KR101662394B1 - System for preheating of catalyst - Google Patents

Abstract

The present invention relates to a catalyst preheating system for preheating a catalyst that reduces nitrogen oxides (NOx) contained in an exhaust gas through a reduction reaction, and a catalyst preheating system according to an embodiment of the present invention is characterized in that the exhaust gas moves A recirculation flow path branched from the exhaust flow path in the rear of the reactor and joined to the exhaust flow path in front of the reactor, And a heating device installed therein.

Description

{SYSTEM FOR PREHEATING OF CATALYST}

The present invention relates to a catalyst preheating system, and more particularly, to a catalyst preheating system for preheating a catalyst used to reduce nitrogen oxides contained in exhaust gas.

Generally, a power unit used for a ship or the like includes a low speed diesel engine and a turbocharger. A selective catalytic reduction (SCR) system is a system for reducing nitrogen oxides by purifying exhaust gases generated from a diesel engine.

The selective catalytic reduction system reacts the nitrogen oxides contained in the exhaust gas with the reducing agent while passing the exhaust gas and the reducing agent together in the reactor equipped with the catalyst, thereby reducing the nitrogen and the water vapor.

A method of purifying the exhaust gas by applying a selective catalytic reduction system to the diesel engine is divided into a method of connecting the catalytic reduction reactor of the selective catalytic reduction system to the front end of the supercharger and a method of connecting to the rear end of the supercharger.

When the catalytic reduction reactor is connected to the upstream side of the supercharger, the reduction reaction occurs when the temperature of the exhaust gas discharged from the engine is relatively high as compared with the case where the catalytic reduction reactor is connected to the rear end of the supercharger. The amount of catalyst required for nitrogen oxides reduction can be reduced. On the contrary, the temperature and pressure of the exhaust gas flowing into the supercharger are reduced, and the performance and efficiency of the engine are lowered.

Further, when the catalyst reduction reactor is connected to the upstream side of the supercharger, if the catalyst installed in the reduction catalyst is poisoned, it is not easy to regenerate the catalyst without replacing the catalyst.

The catalyst may have an active temperature in the range of 250 degrees Celsius to 350 degrees Celsius. Here, the activation temperature refers to a temperature at which the catalyst can be stably reduced without being poisoned. When the catalyst reacts outside the active temperature range, the efficiency decreases as it is poisoned.

In particular, when exhaust gas flows having a relatively low temperature of less than 250 ° C, the catalyst poisoning material is generated by the ammonia of sulfur oxides in the exhaust gas (SOx) and a reducing agent (NH ₄₎ response. Catalyst poisoning material may comprise one or more of ammonium sulfate _{(Ammonium sulfate, (NH4) 2} SO 4) and ammonium bisulfite _{(Ammonium bisulfate, NH 4 HSO 4} ).

The catalyst poisoning material is adsorbed on the catalyst to lower the activity of the catalyst. Therefore, in order to increase the efficiency of the catalyst and to minimize the loss due to maintenance, it is required that the temperature of the catalyst be maintained within the active temperature range.

Particularly, since exhaust gas discharged at the beginning of operation of the engine has a relatively low temperature, there is a problem that the catalyst at the initial stage of operation is intensively poisoned or the nitrogen oxide is not reduced to the target value.

Specifically, the catalyst for reducing nitrogen oxides discharged from a main propulsion diesel engine for a ship has a problem that the temperature of the exhaust gas discharged from the engine at the time of docking is low, so that the catalyst does not normally reduce the nitrogen oxides, It is difficult to reduce air pollution in ports.

In addition, when the catalyst reduction reactor is connected to the upstream side of the supercharger, the valve is not easily controlled due to high pressure (3 to 4 bar level) at the time of high load.

An embodiment of the present invention provides a catalyst preheating system that can preheat a catalyst for nitrogen oxide reduction in advance to effectively reduce nitrogen oxide from the beginning of operation and suppress poisoning of the catalyst.

According to an embodiment of the present invention, there is provided a catalyst preheating system for preheating a catalyst that reduces nitrogen oxide (NOx) contained in exhaust gas through a reduction reaction, comprising: an exhaust passage through which the exhaust gas moves; A recirculation passage branched from the exhaust passage behind the reactor and joined to the exhaust passage in front of the reactor, and a heating device installed on the recirculation passage.

