WO2015151744A1

WO2015151744A1 - Device for purifying exhaust gas, and method for operating same

Info

Publication number: WO2015151744A1
Application number: PCT/JP2015/057225
Authority: WO
Inventors: 博仲田中; 俊介平岩; 諒平小林
Original assignee: 日立造船株式会社
Priority date: 2014-03-31
Filing date: 2015-03-12
Publication date: 2015-10-08
Also published as: JP2015190458A

Abstract

　Catalyst units (31, 32) are installed in an upstream part and a downstream part of a reaction container (11), each of the catalyst units (31, 32) forming an air gap (14) for creating a turbulent flow by the sudden expansion of a flow channel between an upstream-side catalyzer (21) and a downstream-side catalyzer (22). Upstream of the upstream-side catalyst unit (31), an upstream soot-blowing device (51) is provided for spraying soot-blowing gas along with exhaust gas (10) onto the upstream-side catalyzer (21), and downstream of the downstream-side catalyst unit (32), a downstream soot-blowing device (52) is provided for spraying soot-blowing gas toward the downstream-side catalyzer (22) in a direction opposite that of the exhaust gas. Between the upstream-side catalyst unit (31) and the downstream-side catalyst unit (32) is provided a composite soot-blowing device (53) for spraying soot-blowing gas toward both the downstream-side catalyzer (22) of the upstream-side catalyst unit (31) and the upstream-side catalyzer (21) of the downstream-side catalyst unit (32).

Description

Exhaust gas purification device and operation method thereof

The present invention relates to an exhaust gas purification device that removes exhaust gas discharged from an internal combustion engine by contacting a catalyst and reducing pollutants contained in the exhaust gas, and an operation method thereof.

Conventionally, in an SCR denitration apparatus using an ammonia selective catalyst reduction method in which, for example, ammonia gas or urea water is blown into exhaust gas of an exhaust gas line and brought into contact with a denitration catalyst, a stack of catalysts laminated in a honeycomb shape is formed in a reaction vessel. On the other hand, reducing agents such as ammonia gas and urea are blown into the exhaust gas from the inlet side and introduced into the laminate. For example, Patent Document 1 proposes a method in which a plurality of catalyst units made of a laminate are installed with a predetermined space. According to this patent document 1, by discharging into the predetermined space from the flow path of a laminated body, a flow path is expanded rapidly, a turbulent flow is generated, and the catalyst contact efficiency of exhaust gas and a reducing agent can be improved. it can.

Incidentally, Patent Document 2 discloses a device in which a soot blower is disposed on the inlet side of each catalyst layer in order to remove dust adhering to the surface of the catalyst.

Japanese Patent Laid-Open No. 8-144475 Japanese Laid-Open Patent Publication No. 5-309233

However, as described in Patent Document 1, in order to increase the contact efficiency between the exhaust gas and the catalyst, when a plurality of catalyst units are installed with a predetermined space (void), soot blow is performed as described in Patent Document 2. Even if soot blow is performed from the inlet side of the catalyst layer by the apparatus, the soot blow gas is diffused by the space, and there is a problem that the ability to remove and remove dust attached to the surface of the second and subsequent catalyst units is greatly reduced. In order to solve this problem, it is conceivable to install a soot blower on the upstream side of each catalyst unit. However, the space required for diffusing and mixing the exhaust gas is 10 to 15 mm. The injection distance from the nozzle port to the catalyst unit is required to be 300 to 500 mm. As a result, there has been a problem that the space for the reaction vessel cannot be saved.

The present invention solves the above-described problems, makes it possible to effectively contact the exhaust gas and the catalyst, achieves space saving, and effectively removes dust adhering to the catalyst surface and It aims at providing the driving method.

The invention described in claim 1
Two catalyst bodies made of stacked catalysts are arranged on the upstream side and the downstream side in a reaction vessel that sends exhaust gas from the upstream side to the downstream side, and between the upstream side catalyst body and the downstream side catalyst body. In addition, a catalyst unit with a gap that creates a turbulent flow by rapidly expanding the exhaust gas flow path is installed,
In the upstream part of the catalyst unit, an upstream soot blow device having a nozzle port for injecting soot blow gas to the upstream catalyst body along the exhaust gas flow is provided,
A downstream soot blower having a nozzle port for injecting soot blow gas toward the downstream catalyst body in the reverse direction of the exhaust gas flow is provided in the downstream portion of the catalyst unit.

