat ash.

Annular retention device! ff120 is such that the retention device has a flow passage cross-sectional area through which the gas flow passes by 20% to 50%, preferably 30%.
It is advantageous to design it so that it is reduced by between 35% and 35%. In other words, in plan view, the bars of the detention device 20 cover this recommended percentage of area. The cross-sectional area of this gas flow is determined by the central opening 7 and the passage 9 surrounding it. In the design of the residence device 20, it is important to take into account the residence time of the gas stream containing harmful substances in the main combustion chamber as long as possible; E3 means that the flow must be impeded as much as possible. On the other hand, the pressure loss in the combustion chamber 44 should be kept to a minimum so that the gas flow exits suitably by its own conveying force or at least by means of the smallest possible ventilation equipment. Tests have shown that such situations are compatible with a range of -2%, and optimally reduces the cross-sectional area of the gas flow by 17".

The secondary combustion chamber 15 is arranged above the gas flow retention device 20 in the furnace to complete the combustion process. A third gas supply nozzle] 6 is arranged at one end of the auxiliary combustion chamber (see Figure 1), and is an elbow joint that increases the amount of combustion air supercharging and also deflects the gas flow. 24 cools and exhausts the gases exhausted through a chimney (not shown) attached to the furnace. The gas supply nozzle 16 is also directed slightly downward toward the auxiliary combustion chamber 15, which increases the residence time of the gas in this combustion chamber.
By combusting the gas while additionally supplying the third air and the third air, the exhaust gas leaving the furnace becomes more purified.

It is shown in Figure 1. J: Sea urchin, auxiliary combustion chamber] A manhole 23 is provided on the wall of 5. 1. Introducing the gas flow The gas flow moves from the opening 3 to the chimney.゛Regarding items 1 and 7 to generate the necessary conveying force, a suction fan is not necessary, but is desirable.'1. ``C'' is also good.

During operation, gas containing harmful substances sent from, for example, a garbage incinerator, is introduced into the main combustion chamber 1 through the introduction opening '3, where it spirals upward. It flows and passes through the flame from burner 4.

1. Through the nozzles 10a, 1 Ob of the gas flow retention device. The secondary air flowing downward is the 47. J'?
2 to increase the residence time of the gas flow in the main combustion chamber. Finally, through the central opening 7 and the flow path 9, the gas flow enters the secondary combustion chamber 15, where the thermal decomposition reaction of the harmful substances is completed. The purified gas then exits the device through the elbow joint 24 and the chimney.

