JP3940204B2 - Particulate removal device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a particulate removing device for removing particulates in exhaust gas such as diesel engine exhaust gas.
[0002]
[Prior art]
In order to remove fine particles contained in the exhaust gas of a diesel engine, a means using a filter trap or an oxidation catalyst has been conventionally employed.
[0003]
The filter trap is made of ceramic or the like and is arranged in the middle of the exhaust gas pipe to capture the fine particles, but the fine particles are likely to be clogged. For this reason, the filter trap is burned with an electric heater or the like to remove fine particles and reused. However, the filter trap often breaks during this combustion, and the durability is poor.
[0004]
In addition, when an oxidation catalyst is used, the trapping effect is low, and it is deteriorated by sulfate (CaSO ₄ ) generated as a by-product, resulting in a short life.
[0005]
[Problems to be solved by the invention]
In view of the above facts, an object of the present invention is to obtain a particulate removal device that has a high effect of trapping particulates in exhaust gas and has a long lifetime.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, a nozzle that opens into the exhaust gas passage, a liquid feeding means that ejects fine liquid from the nozzle and takes in the fine particles in the exhaust gas into the liquid, and the exhaust gas passage. A collection unit that opens, collects the ejected liquid and circulates it to the liquid feeding means, and removes the liquid stored in the collection unit, removes the fine particles from the liquid, and then returns to the collection unit again. In the fine particle removal apparatus having a passage and a drive means for driving the fine particle removal circulation path at a predetermined time and sending liquid to the circulation path, the liquid feeding means is directed from the nozzle toward the liquid surface of the recovery unit. The fine liquid is ejected, and the exhaust gas containing the liquid after the fine particles are taken in is made to collide with the liquid surface of the recovery unit .
[0007]
In the invention according to claim 1, liquid is supplied to the nozzle opened in the exhaust gas toward the liquid level of the recovery unit by the liquid feeding means, and the liquid becomes fine particles from the nozzle into the exhaust gas passage. And sprayed. Therefore, the sprayed liquid takes in and captures a large number of fine particles contained in the exhaust gas. The liquid particles in which the fine particles have been captured collide with the liquid surface of the collection unit , and are collected, sent to the liquid feeding means, and circulated again to the nozzle, so that a large collection efficiency can be obtained with a small amount of liquid. Since the particulate removal circuit is not operated only at a predetermined time, that is, not always, but is operated only when necessary, the circuit drive means such as a pump can be used efficiently.
[0008]
When the fine particles are suspended in the exhaust gas, the diameter is 0.1 to 0.5 μm, and the filter for capturing fine particles of this size is difficult to reuse as described above. However, it is found that the fine particles in the exhaust gas are bonded to each other and grow to a size of 1 μm when entering the liquid, and can be easily captured by a filter such as a fiber bundle that is generally sold.
[0009]
If liquid is stored in the recovery unit and exhaust gas is sent in contact with the liquid level of the stored liquid, the liquid that is in a fine particle state after being ejected is absorbed by the recovery unit by the surface tension. Most of it can be recovered.
[0010]
By increasing the liquid supply amount from the liquid supply means in accordance with an increase in engine load, it is possible to effectively capture fine particles in the exhaust gas whose exhaust amount increases as the engine load increases. In this case, the discharge amount of the fine particles is increased with the increase of the engine speed, so that the liquid supply amount may be gradually increased in this case as well. Further, particulates in the exhaust gas due to an increase in engine load or an increase in the rotational speed gradually decrease until the engine load reaches a predetermined value or the engine speed decreases to a predetermined value, and then increases as the engine load increases or the rotational speed increases. Since the discharge amount increases, the liquid supply amount may be reduced and increased accordingly.
[0011]
In general, exhaust gas contains SO _x and NO _x , which dissolve in water to form an acidic solution. Therefore, the recovered liquid can be prevented from being oxidized by using a weak alkaline aqueous solution as the liquid to be ejected. Since this acidity is about pH 3, it may be dealt with by using an acid resistant material such as stainless steel. Further, if a heating means is provided in the exhaust gas, it is possible to prevent the water vapor contained in the exhaust gas after the treatment that has been cleaned through this apparatus as a scrubber from condensing and producing white smoke. The heating means preferably uses engine exhaust gas heat.
