JP5296735B2 - Ships equipped with NOx reduction devices - Google Patents

Description

  The present invention relates to a ship provided with a NOx reduction device equipped with a selective catalytic reduction catalyst for purifying NOx in exhaust gas discharged from an internal combustion engine mounted on a ship, and more specifically, used in a selective catalytic reduction catalyst. The present invention relates to a ship provided with a NOx reduction device that has been devised in the arrangement of storage tanks for reducing agents such as urea.

As a technique for reducing NOx (nitrogen oxide) in exhaust gas discharged from an internal combustion engine such as a diesel engine mounted on a ship, there is a method of using a NOx reduction device equipped with a selective catalytic reduction catalyst. In this method, ammonia or a reducing agent such as urea water that generates ammonia is supplied to a selective catalytic reduction catalyst called an SCR (Selective Catalytic Reduction) catalyst, and NOx is ammonia (NH ₃ ) with nitrogen (N ₂ ) and water ( It is reduced to H ₂ O) for purification.

  As an example of this SCR method, an NOx adsorbent is disposed between the engine and the denitration catalyst, NOx is adsorbed by the adsorbent when the exhaust gas temperature is low, and desorbed when the temperature becomes high, A ship exhaust gas purifying method and a purifying apparatus that reduce NOx contained in the exhaust gas from the beginning and NOx desorbed from the adsorbent by a selective catalytic reduction method have been proposed (see, for example, Patent Document 1). .

  Moreover, in the catalyst denitration device for exhaust gas purification of the main engine of the ship, as a reducing agent storage tank for supplying the reducing agent in order to improve the reducing agent storage tank for storing the reducing agent supplied to the catalyst denitrating device, Marine reducing agent supply equipment using a tank container having a standard for marine transport containers has also been proposed (see, for example, Patent Document 2).

  In recent years, exhaust gas regulations in ships tend to be stricter, and there are cases where reduction of NOx emissions is required depending on the route, and a large amount of reducing agent such as urea water is required to reduce NOx. It is becoming. Depending on the route of the reducing agent, it is necessary to mount at least one voyage on the ship. Therefore, although depending on the route and the exhaust gas regulations in the route, the method using the NOx reduction device equipped with this selective catalytic reduction catalyst generally consumes about 10% of the reducing agent, so that a large amount of the reducing agent is consumed. It is necessary to equip a capacity reducing agent tank and to provide a large tank having a hull structure (tank with hull).

  On the other hand, the storage condition of urea water that is one of the reducing agents and is expected to be used is that, on the low temperature side, urea crystallizes around minus 10 ° C. (at a urea concentration of about 32% to 33%). It is necessary to store the container so that the temperature in the container is minus 10 ° C. or higher. On the high temperature side, when the temperature is 40 ° C., the product life is about 4 months, and the product life is greatly reduced due to the temperature rise. Therefore, it is necessary to store the product at about 30 ° C. or less. On the other hand, the outside air temperature in summer and the room temperature of the engine room may exceed 30 ° C.

  Further, the engine room in which the internal combustion engine of the ship is arranged is often provided at the rear part of the hull. As shown in FIGS. 2 and 3, the lower part of the water surface around the engine room (below the draft) Since the stern part behind the engine room has a thin shape, it is difficult to arrange the reducing agent tank. Therefore, there is a problem that it is necessary to devise to arrange a reducing agent tank having a relatively large capacity and requiring temperature management in or around the engine room.

JP 2002-295241 A JP-A-10-203487

  The present invention has been made in view of the above-described situation, and the purpose thereof is to appropriately set the temperature of the reducing agent such as urea water stored in the reducing agent tank even when the outside air temperature or the temperature in the engine room becomes high. NOx reduction device that can be maintained within a range of storage temperatures, can prevent a reduction in the life of the reducing agent, and can reduce the distance between the exhaust gas exhaust path of the internal combustion engine and the reducing agent tank It is to provide a ship having deployed.