[Effect of the invention] Above 1. Apparatus of this configuration provides nearly complete removal of all white matter from gases handled under all practical operating conditions, including only partially chambered conditions. Moreover, this is accomplished by a furnace of relatively simple construction and low cost.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view in the axial direction of the furnace according to the present invention;
Figure 2 is a horizontal mid-level view taken along line nn of Figure 1, Figure 3 is an enlarged partial detail of the retention device rung, and Figure 4 is another detail of the rung. An enlarged partial view showing. 1...1:, Combustion chamber, 'U...Introduction opening, 4...
Burner 6... Crosspiece, 7... Center opening, 1Oa, 1O
b... Nozzle, 13... Support bar, 15... Sub-combustion chamber, 20... Gas flow retention device. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] 1. An apparatus for thermally decomposing fluid harmful substances contained in gas, comprising (a) a substantially cylindrical main combustion chamber, and (b) a sub-combustion chamber disposed above the main combustion chamber. (c) an inlet opening leading to the main combustion chamber for introducing the flow of gas containing the noxious substance into the main combustion chamber; and (d) an inlet opening for combusting the gas containing the noxious substance. a burner disposed above with a flame directed toward the main combustion chamber; (e) an annular gas flow retention device disposed above the burner; (2) a central opening for passage of gas having a diameter smaller than the diameter of the cylindrical main combustion chamber; and (2) defining a gas flow channel means arranged around the central opening; ) a gas flow retention device having an obliquely downwardly directed nozzle for supplying secondary air to the main combustion chamber; 2. The pyrolysis apparatus according to claim 1, wherein the inlet opening is oriented toward the main combustion chamber at an acute angle with respect to the tangential plane, imparting angular momentum to the gas flow introduced into the main combustion chamber. 3. The pyrolysis apparatus of claim 1, wherein the nozzle means is directed downwardly at an angle to the main combustion chamber. 4. The pyrolysis apparatus of claim 3, wherein this angle is approximately 15°. 5. The nozzle means comprises tangentially outwardly directed nozzles as well as tangentially inwardly directed nozzles to increase the angular momentum of the secondary air supplied therethrough; 2. A pyrolysis apparatus as claimed in claim 1, wherein the nozzle means is oriented generally in the direction of gas flow in the main combustion chamber. 6. Claim 6, wherein the annular retention device is provided with an arch-shaped fan-shaped crosspiece between the central opening and the gas flow channel means, and the arch-shaped fan-shaped crosspiece constitutes a ring. 1st
The pyrolysis device described in section. 7. The pyrolysis apparatus according to claim 6, wherein the cross section of the annular retention device has a substantially trapezoidal cross-sectional shape, and the cross section of the trapezoidal cross section has both side surfaces that converge downward. 8. The annular retention device further includes a support bar that supports the bar having an arched fan shape, and the bar having the arched fan shape connects the central opening and the flow path means surrounding the central opening. A communication groove means for secondary air is provided inside the groove, and the supporting crosspiece is disposed between each channel of the flow channel means, and the support bar is arranged between the channels of the channel means to conduct the secondary air in an arch-like fan shape. 7. The pyrolysis apparatus according to claim 6, wherein the groove for feeding into the communication groove of the crosspiece is partitioned. 9. The pyrolysis apparatus according to claim 1, further comprising nozzle means disposed at the upper end of the sub-combustion chamber for supplying tertiary air. 10. The pyrolysis apparatus of claim 1, wherein the annular retention device is configured to reduce the cross-sectional area of the gas flow therethrough by 20% to 50%. 11. The pyrolysis apparatus of claim 10, wherein the annular retention device is configured to reduce the cross-sectional area of the gas flow by 30% to 35%. 12. A furnace for thermally decomposing fluid hazardous substances contained in gas, which includes (a) a furnace wall assembled in a modular manner consisting of a plurality of stacked annular pieces, and (1) a substantially cylindrical furnace wall; (2) a furnace wall that partitions a auxiliary combustion chamber arranged above the main combustion chamber; and (c) an annular main combustion chamber arranged between the main combustion chamber and the auxiliary combustion chamber. A gas flow retention device is defined by (1) a central opening having a smaller diameter than the cylindrical main combustion chamber; and (2) one of the annular furnace wall segments forming the outer portion of the retention device. A pyrolysis furnace equipped with a gas flow retention device. 13. The furnace wall section is composed of a plurality of layers, and the inner layer of the furnace wall section is made of refractory bricks, and at least one of the layers surrounding this inner layer is made of refractory bricks. Claim 12, wherein one is made of buffer bricks.
The pyrolysis furnace described in section. 14. The pyrolysis furnace according to claim 12, further comprising a buffer material made of rock wool and a steel jacket material surrounding the partial piece of the furnace wall. 15. A method for thermally decomposing fluid substances contained in gas, comprising the steps of: a) introducing a gas stream containing harmful substances into a main combustion chamber; and b) introducing a burner flame into the main combustion chamber. c) retaining the gas in the main combustion chamber by means of downwardly directed secondary air exiting from an inlet provided in an annular gas flow retention device located above the burner; d) through the central opening of the retention device and through another opening surrounding this central opening in the region of the furnace wall of the combustion chamber, the exhaust gases pass through the sub-combustion chamber and further through the chimney; A pyrolysis method comprising a process. 16. The pyrolysis method of claim 15, wherein the secondary air is mixed with other harmful substances before being sent to the combustion chamber.