Patent Description:
There has been known a NOx removal system used in ships and the like to reduce a nitrogen oxide (NOX) in an exhaust gas from an engine. Such a NOx removal system supplies, together with the exhaust gas, ammonia to a NOx removal catalyst, such as a selective catalytic reduction (SCR) catalyst, so as to cause a reduction reaction of a nitrogen oxide, thereby purifying the exhaust gas. Typically, in order to supply ammonia, a vessel for a hydrolysis reaction (hydrolysis reaction vessel; carburetor) carries out hydrolysis of urea water, which is easy to handle, in a high-temperature gas stream to generate ammonia. In order to supply the high-temperature gas stream to the hydrolysis reaction vessel, a hydrolysis device includes a burner unit. Further flow diverters for hydrolysis vessels are known from the following publications: <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> or <CIT>.

In the hydrolysis device to be applied to the NOx removal system, if a high-temperature gas stream obtained, in the hydrolysis reaction vessel, as a result of supply of an extraction gas from the engine and a gas from the burner unit has unevenness in flow rate and temperature, urea water sprayed thereto is hydrolyzed partially insufficiently. In view of this, the temperature and the flow rate of the gas stream supplied to the hydrolysis reaction vessel are preferably even.

In order to reduce the degree of unevenness in the gas stream, a study is typically made to design adequately long piping between the burner unit and the hydrolysis reaction vessel. However, adopting longer piping increases a heat loss in the piping, thereby reducing system efficiency. In addition, adopting the longer piping increases the size of the hydrolysis device, which is disadvantageous particularly in application to transportation equipment such as ships. Addition of a flow straightening part in the piping may be one idea. This, however, increases an exhaust resistance, thereby possibly causing deterioration in system efficiency.

An aspect of the present invention has an object to provide a flow straightening device which is for use in a hydrolysis device and with which a reduction in system efficiency in the hydrolysis device can be suppressed and/or the hydrolysis device can be downsized.

In order to attain the object, a flow straightening device in accordance with an aspect of the present invention is a flow straightening device through which a gas stream passes before being introduced into a hydrolysis reaction vessel that causes a hydrolysis reaction of urea water, the flow straightening device including: an outer tube into which the gas stream flows through one end of the outer tube toward the other end of the outer tube which is opposite to the one end; a control wall positioned inside the outer tube or at the other end of the outer tube, the control wall reversing at least a portion of the gas stream flowing into the outer tube through the one end toward the other end; and at least one tube part which is at least partially positioned at a location that is inside the outer tube and that is between the one end and the control wall, the at least one tube part constituting a flow passage of the gas stream flowing from an inside of the outer tube toward an outside of the outer tube through a side wall of the outer tube so as to introduce the gas stream inside the outer tube into the hydrolysis reaction vessel, the at least one tube part having an inlet part and an outlet part for the gas stream.

With the above aspect of the present invention, it is possible to provide a flow straightening device which is for use in a hydrolysis device and with which a reduction in system efficiency in the hydrolysis device can be suppressed and/or the hydrolysis device can be downsized.

The following description will discuss, with reference to the drawings, an embodiment of the present invention. Shapes and sizes (e.g., lengths, widths, and heights) of configurations illustrated in the accompanying drawings do not always reflect shapes and sizes of the actual configurations, and may sometimes be changed appropriately for the purpose of clarification and simplification of the drawings.

The description in Embodiment <NUM> will discuss a basic configuration of a flow straightening device in accordance with an aspect of the present invention. <FIG> is a view of a flow passage structure 100X including a flow straightening device 100A in accordance with Embodiment <NUM>. <FIG> includes an A-A cross-section view <NUM> of the flow straightening device 100A viewed in a front side and a B-B cross-section view <NUM> of the flow straightening device 100A viewed in a left side. The positions in which the cross sections are taken are indicated in the cross-section views in <FIG>.

The flow straightening device 100A includes an outer tube 110A and a tube part 120A. In Embodiment <NUM>, the tube part 120A has a cylindrical shape. Alternatively, the tube part 120A may be a square tube or a tube of another shape. That is, the tube part 120A may have a radial cross section having a circular shape, an elliptical shape, a square shape, a rectangular shape, or any of other polygonal shapes.

The outer tube 110A receives, through one end thereof in its axial direction, a gas stream introduced thereinto. The outer tube 110A has an inlet opening part 102A therefor. The inlet opening part 102A constitutes an introduction port through which a gas is introduced into the flow straightening device 100A. The gas stream flowing through the inlet opening part 102A (the one end of the outer tube 110A) travels toward the other end of the outer tube 110A. That is, a direction in which the gas stream flows through the inlet opening part 102A (the one end of the outer tube 110A) so as to enter the flow straightening device 100A is in parallel with an axis of the outer tube 110A.

The inlet opening part 102A, which is provided at the one end of the outer tube 110A, has an inner diameter smaller than an inner diameter of the outer tube 110A. That is, the inlet opening part 102A has an area smaller than a radial cross-section area of the outer tube 110A. Thus, the outer tube 110A has a portion that is close to the inlet opening part 102A provided at the one end of the outer tube 110A and that constitutes a flow passage enlarging part in which a cross-section area of a flow passage of the gas stream flowing, through the inlet opening part 102A, from the one end of the outer tube 110A toward the other end of the outer tube 110A is enlarged.

The outer tube 110A has a side wall having a portion provided with an outlet opening part 101A. The tube part 120A penetrates through the side wall of the outer tube part 110A at the outlet opening part 101A. The tube part 120A has one end positioned inside the outer tube 110A and the other end positioned outside the outer tube 110A. Both the ends of the tube part 120A are opened, and the tube 120A itself constitutes a flow passage of the gas stream flowing from the inside of the outer tube 110A toward the outside of the outer tube 110A. That is, the one end of the tube part 120A is an inlet part 122A of the gas stream. Meanwhile, the other end of the tube 120A is an outlet part 121A of the gas stream.

The flow straightening device 100A is a device through which a gas stream passes before being introduced into a hydrolysis reaction vessel that causes a hydrolysis reaction of urea water. The tube part 120A supplies, into the hydrolysis reaction vessel, the gas stream coming from the inside of the outer tube 110A. For this, a portion of the tube part 120A which portion is close to the outlet part 121A is connected to the hydrolysis reaction vessel and is used there. The outlet part 121A may be provided with, as needed, a flange for use in connection and fixture of piping as illustrated in the drawings.

In a specific example shown in Embodiment <NUM> in <FIG>, the tube part 120A, which constitutes the flow passage of a gas stream flowing from the inside of the outer tube 110A toward the outside of the outer tube 110A, has a radial cross-section area that is constant along an axial direction of the tube part 120A. The inlet opening part 102A is a minimum portion of the flow passage enlarging part of the outer tube 110A, in which a cross-section area of the flow passage is smaller than that of any other portion of the flow passage enlarging part of the outer tube 110A, and has an area equal to or greater than the radial cross-section area of the tube part 120A. However, there may be a case where the tube part 120A has a radial cross-section area that varies along the axial direction of the tube part 120A. In such a case, the area of the minimum portion of the flow passage enlarging part in which the cross-section area of the flow passage is smaller than that of any other portion only needs to be equal to or greater than a minimum value of the radial cross-section area of the tube part 120A.

As shown in <FIG>, the flow passage structure 100X includes a plurality of flow straightening devices 100A in accordance with an aspect of the present invention being connected in series. One unit of a flow straightening device 100A has one end (inlet opening part 102A) through which a gas stream coming from the outside enters and the other end which is opposite to the one end. The other end of the one unit of the flow straightening device 100A corresponds to one end, through which a gas stream enters, of another flow straightening device 100A positioned downstream of the one unit of the flow straightening device 100A. That is, the other end of the flow straightening device 100A in accordance with Embodiment <NUM> is provided with a control wall 114a that reverses a portion of a gas stream flowing into the outer tube 110A through the one end (inlet opening part 102A) toward the other end.

After being introduced from the one end (inlet opening part 102A) of the outer tube 110A along the axial direction of the outer tube 110A, a gas stream is blocked by an outer peripheral surface of the tube part 120A and consequently makes a detour to avoid the tube part 120A. Then, the gas stream collides with the control wall 114A having an opening (an inlet opening part of a flow straightening device on a downstream side). When the gas stream partially collides with a non-opening portion of the control wall 114A, the gas stream is reversed and flows into the tube part 120A through the inlet part of the tube part 120A. Then, the gas stream introduced into the flow straightening device 100A is partially discharged from the outlet part of the tube part 120A. Drastically changing the flow direction of the gas stream inside the flow straightening device 100A in this manner facilitates agitation and mixing of the gas stream introduced into the flow straightening device 100A, thereby straightening the gas stream and achieving evenness in temperature.

The following description will discuss another embodiment of the present invention. For convenience of description, a member having a function identical to that of a member discussed in the embodiments above is given an identical reference sign, and a description thereof is omitted.

<FIG> is a view of a flow passage structure 100Y including a flow straightening device 100B in accordance with Embodiment <NUM>. <FIG> includes an A-A cross-section view <NUM> of the flow straightening device 100B viewed in a front side and a B-B cross-section view <NUM> of the flow straightening device 100B viewed in a left side. The positions in which the cross sections are taken are indicated in the cross-section views in <FIG>.

