JP6662507B2 - Exhaust gas treatment device and exhaust gas treatment method - Google Patents

Description

  The present invention relates to an exhaust gas processing apparatus and an exhaust gas processing method for cleaning exhaust gas generated by an engine with a scrubber to remove solid components such as dust, and then discharging the exhaust gas to an exhaust path. The present invention relates to an exhaust gas treatment apparatus and an exhaust gas treatment method capable of suppressing the amount of solid components such as dust and the like.

  Ships are equipped with diesel engines called main engines and auxiliary machines. Various exhaust gas treatment apparatuses have been proposed for removing exhaust gas and the like by cleaning exhaust gas generated from the diesel engine with a scrubber (for example, see Patent Document 1).

  Patent Literature 1 discloses a scrubber that cleans exhaust gas with cleaning water such as seawater, a buffer tank that collects wastewater from the scrubber (hereinafter, sometimes referred to as scrubber wastewater), and a scrubber wastewater stored in the buffer tank. An exhaust gas treatment device including a centrifugal separator for removing solid components such as dust is proposed.

  Most of the scrubber effluent collected in the buffer tank is supplied again to the scrubber, and a part is treated by a centrifuge. The gas phase portion in the buffer tank has been discharged, for example, directly into the atmosphere via an exhaust path, or has been discharged to the atmosphere together with the exhaust gas purified by the scrubber.

  The oil contained in the scrubber wastewater may be vigorously mixed with seawater or the like as washing water and emulsified. Emulsions generated by emulsification of oil (hereinafter sometimes referred to as scum) may include solids such as dust contained in scrubber drainage. This scum is a creamy fluid having a high viscosity and has a lower specific gravity than a scrubber drainage mainly composed of seawater.

  This scum was sometimes generated while scrubber wastewater was sent to the buffer tank. The gas phase in the buffer tank sometimes contained fine scum dispersed in a mist. This fine scum is discharged to the discharge path and adheres to the inner wall surface of the discharge path, thereby causing exhaust resistance, or adhering to a blower or the like installed in the middle of the discharge path to reduce efficiency. Had occurred.

JP-T-2013-527788

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an exhaust gas treatment apparatus and an exhaust gas treatment method capable of suppressing the amount of solid components such as dust discharged to an exhaust passage.

An exhaust gas treatment apparatus of the present invention that achieves the above object has a scrubber that purifies exhaust gas generated by an engine with washing water, a buffer tank that collects and stores the washing water discharged from the scrubber, And an exhaust path for discharging the exhaust gas washed with a scrubber, wherein the gas in the buffer tank is supplied to separate a solid component from the gas, and the solid component is removed. A gas-solid separation mechanism for discharging the gas to the discharge path, a line communicating the vicinity of the bottom surface of the gas-solid separation mechanism with the buffer tank, and a valve installed on this line, wherein the line is The washing water flowing into the gas-solid separation mechanism is provided to the buffer tank .

An exhaust gas treatment method of the present invention is the exhaust gas treatment method of washing exhaust gas generated by an engine with washing water, storing the washing water in a buffer tank, and discharging the washed exhaust gas to an exhaust path. Discharging the gas to a discharge path after separating a solid component from a gas in the buffer tank by a gas-solid separation mechanism, and allowing a line near the bottom surface of the gas-solid separation mechanism to communicate with the buffer tank, A valve installed in a line is opened to flow the washing water flowing into the gas-solid separation mechanism into the buffer tank .

  According to the present invention, since solid components such as particulate dust contained in the gas in the buffer tank can be removed, it is advantageous to suppress the amount of solid components discharged to the exhaust path. is there.

FIG. 2 is an explanatory view illustrating an exhaust gas treatment device of the present invention. FIG. 2 is an explanatory view illustrating the gas-solid separation mechanism of FIG. 1. FIG. 4 is an explanatory diagram illustrating a modification of the gas-solid separation mechanism in FIG. 2. FIG. 4 is an explanatory diagram illustrating a modification of the gas-solid separation mechanism in FIG. 2. FIG. 5 is an explanatory view illustrating an exhaust gas treatment device according to another embodiment of the present invention.