  A ship equipped with the NOx reduction device of the present invention for achieving the above object is a NOx reduction device provided with a selective catalytic reduction catalyst for purifying NOx in exhaust gas discharged from an internal combustion engine mounted on the ship. In which a cofferdam is provided on a part or all of the outside of the reducing agent tank for storing the reducing agent to be supplied to the selective catalytic reduction catalyst to form a tank with a hull, and a part of the cofferdam or It is configured to allow water to flow through all. This water flow includes pouring and storing seawater or water in the cofferdam, and replacing the seawater or water by performing water pouring and draining simultaneously.

  According to this configuration, even when the outside air temperature or the temperature in the engine room becomes high and the heat is transferred to the reducing agent in the reducing agent tank, the seawater, river water, lake water, etc. Since the reducing agent in the reducing agent tank can be cooled by the water outside the hull, the temperature of the reducing agent can be maintained within an appropriate storage temperature range. In other words, the cofferdam reduces the heat transfer from the outside to the reducing agent from the cofferdam side, and the cooling agent can be cooled by passing water through the cofferdam, so a relatively simple configuration of pumps, control valves, piping, etc. The temperature of the reducing agent can be easily managed by relatively simple control of the pump and the control valve.

  In addition, since the reducing agent tank can be cooled, a part or all of the reducing agent tank can be provided at a location above the water line that is easily exposed to high-temperature outside air, and a large capacity reducing agent tank is provided in the engine room. It becomes easy to arrange in the inside of the engine or around the engine room. As a result, the distance between the exhaust gas exhaust path of the internal combustion engine and the reducing agent tank can be shortened.

  Further, by providing a cofferdam around a part or all of the periphery of the reducing agent tank, even if the reducing agent leaks from the reducing agent tank, it can be prevented from leaking directly to the outside because it once leaks into the cofferdam. In addition, the leakage of reducing agent can be easily monitored by inspecting the water before it is released to the outside of the ship, and the leakage inspection and treatment when the reducing agent leaks can be performed only for the water that has passed. The only thing that needs to be done is to easily prevent marine pollution from the reducing agent. Furthermore, the space inside the ship can be effectively used by forming the reducing agent tank with a tank with a hull.

  In a ship equipped with the above NOx reduction device, when the cofferdam is provided between a ship side skin or a cargo trough and the reducing agent tank is disposed adjacent to the engine room, the exhaust gas of the internal combustion engine is reduced. The distance between the discharge path and the reducing agent tank can be shortened. Moreover, if the reducing agent tank is disposed on the ship side, the piping for cooling water can be shortened.

  In a ship equipped with the NOx reduction device, a temperature sensor that measures the temperature of the reducing agent in the reducing agent tank is provided, and based on the detected value of the temperature sensor, the flow of water to the reducing agent tank is controlled. The temperature of the reducing agent can be set within a proper storage temperature range easily by simple control.

  Although depending on the conditions of the channel and the outside air temperature, when the capacity of the cofferdam is large, the temperature of the reducing agent may be within the storage temperature range simply by storing the water without replacing it.

  According to the ship equipped with the NOx reduction device of the present invention, even if the outside air temperature or the temperature in the engine room becomes high, the temperature of the reducing agent such as urea water can be maintained within the appropriate storage temperature range, and the reduction can be achieved. The reduction in the life of the agent can be prevented, and the distance between the exhaust gas exhaust path of the internal combustion engine and the reducing agent tank can be shortened. Further, even when the reducing agent tank is corroded, or when the ship side skin is damaged due to collision or grounding, the reducing agent in the reducing agent tank can be prevented from leaking directly from the ship side skin to the outside of the hull.

It is a perspective view which shows the structure of the NOx reduction device and the reducing agent tank in the ship which provided the NOx reduction device of embodiment which concerns on this invention. It is a cross-sectional view in the engine room front part of the ship which shows arrangement | positioning of a reducing agent tank. It is a transverse cross section in the engine room rear part of a ship showing arrangement of a reducing agent tank.

