Patent Description:
There is a conventionally-known system for cleaning emissions by decomposing nitrogen oxides contained in the emissions into nitrogen and water through a selective catalytic reduction (SCR) using, as a reducing agent, ammonia (NH<NUM>) obtained by hydrolyzing an aqueous urea solution. What is being demanded in such a system is an improvement in the efficiency of a hydrolysis reaction of an aqueous urea solution to form ammonia by spraying the catalyst with the aqueous urea solution.

A variety of nozzles for misting a liquid over a spray target object are put into practical use. For example, Patent Literature <NUM> discloses a fluid spray nozzle having two orifices disposed parallel to each other in a width direction thereof and for spraying a fluid from each of the orifices.

[Patent Literature <NUM>] <CIT>. <CIT> relates to an injection nozzle for supplying reducing agent. <CIT> relates to a selective catalytic reduction system. <CIT> relates to a system for preventing the urea crystal formation. <CIT> relates to a reducing agent injection nozzle. <CIT> relates to a two-substance nozzle for atomizing a liquid.

The inventors have found that it is important, for a method of efficiently hydrolyzing an aqueous urea solution into NH<NUM>, to evenly spray an aqueous urea solution on a certain cross-sectional surface of a spray target object, which is a catalyst. The inventors tried to achieve such spraying by using the nozzle as described above.

However, when three or more spraying parts are provided in the nozzle as described above, the amount of liquid adhering to a spray target surface can vary from position to position. Therefore, there still remains room for improvement in evenness of an adhesion amount of a liquid sprayed on a spray target object by using a conventional nozzle.

It is an object of an aspect of the present invention to improve evenness of an adhesion amount of a liquid sprayed on a spray target object by using a nozzle including three or more spraying parts.

In order to solve the above problem, provided is a nozzle in accordance with an aspect of the present invention including the features of claim <NUM>.

An aspect of the present invention enables an improvement in evenness of an adhesion amount of a liquid sprayed on a spray target object by using a nozzle including three or more spraying parts.

The following description will discuss an embodiment of the present invention with reference to <FIG> in detail. <FIG> is a view schematically illustrating a configuration of a hydrolyzing device <NUM>, including a container <NUM>, in accordance with Embodiment <NUM> of the present invention. <FIG> is a view schematically illustrating a nozzle <NUM> of the container <NUM>. <FIG> is a cross-sectional view of a section taken along line A-A' of the nozzle <NUM> illustrated in <FIG>. <FIG> is a cross-sectional view illustrating an internal structure of a spraying part <NUM> of the nozzle <NUM>. <FIG> is a view illustrating how a liquid <NUM> adheres to a spray target surface P on which the liquid <NUM> has been sprayed by using the nozzle <NUM>.

The hydrolyzing device <NUM> in accordance with Embodiment <NUM> is a device for cleaning emissions by supplying a denitration catalyst with a gas containing ammonia (NH<NUM>) and decomposing nitrogen oxides contained in the emissions into nitrogen and water through a selective catalytic reduction (SCR) reaction using, as a reducing agent, the ammonia. As illustrated in <FIG>, the hydrolyzing device <NUM> includes the container <NUM>, a bleed air line <NUM>, a treatment gas line <NUM>, and a heater (not illustrated).

The heater heats a bleed air of exhaust from an engine such as a diesel engine. The bleed air having been heated is supplied to the container <NUM> through the bleed air line <NUM>.

The container <NUM> is a device for hydrolyzing the liquid <NUM> inside the container <NUM> to generate ammonia. For example, the liquid <NUM> is an aqueous urea solution. The container <NUM> stores a spray target object <NUM>, which is a catalyst for accelerating a hydrolysis reaction. The container <NUM> includes the nozzle <NUM> for spraying the spray target object <NUM> with the liquid <NUM>. The container <NUM> further includes a pipe <NUM> for supporting the nozzle <NUM> and supplying the nozzle <NUM> with the liquid <NUM>. The nozzle <NUM> is supplied with the liquid <NUM> through the pipe <NUM>.

The nozzle <NUM> sprays the spray target object <NUM> with the liquid <NUM>. The liquid <NUM> having been sprayed is hydrolyzed by a hot gas (bleed air) introduced into the container <NUM> to form ammonia.