The invention according to claim 2 is the invention according to claim 1,
In the reaction vessel, a plurality of catalyst units are installed in series in the exhaust gas flow direction,
A downstream soot blower arranged on the downstream side of the upstream catalyst unit and an upstream soot blower arranged on the upstream side of the catalyst unit adjacent to the downstream side are integrated to form nozzle ports on the upstream side surface and the downstream side surface, respectively. It is characterized by comprising the combined soot blow device.

The invention described in claim 3 is the configuration described in claim 2,
The upstream soot blow device and the downstream soot blow device are constituted by a plurality of soot blow pipes arranged in parallel to each other at a predetermined interval along the cross section of the exhaust gas flow, and have a length on the upstream side surface or the downstream side surface of these soot blow pipes. Nozzle openings are formed at a predetermined pitch in the direction,
The composite soot blow device is composed of a plurality of soot blow pipes arranged in parallel with each other at a predetermined interval along the cross section of the exhaust gas flow, and a plurality of nozzle ports are provided on the upstream side surface and the downstream side surface of the soot blow pipe, respectively. Each is formed at a predetermined pitch in the length direction.

According to a fourth aspect of the present invention, in the configuration of the third aspect,
The composite soot blow pipe is characterized in that the diameter of the nozzle port opened on the upstream side surface is larger than the nozzle port opened on the downstream side surface.

The invention according to claim 5
A method for operating the purification device according to any one of claims 1 to 4,
The soot blow gas is jetted in a pulse form that repeats jetting and stopping at regular intervals from the nozzle opening.

According to the first aspect of the present invention, the exhaust gas passing through the upstream catalyst body is rapidly expanded in the flow path by the air gap by the catalyst unit having a pair of catalyst bodies arranged upstream and downstream with a gap. As a result, the exhaust gas is effectively brought into contact with the surface of the downstream catalyst body, and the harmful substances contained in the exhaust gas are effectively reduced and purified. Then, the soot blow gas is blown into the upstream catalyst body at predetermined intervals along the exhaust gas flow direction from the nozzle port of the upstream soot blow device disposed upstream of the catalyst unit with respect to the upstream catalyst body. At the same time that dust is removed, soot blow gas is directed to the downstream catalyst body from the nozzle port of the downstream soot blow device disposed downstream of the catalyst unit in the direction opposite to the exhaust gas flow direction. Remove blown dust.

Thus, even with a catalyst unit in which a pair of catalyst bodies are arranged with a gap therebetween to achieve high contact efficiency between exhaust gas and catalyst and space saving, the soot blow gas blown from both sides of the upstream and downstream portions Thus, the dust adhering to the surface of the catalyst body can be effectively peeled off.

According to the second aspect of the present invention, when a plurality of catalyst units are installed in series in the reaction vessel, the downstream catalyst body of the upstream catalyst unit and the upstream catalyst body of the downstream catalyst unit In addition, since the composite soot blow device for injecting the soot blow gas is provided, the number of parts and the space occupied by the reaction vessel can be reduced.

According to the invention described in claim 3, since the plurality of soot blow pipes are arranged in parallel, the nozzle ports can be arranged evenly facing the exhaust gas unit, and the dust adhering to the surface of the catalyst body is peeled off and removed satisfactorily. can do.

According to the invention described in claim 4, since the diameter of the nozzle port opened on the upstream side surface is formed larger than the diameter of the nozzle port on the downstream side surface in the composite soot blow pipe, the soot blow gas injected against the exhaust gas Can be ejected with large energy, and dust adhering to the surface of the catalyst body can be effectively removed.

According to the invention described in claim 5, by injecting soot blow gas in a pulse shape, shock waves can be repeatedly injected on the surface of the catalyst body, and dust can be effectively peeled and removed.

It is a vertical longitudinal cross-sectional view of the reaction container of the SCR denitration apparatus which concerns on the Example of this invention. It is a horizontal longitudinal cross-sectional view of the same reaction container. It is a partial expanded longitudinal cross-sectional view which shows arrangement | positioning of reaction container. It is a time chart of the soot blow gas control valve which shows the injection state of soot blow gas.

