KR102473276B1 - Selective catalytic reduction system - Google Patents

Abstract

The present invention relates to a selective catalytic reduction system for reducing nitrogen oxides contained in exhaust gas discharged from an engine, and a selective catalytic reduction system according to an embodiment of the present invention is for reducing nitrogen oxides contained in the exhaust gas A reactor with a built-in catalyst, a soot blower for injecting a fluid toward the catalyst to remove foreign substances caught in the catalyst or regenerating the catalyst, an air supply unit for supplying compressed air to the soot blower, and the engine and a control unit for adjusting the pressure of the air injected by the soot blower according to load fluctuations.

Description

Selective catalytic reduction system {SELECTIVE CATALYTIC REDUCTION SYSTEM}

The present invention relates to a selective catalytic reduction system used to reduce nitrogen oxides (NOx) contained in exhaust gas.

As industrialization progresses rapidly, the use of various fossil fuels such as petroleum and coal has increased. As a result, various harmful gases discharged during the combustion of fossil fuels cause serious air pollution. Representative examples include smog and acid rain.

The main cause of air pollution is sulfur oxides (SOx) or nitrogen oxides (NOx) of exhaust gas discharged from engines of vehicles and ships or thermal power plants or factories. In recent years, as awareness of environmental preservation has increased, emission regulations for these sulfur oxides and nitrogen oxides have been introduced. In particular, as a representative facility for reducing nitrogen oxides, there is a selective catalytic reduction (SCR) system. The selective catalytic reduction system reacts nitrogen oxides contained in the exhaust gas with a reducing agent while passing the exhaust gas and the reducing agent together through a reactor in which a catalyst is installed to reduce nitrogen and water vapor.

When such a selective catalytic reduction system is used in a ship, the emission of nitrogen oxides (NOx) emitted from a marine diesel engine complies with the International Maritime Organization's International Air Pollution Control Third Regulation (IMO Tier-III). not only must be satisfied, but also separate energy is consumed for the operation of the selective catalytic reduction system, so an effective operation method with a low-cost and high-efficiency denitrification facility is required.

In addition, a supercharger is widely used in a marine or vehicle power unit to supply new outside air to the engine by turning a turbine with pressure of exhaust gas discharged from the engine to improve engine efficiency. The temperature and pressure of the exhaust gas passing through the supercharger are lowered.

In this way, when a supercharger is used, the selective catalytic reduction system includes a method of arranging a reactor having a catalyst for reducing nitrogen oxides installed therein at the rear of the supercharger and a method of disposing the reactor in front of the supercharger, that is, between the engine and the supercharger. divided by way

When the reactor with a built-in catalyst is placed in front of the supercharger, that is, between the engine and the supercharger, the reduction reaction occurs when the temperature of the exhaust gas discharged from the engine is relatively high compared to the case where the reactor is placed behind the supercharger. this will happen As a result, the activity of the catalyst is increased to reduce the amount of catalyst required to reduce nitrogen oxides, but on the contrary, the temperature and pressure of the exhaust gas flowing into the supercharger are reduced, resulting in a decrease in engine performance and efficiency.

In addition, in the engine, combustion products such as soot generated by incomplete combustion of fuel are discharged together with exhaust gas. The soot moves along with the exhaust gas, attaches to the catalyst, and deteriorates the performance of the catalyst. When accumulated for a long time, the soot blocks the catalyst, narrowing or blocking the passage of the exhaust gas, thereby increasing the internal pressure of the reactor in which the catalyst is installed. Accordingly, by regularly spraying compressed air to the catalyst using a soot blower, foreign substances including soot caught in the catalyst are physically removed.

However, when the reactor is disposed in front of the supercharger, the reactor is not only exposed to a relatively high-pressure environment, but also has relatively severe pressure fluctuations. For example, the pressure of a reactor disposed in front of a supercharger varies from about 1 to 5 Bar depending on the load of the engine. As described above, when the load of the engine changes, the combustion state of the engine also changes, and thus the degree of generation of soot also changes. For example, the amount of soot generated may further increase when the engine is operated under high load.

