KR20160087017A - Exhaust gas treating apparatus improved removal efficiensy of so3 - Google Patents

Abstract

The present invention relates to an exhaust gas treating apparatus, which is capable of improving efficiency of removal of SO_3 from exhaust gas which is generated when fuel including sulfur is burnt. According to the present invention, provided is an exhaust gas treating apparatus for improving efficiency of removal of SO_3, comprising: a primary heat exchanger which is coupled to an incinerator configured to burn fuel including sulfur, and adjusts a temperature of exhaust gas, discharged from the incinerator, to a preset temperature; a selective catalytic reductor which is coupled to the primary heat exchanger, and reduces nitrogen oxide of exhaust gas having passed through the primary heat exchanger; a secondary heat exchanger which is coupled to the selective catalytic reductor, and adjust a temperature of exhaust gas, having passed through the selective catalytic reductor, to a preset temperature; an SO_3 remover which is coupled to the secondary heat exchanger, and removes SO_3 of exhaust gas having passed through the secondary heat exchanger; and a flue gas desulfurizer (FGD) which is coupled to the SO_3 remover, and removes sulfur oxide of exhaust gas having passed through the SO_3 remover.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an exhaust gas treatment apparatus,

The present invention relates to an exhaust gas treatment apparatus in an industrial process using a fuel containing sulfur, and more particularly to an exhaust gas treatment apparatus having improved SO ₃ removal efficiency.

Flue-gas desulfurization refers to a method of removing sulfur oxides contained in soot and exhaust gas. It is also called exhaust gas desulfurization. Since sulfur oxides contained in the soot of factories and thermal power plants cause air pollution, desulfurization from soot is an important task in the world, in view of the prevention of environmental pollution and the effective use of sulfur resources. do.

Current flue gas desulfurization processes can remove up to 90% of SO ₂ , but most of the SO ₃ is not treated and is discharged, which has a limitation that can cause new environmental problems. In Korea, the discharge regulation of air environmental conservation law, sulfur oxides, but is regulated by the total amount of sulfur oxides including SO ₂ and SO _3, these indicators and relative to SO _2, sulfur oxides to the SO ₂ as an index (SOx ) Reduction has been studied only. Therefore, even the measurement method for SO ₃ is not well defined.

However, SO ₃ may cause health problems as well as cause civil complaints such as increased pollution of soil and decrease of crop yield, causing air pollution problem and damage of acid rain, and it may cause corrosion of various equipments.

Part of the SO ₃ generated in the combustion of petroleum coke is combined with moisture in the gas and converted into sulfuric acid (H ₂ SO ₄ ) mist, and is present in the gas. Generally, SO ₂ , SO ₃ and H ₂ SO ₄ Mist or the like can be removed through a flue gas desulphurizer (FGD). However, sulfuric acid (H ₂ SO ₄ ) which can not be removed from the desulfurizer is discharged through the stack through a large amount of mist, and a mist eliminator is installed to remove the mist. However, There is a problem in that corrosion due to corrosion is easily generated.

Sulfuric acid mist present at the end of the desulfurization facility installed in most large power plants is corroded at the downstream equipment due to exhaustion without being removed from the desulfurization facility. In other words, as the flue gas is rapidly cooled by the liquid spray in the desulfurization plant, the vaporous sulfuric acid is formed into very fine sulfuric acid aerosol particles through an abrupt concentration process. These aerosol particles are, in most cases, too small in size to be effectively trapped in desulfurization plant systems and released into the atmosphere by sulfuric acid fumes. In particular, the recent power plant to increase the corrosion occurs and trouble (trouble) in the rear end of the trend yiyeoseo desulfurization system because of the additional SO ₃ conversion of SO ₂ to install the catalyst reduction apparatus (SCR) to the rear end of the economizer (Economizer).

The inventors of the present invention have endeavored to research this problem for a long time and completed the present invention.