[0012]
The invention according to claim 2 is characterized in that the driving means drives the circulation path in a state where the amount of fine particles in the liquid exceeds 350 mg / l, that is, 350 mg per liter. As a result of the experiment, it was found that when the amount of fine particles in the liquid exceeded 350 mg per liter, the fine particle capturing effect decreased, and when it exceeded 350 mg / l, the fine particle capturing effect rapidly decreased. For this reason, it is not necessary to always drive the driving means by driving the circulation path in a state where the amount of fine particles in the liquid exceeds 350 mg.
[0013]
According to a third aspect of the present invention, the driving means drives the circulation path every predetermined time. Therefore, control over the relationship between the driving time of the liquid amount and the engine to be used and the like, advance checks whether trapping effect of the fine particles is reduced in advance how much operating time, every time it is predicted that particulate trapping effect fades By driving the driving means by the means, it is not necessary to always drive the driving means, and fine particles can be captured effectively. In addition, it is possible to drive the drive means by the control means using a signal from the detection means based on a combination of a light source and an optical sensor such as a phototransistor, utilizing the property that light does not transmit as the amount of liquid fine particles increases. . Further, since the energization amount of the liquid that has captured the particulates increases as the capture amount increases, other detection means such as driving the drive means by the control means based on a signal from the detection means that detects a change in the energization amount and control Means may be used.
[0014]
[Embodiment]
FIG. 1 shows a particulate removing apparatus to which the present invention is applied. The exhaust pipe 14 of the diesel engine 12 is connected to the large diameter pipe 16 of the particulate removing device at a right angle. One end of the large diameter pipe 16 is connected to the pump 22 via a pipe 18. The pump 22 is rotated by being driven by a motor 24 so that the liquid R (water is used in this embodiment) stored in the recovery unit 26 is sucked through the recovery pipe 28 and is pumped into the pipe 18. It has become. The tip of the pipe 18 gradually becomes a nozzle 32 having a smaller diameter and projects coaxially into the large diameter pipe 16.
[0015]
As shown in FIGS. 5 to 8, a step portion 83 is provided on the inner peripheral surface slightly above the tip opening 82 of the nozzle 32, and a diffusion cylinder 85 as a diffusing means is attached to the step portion 83. Yes. The diffusion cylinder 85 has four spiral protrusions 86 protruding inward from the inner peripheral surface at equal intervals. As a result, the liquid R passing through the diffusion cylinder 85 is given a turning force.
[0016]
Accordingly, the liquid R pumped by the pump 22 is ejected from the tip of the nozzle 32 into the small diameter pipe 34 connected to the tip of the large diameter pipe 16 and sent in the same direction as the exhaust gas, and is given by the diffusion cylinder 85. The portion that exits the opening 82 with a turning force is greatly spread. The exhaust gas that reaches the inside of the large-diameter pipe 16 from the exhaust pipe 14 and is sent to the outer periphery of the nozzle 32 is guided into the small-diameter pipe 34, and the finely divided liquid R and the exhaust gas ejected in the small-diameter pipe 34. Contact each other with a wide contact area. As a result, the fine particles contained in the exhaust gas are taken into the particles of the liquid R ejected in a fog state. The optimum inner diameter value of the nozzle 32 is determined by the relative relationship with the inner diameter value of the small diameter pipe 34.
[0017]
On the downstream side of the small-diameter pipe 34, a diameter-expanding pipe 36 whose inner diameter is gradually increased is connected and opened to the top surface of the box-shaped collection part 26. The amount of the liquid is controlled so that the liquid R exists in the recovery unit 26 to a height of about 70% to 80% of the total height. In addition, an extended exhaust gas pipe 38 is connected to the recovery portion 26 substantially in parallel with the enlarged diameter pipe 36. Therefore, the liquid level of the recovery unit 26 is opened in the exhaust gas passage. A sensor 42 for detecting the amount of particulates in the exhaust gas is provided at the intermediate portion of the extended exhaust gas pipe 38. The tip of the extended exhaust gas pipe 38 requires a heater 44, a silencer (not shown), and the like. It is opened to the atmosphere after passing through a special device. The heater 44 heats the water vapor evaporated as the water temperature rises, thereby preventing the water vapor from condensing and discharging white smoke to the atmosphere. The heater 44 is efficient if it passes a part of the exhaust pipe 14 and heats the exhaust gas in the exhaust gas pipe 38 with exhaust gas heat, and the temperature of the exhaust gas pipe 38 reaches a predetermined value, Heating may be interrupted using a timer.
