KR20130034703A - Nox reduction system of dual type - Google Patents

Abstract

PURPOSE: A complex-type nitrogen oxide processing system is provided to further improve reduction processing efficiency of nitrogen oxide by widening an optimum temperature range of nitrogen oxide reduction reaction by mixing one additive of hydrocarbon and alcohol to a reducer. CONSTITUTION: A complex-type nitrogen oxide processing system includes a non-selective catalytic reduction apparatus and a selective catalytic reduction apparatus. The non-selective catalytic reduction apparatus firstly reduction processes nitrogen oxide included in exhaust gas exhausted from a combustion apparatus(100) using a reducer through a non-selective catalytic reduction method. The selective catalytic reduction apparatus secondly reduction processes nitrogen using a reducer through a selective catalytic reduction method. The non-selective catalytic reduction apparatus is the reductant spray unit spraying one of reducers of urea water and ammonia solution to the combustion apparatus. One of additives of hydrocarbon and alcohol is mixed in the reducer. The reductant spray unit is installed to spray the reducer to the position spaced apart from a combustion room of the combustion apparatus. [Reference numerals] (100) Combustion apparatus;

Description

NOx reduction system of dual type

The present invention relates to a nitrogen oxide treatment system, and more particularly, to a complex nitrogen oxide treatment system combined with a selective catalytic reduction method and a non-selective catalytic reduction method.

Modern society needs enormous amount of energy, and most of the energy required is thermal energy, which is obtained by oxidation of organic materials. However, various types of air pollutants are generated as oxides of organic materials. Among them, the characteristic of nitrogen oxide is that, unlike other pollutants such as SOx and CO, it is generated by combustion air even if there is no nitrogen component in the raw material.

Nitrogen oxides produce secondary pollutants by photochemical action, which is one of the major pollutants in urban air pollution. Nitrogen oxides from combustion are mainly emitted in the form of NO and NO is soon converted into reddish brown NO ₂ in the atmosphere. Although the toxicity of NO is relatively weak, NO ₂ is about 5-10 times more toxic than NO. It destroys respiratory cells at high concentrations and binds with hemoglobin in the blood, causing respiratory distress. It also causes acid rain, increases the atmospheric ozone concentration as a major cause of photochemical reactions, and causes photochemical smog by generating secondary pollutants such as PAN and aldehyde.

In 2005, Korea has tightened emission regulations for nitrogen oxides. Therefore, the necessity of reducing the emission concentration in the main emission facilities is gradually increasing, and as a plan, a method of controlling nitrogen oxide at the emission source is being devised. Fuel reduction and combustion control technologies can be mentioned as a method of reducing nitrogen oxides at the source, but fuel improvement has economic problems, and it is difficult to control the combustion at a certain concentration because high temperature combustion is essential for complete combustion. Accordingly, flue gas denitrification technology has been developed, and many studies have been conducted to increase the treatment efficiency. However, there is still a limit to the removal of nitrogen oxides, which requires the development of new technologies.

On the other hand, the reaction to remove the nitrogen oxide discharged from the source can be divided into dry method and wet method according to the physical properties, the wet method includes a wet cleaning method, oxidation absorption method, liquid phase reduction method, oxidation absorption method and the like. The wet method has the advantage of being able to remove NOx and SOx simultaneously and being hardly affected by particulate matter in the exhaust gas, while having a high investment cost and operation cost, and treating wastewater. On the other hand, the dry method has the advantages of lower investment cost and maintenance cost than the wet method, simple process and high NOx removal rate. It is also suitable for large-capacity NOx removal processes and does not require wastewater treatment.However, it is affected by the dust contained in the exhaust gas, and it is ammonium sulfate ((NH ₄ ) ₂ SO ₄ ) or ammonium bisulfate (NH ₄ HSO _4). There is a disadvantage that is likely to emit by-products such as).

Such a dry method includes a catalytic reduction method, a noncatalytic reduction method, an adsorption method, an electron beam irradiation method, and the like. Among these, Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR) are the most commonly used methods. Each method has different advantages and disadvantages. The SCR process increased the processing efficiency by up to 90% by using a catalyst and allowed processing at low temperatures of 250-350 ° C. However, maintenance costs are high due to high installation costs, catalyst exchange costs, and fuel costs. In domestic incinerators or facilities that emit relatively low concentrations of NOx, the SNCR process has been tried to have a removal efficiency of about 40-60%. SNCR can be easily installed in existing incinerators because it is a relatively simple facility that requires only a reagent injector and a reagent reservoir.

The SNCR process varies depending on the reaction temperature, the location and speed of the injection nozzle, and the type of reagent. Therefore, many studies have been conducted to determine the proper reaction temperature and the position and velocity of the nozzle. The main reaction of SNCR occurs in the narrow temperature range of 900-1100 ℃ and generally shows the maximum removal efficiency at 950-1000 ℃.

The problem with SNCR processes is their narrow processing temperature range with low processing efficiency. In Korea, the legal operating temperature of incinerators is 850 ℃. However, in order to apply the SNCR process, it is necessary to operate in a higher temperature range and design the device according to the high temperature condition when designing the incinerator. Therefore, supplementary energy is required when incineration of household waste or sludge with low calorific value, and stable operation becomes difficult.

