KR102483024B1 - SCR system for ships - Google Patents

Abstract

An SCR system for ships, which is an aspect of the present invention, includes a first injection nozzle for injecting a reducing agent for NOx reduction into exhaust gas, a second injection nozzle for injecting a larger amount of reducing agent than the first injection nozzle into exhaust gas, and any of the above A reactor having a reducing agent supply system for supplying a reducing agent to an injection nozzle, a catalyst layer for reducing NOx in exhaust gas, a first operation mode for reducing NOx emissions to below a regulated value, and lower NOx emissions regulation An operation unit for switchably instructing a second operation mode that reduces the value below the value, and in the case of the first operation mode, supplying the reducing agent at the first flow rate to the first spray nozzle, and in the case of the second operation mode, a more second operation mode. and a control unit for controlling the reducing agent supply system to supply the reducing agent at a flow rate to the second injection nozzle.

Description

SCR system for ships

The present invention relates to a selective catalytic reduction (SCR) system formed in a marine diesel engine, that is, to a marine SCR system.

Conventionally, in the field of marine diesel engines mounted on ships, as a denitrification technology for reducing nitrogen oxides (NOx) in exhaust gas discharged from marine diesel engines, a marine SCR system has been proposed (for example, Patent Document 1, 2). In general, a marine SCR system mixes a reducing agent having an action of reducing NOx with exhaust gas from a marine diesel engine, and reduces NOx emissions by a reduction reaction of NOx in the exhaust gas.

In addition, for the exhaust gas regulations required for marine diesel engines, the first regulation (Tier I), the second regulation (Tier II) and the third regulation (Tier III) are based on Annex VI of the Convention for the Prevention of Marine Pollution of the International Maritime Organization. there is The primary regulation and the secondary regulation regulate NOx emissions from marine diesel engines mounted on ships navigating the global area. The tertiary regulation is a much stricter exhaust gas regulation than the secondary regulation, and regulates NOx emissions from marine diesel engines mounted on ships navigating an ECA (Emission Control Area).

Japanese Patent Publication No. 2017-506716 Japanese Unexamined Patent Publication No. 2015-72015

By the way, the regulation value of NOx discharge|emission in secondary regulation is reduced, for example to 15% or more and 22% or less compared with the primary regulation. These primary regulations and secondary regulations are levels that can be satisfied by performing tuning such as slowing fuel combustion in a combustion chamber in a cylinder with respect to a marine diesel engine. On the other hand, the regulation value of NOx discharge|emission in the 3rd regulation is reduced by 80% or more compared with the 1st regulation, for example. Such a tertiary regulation is a level that is difficult to satisfy only by tuning a marine diesel engine. For this reason, in order to satisfy the tertiary regulation, a marine SCR system having the ability to reduce (denitrate) 80% or more of NOx contained in exhaust gas is applied to a marine diesel engine.

Moreover, in recent years, while satisfying the above-mentioned emission regulation of NOx, it is desired to improve the fuel efficiency (hereinafter, appropriately abbreviated as engine fuel economy) of marine diesel engines. In general, when improvement (reduction) of engine fuel consumption is pursued, NOx emission tends to increase accordingly.

For example, in the tuning of a marine diesel engine, even if NOx emissions can be reduced below the regulated value of the secondary regulation, the engine fuel economy deteriorates, and even if the engine fuel economy is improved, the NOx emissions exceed the regulated value. Excess. That is, in the tuning of marine diesel engines, there is a limit to improving engine fuel efficiency. On the other hand, if the SCR system for ships is used not only in the tertiary regulatory sea area (emission regulation sea area) but also in the secondary regulated sea area (general sea area), even if NOx emissions increase with the improvement of engine fuel efficiency, this increase It can be expected that NOx emissions are reduced below the regulated value of the secondary regulation by the SCR system for ships.

However, marine SCR systems are originally optimized to reduce NOx emissions in order to satisfy tertiary regulations. For this reason, the SCR system for ships is excessive in use to satisfy the secondary regulation, for example, there is a lot of waste such as excessively reducing NOx emissions with respect to the secondary regulations, and the NOx emissions are efficiently reduced. It may be difficult to do.

The present invention has been made in view of the above circumstances, and provides a marine SCR system capable of efficiently reducing NOx emissions in response to a plurality of exhaust gas regulations required for marine diesel engines while pursuing improvement in engine fuel efficiency. aims to do

In order to solve the above problems and achieve the object, a marine SCR system related to the present invention is a first injection for injecting a reducing agent for reducing nitrogen oxides in the exhaust gas to exhaust gas discharged from a marine diesel engine. A nozzle, a second injection nozzle for injecting a larger amount of the reducing agent than the first injection nozzle into the exhaust gas, and a flow rate of the reducing agent injected into the exhaust gas is adjusted, and the reducing agent after the flow rate adjustment is discharged into the first injection nozzle A reactor having a reducing agent supply system for supplying a spray nozzle or the second spray nozzle, a catalyst layer that causes a reduction reaction of nitrogen oxide in contact with the exhaust gas into which the reducing agent is injected, and a first exhaust gas regulation A first operation mode for reducing the amount of nitrogen oxide discharged to below a limit value of the first exhaust gas regulation, and a second operation mode for reducing the amount of nitrogen oxide discharge to below a regulation value of the second exhaust gas regulation lower than the regulation value of the first exhaust gas regulation. an operation unit for instructing to be able to switch, and when the first operation mode is instructed, the reducing agent is adjusted to a first flow rate required to satisfy the first exhaust gas regulation and supplied to the first injection nozzle. A reducing agent supply system is controlled, and when the second operation mode is indicated, the reducing agent is adjusted to a second flow rate required to satisfy the second exhaust gas regulation and higher than the first flow rate, so that the second injection nozzle It is characterized by having a control unit for controlling the reducing agent supply system so as to supply to.

In addition, in the SCR system for ships according to the present invention, in the above invention, the reducing agent supply system comprises: a first control valve for adjusting the flow rate of the reducing agent injected into the exhaust gas from the first injection nozzle; and a second control valve having a flow rate adjustment range wider than that of the control valve and adjusting the flow rate of the reducing agent injected into the exhaust gas from the second injection nozzle.

In addition, the marine SCR system according to the present invention includes a compressed air supply system for supplying compressed air to the first injection nozzle or the second injection nozzle, and the control unit operates in the first operation mode When is indicated, the compressed air supply system is controlled to supply the compressed air having a predetermined flow rate or pressure to the first spray nozzle, and when the second operation mode is indicated, the flow rate or pressure higher than the predetermined flow rate or pressure is indicated. It is characterized in that the compressed air supply system is controlled to supply the compressed air at a flow rate or high pressure to the second injection nozzle.

Further, in the SCR system for ships according to the present invention, in the above invention, the reactor is characterized by having a plurality of stages of the catalyst layer from the inlet side to the outlet side of the exhaust gas in the reactor.

In addition, in the SCR system for ships according to the present invention, in the above-mentioned invention, among the catalyst layers of a plurality of stages formed in the reactor, the catalyst layer at the first stage from the inlet side of the exhaust gas in the reactor, the second injection nozzle An inlet pipe for introducing the exhaust gas containing the reducing agent or the exhaust gas without the reducing agent injected from the inlet pipe, and the second catalyst layer and subsequent catalyst layers located at the rear end of the first catalyst layer, a distribution pipe for distributing the exhaust gas containing the reducing agent injected from the first spray nozzle, and an exhaust gas distribution system communicating with the inlet pipe and the distribution tube and circulating the exhaust gas toward the reactor wherein, when the first operation mode is instructed, the controller circulates the exhaust gas in a state not containing the reducing agent into the inlet pipe and removes the reducing agent injected from the first injection nozzle. The exhaust gas distribution system is controlled so that the exhaust gas containing the exhaust gas is circulated within the distribution pipe, and when the second operation mode is instructed, the reducing agent injected from the second injection nozzle is contained. It is characterized in that the exhaust gas circulation system is controlled so as to flow the exhaust gas into the inlet pipe.

In addition, in the SCR system for ships according to the present invention, in the above invention, a first mixer having the first injection nozzle and mixing the reducing agent injected from the first injection nozzle with the exhaust gas; and a second mixer having a nozzle and mixing the reducing agent injected from the second injection nozzle with the exhaust gas.

In addition, the marine SCR system according to the present invention, in the above invention, has the first injection nozzle and the second injection nozzle, and the reducing agent and the exhaust gas injected from the first injection nozzle or the second injection nozzle It is characterized by having a mixer for mixing.

In addition, in the SCR system for ships according to the present invention, in the above invention, the first injection nozzle is disposed at the rear end of the second injection nozzle in the direction from the inlet side to the outlet side of the exhaust gas in the mixer. characterized by being

According to the marine SCR system according to the present invention, it is possible to achieve an effect of efficiently reducing NOx emissions in response to a plurality of exhaust gas regulations required for marine diesel engines while pursuing improvement in engine fuel efficiency.

1 is a schematic diagram showing an example of a configuration of an SCR system for ships according to Embodiment 1 of the present invention.
2 is a diagram for explaining the operation of the SCR system for ships according to the first embodiment of the present invention for each operation mode.
Fig. 3 is a schematic diagram showing a configuration example of an SCR system for ships according to Embodiment 2 of the present invention.
4 is a diagram for explaining the operation of the SCR system for ships according to the second embodiment of the present invention for each operation mode.
Fig. 5 is a schematic diagram showing an example of a configuration of an SCR system for ships according to Embodiment 3 of the present invention.
6 is a diagram for explaining the operation of the SCR system for ships according to the third embodiment of the present invention for each operation mode.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, with reference to the accompanying drawings, preferred embodiments of the SCR system for ships related to the present invention will be described in detail. In addition, this invention is not limited by this embodiment. In addition, it is necessary to note that the drawing is typical, and that the relationship between the dimensions of each element, the ratio of each element, and the like may be different from those in reality. Even in each other of the drawings, there are cases where there are parts in which the relation or ratio of dimensions to each other is different. Moreover, in each figure, the same code|symbol is attached|subjected to the same component part.

(Embodiment 1)

The configuration of the SCR system for ships according to Embodiment 1 of the present invention will be described. 1 is a schematic diagram showing an example of a configuration of an SCR system for ships according to Embodiment 1 of the present invention. The ship SCR system 10 according to the first embodiment reduces NOx in exhaust gas from the ship diesel engine 100 mounted on the ship, and as shown in FIG. 1, the small injection nozzle 1, the large Injection nozzle (2), exhaust gas distribution system (3), reducing agent supply system (4), compressed air supply system (5), SCR reactor (6), operation unit (8), and control unit (9) to provide

In Fig. 1, piping for fluids such as exhaust gas or reducing agent is indicated by solid arrows. Electrical signal lines are indicated by dashed-dotted lines. This is the same also in other drawings. In addition, exhaust gas means exhaust gas discharged from the marine diesel engine 100 unless otherwise specified.

The small injection nozzle 1 and the large injection nozzle 2 are injection nozzles for injecting a reducing agent for reducing NOx in the exhaust gas into the exhaust gas discharged from the marine diesel engine 100, respectively. The small injection nozzle 1 (an example of the first injection nozzle) is optimally set as a injection nozzle for injecting a reducing agent into the exhaust gas in order to satisfy the first exhaust gas regulation that regulates the amount of NOx in the exhaust gas. Specifically, in the present Embodiment 1, the small injection nozzle 1 is configured to be able to inject a smaller amount of the reducing agent into the exhaust gas than the large injection nozzle 2. On the other hand, the large injection nozzle 2 (an example of the second injection nozzle) injects a reducing agent into the exhaust gas in order to satisfy the second exhaust gas regulation that strictly regulates the amount of NOx in the exhaust gas more strongly than the first exhaust gas regulation. It is optimally set as a spray nozzle for Specifically, in the first embodiment, the large injection nozzle 2 is configured to inject a larger amount of reducing agent into the exhaust gas than the small injection nozzle 1. For example, the large injection nozzle 2 is constituted by a nozzle having a larger diameter than the small injection nozzle 1 .

