JP3052737B2 - Combustion gas mixing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the incineration of municipal garbage, sewage sludge, human waste sludge, and flammable industrial waste in an incinerator such as a stoker furnace (also called a combustion furnace).
Using a barrier, the combustion gas containing a large amount of unburned gas on the upstream side in the flow direction of garbage and the combustion gas on the downstream side containing a large amount of oxygen collide with each other and are mixed and agitated. The present invention relates to a method for mixing combustion gas for reducing harmful substances such as unburned gas containing a large amount of hydrocarbons and organic chlorine compounds containing dioxin.

[0002]

2. Description of the Related Art Conventionally, incinerators such as stoker furnaces have been used.
When incinerating municipal waste, sewage sludge, human waste sludge, and flammable industrial waste (hereinafter collectively referred to as “waste such as municipal waste”), carbon monoxide and aromatic hydrocarbons in exhaust gas It is an issue to reduce harmful substances such as unburned gas and organic chlorine compounds containing dioxin (hereinafter, referred to as “unburned gas and harmful substances”) containing a large amount of dioxin.

[0003] As a technique for solving the above problems, we have
The following proposal was made in Japanese Patent Application Laid-Open No. 2-166306, entitled "Title of Invention: Method for controlling dioxins and the like in refuse incinerators and the like." In a method of mixing combustion gas in a stoker furnace called a two-flow furnace, a barrier for branching the combustion gas is provided, and a combustion gas containing a large amount of unburned gas and a combustion gas containing a large amount of oxygen are provided. A method of suppressing unburned gas, harmful substances, and the like by mixing in a predetermined residence space and maintaining a high temperature for a predetermined time (hereinafter, referred to as “prior art 1”).

Further, Japanese Utility Model Laid-Open No. 4-108130 entitled "Invention name: Combustion gas mixing structure in a refuse incinerator" discloses a stoker furnace as shown in FIG.
Discloses a structure for promoting the mixing of the combustion gas by a barrier 6 for diverting the combustion gas at an outlet 1a of the fuel cell (hereinafter referred to as "prior art 2").

Japanese Patent Application Laid-Open No. 5-126326 discloses a method of mixing combustion gases in a fluidized-bed furnace or a stoker furnace by means of a barrier (hereinafter referred to as "prior art 3"). ).

[0006] In any of the prior arts 1 to 3, after the combustion gas is separated by a barrier or the like in the incinerator, it is joined again to collide and mix and agitate, thereby suppressing unburned gas and harmful substances. Is the way.

[0007]

However, as in the prior arts 1 to 3, simply mixing and stirring by dividing and merging the combustion gas by the barrier does not involve the unburned gas and harmful substances and the like present in the exhaust gas. There is a problem that it is difficult to keep the concentration at a low level. That is, in consideration of the flow rate of the combustion gas, the combustion gas temperature, and the like, it is important to determine under what conditions the combustion gas should collide, mix and stir when the combustion gas merges in the stagnation space.

In the prior arts 1 and 2, the above-mentioned specific contents concerning the effective mixing method for suppressing the unburned gas and harmful substances to a low concentration are not disclosed.

In Prior Art 3, a numerical value relating to the flow rate of the combustion gas at the throttle portion (the flow path of the combustion gas between the barrier and the furnace wall) formed by the furnace wall is shown. Because it is affected by the furnace width and the combustion gas temperature, it is not uniquely determined from the flow rate of the combustion gas.Even if the numerical value of the flow rate of the combustion gas is limited, it is effective to suppress the unburned gas and harmful substances to a low concentration. I'm not showing you how.

Accordingly, an object of the present invention is to provide a method for incinerating municipal garbage, sewage sludge, human waste sludge, combustible industrial waste, and the like in an incinerator such as a stoker furnace by combining the combustion gases separated by a barrier. Provided is a method for mixing combustion gas that can suppress unburned gases such as carbon monoxide and aromatic hydrocarbons and harmful substances such as organic chlorine compounds containing dioxin to a low concentration when mixed and stirred by collision. It is in.

