JP6028673B2 - Gas-liquid contact device for engine wet aftertreatment device - Google Patents

Description

  The present invention relates to a post-treatment device that wet-absorbs a specific gas component in exhaust gas, and more particularly, to a gas-liquid contact device that uses a liquid having a relatively high viscosity and contacts and removes the specific gas component.

  For the post-treatment of harmful substances discharged from the engine, for example, nitrogen oxide (NOx) components, conventionally, a method of reducing and purifying using a catalyst is generally used. For example, selection of adding urea water to the exhaust as a reducing agent A reducing catalyst is employed. In this method, it is necessary to increase the temperature to the operating temperature (about 200 ° C. or higher) of the catalyst that exhibits the NOx purification performance, and the apparatus tends to be large in order to diffuse the urea water into the exhaust gas. On the other hand, when the exhaust heat recovery system is actively introduced in accordance with the demand for improving the thermal efficiency of the engine and the fuel consumption efficiency, the exhaust temperature greatly decreases in the downstream area. Therefore, there is a need for a post-processing apparatus that can handle harmful emissions at a lower temperature.

  As a technique for removing the NOx component at a lower temperature while reducing the size of the aftertreatment device, a wet aftertreatment device using a liquid capable of absorbing NOx has been proposed (for example, Patent Document 1). As the NOx absorbing liquid, for example, water, an alkaline aqueous solution, or an ionic liquid is known, and the exhaust can be discharged to the outside after the NOx component is absorbed and removed by contacting the exhaust with a gas-liquid contact means. The NOx absorbing liquid is recovered, regenerated, returned to the storage means, and supplied again to the gas-liquid contact means.

JP2012-217918A

  In particular, a wet post-treatment apparatus using an ionic liquid having a viscosity higher than that of water can be separated from moisture by being used at 100 ° C. or higher. On the other hand, since the viscosity is relatively high, it is difficult to sufficiently atomize using a known liquid atomization mechanism. For example, since the above-mentioned urea water has a viscosity of about 0.005 Pa · s at room temperature, a control valve for supplying compressed air is provided on the urea water outflow outlet side, and the compressed air is sprayed on the outflowing liquid. A mechanism for atomization is known. However, the high-viscosity liquid handled in the present invention cannot be expected to be atomized by blowing off a gas wind, and such a liquid atomization mechanism is not effective.

  Therefore, a relatively high-viscosity liquid is uniformly supplied and dispersed throughout the gas-liquid contact device, and is in contact with the gas for a predetermined period of time to efficiently adsorb components to be removed (eg, NOx components). A new mechanism is required. That is, an object of the present invention is to provide a gas-liquid contact device having a structure and mechanism effective for uniform distribution of liquid in a wet aftertreatment device that absorbs and removes a specific gas component contained in exhaust from an engine by gas-liquid contact. Is to provide.

The invention according to claim 1 for solving the above-mentioned problem is arranged in the middle of the exhaust passage of the engine, and can absorb the specific gas component contained in the engine combustion exhaust gas more than water. In an engine wet aftertreatment device that uses a liquid having a high viscosity, the gas-liquid contact device includes a gas-liquid contact passage that brings the engine combustion exhaust into contact with the liquid.
The gas-liquid contact device is provided on a porous body having the partitioned cells in the gas-liquid contact passage, a gas introduction portion provided on one end side of the porous body, and one end side of the porous body. And at least one liquid injection valve and a distribution mechanism for distributing the liquid injected from the liquid injection valve to the gas-liquid contact passage on one end side of the porous body.
The distribution mechanism arranges a plurality of injection holes provided in the liquid injection valve in correspondence with a plurality of regions set in advance on one end side of the porous body, and the liquid injected toward each region Distributing to the adjacent gas-liquid contact passages through a plurality of through holes provided in the passage wall of the gas-liquid contact passage ,
Furthermore, according to the engine operating conditions, comprising a control means for controlling the liquid supply flow rate to the porous body,
The control means controls the liquid supply flow rate at the opening / closing frequency per unit time of the liquid injection valve during low speed and low load operation of the engine, and synchronizes with the engine rotation except during the low speed and low load operation. To control .

  According to a second aspect of the present invention, the liquid injection valve includes a seat mechanism that is electromagnetically opened and closed upstream of the plurality of nozzle holes arranged on a distal end surface, and the plurality of the plurality of liquid injection valves can be operated by a single sheet opening and closing operation. At least one droplet is generated in each of the nozzle holes and distributed to the plurality of regions.

  In the invention according to claim 3, the porous body has a rectangular or circular end surface shape, and the plurality of injection holes of the liquid injection valve are arranged in a shape corresponding to the end surface shape of the porous body. .

  5. The distribution mechanism according to claim 4, wherein the distribution mechanism receives and attaches the liquid sprayed to each region on one end side of the porous body, and the gas-liquid corresponding to each region. It has a distribution part which distributes to a contact passage.

According to a fifth aspect of the invention, the control means performs the liquid injection at a timing when the exhaust gas flow rate becomes small in synchronization with the engine rotation except during the low speed and low load operation and during the operation other than the transient operation. To be controlled .

In the invention according to claim 6, wherein said control means, during transient operation in synchronism with the engine Rotation, the liquid supply flow rate is controlled to temporarily increase.