In such a situation where the load of the engine fluctuates, if the pressure of the air injected by the soot blower is set to be constant based on the amount of soot generated during the high-load operation of the engine, air is unnecessarily consumed during low-load operation. In addition, if high-pressure air is blown through the soot blower for a long period of time, the catalyst may be damaged or the durability of the catalyst may be shortened.

Conversely, if the pressure of the air injected by the soot blower is set constant based on the amount of soot generated during low-load operation of the engine, all soot generated during high-load operation cannot be processed and the internal pressure of the reactor exceeds the allowable pressure. An escalating situation may occur. As such, when the internal pressure of the reactor is excessively increased, performance of the selective catalytic reduction system may be deteriorated as well as performance of the engine for discharging exhaust gas may be deteriorated.

The embodiment of the present invention not only minimizes the consumption of air by adjusting the pressure of the air injected by the soot blower according to the load variation of the engine, but also the high-pressure air injected from the soot blower damages the catalyst or Provided is a selective catalytic reduction system capable of suppressing the shortening of the durability life.

According to an embodiment of the present invention, a selective catalytic reduction system for reducing nitrogen oxides contained in exhaust gas discharged from an engine includes a reactor in which a catalyst for reducing nitrogen oxides contained in the exhaust gas is built-in, and the catalyst A soot blower for injecting fluid toward the catalyst to remove trapped foreign matter or regenerate the catalyst, an air supply unit for supplying compressed air to the soot blower, and the soot according to load fluctuations of the engine. It includes a control unit that adjusts the pressure of the air blown by the blower.

The control unit lowers the pressure of the air supplied to the soot blower as the load of the engine decreases within a preset maximum pressure and minimum pressure range, and increases the pressure of the air supplied to the soot blower as the load of the engine increases. can

The selective catalytic reduction system may further include a regulator installed on an air movement path between the air supply unit and the soot blower.

The controller may directly receive load information from the engine.

In addition, the control unit controls the performance of the engine through at least one of an exhaust pressure of exhaust gas discharged from the engine, a scavenging pressure of air supplied to the engine, a rotational speed of the engine, and a flow rate of exhaust gas discharged from the engine. Load can be calculated indirectly.

And the selective catalytic reduction system includes a first pressure sensor for measuring the exhaust pressure of the exhaust gas discharged from the engine, a second pressure sensor for measuring the scavenging pressure of the air supplied to the engine, and measuring the rotational speed of the engine. It may further include at least one of an engine rotation speed sensor that measures a flow rate of exhaust gas discharged from the engine, and a flow rate sensor.

Exhaust gas passing through the reactor is discharged through a supercharger, and the control unit may indirectly calculate the load of the engine through at least one of a pressure at the front end of the supercharger and a rotational speed of the supercharger.

And the selective catalytic reduction system may further include at least one of a supercharger front pressure sensor for measuring the pressure at the front end of the supercharger and a turbocharger rotation speed sensor for measuring the rotation speed of the supercharger.

The control unit may correct the indirectly calculated load of the engine by reflecting the temperature and humidity information of the atmosphere.

The control unit receives load information directly from the engine, and the control unit may compare and review the load information directly received from the engine with the indirectly calculated load information of the engine.

According to an embodiment of the present invention, the selective catalytic reduction system not only minimizes the consumption of air by adjusting the pressure of the air injected from the soot blower according to the load variation of the engine, but also the high-pressure air injected from the soot blower. can prevent damaging the catalyst or shortening the service life of the catalyst.

1 is a block diagram showing a selective catalytic reduction system according to an embodiment of the present invention.
2 is a graph showing a change in pressure of air injected by a soot blower in an experimental example according to an embodiment of the present invention.
3 is a graph showing a change in pressure of air injected by a soot blower in a comparative example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. This invention may be embodied in many different forms and is not limited to the embodiments set forth herein.