Further, as the first exhaust gas regulation, for example, an exhaust gas regulation (secondary regulation, etc.) applied to ships navigating in the general sea area is exemplified. Examples of the second exhaust gas regulations include exhaust gas regulations (tertiary regulations, etc.) applied to ships navigating the emission control sea area.

The exhaust gas distribution system 3 circulates the exhaust gas from the marine diesel engine 100 . As shown in FIG. 1, the exhaust gas distribution system 3 includes a mixer 3a, an exhaust pipe 11a, an inlet pipe 11b, an outlet pipe 11c, a bypass pipe 12, A bypass valve 13 is provided.

The mixer 3a mixes the reducing agent injected from the small injection nozzle 1 or the large injection nozzle 2 and the exhaust gas from the marine diesel engine 100. In the first embodiment, as shown in FIG. 1 , in the mixer 3a, an exhaust pipe 11a is connected to the inlet side of the exhaust gas, and an inlet pipe 11b is connected to the outlet side of the exhaust gas. Moreover, the mixer 3a has the small injection nozzle 1 and the large injection nozzle 2 inside. For example, the small injection nozzle 1 is disposed at the rear end of the large injection nozzle 2 in the direction from the inlet side of the exhaust gas to the outlet side in the mixer 3a. The mixer 3a mixes the exhaust gas introduced from the exhaust pipe 11a with the reducing agent injected from the small injection nozzle 1 or the large injection nozzle 2, while mixing the exhaust gas containing the reducing agent into the SCR reactor It is made to flow in the inlet tube 11b toward (6).

The exhaust pipe 11a is a pipe for distributing the exhaust gas discharged from the marine diesel engine 100 toward the mixer 3a. The exhaust pipe 11a is configured such that the inlet end passes through the marine diesel engine 100. The outlet end of the exhaust pipe 11a is connected to the inlet end of the mixer 3a. As the exhaust gas flowing into the mixer 3a from the marine diesel engine 100 through the exhaust pipe 11a, for example, the exhaust gas discharged from the exhaust manifold (not shown) of the marine diesel engine 100 (high pressure state) exhaust gas), exhaust gas used for rotation of a supercharger turbine (not shown) of the marine diesel engine 100 (exhaust gas in a low pressure state), and the like.

The inlet pipe 11b is a pipe for introducing the exhaust gas from which the reducing agent is injected into the SCR reactor 6. As shown in Fig. 1, the inlet pipe 11b has an inlet end connected to the outlet of the mixer 3a and an outlet end connected to the inlet end of the SCR reactor 6. The inlet pipe 11b introduces the exhaust gas containing the reducing agent injected from the small injection nozzle 1 or the large injection nozzle 2 from the outlet of the mixer 3a to the inlet of the SCR reactor 6.

The outlet pipe 11c is a pipe for discharging the NOx-reduced exhaust gas from the SCR reactor 6. As shown in Fig. 1, the inlet end of the outlet pipe 11c is connected to the outlet end of the SCR reactor 6. Moreover, the exit pipe 11c is comprised so that the exit end may pass through the stack of a ship, or a waste heat recovery apparatus (all not shown), such as a boiler. The outlet pipe 11c passes the exhaust gas, of which NOx has been reduced by the SCR reactor 6, toward a chimney or a waste heat recovery device.

The bypass pipe 12 bypasses the SCR reactor 6 in which pressure loss is occurring and circulates the exhaust gas to the chimney side or the waste heat recovery device side (hereinafter collectively referred to as the "discharge/recovery side" as appropriate). It is a pipe to do it. As shown in Fig. 1, the bypass pipe 12 has an inlet end connected to the midway portion of the exhaust pipe 11a and an outlet end connected to the midway portion of the outlet pipe 11c. In addition, as shown in FIG. 1 , a bypass valve 13 is formed in the bypass pipe 12 . The bypass valve 13 is a drive valve that opens or closes the bypass pipe 12 . When the bypass valve 13 opens the bypass pipe 12, the bypass pipe 12 passes from the exhaust pipe 11a to the SCR reactor 6, etc. (in the first embodiment, the mixer 3a and the SCR Exhaust gas is passed through the outlet pipe 11c bypassing the reactor 6). On the other hand, when the bypass valve 13 closes the bypass pipe 12, the bypass pipe 12 stops the flow of the exhaust gas bypassing the SCR reactor 6 or the like.

The reducing agent supply system 4 adjusts the flow rate of the reducing agent injected into the exhaust gas, and supplies the reducing agent after adjusting the flow rate to the small injection nozzle 1 or the large injection nozzle 2. As shown in FIG. 1, the reducing agent supply system 4 includes a reducing agent supply source 4a, a small control valve 4b, a large control valve 4c, a flow sensor 4d, an on-off valve 4e, 4f) and supply pipes 14a, 14d and 14g.

Although not particularly shown, the reducing agent supply source 4a includes a tank for storing the reducing agent, a pump for pumping the reducing agent from the tank, and a pressure adjusting unit for adjusting the pressure of the reducing agent. The reducing agent supply source 4a adjusts the liquid reducing agent to a predetermined pressure and supplies it to the small spray nozzle 1 side or the large spray nozzle 2 side. Moreover, as a reducing agent supplied from the reducing agent supply source 4a, urea water, ammonia water, etc. are mentioned, for example.

The small control valve 4b and the large control valve 4c are control valves for adjusting the flow rate of the reducing agent injected from the small injection nozzle 1 or the large injection nozzle 2 into the exhaust gas. The small control valve 4b (an example of the first control valve) is optimally set as a control valve for adjusting the flow rate (injection amount) of the reducing agent injected into the exhaust gas in order to satisfy the first exhaust gas regulation. Specifically, the small control valve 4b is constituted by a control valve having a flow rate adjustment range narrower than that of the large control valve 4c, and the flow rate adjustment unit of the small control valve 4b is the large control valve 4c smaller than On the other hand, the control valve 4c (an example of the second control valve) is optimally set as a control valve for adjusting the flow rate of the reducing agent injected into the exhaust gas in order to satisfy the second exhaust gas regulation. Specifically, the large control valve 4c is constituted by a control valve having a flow rate adjustment range wider than that of the small control valve 4b, and the flow rate adjustment unit of the large control valve 4c is the small control valve 4b bigger than In the present Embodiment 1, the small control valve 4b adjusts the flow rate of the reducing agent injected from the small injection nozzle 1 to the exhaust gas. The control valve 4c adjusts the flow rate of the reducing agent injected from the large injection nozzle 2 to the exhaust gas.

The flow sensor 4d is a sensor for detecting the flow rate of the reducing agent injected from the small injection nozzle 1 or the large injection nozzle 2 into the exhaust gas. As shown in FIG. 1 , the flow sensor 4d is disposed at the rear end of the small control valve 4b and the large control valve 4c. In the present Embodiment 1, the flow sensor 4d detects the flow rate of the reducing agent adjusted by the small control valve 4b or the large control valve 4c, and an electric signal indicating the result of detecting the flow rate of the reducing agent each time (Hereafter appropriately referred to as a reducing agent flow rate detection signal) is transmitted to the control unit 9.

The supply pipe 14a is a pipe that communicates the reducing agent supply source 4a and the small control valve 4b and the large control valve 4c. As shown in Fig. 1, the inlet end of the supply pipe 14a is connected to the reducing agent supply source 4a. Further, the supply pipe 14a is configured to branch into two branch pipes 14b and 14c from the inlet end toward the outlet end. One branch pipe 14b of the supply pipe 14a is connected to the inlet side end of the small control valve 4b. The other branch pipe 14c of the supply pipe 14a is connected to the inlet side end of the control valve 4c.

Moreover, the supply pipe 14d is a pipe which communicates the small control valve 4b and the large control valve 4c with the flow sensor 4d. As shown in Fig. 1, the outlet end of the supply pipe 14d is connected to the inlet end of the flow sensor 4d. Further, the supply pipe 14d is configured to branch into two branch pipes 14e and 14f from the outlet end toward the inlet end. One branch pipe 14e of the supply pipe 14d is connected to the exit end of the small control valve 4b. The branch pipe 14f on the other side of the supply pipe 14a is connected to the outlet end of the control valve 4c.

Moreover, the supply pipe 14g is a pipe which communicates the flow rate sensor 4d and the small injection nozzle 1 and the large injection nozzle 2. As shown in Fig. 1, the inlet end of the supply pipe 14g is connected to the outlet end of the flow sensor 4d. Further, the supply pipe 14g is configured to branch into two branch pipes 14h and 14i from the inlet end toward the outlet end. One branch pipe 14h of the supply pipe 14g is connected to the small injection nozzle 1. The other branch pipe 14i of the supply pipe 14g is connected to the large injection nozzle 2.

As shown in FIG. 1, on each branch pipe 14h, 14i of this supply pipe 14g, on-off valves 4e, 4f are formed, respectively. The on-off valve 4e is a drive valve that opens or closes the branch pipe 14h leading to the small injection nozzle 1. The on-off valve 4f is a drive valve that opens or closes the branch pipe 14i leading to the large injection nozzle 2. When a reducing agent is injected into the exhaust gas from the small injection nozzle 1, the on-off valve 4e opens the branch pipe 14h and the on-off valve 4f closes the branch pipe 14i. When a reducing agent is injected into the exhaust gas from the large injection nozzle 2, the on-off valve 4e closes the branch pipe 14h and the on-off valve 4f opens the branch pipe 14i.

The compressed air supply system 5 supplies compressed air to the small injection nozzle 1 or the large injection nozzle 2 . As shown in FIG. 1 , the compressed air supply system 5 includes a compressed air supply source 5a, on-off valves 5b and 5c, and an air supply pipe 15a.

The compressed air supply source 5a is constituted by an air cylinder or the like. The compressed air supply source 5a supplies compressed air for spraying (specifically spraying) the reducing agent into the exhaust gas to the small injection nozzle 1 or the large injection nozzle 2 via the air supply pipe 15a.

The air supply pipe 15a is a pipe that communicates the compressed air supply source 5a and the small injection nozzle 1 and the large injection nozzle 2. As shown in Fig. 1, the inlet end of the air supply pipe 15a is connected to the outlet end of the compressed air supply source 5a. Further, the air supply pipe 15a is configured to branch into two branch pipes 15b and 15c from the inlet end toward the outlet end. One branch pipe 15b of the air supply pipe 15a is connected to the small injection nozzle 1. The other branch pipe 15c of the air supply pipe 15a is connected to the large injection nozzle 2.

In addition, as shown in Fig. 1, orifice portions 15d and 15e are formed in each branch pipe 15b and 15c of the air supply pipe 15a, respectively. The orifice portions 15d and 15e adjust the flow rate or pressure of the compressed air in the respective branch pipes 15b and 15c. The orifice section 15d is optimally set to adjust the flow rate or pressure of compressed air for injecting the reducing agent into the exhaust gas in order to satisfy the first exhaust gas regulation. The orifice portion 15e is optimally set to adjust the flow rate or pressure of compressed air for injecting the reducing agent into the exhaust gas in order to satisfy the second exhaust gas regulation. Specifically, the orifice portion 15d of the branch pipe 15b communicating with the small injection nozzle 1 is configured to have a narrower opening than the orifice portion 15e of the branch pipe 15c communicating with the large injection nozzle 2. do. That is, the flow rate or pressure of the compressed air in the branch pipe 15b in which the orifice portion 15d with a narrow opening is formed is smaller than the flow rate or pressure of compressed air in the branch pipe 15c in which the orifice portion 15e with a wide opening is formed. is adjusted to Also, the orifice portions 15d and 15e may be pressure reducing valves.