A related art is Korean Registered Patent No. 10-0517175 (registered on September 16, 2005, wet flue gas desulfurization method).

An object of the present invention is to provide an exhaust gas treatment device which improves the removal efficiency of SO ₃ from the exhaust gas generated upon combustion of a fuel containing sulfur.

First, an SO ₃ remover including a wet scrubber is additionally provided to improve the removal efficiency of SO _{3 in} the exhaust gas. There is provided an exhaust gas treating apparatus capable of increasing the adsorption efficiency between a solution used in a wet scrubber and SO ₃ particles by providing a wet scrubber at the rear end of a secondary heat exchanger and using high temperature heat passed through a secondary heat exchanger will be.

Further, an exhaust gas treatment device provided with an electrostatic dust precipitator at the downstream of the SO ₃ eliminator is provided so that residual SO ₃ remaining after passing through the SO ₃ eliminator flows into the electrostatic precipitator to reduce the electric resistance value of the dust in the electrostatic precipitator to increase the dust collecting efficiency .

According to an embodiment of the present invention, a primary heat exchanger coupled to an incinerator for combusting a fuel containing sulfur to regulate the temperature of the exhaust gas discharged from the incinerator to a predetermined temperature; A selective catalytic reduction unit coupled to the primary heat exchanger for reducing nitrogen oxides in the exhaust gas passing through the primary heat exchanger; A secondary heat exchanger coupled to the selective catalytic reduction unit for regulating the temperature of the exhaust gas passing through the selective catalytic reduction unit to a predetermined temperature; An SO ₃ remover coupled to the secondary heat exchanger for removing SO ₃ from the exhaust gas passing through the secondary heat exchanger; And coupled to the SO ₃ Disposal, flue gas desulfurizer for removing the exhaust gas of the sulfur dioxide passes through the SO ₃ Disposal: comprising the (FGD Flue Gas Desulferlizer), improve the SO ₃ removal efficiency that the exhaust A gas processing apparatus is provided.

At this time, the SO ₃ eliminator, may be to include a wet scrubber and removing adsorbed SO ₃ and SO ₃ by spraying the solution of which can be absorbed the exhaust gas.

In addition, the present invention may further include an injection amount controller coupled to the wet scrubber, the injection amount controller being capable of controlling the injection amount of the solution.

In addition, the present invention is the SO ₃ canceller in order to increase the dust collection efficiency of the electrostatic precipitator comprises a further electrostatic precipitator, which is disposed between the SO ₃ canceller and the flue gas desulfurizer to remove the dust, in combination with the dust Residual SO ₃ in the exhaust gas that has passed through can be used.

At this time, the temperature of the exhaust gas may be maintained at 350 to 400 ° C in the secondary heat exchanger.

The solution may include any one of lime, limestone, magnesium oxide (MgO), sodium hydroxide (NaOH), and sodium carbonate (Na ₂ CO ₃ ) solution.

In addition, the present invention may further include a re-injector coupled to the wet scrubber and capable of recovering and re-injecting a solution not used for adsorption with SO ₃ .

Above exhaust gas processing that improves the removal efficiency of SO ₃ in accordance with the present invention apparatus is a secondary heat exchanger SO ₃ used to install the wet scrubber at the rear end a high-temperature heat of the group a secondary heat exchanger to the absorption of SO ₃ and the solution Can be improved.

Further, SO ₃ Disposal rear end there is provided an electric dust collector, it is passed through the eliminator, and the remaining residual SO ₃ SO ₃ may be used to reduce the electrical resistance of the dust in the electrostatic precipitator to increase the electric dust-collecting efficiency.

On the other hand, even if the effects are not explicitly mentioned here, the effect described in the following specification, which is expected by the technical features of the present invention, and its potential effects are treated as described in the specification of the present invention.

