KR20210035596A - Producing Device And Method Of Urea Solution For SCR In Ship - Google Patents

Abstract

A device and method for producing an aqueous urea solution for SCR of a ship are provided. The device for producing an aqueous urea solution for SCR of a ship of the present invention includes: a urea storage tank unit provided on a ship and storing urea powder; a stirring tank that receives the urea powder and mixes the urea powder with fresh water to generate an aqueous urea solution to be supplied to a selective catalytic reduction device (SCR) provided on the ship; a supply tank that receives the urea powder from the urea storage tank unit and transfers the urea powder of a fixed amount to the stirring tank; an injector for generating air bubbles for mixing the urea powder and fresh water by injecting gas into the lower part of the stirring tank; and a control panel for controlling the transfer of urea from the urea storage tank unit and the supply tank and generation of the aqueous urea solution in the stirring tank. The present invention reduces the installation cost and installation space of tanks, pipes, related devices, and the like.

Description

Producing Device And Method Of Urea Solution For SCR In Ship}

The present invention relates to an apparatus and method for producing an aqueous urea solution for SCR of a ship, and more particularly, an apparatus for producing an aqueous urea solution for SCR of a ship to prepare an aqueous urea solution to be supplied to a selective catalytic reduction device of a ship by mixing urea powder and fresh water. And a method.

In recent years, when burning heavy oil and MDO (Marine Diesel Oil), which are conventionally used as fuel for various engines in ships, serious environmental pollution due to various harmful substances contained in exhaust gas has emerged, and oil such as heavy oil is used as fuel. Regulations on various engines of ships are being strengthened.

In general, among the exhaust gas components emitted from ships, nitrogen oxides (NOx) and sulfur oxides (SOx) are regulated by the International Maritime Organization (IMO) under the UN, and EU (European Union), CARB (California). Air Resources Board) and other organizations and organizations also have restrictions on the emission of sulfur oxides (SOx). The Protocol on the Prevention of Marine Pollution from Ships (MARPOL 1973/1978; The Prevention of Marine Pollution from Ships), drafted in 1973 and revised and supplemented in 1978, is also in effect.

Ships operating within the sulfur oxide emission control area regulated by some organizations and organizations are obligated to use Low Sulfur Marine Gas Oil with a sulfur content of up to 0.1% or less depending on the time of application. According to the IMO's Global Sulfur Oxide Emission Regulation (Global Sulfur Cap 2020), the standard for sulfur oxide content in ship fuels is strengthened from 3.5% to 0.5%.

For nitrogen oxides, IMO Tier III is applied in the North American and Hawaiian coastal areas from 2016, and in the Northern Europe and Baltic Seas from 2021, in the Emission Control Area (ECA), and in other regions, Tier II is applied, and is discharged from diesel engines. The amount of nitrogen oxides in the exhaust is regulated.

Representative systems applied to ship engines to satisfy Tier II or Tier III include Exhaust Gas Recirculation (EGR) and Selective Catalytic Reduction (SCR) devices.

SCR is a method of reducing nitrogen oxides through a reduction reaction by installing an SCR reactor in an exhaust pipe through which exhaust gas generated after combustion of fuel passes. More specifically, ammonia and NOx injected from the inside of the SCR reactor react in the presence of a catalyst _{to change into N 2} and H ₂ O, thereby reducing the NOx content, and the reaction equation is as follows.

For safety, ammonia is supplied to the SCR system in the form of an aqueous urea solution ((NH ₂ ) ₂ CO). In this urea aqueous solution, urea is decomposed into ammonia and carbon dioxide through the following reaction.

In the SCR system, the temperature of the incoming exhaust gas is important. The minimum required temperature for SCR depends on the sulfur content of the fuel and thus the formation of sulfur oxides in the exhaust gas. At low temperatures, sulfur oxides are neutralized by ammonia and form ABS (ammonium bisulphate, NH ₄ HSO ₄ ) as a reactant, which can easily stick to the inside of the SCR reactor and accumulate. This reaction can be prevented to some extent by maintaining a high temperature. If the sulfur content in the fuel oil is 0.1 or less, the temperature in the SCR reactor is sufficient to be 310°C. The lower the exhaust gas pressure, the lower the required minimum required temperature.

