JPH02207822A - Treatment of incinerator waste gas - Google Patents

Abstract

PURPOSE:To treat the waste gas by sprinkling a liq. chemical contg. a fine alkaline particle and gaseous ammonia into a reaction tower through which the waste gas passes, allowing the formed ammonium chloride to react with the unreacted fine alkaline particle, allowing the regenerated ammonia to react with nitrogen oxides and decomposing the nitrogen oxides into nitrogen and water. CONSTITUTION:The liq. chemical contg. an alkali and gaseous ammonia are supplied into a gas 37 as a processing agent 36, provided with centrifugal force, moved in the radial direction, allowed to collide with a crushing rod 11, pulverized and injected toward the periphery. The formed ammonium chloride alphais introduced into the agglomerate of the fine alkaline particle gamma, and sublimed to make the agglomerate porous. The sublimed ammonium chloride alpha is solidified, adsorbed and fixed on a bag filter 27. The solid reacts with the unreacted fine alkaline particle gamma, and ammonia is regenerated. When the treated waste gas 38 passes through a catalyst bed 30 heated by a steam pipe heater 31, the nitrogen oxides and ammonia in the gas are subjected to a catalytic reaction and decomposed into nitrogen and water.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for treating incinerator exhaust gas.

BACKGROUND OF THE INVENTION Conventionally, as a method for treating incinerator exhaust gas, for example, Ca
Alkaline component fine particles such as (OH)Q are dispersed into the exhaust gas in the reaction tower, and the alkali component fine particles are reacted with sulfur oxides and hydrogen chloride in the exhaust gas to form Ca5O and CaCj.
2, there is a method of absorbing and fixing these and removing them from the exhaust gas.Problems to be Solved by the InventionHowever, according to the above-mentioned conventional configuration, alkaline component fine particles combine and aggregate, and this aggregate The surrounding area is Ca
Because of the reaction products such as CJz, the reaction area of the alkali component fine particles becomes narrower and the unreacted alkali component fine particles are trapped inside the aggregates, causing the alkali to react with the sulfur oxides and hydrogen chloride in the exhaust gas. There is a problem in that the reaction efficiency of the component fine particles becomes low, and the alkaline component fine particles must be dispersed into the reaction column in an amount greater than the equivalent amount required to absorb and remove sulfur oxides and hydrogen chloride.

The present invention solves the above-mentioned problems, and aims to provide a method for treating incinerator exhaust gas in which alkaline component fine particles can effectively act on sulfur oxides and hydrogen chloride in the exhaust gas.

Means for Solving the Problems In order to solve the above problems, the present invention sprays ammonium and a chemical solution containing alkali component fine particles as a processing agent into a reaction tower through which exhaust gas flows, thereby reducing nitrogen oxides and sulfur in the exhaust gas. Ammonium and alkali component fine particles are reacted with the oxide and hydrogen chloride, and the ammonium chloride produced by the reaction of ammonia and hydrogen chloride is incorporated into the aggregate of the alkali component fine particles that aggregate with the reaction product. The sublimation action of the ammonium chloride makes the aggregate porous and makes it finer, expanding the reaction area of the alkali component fine particles present in the unreacted state in the aggregate and promoting the reaction against sulfur oxides and hydrogen chloride. In a method for treating incinerator exhaust gas, ammonium chloride sublimated by cooling the exhaust gas with the heat of vaporization of water in a chemical solution containing fine alkaline particles is condensed, and the treated exhaust gas containing solid fine particles of condensed ammonium chloride is passed through a bag filter. By suctioning through the filter, solid fine particles of ammonium chloride, alkaline component fine particles, and reaction products are separated and removed from the treated exhaust gas, and unreacted alkaline component fine particles are absorbed into the ammonium chloride adsorbed and fixed on the bag filter surface. Ammonia is regenerated from ammonium chloride through a reaction, and the treated exhaust gas containing the regenerated ammonia is guided to a catalyst bed, where nitrogen oxides and ammonia in the treated exhaust gas are reacted and decomposed into nitrogen and water. be.

