KR100999645B1 - Method for regenerating diesel oxidation catalyst - Google Patents

Abstract

The present invention relates to a method for regenerating a diesel coral catalyst which improves the purification efficiency of exhaust gas by performing the sulfur poisoning removal by accurately determining the sulfur poisoning removal time in the platinum and palladium-coated diesel oxidation catalyst.

Regeneration method of the diesel oxidation catalyst according to an embodiment of the present invention is to oxidize hydrocarbon and carbon monoxide in the exhaust gas and to remove sulfur poisoning of the diesel oxidation catalyst coated with platinum and palladium on the carrier, a) the integration distance from the set point Determining whether the distance is greater than a set distance; b) when the integration distance is greater than the set distance from the set time point, raising the diesel oxidation catalyst rear end temperature above the set temperature; c) determining whether the efficiency of the diesel oxidation catalyst is less than the set efficiency; And d) regenerating the diesel oxidation catalyst when the efficiency of the diesel oxidation catalyst is smaller than the set efficiency.

Diesel Coral Catalyst, Humidifying

Description

Regeneration method of diesel oxidation catalyst {METHOD FOR REGENERATING DIESEL OXIDATION CATALYST}

The present invention relates to a regeneration method of a diesel oxidation catalyst, and more particularly, to improve the efficiency of exhaust gas purification by performing the sulfur poisoning removal by accurately determining the sulfur poisoning removal time in the platinum and palladium-coated diesel oxidation catalyst. A method for regenerating a coral catalyst.

In general, the exhaust gas discharged from the engine through the exhaust manifold is guided to a catalytic converter formed in the middle of the exhaust pipe and purified, and the noise is attenuated while passing through the muffler and then released into the atmosphere through the tail pipe. The catalytic converter is a type of diesel particulate filter (DPF) to treat pollutants contained in the exhaust gas. In addition, a catalyst carrier for trapping particulate matter (PM) included in the exhaust gas is formed inside the catalytic converter to purify various exhaust gases discharged from the engine through a chemical conversion process.

One type of catalyst applied to the catalytic converter which plays such a role is Diesel Oxidation Catalyst (DOC). DOC oxidizes HC and CO contained in the exhaust gas.

On the other hand, since the sulfur component contained in the fuel deteriorates the performance of the oxidation catalyst, an oxidation catalyst coated with a platinum (Pt) having strong sulfur resistance is mainly used in DOC. However, since platinum is expensive, there is a problem in that the manufacturing cost is expensive, and accordingly, an oxidation catalyst coated with platinum and palladium (Pd) is supported. In this case, it is a major concern to prevent the degradation of the oxidation catalyst by sulfur.

In particular, the activity of the oxidation catalyst by sulfur is greatly reduced when the temperature of the exhaust gas is low.

Figure 5 is a graph showing the relationship between temperature and time to recover the activity of the oxidation catalyst after sulfur poisoning. As shown in FIG. 5, when the temperature of the exhaust gas is 400 ° C, it takes 5 minutes to recover the activity of the oxidation catalyst, and when the temperature of the exhaust gas is 450 ° C, it takes 1 minute to restore the activity of the oxidation catalyst. When the temperature of the exhaust gas is 500 ° C., it takes 10 seconds to recover the activity of the oxidation catalyst. Therefore, in order to use an oxidation catalyst containing platinum and palladium, the temperature of the exhaust gas must be maintained at 450 ° C. or higher, which is practically difficult.

Up to now, there is no separate method for removing the poisoning of the diesel oxidation catalyst, the exhaust gas temperature is high when the vehicle is running at high speed is to remove the poisoning of the diesel oxidation catalyst naturally. However, in view of the current road conditions that drive more slowly than high speed, it is difficult to see the natural elimination effect of sulfur poisoning.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to provide a regeneration method of a diesel oxidation catalyst that can improve the purification efficiency of the exhaust gas by accurately determining the removal time of sulfur poisoning. .

Another object of the present invention is to provide a method for regenerating a diesel oxidation catalyst having low production cost without lowering the purification efficiency of exhaust gas even when an oxidation catalyst coated with a platinum and palladium carrier is used.

Regeneration method of the diesel oxidation catalyst according to an embodiment of the present invention for achieving this object is to oxidize hydrocarbon and carbon monoxide in the exhaust gas and to remove sulfur poisoning of the diesel oxidation catalyst coated with platinum and palladium on the carrier, a) Determining whether the integration distance is greater than the set distance from the set time point; b) when the integration distance is greater than the set distance from the set time point, raising the diesel oxidation catalyst rear end temperature above the set temperature; c) determining whether the efficiency of the diesel oxidation catalyst is less than the set efficiency; And d) regenerating the diesel oxidation catalyst when the efficiency of the diesel oxidation catalyst is smaller than the set efficiency.

