KR101461326B1 - Selective catalytic reduction system - Google Patents

Abstract

An embodiment of the present invention relates to a selective catalytic reduction system that includes: a main flow channel through which exhaust gas of an engine passes; a reactor which is arranged on the main flow channel and includes a catalyst installed therein; a circumvent flow channel which is branched from the main flow channel and circumvents the reactor; a first opening and closing member installed on the circumvent flow channel; a second opening and closing member which is installed on the main flow channel and switches flow of the exhaust gas entering the reactor; a third opening and closing member which is installed on a main exhaust pipe and switches flow of the exhaust gas, which has passed the reactor; a circulation flow channel which connects one point between the second opening and closing member and a font end of the reactor with the other point between the third opening and closing member and a rear end; a blower which is arranged between the reactor and the circulation flow channel and circulates the exhaust gas; and a heating part which increases the temperature of the exhaust gas passing the circulation flow channel.

Description

{SELECTIVE CATALYTIC REDUCTION SYSTEM}

An embodiment of the present invention relates to a selective catalytic reduction system, and more particularly, to a selective catalytic reduction system capable of effectively regenerating a catalyst installed inside a reactor.

Generally, in order to regenerate a catalyst used in a large facility such as a ship or a plant, the catalyst is withdrawn from the reactor and regenerated.

Specifically, the regeneration of the catalyst is carried out by withdrawing the catalyst from the reactor, performing a cleaning agent injection process, a cleaning process, a drying process, and a catalyst activator carrying process, and then installing the catalyst in the reactor again.

However, in the case of the regeneration method of the catalyst in which the catalyst is withdrawn from the reactor, it is not possible to regenerate the catalyst of the selective catalytic reduction system in operation because it is possible to stop the use of the selective catalyst reduction system. Since the cleaning agent spraying, cleaning, drying, and supporting of the catalyst activator are required, the process is complicated and requires a long time.

In addition, the selective reduction catalyst system used in a vehicle includes a catalyst particulate filter (CPF) installed at the upstream of the reactor. Such a catalyst particulate filter can be regenerated by injecting fuel into the catalyst particulate filter and burning particulate matters (PM) or unburned hydrocarbons (HC) filtered through the catalyst particulate filter.

However, the selective catalytic reduction system including the catalyst particulate filter has a problem that a space for installation is required because it requires a reactor that accommodates a catalyst particulate filter in addition to a reactor that accommodates a catalyst for reducing nitrogen.

An embodiment of the present invention provides a selective catalytic reduction system capable of effectively regenerating a catalyst located inside a reactor.

According to an embodiment of the present invention, a selective catalytic reduction system includes a main passage through which exhaust gas from an engine passes, a reactor disposed on the main passage and provided with a catalyst therein, A second opening and closing member provided on the main flow path for switching the flow of the exhaust gas flowing into the reactor and a second opening and closing member provided on the main exhaust pipe, A circulation flow path connecting one point between the second opening and closing member and the front end of the reactor and another point between the third opening and closing member and the rear end of the reactor; A blower for circulating the exhaust gas between the reactor and the circulating flow passage, and a blower for raising the temperature of the exhaust gas passing through the circulating flow passage And includes a heating portion.

Further, the first opening / closing member, the second opening and closing member, the third opening and closing member, the blower, and the heating unit may be separately operated in either of an exhaust purification operation or a catalyst regeneration operation.

The selective catalytic reduction system may further include a reducing agent injecting unit injecting a reducing agent into the exhaust gas passing through the main flow path during the exhaust purification operation.

In addition, the selective catalytic reduction system may be configured to open the first opening / closing member and close the second opening / closing member and the third opening / closing member when the catalyst regeneration operation is performed, operate the blower, operate the heating unit, And a control unit for closing the first opening and closing member and opening the second opening and closing member and the third opening and closing member and stopping the operation of the blower and the heating unit when the purifying operation is performed.

The selective catalytic reduction system may further include a first NOx sensor for detecting the NOx concentration at the upstream side of the reactor and a second NOx sensor for detecting the NOx concentration at the downstream side of the reactor, The NOx reduction efficiency calculated based on the NOx value detected from the first NOx sensor and the second NOx sensor may be compared with the set NOx efficiency value to determine whether the catalyst is poisoned.

Also, the controller may perform the catalyst regeneration operation when the calculated NOx reduction efficiency is lower than the set NOx efficiency value and the reference time passes.

The control unit may determine whether the NOx value detected from the first NOx sensor and the second NOx sensor is within a permissible range of the pre-input NOx reference value according to the load of the engine, It is possible to diagnose whether or not a failure occurs.

