JP3802308B2 - Dioxins separation and removal equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dioxins separation / removal device that separates and removes dioxins generated by combustion of chlorine compounds and the like from combustion exhaust gas.
[0002]
[Prior art]
Dioxins are extremely toxic substances and are chemically stable, so environmental pollution caused by dioxins has become a major social problem.
[0003]
The largest source of dioxins is said to be an incinerator for municipal waste and other waste. For this reason, the structural standards and maintenance standards for facilities to reduce dioxins emitted from waste incineration facilities have been strengthened from the legal aspect. According to this, the combustion temperature in the combustion chamber is set to 800 ° C. or more, and the residence time is set to 2 seconds or more. In addition, it is obliged to install an exhaust gas treatment device with an advanced dust collector.
[0004]
[Problems to be solved by the invention]
Dioxins, which are a problem in incineration of municipal waste and other waste, are generated with combustion of chlorine compounds and the like. As for the decomposition temperature of dioxins, about 700 ° C. or more is common, and from this viewpoint, the combustion temperature in the combustion chamber is established to be 800 ° C. or more.
[0005]
However, it has been reported in part that a considerably large amount of dioxins is generated even at high temperature combustion of 800 ° C. or higher. In fact, this has been confirmed by investigations by the present inventors. For this reason, the importance of the exhaust gas treatment apparatus has become very large. As the current exhaust gas treatment technology, a method of adsorbing dioxins on activated carbon fine powder and removing it with a bag filter is common, but it is necessary to control the temperature of the exhaust gas appropriately with the bag filter. The complexity and size of the processing apparatus become a very large economic burden for the introducer.
[0006]
An object of the present invention is to provide a dioxins separation / removal apparatus that can easily separate and remove dioxins generated by combustion of chlorine compounds and the like from combustion exhaust gas with high efficiency.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present inventors have studied in detail the generation mechanism of dioxins in combustion of chlorine compounds and the like. As a result, the following was found.
[0008]
(1) Comparison of, for example, about 20 ng-TEQ / m ³ N even under conditions of combusted PVC, which has been considered to have no problem in the generation of dioxins, combustion temperature of 800 ° C., reaction time of 30 seconds, and excess oxygen Dioxins are found in exhaust gas at high concentrations.
[0009]
(2) This is due to the presence of floating C and C compounds in the exhaust gas. That is, dioxins in high-temperature combustion at 800 ° C. are mainly generated in the boundary layer around floating C and C compounds. More specifically, even in high-temperature combustion at 800 ° C., the generation rate is faster than the decomposition rate in the boundary layer around the floating C and C compounds, and the dioxins around the floating C and C compounds seem to be difficult to decompose. Become. Moreover, those dioxins become very easy to adsorb | suck to floating C type | system | group substance with the fall of temperature.
[0010]
(3) The floating C and C compounds in the exhaust gas prevent the decomposition of dioxins, but on the other hand, the generated dioxins are easily separated and removed. That is, dioxins alone are extremely difficult to separate and remove from the exhaust gas, but if they are present in the exhaust gas in the state of being adsorbed by the floating C and C compounds, the floating C and C compounds are removed from the exhaust gas. By separating and removing, it becomes possible to separate and remove from the exhaust gas relatively easily.
[0011]
(4) Regardless of whether or not dioxins are attached, separation and removal of floating C and C compounds are much easier than separation and removal of dioxins alone. For example, floating C and C compounds to which dioxins adhere are removed. The so-called water injection in which the flue gas containing the gas is injected and passed through the water is adsorbed and separated into the water together with dioxins adhering to the floating C and C compounds in the flue gas, resulting in combustion. Dioxins in the exhaust gas are separated and removed from the combustion exhaust gas with high efficiency.