[0018]
The rotation speed of the motor 24 is controlled by a control device 46. The control device 46 detects operating conditions such as the engine load and the rotational speed detected by the amount of fuel supplied to the diesel engine 12 and the amount of intake air, etc., thereby controlling the rotational speed of the motor 24 and Control the amount of liquid delivered. In addition to the above, various detection means can be applied as means for detecting operating conditions such as engine load and rotation speed. The control device 46 also detects the amount of remaining trapped particulates contained in the extended exhaust gas pipe 38 by the sensor 42 and controls the temperature of the heater 44. In the figure, reference numeral 48 denotes a separating means such as a filter for separating the captured fine particles from the liquid. This filter only needs to be able to capture a lump in which fine particles are gathered in a particularly large diameter of 1 to 2 mm, and may have a rough mesh. It should be removable and washable if necessary.
[0019]
As shown in FIG. 1, a particulate removal circuit 88 communicates with the collection unit 26. The circulation path 88 is a lower part of the recovery unit 26, and a take-out pipe 89 opened to a portion where the liquid R is stored, a return pipe 91 opened to the upper part of the recovery part 26, and a filter container connecting these pipes. 92. A filter main body 93 is accommodated in the filter container 92. The take-out pipe 89 is provided with a pump 94 as drive means, and is driven by the control device 46 when necessary and rotated by a motor 96. The filter main body 93 of this embodiment is a cylindrical porous material, and the liquid R from the pipe 89 is taken inward, and the liquid R passes through the filter main body 93 so that fine particles are captured by the porous portion of the filter main body 93. Only the liquid R is returned to the recovery unit 26 through the return pipe 91. The pumps 22 and 94 can be driven by transmitting the rotation of the output shaft of the diesel engine 12.
[0020]
FIG. 2 shows a general fuel injection amount adjusting device for the diesel engine 12. The fuel chamber 52 in which the pressurized fuel is stored communicates with the plunger chamber 56 via the feed hole 54. A plunger 58 is provided in the plunger chamber 56 so that the feed hole 54 can be opened and closed. In this plunger 58, a tappet 59 formed at the lower end is pushed up by a certain amount in synchronization with the vertical movement of the piston 60 by an engine crankshaft cam (not shown), and pressurizes the fuel in the plunger chamber 56. With this fuel pressure, the delivery valve 64 and the nozzle needle 63 are pushed up against the urging force, and fuel is supplied to the combustion chamber 61. At the end of the rise of the plunger 58, an inclined lead groove 58A engraved on the outer periphery of the plunger 58 communicates with the feed hole 54, and this inclined lead groove 58A communicates with the axial hole 58B of the plunger 58, whereby the plan The jar chamber 56 communicates with the feed hole 54 and the fuel pressure supply is stopped.
[0021]
The amount of fuel fed by the plunger 58 is proportional to the rotation angle around the axis of the plunger 58. That is, it is determined depending on at which point of the ascending process of the plunger 58 the inclined lead groove 58A communicates with the feed hole 54 and the fuel feeding process is completed. A control rack 62 is provided to control the fuel supply amount. The control rack 62 is connected to an engine fuel supply control operation handle or an automobile accelerator. When the operator or driver wants to increase the fuel supply amount, the control rack 62 is moved in the direction of arrow A and the control sleeve 67 is moved via the pinion 66. Rotate. This control sleeve 67 is engaged with the driving face 58C of the plunger 58 only in the rotational direction, and the plunger 58 is rotated about its axis to change the corresponding position of the inclined lead groove 58A to the hood hole 54. Change the fuel pumping amount during the stroke.
[0022]
In this embodiment, the amount of movement of the control rack 62 is transmitted to the control device 46, whereby the amount of fuel supplied to the diesel engine 12 is always detected.
[0023]
Next, the operation of this embodiment will be described.
