JP2010071148A - Exhaust gas purification system for engine in marine vessel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a NOx conversion system suitable for a marine vessel. <P>SOLUTION: An exhaust gas treatment device 9 with a built-in SCR reduction catalyst 10 is connected to the exhaust pipe 7 of an engine 1, and NOx is decomposed by spraying urea water on the exhaust pipe 7. The urea water is produced in a mixing tank 25 and adjusted to concentration in response to the output of the engine 1 in an adjusting tank 26. The marine vessel has a drinking water generator 21 for obtaining water for living use and a water tank 22. Water is fed from the water tank 22 to the mixing tank 25, and the urea water is produced by mixing water and powdered or granulated material urea in the mixing tank 25. Although the amount of the urea water used is large because the engine of the marine vessel is continuously operated with large output for a long period of time, the urea water can be produced as needed by using the drinking water generator 21 always provided in the ship. Therefore, even in the marine vessel that cannot receive the urea water on the ocean, it is possible to convert NOx while ensuring space saving and power saving. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification system for an engine (diesel engine) in a ship.

  In diesel engines, an SCR catalyst purification method using urea as a reducing agent has become common as a purification means for NOx (nitrogen inclusions) contained in exhaust gas. In this SCR catalyst purification method, in general, a honeycomb structure made of a material in which an active component such as V or Cr is supported on an oxide carrier such as Ti is used, and an aqueous reducing agent solution is provided upstream of the honeycomb structure. When the urea water is sprayed, the urea water is hydrolyzed by the heat of the exhaust gas to generate ammonia. This ammonia acts on NOx as a reducing agent, and NOx is decomposed into harmless nitrogen and water.

In the SCR catalyst purification method, it is necessary to continue spraying urea water on the exhaust gas. Therefore, in a land vehicle such as a truck, a tank of urea water is attached to the vehicle. Further, in Patent Document 1, as a kind of stand equipment for supplying urea water to a vehicle, an apparatus for producing urea water with a water supply gun in a cart system in which water and raw material urea are charged into a tank and stirred. Is disclosed.
JP-A-2005-324134

  Now, in the case of a land vehicle such as a truck, it can be said that there is no particular problem because the urea water tank mounted on the vehicle can be replenished at a gas station or a garage even if the capacity is small. However, on the other hand, in the case of medium-sized and large vessels that do not call (return to the port) for several days to several months once they depart, such as cargo ships and ocean fishing boats, urea water is also onboard because there is no supply facility such as a stand on the ocean. Must be procured.

  As a means of procuring urea water on a ship, it is conceivable to install a urea water tank that can cover the amount of use from departure to call, but once a ship departs, it continues to operate its engine offshore. In addition to the fact that the amount of urea water used per unit output is significantly higher than that of land vehicles, the marine engine has a much higher output than the land vehicle engine. Therefore, the amount of urea water to be used is large, and therefore the urea water tank must be huge. Except for some ships, the reality is poor.

  As another means for procuring urea water in a ship, it may be possible to arrange the urea water production apparatus described in Patent Document 1 in an engine room. This method does not require a huge tank, so it is more realistic than the tank-only method. However, it is a lot of labor to manually supply the aqueous urea solution to the aqueous solution tank with a gun. It is hard to be accepted by the current ship that advances.

  The present invention has been made in view of such a current situation, and intends to provide an exhaust gas purification system excellent in practicality and practicality in consideration of the special characteristics of a ship.

  The invention of the present application is equipped with an engine, a desalinator that desalinates seawater, and a water tank that stores fresh water produced by the desiccator, and a reducing agent provided in a reduction catalyst provided in an exhaust pipe of the engine The NOx contained in the exhaust gas of the engine is purified by spraying the aqueous solution. Further, the reducing agent aqueous solution converts the solid raw material reducing agent such as powder or granules into fresh water. For ships that are manufactured by mixing.