The SNCR process has low facility investment and operating costs and is easy to install, but shows low removal efficiency, while the SCR process has high removal efficiency, but the initial investment cost and operation cost are large.

On the other hand, as a prior art in the field, a water remover for removing the moisture of the nitrogen oxide contaminated air, an ozone generator for generating ozone, by reacting the ozone supplied from the ozone generator with the nitrogen oxide contaminated air from which the water is removed the polluted air An ozone reaction chamber for oxidizing nitrogen monoxide (NO) to nitrogen dioxide (NO ₂ ), and nitrogen oxide contaminated air and residual ozone are transferred from the ozone reaction chamber to decompose the ozone into oxygen radicals by a catalyst, and the contaminated air. An apparatus for treating nitrogen oxides using an ozone and catalytic hybrid system has been proposed, comprising a catalytic reaction chamber in which nitrogen dioxide (NO ₂ ) in the reaction is reacted with the produced oxygen radicals and oxidized to nitric acid group (NO ₃ −). (See Patent Document 1).

[Patent Document 1] Domestic Patent Publication 10-2010-0104173

In order to solve the above problems, the present invention combines a selective catalytic reduction method and a non-selective catalytic reduction method, which combines a nitrogen oxide treatment system and a nitrogen oxide treatment system. The purpose is to provide.

In order to achieve the above object, the complex nitrogen oxide treatment system according to the present invention is a system for reducing and treating nitrogen oxide contained in exhaust gas discharged from a combustion apparatus, by using a reducing agent through a non-selective catalytic reduction method. A non-selective catalytic reduction device for primarily reducing nitrogen oxides; It characterized in that it comprises a selective catalytic reduction device for the secondary reduction treatment of nitrogen oxides using a reducing agent through a selective catalytic reduction method.

Here, the non-selective catalytic reduction device may be a reducing agent injection means for injecting any one of the reducing agent of urea water and ammonia water to the combustion device.

In addition, the additive may be blended with any one of hydrocarbons and alcohols.

In addition, the reducing agent injection means may be installed to inject the reducing agent at a position spaced apart from the combustion chamber of the combustion device.

In addition, the selective catalytic reduction device, urea water storage tank in which urea water is stored as a reducing agent; A pump for forcibly pumping and transferring urea water in the urea water storage tank; A catalytic reaction tower composed of a casing having an inlet part installed at an upper center and an outlet part provided at a lower part thereof, and a multistage catalyst layer disposed inside the casing and having bead-type catalysts having fine pores; Steam injection means for washing the fine dust in the bead-type catalyst by injecting steam at a high temperature and high pressure between the multi-stage catalyst layer; A transfer duct installed at one end thereof to communicate with an end portion of the discharge duct, and at the other end thereof to communicate with an inlet portion of the casing to guide the exhaust gas into the casing; An exhaust gas uniform distribution means for distributing the exhaust gas uniformly in the transfer duct in one end of the transfer duct; It has an inlet through which the urea water pumped and transported into the pump and an outlet through which the introduced urea water is discharged, and has an accommodating space portion within which the urea water is temporarily accommodated. A circulation heater having an electrode electrically connected with a positive electrode from the outside; Injection means for injecting urea water discharged from the outlet of the circulation heater in the same direction as the traveling direction of the exhaust gas into a transfer duct corresponding to the exhaust gas flow region on the downstream side of the uniform distribution means; Turbulent flow forming means which is installed in a transfer duct corresponding to the downstream side of the injection means to form a turbulent state of the exhaust gas and particulate urea water having passed through the uniform distribution of the exhaust gas, and urea water is decomposed into ammonia. and; After the mixed gas of ammonia and exhaust gas having an irregular flow velocity in turbulent flow flows through the inlet by the turbulence forming means, it is installed in the casing before passing through the first catalyst layer so that the flow rate of the exhaust gas becomes constant. It can be made including a flow rate changing means.

In addition, the selective catalytic reduction device, the ammonia water storage tank 150 in which ammonia water is stored as a reducing agent; A pump 170 for forcibly pumping and transporting the ammonia water in the ammonia water storage tank 150; A casing 210 having an inlet portion 211 installed at an upper side and an outlet portion 212 provided at a lower side thereof, and a multistage having bead catalysts 221 disposed inside the casing 210 and having minute pores. A catalytic reaction tower (200) consisting of a catalyst layer (220) of the; Steam injection means 230 for washing the fine dust in the bead-type catalyst (221) by injecting a steam at a high temperature and high pressure between the multi-stage catalyst layer 220; A transfer duct installed at one end thereof to communicate with an end portion of the discharge duct, and at the other end thereof to communicate with an inlet portion of the casing to guide the exhaust gas into the casing; An exhaust gas uniform distribution means for distributing the exhaust gas uniformly in the transfer duct in one end of the transfer duct; It has an inlet through which the ammonia water pumped to be transferred to the pump is introduced, and an outlet through which the introduced ammonia water is discharged, and has an accommodating space part inside which the ammonia water is temporarily accommodated. A circulation heater having an electrode electrically connected from the positive electrode; Injection means for injecting ammonia water discharged from the outlet of the circulation heater in the same direction as the traveling direction of the exhaust gas into a transport duct corresponding to the exhaust gas flow region on the downstream side of the uniformly uniform exhaust gas distribution means; Turbulence forming means provided in a conveying duct corresponding to the downstream side of the jetting means to form a turbulent state of exhaust gas passing through the exhaust gas uniform distribution means and ammonia water in a particulate state; After the mixed gas of ammonia and exhaust gas having an irregular flow velocity in turbulent flow flows through the inlet by the turbulence forming means, it is installed in the casing before passing through the first catalyst layer so that the flow rate of the exhaust gas becomes constant. It can be made including a flow rate changing means.

