JP2015206304A - Exhaust emission control system of ship - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a passage changeover valve from being a closed state simultaneously even in a case where the passage changeover valve temporarily breaks down, and surely prevent an exhaust gas passage from being closed in a state where an engine is working, in an exhaust emission control system.SOLUTION: An exhaust emission control system of a ship 1 includes as an exhaust passage 30 of an engine 25 mounted on the ship 1: a main passage 31 communicating with the outside; and a bypass passage 32 branched from the middle part of the main passage 31. In the main passage 31 and the bypass passage 32, fluid operation type changeover valves 37, 38 for opening/closing each passage are arranged. Each of the changeover valves is a normally open type.

Description

  The present invention relates to an exhaust gas purification system that removes harmful components in exhaust gas discharged from a ship-mounted engine.

  Conventionally, in a ship such as a tanker or a transport ship, the amount of electric power consumed by various auxiliary machines, cargo handling devices, lighting, air conditioning and other equipment is enormous. In order to supply electric power to these electric systems, diesel A diesel generator is provided that combines an engine and a generator that generates electricity by driving the diesel engine (see, for example, Patent Document 1). Diesel engines are known to be one of the most energy efficient types of internal combustion engines, and the amount of carbon dioxide contained in exhaust gas per unit output is small. In addition, since a low-quality fuel such as heavy oil can be used, there is an advantage that it is economically excellent.

  Diesel engine exhaust gas contains a large amount of nitrogen oxides, sulfur oxides, particulate matter and the like in addition to carbon dioxide. These are mainly derived from heavy oil, which is a fuel, and are harmful substances that hinder environmental conservation. In particular, nitrogen oxides (hereinafter referred to as NOx) are harmful to human bodies and exhibit strong acidity, and are also considered to cause acid rain. Accordingly, it is understood that a machine that drives a diesel generator, such as a ship, has a very large amount of NOx emission and a large burden on the global environment.

  A selective catalytic reduction method (hereinafter referred to as an SCR method) using urea as a reducing agent has been generalized as a post-treatment means for greatly purifying NOx. In general, the SCR method uses a NOx catalyst having 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. When urea water as a reducing agent aqueous solution is sprayed on the upstream side of the NOx catalyst, the urea water is hydrolyzed by the heat of the exhaust gas to generate ammonia, which acts on NOx as a reducing agent, and converts NOx into harmless nitrogen. Decomposes into water.

JP 2006-341742 A

  In consideration of the global environment, it is necessary to remove NOx in the exhaust gas as much as possible, and it is preferable to regulate it uniformly regardless of the high seas territorial waters. As a result of this, a regulatory sea area will be established for NOx. As described above, since the NOx catalyst has a honeycomb structure, it may be clogged with soot and fine particles in the exhaust gas. Further, the performance of the NOx catalyst is degraded by sulfur components in the exhaust gas and products derived therefrom. In order to extend the life of the NOx catalyst as much as possible to reduce running costs and ensure compliance with regulations in the regulated sea area, it is necessary not to expose the NOx catalyst to exhaust gas during navigation outside the regulated sea area. Conceivable.

Therefore, the applicant of the present application has previously provided a purification casing that accommodates the NOx catalyst in the exhaust path of the engine, and bypasses the exhaust gas from the upstream side of the purification casing in the exhaust path without bypassing the NOx catalyst. Has been proposed (see, for example, JP 2010-71149 A). In this case, exhaust gas is sent to the purification casing side during navigation in the restricted sea area, and exhaust gas is sent to the bypass path side during navigation outside the restricted sea area. Here, there is one that switches a path of exhaust gas by providing a path switching valve on each of the purification casing side and the bypass path side. For this reason, it becomes possible to extend the life of the NOx catalyst, and there is an advantage that the running cost can be reduced and the purification performance can be maintained for a long time.

  However, in the configuration in which a path switching valve is provided on each of the purification casing side and the bypass path side and each path switching valve is operated independently, if the path switching valve fails, both path switching valves are closed simultaneously. This may cause the exhaust gas path to be blocked. If the exhaust gas path is blocked as described above while the engine is operating, there is a problem that the exhaust gas escape path disappears and the engine stops.