  In the invention according to claim 7, the liquid is an ionic liquid having a viscosity at 25 ° C. of 0.01 Pa · s or more and maintaining a liquid state in a use environment.

  In the invention according to claim 8, the specific gas component is a nitrogen oxide component.

  The gas-liquid contact device of the present invention introduces the combustion exhaust gas introduced into the exhaust gas introduction section and the liquid injected from the liquid injection valve into the porous body in the same direction, while passing through the gas-liquid contact passage. The specific gas component is absorbed into the liquid. The distribution mechanism sets a plurality of regions with respect to one end surface of the porous body, and ejects liquid from the nozzle holes of the liquid injection valve corresponding to each region. The relatively viscous liquid reaches each region as a droplet and spreads on the wall surface of the gas-liquid contact passage in the porous body. Further, the plurality of through holes provided in the passage walls move downstream while flowing between adjacent passages, spread over the entire porous body, and increase the chance of contact with the combustion exhaust.

  Therefore, the liquid can be effectively distributed to the gas-liquid contact passage, and specific gas components such as NOx components can be absorbed and removed. Therefore, a small and highly efficient gas-liquid contact device can be realized, and the performance of the wet aftertreatment device can be greatly improved.

It is the schematic which shows the whole structure of the gas-liquid contact apparatus in 1st Embodiment of this invention. 1 is an overall schematic cross-sectional view of an engine wet aftertreatment device in a first embodiment. It is a longitudinal cross-sectional view with the top view which shows the porous body structure in the gas-liquid contact apparatus of 1st Embodiment, and its AA sectional view. It is a principal part expanded sectional view of the porous body used for 1st Embodiment. It is a system configuration figure of the whole engine to which the engine wet aftertreatment device of the present invention is applied. It is the top view which shows the whole sectional view and nozzle plate structure of the liquid injector used for the gas-liquid contact apparatus of 1st Embodiment. It is a figure for demonstrating the relationship between the injection hole of the liquid injector which comprises the distribution mechanism of 1st Embodiment, and the area | region of a porous body end surface. It is the principal part schematic sectional drawing and top view of the gas-liquid contact apparatus in 2nd Embodiment. It is the principal part schematic sectional drawing and top view of a cell group unit which comprise the gas-liquid contact apparatus of 2nd Embodiment. It is the principal part schematic sectional drawing and top view of a cell group unit which comprise the gas-liquid contact apparatus of 3rd Embodiment. It is a principal part schematic diagram of the gas-liquid contact apparatus in 4th Embodiment. It is a flowchart figure of the operation control of the liquid injector implemented with an electronic control unit. It is a figure which shows the relationship between engine operating conditions and exhaust pulsation. It is a figure which shows the time transition of exhaust pulsation in a predetermined driving | running condition. It is a whole perspective view which shows the other example of a porous body shape.

  Hereinafter, a first embodiment in which the present invention is used for post-processing of a vehicle engine will be described based on the drawings. FIG. 1 shows a gas-liquid contact device 1 to which the present invention is applied. The gas-liquid contact device 1 is installed in an exhaust passage of an engine E shown in FIG. 5 and uses a specific gas component in combustion exhaust (hereinafter referred to as exhaust) as a liquid. This constitutes the main part of an aftertreatment device (hereinafter referred to as a wet aftertreatment device) 100 for removal. The engine E is a turbocharged diesel engine, and a DPF (diesel particulate filter) 101 and an exhaust heat recovery device 102 are arranged in the middle of an exhaust pipe EX serving as an exhaust passage. A wet aftertreatment device 100 is arranged. The wet aftertreatment device 100 of the present embodiment shown in FIG. 2 absorbs and removes a specific gas component in exhaust gas, particularly a nitrogen oxide (NOx) component, using a NOx absorbing liquid as a liquid.

  The engine E includes a supercharger that includes a compressor 103 and an exhaust turbine 104. The air taken in from the intake pipe inlet IN1 is pressurized by the compressor 103, and the air that has become hot due to the pressurization is cooled by the intercooler 106 installed in the intake pipe IN, and then is sent from each port of the intake manifold 107 to the engine. Inhaled into E's combustion chamber. In the combustion chamber of the engine E, air and fuel are mixed and burned to generate power as a rotational force of the engine output shaft 108.

  The exhaust after the combustion is exhausted from the combustion chamber of the engine E to the exhaust manifold 105. After that, the exhaust gas is discharged to the exhaust pipe EX after rotating the exhaust turbine 104 directly connected to the compressor 103 and performing the work of pressurizing the air. The exhaust gas passes through the DPF 101 here, and particulate matter (PM) in the exhaust gas is collected by filtration with the DPF 101. At the same time, the HC component and the CO component are also purified by the oxidation catalyst coated on the surface of the DPF 101 through which the exhaust passes. Thereafter, the exhaust gas passes through the exhaust heat recovery device 102, is cooled, and the exhaust gas temperature usually falls between 100 ° C and 180 ° C.

  The DPF 101 used here is a known wall flow type exhaust filter in which a porous wall formed of ceramic works as a filter. The exhaust heat recovery device 102 is a known Rankine cycle exhaust heat recovery system. For example, the heat energy obtained by cooling the exhaust gas evaporates the refrigerant to become a high-pressure gas, and is directly connected to the gas turbine. It is like being converted into electrical energy by a generator and stored in a battery.