When the diesel engine 12 is operated, exhaust gas discharged from the exhaust pipe 14 is sent to the large diameter pipe 16. The control device 46 drives the motor 24 to eject liquid from the nozzle 32 into the small diameter pipe 34. As a result, the ejected liquid becomes finely particulate, and traps particulates in the exhaust gas. The trapped exhaust gas particulates together with the finely divided liquid pass through the recovery unit 26 and reach the extended exhaust gas pipe 38. In this case, the exhaust gas fine particles come into contact with the liquid level of the liquid R in the recovery unit 26. Is taken into the liquid R in the recovery unit 26. As shown in FIG. 1, when exhaust gas containing exhaust gas particulates is sent vertically downward and collides with the liquid surface of the recovery unit 26, the temperature of the exhaust gas comes into contact with the liquid R in the recovery unit 26. Lowering facilitates liquid recovery. The exhaust gas containing the liquid particles after taking in the exhaust gas fine particles may be passed through the liquid in the recovery unit 26, but in this embodiment, the exhaust gas is passed from the expanded pipe 36 to the upper part of the liquid level of the recovery unit 26. Since the gas passes through the gas and reaches the extended exhaust gas pipe 38, the loss of the exhaust gas pressure is extremely small and the load applied to the diesel engine 12 is also small.
[0024]
The collected liquid R is removed by the particulate separation means 48 and the particulates that have grown to a large size of about several millimeters are removed and returned to the pump 22 for circulation. By making the liquid R to be used weakly alkaline, it is possible to prevent water from being acidified and corroding the material by SO _x or NO _x in the exhaust gas. That is, about 0.2% of sulfur is contained in diesel oil fuel, which is oxidized in the engine and sulfur dioxide is contained in the exhaust gas. This and nitrogen oxides circulate. Dissolves in liquid R, which is water. Since the acidity of the liquid R may be about pH 3 to 5, the interior of the apparatus of the present invention is made of an acid-resistant material, or if the acidity is high, the inner wall that comes into contact with the liquid is glass coated. It is necessary to apply acid-resistant means such as. In this embodiment, the acidity of the liquid R is controlled within the acid-resistant range of the material with a weak alkaline solution without performing such special processing. Is applicable. Since the acidity in the liquid R depends on the operation time, the acidity may be controlled according to the operation time. However, if the operating time is short, it is not necessary to increase the alkalinity so much, so no special control is necessary. Further, when the pH is lowered, a basic substance NaOH or the like may be added to the aqueous solution.
[0025]
As shown in FIG. 3, when the engine load increases, the emission amount of fine particles increases at a certain point of the engine load (load factor is about 25%). The amount of particulate emission increases as the engine speed increases, but the change in particulate emissions relative to the load factor is similar even when the engine speed increases. For this reason, as shown in FIG. 4, the control device 46 sends the liquid amount to the nozzle 32 until the engine speed and load (which are detected as the fuel supply amount, that is, the movement amount of the control rack 62) exceed a predetermined value. Is gradually reduced (or maintained at a constant value), and when the load and the engine speed increase beyond this predetermined value, the liquid feeding amount is increased. For example, the amount of liquid feeding is increased by increasing the rotational speed of the motor 24. Regardless of the amount of liquid sent by the pump 22 or the amount of liquid discharged from the exhaust gas pipe 38 to the atmosphere, liquid replenishing means such as a reserve tank for maintaining the liquid storage amount of the recovery unit 26 constant may be provided.
[0026]
When the operation elapsed time of the engine 12 increases, the concentration of the fine particles trapped in the liquid R increases and the trapping effect decreases. For example, the controller 46 drives the circulation path 88 by operating the pump 94 in a state where the amount of fine particles in the liquid exceeds 350 mg / l. In the case where the liquid R is water or water as a main component, if the amount of fine particles in one liter of water exceeds 350 mg, the fine particle trapping effect is lowered, and if it exceeds 400 mg, the fine particle trapping effect is drastically reduced. Capturing fine particles beyond that becomes almost impossible. FIG. 9 shows the relationship between the operation time and the particulate trapping amount of the apparatus of this embodiment (engine load 32.4 kilowatts, engine speed 1400 rpm), and the amount of particulates per liter exceeds 350 mg in a continuous operation state for 12 hours. The capture effect is reduced. Therefore, by driving the pump 94 (power 1.5 kW, water supply amount 120 l / min) for about 15 to 30 minutes in this state, the fine particles in the liquid are captured by the filter 93 and can be captured again. It was. Increasing the amount of water will further reduce the time. In addition, the control device 46 also has the effect of trapping the fine particles of the liquid R in a state where the elapsed operation time of the engine 12 such as every 12 hours, that is, the total operation time in the case of intermittent operation is a predetermined time. A timer that operates for a predetermined time until recovery may be provided. Since the filter 93 is for capturing fine particles having a fine diameter of about 1 μm, the resistance of the pump 24 is increased when the filter 93 is provided in the recovery pipe 28, but a separate pipe line is formed from the recovery pipe 28. Therefore, the load on the pump 24 is not increased. If all the fine particle removal circulation path 88 is accommodated in the collection unit 26, the entire apparatus can be reduced in size.