Effect: With the above-mentioned configuration, ammonium chloride incorporated into the agglomerates of alkaline component fine particles rises. By doing so, the portion occupied by ammonium chloride in the aggregate becomes a cavity, making the aggregate porous, and at the same time, the bonds between the alkaline component fine particles are broken and the aggregate is made finer. This expands the reaction area of unreacted alkali component fine particles, improves the reaction efficiency of the alkali component fine particles, and suppresses the amount of alkali component fine particles to be sprayed.

Furthermore, nitrogen oxides in the exhaust gas react with ammonia, decompose into nitrogen and water, and are removed. Then, ammonia is regenerated from the generated ammonium chloride, and the regenerated ammonia reacts with nitrogen oxides in the treated exhaust gas and decomposes into nitrogen and water, so it is necessary to treat ammonium chloride, which is a harmful substance, by a separate means. As the nitrogen oxides disappear, the removal efficiency of nitrogen oxides increases.

EXAMPLE An example of the present invention will be described below based on the drawings. 1st
In the figure, the lower part of the casing 1 of the reaction tower has an exhaust gas 2
A supply port 3 is formed in the upper part of the casing 1, and a discharge port 4 is formed in the upper part of the casing 1 to communicate with the next process. and,
A hollow first drive shaft 5 is attached to the casing 1.
The first drive shaft 5 is rotatably held by the top plate 6 via an upper bearing 7, and forms a processing agent input passage 8. There is.

Further, a first drive device 9 is connected to the first drive shaft 5, and this first drive device 9 rotates the first drive shaft 5 in one direction around the axis at high speed. Furthermore, the first drive shaft 5
A first diffusion plate 10 is provided around the opening at the lower end of the first diffusion plate 10, and a plurality of crushing rods U are vertically disposed at appropriate intervals on the peripheral edge of the first diffusion plate 10.

A second diffusion plate 12 is arranged at a position facing the first diffusion plate 10 via a crushing rod 11, and this second diffusion plate 2 vertically penetrates the bottom plate I3 of the casing 1 and is inserted into the casing 1. The second drive shaft 14 is fixed to the upper end of the second drive shaft 14 inserted into the inside of the second drive shaft 14 . Furthermore, a plurality of standing dispersion plates 15 are arranged radially above the second dispersion plate 12 . Further, the second drive shaft 14 is connected to the bottom plate 1 through the second bearing 11i.
3, and a second drive device 17 is connected to the lower end side of the second drive shaft 14. This second drive device I7 rotates the second drive shaft 14 at high speed in a direction opposite to the rotational direction of the first drive shaft 5.

A plurality of crushing plates 18 are provided at predetermined intervals on the second drive shaft I4, and a large number of bins 19 are arranged concentrically and in multiple rows on the crushing plate I8. .

Further, a plurality of fixing plates 20 are provided on the inner wall of the casing 1 and are located between the crushing plates 18.
rotatably supports the second drive shaft 14 via the third bearing 21. Furthermore, a large number of bins 22 are provided on the fixed plate 20 so as to be located between the bins 19 of the crushing plate 18.

The outlet 4 of the casing 1 communicates with the baghouse 24 via the rectifying plate 23, and the baghouse 24 is divided into an upper chamber 25 and a lower chamber 26, with the lower chamber 2B connected to the outlet 4 of the casing 1. It's communicating. Further, a plurality of bag filters 27 are provided in the lower chamber 2B so as to communicate with the upper chamber 25.
A dust conveyor 2 is provided at the bottom of the lower chamber 2B so as to be located below each bag filter 27. Further, a dust outlet 29 of the baghouse 24 is formed at the terminal end of the dust conveyor 28.