Further, the selective catalytic reduction system may further include a flow rate sensor for detecting a flow rate of the exhaust gas circulated by the blower, wherein the control unit divides the flow rate of the exhaust gas detected by the flow rate sensor by the volume of the catalyst The target flow rate value and the target temperature value of the catalyst regeneration operation can be determined by calculating the space velocity.

The control unit may compare the flow rate of the exhaust gas detected by the flow rate sensor during the catalyst regeneration operation with the target flow rate value, and when the flow rate of the exhaust gas detected by the flow rate sensor exceeds the target flow rate value, The operation can be terminated.

The selective catalytic reduction system may further include a temperature sensor for detecting the temperature of the exhaust gas heated by the heating unit, wherein the control unit controls the temperature of the exhaust gas detected by the temperature sensor, And the catalyst regeneration operation may be terminated when the temperature of the exhaust gas detected by the temperature sensor exceeds the target temperature value.

According to embodiments of the present invention, the selective catalytic reduction system can effectively regenerate the catalyst located inside the reactor.

1 illustrates a selective catalytic reduction system according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating a control procedure of a selective catalytic reduction system according to an exemplary embodiment of the present invention. Referring to FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

The drawings are schematic and illustrate that they are not drawn to scale. The relative dimensions and ratios of the parts in the figures are shown exaggerated or reduced in size for clarity and convenience in the figures, and any dimensions are merely illustrative and not restrictive. And to the same structural elements or parts appearing in more than one drawing, the same reference numerals are used to denote similar features.

The embodiments of the present invention specifically illustrate ideal embodiments of the present invention. As a result, various variations of the illustration are expected. Thus, the embodiment is not limited to any particular form of the depicted area, but includes modifications of the form, for example, by manufacture.

Hereinafter, a selective catalytic reduction 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 includes a main flow path 110, a reactor 200, a first opening and closing member 310, A third opening and closing member 500, a circulating flow path 600, a blower 710, and a heating unit 720.

The main flow channel 110 passes through the exhaust gas containing nitrogen oxide. Specifically, the main flow path 110 passes through the exhaust gas generated by the combustion of the diesel engine 100.

The reactor 200 is disposed on the main flow path 110. Also, the reactor 200 is disposed on the main flow path 110, and the exhaust gas passing through the main flow path 110 flows into the reactor 200.

Specifically, a catalyst 210 is installed in the reactor 200. The catalyst 210 may have various flow paths, such as honeycomb or corrugated shapes. In addition, the catalyst 210 may be formed in plural. The catalyst 210 reduces the nitrogen oxide contained in the exhaust gas through the reduction reaction.

The bypass channel 300 is branched from the main channel 110 to bypass the reactor 200. One end of the bypass passage 300 is connected to the main passage 110 at the front of the reactor 200 and the other end is connected to the main passage 110 at the rear of the reactor 200. Therefore, the exhaust gas can pass through the bypass 200 along the bypass channel 300. [

That is, one end of the bypass channel 300 is positioned forward of the first opening and closing member 310 and the other end is located behind the third opening and closing member 500.

The first opening and closing member 310 allows the flow of the exhaust gas to be switched to the bypass passage 300. The first opening and closing member 310 is installed on the bypass passage 300 and is selectively switchable.

The second opening and closing member 400 allows the flow of the exhaust gas flowing into the reactor 200 through the main flow path 110 to be switched.

Specifically, the second opening and closing member 400 may block the flow of the exhaust gas flowing into the reactor 200 by closing the main flow path 110 in front of the reactor 200. The second opening and closing member 400 may allow the exhaust gas to flow into the reactor 200 by opening the main flow path 110 in front of the reactor 200. That is, the second opening / closing member 400 can be selectively switched to switch the flow of the exhaust gas flowing into the reactor 200.

The third opening and closing member 500 allows the flow of the exhaust gas passing through the reactor 200 to be switched.

The third opening and closing member 500 may block the exhaust gas passing through the reactor 200 from being discharged to the outside through the main flow path 110 by closing the main flow path 110 behind the reactor 200 . The third opening and closing member 500 opens the main flow passage 110 in the rear of the reactor 200 and exhausts the exhaust gas passing through the reactor 200 to the outside through the main flow passage 110 in the rear of the reactor 200 . That is, the third opening and closing member 500 can be selectively switched to change the flow of the exhaust gas passing through the reactor 200.

The first opening / closing member 310, the second opening and closing member 400, and the third opening and closing member 500 may have various structures such as a damper or a valve.

The circulation flow passage 600 connects one point between the second opening and closing member 400 and the front end of the reactor 200 and another point between the third opening and closing member 500 and the rear end of the reactor 200.

Specifically, one end of the circulating flow passage 600 may be positioned between the second opening and closing member 400 and the front end of the reactor 200, and the other end may be positioned between the third opening and closing member 500 and the rear end of the reactor 200.