Embodiments of an exhaust gas purifying apparatus and its operating method according to the present invention will be described below with reference to the drawings.
In FIG. 1 and FIG. 2, 11 is a reaction vessel of an SCR denitration device installed in an exhaust gas path for discharging exhaust gas from a large diesel engine of a ship, for example. In an evaporator (not shown) installed on the upstream side of the reaction vessel 11 in the exhaust gas path, ammonia gas or urea water as a reducing agent is blown into the exhaust gas, and a mixed gas containing the reducing agent in the exhaust gas ( Hereinafter, the exhaust gas 10 is sent from the inlet (upstream side) 1 to the outlet (downstream side) 9 of the reaction vessel 11.

In the reaction vessel 11,

catalyst bodies

21 and 22 are formed by catalysts stacked in a honeycomb shape, and an upstream side catalyst unit 31 and a downstream side catalyst unit 32 composed of a pair of front and

rear catalyst bodies

21 and 22 are provided. Multiple sets (two sets in the figure) are installed in series. The upstream side catalyst body 21 and the downstream side catalyst body 22 of these

catalyst units

31 and 32 are cross-sectional shapes that cover the cross section of the reaction vessel 11 and have a predetermined thickness, and the upstream side catalyst body 21 and the downstream side catalyst body 21. Gaps 14 are respectively formed between the catalyst bodies 22. The interval 14D, which is the upstream / downstream width of the gap 14, is effective to be at least three times the one side of the honeycomb shape of the

catalyst bodies

21 and 22. By setting the interval 14D to be, for example, 24 mm or more, the gas flow path in the upstream side catalyst body 21 is rapidly expanded to generate turbulent flow in the exhaust gas 10, and the turbulent flow further reduces the exhaust gas and the reducing agent. The mixture is stirred and introduced into the downstream catalyst body 22, and the exhaust gas 10 and the downstream catalyst body 22 are effectively brought into contact with each other to promote the reduction reaction.

An upstream soot blow device 51 that is disposed upstream of the upstream catalyst unit 31 and removes dust attached to the surface of the upstream catalyst body 21 in the catalyst unit 31 by the soot blow gas, and downstream of the downstream catalyst unit 32 And a downstream soot blower 52 that removes dust attached to the surface of the downstream catalyst body 22 in the catalyst unit 32 by the soot blow gas. Further, between the upstream catalyst unit 31 and the downstream catalyst unit 32 that are adjacent to each other, the downstream catalyst body 22 in the upstream catalyst unit 31 and the upstream catalyst body 21 in the downstream catalyst unit 32, respectively. A composite soot blower 53 for blowing soot blow gas is provided. This composite soot blower 53 is like a downstream soot blower 52 and an upstream soot blower 51 being integrated.

The upstream soot blow device 51, the downstream soot blow device 52, and the composite soot blow device 53 are constituted by a plurality of

soot blow pipes

61, 62, 63 arranged in parallel to each other at a predetermined interval along the cross section of the reaction vessel 1. ing. The

soot blow pipes

61, 62, 63 are arranged at a

predetermined arrangement pitch

61P, 62P, 63P so that the soot blow gas can be uniformly injected toward the

catalyst bodies

21, 22 of the

catalyst units

31, 32.

As shown in FIG. 3, the upstream soot blow device 51 has nozzle ports 71 having a predetermined diameter 71d formed in the length direction at an injection pitch 71p on the downstream side surface of the soot blow pipe 61 having an inner diameter 61D. The soot blow gas is injected from the 71 toward the catalyst body 21 of the upstream catalyst unit 31 at a predetermined injection angle 71α. Here, 71L is an injection distance from the nozzle port 71 to the catalyst body 21.

Further, in the downstream soot blower 52, nozzle ports 72 having a predetermined diameter 72d are formed in the longitudinal direction at an injection pitch 72p on the upstream side surface of the soot blow pipe 62 having an inner diameter 62D. Soot blow gas is injected toward the catalyst body 22 of the unit 32 at a predetermined injection angle 72α. Here, 72L is an injection distance from the nozzle port 72 to the catalyst body 22.

