KR100958345B1 - Scr system - Google Patents

Abstract

PURPOSE: An SCR system is provided to remove contaminated components of exhaust gas with simple structure while preventing destruction and damages of the SCR system due to vibration and external shock while reducing volume of a catalyst. CONSTITUTION: An SCR system connected to an exhaust gas facility(1) includes the following: an SCR reactor(2) having a front pipe and a back pipe with a catalyst activated by exhaust gas; a reducing agent supply line supplying a reducing agent to the SCR reactor; a sensor(11) detecting remaining contaminants in the exhaust gas and is equipped on the rear end of the SCR reactor; an analyzer(7) analyzing remaining contaminants by using information gained from the sensor; and a water spray part(20) removing the contaminants in the exhaust gas.

Description

SCR system {SCR SYSTEM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an SCR system for reducing nitrogen oxides (NOx) in exhaust gas, and more particularly, to an SCR system having improved efficiency by further removing some pollutant exhaust gas components using water. The present invention is applicable to all ships or onshore plants including offshore floating structures, and has been developed to satisfy various regulations in each application.

SCR systems are used to reduce NOx in exhaust gases generated during the operation of land plants or ships. For example, an SCR system is required to reduce nitrogen oxides in exhaust gas generated from an engine or a boiler of a ship (especially an LNG carrier) or a boiler or an incinerator of a land plant. The SCR system is a NOx reduction system using a selective catalytic reduction method. The SCR system is configured to react NOx with a reducing agent and to reduce the nitrogen and water vapor while simultaneously passing the exhaust gas and the reducing agent in the catalyst. Recently, there have been many efforts to improve the SCR system. In spite of such efforts, the particularity of ships or some land plants does not produce noticeable results. For example, in the case of ships, there is a lot of movement and vibration at sea, and hence load variables, which makes it difficult to apply SCR systems to ships.

In general, SCR systems use NH3 and urea as reducing agents for NOx reduction. In addition, the SCR system utilizes a high temperature catalyst having an active temperature range of 330 ° C to 400 ° C. Therefore, in the conventional SCR system, a reheating system for heating the exhaust gas is installed in front of the casing of the SCR reactor in which the catalyst is installed in order to increase the reaction efficiency by matching the conditions of the active temperature range. In addition, the conventional SCR system includes a dust collecting facility at the rear end of the SCR reactor casing to reduce PM (Particle Material), dust, and fine dust contained in the exhaust gas which has been reacted in the SCR reactor.

The heating system and / or the dust collection equipment increase the overall size of the SCR system. Therefore, applying the SCR system to a fixed space of a ship or a land plant is very disadvantageous in that it further reduces the idle space of a ship or a land plant. In addition, the SCR system must be designed taking into account the conditions of the facility in which it is installed, for example, if the facility is a ship, the Richting system and / or the dust collection facility have been difficult to meet the limited conditions of the ship. In addition, the installation cost of the SCR system will be greatly increased due to the limiting system and / or the dust collecting facility, and the cost incurred later according to the operation of the limiting system and the dust collecting facility.

In addition, a problem of the conventional SCR system is that high pressure air is required to supply urea or NH3, which is a reducing agent, into the SCR reactor, and it is complicated to connect such high pressure air to a line supplied with the reducing agent or to use a compressor. There is a problem that piping or equipment is required. In addition, the prior art also has a limitation in supplying urea or NH3 to the SCR reactor with high purity.

In addition, since the conventional SCR system is vulnerable to vibration, it was very difficult to install in a land plant in an area where ships or earthquakes are concerned. Vibration may cause destruction and damage of the SCR system, so a countermeasure is required. In particular, since the ship is subjected to high external shocks or vibrations due to high waves, the SCR system installed therein is also more vulnerable to external shocks or vibrations.

Above all, the conventional SCR system installed in a ship or a land plant has a problem that there is no processing function for PM (Particulate Matter). DFP, which was applied in a very limited way to automobiles, was not economical or efficient to be applied to a ship or a land plant.

It is an object of the present invention to provide an SCR system for a ship or land plant that allows contaminants in the exhaust gas, such as PM, that are difficult or unremovable from the SCR reactor to be removed from the piping of the SCR reactor with water.