  Hereinafter, an exhaust gas processing apparatus and an exhaust gas processing method of the present invention will be described based on an embodiment shown in the drawings. In the figure, for the sake of explanation, the moving path of the liquid such as the washing water w0 is indicated by a solid line, the moving path of the gas such as the exhaust gas g0 is indicated by a broken line, and the moving path of the solid such as scum s and solid components is indicated by a chain line. ing.

  As illustrated in FIG. 1, an exhaust gas treatment apparatus 1 of the present invention collects a scrubber 3 for cleaning exhaust gas g0 generated by an engine 2 with cleaning water w0 and a scrubber drainage w1 discharged from the scrubber 3. It has a buffer tank 4 for storing, and a discharge path 5 for discharging the cleaned exhaust gas g1 purified by the scrubber 3. In the present specification, the discharge path 5 is a general term for a path installed downstream of the scrubber 3, for example, a pipe that directly or indirectly discharges into the outside air, or a pipe installed in the middle of this pipe. It includes equipment such as a blower. A part of the exhaust gas g1 washed by the scrubber 3 flows into the buffer tank 4 together with the scrubber drainage w1. Most of the scrubber drainage w1 stored in the buffer tank 4 is supplied to the scrubber 3 again as washing water w0.

  The exhaust gas treatment device 1 is provided with a water treatment mechanism 6 that is supplied with a part of the scrubber wastewater w1 stored in the buffer tank 4 to remove solid components such as dust contained in the scrubber wastewater w1; And a sludge tank 7 for collecting and storing the solid components separated in the step. The water treatment mechanism 6 is composed of, for example, a centrifuge or a separation membrane. The scrubber wastewater w1 from which solid components have been removed by the water treatment mechanism 6 is supplied to the scrubber 3 again as washing water w0.

  In the present invention, the installation positions of the water treatment mechanism 6 and the sludge tank 7 are not limited to the above, and can be appropriately changed. Further, a configuration in which one or both of the water treatment mechanism 6 and the sludge tank 7 are not provided may be adopted.

The exhaust gas treatment device 1 is provided with a gas-solid separation mechanism 8 which is supplied with a gas g2 constituting a gas phase portion of the buffer tank 4 and removes a solid component from the gas g2. The gas-solid separation mechanism 8 is constituted by, for example, a cyclone type separation mechanism. The gas-solid separation mechanism 8 is a gas g3 from which solid components have been removed.
To the discharge path 5.

  When the scrubber wastewater w1 is collected from the scrubber 3 into the buffer tank 4, the oil in the scrubber wastewater w1 may be emulsified to generate scum s. The scum s is generated due to the pressure drop when the scrubber drainage w1 moves to the buffer tank 4 and the agitation of the scrubber drainage w1 in the buffer tank 4. Since the scum s has a relatively low specific gravity, it often floats on the liquid surface in the buffer tank 4.

  Since the scrubber drainage w1 is continuously supplied to the buffer tank 4, the liquid surface is beaten or agitated, so that the scum s soars as fine particles in the gas phase in the buffer tank 4.

  The gas-solid separation mechanism 8 is supplied from the buffer tank 4 with the gas g2 containing the scum s soared in the form of a mist, and removes fine particles of the scum s from the gas g2. The scum s collected by the gas-solid separation mechanism 8 is sent to the sludge tank 7. The gas g3 from which the scum s has been removed by the gas-solid separation mechanism 8 is guided to the discharge path 5, and merges with the exhaust gas g1 washed by the scrubber 3. The scum s removed by the gas-solid separation mechanism 8 contains solid components such as dust.

  The exhaust gas g1 and the gas g3 that join in the discharge path 5 are subjected to removal of NOx by a separately installed device or the like, or are directly released to the atmosphere when purification is sufficient.