In the composite soot blow device 53, nozzle ports 74 having a predetermined diameter 74d are formed at a predetermined injection pitch 74p in the length direction on the downstream side surface of the soot blow pipe 63 having an inner diameter 63D. Then, soot blow gas is injected at a predetermined injection angle 74α from each nozzle port 74 toward the catalyst body 21 of the catalyst unit 32 on the downstream side. Here, 74L is an injection distance from the nozzle port 74 to the catalyst body 21. Further, on the upstream side surface of the soot blow pipe 63, nozzle ports 73 having a predetermined diameter 73d are formed in the length direction at a predetermined injection pitch 73p. Then, soot blow gas is injected from each nozzle port 73 toward the catalyst body 22 of the upstream catalyst unit 31 in a direction opposite to the exhaust gas 10 at a predetermined injection angle 73α. Here, 73 </ b> L is an injection distance from the nozzle port 73 to the catalyst body 22.

In the above structure, the reaction vessel 11 has a straight shape with the same cross section, the

catalyst units

31 and 32 have the same shape and specifications, and the soot blow gas supplied to the three

soot blow pipes

61, 62, and 63 is supplied with the same supply pressure. When the supply amount is set, with respect to the upstream soot blow device 51 and the composite soot blow device 53 that inject the soot blow gas in the same direction as the exhaust gas 10, the arrangement pitches 61P and 63P of the

soot blow pipes

61 and 63 are equal (61P = 63P), the

diameters

71d and 74d of the

nozzle openings

71 and 73 are equal (71d = 74d), the injection angles 71α and 74α are equal (71α = 74α), and the injection distances 71L and 74L are equal (71L = 74L). Forming. However, when the supply pressure and supply amount of the soot blow gas are different from each other, or when the shape of the reaction vessel 11 and the specifications of the

catalyst units

31 and 32 are different, these may be different from each other.

Similarly, in the composite soot blow device 53 and the downstream soot blow device 52 that inject the soot blow gas in the opposite direction to the exhaust gas 10, the

diameters

73d and 72d of the

nozzle ports

73 and 72 are equal (73d = 72d), and the injection angles 73α and 72α. Are equal (73α = 72α), and the injection distances 73L and 72L are equal (73L = 72L). However, when the supply pressure and supply amount of the soot blow gas are different from each other, or when the shape of the reaction vessel 11 and the specifications of the

catalyst units

31 and 32 are different, these may be different from each other.

However, in the composite soot blower 53, the nozzle port 74 that injects in the same direction as the exhaust gas 10 and the nozzle port 73 that injects in the opposite direction are formed in the same soot blow pipe 63, and the supply pressure and supply amount of the soot blow gas are the same. For this reason, it is preferable that the diameter 73d of the nozzle port 73 that injects in the opposite direction to the exhaust gas 10 is larger than the diameter 74d of the nozzle port 74 that injects in the same direction as the exhaust gas 10 (74d <73d). This is because when soot blow gas is injected in the direction opposite to the exhaust gas 10, soot blow gas is injected against the kinetic energy of the exhaust gas 10, so the kinetic energy for separating and removing dust is reduced by the kinetic energy flowing backward in the exhaust gas. This is because the peeling / removing ability is lower than that of the soot blow gas ejected from the nozzle port 74. In this case, the area ratio of the

bore diameters

74d and 73d formed in the soot blow pipe 63 is set to 1.4 or less, exceeding 1.0, for example, when the bore diameter 74d is 1.0.

Of course, when the kinetic energy of the soot blow gas injected in the opposite direction to the exhaust gas 10 is sufficiently large relative to the kinetic energy of the exhaust gas 10, the reduction of the dust separation and removal capability due to the soot blow gas injected in the reverse direction is reduced. Very small. Therefore, the diameter 74d of the nozzle port 74 and the diameter 73d of the nozzle port 73 may be the same, and the area ratio is set to 74d: 73d = 1: 1.

