JPH11347360A - Method for treating flue gas and treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make glycols absorb dioxines and water vapor simultaneously and efficiently remove the dioxines and the water vapor from flue gas by bringing the flue gas containing the dioxines and the water vapor into contact with specific glycols or activated glycols in a counter-flow fashion. SOLUTION: When flue gas is introduced onto inner bottom part 17 of an absorption column 10, a regenerated low-concentrated glycol solution flowing from a gas introduction and liquid flow part 35 on the internal upper stage treatment part 32 of a regeneration column 30 is supplied onto a gas and liquid contact shelf 13 on the internal lower stage treatment part 11 of the absorption column 10 using a pump 24. At the same time, a regenerated highly concentrated glycol solution flowing from the bottom part 37 of a lower stage treatment part 31 is likewise supplied onto a gas and liquid contact shelf 14 on an upper stage treatment part 12 using a pump 23. Next the combustion exhaust gas is brought into contact with the glycol solution in both treatment parts 11, 12 in a counterflow fashion. Thus dioxines and water vapor in the gas phase are absorbed into the glycol solution to be removed. In this case, a triethylene glycol or the like is used as the glycol solution and may be activated using hydrazine or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion method for purifying combustion exhaust gas containing dioxins and a large amount of steam discharged from combustion equipment such as boiler equipment and waste incineration equipment in order to suppress environmental pollution. The present invention relates to a method and an apparatus for treating exhaust gas.

[0002]

2. Description of the Related Art For example, flue gas discharged from a wet flue gas desulfurization facility or a waste incineration facility in a thermal power plant contains a large amount of water vapor and is released to the atmosphere unless any treatment is performed before the discharge. When it does so, it cools below the saturation temperature due to heat exchange with the low-temperature atmosphere and condenses, producing white smoke that causes problems such as infringing the right to sunlight. Further, the combustion exhaust gas discharged from the waste incineration equipment and the like includes nitrogen oxides (NOx), sulfur oxides (SOx), hydrogen chloride (H
Cl), polychlorobiphenyl (PCB), dust, fly ash, and other environmental pollutants, as well as polychlorobenzopara-tetratetradioxin, which has recently become a problem as a potent carcinogen. Dioxins.

Conventionally, methods for preventing the generation of white smoke from the combustion exhaust gas include a method of reheating the exhaust gas with an afterburner, a method of reheating the exhaust gas with a gas-gas heat exchanger, and a method of cooling the exhaust gas. A method of reheating by the above-mentioned method after reducing the saturation temperature by heating is known.

[0004]

However, in the above-mentioned method, since the consumption of the fuel for reheating by the afterburner is added, there is a problem that the operating cost (running cost) increases. Further, the combustion exhaust gas discharged from the wet flue gas desulfurization equipment, the waste incineration equipment, and the like,
Usually, it is at a temperature of about 55 ° C to 85 ° C and is in a steam-saturated state, so it shows remarkable corrosiveness due to the acid dew point, and reheats the exhaust gas with a heat exchanger as described above. In order to prevent the generation of white smoke, an extremely expensive material having corrosion resistance must be used for the heat exchanger and the like, which is problematic in terms of cost.

[0005] Further, as described above, in the method of cooling the exhaust gas to lower the saturation temperature and then reheating by the above-mentioned method, the consumption amount of the reheating fuel is higher than in the above-mentioned method. However, there is a problem that an exhaust gas cooling means such as a heat exchanger for cooling the exhaust gas or a re-cooling tower is separately required, and the initial equipment investment becomes expensive. On the other hand, dioxins contained in the combustion exhaust gas cannot be removed by the above-mentioned method, and there is no effective method other than using expensive activated carbon (eg, activated carbon bubble filter method) to remove the dioxins. Was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems relating to the treatment of flue gas, and it is an object of the present invention to effectively prevent the generation of white smoke from flue gas. Dioxins contained in flue gas can be effectively removed, and reheating operation,
Without using cooling operation and adsorption operation with activated carbon etc.
It is an object of the present invention to provide a method and an apparatus for treating flue gas, which are capable of minimizing operating costs and equipment costs.

[0007]

In order to achieve the above-mentioned object, a method for treating flue gas according to the present invention basically comprises converting a flue gas containing dioxins and a large amount of water vapor into triethylene glycol. Alternatively, glycols represented by tri-propylene glycol, or by contacting the glycols activated with a small amount of hydrazine or hydroquinone in countercurrent contact to simultaneously absorb the dioxins and water vapor in the glycols The dioxins and water vapor are removed from the combustion exhaust gas.

