JPH07313839A - Moving bed for treating exhaust gas - Google Patents

Abstract

PURPOSE:To provide a device optimum for dust removal, desulfurization, denitrification and chlorine compound removal of exhaust gas contg. smoke dust, gaseous SO2, nitrogen oxides and chlorine compounds. CONSTITUTION:A carbon agent 2 of <=5mm average particle diameter is deposited on sintered ore 1 of 1mm-10mm diameter. Then, a moving bed 6 is packed with the deposited material. The spacific surface area of the carbon agent 2 measure by the BET method is preferably >=20m<2>/g.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an industrial field in which a large amount of exhaust gas is discharged, for example, an exhaust gas for desulfurizing and denitrifying a large amount of exhaust gas discharged from a sintering furnace, a refuse incinerator, a boiler, etc. to remove chlorine compounds. It relates to a moving bed for processing.

[0002]

2. Description of the Related Art For example, exhaust gas generated from a sintering furnace, a refuse incinerator, or a boiler has a high concentration of sulfurous acid gas (SO
₂ ), Nitrogen oxides and trace amounts of chlorine compounds are contained, so desulfurization, denitration and removal of chlorine compounds are necessary to prevent air pollution.

Regarding desulfurization, a lime gypsum method, a magnesium hydroxide method, and an adsorption method on activated coke are known.
Regarding denitration, for example, selective reduction denitration with ammonia in the presence of a catalyst such as vanadium pentoxide or activated coke is known. Regarding the removal of chlorine compounds, for example, as described in “Mechanical Engineering Handbook”, Engineering Edition, C8 environmental equipment, a method of decomposing by heating to 600 ° C. or higher, a method of oxidative decomposition with a vanadium oxide 5 catalyst, an activity A method of adsorbing and removing coke is known.

In order to carry out these reactions, for example,
As described in "Research on flue gas desulfurization technology", Japan Industrial Machinery Manufacturers Association, in the case of aqueous substances such as magnesium hydroxide, gas is blown into a container filled with a scrubber or liquid. The bubbling method is 5
For denitration using a vanadium oxide catalyst or removal of chlorine compounds, the fixed bed is a fixed bed, and in the case of activated coke or zeolite molded to a size of 5 mm or more, the moving bed or fixed bed is a lignite coke produced by lightly distilling brown coal. When using powdered substances such as slaked lime, dry scrubbers or circulating fluidized beds are used.

Further, for example, as described in "Mechanical Engineering Handbook", Engineering Edition, C8 Environmental Equipment,
There is also known a method in which a metal oxide catalyst having a denitration action is supported on a carrier made of TiO ₂ or the like, and exhaust gas treatment is carried out as a fixed bed.

[0006]

However, when a liquid reactant such as a magnesium hydroxide solution is used, a water treatment facility for treating the reaction product is required and the water treatment facility can be operated smoothly. Therefore, the dust concentration in the treated gas needs to be about 100 mg / Nm ³ or less, and it is indispensable to install the dust removing equipment in the preceding stage of the water treatment equipment, so the equipment cost is high.

When denitration using a vanadium pentoxide catalyst or chlorine compound removal is performed, in order to maintain the catalytic function, it is necessary to remove dust in order to remove a solid substance that inhibits the catalytic function, such as alkali, in the preceding stage. It is necessary to install a high-performance dust remover in the previous stage. Further, for example, when ammonia is blown into the gas as a reducing agent for nitrogen oxides,
Since a chemical reaction with sulfur oxides on the catalyst produces ammonium sulfate or acidic ammonium sulfate to impair the catalytic function, it is also necessary to install a desulfurizer at the previous stage in order to remove the sulfur oxides. In addition to these, it is necessary to heat the gas to be treated to 300 ° C. or higher, so it is necessary to install a heating device. As a result, the equipment cost becomes very expensive.

The method of performing gas treatment in a moving bed or fixed bed using activated coke or zeolite molded to a size of 5 mm or more does not require water treatment equipment because it is a dry treatment, and desulfurization, denitration, and removal of chlorine compounds are carried out at the same time. Since it can be performed, it is inexpensive in terms of equipment. However, in order to allow the gas to smoothly pass through the moving bed or the fixed bed, it is necessary to mold active coke or zeolite to a particle size of 5 mm or more, which increases the cost for molding.