In the upper chamber 25 of the baghouse 24, a plurality of catalyst beds 3 are provided.
0 is provided between each bag filter 27, and a heating steam pipe 31 is provided between each catalyst bed 30. In addition, a ventilation duct 3 is provided on the upstream side of the upper chamber 25.
1 is in communication with the casing 1, and the ventilation duct 32 is in communication with the casing 1 via a fan 33. Further, an exhaust port 34 is formed on the downstream side of the upper chamber 25 and communicates with a suction device 35 .

The effects of the above configuration will be explained below.

A first drive shaft 5 driven by a first drive device 9, and a second drive shaft 5 driven by a first drive device 9.
The rotation of the second drive shaft 14 driven by the drive device 17 causes the first diffusion plate! While rotating O and the second diffusion plate 12 at high speed in opposite directions, a chemical solution containing an alkaline component such as Ca(OH)si and ammonium are first introduced as the treatment agent 3B through the first opening of the first drive shaft 5. Diffusion plate 10 and second diffusion plate! 2 to the gap 37 between the two.
Then, centrifugal force is applied to the processing agent 38 supplied to the gap 3 by rotation of the second diffusion plate 12. At this time, the dispersion plate 15 receives and stops the processing agent 38 in the circumferential direction of the second diffusion plate 12, prevents the processing agent 3B from sliding in the circumferential direction, and reliably applies centrifugal force to the processing agent 3G.

Then, the processing agent 36 subjected to centrifugal force is moved in the radial direction on the second diffusion plate I2 along the distribution plate 15, and after leaving the distribution plate 15, it collides with the crushing rod U and is crushed into fine particles. , is ejected around the second diffusion plate 12. At this time, the crushing rod 11 is moving in a direction opposite to the direction of rotation of the second diffuser plate 12, so the crushing rod! The collision speed of L and the processing agent 36 is increased synergistically, and the pulverization efficiency of the processing agent 36 is improved.

Then, the processing agent 3B spouted into the inside of the casing 1 is transferred to the bottles 19 and 22 provided on the crushing plate 18 and the fixed plate 2o.
The exhaust gas 2 is further pulverized by colliding with the exhaust gas 2 supplied into the casing 1 from the supply port 3, and reacts with the harmful components of nitrogen oxides, sulfur oxides, and hydrogen chloride in the exhaust gas 2, and then becomes the treated exhaust gas. 38 and is sent to the baghouse 24 from the discharge port 4. This reaction formula is shown below.

N H3+ HCI-+N H4C1 2NH3+sO, -i-(NH4)2804Ca (O
H)* +2HC1 → CaC7g +2H20 Ca (OH)Q +5O- 1+CaSO4+2H2O NH3+NO4→NQ+nHa O And, in the above reaction production step, as shown in Figure 2, ammonium chloride α produced by the reaction of ammonia and hydrogen chloride is incorporated into the aggregate of alkaline component fine particles γ that aggregate together with the reaction product β.

Then, as the ammonium chloride α taken in is degassed by sublimation, the part occupied by ammonium chloride α in the aggregate becomes a cavity, the aggregate becomes porous, and the bonds between the alkaline component fine particles γ are broken. As a result, the aggregates are made finer, and the reaction area of the alkali component fine particles γ present in the form of unreacted rods in the aggregates is expanded, thereby promoting the reaction against sulfur oxides and hydrogen chloride. This eliminates the need to spray more than the equivalent amount of alkaline component fine particles γ, and it is possible to suppress the amount of alkali component fine particles γ to be sprayed.

Then, the exhaust gas 2 is cooled by the heat of vaporization of the water in the chemical solution containing the alkali component fine particles γ, and the sublimated ammonium chloride α is condensed. The solid fine particles of ammonium chloride α that have condensed are guided into the baghouse 24 through the rectifying plate 23 together with the treated exhaust gas 38.
It is separated and removed from the treated exhaust gas 38 by being sucked into the suction device 35 through the bag filter 27 . At this time, as shown in FIG. 3, unreacted alkali component fine particles γ, Ca C12, and Ca S
Oa and (NH4)2S04 are simultaneously separated and removed from the treated exhaust gas 38, and a cake layer 39 is formed around the bag filter 27 by the removed substances. Then, the unreacted alkali component fine particles γ react with the ammonium chloride α adsorbed and fixed on the surface of the bag filter 24, and ammonia is regenerated from the ammonium chloride α. This reaction is shown below.