In a preferred embodiment of the method of the present invention, the dioxins and the glycols, which have absorbed a large amount of water vapor, are brought into countercurrent contact with air to reduce the partial pressure of water vapor in the gas phase in contact with the gas-liquid interface. Dispersing a large amount of water vapor absorbed in the glycols into the gas phase,
The glycols are regenerated. Further, in a further preferred embodiment, air containing water vapor diffused from the glycols is cooled by directly contacting with water, so that a part of the water vapor is condensed and separated, and a part of the water vapor is separated. The used air is used as combustion air.

In another preferred embodiment, the dioxins and the glycols that have absorbed a large amount of water vapor are indirectly heated under reduced pressure to increase the equilibrium water vapor pressure at the gas-liquid interface, thereby absorbing the dioxins and the glycols. The water vapor is diffused into the gas phase to regenerate the glycols. In another preferred embodiment of the method of the present invention, the dioxins and glycols having absorbed a large amount of water vapor are stored in an absorbent storage tank,
The regenerated glycols are stored in a regenerating liquid storage tank,
The operation of bringing the regenerated glycols in the regenerating liquid storage tank into countercurrent contact with the combustion exhaust gas and the operation of regenerating the glycols in the absorbing liquid storage tank are independently performed in a predetermined time zone. To be done.

On the other hand, a combustion exhaust gas treatment apparatus according to the present invention is an absorption tower through which combustion exhaust gas containing dioxins and a large amount of water vapor is flown, and this absorption tower is typically represented by triethylene glycol or tripropylene glycol. A first processing liquid supply means for supplying the glycols or the glycols activated with a small amount of hydrazine or hydroquinone, and a regeneration means for regenerating the dioxins and the glycols having absorbed a large amount of water vapor Wherein the combustion exhaust gas is brought into countercurrent contact with the glycols in the absorption tower, and the dioxins and the glycols which have absorbed a large amount of water vapor are recovered and regenerated by the regenerating means. And circulates through the processing liquid supply means.

[0011] In a preferred aspect of the apparatus of the present invention, the regenerating means includes a regenerator provided with the dioxins and glycols having absorbed a large amount of water vapor and with air supplied in countercurrent contact with the glycols. Reducing the partial pressure of water vapor in the gas phase in contact with the gas-liquid interface in the regeneration tower, thereby dispersing a large amount of water vapor absorbed in the glycols into the gas phase, In a further preferred embodiment, a condensing / separating means for condensing and separating a part of the steam by bringing the air containing the steam into direct contact with water and cooling the water is provided.

Preferably, the regenerating means comprises a regenerating tower to which the dioxins and glycols having absorbed a large amount of water vapor are supplied, a depressurizing means for reducing the pressure in the regenerator, dioxins and Heating means for indirectly heating the glycols having absorbed a large amount of water vapor in the regeneration tower, and increasing the equilibrium water vapor pressure at a gas-liquid interface in the regeneration tower depressurized by the decompression means. Thereby, the water vapor absorbed in the glycols is diffused into the gas phase to regenerate the glycols.

[0013] In another preferred embodiment of the apparatus of the present invention, between the absorption tower and the regeneration tower, an absorption liquid storage tank to which the dioxins and glycols having absorbed a large amount of water vapor are supplied in the absorption tower; A regeneration liquid storage tank to which the glycols regenerated from the regeneration tower are supplied, and an absorption liquid supply means for supplying the glycols in the absorption liquid storage tank to the regeneration tower are provided, An operation of supplying the regenerated glycols in the regenerating liquid storage tank to the absorption tower by the processing liquid supply means, and supplying the glycols flowing down in the absorption tower by the processing liquid recovery means to the absorption liquid storage tank The operation and the operation of supplying the glycols in the absorption liquid storage tank to the regeneration tower by the absorption liquid supply means can be performed independently in a predetermined time zone. It made.

