KR100587490B1 - Treatment apparatus of incineration flue gas - Google Patents

Abstract

The present invention relates to an incinerator exhaust gas treating apparatus and an incinerator exhaust gas treating method, which apparatus includes a pretreatment facility, a combustion chamber, a waste heat boiler, and an exhaust gas treatment facility, A dry-type reaction unit for removing acidic gas from the exhaust gas by reacting with sodium bicarbonate; Activated carbon input section; A bag filter unit; And a low-temperature selective catalytic reduction unit, the use of the cooling process water required in the existing exhaust gas treatment process and the reheating for heating the exhaust gas are unnecessary, It is possible to reduce the cost of separate wastewater treatment and fuel for reheating the exhaust gas, and the exhaust gas treatment process can be simplified to make the equipment compact, thereby reducing the site required for the facility construction.

Exhaust gas, dry reaction, sodium bicarbonate, activated carbon, low temperature selective catalytic reduction, selective non catalytic reduction

Description

TECHNICAL FIELD [0001] The present invention relates to an apparatus for treating incineration flue gas,

1 to 3 are conceptual diagrams of a conventional incinerator exhaust gas treatment process,

FIG. 4 and FIG. 5 are conceptual diagrams of a process for treating an exhaust gas discharged from an incinerator according to the present invention.

The present invention relates to an apparatus for treating contaminants such as dust, acid gas, heavy metals, nitrogen oxides, dioxins and the like contained in exhaust gas discharged from an incinerator, comprising a dry reactor for supplying sodium sodium bicarbonate, The waste gas is not generated in the exhaust gas treatment process, and the exhaust gas treatment process is performed at a low temperature without separately heating the exhaust gas from the dry reaction unit, which is the first stage of the exhaust gas treatment process, to the low temperature selective catalytic reduction unit, The present invention relates to an apparatus for treating waste gas discharged from an incinerator and a method for treating waste gas using the same.

The incinerator is composed of a waste pretreatment facility, a combustion chamber, a waste heat boiler and an exhaust gas treatment facility. The pretreatment facility functions to homogenize the waste in the bunker and supply it to the incinerator. The combustion chamber functions to incinerate the waste at a certain temperature , The waste heat boiler functions to collect the heat of the exhaust gas and cool the exhaust gas, and the exhaust gas treatment facility functions to remove and destroy the contaminants in the exhaust gas.

The exhaust gas treatment facility is an exhaust gas treatment facility in which exhaust gas contains particulate matter, acid gas such as HCl, SO ₂ and HF, heavy metals such as Pb, Hg and Cd, dioxins such as nitrogen oxides (NO x), dioxins and furans As the facility to remove the material before it is discharged to the atmosphere, the exhaust gas treatment facility of the incineration facility applied in Korea can be divided into the following three types according to the acid gas treatment process.

The first type is a semi-dry process in which the liquid phase is evaporated while the slurry of calcium hydroxide supplied to the semi-dry reaction tower reacts with the exhaust gas to form a reaction state with the acid gas, and the solid product is collected and discharged into a bag filter A semi-dry type reaction tower for introducing calcium hydroxide slurry as shown in FIG. 1, an activated carbon charging unit, a bag filter unit, and a selective catalytic reduction (SCR) unit. The semi-dry process is advantageous in that it is easy to operate and operate. However, problems such as clogging and abrasion in the calcium hydroxide supply facility and scaling due to the calcium hydroxide supplied into the semi-cylindrical reaction column are generated, And there is a disadvantage that the operation cost and the construction cost are slightly increased.

 The second type is that as the exhaust gas from which the dust is removed from the electrostatic precipitator is cooled to a saturated state by the circulating water in the wet scrubbing tower, the exhaust gas discharged from the scrubbing tower is cooled to 60-80 캜, A wet scrubbing tower in which acid gas is removed by a sodium hydroxide solution sprayed from a spray nozzle provided in a scrubbing tower, an electrostatic precipitator, a wet scrubbing tower in which sodium hydroxide is circulated and discharged as shown in FIG. 2, Heater and a selective catalytic reduction (SCR) unit. The above-mentioned wet process uses sodium hydroxide which is harmful and corrosive, is complicated in operation operability, is problematic in the treatment of wastewater generated in a wet scrubbing column, requires countermeasures against white smoke, requires a large amount of process water, And the construction cost is very high.