The cooled exhaust gas is introduced into the wet aftertreatment device 100. Here, the NOx component contained in the exhaust is absorbed in contact with the NOx absorbing liquid in the wet aftertreatment device 100. Up to this point, PM, HC, CO, and NOx are removed, and the exhaust becomes clean and exhausted from the exhaust pipe outlet EX1 into the atmosphere. An ozone supply means (not shown) is installed upstream of the wet aftertreatment device 100 to react NOx contained in the exhaust gas with the supplied ozone, thereby converting it into nitric acid (HNO ₃ ) or its precursor (N ₂ O ₅ ). It can also be converted. In the present invention, nitrogen oxides (NO, NO ₂ ) and compounds generated from these (HNO ₃ , N ₂ O ₅ ) are collectively referred to as NOx components.

  In the intake system, an air flow rate sensor S1 is disposed immediately downstream of the intake pipe inlet IN1. In addition, a throttle opening sensor S2 for detecting the throttle opening of the intake throttle 110 is disposed, and an intake pressure sensor S3 is disposed at the junction of the intake manifold 107. In the vicinity of the output shaft 108 of the engine 1, a rotational speed sensor S4 that measures the engine rotational speed is arranged, and in the exhaust system, an exhaust temperature sensor S5 that measures the exhaust temperature is arranged downstream of the DPF 101. Further, a sensor accelerator opening sensor S6 for detecting the opening degree of an accelerator pedal (not shown) is provided, and each of these sensors converts the measured information into an electric signal, and is an electronic control means through a connected electric wire. This is sent to the control unit (ECU) 111.

  Next, a specific configuration example of the wet post-processing apparatus 100 will be described. In FIG. 2, the wet aftertreatment device 100 includes a gas-liquid contact device 1 interposed in the middle of the exhaust pipe EX, and a liquid supply device 4 that supplies NOx absorbing liquid to the gas-liquid contact device 1. The gas-liquid contact device 1 has a porous body 2 having a gas-liquid contact passage 22 inside, and a liquid injector 3 that is a liquid injection valve and an exhaust inlet 11 are provided on one end side (the upper end side in the figure). The exhaust introduction part 13 which is a gas introduction part is located. The exhaust introduced from the exhaust inlet 11 connected to the exhaust pipe EX flows in the same direction as the NOx absorbing liquid injected and supplied from the liquid injector 3 and comes into contact with the inside of the porous body 2. The liquid supply device 4 has a gas-liquid separation device 41 installed on the lower end side of the porous body 2, and connects the gas-liquid separation device 41 and the liquid injector 3 with a liquid pipe 42 to form a circulation path for NOx absorbing liquid. doing. In the gas-liquid separator 41, the NOx absorption liquid separated and recovered from the exhaust gas passes through the filter F provided in the liquid pipe 42, is sucked up by the pump P, and is supplied to the liquid injector 3 again. On the other hand, the exhaust gas separated from the NOx absorbing liquid passes through the gas-liquid separator 41 and is returned from the exhaust outlet 12 to the exhaust pipe EX.

  A gas-liquid contact device 1 shown in detail in FIG. 1 has a liquid injector 3 attached to the upper end of a cylindrical housing H whose axial direction is the vertical direction, and a porous body 2 is accommodated below the liquid injector 3. A space serving as an exhaust introduction portion 13 is formed between the liquid injector 3 and the porous body 2, and an exhaust inlet 11 is connected to the upper end portion from the side. At this time, since the exhaust gas is introduced above the injection hole 32 of the liquid injector 3, there is little possibility of disturbing the flow of the ejected droplet L. The porous body 2 is a honeycomb structure composed of a large number of cells extending in the axial direction, and each cell constituted by stacking a large number of gas-liquid contact plates 21 serves as a gas-liquid contact passage 22. A space below the porous body 2 serves as a gas-liquid collecting portion 14 and is connected to the gas-liquid separation device 41 of FIG.

  As shown in FIG. 3, the gas-liquid contact plate 21 of this embodiment is a combination of two types of plate materials, a corrugated plate-like gas-liquid contact plate 21a and a flat plate-like gas-liquid contact plate 21b. The porous body 2 having a large number of partitioned cells is formed by alternately stacking in the direction and accommodating in the cylindrical body 23. The cylindrical body 23 has a rectangular cylindrical shape with rounded corners, and the porous body 2 has a rectangular parallelepiped shape as a whole having a substantially square cross section. The gas-liquid contact plates 21 a and 21 b and the cylinder body 23 are usually metal plates such as stainless steel having corrosion resistance, and a large number of cells having a substantially triangular cross section surrounded by the adjacent gas-liquid contact plates 21 a and 21 b and the cylinder body 23. Forms a number of parallel gas-liquid contact passages 22. Both surfaces of the gas-liquid contact plates 21a and 21b facing the gas-liquid contact passage 22 and the inner surface of the cylinder 23 function as a gas-liquid contact surface, while the NOx absorbing liquid flows down along the gas-liquid contact surface. In contact with the exhaust gas flowing into the gas-liquid contact passage 22, the NOx component contained in the exhaust gas is absorbed.