In a preferred embodiment of the method and the apparatus for treating flue gas according to the present invention having such a configuration, the generation of white smoke from the flue gas is simply described as a physical latent heat transfer operation. , A chemical engineering water vapor absorption / regeneration operation, while simultaneously transferring dioxins to a liquid phase in which the supply of oxygen is shut off, and then catalyzing, reducing and deactivating the activated glycols. By utilizing the oxygen action, the dechlorination of dioxins and the deoxygenation catalytic cracking reaction are allowed to proceed at normal temperature and normal pressure. By doing so, white smoke is generated from the combustion exhaust gas. Can be effectively prevented, dioxins contained in the flue gas can be effectively removed, and reheating operation, cooling operation, and adsorption operation using activated carbon etc. can be avoided. So, it is possible to suppress the operating costs and equipment costs as much as possible.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a first embodiment of a combustion exhaust gas treatment apparatus according to the present invention. In the treatment apparatus 1 of the illustrated embodiment, the combustion exhaust gas containing dioxins and a large amount of steam discharged from a waste incinerator or the like is preferably treated with an aqueous treatment solution (scrubber) installed outside the figure by an alkali absorption tower (scrubber). Aqueous solution of various amines, mixed aqueous solution of alkali carbonate and alkali bicarbonate) to remove the harmful impurities contained therein, such as hydrogen chloride. At a temperature of ８５85 ° C., it is introduced into the bottom 17 of the absorption tower 10 provided in the processing apparatus 1.

The absorption tower 10 has a lower processing section 1
1. A demister 1 for removing water (mist) in exhaust gas near the top, in which an upper processing section 12 is continuously provided at an upper portion.
6 are provided. Gas-liquid contact shelves 13 and 14 each of which is formed by layering a net-like body are disposed around the center of the lower processing section 11 and the upper processing section 12, respectively. Between them, there is provided a gas insertion / liquid reservoir 15 that allows gas to pass but does not allow liquid to pass.

Accordingly, the flue gas introduced near the lower end of the absorption tower 10 rises inside the absorption tower 10 and is regenerated at the upper part of each of the lower processing section 11 and the upper processing section 12 as described later. A tri-ethylene glycol solution or a glycol solution activated by hydrazine or hydroquinone (hereinafter simply referred to as a glycol solution) supplied from the tower 30 via the pumps 24 and 23 of the first processing solution supply means and sprayed. And rises while being brought in countercurrent contact to the top.

On the other hand, the regeneration tower 30 is
Similarly, the lower processing unit 31 is provided at the lower part, and the upper processing unit 3 is provided at the upper part.
2, a demister 36 for removing the absorbent mist is provided near the top, and a mesh is layered around the center of the lower processing section 31 and the upper processing section 32, respectively. Liquid contact shelves 33 and 34 are provided, and between the lower processing section 11 and the upper processing section 12, a gas insertion / liquid storage section 35 that allows gas to pass but does not allow liquid to pass is provided. A heater (heat exchanger) 4 into which high-temperature steam as a heat medium is introduced from the outside between the bottom 37 of the regeneration tower 30 and the lower gas-liquid contact shelf 33.
The blower 25 supplies air (air for combustion in the waste incinerator or the like) from the outside between the heater 40 and the lower gas-liquid contact shelf 33. ing.

In the flue gas treatment apparatus 1 of the present embodiment having such a configuration, when the flue gas from the waste incinerator or the like is introduced above the bottom portion 17 of the absorption tower 10, The regeneration tower 3 by the pump 24
The low-concentration (about 80 to 85%) glycol liquid regenerated from the gas insertion and liquid storage section 35 of the upper processing section 32 is supplied to the gas-liquid contact shelf 13 of the lower processing section 11 in the absorption tower 10. It is supplied upward and sprayed, and the lower processing unit 31 of the regeneration tower 30 is pumped by the pump 23.
The regenerated high-concentration (about 99% or more) glycol liquid from the bottom portion 37 is supplied to the upper gas-liquid contact shelf 14 of the upper processing section 12 in the absorption tower 10 and sprayed.

For this reason, the flue gas introduced into the absorption tower 10 sequentially comes into countercurrent contact with the glycol liquid supplied to the lower processing section 11 and the upper processing section 12, thereby forming Water vapor and dioxins are absorbed by the glycol solution and are almost completely removed, and mist of the absorbing solution (glycol solution) accompanying the water is removed by the demister 16.

The combustion exhaust gas purified by removing the water vapor, dioxins, and mist of the absorption liquid in the absorption tower 10 almost completely is led out from the top of the absorption tower 10 and introduced into the aerosol collector 80. After the liquid and solid aerosols (particles smaller in diameter than the mist) entrained in the aerosol collector 80 are removed, the blower 26
, And is discharged from the chimney 90 to the outside as purified exhaust gas which is almost completely made harmless.