  An object of the present invention is to provide a ship exhaust gas purification system which has been improved by examining the above-described present situation.

  According to a first aspect of the present invention, there is provided a ship exhaust gas purification system including a main path communicating with the outside and a bypass path branched from a midway portion of the main path as an exhaust path of a ship-mounted engine. In the gas purification system, a fluid-operated switching valve that opens and closes each path is disposed in the main path and the bypass path, and each switching valve is configured as a normally open type. .

  According to a second aspect of the present invention, in the ship exhaust gas purification system according to the first aspect, when the exhaust gas movement direction is switched to one of the two paths, the fluid supply to the two switching valves is turned off, After the switching valve is opened, fluid is supplied to one switching valve that is closed.

  According to the present invention, since the fluid-operated switching valve that opens and closes each path is configured as a normally open type, the switching valve is used when the exhaust gas path is switched while the engine is operating. Even when the fluid supply to is simultaneously turned off, the main path and the bypass path are not simultaneously closed. Therefore, even if the switching valve fails, the exhaust gas path is not blocked while the engine is operating, and the engine can be prevented from stopping.

It is the whole ship side view. It is II-II front sectional drawing of FIG. It is a front view of a composite casing. It is a side view of a composite casing. It is a rear view of a composite casing. It is side surface sectional drawing of a composite casing. It is a cross-sectional perspective view which shows the internal structure of an exhaust mixer. It is the front view which looked at the exhaust mixer from the exhaust gas moving direction upstream. It is side surface sectional drawing of an exhaust mixer. It is side surface sectional drawing explaining the exhaust gas flow which goes to a composite casing from an exhaust mixer. It is a circuit diagram of the fluid circulation piping which operates a switching valve. It is the schematic explaining the switching operation | movement of an exhaust path.

Hereinafter, an embodiment embodying the present invention will be described with reference to the drawings when applied to a diesel generator mounted on a ship.

(1). Outline of Ship First, an outline of the ship 1 in the first embodiment will be described with reference to FIG. The ship 1 according to the first embodiment is provided in a hull 2, a cabin 3 (bridge) provided on the stern side of the hull 2, a funnel 4 (chimney) arranged behind the cabin 3, and a lower rear part of the hull 2. A propeller 5 and a rudder 6 are provided. In this case, the skeg 8 is integrally formed on the bottom 7 of the stern side. A propeller shaft 9 that rotationally drives the propeller 5 is supported on the skeg 8. A hold 10 is provided on the bow side and the center in the hull 2. An engine room 11 is provided on the stern side in the hull 2.

  In the engine room 11, a main engine 21 (diesel engine in the first embodiment) and a speed reducer 22 that are driving sources of the propeller 5, and a power generation device 23 for supplying electric power to the electrical system in the hull 2 are arranged. doing. The propeller 5 is rotationally driven by the rotational power from the main engine 21 via the speed reducer 22. The interior of the engine room 11 is partitioned vertically by an upper deck 13, a second deck 14, a third deck 15, and an inner bottom plate 16. In the first embodiment, the main engine 21 and the speed reducer 22 are installed on the inner bottom plate 16 at the lowest stage of the engine room 11, and the power generator 23 is installed on the third deck 15 at the middle stage of the engine room 11. Although detailed illustration is omitted, the hold 10 is divided into a plurality of sections.

  As shown in FIG. 2, the power generator 23 includes a plurality of diesel generators 24 (three in the first embodiment). The diesel generator 24 is configured by combining a power generation engine 25 (a diesel engine in the first embodiment) and a power generator 26 that generates power by driving the power generation engine 25. The diesel generator 24 is basically configured to operate efficiently in accordance with the required power amount in the hull 2. For example, all the diesel generators 24 are operated at the time of entry / exit that consumes a large amount of power, and an arbitrary number of diesel generators 24 are operated at the time of berthing where the power consumption is relatively low. The generated power generated by the operation of each generator 26 is supplied to the electrical system in the hull 2. Although not shown in detail, a power transducer is electrically connected to each generator 26. The power transducer detects power generated by each generator 26.