  By collecting the mist scum s contained in the gas g2 constituting the gas phase part of the buffer tank 4 by the gas-solid separation mechanism 8, solid components such as dust contained in the scum s can be collected. This is advantageous for suppressing the amount of the solid component discharged to the discharge path 5.

  The particulate scum s contained in the gas g2 can be prevented from adhering to the inner wall surface of the discharge path 5. Therefore, it is advantageous to avoid a problem that the scum s accumulates in the discharge path 5 due to long-term use of the exhaust gas treatment device 1 and the discharge path 5 is blocked. Further, it is advantageous to suppress the pressure loss when the exhaust gas g1 and the gas g3 pass through the discharge path 5.

  In a conventional exhaust gas treatment apparatus, solid components are collected only by a water treatment mechanism such as a centrifuge. In a water treatment mechanism such as a centrifugal separator, it is difficult to separate scum s which is relatively light as compared with scrubber drainage, and it is difficult to collect solid components such as dust contained in the scum s.

  On the other hand, the exhaust gas treatment apparatus 1 of the present invention can collect the scum s in the gas-solid separation mechanism 8 in addition to the collection of the solid components in the water treatment mechanism 6. Since the solid components such as dust contained in the scum s can be collected with the recovery of the scum s, the amount of the solid components collected in the exhaust gas treatment device 1 can be increased. This is advantageous for suppressing the amount of the solid component discharged to the discharge path 5.

  A recovery mechanism 4a for recovering the scum s may be provided near the liquid surface of the buffer tank 4. The recovery mechanism 4a can be constituted by, for example, an arm-type scum recovery device including an arm for collecting the scum s floating on the liquid surface and a recovery unit for recovering the scum s collected by the arm. The recovery mechanism 4a may be constituted by a scum skimmer. The scum s collected by the collection mechanism 4a is sent to the sludge tank 7.

  According to this configuration, since the scum s in the buffer tank 4 can be efficiently collected, it is advantageous to suppress the amount of the solid component discharged to the discharge path 5.

As illustrated in FIG. 2, the gas-solid separation mechanism 8 can be constituted by a cyclone type separation mechanism. The gas-solid separation mechanism 8 in this embodiment has a main body 9 having a truncated conical shape having a hollow portion inside and having a diameter decreasing downward with the vertical direction as the axial direction, and disposed near the upper end of the main body 9. And a supply port 10 for guiding and turning the gas g2 supplied from the buffer tank 4 into the main body 9. The main body 9 has a solid discharge port 11 formed at a lower end and a gas discharge port 12 formed at an upper end. In FIG. 2, for the sake of explanation, the moving path of the gas g2 is indicated by a broken line, and the moving path of the scum s is indicated by an alternate long and short dash line.

  The gas g2 supplied from the supply port 10 moves downward while turning in the main body 9. The scum s sufficiently heavier than the gas g2 moves downward while colliding with the inner wall surface of the main body 9 and is discharged from the solid discharge port 11. The scum s discharged from the solid discharge port 11 is sent to the sludge tank 7. The gas g3 from which the solid components have been removed is sent to the discharge path 5 from the gas discharge port 12 above the main body 9.

  As illustrated in FIG. 3, the gas-solid separation mechanism 8 can be composed of a cylindrical casing 13 whose axial direction is the vertical direction, and a pushing mechanism 14 disposed inside the casing 13. The casing 13 includes a supply port 10 and a gas discharge port 12 formed at an upper end, and a solid discharge port 11 formed at a lower end. Further, the casing 13 includes an inclined portion 15 which is inclined downward from an intermediate portion in the vertical direction of the casing 13 and toward the central axis of the casing 13. The inclined portion 15 is made of, for example, a funnel-shaped plate or the like disposed inside the casing 13.

  The pushing mechanism 14 includes a rotating shaft 16 extending vertically and penetrating through the casing 13, a motor 17 provided outside the casing 13 at the upper end of the rotating shaft 16, and disposed near the lower end of the rotating shaft 16. The screw 18 is provided. The outer peripheral edge of the screw 18 is configured to be in contact with the inner wall surface of the inclined portion 15.