The container <NUM> has a shape that include, as a specific example, the shape of an axially long tube, such as the shape of a rectangular tube that is substantially square in a cross section perpendicular to an extending direction thereof. However, the container <NUM> is not limited to the shape of a rectangular tube, but may be cylindrical. The container <NUM> supplies, through the treatment gas line <NUM>, a hot treatment gas into which ammonia has been mixed.

The nozzle <NUM>, which is provided in the container <NUM>, is a liquid spray nozzle for spraying (misting) the liquid <NUM> in the form of mist, over a spray target surface P of the spray target object <NUM>. As illustrated in <FIG>, the nozzle <NUM> includes: a nozzle body <NUM> connected to the pipe <NUM>; and at least three spraying parts <NUM> for spraying the liquid <NUM>. Described as an example in Embodiment <NUM> is a case where the nozzle body <NUM> includes, as a spraying part <NUM>, three spraying parts: a spraying part 13A; a spraying part 13B; and a spraying part 13C.

The spraying parts 13A to 13C have the same structure. Therefore, in the following description, only the structure of the spraying part 13A is described and the descriptions of the structures of the spraying part 13B and the spraying part 13C will be omitted. <FIG> is a cross-sectional view illustrating the structure of the spraying part 13A of the nozzle <NUM>. As illustrated in <FIG>, the spraying part 13A includes: a liquid spray hole <NUM>; a gas supply portion <NUM>; and gas ejecting parts <NUM> (route control part) paired together. The liquid spray hole <NUM> is a circular opening provided in the spraying part <NUM>. The liquid spray hole <NUM> is connected to a liquid passage <NUM> inside the pipe <NUM>, and sprays the liquid <NUM> carried by the liquid passage <NUM>.

The gas supply portion <NUM> includes: gas spray holes <NUM> serving as spray holes; and gas passages <NUM>. The gas spray holes <NUM> are a pair of openings located near the liquid spray hole <NUM>. The gas passages <NUM> are connected to a gas passage inside the pipe <NUM>. The gas passages <NUM> supply a gas <NUM> carried by the gas passage to the gas spray holes <NUM>, which spray the gas <NUM> toward the liquid <NUM> sprayed from the spraying part <NUM>. This makes the particle diameter of the liquid <NUM> sprayed from the liquid spray hole <NUM> smaller, so that the liquid <NUM> becomes misty.

The gas ejecting parts <NUM> are a mechanism for controlling a region (hereinafter, referred to also as adhesion region) formed through adhesion, to the spray target surface P, of the liquid <NUM> sprayed from the spraying part <NUM>. Note that the spray target surface P is a flat surface substantially perpendicular to a direction in which the nozzle body <NUM> is viewed in a plan view.

The gas ejecting parts <NUM> control a route of a liquid sprayed from the liquid spray hole <NUM> by blowing a gas toward the liquid sprayed from the liquid spray hole <NUM>. The gas ejecting parts <NUM> include: gas spray holes <NUM>; and gas passages <NUM>. Each of the gas ejecting parts <NUM> paired together includes corresponding one of the gas spray holes <NUM>.

The gas spray holes <NUM> are a pair of openings provided near the end of the spraying part 13A, on a straight line L (a straight line denoted by a sign L in <FIG>) connecting a center point <NUM> (see <FIG>) of the nozzle body <NUM> and the spraying part 13A. As illustrated in <FIG>, the gas spray holes <NUM> paired together are disposed such that the liquid spray hole <NUM> is placed therebetween on the straight line L. In other words, the gas spray holes <NUM> paired together are provided in an outer circumferential part of the spraying part 13A and also on a straight line L passing through the center of the nozzle body <NUM> and the liquid spray hole <NUM>.

The gas passages <NUM> are connected to another gas passage that is different from the gas passage connected to the gas passages <NUM> and that is provided inside the pipe <NUM>. The gas passages <NUM> supply the gas spray holes <NUM> with a gas <NUM> carried by the other gas passage. It should be noted that the gas passages <NUM> and the gas passages <NUM> can be connected to the same gas passage provided inside the pipe <NUM>. In such a case, the gas spray holes <NUM> and the gas spray holes <NUM> are supplied with the gas <NUM> carried by the same gas passage.