FIG. 1 is a view showing an exhaust gas treatment apparatus having improved SO ₃ removal efficiency according to an embodiment of the present invention.
2 is a view showing an adsorption mechanism in the SO ₃ eliminator of the present invention.
3 is a graph showing the conversion of SO ₃ to H ₂ SO ₄ at a constant humidity (8%) with temperature.
FIG. 4 is a view showing an exhaust gas treatment apparatus having improved SO ₃ removal efficiency according to another embodiment of the present invention.
It is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, the same reference numbers refer to the accompanying drawings, the exhaust gas processing device that improves the removal efficiency of SO ₃ to be described in detail, and, in the following description with reference to the accompanying drawings, components identical or corresponding are according to the invention And redundant explanations thereof will be omitted.

The flue gas desulfurization process in the industrial process using sulfur is mainly used to remove SO ₂ , and the sulfur dioxide emission control index is also based on the SO ₂ in the Air Quality Preservation Act. Through continuous strengthening of sulfuric acid emission regulations and research and development in Korea, the concentration and emission of SO ₂ were reduced to about 90%. However, environmental pollution including the corrosion of process facilities due to untreated SO ₃ , air pollution, etc. Is continuing. In the present invention the exhaust gas processing device that improves the removal efficiency of SO ₃ according to are intended to provide an exhaust gas treatment apparatus including an SO ₃ Disposal of a primary object to remove SO _3.

Sulfur-containing fuels include petroleum coke. Exhaust gases from industrial processes using petroleum coke fuels include sulfur oxides such as SO _{2 and} SO ₃ . In addition, a part of the SO ₃ generated in the combustion of the petroleum coke is converted into sulfuric acid (H ₂ SO ₄ ) mist by being combined with moisture in the gas, and is present in the gas. Generally, SO ₂ , SO ₃ and H ₂ SO ₄ mist contained in the gas can be removed through a desulfurization facility. However, the sulfuric acid (H ₂ SO ₄ ) which has not been removed from the desulfurization plant is discharged through the stack as a large amount of mist.

In other words, as the flue gas is rapidly cooled by the liquid spray in the desulfurization facility, the vaporous sulfuric acid forms fine sulfuric acid aerosol particles through an abrupt concentration process. These aerosol particles are so small in most cases that they are difficult to capture effectively in a desulfurization facility and are released into the atmosphere by sulfuric acid mist. Especially, recently, the power plants have installed the SCR unit at the end of the economizer. Therefore, the conversion of the SO ₂ to SO ₃ has caused corrosion at the rear end of the desulfurization equipment.

1 is a view showing an exhaust gas processing apparatus 1000 having improved SO ₃ removal efficiency according to an embodiment of the present invention. As shown in FIG. 1, an exhaust gas treatment apparatus having improved SO ₃ removal efficiency according to an embodiment of the present invention includes a primary heat exchanger 100, a selective catalytic reduction unit (SCR) 200, A heat exchanger 300, an SO ₃ remover 400, and a flue gas desulfurizer (FGD) 500. The fuel including sulfur such as petroleum coke is burned in the incinerator I and the exhaust gas generated by the combustion moves to the primary heat exchanger 100. [ The incinerator (I) is a facility for combustion of petroleum coke and the like, and is a place for emitting high-temperature heat.

In the primary heat exchanger 100, the temperature of the exhaust gas supplied to the SCR is controlled. That is, the exhaust gas discharged from the incinerator I flows through the primary heat exchanger 100 to the selective catalytic reducer 200 under temperature control. At this time, the temperature of the exhaust gas in the primary heat exchanger 100 can be adjusted to about 400 degrees or less. That is, the exhaust gas is adjusted to an appropriate temperature so that the reduction process by the catalytic reduction process in the selective catalytic reduction unit 200 can be performed well.

In the selective catalytic reduction unit 200, the nitrogen oxide in the exhaust gas is preferentially reduced. That is, nitrogen oxides (NOx) in the exhaust gas transferred to the SCR are reduced to water (H ₂ O) and nitrogen (N ₂ ) using a catalyst at a temperature of 400 ° C. or less. In this process, SO ₂ in sulfur oxides is oxidized by high heat and converted to small amounts of SO ₃ .