[0012]
The dioxin separation and removal apparatus of the present invention has been completed based on such knowledge, and when the combustion exhaust gas contains floating C and C compound, the floating C and C compound is separated and removed from the combustion exhaust gas. Accordingly, dioxins adhering to the floating C and C compounds Ri greatest feature there in that separated off from the flue gas, and more specifically, while circulating onto the flue gas from the bottom, while the flue gas A processing tower main body that circulates an adsorbing liquid for adsorbing floating C and C compounds contained from top to bottom, and a plurality of stages in the processing tower main body, and the adsorbing liquid introduced into the processing tower main body A number of gas liquids are provided in each stage so that the combustion exhaust gas introduced into the main body of the treatment tower is bubbled into the stagnant liquid of each stage and passed from the bottom to the top while being temporarily retained in each stage. Through hole Is obtained by the leakage shelf type and a plurality of leakage shelves kicked excellent separation efficiency of dioxins, and excellent economy. The C compound is typically HC.
[0013]
(Delete)
[0014]
(Delete)
[0015]
(Delete)
[0016]
In the leaky shelf type separation / removal device, the adsorbed liquid that has passed through the processing tower main body is passed through a filter to separate and remove floating C and C compounds in the adsorbing liquid from the adsorbing liquid, and the adsorbed liquid is then removed from the processing tower main body By returning to, it becomes possible to circulate and use the adsorbed liquid, and the suspended C and C compounds separated and removed from the adsorbed liquid can be easily processed.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a dioxins separation / removal device according to an embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of a leakage shelf used in the separation / removal device.
[0018]
The dioxin separation / removal device shown in FIG. 1 is a leaky shelf type that is suitably used for separation / removal of dioxins generated in incinerators (high-temperature combustion at 800 ° C. or higher) of municipal waste and other waste. It is a separation and removal device.
[0019]
This separation / removal apparatus includes a vertical gas processing tower 10 for treating combustion exhaust gas G discharged from an incinerator with adsorbed water W, a gas cooler 20 provided on the gas inlet side of the gas processing tower 10, and a gas A suction blower 30 provided on the outlet side, a liquid feed pump 40 provided on the adsorbed water inlet side of the gas processing tower 10, and a liquid processing unit 50 provided on the adsorbed water outlet side are provided.
[0020]
The gas processing tower 10 includes a cylindrical processing tower main body 11 and leak shelves 12, 12... Horizontally arranged in a plurality of stages inside the processing tower main body 11. A header 13 for introducing combustion exhaust gas into the processing tower main body 11 is provided below the lowermost leakage shelf 12 below the processing tower main body 11. On the other hand, an introduction pipe 14 for spraying treated water as an adsorbed liquid into the processing tower main body 11 is provided above the uppermost leakage shelf 12 in the upper part of the processing tower main body 11.
[0021]
The combustion exhaust gas G introduced into the lower portion of the processing tower main body 11 through the header 13 circulates in the processing tower main body 11 from the bottom to the top while sequentially passing through the leakage shelves 12, 12,. Then, it is discharged out of the processing tower body 11 from the top. On the other hand, the adsorbed water W introduced into the upper portion of the processing tower main body 11 by the introduction pipe 14 passes through the leakage shelves 12, 12... 11 circulates from the top to the bottom, and is discharged out of the processing tower body 11 from the bottom.
[0022]
The leakage shelves 12, 12,... Allow the adsorbed water W introduced into the processing tower main body 11 to pass downward while being temporarily retained above. Further, the combustion exhaust gas G introduced into the processing tower main body 11 is made into a bubble state and injected into the staying layer of the adsorbed water W from below and passed upward. As shown in FIG. 2, a large number of gas-liquid passage holes 12a, 12a,... Are dispersed at a predetermined pitch in each leak shelf 12 for the passage of gas-liquid countercurrent with water injection of the combustion exhaust gas G. Is provided. Each gas-liquid passage hole 12a is a through-hole in the vertical direction, and the taper hole whose inner diameter gradually decreases from the bottom to the top is said to have a large effect of promoting the bubbling of the combustion exhaust gas G.
[0023]
The gas cooler 20 rapidly cools the high-temperature combustion exhaust gas G discharged from municipal waste or other waste incinerators to about 180 ° C. before introducing it into the gas processing tower 10. The liquid processing unit 50 includes a tank 51 that stores the adsorbed water W discharged from the gas processing tower 10 and a filter 52. The filter 52 adsorbs the floating C in the adsorbed water W and the compound (HC, etc.) by passing the adsorbed water W introduced into the tank 51.