According to the present invention, the dual type combining the selective catalytic reduction method and the non-selective catalytic reduction method can improve the reduction efficiency and economic efficiency of nitrogen oxide to the maximum. In addition, by mixing an additive of any one of hydrocarbons and alcohols with the reducing agent, the optimum temperature range of the nitrogen oxide reduction reaction can be widened to further improve the efficiency of reducing nitrogen oxides. In addition, by using a bead-type catalyst having fine pores in the catalyst layer in the catalytic reaction tower, the contact area of the exhaust gas is widened as compared with the conventional fixed honeycomb catalyst layer to further improve the nitrogen oxide reduction treatment efficiency. It can be arranged freely with little space limitation.

1 is a graph showing changes in nitrogen oxide reduction efficiency of urea water and ammonia water according to temperature change.
2 is a graph showing a change in nitrogen oxide reduction efficiency according to temperature change when hydrocarbons are injected as an additive when urea water is used as a reducing agent.
Figure 3 is a graph showing the change in nitrogen oxide reduction efficiency with temperature changes when alcohol is injected into the additive when using urea water as a reducing agent.
4 is a graph showing a change in nitrogen oxide reduction efficiency according to temperature change when alcohols are injected as an additive when ammonia water is used as a reducing agent.
5 is a diagram showing an overall configuration of a processing system of the present invention.
Figure 6 shows a conventional honeycomb catalyst layer.
7 is an external perspective view of the exhaust gas uniform distribution means in the configuration of the treatment system of the present invention.
8 and 9 are external perspective views showing the configuration of the turbulence forming means according to the present invention.
10 is a view showing a state in which the flow rate change means according to the present invention is installed in the casing.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a graph showing a change in nitrogen oxide reduction efficiency of urea water and ammonia water with temperature change, Figure 2 shows a change in nitrogen oxide reduction efficiency with temperature change when hydrocarbons are injected as an additive when urea water is used as a reducing agent. 3 is a graph showing a change in nitrogen oxide reduction efficiency according to temperature change when alcohols are injected as an additive when urea water is used as a reducing agent, and FIG. 5 is a graph showing a change in nitrogen oxide reduction efficiency according to temperature change, FIG. 5 is a view showing the overall configuration of the treatment system of the present invention, and FIG. 6 is a view showing a conventional honeycomb catalyst layer.

The composite nitrogen oxide treatment system according to the present invention is a dual type in which a selective catalytic reduction method and a non-selective catalytic reduction method are combined to improve the efficiency and economic efficiency of reducing nitrogen oxides.

That is, the complex nitrogen oxide treatment system according to the present invention is a system for efficiently reducing and treating nitrogen oxides contained in exhaust gas discharged from a combustion apparatus, and using a reducing agent through a non-selective catalytic reduction method to reduce nitrogen oxides to 1. Including a non-selective catalytic reduction device for the reduction process and a selective catalytic reduction device for the secondary reduction treatment of the nitrogen oxide firstly reduced in the non-selective catalytic reduction device using a reducing agent through a selective catalytic reduction method Characterized in that made.

Through this configuration, it is possible to more efficiently reduce the nitrogen oxide contained in the exhaust gas discharged from the combustion device.

Here, the non-selective catalytic reduction device comprises a reducing agent injection means 101 for injecting a reducing agent of any one of urea water (urea) and ammonia water (NH ₃ ) to the combustion device.

In this case, the reducing agent to widen the optimum temperature range of the NOx reducing reaction to further improve the reduced processing efficiency of _{NOx, CH 4, C 2 H 6} , C 3 H 6 , etc. of the hydrocarbons and CH _3O H, C ₂ may be any of alcohols such as H ₅ OH in the additive is combined.

In other words, when only the urea water and the ammonia water reducing agent are used without any additive, the nitrogen oxide reduction reaction occurs only in a narrow temperature window of 800 to 1050 ° C as shown in FIG. Therefore, in order to reduce the nitrogen oxide generated in the combustion device 100 such as a boiler or an incinerator, a reducing agent must be injected into the optimum temperature region in the furnace through a non-selective catalytic reduction device.

In addition, in most cases, since the optimum temperature region moves in accordance with the load in the combustion apparatus 100, the reducing agent injection position may be installed in two or three stages. However, in many cases, the reducing agent is structurally selected as the optimum temperature region. There is a case that cannot be sprayed. In such a case, there is a limitation in reducing the nitrogen oxide with only the reducing agent, and by using a predetermined additive in the reducing agent, the optimum temperature range in the reaction through the non-selective catalytic reduction apparatus is appropriately widened. At this time, the additive generates the OH, H, O radical at a low temperature to play a role in the reaction rate governing step of the non-selective catalytic reduction device occurs at a low temperature.