The inner diameter 63D of the soot blow pipe 63 of the composite soot blow device 53 is set sufficiently larger than the

inner diameters

61D and 62D of the upstream and downstream

soot blow pipes

61 and 62 corresponding to the supply amount of the soot blow gas. The

soot blow pipes

61, 62, 63 of the upstream soot blow apparatus 51, the downstream soot blow apparatus 52, and the composite soot blow apparatus 53 are connected to the soot blow gas supply pipe 18 from a soot blow gas supply source (air receiver tank) of the ship engine system. Yes. The pressure of the soot blow gas supplied through the soot blow gas supply pipe 18 is set to 0.3 to 0.6 (MPaG). The soot blow gas supply pipe 18 has soot

blow control valves

41, 42, 43 operated by a soot blow control device 19 provided in an engine control device (not shown) for each of the

soot blow pipes

61, 62, 63, respectively. Intervened. The soot

blow control valves

41, 42, 43 control the soot blow gas injection timing and injection time for each of the

soot blow devices

51, 52, 53.

The operation in the above configuration will be described with reference to FIGS.
During operation of the diesel engine, a reducing agent is blown into the exhaust gas by the SCR denitration device, and is introduced into the reaction vessel 11 so that NO _X is reduced and removed by contact between the exhaust gas 10 and the catalyst surface. In the reaction vessel 11, the exhaust gas 10 is sequentially passed through a pair of

catalyst bodies

21, 22 arranged with a gap 14 in the pair of front and

rear catalyst units

31, 32, thereby allowing the gap 14 to pass through the honeycomb-shaped passage. A turbulent flow is generated in the released exhaust gas 10, and the contact rate between the exhaust gas 10 and the

catalyst bodies

21 and 22 is increased as compared with a continuous catalyst body, and NO _X is reduced and removed with high reaction efficiency.

As shown in FIG. 4, during the operation of the diesel engine, the soot

blow control valve

41, 43, 42 is operated by the soot blow control device 19 every predetermined operating time T, for example, every 60 to 120 minutes. A predetermined amount of soot blow gas of a predetermined pressure is blown into the reaction vessel 11 from the

devices

51, 52, 53 toward the

catalyst units

51, 52. Thereby, the dust adhering to the surface of each

catalyst body

21 and 22 is peeled and removed. At this time, the soot

blow control valve

41, 43, 42 causes the soot blow gas to be injected from the

nozzle ports

71, 73, 74, 72 at intervals of a predetermined time (for example, every 0.5 to 2 seconds), and a pulse that repeats multiple times. Is injected into the shape. Dust adhering to the surfaces of the

catalyst bodies

21 and 22 can be effectively peeled and removed by the shock wave generated by the pulsed injection of the soot blow gas.

Here, in principle, the soot

blow control valves

41, 42, 43 are sequentially operated in accordance with the capacity of the air receiver tank, and soot blow gas is sequentially injected into the

soot blow pipes

61, 62, 63. Of course, if the capacity of the air receiver tank is sufficient, a plurality or all of the

soot blow pipes

61, 62, 63 can be simultaneously injected with the soot blow gas.

According to the above embodiment, the exhaust gas 10 passing through the upstream catalyst body 21 is caused to pass through the air gap 14 by the

catalyst units

31 and 32 having the pair of

catalyst bodies

21 and 22 arranged with the air gap 14 between the upstream and downstream sides. passage is suddenly enlarged becomes turbulent, is effectively in contact with the surface of the downstream side of the catalyst 22, NO _X contained in the exhaust gas 10 is effectively reduced and removed. The dust adhering to the surfaces of the

catalyst bodies

21 and 22 is applied to the soot blower from the

nozzle ports

71 and 74 of the upstream soot blower 51 and the composite soot blower 53 disposed in the upstream part 31 of the

catalyst units

31 and 32. Gas is blown into the upstream catalytic body 21 along the flow direction of the exhaust gas 10 every predetermined time, and dust adhering to the surface of the upstream catalytic body 21 of the

catalyst units

31 and 32 is removed. At the same time, the soot blow gas is sent downstream from the

nozzle ports

73 and 72 of the composite soot blower 53 and the downstream soot blow device 52 disposed downstream of the

catalyst units

31 and 32 in the direction opposite to the flow direction of the exhaust gas 10. The dust adhering to the surface of the catalyst body 22 on the downstream side of the

catalyst units

31 and 32 is removed. Accordingly, even in the

catalyst units

31 and 32 in which the

catalyst bodies

21 and 22 are arranged on the upstream side and the downstream side with the gap 14 therebetween, the

catalyst bodies

21 and 22 are caused by the soot blow gas blown from both sides of the upstream portion and the downstream portion. The dust adhering to the surface of each can be effectively peeled and removed.