It is advised that the drawings are schematic and not drawn to scale. Relative dimensions and proportions of parts in the drawings are shown exaggerated or reduced in size for clarity and convenience in the drawings, and any dimensions are illustrative only and not limiting. And like structures, elements or parts appearing in two or more drawings, like reference numerals are used to indicate like features.

The embodiments of the present invention specifically represent ideal embodiments of the present invention. As a result, various variations of the diagram are expected. Therefore, the embodiment is not limited to the specific shape of the illustrated area, and includes, for example, modification of the shape by manufacturing.

Hereinafter, a selective catalytic reduction (SCR) system 101 according to an embodiment of the present invention will be described with reference to FIG. 1 .

The selective catalytic reduction system 101 according to an embodiment of the present invention reduces nitrogen oxides (NOx) contained in exhaust gas discharged from the engine 100 .

As an example, the engine 100 may be a two-stroke low-speed diesel engine for a ship. However, an embodiment of the present invention is not limited to the above, and the engine 100 may be a 4-line medium-speed diesel engine. In addition, a plurality of engines 100 may be used, and in this case, a 2-stroke low-speed diesel engine and a 4-stroke medium-speed diesel engine may be mixed. At this time, the 2-stroke low-speed diesel engine may be used as a main power source for providing thrust to the ship, and the 4-stroke medium-speed diesel engine may be used for power generation or as an auxiliary power source.

In addition, the engine 100 is not necessarily limited to a vessel and may be a vehicle engine. In addition, various types of engines 100 known to those skilled in the art may be used.

In addition, in one embodiment of the present invention, some or all of the exhaust gas discharged from the engine 100 may pass through the supercharger 150. When the supercharger 150 is connected to the exhaust port of the engine 100 and turns the turbine 151 with the pressure of the exhaust gas of the engine 100, the compressor 152 compresses new external air to the engine 100 with that force. supply Thus, the efficiency of the engine 100 equipped with the supercharger 150 can be improved. The supercharger 150 and the engine 100 are connected through a scavenging line 620, and the air compressed by the supercharger 150 is supplied to the engine 100 through the scavenging line 620.

In addition, in one embodiment of the present invention, the exhaust gas discharged from the engine 100 has a temperature within the range of 200 degrees Celsius to 500 degrees Celsius, and the temperature of the exhaust gas can be lowered by passing through the supercharger 150. For example, the temperature of the exhaust gas passing through the supercharger 150 may be lowered to 150 degrees Celsius or more and less than 200 degrees Celsius, and may be even lower at the initial stage of operation of the engine 100 .

As shown in FIG. 1, the selective catalytic reduction (SCR) system 101 according to an embodiment of the present invention includes a reactor 300, a soot blower 410, an air supply unit 450, and a control unit. (700).

In addition, the selective catalytic reduction system 101 according to an embodiment of the present invention includes a regulator 430, an exhaust flow path 610, a scavenging line 620, a decomposition chamber 500, a reducing agent injection unit 510, And it may include a reducing agent supply unit 550.

In addition, the selective catalytic reduction system 101 according to an embodiment of the present invention includes a first pressure sensor 710, a second pressure sensor 720, an engine rotation speed sensor 730, a flow meter 750, and a supercharger front pressure One or more of a sensor 760 and a supercharger rotational speed sensor 770 may be further included.

The exhaust passage 610 moves exhaust gas containing nitrogen oxides (NOx). And the exhaust gas moving along the exhaust passage 610 is discharged to the outside via the reactor 300 to be described later. For example, the exhaust passage 610 may be connected to an exhaust port of the engine 100 to discharge exhaust gas discharged from the engine 100 .