  And in invention of Claim 1, the engine, the water generator which desalinates seawater, and the water tank which stores the fresh water made with the said water generator are mounted, and it provided in the exhaust pipe of the said engine. The NOx contained in the exhaust gas is purified by spraying a reducing agent aqueous solution on the reducing catalyst, and the reducing agent aqueous solution is a solid raw material reducing agent such as powder or granules. It is manufactured by mixing with fresh water.

  In addition to claim 1, the invention of claim 2 is further provided with an output sensor for detecting the output of the engine or a concentration sensor for detecting NOx concentration in the exhaust gas. Is provided with an adjustment tank that adjusts the concentration of the reducing agent by diluting the reducing agent aqueous solution supplied from the mixing tank with fresh water, and the reduction in the adjustment tank is based on a signal from the output sensor or the concentration sensor. The concentration of the agent is adjusted, and the adjustment tank is also supplied with water from the water tank.

  A third aspect of the present invention provides the raw material reducing agent according to the first or second aspect, wherein the raw material reducing agent is urea or its content and has a powdery or granular appearance, while the raw material tank is provided with a drying means. The mixing tank and the adjustment tank are provided with a heating means. As a development example of the third aspect, in the fourth aspect, the heating means uses exhaust gas of the engine or used cooling water as a heat source.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the mixing tank is provided with a water level sensor, while the supply of the raw material reducing agent from the raw material hopper to the mixing tank is controlled by a shutter means. In addition, the raw water pipe is provided with water supply means, and the water level sensor, the water supply means, and the shutter means are supplied with water supplied by the water supply means operated by a lower limit level detection signal from the water level sensor. The water supply means is stopped by the upper limit level detection signal from the water level sensor, and the shutter means is opened and the raw material reducing agent is introduced after water supply to the mixing tank or after or before water supply. .

  Now, medium and large ships are usually equipped with a desalinator that desalinates seawater (freshwater) in order to provide water for daily use, and the fresh water produced by the dessicator is stored in a water tank. As a result, the pipes are supplied to each place of use. In the present invention, since the reducing agent aqueous solution is produced by mixing the powdery or granular raw material reducing agent with fresh water in the mixing tank, that is, the reducing agent aqueous solution can be produced at any time while sailing. The tank does not need to be huge and can contribute to space saving. Since the raw water used for the reducing agent aqueous solution is supplied from the water tank, it is not necessary to newly install or add a fresh water generator for producing the reducing agent aqueous solution, which can contribute to cost reduction.

  Further, since the reducing agent aqueous solution produced in the mixing tank is automatically supplied to the catalyst via the aqueous solution pipe, it does not require manual labor. That is, the present invention contributes to labor saving and is therefore suitable for modern ships.

  In a diesel engine, the concentration of NOx contained in exhaust gas generally increases in proportion to the output. Therefore, the concentration of the reducing agent aqueous solution sprayed on the catalyst is preferably increased or decreased in proportion to the concentration of NOx (the amount of spray can be increased or decreased depending on the concentration, but there is a problem that the amount of water generated increases. .)

  In the case of claim 1 of the present invention, it is possible to adjust the concentration in the mixing tank. However, adjusting the concentration by dispensing the raw material reducing agent and dilution water is troublesome and the concentration adjustment is accurate. There is a possibility that it cannot be done. On the other hand, when the configuration of claim 2 is adopted, a high concentration reducing agent aqueous solution corresponding to (or higher than) the highest output (NOx concentration) is produced in the mixing tank, and diluted water is supplied in the adjustment tank. By adding, there exists an advantage which can manufacture easily the aqueous solution of a desired reducing agent active. Further, since the dilution water in the adjustment tank is also supplied from the water tank, it is not necessary to newly install or add a fresh water generator, which is advantageous in terms of cost.