On the other hand, the lower processing section 1 of the absorption tower 10
In 1, the absorbing liquid (glycol liquid) that has absorbed water vapor and dioxins from the combustion exhaust gas and has flowed to the bottom 17 thereof is supplied to the upper processing section 32 in the regeneration tower 30 by the pump 22 of the second processing liquid supply means. Is supplied and sprayed above the upper gas-liquid contact shelf 34, and the upper processing section 12 of the absorption tower 10 absorbs water vapor and dioxins from the combustion exhaust gas to form the gas insertion and liquid storage section 15 Liquid (glycol solution) flowing down
Is supplied and sprayed above the lower gas-liquid contact shelf 33 of the lower processing section 31 in the regeneration tower 30 in the regeneration tower 30 by the pump 21 of the second processing liquid supply means, and when flowing down in the regeneration tower 30, The air supplied from the blower 25 to a portion below the lower gas-liquid contact shelf 33 comes into countercurrent contact with the rising air, and the partial pressure of water vapor in the gas phase in contact with the gas-liquid interface is reduced. It regenerates itself by absorbing absorbed water vapor and dioxin decomposition products (regeneration gas) such as phenol and hydrogen chloride generated in the regeneration step.

The glycol liquid regenerated in the upper processing section 32 of the regeneration tower 30 and retained in the gas insertion and liquid storage section 35 is supplied to the absorption tower 10 by the pump 24 of the first processing liquid supply means. It is supplied to the upper part of the lower gas-liquid contact shelf 13 of the lower processing part 11 and circulated, is provided for rough removal of water vapor and dioxins contained in the combustion exhaust gas, and is provided in the lower processing part 31 of the regeneration tower 30.
The glycol liquid regenerated in and flowing down to the bottom 37 is
The absorption tower 1 is pumped by the pump 23 of the first processing liquid supply means.
0, the upper gas-liquid contact shelf 1 of the upper processing unit 12
4 is supplied upward and circulated to be subjected to final finishing removal of water vapor and dioxins contained in the combustion exhaust gas.

On the other hand, air containing water vapor and a regeneration gas such as phenol, which is supplied from the blower 25 to a portion below the lower gas-liquid contact shelf 33 and is brought into countercurrent contact with the absorbent during the ascent, is entrained. After the absorbing liquid mist is removed by the demister 36 disposed near the top of the regeneration tower 30, the mist is introduced into the condenser 50 from the top of the regeneration tower 30. The condenser 50 controls the water balance of the entire treatment facility including the waste incinerator (not shown), the cyclone attached thereto, the alkali absorption tower, the absorption tower 10, the regeneration tower 30, the aerosol collector 80, and the like. It is provided for balancing and has a gas-liquid contact shelf 53 and a demister 56, and the regeneration tower 30
The air introduced into the condenser 50 from above is directly cooled by make-up water (an amount substantially equal to the amount of alkaline drainage) of the alkali absorption tower, which is supplied into the condenser 50 and sprayed, and a part of the steam contained therein Is condensed, separated and conditioned, and supplied to the waste incinerator as combustion air as combustion air. On the other hand, the make-up water obtained by condensing a part of the water vapor is supplied to the scrubber with a water amount required on the water balance of the alkali absorption tower (scrubber) installed outside FIG.

In this embodiment, the absorption tower 1
The main reason why the regeneration tower 30 and the regeneration tower 30 have an upper and lower two-stage structure is to balance the amount of air for regeneration of the glycol liquid with the amount of combustion air required for the waste incinerator. Further, in the present embodiment apparatus 1, the calorific value in the gas absorption step in the absorption tower 10 is an isothermal operation equal to the heat absorption in the gas dissipation step in the regeneration tower 30, but the molecules in the gas phase The driving force required for transfer to the liquid phase and for transfer of molecules in the liquid phase to the gas phase must be applied in the form of heat from outside the gas absorption-gas diffusion system. Therefore, in the apparatus 1 of the present embodiment, a heater 40 is provided in the regeneration tower 30, and the external force applied in the form of heat by the heater 40 is consumed in the form of a propulsive force necessary for moving molecules. You.