One end of the circulation channel 600 may be opened and closed by the second opening and closing member 400 and the other end may be opened and closed by the third opening and closing member 500.

That is, when the second opening and closing member 400 closes the main flow passage 110 in front of the reactor 200 and the exhaust gas flowing into the reactor 200 is switched to the bypass flow passage 300, one end of the circulation flow passage 600 Can be opened by the second opening and closing member (400). When the third opening and closing member 500 closes the main flow path 110 in the rear of the reactor 200 to switch the exhaust gas passing through the reactor 200 to the circulating flow path 600, Can be opened by the third opening / closing member (500). Accordingly, when the second opening and closing member 400 and the third opening and closing member 500 are closed, the exhaust gas can circulate through a closed loop formed by the reactor 200 and the circulating flow path 600.

The blower 710 circulates the exhaust gas between the reactor 200 and the circulating flow path 600. Specifically, the blower 710 provides power to circulate the exhaust gas between the reactor 200 and the circulating flow path 600 when the second opening and closing member 400 and the third opening and closing member 500 are closed .

In addition, the circulation flow of the exhaust gas between the reactor 200 and the circulating flow path 600 can be changed according to the rotating direction of the blower 710. The blower 710 may be installed inside the circulating flow path 600.

The heating unit 720 heats the exhaust gas passing through the circulation channel 600. Specifically, when the second opening and closing member 400 and the third opening and closing member 500 are closed, the heating unit 720 heats the exhaust gas passing through the circulating flow path 600, .

Further, the heating unit 720 may be located outside the circulation channel 600 to heat the circulation channel 600. Alternatively, the heating unit 720 may be located inside the circulation channel 600, and may directly heat the exhaust gas passing through the circulation channel 600 using a hot wire or a current-carrying device. The heating unit 720 according to an embodiment of the present invention is not limited thereto and can be modified into various heating apparatuses known to those skilled in the art.

With such a configuration, the selective catalytic reduction system according to an embodiment of the present invention can effectively regenerate the catalyst located inside the reactor.

Specifically, the selective catalytic reduction system 101 includes a third opening / closing member 500 for switching the flow of the exhaust gas passed through the reactor 200, so that the exhaust gas passing through the bypass channel 300 flows to the outside It can be prevented that it flows into the reactor 200 again before being discharged.

When the second opening and closing member 400 and the third opening and closing member 500 shut off the flow of the exhaust gas flowing into the reactor 200 and shut off the flow of the exhaust gas passing through the reactor 200, When the exhaust gas is heated by the heating unit 720 because the exhaust gas is circulated by forming the closed loop and the circulating flow path 600, the exhaust gas can be circulated while the heat loss is reduced, thereby effectively regenerating the catalyst.

According to an embodiment of the present invention, the heating unit 720 heats and regenerates the catalyst 210 by heating the exhaust gas circulated through the circulation channel 600 to be closed loop, The catalyst of the enlarged selective catalytic reduction system 101 can be effectively regenerated.

The first opening / closing member 310, the second opening and closing member 400, the third opening and closing member 500, the blower 710, and the heating unit 720 are either of an exhaust purification operation or a catalyst regeneration operation It can be operated separately.

That is, the first opening / closing member 310, the second opening and closing member 400, the third opening and closing member 500, the blower 710, and the heating unit 720 are opened and closed according to the exhaust purification mode and the catalyst regeneration mode And can be selectively operated.

With such a configuration, the selective catalytic reduction system according to an embodiment of the present invention can effectively regenerate the catalyst located inside the reactor.

That is, the first opening / closing member 310, the second opening and closing member 400, the third opening and closing member 500, the blower 710, and the heating unit 720 are effectively disposed in accordance with the exhaust purification operation or the catalyst regeneration operation. Can be selectively operated.

In addition, the selective catalyst reduction system 101 according to an embodiment of the present invention may further include a reducing agent spraying unit 730.

The reducing agent spraying part 730 injects the reducing agent into the exhaust gas passing through the main flow path 110. Accordingly, the injected reducing agent is mixed with the exhaust gas, flows into the reactor 200, and reacts with the catalyst 210 installed in the reactor 200 to generate NOx (hereinafter referred to as NOx) contained in the exhaust gas. ) Is reduced to N2 and H2O. That is, when the reducing agent injected by the reducing agent injecting unit 730 is mixed with the exhaust gas and passes through the catalyst 210 installed in the reactor 200, NOx contained in the exhaust gas is reduced to N2 and H2O, Cleanse.

The reducing agent injected from the reducing agent spraying part 730 of the present invention may use urea or ammonia (NH3). In addition, the reducing agent injected from the reducing agent spraying unit 730 of the embodiment of the present invention is not limited to urea water or ammonia, and may be modified into various structures known to those skilled in the art.