Another object of the present invention is to provide a ship which further comprises additional functions for the safe handling in dust and / or hazardous situations, while removing contaminants in the exhaust gas that are difficult or unremovable in the SCR reactor with water. It is to provide an SCR system for a land plan.

In accordance with one aspect of the present invention, an SCR system is provided that is connected to the exhaust plant of a land plant or vessel. The SCR system includes a catalyst activated by exhaust gas therein, an SCR reactor having a front pipe and a rear pipe, a reducing agent supply line for supplying a reducing agent into the SCR reactor, and a front end of the SCR reactor. Or a water spray unit for spraying water to remove contaminants into the pipe at the rear stage.

Preferably, the water used by the water spraying unit is sea water, and in particular, in the case of a ship or a land plant installed on the shore, it is particularly preferable to use sea water that can be easily obtained from the sea.

According to one embodiment, the water injection unit may be arranged to spray water to the rear end pipe of the SCR reactor.

According to another embodiment. The water injection unit may be configured to selectively spray water to at least one of the front pipe of the SCR reactor and the rear pipe of the SCR reactor.

According to one embodiment, the waste tailings removing portion is installed in the pipes so as to remove the waste tailings dropped on the inner surface of the pipe together with the water by the water spraying unit. In this case, the waste residue removing portion may include a structure for selectively and temporarily allowing the opening of a portion of the pipe to remove the waste residue.

According to an embodiment, a dustproof device may be installed in the SCR reactor, and a flexible connection structure may be installed in a portion of the pipes at the front and rear ends of the SCR reactor.

The SCR system according to an embodiment may further include a bypass system for flowing exhaust gas from the exhaust gas facility bypassing the SCR reactor in an abnormal state.

According to one embodiment, the reducing agent is preferably urea or NH ₃ .

According to the present invention, there is an advantage that the components in the exhaust gas, such as PM, which have been difficult to process with the existing SCR system, can be removed by adopting a simple water injection structure. The water injection structure can remove not only PM but also other pollutants in the exhaust gas such as NOx, which contributes to reducing the catalyst volume employed in the SCR reactor. In addition, according to one embodiment of the present invention, since it is possible to seismic isolation, earthquake-resistant or vibration-proof by the vibration isolator, it is possible to prevent the destruction and damage of the SCR system due to vibration or external shock. In addition, according to one embodiment of the present invention, by the bypass system to bypass the SCR reactor to flow the exhaust gas, in the event of an abnormality or emergency in the system, without the operation of the exhaust gas equipment, Repair or replace parts or parts.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided as examples to ensure that the spirit of the present invention can be fully conveyed to those skilled in the art. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. And, in the drawings, the width, length, thickness, etc. of the components may be exaggerated for convenience. Like numbers refer to like elements throughout. In addition, Table 1 below describes the names of elements or signals denoted by symbols in the accompanying drawings.

<First Embodiment>

1 is a view for explaining a SCR system for a ship or a land plant according to a first embodiment of the present invention.

Referring to FIG. 1, the SCR system of the present embodiment includes an SCR reactor 2 in which a pipe of a front end is connected to an exhaust gas installation 1. The exhaust gas installation 1 may be an engine for propulsion of a ship, an engine for other uses, a boiler in an LNG carrier, or various kinds of facilities for exhausting exhaust gas by combustion in a ship. In addition, the exhaust gas facility 1 may be a facility for discharging the exhaust gas, such as a boiler or incinerator installed in the land plant.

The SCR reactor 2 includes a catalyst for reducing NOx in exhaust gas by a selective catalytic reduction method. In the casing of the SCR reactor 2, NOx is reduced to nitrogen by reacting with a reducing agent in the presence of a catalyst.

Unlike the conventionally known system, the SCR system according to the present embodiment does not have a heating system for heating exhaust gas in front of the SCR reactor 2. Instead, the system comprises a catalyst activated in the SCR reactor 2 at a temperature below 320 ° C., more preferably below 300 ° C. The lower limit of the activation temperature of the catalyst is determined to be around the temperature of the exhaust gas below 320 ° C, more preferably below 300 ° C, based on the point at which the exhaust gas passes the SCR reactor 2. That is, the system of the present embodiment selects and uses a catalyst having an activation temperature corresponding to the exhaust gas temperature passing through the SCR reactor 2 in consideration of the decrease in temperature as the exhaust gas proceeds out of the exhaust gas equipment 1. However, a variety of catalysts of the SCR reactor 2 may be selectively used as desired.