The operation and effect of the apparatus 1 of the present embodiment as described above will be described in more detail as follows. That is, in the absorption tower 10, the amount of gas absorption heat (different from the latent heat of condensation of water vapor) generated when the water vapor contained in the combustion exhaust gas is absorbed by the glycol liquid is given to the absorption liquid (glycol liquid). After the absorption liquid is supplied into the regeneration tower 30, after the supply of air from the outside and the partial pressure of water vapor in the gas phase decreases, the equilibrium vapor pressure of the water vapor indicated by the liquid phase and A difference from the partial pressure of the water vapor in the gas phase is generated, and when the water vapor moves from the liquid phase to the gas phase using the pressure difference as a driving force, an equal amount of heat is dissipated by the gas from the glycol liquid (gas latent heat And different).

Accordingly, the processing apparatus 1 does not require a cooler or a heater, and promotes the difference between the equilibrium vapor pressure of the gas component in the gas phase and the equilibrium vapor pressure of the gas component in the liquid phase during the isothermal operation. As a force, gas absorption and gas emission will be repeated. Therefore, the work given to the apparatus 1 from the outside is only the supply of air to the regeneration tower 30.

In this way, the water vapor in the combustion exhaust gas supplied to the absorption tower 10 is continuously absorbed by the glycol liquid, and the air is supplied in the regeneration tower 30 without being heated or cooled. Received and recovered as steam again, and supplied to the waste incinerator as combustion air together with the air. The accompanying saturated steam reacts with unburned carbon monoxide and soot (fixed oxygen) in the furnace. As a result, a water gas reaction occurs to generate hydrogen and carbon dioxide, so that the method of recovering latent heat of two birds per stone, which promotes complete combustion in the furnace, has been applied as a method of removing water vapor from exhaust gas. By the operation as described above,
Since 50% to 100% of water vapor in the combustion exhaust gas is removed at normal temperature in the absorption tower 10, for example, when the temperature is 0 °
Even in the winter season of C, even if the exhaust gas is radiated from the chimney 90 to the outside without reheating, white smoke is not generated.

FIG. 4 shows the equilibrium vapor pressure of an activated triethylene glycol solution, which is a glycol used in the present embodiment. For example, at 40 ° C. (104 ° F.) (triethylene glycol 99% + 1% of water vapor) is about 2 mmHg. That is, the water vapor concentration in the gas phase (in the combustion exhaust gas) in contact with the glycol liquid is (2/760) × 100% to (4/760) × 100%.
At this concentration, it is shown that white smoke is generated by water vapor only when the atmospheric temperature falls to a range from -10 ° C to -1 ° C.

Therefore, the flue gas washed with the activated triethylene glycol solution at 40 ° C. (104 ° F.) can be used in normal winter season without performing the relative saturation lowering operation by reheating as in the conventional apparatus. At temperatures, the generation of white smoke is reliably suppressed.

On the other hand, the glycols themselves are strong solvents, and have the property of mutually dissolving all organic compounds except for petroleum ether, so that the biphenyl chloride ( For PCBs and dioxins such as polychlorinated dibenzoparadioxin (dioxin) and polychlorinated dibenzofuran (furan), about 1320 (kg / m.
³ solution) / (kg / m ³ gas), but when activating the glycols with hydroquinones or hydrazines of about 100 to 200 wt.ppm, oxygen In the liquid phase in which is blocked, at normal temperature and normal pressure, a dechlorination reaction easily occurs according to the following chemical formula, and hydrazines cause a deoxygenation decomposition reaction, so that dioxins disappear, and hydrogen chloride and phenols disappear. Is produced, but only a very small amount is dissolved in the glycols. Most of the generated hydrogen chloride and phenols are supplied to the waste incinerator together with the air used in the regeneration tower 30 and completely burned, and the hydrogen chloride is treated in the alkali absorption tower downstream of the waste incinerator. Will be done.

[0032]

Embedded image

[0033]

Embedded image

[0034]

Embedded image

[0035]

Embedded image

The chemical formula (1) is obtained under the condition that the dioxin (polychlorinated dibenzoparadioxin) gas-absorbed by the glycols is in a liquid phase in a reducing atmosphere in which contact with oxygen is cut off at normal temperature and normal pressure. Dechlorinated,
It shows a detoxifying reaction (dechlorination reaction). The chemical formula (2) indicates a reaction in which benzodioxin generated according to the chemical formula (1) is decomposed to generate phenol and nitrogen gas (catalytic decomposition reaction).