With such a structure, the selective catalytic reduction system 101 according to the embodiment of the present invention can effectively purify the exhaust gas.

Specifically, the reducing agent injected by the reducing agent injecting portion 730 is mixed with the exhaust gas to promote the reduction reaction of the catalyst 210 for reducing the nitrogen oxide, thereby effectively purifying the exhaust gas.

In addition, the selective catalytic reduction system 101 according to an embodiment of the present invention may further include a control unit 900.

The control unit 900 controls the first opening and closing member 310, the second opening and closing member 400, the third opening and closing member 500, the blower 710, and the heating unit 720).

When the catalyst regeneration operation is performed, the controller 900 opens the first opening / closing member 310 to allow the exhaust gas generated in the engine 100 to pass through the bypass passage 300. The control unit 900 closes the second opening and closing member 400 and the third opening and closing member 500 to block exhaust gas from entering the reactor 200, . The control unit 900 operates the blower 710 so that the exhaust gas can be circulated between the circulating flow path 600 and the reactor 200. The control unit 900 operates the heating unit 720 to circulate the exhaust gas The gas is heated to flow into the reactor 200.

For example, in the catalyst regeneration operation, the exhaust gas that has passed through the reactor 200 can not be discharged to the outside by the third opening / closing member 500, passes through the circulation passage 600, and then flows into the reactor 200 again. At this time, the exhaust gas passing through the circulation channel 600 is heated by the heating unit 720. Therefore, the catalyst 210 is heated by the exhaust gas heated by the heating unit 720 through the reactor 200, and the adsorbed ammonia is removed to regenerate the catalyst. That is, the catalyst 210 adsorbed by the ammonia adsorbed by the third opening / closing member 500 is heated to prevent the ammonia, which is harmful to the human body together with the exhaust gas, from being discharged to the outside of the selective catalytic reduction system 101. The exhaust gas generated by the combustion of the engine 100 is switched to the bypass flow path 300 by the first opening and closing member 310 and bypasses the reactor 200 and the engine 100, The exhaust gas generated by the combustion of the second open / close member 400 is restricted from flowing into the reactor 200.

When the exhaust purification operation is performed, the controller 900 closes the second opening and closing member 400 to restrict the exhaust gas from flowing into the bypass passage 300. The control unit 900 opens the second opening and closing member 400 and the third opening and closing member 500 to allow the exhaust gas to flow into the reactor 200 through the main flow path 110. Then, the control unit 900 stops the operation of the blower 710 and stops the operation of the heating unit 720.

The selective catalytic reduction system according to an embodiment of the present invention can effectively regenerate the catalyst located inside the reactor.

That is, the control unit 900 controls the first opening / closing member 310, the second opening and closing member 400, the third opening and closing member 500, the blower 710, And controls the heating unit 720.

When the catalyst regeneration operation is performed by the control unit 900, the exhaust gas generated during operation of the engine 100 is discharged through the bypass flow path 300 bypassing the reactor 200, The exhaust gas between the circulating flow paths 600 is circulated by the blower 710 and the temperature of the exhaust gas heated by the heating unit 720 is raised to raise the temperature of the catalyst 210 so that ammonia adsorbed on the catalyst 210 is effectively removed Thereby regenerating the catalyst 210.

That is, since the catalyst 210 is regenerated by the catalyst regeneration operation, the service life and replacement period of the catalyst 210 can be increased. Therefore, the complicated processes such as the cleaning liquid injection, cleaning, drying, and catalyst activator supporting process, which are conventionally required for catalyst regeneration, and the process of withdrawing the catalyst from the reactor for this process are significantly reduced, .

Further, the number of parts can be reduced because a separate catalyst particle filter used conventionally is not needed. By reducing the number of components, the selective catalytic reduction system 101 can be compactly installed, thus enabling efficient utilization of space.

In addition, the selective catalytic reduction system 101 according to an embodiment of the present invention may further include a first NOx sensor 910 and a second NOx sensor 920.

The first NOx sensor 910 detects the NOx concentration at the front end of the reactor 200. Specifically, the first NOx sensor 910 detects the NOx concentration contained in the exhaust gas before entering the reactor 200.

In addition, the first NOx sensor 910 may be installed at one side of the main flow path 110 in front of the reactor 200.

The second NOx sensor 920 detects the NOx concentration at the rear end of the reactor 200. Specifically, the second NOx sensor 920 detects the concentration of NOx contained in the exhaust gas that has passed through the reactor 200. In addition, the second NOx sensor 920 may be installed at one side of the main flow path 110 in the rear of the reactor 200.

Therefore, the control unit 900 calculates the NOx reduction efficiency from the NOx value detected by the first NOx sensor 910 and the second NOx sensor 920. [ In addition, it is determined whether or not the catalyst 210 is poisoned by comparing it with the NOx efficiency value set in the controller 900.