2N84C! +Ca(OH)2 →2NH3+CaCノ2+H20 Then, the regenerated ammonia and the treated exhaust gas 38 flow into the upper chamber 25 through the bag filter 27, and the steam pipe 3
It passes through a catalyst bed 30 which is heated to 1. At this time, nitrogen oxides and ammonia in the treated exhaust gas 38 react with each other under catalytic action, and are decomposed into nitrogen and water.

This reaction is shown below.

NH3 + NOx → N2 + n H20 Further, hot air inside the casing 6 is supplied to the upper chamber 25 by a fan 33 via the ventilation duct 32, and the temperature inside the upper chamber 25 is maintained at a high temperature, thereby preventing dew condensation.

The removed substances adhering to the bag filter 27 can be removed by applying vibration or backwashing air to the bag filter 27.
It is peeled off from the bag filter 27, falls onto the dust conveyor 28, and is taken out from the dust outlet 29.

Effects of the Invention As described above, according to the present invention, ammonium chloride is incorporated into the aggregate of alkaline component fine particles, and by sublimation of the ammonium chloride, the portion occupied by ammonium chloride in the aggregate is made into a cavity. None, it is possible to make the aggregate porous and make the aggregate finer by breaking the bonds between the alkaline component fine particles, expanding the reaction area of the unreacted alkali component fine particles, and increasing the reaction efficiency of the alkali component fine particles. can be improved and the amount of alkali component fine particles sprayed can be suppressed. Furthermore, since ammonia is regenerated from sublimated ammonium chloride and ammonium chloride is decomposed into chlorine and gaseous ammonium, which migrate into the dust components, it is possible to prevent ammonium chloride from migrating into the treated exhaust gas, and to prevent ammonium chloride from being regenerated. By reacting the ammonia with nitrogen oxides in the treated exhaust gas, the removal efficiency of nitrogen oxides can be increased.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing one embodiment of the present invention, FIG. 2 is a schematic diagram showing a reaction generation process in the same embodiment, and FIG. 3 is a schematic diagram showing the state of separation and removal in a bag filter. 2... Exhaust gas, 27... Bag filter, 38...
Processing agent, α...ammonium chloride, β...reaction product, γ...alkaline component fine particles.

Claims (1)

[Claims] 1. Sprinkle a chemical solution containing alkali component fine particles as a treatment agent and ammonia gas into the reaction tower through which exhaust gas flows, and cause the ammonia gas and alkali component fine particles to react with nitrogen oxides, sulfur oxides, and hydrogen chloride in the exhaust gas. , ammonium chloride produced by the reaction of ammonia and hydrogen chloride is incorporated into the aggregate of alkali component fine particles that aggregate with the reaction product, and the aggregate is made porous by the sublimation action of the incorporated ammonium chloride. In a method for treating incinerator exhaust gas, in which the alkali component fine particles present in an unreacted state in the agglomerate are further refined and the reaction area of the alkali component fine particles present in the aggregate is expanded to promote the reaction against sulfur oxides and hydrogen chloride. The sublimated ammonium chloride is condensed by cooling the exhaust gas with the heat of vaporization of water in the chemical solution, and the treated exhaust gas containing the condensed solid fine particles of ammonium chloride is sucked through a bag filter. Alkaline component fine particles and reaction products are separated and removed from the treated exhaust gas, and unreacted alkali component fine particles are reacted with ammonium chloride adsorbed and fixed on the bag filter surface to regenerate ammonia from ammonium chloride. A method for treating incinerator exhaust gas characterized by introducing treated exhaust gas containing ammonia into a catalyst bed, causing nitrogen oxides in the treated exhaust gas to react with ammonia and decomposing it into nitrogen and water.