The flow straightening device 100B in accordance with Embodiment <NUM> has a distribution plate 242B at a boundary between the flow straightening device 100B and a unit flow straightening device upstream or downstream of the flow straightening device 100B. On this point, the flow straightening device 100B in accordance with Embodiment <NUM> differs from Embodiment <NUM>. The distribution plate 242B is made of a so-called punching board having multiple holes. The distribution plate <NUM> adjusts a gas-stream flow rate ratio between unit flow straightening devices.

One end of an outer tube 110B is provided with a distribution plate 242B constituting a flow passage enlarging part in which a cross-section area of a flow passage of the gas stream flowing, through the one end, into the outer tube 110B toward the other end of the outer tube 110B is enlarged. The multiple holes of the distribution plate 242B constitute an inlet opening part 102B. The other end of the outer tube 110B is provided with a distribution plate 242B functioning as a control wall that reverses at least a portion of the gas stream flowing into the outer tube 110B through the one end toward the other end. Embodiment <NUM> also brings about similar effects given by Embodiment <NUM>.

The following description will discuss more specific configurations of embodiments of the present invention.

<FIG> is a view schematically illustrating a hydrolysis device <NUM> including a flow straightening device <NUM> in accordance with Embodiment <NUM>. The hydrolysis device <NUM> in accordance with Embodiment <NUM> is a device that supplies a gas containing ammonia to a NOx removal catalyst. The hydrolysis device <NUM> includes, in addition to a flow straightening device <NUM>, a burner unit <NUM> and a hydrolysis reaction vessel <NUM>.

The burner unit <NUM> is a device that supplies, to the hydrolysis reaction vessel <NUM>, a high-temperature gas that is required to cause a hydrolysis reaction of urea water. The flow straightening device <NUM> is connected to the burner unit <NUM> and the hydrolysis reaction vessel <NUM> at a location between the burner unit <NUM> and the hydrolysis reaction vessel <NUM>. Preferably, the flow straightening device <NUM> is positioned at a location very close to the hydrolysis reaction vessel <NUM>.

The burner unit <NUM> includes a combustion chamber <NUM> and a burner <NUM>. The burner <NUM> is connected to a fuel line <NUM>. A fuel to be supplied to the burner <NUM> via the fuel line <NUM> can be any of Bunker A heavy oil, Bunker B heavy oil, Bunker C heavy oil, light oil, a gas fuel made of a hydrocarbon gas, and other fuels.

External air from a blower <NUM> is introduced into the combustion chamber <NUM> through an external air line <NUM>, and a fuel is burnt in the combustion chamber <NUM>. In a specific example, the combustion chamber <NUM> has a tubular shape elongated in its axial direction, more preferably a cylindrical shape, and has a bottom provided with the burner <NUM>. In addition, an extraction gas from the exhaust gas from an engine such as a diesel engine is introduced into the combustion chamber <NUM> via a gas extraction line <NUM>, and a combustion gas discharged from the burner unit <NUM> and the extraction gas from the exhaust gas from the engine are mixed in the combustion chamber <NUM>. Then, a resultant mixture gas passes through the flow straightening device <NUM>, and consequently the gas stream is straightened and the degree of unevenness is temperature is improved.

While the hydrolysis device <NUM> is in operation, adjustment is carried out so that the extraction gas is greater in proportion than the combustion gas. The burner unit <NUM> refers to the flow rate and temperature of the gas to be supplied to the hydrolysis reaction vessel <NUM> to regulate the combustion appropriately.

The hydrolysis reaction vessel <NUM> is a device that hydrolyzes urea water in its inside to generate ammonia. The hydrolysis reaction vessel <NUM> is provided with a nozzle <NUM>. The nozzle <NUM> is supplied with the urea water via a supply line <NUM>. The nozzle <NUM> sprays the urea water to a high-temperature gas introduced into the hydrolysis reaction vessel <NUM>. Then, the urea water thus sprayed is hydrolyzed at a high temperature, and consequently ammonia is generated.

In a specific example, the hydrolysis reaction vessel <NUM> has a tubular shape elongated in its axial direction or a polygonal tubular shape whose radial cross-section shape is a square. However, the shape of the hydrolysis reaction vessel <NUM> is not limited to the polygonal tube. Alternatively, the hydrolysis reaction vessel <NUM> may have a cylindrical shape. The hydrolysis reaction vessel <NUM> may include, in its inside, a hydrolysis catalyst that further facilitates the hydrolysis reaction. The hydrolysis reaction vessel <NUM> supplies, through a processed gas line <NUM>, a high-temperature processed gas mixed with ammonia.

<FIG> is a view schematically illustrating a structure of the flow straightening device <NUM> in accordance with Embodiment <NUM>. <FIG> includes an A-A cross-section view <NUM> of the flow straightening device <NUM> viewed in a front side and a B-B cross-section view <NUM> of the flow straightening device <NUM> viewed in a left side. The positions in which the cross sections are taken are indicated in the cross-section views in <FIG>.

The flow straightening device <NUM> includes a housing <NUM> and a tube part <NUM>. In a specific example shown in Embodiment <NUM>, the housing <NUM> has a rectangular parallelepiped shape. The housing <NUM> is hollow in its inside, and has an internal space <NUM> surrounded by the housing <NUM>. The housing <NUM>, which has the rectangular parallelepiped shape, has one side surface (a side surface on the front side) constituting a first side surface <NUM>, which is a side surface close to an outlet.

One side surface intersecting the first side surface <NUM> at right angles constitutes a second side surface <NUM>, which is a side surface close to an inlet of a gas stream. A side surface opposed to the first side surface <NUM> is a third side surface <NUM>. A side surface opposed to the second side surface <NUM> is a fourth side surface <NUM>. The other two side surfaces are a fifth side surface <NUM> (left side surface) and a sixth side surface <NUM> (right side surface). The fifth side surface <NUM> is opposed to the sixth side surface <NUM>.

For convenience of explanation, x-y-z coordinate systems for the housing <NUM> having the rectangular parallelepiped shape are defined as follows. Assuming that the first side surface <NUM> and the third side surface <NUM> are orthogonal to an x-axis, a direction extending from the inside of the housing <NUM> toward the outside of the housing <NUM> over the first side surface <NUM> is referred to as an x-axis positive direction. Assuming that the second side surface <NUM> and the fourth side surface <NUM> are planes orthogonal to a y-axis, a direction extending from the outside of the housing <NUM> toward the inside of the housing <NUM> over the second side surface <NUM> is referred to as a y-axis positive direction. Assuming that the fifth side surface <NUM> and the sixth side surface <NUM> are planes orthogonal to a z-axis, the fifth side surface <NUM> is positioned advanced in a z-axis positive direction more than the sixth side surface <NUM>. In each of the A-A cross-section view <NUM> and the B-B cross-section view <NUM>, the x-y-z coordinate systems are indicated.

The second side surface <NUM> has a portion that is at or close to a center of the second side surface <NUM> and that is provided with an inlet opening part <NUM>. In the specific example shown in Embodiment <NUM>, the inlet opening part <NUM> has a circular shape. This is because that piping (duct) connected to the flow straightening device <NUM> typically has a circular cross-sectional shape. The inlet opening part <NUM> constitutes an introduction port through which a gas is introduced into the flow straightening device <NUM>. With this, while the flow straightening device <NUM> is in use, the gas stream is introduced into the flow straightening device <NUM> through the inlet opening part <NUM> from the outside of the flow straightening device <NUM> so that the gas stream flows in a y-direction. In the specific example shown in Embodiment <NUM>, a second direction, which is a direction of the gas stream introduced from the inlet opening part <NUM>, is the y-direction.

The first side surface <NUM>, the fifth side surface <NUM>, the third side surface <NUM>, and the sixth side surface <NUM> of the housing <NUM> constitute an outer tube. That is, these side surfaces are side walls of the outer tube. An axial direction of the outer tube is in parallel with the y-direction. The second side surface <NUM>, in which the inlet opening part <NUM> is provided, is at one end of the outer tube. The second side surface <NUM>, in which the inlet opening part <NUM> is provided, constitutes a flow passage enlarging part.

The fourth side surface <NUM>, which is opposed to the second side surface <NUM>, is at the other end of the outer tube, and constitutes a control wall that reverses the gas stream flowing into the outer tube through the one end toward the other end. In Embodiment <NUM>, the fourth side surface <NUM>, which is the control wall, is a wall surface without an opening, and closes the other end of the outer tube.

The first side surface <NUM> has a portion that is at or close to a center of the first side surface <NUM> and that is provided with an outlet opening part <NUM>. The tube part <NUM> penetrates through the first side surface <NUM> at the outlet opening part <NUM>. The tube part <NUM> is opened in its both ends, and has a straight tubular shape extending in its axial direction. In the specific example shown in Embodiment <NUM>, the outlet opening part <NUM> has a circular shape, and the tube part <NUM> has a cylindrical shape. In the specific example shown in Embodiment <NUM>, the tube part <NUM> has an inner diameter and an outer diameter that are substantially constant in the axial direction of the tube part <NUM>.