A method such as an inexpensive method such as lignite coke in which a powdery reactant having a particle size adapted to the gas flow rate in the reactor is blown into a reactor such as a circulating fluidized bed or a dry scrubber is It is cheaper than when used for a moving bed or a fixed bed, and a dry scrubber or a circulating fluidized bed can secure a sufficient time for carrying out a reaction for removing harmful substances in a gas. However, when comparing the service life of powdered reactants such as lignite coke with the retention of lignite coke in the dry scrubber or circulating fluidized bed riser, the residence time in these reactors is short. Therefore, in order to use the powdery reactant economically, the powdery reactant discharged from the dry scrubber and the riser of the circulating fluidized bed should be collected by the dust collector and used again, that is, the circulation of the powdery reactant should be performed. Use is essential. However, if the inlet dust concentration of the dry scrubber or circulating fluidized bed is high, the powdery reactant and the dust are mixed, so in order to prevent the powdery reactant from being diluted by the mixing, the dust concentration of the inlet gas is 50 mg / It is necessary to remove dust to Nm ³ or less, and an advanced dust remover must be installed in the preceding stage. In addition, it is necessary to install dust removing equipment for collecting the reactant in the subsequent stage, and the equipment cost becomes high.

The method of supporting the catalyst on the carrier and treating the exhaust gas in the fixed bed needs to be replaced every time the catalyst function deteriorates. Therefore, it is economical when using a powdery reactant having a relatively short service life. is not.

An object of the present invention is to provide an apparatus suitable for dust removal, desulfurization, denitration, and chlorine compound removal of exhaust gas containing soot dust, sulfurous acid gas, nitrogen oxides, and chlorine compounds.

[0012]

Means for Solving the Problems The gist of the present invention is to provide a moving bed for treating exhaust gas, which is filled with a substance for purifying exhaust gas emitted into the atmosphere, by adding a carbonizing agent having an average particle diameter of 5 mm or less to a sintered ore having a diameter of 1 mm or more and 10 mm or less. It is a moving bed for treating exhaust gas, characterized in that it is carried on and filled with. BET of the charcoal agent
The specific surface area measured by the method is preferably 20 m ² / g or more.

[0013]

[Function] For example, a sulfurous acid gas concentration of 150 to 200 ppm
The exhaust gas containing a small amount of chlorine compounds has a pore radius of 1 to 1 that has a function of adsorbing sulfur dioxide gas and chlorine compounds in the gas.
When treated with an activated carbon agent having a pore size of 10 nm and a specific surface area of about 100 m ² / g, a contact time with a gas, that is, a reaction time is required to be 0.5 to 1.0 seconds in order to desulfurize by 80% or more, The service life until the desulfurization ability of the activated carbon agent decreases to 80% or less is about 20 hours. In addition, the chlorine compound is 80
% Or more, the reaction time is required to be 0.5 to 1.0 seconds, and the service life until the chlorine compound removing ability of the activated carbon agent decreases to 80% or less is about 120 hours.

A moving bed filled with an activated carbon agent having the functions of desulfurization, denitration and chlorine compound removal of exhaust gas by supporting it on a sintered ore having a large particle size removes harmful substances and has a sufficient exhaust gas treatment ability of the activated carbon agent. It can be used up. Also,
Since it is not necessary to use an expensive molded activated carbon agent, it is possible to use an inexpensive powdered activated carbon agent. In addition, since the moving bed has a dust removing capability, there is no need to install dust removing equipment at the front and rear stages, and the equipment cost is low.

Activated carbon agents having an average particle size of more than 5 mm can be used as the packing for the moving bed, but the average particle size is 5 m.
In order to exceed m, molding is required, resulting in high manufacturing cost. Therefore, a carbonizing agent having an average particle diameter of 5 mm or less is used.

The reason why the carbonizing agent is supported on the sinter having a diameter of 1 mm or more and 10 mm or less is that, as described in Japanese Patent Application No. 4-337798, the sinter having a diameter of 1 to 10 mm has a dust removal rate of 98. This is because, in addition to having a high degree of dust removal capability of not less than%, being excellent in the ability to adhere and carry powders in a porous manner, it can be used as a sintering raw material after exhaust gas treatment. The reason for using the charcoal agent as a substance that removes harmful substances is
This is because the carbonizing agent can be used as a fuel after losing its function in exhaust gas treatment.