(2). Next, an exhaust system of the power generation device 23 will be described with reference to FIGS. Each power generation engine 25 is connected to an intake path (not shown) for air intake and an exhaust path 30 for exhaust gas discharge. The air taken in through the intake path is sent into each cylinder of the power generation engine 25 (inside the cylinder in the intake stroke). When the compression stroke of each cylinder is completed, the fuel sucked up from the fuel tank is pumped into the combustion chamber of each cylinder by the fuel injection device, and the expansion stroke accompanying the self-ignition combustion of the air-fuel mixture is performed by each combustion chamber.

  The exhaust passage 30 of each power generation engine 25 extends to the funnel 4 and directly communicates with the outside. As described above, since there are three power generation engines 25, there are three exhaust paths 30. The exhaust path 30 of each power generation engine 25 includes a main path 31 extending to the funnel 4, a bypass path 32 branched from a middle portion of the main path 31, and a composite casing communicating with both the main path 31 and the bypass path 32. 33. That is, in the first embodiment, a plurality of power generation engines 25 are mounted, and an exhaust gas purification system including the main path 31, the bypass path 32, the composite casing 33, and the like is associated with each power generation engine 25 on a one-to-one basis. Yes.

The composite casing 33 is made of a heat-resistant metal material and has a substantially cylindrical shape (in the first embodiment, a rectangular tube shape), and is disposed above the third deck 15 on which the power generation engines 25 are disposed. In this case, the composite casing 33 is located on the upper side of the engine room 11 (on the second deck 14 on the upper stage of the engine room 11). On the main path 31 side in the composite casing 33, a NOx catalyst 34 and a slip treatment catalyst 35 (details will be described later) serving as a selective catalyst reduction device that promotes reduction of NOx in the exhaust gas of the power generation engine 25 are accommodated. ing. The bypass path 32 is a path for bypassing the exhaust gas without passing through the NOx catalyst 34 and the slip treatment catalyst 35. The main path 31 and the bypass path 32 are merged at the exhaust outlet portion 42 of the composite casing 33 (the downstream side in the exhaust gas movement direction (hereinafter simply referred to as the downstream side) from the slip treatment catalyst 35). As the selective catalyst reduction device, the NOx catalyst 34 may be used without the slip treatment catalyst 35.

  At the branch portion between the main path 31 and the bypass path 32 outside the composite casing 33, the main side which is a fluid-operated switching valve is used as a path switching member for switching the exhaust gas movement direction between the main path 31 and the bypass path 32. A switching valve 37 and a bypass side switching valve 38 are provided. The main side switching valve 37 and the bypass side switching valve 38 of the present embodiment are configured by a single-acting switching valve. As an example of the fluid-actuated single-acting switching valve, it is conceivable that the main-side switching valve 37 and the bypass-side switching valve 38 are composed of air-actuated butterfly valves. The main side switching valve 37 is provided on the inlet side to the composite casing 33 in the main path 31. The bypass side switching valve 38 is provided on the inlet side to the composite casing 33 in the bypass path 32.

  Next, the structure of the composite casing 33 will be described with reference to FIGS. As described above, the composite casing 33 communicates with both the main path 31 and the bypass path 32. The main path 31 side in the composite casing 33 includes, in order from the upstream side in the exhaust gas movement direction (hereinafter simply referred to as the upstream side), a NOx catalyst 34 that promotes reduction of NOx in the exhaust gas, and an excessively supplied reducing agent. A slip treatment catalyst 35 that promotes an oxidation treatment of (urea water (urea aqueous solution), more specifically, ammonia after hydrolysis) is accommodated in series. Each of the catalysts 34 and 35 has a honeycomb structure composed of a large number of cells partitioned by porous (filterable) partition walls, and has a catalytic metal such as alumina, zirconia, vanadia / titania or zeolite. doing.

The NOx catalyst 34 selectively reduces NOx in the exhaust gas to the main path 31 side in the composite casing 33 by using ammonia generated by hydrolysis of urea water from the urea water injection nozzle 61 described later as a reducing agent. The sent exhaust gas is purified. The slip treatment catalyst 36 oxidizes unreacted (surplus) ammonia flowing out of the NOx catalyst 34 to harmless nitrogen. In this case, on the main path 31 side in the composite casing 33, the following reaction formula:
(NH ₂ ) ₂ CO + H ₂ O → 2NH ₃ + CO ₂ (hydrolysis)
NO + NO ₂ + 2NH ₃ → 2N ₂ + 3H ₂ O (reaction with NOx catalyst 62)
4NH ₃ + 3O ₂ → 2N ₂ + 6H ₂ O (reaction at slip treatment catalyst 63)
Will occur.