  When urea or its inclusion is used as a raw material reducing agent as in claim 3, there is an advantage of excellent safety. Urea has the advantage of high safety, but has the property of high hygroscopicity and the property that the dissolved amount (the number of moles dissolved per unit amount of water) decreases as the temperature of the aqueous solution decreases. In the item 3, since the raw material tank is provided with a drying means and the mixing tank and the adjustment tank are provided with a heating means, it is possible to prevent or suppress the drying of the raw material urea and contribute to the realization of automatic mixing. It can contribute to efficient NOx removal by preventing a decrease in the concentration of urea in it. The heating temperature is preferably about 40 ° C.

  In the case of claim 3, an electric heater such as a sheathed heater can be used as the heating means for the mixing tank and the adjustment tank. However, if the exhaust gas of the engine or the used cooling water is used as the heating means as in claim 4, There is an advantage that the running cost can be suppressed.

  As a specific method of manufacturing the reducing agent aqueous solution in the mixing tank, it is possible to periodically manufacture and store it at a predetermined time interval, for example, once a day. It is negative in terms of space saving because the tank is large, and negative in terms of labor saving because it requires manpower. On the other hand, if the structure of claim 5 is adopted, since the manufacture and replenishment are automatically performed when the stock of the aqueous solution is reduced to a predetermined amount, it is not necessary to make the mixing tank and the adjustment tank larger than necessary and save space. In addition to being able to promote, it can greatly contribute to labor saving by eliminating human resources.

  Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a conceptual block diagram showing the arrangement of equipment in a ship, and the embodiment of the present invention is condensed in FIG.

(1) Basic configuration around the engine As shown in FIG. 1, the ship includes a diesel engine 1, and a generator 2 is connected to the engine 1. Fuel is supplied to the engine 1 from either the first fuel tank 3 or the second fuel tank 4. Therefore, a three-way valve 6 is interposed in the fuel line 5 connecting the fuel tanks 3 and 4 and the engine 1. The two fuel tanks 3 and 4 can store the same type of fuel, and can be classified into general fuel such as A heavy oil and high quality heavy oil such as low sulfur heavy oil.

  The generator of the present embodiment is mainly for driving a marine propulsion motor, but the engine 1 can also drive the screw directly. Of course, the generator 2 may be connected to the engine 1 as a dedicated engine for obtaining electric power to be used in the ship. An output sensor 7 is attached to the generator 2. The output sensor 7 directly detects the output (or load) of the generator, but the output of the engine 1 and the output of the generator 2 are almost the same, so the output sensor 7 functions as an output detection means of the engine 1. ing.

  The engine 1 has a main exhaust pipe 8 connected to an exhaust manifold, and an exhaust treatment device 8 is connected in the middle of the main exhaust pipe 8. The exhaust treatment device 9 has an SCR reduction catalyst 10 described above, a slip catalyst 11 for treating NOx that has passed through the SCR reduction catalyst 10, and a silencer 12 in order from the upstream side when viewed from the flow direction of the exhaust gas. is doing. A discharge pipe 13 is connected to the silencer 12. Note that the discharge pipe 13 can also be considered as a part of the main exhaust pipe 8. In this case, the exhaust treatment device 9 is interposed in the middle of the main exhaust pipe 8. For convenience, the upstream side portion of the exhaust treatment device 9 is defined as the main exhaust pipe 8.

  A spray port 15 for spraying urea water as an example of the reducing agent aqueous solution is provided in the middle of the main exhaust pipe 8. In addition, a blower 14 that ejects air toward the SCR reduction catalyst 10 is connected to the exhaust treatment device 9. A bypass exhaust pipe 16 is connected upstream of the spray port 15 in the main exhaust pipe 8, and the end of the bypass exhaust pipe 16 is connected to the silencer 12 portion of the exhaust treatment device 8. Yes.

  A switching valve 17 for changing the flow direction of the exhaust gas is provided at a connection portion between the exhaust switching valve 17 and the bypass exhaust pipe 16. A specific structural example of the switching valve 17 is shown in FIG. That is, in this example, the switching valve 17 is of a flat plate type and rotates around a support shaft located at one end thereof, and when rotated by an actuator 18 such as a motor, the inlet of the bypass exhaust pipe 16 is provided. Are switched to a posture for closing the main exhaust pipe 8 and a posture for closing the main exhaust pipe 8.