The third type is a dry process in which the exhaust gas discharged from the waste heat boiler is cooled in a water-spray type quenching tower and the calcium hydroxide is sprayed in a fine powder state to form a filter cake in the bag filter, 3, the apparatus includes a temperature tower, a calcium hydroxide powder input unit, an activated carbon input unit, a bag filter unit, and a selective catalytic reduction (SCR) unit. Since the dry process requires the use of process water in the thermal tower and the acid gas removal of the calcium hydroxide powder is good at low temperatures of about 150 ° C., the process water is sprayed in the thermal tower to lower the discharge gas temperature, The SCR process must reheat the exhaust gas at 150-160 ° C to 220-300 ° C, which is the catalyst activation temperature, thereby causing fuel cost problems.

Therefore, development of an exhaust gas treatment facility capable of solving the problems of conventional waste gas treatment facilities, such as the problem of waste water treatment and the problem of fuel gas cost due to exhaust gas heating, has been urgently needed.

 In order to overcome the problems of the conventional exhaust gas treatment facility, that is, the problem of waste water treatment and the fuel cost due to exhaust gas heating, sodium bicarbonate is injected into a dry process without generation of wastewater to remove acidic gas, An exhaust gas treatment apparatus for removing NOx and gaseous dioxins by a low-temperature SCR process which removes dust, heavy metals and dioxins from the bag filter and eliminates the need for heating the exhaust gas and has high nitrogen oxide removal efficiency, and an exhaust gas treatment method using the same The purpose is to provide.

In order to achieve the above object,

An apparatus for treating gas discharged from an incinerator, comprising a pretreatment facility, a combustion chamber, a waste heat boiler, and an exhaust gas treatment facility, wherein the exhaust gas treatment facility comprises a dry reaction unit for removing acidic gas by reacting with sodium bicarbonate; Activated carbon input section; A bag filter unit; And a low temperature selective catalytic reduction section.

At this time, the operating temperature of the dry type reaction part is 200 ° C, the operating temperature of the bag filter is 190-200 ° C, and the operating temperature of the low temperature selective catalytic reduction part is 175-185 ° C.

The present invention also provides an incinerator exhaust gas treatment method comprising a waste pretreatment step, a waste incineration step, a waste heat boiler passing step, and an exhaust gas treatment step, wherein the exhaust gas treatment step comprises: Removing the acid gas by transferring sodium bicarbonate to the reaction part (step 1); A step of adsorbing dust, heavy metals and dioxins by injecting activated carbon into the exhaust gas subjected to the dry reaction (second step); Removing the adsorbed dust, heavy metals and dioxins by moving the activated carbon treated exhaust gas to the bag filter unit (third step); And a step of moving the exhaust gas passing through the bag filter unit to the low temperature selective catalytic reduction unit and removing a nitrogen oxide by adding a reducing agent (fourth step).

At this time, the operating temperature of the first step is 200 ° C, the operating temperatures of the second and third steps are 190-200 ° C, and the operating temperature of the fourth step is 175-185 ° C.

The acid gas is hydrogen chloride, sulfur dioxide, sulfur trioxide or hydrogen fluoride, the nitrogen oxide is nitrogen oxide or nitrogen dioxide, and ammonia is used as a reducing agent.

The present invention will be described in detail as follows.

Temperature which has passed through the waste heat boiler the exhaust gas of 200 ℃ is charged into the sodium bicarbonate powder into the dry reaction by moving parts of the dry reaction, and acid gases such as hydrogen chloride (HCl), sulfur dioxide (SO _2), sulfur trioxide (SO _3), fluoride Hydrogen (HF) and the like are removed. The removal reaction of sodium bicarbonate and the acid gas in the exhaust gas is shown in the following reaction formula (1). As in the present invention, when the step of removing the acid gas from the exhaust gas is carried out by dry sodium bicarbonate powder, there is no generation of waste water unlike the conventional wet reaction tower process.

NaHCO ₃ + HCl → NaCl + H ₂ O + CO ₂

2NaHCO ₃ + SO ₂ + 1 / 2O ₂ → Na ₂ SO ₄ + H ₂ O + 2CO ₂

2NaHCO ₃ + SO _{3 -} > Na ₂ SO ₄ + H ₂ O + 2CO ₂

NaHCO ₃ + HF - > NaF + H ₂ O + CO ₂

Activated carbon powder is injected into the exhaust gas passing through the dry reaction section to absorb heavy metals such as dust, Pb, Hg, Cd, and dioxins such as dioxins and furans and remove them from the bag filter. The operating temperature is 190-200 ° C.