A second end <NUM> of the tube part <NUM>, which penetrates through the first side surface <NUM>, is one end in its axial direction, and is positioned outside the housing <NUM>. A first end <NUM> of the tube part <NUM> is the other end in its axial direction, and is positioned in the internal space <NUM> of the housing <NUM>. That is, the tube part <NUM> is set to the housing <NUM> so as to extend in a first direction from the first end <NUM> toward the first side surface <NUM>.

In the specific example shown in Embodiment <NUM>, the axial direction (first direction) of the tube part <NUM> is orthogonal to the first side surface <NUM> (i.e., in parallel with the x-axis). The second end <NUM> and the first end <NUM> of the tube part <NUM> are on a plane being in parallel with the first side surface <NUM> (i.e., a plane being in parallel with a y-z plane).

In Embodiment <NUM>, the second end <NUM> of the tube part <NUM> constitutes an outlet through which the gas stream is discharged to the outside of the flow straightening device <NUM>. With this, while the flow straightening device <NUM> is in use, the gas stream flows in an x-direction from the inside of the flow straightening device <NUM> toward the outside of the flow straightening device <NUM>. That is, the tube part <NUM> constitutes a flow passage of the gas stream flowing in the first direction from the internal space <NUM> of the housing <NUM> so as to be discharged to the outside. The second end <NUM> of the tube part <NUM> is an outlet part of the tube part <NUM>, and the first end <NUM> is an inlet part. In this case, the gas stream is discharged to the outside through the outlet opening part <NUM> provided in the first side surface <NUM>.

The tube part <NUM>, which constitutes the outlet-side flow passage of the gas stream, penetrates through the first side surface <NUM> so as to protrude into the internal space <NUM>. An outer surface of the tube part <NUM> is positioned so as to block the gas stream being introduced from the inlet opening part <NUM> in the second direction. The tube part <NUM> is partially disposed in a space virtually extended from the inlet opening part <NUM> in the second direction (y-direction) (i.e., in a trajectory along which the inlet opening part <NUM> is virtually moved in the second direction).

Particularly, in Embodiment <NUM>, the inlet opening part <NUM>, which constitutes the introduction port, is set in the housing <NUM> such that a center axis of the inlet opening part <NUM> intersects the tube part <NUM>. Thus, the gas stream introduced from the inlet opening part <NUM> in the second direction includes a center part, and collides with the outer surface of the tube part <NUM>.

Note that, as shown in <FIG>, each of the inlet opening part <NUM>, which constitutes the introduction port, and the second end <NUM> of the tube part <NUM>, which constitutes the outlet of the gas stream, may be provided with a flange for connection and fixing to the piping, as appropriate. Each of the housing <NUM> and the tube part <NUM> of the flow straightening device <NUM> may be made of a stainless steel, but may alternatively be made of another material, particularly another metal.

In an example, the size of the housing <NUM> of the flow straightening device <NUM> may be defined as follows. Each of the first side surface and the second side surface is constituted by sides each being within a range of <NUM> to <NUM>. A ratio of an area of the inlet opening part <NUM> with respect to an area of the second side surface <NUM> is preferably approximately <NUM>% to approximately <NUM>%. A ratio of a cross-section area of a portion of the tube part <NUM> which portion is at or close to the first end <NUM> with respect to an area of the first side surface is preferably approximately <NUM>% to approximately <NUM>%. However, the sizes of the parts of the flow straightening device <NUM> may be designed as appropriate depending on the flow rate of a gas stream to be applied.

While the hydrolysis device <NUM> is in operation, the flow straightening device <NUM> functions as follows. A combustion gas from the burner unit <NUM> and an extraction gas from an exhaust gas from the engine are mixed in the combustion chamber <NUM>, so as to yield a gas stream (a gas stream of an extraction gas heated by the burner unit <NUM>). The gas stream passes through the flow straightening device <NUM> so as to be supplied to the hydrolysis reaction vessel <NUM>. The gas stream being introduced into the flow straightening device <NUM> through the inlet opening part <NUM> and flowing mainly in the second direction, i.e., the y-direction, collides with the outer surface of the tube part <NUM> extending in the x-axis direction, which is the first direction, and makes a detour to flow toward a part behind the tube part <NUM>.

Due to the fourth side surface <NUM>, which is a portion of the housing <NUM> opposed to the inlet opening part <NUM>, the gas stream cannot advance farther in the y-direction, and consequently the direction of the gas stream is changed. That is, the fourth side surface <NUM> changes the direction of the gas stream introduced from the inlet opening part <NUM> in the second direction, and accordingly reverses at least a portion of the gas stream.

In Embodiment <NUM>, the fourth side surface <NUM> constitutes the control wall that controls, in this manner, the direction of the gas stream having been introduced from the inlet opening part <NUM> in the second direction. Thus, in this case, the control wall is disposed at a location where the control wall faces the internal space <NUM>. The entire gas stream changes its flowing direction to an x-axis negative direction, so as to reach the first end <NUM> of the tube part <NUM>.

The gas stream further changes its flowing direction to the x-axis positive direction, so as to enter the tube part <NUM> through the first end <NUM>. The gas stream is then guided by the tube part <NUM>, so as to be discharged from the outlet (the second end <NUM> of the tube part <NUM>). In this manner, the direction of the gas stream is drastically changed in the flow straightening device <NUM>. This facilitates agitation and mixing of the gas stream. In addition, the tube part <NUM> is disposed so as to allow the gas stream to collide with the tube part <NUM> at a location close to the inlet opening part <NUM>. With this, a portion of the gas stream making a detour to avoid the tube part <NUM> may generate a swirl at a location behind the tube part <NUM>. The swirl generated in this manner also facilitates agitation and mixing of the gas stream.

Consequently, the degree of unevenness in temperature of the supplied gas stream is reduced. In addition, even in a case where the gas stream introduced from the inlet opening part <NUM> is a drift, the drift is corrected to rectify unevenness in the flow rate, and is then discharged out of the flow straightening device <NUM>. The gas stream is preferably introduced into the hydrolysis reaction vessel <NUM> immediately after passing through the flow straightening device <NUM>. In such a case, thanks to the small degrees of unevenness in temperature and flow rate of the gas stream, a hydrolysis reaction of urea water inside the hydrolysis reaction vessel <NUM> proceeds reliably.

The inlet opening part <NUM>, which is the introduction port of the flow straightening device <NUM>, is provided in a portion of the second side surface <NUM>. Thus, a cross-section area of the gas stream introduced into the flow straightening device <NUM> is substantially enlarged at the time when the gas stream is introduced into the flow straightening device <NUM>. A cross-section area of the gas stream introduced perpendicularly to the second side surface <NUM>, which is in the second direction, is equal to an area of the inlet opening part <NUM> at the time when the gas stream passes through the inlet opening part <NUM>. Then, at the time when the gas stream is introduced into the housing <NUM>, a flow passage of the gas stream is defined by the side surfaces of the housing, specifically, by the first side surface <NUM>, the third side surface <NUM>, and two side surfaces intersecting the first side surface <NUM> and the second side surface <NUM>. Thus, a cross-section area of the flow passage of the gas stream is enlarged so as to be substantially equal to the area of the second side surface <NUM>.

In addition, at the time when the gas stream is discharged from the flow straightening device <NUM>, the gas stream is narrowed by a flow passage defined by a cross-section area of a portion of the tube part <NUM> which portion is at or close to the first end <NUM> (i.e., the area of the gas stream is reduced so as to be smaller than the area of the first side surface <NUM>). As described above, the cross-section area of the gas stream inside the flow straightening device <NUM> is substantially enlarged. Therefore, even when agitation and mixing of the gas stream is facilitated, the flow straightening device <NUM> would not generate a large exhaust resistance.

Generally, mixing of the gas stream in the piping can be facilitated by employing adequately long piping between devices. However, applying such a technique to the hydrolysis device may cause a heat loss, thereby leading to a reduction in system efficiency of the hydrolysis device. Further, employing the long piping may make it difficult to downsize the hydrolysis device. From the viewpoint of application of the hydrolysis device to transportation equipment such as ships, the downsizing is an important item.

Meanwhile, the flow straightening device <NUM> in accordance with Embodiment <NUM> has a compact box-shape as a whole, and can be installed at a location upstream of and very close to the hydrolysis reaction vessel <NUM>. A heat loss in the flow straightening device <NUM> is small. In addition, in the effort for reducing the degree of unevenness by modifying the piping, various factors such as the length and/or routing (turn) of the piping may affect the degree of unevenness in the gas stream. Thus, it is necessary to deal with different tasks in different application cases. Meanwhile, in a case where the flow straightening device <NUM> is applied, such a problem would not occur.

Providing a known flow straightening member in the piping can be considered as one way to improve the degree of unevenness in the gas stream. Generally, however, this may lead to an increase in exhaust resistance, thereby deteriorating the system efficiency of the hydrolysis device. Meanwhile, the flow straightening device <NUM> would not cause a large exhaust resistance.