The chemical formula (3) indicates that the total number of moles of the gas components in which the chlorine gas generated by the chemical formulas (1) and (4) is dissolved in the liquid phase completely cut off from the presence of oxygen. 100 indicates that the process proceeds to the right side under the condition that the dissolved oxygen concentration is 5 or less. This can be understood from the fact that the Dacon reaction, which is a gas phase reaction, proceeds to the left side of the chemical formula (3) at an oxygen partial pressure of 0.05 atm. In the Dacon reaction, copper chloride is used as an oxidation catalyst. In the present embodiment, hydroquinone is used as an oxidation-reduction catalyst, and hydroquinone acts on the chemical formulas (1) and (4) as an oxygen carrier. When the chemical formulas (1) to (4) are arranged, it is understood that dioxins are decomposed by the following chemical formula (5).

[0038]

Embedded image

The right side of the chemical formula (5) corresponds to the regeneration tower 3
The partial pressure of each component at the gas-liquid interface is reduced by the air supplied to zero, and the components are radiated into the air. In this embodiment, the consumption of hydrazine for activating glycols is determined by the amount of dioxins (about 1
0 ng / Nm ³ ) of 16/290, that is, about 1/1
Therefore, the consumption of hydrazine for an exhaust gas of 20000 Nm ³ / h is about 0.2 mg / h, that is, about 1.75 g per year.

Originally, hydrazine itself was not very effective in removing dioxins in exhaust gas.
When the glycols having a high solubility for organic polychlorides such as dioxins are activated with hydrazines or hydroquinones and then the glycols are brought into contact with combustion exhaust gas, the dioxins in the exhaust gas are Moves to the liquid phase and is completely shut off from oxygen in the exhaust gas. Next, the dechlorination reaction (1) occurs by the action of an oxidation catalyst (redox catalyst).
The catalytic cracking reaction (2) occurs by the action of the oxygen scavenger.

In this way, the dioxins in the exhaust gas are completely decomposed into phenol, nitrogen, hydrogen chloride and oxygen as shown by the chemical formula (5). Emitted into the air supplied to the tower 30 and enters the waste incinerator. In the furnace, phenol is decomposed into carbon dioxide gas and water vapor by the following chemical formula (6), and the remaining nitrogen, oxygen and hydrogen chloride are mixed into the combustion exhaust gas and guided to the alkali absorption tower to be removed. .

[0042]

Embedded image

FIG. 2 is a schematic configuration diagram showing a second embodiment of the apparatus for treating flue gas according to the present invention. Also in the processing apparatus 2 of the illustrated embodiment, in addition to the absorption tower 10 and the pumps 21, 22, 23, and 24 similar to those of the first embodiment, not shown but similar to the first embodiment shown in FIG. A regeneration tower 30 ′ which is provided with an aerosol collector 80 and a chimney 90, and has the same basic components as those of the first embodiment, but is configured not to supply air from the outside. An indirect condenser 55 and a condensing / separating tower 57 connected to the top of the regenerator 30 ′, and furthermore, the steam condensed in the regenerator 30 ′ from the absorbing liquid (glycol solution). And a jet condenser 61, a tank 63, a blower 65, and a cooler 67 which are evacuated through the condensing / separating column 57 to reduce the pressure inside the regenerating column 30 'to a vacuum.

Therefore, in the processing apparatus 2 of the second embodiment, in the regeneration tower 30 ′, the dioxin and the glycol liquid having absorbed a large amount of water vapor are reduced in pressure by vacuum suction by the jet condenser 61. Indirectly heated by the heater 40, the equilibrium water vapor pressure at the gas-liquid interface is raised, whereby the water vapor absorbed in the glycol liquid is diffused into the gas phase, and the glycol liquid is regenerated. Is done. In addition, a part of the water vapor diffused into the gas phase from the glycol liquid is indirectly cooled by the indirect condenser 55 and condensed and separated in the condensing / separation column 57, and the remaining water vapor is also condensed by the jet condenser 61 It will be condensed and separated.

FIG. 3 is a schematic configuration diagram showing a third embodiment of the apparatus for treating combustion exhaust gas according to the present invention. In the processing apparatus 3 of the illustrated embodiment, a relatively small absorption tower 10 ′ having a single-stage configuration provided with a gas-liquid contact shelf 14 and a demister 16 similar to those of the second embodiment, In addition to a pump 22 'as a pump and a pump 23' as a processing liquid supply means, not shown, an aerosol collector 80 and a chimney 90 are provided similarly to the first embodiment shown in FIG. Although the basic configuration is substantially the same as that of the above, a relatively small regenerator 130 is provided. Further, in the regenerator 130, the vapor emanating from the absorbing solution (glycol solution) is vacuum-evacuated to form the regenerator. Jet condenser 6 which decompresses 130 and makes it vacuum
1, a tank 63, a blower 65, and a cooler 67 are provided.