Specifically, the control unit 900 stores a threshold value of NOx reduction efficiency. Accordingly, the controller 900 determines that the catalyst 210 is poisoned when the calculated NOx reduction efficiency is less than the stored NOx reduction efficiency threshold. The threshold value of the NOx reduction efficiency may be the lowest NOx reduction efficiency set so that the catalyst 210 can maintain normal performance. In addition, the poisoning of the catalyst 210 is a state in which the performance of the catalyst 210 is deteriorated due to particulate matter or unburned hydrocarbons.

The selective catalytic reduction system according to an embodiment of the present invention can effectively regenerate the catalyst located inside the reactor.

Specifically, the controller 900 detects NOx in the exhaust gas at the upstream side of the reactor 200 and at the downstream side of the reactor 200 to calculate the NOx reduction efficiency, so that the catalyst 210 inside the reactor 200 is effectively included in the exhaust gas. It is possible to discriminate whether the catalyst 210 is poisoned or not.

That is, the control unit 900 mixes the reducing agent injected by the reducing agent injecting unit 730 with the exhaust gas, passes through the reactor 200, effectively fails to decompose NOx into N2 and H2O by the catalyst 210, The ammonia adsorbed on the catalyst 210 may deteriorate the performance of the catalyst 210 by comparing the set NOx efficiency value with the calculated NOx reduction efficiency.

The control unit 900 can detect the NOx concentration of the exhaust gas through the first NOx sensor 910 and the second NOx sensor 920 to detect the NOx concentration of the exhaust gas in real time during the operation of the engine 100 .

In addition, the controller 900 according to an embodiment of the present invention determines whether the calculated NOx reduction efficiency value is lower than the set NOx efficiency value and whether the reference time has passed.

Specifically, the controller 900 keeps the calculated NOx reduction efficiency detected by the first NOx sensor 910 and the second NOx sensor 920 lower than the threshold value of the stored NOx reduction efficiency, It is determined that the catalyst regeneration operation is necessary and the catalyst regeneration operation can be performed.

The selective catalytic reduction system 101 according to an embodiment of the present invention can effectively regenerate the catalyst located inside the reactor.

Specifically, the control unit 900 judges whether or not the poisoning of the catalyst has exceeded the reference time in a state where the calculated NOx reduction efficiency value is lower than the set NOx efficiency value, and if the reference time is temporarily changed, the catalyst regeneration operation is not performed, The operation can be performed stably.

The control unit 900 according to an embodiment of the present invention stores information on NOx reference values that can be detected by the first NOx sensor 910 and the second NOx sensor 920 according to the load of the engine 100 have.

Specifically, the controller 900 determines whether there is a detected NOx value within the allowable range of the stored NOx reference value. If the detected NOx value is less than the allowable range of the NOx reference value or exceeds the allowable range, Diagnose.

In addition, if at least one of the first NOx sensor 910 and the first NOx sensor 910 is diagnosed as a failure, the user can be informed of the failure of the sensor. The form of the notification informing the user of the failure of the sensor can be changed in various forms such as lighting the sensor failure indicator of the instrument panel or generating a warning sound.

The selective catalytic reduction system 101 according to an embodiment of the present invention can effectively regenerate the catalyst located inside the reactor.

Specifically, the controller 900 can diagnose the failure of the first NOx sensor 910 and the second NOx sensor 920 that detect the NOx concentration of the exhaust gas to determine the poisoning of the catalyst, so that the failure of the NOx sensor It is possible to prevent an erroneous operation of separating the catalyst regeneration operation or the exhaust purification operation by the exhaust gas purifying catalyst.

That is, the control unit 900 can diagnose the failure of the first NOx sensor 910 and the second NOx sensor 920, thereby determining whether the catalyst regeneration operation or the exhaust purification operation required for the selective catalytic reduction system 101 is required Can be accurately determined.

In addition, the selective catalytic reduction system 101 according to an embodiment of the present invention may further include a flow rate sensor 930.

The flow sensor 930 detects the flow rate of the exhaust gas circulated by the blower 710. Specifically, the flow rate sensor 930 detects the flow rate of the exhaust gas circulating in the circulation flow path 600 formed on one side of the circulation flow path 600 and circulated by the blower 710.