As described above, the hydrolysis device <NUM> to which the flow straightening device <NUM> is applied enables: a reduction of an inadequate hydrolysis reaction thanks to improvement in the degree of unevenness of the gas stream; a reduction in energy loss in the hydrolysis device (i.e., a reduction in exhaust resistance, a reduction in heat loss); and downsizing of the hydrolysis device <NUM>.

In the flow straightening device <NUM> in accordance with Embodiment <NUM>, the housing <NUM> has the rectangular parallelepiped shape. The housing having the rectangular parallelepiped shape is favorable in the following points. Specifically, the housing having the rectangular parallelepiped shape can be manufactured easily. In addition, the housing having the rectangular parallelepiped shape may have arrangement in which the introduction port and the outlet for the gas stream are disposed so as to be orthogonal to each other and thus can effectively reduce the degree of unevenness in the gas stream. However, application of the present invention is not limited to cases where the housing has the rectangular parallelepiped shape. Alternatively, the present invention is applicable to cases in which the housing is a solid body having a side surface being in a parallelogram shape or a trapezoid shape. Further alternatively, the housing may be a solid body having, e.g., a spherical shape, an oval shape, a cylindrical shape, or a barrel-shape.

In the example of the flow straightening device <NUM> in accordance with Embodiment <NUM>, the first direction which is a direction of the flow passage of the gas stream flowing to the outside from the internal space <NUM> of the housing <NUM> is perpendicular (at <NUM>°) to the second direction which is a direction of the gas stream flowing toward the internal space <NUM> of the housing <NUM> from the outside through the inlet opening part <NUM>. However, the present invention is not limited to the configuration in which the first direction and the second direction are strictly perpendicular to each other. Alternatively, the first direction and the second direction may be substantially perpendicular to each other, specifically, at an angle of approximately <NUM>° to approximately <NUM>°. This does not affect the effects given by the above configuration.

The present invention is not limited to these examples. The present invention may encompass other configurations, provided that the first direction and the second direction are different directions and a direction of a gas stream in the housing <NUM> can be changed as described above so that a drift is straightened.

As described above, in the specific example of Embodiment <NUM>, the combustion chamber <NUM> of the burner unit <NUM> has the tubular shape elongated in its axial direction. The hydrolysis reaction vessel <NUM> has the tubular shape elongated in its axial direction. In view of this, in order to achieve a compact hydrolysis device <NUM>, the combustion chamber <NUM> of the burner unit <NUM> and the hydrolysis reaction vessel <NUM> are preferably arranged so that their axial directions are in parallel with each other.

However, arrangement of the devices in the hydrolysis device <NUM> is not limited to this. Particularly in a case where there is a limitation on a space, such as a case where the hydrolysis device is installed in transportation equipment such as a ship, it is necessary to design the arrangement of the devices in accordance with the shape of the space of the installation site. Note that an orientation of the hydrolysis reaction vessel <NUM> to be installed may be an orientation with which a gas stream flows in a vertical direction inside the hydrolysis reaction vessel <NUM> (vertical installation), an orientation with which a gas stream flows in a horizontal direction inside hydrolysis reaction vessel <NUM> (horizontal installation), or any of other orientations.

Variation <NUM> is a variation of Embodiment <NUM>, and is similar to Embodiment <NUM> except for a configuration of a flow straightening device. <FIG> is a view schematically illustrating a structure of a flow straightening device <NUM> in accordance with Variation <NUM>. <FIG> includes an A-A cross-section view <NUM> of the flow straightening device <NUM> viewed in a front side (in an x-axis negative direction) and a B-B cross-section view <NUM> of the flow straightening device <NUM> viewed in a left side (in a z-axis negative direction).

In the flow straightening device <NUM>, a separation plate <NUM> having a planar shape is disposed in an internal space <NUM> of a housing <NUM> so as to extend, along a direction in which a tube part <NUM> extends (i.e., a direction perpendicular to a first side surface; an x-axis direction), between a fourth side surface <NUM> and the tube part <NUM>. The separation plate <NUM> is perpendicular to the first side surface <NUM> and to a second side surface <NUM> (i.e., in parallel with an x-y plane).

As described above, the separation plate <NUM> is disposed at a location that is inside the outer tube and that is between the tube part <NUM> and the control wall (fourth side surface <NUM>), and has a planar shape extending in a longitudinal direction (x-axis direction) of the tube part <NUM> and in a direction (y-axis direction) extending from one end of the outer tube toward the other end of the outer tube. The separation plate <NUM> is disposed behind a portion of the outer surface of the tube part <NUM> which portion collides with a gas stream introduced into the flow straightening device <NUM> from the outside of the flow straightening device <NUM> through the inlet opening part <NUM>.

The separation plate <NUM> prevents a phenomenon that a gas stream introduced into the flow straightening device <NUM> flows around the tube part <NUM> plural times, which phenomenon may occur if the gas stream partially includes an extreme drift. In this manner, the separation plate <NUM> improves the degree of unevenness in the flow quantity in both sides partitioned by the separation plate <NUM>. Note that the separation plate <NUM> may be a planar plate that closes a space between the tube part <NUM> and the fourth side surface <NUM> without any gap, but may alternatively be disposed between the tube part <NUM> and the fourth side surface <NUM> with a gap therebetween, as appropriate, within the scope of the purpose of controlling the gas stream.

Variation <NUM> is a variation of Embodiment <NUM>, and is similar to Embodiment <NUM> except for a shape of a tube part of a flow straightening device. <FIG> is a view schematically illustrating a structure of a flow straightening device <NUM> in accordance with Variation <NUM>, and corresponds to the B-B cross-section view <NUM> shown in <FIG>.

In the flow straightening device <NUM>, a tube part <NUM> has a portion which is close to a first end <NUM> and which has a diameter enlarged with increasing proximity to the first end <NUM>. A tapered part <NUM> designed as above allows a gas stream to more smoothly flow from an internal space <NUM> into the tube part <NUM>. Consequently, the gas stream can flow along an inner wall of the tube part <NUM> more smoothly. This can reduce a pressure resistance of the flow, thereby further reducing the degree of unevenness in the flow rate inside the tube part <NUM>. Thus, by adopting a tapered shape such as that of the tube part <NUM>, it is possible to further improve the degree of unevenness in the flow rate of the gas stream supplied to the hydrolysis reaction vessel.

Variation <NUM> is a variation of Embodiment <NUM>, and is similar to Embodiment <NUM> except for a configuration of a flow straightening device. <FIG> is a view schematically illustrating a structure of a flow straightening device <NUM> in accordance with Variation <NUM>, and corresponds to the B-B cross-section view <NUM> shown in <FIG>.

The flow straightening device <NUM> has a housing <NUM> including a third side surface <NUM> having a maintenance opening part <NUM> (manhole) that is opened. The third side surface <NUM> of the housing <NUM> is a side surface of an outer tube and is opposed to a first end <NUM> (inlet part) of a tube part <NUM>. The maintenance opening part <NUM> is closed by a closing plate <NUM> in a normal state. The closing plate <NUM> is detachably fixed to the housing <NUM>, and is configured to be detachable so that a worker can access an internal space <NUM> during maintenance.

The closing plate <NUM> can be fixed to the housing <NUM> by fixing a bolt and a nut to a flange provided in the housing <NUM>. Alternatively, the closing plate <NUM> may be fixed to the housing <NUM> by other method(s). For example, the fixing may be carried out via a bolt and a screw hole provided in the third side surface <NUM> or via a fixing lever provided in the third side surface <NUM>. By employing the maintenance opening part <NUM> and the closing plate <NUM> configured as above, it is possible to provide a flow straightening device that allows easy access to the internal space <NUM> during maintenance.

The description in Configuration Example <NUM> will discuss further details of an aspect of connection between a flow straightening device and a hydrolysis reaction vessel in a hydrolysis device in accordance with an aspect of the present invention. <FIG> is a view schematically illustrating a state in which a piping part <NUM> for connection with a hydrolysis reaction vessel is attached to a flow straightening device <NUM>. The piping part <NUM> has one end connected to a second end <NUM>, which is an outlet of a gas stream, of a tube part <NUM>. In <FIG>, fixing of the piping part <NUM> is carried out via a flange provided at the second end <NUM>.

The piping part <NUM> has the other end connected to an inlet side of the hydrolysis reaction vessel <NUM> having a tubular shape. In Configuration Example <NUM>, the piping part <NUM> has a portion which is close to the inlet side of the hydrolysis reaction vessel <NUM> and which has a cross-section area greater than a cross-section area of an outlet (a second end <NUM> of the tube part <NUM>) of the flow straightening device <NUM>, and accordingly has a shape gradually expanded along a traveling direction of a gas stream (i.e., an x-axis direction). By employing the piping part <NUM> having a cross-sectional shape that gradually changes with increasing proximity to the inlet of the hydrolysis reaction vessel <NUM> from the outlet (the second end <NUM> of the tube part <NUM>) of the flow straightening device <NUM>, it is possible to reduce the degree of unevenness in flow rate of a gas stream to be supplied to the hydrolysis reaction vessel <NUM>, thereby exerting the effect of achieving uniformity.