The NOx absorbing liquid is not particularly limited as long as it is capable of absorbing the NOx component, has a higher viscosity than water, and maintains a liquid state in the use environment. Specifically, the liquid may have a viscosity of 0.01 Pa · s or higher at room temperature (25 ° C.), and preferably an ionic liquid that chemically absorbs NOx components such as NOx or HNO ₃ , for example, a carboxylate. An ionic liquid containing is used. Preferable examples of the carboxylate anion include an alkylcarboxylate ion represented by C _n H _{2n + 1} COO ⁻ (n is an integer of 0 to 10) and derivatives thereof, and a combination of at least one or two or more thereof. To an absorbent liquid having a desired absorption performance and viscosity.

  Since such an ionic liquid does not evaporate even in a high temperature environment, it does not atomize and float in the exhaust introduction part 13 and is relatively high in viscosity. Therefore, exhaust is introduced at an injection angle corresponding to the shape of the injection hole 32. It spreads in the part 13 and adheres to the upper end surface of the porous body 2. Then, while slowly flowing down the wall surface of the gas-liquid contact passage 22, the NOx component in the exhaust gas is contacted and chemically absorbed to maintain the state stably. For this reason, for example, it is not necessary to provide a cooling device or the like for cooling the liquid, separation and recovery are easy, and the entire device can be made compact.

  However, the ionic liquid having a large viscosity reaches the porous body 2 while maintaining the spray angle substantially without the droplets L sprayed from the one nozzle hole 32 being atomized. For this reason, it is difficult to supply the porous body 2 so as to spread over the entire upper end surface, and a distribution mechanism that spreads the droplets L attached to the porous body 2 over the entire surface of the gas-liquid contact passage 22 is required. . Therefore, in the present invention, the NOx absorbing liquid is evenly attached to the upstream end portion of the porous body 2 and the attached liquid droplet L is configured to be able to flow between the gas-liquid contact passages 22, so that the NOx absorbing liquid is formed. A distribution mechanism for distributing the liquid to the entire porous body 2 is provided. Specifically, the distribution mechanism of the NOx absorbing liquid is a combination of appropriate generation of the droplets L by the liquid injector 3 and uniform distribution of the droplets L by the geometric structure of the porous body 2. By optimizing, the gas-liquid contact ability can be greatly improved.

  Of these, the structure of the porous body 2 will be described first. In FIG. 1, the gas-liquid contact plate 21 to be the porous body 2 is provided with a large number of through holes 24 penetrating the plate surface in a part on the upstream side facing the exhaust introduction portion 13. The both surfaces, which constitute the gas-liquid contact surface, that constitute the distribution mechanism through these through holes 24 communicate with each other, so that the NOx absorbing liquid can flow through the adjacent gas-liquid contact passages 22. As shown in FIG. 3, the through holes 24 are, for example, circular holes having a size corresponding to the pitch of the corrugated gas-liquid contact plate 21a, and are provided at equal intervals in a predetermined region in the longitudinal direction. In FIG. 3, the through-hole 24 provided in the corrugated gas-liquid contact plate 21a is shown. However, by providing the through-hole 24 also in the flat gas-liquid contact plate 21b, the flow of the NOx absorbing liquid is promoted.

  FIG. 4 shows an enlarged cell of the porous body 2, and the flat gas-liquid contact plate 21 b penetrates the plate surface at a position where the crest or valley of the corrugated gas-liquid contact plate 21 a abuts. A number of through holes 24 are provided. At this time, the droplet L moves along the surfaces of the gas-liquid contact plates 21a and 21b as indicated by arrows in the figure, and moves to the opposite surface at the position of the through hole 24. As described above, the movement of the liquid droplets L through the large number of through holes 24 spreads so as to wet the entire wall surfaces of the gas-liquid contact plates 21a and 21b and is evenly distributed.

  Although the formation region of the through hole 24 can be set as appropriate, it is usually preferable to set it to 1/8 or more of the longitudinal length from the upstream side of the porous body 2. Preferably, by setting the region to ½ of the length in the longitudinal direction, for example, about １ ／ of the length in the longitudinal direction, a sufficient effect can be obtained by distributing and supplying the droplets L while reducing the labor of manufacturing. Thereby, on the upstream side of the gas-liquid contact plate 21, the NOx absorbing liquid can be distributed between the adjacent gas-liquid contacting passages 22, and the NOx absorbing liquid can be spread over the entire porous body 2.

  In FIG. 6, the liquid injector 3 has a cylindrical injector body 31 as a liquid passage 34, and a nozzle plate 33 provided with a plurality of injection holes 32 is fixed to the tip (lower end in the figure) of the injector body 31. . A needle 35 is slidably accommodated in the lower half of the injector body 3, and the tip tapered surface is seated on or separated from a tapered sheet 31 a provided on the tip-side inner wall of the injector body 3, and liquid The passage 34 is opened and closed. The needle 35 is driven upwardly by energizing an electric terminal 36a of an electromagnetic solenoid 36 disposed on the outer periphery of the core 35a with the proximal end portion as a core 35a. When not energized, the spring 38 supported by the adjusting pipe 37 above the needle 35 urges the needle 35 downward and presses it against the seat 31a. Thus, the liquid injector 3 is configured to electromagnetically open and close the seat mechanism composed of the needle 35 and the seat 31a.

