KR102598692B1 - Efficiency improving method for PM-NOx simultaneous reduction apparatus by using regeneration burner - Google Patents

Abstract

An exhaust gas device according to an embodiment of the present invention includes a DOC/DPF module that removes particulate matter (PM) contained in exhaust gas, a regenerative burner module disposed in front of the DOC/DPF module and heated, and the DOC/DPF module. It includes an SCR module disposed at the rear end to remove nitrogen oxides contained in exhaust gas using a reducing agent, and a control module controlling the operation of the regeneration burner according to the injection amount of the reducing agent and the temperature of the exhaust gas.

Description

Efficiency improving method for PM-NOx simultaneous reduction apparatus by using regeneration burner}

The present invention relates to an exhaust gas device and an exhaust gas reduction method, and more specifically, to an exhaust gas device and an exhaust gas reduction method that simultaneously reduces PM-NOx by increasing the efficiency of SCR using a regenerative burner.

Certain operating diesel vehicles have lower emission standards than newly sold vehicles, so they emit more pollutants on the road. In Korea, the emission standards for harmful emissions from manufactured and operated diesel vehicles are continuously being strengthened to improve air quality. Accordingly, a project to reduce emissions by installing simultaneous PM-NOx reduction devices on certain diesel vehicles in order to improve air quality is actively underway.

However, in the case of certain vehicles, they have a low temperature gradient through low-speed/low-load operation when driving, and in this case, they exhibit low nitrogen oxide reduction characteristics, and at such a low temperature distribution, high NH3 slip can be generated due to continuous occlusion of the reducing agent. there is a problem.

The PM-NOx simultaneous reduction device induces natural regeneration by displacing DOC/DPF because the exhaust gas temperature during operation is lower than the oxidation temperature of PM, and soot deposited in the DPF is oxidized periodically using a regeneration burner. The SCR (Selective Chemical Reaction) system using urea as a reducing agent is generally efficient at over 200 degrees, and shows ammonium nitrate formation and low purification efficiency at low temperatures (T≤200°C). Therefore, there is a problem of low nitrogen oxide reduction efficiency during vehicle cold start and low speed and low load operation.

Technology is needed to improve the nitrogen oxide reduction characteristics of diesel vehicles operating with low temperature gradients.

The technical problem to be solved by the present invention is to provide an exhaust gas device and an exhaust gas reduction method that simultaneously reduces PM-NOx by increasing the efficiency of SCR using a regenerative burner.

In order to solve the above technical problem, an exhaust gas device according to an embodiment of the present invention includes a DOC/DPF module for removing particulate matter (PM) contained in exhaust gas; A regeneration burner module disposed in front of the DOC/DPF module and heated; an SCR module disposed behind the DOC/DPF module to remove nitrogen oxides contained in exhaust gas using a reducing agent; and a control module that controls the operation of the regeneration burner according to the injection amount of the reducing agent and the temperature of the exhaust gas.

In addition, the control module determines the injection amount of the reducing agent using the temperature and intake air amount of the input terminal of the SCR module, and can drive the regenerative burner module when the temperature of the input terminal is lower than the first value.

Additionally, the control module may determine the injection amount of the reducing agent by applying a weight when the regeneration burner module is operating.

Additionally, the control module may drive the regenerative burner module under a first heating condition when the DOC/DPF module operates, and may drive the regenerative burner module under a second heating condition when the SCR module operates.

Additionally, the amount of fuel injected into the regenerative burner module under the first heating condition may be greater than the amount of fuel injected into the regenerative burner module under the second heating condition.

In order to solve the above technical problem, an exhaust gas reduction method according to an embodiment of the present invention includes detecting the temperature of the input terminal of the SCR module; Determining the injection amount of the reducing agent using the temperature of the input terminal of the SCR module and the amount of intake air; and removing nitrogen oxides contained in the exhaust gas by spraying the reducing agent, wherein when the temperature of the input terminal is lower than the first value, the regenerative burner module is driven.

In addition, after the step of removing nitrogen oxides, a step of verifying the efficiency of the SCR module may be further included.

Additionally, in the step of determining the injection amount of the reducing agent, the injection amount of the reducing agent may be determined by applying a weight when the regeneration burner module is operating.

Additionally, the regenerative burner module may be driven under a first heating condition when the DOC/DPF module is operating, and may be driven under a second heating condition when the SCR module is operating.

Additionally, the amount of fuel injected into the regenerative burner module under the first heating condition may be greater than the amount of fuel injected into the regenerative burner module under the second heating condition.