[0011]

SUMMARY OF THE INVENTION The present invention relates to an incinerator having a combustion chamber provided with a grate for burning while moving the incinerated material, wherein the incinerator moves the incinerated material near an outlet of the combustion chamber. Provide a barrier for branching the combustion gas on the upstream side in the direction and the combustion gas on the downstream side in the moving direction, the upstream side combustion gas containing unburned gas generated in large quantities from the incinerated material on the upstream side in the moving direction, and The downstream combustion gas containing more oxygen than the upstream combustion gas flows into the predetermined retention space from the upstream and downstream sides, respectively, through the space between the barrier and the combustion chamber furnace wall. In a method of mixing combustion gas in which an upstream combustion gas and a downstream combustion gas are caused to collide with each other and mixed, the downstream combustion gas in the flow path of the downstream combustion gas between the barrier and the combustion chamber furnace wall. A combustion gas flow rate F1, the ratio between the upstream combustion gas flow rate F2 in the flow path of the upstream combustion gas between the barrier and the combustion chamber furnace wall, F1: F2 =
8: 2 to 5.5: 4.5.

Also, the ratio of the cross-sectional area A1 of the narrowest portion of the space forming the flow path of the downstream combustion gas to the cross-sectional area A2 of the narrowest portion of the space forming the flow path of the upstream combustion gas. And A
1: A2 = 8: 2 to 5.5: 4.5.

The shortest distance L1 of the narrowest part of the space forming the flow path of the downstream combustion gas and the shortest distance L2 of the narrowest part of the space forming the flow path of the upstream combustion gas
Are characterized in that each is 0.3 m or more.

Further, the temperature at which the downstream combustion gas passes through the flow path and the temperature at which the upstream combustion gas passes through the flow path are each 830 ° C. or more. Have

[0015]

[Function] Dioxin and the like have the property of being thermally decomposed when the exhaust gas containing the same is heated to a high temperature due to its chemical structure. C as heat source when reburning from incineration
A state in which a large amount of unburned gas containing a large amount of O, HC, and the like is generated, and the unburned gas collides, mixes, and stirs with a combustion gas containing a large amount of oxygen in a predetermined stagnation space, and the unburned gas is in a state close to complete combustion. By recombusting and maintaining the temperature at a high temperature, dioxins and the like in the exhaust gas generated from the incineration material can be efficiently thermally decomposed, and the amount of the generation can be greatly reduced.

After the combustion gas on the upstream side in the flow direction containing a large amount of unburned gas and the combustion gas on the downstream side in the flow direction containing a large amount of oxygen are divided by the barrier, the two combustion gases are recombined in a predetermined stagnation space. When colliding and burning, according to the method of the present invention described above, (1) the combustion gas flow rate ratio, (2) the cross-sectional area ratio of the narrowest part of the space forming the combustion gas flow path, (3) the narrowest part By defining the shortest distance of (1) and (4) the temperature at which the combustion gas passes through the flow path, the action of reducing dioxins and the like can be ensured.

In an incinerator (two-stage incinerator) for waste such as municipal waste, the oxygen concentration of the combustion gas containing a large amount of oxygen is 9 V on a dry basis due to the properties of the incinerated material.
ol. % To 19 vol. %. Further, in a combustion gas containing a large amount of unburned gas, the oxygen concentration is 0 vol. %, And the concentration of carbon monoxide is 0.1 vol. % To 8 vol. %. Therefore, in the present invention, the combustion gas containing a large amount of oxygen means that the oxygen concentration is 9 to 19 vol.
l. % Is defined as a combustion gas containing a large amount of unburned gas, and is defined as a combustion gas having a carbon monoxide concentration of 0.1 to 8 vol. % Defined as combustion gas.

(1) The combustion gas flow ratio is defined as "F1: F2 =
8: 2 to 5.5: 4.5 ”Action: When waste such as municipal waste is burned in an incinerator such as a stoker furnace, a large amount of oxygen separated by a barrier is contained. The downstream combustion gas and the upstream combustion gas, which contains a large amount of unburned gas, collide and mix and agitate by re-merging in a predetermined stagnation space. (Hereinafter referred to as "incinerator"), the combustion product gas (combustion gas) generated by the combustion of the incinerated material (waste such as municipal waste) in the combustion chamber is the difference in the original size and composition of the incinerated material. Thus, at each point in the incineration flow direction from the upstream side to the downstream side where the incineration moves, different gas compositions (main components are oxygen, carbon monoxide,
Carbon dioxide, water vapor and nitrogen), and different gas properties (gas viscosity, dust concentration and viscosity, etc.) and have a certain size of concentration mass. Therefore, the downstream combustion gas containing a large amount of oxygen (flow rate F1)
And the upstream side combustion gas containing a large amount of unburned gas (flow rate F
2) and then merged again without considering the flow ratio (F1: F2), collided, and mixed and stirred to suppress the unburned gas and harmful substances in the combustion gas to a low concentration. A sufficient effect cannot be obtained.