When a plurality of

catalyst units

31 and 32 are installed in series in the reaction vessel 11, the catalyst body 22 on the downstream side of the upstream catalyst unit 31 and the catalyst body 21 on the upstream side of the downstream catalyst unit 32 are arranged. Since the soot blow device 53 for injecting soot blow gas is provided, the number of parts and the space occupied by the reaction vessel 11 can be reduced.

Further, since the plurality of

soot blow pipes

61, 62, 63 are arranged in parallel, the

nozzle ports

71, 72, 73 can be arranged evenly facing the

catalyst units

31, 32, and the surfaces of the

catalyst bodies

21, 22 are arranged. The dust adhering to the surface can be peeled and removed in a good and uniform manner.

Furthermore, since the diameter 73d of the nozzle port 73 opened on the upstream side surface is formed in the composite soot blow pipe 63 larger than the diameter 74d of the nozzle port 74 on the downstream side surface, the soot blow gas injected against the exhaust gas 10 is A large amount of energy can be injected, and dust adhering to the surfaces of the

catalyst bodies

22 and 21 can be effectively removed.

In addition, the soot blow gas injected from the

nozzle ports

71, 74, 73, 72 of the

soot blow pipes

61, 62, 63 at regular intervals is pulsed to repeat injection and stop a plurality of times. The shock wave by soot blow gas is repeatedly given to the dust adhering to the surface, and the dust can be effectively peeled and removed.

In the above embodiment, the SCR denitration apparatus in which the

catalyst units

31 and 32 are arranged on the upstream side and the downstream side has been described. However, three or more catalyst units may be arranged in series.
In the above embodiment, the soot blow for the denitration catalyst of the SCR denitration apparatus has been described. For example, the soot blow for the desulfurization catalyst for removing the sulfur oxide of the exhaust gas 10 of the gasoline engine or the catalyst provided in the exhaust gas line of another internal combustion engine. A soot blower may be used.

Claims

Two catalyst bodies made of stacked catalysts are arranged on the upstream side and the downstream side in a reaction vessel that sends exhaust gas from the upstream side to the downstream side, and between the upstream side catalyst body and the downstream side catalyst body. In addition, a catalyst unit with a gap that creates a turbulent flow by rapidly expanding the exhaust gas flow path is installed,
In the upstream part of the catalyst unit, an upstream soot blow device having a nozzle port for injecting soot blow gas to the upstream catalyst body along the exhaust gas flow is provided,
An exhaust gas purifying apparatus comprising a downstream soot blow device having a nozzle port for injecting soot blow gas toward a downstream catalyst body in a reverse direction of the exhaust gas flow in a downstream portion of the catalyst unit.
In the reaction vessel, a plurality of catalyst units are installed in series in the exhaust gas flow direction,
A downstream soot blower arranged on the downstream side of the upstream catalyst unit and an upstream soot blower arranged on the upstream side of the catalyst unit adjacent to the downstream side are integrated to form nozzle ports on the upstream side surface and the downstream side surface, respectively. The exhaust gas purifying device according to claim 1, wherein the exhaust gas purifying device is constituted by a combined soot blower.
The upstream soot blow device and the downstream soot blow device are constituted by a plurality of soot blow pipes arranged in parallel to each other at a predetermined interval along the cross section of the exhaust gas flow, and have a length on the upstream side surface or the downstream side surface of these soot blow pipes. Nozzle openings are formed at a predetermined pitch in the direction,
The composite soot blow device is composed of a plurality of soot blow pipes arranged in parallel with each other at a predetermined interval along the cross section of the exhaust gas flow, and a plurality of nozzle ports are provided on the upstream side surface and the downstream side surface of the soot blow pipe, respectively. The exhaust gas purifier according to claim 2, wherein the exhaust gas purifier is formed at a predetermined pitch in the length direction.
The exhaust gas purifying apparatus according to claim 3, wherein the composite soot blow pipe is formed such that a diameter of a nozzle port opened on an upstream side surface is larger than a nozzle port opened on a downstream side surface.
A method for operating the purification device according to any one of claims 1 to 4,
A method for operating an exhaust gas purifying apparatus, characterized in that soot blow gas is injected in a pulse form that repeats injection and stop at regular intervals from a nozzle port.