The reactor 300 is installed on the exhaust passage 610 . That is, the reactor 300 receives exhaust gas containing nitrogen oxides (NOx) through the exhaust passage 610 . And the reactor 300 has a built-in catalyst 350 for reducing nitrogen oxides (NOx) contained in the exhaust gas. The catalyst 350 promotes the reaction of nitrogen oxides (NOx) contained in exhaust gas with a reducing agent to reduce nitrogen oxides (NOx) to nitrogen and water vapor.

In addition, in one embodiment of the present invention, the catalyst 350 installed inside the reactor 300 may be arranged in a multi-layered structure based on the moving direction of the exhaust gas. That is, the catalyst 350 may be provided in the form of a plurality of catalytic modules, and the plurality of catalytic modules may be disposed along the moving direction of the exhaust gas.

The catalyst 350 may be made of various materials known to those skilled in the art, such as zeolite, vanadium, and platinum. As an example, the catalyst 350 may have an activation temperature in the range of 200 degrees Celsius to 500 degrees Celsius. Here, the activation temperature refers to a temperature at which the catalyst 350 is not poisoned and can stably reduce nitrogen oxides. If the catalyst 350 reacts outside the activation temperature range, the catalyst 350 is poisoned and efficiency is reduced. For example, when a reduction reaction to reduce nitrogen oxides contained in exhaust gas occurs at a relatively low temperature of 150 degrees Celsius or more and less than 250 degrees Celsius, sulfur oxides (SOx) and ammonia (NH ₃ ) in the exhaust gas react As a result, catalyst poisoning substances are generated. Specifically, the poisoning substance that poisons the catalyst 350 may include at least one of ammonium sulfate ((NH ₄ ) ₂ SO ₄ ) and ammonium bisulfate (NH ₄ HSO ₄ ). These catalyst poisoning materials are adsorbed on the catalyst to lower the activity of the catalyst 350 . Since the catalyst poisoning material is decomposed at a relatively high temperature, that is, a temperature in the range of 350 degrees Celsius to 450 degrees Celsius, the poisoned catalyst 350 may be regenerated by raising the temperature of the catalyst 350 in the reactor 300 .

Also, in one embodiment of the present invention, the reactor 300 may be installed on the exhaust passage 610 ahead of the supercharger 150 . That is, the reactor 300 may be disposed between the engine 100 and the supercharger 150.

Hereinafter, in the present specification, "front" refers to an upstream direction based on the moving direction of exhaust gas, and "rear" refers to a downstream direction based on the moving direction of exhaust gas.

The decomposition chamber 500 is installed on the exhaust passage 610 in front of the reactor 300. The decomposition chamber 500 forms a space for decomposition and vaporization of the reducing agent, and may be omitted depending on the type of the selective catalytic reduction system 101.

The reducing agent injection unit 510 may be installed in the decomposition chamber 500, the exhaust passage 610 in front of the reactor 300, or the front end of the reactor 300 to inject the reducing agent. For example, the reducing agent injection unit 510 may inject urea (CO(NH ₂ ) ₂ ) in the form of an aqueous solution to the exhaust gas moving along the exhaust passage 610 .

In one embodiment of the present invention, the urea (urea, CO (NH ₂ ) ₂ ) aqueous solution injected by the reducing agent spraying unit 510 corresponds to the reducing agent precursor, and urea is thermally decomposed or hydrolyzed to ammonia (NH ₃ ) and iso Isocyanic acid (HNCO) is produced, and isocyanic acid (HNCO) can be decomposed into ammonia (NH ₃ ) and carbon dioxide (CO ₂ ). Finally, ammonia (NH ₃ ) is used as a reducing agent to reduce nitrogen oxides (NOx) contained in exhaust gas.

The reducing agent supply unit 500 supplies the reducing agent to be injected by the reducing agent injection unit 510 . Since the amount of exhaust gas discharged from the engine 100 varies according to the load variation of the engine 100, the amount of a reducing agent required to reduce nitrogen oxides contained in the exhaust gas also varies. Accordingly, the reducing agent supply unit 500 may adjust the supply amount of the reducing agent so that an appropriate amount of the reducing agent may be supplied according to the operating conditions of the engine 100 or exhaust gas discharge conditions. In addition, the reducing agent supply unit 500 may provide information on the supply flow rate of the reducing agent to the control unit 700 to be described later.