Configuration Example <NUM> indicates another aspect of connection between a flow straightening device and a hydrolysis reaction vessel, which can be an alternative of Configuration Example <NUM>. <FIG> is a view schematically illustrating a structure of a flow straightening device <NUM> in accordance with Configuration Example <NUM>. The flow straightening device <NUM> has, in its inside, a function of the piping part <NUM> of Configuration Example <NUM>. A first side surface <NUM>, which is close to an outlet of the flow straightening device <NUM>, is actually removed. The whole of the first side surface <NUM> constitutes an outlet opening part <NUM>. The outlet opening part <NUM> is directly connected to a hydrolysis reaction vessel.

A first end <NUM> of a tube part <NUM> of the flow straightening device <NUM> is positioned in an internal space <NUM>. On this point, the flow straightening device <NUM> is the same as the flow straightening device <NUM> in accordance with Embodiment <NUM>. The tube part <NUM> extends from the first end <NUM> toward the first side surface (outlet opening part <NUM>), but does not reach the first side surface <NUM> (outlet opening part <NUM>). A second end <NUM> of the tube part <NUM> is positioned inside a housing of the flow straightening device <NUM>.

The tube part <NUM> has a portion which is close to the first end <NUM> and which has a straight tubular shape, and has another part which extends from an intermediate part of the tube part <NUM> to a second end <NUM> (outlet part) while being enlarged gradually toward the second end <NUM>. That is, in Configuration Example <NUM>, the tube part <NUM> has a tube part enlarging part <NUM> in which a radial cross-section area of the tube part <NUM> is enlarged with increasing proximity to the second end <NUM> (outlet part) from the first end <NUM> (inlet part). In Configuration Example <NUM>, the tube part enlarging part <NUM> functions as the piping part <NUM> of Configuration Example <NUM>.

In Configuration Example <NUM>, the flow straightening device <NUM> includes, in its inside, the function of the piping part for use in connection between the flow straightening device and the hydrolysis reaction vessel. Therefore, the hydrolysis device to which the flow straightening device <NUM> is applied can be made more compact.

The description in Configuration Example <NUM> will discuss an example of a piping part that can be connected to an inlet opening part <NUM> of a flow straightening device in a hydrolysis device. In a case where there is an extreme variation in temperature and/or flow rate in a z-direction (i.e., a direction orthogonal to an axial direction of the tube part <NUM>) in a gas stream coming from the burner unit <NUM> and being to be introduced to the inlet opening part <NUM> of the flow straightening device <NUM> shown in <FIG>, the degree of unevenness may possibly not be improved adequately. Meanwhile, even in a case where there is an extreme variation in temperature in an x-direction (i.e., the axial direction of the tube part <NUM>), a direction of the gas stream is drastically changed in the x-direction inside the flow straightening device <NUM>. Consequently, the gas stream is well agitated and mixed, and therefore the degree of unevenness is likely to be improved.

In view of the above, in a case where there is an extreme variation in temperature and/or flow rate in a certain direction in a gas stream coming from the burner unit <NUM> and being to be introduced to the inlet opening part <NUM> of the flow straightening device <NUM>, it is preferable to set the piping part in the flow straightening device <NUM>. Specifically, a swirl device <NUM> such as the one shown in <FIG> may be connected to the inlet opening part <NUM> of the flow straightening device as needed. With this, the unevenness can be changed into unevenness in a desired direction. The swirl device <NUM> is a piping part that causes the gas stream passing therethrough to swirl around a center axis as the gas stream advances along the swirl device <NUM>.

As shown in <FIG>, the swirl device <NUM> includes a cylindrical part <NUM> and a twisted plate <NUM> disposed inside the cylindrical part <NUM>. The twisted plate <NUM> is a member that divides an internal space of the cylindrical part <NUM> into two and that is twisted about the center axis along an axial direction of the cylindrical part <NUM>. When a radial cross section of the swirl device <NUM> is observed along the center axis, a cross section of the twisted plate <NUM> seems to rotate gradually.

In the swirl device <NUM> shown in <FIG>, the twisted plate <NUM> is twisted so that an angle of <NUM>° is made by a gas-stream inlet side and a gas-stream outlet side of the twisted plate <NUM>. The angle at which the twisted plate <NUM> is twisted may be set as appropriate in accordance with the direction of the unevenness in the inlet opening part <NUM> of the flow straightening device <NUM>.

<FIG> is a view schematically illustrating a hydrolysis device <NUM> including a flow straightening device <NUM> in accordance with Embodiment <NUM>. As shown in <FIG>, the hydrolysis device <NUM> in accordance with Embodiment <NUM> includes two hydrolysis reaction vessels <NUM>. On this point, the hydrolysis device <NUM> in accordance with Embodiment <NUM> differs from the hydrolysis device <NUM> in accordance with Embodiment <NUM>. Thus, the flow straightening device <NUM> in accordance with Embodiment <NUM> has two outlets of a gas stream. Processed gases from the respective hydrolysis reaction vessels <NUM> are merged into one, and the merged gas is supplied to the outside through a processed gas line <NUM>.

<FIG> is a view schematically illustrating a structure of a flow straightening device <NUM>, and corresponds to the B-B cross-section view <NUM> shown in <FIG>. In the flow straightening device <NUM>, a first side surface <NUM> of a housing <NUM> has two outlet opening parts <NUM> arranged side by side in a y-direction (i.e., a direction perpendicular to a second side surface <NUM>). Tube parts <NUM> respectively penetrate through the outlet opening parts <NUM> so as to constitute two outlets (second ends <NUM> of the tube parts <NUM>).

An internal space <NUM> of the housing <NUM> has a distribution plate <NUM> that extends in parallel with a second side surface <NUM> (i.e., in parallel with a z-x plane) and that divides the internal space <NUM> into two. The distribution plate <NUM> is made of a so-called punching board having multiple holes. The distribution plate <NUM> adjusts a flow rate ratio between the gas streams from the two outlets.

For a gas stream that is to be discharged through one of the tube parts <NUM> closer to the inlet opening part <NUM>, the distribution plate <NUM> functions as a control wall that reverses at least a portion of the gas stream introduced from the inlet opening part <NUM> in a second direction. This function corresponds to the effects given by the fourth side surface <NUM> of the flow straightening device <NUM> in accordance with Embodiment <NUM>. Meanwhile, for a gas stream that is to be discharged through the other of the tube parts <NUM> farther from the inlet opening part <NUM>, the distribution plate <NUM> carries out a function corresponding to the inlet opening part <NUM> of the flow straightening device <NUM> in accordance with Embodiment <NUM>.

Embodiment <NUM> also brings about similar effects given by Embodiment <NUM>. According to the configuration in accordance with Embodiment <NUM>, which employs a plurality of hydrolysis reaction vessels <NUM>, it is possible to easily scale up the capacity of the hydrolysis device.

In the flow straightening device <NUM>, a first side surface <NUM> of a housing <NUM> has two outlet opening parts <NUM> arranged side by side in a z-direction (in parallel with a second side surface <NUM>). Tube parts <NUM> respectively penetrate through the outlet opening parts <NUM> so as to constitute two outlets (second ends <NUM> of the tube parts <NUM>). The tube parts <NUM> respectively have center axes positioned on a plane orthogonal to a direction (y-axis direction) extending from one end of an outer tube (the first side surface <NUM>, a fifth side surface <NUM>, a third side surface <NUM>, and a sixth side surface <NUM>) to the other end of the outer tube.

The flow straightening device <NUM> is configured such that a gas stream introduced into an internal space <NUM> of the housing <NUM> in a second direction (y-direction) through an inlet opening part <NUM>, which is provided in a portion of the second side surface <NUM>, is blocked by the tube parts <NUM>. Similarly to Embodiment <NUM>, the tube parts <NUM> are partially disposed in a space virtually extended from the inlet opening part <NUM> in the second direction (y-direction) (i.e., in a trajectory along which the inlet opening part <NUM> is virtually moved in the second direction). However, in Variation <NUM>, a center axis of the inlet opening part <NUM> does not intersect the tube parts <NUM>.

Variation <NUM> is an example in which a flow straightening device has two introduction ports of gas streams. <FIG> is a view schematically illustrating a structure of a flow straightening device <NUM> in accordance with Variation <NUM>. In the flow straightening device <NUM> in accordance with Variation <NUM>, a second side surface <NUM> of a housing <NUM> has an inlet opening part, and, in addition, a side surface (a fifth side surface in the example shown in <FIG>) orthogonal to a first side surface <NUM> and to the second side surface <NUM> has a portion provided with an inlet opening part <NUM>. Consequently, two introduction ports communicating with an internal space <NUM> are given.

The inlet opening part <NUM> is also disposed so as to have a center axis intersecting a tube part <NUM>. With this, a gas stream introduced into the internal space <NUM> through the inlet opening part <NUM> is blocked by an outer peripheral surface of the tube part <NUM>, and a gas stream introduced into the internal space <NUM> through the inlet opening part <NUM> is also blocked by the outer peripheral surface of the tube part <NUM>.