In addition, two or more kinds of catalysts having different activation temperatures may be embedded in the SCR reactor 2. This may contribute to widening the temperature range at which the catalytic reaction takes place in the SCR reactor 2. In addition, it is moron that the catalyst for reducing other components in addition to the catalyst for reducing NOx may be further installed in the SCR reactor 2.

Unlike the conventionally known system, the SCR system according to the present embodiment does not have a dust collecting facility at the rear end of the SCR reactor 2. Instead, in the system of the present embodiment, the water jetting unit 20 and the waste tailings removing unit 30, which will be described in detail below, may at least partially perform the role of the existing dust collector. Further, for better dust collection efficiency, it may have a dust collecting structure inside the SCR reactor 2, by which the PM, dust or fine dust can be collected in the SCR reactor 2. However, of course, the system of the present embodiment may further install any other dust collector at the rear stage as desired.

In addition, the system of this embodiment is equipped with various sensors 11 capable of detecting NOx, NH3, PM, HC, SO ₂ , CO, CO ₂ , O ₂ , and the like in the exhaust gas at the rear end of the SCR reactor ₂ . can do. In addition, the system includes an analyzer for analyzing residual components in the exhaust gas such as NOx, NH ₃ , PM, HC, SO ₂ , CO, CO ₂ , O ₂ using information obtained from the sensor 11. ) Is provided at the rear end of the SCR reactor 2. The various sensors 11 and the analyzer 7 described above are controlled by the ECU 5. The ECU 5 electronically controls devices such as various valves or pumps as well as the sensor 11 and the analyzer 7. In addition, the system of the present embodiment includes an OBM system 6, which is responsible for the control of the entire system and the monitoring of the system, the on / off of the system and the display of pollutant (especially NOx) reduction efficiencies.

On the other hand, the SCR system according to the present embodiment includes an air line 3 for supplying air to an air soot blower system 8 in or near the SCR reactor 2. The air soot blower system 8 blows the air supplied from the air line 3 to the catalyst in the SCR reactor 2 to remove foreign matter trapped in the catalyst.

The SCR system according to the present embodiment includes a reducing agent supply line 4 to supply the reducing agent for NOx reduction as mentioned above into the SCR reactor 2. The reducing agent supply line 4 supplies NH ₃ or urea into the SCR reactor 2, and the supplied NH 3 or urea reacts with the NOx in the exhaust gas in the presence of a catalyst.

The aforementioned air line 3 comprises a line branching from the line facing the soot blower system to the reducing agent supply line 4. The structure of this airline 3 is hereinafter referred to as "two way". The two-way airline 3 has one line participating in the operation of the air soot blower system 8 described above, and the other line injects NH 3 or urea into the injection nozzle 12 in the SCR reactor 2. It acts as a push out.

In addition, the SCR system according to the present embodiment has a damper 9 at the inlet side of the SCR reactor 2 to evenly distribute the exhaust gas to the catalyst. A mixer 10 for evenly mixing exhaust gas and urea / NH 3 is provided at the front end of the SCR reactor 2 upstream of the damper 9. Various sensors 11 are also provided at the front end of the SCR reactor 2, which are arranged before the exhaust gas is purified, that is, before the exhaust gas passes through the SCR reactor 2. This is to measure and analyze the content of NOx, NH3, PM, HC, SO ₂ , CO, CO ₂ or O _2, etc. This analyzed information is based on the component information in the purified exhaust gas which has passed through the SCR reactor 2. Can be prepared.

First of all, the SCR system of the present embodiment includes a water injection unit 20 configured to selectively spray water to at least one of a rear end pipe of the SCR reactor 2 and a front end pipe of the SCR reactor 2. In the present embodiment, the water spray unit 20 includes first and second water supply lines 21 and 22 extending to the rear end pipe of the SCR reactor 2 and the front end pipe of the SCR reactor 2, respectively. The water is injected through the nozzles at the ends of the first and second water supply lines 21 and 22, respectively, to the rear end pipe and the front end pipe. In addition, the first and second water supply lines 21 and 22 are provided with valves 23 and 24 for selectively using the first and second supply lines 21 and 22, respectively. The first and second supply lines 21 and 22 are provided with blowers 25 and 26 for generating power for water supply.

