KR20130013134A - Exhaust gas cleaning apparatus and method in ship or marine structure - Google Patents

Abstract

PURPOSE: An apparatus and method for purifying exhaust gas from ships or offshore structures are provided to guarantee an installation space, and to effectively reduce NOx by a catalyst reaction. CONSTITUTION: An apparatus for purifying exhaust gas from ships or offshore structures includes an exhaust receiver(10), a SCR(Selective Catalytic Reduction) reactor(30), a bypass pipe(22), a control valve(24), and a heating unit. The exhaust receiver receives exhaust gas generated during engine combustion. The SCR reactor is placed at the rear end of a supercharger, and reduces NOx in the exhaust gas by a SCR catalyst reaction. The bypass pipe bypasses some exhaust gas without passing the gas through the supercharger. The temperature of the exhaust gas is compensated while the exhaust gas passes through the bypass pipe. The control valve is installed in the bypass pipe to adjust the amount of the exhaust gas passing through the bypass pipe. The heating unit increases the temperature of the exhaust gas before the gas flows into the SCR reactor. [Reference numerals] (AA) Waste heat

Description

Exhaust gas purification device and method for ship or offshore structure {EXHAUST GAS CLEANING APPARATUS AND METHOD IN SHIP OR MARINE STRUCTURE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for the purification of exhaust gas of a ship or offshore structure. An exhaust gas purification apparatus and method for a structure.

SCR is used to reduce NOx, ie NOx, in the exhaust gas generated during operation of a ship or offshore structure. By way of example, SCR is used for NOx removal from engines of ships, in particular from two-stroke diesel engines. The SCR exhaust gas purifying apparatus is a NOx abatement apparatus using a selective catalytic reduction method, and is configured to react NOx with a reducing agent while simultaneously reducing exhaust gas and a reducing agent in a catalyst to reduce treatment with nitrogen and water vapor.

On the other hand, the exhaust gas generated during the combustion of the two-stroke diesel engine of the ship or offshore structure is transferred from the cylinder to the exhaust gas receiver through the exhaust valve. At this time, the exhaust gas temperature is different depending on various operating conditions such as the engine type, load (load), outside conditions, a high temperature of approximately 350 ℃ or more is appropriate.

Therefore, in consideration of the reaction temperature (270 ~ 350 ℃) of the general catalyst applied to the SCR, it is generally considered to install the SCR reactor between the exhaust gas receiver (turbo gas receiver) and the turbocharger (turbo charger). However, due to the limitation of the installation position of the SCR reactor due to the reaction temperature constraint of the catalyst, there are many difficulties in the arrangement of the engine room and an alternative is required.

With the development of low-temperature catalysts, an exhaust gas purifier having a SCR reactor installed at the rear end of a turbocharger has been conventionally proposed, but in this case, the temperature is lowered as the exhaust gas of the high temperature exhaust gas receiver drives the supercharger. The low temperature catalyst in the engine operating zone is lower than the temperature required for the reaction (less than 250 ℃), even if the installation of the SCR reactor there is a problem that can not satisfy the NOx reduction.

Accordingly, the problem to be solved by the present invention is that the catalytic reduction reaction in the SCR reactor by bypassing a part of the exhaust gas receiver of the high temperature exhaust gas so as not to pass through the supercharger and mixing the exhaust gas passing through the supercharger and the high temperature exhaust gas that is not It is to provide an exhaust gas purification apparatus for ships or offshore structures capable of adjusting the temperature (above 270 ℃) suitable for.

According to an aspect of the present invention, there is provided an exhaust gas purification device used in conjunction with an engine and a supercharger in a ship or offshore structure, the exhaust gas purification device, the exhaust gas receiver receiving the exhaust gas generated during combustion of the engine and ; An SCR reactor disposed at a rear end of the supercharger to reduce NOx in the exhaust gas by an SCR catalytic reaction; And a bypass pipe for bypassing a part of the exhaust gas from the exhaust gas receiver without passing through the supercharger. The exhaust gas purification device compensates for the temperature of the exhaust gas lowered through the supercharger with the high temperature exhaust gas passing through the bypass pipe.