  Hereinafter, a ship provided with a NOx reduction device according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a ship provided with the NOx reduction device according to the embodiment of the present invention includes an internal combustion engine 2 such as a diesel engine and an exhaust gas passage 11 that is a discharge path of the exhaust gas G of the internal combustion engine 2. A NOx reduction device 12 having a selective catalytic reduction catalyst called an SCR (Selective Catalytic Reduction) catalyst provided in the middle of the exhaust gas passage 11, and for supplying the reducing agent R to the selective catalytic reduction catalyst 12. The reducing agent supply system 20 and a reducing agent cooling system 30 for cooling the reducing agent R in the reducing agent tank 21 are provided.

  The reducing agent supply system 20 includes a reducing agent tank 21, a reducing agent spray nozzle 24, a reducing agent pipe 22 that connects both of them 21, 24, and a reducing agent pump 23 disposed in the reducing agent pipe 22. And control valves 25 and 26. Further, in order to improve the exhaust gas purification performance, the exhaust gas G is supplied from the reducing agent spray nozzle 24 into the exhaust gas G in accordance with the NOx concentration in the exhaust gas, the amount of exhaust gas, and the like that change depending on the operating state of the internal combustion engine 2. A control device for exhaust gas purification that adjusts the supply amount of the reducing agent R is provided. Normally, this exhaust gas purification control device is incorporated in the operation control device of the internal combustion engine 2.

  Further, the reducing agent cooling system 30 includes a cofferdam (vacant space) 31 between the ship-side outer plate 3 and the reducing agent tank 21, a cofferdam 31 provided between the upper deck 4 and the reducing agent tank 21, and these The cofferdam 31 and the seawater intake port 37 are connected to a water passage pipe 33, a water passage pump 34 provided in the water passage pipe 33, and control valves 35 and 36. In addition, the discharge piping etc. (discharge line) which discharge | emit the seawater (or water) which passed the cofferdam 31 to the hull exterior are provided. When this reducing agent R is urea water, in consideration of corrosiveness, avoid the use of iron, copper, gunmetal, aluminum, aluminum alloy, etc., use stainless steel, or use corrosion resistant paint, polyethylene, etc. Coating with resin material.

  Further, a temperature sensor (not shown) is provided to measure the temperature of the reducing agent R in the reducing agent tank 21. Based on the output of this temperature sensor (not shown), the water flow pump 34 and the control valves 35, 36 are provided. And a control device for controlling a control valve (not shown) of an exhaust line (not shown) is incorporated into the exhaust gas purification control device or the operation control device of the internal combustion engine 2. In addition, even if the water level of the reducing agent R changes, it is installed in a low part so that only one temperature sensor is required, or a float type temperature sensor is used.

This selective catalytic reduction catalyst is formed of a titanium / vanadium-based catalyst and hydrolyzed from a reducing agent R such as urea water ((NH ₂ ) ₂ CO) ((NH ₂ ) ₂ CO + H ₂ O → 2NH ₃ + CO ₂ ). Using ammonia (NH ₃ ) generated by the above, nitrogen oxide (NOx), nitric oxide (NO) and nitrogen dioxide (NO ₂ ) are catalyzed (4NO + 4NH ₃ + O ₂ → 4N ₂ + 6H ₂ O, NO + NO ₂ Reduction to nitrogen (N ₂ ) and water (H ₂ O) by + 2NH ₃ → 2N ₂ + 3H ₂ O).

  Examples of the reducing agent R used in the selective catalytic reduction catalyst include ammonia, aqueous ammonia, and a reducing agent that generates ammonia. However, urea water is often used because of its relatively high safety. Urea water is also used in the form. When the urea concentration is about 32% to 33%, the product life will be about 4 months at about 40 ° C, and the product life will be greatly reduced due to temperature rise, so always store it at about 30 ° C or less. Is preferred. Further, since the urea water is crystallized around minus 10 ° C., it is necessary to manage the temperature of the reducing agent R in the reducing agent tank 21 so that the liquid temperature becomes minus 10 ° C. or more.

  On the other hand, the outside air temperature may exceed 30 ° C in summer, and the ship side skin 3 and upper deck 4 irradiated with direct sunlight reach temperatures exceeding 30 ° C. It is also necessary to consider the heat transfer from 4 to the reducing agent R. Furthermore, since the temperature of the engine room 5 exceeds 40 ° C., when the reducing agent tank 21 is provided adjacent to the engine room 5 in which the internal combustion engine 2 is disposed, heat from the engine room 5 side is supplied to the reducing agent R. This is necessary because it is communicated.