In particular, spraying water into the pipe downstream of the SCR reactor 2 is very useful for removing PM in the exhaust gas that has passed through the SCR reactor 2. In addition, by injecting water into the SCR reactor 2 front pipe together with the downstream pipe of the SCR reactor 2, it is possible to further remove contaminants in other exhaust gases such as NOx, and thus the catalyst volume in the SCR reactor 2 Can be reduced, which is economically advantageous. In this embodiment, although the water injection unit 20 is configured to spray water at the same time or only one of the front end pipe and the rear end pipe of the SCR reactor 2, water is sprayed only to one of the two front pipes, in particular, the rear pipes. Note that the configuration of the water jetting section 20 is also within the scope of the present invention. In this case, the water injection unit 20 may include only one water supply line.

In the case of ships or offshore plants, it is preferred that the water spray unit 20 use sea water. However, it is, of course, possible that the water spray unit 20 uses arbitrary water rather than seawater.

FIG. 1 includes a waste residue removal unit 30 for removing contaminants such as PM from the inner surface of the rear end pipe of the SCR reactor 2 together with the water by the water injection unit 20. The waste residue removing unit 30 is useful for opening a portion of the rear end pipe and removing waste residues accumulated in the rear end pipe. Although the waste residue removal unit 30 is illustrated in FIG. 1 as being provided only in the rear end pipe of the SCR reactor 2, it is noted that the waste residue removal unit may be further included in the front end pipe of the SCR reactor 2.

Second Embodiment One-Way Airlines

2 shows an SCR system according to a second embodiment of the present invention.

Referring to FIG. 2, the SCR system according to the present embodiment includes a water spray unit 20 and a waste residue removing unit 30, as described in the foregoing embodiment. Since this has been described above, the description thereof is omitted.

Meanwhile, the SCCR system according to the present embodiment includes a reducing agent supply line 4 for supplying NH 3 / urea to the SCR reactor 2, wherein the reducing agent supply line 4 is an air line 3 of the foregoing embodiment. Without being connected to, it extends to the injection nozzle 12 in front of the SCR reactor 2. The reducing agent supply line 4 sends NH3 / urea directly to the injection nozzle 12 in the front end of the SCR reactor 2 by itself, i.e., a supply means such as a self-contained pump, thereby simplifying the piping. More urea or NH3 can be used for NOx reduction. To this end, the pump itself or a control line connected to the pump may be equipped with devices for controlling the flow rate of urea or NH3. Thereby, the air line 3 comprises one line which participates in the operation of the air soot blower system 8, hereinafter referred to as 'one-way air line'. The rest of the configuration of this embodiment is the same as in the first embodiment, so detailed description thereof will be omitted.

<Third Embodiment: Dustproof Device for Seismic / Isolation / Vibration Prevention>

3 shows an SCR system according to a third embodiment of the present invention.

Referring to FIG. 3, the SCR system according to the present embodiment includes a water spray unit 20 and a waste residue removing unit 30, as described in the foregoing embodiment. Since this has been described above, the description thereof is omitted.

On the other hand, in the system of the present embodiment, the vibration isolator 14 for seismic isolation, vibration isolation, and vibration isolation is provided in the SCR reactor 2. Since the ship moves by sea or by sea or the like, the vibration is severe and the load is variable. Correspondingly, the present system is very well suited for land plant use in ships or earthquake-prone areas since the vibration isolator 14 is installed in the SCR reactor 2. At this time, the vibration isolator 14 may consider a variety of structures, but the suspension structure is preferred. In addition, the tubes of the front and rear ends of the SCR reactor 2 have a flexible connection structure so that the dustproof device 14 works well on the SCR reactor 2. In this embodiment, the flexible joint 13 was used for pipe connection at the front end and the rear end of the SCR reactor 2. The system shown in FIG. 3 is a system comprising a one-way airline 3.

However, the vibration isolator 14 may also be applied to a system including a two-way airline, and the configuration of the SCR system including the dustproof device 14 and the two-way airline 3 is illustrated in FIG. 4.