According to one embodiment, the exhaust gas purification device further comprises a control valve installed in the bypass pipe to adjust the amount of exhaust gas passing through the bypass pipe.

According to one embodiment, the exhaust gas purification device further comprises a heating unit for heating the exhaust gas before entering the SCR reactor to increase the temperature.

According to an aspect of the present invention, there is provided an exhaust gas purification method for purifying exhaust gas generated during engine combustion in association with an engine and a supercharger in a ship or offshore structure, and the exhaust gas purification method includes the exhaust gas by an SCR catalytic reaction. Arranging an SCR reactor for reducing NOx in the rear of the supercharger; Bypassing a portion of the exhaust gas that passes through the supercharger to the SCR reactor without passing through the supercharger at the front of the supercharger; The temperature of the exhaust gas is raised by the mixing of the bypassed exhaust gas and the exhaust gas passing through the supercharger, and the exhaust gas of the elevated temperature flows to the SCR reactor.

According to one embodiment, the amount of exhaust gas bypassed is determined taking into account at least the catalytic reaction temperature of the SCR reactor and the type of engine.

According to one embodiment, the waste heat in the exhaust gas from the SCR reactor is recovered and used.

According to one embodiment, the exhaust gas before entering the SCR reactor is heated by a separate heating unit.

According to the present invention, a part of the exhaust gas can be bypassed so as not to go through the supercharger, the exhaust gas having passed through the supercharger and the other exhaust gas can be mixed, and the mixed exhaust gas can be supplied to the SCR reactor, whereby Even if the temperature is lowered through the supercharger, the temperature of the entire exhaust gas by the bypassed exhaust gas becomes a temperature suitable for the catalytic reduction reaction. This makes it possible to efficiently reduce NOx by the SCR catalytic reaction even if the SCR reactor is placed on the rear side of the supercharger, and the existing space caused by the SCR reactor is installed in the engine room deck or the engine casing. Resolve installation constraints.

1 is a view for explaining the exhaust gas purification apparatus of a ship or offshore structure according to an embodiment of the present invention.
2 is a view for explaining the exhaust gas purification apparatus of a ship or offshore structure according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the same reference numerals denote the same components, and the width, length, thickness, etc. of the components may be exaggerated for convenience.

1 is a view for explaining the exhaust gas purification apparatus of a ship or offshore structure according to an embodiment of the present invention.

Referring to FIG. 1, a two-stroke diesel engine 1 and a turbocharger 2 installed in a ship or offshore structure can be seen.

In addition, the exhaust gas purifying apparatus according to the present embodiment is used in conjunction with the engine 1 and the supercharger 2, and is configured to reduce NOx in exhaust gas generated during combustion of the engine 1.

In addition, referring to FIG. 1, the exhaust gas purifying apparatus according to the present embodiment includes an exhaust gas receiver 10 provided at one side of the engine 1 and receiving exhaust gas generated during combustion of the engine 1 and a main exhaust line. And an SCR reactor 30 which reduces the NOx by catalytic reduction of the exhaust gas which has passed through the exhaust gas receiver 10 and the supercharger 2 at the rear end thereof. The SCR reactor 30 has a low temperature or general catalyst therein. In addition, for the catalytic reaction of the SCR reactor 30, urea or ammonia may be used as the reducing agent.

In addition, the exhaust gas purification apparatus includes an exhaust gas bypass pipe 22 for bypassing a portion of the exhaust gas from the exhaust gas receiver 10 to pass through the supercharger 2 to the SCR reactor 30. do. The bypass pipe 22 branches off from the main exhaust line 20 at the front of the supercharger 2 and is then integrated back into the main exhaust line 20 between the supercharger 2 and the SCR reactor 30. .

