Electric three-way catalytic converter with heat exchange function

Abstract

The invention relates to an electric three-way catalyst with a heat exchange function, which is characterized in that firstly, tail gas passes through a plasma net, nitrogen oxide is ionized in an oxygen-deficient environment, ionic oxygen reacts with residual carbon monoxide and hydrocarbon in the tail gas to generate carbon dioxide and water, and the ionic nitrogen regenerates nitrogen in the oxygen-deficient environment; secondly, after the treated tail gas passes through a streaming partition plate, low-flux external aerobic air is introduced, the low-flux external aerobic air is mixed with the tail gas and then passes through a low-temperature combustion net, and residual carbon monoxide and hydrocarbon are combusted under the aerobic condition to generate carbon dioxide and water; thirdly, the tail gas obtained after sufficient combustion is sufficiently cooled through a heat exchanger, and energy recycling is achieved through the heat exchanger; fourthly, the cooled tail gas passes through activated carbon (or ceramic) and an HEPA filter screen, and tail gas harmlessness and particle capturing are achieved; precious metal is not used to reduce the cost, the heat efficiency can be improved based on heat recycling of tail gas, and the emission standard can be improved through particle capturing after tail gas cooling.

Description

Technical Field

[0001] The invention relates to an electric three-way catalytic converter with heat exchange. Background Art

[0002] With a huge number of vehicles in society, the problem of air pollution caused by vehicle exhaust has always been a hot topic. Under existing technical conditions, the thermal efficiency of internal combustion engines is relatively low, resulting in a huge waste of energy. While most of the energy is carried away in the form of high-temperature exhaust gas, a large amount of pollutants are also discharged into the atmosphere along with the exhaust gas, causing air pollution. The main pollutants are nitrogen oxides, carbon monoxide and hydrocarbons.

[0003] The existing automobile exhaust treatment mainly uses three-way catalytic converters. The mainstream three-way catalytic converters use platinum, rhodium, palladium precious metals and rare earth coatings on the surface of a carrier (such as alumina) as catalysts to promote the redox reaction of exhaust gas at a suitable temperature to achieve the purpose of purification. The use of precious metals determines its relatively high cost.

[0004] The exhaust treatment devices based on precious metal and rare earth coated catalysts generally have a good operating temperature range of 400-800 degrees Celsius. They generally do not work below 200 degrees Celsius, and are prone to sintering and permanent failure at temperatures exceeding 1000 degrees Celsius. This also causes emissions to fail to meet standards during the vehicle startup phase and when the ambient temperature is low.

[0005] The improvement of emission standards, especially the increasingly stringent requirements for particulate emissions, has posed a huge challenge to traditional three-way catalytic technology. Summary of the invention

[0006] The invention relates to an electric three-way catalytic converter with heat exchange. In the first step, the tail gas passes through a plasma net to ionize nitrogen oxides in an oxygen-deficient environment, and the ionized oxygen reacts with the remaining carbon monoxide and hydrocarbons in the tail gas to generate carbon dioxide and water, and the ionized nitrogen regenerates nitrogen in the oxygen-deficient environment; the second step is that the treated tail gas passes through a bypass baffle, and low-flux external aerobic air is introduced, and after mixing with the tail gas, it passes through a low-temperature combustion net, and the remaining carbon monoxide and hydrocarbons are burned under aerobic conditions to generate carbon dioxide and water; the third step is that the tail gas after full combustion is fully cooled through a heat exchanger, and energy is recovered and utilized through the heat exchanger; the fourth step is that the cooled tail gas passes through an activated carbon filter (or a ceramic filter) and a HEPA filter to achieve harmlessness of the tail gas and particle capture; not using precious metals can reduce costs, and heat recovery based on tail gas can improve thermal efficiency. After the tail gas is cooled, it is convenient to capture particles, which can improve emission standards.