  The gas g2 supplied from the buffer tank 4 is supplied from the supply port 10 to the inside of the casing 13 and collides with the inner wall surface and the inclined portion 15 of the casing 13 and then sent from the gas discharge port 12 to the discharge path 5. When the gas g2 collides with the inner wall surface of the casing 13 or the inclined portion 15, fine scum s adheres to the inner wall surface or the like. The scum s attached to the inner wall surface or the like of the casing 13 moves downward by its own weight. After a certain period of time, the scum s is deposited on the inclined portion 15.

  When the screw 18 is rotated by the operation of the motor 17, the scum s deposited on the inclined portion 15 is pushed into the solid discharge port 11 and sent to the sludge tank 7. The motor 17 may be configured to always rotate, or may be configured to rotate intermittently.

  According to this configuration, even in a case where there is almost no pressure difference between the supply port 10 and the gas discharge port 12 and a sufficient swirling flow cannot be generated by the above-described cyclone-type separation mechanism, The scum s can be efficiently removed from the gas g2 even when there is almost no pressure difference between the gas phase portion 4 and the discharge path 5.

  The pushing mechanism 14 only needs to have a function of pushing the scum s accumulated in the casing 13 into the solid discharge port 11, and is not limited to the screw conveyor system described above. The pushing mechanism 14 may be constituted by, for example, a scraper that moves up and down along at least one of the inner wall surface of the casing 13 and the inclined portion 15. Further, a configuration without the inclined portion 15 may be adopted. In this case, the pushing mechanism 14 has a configuration in which the scum s attached to the inner wall surface of the cylindrical casing 13 is pushed into the solid discharge port 11.

As illustrated in FIG. 4, the supply port 10 and the gas discharge port 12 formed at the upper end of the casing 13, the solid discharge port 11 formed at the lower end, and the inside of the casing 13 below the supply port 10. And a mesh portion 19 disposed at the same position.

  The casing 13 includes a conical inclined portion 15 that becomes thinner toward the lower end below the cylindrical main body 9. In this embodiment, the inclined portion 15 is formed integrally with the casing 13.

  The supply port 10 and the gas discharge port 12 are formed by pipes that penetrate from the upper surface of the casing 13 toward the inside. Below the pipe constituting the supply port 10, a mesh portion 19 composed of, for example, one wire mesh or a wire mesh of a plurality of wires is arranged. The mesh portion 19 is fixed directly or indirectly to the inner wall surface of the casing 13. The mesh portion 19 has a configuration in which fine scum s contained in the gas g2 is attached and removed.

  The solid discharge port 11 is constituted by a pipe connected to the bottom surface of the casing 13, and a valve 20 is provided at an intermediate portion of the pipe.

  When the gas g2 is supplied from the supply port 10 into the casing 13, the gas g2 is discharged from the gas discharge port 12 after passing through the mesh portion 19. The fine scum s contained in the gas g2 adheres to a wire mesh or the like constituting the mesh portion 19 when passing through the mesh portion 19, and is removed from the gas g2. The scum s attached to the wire mesh of the mesh portion 19 falls toward the bottom surface of the casing 13 and accumulates.

  The scum s accumulated in the casing 13 falls to the sludge tank 7 by its own weight when the valve 20 is opened. When the pressure inside the casing 13 is higher than the pressure inside the sludge tank 7, the scum s is pushed into the sludge tank 7 by this pressure difference.

  The opening and closing of the valve 20 can be manually operated. A control mechanism 21 for automatically controlling the valve 20 may be provided so that the valve 20 is temporarily opened every predetermined time. Further, the opening and closing of the valve 20 may be controlled by the control mechanism 21 in accordance with the amount of scum s accumulated in the casing 13. At this time, for example, a level gauge 22 that responds according to the height at which the scum s is deposited can be provided on the casing 13. The measurement or estimation of the amount of the scum s is not limited to the level meter 22, and may be performed by a load cell or the like that measures the weight of the scum s.

