KR20120010352A - Exhaust gas purifying device utilize electrolysis hydrogen for SCR reduction - Google Patents

Abstract

PURPOSE: An exhaust purifying apparatus using electrolyzed hydrogen as the reducing agent of a selective catalyst reduction reaction is provided to charge power in a storage battery and use the stored electric energy from the storage battery by including a thermoelectric element. CONSTITUTION: An exhaust purifying apparatus includes a nitrogen oxide reducing catalyst part(1) and a particle eliminating filter part(2). The nitrogen oxide reducing catalyst part and the particle eliminating filter part are successively arranged from the upstream of exhaust gas flow. The nitrogen oxide reducing catalyst part and the particle eliminating filter part are inserted into the exhaust pipe of a diesel engine(3). The apparatus includes a first storage battery(7) and an electrolyzing unit(4). The first storage battery charges or supplies power generated from the drive of the diesel engine. The electrolyzing unit is in connection with the first storage battery and is driven based on the power of the first storage battery. The electrolyzing unit generates hydrogen and oxygen based on the electrolysis of water. The hydrogen is supplied to the front part of the nitrogen oxide reducing catalyst part to be used as a reducing agent.

Description

Exhaust gas purifying device utilizes electrolysis hydrogen for SCR reduction

The present invention relates to an exhaust gas purification apparatus utilizing hydrogen generated by an electrolysis reaction as a selective catalytic reduction (SCR) reducing agent, and more particularly, a nitrogen oxide reduction catalyst (LNC) and a particle removal filter. In an exhaust gas purifying apparatus including a diesel particulate filter (DPF), hydrogen is obtained by electrolyzing water by using surplus power of a battery or by using a thermoelectric element according to the exhaust temperature as a heat source, and exhaust gas thereof. It relates to a device utilized as a reducing agent of the purification device.

Diesel engines are used in various industries as well as automobiles and ships based on good fuel efficiency and excellent reliability, and the demand is continuously increasing due to high power and high load operation. While an increase in such low fuel consumption diesel engine vehicles is expected, diesel engines have a problem of inevitably emitting NOx and particulate matter (PM). Various engine related technologies such as high pressure fuel injection system, new combustion concept, and exhaust gas recirculation (EGR) have been developed and applied to reduce nitrogen oxides and particulate matters emitted from diesel engines. The application of exhaust aftertreatment technology is inevitable due to limitations in satisfying regulations with these technologies alone.

Therefore, research on the development of oxidation catalysts or diesel particulate filters (DPF), catalysts for reducing nitrogen oxides, and exhaust post-treatment devices has been conducted.

Nitrogen oxide reduction method (SCR) is a method of modularizing the catalyst and installing it in the middle of the flow of exhaust gas, and spraying a reducing agent to decompose harmful nitrogen oxide into harmless nitrogen and water vapor through reduction reaction in the catalyst layer to reduce the emission nitrogen oxide. The reaction in which NO is decomposed varies depending on the process and reaction conditions, but the main reaction is decomposed through a reaction such as the following formula.

6NO + 4NH ₃ → 5N ₂ + 6H ₂ O

4NO + 4NH ₃ + O ₂ → 4N ₂ + 6H ₂ O

2NO + 2H ₂ → N ₂ + 2H ₂ O

2NO + 2CO → N ₂ + 2CO ₂

In this case, as the reducing agent used in the selective catalytic reduction reaction, ammonia, urea, or hydrocarbons may be used, but ammonia (NH ₃ ) and urea, etc., have a disadvantage in that an infrastructure that can be supplied separately is preferred, and hydrocarbons are preferred. Examples include light oil, kerosene, propylene, propane, ethylene, butylene, and methane. However, in the case of hydrocarbons, there is a problem that causes deterioration of fuel economy by using diesel fuel.

In addition, a diesel particulate filter (DPF) method is widely used as a method of reducing particulate matter, and may be classified into a continuous regeneration type or a forced regeneration type according to a method of continuously regenerating PM collected in the filter. The continuous regeneration method converts NO into NO ₂ by the oxidation catalyst installed in the front of the DPF, and regenerates PM. Nitrogen oxide reduction performance and the removal efficiency of particulate matter at 250 ~ 600 ℃ can be improved more.