The control unit 900 calculates a space velocity (SV) based on the flow rate of the exhaust gas detected by the flow sensor 930. The space velocity SV is a value obtained by dividing the flow rate of the exhaust gas detected by the flow sensor 930 by the volume of the catalyst 210 installed in the reactor 200. The amount of ammonia adsorbed to the catalyst 210 can be derived from the space velocity SV calculated by the controller 900. [

Specifically, when a certain amount or more of ammonia is adsorbed on the catalyst 210, the ability of the catalyst 210 to purify the exhaust gas mixed with the reducing agent deteriorates. That is, in order to improve the purifying capability of the catalyst 210, the control unit 900 sets the flow rate of the exhaust gas detected from the flow rate sensor 930 to a value of the space velocity SV divided by the volume of the input catalyst 210 The amount of ammonia adsorbed on the catalyst 210 is derived and a target flow rate value, a target temperature value, and a target time of the catalyst regeneration operation are determined according to the space velocity SV based on the input information.

That is, the controller 900 calculates the space velocity SV at the flow rate of the exhaust gas detected by the flow rate sensor 930, and determines the target flow rate value, the target temperature value, and the target time for performing the catalyst regeneration operation .

Specifically, information on the target flow rate value, the target temperature value, and the target time of the catalyst regeneration operation according to the space velocity SV is stored in the controller 900 in the form of a map. The information on the target flow rate value, the target temperature value, and the target time, etc. in the map form may be information stored in the controller 900 based on the repeated experimental data.

The selective catalytic reduction system 101 according to an embodiment of the present invention can effectively regenerate the catalyst located inside the reactor.

Specifically, the control unit 900 calculates the space velocity SV from the flow rate of the exhaust gas detected by the flow rate sensor 930, and calculates a target flow rate value, a target temperature value, And the target time can be determined, and information on the flow rate, temperature, and time necessary for regeneration of the catalyst 210 can be determined from the current flow rate of the exhaust gas.

The flow sensor 930 can be formed on one side of the circulation flow passage 600 and can be prevented from being exposed to the exhaust gas when the exhaust purification operation is performed by the controller 900, The service life and replacement cycle of the battery can be increased.

The controller 900 compares the flow rate of the exhaust gas detected by the flow sensor 930 with the target flow rate value to determine whether the flow rate of the exhaust gas detected exceeds the target flow rate value, (710).

Specifically, the control unit 900 compares the detected flow rate of the exhaust gas with the target flow rate value, and stops the increase of the rotational speed of the blower 710 and terminates the catalyst regeneration operation if the target flow rate value is exceeded.

The selective catalytic reduction system 101 according to an embodiment of the present invention can effectively regenerate the catalyst located inside the reactor.

That is, the control unit 900 can compare the current flow rate of the exhaust gas with the target flow rate value, thereby effectively controlling the blower 710.

In addition, the selective catalytic reduction system 101 according to an embodiment of the present invention may further include a temperature sensor 940.

The temperature sensor 940 detects the temperature of the exhaust gas heated by the heating unit 720. Specifically, the temperature sensor 940 is formed on one side of the circulation flow path 600 to detect the temperature of the exhaust gas circulating in the circulation path 600.

The control unit 900 compares the temperature of the exhaust gas detected by the temperature sensor 940 with the target temperature value to determine whether the detected temperature of the exhaust gas exceeds the target temperature value, .

 Specifically, the control unit 900 compares the detected temperature of the exhaust gas with the target temperature value, and when the target temperature value is exceeded, the controller 900 stops the temperature rise of the heating unit 720 and terminates the catalyst regeneration operation.

The selective catalytic reduction system 101 according to an embodiment of the present invention can effectively regenerate the catalyst located inside the reactor.

That is, the control unit 900 can effectively control the heating unit 720 by comparing the current exhaust gas temperature detected by the temperature sensor 940 with the target temperature value.

The temperature sensor 940 may be formed on one side of the circulation channel 600 to detect the temperature of the exhaust gas circulating in the circulation channel 600. When the control unit 900 performs the exhaust purification operation It is possible to prevent the exhaust gas from being exposed to the exhaust gas and to increase the service life and replacement cycle of the temperature sensor 940.

In the case where the selective catalytic reduction system 101 includes both the flow sensor 930 and the temperature sensor 940, the controller 900 controls the flow rate of the exhaust gas and the temperature of the exhaust gas, When the target temperature value is exceeded, the catalyst regeneration operation can be terminated.

The control unit 900 determines whether a predetermined time period during which the circulation is maintained between the exhaust gas recirculation channel 600 and the reactor 200 exceeding the target flow rate value and the target temperature value by the heating unit 720 exceeds the target time And if the predetermined time exceeds the target time, the catalyst regeneration operation can be terminated.

Hereinafter, with reference to FIG. 2, a description will be given of a control method of an operation process using a selective catalytic reduction system according to an embodiment of the present invention.

The selective catalytic reduction system according to an embodiment of the present invention can be divided into a NOx sensor failure diagnosis step S100, a catalyst poisoning determination step S200, and a catalyst regeneration step S300.