Moreover, as shown in FIG. 1, in each branch pipe 15b, 15c of this air supply pipe 15a, on-off valve 5b, 5c is provided, respectively. The on-off valve 5b is a drive valve that opens or closes the branch pipe 15b leading to the small injection nozzle 1. The on-off valve 5c is a drive valve that opens or closes the branch pipe 15c leading to the large injection nozzle 2. When compressed air for spraying the reducing agent is supplied to the small injection nozzle 1, the on-off valve 5b opens the branch pipe 15b and the on-off valve 5c closes the branch pipe 15c. When compressed air for spraying the reducing agent is supplied to the large injection nozzle 2, the on-off valve 5b closes the branch pipe 15b and the on-off valve 5c opens the branch pipe 15c.

The SCR reactor 6 is a reactor for reducing (denitrating) NOx by a reduction reaction of NOx in exhaust gas. As shown in FIG. 1, the SCR reactor 6 is an example of a catalyst layer that causes a reduction reaction of NOx in contact with the exhaust gas into which the reducing agent is injected, and includes a plurality of stages (three stages in the first embodiment) of the catalyst layer ( 6a, 6b, 6c). Further, in the SCR reactor 6, an inlet pipe 11b is connected to the inlet side of the exhaust gas, and an outlet pipe 11c is connected to the outlet side of the exhaust gas. Catalyst layers 6a, 6b, and 6c are disposed inside the SCR reactor 6 while being separated from each other from the inlet side of the exhaust gas to the outlet side in the SCR reactor 6. In the present Embodiment 1, the catalyst layer 6a is the first catalyst layer from the inlet side of the exhaust gas in the SCR reactor 6 (on the inlet pipe 11b side). The catalyst layer 6b is a second stage catalyst layer located at the rear stage of the catalyst layer 6a. The catalyst layer 6c is the third catalyst layer (the last stage in FIG. 1) located at the rear stage of the catalyst layer 6b.

In addition, as shown in Fig. 1, a differential pressure gauge 7 is provided in the SCR reactor 6. The differential pressure gauge 7 measures the differential pressure between the internal pressure on the inlet side and the internal pressure on the outlet side of the exhaust gas in the SCR reactor 6 . The differential pressure gauge 7 continuously or intermittently measures the differential pressure along time series, and transmits an electrical signal indicating the measurement result of the differential pressure (hereinafter appropriately referred to as a differential pressure measurement signal) to the control unit 9 each time. This differential pressure gauge 7 is used to determine whether or not a pressure loss equal to or greater than a predetermined value has occurred in the SCR reactor 6. In addition, the pressure loss of the SCR reactor 6 is determined by the internal pressure at the inlet side of the SCR reactor 6 (for example, the internal pressure at the front end of the first stage catalyst layer 6a) , 6c) (particularly, the catalyst layer 6a) is a phenomenon in which the internal pressure is increased compared to the internal pressure of the outlet side due to clogging or the like. In particular, when the pressure loss of the SCR reactor 6 is more than a prescribed value (for example, the differential pressure is more than a prescribed value), the internal pressure on the inlet side of the SCR reactor 6 is excessive compared to the internal pressure on the outlet side. .

The operation unit 8 is for operating the operation mode of the SCR system 10 for ships. In the first embodiment, the operation unit 8 sets the operation mode of the marine SCR system 10 to a low-denitrification SCR operation mode (an example of the first operation mode) and a high-denitrification SCR operation mode (an example of the second operation mode). It is configured to be able to switch to and operate. The operation unit 8 transmits a driving mode instruction signal to the control unit 9 according to the operator's operation. In this way, the operation unit 8 instructs the control unit 9 to be able to switch between the low-denitrification SCR operation mode and the high-denitrification SCR operation mode of the marine SCR system 10 .

Here, the low denitrification SCR operation mode is an operation mode for reducing the amount of NOx in the exhaust gas below the regulated value of the first exhaust gas regulation. The high denitrification SCR operation mode is an operation mode for reducing the amount of NOx in the exhaust gas below the regulation value of the second exhaust gas regulation, which is lower than the regulation value of the first exhaust gas regulation.

The control unit 9 controls each operation of the exhaust gas distribution system 3 for reducing NOx in the exhaust gas, the reducing agent supply system 4 and the compressed air supply system 5 in the operation mode of the SCR system 10 for ships. very controlled In detail, when the low denitrification SCR operation mode is instructed, the control unit 9 adjusts the reducing agent to a first flow rate required to satisfy the first exhaust gas regulation and supplies the reducing agent to the small injection nozzle 1 so as to supply the reducing agent. Control system (4). When the high denitrification SCR operation mode is instructed, the control unit 9 adjusts the reducing agent to a second flow rate necessary to satisfy the second exhaust gas regulation and is higher than the first flow rate, and supplies it to the large injection nozzle 2. , to control the reducing agent supply system (4). Also, when the low denitrification SCR operation mode is instructed, the controller 9 controls the compressed air supply system 5 to supply compressed air at a predetermined flow rate or pressure to the small injection nozzle 1 . When the high denitrification SCR operation mode is instructed, the control unit 9 supplies the large injection nozzle 2 with compressed air having a flow rate higher than the predetermined flow rate or a pressure higher than the predetermined pressure, so as to supply the compressed air supply system 5 ) to control.

In addition, the control unit 9 determines the degree of pressure loss of the SCR reactor 6 based on the differential pressure measurement signal from the differential pressure gauge 7 regardless of the operation mode of the marine SCR system 10 . When the pressure loss of the SCR reactor 6 is less than a specified value, the controller 9 controls the exhaust gas distribution system 3 so that the exhaust gas containing the injected reducing agent flows through the SCR reactor 6 . In this case, the controller 9 controls the bypass valve 13 to close. When a pressure loss equal to or greater than a prescribed value occurs in the SCR reactor 6, the controller 9 controls the exhaust gas distribution system 3 so that the exhaust gas bypasses the SCR reactor 6 and flows. In this case, the controller 9 controls the bypass valve 13 to open. Thereby, the exhaust gas discharged from the marine diesel engine 100 passes through the inside of the bypass pipe 12 and flows into the outlet pipe 11c.

Next, the operation of the marine SCR system 10 according to Embodiment 1 of the present invention will be described. 2 is a diagram for explaining the operation of the SCR system for ships according to the first embodiment of the present invention for each operation mode. Below, the exhaust gas regulation of the general sea area (secondary regulation) is exemplified as the first exhaust gas regulation, and the exhaust gas regulation (tertiary regulation) of the emission regulation sea area is exemplified as the second exhaust gas regulation. With reference to, the operation of the SCR system 10 for ships will be described for each operation mode.

In the general sea area, the marine SCR system 10 reduces the amount of NOx emitted from the exhaust gas discharged from the marine diesel engine 100 to a value equal to or less than the secondary regulation. In this case, the marine SCR system 10 performs denitrification of NOx in the exhaust gas in the low denitrification SCR operation mode.

In detail, the operation unit 8 transmits an instruction signal instructing the low-denitrification SCR operation mode to the control unit 9 according to an operator's operation, thereby instructing the control unit 9 to perform the low-denitization SCR operation mode. . When the low denitrification SCR operation mode is instructed, the control unit 9 exhausts the reducing agent at the flow rate (ie, the first flow rate) required to reduce the amount of NOx discharged to below the regulated value of the secondary regulation, The exhaust gas distribution system 3, the reducing agent supply system 4, and the compressed air supply system 5 are controlled so that the gas is injected.

For example, in the low denitrification SCR operation mode, the control unit 9 performs the following control for the reducing agent supply system 4. That is, the controller 9 controls the reducing agent supply source 4a to deliver the reducing agent at a predetermined pressure. In addition, the controller 9 includes a control valve 4c for adjusting the flow rate of the reducing agent injected from the large injection nozzle 2 and a branch pipe 14i of the supply pipe 14g leading to the large injection nozzle 2. is controlled to close the on-off valve 4f. On the other hand, the controller 9 controls to open the on-off valve 4e of the branch pipe 14h of the supply pipe 14g leading to the small injection nozzle 1. In addition, the controller 9 controls the opening of the control valve 4b according to the load of the marine diesel engine 100 (hereinafter referred to as engine load), thereby reducing the flow rate of the reducing agent to the first flow rate. Control. At this time, the control unit 9 acquires a reducing agent flow rate detection signal from the flow sensor 4d, and based on the acquired reducing agent flow rate detection signal, performs feedback control so that the flow rate of the reducing agent becomes the first flow rate. In addition, an engine load is computable based on the number of engine revolutions per unit time of the marine diesel engine 100 and the amount of fuel injection per cycle, for example.

Further, in parallel with the control of the reducing agent supply system 4 described above, the control unit 9 performs control of the compressed air supply system 5 as shown below. That is, the controller 9 controls to open the on-off valve 5b of the branch pipe 15b of the air supply pipe 15a communicating with the small injection nozzle 1, and opens the air supply pipe communicating with the large injection nozzle 2 ( The on-off valve 5c of the branch pipe 15c of 15a) is controlled to close. In addition, the control unit 9 judges that the pressure loss of the SCR reactor 6 does not exceed a specified value in the exhaust gas distribution system 3 based on the differential pressure measurement signal from the differential pressure gauge 7, while by The pass valve 13 is controlled to close.

As described above, the controller 9 controls the exhaust gas distribution system 3, the reducing agent supply system 4, and the compressed air supply system 5, so that NOx emissions in the exhaust gas can be reduced in the low-denitization SCR operation mode. Optimum denitrification of NOx is performed to reduce it below the regulated value of the secondary regulation.

Specifically, as shown in FIG. 2 , in the low denitrification SCR operation mode, the reducing agent L1 sent from the reducing agent supply source 4a to the supply pipe 14a passes through the branch pipe 14b to the control valve 4b ) is reached. The small control valve 4b adjusts (fine-adjusts) the flow rate of the reducing agent L1 to the said 1st flow rate by controlling the opening degree by the control part 9. The reducing agent L1 (hereinafter, referred to as the reducing agent L2) adjusted to the first flow rate by the extinguishing control valve 4b passes from the extinguishing control valve 4b through the branch pipe 14e of the supply pipe 14d. After passing through the flow sensor 4d, it is supplied into the small injection nozzle 1 via the branch pipe 14h of the supply pipe 14g. In parallel with this, the compressed air G11 sent from the compressed air supply source 5a to the air supply pipe 15a reaches the orifice section 15d via the branch pipe 15b. The orifice portion 15d adjusts the flow rate or pressure of the compressed air G11 to a flow rate or pressure suitable for jetting (specifically, spraying) of the reducing agent from the small jet nozzle 1. Compressed air G11 (hereinafter referred to as compressed air G12) whose flow rate or pressure has been adjusted in this way is supplied into the small jet nozzle 1 via the branch pipe 15b. The small injection nozzle 1 injects the reducing agent L2 into the mixer 3a by the action of the compressed air G12.