In order to sufficiently obtain the above-described effects, oxygen in the flow path of the combustion gas flowing into the predetermined stagnation space, that is, the flow path of the combustion gas between the barrier and the furnace wall opposite to the barrier, is required. The flow rate ratio between the downstream combustion gas flow rate F1 including a large amount and the upstream combustion gas flow rate F2 including a large amount of unburned gas is represented by “F1: F2 = 8: 2 to 5.5: 4.5”. Should be within range. Note that the flow rate ratio does not include a fluctuation in a minute time in units of seconds, and indicates an average flow rate ratio.

When the flow ratio F1 is made smaller than "F1: F2 = 5.5: 4.5", that is, the flow rate F1 of the downstream combustion gas containing a large amount of oxygen becomes "F1 <(5.5 / 4. 5)
In F2 ″, sufficient oxygen cannot be supplied to the downstream combustion gas to reduce the unburned gas and harmful substances in the upstream combustion gas by mixing, and the effect of reducing the unburned gas and harmful substances is reduced. The sufficient amount of oxygen corresponding to the downstream combustion gas flow rate shown here: F1 = 5.5 is larger than the amount of oxygen obtained from the chemical reaction formula required for complete combustion of unburned gas and harmful substances. It is an amount necessary to break down the combustion gas concentration mass into minute concentration masses to generate a state that promotes the combustion reaction and to completely burn unburned gas and harmful substances.

On the other hand, if the flow ratio F1 is larger than "F1: F2 = 8: 2", that is, if the flow rate F1 of the downstream combustion gas containing a large amount of oxygen is "F1> (8/2) .F2", Due to the difference in the flow rate of the upstream and downstream combustion gases and the difference in the gas properties, the flow of the combustion gas is greatly disturbed, and the upstream combustion gas flowing through the upstream combustion gas flow path between the barrier and the road wall However, it passes near the barrier or the vicinity of the furnace wall, and the effect of promoting mixing and stirring of the barrier is reduced, and the effect of reducing unburned gas and harmful substances cannot be sufficiently obtained.

(2) The cross-sectional area ratio of the narrowest part of the space forming the combustion gas flow path is defined as “A1: A2 = 8: 2 to 5.5: 4.
Action by in the range of 5 ":. Furnace pressure incinerators are generally -5~-30mmH ₂ O approximately in the negative pressure of this order, that much oxygen between the barrier and the combustion chamber furnace wall The cross-sectional area A1 of the narrowest part of the space forming the downstream combustion gas flow furnace included therein and the cross-sectional area of the narrowest part of the space forming the upstream combustion gas flow furnace containing a large amount of unburned gas A
The cross-sectional area ratio with respect to "A1: A2 = 8: 2 to 5.5:
By setting the ratio within the range of 4.5 ", the above-mentioned combustion gas flow ratio can be set within the range of" F1: F2 = 8: 2 to 5.5: 4.5 ".

(3) Action by setting the shortest distances L1 and L2 of the narrowest part of the space forming the combustion gas flow path to 0.3 m or more: The combustion gas flow rate is affected by the properties of the incinerated material. It changes every moment, and a minute drift occurs in the flow of the combustion gas on the upstream side and the downstream side. Due to the influence of this drift, dust may start to adhere and accumulate on the barrier and the furnace wall facing the barrier irrespective of the flow velocity of the combustion gas flowing on the upstream side and the downstream side, and may block the combustion gas flow path. The shortest distance L1 of the narrowest part of the space forming the flow path of the combustion gas containing much oxygen downstream and the shortest distance L2 of the narrowest part of the space forming the combustion gas flow path containing much unburned gas upstream. Is 0.3 m or more, it is possible to prevent the combustion gas flow path from being blocked due to dust.