Specifically, the reducing agent supply unit 500 includes a reducing agent storage tank for storing the reducing agent to be supplied to the reducing agent injection unit 510, a reducing agent supply pump module for supplying the reducing agent stored in the reducing agent storage tank, a flowmeter for measuring the supply flow rate, and A reducing agent supply line for moving the reducing agent may be included. Here, the reducing agent supply pump module may include a pump for supplying the reducing agent, a filter necessary for installing the pump, a pressure gauge for the pump, and a manual valve for the pump.

A soot blower 410 is inserted into the reactor 300 and is installed to inject compressed air toward the catalyst 350. In addition, the soot blower 410 may be a lance (1ance) type, but is not limited thereto in one embodiment of the present invention, and the soot blower 410 may be formed in various shapes. The soot blower 410 receives compressed air from an air supply unit 450 to be described later and injects the compressed air toward the catalyst 350 of the reactor 300. Air injected from the soot blower 410 may physically remove foreign substances caught in the catalyst 350 . Here, foreign substances include combustion products such as soot generated by incomplete combustion of fuel in the engine 100 . These foreign substances move along with the exhaust gas, attach to the catalyst 350, degrade the performance of the catalyst 350, and when accumulated for a long time, block the catalyst 350, narrowing or blocking the passage of exhaust gas, is to increase the internal pressure of the reactor 300 is installed. As such, if the internal pressure of the reactor 300 is excessively increased, performance and lifespan of the selective catalytic reduction system 101 may be deteriorated, as well as performance of the engine 100 for discharging exhaust gas may be deteriorated.

In addition, the air injected from the soot blower 410 may be used to regenerate the catalyst 350 by removing poisonous substances poisoning the catalyst 350 . Air blown from the soot blower 410 to regenerate the catalyst 350 may have a temperature at which catalyst poisoning substances can be decomposed.

In addition, in one embodiment of the present invention, the pressure of the air injected by the soot blower 410 is adjusted according to the control of the control device 700 to be described later.

The air supplier 450 may supply compressed air to the soot blower 410 . The air supply unit 450 may be configured in various ways known to those skilled in the art. For example, the supercharger 150 may be used as the air supply unit 450, or the air supply unit 450 may be one of a compressed air tank or a compressed air supply pump installed on a ship.

A regulator 430 may be installed on an air movement path between the air supply unit 450 and the soot blower 410 . The regulator 430 controls the pressure of the air supplied to the soot blower 410 by the air supply unit 450 . The control device 700, which will be described later, may control the air supply unit 450 or the regulator 430 to adjust the pressure of the air injected by the soot blower 410.

The first pressure sensor 710 may measure the exhaust pressure of the exhaust gas discharged from the engine 100 . Also, the second pressure sensor 720 may measure the scavenging pressure of the air supplied to the engine 100 .

The engine rotation speed sensor 730 may measure the rotation speed of the engine 100 . At this time, the engine rotation speed sensor 730 may be built into the engine 100 or installed on a rotation shaft of the engine 100 .

The flow meter 750 may measure the flow rate of the exhaust gas discharged from the engine 100 .

The pressure sensor 760 in front of the supercharger may measure the pressure in front of the supercharger 150, that is, the pressure of the exhaust gas flowing into the supercharger 150. Also, the supercharger rotational speed sensor 770 may measure the rotational speed of the supercharger 150 . At this time, the supercharger rotational speed sensor 770 may be built into the supercharger 150 or installed on the rotational shaft of the turbine.

In one embodiment of the present invention, the first pressure sensor 710, the second pressure sensor 720, the engine rotation speed sensor 730, the flow meter 750, the supercharger front pressure sensor 760, and the supercharger rotation speed sensor One or more of 770 may be used, and the rest not used may be omitted.