The specific surface area of the carbonizing agent measured by the BET method is 20.
The reason why it is preferably m ² / g or more is to ensure the adsorption ability of sulfur oxides, nitrogen oxides, and chlorine compounds on the surface of the carbonizing agent.

In the present invention, a carbonizing agent is adopted as the substance having a harmful substance removing function.
It is also possible to support a substance having a function of removing harmful substances such as slaked lime and a metal oxide catalyst on the sinter.

[0019]

Embodiments of the present invention will be described with reference to FIGS.

For the purpose of desulfurization of exhaust gas and removal of chlorine compounds, as shown in FIG. 1, a sintered ore 1 having a grain size adjusted to a diameter of 3 mm or more and 5 mm or less has pores having a pore radius of 1 to 10 nm, A specific surface area of about 100 m ² / g and an average particle size of 0.
In the cross flow type moving bed 6 in which the powder of the charcoal agent 2 of 5 mm of activated carbon was premixed at a rate of 20 kg / t, and supported and filled,
Sulfurous acid gas concentration of 150 under the condition of space velocity of about 5000 h ^-1
It was brought into contact with the exhaust gas 5 of a sintering furnace containing a trace amount of chlorine compounds at ˜200 ppm. Inlet exhaust gas 5 if dust is not removed in advance
The soot and dust concentration of No. ³ varied from 400 to 800 mg / Nm ³ . In this case, since the moving bed 6 also has a function of removing the exhaust gas 5, soot is accumulated in the moving bed 6, so that the retention time of the packing is about 10 in order to smoothly operate without causing clogging. Must be less than or equal to time. Therefore, as a result of operating as the residence time of the packing, which is the shorter of the limit retention time that does not cause clogging due to soot dust and the service life of the activated carbon agent, which is the shorter time, desulfurization is performed as the exhaust gas cleaning capacity of the moving bed 6. A rate of 85%, a chlorine compound removal rate of 99%, and a dust removal rate of 97% were obtained.

Next, for the purpose of removing chlorine compounds only,
As shown in FIG. 2, a cross flow type moving layer 6 having a two-layer structure.
Was used. The first moving bed 8 is made of a sintered ore whose particle size is adjusted to have a diameter of 3 mm or more and 5 mm or less, and has a space velocity of about 7,000.
It is a moving bed with h ⁻¹ and a residence time of 10 hours. Dust removal rate is about 9
At 7%, the dust concentration at the outlet is less than 35 mg / Nm ³ . The second moving bed 9 is preliminarily mixed and loaded with a powder of activated carbonaceous agent 2 having an average particle diameter of 0.5 mm in a proportion of 20 kg / t in a sintered ore 1 having a diameter adjusted to 3 mm or more and 5 mm or less. In the moving bed, the space velocity is about 7000 h ^-1 .
The reason why the moving layer has a two-layer structure is that if the first moving layer 8 is preliminarily dedusted, the second moving layer 9 can prevent clogging due to soot and dust, so that the residence time is about 1 which is close to the service life of the carbonaceous agent 2 of activated carbon.
This is because it can be operated as 00 hours. The test results are
The dust removal rate was 99% and the chlorine compound removal rate was 85%.

As an example of the method of supporting the carbonizing agent, the method of mixing with the sintered ore in advance has been explained. For example, the moving bed utilizes the function of removing and holding the powder contained in the gas, and the exhaust gas is provided in the preceding stage of the moving bed. A powdery carbonaceous agent may be blown therein.

[0023]

According to the present invention, it is possible to highly remove soot and harmful substances from exhaust gas containing soot and harmful substances with inexpensive equipment.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a moving layer for treating exhaust gas of the present invention.

FIG. 2 is a diagram showing an example of a moving layer for treating exhaust gas of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sintered ore 2 Charcoal agent 3 Mixer 4 Transport path 5 Exhaust gas 6 Moving bed 7 Clean exhaust gas 8 1st moving bed 9 2nd moving bed 10 Transfer path

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B01D 53/68 B01D 53/34 134 A

Claims (2)

[Claims] 1. A moving bed for treating exhaust gas, which is filled with a substance for purifying exhaust gas emitted into the atmosphere, characterized in that a carbonizing agent having an average particle diameter of 5 mm or less is carried and filled in a sinter having a diameter of 1 mm to 10 mm. A moving bed for exhaust gas treatment. 2. The moving bed for treating exhaust gas according to claim 1, wherein the carbonaceous agent has a specific surface area of 20 m ² / g or more as measured by the BET method.