Accordingly, the present invention is to solve the problems of the prior art and has an electrolysis device which is driven by the surplus power of the battery which can be charged or supplied by the driving of the diesel engine, the hydrogen and oxygen in the electrolysis device By using the generated hydrogen as a reducing agent of the nitrogen reduction catalytic reduction reaction, it is possible to supply the reducing agent uniformly and stably without additional equipment, and to increase the nitrogen reduction efficiency in comparison with other reducing agents. There is this.

 In addition, the present invention can utilize the waste heat of the exhaust gas passing through the exhaust pipe as a charging of the battery and other power source using the thermoelectric element for power generation.

In addition, hydrogen generated by the present invention can be used as a raw material of the fuel cell, oxygen can be sucked into the diesel engine to increase the engine efficiency.

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an electrolytic gas purification apparatus including a nitrogen oxide reduction catalyst portion and a particle removal filter portion inserted into an exhaust pipe of a diesel engine sequentially from upstream with respect to the flow of exhaust gas. The present invention provides an exhaust gas purifying apparatus including an apparatus to generate hydrogen and oxygen by electrolyzing water in the electrolytic apparatus, and supplying the generated hydrogen to the front end of the nitrogen oxide reducing catalyst unit.

Hereinafter, the present invention will be described in more detail.

The exhaust gas purification apparatus of the diesel engine according to the present invention includes a nitrogen oxide reduction catalyst portion and a particle removal filter portion (hereinafter referred to as 'DPF') sequentially in the exhaust gas flow. The nitrogen oxide reduction catalyst unit is a selective reduction catalytic reaction (hereinafter referred to as 'SCR') to reduce nitrogen oxides by injecting diesel, and has an advantage in that the reaction rate by oxygen is fast and secondary pollutants are not generated. The reduced nitrogen oxides are not only removed by the nitrogen reduction catalyst but additionally removed by the DPF catalyst in the mid-temperature zone of 250 to 350 ° C., thereby effectively removing the nitrogen oxides. Removal and at the same time carbon monoxide and hydrocarbons are removed.

In the SCR, the present invention is equipped with an electrolysis device, it is possible to use hydrogen as a reducing agent of the nitrogen oxide reduction catalyst portion. It is possible to supply the reducing agent of the selective catalytic reaction uniformly and stably without the need for additional equipment by using a reducing agent such as ammonia, and has an excellent effect of reducing nitrogen compared to other reducing agents.

The electrolysis device includes a water tank for storing water and an electrode rod installed in the water tank to separate hydrogen and oxygen from water through an electrolysis reaction. The electrodes are respectively installed as a positive electrode and a negative electrode to electrolyze water when power is applied. At this time, oxygen gas is generated at the anode and hydrogen gas is generated at the cathode.

At this time, the generated hydrogen and oxygen are stored in the hydrogen tank and oxygen tank, respectively. Hydrogen stored in the hydrogen tank is supplied to the front end of the nitrogen reducing catalyst portion to be used as a reducing agent of the SCR through the line. By doing so, it is possible to stably and uniformly supply hydrogen in the system without the need for a separate supply of reducing agent. In addition, the oxygen stored in the oxygen tank is sucked in the intake valve that can suck the oxygen in the front end portion of the diesel engine can increase the engine efficiency.

The electrolysis device receives power from a first storage battery capable of charging or supplying power generated from driving of a diesel engine. At this time, since the power supplied from the first storage battery uses extra power, there is no need to additionally provide a separate power supply device.

The present invention provides a power supply to the electrolysis device, comprising a first temperature sensor and a second temperature sensor as a temperature sensor for sensing the temperature of the exhaust gas in the exhaust pipe, the thermoelectric element connected to the temperature sensors It is possible to generate power due to the temperature difference between the first temperature sensor and the second temperature sensor. The generated power is charged into the additional storage battery, and thus the charged power can be supplied. By doing so, it is possible to construct an economic system by recovering waste heat to generate electric power and having an energy circulation structure using the same as a power source of an electrolysis device.

The thermoelectric device is for waste heat recovery power generation and is a device for generating power through the SEEBECK effect of the thermoelectric device. The rebecking effect refers to a phenomenon in which a current is generated in a circuit when two kinds of metals are connected in a ring shape and one contact is made high temperature and the other is made low temperature. Only the temperature difference between the two ends can generate electromotive force. In addition, the thermoelectric element may generate power continuously as long as heat remains in the system, and electromotive force may be generated even if the temperature is not constant, so that energy may be recycled by using a temperature difference of exhaust gas of a diesel engine.