  For heat transfer to these reducing agent tanks 21, it is necessary to control the temperature of the reducing agent R in the reducing agent tank 21, and the engine room side wall 8 of the reducing agent tank 21 is subjected to heat insulation treatment with a heat insulating material or the like. . Further, the exhaust gas passage 11 and the reducing agent tank 21 for the exhaust gas G of the internal combustion engine 2 can also be used to reduce the amount of heat transfer in the reducing agent pipe 22 and to simplify the heat-proofing of the reducing agent pipe 22. Since it is also a good idea to shorten the reducing agent pipe 22 connecting the two, the reducing agent tank 21 is provided adjacent to the engine room 5 as shown in FIGS. FIG. 2 shows a cross section viewed from the front of the engine room, and FIG. 3 shows a cross section viewed from the rear of the engine room.

  The reducing agent tank 21 is preferably provided in a portion below the draft that is easily cooled because the outside of the ship-side outer plate 3 is immersed in seawater or water, but the stern portion is narrow and the full draft (L.W. L.) It is difficult to provide the reducing agent tank 21 below 6, especially below the ballast draft (BWL) 7, and in many cases, the ship side is easy to ensure a large capacity. It will be provided above. Further, by forming the reducing agent tank 21 as a tank with a hull, it is possible to secure a large capacity tank by effectively using the capacity of the ship.

  In the embodiment shown in FIGS. 1 to 3, heat transfer from the engine room 5 to the reducing agent tank 21 is not provided on the engine room 5 side without providing a cofferdam in order to use the volume of the engine room 5 as widely as possible. In order to reduce the amount, heat-resistant paint or heat-shielding material is attached. In addition, the upper deck 4 is configured so that a cofferdam (vacant space) 31 is provided as much as possible so that heat transfer from the upper deck 4 to the reducing agent tank 21 is blocked by the air layer. Is not provided, the upper deck 4 of the upper part of the reducing agent tank 21 is heat-resistant coated, or a heat shielding material is attached to the upper deck 4 of this part.

  Further, if the reducing agent tank 21 is also provided above the draft lines 6 and 7 on the ship side outer plate 3 side, the possibility of heat transfer from the ship side outer plate 3 side to the reducing agent tank 21 is increased. The cofa dam (vacant space) 31 is provided between the ship side skin 3 and the reducing agent tank 21, and the cooling seawater (or water) W can be passed through the cofa dam 31. Is provided with a reducing agent cooling system 30.

  Based on the temperature Tr of the reducing agent R measured by a temperature sensor (not shown) provided in the reducing agent tank 21, the water supply pump 34, the control valves 35 and 36, and the drain line (not shown) are controlled. This is done by controlling a valve (not shown). The outside of the reducing agent tank 21 is cooled by passing water (seawater or water) W outside the hull so that the temperature Tr of the reducing agent R falls within the storage temperature range.

  In consideration of the temperature Tr of the reducing agent R and the capacity of a pump that can be used for the water pump 34, the water is passed temporarily, intermittently, or continuously (always). In addition, when always passing water, the amount of water flow may be made constant, or the amount of water flow may be increased or decreased as necessary. In addition, under conditions such as the channel, the outside air temperature, the capacity of the reducing agent tank 21 and the cofferdam 31 such that the temperature Tr of the reducing agent R is kept within the storage temperature range by simply storing water without passing water, It may be stored without changing water.

  Next, a method for purifying exhaust gas in a ship provided with the NOx reduction device having the above configuration will be described.

  First, when leaving the port, the reducing agent R is loaded into the reducing agent tank 21. Seawater (or water) W outside the hull is passed through the cofferdam 31 adjacent to the reducing agent tank 21 and placed in the cofadam 31.