  The outer periphery of the needle 35 is a sliding portion 35b that slides on the injector body 31, and a part of the outer periphery of the sliding portion 35b is a chamfered portion 35c so that the upper and lower liquid passages 34 communicate with each other. . Further, a passage that passes through the core 35a of the needle 35 and communicates with the upper and lower spaces thereof is provided to facilitate the movement of fuel when the needle 35 is operated. On the outer periphery of the upper end portion of the injector body 31, an O-ring 31b is fitted to seal a wall surface of the gas-liquid contact device 1 to which the liquid injector 3 is attached. Energization to the electrical terminal 36a is controlled by an electronic control unit (ECU) 111 in FIG. 5, and at least one droplet L is generated for each nozzle hole 32 by a single opening / closing operation of the sheet 31a. It is distributed and supplied to each part of the porous body 2.

  The nozzle plate 33 has a disc-shaped tip surface corresponding to the shape of the injector body 31, and a large number of injection holes 32 are formed through the central portion of the nozzle plate 33 facing the needle 35. A large number of nozzle holes 32 constituting the NOx-absorbing liquid distribution mechanism are arranged in a rectangular shape corresponding to the shape of the upper end portion of the porous body 2, and here, a square shape in which four nozzle holes 32 are aligned at equal intervals on one side. It has become. Each nozzle hole 32 is a circular hole having the same diameter, and the number, position, and angle of the nozzle holes are adjusted so that the ejected droplets L are evenly distributed to the upper end surface of the porous body 2.

  In the present embodiment, as shown in FIG. 7, the upper end surface of the porous body 2 is regarded as a square, and 16 regions of approximately equal area corresponding to the number of nozzle holes 32 (16 in this case) (dotted lines in the figure). The injection angle, that is, the injection hole angle (inclination of the injection hole with respect to the axis) so that the droplet L supplied from the corresponding injection hole 32 reaches the center of each region including a plurality of cell groups. Angle). Since the NOx absorbing liquid having a relatively high viscosity is scattered as droplets L in the direction of the nozzle hole angle along the nozzle hole 32 shape, the nozzle hole 32 is designed from the geometric dimensions of the gas-liquid contact device 1. can do.

  More specifically, the rectangular upper end surface of the porous body 2 is larger than the size of the rectangular nozzle holes 32 formed in the nozzle plate 33, and the corresponding region is located on the outer side. 32 has an injection hole angle inclined outward with respect to the axis. Further, as shown in a cross-sectional shape in FIG. 6, the nozzle hole angles of the 12 nozzle holes 32 on the outer peripheral side are set larger than the four nozzle holes 32 on the inner peripheral side close to the center. Further, when the droplet L does not reach the predetermined position due to the influence of the exhaust flow or the like, it is possible to experimentally adjust the deviation of the nozzle hole angle by performing the injection with the used injection pressure.

  In the NOx absorbing liquid distribution mechanism, which is a feature of the present invention, the nozzle holes 32 of the liquid injector 3 that generates the droplets L are appropriately disposed in this manner, and the droplets are disposed on the entire upper end surface of the porous body 2. L is adhered uniformly, and the adhered droplets L are distributed to the whole using the through holes 24 provided on the upstream side of the porous body 2. By combining these, the gas-liquid contact efficiency can be increased and the processing performance can be improved.

  The size of the gas-liquid contact device 1 can normally be arbitrarily set according to the engine displacement. For example, the volume of the porous body 2 is set to about 0.5 to 3 times the displacement, and the number of meshes is set to 6 meshes or more, so that the gas-liquid contact passage 22 formed in a plurality of cells in each region. In this case, sufficient gas-liquid contact is possible. As the number of meshes is increased, the effective gas-liquid contact area increases. However, it takes time to manufacture and the pressure loss also increases. Therefore, it is preferable to design appropriately within a range where desired processing capability can be obtained.

About the structure of 1st Embodiment, the gas-liquid contact apparatus 1 containing the porous body 2 and the liquid injector 3 was actually manufactured and evaluated. The porous body 2 used in the experiment had a mesh 12.7 (pitch 2 mm), a through hole 24 diameter φ1 mm, a pitch 2 mm, and a through hole 24 formation length 36 mm with respect to a total length 110 mm. A test gas was introduced and injection was performed from the liquid injector 3 under the conditions of a space velocity SV60000 (h ⁻¹ ) and a gas-liquid weight ratio of 7.8, using an experimental apparatus that was not yet wet with liquid. After continuing the operation for about 7 minutes, the apparatus was disassembled and the wall surface at the outlet of the porous body 2 was observed. As a result, all the wall surfaces were wetted with liquid, and the liquid was removed from the entire porous body in a relatively short time. Confirmed to go around.

  FIG. 8 shows a second embodiment of the present invention, which is a configuration example in which the direction of exhaust introduction into the porous body 2 of the gas-liquid contact device 1 and the arrangement of the liquid injector 3 are changed. As shown in the drawing, the gas-liquid contact device 1 has a part of the exhaust pipe EX as a housing H, and a porous body 2 is disposed in the interior with the horizontal direction as the axial direction. As in the first embodiment, the porous body 2 of the present embodiment is composed of a rectangular parallelepiped honeycomb structure in which a large number of cells have gas-liquid contact passages 22 (not shown), and the upstream end thereof is stepped. It is different in the point that it is attached. Here, the porous body 2 is divided into four regions each in the vertical direction and the horizontal direction, and each region in the vertical direction is composed of different cell group units U1 to U4. The cell group units U1 to U4 constituting the horizontal region are common to each stage.