The step of raising the diesel oxidation catalyst rear end temperature above a predetermined temperature may be performed by post injection or secondary injection of the first preset fuel amount.

The efficiency of the diesel oxidation catalyst may be defined as the ratio between the initial and the current heat of oxidation generated in the diesel oxidation catalyst by the exhaust gas.

The regenerating of the diesel oxidation catalyst may be performed by post-injection or secondary injection of the second preset fuel amount greater than the first preset fuel amount for a predetermined time.

The method for regenerating the diesel oxidation catalyst may include: e) regenerating the diesel oxidation catalyst and then raising the rear end temperature of the diesel oxidation catalyst to a predetermined temperature or more; And f) re-determining whether the efficiency of the diesel oxidation catalyst is less than the set efficiency. When the efficiency of the oxidation catalyst is again smaller than the set efficiency, the failure code may be stored.

In the above steps c) and f), if the efficiency of the diesel oxidation catalyst is greater than or equal to the set efficiency, the method may further include resetting the set time point.

As described above, according to the present invention, it is possible to improve the purification efficiency and fuel economy of the exhaust gas by accurately determining the timing of removing the sulfur poisoning.

In addition, since an oxidation catalyst coated with a platinum and palladium may be used, the manufacturing cost is lowered.

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

1 is an example of an exhaust apparatus to which a regeneration method of a diesel oxidation catalyst according to an exemplary embodiment of the present invention may be applied.

As shown in FIG. 1, the internal combustion engine includes an engine 10, a turbocharger 20, a Diesel Oxidation Catalyst (DOC) 30, an exhaust pipe 40, and a controller 50. .

Engine 10 converts chemical energy into mechanical energy by combusting a mixture of fuel and air. The engine 10 is connected to the intake manifold 18 to receive air into the combustion chamber 12, and is connected to the exhaust manifold 16 so that the exhaust gas generated in the combustion process is collected in the exhaust manifold 16. do. An injector 14 is mounted in the combustion chamber 12 to inject fuel into the combustion chamber 12.

Although a diesel engine is illustrated here, a gasoline engine may be used. When using a gasoline engine, a mixer is introduced into the combustion chamber 12 through an intake manifold, and an ignition plug for ignition is mounted on the combustion chamber 12.

The injector 14 may also be mounted in front of the diesel oxidation catalyst 30 of the exhaust pipe 40. For convenience, the case of additional injection through the injector 14 mounted on the engine 10 is called post injection, and the case of additional injection through the injector 14 mounted on the exhaust pipe 40 is called secondary injection. . In the case of the secondary injection, the temperature of the rear end portion of the diesel oxidation catalyst 30 is increased by the heat of oxidation generated in the oxidation process occurring in the diesel oxidation catalyst 30.

The exhaust pipe 40 is connected to the exhaust manifold 16 to discharge the exhaust gas collected therein to the outside of the vehicle. The diesel oxidation catalyst 30 is mounted on the exhaust pipe 40 to oxidize carbon monoxide and hydrocarbons contained in the exhaust gas to carbon dioxide. If necessary, a diesel particulate filter (DPF), a nitrogen oxide sorbent catalyst (Lean NOx Trap; LNT), and the like are mounted on the exhaust pipe 40, respectively. Particulate Materials (PM) ) And nitrogen oxides.

The turbocharger 20 uses the energy of the exhaust gas to rotate a turbine (not shown) to increase the suction amount of air.

The diesel oxidation catalyst 30 oxidizes carbon monoxide and hydrocarbons contained in the exhaust gas discharged through the exhaust pipe 40 to carbon dioxide. To this end, as the diesel oxidation catalyst 30, a catalyst coated with platinum (Pt) and palladium (Pd) on an alumina carrier is used.

Meanwhile, first and second temperature sensors 52 and 54 are mounted at the front end and the rear end of the diesel oxidation catalyst 30, respectively, to measure the front end temperature and the rear end temperature of the diesel oxidation catalyst 30.

The controller 50 may be implemented by one or more processors operating by a set program, which may be programmed to perform each step of the regeneration method of a diesel oxidation catalyst according to an embodiment of the present invention.

The controller 50 is connected to the first and second temperature sensors 52 and 54, respectively, and receives signals for the front end temperature and the rear end temperature of the diesel oxidation catalyst 30 and is connected to the injector 14. To control the operation of the injector 14.