Exhaust gas G1 from the marine diesel engine 100 flows into the mixer 3a through the exhaust pipe 11a. In the mixer 3a, the exhaust gas G1 flowing in from the exhaust pipe 11a and the reducing agent L2 injected from the small injection nozzle 1 are mixed with each other. For example, when the reducing agent L2 is urea water, the urea water atomized by injection is mixed with the exhaust gas G1 and is changed into ammonia by the heat of the exhaust gas G1. The exhaust gas G1 from which the reducing agent L2 has been injected in this way, that is, the exhaust gas G2 in a state containing the injected reducing agent L2 passes from the mixer 3a through the inlet pipe 11b to the SCR reactor ( 6) is introduced within. In the SCR reactor 6, the exhaust gas G2 flows toward the outlet of the SCR reactor 6 while sequentially contacting the plurality of catalyst layers 6a, 6b, and 6c. At this time, the SCR reactor 6 advances the NOx reduction reaction in the exhaust gas G2 by the catalytic action in each of the catalyst layers 6a, 6b, and 6c. In this way, the SCR reactor 6 denitrates NOx in the exhaust gas G2. Due to this denitrification, the amount of NOx discharged in the exhaust gas G2 is reduced below the regulation value of the secondary regulation. This exhaust gas G2 is discharged from the SCR reactor 6 to the discharge/recovery side through the outlet pipe 11c.

On the other hand, in the emission control sea area, the marine SCR system 10 reduces the amount of NOx in the exhaust gas discharged from the marine diesel engine 100 below the regulated value of the tertiary regulation. In this case, the marine SCR system 10 performs denitrification of NOx in the exhaust gas in the high denitrification SCR operation mode.

In detail, the operation unit 8 transmits an instruction signal instructing the high-denitization SCR operation mode to the control unit 9 according to the operator's operation, thereby instructing the control unit 9 to the high-denitization SCR operation mode. . When the high denitrification SCR operation mode is instructed, the controller 9 exhausts the reducing agent from the large injection nozzle 2 at a flow rate (ie, the second flow rate) necessary to reduce the amount of NOx discharged to below the regulated value of the tertiary regulation. The exhaust gas distribution system 3, the reducing agent supply system 4, and the compressed air supply system 5 are controlled so that the gas is injected.

For example, in the high denitrification SCR operation mode, the controller 9 controls the reducing agent supply system 4 as follows. That is, the controller 9 controls the reducing agent supply source 4a to deliver the reducing agent at a predetermined pressure. In addition, the controller 9 includes a small control valve 4b for adjusting the flow rate of the reducing agent injected from the small injection nozzle 1 and a branch pipe 14h of the supply pipe 14g leading to the small injection nozzle 1 is controlled to close the on-off valve 4e. On the other hand, the controller 9 controls to open the on-off valve 4f of the branch pipe 14i of the supply pipe 14g leading to the large injection nozzle 2. Further, the controller 9 controls the opening of the control valve 4c according to the engine load, thereby controlling the flow rate of the reducing agent to the second flow rate. At this time, the controller 9 acquires a reducing agent flow rate detection signal from the flow sensor 4d, and based on the acquired reducing agent flow rate detection signal, performs feedback control so that the flow rate of the reducing agent becomes the second flow rate.

Further, in parallel with the control of the reducing agent supply system 4 described above, the control unit 9 performs control of the compressed air supply system 5 as shown below. That is, the control unit 9 controls to open the on-off valve 5c of the branch pipe 15c of the air supply pipe 15a communicating with the large injection nozzle 2, and opens the air supply pipe communicating with the small injection nozzle 1 ( Control is performed to close the on-off valve 5b of the branch pipe 15b of 15a). In addition, the control unit 9 judges that the pressure loss of the SCR reactor 6 does not exceed a specified value in the exhaust gas distribution system 3 based on the differential pressure measurement signal from the differential pressure gauge 7, while by The pass valve 13 is controlled to close.

As described above, the controller 9 controls the exhaust gas distribution system 3, the reducing agent supply system 4, and the compressed air supply system 5, so that NOx emissions in the exhaust gas can be reduced in the high-denitization SCR operation mode. Optimum NOx denitrification is performed to reduce the level below the regulated value of the tertiary regulation.

Specifically, as shown in FIG. 2 , in the high denitrification SCR operation mode, the reducing agent L1 sent from the reducing agent supply source 4a to the supply pipe 14a passes through the branch pipe 14c to the control valve 4c ) is reached. The control valve 4c adjusts the flow rate of the reducing agent L1 to the second flow rate by controlling the opening of the control valve 9. The reducing agent L1 (hereinafter referred to as the reducing agent L3) adjusted to the second flow rate by the control valve 4c flows from the control valve 4c through the branch pipe 14f of the supply pipe 14d. After passing through the flow rate sensor 4d, it is supplied into the large injection nozzle 2 through the branch pipe 14i of the supply pipe 14g. In parallel with this, the compressed air G11 sent from the compressed air supply source 5a to the air supply pipe 15a reaches the orifice portion 15e via the branch pipe 15c. The orifice portion 15e adjusts the flow rate or pressure of the compressed air G11 to a flow rate or pressure suitable for jetting (specifically, spraying) of the reducing agent from the large jet nozzle 2. Compressed air G11 whose flow rate or pressure has been adjusted in this way (hereinafter referred to as compressed air G13) is supplied into the large injection nozzle 2 through the branch pipe 15c. The large injection nozzle 2 injects the reducing agent L3 into the mixer 3a by the action of the compressed air G13.

Exhaust gas G1 from the marine diesel engine 100 flows into the mixer 3a through the exhaust pipe 11a. In the mixer 3a, the exhaust gas G1 flowing in from the exhaust pipe 11a and the reducing agent L3 injected from the large injection nozzle 2 mix with each other. The exhaust gas G1 from which the reducing agent L3 has been injected in this way, that is, the exhaust gas G3 in a state containing the injected reducing agent L3 passes from the mixer 3a through the inlet pipe 11b to the SCR reactor ( 6) is introduced within. In the SCR reactor 6, the exhaust gas G3 flows toward the outlet of the SCR reactor 6 while sequentially contacting the plurality of catalyst layers 6a, 6b, and 6c. At this time, the SCR reactor 6 advances the NOx reduction reaction in the exhaust gas G3 by the catalytic action in each of the catalyst layers 6a, 6b, and 6c. In this way, the SCR reactor 6 denitrates NOx in the exhaust gas G3. By this denitrification, the amount of NOx discharged in the exhaust gas G3 is reduced below the regulated value of the tertiary regulation. This exhaust gas G3 is discharged from the SCR reactor 6 to the discharge/recovery side through the outlet pipe 11c.

As described above, in the marine SCR system 10 according to Embodiment 1 of the present invention, in the low-denitization SCR operation mode in which the amount of NOx discharged in exhaust gas is reduced below the regulated value of the first exhaust gas regulation, the exhaust gas A reducing agent for reducing (denitrating) NOx in the gas is adjusted to a first flow rate required to satisfy the first exhaust gas regulation, and is injected into the exhaust gas from the small injection nozzle 1, and the amount of NOx in the exhaust gas is reduced. In the high-denitrification SCR operation mode in which the reducing agent is reduced to a level lower than that of the second exhaust gas regulation, which is lower than the regulation value of the first exhaust gas regulation, the reducing agent is required to satisfy the second exhaust gas regulation, and the first flow rate It is adjusted to a larger second flow rate and is injected from the large injection nozzle 2 to the exhaust gas.

For this reason, the NOx denitrification ability of the exhaust gas in the high NOx removal SCR operation mode is not lowered, and the NOx removal capacity of the exhaust gas in the low NOx removal SCR operation mode can be exhibited without waste. In this way, it is possible to ensure the NOx denitrification ability that can satisfy the regulatory value in each of the first exhaust gas regulation sea area and the other sea area (ie, the second exhaust gas regulation sea area), and even if the first exhaust gas regulation sea area Even if engine fuel efficiency is improved in the exhaust gas regulation sea area, NOx emissions that increase with the improvement in engine fuel economy can be reduced by the NOx denitrification capability in the exhaust gas in the low NOx removal SCR operation mode in the first exhaust gas. It can be reduced below the regulated value of regulation. As a result, further improvement in engine fuel efficiency can be pursued, and NOx emissions can be reduced for a plurality of exhaust gas regulations required for marine diesel engines, such as secondary regulations in general sea areas and tertiary regulations in emission control sea areas. can be effectively reduced.

Further, in the marine SCR system 10 according to Embodiment 1 of the present invention, the flow rate of the reducing agent injected from the small injection nozzle 1 to the exhaust gas is adjusted by the small control valve 4b, and the large injection nozzle The flow rate of the reducing agent injected from (2) into the exhaust gas is adjusted by a large control valve 4c having a larger flow rate adjustment range than the small control valve 4b. For this reason, the first flow rate of the reducing agent, which is difficult to adjust because the flow rate adjustment range is too wide (ie, the flow rate adjustment unit is too large) in the large control valve 4c, can be easily adjusted by the small control valve 4b. . In addition, in the small control valve 4b, the second flow rate of the reducing agent, which is difficult to adjust because the flow rate adjustment range is too narrow (ie, the flow rate adjustment unit is too small), can be easily adjusted by the large control valve 4c.

Further, in the marine SCR system 10 according to Embodiment 1 of the present invention, in the low NOx removal operation mode, compressed air having a predetermined flow rate or pressure is supplied to the small injection nozzle 1, and the high NOx removal SCR In the operation mode, the large injection nozzle 2 is supplied with compressed air with a flow rate higher than the predetermined flow rate or a pressure higher than the predetermined pressure. Therefore, in the low denitrification SCR operation mode, the reducing agent at the first flow rate can be efficiently injected from the small injection nozzle 1 into the exhaust gas. In addition, in the high denitrification SCR operation mode, the reducing agent at the second flow rate can be efficiently injected from the large injection nozzle 2 into the exhaust gas.

Further, in the marine SCR system 10 according to Embodiment 1 of the present invention, the small injection nozzle 1 and the large injection nozzle 2 are formed in the same mixer 3a, and the small injection nozzle 1 or the large injection nozzle 2 The reducing agent injected from the nozzle 2 and the exhaust gas are mixed in the mixer 3a, and the small injection nozzle 1 is set in the direction from the inlet side of the exhaust gas to the outlet side in the mixer 3a. It is arranged at the rear end of the large injection nozzle 2. For this reason, the distance from the injection port of the large injection nozzle 2 to the outlet of the mixer 3a can be made larger than that of the small injection nozzle 1. Thus, the injection range of the reducing agent from the large injection nozzle 2 can be wider than that of the small injection nozzle 1, and as a result, the exhaust gas in the mixer 3a and the reducing agent injected from the large injection nozzle 2 can be efficiently can be mixed with

(Embodiment 2)

Next, Embodiment 2 of the present invention will be described. In the above-described Embodiment 1, the exhaust gas into which the reducing agent has been injected is brought into contact with each catalyst layer from the first stage to the final stage in the SCR reactor 6 regardless of the low NOx SCR operation mode and the high NOx SCR operation mode. In this Embodiment 2, in the case of the low denitration SCR operation mode, it is possible to select a catalyst layer to be brought into contact with the exhaust gas into which the reducing agent has been injected from the second and subsequent catalyst layers.

Fig. 3 is a schematic diagram showing a configuration example of an SCR system for ships according to Embodiment 2 of the present invention. As shown in Fig. 3, the marine SCR system 20 according to the second embodiment includes an inlet pipe 21 instead of the inlet pipe 11b of the marine SCR system 10 according to the first embodiment described above. The exhaust gas flow system 23 is provided instead of the exhaust gas flow system 3, and the control unit 29 is provided instead of the control unit 9. In addition, the SCR system 20 for ships is provided with distribution tubes 22a and 22b as a new configuration. Other configurations are the same as in Embodiment 1, and the same reference numerals are attached to the same configuration parts.