[0024]
Next, the operation method and function of the dioxin separation and removal apparatus shown in FIG. 1 will be described.
[0025]
During operation, the suction blower 30 and the liquid feed pump 40 operate. When the suction blower 30 is operated, the combustion exhaust gas G of, for example, 800 ° C. discharged from the municipal waste incinerator (high-temperature combustion of 800 ° C. or higher) is rapidly cooled to, for example, about 180 ° C. by the gas cooler 20, and then the gas It introduce | transduces into the processing tower 10 from the lower part.
[0026]
In the incineration treatment of municipal waste and other waste, it is inevitable that floating C and C compounds (HC, etc.) coexist. As a result, dioxins are generated even at high temperature combustion of 800 ° C. or higher, but most of the dioxins are present in a state of adhering to floating C and C compounds (HC, etc.).
[0027]
The cooled combustion exhaust gas G introduced from the lower part into the gas processing tower 10 passes through the leakage shelves 12, 12,. On the other hand, when the liquid feed pump 40 operates, the adsorbed water W is introduced into the gas processing tower 10 from above. The adsorbed water W introduced from the upper part into the gas processing tower 10 passes through the leakage shelves 12, 12,.
[0028]
In the leakage shelves 12 at each stage, the adsorbed water W stays at a predetermined layer thickness T thereon. The stagnant water flows downward through a large number of gas-liquid passage holes 12a, 12a,..., But the amount of adsorbed water W equal to the outflow amount is supplied from above, so the layer thickness T of the stagnant water is kept constant. Is done. Combustion exhaust gas G is injected into the staying water from below through a large number of gas-liquid passage holes 12a, 12a,. The injected gas becomes fine bubbles. By this water injection, floating C and C compounds (HC, etc.) in the injected gas are adsorbed by the stagnant water. The stagnant water that has adsorbed the floating C and the C compound (HC, etc.) sequentially flows downward from a large number of gas-liquid passage holes 12a, 12a.
[0029]
The combustion exhaust gas G introduced into the gas processing tower 10 passes through the leakage shelves 12, 12... In the gas processing tower 10 in order from the bottom to the top, thereby floating C and C compounds (HC, etc.) in the gas. ) Are gradually reduced in the form of being transferred into the adsorbed water W, and finally the suspended C and C compound (HC, etc.) are hardly included, and the suction blower 30 is removed from the top of the gas treatment tower 10. After that, it is released into the atmosphere.
[0030]
On the other hand, the adsorbed water W introduced into the gas treatment tower 10 passes through the leakage shelves 12, 12,... In the gas treatment tower 10 in order from the top to the bottom, thereby floating C and C in the combustion exhaust gas G. A compound (HC or the like) is adsorbed stepwise to increase its amount, and finally discharged from the lowermost part of the gas processing tower 10 to the liquid processing unit 50.
[0031]
In the liquid processing unit 50, suspended C and C compounds (HC, etc.) in the adsorbed water W are adsorbed and removed by the filter 52. Thereby, the adsorbed water W is regenerated into clean water and returned to the gas processing tower 10 by the liquid feed pump 40. Thereby, the adsorbed water W is circulated and used. The filter 52 that has adsorbed the floating C and C compound (HC, etc.) is treated by high-temperature combustion in an incinerator.
[0032]
In addition, when elution of dioxins is observed even in a very small amount in the adsorbed water W collected in the tank 51, the adsorbed water W is brought into contact with the aerated gas through a porous plate of another small device. The dioxins in the adsorbed water W can be effectively removed by removing the dioxins in the gas using an activated carbon adsorber after the dioxins in the adsorbed water W are transferred to the gas side. .
[0033]
As described above, incineration of municipal waste and other wastes cannot avoid the coexistence of floating C and C compounds (HC, etc.), and as a result, dioxins are generated even at high-temperature combustion at 800 ° C. or higher. However, most of the dioxins are present in a state of adhering to floating C and C compounds (HC, etc.). The dioxins separation and removal apparatus shown in FIG. 1 separates and removes most of the dioxins from the combustion exhaust gas G by efficiently separating and removing floating C and C compounds (HC, etc.) in the combustion exhaust gas G. To do. Experiments have confirmed that the removal rate is 95% or more.