In Fig. 1, reference numerals "2a" and "1a" represent a scavenging air line and a scavenging air receiver, respectively, and these are not directly related to the present invention and their general description is omitted.

In addition, the exhaust gas purification device includes a control valve 24 installed in the bypass pipe 22. The control valve 24 may be a flow control valve, and controls the amount of exhaust gas directed to the SCR reactor 30 without passing through the supercharger 2 through the bypass pipe 22.

In addition, the exhaust gas purification apparatus includes a waste heat recovery unit 40 installed at a rear end of the SCR reactor 30 to recover waste heat in the exhaust gas passing through the SCR reactor 30.

According to the above configuration, the exhaust gas generated in the combustion process of the engine 1 is transferred to the exhaust gas receiver 10 through an exhaust valve in a cylinder in the engine 1. At this time, the exhaust gas temperature varies depending on the operating conditions such as the type of the engine 1, load, and outdoor conditions, but is suitable for the operation of the SCR reactor at a high temperature of about 350 ° C or more.

Since the exhaust gas temperature in the exhaust gas receiver 10 is a temperature suitable for the general catalytic reduction reaction of the SCR reactor, as described in the background art above, the exhaust gas is conventionally considered in consideration of the reaction temperature of the catalyst applied to the SCR reactor. It was considered to install an SCR reactor between the receiver and the supercharger. However, these conventional considerations present many difficulties in engine room arrangement.

Exhaust gas purifying apparatus according to an embodiment of the present invention is configured to supply an exhaust gas of a temperature sufficient for the catalytic reaction of the SCR reactor 30, even if the SCR reactor 30 is moved to the rear end of the supercharger (2), This is possible by an additional configuration such as the bypass tube 22.

According to the exemplary embodiment of the present invention, the exhaust gas from the exhaust gas receiver 10 is significantly lowered in temperature while passing through the supercharger 2, and the temperature of the exhaust gas passed through the supercharger 2 is the SCR reactor 30. It can be lower than the low temperature of the reaction temperature of the catalyst, and therefore, this exhaust gas alone causes a desired catalytic reaction in the SCR reactor 30, so that the NOx regulation which is strengthened in the future is hardly satisfied in all the operating zones. However, according to the present embodiment, a part of the exhaust gas supplied from the exhaust gas receiver 10 to the supercharger 2 is bypassed through the bypass pipe 22 so as not to pass through the supercharger 2, thereby greatly reducing the temperature. It is mixed with the low temperature exhaust gas through the supercharger 2 without. Since this mixed exhaust gas contains high-temperature exhaust gas which did not pass through the supercharger 2, it can enter into the SCR reactor 30 at the temperature which can catalyze reaction of the SCR reactor 30 (270 degreeC or more).

Furthermore, by using the control valve 24 installed in the bypass pipe 22, the bypass amount of the hot exhaust gas through the bypass pipe 22 in the mixed exhaust gas can be increased or reduced, so that the SCR reactor The temperature of the mixed exhaust gas can be adjusted according to the reaction temperature of (30). For example, by adjusting the control valve 24 in consideration of whether the catalyst in the SCR reactor 30 is a low temperature catalyst (of about 250 ° C. reaction temperature) or a general catalyst (of about 270-350 ° C. reaction temperature), It is possible to adjust the amount of exhaust gas passing through the bypass pipe 22 and the temperature of the resulting mixed exhaust gas.

As described above, according to the present invention, even if the SCR reactor 30 is installed at the rear end of the supercharger 2, the temperature of the exhaust gas can be raised to the temperature required for the reaction of the SCR catalyst. As described above, the exhaust gas receiver 10 bypasses a part of the exhaust gas supplied from the exhaust gas receiver 10 to the supercharger 2 through the exhaust gas bypass pipe 22 without passing through the supercharger 2. It is possible by sending to.