As shown in FIG. 2, when hydrocarbons are injected as an additive when urea water is used as a reducing agent, it can be seen that nitrogen oxide removal efficiency is increased in the injection temperature range of 800 ° C. or lower than when only urea water is injected. .

As shown in FIG. 3, when the urea water is used as the reducing agent, when the alcohols are injected as an additive, the nitrogen oxide removal efficiency is increased in the injection temperature range of 800 ° C. or lower than when only the urea water is injected. .

As shown in FIG. 4, when the ammonia water is used as the reducing agent, when the alcohols are injected as an additive, the nitrogen oxide removal efficiency is increased in the injection temperature range of 800 ° C. or lower than when only the ammonia water is injected.

As such, it can be seen that nitrogen oxide removal efficiency is improved in the low temperature region of 700 to 800 ° C. by using the reducing agent and the additive simultaneously.

In addition, the reducing agent injection means 101 is preferably installed to inject the reducing agent in a position spaced apart from the combustion chamber of the combustion device (100). The reason for this is that when the reducing agent injection means 101 is provided at a position close to the combustion chamber, the reducing agent to be injected may oxidize and the nitrogen oxide generation amount may increase.

On the other hand, the selective catalytic reduction device of the present invention, by using the urea water and ammonia water as a reducing agent to perform a pretreatment so that the ammonia and nitrogen oxides are sufficiently mixed before passing through the catalyst layer of the catalytic reaction tower, first, the urea water as a reducing agent Will be described first.

The present invention is a selective catalytic reduction device for the first treatment in a non-selective catalytic reduction device, the second treatment so that the nitrogen oxide contained in the exhaust gas discharged from the combustion device 100 through the exhaust duct 110, The main configuration is the storage tank 150, pump 170, catalytic reaction tower 200, steam injection means 230, transfer duct 300, exhaust gas uniform distribution means 400, The circulation heater 500, the injection means 600, the turbulence forming means 700, and the flow rate changing means 900 are included.

Urea water is stored in the storage tank 150.

The pump 170 serves to pump and transfer the urea water in the urea water storage tank 150 by force.

The catalytic reaction tower 200 has a casing 210 having an inlet portion 211 installed at an upper center and an outlet portion 212 provided at a lower side thereof, and a bead having a fine pore disposed inside the casing 210. It consists of a multi-stage catalyst layer 220 (220a, 220b, 220c) with catalysts 221.

Here, the catalyst layers 220: 220a, 220b, and 220c are installed in multiple stages spaced apart from each other. In the present invention, the catalyst layer has a three-layer structure. As the catalyst of the catalyst layer, the catalyst layer is generally used for reducing nitrogen oxides. Can be used.

For reference, the conventional catalyst layer used a honeycomb catalyst layer having a fixed shape as shown in FIG. Accordingly, it has to be manufactured and installed to fit the structure of the catalytic reaction tower 200, there was a problem receiving space constraints.

However, the catalyst layers 220: 220a, 220b, and 220c of the present invention use a catalyst layer having beaded catalysts 221 having fine pores. Accordingly, regardless of the structure of the catalytic reaction tower 200 can be installed freely, it can be arranged freely with little space constraint. In addition, since the surface of the bead catalyst 221 has a plurality of fine pores, it is possible to further increase the contact area of the exhaust gas to further improve the nitrogen oxide reduction treatment efficiency.

The steam injecting means 230 is to inject steam of a high temperature and high pressure between the multi-stage catalyst layer 220 to clean the fine dust in the catalyst bar, this steam injecting means 230 is a known technique, Detailed description will be omitted.

The transfer duct 300 is provided such that one end portion 310 is in communication with the end portion of the discharge duct 110, and the other end portion 320 is installed so as to communicate with the inlet portion 211 of the casing 210. It serves to guide the exhaust gas into the casing 210.

The exhaust gas uniform distribution means 400 serves to uniformly distribute the exhaust gas so as to flow uniformly in the transfer duct 300 to one end 310 side of the transfer duct 300.

The circulation heater 500 has an inlet 510 through which urea water pumped and transferred by the pump 170 is introduced, and an outlet 520 through which the introduced urea water is discharged, and the urea water is temporarily accommodated therein. It has a space portion 530, and is provided so as to be immersed in the urea water in the receiving space portion 530 has a configuration having an electrode rod 540 electrically connected to the (+) electrode from the outside.

The injection means 600, the urea discharged from the outlet 520 of the circulation heater 500 into the transfer duct 300 corresponding to the exhaust gas flow region on the downstream side of the uniform distribution of the exhaust gas 400 To spray in the same direction as the traveling direction of the exhaust gas in the particulate state, the technical configuration of injecting a liquid such as urea in the particulate (micro unit; μm) state is generally well known and will not be described. Shall be.

The turbulence forming means 700 is installed in a conveying duct 300 corresponding to the wake side of the jetting means 600 to turbulent exhaust gas and the urea water in the form of particulates past the uniform distribution of the exhaust gas 400. The state is formed and the urea water is decomposed into ammonia.