In addition to the above, in the processing apparatus 3 of the present embodiment, the dioxins and a large amount of water vapor are absorbed between the absorption tower 10 ′ and the regeneration tower 130 in the absorption tower 10 ′. An absorption liquid storage tank 71 to which the glycol liquid is supplied by the processing liquid recovery pump 22 ′ and a regenerating liquid storage tank 72 to which the glycol liquid regenerated from the regenerator 130 are supplied are provided. , The glycol solution in the absorbing solution storage tank 71 and the regeneration tower 1
A pump 28 is provided as an absorbing liquid supply means for supplying the regenerated glycol liquid in the regenerating liquid storage tank 72 to the absorption tower 10 'by the processing liquid supply pump 23'. Processing liquid recovery pump 2
An operation of supplying the glycol liquid flowing down to the bottom portion 17 of the absorption tower 10 ′ to the absorption liquid storage tank 71 by 2 ′; and an operation of the absorption liquid storage tank 71 by the absorption liquid supply pump 28.
And the operation of supplying the glycol solution to the regeneration tower 130 can be performed independently in a predetermined time zone.

Therefore, in the processing apparatus 3 of the present embodiment, the continuous processing is not performed as in the processing apparatuses 1 and 2 of the first and second embodiments described above, and for example, when the waste incinerator is operated. In the daytime, the treatment liquid pump 2
By operating 2 ′ and 23 ′, the regenerated glycol liquid stored in the regenerating liquid storage tank 72 is rejected by the absorption tower 10 ′.
To continuously remove dioxins and water vapor in the combustion exhaust gas by gas absorption, and supply and store a used absorbent (glycol solution) in the absorbent storage tank 71 so as to remove waste. When the incinerator is not in operation (at night when the electricity rate is low), the absorption liquid supply pump 28 is operated to supply the glycol liquid in the absorption liquid storage tank 71 to the regeneration tower 130 and to perform the above operation. The regenerated glycol solution is stored in the regenerated liquid storage tank 72 so as to be prepared for the next day.

By doing so, it is possible to keep running costs such as power charges low. In order to understand the above description, Table 1 shows the purification performance of the processing apparatus 1 of the first embodiment.

[0049]

[Table 1]

[0050]

As will be understood from the above description, according to the method and apparatus of the present invention, it is possible to effectively prevent the generation of white smoke from flue gas and to reduce dioxins contained in the flue gas. It can be removed effectively, and further, since it is not necessary to use a reheating operation, a cooling operation, and an adsorption operation using activated carbon or the like, the operation cost and the equipment cost can be reduced as much as possible.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a combustion exhaust gas treatment apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the apparatus for treating combustion exhaust gas according to the present invention.

FIG. 3 is a schematic configuration diagram showing a third embodiment of the apparatus for treating combustion exhaust gas according to the present invention.

FIG. 4 is a graph showing a vapor pressure curve of triethylene glycol.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Combustion exhaust gas processing apparatus (1st embodiment) 2 Combustion exhaust gas treatment apparatus (2nd embodiment) 3 Combustion exhaust gas treatment apparatus (3rd embodiment) 10 Absorption tower 21-24 Pump (processing liquid supply means) 22 'Pump (treatment liquid recovery means) 23' Pump (treatment liquid supply means) 30 Regeneration tower (regeneration means) 50 Condenser (condensation separation means) 61 Jet condenser (decompression means) 71 Absorbing liquid storage tank 72 Regenerated liquid storage tank

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B01D 53/77 ZAB

Claims (10)