[0034]
The number of stages of the leakage shelves 12, 12... Is better from the viewpoint of separation and removal of floating C and C compounds (HC, etc.), but if too much, the cost increase of the gas treatment tower 10 becomes a problem. Ten stages are preferred.
[0035]
From the point of separation and removal of floating C and C compounds (HC, etc.), the gas-liquid passage holes 12a, 12a,. However, if it is fine, the flowability of the adsorbed water W deteriorates, and if it is too large, an increase in processing cost becomes a problem. In this respect, the hole diameter D is preferably 3 to 10 mm, and the number is preferably 0.3 to 0.6 in terms of the ratio of the total hole area to the shelf area.
[0036]
Further, the hole diameter D and the pitch P of the gas-liquid passage holes 12a, 12a,... Affect the layer thickness T of the adsorbed water W retained on the leak shelf 12, so that a predetermined layer thickness T can be obtained. Based on the amount of adsorbed water W introduced, it is selected within the above range. The layer thickness T of the adsorbed water W is preferably 30 to 50 mm. If this layer thickness T is too small, the adsorptivity of floating C and C compounds (HC, etc.) is reduced, and if it is too large, the power of the exhaust gas exhaust fan (suction blower 30) is increased, resulting in a reduction in economic efficiency.
[0037]
Moreover, as the filter 52, a commercially available paper filter, a nonwoven fabric filter, etc. can be used.
[0038]
【The invention's effect】
As described above, the dioxin separation / removal device of the present invention circulates combustion exhaust gas from the bottom to the top, while adsorbing liquid for adsorbing floating C and C compounds contained in the combustion exhaust gas from above. The processing tower main body to be circulated downward, and arranged in a plurality of stages in the processing tower main body, the adsorbed liquid introduced into the processing tower main body is temporarily retained in each stage and introduced into the processing tower main body. A leakage shelf type comprising a plurality of leakage shelves each provided with a large number of gas-liquid passage holes so that the combustion exhaust gas is bubbled into the stagnant liquid of each step and passed from the bottom to the top. As a result, dioxins generated by combustion of chlorine compounds and the like can be easily separated and removed from the combustion exhaust gas with high efficiency. As a result, the release of dioxins into the atmosphere is suppressed, and it has a great effect in preventing environmental pollution caused by dioxins. For example, exhaust gas treatment attached to incinerators such as municipal waste and industrial waste From the point of reducing the price of the equipment, reducing the burden on the introducer and facilitating its introduction, it is very effective in preventing environmental pollution.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a dioxins separation and removal apparatus according to an embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of a leakage shelf used in the separation / removal apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Gas treatment tower 11 Treatment tower main body 12 Leakage shelf 12a Gas-liquid passage hole 20 Gas cooler 30 Suction blower 40 Liquid feed pump 50 Liquid treatment part 52 Filter

Claims (3)

A dioxin separation / removal device for separating and removing dioxins generated by combustion of chlorine compounds from combustion exhaust gas,
A treatment tower main body that circulates the combustion exhaust gas from the bottom to the top while circulating an adsorbing liquid for adsorbing the floating C and C compounds contained in the combustion exhaust gas, from the top to the bottom,
Arranged in multiple stages in the processing tower body, the adsorbed liquid introduced into the processing tower body is temporarily retained in each stage, and the combustion exhaust gas introduced into the processing tower body is retained in each stage. A dioxin separation / removal device comprising: a plurality of leak shelves each having a plurality of gas-liquid passage holes so as to be bubbled therein and passed from the bottom to the top. Through an adsorption liquid that has passed through the processing tower body filter according to claim 1, characterized in that it comprises a filtering means of the adsorption solution is separated off from the adsorption solution stray C and C compounds in the adsorption solution Dioxin separation and removal equipment. The apparatus for separating and removing dioxins according to claim 2 , further comprising a means for circulating the adsorbed liquid that returns the adsorbed liquid that has passed through the filtering means into the main body of the processing tower.

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