The gas spray holes <NUM> spray, with the gas <NUM> supplied by the gas passages <NUM>, the liquid <NUM> that have been sprayed and have become misty. Note that the gas <NUM> and the gas <NUM> sprayed from the gas spray holes <NUM> and the gas passage <NUM>, respectively are not limited to any particular types. The gas <NUM> and the gas <NUM> may be, for example, air.

The three spraying parts <NUM> are disposed so as not to be located in line with each other when seen from a third direction (a direction represented by an arrow <NUM> in <FIG>) that is perpendicular to the spray target surface P. Specifically, the three spraying parts <NUM> are disposed on the circumference of the same circle having a center which is the center point <NUM> (a position represented by a dot <NUM> in <FIG>), which is the center of the nozzle body <NUM>, when seen from the third direction (in other words, in the plan view, from a position where the three spraying parts <NUM> are disposed, of the nozzle body <NUM>).

The three spraying parts <NUM> are disposed so as to be spaced at regular intervals. In other words, the three spraying parts <NUM> are disposed so as to form a regular triangle when seen from the third direction. Further, the three spraying parts <NUM> are disposed so as to be inclined with respect to a plane perpendicular to the third direction, so that, when seen from the third direction, the liquid is sprayed in directions from the center point <NUM> of the nozzle body <NUM> to the spraying parts <NUM> (for example, the direction represented by an arrow <NUM> in a case of the spraying part 13B in <FIG>).

According to the nozzle <NUM> of Embodiment <NUM>, with the pressure of the gas <NUM> sprayed by the gas spray holes <NUM> of the gas ejecting parts <NUM>, the liquid <NUM> sprayed from the liquid spray hole <NUM> is deformed to be flattened (oval) as a whole, so as to be shorter in a direction in which the gas spray holes <NUM> face each other and longer in a direction perpendicular to the direction in which the gas spray holes <NUM> face each other. This means the gas ejecting parts <NUM> control a route of the liquid such that an adhesion region S is shorter in a first direction outward from a central part of a group of the plurality of adhesion regions S than in a second direction perpendicular to the first direction.

The configuration described above makes flattened (oval) the adhesion region S (a region denoted by a sign S in <FIG>) of the liquid <NUM> that is sprayed from each of the spraying parts <NUM> and then adheres to the spray target surface P, as illustrated in <FIG>. In other words, the adhesion region S is shorter in a first direction (a direction represented by an arrow <NUM> in <FIG>) outward from the center (center point <NUM>) of the nozzle body <NUM> than in a second direction (a direction represented by an arrow <NUM> in <FIG>) perpendicular to the first direction.

As illustrated in <FIG>, a region T (referred to as an adhesion region T) is a group of the adhesion regions S, in which the liquid having been sprayed from the three spraying parts <NUM> adheres to the spray target surface P. In the region T, an end part of one adhesion region S (a region denoted by S in <FIG>) produced by one of the spraying parts <NUM> overlaps an end part of another adhesion region S produced by another one of the spraying parts <NUM>. The gas ejecting parts <NUM> control the route of the liquid such that the adhesion region S is shorter in the first direction outward from the central part of the adhesion region T than in the second direction perpendicular to the first direction.

Since the spray region S generated by a single spraying part <NUM> is flattened, an adhesion amount of the liquid <NUM> is likely to be reduced, in particular, in end parts thereof in a longitudinal direction. However, according to the nozzle <NUM>, the three spraying parts <NUM> generate the spray regions S each having end parts that overlap end parts of the other spray regions S. This reduces variation in the adhesion amount of the liquid <NUM> within the spray region T.

Each of the spraying parts <NUM> is inclined outward from the nozzle body <NUM>. The spraying parts <NUM> therefore spray the liquid <NUM> in a direction outward from the nozzle body <NUM>. This reduces the variation in the adhesion amount of the liquid <NUM> within the adhesion region S more than in a case where the spraying parts <NUM> point in the third direction.

In a case where the spraying parts <NUM> face, in the third direction, the spray target object <NUM> that has a honeycomb structure, the liquid <NUM> sprayed from the spraying parts <NUM> is mostly sprayed substantially in the third direction. In this case, the liquid <NUM> mostly passes through the inside of the honeycomb structure of a catalyst, which is the spray target object <NUM>, without touching the inner wall surface of the honeycomb structure. This could reduce the efficiency of a catalyzed reaction.