The inlet pipe 21 is a pipe for introducing exhaust gas into the SCR reactor 6 . As shown in FIG. 3 , the inlet end of the inlet pipe 21 is connected to the on-off valve 25b of the exhaust gas distribution system 23 and the outlet end is connected to the inlet end of the SCR reactor 6 . The inlet tube 21 is the inlet side of the exhaust gas in the SCR reactor 6 among the multiple stages of catalyst layers (three stages of catalyst layers 6a, 6b and 6c in the present embodiment 2) formed in the SCR reactor 6. From there, the exhaust gas containing the reducing agent or the exhaust gas not containing the reducing agent injected from the large injection nozzle 2 is introduced into the catalyst layer 6a on the first stage. In addition, exhaust gas in a state containing no reducing agent is exhaust gas in which no reducing agent is injected from either the small injection nozzle 1 or the large injection nozzle 2.

The distribution tubes 22a and 22b are pipes for dispersing the exhaust gas from which the reducing agent has been injected into the SCR reactor 6. As shown in FIG. 3 , the inlet end of the distribution pipe 22a is connected to the on-off valve 25d of the exhaust gas distribution system 23 . A plurality (for example, four) of dispersing nozzles 22c are provided in a piping portion on the outlet side of the dispersing pipe 22a. The piping portion on the outlet side of the diffusion pipe 22a is disposed in the SCR reactor 6 so as to extend into a region between the first catalyst layer 6a and the second catalyst layer 6b. At this time, the dispersion tube 22a is in a state in which the plurality of dispersion nozzles 22c are directed toward the catalyst layer 6b in the second stage. On the other hand, as shown in FIG. 3 , the inlet end of the distribution tube 22b is connected to the on-off valve 25e of the exhaust gas distribution system 23 . A plurality (for example, four) of dispersing nozzles 22d are provided in the piping portion on the outlet side of the dispersing pipe 22b. The piping portion on the outlet side of the diffusion tube 22b is inside the SCR reactor 6 so as to extend into the region between the second catalyst layer 6b and the third (last stage in this embodiment 2) catalyst layer 6c. are placed At this time, the dispersion tube 22b is in a state in which the plurality of dispersion nozzles 22d are directed toward the third stage catalyst layer 6c. These diffusion tubes 22a, 22b are located at the rear end of the first catalyst layer 6a among the plurality of catalyst layers formed in the SCR reactor 6 (three catalyst layers 6a, 6b, and 6c in the present embodiment 2). The exhaust gas in a state containing a reducing agent injected from the small injection nozzle 1 is spread over the second and subsequent catalyst layers located in the above. In detail, in the present Embodiment 2, the distribution pipe 22a spreads the exhaust gas in a state containing a reducing agent injected from the small injection nozzle 1 to the second stage catalyst layer 6b. The dispersion tube 22b spreads the exhaust gas containing the reducing agent injected from the small injection nozzle 1 onto the third catalyst layer 6c.

The exhaust gas distribution system 23 communicates with the above-described inlet pipe 21 and distribution pipes 22a and 22b, and passes the exhaust gas toward the SCR reactor 6. As shown in FIG. 3 , the exhaust gas distribution system 23 includes a bypass pipe 24a, an outlet pipe 24b, a flow pipe 24c, on-off valves 25a to 25e, and a blower 26 to provide In addition, the exhaust gas circulation system 23 includes the same mixer 3a as in the first embodiment, exhaust pipe 11a, bypass pipe 12, and bypass valve 13.

The bypass pipe 24a is a pipe for passing the exhaust gas in a state not containing a reducing agent toward the SCR reactor 6. As shown in FIG. 3 , the bypass pipe 24a has an inlet end connected to the midway portion of the exhaust pipe 11a and an outlet end connected to the midway portion of the inlet pipe 21 . The bypass pipe 24a forms a bypass flow path for exhaust gas that bypasses the mixer 3a from the exhaust pipe 11a and joins the inlet pipe 21 .

The outlet pipe 24b is a pipe for passing the exhaust gas sent from the mixer 3a to the side of the SCR reactor 6. As shown in Fig. 3, the outlet pipe 24b has an inlet end connected to the outlet end of the mixer 3a and an outlet end connected to the on-off valve 25b. Exhaust gas flowing through the outlet pipe 24b includes, for example, exhaust gas containing a reducing agent injected from the small injection nozzle 1 and exhaust gas containing a reducing agent injected from the large injection nozzle 2. Exhaust gas can be cited.

The distribution pipe 24c is a pipe for distributing the exhaust gas containing the reducing agent injected from the small injection nozzle 1 toward the distribution pipes 22a and 22b. As shown in Fig. 3, the inlet end of the flow pipe 24c is connected to the outlet pipe 24b. In addition, the outlet end of the circulation pipe 24c is branched into two, for example, corresponding to the number of distribution pipes 22a and 22b. Each outlet end of these distribution pipes 24c is connected to on-off valves 25d and 25e. That is, the distribution pipe 24c is branched off from the outlet pipe 24b and communicates with the distribution pipes 22a and 22b via the on-off valves 25d and 25e.

Moreover, as shown in FIG. 3, the on-off valve 25a is provided in the bypass pipe 24a. The on-off valve 25a is a drive valve that opens or closes the bypass pipe 24a. The on-off valve 25b is a drive valve that allows the inlet pipe 21 and the outlet pipe 24b to communicate open and close. The on-off valve 25c is provided in the midway portion of the flow pipe 24c (for example, near the outlet end). The on-off valve 25c is a drive valve that opens or closes the flow pipe 24c. The opening/closing valve 25d is a drive valve that connects the distribution pipe 22a and the distribution pipe 24c so that they can open and close. The on-off valve 25e is a drive valve that allows the distribution pipe 22b and the flow pipe 24c to communicate with each other so as to be able to open and close.

The blower 26 is for applying pressure to the exhaust gas flowing through the flow pipe 24c. As shown in Fig. 3, the blower 26 is located between the on-off valve 25c and the outlet end (in the second embodiment, the on-off valves 25d and 25e connected to the respective outlet ends) as a midway portion of the flow pipe 24c. is formed in The blower 26 sucks exhaust gas from the outlet pipe 24b into the flow pipe 24c and applies pressure to the sucked exhaust gas. This pressure is such that the exhaust gas flowing into the distribution tubes 22a and 22b through the flow pipe 24c can be ejected from the respective distribution nozzles 22c and 22d. The blower 26 sends the exhaust gas to which such a pressure has been applied to the distribution pipe 22a, 22b side along the inside of the flow pipe 24c.

The control unit 29 controls the operation of the exhaust gas distribution system 23 that circulates the exhaust gas for each operation mode of the SCR system 20 for ships. Specifically, when the low-denitization SCR operation mode is instructed, the control unit 29 circulates the exhaust gas in a state not containing a reducing agent into the inlet pipe 21, and the injected from the small injection nozzle 1 The exhaust gas distribution system 23 is controlled so that the exhaust gas containing the reducing agent is passed through the distribution tubes 22a and 22b. When the high denitrification SCR operation mode is instructed, the control unit 29 controls the exhaust gas distribution system 23 so that the exhaust gas containing the reducing agent injected from the large injection nozzle 2 is passed through the inlet pipe 21. ) to control. In addition, the controller 29 is the same as in Embodiment 1 described above except for controlling the exhaust gas flow system 23 in this way.

Next, the operation of the marine SCR system 20 according to Embodiment 2 of the present invention will be described. 4 is a diagram for explaining the operation of the SCR system for ships according to the second embodiment of the present invention for each operation mode. Below, the exhaust gas regulation of the general sea area (secondary regulation) is exemplified as the first exhaust gas regulation, and the exhaust gas regulation (tertiary regulation) of the emission regulation sea area is exemplified as the second exhaust gas regulation, and FIGS. 3 and 4 With reference to, the operation of the SCR system 20 for ships will be described for each operation mode.

In the general sea area, the marine SCR system 20 reduces the amount of NOx emitted from the exhaust gas discharged from the marine diesel engine 100 to a value equal to or less than the secondary regulation. In this case, the marine SCR system 20 performs denitrification of NOx in the exhaust gas in the low denitrification SCR operation mode.

In detail, the operation unit 8 transmits an instruction signal instructing the low-denitization SCR operation mode to the control unit 29 according to the operator's operation, thereby instructing the control unit 29 of the low-denitization SCR operation mode. . When the low denitrification SCR operation mode is instructed, the control unit 29 exhausts the reducing agent at the flow rate (ie, the first flow rate) required to reduce the amount of NOx discharged to below the regulated value of the secondary regulation, from the small injection nozzle 1 The exhaust gas distribution system 23, the reducing agent supply system 4, and the compressed air supply system 5 are controlled so that the gas is injected. In addition, the controller 29 selectively brings the exhaust gas containing the reducing agent injected from the small injection nozzle 1 into contact with the second and subsequent catalyst layers 6b and 6c in the SCR reactor 6 so as to selectively contact the exhaust gas. The gas distribution system 23 is controlled. In addition, the control of the reducing agent supply system 4 and the compressed air supply system 5 by the control unit 29 in the low denitrification SCR operation mode is the same as in the first embodiment described above.

For example, in the low denitrification SCR operation mode, the controller 29 performs the following control for the exhaust gas distribution system 23 . That is, the control unit 29 includes an on-off valve 25a of the bypass pipe 24a, an on-off valve 25c on the inlet end side of the flow pipe 24c, and an on-off valve 25d on the outlet end side of the flow pipe 24c. 25e) to open at least one of them. Parallel to this, the controller 29 controls the on-off valve 25b between the outlet pipe 24b and the inlet pipe 21 to be closed. Also, the control unit 29 drives the blower 26 . Control of the bypass valve 13 by the control unit 29 is the same as that of the first embodiment described above.

Here, the control unit 29 opens at least one of the on-off valves 25d and 25e on the outlet end side of the flow pipe 24c according to the engine load. For example, in the control unit 29, a predetermined threshold value is set in advance for the engine load. When the engine load is less than a predetermined threshold value, the control unit 29 controls to open the on-off valve 25e on the rear stage among the on-off valves 25d and 25e, and closes the on-off valve 25d on the front stage. Control. On the other hand, the controller 29 controls to open only the on-off valve 25d or both of the on-off valves 25d and 25e when the engine load is equal to or greater than a predetermined threshold value. In addition, the opening/closing valve 25e at the rear stage is a spreading tube that directs the spraying nozzle 22d to the catalyst layer 6c at the rear stage (third stage in the present embodiment 2) among the second and subsequent catalyst layers 6b and 6c. It is an on-off valve leading to (22b). The front-stage on-off valve 25d has a distribution tube 22a that directs the spraying nozzle 22c to the catalyst layer 6b of the previous stage (the second stage in the present embodiment 2) among the second and subsequent catalyst layers 6b and 6c. ) is an on-off valve through

As described above, the controller 29 controls the exhaust gas distribution system 23, the reducing agent supply system 4, and the compressed air supply system 5, so that NOx emissions in the exhaust gas can be reduced in the low-denitization SCR operation mode. Optimum denitrification of NOx is performed to reduce it below the regulated value of the secondary regulation.