The remaining configuration is not significantly different from the foregoing first and second embodiments, and therefore, description of the remaining configuration will be omitted.

Fourth Embodiment Bypass System

5 shows an SCR system according to a fourth embodiment of the present invention.

Referring to FIG. 5, the SCR system according to the present embodiment includes a water spray unit 20 and a waste residue removing unit 30, as described in the foregoing embodiment. Since this has been described above, the description thereof is omitted.

On the other hand, the SCR system according to the present embodiment, in the event of an abnormal situation and / or an emergency situation, replaces an abnormal part (particularly, an abnormal part of the SCR reactor 2) while maintaining the operation of the exhaust gas installation 1 as it is. It includes a bypass system that allows for maintenance.

In the present embodiment, the bypass system includes a bypass line 16 and bypass dampers 17. Both ends of the bypass line 16 are connected to the front end and the rear end of the SCR reactor 2, respectively. In the steady state, the gas flowing through the SCR reactor 2 flows in a abnormal or emergency situation by bypassing the SCR reactor 2 through the bypass line 16 from the front end to the rear end of the SCR reactor 2 without passing through the SCR reactor 2. The pair of bypass dampers 17 are respectively provided at both ends of the bypass line 16, and in a normal state, both ends of the bypass line 8 are closed and the passage of the SCR reactor 2 is opened. In an abnormal or emergency situation, both ends of the bypass line 16 are opened and the passage of the SCR reactor 2 is closed.

The SCR system shown in FIG. 5 is an SCR system including a one-way airline 3. However, the bypass line and the bypass dampers may also be applied to a system including the two-way airline, and the SCR system including the bypass line 16 and the bypass dampers 17 and the two-way airline 3 may be applied. The configuration is shown in FIG.

The rest of the configuration is not significantly different from the foregoing embodiments and detailed description thereof will be omitted.

1 is a view for explaining an SCR system according to a first embodiment of the present invention.

2 is a view for explaining an SCR system according to a second embodiment of the present invention.

3 is a view for explaining an SCR system according to a third embodiment of the present invention.

4 shows a modification of the third embodiment shown in FIG.

5 is a diagram for explaining an SCR system according to a fourth embodiment of the present invention;

6 is a view showing a modification of the fourth embodiment shown in FIG.

Claims (8)

SCR system connected to the exhaust gas plant, An SCR reactor including a catalyst activated by exhaust gas and having a front pipe and a rear pipe; A reducing agent supply line for supplying a reducing agent into the SCR reactor; A sensor provided at a rear end of the SCR reactor to detect a residual pollutant in exhaust gas; And An analyzer for analyzing residual pollutants in exhaust gas using information obtained from the sensor; In the water supply line, a valve and a water supply blower electronically controlled by the ECU are provided, and water is injected into the exhaust gas flowing through the front end pipe or the rear end pipe of the SCR reactor to drop contaminants in the exhaust gas into the water. SCR system comprising a water spray to remove. The SCR system according to claim 1, wherein the water used by the water spray unit is sea water. The water jetting unit of claim 1, wherein the water spraying unit includes first and second water supply lines extending to a rear end pipe of the SCR reactor and a front end pipe of the SCR reactor, respectively, and end nozzles of the first and second water supply lines. It is configured to spray the water through each of the first and second water supply line is provided with valves for selectively using at least any one of the first and second water supply line, the second water supply line SCR system, characterized in that for spraying water upstream of the position where the reducing agent is supplied in the shear pipe of the SCR reactor. The SCR system of claim 1, wherein the water spray unit is configured to selectively spray water to at least one of a front pipe of the SCR reactor and a rear pipe of the SCR reactor. The SCR system as set forth in claim 1, wherein a waste residue removal unit is installed in the pipe so as to remove waste residues dropped on the inner surface of the pipe together with water by the water spray unit. The SCR system of claim 1, wherein the SCR reactor is provided with a dustproof device. The SCR system of claim 1, further comprising a bypass system for flowing exhaust gas from the exhaust gas facility bypassing the SCR reactor in an abnormal state. The SCR system of claim 1, wherein the reducing agent is urea or NH ₃ .

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