  Each of the four cell group units U1 to U4 in the vertical direction has a two-stage configuration, and the cell group constituting the lower stage portion projects from the cell group constituting the upper stage portion so as to protrude upstream, and the lower stage portion that projects The upper surface is an adhesion surface (attachment part) 25 of the droplet L. The lower part of the cell group units U1 to U3 is stacked on the upper part of the lower cell group units U2 to U4. Thereby, the adhesion surfaces 25 of the cell group units U1 to U4 are arranged upward in a square shape, and a total of 16 regions are formed in each of four in the width direction and the axial direction of the housing H.

  On the other hand, the liquid injector 3 has the same shape as the first embodiment, and has 16 injection holes 32 corresponding to the attachment surfaces 25 of the housing H. The housing H has a part of the upper wall surface protruding upward on the upstream side of the cell group units U1 to U4 to form a space serving as the gas introduction part 13 inside, and the liquid injector 3 is attached to the protruding wall surface. Yes. The liquid injector 3 is disposed so as to be inclined toward the downstream side of the exhaust flow, and the nozzle hole 32 at the tip is located immediately above the most upstream part of the cell group units U1 to U4.

  Also in this embodiment, the 16 nozzle holes 32 are respectively set to correspond to the 16 attachment surfaces 25 of the cell group units U1 to U4 to set the nozzle hole angles. Thereby, the droplet L ejected from each injection hole 32 can be attached to the central portion of each attachment surface 25. Further, inside each cell group unit U1 to U4, as shown in FIG. 9 (only cell group unit U1 is shown), a plurality of gas-liquid contact passages 22 that are partitioned by gas-liquid contact plates 21 in the horizontal direction are formed. Each gas-liquid contact passage 22 is provided with a plurality of through holes 24 in the gas-liquid contact plate 21 so as to constitute the bottom surface on the upstream side. The plurality of through holes 24 communicate the upper and lower stages of the cell group units U1 to U4, and drop the liquid droplet L flowing from the upper stage side of the gas-liquid contact passage 22 along the exhaust flow by gravity. Thus, a distribution mechanism that distributes to the lower stage side is configured.

  In addition, the adhering surface 25 of each of the cell group units U1 to U4 is recessed at a portion facing the inlet portions of the plurality of gas-liquid contact passages 22 on the upper stage side to constitute a NOx absorbing liquid distribution mechanism. (Distributing unit) 26 is provided. The recess 26 is close to the central portion where the droplet L adheres, and is a shallow recess having the same capacity as the droplet L. When the droplet L adheres, the recess 26 quickly spreads in the width direction due to surface tension, and a plurality of gas-liquid contact paths 22 is introduced. By providing the recess 26 in this way, the NOx absorbing liquid can be evenly distributed to the corresponding gas-liquid contact passages 22 even if the position where the droplet L adheres is shifted due to the influence of the exhaust flow or the like. .

  By configuring like this embodiment, since the apparatus height of the gas-liquid separation apparatus 1 can be made low, it is advantageous when the space in the height direction is restricted. Therefore, for example, for a vehicle-mounted engine, it can be suitably used by being attached to an exhaust pipe EX that runs horizontally under the vehicle floor.

  FIG. 10 shows a third embodiment of the present invention, and the basic configuration of the distribution mechanism is the same as that of the second embodiment. In the present embodiment, a plurality of through holes 24 are also provided in the gas-liquid contact plate 21 that divides the adjacent gas-liquid contact passages 22 on the upstream side of each cell group unit U1 (the same applies to U2 to U4). As a result, the droplets L that spread from the adhesion surface 25 to the recessed portion 26 and are distributed to each gas-liquid contact passage 22 further spread over the entire surface so as to wet the wall surface through the through holes 24 that open to the bottom surface and the side surface. Therefore, the liquid droplets L can be further effectively distributed. In these second and third embodiments, the region where the through hole 24 is formed may be set similarly to the first embodiment.

  FIG. 11 shows a fourth embodiment of the present invention, which is a configuration example in which a plurality of liquid injectors 3 are arranged. The basic structure of the distribution mechanism is the same as that of the second embodiment. The combination of the cell group units U1 to U4 and the liquid injector 3 shown in FIG. Are arranged side by side in a direction perpendicular to the flow of the gas. When the gas-liquid contact device 1 is enlarged in order to increase the NOx processing capacity, it is possible to increase the number of corresponding holes by increasing the number of nozzle holes, but the liquid injector 3 is enlarged and the nozzle hole design is increased. Is not easy. Therefore, in this embodiment, by combining the basic unit U, the processing capacity is doubled without changing the design of the liquid injector 3 and the cell group units U1 to U4. Further, since the number of basic units U can be increased according to the required processing capacity, the droplets L can be effectively distributed, and NOx absorption can be efficiently performed in the entire apparatus.