The flow rate changing means 900 is a first catalyst layer 220a after a mixed gas of ammonia and exhaust gas having an irregular flow velocity in turbulent flow by the turbulence forming means 700 flows through the inlet portion 211. It is installed in the casing 210 before passing through so that the flow rate of the exhaust gas is constant.

Referring to the operation of the nitrogen oxide treatment system using urea water as a reducing agent in the present invention configured as described above are as follows.

First, the exhaust gas due to the operation of the combustion device 100 such as a boiler is discharged through the discharge duct 110 and moved along the inside of the transfer duct 300, and then the casing constituting the catalytic reaction tower 200 ( Inflow to the inlet 211 of the 210.

Here, after passing through the exhaust gas uniform distribution means 400 installed on one end of the transfer duct 300 connected to the exhaust duct 110, the exhaust gas flows through the entire interior of the transfer duct 300 Rather it is distributed and flows in a uniform, evenly distributed state.

The exhaust gas uniform distribution means 400 is composed of a plate 410 which is installed in the transfer duct 300 in a direction perpendicular to the flow direction of the exhaust gas, and the distribution hole 411 over the entire plate 410. ) Are penetrated to be spaced apart from each other at equal intervals.

When the exhaust gas passes through the plate 410 due to the distribution holes 411 of the uniform gas distribution unit 400 as described above, the flow is evenly distributed throughout the interior of the transfer duct 300 It can be distributed and flowed.

Here, the diameter of the distribution hole 411 is 3cm ~ 10cm to be distributed and flow evenly distributed throughout the interior of the transfer duct 300, the distribution holes 411 the plate 410 It is preferable to form in a dense state.

In addition, it is preferable that the spacing between the distribution holes 411 is approximately half of the diameter of the distribution holes 411.

On the other hand, the present invention is provided with an exhaust gas sensor (not shown) in the rear end transfer duct (300; 300a) of the exhaust gas uniform distribution means 400, the exhaust gas detection sensor (not shown) When it is detected that the gas flows, the controller (not shown) outputs a control signal to drive the pump 170 and the circulation heater 500.

The pump 170 is driven by the control of a controller (not shown) to pump the urea in the urea water storage tank 150 to form the circulation heater 500 through the inlet 510 of the circulating heater 500. It is accommodated in the accommodation space 530. The urea water accommodated in the accommodating space 530 is moved to the injection means 600 by the pumping pressure through the discharge port 520 formed in the circulation heater 500, after which the urea water moves the injection means 600. Through the exhaust gas uniform distribution means 400 is injected in the same direction as the traveling direction of the exhaust gas in the particulate state in the transfer duct (300; 300a) corresponding to the exhaust gas flow region on the downstream side.

Here, the circulating heater 500 is operated simultaneously with the pump 170 by the control of a controller (not shown), the external power is applied to the electrode 540 installed therein so that the positive electrode is applied from the outside. do.

In this case, since the urea water accommodated in the accommodating space 530 of the circulation heater 500 is supplied with its own positive polarity, the positive electrode is further applied through the electrode rod 540. The movement of urea water becomes more active.

As described above, the urea water is passed through the circulating heater 500 to make the kinetic force more active, so that the urea water flows into the exhaust gas flow region on the downstream side of the exhaust gas uniform distribution means 400 in a particulate state through the injection means 600. When sprayed in the same direction as the traveling direction of the exhaust gas in the corresponding transfer duct 300, it is distributed in a state evenly distributed throughout the transfer duct 300 after passing through the uniform distribution means of the exhaust gas flows Very well mixed with the exhaust gases.

That is, in the present invention, the injection position of the urea water injected in the particulate state through the injection means 600 is a rear point of the uniform distribution of the exhaust gas 400, and the state is evenly distributed throughout the inside of the transfer duct 300. It is very well mixed with the exhaust gas which is distributed and flowed.

In this way, in order to implement the present invention, the present applicant, in addition to the configuration in which the injection means is installed at the rear point of the uniform distribution unit of the exhaust gas 400, the present inventors use the exhaust gas by another method for mixing the urea water in the particulate state and the exhaust gas. If it is made into turbulent conditions by means of a vortex generator or the like, and then the urea water in the particulate state is injected into the turbulent exhaust gas, the urea water is not sufficiently mixed with each other in the transfer duct. It was found out.

That is, since the flow of exhaust gas generated in the conveying duct by the vortex generator is in a vortex-shaped turbulent state, the inner space of the conveying duct and the part having no vortex exist. Therefore, the urea water injected into the conveying duct is separated and biased into a part with and without turbulence. As a result, the urea water and the exhaust gas are sufficiently in contact with each other to prevent mixing.

On the other hand, the present invention, as described above, while passing through the circulation heater 500 (+) ion particle movement is more active in the urea water storage tank 150 to the urea water to the particulate state through the injection means 600 Since the injection position of the urea water to be injected is to be the rear point 300a of the exhaust gas uniform distribution means 400, it is very mixed with the exhaust gas that is distributed evenly distributed throughout the inside of the transfer duct 300. In addition, the urea water in the turbulence forming means 700 to be described later becomes a factor that can facilitate the decomposition reaction to ammonia.