According to embodiments of the present invention, nitrogen oxide reduction performance can be improved at a low cost by changing the control logic using the regenerative burner included in the system. In addition, by maintaining the exhaust gas temperature at an appropriate level, it can be applied to vehicles with low temperature gradients, and accordingly, there is an advantage in terms of reaction speed when spraying the reducing agent of SCR. Furthermore, by minimizing the area for ammonia storage, the problem of ammonia being released into the atmosphere can be solved.

1 is a block diagram of an exhaust gas device according to an embodiment of the present invention.
2 to 5 are diagrams for explaining the exhaust gas reduction process according to an embodiment of the present invention.
Figure 6 is a flowchart of an exhaust gas reduction method according to an embodiment of the present invention.
Figure 7 is a flowchart of an exhaust gas reduction method according to another embodiment of the present invention.

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

However, the technical idea of the present invention is not limited to some of the described embodiments, but may be implemented in various different forms, and as long as it is within the scope of the technical idea of the present invention, one or more of the components may be optionally used between the embodiments. It can be used by combining or replacing.

In addition, terms (including technical and scientific terms) used in the embodiments of the present invention, unless explicitly specifically defined and described, are generally understood by those skilled in the art to which the present invention pertains. It can be interpreted as meaning, and the meaning of commonly used terms, such as terms defined in a dictionary, can be interpreted by considering the contextual meaning of the related technology.

Additionally, the terms used in the embodiments of the present invention are for describing the embodiments and are not intended to limit the present invention.

In this specification, the singular may also include the plural unless specifically stated in the phrase, and when described as "at least one (or more than one) of A and B and C", it is combined with A, B, and C. It can contain one or more of all possible combinations.

Additionally, in describing the components of the embodiments of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the component from other components, and are not limited to the essence, order, or order of the component.

And, when a component is described as being 'connected', 'coupled', or 'connected' to another component, that component is directly 'connected', 'coupled', or 'connected' to that other component. In addition to cases, it may also include cases where the component is 'connected', 'coupled', or 'connected' by another component between that component and that other component.

Additionally, when described as being formed or disposed “on top” or “bottom” of each component, “top” or “bottom” means that the two components are directly adjacent to each other. This includes not only the case of contact, but also the case where one or more other components are formed or disposed between the two components. In addition, when expressed as “top” or “bottom,” the meaning of not only the upward direction but also the downward direction can be included based on one component.

Figure 1 is a block diagram of an exhaust gas device 100 according to an embodiment of the present invention.

The exhaust gas system 100 according to an embodiment of the present invention is composed of a DOC/DPF module 110, a regeneration burner module 120, an SCR module 130, and a control module 140. The exhaust gas device 100 can be applied to the exhaust pipe of a diesel vehicle, and can be applied to a device that exhausts PM and nitrogen oxides, which are particulate matter. In addition, it can be applied to various exhaust pipes or exhaust pipes.

The DOC/DPF module 110 removes particulate matter (PM) contained in the exhaust gas 200.

More specifically, the exhaust gas contains particulate matter (PM), which is a pollutant, and the DOC/DPF module 110 removes the particulate matter contained in the exhaust gas. Here, DOC (Diesel Oxidize Catalyst) purifies particulate matter, carbon monoxide, hydrocarbons, etc. contained in the exhaust gas, and DPF (Diesel Particulate Filter) burns and removes particulate matter. Here, particulate matter (PM) is a particle pollutant and refers to very small liquid or solid suspended matter. Particulate matter may include dust, smoke, soot, mist, aerosols, dust, fly ash, smoke, haze, smoke, smog, and airborne allergens. The DOC/DPF module 110 may be referred to as a DePM module.

The regeneration burner module 120 is placed in front of the DOC/DPF module 110 and heats it.

More specifically, the regenerative burner module 120 transfers heat through combustion. The regeneration burner module 120 may perform a regeneration process to oxidize soot deposited in the DPF. The regeneration burner module 120 may perform a DPF regeneration process by periodically heating. Additionally, when the SCR module 130 operates, heating can be performed under control of the control module 140 as needed.

The regenerative burner module 120 may include a fuel dosing unit that provides fuel for combustion, and may use diesel oil as fuel. In addition, it is driven using plasma or an igniter as an ignition source for combustion, and combustion air and fuel are introduced and heated by combustion by the ignition source.

The SCR module 130 is located behind the DOC/DPF module 110 and removes nitrogen oxides contained in the exhaust gas using a reducing agent.