The catalyst preheating system may further include a blower installed on the recirculation flow path and circulating the fluid from the rear of the reactor to the front of the reactor along the recirculation flow path.

The catalyst preheating system may further include an outside air supply line that joins with the recirculation flow path to supply outside air. The outside air supply line may supply oxygen necessary for operating the heating apparatus.

The catalyst preheating system includes a first exhaust valve provided on the exhaust passage in front of a confluence point of the recirculation passage and the exhaust passage, a second exhaust valve provided on the exhaust passage behind the junction of the recirculation passage and the exhaust passage, As shown in FIG.

The catalyst preheating system may further include a bypass flow path branched from the exhaust flow path and bypassing the reactor, and a bypass valve provided on the bypass flow path.

The first exhaust valve may be closed when the temperature inside the reactor is less than 200 degrees Celsius and may be gradually opened when the temperature inside the reactor reaches 200 degrees Celsius to 300 degrees Celsius.

The catalyst may reduce nitrogen oxides (NOx) contained in the exhaust gas discharged from the engine, and may preheat the catalyst installed in the reactor using the heating apparatus while the engine is stopped before the engine is started .

According to the embodiment of the present invention, the catalyst preheating system can preheat a catalyst for reducing nitrogen oxides in advance, effectively reduce nitrogen oxides from the beginning of operation, and inhibit poisoning of the catalyst.

1 is a configuration diagram of a catalyst preheating system according to a first embodiment of the present invention.
FIG. 2 is a configuration diagram showing an operation state of the catalyst preheating system of FIG. 1. FIG.
3 is a configuration diagram of a catalyst preheating system according to a second embodiment of the present invention.
FIG. 4 is a configuration diagram showing an operation state of the catalyst preheating system of FIG. 3. FIG.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In addition, in the various embodiments, components having the same configuration are represented by the same reference symbols in the first embodiment, and in the other embodiments, only the configurations different from those of the first embodiment will be described do.

The drawings are schematic and illustrate that they are not drawn to scale. The relative dimensions and ratios of the parts in the figures are exaggerated or reduced in size for clarity and convenience in the figures, and any dimensions are merely illustrative and not restrictive. And to the same structure, element or component appearing in more than one drawing, the same reference numerals are used to denote similar features.

The embodiments of the present invention specifically illustrate ideal embodiments of the present invention. As a result, various variations of the illustration are expected. Thus, the embodiment is not limited to any particular form of the depicted area, but includes modifications of the form, for example, by manufacture.

Hereinafter, the catalyst preheating system 101 according to the first embodiment of the present invention will be described with reference to Figs. 1 and 2. Fig.

The catalyst preheating system 101 according to the first embodiment of the present invention is a catalyst preheating system for reducing a NOx contained in an exhaust gas by reducing a catalyst for selective catalytic reduction (SCR) .

Particularly, the catalyst preheating system 101 according to the first embodiment of the present invention is a system in which a catalyst for reducing nitrogen oxides contained in exhaust gas discharged from a main propulsion diesel engine for a ship, The system is preheated before operation to prevent nitrogen oxides from being reduced normally due to the low temperature of the catalyst and to prevent the release of nitrogen oxides harmful to the human body into the atmosphere.

1, the catalyst preheating system 101 according to the first embodiment of the present invention is a catalyst preheating system according to the first embodiment of the present invention. In the catalyst preheating system 101 according to the first embodiment of the present invention, Reduce one nitrogen oxide.

The engine 100 is used as a main power source of the ship, and provides a propulsion force to the ship. Engine 100 may be a low speed diesel engine, typically used in ships, and various engines known to those skilled in the art may be used.

In one embodiment of the present invention, the engine 100 discharges exhaust gas containing nitrogen oxides (NOx), sulfur components, and the like.

A turbocharger 150 rotates the turbine with the pressure of the exhaust gas of the engine 100 to supply fresh air to the engine 100.

Therefore, the performance of the turbocharger 150 can be improved as the temperature and the pressure of the exhaust gas supplied to the turbocharger 150 are higher. The efficiency of the engine 100 supplied with the compressed air from the supercharger 150 is improved.