(4) Function by setting the temperature at which the combustion gas passes through the flow path to 830 ° C. or higher: In the present invention, the downstream combustion gas containing a large amount of oxygen and the unburned gas contain a large amount. The method of mixing and agitating the upstream combustion gas at the flow rate ratio described above, and further adding a condition that the temperature of the combustion gas is set to 830 ° C. or higher, so that carbon monoxide at the outlet of the incinerator is added. When the concentration is several ppm (10p
pm).

The unburned components such as carbon monoxide and hydrocarbons generated from waste such as municipal garbage decompose as the temperature increases, but the temperature deviation at which the decomposition rate of the unburned components changes around 830 ° C. Has a curved point. The inflection point temperature of 830 ° C. is a characteristic characteristic of combustion gas properties, that is, a temperature peculiar to the incineration of waste such as municipal garbage, which is affected by dust containing heavy metals, hydrogen chloride gas and soot in the combustion gas. It is. Therefore, in the present invention, the temperature of the combustion gas is set to 83
Should be limited to 0 ° C. or higher.

For example, comparing a gas turbine or an industrial furnace with an incinerator for waste such as municipal garbage, the gas turbine or the industrial furnace is a clean combustion for burning fuel such as city gas or propane. Since there is no such an effect as seen in an incinerator burning waste such as municipal garbage, the inflection point temperature is several tens of degrees lower than that of the municipal garbage or the like waste (830 ° C.).

In the method of mixing combustion gas in an incinerator outside the scope of the present invention without using a barrier, or in the method of mixing combustion gas using a barrier and deviating from the flow rate ratio of the present invention even if a barrier is used, the above-mentioned temperature is not considered. If the inflection point is lower than 830 ° C., it is difficult to reduce the unburned component to several ppm.

[0028]

Next, the present invention will be described with reference to the drawings. FIG. 2 is a sectional view showing a fully continuous inclined grate type double-flow furnace according to an embodiment of the present invention. Reference numeral 1 in FIG. 2 denotes a combustion chamber of a fully continuous inclined grate type two-stage furnace (hereinafter, referred to as a "two-stage furnace"), and one side (the left side in FIG. 2) of the combustion chamber 1 is incinerated. A hopper 2 is provided for charging an object (waste such as municipal waste) 7 into the combustion chamber 1. At the bottom of the combustion chamber 1, a mesh-shaped grate 11 that burns while moving the incineration material 7 is provided inclining in a direction away from the hopper 2. A step is formed. At the lower part of the grate 11, there is provided a hollow block 5 to which a supply pipe 4 for supplying combustion air is connected. A combustion chamber outlet 1a is provided above the combustion chamber on the opposite side of the hopper 2, and the outlet 1a has a boiler section (hereinafter, referred to as a "boiler section") of a gas cooling facility downstream of the combustion chamber.
3) are connected to each other. In the combustion chamber 1, a barrier (also referred to as a baffle plate) 6 for diverting the combustion gas is provided near the outlet 1a.

The incineration of waste such as municipal waste in a two-flow furnace having such a structure will be described below. First, as shown in FIG.
Is supplied to the incinerated material 7 moving on the grate 11 through the supply pipes 4 and the cavity blocks 5 to dry and burn the incinerated material 7. At this time, the supply pipe 4 close to the hopper 2 (upstream side)
And the amount of combustion air supplied through the cavity block 5 is made smaller than the amount of combustion air supplied through the supply pipe 4 and the cavity block 5 on the other side (downstream side), so that the incineration material on the upstream side is reduced. 7 generates a large amount of unburned gas. The combustion gas 9 (indicated by an arrow) containing a large amount of unburned gas thus generated rises in the combustion chamber 1 and passes between the barrier 6 and the furnace wall of the combustion chamber 1 from above the barrier 6. It flows into the back side (upper side) of the barrier 6.

On the other hand, a combustion gas 10 (indicated by an arrow) which is completely burned by air supplied through the supply pipe 4 and the cavity block 5 on the downstream side of the grate 11 and contains a large amount of oxygen.
Rises in the combustion chamber 1, passes between the barrier 6 and the furnace wall of the combustion chamber 1 from below the barrier 6, and flows into the rear side of the barrier 6.