2 is a block diagram of a system for performing a regeneration method of a diesel oxidation catalyst according to an embodiment of the present invention.

As shown in FIG. 2, a system for performing a regeneration method of a diesel oxidation catalyst according to an exemplary embodiment of the present invention includes first and second temperature sensors 52 and 54, an integration distance sensor 56, a controller 50, And an injector 14. Since the first and second temperature sensors 52 and 54, the controller 50, and the injector 14 of the above components have been described above, a detailed description thereof will be omitted.

The integration distance sensor 56 measures the integration distance of the vehicle from the set time point and transmits a signal thereof to the controller 50. It is apparent to those skilled in the art that such integration distance sensor 56 is conventionally attached to a vehicle.

3 is a flowchart of a regeneration method of a diesel oxidation catalyst according to an embodiment of the present invention.

As shown in FIG. 3, the regeneration method of the diesel oxidation catalyst according to the embodiment of the present invention starts by measuring an integration distance from a set time point (S110). That is, the integration distance sensor 56 measures the integration distance from the set time point and applies a signal thereof to the controller 50. The set time point may be an initial driving time point after purchase of a vehicle or a previous regeneration time point of the diesel oxidation catalyst 30.

Here, the regeneration of the diesel oxidation catalyst 30 refers to removing sulfur poisoned by the diesel oxidation catalyst.

Thereafter, the controller 50 determines whether the integrated distance is greater than the set distance (for example, 1500 km) from the set time point (S120). Here, the set distance can be determined to be a distance at which a person skilled in the art needs to examine whether the regeneration of the diesel oxidation catalyst 30 is necessary through data such as experiments.

If the integrated distance is less than or equal to the set distance from the time set in step S120, the integration distance sensor 56 continuously measures the integrated distance from the set time point (S110).

If the integrated distance is greater than the set distance from the time point set in the step S120, the controller 50 increases the rear end temperature of the diesel oxidation catalyst 30 above the set temperature (S130). The set temperature may be 250 ° C. As shown in FIG. 4, when the rear end temperature of the diesel oxidation catalyst 30 is 250 ° C. or more, the rear end temperature of the diesel oxidation catalyst 30 is always greater than the front end temperature of the diesel oxidation catalyst 30. This means that the diesel oxidation catalyst 30 is warmed up sufficiently to start the oxidation reaction of hydrocarbon and carbon monoxide in the diesel oxidation catalyst 30. Therefore, in the region where the rear end temperature of the diesel oxidation catalyst 30 is 250 ° C. or more, the efficiency of the diesel oxidation catalyst 30 can be measured accurately.

The step of raising the rear end temperature of the diesel oxidation catalyst 30 above the set temperature is performed by the controller 50 controlling the injector 14 to post injection or secondary injection the first set fuel amount. The first preset fuel amount is a value determined through experiments, and is a fuel amount sufficient to raise the rear end temperature of the diesel oxidation catalyst 30 above the set temperature. In addition, the after injection injection injector may be separately installed in the engine 10 to control the after injection.

When the rear end temperature of the diesel oxidation catalyst 30 rises above the set temperature, the controller 50 determines whether the efficiency of the diesel oxidation catalyst 30 is smaller than the set efficiency (S140). The efficiency of the diesel oxidation catalyst 30 is defined as the initial and current ratio of the amount of heat of oxidation generated in the diesel oxidation catalyst 30 by exhaust gas, and the amount of heat of oxidation Q generated in the diesel oxidation catalyst 30 is represented by the following equation. Calculated by

Where m is the mass of the exhaust gas, C _p is the specific heat of the exhaust gas, T _out is the temperature at the rear end of the DOC, and T _in is the temperature at the front end of the DOC.

Therefore, the efficiency DOC _eff of the diesel oxidation catalyst 30 is calculated by the following equation.

Here, Q _cur is the heat of oxidization generated in the current diesel oxidation catalyst, Q _fre means the heat of oxidation generated in the first diesel oxidation catalyst. For example, the efficiency of the diesel oxidation catalyst 30 (DOC _eff) means a diesel oxidation catalyst (30) immediately after production is 1, and the efficiency of the diesel oxidation catalyst 30 (DOC _eff) is 0, the catalyst is It means a missing or broken condition.

Q _fre is a value stored through the experiment when the diesel oxidation catalyst is made, Q _cur is calculated by the controller 50 using the difference in temperature before and after the diesel oxidation catalyst (30).

On the other hand, the set efficiency refers to the efficiency of the diesel oxidation catalyst 30 necessary to meet the exhaust gas regulation, the designer sets in advance through experiments and the like.