The electrolysis device generates hydrogen and oxygen by electrolyzing water by receiving the extra power of the first storage battery or the waste heat of the exhaust gas from the second storage battery charged with the thermoelectric element for power generation as a power source. The generated hydrogen and oxygen are stored in a hydrogen tank and an oxygen tank, respectively, and hydrogen is constantly supplied from the hydrogen tank at the front end of the nitrogen reduction catalyst part for use as a reducing agent of the selective catalytic reduction reaction (SCR). In addition, the oxygen can be used to improve the engine efficiency by inducing the suction in the intake valve provided in the front end of the diesel engine.

In addition, the present invention not only uses hydrogen produced by itself as a reducing agent of the SCR, but also includes a fuel cell to supply hydrogen when there is remaining hydrogen, thereby generating power in the fuel cell. This power can be driven with other energy by recharging the batteries or by supplying the electric power device in another embodiment. This can exhibit a more complex effect by allowing the exhaust gas purification apparatus having the electrolysis device according to the present invention to have a hybrid driving engine. The complex effect means that the diesel engine can be driven in a situation where low efficiency and high power are required according to the driving environment of the engine, and the electric drive engine using a fuel cell can be driven in a situation where low noise and low power are required.

As described above, the hydrogen generated in the electrolysis device can be used as a reducing agent of the SCR to not only improve the efficiency of nitrogen reduction, but also reduce the nitrogen oxide economically and stably by having a system to supply itself. This is because when the hydrocarbon is used as a reducing agent, a high temperature of 450 ° C. is required for the performance of reducing nitrogen oxides. However, when hydrogen is used as a reducing agent, the nitrogen oxides are reduced at 150 ° C. because the high temperature is not required. It is suitable for the actual driving conditions and more effective. In particular, when hydrogen is further used as a reducing agent in a device using a conventional hydrocarbon as a reducing agent, the reduction rate may be greatly improved as the temperature range for reducing nitrogen oxide is widened.

As described above, in the case of mainly using ammonia (NH ₃ ) and a hydrocarbon as a reducing agent of the nitrogen reduction catalyst unit, the ammonia (NH ₃ ) is equipped with a separate device and requires the filling of ammonia (NH ₃ ), In the case of the hydrocarbon, the fuel efficiency is deteriorated by using diesel fuel, whereas the exhaust gas purifying apparatus according to the present invention utilizes hydrogen generated by electrolysis of water as a reducing agent by utilizing surplus power of a battery. It can supply itself uniformly and stably, and it is economical, and the nitrogen reduction effect is remarkably superior to other reducing agents.

In addition, the present invention includes a thermoelectric element capable of generating power by the temperature difference of the exhaust gas by using the waste heat of the exhaust gas emitted from the diesel engine exhaust pipe, thereby not only charging electric power to the storage battery, but also charging electric energy. There is an advantage to utilize.

1 is an aspect of an exhaust gas purifying apparatus according to the present invention
2 is another aspect of the exhaust gas purifying apparatus according to the present invention.

As an aspect of the present invention, an exhaust gas purification apparatus having an electrolysis device inserted into an exhaust pipe 11 of a diesel engine is shown in FIG. According to FIG. 1, the present invention includes a nitrogen reduction catalyst unit 1 for performing a selective reduction catalytic reaction from an upstream side according to the flow of exhaust gas, and a particle removal filter unit 2 is provided in series thereof. A first storage battery 7 capable of charging or supplying power generated from driving and an electrolysis device 4 connected to the first storage battery 7 and driven by the power of the first storage battery 7 are provided.

The electrolysis device 4 generates hydrogen and oxygen by electrolysis of water, and uses the hydrogen as a reducing agent of a selective reduction catalytic reaction by supplying the hydrogen to the front end of the nitrogen oxide reduction catalyst unit 1.

The electrolysis device 4 includes a water tank 5 for storing water and an electrode rod 6 installed at the water tank 5 to separate hydrogen and oxygen from water through an electrolysis reaction. Hydrogen and oxygen separated in the electrolysis device 4 are to be stored in the hydrogen tank 8 and the oxygen tank 9, respectively.