  As shown in detail in FIG. 6, both the main path 31 and the bypass path 32 are provided side by side in the composite casing 33. In this case, a partition plate 40 extending along the exhaust gas movement direction is disposed in the composite casing 33. The presence of the partition plate 40 partitions the composite casing 33 into a main path 31 side and a bypass path 32 side. By partitioning the inside of the composite casing 33 with the partition plate 40, when the exhaust gas passes through the bypass path 32, the heat of the exhaust gas is used to warm the NOx catalyst 34 and the slip treatment catalyst 35 on the main path 31 side. Is possible. For this reason, regardless of whether or not the exhaust gas is purified, the NOx catalyst 34 and the slip treatment catalyst 35 can always be warmed up to easily maintain the activated state. When exhaust gas passes through the main-side path 31, warm-up operation is not necessary, so that exhaust gas purification can be performed quickly.

  The upstream end of the partition plate 40 is abutted and fixed to the front inner surface of the exhaust inlet 41 located upstream of the NOx catalyst 62 in the main path 31 side in the composite casing 33. The exhaust inlet 41 on the main path 31 side in the composite casing 33 is formed in a tapered shape (conical shape) that decreases in cross-sectional area toward the upstream side. On the other hand, the downstream end portion of the partition plate 40 is interrupted in the exhaust outlet portion 42 on the downstream side of the slip treatment catalyst 35 in the composite casing 33. For this reason, in the exhaust outlet part 42 of the composite casing 33, the main path 31 side and the bypass path 32 side merge.

  On one side of the composite casing 33, a plurality of jet nozzles 43 serving as jets are attached to the upstream side of the NOx catalyst 34 and the upstream side of the slip treatment catalyst 35. In the first embodiment, three jet nozzles 43 are provided on one side of the composite casing 33 on the upstream side of the NOx catalyst 34, and three jet nozzles 43 are provided on one side of the composite casing 33 on the upstream side of the slip treatment catalyst 35. It is provided on the side. Compressed gas (air) from a gas supply source (not shown) is blown toward the NOx catalyst 34 and the slip treatment catalyst 35 by each blast nozzle 43. By the action of the blow nozzle 43, the dust accumulated on the main path 31 side in the composite casing 33 during use can be forcibly removed.

  A plurality of inspection opening windows 44 (three locations in the first embodiment) are formed on the other side surface of the composite casing 33. Each inspection opening window 44 is formed for the inspection and maintenance of the inside of the composite casing 33, the jet nozzle 43, the NOx catalyst 34, and the slip treatment catalyst 35. Each inspection opening window 44 is normally closed by a lid cover 45 so as to be opened and closed. Each lid cover 45 is detachably fastened to the peripheral edge of the corresponding inspection opening window 44 with a bolt.

  A main side inlet 47 and a bypass side inlet 48 are formed on the front side of the exhaust inlet 41 of the composite casing 33. The main side inlet 47 communicates with the main path 31 in the composite casing 33, and the bypass side inlet 48 communicates with the bypass path 32 in the composite casing 33. A main-side introduction pipe 51 that communicates with the main-side inlet 47 and a bypass-side introduction pipe 52 that communicates with the bypass-side inlet 48 are provided on the front outer surface side of the exhaust inlet 41 of the composite casing 33. The main side introduction pipe 51 and the bypass side introduction pipe 52 are connected to the bifurcated pipe 53 via relay pipes 55 and 56, respectively. In this case, the inlet side of the main relay pipe 55 is fastened to the main outlet part 57 of the bifurcated pipe 53 via a flange. The other end side of the main side relay pipe 55 communicates with the main side introduction pipe 51. An inlet side of the bypass side relay pipe 56 is fastened to the bypass side outlet portion 58 of the bifurcated pipe 53 via a flange. The outlet side of the bypass side relay pipe 56 is fastened with a bypass side introduction pipe 52 via an adjustment pipe 69 having a bellows structure for adjusting the length.