The combustion gas 9 and the combustion gas 10 are
Merge in a predetermined stagnation space on the back side (upper side) of the barrier 6,
Here, the combustion gases collide with each other, and the mixture is sufficiently mixed and stirred for a predetermined time to achieve complete combustion, the high temperature state is maintained, and harmful substances such as organic chlorine compounds including dioxin are thermally decomposed. Then, the exhaust gas after combustion (combustion gas discharged from the outlet 1a) flows into the boiler unit 3 downstream of the outlet 1a and is cooled.

FIG. 8 is a sectional view showing a grate furnace with a double-flow waste heat boiler according to another embodiment of the present invention. The incinerator shown in FIG. 8 is also similar to FIG. 2 in that the implementation of the method of the present invention results in unburned gas containing a large amount of carbon monoxide and aromatic hydrocarbons in exhaust gas and harmful substances such as organic chlorine compounds containing dioxin. Can be reduced to a low concentration.

FIG. 9 is a sectional view showing an embodiment of the shape of the barrier of the incinerator, and FIG. 10 is a sectional view taken along line AA of FIG. The barrier 6 shown in FIG. 9 and FIG.
This is an effective shape in the case of 6.7 t / h (400 t / 24 h) or more. In the stoker furnace, since the furnace width is increased in accordance with the throughput, the support wall 12 is provided so as to bisect the sub-flue 13 as shown in FIG. In addition, the barrier 6 and the support wall 12 may have a water-cooled structure having a heat exchange section inside. FIGS. 2, 8, 9 and 10 show one embodiment of the present invention, and the present invention is not limited to the above incinerator.

Using the two-flow furnace shown in FIG.
(1) flow rate ratio, (2) cross-sectional area ratio, (3) blockage prevention effect,
And (4) the temperature effect was investigated.

(1) Flow ratio: The barrier 6 and the combustion chamber 1 of the two-flow furnace with a boiler shown in FIG. 2 having an incineration treatment amount (hereinafter referred to as “treatment amount”) of about 6 tons / hour (t / h). Downstream combustion gas 10 rich in oxygen in the flow path between
The incineration was carried out by changing the flow rate ratio between the flow rate F1 of the combustion gas 9 and the flow rate F2 of the upstream combustion gas 9 containing a large amount of unburned gas in the flow furnace, and carbon monoxide (CO) in the exhaust gas in the boiler section 3 was changed. ) Was examined. Since the concentration of carbon monoxide changes depending on the oxygen concentration, the oxygen concentration of 12 vol. % (The same applies to the following carbon monoxide concentration measurement). The result is shown in FIG. As shown in FIG. 1, the flow ratio is “F1: F2 = 8: 2 to 5.5:
When the flow rate ratio is within the range of 4.5 ″, the concentration of carbon monoxide is reduced to several ppm (specifically, 3
pm or less).
Also, the hydrocarbon concentration shows the same behavior as the carbon monoxide concentration.

The dioxin concentration (I) corresponding to the carbon monoxide concentration (oxygen concentration 12 vol.%)
−TEQ ng / Nm ³ ) was examined in the boiler section 3. The result is shown in FIG. As shown in FIG. 3, the dioxin concentration was determined by the flow rate ratio “F1: F2 = 8: 2 to 5.5:
It can be seen that the carbon monoxide concentration and the behavior of the total hydrocarbon concentration corresponding to 4.5 ″ show low values almost similar to the behavior.

(2) Cross-sectional area ratio: In the two-flow furnace shown in FIG. 2, the cross-sectional area A1 of the narrowest part of the space forming the flow path of the downstream combustion gas 10 containing a large amount of oxygen and the unburned gas are reduced. The concentration of carbon monoxide in the exhaust gas of the boiler unit 3 with respect to the flow rate ratio of the cross-sectional area A2 of the narrowest space forming the flow path of the upstream-side combustion gas 9 that is largely contained was examined. FIG. 4 shows the results. As shown in FIG. 4, the cross-sectional area ratio is “A1: A2 =
8: 2 to 5.5: 4.5 ″, it can be seen that the carbon monoxide concentration can be suppressed lower than when the cross-sectional area ratio is out of the range. It shows the same behavior as the carbon concentration, and the cross-sectional area ratio is “A1: A
When 2 = 8: 2 to 5.5: 4.5 ", the ratio can be suppressed lower than when the cross-sectional area ratio is out of the range.