In another embodiment of the present invention, an exhaust gas purifying apparatus capable of generating and charging electric power by recovering waste heat of exhaust gas in an exhaust pipe 11 of a diesel engine is shown in FIG. 2. According to FIG. 2, another embodiment of the present invention further includes a first temperature sensor 12 and a second temperature sensor 13 for sensing a temperature of exhaust gas in the exhaust pipe 11, and a thermoelectric element connected to the temperature sensors. 14, a second storage battery 15 connected to the thermoelectric element 14 to charge electric power generated by the temperature difference between the first temperature sensor 12 and the second temperature sensor 13 is further included. Power of the biaxial battery 15 is supplied to the electrolysis device 4 to generate hydrogen and oxygen, and the hydrogen and oxygen are stored in the hydrogen tank 8 and the oxygen tank 9, respectively.

Hydrogen and oxygen generated by the electrolysis reaction as described above may include a pressure regulator to be supplied at a constant pressure in the stored hydrogen tank (8) and oxygen tank (9), respectively, and supply a predetermined amount through injection Done.

The hydrogen may further include a fuel cell driven by hydrogen as fuel. The fuel cell may supply electricity of an electric drive engine.

The oxygen is sucked by the intake valve provided at the front end of the diesel engine to improve the engine efficiency.

The present invention will be described in detail by way of examples.

However, the following examples are merely to illustrate the invention, but the content of the present invention is not limited by the following examples.

(Production Example 1)

The nitrogen oxide reduction catalyst was prepared as follows. Gamma alumina powder was mixed with acetic acid and distilled water to grind a wet ball mill for 24 hours to produce a uniform alumina slurry, and then washcoating a 400cpi cordierite honeycomb of 11.25 inches in diameter and 3 inches in length to carry alumina. After coating to 3g / in ³ , and dried at 120 ℃, it was baked at 120 ~ 550 ℃. The calcined alumina-supported cordierite dried body was impregnated into a solution prepared by dissolving platinum chloride with silver nitrate and a platinum precursor, and calcined by the same method as the alumina wash coating such that silver was impregnated with 2.0 to the weight of alumina and 0.001 wt% of a platinum catalyst component. It was.

(Manufacture example 2)

The particle removal filter was prepared as follows. In a 2 L flask, 252 g of polyvinylpyrrolidone (Aldrich Chemical, average molecular weight 10,000) is dissolved in 1 L of distilled water to make a homogeneous solution. 30.4 g of chloroplatinic acid was added thereto, and 1 L of methanol was added thereto, followed by stirring. The solution was refluxed at 80 ° C. for 6 hours and filtered to obtain 2,070 g of a dark brown platinum colloidal solution with a platinum content of 0.62% by weight. 15.4 g of ammonium molybdate and 10 g of potassium hydroxide were added to 250 mL of distilled water, followed by stirring to prepare an aqueous molybdenum (Mo) solution and an aqueous potassium (K) solution.

Platinum colloidal solution prepared above, molybdenum (Mo) aqueous solution and potassium (K) aqueous solution are mixed in the same weight ratio to obtain a catalyzed metal salt colloidal solution for the filter. Corning's 11.25 ˝ diameter 14 inch long, cell density 200 cpsi wall filter type ceramic filter is used as a support for the catalyzed filter.

The honeycomb monolith was deposited with 7% by weight of titania and silica mixed washcoat solution and then calcined dry. The colloidal solution for catalyzed filters described above was supported on the wash-coated support so that the platinum content was 0.27% by weight, the molybdenum content was 0.16% by weight, and the potassium content was 0.077% by weight. After drying for 3 hours at 120 ℃, it was baked for 4-6 hours at a temperature of 550 ℃ to prepare a filter for removing particulate matter.

(Example)

The nitrogen oxide reduction catalyst prepared in Preparation Example 1 and the particle removal catalyst prepared in Preparation Example 2 were successively connected, and then placed in a canning made of stainless steel. A Daewoo engine with a cooler was used. It is equipped with an electrolysis device and a hydrogen tank and an oxygen tank for storing hydrogen and oxygen generated in the electrolysis device, by adjusting the pressure regulator of the hydrogen tank to the hydrogen and hydrocarbon (diesel) at a constant pressure of the front end of the nitrogen reduction catalyst portion The nitrogen reduction test performance was measured by injecting through an index.