The control unit 700 adjusts the pressure of the air injected by the soot blower 410 according to the load variation of the engine 100 . Specifically, the control unit 700 lowers the pressure of the air supplied to the soot blower 410 as the load of the engine 100 decreases within a predetermined maximum pressure and minimum pressure range, and as the load of the engine 100 increases, The pressure of air supplied to the soot blower 410 may be increased. Here, the preset maximum pressure and preset minimum pressure take into consideration the performance and specifications of the soot blower 410 and the amount of soot generated from the engine 100, as well as the overall performance of the selective catalytic reduction system 101 and the engine 100. ) can be set considering the effect on the performance of

When the load of the engine 100 increases, soot due to incomplete combustion increases in the exhaust gas discharged from the engine 100 . Therefore, in one embodiment of the present invention, as the load of the engine 100 increases, the pressure of the air injected by the soot blower 410 is increased to effectively remove foreign substances caught in the catalyst 350, and the load of the engine 100 increases. As the pressure decreases, the pressure of the air injected by the soot blower 410 may be lowered to minimize unnecessary consumption of air.

Also, the controller 700 may directly receive load information from the engine 100 . In addition, the control unit 700 controls the exhaust pressure of the exhaust gas discharged from the engine 100, the scavenging pressure of the air supplied to the engine 100, the rotational speed of the engine 100, and the exhaust gas discharged from the engine 100. The load of the engine 100 may be indirectly calculated through one or more of the flow rates of the exhaust gas. In addition, the controller 700 may indirectly calculate the load of the engine 100 through at least one of the pressure at the front end of the supercharger 150 and the rotational speed of the supercharger 150 .

The operating state of the engine 100, that is, the load information of the engine 100 can be calculated under various exhaust gas conditions. For each load of the engine 100, the scavenging gas and exhaust gas have different characteristics such as constant temperature, pressure, and flow rate, and exhibit a constant rotational speed for each load of the engine 100. In this way, the load of the engine 100 is correlated with the exhaust pressure, the scavenging pressure, the rotational speed of the engine 100, the flow rate of the exhaust gas, the pressure at the front end of the supercharger 150, and the rotational speed of the supercharger 150. , the load of the engine 100 can be calculated indirectly through these information. For example, when the pressure at the front end of the supercharger 150 is increased by the exhaust gas discharged from the combustion chamber of the engine 100, and the pressure at the front end of the supercharger 150 is increased, the supercharger 150 supplies to the engine 100 The air pressure, that is, the scavenging pressure, rises. An increase in pressure and scavenging pressure at the front end of the supercharger 150 means that the load of the engine 100 is relatively high, and a decrease in pressure and scavenging pressure at the front end of the supercharger 150 means that the load on the engine 100 is relatively low. means In addition, since the amount of exhaust gas discharged from the engine 100 varies according to the change in the load of the engine 100, the load of the engine 100 can be indirectly estimated by measuring the flow rate of the exhaust gas.

In addition, since the amount of exhaust gas from the engine 100 and the flow rate and pressure of the scavenged air are changed by the temperature and humidity of the atmosphere, the control unit 700 indirectly reflects information on the temperature and humidity of the air for more precise control. The calculated load of the engine 100 may be corrected.

In addition, it is most preferable that the control unit 700 directly receives load information from the engine 100, but if an error occurs in the engine 100 or an error occurs in the signal for the operating conditions of the engine 100, the engine ( An error may occur between the signal for the load information received from 100 and the load of the actual engine 100 .

Therefore, the control unit 700 indirectly calculates the load of the engine 100 from various factors generated by the actual operation of the engine 100, and compares the calculated load information with the load information directly transmitted from the engine 100. The current operating state of the engine 100 can be more accurately determined by cross-examination.

That is, according to an embodiment of the present invention, the control unit 700 may use only one method among several methods for determining the operating state of the engine 100, but each of the engine 100 It is possible to more accurately determine the load of the engine 100 by grasping the operating state and comparing and reviewing them.