[0007] The implementation scheme of the present invention is divided into four functional areas, including the nitrogen oxide plasma decomposition area; the carbon monoxide and hydrocarbon low-temperature combustion area; the heat exchange cooling and energy recovery area; the exhaust gas harmless filtration and particle capture area after cooling: (1) Plasma decomposition of nitrogen oxides: Nitrogen oxides, one of the main pollutants in exhaust gas, are generated by the reaction of nitrogen and oxygen during high-temperature combustion. Generally, they are generated in large quantities when the temperature exceeds 1200 degrees Celsius. Accurate control of the combustion temperature and oxygen supply can reduce the generation of nitrogen oxides. Under high-temperature conditions, the generation and decomposition of nitrogen oxides is a reversible chemical equilibrium reaction. Oxygen-rich environmental conditions will promote the synthesis of nitrogen oxides, while oxygen-deficient environmental conditions will promote the decomposition of nitrogen oxides. Under the premise that the engine is operating normally, the exhaust gas is in an oxygen-deficient state. Under the premise that high-voltage direct current with a preset voltage is passed through the plasma grid array, the nitrogen oxides in the exhaust gas are ionized when passing through the plasma grid array, and the nitrogen oxides are decomposed into ionized nitrogen and ionized oxygen. Among them, ionized oxygen is more likely to react with residual carbon monoxide and hydrocarbon components to generate carbon dioxide and water, while ionized nitrogen will regenerate nitrogen in an oxygen-deficient state. (2) Low-temperature combustion of carbon monoxide and hydrocarbons: After the tail gas passes through the plasma net array, the nitrogen oxides are reduced, but the remaining carbon monoxide and hydrocarbons are difficult to remove in an oxygen-deficient environment. On the premise of using a flow baffle to separate the plasma net array, a micro air pump (it is recommended to purchase industrial finished products) is used to introduce low-flux external air. While providing oxygen, the temperature of the tail gas is appropriately reduced to avoid the re-generation of nitrogen oxides. The oxygen-containing air is mixed with the tail gas to form a low-concentration combustible gas. When passing through the low-temperature combustion net, it is ignited under the action of the ignition voltage (lower than the plasma decomposition voltage), realizing low-temperature combustion of the combustible gas and oxidizing the remaining carbon monoxide and hydrocarbons into carbon dioxide and water. Due to the low combustion temperature, this process is not easy to generate new nitrogen oxides; (3) Heat exchange cooling and energy recovery: After the exhaust gas passes through the plasma net array, the overall temperature will rise slightly. After mixing with the external air, it will drop significantly. After passing through the low-temperature plasma combustion net, the temperature will rise slightly again. The overall temperature remains stable. There is still a large amount of heat energy in the exhaust gas. In the process of passing through the heat exchanger, the outside air is used as the cooling medium (refrigerant). It enters the cooling channel from the tail end of the equipment and moves along the spiral curve under the action of the heat exchanger baffle. After efficiently absorbing heat, the temperature rises and is discharged from the outlet. The high-temperature air can be used as an energy source for power generation, heating or directly supplied to engines with heat recovery. By properly adjusting the stroke of the heat exchanger, the exhaust gas temperature can be reduced to close to the ambient temperature. At the same time, the water vapor in the exhaust gas will turn into liquid water. A drain outlet is set at the rear of the heat exchanger. An automatic drainer is installed at the drain outlet (it is recommended to purchase industrial finished products) to achieve automatic drainage under the premise of isolating the outside air. (4) Exhaust gas filtration and particle capture after cooling: After the exhaust gas is cooled and the water is separated, the pollutants have been purified to a great extent. Since the exhaust gas temperature is close to the outside temperature at this time, the exhaust gas can be purified more thoroughly through activated carbon filters (or ceramic filters) and high-efficiency air filters (HEPA). The activated carbon filter can adsorb most organic pollutants and filter particles larger than 5 microns. The high-efficiency air filter (HEPA) can achieve efficient filtration of particles between 2.5 and 5 microns. The ceramic filter can also achieve the same accuracy and can withstand higher temperatures.

[0008] The three-way catalytic converter of the present invention is an active catalytic converter, which can adjust the plasma network voltage, the low-temperature combustion network voltage and the air pump flow, and actively adjust the catalytic converter to achieve the best operating state in coordination with the data of the corresponding temperature sensor and the oxygen sensor.

[0009] The present invention adopts a detachable structure, and the main internal components such as the plasma screen and the filter screen can be easily replaced, which reduces the repair and maintenance costs. The high-voltage generator, micro air pump and automatic drainer can all use mature industrial products, and the overall cost is transparent and controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific implementation schemes and in conjunction with the accompanying drawings. Figure 1 is a cross-sectional view of an electric three-way catalytic converter with heat exchange according to the present invention, Figure 2 The figure is a schematic diagram of the appearance of an electric three-way catalytic converter with heat exchange according to the present invention. DETAILED DESCRIPTION

[0011] Attached Figure 1 An embodiment of the present invention is shown. It should be noted that these and subsequent drawings are only examples and are not drawn in proportion. The drawings only show the parts related to the present invention rather than all structural processes, and should not be used as a limitation on the actual scope of protection required by the present invention.

[0012] Attached Figure 1 It is a cross-sectional view of the present invention, in which the numbers respectively represent: 1, exhaust gas inlet; 2, plasma screen electrode interface; 3, flow-around baffle; 4, external air inlet; 5, low-temperature combustion screen electrode interface; 6, front sensor mounting hole; 7, heat exchanger refrigerant outlet; 8, heat exchanger flow-around baffle; 9, rear sensor mounting hole; 10, activated carbon (or ceramic) filter; 11, HEPA filter; 12, exhaust gas outlet; 13, plasma screen; 14, low-temperature combustion screen; 15, heat exchanger refrigerant inlet; 16, drain outlet.

[0013] The external air inlet 4 is connected to a micro air pump to input low-flow external air, and the drain outlet 16 is connected to an automatic drainer to realize automatic discharge of liquid water. Under the premise that the heat exchanger uses air as a refrigerant for cooling, the heat exchanger refrigerant inlet 15 is connected to an air filter, and the heat exchanger refrigerant outlet 7 is directly connected to a device that requires high-temperature air input for heat recovery, or connected to a cooling fan to speed up air circulation (without recovering heat energy).