  FIG. 12 is a flowchart showing a method for controlling the operation of the liquid injector 3 in accordance with engine operating conditions in order to effectively demonstrate the processing capability of the gas-liquid contact device 1 in each embodiment of the present invention. This is executed in an electronic control unit (ECU) 111. The exhaust has pulsations that are synchronized with the number of engine combustions, and when the exhaust flow rate increases, the droplets L are caused to flow by the wind, and the discrete uniformity of the droplets L flying from the liquid injector 3 to the porous body 2 is increased. There is a risk of damage. Therefore, preferably, the liquid injection flow rate (liquid supply flow rate) is controlled according to the amount of NOx in the exhaust gas, and further, under the operating conditions in which the effects of the exhaust gas flow velocity and pulsation are predicted, these effects are minimized. It is desirable to determine the operation timing of the liquid injector 3.

  In step 1 of FIG. 12, it is determined whether or not the wet post-processing apparatus 100 is operating. For example, NOx processing is not performed under operating conditions where the amount of NOx generated is small at the start of the engine or immediately after the start. Further, when any abnormality is detected in the wet aftertreatment device 100 by the failure determination device attached to the engine E, it is determined as the non-operating condition. As described above, when a negative determination is made in step 1, the present process is terminated without operating the liquid injector 3 of the gas-liquid contact device 1. If an affirmative determination is made in step 1, the process proceeds to the subsequent step 2.

  In step 2, the liquid injection flow rate GL required for the NOx process is calculated from the operating state of the engine E. Specifically, based on the engine speed and the injection amount, the NOx concentration discharged from the engine E is obtained from a pre-programmed map. Then, the NOx flow rate is calculated based on the intake flow rate and the exhaust temperature measured by the air flow rate sensor S1 and the temperature sensor S5. Based on this, the flow rate of the NOx absorption liquid can be calculated, and the liquid injection flow rate GL of the NOx absorption liquid supplied from the liquid injector 3 can be determined.

  In the subsequent step 3, it is determined whether or not the engine E is in a low speed and low load operation condition. FIG. 13 shows the magnitude of exhaust pulsation for each operating region of the engine E. In the low-speed and low-load region, the exhaust pulsation is sufficiently small and the exhaust flow velocity is small, so that the gas-liquid contact device 1 can be operated without taking these effects into consideration. However, when the low-speed and low-load region is exceeded, the exhaust flow velocity increases and the exhaust pulsation tends to increase, so that the flow velocity further increases and the influence cannot be ignored. Therefore, when the region other than the low speed and low load region is negative, that is, when the negative determination is made in Step 3, the process proceeds to Step 4 and the subsequent steps, and optimal injection is performed in synchronization with the rotation of the engine E. If an affirmative determination is made in step 3, the process proceeds to step 9.

In the subsequent step 4, the number of injections N per unit time is calculated by the following equation (1) using the single injection amount qi by the liquid injector 3 and the liquid injection flow rate GL calculated in step 2.
N = GL / qi (1)
Next, at step 5, the current engine speed Ne measured by the engine speed sensor S4 is read. Using this to calculate the injection frequency per 100 revolutions, calculating the N ₁₀₀ is further integer.

  Next, it progresses to step 6 and it is determined whether it is an engine rapid acceleration driving condition. During transient operation such as during rapid acceleration, the exhaust flow velocity increases, and therefore the supply of NOx absorbing liquid may not be able to catch up due to a response delay of the gas-liquid contact device 1. In order to avoid this, only when step 6 is negatively determined, the routine proceeds to step 7 where the injection based on step 5 is performed. If step 6 is affirmed, the process proceeds to step 8.

Step 7 is a process that is executed in an operating condition other than the low-speed and low-load region and excluding the time of rapid engine acceleration. In this region, in order to minimize the influence of the exhaust pulsation, the injection by the liquid injector 3 is performed at the timing at which the exhaust flow velocity becomes the smallest in synchronization with the engine rotation. FIG. 14 is an example of exhaust pulsation measurement data (engine speed 1800 rpm, engine torque 60 Nm), and the exhaust pressure change amount (ΔP) fluctuates with time, and has a constant cycle with engine rotation. I understand. Therefore, the bottom portion of the pulsation and the engine rotational position at which the exhaust flow velocity is the smallest are set as the reference rotational position, and the number of injections N ₁₀₀ (per 100 revolutions) calculated in step 5 is injected every rotation.

  Step 8 is a process executed under the engine rapid acceleration operation condition. In this region, in order to compensate for the processing capacity decrease due to the response delay, the injection is performed every time the engine rotates regardless of the calculated value of Step 5. carry out. As described above, when engine acceleration is detected, the liquid supply amount is temporarily increased. Therefore, even if the exhaust gas flow rate increases, sufficient NOx absorbing liquid can be supplied to the gas-liquid contact device 1.

Step 9 is a process executed under low-speed and low-load operation conditions. In this region, the exhaust flow velocity and the exhaust pulsation are sufficiently small, and it is not necessary to synchronize with the engine rotation. Specifically, the injection frequency (injection frequency) F per unit time is calculated by the following equation (2) using the single injection amount qi and the liquid injection flow rate GL calculated in step 2.
F = GL / qi (2)
Next, in step 10, the liquid injector 3 is operated with the calculated injection frequency F.