Next, in a two-flow furnace (shown in FIG. 2) having a throughput of about 3 to 8 t / h, the flow rate F1 of the downstream combustion gas 10 containing a large amount of oxygen and the unburned gas are contained a lot. Flow rate ratio “F1: F2” with the flow rate F2 of the upstream combustion gas 9
And the combustion is performed, and the flow rate F of the combustion gas 10 on the downstream side is changed.
1 and the cross-sectional area A1 of the narrowest part of the space forming the downstream combustion gas flow furnace with respect to the flow ratio of the flow rate F2 of the upstream combustion gas 9 and the space forming the upstream combustion gas flow furnace. The cross-sectional area ratio with the cross-sectional area A2 of the narrowest part was examined. The result is shown in FIG. As shown in FIG. 5, the cross-sectional area ratio “A1: A2 =
8: 2 to 5.5: 4.5 ”is the flow rate ratio“ F1: F2 =
It can be seen that the ratio is almost the same as the ratio of 8: 2 to 5.5: 4.5 ". The position of the barrier 6 installed in the furnace of each factory having different treatment amounts depends on the quality of the incineration material. However, the above result does not change regardless of the arrangement of the barrier 6.

(3) Blocking prevention effect: In the two-stage furnace shown in FIG. 2, the narrowest part of the space forming the flow path of the upstream combustion gas 9 containing a large amount of unburned gas divided by the barrier 6 is formed. The shortest distance L2 is set to 0.25 m outside the range of the present invention, and the flow rate of the combustion gas 9 is set to 1 m / s, 6 m / s or 15 m / s.
The flow rate F2 of the combustion gas 9 was changed at each of the flow rates, and clogging of the narrowest portion was examined. The flow rate F2 was changed by changing the processing amount of the incineration material. As a result, the flow rate of the combustion gas fluctuates from time to time, and dust floating in the combustion gas adheres to the barrier 6 and the furnace wall of the combustion chamber 1 facing the barrier 6 irrespective of the flow velocity due to the influence of the minute drift. Then, the deposition started, and the flow path was closed.

Next, in the two-flow furnace shown in FIG. 2, the shortest distance L of the narrowest part of the space forming the flow path of the upstream combustion gas 9 containing a large amount of unburned gas separated by the barrier 6 is formed.
We investigated how much 2 was needed. That is, the shortest distance L
2 was changed from 0.17 m to 0.51 m, and the clogging of the narrowest portion was examined. Note that the shortest distance L2 of the narrowest portion was changed by stacking bricks in the channel. Tests include general urban waste, plastic waste,
Separation waste containing plastic and incombustibles, mixing of general municipal garbage and sewage sludge, mixing of general municipal garbage and night soil sludge, and using any one of the above-mentioned sewage sludge as incineration materials. The combustion gas flow rate ranges from 2 m / s to 17 m / s depending on the properties of the incineration material.
Varied between. As a result, when the shortest distance L2 of the narrowest portion is less than 0.3 m due to fluctuations in the flow rate of the combustion gas of the incineration material and fluctuations in the properties of the incineration material, the flow path does not matter regardless of the flow rate of the combustion gas. Dust floating in the combustion gas flowing through the chamber starts to adhere and accumulate on the barrier 6 and the furnace wall of the combustion chamber 1 opposed to the barrier 6, and eventually blocks the flow passage, thereby hindering the operation. On the other hand, when the shortest distance L2 of the narrowest portion was 0.3 m or more, there was no adhesion and accumulation of dust.

(4) Temperature effect: The change in the combustion gas temperature at the combustion chamber outlet 1a (hereinafter referred to as "furnace outlet temperature") when the waste such as municipal waste is burned by the two-flow furnace shown in FIG. The behavior of the concentration of carbon monoxide in the exhaust gas of the boiler section 3 was examined. The result is shown in FIG. 6 by a solid line. For comparison, the behavior of the concentration of carbon monoxide in the exhaust gas of a general industrial furnace with respect to the change of the outlet temperature of the propane combustion exhaust gas was similarly examined. The result is also shown in FIG. 6 by a broken line.