Table 1. Exhaust gas nitrogen oxide and particulate matter reduction test according to an embodiment of the present invention

In the nitrogen oxide and particulate matter reduction performance test according to the above embodiment, when the hydrocarbon was used as the reducing agent for reducing the nitrogen oxides, the reduction performance of the nitrogen oxides was shown at the high temperature portion, and when the hydrogen was used as the reducing agent, the reduction of the nitrogen oxides was shown at the low temperature portion. I could confirm that. As shown in Table 1, the reduction rate of nitrogen oxides of the diesel reducing agent and the hydrogen reducing agent is similar, but in the case of the diesel reducing agent, as the fuel of the vehicle is used as the reducing agent, the fuel consumption due to the amount used as the reducing agent is reduced while hydrogen In this case, as well as nitrogen oxide reduction performance of the diesel reducing agent level, as the fuel economy and the fuel economy is produced in the electrolysis device, it can be said that the hydrogen reduction agent in terms of fuel efficiency. In the case of using diesel and hydrogen as reducing agents, nitrogen oxides are reduced by hydrogen reducing agent when the exhaust gas is relatively low, and nitrogen oxides are reduced by diesel reducing agent in the relatively high part. have. In other words, when hydrogen is used as a reducing agent in a device using an existing hydrocarbon as a reducing agent, the reduction rate is also greatly improved as the temperature range for reducing nitric oxide is widened.

In the present invention as described above has been described by the specific matters and the specific embodiments and drawings as shown in the specific device diagram, which is provided only to help a more general understanding of the present invention, the present invention is not limited to the above embodiment. For those skilled in the art, various modifications and variations are possible from such description.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and all of the equivalents or equivalents of the claims as well as the claims to be described later will belong to the scope of the present invention. .

1 nitrogen reduction catalyst part 2 particle removal filter part
3: diesel engine 4: electrolysis device
5: water tank 6: electrode
7: first storage battery
8: hydrogen tank 9: oxygen tank
10: alternator
11: piping material
12: first temperature sensor 13: second temperature sensor
14 thermoelectric element 15 secondary battery

Claims (5)

The nitrogen oxide reduction catalyst (DeNOx catalyst) part 1 and the diesel particulate filter (DPF) part 2 inserted into the exhaust pipe 11 of the diesel engine 3 are sequentially disposed from the upstream with respect to the flow of the exhaust gas. In the exhaust gas purification device provided with,
A first storage battery 7 capable of charging or supplying electric power generated from driving of the diesel engine; An electrolysis device 4 connected to the first storage battery 7 and driven by electric power of the first storage battery 7, wherein the electrolysis device 4 generates hydrogen and oxygen through an electrolysis reaction of water. An exhaust gas purification device characterized by utilizing hydrogen as a reducing agent of a catalyst by supplying hydrogen to the front end of the nitrogen oxide reduction catalyst part (1).
The method of claim 1,
The electrolysis device 4 includes a water tank 5 for storing water, and an electrode rod 6 installed at the water tank to separate hydrogen and oxygen from water through an electrolysis reaction. Hydrogen and oxygen separated in (4) are stored in the hydrogen tank (8) and oxygen tank (9), respectively, characterized in that the exhaust gas purification device.
The method of claim 1,
The exhaust pipe 11 is provided with a first temperature sensor 12 and a second temperature sensor 13 for detecting the temperature of the exhaust gas, and the thermoelectric element 14 and the thermoelectric element 14 connected to the temperature sensors. It is connected to the second storage battery 15 for charging the power generated by the temperature difference between the first temperature sensor 12 and the second temperature sensor 13; further comprising the electrolysis device of the power of the second storage battery (4) To generate hydrogen and oxygen; The hydrogen and oxygen are exhaust gas purification device, characterized in that stored in the hydrogen tank (8) and oxygen tank (9), respectively.
The method according to claim 2 or 3,
The exhaust gas purification device further comprises a fuel cell capable of using hydrogen stored in the hydrogen tank (8) as fuel.
The method according to claim 2 or 3,
The exhaust gas purification device further comprises an inlet valve for sucking oxygen stored in the oxygen tank (9) at the front end of the diesel engine (3).

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