  Although not shown in detail, the inlet 59 of the bifurcated pipe 53 is connected to the upstream side of the main path 31 via a flange. The bifurcated pipe 53 corresponds to a branch portion between the main path 31 and the bypass path 32. A main-side switching valve 37 is provided in the main-side outlet 57 of the bifurcated pipe 53 that communicates with the main path 31 side in the composite casing 33. A bypass-side switching valve 38 is provided in the bypass-side outlet 58 of the bifurcated pipe 53 that communicates with the bypass path 32 in the composite casing 33. On the rear surface side of the exhaust outlet portion 42 of the composite casing 33, an outlet 49 is formed close to the main path 31 side. An exhaust discharge pipe 60 communicating with the outflow port 49 is provided on the rear outer surface side of the exhaust outlet portion 42 of the composite casing 33. The exhaust discharge pipe 60 is connected to the downstream side of the main path 31 via a flange.

Between the main side switching valve 37 and the main side introduction pipe 51 connected to the composite casing 33 in the main path 31, a reducing agent supply device that supplies urea water as a reducing agent to exhaust gas in order from the upstream side. A urea water injection nozzle 61 as a reducing agent injection body and an exhaust mixer 62 for mixing exhaust gas and urea water are arranged. The reducing agent supply device includes a urea water tank (not shown) for storing urea water, a feed pump (not shown) for sucking urea water from the urea water tank, and a urea water injection nozzle 61 provided in the main-side relay pipe 55. It has. The urea water is sent from the urea water tank to the urea water injection nozzle 61 by driving the feed pump, and the urea water is injected from the urea water injection nozzle 61 into the main relay pipe 55 in the form of a mist.

  A nozzle inspection window 63 for inspection and maintenance of the urea water injection nozzle 61 is provided in the vicinity of the urea water injection nozzle 61 in the main side relay pipe 55. The nozzle inspection window 63 is also normally closed with a lid cover 64 so that it can be opened and closed in the same manner as the inspection opening windows 44 described above. The lid cover 64 is detachably fastened to the peripheral edge of the nozzle inspection window 63 with bolts.

  An exhaust mixer 62 is provided between the main side relay pipe 55 and the main side introduction pipe 51. The exhaust mixer 62 is located downstream from the urea water injection nozzle 61 provided in the main-side relay pipe 55 by a predetermined distance. The predetermined distance in this case is a distance necessary for hydrolyzing the urea water injected from the urea water injection nozzle 61 into ammonia in the main-side relay pipe 55. As shown in FIGS. 7 to 10, the exhaust mixer 62 according to the first embodiment includes a cylindrical mixer pipe 71 having the same inner diameter as the main-side relay pipe 55 and the main-side introduction pipe 51, and the mixer pipe 71. A plurality of mixing fins 72 (four in the first embodiment) provided on the inner peripheral side of the, and a shaft core body 73 located at the shaft core of the mixer tube 71. The core body 73 is configured to generate a swirling flow in the exhaust gas passing through the exhaust mixer 62 and the mist-like urea water.

  Each mixing fin 72 is a member for turning the exhaust gas flow into a swirling flow, and is arranged radially on the inner peripheral side of the mixer tube 71 with the shaft core 73 as the center. In this case, the radially inner side end surface of each mixing fin 72 is fixed to the shaft core 73, and the radially outer side end surface of each mixing fin 72 is fixed to the inner peripheral surface of the mixer tube 71. Each mixing fin 72 is located at equal angles along the circumferential direction of the mixer tube 71 (positioned symmetrically about the shaft core 73). The number of mixing fins 72 is not limited to the four in the first embodiment.