If the efficiency of the diesel oxidation catalyst 30 in the step S140 is greater than or equal to the set efficiency, it is determined that the diesel oxidation catalyst 30 is operating normally, reset the current time point to the set time (S190), the present invention The regeneration method of the diesel oxidation catalyst according to the embodiment of is terminated.

If the efficiency of the diesel oxidation catalyst 30 in the step S140 is less than the set efficiency, it is determined that the sulfur poisoned in the diesel oxidation catalyst 30 more than the limit, the controller 50 regenerates the diesel oxidation catalyst 30. (S150). The step of regenerating the diesel oxidation catalyst may be carried out by post-injection or secondary injection of a second preset fuel amount greater than the first preset fuel amount for a set time. The second preset fuel amount is determined by experiment as an amount of fuel that can be raised to a temperature (for example, 450 ° C.) at which the activity of the diesel oxidation catalyst 30 can be restored. In addition, the set time is sufficient time for the diesel oxidation catalyst 30 to be regenerated when exposed to a temperature (eg, 450 ° C.) capable of restoring the activity of the aforementioned diesel oxidation catalyst 30 (eg, 1). Min), determined by experiment (see FIG. 5).

Thereafter, the controller 50 raises the rear end temperature of the diesel oxidation catalyst 30 again above the set temperature (S160). The step S160 is performed by post-injection or second-injection of the first set amount of fuel as in step S130.

When the rear end temperature of the diesel oxidation catalyst 30 rises above the set temperature, the controller determines again whether the efficiency of the diesel oxidation catalyst 30 is smaller than the set efficiency (S170).

If the rear end temperature of the diesel oxidation catalyst 30 in step S170 is higher than the set temperature, since the diesel oxidation catalyst 30 is operating normally (that is, if the regeneration is properly), the controller 50 sets the current time point. (S1990) and the regeneration method of the diesel oxidation catalyst according to the embodiment of the present invention is terminated.

If the rear end temperature of the diesel oxidation catalyst 30 in step S170 is less than the set temperature, the regeneration was performed, but the case is not properly reproduced, so that the control unit 50 determines that the failure and stores the fault code (S180), the implementation of the present invention The regeneration method of the diesel oxidation catalyst according to the example ends.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and easily changed and equalized by those skilled in the art from the embodiments of the present invention. It includes all changes to the extent deemed acceptable.

1 is an example of an exhaust apparatus to which a regeneration method of a diesel oxidation catalyst according to an exemplary embodiment of the present invention may be applied.

2 is a block diagram of a system for performing a regeneration method of a diesel oxidation catalyst according to an embodiment of the present invention.

3 is a flowchart of a regeneration method of a diesel oxidation catalyst according to an embodiment of the present invention.

Figure 4 is a graph showing the front and rear temperature of the diesel oxidation catalyst over time.

Figure 5 is a graph showing the relationship between temperature and time to recover the activity of the oxidation catalyst after sulfur poisoning.

Claims (6)

 In the regeneration method of the diesel oxidation catalyst to remove the sulfur poisoning of the diesel oxidation catalyst for oxidizing hydrocarbons and carbon monoxide in the exhaust gas, a) determining whether the integration distance is greater than the set distance from the set time point; b) when the integration distance is greater than the set distance from the set time point, raising the diesel oxidation catalyst rear end temperature above the set temperature; c) determining whether the efficiency of the diesel oxidation catalyst is less than the set efficiency; And d) regenerating the diesel oxidation catalyst if the efficiency of the diesel oxidation catalyst is less than the set efficiency; Regeneration method of the diesel oxidation catalyst comprising a. The method of claim 1, The step of raising the diesel oxidation catalyst rear end temperature above a predetermined temperature is carried out by post-injection or secondary injection of the first set amount of fuel. The method of claim 1, The efficiency of the diesel oxidation catalyst is a method of regenerating a diesel oxidation catalyst, characterized in that the first and the current ratio of the heat of oxidation generated in the diesel oxidation catalyst by the exhaust gas. 3. The method of claim 2, The regenerating method of the diesel oxidation catalyst is carried out by post-injection or secondary injection of the second preset fuel amount greater than the first preset fuel amount for a set time. The method of claim 1, e) after regenerating the diesel oxidation catalyst, re-raising the diesel oxidation catalyst rear end temperature above a set temperature; And f) determining again whether the efficiency of the diesel oxidation catalyst is less than the set efficiency; Include more, And storing the fault code when the efficiency of the oxidation catalyst is smaller than the set efficiency again. The method of claim 5, And resetting the set time point when the efficiency of the diesel oxidation catalyst in the steps c) and f) is equal to or greater than the set efficiency.

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