More specifically, the SCR module 130 sprays a reducing agent into the exhaust gas from which particulate matter has been removed in the DOC/DPF module 110 to remove nitrogen oxides (NOx) contained in the exhaust gas. The SCR module 130 may use urea as a reducing agent. By spraying a reducing agent into the exhaust gas, nitrogen oxides can be removed by reducing them with the reducing agent. The nitrogen oxide reduction efficiency of the SCR module 130 is affected by temperature. When the temperature of the exhaust gas flowing into the SCR module 130 is within a predetermined range, the nitrogen oxide reduction efficiency increases. The temperature range in which the reduction efficiency of nitrogen oxides exceeds the critical value may vary depending on the injection amount of the reducing agent.

The control module 140 controls the operation of the regenerative burner module 120 according to the reducing agent injection amount and the temperature of the exhaust gas.

More specifically, when the exhaust gas temperature is lower than the temperature at which the nitrogen oxide reduction efficiency of the currently injected reducing agent injection amount becomes more than a threshold value, the regenerative burner module 120 is operated to increase the temperature. The control module 140 determines the injection amount of the reducing agent using the temperature and the amount of intake air at the input end of the SCR module 130. If the temperature at the input end is lower than the first value, the regeneration burner module 120 can be driven. . Here, the amount of intake air may be the amount of air applied to a device discharging exhaust gas, or may mean the amount of intake air applied to the engine of a diesel vehicle. The control module 140 can determine an appropriate injection amount of reducing agent to increase nitrogen oxide reduction efficiency according to the current temperature of the input terminal and the amount of intake air. At this time, the injection amount of reducing agent according to the temperature of the input terminal and the amount of intake air can be set in advance and stored in the memory as a table or map. The control module 140 may determine the injection amount of the reducing agent using the stored map.

The first value is a temperature value that varies depending on the injection amount of the reducing agent, and may be the minimum temperature at which the nitrogen oxide reduction efficiency is higher than the threshold value or may be a preset temperature. The first value may be a variable value or a fixed value. For example, the first value may be 250 °C. That is, if the temperature of the input terminal of the SCR module 130 is lower than 250°C, the control module 140 increases the exhaust gas temperature by driving the regeneration burner module 120, and the exhaust gas with the increased temperature is transferred to the SCR module 130. It can be applied to increase the temperature of the input terminal.

When the temperature of the input terminal is lower than the first value, the control module 140 drives the regeneration burner module 120 and can determine the injection amount of the reducing agent by applying a weight when the regeneration burner module 120 operates. When operating the regenerative burner module, a constant temperature can be maintained, thereby increasing the nitrogen oxide reduction efficiency, and the reducing agent injection amount can be efficiently determined. When driving the regeneration burner module 120, the injection amount of the reducing agent may increase. When driving the regeneration burner module 120, the map used when weighting is applied or the regeneration burner module 120 is not operated is The reducing agent injection amount can be determined using a map or table depending on the case of driving the regeneration burner module 120.

In this way, appropriate nitrogen oxide reduction efficiency can be maintained at high temperatures when operating the SCR module 130, and through this, the amount of NH3 stored in the SCR module 130 is minimized to reduce the possibility of NH3 slip. It can be lowered. In other words, the ammonia storage area can be minimized to prevent ammonia from being released into the atmosphere.

The exhaust gas device 100 according to an embodiment of the present invention may be formed as shown in FIG. 2. Figure 2 is an example of being mounted on the exhaust pipe of a diesel vehicle, in which air flows into the engine, and the exhaust gas exhausted from the engine passes through the DOC and DPF, which are the DOC/DPF module 110, and out through the SCR, which is the SCR module 130. It is exhausted. At this time, the regeneration burner module 120 is disposed at the front of the DOC. The regenerative burner module 120 may include a dosing unit including an air pump and a fuel pump, and an igniter. The SCR module 130 includes a dosing unit that supplies urea, a reducing agent, and a reducing agent injection device. A mass air flow (MAF) sensor is placed at the front of the engine to measure the amount of intake air. The control module 140 may receive information from each exhaust pipe to cause combustion in the regenerative burner module 120 or determine the amount of reducing agent injection of the SCR module 130 and perform injection of the reducing agent.