In contrast, according to the nozzle <NUM> in accordance with Embodiment <NUM>, each of the spraying parts <NUM> is inclined outward from the nozzle body <NUM>. This causes the liquid <NUM> sprayed from the spraying parts <NUM> to be sprayed in a direction inclined with respect to the third direction. Accordingly, the liquid <NUM> mostly touches the inner wall surface of the honeycomb structure of the spray target object <NUM>. This improves the efficiency of the catalyzed reaction.

In the spraying parts <NUM>, the flattened shape is adjusted by means of wind pressure of a gas jetted from the gas spray holes <NUM>. This enables adaptation by changing the wind pressure without changing the structure of the spraying parts <NUM>, even in a case where a condition such as the size of the spray target surface P is changed.

The route control part described in Embodiment <NUM> has the configuration that involves the gas ejecting parts <NUM>. However, a method for controlling the shape of the adhesion region S is not limited to this. For example, the route control part may be a liquid spray hole <NUM> that is deformed to be flattened so that the adhesion region S is adjusted to be flattened.

The following description will discuss another embodiment of the present invention with reference to <FIG>. For the convenience of description, a member having the same function as the member already described in Embodiment <NUM> is assigned with the same reference sign, and the description thereof is omitted. <FIG> is a view schematically illustrating a nozzle 2A in accordance with Embodiment <NUM> of the present invention. <FIG> is a cross-sectional view of a section taken along line B-B' of the nozzle 2A illustrated in <FIG>. <FIG> is a view illustrating a spray target surface P on which a liquid <NUM> has been sprayed by using the nozzle 2A.

As illustrated in <FIG>, the nozzle 2A in accordance with Embodiment <NUM> of the present invention includes, as a spraying part <NUM>, four spraying parts: spraying parts 13A, 13B, 13C, and 13D. The four spraying part 13A to 13D are disposed so as not to be located in line with each other when viewed from a third direction perpendicular to the spray target surface P. Specifically, the four spraying parts <NUM> are disposed on the circumference of the same circle having a center which is a center point <NUM> of a nozzle body <NUM> when seen from the third direction.

The four spraying parts <NUM> are disposed so as to be spaced at regular intervals. In other words, the four spraying parts <NUM> are disposed so as to form a regular triangle when seen from the third direction. Further, the four spraying parts <NUM> are disposed so as to be inclined with respect to a plane perpendicular to the third direction, so that, when seen from the third direction, the liquid is sprayed in directions from the center point <NUM> of the nozzle body <NUM> to the spraying parts <NUM>.

Claim 1:
A nozzle comprising:
a nozzle body (<NUM>); and
at least three spraying parts (<NUM>, 13A, 13B, 13C, 13D) provided in the nozzle body (<NUM>) and for spraying a liquid (<NUM>) on a spray target surface (P), wherein the liquid (<NUM>) is an aqueous urea solution (<NUM>),
the at least three spraying parts (<NUM>, 13A, 13B, 13C, 13D) being disposed so as not to be in line with each other in a plan view, from a position where the at least three spraying parts (<NUM>, 13A, 13B, 13C, 13D) are disposed, of the nozzle body (<NUM>),
the at least three spraying parts (<NUM>, 13A, 13B, 13C, 13D) each including:
a spray hole (<NUM>) through which the liquid (<NUM>) is sprayed outward from the nozzle body (<NUM>); and
a route control part (<NUM>) for controlling a route of the liquid (<NUM>) sprayed from the spray hole (<NUM>),
wherein the nozzle (<NUM>, 2A) comprises, as the route control part (<NUM>), gas ejecting parts (<NUM>) paired together for blowing a gas toward the liquid (<NUM>) sprayed from the spray hole (<NUM>),
the liquid (<NUM>) sprayed from the spray hole (<NUM>) adhering to the spray target surface (P) to form an adhesion region (S), and
the route control part (<NUM>) controlling the route of the liquid (<NUM>) such that the adhesion region (S) is shorter in a first direction (<NUM>) outward from a central part of a group of a plurality of adhesion regions (S), the plurality of adhesion regions (S) each being the adhesion region (S), than in a second direction (<NUM>) perpendicular to the first direction (<NUM>).