  As illustrated in FIG. 5, the exhaust gas processing device 1 can be applied to a configuration including an EGR system 23 that recirculates a part of the exhaust gas to the engine 2. In this embodiment, the exhaust gas treatment device 1 is installed at a position where the mist catcher 24 is installed at an intermediate portion of the discharge path 5 and downstream of the mist catcher 24 and upstream of a branch portion to the EGR system 23. And a blower 25 to be used. The gas g3 from which the solid components have been removed by the gas-solid separation mechanism 8 is supplied to the mist catcher 24. In this embodiment, the discharge path 5 includes a pipe of the EGR system 23, a mist catcher 24, and a blower 25 in addition to a pipe through which exhaust gas flows.

  The mist catcher 24 is made of, for example, a laminated wire net, and has a function of attaching and removing fine particles contained in the passing exhaust gas g1. Since the fine particles in the exhaust gas g1 can be removed by the mist catcher 24, it is advantageous to suppress the amount of the solid component discharged to the discharge path 5. Since gas containing almost no solid component can be supplied to the engine 2 by the EGR system 23, it is advantageous to improve the combustion efficiency of the engine 2. This is advantageous for avoiding a problem that fine particles such as dust adhere to the blower 25 to lower the air supply efficiency of the blower 25 and that the blower 25 breaks down.

  Since the gas g3 supplied from the gas-solid separation mechanism 8 to the mist catcher 24 contains almost no scum in the form of fine particles, problems such as scum adhering to and depositing on the mist catcher 24 and the blower 25 do not occur.

  The configuration of the mist catcher 24 is not limited to the above. For example, the mist catcher 24 may be configured by arranging a plurality of flat plates in a state where the plane direction is parallel to the flow direction of the exhaust gas g1. The installation position of the blower 25 is not limited to the above. For example, the blower 25 may be installed at a position downstream of the mist catcher 24 and downstream of a branch to the EGR system 23.

  A configuration may be adopted in which a line 26 that connects the gas-solid separation mechanism 8 and the buffer tank 4 is arranged. A valve 27 is disposed on the line 26, and one end of the line 26 is connected to the vicinity of the bottom surface of the gas-solid separation mechanism 8. The valve 27 is normally closed.

  Water w1 in the buffer tank 4 may flow into the gas-solid separation mechanism 8 due to the effect of pressure fluctuations in the buffer tank 4 and the gas-solid separation mechanism 8. The flow of the water w1 may occur, for example, several times a hour. When the water w1 flows into the gas-solid separation mechanism 8, the valve 20 disposed between the gas-solid separation mechanism 8 and the sludge tank 7 is closed.

  When the water w1 flows into the gas-solid separation mechanism 8, the water w1 is mixed with the scum s collected by the gas-solid separation mechanism 8. However, when left still for a while, water and scum s are separated due to a difference in specific gravity. When the valve 27 is opened after standing still, water w1 having a large specific gravity flows from the gas-solid separation mechanism 8 into the buffer tank 4. When the valve 20 is opened after the valve 27 is closed, the separated scum s is sent to the sludge tank 7.

  According to this configuration, even when the water w1 suddenly flows into the gas-solid separation mechanism 8 from the buffer tank 4, at least a part of the water w1 can be returned to the buffer tank 4, so that the capacity of the sludge tank 7 is increased. Can be suppressed from being pressed by the water w1.

  A configuration may be adopted in which a pressure type liquid level gauge is installed in the gas-solid separation mechanism 8 in advance, the amount of water w1 separated by specific gravity is estimated by the liquid level gauge, and the water w1 is returned to the buffer tank 4. The pressure-type liquid level gauge has a configuration in which, for example, the liquid pressure in the gas-solid separation mechanism 8 is sensed by a diaphragm, and the pressure is measured from a change in capacitance caused by a change in distance between two electrodes arranged in parallel.