The control module 140 can control the operation of the SCR module 130 and the regeneration burner module 120, as shown in FIG. 3. First, when the SCR module 130 is driven, it is determined (S1) whether the temperature (SCR inlet temp) of the input terminal of the SCR module 130 is higher than the first value of 200 degrees Celsius, and if it is higher than the first value, the current input terminal temperature and suction Determine the reducing agent injection amount using the air volume (S2). At this time, the amount of reducing agent injection can be determined using the stored map (map 01). Afterwards, the reducing agent is sprayed (S3) and the temperature of the exhaust gas is verified. At this time, the temperature of the input terminal and output terminal is verified, and it is determined whether it is higher than the first value (S4). If the temperature of the input terminal is lower than the first value, the control module 140 can drive the regeneration burner module 120 and compensate (S6) the weight or the amount of reducing agent injection using the map (MAP 02). By compensating for the injection amount, the reducing agent injection amount is determined while the temperature at the input end is higher than the first value, and the reducing agent is injected. Afterwards, the target purification efficiency is verified (S5). If the target purification efficiency is not met, the operation of the SCR module 130 can be repeated.

The process of operating the regeneration burner according to the temperature of the input stage can be represented graphically as shown in FIG. 4. Since the exhaust gas moves to the input terminal along the exhaust pipe, when the regenerative burner module 120 is not driven, the temperature 420 of the input terminal follows the temperature 410 of the exhaust gas with a time difference. The exhaust gas temperature 410 may vary according to a trigonometric function depending on the driving frequency of the engine. When operating the SCR module 130, if the exhaust gas temperature is a, it is judged as low temperature, and the regenerative burner module 120 is driven to move the temperature of the input terminal to the 430 line instead of the 410 line. The regeneration burner module 120 can be driven by injecting fuel into the regeneration burner and burning it. At this time, fuel can be controlled and injected (440) by a preset amount. Initially, to increase the temperature, you can spray 5 times, and then you can spray 3 times at a time. The injection amount may vary depending on the appropriate temperature. When the temperature of the input terminal reaches an activation section where the nitrogen oxide reduction efficiency is higher than the threshold, heating of the regenerative burner module 120 is unnecessary. When the temperature of the input terminal becomes b, the operation of the regenerative burner module 120 is stopped. Even when the regenerative burner module 120 is turned off, the temperature of the input stage does not immediately drop due to changes in the temperature of the exhaust gas, but rises and falls along line 420. When the temperature of the input terminal reaches c while descending along line 420, the nitrogen oxide reduction efficiency decreases, and the regeneration burner module 120 is re-ignited. Due to the operation of the regenerative burner module 120, the temperature of the input terminal repeats between b and c to maintain the corresponding section, and when the 420 line rises again according to the temperature of the exhaust gas, the temperature of the input terminal does not lower to c but rises and falls. do. While operating the SCR module 130, the operation of the regenerative burner module 120 can be turned on and off so that the temperature of the input terminal is maintained above c.

The control module may drive the regenerative burner module 120 under the first heating condition when the DOC/DPF module 110 operates, and drive the regenerative burner module 120 under the second heating condition when the SCR module 130 operates. . At this time, the amount of fuel injected into the regenerative burner module under the first heating condition may be greater than the amount of fuel injected into the regenerative burner module under the second heating condition. When operating the DOC/DPF module 110, a temperature of more than 300 degrees Celsius is required to combust the particulate module, and when operating the SCR module 130, a temperature of 200 to 250 degrees Celsius is required. If the temperature is too high when the SCR module 130 is operating, the nitrogen oxide reduction efficiency is lowered, so when the DOC/DPF module 110 is operating, the operation of the SCR module 130 can be stopped. The control module 140 can control the regeneration burner module 120 so that the exhaust gas reaches an appropriate temperature when operating in each mode.

Figure 5 is a graph comparing the case where the regenerative burner module 120 is driven when the SCR module 130 is operating and the case where the regenerative burner module 120 is not driven. When the regenerative burner module 120 is not driven, the nitrogen oxide reduction efficiency at 200 degrees Celsius is 60%, as shown in FIG. 6(A), and the efficiency dispersion increases as shown in FIG. 6(C), while the regenerative burner module 120 is not operated. When driving, as shown in Figure 6(B), the nitrogen oxide reduction efficiency increases to 80% at 200 degrees Celsius, and as shown in Figure 6(D), the efficiency dispersion also decreases, showing that the efficiency increases. In other words, it can be seen that the average temperature increases and the average efficiency increases by driving the regenerative burner module 120.

As described above, the probability of reducing nitrogen oxides can be increased by maintaining the temperature of the SCR module 130 above a certain temperature using only drive control for the regeneration burner module 120 without any additional configuration.