First, the NOx sensor failure diagnosis step (S100) during the operation of the selective catalytic reduction system according to an embodiment of the present invention will be described.

In order to diagnose the failure of the NOx sensor, the load of the engine is detected (S110). For example, it is possible to detect whether the load of the engine is equal to or higher than a predetermined value.

And derives a reference value of the NOx concentration predicted at the front end and the rear end of the reactor according to the detected load (S120). The NOx concentration of the exhaust gas is detected from the NOx sensor at the front end and the rear end of the reactor (S130). Then, it is determined whether the detected NOx concentration is within the permissible range of the reference value (S140). If it is determined that the detected NOx concentration exceeds the allowable range of the reference value or is less than the allowable range, the NOx sensor is diagnosed as a failure and the driver is informed that the NOx sensor needs to be replaced (S150).

If it is determined that the detected NOx concentration is within the allowable range of the reference value, the NOx sensor is diagnosed as normal and the process proceeds to the next catalyst poisoning determination step (S200).

Next, a catalyst poisoning determination step (S200) of the selective catalytic reduction system according to an embodiment of the present invention will be described.

The reducing agent injection unit is controlled to inject the reducing agent into the exhaust gas (S210). The reducing agent injection is executed when it is determined that the detected NOx concentration is within the allowable range of the reference value (S140).

The NOx concentration of the exhaust gas is detected from the NOx sensor at the front end and the rear end of the reactor (S220). Then, the NOx reduction efficiency is calculated from the detected NOx concentration (S230). The calculated NOx reduction efficiency is compared with the set NOx efficiency value (S240).

When the calculated NOx reduction efficiency exceeds the set NOx efficiency value, the NOx concentration of the exhaust gas after reductant injection is re-detected (S220).

If the calculated NOx reduction efficiency is less than the set NOx efficiency value, it is determined whether the calculated NOx reduction efficiency is lower than the set NOx efficiency value (S250).

If the calculated NOx reduction efficiency is lower than the set NOx efficiency value, the calculated NOx reduction efficiency is compared with the set NOx efficiency value (S240).

If the calculated NOx reduction efficiency is lower than the set NOx efficiency value, it is determined that the catalyst has been poisoned, and the process proceeds to the next catalyst regeneration step (S300).

Next, a catalyst regeneration step (S300) of the selective catalytic reduction system according to an embodiment of the present invention will be described.

The reducing agent injection is stopped to regenerate the catalyst (S310). The reducing agent injection stop (S310) is executed when the calculated NOx reduction efficiency is lower than the set NOx efficiency value and the reference time has elapsed.

The exhaust gas discharged from the engine is bypassed to the reactor, the exhaust gas flowing into the reactor is blocked, the exhaust gas passing through the reactor is prevented from being discharged to the outside, and the exhaust gas is circulated between the reactor and the circulating flow path. (S320).

The flow rate of the exhaust gas is detected from the flow rate sensor, and the flow rate of the exhaust gas is divided by the volume of the catalyst to calculate the space velocity (S330).

And determines a target flow rate value, a target temperature value, and a target time according to the calculated space velocity (S340).

The blower is operated (S350) for catalyst regeneration. Then, the flow rate of the exhaust gas is compared with the target flow rate value according to the current blower flow rate (S360).

When the current flow rate of the exhaust gas is less than the target flow rate value, the operation is performed so that the flow rate of the blower is increased (S350).

When the current flow rate of the exhaust gas exceeds the target flow rate value, the heating unit is operated (S370).

The temperature of the exhaust gas heated by the heating unit is compared with the target temperature value (S380).

When the temperature of the exhaust gas is lower than the target temperature value, the operation is performed so that the operating temperature of the heating unit is increased (S370).

When the temperature of the exhaust gas exceeds the target temperature value, the time when the exhaust gas exceeding the target temperature value is circulated is compared with the target time (S390).

If the circulation time of the exhaust gas exceeding the target temperature value is less than the target time, the circulation time is increased to exceed the target time.

When the circulation time of the exhaust gas exceeding the target temperature value exceeds the target time, the catalyst regeneration step (S300) ends.

By performing such an operation process, the catalyst can be regenerated effectively.

Specifically, the operating procedure determines whether the catalyst is poisoned by comparing the NOx reduction efficiency with the set NOx efficiency value, determining whether the calculated NOx reduction efficiency is lower than the set NOx efficiency value, The catalyst can be regenerated and the catalyst of the selective catalytic reduction system can be effectively regenerated according to the determination of whether the catalyst is poisoned. In addition, the operation process can diagnose the failure of the NOx sensor that detects NOx to determine whether the catalyst is poisoned, and can accurately determine whether the catalyst is poisoned.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. will be.