Specifically, the catalyst preheating system 101 according to the first embodiment of the present invention includes an exhaust passage 610, a reactor 300, a recirculation passage 680, and a heating device 410.

The catalyst preheating system 101 according to the first embodiment of the present invention includes a blower 420, an outside air supply line 690, a first exhaust valve 811, a second exhaust valve 812, 620), and a bypass valve (820).

Further, the catalyst preheating system 101 according to the first embodiment of the present invention may further include a gasification chamber 460, a urea injection nozzle 470, and a urea supply unit 480.

The exhaust passage 610 is a passage through which the exhaust gas containing nitrogen oxides (NOx) moves.

For example, the exhaust passage 610 is connected to the engine 100 to move the exhaust gas discharged from the engine 100. In the first embodiment of the present invention, the supercharger 150 is installed on the exhaust passage 610 between the engine 100 and the reactor 300 to be described later.

The reactor 300 is installed on the exhaust passage 610. In the first embodiment of the present invention, the reactor 300 is installed on the exhaust passage 610 through the engine 100 and the turbocharger 150.

The reactor 300 includes a catalyst for reducing nitrogen oxides (NOx) contained in the exhaust gas discharged from the engine 100. The catalyst promotes the reaction of the reducing agent with the nitrogen oxides (NOx) contained in the exhaust gas and reduces the nitrogen oxides (NOx) to nitrogen and water vapor.

The catalyst may be made of a variety of materials known to those skilled in the art, such as zeolite, vanadium, and platinum. In one example, the catalyst may have an active temperature in the range of 250 degrees Celsius to 350 degrees Celsius. Here, the activation temperature refers to a temperature at which the catalyst can be stably reduced without being poisoned. When the catalyst reacts outside the active temperature range, the efficiency decreases as it is poisoned.

In particular, when exhaust gas flows having a relatively low temperature of less than 250 ° C, the catalyst poisoning material is generated by the ammonia of sulfur oxides in the exhaust gas (SOx) and a reducing agent (NH ₄₎ response. Catalyst poisoning material may comprise one or more of ammonium sulfate _{(Ammonium sulfate, (NH4) 2} SO 4) and ammonium bisulfite _{(Ammonium bisulfate, NH 4 HSO 4} ).

The catalyst poisoning material is adsorbed on the catalyst to lower the activity of the catalyst. That is, when the nitrogen oxide reduction efficiency is lowered, it can be judged that the catalyst is poisoned. Such catalyst poisonous materials can be decomposed or removed by an external heat source.

Also, the housing of the reactor 300 can be made of, for example, stainless steel.

The recirculation flow path 680 branches off from the exhaust flow path 610 behind the reactor 300 and joins the exhaust flow path 610 in front of the reactor 300. That is, the exhaust gas passing through the reactor 300 can be introduced into the reactor 300 through the recycle conduit 680 again. That is, the exhaust gas passing through the reactor 300 can be recycled through the circulation passage 680.

The heating device 410 is installed on the recirculation flow path 680 to raise the temperature of the fluid flowing through the recirculation flow path 680. The fluid heated by the heating device 410 is circulated through the exhaust flow path 610 and the recirculation flow path 680 to raise the temperature of the catalyst provided inside the reactor 300. At this time, since the heating device 410 continuously heats the circulating fluid, the fluid can be heated using a relatively small amount of energy. That is, the energy consumed for raising the temperature of the catalyst installed in the reactor 300 can be minimized.

Further, in the first embodiment of the present invention, the heating device 410 may be a burner.

The blower 420 is installed on the recirculation passage 680. The blower 420 recirculates the fluid back to the reactor 300 in the rear of the reactor 300 along the recirculation flow path 680.

The outside air supply line 690 joins with the recirculation flow path 680 to supply outside air. Specifically, the outside air supply line 690 supplies outside air to the heating apparatus 410. Thus, the heating device 410 can stably receive the oxygen required for the operation.