The exhaust gas that has undergone the above process is subjected to a low-temperature selective catalytic reduction (SCR) unit to introduce ammonia as a reducing agent to remove nitrogen oxides (NOx) and remove gaseous dioxins. The operating temperature is 175-185 ° C. The elimination reaction of the nitrogen oxide by the ammonia reducing agent is as shown in the following reaction formula 2, and the elimination reaction of the dioxins is as shown in the following reaction formula 3. Since the catalyst used in the conventional SCR process has a high temperature of 220 to 300 ° C, the SCR process reheats the exhaust gas by operating at 220 to 300 ° C, which causes problems such as fuel cost problems and re-synthesis of dioxins However, since the operating temperature of the low-temperature SCR is 175-185 ° C, it is possible to remove nitrogen oxides and gaseous dioxins in the exhaust gas without any problem due to the reheating of the exhaust gas.

4NO + 4NH ₃ + O ₂ ? 4N ₂ + 6H ₂ O

_{6NO 2 + 8NH 3 → 7N 2} + 12H 2 O

_{C 12 H 4 Cl 4 O 2} + 11O 2 → 12CO 2 + 4HCl

2C ₁₂ H ₄ Cl ₄ O + 23O ₂ → 24CO ₂ + 8HCl

The apparatus for treating waste gas discharged from an incinerator according to the present invention is characterized in that the operating temperature of the dry reactor is 200 ° C, the operating temperature of the bag filter is 200-190 ° C, and the operating temperature of SCR is 175-185 ° C, The construction of the facility can be made compact, and the site required for construction can be reduced.

The present invention also provides a system for treating gas discharged from an incinerator, comprising a pretreatment facility, a combustion chamber, a waste heat boiler, and an exhaust gas treatment facility, the apparatus comprising: a selective non-catalytic reduction (SNCR) unit between a combustion chamber and a waste heat boiler; An exhaust gas treatment system includes an apparatus for treating an exhaust gas discharged from an incinerator comprising a dry reaction unit for removing an acid gas by reacting with sodium bicarbonate, an activated carbon charging unit, and a bag filter unit.

In the selective non-catalytic reduction (SNCR) unit, the urea is introduced as a reducing agent to remove NOx, which is shown in the following reaction formula (4).

_{4NO + 2CO (NH 2) 2} + O 2 → 4N 2 + 2CO 2 + 4H 2 O

_{6NO 2 + 4CO (NH 2)} 2 → 7N 2 + 4CO 2 + 8H 2 O

As described above, the use of the apparatus for treating waste gas discharged from an incinerator according to the present invention prevents the generation of wastewater due to the acidic gas treatment being performed in a dry process, As the exhaust gas treatment process proceeds at a low temperature without separately heating the exhaust gas to the reducing unit, it is not necessary to input additional energy for reheating the exhaust gas, so it is possible to reduce the cost of the wastewater treatment and the fuel cost for reheating the exhaust gas In addition, since the exhaust gas treatment process is simplified, the equipment can be made compact, thereby reducing the site required for equipment construction.

Claims (4)

An apparatus for treating gas discharged from an incinerator, comprising a pretreatment facility, a combustion chamber, a waste heat boiler, and an exhaust gas treatment facility, the exhaust gas treatment facility comprising: a dry reaction unit for reacting and removing acidic gas with sodium bicarbonate; Activated carbon input section; A bag filter unit; And a low temperature selective catalytic reduction unit. The apparatus for treating an incinerator exhaust gas according to claim 1, wherein the operating temperature of the dry reaction part is 200 ° C, the operating temperature of the bag filter is 190-200 ° C, and the operating temperature of the low temperature selective catalytic reduction part is 175-185 ° C. A method for treating an incinerator exhaust gas comprising a waste pre-treatment stage, a waste incineration stage, a waste heat boiler passing stage, and an exhaust gas treatment stage, Transferring the exhaust gas passing through the waste heat boiler to the dry reaction section to remove the acid gas by injecting sodium bicarbonate (first step); A step of adsorbing dust, heavy metals and dioxins by injecting activated carbon into the exhaust gas subjected to the dry reaction (second step); Removing the adsorbed dust, heavy metal and dioxin by moving the activated carbon treated exhaust gas to the bag filter unit (third step); And Removing the nitrogen oxide by moving the exhaust gas passing through the bag filter unit to the low temperature selective catalytic reduction unit and adding a reducing agent (fourth step) Wherein the gas is discharged from the incinerator. An apparatus for treating gas discharged from an incinerator, comprising a pretreatment facility, a combustion chamber, a waste heat boiler and an exhaust gas treatment facility, the apparatus comprising a selective non-catalytic reduction unit between a combustion chamber and a waste heat boiler, A dry reaction part for removing and reacting with sodium bicarbonate, an activated carbon charging part, and a bag filter part.

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