As described above, the control unit 700 grasps the load information of the engine 100, and when the engine 100 is in a low load state, relatively lowers the pressure of the air injected by the soot blower 410, and the engine 100 In this high load state, by relatively increasing the pressure of the air blown by the soot blower 410, consumption of the air blown by the soot blower 410 is minimized, and when high-pressure air is blown for a long period of time, the catalyst 350 It is possible to suppress damage or shortening of the durability life of the catalyst 350, and to prevent performance degradation of the selective catalytic reduction system 101 and performance degradation of the engine 100.

With this configuration, the selective catalytic reduction system 101 according to an embodiment of the present invention minimizes air consumption by adjusting the pressure of the air injected by the soot blower 410 according to the load variation of the engine 100. In addition, it is possible to suppress the high-pressure air injected from the soot blower 410 from damaging the catalyst 350 or shortening the durability life of the catalyst 350 . In addition, performance degradation of the selective catalytic reduction system 101 and performance degradation of the engine 100 can be prevented.

Hereinafter, with reference to FIG. 2, an experimental example and a comparative example according to an embodiment of the present invention will be compared and examined.

2 shows the pressure change of the exhaust gas and the pressure change of the air injected by the soot blower according to the load change of the engine in the experimental example. As shown in FIG. 2, the difference P1 between the pressure of the exhaust gas and the pressure of the air injected by the soot blower when the engine operates at a high load is the pressure of the exhaust gas and the air injected by the soot blower when the engine operates at a low load. is very similar to or equal to the difference (P2) between the pressures of

3 shows the pressure change of the exhaust gas and the pressure change of the air injected by the soot blower according to the load change of the engine in the comparative example. However, in the comparative example, the soot blower sprays air at a constant pressure. That is, as shown in FIG. 3, even if the pressure of the exhaust gas changes due to the change in the load of the engine, the pressure of the air injected by the soot blower does not change. In addition, the pressure of the air injected by the soot blower is set based on the relatively large amount of soot generated during high-load operation of the engine.

Therefore, the difference between the pressure of the exhaust gas and the pressure of the air injected by the soot blower (P4) is greater than the difference (P3) between the pressure of the exhaust gas and the pressure injected by the soot blower when the engine is operating at a high load. It can be seen that it is much larger. That is, in the experimental example, air consumption can be reduced by the area indicated by dots in FIG. 3 compared to the comparative example.

In addition, in the experimental example, since the pressure of the air injected by the soot blower is not always maintained high, the catalyst can be prevented from being damaged by the high-pressure air.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art to which the present invention pertains can understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. will be.

Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting, and the scope of the present invention is indicated by the following detailed description of the claims, the meaning and scope of the claims, and All changes or modified forms derived from the equivalent concept should be construed as being included in the scope of the present invention.

100: engine
101: selective catalytic reduction system
150: supercharger
151: turbine
152: compressor
300: reactor
350 Catalyst
410: soot blower
430: regulator
450: compressed air supply
500: decomposition chamber
510: reducing agent injection unit
550; reducing agent supply
610: exhaust flow path
620: scavenging line
700: control unit
710: first pressure sensor
720: second pressure sensor
730: engine rotation speed sensor
750: flow meter
760: supercharger shear pressure sensor
770: Supercharger rotational speed sensor

Claims (10)