[0014] The plasma net 13 is formed into a plasma net array by combining multiple pieces. The formation of the plasma electric field is closely related to the distance between the nets and the voltage. Under the premise of rated voltage, in a preferred embodiment, the distance between the electrodes is 10 mm, and 6 plasma nets are used to form 3 pairs of plasma net arrays. The plasma net uses corrosion-resistant high-temperature stainless steel materials (such as 310S) or titanium alloy materials, and the electrodes are insulated and protected by a ceramic insulating layer; the low-temperature plasma combustion net 12 is composed of two electrode nets, and uses corrosion-resistant high-temperature stainless steel materials (such as 310S) or titanium alloy materials.

[0015] The front sensor mounting hole 6 and the rear sensor mounting hole 9 are respectively installed with a temperature sensor or an oxygen sensor for monitoring the oxygen-added combustion effect and temperature of the exhaust gas.

[0016] The specific embodiments described above further illustrate the purpose, technical solutions and effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An electric three-way catalytic converter with heat exchange, characterized in that: Along the exhaust direction, a plasma net array, a flow baffle, an external air inlet, a low-temperature plasma combustion net, a front sensor, a heat exchange unit, a rear sensor, a drain outlet and a filter net are arranged in sequence, forming four functional areas of plasma decomposition, low-temperature combustion, heat exchange and filtration respectively; (1) Plasma decomposition zone: It is composed of a plasma grid array. The number of plasma grid arrays can be adjusted according to actual needs. The electrodes are connected to an external plasma high voltage generator through reserved holes in the shell; (2) Low-temperature combustion zone: It consists of a flow baffle, an external air inlet and a low-temperature combustion net. The flow baffle isolates the combustion zone from the plasma decomposition zone. The external air inlet is connected to an external micro air pump to input oxygen-containing air. The low-temperature combustion net is connected to an external high-voltage generator through a reserved hole in the shell. A temperature or oxygen sensor is installed through the front sensor hole. (3) Heat exchange area: It consists of a heat exchanger and a drain port. The interior of the heat exchanger is a straight-through pipe. The refrigerant inlet is set at the rear end of the catalyst. A flow baffle is set in the refrigerant channel to form a spiral cooling channel. The refrigerant outlet is set above the catalyst. A drain port is set at the rear end of the heat exchanger to install an automatic drainer. The temperature sensor is installed through the rear sensor hole. (4) Filter area: It is composed of activated carbon filter (or ceramic filter) and high-efficiency air filter (HEPA). The type and quantity of filter elements can be adjusted according to actual needs.

2. The electric three-way catalytic converter with heat exchange according to claim 1, characterized in that: The shell of the three-way catalytic converter is made of stainless steel, and the surface can be sprayed or wrapped with insulation material.

3. The electric three-way catalytic converter with heat exchange according to claim 1, characterized in that: The three-way catalytic converter housing is a detachable structure and is fastened and connected by screws or bolts.

4. The electric three-way catalytic converter with heat exchange according to claim 1, characterized in that: The plasma net and low-temperature plasma combustion net are made of corrosion-resistant high-temperature stainless steel or titanium alloy, with a honeycomb mesh structure, and the edges and electrodes are wrapped with a ceramic insulation layer.

5. The electric three-way catalytic converter with heat exchange according to claim 1, characterized in that: Two adjacent plasma nets form a plasma action area, and the positive and negative poles of the plasma generator are connected respectively through electrodes. The positive and negative voltages are symmetrical values. Multiple groups of plasma nets form an array to increase the range of the plasma action area. After the exhaust gas passes through the plasma net, the overall charge is neutral.

6. The electric three-way catalytic converter with heat exchange according to claim 1, characterized in that: The two adjacent low-temperature combustion networks form a low-temperature combustion area, which are connected to the positive and negative poles of independent high-voltage generators through electrodes. The ignition voltage is lower than the plasma network voltage, and the positive and negative voltages are symmetrical values. The overall charge of the exhaust gas is neutral after passing through the low-temperature combustion network; the first end of the combustion network (the end where the exhaust gas enters) can also be connected to the zero potential of the plasma generator, and the secondary end of the combustion network (the end where the exhaust gas leaves) can be connected to the negative potential of the plasma generator to form a negative voltage ignition. After the exhaust gas passes through the low-temperature combustion network, the overall charge is negative and has negative ion characteristics.

7. The electric three-way catalytic converter with heat exchange according to claim 1, characterized in that: The pipes and flow-around baffles in the heat exchange area are made of stainless steel. Air is generally used as the heat exchange refrigerant. Water or oil can be used as the coolant when the heat exchange efficiency needs to be improved or in specific circumstances.

8. The electric three-way catalytic converter with heat exchange according to claim 1, characterized in that: Activated carbon filters (or ceramic filters) and high-efficiency air filters (HEPA) are installed in the filtration area along the direction of exhaust gas travel.

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