[Claims] 1. A method of producing a combustion exhaust gas containing dioxins and a large amount of water vapor by using glycols represented by tri-ethylene glycol or tri-propylene glycol, or the glycols activated by a small amount of hydrazine or hydroquinone. A method for treating combustion exhaust gas wherein the dioxins and water vapor are simultaneously absorbed by the glycols by bringing the glycols into countercurrent contact to remove the dioxins and water vapor from the combustion exhaust gas. 2. The dioxins and the glycols, which have absorbed a large amount of water vapor, are brought into countercurrent contact with air to reduce the partial pressure of water vapor in the gas phase in contact with the gas-liquid interface. The method according to claim 1, wherein the glycols are regenerated by dispersing a large amount of absorbed water vapor into a gas phase. 3. An air containing water vapor released from the glycols is brought into direct contact with water and cooled,
The method for treating combustion exhaust gas according to claim 2, wherein a part of the steam is condensed and separated, and the air from which a part of the steam is separated is used as combustion air. 4. The dioxins and the glycols, which have absorbed a large amount of water vapor, are indirectly heated under reduced pressure to raise the equilibrium water vapor pressure at the gas-liquid interface, whereby the water vapor absorbed in the glycols is increased. The method for treating combustion exhaust gas according to claim 1, wherein the glycols are regenerated by dispersing the glycols in a gas phase. 5. The dioxins and glycols that have absorbed a large amount of water vapor are stored in an absorption liquid storage tank, and the regenerated glycols are stored in a regeneration liquid storage tank. The operation of bringing the regenerated glycols into countercurrent contact with the combustion exhaust gas and the operation of regenerating the glycols in the absorbent storage tank are performed independently in a predetermined time zone. 2 or 4
A method for treating combustion exhaust gas according to item 1. 6. An absorption tower (10) through which a combustion exhaust gas containing dioxins and a large amount of steam is flown, and tri-ethylene glycol or tri-ethylene glycol is added to the absorption tower (10).
A first processing liquid supply means (23, 24) for supplying glycols represented by propylene glycol or the glycols activated with a small amount of hydrazine or hydroquinone, and the dioxins and a large amount of steam. Regenerating means (30) for regenerating the absorbed glycols, wherein the combustion exhaust gas is supplied to the absorption tower (1).
In 0), the glycols are brought into countercurrent contact with the glycols,
Treatment of combustion exhaust gas wherein the dioxins and the glycols having absorbed a large amount of water vapor are collected and regenerated by the regenerating means (30) and circulated through the second processing liquid supply means (21, 22). apparatus. 7. The regeneration means has a regeneration tower (30) to which the dioxins and glycols that have absorbed a large amount of water vapor are supplied, and air that is brought into countercurrent contact with the glycols is supplied. In the regeneration tower (30), the partial pressure of water vapor in the gas phase in contact with the gas-liquid interface is reduced, so that a large amount of water vapor absorbed in the glycols is diffused into the gas phase to remove the glycols The flue gas treatment apparatus according to claim 6, wherein the combustion exhaust gas is regenerated. 8. A condensing / separating means (50) for condensing and separating a part of the steam by bringing the air containing the steam into direct contact with water to cool the water. Item 8. A treatment device for a combustion exhaust gas according to Item 7. 9. The regeneration means comprises: a regeneration tower (30 ') to which the dioxins and glycols having absorbed a large amount of water vapor are supplied; and a pressure reducing means for reducing the pressure inside the regeneration tower (30'). (61) and the dioxins and the glycols that have absorbed a large amount of water vapor in the regeneration tower (3).
0 '), a heating means (40) for indirect heating within the regeneration tower (30'), which is decompressed by the decompression means (61), to raise the equilibrium water vapor pressure at the gas-liquid interface. The apparatus according to claim 6, wherein the water vapor absorbed in the glycols is diffused into a gaseous phase to regenerate the glycols. . 10. An absorption tower (10 ′) and a regeneration tower (130).
Between the absorption tower (10 ′) and the absorption liquid storage tank (71) to which the dioxins and glycols having absorbed a large amount of water vapor are supplied, and the regeneration tower (130). A regenerating liquid storage tank (72) to which glycols are supplied; and an absorbing liquid supply means (28) for supplying the glycols in the absorbing liquid storage tank (71) to the regenerator (130). An operation of supplying the regenerated glycols in the regenerating liquid storage tank (72) to the absorption tower (10 ') by a processing liquid supply means (23') and a processing liquid collecting means (22 ') Supplying the glycols flowing down in the absorption tower (10 ') to the absorption liquid storage tank (71) by the method described above, and the glycol in the absorption liquid storage tank (71) by the absorption liquid supply means (28). The regeneration tower Operations and supplies to 130),
7. The apparatus for treating flue gas according to claim 6, wherein the processing can be performed independently in a predetermined time zone.