In the method for purifying exhaust gas using the exhaust gas purifying apparatus according to the present embodiment described above, first, the type of the engine and the temperature at which the SCR catalyst for each load can react should be grasped. In addition, if such grasping is made, the bypass amount of the exhaust gas through the bypass pipe 22 should be determined. In addition, depending on the price and operating cost of the SCR catalyst (low temperature or general catalyst), it is possible to adjust the bypass amount of the exhaust gas. In addition, an increase in fuel consumption of a two-stroke diesel engine may be considered in determining the bypass amount of the exhaust gas. If necessary, separate exhaust bypass levels for each engine load can be adjusted to meet the relevant regulatory requirements.

2 is a view for explaining the exhaust gas purification apparatus of a ship or offshore structure according to another embodiment of the present invention.

2, the exhaust gas purifying apparatus according to the present embodiment further includes a heating unit 50 as a means for further raising the temperature of the exhaust gas. In the present embodiment, the heating unit 50 may be disposed on the rear end side of the supercharger 2 to heat the exhaust gas passing through the supercharger 2. Since the temperature of the exhaust gas passing through the supercharger 2 is increased by the heating unit 50, it is possible to reduce the bypass amount of the exhaust gas through the bypass pipe 22. In this case, the heating unit 50 may be operated only when necessary.

In the present embodiment, the heating unit 50 is installed to heat the exhaust gas directly passing through the supercharger 2, but this is only one embodiment, so that the heating unit 50 is heated to bypass the exhaust gas. It may be installed in the bypass pipe 22, or may be installed to heat the mixed exhaust gas installed at the front end of the SCR reactor 30. The heating unit 50 may be a small burner or may alternatively be a heat exchanger using waste heat or some other heat source.

1: two-stroke diesel engine 2: turbocharger
10: exhaust gas receiver 20: main exhaust line
22: bypass pipe 24: control valve
30: SCR reactor 40: waste heat recovery unit
50: heating unit

Claims (7)

An exhaust gas purification device used in conjunction with an engine and a supercharger in a ship or offshore structure,
An exhaust gas receiver which receives exhaust gas generated during combustion of the engine;
An SCR reactor disposed at a rear end of the supercharger to reduce NOx in the exhaust gas by an SCR catalytic reaction;
A bypass pipe for bypassing a part of the exhaust gas from the exhaust gas receiver without passing through the supercharger,
Compensating the temperature of the exhaust gas lowered while passing through the supercharger with the exhaust gas passing through the bypass pipe, characterized in that the exhaust gas purification apparatus for ships or offshore structures. The exhaust gas purification apparatus for a ship or offshore structure according to claim 1, further comprising a control valve installed in the bypass pipe to adjust an amount of exhaust gas passing through the bypass pipe. The exhaust gas purification apparatus according to claim 1 or 2, further comprising a heating unit for heating the exhaust gas before entering the SCR reactor to increase the temperature. A method of purifying exhaust gas generated during engine combustion in connection with an engine and a supercharger in a ship or offshore structure,
An SCR reactor for reducing NOx in the exhaust gas by an SCR catalytic reaction is arranged at a rear end of the supercharger;
Bypassing a portion of the exhaust gas that passes through the supercharger to the SCR reactor without passing through the supercharger at the front of the supercharger;
The temperature of the exhaust gas is increased by mixing the bypassed exhaust gas and the exhaust gas passing through the supercharger, and the exhaust gas of the elevated temperature flows to the SCR reactor. Purification Method. The method of claim 4, wherein the amount of exhaust gas to be bypassed is determined in consideration of at least the catalytic reaction temperature of the SCR reactor and the type of the engine. The method of claim 4, wherein the waste heat in the exhaust gas from the SCR reactor is recovered and used. The exhaust gas purification method according to claim 4, wherein the exhaust gas before entering the SCR reactor is heated by a separate heating unit.

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