The first exhaust valve 811 is installed on the exhaust passage 610 in front of the confluence point of the recirculation passage 680 and the exhaust passage 610. The second exhaust valve 812 is connected to the recirculation passage 680 and the exhaust passage 610 The first exhaust valve 811 and the second exhaust valve 812 regulate the flow of the exhaust gas flowing into the reactor through the exhaust passage 610. The exhaust valve 610 is connected to the first exhaust valve 811 and the second exhaust valve 812,

The bypass flow path 620 branches off the exhaust flow path 610 and bypasses the reactor 300 to move the exhaust gas.

That is, when the first exhaust valve 811 and the second exhaust valve 812 are closed to shut off the exhaust passage 610, the exhaust gas can be moved through the bypass passage 620.

The bypass valve 620 is provided on the bypass passage 620 to prevent the exhaust gas from moving along the bypass passage 620 unnecessarily in a state where the first exhaust valve 811 is opened.

The gasification chamber 460 is installed on the recirculation passage 680.

The urea injection part 470 is installed in the gasification chamber 460 and injects urea (CO (NH ₂ ) ₂ ) into the gasification chamber 460. In the gasification chamber 460, the urea is decomposed to produce ammonia.

Specifically, the gasification chamber 460 receives urea (CO (NH ₂ ) ₂ ) and hydrolyzes it to produce ammonia (NH ₃ ). Ammonia (NH ₃ ) is used as a reducing agent for reducing nitrogen oxides.

When the internal temperature of the gasification chamber 460 is maintained within the range of 300 to 500 degrees centigrade, the urea injected into the gasification chamber 460 is easily hydrolyzed and ammonia (NH ₃ ) and isocyanic acid HNCO) is produced, and isocyanic acid (HNCO) is decomposed again into ammonia (NH ₃ ) and carbon dioxide (CO ₂ ).

The urea supply unit 480 stores the urea and supplies the stored urea to the urea injection unit 470.

Further, in the first embodiment of the present invention, the urea injector 470 injects the urea when the engine is started after the preheating of the catalyst is finished.

And the temperature inside the vaporization chamber 460 is regulated by the heating device 410. That is, the heating device 410 not only supplies thermal energy for preheating the catalyst at the beginning of operation, but also supplies thermal energy for decomposing the urea during operation.

In addition, since the gasification chamber 460 is provided on the recirculation passage 580, the thermal energy of the exhaust gas passing through the reactor 300 can also be utilized.

With such a structure, the catalyst preheating system 101 according to the first embodiment of the present invention can preheat the catalyst for reducing nitrogen oxide in advance, effectively reduce the nitrogen oxide from the beginning of operation, and suppress the poisoning of the catalyst .

Hereinafter, the operation principle of the catalyst preheating system 101 according to the first embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2. FIG.

As shown in Fig. 1, when the engine 100 is to be started in a stopped state, the first exhaust valve 811 is closed. At this time, the first exhaust valve 811 maintains the closed state when the temperature inside the reactor 300 is less than 200 degrees Celsius. The outside air supplied through the outside air supply line 690 is circulated through the recirculation line 680 and the exhaust flow path 610 by using the blower 420 and heated by the heating device 410. The heated fluid preheats the catalyst and raises the catalyst to the activation temperature. At this time, the burner can be used as the heating device 410. The outside air introduced through the outside air supply line 690 can supply the necessary oxygen to the heating device 410, which is a burner for heating the circulating fluid.

In addition, the second exhaust valve 812 may be closed or partially open to regulate the pressure of the fluid circulating through the recirculation line 680. That is, when the ambient air continuously flows into the outside air supply line 690, the pressure inside the system may be increased. Therefore, the second exhaust valve 812 may be partially opened so that the pressure inside the system maintains an appropriate pressure.

As shown in Fig. 2, when the temperature inside the reactor 300 reaches 200 degrees Celsius to 300 degrees Celsius degrees, the first exhaust valve 811 is gradually opened. The second exhaust valve 812 is likewise opened.

The exhaust gas discharged from the engine 100 is gradually introduced into the reactor 300 through the first exhaust valve 811 while the engine 100 is started.

When the engine 100 is started, the fluid moving along the recirculation passage 680 is heated by the heating device 410 to a temperature necessary for urea decomposition and is transferred to the gasification chamber 460, and the gasification chamber 460 The ammonia produced by decomposition of urea is mixed with the fluid flowing along the recycle flow path 680 and is transferred to the reactor 300.