FIG. 6 is a flowchart of a method for reducing exhaust gases according to an embodiment of the present invention, and FIG. 7 is a flowchart of a method for reducing exhaust gases according to another embodiment of the present invention. The detailed description of each step in FIGS. 6 to 7 corresponds to the detailed description of the exhaust gas device in FIGS. 1 to 5, and redundant description will be omitted below.

When driving the SCR module, the temperature of the input terminal of the SCR module is detected in step S11, the injection amount of the reducing agent is determined using the temperature and intake air amount of the input terminal of the SCR module in step S12, and the reducing agent is sprayed in step S13. Removes nitrogen oxides contained in exhaust gas. At this time, if the temperature of the input terminal is lower than the first value, the regeneration burner module is driven. When operating the regenerative burner module, the amount of reducing agent injection can be determined by applying a weight, and the regenerative burner module is driven under a first heating condition when the DOC/DPF module is operated, and driven under a second heating condition when the SCR module is operated. It may be possible, and the amount of fuel injected into the regenerative burner module under the first heating condition may be greater than the amount of fuel injected into the regenerative burner module under the second heating condition.

After step S13 of removing the nitrogen oxides, the efficiency of the SCR module can be verified in step S21, and steps S11 to S13 can be repeated until the target efficiency is satisfied.

Meanwhile, embodiments of the present invention can be implemented as computer-readable code on a computer-readable recording medium. Computer-readable recording media include all types of recording devices that store data that can be read by a computer system.

Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, and optical data storage devices. In addition, computer-readable recording media are distributed in computer systems connected to a network. , computer-readable code can be stored and executed in a distributed manner. And functional programs, codes, and code segments for implementing the present invention can be easily deduced by programmers in the technical field to which the present invention pertains.

Those skilled in the art related to this embodiment will understand that the above-described base material can be implemented in a modified form without departing from the essential characteristics. Therefore, the disclosed methods should be considered from an explanatory rather than a restrictive perspective. The scope of the present invention is indicated in the claims rather than the foregoing description, and all differences within the equivalent scope should be construed as being included in the present invention.

100: exhaust gas device
110: DOC/DPF module
120: Regeneration burner module
130: SCR module
140: Control module
200: exhaust gas

Claims (11)

DOC/DPF module that removes particulate matter (PM) contained in exhaust gases;
A regeneration burner module disposed in front of the DOC/DPF module and heated;
an SCR module disposed behind the DOC/DPF module to remove nitrogen oxides contained in exhaust gas using a reducing agent; and
It includes a control module that controls the operation of the regenerative burner module according to the injection amount of reducing agent and the temperature of the exhaust gas,
The control module is,
The injection amount of the reducing agent is determined using a data table or map that is preset and stored according to the temperature and intake air amount of the input terminal of the SCR module,
When the temperature of the input terminal is lower than the first value, the regeneration burner module is driven, but instead of the first data table or first map applied when the regeneration burner module is not operating, the regeneration burner module is applied when the regeneration burner module is operating. 2 An exhaust gas device that determines the injection amount of the reducing agent using a data table or a second map. delete delete According to paragraph 1,
The control module is,
An exhaust gas device that drives the regenerative burner module under a first heating condition when the DOC/DPF module operates, and drives the regenerative burner module under a second heating condition when the SCR module operates. According to paragraph 4,
An exhaust gas device in which the amount of fuel injected into the regenerative burner module under the first heating condition is greater than the amount of fuel injected into the regenerative burner module under the second heating condition. Detecting the temperature of the input terminal of the SCR module;
Determining the injection amount of the reducing agent using the temperature of the input terminal of the SCR module and the amount of intake air; and
Including the step of removing nitrogen oxides contained in the exhaust gas by spraying the reducing agent,
If the temperature of the input terminal is lower than the first value, the regeneration burner module is driven,
When the regeneration burner module is operating, instead of the first data table or first map applied when the regeneration burner module is not operating, the reducing agent is used using the second data table or second map applied when the regeneration burner module is operating. An exhaust gas reduction method that determines the injection amount. According to clause 6,
An exhaust gas reduction method further comprising verifying the efficiency of the SCR module after the step of removing nitrogen oxides. delete According to clause 6,
The regeneration burner module,
A method of reducing exhaust gases in which the DOC/DPF module is operated under a first heating condition and the SCR module is operated under a second heating condition. According to clause 9,
A method of reducing exhaust gas in which the amount of fuel injected into the regenerative burner module under the first heating condition is greater than the amount of fuel injected into the regenerative burner module under the second heating condition. A computer-readable recording medium recording a program for executing the method of any one of claims 6, 7, 9, and 10 on a computer.