Similarly to the flow straightening device <NUM> shown in <FIG>, the flow straightening device <NUM> can be understood as having an outer tube constituted by the first side surface <NUM>, the fifth side surface <NUM>, the third side surface <NUM>, and the sixth side surface <NUM> of the housing <NUM>. In this case, the second side surface <NUM>, which has the inlet opening part <NUM>, is at one end of the outer tube. The second side surface <NUM>, which has the inlet opening part <NUM>, constitutes a flow passage enlarging part. The fourth side surface <NUM>, which is opposed to the second side surface <NUM>, is at the other end of the outer tube, and constitutes a control wall that reverses the gas stream introduced into the outer tube through the one end toward the other end.

Alternatively, focusing on the additional inlet opening part <NUM>, the flow straightening device <NUM> can be understood as follows. That is, the outer tube is constituted by the first side surface <NUM>, the second side surface <NUM>, the third side surface <NUM>, and the fourth side surface <NUM> of the housing <NUM>. In this case, the fifth side surface <NUM>, which has the inlet opening part <NUM>, is at the one end of the outer tube. The fifth side surface <NUM>, which has the inlet opening part <NUM>, constitutes a flow passage enlarging part. The sixth side surface <NUM>, which is opposed to the fifth side surface <NUM>, is at the other end of the outer tube, and constitutes the control wall that reverses the gas stream introduced into the outer tube through the one end toward the other end. The sixth side surface <NUM>, which is the control wall, is a wall surface without any opening, and closes the other end of the outer tube.

Variation <NUM> is another example in which a flow straightening device has two introduction ports of gas streams. <FIG> is a view schematically illustrating a structure of a flow straightening device <NUM> in accordance with Variation <NUM>. In the flow straightening device <NUM> in accordance with Variation <NUM>, a second side surface <NUM> of a housing <NUM> has two inlet opening parts <NUM>. Consequently, two introduction ports communicating with an internal space <NUM> are given. The two inlet opening parts <NUM> are arranged along a z-axis direction.

Center axes of the inlet opening parts <NUM> intersect a tube part <NUM>. With this, gas streams introduced into the internal space <NUM> through the inlet opening parts <NUM> are blocked by an outer peripheral surface of the tube part <NUM>. In the flow straightening device <NUM>, the fourth side surface <NUM> constitutes a control wall that reverses both the gas streams introduced into the internal space <NUM> through the inlet opening parts <NUM>. Note that the two inlet opening parts <NUM> may alternatively be arranged side by side along an x-axis direction.

Variation <NUM> is further another example in which a flow straightening device has two introduction ports of gas streams. <FIG> is a view schematically illustrating a structure of a flow straightening device <NUM> in accordance with Variation <NUM>. <FIG> includes an A-A cross-section view <NUM> of the flow straightening device <NUM> viewed in a front side (in an x-axis negative direction) and a B-B cross-section view <NUM> of the flow straightening device <NUM> viewed in a left side (in a z-axis negative direction).

In the flow straightening device <NUM> in accordance with Variation <NUM>, a second side surface <NUM> of a housing <NUM> has two inlet opening parts <NUM>. Consequently, two introduction ports communicating with an internal space <NUM> are given. The two inlet opening parts <NUM> are arranged along an axial direction of a tube part <NUM>, i.e., an x-axis direction.

Center axes of the inlet opening parts <NUM> intersect the tube part <NUM>. With this, gas streams introduced into the internal space <NUM> through the inlet opening parts <NUM> are blocked by an outer peripheral surface of the tube part <NUM>. In the flow straightening device <NUM>, the fourth side surface <NUM> constitutes a control wall that reverses both the gas streams introduced into the internal space <NUM> through the inlet opening parts <NUM>.

In a hydrolysis device to which the flow straightening device <NUM> in accordance with Variation <NUM>, the flow straightening device <NUM> in accordance with Variation <NUM>, or the flow straightening device <NUM> in accordance with Variation <NUM> is applied, one of the inlet opening parts may be supplied with a gas stream from a burner unit <NUM>, and the other of the inlet opening parts may be connected to a gas extraction line <NUM>. In this case, the gas extraction line <NUM> may not be connected to the burner unit <NUM>. That is, the extraction gas and the combustion gas may be mixed in the flow straightening device <NUM>,<NUM>,<NUM>.

The description in Embodiment <NUM> will discuss a basic configuration of a NOx removal system to which the hydrolysis device <NUM> in accordance with Embodiment <NUM> is applied. <FIG> is a view schematically illustrating a configuration of a NOx removal system <NUM> in accordance with Embodiment <NUM>. The NOx removal system <NUM> includes the hydrolysis device <NUM> and a NOx removal catalyst <NUM>. The NOx removal system <NUM> includes a gas extraction line <NUM>, a processed gas line <NUM>, an exhaust gas line <NUM>, and an exhaust line <NUM>.

Note that, actually, the lines shown in <FIG> are connected to the hydrolysis device <NUM>. However, for the purpose of avoiding complexity in the drawings, <FIG> shows only the gas extraction line <NUM> and the processed gas line <NUM> out of the lines connected to the hydrolysis device <NUM>. This applies also to the later-described embodiments.

The hydrolysis device <NUM> receives an extraction gas introduced thereto through the gas extraction line <NUM>. A processed gas, which is a high-temperature gas containing ammonia, is supplied to the NOx removal catalyst <NUM> through the processed gas line <NUM>. The NOx removal catalyst <NUM> receives an exhaust gas introduced thereto from an engine such as a diesel engine through the exhaust gas line <NUM>.

The processed gas line <NUM> is merged into the exhaust gas line at a location upstream of a portion where introduction into the NOx removal catalyst <NUM> takes place. Thus, the processed gas from the hydrolysis device <NUM> is mixed in the exhaust gas before being introduced into the NOx removal catalyst <NUM>. The processed gas containing ammonia is mixed in the exhaust gas, and a resultant gas passes through the NOx removal catalyst <NUM>. Consequently, a NOx removal treatment is carried out on the exhaust gas. The exhaust gas thus purified is discharged from the NOx removal catalyst <NUM> through the exhaust line <NUM>.

The description in Embodiment <NUM> will discuss an example of a basic configuration of a NOx removal system to which the hydrolysis device <NUM> in accordance with Embodiment <NUM> is applied. In Embodiment <NUM>, the NOx removal system processes exhaust gases from a plurality of engines. <FIG> is a view schematically illustrating a configuration of a NOx removal system <NUM> in accordance with Embodiment <NUM>. <FIG> shows three engines <NUM> as an example of the plurality of engines.

The NOx removal system <NUM> includes one hydrolysis device <NUM> and three NOx removal catalysts <NUM> respectively provided for the engines <NUM>. The NOx removal system <NUM> includes a gas extraction line <NUM> and a processed gas line <NUM>. The NOx removal system <NUM> further includes three sets of exhaust gas lines <NUM>, exhaust lines <NUM>, and bypass lines <NUM>, respectively provided for the engines <NUM>.

The hydrolysis device <NUM> receives an extraction gas introduced thereto through the gas extraction line <NUM>. A processed gas is supplied to the NOx removal catalysts <NUM> through the processed gas line <NUM>. The NOx removal catalysts <NUM> respectively receive exhaust gases introduced thereto from their corresponding engines <NUM> through the exhaust gas lines <NUM>. The processed gas line <NUM> is branched into a plurality of lines, which are respectively merged into the exhaust gas lines <NUM>. With this, the processed gas from the hydrolysis device <NUM> is mixed in the exhaust gases before being introduced into the NOx removal catalysts <NUM>. The processed gas containing ammonia is mixed in the exhaust gases, and resultant gases pass through the NOx removal catalysts <NUM>. Consequently, a NOx removal treatment is carried out on the exhaust gases. The exhaust gases thus purified are discharged from the NOx removal catalysts <NUM> through the exhaust lines <NUM>, respectively.

From each of the exhaust gas lines <NUM>, a corresponding one of the bypass lines <NUM> is branched off at a location upstream of a part in which a corresponding one of the processed gas lines <NUM> is merged into the each of the exhaust gas lines <NUM>. Each of the bypass lines <NUM> has an end connected to a corresponding one of the exhaust lines <NUM>. The bypass lines <NUM> are piping (bypass mechanism) for causing the exhaust gases from the engines <NUM> to directly flow into the exhaust lines <NUM>, not through the NOx removal catalysts <NUM>.

Valves are respectively provided to (i) a part where each of the bypass lines <NUM> is branched off from a corresponding one of the exhaust gas lines <NUM> and (ii) a part where the each of the bypass lines <NUM> is merged into a corresponding one of the exhaust lines <NUM>. Depending on the operating states of each of the engines <NUM> and the NOx removal system <NUM>, opening and closing of the valves are regulated so as to appropriately control (i) a ratio between a portion of the exhaust gas from the each of the engines <NUM> which portion is caused to pass through a corresponding one of the NOx removal catalysts <NUM> (NOx removal mechanism side) and a portion of the exhaust gas from the each of the engines <NUM> which portion is caused to pass through a corresponding one of the bypass lines <NUM> (bypass mechanism side) and/or (ii) closing of each line. According to Embodiment <NUM>, it is possible to provide a NOx removal system <NUM> that can deal with exhaust gases from a plurality of engines.