The ammonia, that is, the reducing agent, which has been transferred to the reactor 300, is reduced by the catalyst with the nitrogen oxide contained in the exhaust gas to reduce the concentration of nitrogen oxide in the exhaust gas.

As described above, the catalyst preheating system 101 according to the first embodiment of the present invention circulates through the recycle line 680 before starting the engine, that is, before the exhaust gas containing nitrogen oxides flows into the reactor 300 The temperature of the catalyst is increased by heating the fluid with the heating device 410 so that the temperature of the exhaust gas discharged from the engine 100 at the time of dispatching the vessel is low so that the catalyst can not normally reduce nitrogen oxides and nitrogen oxides Air pollution in the port caused by the discharge can be effectively reduced.

Hereinafter, a catalyst preheating system 102 according to a second embodiment of the present invention will be described with reference to FIGS. 3 and 4. FIG.

3 and 4, the catalyst preheating system 102 according to the second embodiment of the present invention has the reactor 300 disposed between the engine 100 and the turbocharger 150. That is, the exhaust gas before passing through the turbocharger 150 flows into the reactor 300.

The second embodiment is the same as the first embodiment except for the position of the reactor 300.

That is, even if the reactor 300 is located between the engine 100 and the turbocharger 150, that is, even if the reactor is exposed to a relatively high temperature and high pressure environment, the catalyst can be effectively preheated as in the second embodiment of the present invention .

With such a structure, the catalyst preheating system 102 according to the second embodiment of the present invention can also preheat the catalyst for reducing nitrogen oxides in advance, effectively reducing the nitrogen oxides from the beginning of operation and suppressing the poisoning of the catalyst .

As described above, according to the first and second embodiments of the present invention, it is possible to effectively preheat the catalyst regardless of the positional relationship between the reactor 300 and the turbocharger 150, But also the problems caused by low temperature of the exhaust gas discharged from the engine 100 can be solved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. will be.

It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

101: Catalyst preheating system
100: first engine 150: supercharger
300: Reactor 410: Heating device
420: blower 460: gasification chamber
470: Urea dispensing part 480: Urea supplying part
610: exhaust channel 620: bypass channel
680: recirculation channel 690: outside air supply line
811: first exhaust valve 812: second exhaust valve
820: Bypass valve

Claims (7)

A catalyst preheating system for preheating a catalyst that reduces nitrogen oxides (NOx) contained in exhaust gas through a reduction reaction,
An exhaust passage through which the exhaust gas moves;
A reactor provided on the exhaust flow path and provided with the catalyst therein;
A recirculation flow path branched from the exhaust flow path behind the reactor and joined to the exhaust flow path in front of the reactor;
A heating device installed on the recirculation flow path;
An outside air supply line which joins with the recirculation flow path and supplies outside air for supplying oxygen necessary for operating the heating apparatus; And
A first exhaust valve provided on the exhaust passage in front of a confluence point of the recirculation passage and the exhaust passage,
/ RTI >
If the internal temperature of the reactor is lower than a predetermined temperature, the first exhaust valve is closed and the heating device is activated to preheat the catalyst inside the reactor,
Wherein the first exhaust valve is opened and the exhaust gas flows into the reactor to preheat the catalyst in the reactor when the internal temperature of the reactor is above a predetermined temperature. delete delete The method according to claim 1,
Further comprising a second exhaust valve provided on the exhaust passage behind the junction of the recirculation passage and the exhaust passage,
Wherein the second exhaust valve is partially or wholly opened when the internal temperature of the reactor is closed or partially opened when the internal temperature of the reactor is lower than a preset temperature and is higher than a predetermined temperature. The method according to claim 1 or 4,
Wherein the first exhaust valve is closed when the temperature inside the reactor is less than 200 degrees Celsius and is gradually opened when the temperature inside the reactor reaches 200 degrees Celsius to 300 degrees Celsius. The method according to claim 1 or 4,
And a blower installed on the recirculation flow path to circulate the fluid in the rear of the reactor in front of the reactor along the recirculation flow path. The method according to claim 1 or 4,
A bypass flow path branched from the exhaust flow path and bypassing the reactor;
And a bypass valve
Further comprising a catalyst preheating system.

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