  In the above-described embodiment, a honeycomb structure in which corrugated plates and flat plates are combined is used as the porous body 2 constituting the gas-liquid contact device 1, but any structure that can form a large number of gas-liquid contact passages 22 therein can be used. Good. The shape of the porous body 2 composed of the laminated body of the gas-liquid contact plate 21 is not particularly limited, but it is easy to manufacture a laminated body using the corrugated and flat gas-liquid contact plate 21 by making it a rectangular parallelepiped shape. The volume of the NO absorption part 2 can be made relatively large with respect to the installation space. Furthermore, it can also be a circular, elliptical or other cross-sectional shape, and can be arbitrarily selected according to the installation space or the like.

  FIG. 15 shows an example in which the porous body 2 has a circular cross-sectional shape in which gas-liquid contact plates 21 are laminated. In this case, too, a combination of corrugated gas-liquid contact plates 21a and flat gas-liquid contact plates 21b is combined. A similar effect can be obtained by forming the gas-liquid contact passage 22 in the cell and arranging the injection holes 32 of the liquid injector 3 so as to correspond to the plurality of regions set on the end face of the porous body 2. Further, the configuration of each part of the liquid injector 3, the liquid supply device 4, and the other components of the wet post-treatment device 100 is not particularly limited, and can be changed as appropriate.

  The engine wet aftertreatment device using the gas-liquid contact device of the present invention is applicable to even an engine having a small size and low cost, and a large change in environmental temperature and operating state. For this reason, although it is suitable for a vehicular engine having a severe use environment and a large space restriction, it is applicable not only to a vehicular or a diesel engine but also to any engine. Further, the specific component in the exhaust gas is not limited to the NOx component, and a similar high processing performance is realized by combining a specific gas component and an absorbing liquid.

E Engine EX Exhaust pipe (exhaust passage)
100 Wet after-treatment device 111 Electronic control unit (control means)
1 Gas-liquid contact device 13 Exhaust introduction part (gas introduction part)
2 Porous body 21 Gas-liquid contact plate 22 Gas-liquid contact passage 23 Cylindrical body 24 Through-hole (distribution mechanism)
25 Adhering surface (adhering part)
26 Recessed part (distribution part)
3 Liquid injector (liquid injection valve)
31a Sheet (sheet mechanism)
35 Needle (seat mechanism)
32 injection hole (distribution mechanism)
4 Liquid supply device

Claims (8)

An engine which is disposed in the middle of the exhaust passage (EX) of the engine (E) and processes a specific gas component contained in the engine combustion exhaust gas using a liquid which can absorb the specific gas component and has a higher viscosity than water. In the wet after-treatment device (100), a gas-liquid contact device (1) comprising a gas-liquid contact passage (22) for bringing the engine combustion exhaust into contact with the liquid,
The gas-liquid contact device includes a porous body (2) having a plurality of partitioned cells as the gas-liquid contact passage, a gas introduction part (13) provided on one end side of the porous body, and the porous body At least one liquid injection valve (3) provided on one end side of the liquid, and a distribution mechanism for distributing the liquid injected from the liquid injection valve to the gas-liquid contact passage on one end side of the porous body,
In the distribution mechanism, a plurality of nozzle holes (32) provided in the liquid injection valve are arranged in correspondence with a plurality of areas set in advance on one end side of the porous body, and the liquid ejected toward each area Are distributed to the adjacent gas-liquid contact passages through a plurality of through holes (24) provided in the passage walls of the gas-liquid contact passages ,
Furthermore, according to the engine operating conditions, provided with a control means (111) for controlling the liquid supply flow rate to the porous body,
The control means controls the liquid supply flow rate at the opening / closing frequency per unit time of the liquid injection valve during low speed and low load operation of the engine, and synchronizes with the engine rotation except during the low speed and low load operation. A gas-liquid contact device for an engine wet after-treatment device, characterized by controlling .   The liquid injection valve includes a seat mechanism (35, 31a) that is electromagnetically opened and closed upstream of the plurality of nozzle holes arranged on a front end surface. The gas-liquid contact device for an engine wet aftertreatment device according to claim 1, wherein at least one droplet is generated and distributed to the plurality of regions.   The engine wet according to claim 1 or 2, wherein the porous body has a rectangular or circular end surface shape, and the plurality of injection holes of the liquid injection valve are arranged in a shape corresponding to the end surface shape of the porous body. Gas-liquid contact device for post-processing equipment.   The distribution mechanism receives and attaches the liquid ejected to each region on one end side of the porous body, and distributes the adhered liquid to the gas-liquid contact passage corresponding to each region. The gas-liquid contact device for an engine wet aftertreatment device according to any one of claims 1 to 3, further comprising a section (26). The control means controls the liquid injection to be performed at a timing at which the exhaust gas flow velocity becomes smaller in synchronization with the engine rotation during operation other than during low speed and low load operation and during operation other than transient operation. The gas-liquid contact apparatus for engine wet aftertreatment apparatuses of any one of thru | or 4. The control means, at the time of transient operation in synchronism with the engine Rotation, engine wet post-processing apparatus according to any one of claims 1 to 5 for controlling so that the liquid supply flow rate increases temporarily Gas-liquid contact device.   7. The engine wet aftertreatment device according to claim 1, wherein the liquid is an ionic liquid having a viscosity at 25 ° C. of 0.01 Pa · s or more and maintaining a liquid state in a use environment. Gas-liquid contact device.   The gas-liquid contact device for an engine wet aftertreatment device according to any one of claims 1 to 7, wherein the specific gas component is a nitrogen oxide component.

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