Specifically, as shown in FIG. 4 , in the low-denitization SCR operation mode, the exhaust gas G1 discharged from the marine diesel engine 100 (see FIG. 3 ) passes through the exhaust pipe 11a to the mixer 3a. While flowing into the inside, it flows into the inlet pipe 21 from the exhaust pipe 11a through the bypass pipe 24a. In the mixer 3a, as in the first embodiment described above, the reducing agent L2 adjusted to the first flow rate is sprayed (sprayed) from the small injection nozzle 1 by the action of the compressed air G12. It is becoming. The exhaust gas G1 flowing into the mixer 3a is injected with the reducing agent L2 from the small injection nozzle 1, and is mixed with the reducing agent L2. The exhaust gas G1 from which the reducing agent L2 has been injected in this way, that is, the exhaust gas G2 containing the injected reducing agent L2 is discharged from the mixer 3a into the outlet pipe 24b. The exhaust gas G2 in the outlet pipe 24b is sucked into the flow pipe 24c by the action of the blower 26 and, while maintaining a predetermined pressure, passes through the flow pipe 24c to the SCR reactor 6 side. distributed towards

Here, when the engine load is less than a predetermined threshold value, the on-off valve 25d is in a closed state, and the on-off valve 25e is in an open state. In this case, the exhaust gas G2 in the flow pipe 24c flows into the distribution pipe 22b via the on-off valve 25e. The dispersion tube 22b passes the exhaust gas G2 introduced from the plurality of dispersion nozzles 22d to the third stage catalyst layer 6c in the SCR reactor 6 (reducing agent injected from the small injection nozzle The exhaust gas) in a state containing L2) is dispersed. On the other hand, when the engine load is equal to or greater than a predetermined threshold value, only the on-off valve 25d is open, or both of the on-off valves 25d and 25e are open. When only the on-off valve 25d is open, the exhaust gas G2 in the flow pipe 24c flows into the distribution pipe 22a via the on-off valve 25d. The distribution tube 22a spreads the introduced exhaust gas G2 from the plurality of distribution nozzles 22c to the second stage catalyst layer 6b in the SCR reactor 6. Alternatively, when both of the on-off valves 25d and 25e are open, the exhaust gas G2 in the flow pipe 24c flows into the distribution pipe 22a via the on-off valve 25d, and the on-off valve ( 25e) flows into the dispersing tube 22b. The diffusion tube 22a spreads the exhaust gas G2 to the second stage catalyst layer 6b in the SCR reactor 6 as in the case described above. Parallel to this, the distribution tube 22b spreads the introduced exhaust gas G2 from the plurality of distribution nozzles 22d to the third catalyst layer 6c in the SCR reactor 6.

On the other hand, the exhaust gas G1 flowing into the inlet pipe 21 from the exhaust pipe 11a through the bypass pipe 24a flows into the SCR reactor 6 through the inlet pipe 21, and passes through the first stage catalyst layer. (6a) is introduced. Here, this exhaust gas G1 is an exhaust gas that has flowed into the SCR reactor 6 bypassing the mixer 3a by passing through the inside of the bypass pipe 24a from the exhaust pipe 11a. That is, this exhaust gas (G1) is exhaust gas in a state of not containing the reducing agent (L2). Exhaust gas G1 flowing into the SCR reactor 6 flows through the first catalyst layer 6a. In this case, since the exhaust gas G1 does not contain the reducing agent L2, even if the exhaust gas G1 and the first stage catalyst layer 6a contact each other, NOx in the exhaust gas G1 is denitrated (reduction reaction ) is not implemented.

The exhaust gas G1 that has passed through the first catalyst layer 6a flows through the second and subsequent catalyst layers 6b and 6c sequentially. Here, when the engine load is less than the predetermined threshold value, exhaust gas G2 containing the reducing agent L2 is discharged from only the dispersing tube 22b at the rear stage among the dispersing tubes 22a and 22b in the SCR reactor 6. is scattered In this case, the exhaust gas G1 flows through the second catalyst layer 6b without containing the reducing agent L2, similar to the case of the first catalyst layer 6a. That is, NOx in the exhaust gas G1 is not denitrated even in the second catalyst layer 6b. Subsequently, the exhaust gas G1 flows from the second catalyst layer 6b toward the third catalyst layer 6c. At this time, the exhaust gas G1 is mixed with the exhaust gas G2 sprayed from the plurality of spray nozzles 22d of the distribution pipe 22b, thereby containing the reducing agent L2 in the exhaust gas G2. exhaust gas (that is, a part of the exhaust gas G2) in a state of Such exhaust gas (G2) flows into the third stage catalyst layer (6c) in a state containing a reducing agent (L2). In the catalyst layer 6c of the third stage, a reduction reaction of NOx in the exhaust gas G2 proceeds by a catalytic action, whereby NOx in the exhaust gas G2 is denitrated. Due to this denitrification, the amount of NOx discharged in the exhaust gas G2 is reduced below the regulation value of the secondary regulation. After that, the exhaust gas G2 that has passed through the third catalyst layer 6c is discharged from the SCR reactor 6 through the outlet pipe 11c to the discharge/recovery side.

On the other hand, when the engine load is equal to or greater than the predetermined threshold value, the exhaust gas (G2) containing the reducing agent (L2) is discharged from only the diffusion pipe (22a) or both of the diffusion pipes (22a, 22b) in the SCR reactor (6). ) is distributed. In this case, the exhaust gas G1 that has passed through the catalyst layer 6a in the first stage is mixed with the exhaust gas G2 distributed from the plurality of dispersing nozzles 22c of the dispersing pipe 22a, thereby resulting in this exhaust gas G1. It becomes the exhaust gas in a state containing the reducing agent (L2) in the gas (G2) (that is, a part of the exhaust gas (G2)). Alternatively, the exhaust gas G1 that has passed through the first catalyst layer 6a is mixed with the exhaust gas G2 distributed from the plurality of dispersing nozzles 22c of the dispersing tube 22a, and then the dispersing tube 22a. It is mixed with the exhaust gas G2 dispersed from the plurality of dispersing nozzles 22d of (22b). In this way, the exhaust gas G1 becomes exhaust gas (that is, a part of the exhaust gas G2) in a state in which the reducing agent L2 is sequentially contained in the exhaust gas G2. In any of the cases described above, the exhaust gas G2 flows sequentially into the second and subsequent catalyst layers 6b and 6c in a state containing the reducing agent L2. In the second and subsequent catalyst layers 6b and 6c, a reduction reaction of NOx in the exhaust gas G2 proceeds sequentially by a catalytic action, whereby NOx in the exhaust gas G2 is denitrated. Due to this denitrification, the amount of NOx discharged in the exhaust gas G2 is reduced below the regulation value of the secondary regulation. After that, the exhaust gas G2 that has passed through the third catalyst layer 6c is discharged from the SCR reactor 6 through the outlet pipe 11c to the discharge/recovery side.

On the other hand, in the emission control sea area, the marine SCR system 20 reduces the amount of NOx emitted from the exhaust gas discharged from the marine diesel engine 100 below the regulated value of the tertiary regulation. In this case, the marine SCR system 20 performs denitrification of NOx in the exhaust gas in the high denitrification SCR operation mode.

In detail, the operation unit 8 transmits an instruction signal instructing the high-denitrification SCR operation mode to the control unit 29 according to the operator's operation, thereby instructing the control unit 29 of the high-denitization SCR operation mode. . When the high denitrification SCR operation mode is instructed, the controller 29 exhausts the reducing agent from the large injection nozzle 2 at a flow rate (ie, the second flow rate) necessary to reduce the amount of NOx discharged to below the regulated value of the tertiary regulation. The exhaust gas distribution system 23, the reducing agent supply system 4, and the compressed air supply system 5 are controlled so that the gas is injected. In addition, the control of the reducing agent supply system 4 and the compressed air supply system 5 by the control unit 29 in the high denitrification SCR operation mode is the same as in the first embodiment described above.

For example, in the high denitrification SCR operation mode, the control unit 29 controls the exhaust gas distribution system 23 as follows. That is, the control unit 29 includes an on-off valve 25a of the bypass pipe 24a, an on-off valve 25c on the inlet end side of the flow pipe 24c, and an on-off valve 25d on the outlet end side of the flow pipe 24c. 25e) is controlled to block. Prior to this, the controller 29 controls to open the on-off valve 25b between the outlet pipe 24b and the inlet pipe 21. Also, the control unit 29 stops the blower 26 . Control of the bypass valve 13 by the control unit 29 is the same as that of the first embodiment described above.

As described above, the controller 29 controls the exhaust gas distribution system 23, the reducing agent supply system 4, and the compressed air supply system 5, so that NOx emissions in the exhaust gas can be reduced in the high-denitization SCR operation mode. Optimum NOx denitrification is performed to reduce the level below the regulated value of the tertiary regulation.

Specifically, as shown in FIG. 4 , in the high-denitization SCR operation mode, the exhaust gas G1 discharged from the marine diesel engine 100 (see FIG. 3 ) passes through the exhaust pipe 11a to the mixer 3a. infiltrated into In the mixer 3a, as in the first embodiment described above, the reducing agent L3 adjusted to the second flow rate is sprayed (sprayed) from the large injection nozzle 2 by the action of the compressed air G13. It is becoming. The exhaust gas G1 flowing into the mixer 3a is injected with the reducing agent L3 from the large injection nozzle 2, and is mixed with the reducing agent L3. The exhaust gas G1 from which the reducing agent L3 has been injected in this way, that is, the exhaust gas G3 containing the injected reducing agent L3 is discharged from the mixer 3a into the outlet pipe 24b. The exhaust gas G3 in the outlet pipe 24b flows into the SCR reactor 6 through the on-off valve 25b and the inlet pipe 21, and is introduced into the first catalyst layer 6a.

In the SCR reactor 6, the exhaust gas G3 flows toward the outlet of the SCR reactor 6 while sequentially contacting the plurality of catalyst layers 6a, 6b, and 6c. Here, the exhaust gas G3 is exhaust gas in a state containing the reducing agent L3 injected from the large injection nozzle 2 . The SCR reactor 6 advances the NOx reduction reaction in the exhaust gas G3 by the catalytic action in each of the catalyst layers 6a, 6b, and 6c. In this way, the SCR reactor 6 denitrates NOx in the exhaust gas G3. By this denitrification, the amount of NOx discharged in the exhaust gas G3 is reduced below the regulated value of the tertiary regulation. Exhaust gas G3 that has passed through the third catalyst layer 6c is discharged from the SCR reactor 6 through the outlet pipe 11c to the discharge/recovery side.

As described above, in the marine SCR system 20 according to the second embodiment of the present invention, a plurality of catalyst layers are formed in the SCR reactor 6 from the inlet side to the outlet side of the exhaust gas, and the low NOx SCR operation mode is indicated, the exhaust gas containing no reducing agent is introduced into the first catalyst layer among the plurality of catalyst layers, and the exhaust gas containing the reducing agent injected from the small injection nozzle 1 is introduced into the catalyst layer in a plurality of stages. is distributed over the second and subsequent catalyst layers among the catalyst layers, and when the high denitration SCR operation mode is instructed, the exhaust gas containing the reducing agent injected from the large injection nozzle 2 is transferred to the first catalyst layer among the plurality of catalyst layers ( 6a), and other configurations are the same as in Embodiment 1.