The exhaust gas passing through the selective catalytic reducer 200 is transferred to the secondary heat exchanger. The secondary heat exchanger is for regulating the temperature of the exhaust gas passing through the selective catalytic reducer 200 to a constant temperature. In other words, doubling the gas passed through the secondary heat exchanger there is moved to SO ₃ canceller 400, where it is possible to adjust the temperature of the exhaust gas to a temperature required for the SO ₃ eliminator 400. The The SO ₃ remover 400 may include a wet scrubber. Further, the secondary heat exchanger may be set to maintain the temperature of the exhaust gas at 350 to 400 degrees. The reason why exhaust gas of 350 degrees to 400 degrees is set up will be described in detail below.

2 is a view showing an adsorption mechanism in the SO ₃ remover 400. FIG. 2, the wet scrubber is a spray solution to be adsorbed and the SO ₃ to remove the SO ₃ in the downward direction. The solution may include any one of lime, limestone, magnesium oxide (MgO), sodium hydroxide (NaOH), and sodium carbonate (Na ₂ CO ₃ ) solution. These solutions include solutes in which adsorption reaction with SO ₃ particles occurs well. The sprayed solution is brought into contact with the hot SO ₃ gas supplied from the high-temperature secondary heat exchanger to evaporate the solvent. At this time, the separated solute is adsorbed with SO ₃ and sinks in the form of dust, which is recovered and SO ₃ can be removed.

An important reason for passing through a secondary heat exchanger before moving to a wet scrubber for SO ₃ removal is that SO ₃ is converted to gaseous sulfuric acid (H ₂ SO ₄ ) at a typical exhaust gas temperature of 204 ° C or less, 127 to 150 degrees) or less to form an aerosol, and sulfuric acid in an aerosol state is not easily removed. As can be seen from FIG. 3, at a constant humidity (8%), SO ₃ is hardly converted to sulfuric acid at a high temperature, for example, 350 ° C or higher. That is, the exhaust gas processing device that improves the removal efficiency of SO ₃ in accordance with the present invention made the SO ₃ by was kept above a constant temperature preventing the SO ₃ conversion with sulfuric acid, the SO ₃ removal in the wet scrubber will effectively It can be done.

As can be seen from FIG. 2, the present invention may further include a re-injector 700 coupled to the wet scrubber. The re-injector 700 re-injects a solution that has been injected for adsorption with SO _{3 in} a wet scrubber but has not been used for the adsorption reaction with SO ₃ so that it can be re-injected into the wet scrubber. Therefore, it is possible to eliminate environmental pollution by eliminating the use of the discharged and discarded solution, and to greatly reduce the total amount of the solution as the solution is reused.

Further, the present invention may further include an injection amount regulator 600. The injection amount regulator 600 is coupled to a wet scrubber to regulate the injection amount of the solution. By controlling the injection amount of the sprayed solution, it becomes possible to control the amount of SO ₃ to be removed. One of the reasons for controlling the amount of SO ₃ removed is as follows.

FIG. 4 is a view showing an exhaust gas treatment apparatus having improved SO ₃ removal efficiency according to another embodiment of the present invention. As shown in FIG. 4, in the exhaust gas treatment apparatus having improved SO ₃ removal efficiency according to the present invention, an electrostatic precipitator 450 may be coupled to the rear end of the SO ₃ remover 400. The electrostatic precipitator 450 collects and removes dust generated in the flue gas desulfurization process with electricity. At this time, SO ₃ is a main factor that influences the surface conduction effect of dust together with moisture, and as the amount of water and SO ₃ increases, the electric resistance value of dust decreases. That is, SO ₃ is combined with moisture to increase the surface conduction and lower the electric resistance value, thereby increasing the electrostatic precipitating efficiency of the electrostatic precipitator 450. Therefore, it is possible to control the amount of SO ₃ removed in the SO ₃ remover 400 and to move the constant SO ₃ to the electrostatic precipitator 450 to increase the dust collecting efficiency of the electrostatic precipitator 450. That is, by moving the appropriate amount of SO _3, rather than removing 100% of SO ₃ injection amount controller (600) of a wet scrubber to control the injection amount of solution used in the SO ₃ and the suction in the electric dust collector 450 of the electrostatic precipitator 450 The dust collecting efficiency can be improved.