As can be seen from FIG. 6, when waste such as municipal waste is burned, the temperature inflection point at which the decomposition rate of unburned components changes above 830 ° C. It can be seen that the concentration of carbon monoxide can be suppressed to about several ppm by setting the inflection point to 830 ° C. or higher. That is, when waste such as municipal waste is burned in a double-flow furnace, dust containing complex components including chlorine-based hydrogen chloride gas and heavy metals having a fire-extinguishing effect is generated in the combustion gas. Compared with propane combustion, the properties of the combustion gas become complicated, and a temperature difference of several tens of degrees occurs at the temperature inflection point for lowering the unburned components such as carbon monoxide and hydrocarbons. As shown, the temperature inflection point (indicated by ●) of combustion of waste such as municipal waste is higher than that in propane combustion (indicated by ▲).

Next, in a two-flow furnace with a boiler with a throughput of about 6 t / h shown in FIG. 2, the flow rate F1 of the downstream combustion gas 10 containing a large amount of oxygen and the upstream flow containing a large amount of unburned gas The concentration of carbon monoxide in the exhaust gas of the boiler unit 3 with respect to the change in the flow rate ratio of the combustion gas flow rate 9 on the side to the flow rate F2 was examined. At this time, the average temperature of the downstream combustion gas 10 containing a large amount of oxygen was changed between 700 ° C and 900 ° C. On the other hand, the temperature of the upstream combustion gas 9 containing a large amount of unburned gas was 900 ° C. or higher. FIG. 7 shows the result. FIG. 7 shows that the concentration of carbon monoxide was several ppm (10 pp).
m) when the downstream combustion gas temperature is 8
It turns out that it is the time of 30 degreeC or more.

Further, the flow rate ratio in a two-stage furnace having a processing amount of about 5.5 t / h is set to “F1: F2 =
7: 3 ″, and the temperature of the downstream combustion gas 10 is 83
As a result of measuring the carbon monoxide concentration of the boiler unit 3 when the temperature of the upstream side combustion gas 9 was set to 850 ° C.
The concentration could be suppressed to several ppm.

[0045]

As described above, according to the present invention, when municipal garbage, sewage sludge, human waste sludge, and combustible industrial waste are incinerated by an incinerator such as a stoker furnace, the waste is eliminated by a barrier. In the method in which the combustion gas containing a large amount of unburned gas on the upstream side in the flow direction and the combustion gas on the downstream side containing a large amount of oxygen are diverted and then joined again to collide and mix and stir, the combustion gas flow ratio By defining the cross-sectional area ratio of the narrowest part of the space forming the combustion gas flow path, the shortest distance of the narrowest part, and the temperature at which the combustion gas passes through the flow path, the monoxide in the exhaust gas is defined. Harmful substances such as unburned gas containing a large amount of carbon and aromatic hydrocarbons and organic chlorinated compounds containing dioxin can be reduced to a low concentration, thus providing an industrially useful effect.

[Brief description of the drawings]

FIG. 1 shows a processing amount of about 6 t / h according to an embodiment of the present invention.
Of the continuous continuous inclined grate type double-flow furnace with boiler of
Shows the concentration of carbon monoxide in the exhaust gas of the boiler section with respect to the flow ratio “F1: F2” of the downstream combustion gas flow rate F1 containing a large amount of oxygen and the upstream combustion gas flow rate F2 containing a large amount of unburned gas. It is a graph.

FIG. 2 is a sectional view showing a fully continuous inclined grate type double-flow furnace according to an embodiment of the present invention.

FIG. 3 is a graph showing the concentration of dioxins corresponding to the concentration of carbon monoxide in exhaust gas according to the example of the present invention.

FIG. 4 is a cross-sectional area A1 of a narrowest part of a space forming a downstream combustion gas flow path containing a large amount of oxygen in a fully continuous inclined grate type double-flow furnace with a boiler according to an embodiment of the present invention.
And the cross-sectional area ratio “A1: of the cross-sectional area A2 of the narrowest part of the space forming the upstream combustion gas flow path containing a large amount of unburned gas.
It is a graph which shows carbon monoxide density | concentration in the exhaust gas of a boiler part with respect to A2 ".