It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

100: engine 101: selective catalytic reduction system
110: Main flow path 210: Catalyst
200: Reactor 300: Bypass channel
310: first opening and closing member 400: second opening and closing member
500: third opening and closing member 600:
710: blower 720: heating part
730: reducing agent spraying part 900: control part
910: first NOx sensor 920: second NOx sensor
930: Flow sensor 940: Temperature sensor
S100: NOx sensor failure diagnosis step S110: engine load detection step
S120: NOx concentration reference value deriving step S130: NOx detection step
S140: NOx concentration allowable range determination step S150: NOx sensor replacement alarm step
S200: Determination of catalyst poisoning status S210: Reducing agent injection step
S220: NOx detection step S230: NOx reduction efficiency calculation step
S240: NOx reduction efficiency comparison step S250: reference time comparison step
S300: catalyst regeneration step S310: reducing agent injection stop step
S320: opening / closing member adjustment step S330: space velocity calculation step
S340: Target value determination step S350: Blower operation step
S360: target flow value comparison step S370: heating section operation step
S380: target temperature value comparison step S390: target time value comparison step

Claims (10)

A main flow path 110 through which the exhaust gas of the engine 100 passes;
A reactor 200 disposed on the main flow path 110 and having a catalyst 210 installed therein;
A bypass channel (300) branched from the main channel (110) and bypassing the reactor (200);
A first opening / closing member 310 installed on the bypass channel 300;
A second opening / closing member (400) installed on the main flow path (110) for switching the flow of exhaust gas flowing into the reactor (200);
A third opening / closing member (500) installed on the main flow path (110) for switching the flow of the exhaust gas passing through the reactor (200);
A circulation flow passage 600 connecting one point between the second opening and closing member 400 and the front end of the reactor 200 and another point between the third opening and closing member 500 and the rear end of the reactor 200;
A blower 710 for circulating the exhaust gas between the reactor 200 and the circulation passage 600;
A heating unit 720 for raising the exhaust gas passing through the circulation passage 600; And
The first opening / closing member 310, the second opening and closing member 400, the third opening and closing member 500, the blower 710, and the heating unit 720 may be either of an exhaust purification operation or a catalyst regeneration operation The control unit 900,
/ RTI >
The control unit (900)
Closing member 400 and the third opening and closing member 500 are closed and the blower 710 is operated when the catalyst regeneration operation is performed, Closing member 400 and the third opening and closing member 500 when the exhaust purifying operation is performed and the blower 710 is operated while the first opening and closing member 310 and the third opening and closing member 500 are opened, And stops the operation of the heating unit (720).
delete The method of claim 1,
Further comprising a reducing agent spraying part (730) for spraying a reducing agent to the exhaust gas passing through the main flow path (110) during the exhaust purifying operation.
delete The method of claim 1,
A first NOx sensor 910 for detecting the NOx concentration at the upstream side of the reactor 200; And
Further comprising a second NOx sensor (920) for detecting the NOx concentration at the downstream end of the reactor (200)
The control unit (900)
A selective catalytic reduction (NOx) reduction catalyst for determining whether the catalyst 210 is poisoned by comparing the NOx reduction efficiency calculated by the NOx value detected from the first NOx sensor 910 and the second NOx sensor 920 with the set NOx efficiency value, system.
The method of claim 5,
The control unit (900)
A selective catalyst reduction system for performing the catalyst regeneration operation when the calculated NOx reduction efficiency is lower than the set NOx efficiency value,
The method of claim 5,
The control unit (900)
It is determined whether or not the NOx value detected from the first NOx sensor 910 and the second NOx sensor 920 is within the permissible range of the input NOx reference value according to the load of the engine 100 and the first NOx sensor 910 ) And the second NOx sensor (920).
8. The method according to any one of claims 5 to 7,
Further comprising a flow sensor (930) for detecting the flow rate of the exhaust gas circulated by the blower (710)
The control unit (900)
A selective catalytic reduction system for determining a target flow rate value and a target temperature value of the catalyst regeneration operation by calculating a space velocity (SV) obtained by dividing a flow rate of exhaust gas detected by the flow rate sensor (930) .
9. The method of claim 8,
The control unit (900)
The catalyst regeneration operation is performed by comparing the flow rate of the exhaust gas detected by the flow rate sensor 930 with the target flow rate value, and when the flow rate of the exhaust gas detected by the flow rate sensor 930 exceeds the target flow rate value, And terminating the regeneration operation.
9. The method of claim 8,
And a temperature sensor (940) for detecting the temperature of the exhaust gas heated by the heating unit (720)
The control unit (900)
When the temperature of the exhaust gas detected by the temperature sensor 940 exceeds the target temperature value by comparing the temperature of the exhaust gas detected by the temperature sensor 940 with the target temperature value during the catalyst regeneration operation, And terminating the regeneration operation.

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