An extraction gas to be supplied to the hydrolysis device <NUM> through the gas extraction line <NUM> may be taken at a position in each exhaust gas line <NUM> or each exhaust line <NUM>. The position where the extraction gas is taken can be selected as appropriate on the basis of known techniques. This also applies to the other embodiments and the other configuration examples.

The description in Embodiment <NUM> will discuss another example of a configuration of a NOx removal system to which the hydrolysis device <NUM> in accordance with Embodiment <NUM> is applied. In Embodiment <NUM>, the NOx removal system processes exhaust gases from a plurality of engines. <FIG> is a view schematically illustrating a configuration of a NOx removal system <NUM> in accordance with Embodiment <NUM>. <FIG> shows three engines <NUM> as an example of the plurality of engines.

The NOx removal system <NUM> includes one hydrolysis device <NUM> and one NOx removal catalyst <NUM> provided for the three engines <NUM>. The NOx removal system <NUM> also includes a gas extraction line <NUM> and a processed gas line <NUM>. The NOx removal system <NUM> further includes an exhaust line <NUM>, a bypass line <NUM>, and three exhaust gas lines <NUM> respectively provided for the engines <NUM>. The three exhaust gas lines <NUM> are merged into one, and the merged line is connected to the NOx removal catalyst <NUM>.

The hydrolysis device <NUM> receives an extraction gas introduced thereto through the gas extraction line <NUM>. A processed gas is supplied to the NOx removal catalyst <NUM> through the processed gas line <NUM>. The processed gas line <NUM> is further merged into the merged line into which the three exhaust gas lines <NUM> are merged. With this, the processed gas from the hydrolysis device <NUM> is mixed in the exhaust gas before being introduced into the NOx removal catalyst <NUM>. The processed gas containing ammonia is mixed in the exhaust gas, and a resultant gas passes through the NOx removal catalyst <NUM>. Consequently, a NOx removal treatment is carried out on the exhaust gas. The exhaust gas thus purified is discharged from the NOx removal catalyst <NUM> through the exhaust line <NUM>.

From the exhaust gas line <NUM>, the bypass line <NUM> is branched off at a location upstream of a part in which the processed gas line <NUM> is merged into the exhaust gas line <NUM>. The bypass line <NUM> has an end connected to the exhaust line <NUM>. The bypass line <NUM> is piping (bypass mechanism) for causing the exhaust gases from the engines <NUM> to directly flow into the exhaust line <NUM>, not through the NOx removal catalyst <NUM>.

Valves are respectively provided to (i) a part where the bypass line <NUM> is branched off from the exhaust gas line <NUM> and (ii) a part where the bypass line <NUM> is merged into the exhaust line <NUM>. Depending on the operating states of each of the engines <NUM> and the NOx removal system <NUM>, opening and closing of the valves are regulated so as to appropriately control (i) a ratio between a portion of an exhaust gas from the each of the engines <NUM> that is caused to pass through the NOx removal catalyst <NUM> (NOx removal mechanism side) and a portion of the exhaust gas from the each of the engines <NUM> that is caused to pass through the bypass line <NUM> (bypass mechanism side) and/or (ii) closing of each line. According to Embodiment <NUM>, it is possible to provide a NOx removal system <NUM> that can deal with exhaust gases from a plurality of engines.

Aspects of the present invention can also be expressed as follows:
A flow straightening device in accordance with a first aspect of the present invention is a flow straightening device through which a gas stream passes before being introduced into a hydrolysis reaction vessel that causes a hydrolysis reaction of urea water, the flow straightening device including: an outer tube into which the gas stream flows through one end of the outer tube toward the other end of the outer tube; a control wall positioned inside the outer tube or at the other end of the outer tube, the control wall reversing at least a portion of the gas stream flowing into the outer tube through the one end toward the other end; and at least one tube part which is at least partially positioned at a location that is inside the outer tube and that is between the one end and the control wall, the at least one tube part constituting a flow passage of the gas stream flowing from an inside of the outer tube toward an outside of the outer tube through a side wall of the outer tube so as to introduce the gas stream inside the outer tube into the hydrolysis reaction vessel, the at least one tube part having an inlet part and an outlet part for the gas stream.

A flow straightening device in accordance with a second aspect of the present invention may be configured such that, in the first aspect, the inlet part of the at least one tube part is positioned at a location that is inside the outer tube and that is between the one end and the control wall, the outlet part is positioned outside the outer tube, and the at least one tube part has an outer peripheral surface positioned to block at least a portion of the gas stream flowing into the outer tube through the one end toward the other end.

A flow straightening device in accordance with a third aspect of the present invention may be configured to such that, in the first or second aspect, the flow straightening device further includes a separation plate having a planar shape, the separation plate being disposed at a location that is inside the outer tube and that is between the at least one tube part and the control wall, the separation plate extending in a longitudinal direction of the at least one tube part and in a direction extending from the one end toward the other end.

A flow straightening device in accordance with a fourth aspect of the present invention may be configured such that, in any of the first to third aspects, the at least one tube part has a tube part enlarging part in which a radial cross-section area of the at least one tube part is enlarged with increasing proximity to the outlet part from the inlet part.

A flow straightening device in accordance with a fifth aspect of the present invention may be configured such that, in any of the first to fourth aspects, the one end of the outer tube has a flow passage enlarging part in which a cross-section area of a flow passage of the gas stream flowing into the outer tube through the one end toward the other end is enlarged.

A flow straightening device in accordance with a sixth aspect of the present invention may be configured such that, in the fifth aspect, the flow passage enlarging part has a minimum portion in which a cross-section area of the flow passage is smaller than that of any other portion of the flow passage enlarging part, said at least one tube part has a minimum portion having a radial cross-section area smaller than that of any other portion of said at least one tube part, and the cross-section area of the minimum portion of the flow passage enlarging part is equal to or greater than the radial cross-section area of the minimum portion of said at least one tube part.

A flow straightening device in accordance with a seventh aspect of the present invention may be configured such that, in any of the first to sixth aspects, the outer tube has a side wall which is opposed to the inlet part of the at least one tube part and which is provided with a maintenance opening part and a closing plate that is detachable and that is configured to close the maintenance opening part.

A flow straightening device in accordance with an eighth aspect of the present invention may be configured such that, in any of the first to seventh aspects, the control wall closes the other end of the outer tube.

A flow straightening device in accordance with a ninth aspect of the present invention may be configured such that, in the first or eighth aspect, the at least one tube part includes a plurality of tube parts, and the plurality of tube parts respectively have center axes positioned on a plane substantially orthogonal to a direction extending from the one end of the outer tube toward the other end of the outer tube.

A hydrolysis device in accordance with a tenth aspect of the present invention includes: a flow straightening device described in any of the first to ninth aspects; a hydrolysis reaction vessel that causes a hydrolysis reaction of urea water; and a burner unit configured to burn a fuel so as to supply a heated gas to the flow straightening device.

A hydrolysis device in accordance with an eleventh aspect of the present invention includes: a flow straightening device described in the ninth aspect; a plurality of hydrolysis reaction vessels each of which is configured to cause a hydrolysis reaction of urea water and to receive a gas stream flowing out of a corresponding one of the plurality of tube parts; and a burner unit configured to burn a fuel so as to supply a heated gas to the flow straightening device.

A hydrolysis device in accordance with a twelfth aspect of the present invention may be configured such that, in the tenth or eleventh aspect, the hydrolysis device further includes a swirl device configured to cause a gas stream coming from the burner unit to swirl around a center axis of the outer tube and then to introduce the gas stream into the flow straightening device through the one end of the outer tube.

A hydrolysis device in accordance with a thirteenth aspect of the present invention may be configured such that, in any of the tenth to twelfth aspects, the hydrolysis reaction vessel comprises one or more hydrolysis reaction vessels each of which has a tubular shape elongated in an axial direction of the hydrolysis reaction vessel, the burner unit includes a combustion chamber that burns the fuel, the combustion chamber having a tubular shape elongated in an axial direction of the combustion chamber, and the one or more hydrolysis reaction vessels and the burner unit are arranged so that axial directions of the one or more hydrolysis reaction vessels are in parallel with the axial direction of the combustion chamber.

A NOx removal system in accordance with a fourteenth aspect of the present invention is a NOx removal system that carries out a NOx removal treatment on an exhaust gas from an engine, including: a hydrolysis device described in any of the tenth to thirteenth aspects; and a NOx removal mechanism configured to mix the exhaust gas with a processed gas from the hydrolysis reaction vessel to yield a mixture gas, to introduce the mixture gas into a NOx removal catalyst, and then to discharge a resultant.

A NOx removal system in accordance with a fifteenth aspect of the present invention is a NOx removal system that carries out a NOx removal treatment on exhaust gases from a plurality of engines, including: a hydrolysis device described in any of the tenth to thirteenth aspects; and NOx removal mechanisms and bypass mechanisms respectively provided for the plurality of engines, wherein the NOx removal mechanisms are configured to respectively mix the exhaust gases from the plurality of engines with a processed gas from the hydrolysis reaction vessel to yield mixture gases, to introduce the mixture gases into NOx removal catalysts, and then to discharge resultants; and the bypass mechanisms are configured to respectively cause the exhaust gases from the plurality of engines to bypass the NOx removal mechanisms so as to discharge the exhaust gases.