Among these plural catalyst layers, the amount of NOx denitrated in the first catalyst layer by the reduction reaction is larger than that of the second and subsequent catalyst layers. Therefore, the rate of deterioration of the catalyst layer in the first stage accompanying the NOx reduction reaction is faster than that of the catalyst layers in the second and subsequent stages, and there is a risk that uneven deterioration may occur between these catalyst layers in the plurality of stages. On the other hand, according to the configuration of the second embodiment, the same functions and effects as those of the first embodiment described above can be enjoyed, and in accordance with the amount to be reduced (denitration) of NOx in the exhaust gas, these plural stages of the catalyst layer Among them, a catalyst layer required for the NOx reduction reaction can be selected. As a result, in the sea area subject to the first exhaust gas regulation (eg, general sea area) where the amount of NOx to be reduced is smaller than that of the second exhaust gas regulation (eg, the tertiary regulation), the catalyst associated with the NOx reduction reaction The second and subsequent catalyst layers having a slower deterioration rate than the first catalyst layer can be positively used as catalyst layers for carrying out the reduction reaction. As a result, since the deterioration rate of the first catalyst layer can be reduced, the unevenness of deterioration among the catalyst layers of these multiple stages can be suppressed, and the catalyst layers of these multiple stages can be efficiently used for the reduction reaction. can

(Embodiment 3)

Next, Embodiment 3 of the present invention will be described. In Embodiment 2 described above, the small injection nozzle 1 and the large injection nozzle 2 are arranged in a single mixer 3a, but in the present Embodiment 3, the small injection nozzle 1 and the large injection nozzle ( 2) are placed in separate mixers.

Fig. 5 is a schematic diagram showing an example of a configuration of an SCR system for ships according to Embodiment 3 of the present invention. As shown in Fig. 5, the marine SCR system 30 according to the third embodiment includes an inlet pipe 31 instead of the inlet pipe 21 of the marine SCR system 20 according to the second embodiment described above. The exhaust gas flow system 33 is provided instead of the exhaust gas flow system 23, and the control unit 39 is provided instead of the control unit 29. Other configurations are the same as those of Embodiment 2, and the same reference numerals are attached to the same components.

The inlet pipe 31 is a pipe for introducing exhaust gas into the SCR reactor 6 . As shown in FIG. 5 , the inlet pipe 31 has an inlet end connected to the outlet pipe 34a of the exhaust gas distribution system 33 and an outlet end connected to the inlet end of the SCR reactor 6 . The inlet pipe 31 is the inlet side of the exhaust gas in the SCR reactor 6 among the multiple stages of catalyst layers (three stages of catalyst layers 6a, 6b and 6c in the present embodiment 3) formed in the SCR reactor 6. From there, the exhaust gas containing the reducing agent or the exhaust gas not containing the reducing agent injected from the large injection nozzle 2 is introduced into the catalyst layer 6a on the first stage.

The exhaust gas distribution system 33 communicates with the above-described inlet pipe 31 and distribution pipes 22a and 22b, and flows the exhaust gas toward the SCR reactor 6. As shown in FIG. 5 , the exhaust gas distribution system 33 is provided with separate mixers 33a and 33b instead of the single mixer 3a in the second embodiment, and the outlet in the second embodiment. Instead of the tube 24b, an outlet tube 34a is provided. In addition, the exhaust gas distribution system 33, as in the second embodiment, includes an exhaust pipe 11a, a bypass pipe 12, a bypass valve 13, a distribution pipe 24c, and an on-off valve 25c , 25d, 25e) and a blower 26.

The mixer 33a mixes the reducing agent injected from the small injection nozzle 1 and the exhaust gas from the marine diesel engine 100 (an example of the first mixer). As shown in Fig. 5, the mixer 33a has the small injection nozzle 1 therein, and is formed between the blower 26 and the on-off valves 25d and 25e as a midway portion of the flow pipe 24c. The mixer 33a mixes the exhaust gas introduced through the distribution pipe 24c with the reducing agent injected from the small injection nozzle 1, while circulating the exhaust gas containing the reducing agent toward the SCR reactor 6. let it

The mixer 33b mixes the reducing agent injected from the large injection nozzle 2 and the exhaust gas from the marine diesel engine 100 (an example of the second mixer). As shown in Fig. 5, in the mixer 33b, an exhaust pipe 11a is connected to the inlet side of the exhaust gas, and an outlet pipe 34a is connected to the outlet side of the exhaust gas. Moreover, the mixer 33b has the large injection nozzle 2 inside. The mixer 33b mixes the exhaust gas introduced from the exhaust pipe 11a and the reducing agent injected from the large injection nozzle 2, while passing the exhaust gas containing the reducing agent toward the SCR reactor 6 through the outlet pipe. Circulated in (34a).

The outlet pipe 34a is a pipe for passing the exhaust gas sent from the mixer 33b to the SCR reactor 6 side. As shown in FIG. 5 , the outlet pipe 34a has an inlet end connected to the outlet end of the mixer 33b and an outlet end connected to the inlet end of the inlet pipe 31 . Moreover, the outlet end of the outlet pipe 34a is connected to the inlet end of the flow pipe 24c. That is, the outlet pipe 34a is configured such that the outlet end side is branched into the inlet pipe 31 and the flow pipe 24c. Exhaust gas flowing through the outlet pipe 24b includes, for example, exhaust gas containing a reducing agent injected from the large injection nozzle 2 and exhaust gas containing no reducing agent (large injection nozzle 2 ) from the exhaust gas to which the reducing agent is not injected).

The control unit 39 controls the operation of the exhaust gas distribution system 33 that circulates the exhaust gas for each operation mode of the SCR system 30 for ships. In detail, when the low-denitization SCR operation mode is instructed, the control unit 39 circulates the exhaust gas in a state not containing a reducing agent into the inlet pipe 31, and the injected from the small injection nozzle 1 The exhaust gas distribution system 33 is controlled so that the exhaust gas containing the reducing agent is passed only within the distribution tube 22b or both within the distribution tube 22a, 22b. When the high denitrification SCR operation mode is instructed, the control unit 39 causes the exhaust gas in a state containing a reducing agent injected from the large injection nozzle 2 to flow through the inlet pipe 31 so that the exhaust gas distribution system 33 ) to control. In addition, the control unit 39 is the same as in the above-described Embodiment 2 except for the above control.

Next, the operation of the marine SCR system 30 according to Embodiment 3 of the present invention will be described. 6 is a diagram for explaining the operation of the SCR system for ships according to the third embodiment of the present invention for each operation mode. Below, the exhaust gas regulation of the general sea area (secondary regulation) is exemplified as the first exhaust gas regulation, and the exhaust gas regulation of the emission regulation sea area (tertiary regulation) is exemplified as the second exhaust gas regulation. With reference to, the operation of the SCR system 30 for ships will be described for each operation mode.

In the general sea area, the marine SCR system 30 reduces the amount of NOx in the exhaust gas discharged from the marine diesel engine 100 to below the regulation value of the secondary regulation. In this case, the marine SCR system 30 performs denitrification of NOx in the exhaust gas in the low denitrification SCR operation mode.

In detail, the operation unit 8 transmits an instruction signal instructing the low NOx removal SCR operation mode to the control unit 39 according to the operator's operation, thereby instructing the control unit 39 to the low NOx removal SCR operation mode. . When the low denitrification SCR operation mode is instructed, the control unit 39 exhausts the reducing agent at the flow rate (ie, the first flow rate) required to reduce the amount of NOx discharged to below the regulated value of the secondary regulation, The exhaust gas distribution system 33, the reducing agent supply system 4, and the compressed air supply system 5 are controlled so that the gas is injected. In addition, in the low denitrification SCR operation mode, the control unit 39 operates the bypass valve 13 of the exhaust gas distribution system 33, the on-off valves 25c, 25d, and 25e, the blower 26, and the reducing agent supply system. (4) and the compressed air supply system 5 are controlled in the same manner as in Embodiment 2 described above.

As described above, the controller 39 controls the exhaust gas distribution system 33, the reducing agent supply system 4, and the compressed air supply system 5, so that NOx emissions in the exhaust gas can be reduced in the low-denitization SCR operation mode. Optimum denitrification of NOx is performed to reduce it below the regulated value of the secondary regulation.

Specifically, as shown in FIG. 6 , in the low-denitization SCR operation mode, the exhaust gas G1 discharged from the marine diesel engine 100 (see FIG. 5 ) passes through the exhaust pipe 11a to the mixer 33b. infiltrated into Here, in the low denitrification SCR operation mode, the reducing agent is not injected from the large injection nozzle 2 as in the above-described Embodiment 2. Therefore, the exhaust gas G1 in the mixer 33b is discharged from the mixer 33b into the outlet pipe 34a without being mixed with the reducing agent. The exhaust gas G1 in the outlet pipe 34a flows into the inlet pipe 31 and is sucked into the flow pipe 24c by the action of the blower 26, and flows through the flow pipe 24c in a state of having a predetermined pressure. from which it flows into the mixer 33a.

In the mixer 33a, as in the second embodiment described above, the reducing agent L2 adjusted to the first flow rate is sprayed (sprayed) from the small injection nozzle 1 by the action of the compressed air G12. It is becoming. The exhaust gas G1 flowing into the mixer 33a is injected with the reducing agent L2 from the small injection nozzle 1, and is mixed with the reducing agent L2. The exhaust gas G1 from which the reducing agent L2 has been injected in this way, that is, the exhaust gas G2 in a state containing the injected reducing agent L2 is discharged from the outlet side of the mixer 33a into the flow pipe 24c. Exhaust gas G2 discharged into the distribution pipe 24c is spread in the SCR reactor 6 from at least one of the distribution pipes 22a and 22b, similarly to the above-described Embodiment 2.

On the other hand, the exhaust gas G1 flowing into the inlet pipe 31 from the mixer 33b through the outlet pipe 34a flows into the SCR reactor 6 through the inlet pipe 31, and passes through the first stage catalyst layer ( 6a) is introduced. Subsequently, this exhaust gas G1 flows through the first catalyst layer 6a. Since this exhaust gas G1 does not contain the reducing agent L2, similarly to the above-described Embodiment 2, in the catalyst layer 6a of the first stage, the reduction reaction of NOx in this exhaust gas G1 denitrification is not performed.

The exhaust gas G1 that has passed through the first catalyst layer 6a flows through the second and subsequent catalyst layers 6b and 6c sequentially. In this case, the exhaust gas G1 is mixed with the reducing agent L2 in the exhaust gas G2 dispersed from at least one of the distribution tubes 22a and 22b, similar to the above-described Embodiment 2, and the reducing agent ( L2) and is denitrated by the NOx reduction reaction. Due to this denitrification, the amount of NOx discharged in the exhaust gas G2 is reduced below the regulation value of the secondary regulation. Thereafter, this exhaust gas G2 is discharged from the SCR reactor 6 to the discharge/recovery side through the outlet pipe 11c.

On the other hand, in the emission control sea area, the marine SCR system 30 reduces the amount of NOx in the exhaust gas discharged from the marine diesel engine 100 below the regulated value of the tertiary regulation. In this case, the marine SCR system 30 performs denitrification of NOx in the exhaust gas in the high denitrification SCR operation mode.

In detail, the operation unit 8 transmits an instruction signal instructing the high-denitrification SCR operation mode to the control unit 39 according to the operator's operation, thereby instructing the control unit 39 of the high-denitization SCR operation mode. . When the high denitrification SCR operation mode is instructed, the control unit 39 exhausts the reducing agent from the large injection nozzle 2 at a flow rate (ie, the second flow rate) required to reduce the amount of NOx discharged to below the regulated value of the tertiary regulation. The exhaust gas distribution system 33, the reducing agent supply system 4, and the compressed air supply system 5 are controlled so that the gas is injected. In addition, in the high denitrification SCR operation mode, the control unit 39 controls the bypass valve 13, the on-off valves 25c, 25d, and 25e of the exhaust gas distribution system 33, the blower 26, and the reducing agent supply system. (4) and the compressed air supply system 5 are controlled in the same manner as in Embodiment 2 described above.