Then, as described above, after the urea water injected in the particulate state through the injection means 600 is sufficiently mixed with the exhaust gas on the downstream side of the exhaust gas uniform distribution means 400, it is discharged from the combustion device 100 The turbulent flow forming means 700 passes by the flow force of the exhaust gas.

That is, the mixed gas in which the urea water in the particulate state and the exhaust gas are mixed while passing through the turbulence forming means 700 becomes a turbulent state, whereby the urea in the particulate state is thermally decomposed by the thermal decomposition reaction of the exhaust gas. It is decomposed into ammonia through the same reaction as in formula (1).

[Formula 1]

NH ₂ CONH ₂ + H ₂ O → NH ₄ COONH ₂ + H ₂ O → 2NH ₃ + CO ₂ + H ₂ O

Preferred turbulent flow forming means 700 according to the present invention, the outer cylinder 710 is provided in the transfer duct 300, the rotating shaft 740 disposed in the axial direction in the inner center of the outer cylinder 710, Composed radially on the outer circumferential surface of the rotating shaft 740 is composed of a plurality of blades (750; 750a, 750b) fixed to the inner surface of the outer cylinder 710, a plurality of stages spaced apart at regular intervals in the transfer duct (300) Is installed.

That is, when the turbulence forming means 700 is installed in two stages, for example, spaced apart at a predetermined interval from the transfer duct 300, one of the two turbulence forming means 700 and the remaining one of the blades (750; 750a) The arrangement angles of the one blades 750 and 750b are different from each other, so that the turbulence generation directions of the mixed gas by the respective turbulence forming means 700 are different from each other.

For example, all of the blades 750a are installed obliquely on the rotation shaft 740, and all of the blades 750b are installed obliquely on the rotation shaft 740 so as to be different from the blades 750a. .

As described above, as the blades 750 and 750a and 750b rotate together with the rotating inner cylinder, the mixed gas becomes a turbulent flow, and then the exhaust gas discharged from the combustion device 100 along the transfer duct 300. Continued to move by the flow force flows into the inlet 211 of the casing 210 constituting the catalytic reaction tower 200, and then passes through the multi-stage catalyst layer (220; 220a, 220b, 220c) to reduce the nitrogen oxides After the treatment, it is discharged through the outlet portion 211 of the casing 210 constituting the catalytic reaction tower 200.

Here, the bearing means which is a means for enabling the rotating inner cylinder to rotate relative to the outer cylinder 710 in the configuration of the turbulence forming means 700 may use a bearing as a conventional means, the inner cylinder 710 and the inner rotation Of course, the contact surface of the cylinder can be filled with a fluid such as oil that can reduce the mutual friction.

On the other hand, the present invention is the turbulence forming means 700 is a mixture of ammonia and exhaust gas having an irregular flow velocity in the turbulent state of the inlet portion 211 of the casing 210 constituting the catalytic reaction tower 200 After flowing through, the flow rate changing means 900 is installed in the casing 210 so that the flow rate of the exhaust gas is constant before passing through the first catalyst bed.

In the preferred flow rate changing means 900 of the present invention, the casing 210 between the first catalyst layer 220a and the inlet portion 211 is installed horizontally corresponding to the inlet portion 211, and the inlet portion As the mixed gas of the turbulent state introduced through the (211) collides with a resistor 910 for reducing the flow of the turbulent state, the resistor 910 is introduced through the inlet 211, the exhaust exhausted Mixed gas passage holes through which some of the gas passes are arranged at regular intervals, and the resistor 910 has the remaining of the mixed gas introduced through the inlet 211 and the inner surface of the casing 210 and the resistor. A bypass flow path BP is formed between the inner surface of the casing 210 and the edge of the resistor 910 so as to branch flow between the edge portions of the 910.

The resistor 910 of the present invention may be formed in a substantially plate shape, but may have any structure as long as it has a mixed gas through hole. After arranging longitudinal frames having a cross section at regular intervals, a transverse frame 913 having a substantially "대략" shaped cross section having a mixed gas guide surface 913a inclined on the outer surface thereof is provided at the vertices of the vertical frame 912. Arranged at regular intervals so as to be orthogonal to the portion of the attachment (912b) corresponding to the configuration by combining them by a joining method such as welding.

That is, when the two-layer laminated structure of the vertical frame 912 and the transverse frame 913 intersect with each other, the above-described mixed gas passage hole 911 is formed therebetween.

Here, reference numeral 914 denotes a connecting support for installing the resistor 910 including the vertical frame 912 and the horizontal frame 913 in the inner space of the casing 210.

The area of the resistor 910, which is the flow rate changing means 900 of the present invention, is approximately 1.5 to 2 times the area of the passage of the inlet 211, that is, larger than the passage size of the inlet 211. desirable.

In addition, the vertical frame 912 and the horizontal frame 913 constituting the resistor 910 of the present invention are not limited to the number thereof, and the passage size of the mixed gas passage hole 911 is reduced and the passage hole ( A large number of vertical frames 912 and horizontal frames 913 may be used to increase the number of 911.