In the selective catalytic reduction system for reducing nitrogen oxides contained in exhaust gas discharged from an engine,
a reactor having a built-in catalyst for reducing nitrogen oxides contained in the exhaust gas;
a soot blower injecting a fluid toward the catalyst to remove foreign substances caught in the catalyst or to regenerate the catalyst;
an air supply unit supplying compressed air to the soot blower; and
A control unit for adjusting the pressure of the air injected by the soot blower according to the load variation of the engine.
Including,
The controller determines the load of the engine through at least one of an exhaust pressure of exhaust gas discharged from the engine, a scavenging pressure of air supplied to the engine, a rotational speed of the engine, and a flow rate of exhaust gas discharged from the engine. calculated indirectly,
The control unit corrects the load of the engine indirectly calculated by reflecting the temperature and humidity information of the atmosphere. In the selective catalytic reduction system for reducing nitrogen oxides contained in exhaust gas discharged from an engine,
a reactor having a built-in catalyst for reducing nitrogen oxides contained in the exhaust gas;
a soot blower injecting a fluid toward the catalyst to remove foreign substances caught in the catalyst or to regenerate the catalyst;
an air supply unit supplying compressed air to the soot blower; and
A control unit for adjusting the pressure of the air injected by the soot blower according to the load variation of the engine.
Including,
The controller determines the load of the engine through at least one of an exhaust pressure of exhaust gas discharged from the engine, a scavenging pressure of air supplied to the engine, a rotational speed of the engine, and a flow rate of exhaust gas discharged from the engine. calculated indirectly,
The controller receives load information directly from the engine,
The selective catalytic reduction system wherein the control unit compares and reviews the load information directly transmitted from the engine and the load information of the engine indirectly calculated. According to claim 1 or 2,
a first pressure sensor for measuring exhaust pressure of the exhaust gas discharged from the engine;
A second pressure sensor for measuring the scavenging pressure of the air supplied to the engine:
an engine rotation speed sensor for measuring the rotation speed of the engine; and
A flow meter for measuring the flow rate of the exhaust gas discharged from the engine
Selective catalytic reduction system, characterized in that it further comprises one or more of. In the selective catalytic reduction system for reducing nitrogen oxides contained in exhaust gas discharged from an engine,
a reactor with a built-in catalyst for reducing nitrogen oxides contained in the exhaust gas;
a soot blower injecting a fluid toward the catalyst to remove foreign substances caught in the catalyst or to regenerate the catalyst;
an air supply unit supplying compressed air to the soot blower; and
A control unit for adjusting the pressure of the air injected by the soot blower according to the load variation of the engine.
Including,
Exhaust gas passing through the reactor is discharged through a supercharger,
The control unit indirectly calculates the load of the engine through at least one of the pressure at the front end of the supercharger and the rotational speed of the supercharger,
The control unit corrects the load of the engine indirectly calculated by reflecting the temperature and humidity information of the atmosphere. In the selective catalytic reduction system for reducing nitrogen oxides contained in exhaust gas discharged from an engine,
a reactor having a built-in catalyst for reducing nitrogen oxides contained in the exhaust gas;
a soot blower injecting a fluid toward the catalyst to remove foreign substances caught in the catalyst or to regenerate the catalyst;
an air supply unit supplying compressed air to the soot blower; and
A control unit for adjusting the pressure of the air injected by the soot blower according to the load variation of the engine.
Including,
The exhaust gas passing through the reactor is discharged through a supercharger,
The control unit indirectly calculates the load of the engine through at least one of the pressure at the front end of the supercharger and the rotational speed of the supercharger,
The controller directly receives load information from the engine,
The selective catalytic reduction system wherein the control unit compares and reviews the load information directly transmitted from the engine and the load information of the engine indirectly calculated. According to claim 4 or 5,
a pressure sensor at the front of the supercharger that measures the pressure at the front of the supercharger; and
Supercharger rotational speed sensor for measuring the rotational speed of the supercharger
Selective catalytic reduction system, characterized in that it further comprises one or more of. The method of any one of claims 1, 2, 4, and 5,
The controller lowers the pressure of the air supplied to the soot blower as the load of the engine decreases within a preset maximum pressure and minimum pressure range, and increases the pressure of the air supplied to the soot blower as the load of the engine increases. Selective catalytic reduction system, characterized in that. The method of any one of claims 1, 2, 4, and 5,
The selective catalytic reduction system further comprising a regulator installed on an air movement path between the air supply unit and the soot blower. delete delete

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