A NOx removal system in accordance with a sixteenth aspect of the present invention is a NOx removal system that carries out a NOx removal treatment on exhaust gases from a plurality of engines, including: a hydrolysis device described in any of the tenth to thirteenth aspects; and a NOx removal mechanism configured to mix the exhaust gases from the plurality of engines with a processed gas from the hydrolysis reaction vessel to yield a mixture gas, to introduce the mixture gas into a NOx removal catalyst, and then to discharge a resultant; and a bypass mechanism configured to cause the exhaust gases from the plurality of engines to bypass the NOx removal mechanism so as to discharge the exhaust gases.

A flow straightening device in accordance with a seventeenth aspect of the present invention is a flow straightening device through which a gas stream passes before being introduced into a hydrolysis reaction vessel that causes a hydrolysis reaction of urea water, the flow straightening device including: a housing; at least one tube part; and a control wall, wherein the at least one tube part has a first end positioned in an internal space of the housing, the at least one tube part is disposed to extend in a first direction from the first end, the at least one tube part constitutes a flow passage of the gas stream flowing from the internal space of the housing toward an outside of the housing through an outlet opening part, which is provided in a portion of the housing so as to face the first direction from the first end, the housing has, in a portion thereof, an inlet opening part through which the gas stream is introduced from the outside in a second direction toward the internal space of the housing, the control wall is disposed at a location that is opposed to the inlet opening part and faces the internal space or at a position inside the internal space so that the control wall is positioned on a side opposed in the second direction to the inlet opening part across the at least one tube part, at least a portion of the gas stream introduced from the inlet opening part in the second direction is revered by the control wall, and the first direction and the second direction are different directions.

A flow straightening device in accordance with an eighteenth aspect of the present invention is a flow straightening device through which a gas stream passes before being introduced into a hydrolysis reaction vessel that causes a hydrolysis reaction of urea water, the flow straightening device including: a housing; and at least one tube part, wherein the at least one tube part has a first end positioned in an internal space of the housing, the at least one tube part is disposed to extend in a first direction from the first end, the at least one tube part constitutes a flow passage of the gas stream flowing from the internal space of the housing toward an outside of the housing through an outlet opening part, which is provided in a portion of the housing so as to face the first direction from the first end, the housing has, in a portion thereof, an inlet opening part through which the gas stream is introduced from the outside in a second direction toward the internal space of the housing, and the first direction and the second direction are different directions.

A flow straightening device in accordance with a nineteenth aspect of the present invention may be configured such that, in the eighteenth aspect, at least a portion of the gas stream introduced from the inlet opening part in the second direction is reversed by a portion of the housing which portion is opposed to the inlet opening part.

A flow straightening device in accordance with a twentieth aspect of the present invention may be configured such that, in any of the seventeenth to nineteenth aspects, an outer surface of the at least one tube part is positioned so as to block the gas stream being introduced from the inlet opening part in the second direction.

A flow straightening device in accordance with a twenty-first aspect of the present invention may be configured such that, in any of the seventeenth to twentieth aspects, the at least one tube part is at least partially positioned in a space virtually extended from the inlet opening part in the second direction.

A flow straightening device in accordance with a twenty-second aspect of the present invention may be configured such that, in any of the seventeenth to twenty-first aspects, a center axis of the inlet opening part intersects the at least one tube part.

A flow straightening device in accordance with a twenty-third aspect of the present invention may be configured such that, in any of the seventeenth to twenty-second aspects, the gas stream introduced from the inlet opening part in the second direction has a cross-section area that is enlarged when the gas stream is introduced from the inlet opening part into the internal space of the housing.

A flow straightening device in accordance with a twenty-fourth aspect of the present invention may be configured such that, in any of the seventeenth to twenty-third aspects, the first direction and the second direction are substantially perpendicular to each other.

A flow straightening device in accordance with a twenty-fifth aspect of the present invention may be configured such that, in any of the seventeenth to twenty-fourth aspects, the flow straightening device further includes a separation plate having a planar shape, the separation plate being disposed at a location that is in the internal space of the housing and that is opposite to the inlet opening part across the at least one tube part, the separation plate being substantially in parallel with the first direction and the second direction.

A flow straightening device in accordance with a twenty-sixth aspect of the present invention may be configured such that, in any of the seventeenth to twenty-fifth aspects, the at least one tube part has a portion which is close to the first end and which has a diameter enlarged with increasing proximity to the first end.

A flow straightening device in accordance with a twenty-seventh aspect of the present invention may be configured such that, in any of the seventeenth to twenty-sixth aspects, the housing has a portion which is opposed to the outlet opening part and which is provided with a maintenance opening part and a closing plate that is detachable and that is configured to close the maintenance opening part.

A flow straightening device in accordance with a twenty-eighth aspect of the present invention may be configured such that, in any of the seventeenth to twenty-seventh aspects, the at least one tube part includes a plurality of tube parts.

A hydrolysis device in accordance with a twenty-ninth aspect of the present invention includes: a flow straightening device described in any of the seventeenth to twenty-eighth aspects; a hydrolysis reaction vessel that causes a hydrolysis reaction of urea water; and a burner unit configured to burn a fuel so as to supply a heated gas to the flow straightening device.

A hydrolysis device in accordance with a thirtieth aspect of the present invention includes: a flow straightening device described in the twenty-eighth aspect; a plurality of hydrolysis reaction vessels each of which is configured to cause a hydrolysis reaction of urea water and to receive a gas stream flowing out of a corresponding one of the plurality of tube parts; and a burner unit configured to burn a fuel so as to supply a heated gas to the flow straightening device.

A hydrolysis device in accordance with a thirty-first aspect of the present invention may be configured such that, in the twenty-ninth or thirtieth aspect, the hydrolysis device further includes a swirl device configured to cause a gas stream coming from the burner unit to swirl around a center axis of the inlet opening part so as to be introduced into the flow straightening device through the inlet opening part.

A hydrolysis device in accordance with a thirty-second aspect of the present invention may be configured such that, in any of the twenty-ninth to thirty-first aspects, the hydrolysis reaction vessel comprises one or more hydrolysis reaction vessels each of which has a tubular shape elongated in an axial direction of the hydrolysis reaction vessel, the burner unit includes a combustion chamber that burns the fuel, the combustion chamber having a tubular shape elongated in an axial direction of the combustion chamber, and the one or more hydrolysis reaction vessels and the burner unit are arranged so that axial directions of the one or more hydrolysis reaction vessels are in parallel with the axial direction of the combustion chamber.

A NOx removal system in accordance with a thirty-third aspect of the present invention is a NOx removal system that carries out a NOx removal treatment on an exhaust gas from an engine, including: a hydrolysis device described in any of the twenty-ninth to thirty-second aspects; and a NOx removal mechanism configured to mix the exhaust gas with a processed gas from the hydrolysis reaction vessel to yield a mixture gas, to introduce the mixture gas into a NOx removal catalyst, and then to discharge a resultant.

A NOx removal system in accordance with a thirty-fourth aspect of the present invention is a NOx removal system that carries out a NOx removal treatment on exhaust gases from a plurality of engines, including: a hydrolysis device described in any of the twenty-ninth to thirty-second aspects; and NOx removal mechanisms and bypass mechanisms respectively provided for the plurality of engines, wherein the NOx removal mechanisms are configured to respectively mix the exhaust gases from the plurality of engines with a processed gas from the hydrolysis reaction vessel to yield mixture gases, to introduce the mixture gases into NOx removal catalysts, and then to discharge resultants, and the bypass mechanisms are configured to respectively cause the exhaust gases from the plurality of engines to bypass the NOx removal mechanisms so as to discharge the exhaust gases.

Claim 1:
A flow straightening device (<NUM>) through which a gas stream passes before being introduced into a hydrolysis reaction vessel (<NUM>) that causes a hydrolysis reaction of urea water, said flow straightening device (<NUM>) comprising:
an outer tube (<NUM>) into which the gas stream flows through one end of the outer tube (<NUM>) toward the other end of the outer tube (<NUM>) which is opposite to the one end;
a control wall (<NUM>) positioned inside the outer tube (<NUM>) or at the other end of the outer tube (<NUM>), the control wall (<NUM>) reversing at least a portion of the gas stream flowing into the outer tube (<NUM>) through the one end toward the other end; and
at least one tube part (<NUM>) which is at least partially positioned at a location that is inside the outer tube (<NUM>) and that is between the one end and the control wall (<NUM>), said at least one tube part (<NUM>) constituting a flow passage of the gas stream flowing from an inside of the outer tube (<NUM>) toward an outside of the outer tube (<NUM>) through a side wall (<NUM>) of the outer tube (<NUM>) so as to introduce the gas stream inside the outer tube (<NUM>) into the hydrolysis reaction vessel (<NUM>), said at least one tube part (<NUM>) having an inlet part (<NUM>) and an outlet part (<NUM>) for the gas stream.