As described above, the controller 39 controls the exhaust gas distribution system 33, the reducing agent supply system 4, and the compressed air supply system 5, so that NOx emissions in the exhaust gas can be reduced in the high-denitization SCR operation mode. Optimum NOx denitrification is performed to reduce the level below the regulated value of the tertiary regulation.

Specifically, as shown in FIG. 6 , in the high-denitization SCR operation mode, the exhaust gas G1 discharged from the marine diesel engine 100 (see FIG. 5 ) passes through the exhaust pipe 11a to the mixer 33b. infiltrated into In the mixer 33b, as in the second embodiment described above, the reducing agent L3 adjusted to the second flow rate is sprayed (sprayed) from the large injection nozzle 2 by the action of the compressed air G13. It is becoming. The exhaust gas G1 flowing into the mixer 33b is injected with the reducing agent L3 from the large injection nozzle 2, and is mixed with the reducing agent L3. The exhaust gas G1 from which the reducing agent L3 has been injected in this way, that is, the exhaust gas G3 in a state containing the injected reducing agent L3 is discharged from the mixer 33b into the outlet pipe 34a. Exhaust gas G3 in the outlet pipe 34a flows into the SCR reactor 6 through the inlet pipe 31 and is introduced into the first catalyst layer 6a.

In the SCR reactor 6, the exhaust gas G3 flows toward the outlet of the SCR reactor 6 while sequentially contacting the plurality of catalyst layers 6a, 6b, and 6c. Here, the exhaust gas G3 is exhaust gas in a state containing the reducing agent L3 injected from the large injection nozzle 2 . Similar to the above-described Embodiment 2, the SCR reactor 6 advances the NOx reduction reaction in the exhaust gas G3 by the catalytic action in each of the catalyst layers 6a, 6b, and 6c, NOx in the exhaust gas (G3) is denitrated. By this denitrification, the amount of NOx discharged in the exhaust gas G3 is reduced below the regulated value of the tertiary regulation. This exhaust gas G3 is discharged from the SCR reactor 6 to the discharge/recovery side through the outlet pipe 11c.

As described above, in the marine SCR system 30 according to the third embodiment of the present invention, the small injection nozzle 1 is disposed in the mixer 33a, and the reducing agent and the exhaust gas injected from the small injection nozzle 1 are disposed in the mixer 33a. are mixed in the mixer 33a, and the large injection nozzle 2 is disposed in the mixer 33b separate from the mixer 33a, so that the reducing agent and the exhaust gas injected from the large injection nozzle 2 are mixed in the mixer 33b. It is made to mix within, and the others are comprised similarly to Embodiment 2. For this reason, while being able to enjoy the same operation and effect as the above-described Embodiment 2, compared to the exhaust gas distribution system 23 in Embodiment 2, the piping and opening/closing valve for switching the distribution route of the exhaust gas can reduce In this way, the exhaust gas distribution system 33 for selecting a catalyst layer necessary for the NOx reduction reaction from among the plural stages of catalyst layers in the SCR reactor 6 according to the amount to be reduced (denitrogenation) of NOx in the exhaust gas is simply provided. can be configured. Furthermore, control of this exhaust gas flow system 33 can be performed simply.

Further, in Embodiments 1 to 3 described above, the large jet nozzle 2 was made a jet nozzle with a larger diameter than the small jet nozzle 1, but the present invention is not limited to this. In the present invention, the large injection nozzle 2 may be constituted by an assembly of injection nozzles having a small diameter (for example, a diameter smaller than or equal to the small injection nozzle 1). In addition, a spray nozzle in which the small spray nozzle 1 and the large spray nozzle 2 are integrated is constituted by an assembly of small-diameter spray nozzles, and m spray nozzles of this assembly are used as small spray nozzles 1, It is good also considering the remaining n spray nozzles (provided that n > m) as large spray nozzles 2. Alternatively, the small injection nozzle 1 and the large injection nozzle 2 may be constituted by one or more variable injection nozzles capable of adjusting the amount of injection.

Further, in Embodiments 1 to 3 described above, as an example of a plurality of catalyst layers disposed along the direction from the inlet side of the exhaust gas to the outlet side (ie, the flow direction of the exhaust gas) in the SCR reactor 6, 3 Although the stage catalyst layers 6a, 6b, and 6c were illustrated, this invention is not limited to this. In the present invention, the number (number of stages) of catalyst layers disposed in the SCR reactor 6 may be two or more. In Embodiment 1, the number of catalyst layers may be one or more.

In addition, in Embodiments 2 and 3 described above, two diffusion tubes 22a and 22b are arranged in the SCR reactor 6, but the present invention is not limited to this. In the present invention, the required number (for example, the same number) of the diffusion tubes for distributing the exhaust gas containing the reducing agent is arranged according to the number of the second and subsequent catalyst layers among the plurality of catalyst layers in the SCR reactor 6. may be

Further, in Embodiments 1 and 2 described above, the small injection nozzle 1 and the large injection nozzle 2 are arranged in a single mixer 3a, but the present invention is not limited to this. In the present invention, the small injection nozzle 1 and the large injection nozzle 2 may be separately disposed in separate mixers.

In the above-described Embodiments 2 and 3, in the low-denitization SCR operation mode, the exhaust gas containing no reducing agent is introduced into the first stage catalyst layer 6a in the SCR reactor 6, and the small injection nozzle Although the exhaust gas containing the reducing agent injected from (1) has been introduced (dispersed) to at least one of the second and subsequent catalyst layers 6b and 6c in the SCR reactor 6, the present invention is limited to this It is not. In the present invention, in not only the low-denitization SCR operation mode but also the high-denitization SCR operation mode, the exhaust gas in a state containing no reducing agent is introduced into the catalyst layer 6a of the first stage in the SCR reactor 6, and the large injection The exhaust gas containing the reducing agent injected from the nozzle 2 may be introduced into at least one of the second and subsequent catalyst layers 6b and 6c in the SCR reactor 6.

In addition, this invention is not limited by Embodiment 1-3 mentioned above. What was constituted by appropriately combining each of the components described above is also included in the present invention. In addition, all other embodiments, examples, operation techniques, etc. made by those skilled in the art based on the above-described embodiments 1 to 3 are included in the scope of the present invention.

As described above, the marine SCR system according to the present invention is useful for reducing NOx in exhaust gas, and in particular, while pursuing improvement in engine fuel efficiency, the NOx It is suitable for the SCR system for ships that can reduce emissions efficiently.

1: small injection nozzle
2: Large injection nozzle
3: exhaust gas distribution system
3a: mixer
4: reducing agent supply system
4a: source of reducing agent
4b: small control valve
4c: large control valve
4d: flow sensor
4e, 4f: open/close valve
5: Compressed air supply system
5a: source of compressed air
5b, 5c: open/close valve
6: SCR reactor
6a, 6b, 6c: catalyst layer
7: differential pressure gauge
8: control panel
9, 29, 39: control unit
10, 20, 30: SCR system for ships
11a: exhaust pipe
11b: inlet pipe
11c: outlet pipe
12: bypass pipe
13: bypass valve
14a, 14d, 14g: supply pipe
14b, 14c, 14e, 14f, 14h, 14i: branch pipe
15a: air supply pipe
15b, 15c: branch pipe
15d, 15e: orifice part
21: inlet pipe
22a, 22b: distribution pipe
22c, 22d: Scattering nozzle
23: Exhaust gas distribution system
24a: bypass pipe
24b: outlet pipe
24c: distribution pipe
25a, 25b, 25c, 25d, 25e: on-off valve
26: blower
31: inlet pipe
33: exhaust gas distribution system
33a, 33b: mixer
34a: outlet pipe
100: marine diesel engine
G1, G2, G3: Exhaust gas
G11, G12, G13 : Compressed air
L1, L2, L3: reducing agent

Claims (8)

A first injection nozzle for injecting a reducing agent for reducing nitrogen oxides in the exhaust gas into the exhaust gas discharged from the marine diesel engine;
a second injection nozzle for injecting a larger amount of the reducing agent than the first injection nozzle into the exhaust gas;
A reducing agent supply system for adjusting the flow rate of the reducing agent injected into the exhaust gas and supplying the reducing agent after adjusting the flow rate to the first spray nozzle or the second spray nozzle;
A reactor having a catalyst layer that contacts the exhaust gas into which the reducing agent has been injected to perform a reduction reaction of the nitrogen oxide;
a first operation mode in which the amount of nitrogen oxides is reduced below a regulation value of a first exhaust gas regulation, and an amount of nitrogen oxides emitted below a regulation value of a second exhaust gas regulation lower than the regulation value of the first exhaust gas regulation; an operation unit for switchably instructing a second driving mode for reducing
When the first operation mode is indicated, the reducing agent supply system is controlled so that the reducing agent is adjusted to a first flow rate required to satisfy the first exhaust gas regulation and supplied to the first injection nozzle, When 2 operation mode is indicated, the reducing agent supply system is configured to supply the reducing agent to the second injection nozzle at a second flow rate necessary to satisfy the second exhaust gas regulation and higher than the first flow rate. Marine SCR system characterized in that it is provided with a control unit for controlling. According to claim 1,
The reducing agent supply system,
A first control valve for adjusting the flow rate of the reducing agent injected into the exhaust gas from the first injection nozzle;
and a second control valve having a flow rate adjustment range wider than that of the first control valve and adjusting the flow rate of the reducing agent injected into the exhaust gas from the second injection nozzle. According to claim 1 or 2,
A compressed air supply system for supplying compressed air to the first spray nozzle or the second spray nozzle,
The control unit controls the compressed air supply system to supply the compressed air having a predetermined flow rate or pressure to the first injection nozzle when the first operation mode is instructed, and when the second operation mode is instructed , The SCR system for ships characterized in that for controlling the compressed air supply system to supply the compressed air having a higher flow rate or higher pressure than the predetermined flow rate or pressure to the second injection nozzle. According to claim 1 or 2,
The vessel SCR system, characterized in that the reactor has a plurality of stages of the catalyst layer from the inlet side of the exhaust gas in the reactor to the outlet side. According to claim 4,
The exhaust gas or the reducing agent in a state containing the reducing agent injected from the second injection nozzle to the catalyst layer at the first stage from the inlet side of the exhaust gas in the reactor among the plurality of stages of the catalyst layers formed in the reactor. an inlet pipe for introducing the exhaust gas in a state not containing;
a distribution tube for distributing the exhaust gas containing the reducing agent injected from the first injection nozzle to the second and subsequent catalyst layers located at the rear end of the first catalyst layer;
an exhaust gas distribution system communicating with the inlet pipe and the distribution pipe and circulating the exhaust gas toward the reactor;
The control unit, when the first operation mode is instructed, circulates the exhaust gas in a state not containing the reducing agent into the inlet pipe, and in a state containing the reducing agent injected from the first injection nozzle. The exhaust gas distribution system is controlled so that the exhaust gas is circulated in the distribution tube, and the exhaust gas containing the reducing agent injected from the second injection nozzle is discharged when the second operation mode is instructed. The marine SCR system, characterized in that for controlling the exhaust gas distribution system so as to flow in the inlet pipe. According to claim 1 or 2,
a first mixer having the first injection nozzle and mixing the reducing agent injected from the first injection nozzle with the exhaust gas;
and a second mixer having the second injection nozzle and mixing the reducing agent injected from the second injection nozzle with the exhaust gas. According to claim 1 or 2,
and a mixer having the first injection nozzle and the second injection nozzle and mixing the reducing agent injected from the first injection nozzle or the second injection nozzle and the exhaust gas. According to claim 7,
The marine SCR system, characterized in that the first injection nozzle is disposed at a rear end of the second injection nozzle in a direction from the inlet side of the exhaust gas to the outlet side in the mixer.

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