  The upstream side and the downstream side of each mixing fin 72 are configured to make a predetermined angle with respect to the exhaust gas movement direction (axial center direction of the mixer tube 71 etc.). That is, each mixing fin 72 is bent in the middle of the exhaust gas movement direction. In this case, each mixing fin 72 is bent so that the angle of the upstream fin plate portion 72a with respect to the exhaust gas movement direction is the inclination angle θ1, and the angle of the downstream fin plate portion 72b with respect to the exhaust gas movement direction is the inclination angle θ2. I am letting. The inclination angle θ2 of the downstream fin plate portion 72b is set larger than the inclination angle θ1 of the upstream fin plate portion 72a. That is, the inclination angles θ1 and θ2 of the fin plate portions 72a and 72b are larger on the downstream side than on the upstream side. In other words, the inclination angles θ1 and θ2 of the fin plate portions 72a and 72b increase continuously or stepwise from the upstream side toward the downstream side.

  The upstream tip portion of the shaft core 73 that supports the radially inner side end surface of each mixing fin 72 has a tapered shape (conical shape) that decreases in cross-sectional area toward the upstream side. Forming. Further, the downstream base end portion of the shaft core 73 is formed in a taper shape (cone shape) having a rear narrowing that reduces the cross-sectional area toward the downstream side. For this reason, the exhaust gas flowing into the vicinity of the shaft core of the mixer tube 71 is guided toward the mixing fins 72 on the radially outer side by the tapered upstream tip portion of the shaft core 73.

  As shown in FIGS. 4 and 5, a main side inlet temperature sensor that detects the temperature of exhaust gas flowing into the main path 31 side in the composite casing 33 is provided in the exhaust path inlet 41 on the main path 31 side of the composite casing 33. 65a is arranged. A bypass side inlet temperature sensor 65 b that detects the temperature of the exhaust gas flowing into the bypass path 32 in the composite casing 33 is disposed in the bypass side relay pipe 56. An outlet temperature sensor 65 c that detects the temperature of the exhaust gas that has passed through the main path 31 side or the bypass path 32 side is disposed in the exhaust discharge pipe 60 of the composite casing 33.

  As shown in FIGS. 3 to 5, a plurality of lifting metal fittings 66 are integrally provided on the upper outer peripheral side of the composite casing 33. In this case, two lifting metal fittings 66 (four in total) are attached to the upper side of the two side surfaces of the composite casing 33 having a substantially rectangular tube shape in parallel with each other. In an assembly factory of the ship 1, for example, the lifting metal fitting 66 group is locked to a hook (not shown) of a chain block, and the composite casing 33 is moved up and down by the chain block. The composite casing 33 can be easily assembled on the second deck 14).

(3). Exhaust path switching operation The main path 31 and the bypass path 32 in each exhaust path 30 are provided with a main side switching valve 37 and a bypass side switching valve 38 as opening and closing members for opening and closing each (in the embodiment, three sets, 6 in total). The main-side switching valve 37 and the bypass-side switching valve 38 have a relationship that when one is opened, the other is closed in order to select a path through which the exhaust gas passes. Further, the main side switching valve 37 and the bypass side switching valve 38 are configured to open and close according to the state of the corresponding power generation engine 25 and the type of fuel used.

  In a state where the bypass side switching valve 38 is closed and the main side switching valve 37 is opened, the exhaust gas sent from the plurality of power generation engines 25 to the main paths 31 in the exhaust stroke after the expansion stroke is transferred to the main paths. After being purified via NOx catalyst 34 and slip treatment catalyst 35 via 31, it is discharged out of ship 1. In a state in which the main side switching valve 37 is closed and the bypass side switching valve 38 is opened, the exhaust gas passes through each bypass path 32 (without passing through the NOx catalyst 34 and the slip treatment catalyst 35) and directly outside the ship 1. To be released.

  Thus, when the main side switching valve 37 and the bypass side switching valve 38 as the opening and closing members for opening and closing the exhaust paths 31 and 32 are provided in the main path 31 and the bypass path 32 in each exhaust path 30, For example, the main switching valve 37 and the bypass switching valve 38 are switched between open and closed states when the exhaust gas purification process is necessary and unnecessary, such as when navigating within the regulated sea area and when navigating outside the regulated sea area. The route through which the exhaust gas passes can be selected as appropriate. Therefore, the exhaust gas can be processed efficiently. For example, when the exhaust gas purification process is unnecessary, the exhaust gas can be guided to the bypass path 32 side that communicates directly with the outside while avoiding the NOx catalyst 34 and the slip treatment catalyst 35. For this reason, a state with good exhaust efficiency can be maintained, and it is possible to avoid a decrease in output of each power generation engine 25. Further, when the exhaust gas purification process is unnecessary, the NOx catalyst 34 and the slip treatment catalyst 35 are not exposed to the exhaust gas, which contributes to extending the life of the NOx catalyst 34 and the slip treatment catalyst 35.