(2) Urea water supply system The ship has a water generator 21 that pumps seawater into fresh water by the first pump 20, and a water tank 22 that stores fresh water produced by the water generator 21. is doing. Both are conventionally used in ships, and a number of general water pipes 23 for supplying water to a kitchen, a washroom, etc. are connected to the water tank 22.

  There are cases where a lot of germs are mixed in the water that has just been desalinated by the water generator 21. Therefore, sterilization is also performed as drinking water or kitchen water. In this case, miscellaneous water before sterilization and sterilized drinking water are separately stored in a water tank. In this case, in this embodiment, any tank can be used as the water tank 22 (because urea water is not potable, it can be used with miscellaneous water).

  The ship further includes a raw material hopper 24 into which granular urea as an example of the raw material reducing agent is charged, a mixing tank 25 that mixes the raw material urea supplied from the raw material hopper 24 with water to form urea water, and a mixing tank 25. And an adjustment tank 26 for adjusting the concentration of the urea water produced in (1).

  The mixing tank 25 and the water tank 22 are connected by a raw water pipe 27, and the raw material pipe 27 is provided with a second pump 28 as an example of water supply means for turning ON / OFF the water supply. And the adjustment tank 26 are connected by a first aqueous solution pipeline 29, and a third pump 30 is interposed in the first aqueous solution pipeline 29. The adjustment tank 26 and the spray port 15 are connected by a second aqueous solution conduit 31, and an electromagnetic on-off valve 32 is interposed in the second aqueous solution conduit 31.

  The raw material hopper 24 is provided with a drying device 34, and the discharge pipe 36 between the raw material hopper 24 and the mixing tank 25 is provided with shutter means 37 for opening and closing the discharge pipe 36. The drying device 34 can use a warm air type or a hygroscopic type. The raw material hopper 24 is provided with a capacity sensor 35 that detects the amount of raw material urea. The specific structure of the shutter means 36 is also shown in FIG. This shutter means is driven remotely by an actuator such as an electromagnetic solenoid.

  In addition, when releasing the raw material urea with the raw material hopper 24, there can be a method in which the flow continues as long as the shutter means 37 is open, and a dredging method in which a certain amount is released when the shutter means 37 is operated once. Either can be used (it can be said that the dredge method is superior in terms of ease of control). It is also possible to provide a stirring device such as an impeller type in the raw material hopper 24 and regularly hold the raw material urea in a granular or powder state by stirring periodically.

  The mixing tank 25 is provided with a rotary stirring device 38, a water level sensor 39, and a heating means 40. The stirring device 38 is driven by a motor. As shown in FIG. 2, the heating means 40 is disposed near the bottom of the mixing tank 25 in a looped form. Specifically, the heating means 40 can be a sheathed heater that generates heat by electric resistance. Alternatively, the heating means 40 can be constituted by a pipe, and the exhaust gas of the engine 1 or the cooling water that has been warmed by using it can be passed through the heating means 40. Of course, other types of heating means may be employed.

  The adjustment tank 26 is also provided with a stirring device 41, a heating means 42, and a water level sensor 43. The adjustment tank 26 and the water tank 22 are connected by a dilution water pipe 44, and a third pump 45 is interposed in the dilution water pipe 44 (a switching valve is disposed in place of the third pump 45). Is also possible.) Further, the adjustment tank 26 is provided with a concentration sensor 46 for detecting the urea concentration of the urea water.

  Note that the mixing tank 25 and the adjustment tank 26 may have a heat insulating structure. A water level sensor 47 is also provided in the water tank 22, and the first pump 20 automatically operates when the water level falls to the lower limit, and the first pump 20 automatically stops when the water level rises to the upper limit.