[0027]
In addition, although the said embodiment showed the exhaust-gas particulate removal apparatus of the fixed type diesel engine, it is also applicable to mobile diesel engines, such as a motor vehicle engine, and since a liquid can be circulated and used fundamentally, a mobile type Even so, it is easy to handle. In the above-mentioned embodiment, the place where the nozzle for ejecting the liquid is opened can be applied anywhere in the exhaust gas passage of the engine. In addition, the direction of the liquid ejected from the nozzle, that is, the direction of the nozzle may be oblique, lateral, upward, etc. instead of vertically downward as in the above embodiment, and the direction of the exhaust gas contacting the liquid surface is also vertical. It does not have to be downward. Furthermore, in the present invention, two or more devices of the above embodiment may be connected and arranged in multiple stages to improve the particulate collection effect. The present invention is not limited to exhaust gas from a diesel engine, but can be widely applied to exhaust gas from a garbage incinerator or a food cooking device.
[0028]
【The invention's effect】
Since the present invention has the above-described configuration, it is possible to obtain a particulate removal device that is excellent in durability, easy to handle, and can reliably collect particulates in exhaust gas over a long period of time.
[Brief description of the drawings]
FIG. 1 is a schematic side view of a particulate removing device according to an embodiment to which the present invention is applied.
FIG. 2 is a cross-sectional view showing a fuel injection amount adjusting unit used in this embodiment.
FIG. 3 is a diagram showing a discharge amount of fine particles according to a load and a rotational speed of a diesel engine.
FIG. 4 is a diagram showing changes in the amount of supplied liquid in accordance with the load and rotation speed of a diesel engine.
FIG. 5 is a cross-sectional view showing a nozzle tip.
FIG. 6 is a plan view showing a diffusion tube provided at the nozzle tip.
7 is a cross-sectional view taken along line 7-7 in FIG.
FIG. 8 is a partially broken perspective view showing a diffusion tube.
FIG. 9 is a diagram showing the relationship between the operating time and the amount of fine particles in the liquid in the operating state of the fine particle removal circuit.
[Explanation of symbols]
R liquid 12 diesel engine 14 exhaust pipe 22 pump (liquid feeding means)
26 Recovery Unit 28 Recovery Pipe 32 Nozzle 36 Expanded Pipe 38 Extended Exhaust Gas Pipe 46 Control Device (Control Unit)
88 Fine particle removal circuit 89 Extraction pipe 91 Return pipe 93 Filter body 94 Pump (drive means)
96 motor (drive means)

Claims (3)

A nozzle that opens into the exhaust gas passage;
Liquid feeding means for ejecting fine liquid from the nozzle and taking fine particles in the exhaust gas into the liquid;
A recovery unit that opens into the exhaust gas passage and recovers the ejected liquid and circulates it to the liquid feeding means;
Taking out the liquid stored in the recovery unit, removing the fine particles from the liquid, and then returning the particles to the recovery unit;
Drive means for driving the particulate removal circuit at a predetermined time to send liquid to the circuit;
In a fine particle removing apparatus having
The liquid feeding means ejects the fine liquid from the nozzle toward the liquid surface of the recovery unit, and causes the exhaust gas containing the liquid after the fine particles are taken in to collide with the liquid surface of the recovery unit. A particulate removal apparatus characterized by the above.   2. The particulate removing apparatus according to claim 1, wherein the driving means drives the circulation path in a state where the amount of particulates in the liquid exceeds 350 mg / l.   2. The particulate removing apparatus according to claim 1, wherein the driving unit drives the circulation path every predetermined time.

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