  The main side switching valve 37 and the bypass side switching valve 38 for the power generation engine 25 being stopped are configured so that at least the bypass side switching valve 38 on the bypass path 32 side is closed. For this reason, it is possible to easily and reliably prevent the exhaust gas discharged from the other engine from flowing backward toward the power generation engine 25 that is stopped.

As described above, the main-side switching valve 37 and the bypass-side switching valve 38 are fluid-operated, and are kept open (normally open type) when no fluid is supplied. A main-side valve driver 67 that switches and drives the main-side switching valve 37 and a bypass-side valve driver 68 that switches and drives the bypass-side switching valve 38, each composed of a single-acting pneumatic cylinder, are provided. It has been. The main side valve driver 67 is provided on the outer peripheral side of the main side relay pipe 55 in parallel along the longitudinal direction of the main side relay pipe 55. The bypass side valve driver 68 is provided on the outer peripheral side of the bypass side relay pipe 56 in parallel along the longitudinal direction of the bypass side relay pipe 56.

  The valve drivers 67 and 68 of the main side switching valve 37 and the bypass side switching valve 38 are each connected to a fluid supply source 81 via a fluid circulation pipe 80 as shown in FIG. The fluid supply source 81 is for supplying air (which may be nitrogen gas) which is a compressed fluid for operating the valve drivers 67 and 68 (for operating the main side switching valve 37 and the bypass side switching valve 38). A filter regulator 82, an electromagnetic valve 83 for switching whether or not to supply fluid to the valve drivers 67 and 68, in order from the upstream side, and a closed side in the middle part of the fluid circulation pipe 80 on each of the main side and the bypass side A flow rate adjustment unit 84 having an adjustment unit and an open side adjustment unit is provided. Each electromagnetic valve 83 operates based on control information, and is configured to supply or stop the compressed fluid to the valve drivers 67 and 68 of the corresponding switching valves 37 and 38. Each valve driver 67, 68 is provided with a limit switch 85 for detecting whether each electromagnetic valve 83 is in a fluid supply state or in a fluid stop state. A silencer 86 is connected to 68, and a silencer 87 is connected to each solenoid valve 83.

  When switching the path through which the exhaust gas passes, both the main-side and bypass-side electromagnetic valves 83 are in a fluid supply stop state, and the fluid supply to the main-side switching valve 37 and the bypass-side switching valve 38 is stopped. Since the main-side switching valve 37 and the bypass-side switching valve 38 are normally open as described above, when the fluid supply is stopped, they are driven by both valve drivers 67 and 68 to be opened. Thereafter, the solenoid valve 83 on the side that does not allow the exhaust gas to pass is in a fluid supply state, and the valve on the side to which the fluid is supplied is closed. Here, the solenoid valve 83 on the side where the exhaust gas is desired to pass is still in the fluid supply stop state, and the switching valve is still in the open state. As described above, the path through which the exhaust gas passes is switched. As an example of the operation of the main side switching valve 37 and the bypass side switching valve 38, the main side switching valve is temporarily changed from the state in which the main side switching valve 37 is opened and the bypass side switching valve 38 is closed (see FIG. 12A). 37 and the bypass side switching valve 38 are both opened (see FIG. 12B), and then the bypass side switching valve 38 is opened and the main side switching valve 37 is closed (see FIG. 12C). )become.

  In the above configuration, when the main side switching valve 37 is opened and the bypass side switching valve 38 is closed, the exhaust gas passes through the main path 31. That is, it flows into the main path 31 side in the composite casing 33 via the main side outlet 57, the main side relay pipe 55, the exhaust mixer 62, the main side introduction pipe 51, and the main side inlet 47 of the bifurcated pipe 53, The NOx catalyst 34 and the slip treatment catalyst 35 are passed through for purification treatment.