(3). Control System / Summary In this embodiment, a processing unit 41 having a central processing unit (CPU), a memory, and the like is provided. The processing device 41 can be manufactured and arranged as a dedicated product, or a commercially available personal computer or workstation can be used.

  A predetermined program is incorporated in the processing device 41, and signals are input and output based on input signals. That is, signals are input to the processing device 41 from the capacity sensor 35 of the raw material hopper 24, the water level sensor 35 of the mixing tank 25, the water level sensor 39 of the adjustment tank 26, and the output sensor 7 of the generator 1. The two fuel tanks 3 and 4 are also provided with capacity sensors (level meters) 42 and 43, and signals are sent from these capacity sensors 42 and 43 to the processing device 41.

  Further, the ship is equipped with an antenna A that receives radio waves from satellites and ground stations, and a position specifying device B that specifies the position of the ship based on the radio waves received by the antenna A. From the position specifying device B, A control signal is sent to the processing device 41. Note that the position specifying device 48 can also be incorporated into the processing device 41.

  The processing device 41 controls the drive of the following. That is, the stirring means 28 and 41 and the heating means 40 and 42 of the second pump 28, the mixing tank 25 and the adjustment tank 26, the shutter means 37, the fourth pump 45 of the dilution water pipe 44, and the opening and closing of the second aqueous solution pipe 31. The drive of the valve 32, the three-way valve 6 of the fuel line 5, the exhaust gas switching valve 17, and the blower 14 is controlled. Of these, the control of the three-way valve 6 in the fuel line 5 is performed based on the position specifying device 48, but this is not related to the present invention and will not be described.

  Now, in this embodiment, urea water is manufactured in the mixing tank 25, this is sent to the adjustment tank 26, urea adjustment is made, and then it sprays on exhaust gas from the spraying port 15, First, urea water Must be supplied without interruption. Therefore, when the lower limit position is detected from the water level sensor 39 of the mixing tank 25, the second pump 28 is driven to supply water from the water tank 22 to the mixing tank 25 until the water level sensor 39 detects the upper limit position, and the shutter 37. The raw material urea is supplied to the mixing tank 25 by a predetermined amount and stirred by the stirring means 38. Feeding of raw material urea and starting of driving of the stirring means 38 may be performed simultaneously with the driving of the second pump 28, or may be before or after.

  When the water level sensor 43 of the adjustment tank 26 detects the lower limit position, the third pump 30 is driven, and when the water level sensor 43 detects the upper limit position, the driving of the third pump 30 is stopped. When the drying means of the raw material hopper 24 and the heating means 40 and 42 of the mixing tank 25 and the adjustment tank 26 are of an electric type, these ON / OFF can be controlled remotely. There is no need to switch while the engine is running.

  Further, the on-off valve 32 of the second aqueous solution pipe 31 is normally kept open, and is closed when the exhaust gas flows through the bypass exhaust pipe 16 and there is no need for NOx purification. By replacing the on-off valve 32 with a flow rate adjusting valve, it is possible to increase or decrease the amount of urea water ejected according to the amount of NOx produced (that is, based on the signal from the concentration sensor of NOx), which is rather preferable.

  It is also possible to arrange the adjustment tank 26 at a position lower than the mixing tank 25 so that the adjustment tank 26 is always kept full. In this case, the third pump 30 and the water level sensor 43 are unnecessary. It is also possible to arrange the adjustment tank 26 at a position lower than the mixing tank 25 and allow the urea water to naturally flow from the mixing tank 25 to the adjustment tank 26. In this case, switching is performed in place of the third pump 30. A valve should be provided.

  If the concentration of NOx in the exhaust gas is high, the amount of urea necessary for the unit amount of the exhaust gas also increases. Therefore, in the mixing tank 25, an aqueous solution having a urea concentration corresponding to the highest possible NOx concentration is manufactured, and based on the signal from the output sensor 7, the urea water has a urea concentration necessary for purification. The fourth pump 45 is driven to take in the dilution water. When the predetermined concentration is reached, the driving of the fourth pump 45 is stopped. When it is necessary to increase the concentration of urea water, the third pump 30 is driven to take in high-concentration urea water.