The exhaust gas passing through the electrostatic precipitator 450 is removed through the flue gas desulfurizer 500 after removing most of the SO ₂ to the discharge part O and then discharged to the outside. The exhaust gas thus discharged can effectively remove not only SO ₂ but also SO ₃ , and can be discharged to the outside.

The scope of protection of the present invention is not limited to the description and the expression of the embodiments explicitly described in the foregoing. It is again to be understood that the present invention is not limited by the modifications or substitutions that are obvious to those skilled in the art.

I: Incinerator
O: outlet
100: primary heat exchanger
200: Selective catalytic reducer
300: Secondary heat exchanger
400: SO ₃ remover
450: Electrostatic precipitator
500: Flue gas desulfurizer
600: injection quantity regulator
700: Re-injector
1000: Exhaust gas treatment device with improved removal efficiency of SO ₃

Claims (7)

A primary heat exchanger coupled to the incinerator for combusting the fuel including sulfur and adjusting the temperature of the exhaust gas discharged from the incinerator to a predetermined temperature;
A selective catalytic reduction unit coupled to the primary heat exchanger for reducing nitrogen oxides in the exhaust gas passing through the primary heat exchanger;
A secondary heat exchanger coupled to the selective catalytic reduction unit for regulating the temperature of the exhaust gas passing through the selective catalytic reduction unit to a predetermined temperature;
An SO ₃ remover coupled to the secondary heat exchanger for removing SO ₃ from the exhaust gas passing through the secondary heat exchanger; And
The SO ₃ is coupled to the eliminator, flue gas desulfurizer for removing sulfur oxides from the exhaust gas passing through the eliminator SO _3: comprising the (FGD Flue Gas Desulferlizer),
An exhaust gas treatment apparatus improved in SO ₃ removal efficiency. The method according to claim 1,
The SO ₃ eliminator includes:
Including a wet scrubber, wherein the SO ₃ is sprayed with a solution which can be absorbed, characterized in that for removing adsorbed SO ₃ in the exhaust gas,
An exhaust gas treatment apparatus improved in SO ₃ removal efficiency. 3. The method of claim 2,
Further comprising an injection amount adjuster coupled to the wet scrubber to adjust the injection amount of the solution.
An exhaust gas treatment apparatus improved in SO ₃ removal efficiency. The method of claim 3,
The SO ₃ canceller and the flue gas desulfurizer is installed between, and further comprising an electric dust collector for removing dust, in combination with the dust, the exhaust gas having passed through the SO ₃ canceller in order to increase the dust collection efficiency of the electrostatic precipitator of that the residual SO ₃ is used, characterized in,
An exhaust gas treatment apparatus improved in SO ₃ removal efficiency. 3. The method of claim 2,
And the secondary heat exchanger maintains the temperature of the exhaust gas at 350 to 400 DEG C,
An exhaust gas treatment apparatus improved in SO ₃ removal efficiency. 3. The method of claim 2,
Characterized in that the solution comprises any one of lime, limestone, magnesium oxide (MgO), sodium hydroxide (NaOH) and sodium carbonate (Na ₂ CO ₃ )
An exhaust gas treatment apparatus improved in SO ₃ removal efficiency. 3. The method of claim 2,
Further comprising a re-injector coupled to the wet scrubber and capable of recovering and re-injecting a solution not used for adsorption to SO ₃ ,
An exhaust gas treatment apparatus improved in SO ₃ removal efficiency.

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