In this case, the exhaust gas containing the atomized urea water injected from the urea water injection nozzle 61 is guided to the exhaust mixer 62 through the main-side relay pipe 55. As a result of the upstream fin plate portion 72a of each mixing fin 72 changing the exhaust gas movement direction to the direction of the inclination angle θ1, and the downstream fin plate portion 72b further changing the exhaust gas movement direction to the direction of the inclination angle θ2. The exhaust gas containing urea water flows toward the inner peripheral surface of the mixer tube 71 and moves in the circumferential direction along the inner peripheral surface of the mixer tube 71. For this reason, a swirling flow of the exhaust gas is formed at the exhaust inlet 41 on the main path 31 side in the composite casing 33, and the exhaust gas and the urea water are smoothly and efficiently mixed. The exhaust inlet 41 on the main path 31 side in the composite casing 33 has a tapered shape (conical shape) that reduces the cross-sectional area toward the upstream side. The turning diameter becomes large. As a result, the exhaust gas reaches the NOx catalyst 34 on the main path 31 side in the composite casing 33 while being more uniformly mixed with the urea water.

(4). Operation and Effect of First Embodiment According to the above configuration, the engine 25 is operating because the main-side switching valve 37 and the bypass-side switching valve 38 are configured by normally open type single-acting switching valves. Even when the fluid supply is off, such as when the exhaust gas path is switched in the state, both the main path 31 and the bypass path 32 are not simultaneously closed. Therefore, even if the path switching valves 37 and 38 break down, it is possible to prevent both the path switching valves 37 and 38 from being simultaneously closed while the engine 25 is operating.

  In the first embodiment, when switching the path through which the exhaust gas passes from one of the exhaust paths 31 and 32 to the other, the fluid supply to the main side switching valve 37 and the bypass side switching valve 38 is once turned off, The main side switching valve 37 and the bypass side switching valve 38 are once opened, and then fluid is supplied to one single operation switching valve that is closed. Therefore, even if the path switching valves 37 and 38 fail, both the main path 31 and the bypass path 32 are not closed at the same time when the exhaust gas path is switched, and the engine 25 is operating. It is possible to reliably prevent the exhaust gas path from being blocked.

  As described above, since both the path switching valves 37 and 38 can be prevented from being closed simultaneously, the power generation engine 25 is stopped and the power generation by the diesel generator 24 is prevented from being stopped. Electric power can be reliably supplied to the electric system, and for example, various auxiliary machines, cargo handling devices, lighting, air conditioning, and other devices can be reliably prevented from becoming unusable.

(5). In addition, the structure of each part is not limited to embodiment of illustration, A various change is possible in the range which does not deviate from the meaning of this invention. In each of the above-described embodiments, the present invention is applied to the exhaust gas purification system provided in the exhaust path 30 of the power generation engine 25. However, the present invention is not limited to this, for example, the exhaust gas purification system in the exhaust system of the main engine 21. You may apply.

DESCRIPTION OF SYMBOLS 1 Ship 11 Engine room 21 Main engine 22 Reduction gear 23 Electric power generation device 24 Diesel generator 25 Electric power generation engine 26 Generator 30 Exhaust path 31 Main path 32 Bypass path 33 Composite casing 34 NOx catalyst 35 Slip treatment catalyst 37 Main side switching valve 38 Bypass side switching valve 40 Partition plate 61 Urea water injection nozzle (reducing agent injection body)
62 Exhaust mixer 80 Fluid distribution pipe 81 Fluid supply source 82 Filter regulator 83 Solenoid valve 84 Flow rate adjusting unit 85 Limit switch

Claims (2)

In an exhaust gas purification system for a ship provided with a main path communicating with the outside as an exhaust path of an engine for mounting on a ship, and a bypass path branched from a midway part of the main path,
In the main path and the bypass path, a fluid operated switching valve that opens and closes each path is arranged, and each switching valve is configured as a normally open type.
Ship exhaust gas purification system. When the exhaust gas moving direction is switched to one of the two paths, the fluid supply to both switching valves is turned off, the fluid is supplied to one switching valve that is closed after both switching valves are opened. Configured as
The ship exhaust gas purification system according to claim 1.

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