As described above, the reason for installing the flow rate changing means 910 in the present invention is that the turbulent flow forming means 700 catalyzes the mixed gas of ammonia and exhaust gas having an irregular flow rate in turbulent state by the catalytic reaction tower 200. When passing through the catalyst layer 220, the flow rate of the flow in the entire catalytic reaction tower 200 is not uniform, so that the reaction of the mixed gas with the catalyst layer is not made smoothly, since the reduction efficiency of the nitrogen oxide is reduced in the end It is to change the flow rate of the mixed gas having an irregular flow rate in the turbulent state before passing through the first catalyst layer 220a.

That is, if the flow rate of the mixed gas is constant before passing through the first catalyst layer 220a, and the flow state is changed to be regular, the first gas is contacted with the catalyst layer 220a with an even distribution. The reaction efficiency can be improved.

On the other hand, when the flow rate change means 910 is not installed, the mixed gas flowing into the turbulent state through the inlet portion 211 protruding from the upper center of the casing 210 is the first catalyst layer 220a corresponding to the bottom. Only in the central portion of the c) and the contact reaction, but not reach the portion of the Gaza except for the central portion of the first catalyst layer (220a) as well as in the space of the casing 210 between the first catalyst layer (220a) and the inlet portion (211) The flow rate of the mixed gas flow rate turbulent flow becomes uneven.

Accordingly, the present invention forms an atmosphere in which the flow rate of the exhaust gas is uniform to some extent in the space of the casing 210 between the first catalyst layer 220a and the inlet portion 211, and the entire first catalyst layer 220a. The even distribution allows the mixed gases to contact each other.

As described above, the reaction efficiency with the first catalyst layer 220a is increased to increase the reduction efficiency of nitrogen oxide contained in the mixed gas primarily, and in the remaining two catalyst layers 220b and 220c installed at the lower stage, By reacting with the remaining untreated nitrogen oxide it is possible to reduce the emission concentration of the nitrogen oxide contained in the exhaust gas finally discharged from the outlet 212.

That is, the nitrogen oxide is reduced to nitrogen and H 2 O by the reaction as shown in Formula 2 or Formula 3 below.

(2)

4N0 + 4NH ₃ + O ₂ → 4N ₂ + 6H ₂ O

[Formula 3]

NO + N0 ₂ + 2NH ₃ → 2N ₂ + 3H ₂ O

The present invention described so far has been described using an example of using urea water as a reducing agent.

However, the present invention can use ammonia water by storing ammonia water instead of urea water stored in the urea water storage tank 150 without changing the configuration of the system of the present invention described above. When the ammonia water is stored and used in the storage tank 150 as described above, the decomposition reaction of urea water-> ammonia does not occur, but the reduction efficiency of nitrogen oxide is improved as in the case of using urea water as a reducing agent.

That is, when passing through the above-described turbulence generating means 700 region, since the urea water is decomposed and then reacted with ammonia, since the same will have the same effect as when using urea water as a reducing agent. Will be omitted.

On the other hand, in the embodiment of the present invention is connected to the inside of the connection portion 300b of the transfer duct 300 connected to the exhaust gas 100 is rotatably installed via a hinge axis is installed to open and close the internal flow path of the transfer duct 300 The first damper 800 and one end 810a are installed to branch from the connection portion between the exhaust gas 100 and the transfer duct 300 and the outlet portion 212 of the casing 210 is disposed at the middle portion 810b. Branch duct 810, which is installed to communicate with each other, a second damper 820 rotatably installed via a hinge shaft to open and close its flow path in the branch duct 810, and an outlet of the casing 210. 312 may further include a third damper 830 rotatably installed through the hinge shaft to open and close the flow path at the distal end thereof.

The reason for having the above structure further is as follows.

First, when the exhaust gas is to flow into the normal flow path, that is, the transfer duct 300, the first damper 800 is opened, the second damper 820 is closed, and the third damper 830 is operated. ) Open operation.

However, in case of an emergency in which the system is stopped, such as the operation of the pump 170 and the circulation heater 500, which are the components of the present invention, the exhaust gas discharged from the combustion device 100 is transferred to the inside of the transfer duct 300. Bar flow should be blocked, so that the first damper 800 is closed, the second damper 820 is opened, and the third damper 830 is closed.

In the present invention, a dust collecting facility (not shown) is provided at the rear end of the branch duct 810 to collect exhaust gas as a post-treatment means.

 On the other hand, the composite nitrogen oxide treatment system according to the present invention has been described according to a limited embodiment, but the scope of the present invention is not limited to the specific embodiment, the scope obvious to those of ordinary skill in the art related to the present invention Various alternatives, modifications and changes can be made within the implementation.

Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by the embodiments and the accompanying drawings. . The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

100: combustion device
110: discharge duct
150: storage tank
170: pump
200: catalytic reaction tower
220: catalyst layer
221: Bead Catalyst
230: steam injection means
300: transfer duct
400: uniform distribution of exhaust gas
500: circulation heater
600: injection means
700: turbulence forming means
900: flow rate change means

Claims (6)

As a system for reducing the nitrogen oxide contained in the exhaust gas discharged from the combustion device 100,
A non-selective catalytic reduction device for primarily reducing nitrogen oxide using a reducing agent through a non-selective catalytic reduction method;
And a selective catalytic reduction device for secondaryly reducing nitrogen oxide using a reducing agent through a selective catalytic reduction method. The method according to claim 1,
The non-selective catalytic reduction device is a composite nitrogen oxide processing system, characterized in that the reducing agent injection means 101 for injecting any one of the reducing agent of urea water and ammonia water to the combustion device (100). The method according to claim 2,
The reducing agent is a composite nitrogen oxide treatment system, characterized in that any one of the additives of hydrocarbons and alcohols. The method according to claim 2,
The reducing agent injection means 101 is a composite nitrogen oxide processing system, characterized in that it is installed so as to inject the reducing agent at a position spaced apart from the combustion chamber of the combustion device (100). The method according to claim 1,
The selective catalytic reduction device,
Urea water storage tank 150 is stored as a reducing agent;
A pump 170 for pumping and transporting the urea water in the urea water storage tank 150;
A casing 210 having an inlet portion 211 installed at an upper center and an outlet portion 212 provided at a lower side thereof, and having bead-shaped catalysts 221 disposed inside the casing 210 and having minute pores. Catalytic reaction tower 200 consisting of a multi-stage catalyst layer 220;
Steam injection means 230 for washing the fine dust in the bead-type catalyst (221) by injecting a steam at a high temperature and high pressure between the multi-stage catalyst layer 220;
One end is installed to communicate with the end of the discharge duct 110, the other end is installed to be in communication with the inlet 211 of the casing 210 to transfer the exhaust gas into the casing 210 ( 300);
In one end side of the transfer duct 300, the exhaust gas uniform distribution means for distributing the exhaust gas to be uniformly flows in the transfer duct (300);
It has an inlet 510 through which the urea water pumped into the pump 170 is introduced, and an outlet 520 through which the introduced urea water is discharged, and has an accommodating space 530 therein temporarily containing the urea water. A circulation heater 500 installed in the accommodation space 530 so as to be immersed in the urea water and having an electrode rod 540 electrically connected to a positive electrode from the outside;
The urea water discharged from the discharge port 520 of the circulation heater 500 into the transfer duct 300 corresponding to the exhaust gas flow region on the downstream side of the uniform distribution means 400 of the exhaust gas in the particulate state of the exhaust gas. Injection means 600 for injecting in the same direction as the traveling direction;
It is installed in the conveying duct 300 corresponding to the downstream side of the injection means 600 to form a turbulent state of the urea in the form of exhaust gas and particulates that have passed through the exhaust gas uniform distribution means 400 Turbulence forming means 700 for causing the water to be decomposed into ammonia;
The casing 210 before passing through the first catalyst layer 220a after the mixed gas of ammonia and exhaust gas having an irregular flow velocity in turbulent flow by the turbulence forming means 700 flows in through the inlet portion 211. And a flow rate changing means (900) installed in the tank so that the flow rate of the exhaust gas becomes constant. The method according to claim 1,
The selective catalytic reduction device,
An ammonia water storage tank 150 in which ammonia water is stored as a reducing agent;
A pump 170 for forcibly pumping and transporting the ammonia water in the ammonia water storage tank 150;
A casing 210 having an inlet portion 211 installed at an upper side and an outlet portion 212 provided at a lower side thereof, and a multistage having bead catalysts 221 disposed inside the casing 210 and having minute pores. A catalytic reaction tower (200) consisting of a catalyst layer (220) of the;
Steam injection means 230 for washing the fine dust in the bead-type catalyst (221) by injecting a steam at a high temperature and high pressure between the multi-stage catalyst layer 220;
One end is installed to communicate with the end of the discharge duct 110, the other end is installed to be in communication with the inlet 211 of the casing 210 to transfer the exhaust gas into the casing 210 ( 300);
In one end side of the transfer duct 300, the exhaust gas uniform distribution means for distributing the exhaust gas to be uniformly flows in the transfer duct (300);
It has an inlet port 510 through which the ammonia water pumped and transported to the pump 170 is introduced, and an outlet port 520 through which the introduced ammonia water is discharged. A circulation heater 500 installed in the accommodation space 530 so as to be immersed in the ammonia water and having an electrode rod 540 electrically connected to a positive electrode from the outside;
Progression of the exhaust gas in the form of fine particles of ammonia water discharged from the outlet 520 of the circulation heater 500 into the transfer duct 300 corresponding to the exhaust gas flow region on the downstream side of the exhaust gas uniform distribution means 400. Injection means 600 for injecting in the same direction as the direction;
Turbulent flow forming means which is installed in the transfer duct 300 corresponding to the downstream side of the injection means 600 to form a turbulent state of the exhaust gas and the particulate ammonia water that has passed through the exhaust gas uniform distribution means 400 ( 700);
The casing 210 before passing through the first catalyst layer 220a after the mixed gas of ammonia and exhaust gas having an irregular flow velocity in turbulent flow by the turbulence forming means 700 flows in through the inlet portion 211. And a flow rate changing means (900) installed in the tank so that the flow rate of the exhaust gas becomes constant.

Images