  The concentration of NOx and the concentration of urea water can be a fine adjustment system that adjusts the urea concentration sensitively in response to slight changes in the concentration of NOx. While dividing into multiple zones such as medium output and high output, urea concentration is also divided into multiple concentration areas such as low concentration, medium concentration and high concentration corresponding to the output zone to change the output zone It can be said that the zone adjustment method of changing the density area in accordance with this is realistic. The exhaust system is also provided with a temperature sensor, and cool air is sent from the blower 14 when the temperature of the exhaust gas rises excessively.

(4). Others The present invention can be embodied in various ways other than the above embodiment. For example, a ship is often equipped with a plurality of engines, but the present invention targets at least one engine. When the mixing tank is disposed at a position lower than the water tank, it is possible to employ a simple switching valve as the water supply means.

It is a typical block diagram which shows embodiment of this invention. (A) is sectional drawing of the mixing tank 25, (B) is a BB view planar sectional view of (A). It is sectional drawing which shows an example of an exhaust gas switching valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Generator 7 Output sensor 8 Main exhaust pipe 9 Exhaust treatment device 10 SCR reduction catalyst 11 Slip catalyst 12 Silencer 15 Spray port 21 Fresh water generator 22 Water tank 24 Raw material hopper 25 Mixing tank 26 Adjustment tank 27 Raw water pipe 28 Second pump as an example of water supply means 29, 31 Aqueous solution pipe 34 Drying means (drying device)
38, 41 Stirring means (stirring device)
40, 42 Heating means (heating device)
39,43 Water level sensor

Claims (5)

An engine, a fresh water generator that desalinates seawater, and a water tank that stores fresh water produced by the fresh water generator are mounted, and a reducing agent aqueous solution is sprayed on a reduction catalyst provided in an exhaust pipe of the engine. As a result, NOx contained in the exhaust gas of the engine is purified, and the aqueous reducing agent solution is mixed with fresh raw material reducing agent such as powder or granules in fresh water. In a ship that is manufactured,
A raw material hopper into which the raw material reducing agent is charged; and a mixing tank with stirring means for mixing the raw material reducing agent discharged from the raw material hopper with fresh water to form an aqueous solution. The water tank and the mixing tank Are connected by raw water pipes, and the mixing tank is connected with an aqueous solution pipe for guiding the reducing agent aqueous solution to the reduction catalyst.
Engine exhaust gas purification system for ships. Further, an output sensor for detecting the output of the engine or a concentration sensor for detecting NOx concentration in the exhaust gas is provided, while the aqueous solution conduit is provided with a reducing agent aqueous solution supplied from the mixing tank with fresh water. An adjustment tank that adjusts the concentration of the reducing agent by dilution is interposed, and the concentration of the reducing agent in the adjustment tank is adjusted based on a signal from the output sensor or the concentration sensor. Water is supplied from the tank,
The exhaust gas purification system of the engine in the ship described in Claim 1. The raw material reducing agent is urea or its content and has a powdery or granular appearance, while the raw material hopper is provided with a drying means, and the mixing tank and the adjustment tank are heated by the heating means. Have
The exhaust gas purification system for an engine in a ship according to claim 1 or 2. The heating means uses the exhaust gas or used cooling water of the engine as a heat source.
An exhaust gas purification system for an engine in a ship according to claim 3. While the mixing tank is provided with a water level sensor, the introduction of the raw material reducing agent from the raw material hopper to the mixing tank is controlled by shutter means, and the raw water pipe is provided with water supply means, And
The water level sensor, the water supply means, and the shutter means are supplied by the water supply means by the lower limit level detection signal from the water level sensor, the water supply means is stopped by the upper limit level detection signal by the water level sensor, It is related that the shutter means is opened and the raw material reducing agent is put in before or after water supply.
The engine exhaust gas purification system in the ship described in any one of Claims 1-4.

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