  This pressure type liquid level gauge can measure the liquid level without being affected by the scum s floating on the water w1. That is, it is possible to measure the position of the liquid surface which is the boundary between the water w1 separated from the specific gravity and the scum s. By controlling the opening and closing of the valve 27 based on the measurement result by the liquid level gauge, it becomes easy to return only the water w1 to the buffer tank 4.

  Regardless of the amount of the water w1, the valve 27 may be opened for a predetermined time and then closed. Since at least a part of the water w1 in the gas-solid separation mechanism 8 can be returned to the buffer tank 4, it is possible to prevent the capacity of the sludge tank 7 from being pressed by the water w1.

  The opening time of the valve 27 may be set relatively long so that the entire water w1 in the gas-solid separation mechanism 8 is returned to the buffer tank 4. At this time, a part of the scum s may move to the buffer tank 4 together with the water w1. However, since the scum s is later collected by the collection mechanism 4a installed in the buffer tank 4, there is no problem. Since the water w1 can be prevented from being sent to the sludge tank 7, the capacity of the sludge tank 7 can be prevented from being compressed by the water w1. Note that the recovery mechanism 4a is not an essential requirement of the present invention.

  The configuration in which the line 26 and the valve 27 for communicating the gas-solid separation mechanism 8 and the buffer tank 4 are provided can be adopted also in the embodiment illustrated in FIG.

DESCRIPTION OF SYMBOLS 1 Exhaust gas processing apparatus 2 Engine 3 Scrubber 4 Buffer tank 4a Recovery mechanism 5 Drainage path 6 Water treatment mechanism 7 Sludge tank 8 Gas-solid separation mechanism 9 Main body 10 Supply port 11 Solid discharge port 12 Gas discharge port 13 Casing 14 Pushing mechanism 15 Incline Unit 16 Rotary shaft 17 Motor 18 Screw 19 Mesh unit 20 Valve 21 Control mechanism 22 Level meter 23 EGR system 24 Mist catcher 25 Blower 26 Line 27 Valve g0 Exhaust gas g1 Exhaust gas g2 after cleaning Constitutes gas phase part of buffer tank Gas g3 Gas from which solid components have been removed w0 Wash water w1 Scrubber drainage s Scum

Claims (5)

A scrubber for purifying exhaust gas generated by the engine with washing water, a buffer tank for collecting and storing the washing water discharged from the scrubber, and a discharge path for discharging the exhaust gas washed by the scrubber. In the exhaust gas treatment device provided,
A gas-solid separation mechanism for supplying a gas in the buffer tank to separate a solid component from the gas and discharging the gas from which the solid component has been removed to the discharge path, and a bottom surface of the gas-solid separation mechanism A line communicating the vicinity with the buffer tank, and a valve installed in this line,
The exhaust gas treatment device , wherein the line has a configuration in which the washing water flowing into the gas-solid separation mechanism flows into the buffer tank .   The exhaust gas treatment device according to claim 1, wherein the gas-solid separation mechanism is constituted by a cyclone type separator.   2. The exhaust gas treatment device according to claim 1, wherein the gas-solid separation mechanism includes a casing to which the gas is supplied, and a pushing mechanism that discharges the solid component attached to the casing to the outside of the casing. An exhaust gas treatment method comprising: washing exhaust gas generated by an engine with washing water, storing the washing water in a buffer tank, and discharging the washed exhaust gas to an exhaust path.
Discharging the gas into a discharge path after separating a solid component from the gas in the buffer tank by a gas-solid separation mechanism ,
The vicinity of the bottom surface of the gas-solid separation mechanism is communicated with the buffer tank by a line, and a valve installed in the line is opened to flow the washing water flowing into the gas-solid separation mechanism into the buffer tank. An exhaust gas treatment method characterized by the above-mentioned. When separating the solid component from the gas in the buffer tank, the gas is supplied to a casing to attach the solid component to the inner wall surface of the casing, and the solid component attached to the casing is pushed by a pushing mechanism. The exhaust gas treatment method according to claim 4 , wherein the exhaust gas is discharged outside the casing.

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