FIG. 5 shows a processing amount of about 3 to 8 t according to the embodiment of the present invention.
/ H, a downstream side combustion gas flow rate F1 containing a large amount of oxygen in a fully continuous inclined grate type double-flow furnace with a boiler of
The cross-sectional area A of the narrowest part of the space forming the downstream combustion gas flow path containing a large amount of oxygen with respect to the flow ratio “F1: F2” to the flow rate F2 of the upstream combustion gas containing a large amount of unburned gas.
1 and the cross-sectional area ratio “A2” of the cross-sectional area A2 of the narrowest part of the space forming the upstream combustion gas flow path containing a large amount of unburned gas.
1: A2 ″.

FIG. 6 is a graph showing the behavior of the concentration of carbon monoxide in the exhaust gas of the boiler section with respect to the furnace exit temperature of propane combustion and combustion of waste such as municipal waste, according to the embodiment of the present invention.

FIG. 7 shows a processing amount of about 6 t / h according to the embodiment of the present invention.
In a fully continuous inclined grate type double-flow furnace with a boiler,
The average temperature of the downstream combustion gas containing a large amount of oxygen is 70
When changed between 0 ° C and 900 ° C,
The carbon monoxide concentration in the exhaust gas of the boiler section is defined as the flow ratio “F1: F2” between the downstream combustion gas flow rate F1 containing a large amount of oxygen and the upstream combustion gas flow rate F2 containing a large amount of unburned gas. It is a graph shown.

FIG. 8 is a sectional view showing a grate furnace with a two-flow waste heat boiler according to another embodiment of the present invention.

FIG. 9 is a sectional view showing an embodiment of a shape of a barrier of an incinerator.

FIG. 10 is a sectional view taken along line AA of FIG. 9;

FIG. 11 is a sectional view showing an example of a conventional stoker furnace.

[Explanation of symbols]

 1: Combustion chamber 1a: Combustion chamber outlet 2: Hopper 3: Boiler 4: Supply pipe 5: Cavity block 6: Barrier 7: Incineration material 8: Combustion air 9: Combustion gas containing a large amount of unburned gas 10: Combustion gas containing much oxygen 11: Grate 12: Support wall 13: Secondary flue

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Michio Nagaseki 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Eiichi Shibuya 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Japan (56) References JP-A-3-233207 (JP, A) JP-A-3-5034 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23G 5 / 00 109 F23G 7/06

Claims (4)

(57) [Claims] 1. An incinerator provided with a combustion chamber provided with a grate that moves and burns an incinerator while moving the incinerator near an outlet of the combustion chamber with a combustion gas upstream of a moving direction of the incinerator. A barrier is provided for branching off the combustion gas on the downstream side in the moving direction, and the upstream combustion gas containing a large amount of unburned gas generated from the incinerated material on the upstream side in the moving direction and the oxygen is higher than the upstream combustion gas. The downstream combustion gas containing a large amount of, mainly flows from the upstream side and the downstream side respectively into the predetermined retention space through the space between the barrier and the combustion chamber furnace wall, the upstream combustion gas and the downstream side in the retention space A method of mixing combustion gas by causing combustion gas to collide with the combustion gas, wherein the downstream combustion gas flow rate F1 in the flow path of the downstream combustion gas between the barrier and the combustion chamber furnace wall; The ratio of the upstream combustion gas flow rate F2 in the flow path of the upstream combustion gas between the wall and the combustion chamber furnace wall, F1:
F2 = 8: 2 to 5.5: 4.5. 2. The ratio of the cross-sectional area A1 of the narrowest part of the space forming the flow path of the downstream combustion gas to the cross-sectional area A2 of the narrowest part of the space forming the flow path of the upstream combustion gas. To A1:
A2 = 8: 2 to 5.5: 4.5.
A method for mixing the combustion gases according to the above. 3. The shortest distance L1 of the narrowest part of the space forming the flow path of the downstream combustion gas and the shortest distance L2 of the narrowest part of the space forming the flow path of the upstream combustion gas are as follows: 3. The method for mixing combustion gases according to claim 1, wherein each of the lengths is 0.3 m or more. 4. The temperature at which the downstream combustion gas passes through the flow path and the temperature at which the upstream combustion gas passes through the flow path are each 830 ° C. or higher. 4. The method for mixing combustion gases according to 2 or 3.