  Then, the temperature of the reducing agent R in the reducing agent tank 21 rises due to the engine room 5, outside air, or direct sunlight, and the temperature detected by the temperature sensor 38 is within a preset storage temperature range (for example, minus 5 ° C. to When the temperature deviates from 30 ° C., the control valves 35 and 36 are opened, the water pump 34 is driven, and seawater (or water) is injected into the cofferdam 31. If necessary, seawater (or water) in the cofferdam 31 is drained out of the ship from another drainage line (not shown).

  The temperature of seawater (or water) outside the hull is usually higher than the lower limit (eg, minus 5 ° C) of the storage temperature of the reducing agent R and lower than the upper limit (eg, 30 ° C). By adjusting, the temperature of the reducing agent R can be kept within the storage temperature range. This water flow is performed temporarily or intermittently or continuously, and the temperature of the reducing agent R is adjusted and managed by adjusting the cooling amount according to the presence / absence of the water flow or the water flow rate.

  In addition, when discharging the seawater (or water) W in the cofferdam 31, it is inspected whether the reducing agent R has leaked out, and after confirming that the reducing agent R has not leaked into the cofferdam 31, it is discharged. . Thereby, the safety | security regarding the leakage of the reducing agent R is ensured.

  When it is necessary to reduce NOx in the exhaust gas G during operation of the internal combustion engine 2, the reducing agent supply system 20 sprays the reducing agent R from the reducing agent spray nozzle 24 into the exhaust gas G. It supplies to the selective catalytic reduction catalyst of the NOx reduction device 12. This supply amount varies depending on the operation state (NOx concentration, exhaust gas amount, etc.) of the internal combustion engine and the state (temperature, deterioration, etc.) of the selective catalytic reduction catalyst. For example, the amount of fuel consumed by the internal combustion engine 2 is 10%. %.

  By supplying the reducing agent R, in the case of urea water, ammonia is generated by hydrolysis. The ammonia and NOx are converted into nitrogen and water by a reaction by the catalytic action, and NOx in the exhaust gas is purified.

  According to the ship provided with the NOx reduction device having the above-described configuration, even if the outside air temperature or the temperature in the engine room 5 becomes high, the temperature Tr of the reducing agent R such as urea water is within an appropriate storage temperature range. Thus, the life of the reducing agent R can be prevented from decreasing, and the distance between the exhaust gas G discharge path 11 of the internal combustion engine 2 and the reducing agent tank 21 can be shortened. Further, even when the reducing agent tank 21 is corroded or when the ship side skin 3 is damaged due to a collision or grounding, the reducing agent R can be prevented from leaking directly from the ship side skin 3 to the outside of the hull.

  A ship equipped with the NOx reduction device of the present invention can maintain the temperature of a reducing agent such as urea water within an appropriate temperature range even if the outside air temperature or the temperature in the engine room becomes high, and the life of the reducing agent is reduced. The reduction can be prevented, and the distance between the exhaust gas exhaust path of the internal combustion engine and the reducing agent tank can be shortened, so that it can be used as an environment-friendly ship that reduces NOx.

2 Internal combustion engine 3 Ship side shell 4 Upper deck 5 Engine room 6 Full draft 7 Ballast draft (light draft)
8 Engine room side plate 11 Exhaust passage 12 NOx reduction device 20 Reducing agent supply system 21 Reducing agent tank 22 Reducing agent piping 23 Reducing agent pump 24 Reducing agent spray nozzle 31 Cofferdam (vacant space)
33 Pipe for water flow 34 Pump for water flow G Exhaust gas R Reducing agent W Seawater or water (water outside the hull)

Claims (2)

  In order to store a reducing agent to be supplied to the selective contact reduction catalyst in a ship provided with a NOx reduction device equipped with a selective contact reduction catalyst for purifying NOx in exhaust gas discharged from an internal combustion engine mounted on the ship. Provided with a cofferdam on the outside or part of the reducing agent tank to form a tank with a hull, and deployed a NOx reduction device configured to allow water to pass through part or all of the cofferdam. Ship.   The ship provided with the NOx reduction device according to claim 1, wherein the cofferdam is provided between a ship side outer plate or a cargo trough and the reducing agent tank is disposed adjacent to an engine room.

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