On the other hand, when reaching a too high temperature inside the catalyst there are SO ₃ can be formed, SO ₃ will later form the aerosols of the undesirable white in response to the water turning into sulfuric acid. Another unwanted reaction is _{the oxidation of NH 3} , which occurs when the exhaust gas temperature approaches 500°C, and when the temperature of the exhaust gas approaches 500°C, the catalyst starts to be silicified (sintered). The maximum permissible temperature is determined.

It is important to maintain the temperature of the exhaust gas within an appropriate range for reliable SCR operation as described above.

1 and 2 schematically illustrate a conventional SCR system, respectively.

The SCR system shown in FIG. 1 is a HP (High Pressure) SCR system in which a combined vaporizer/mixer unit 20 and an SCR reactor 10 are installed. In the vaporizer 20, a reducing agent is injected and mixed with exhaust gas, and then a catalytic reaction starts, and the mixed exhaust gas is introduced into the SCR reactor.

Since the SCR process requires a relatively high reaction temperature, in the case of a two-stroke diesel engine, it is advantageous to place the SCR piping on the High Pressure Side (in front of the turbocharger (T/C)). Depending on the engine 50 load, the exhaust gas temperature is 50 to 175°C higher than the Low Pressure Side (T/C rear end). When operating in Tier II mode, close the Reactor Sealing Valve (RSV) and Reactor Throttle Valve (RTV) to cut off the SCR system. In addition, by opening the Reactor Bypass Valve (RBV), the exhaust gas is sent directly to the T/C. The SCR system is equipped with an Exhaust Gas Bypass Valve (EGB) to provide Low Load EGB turning. When opening the SCR piping, open RSV and RTV and close RBV.

Although the reactor is installed in front of the T/C, the exhaust gas temperature is low when the engine is operated under low load, so the cylinder bypass from the Scavenge Air Receiver (40) to the T/C in order to increase the temperature of the exhaust gas. Install the pipe (Cylinder Bypass line) and control it through the Cylinder Bypass Valve (CBV). When the bypass valve is opened, the amount of air flowing into the cylinder can be reduced without reducing the desired pressure, and the temperature of the exhaust gas rises. This system makes it possible to keep the temperature of the exhaust gas above the required level in the full load range of the engine. However, cylinder bypass increases fuel consumption SFOC (Specific Fuel Oil Consumption) to some extent.

The HP SCR reactor and vaporizer have a very large heat capacity, which can lead to thermal stagnation between the T/C and the exhaust receiver, which may cause instability of the engine and T/C due to the heat capacity of the SCR during Tier III operation. In order to reduce such instability, charge air is additionally supplied to an auxiliary blower to stabilize the system.

The SCR system shown in FIG. 2 is an LP (Low Pressure) SCR system, and an LP SCR can be installed if the sulfur content of the fuel oil is limited to 0.1% or less. LP SCR piping can be installed at the rear end of the T/C, so it can have flexibility in the installation location.

As shown in FIG. 2, the LP SCR system includes three main components, an SCR Reactor 10, a mixer (Ammonia Injection Grid, AIG), and a decomposition unit (DCU). The DCU is located between the reactor outlet and the mixer inlet and consists of a blower 22, a heater (Burner, 21) and a vaporizer (20). The reducing agent is injected into the vaporizer 20 to form a mixture of ammonia vapor, flows into the mixer (AIG), and is transferred to the SCR reactor 10 by a blower. Even if low sulfur fuel is used, the exhaust temperature may be low when the engine is operated under a low load or when the outside temperature is low.In this case, the exhaust gas on the high pressure side is turned off by turning the exhaust gas bypass pipe valve (EGB) to increase the exhaust temperature. It can be opened to bypass the turbocharger (T/C), and in this process, the SFOC increases by a certain amount.

In the SCR device, anhydrous ammonia (NH3), NH ₃ aqueous solution (25% NH ₃ ) or urea aqueous solution (32.5% or 40% aqueous solution) may be used as a reducing agent. Among them, anhydrous ammonia is dangerous as a toxic substance, and urea is preferred in ships because of its strong corrosiveness and harmfulness to the human body and the environment.

3 schematically shows an example of a urea supply system for supplying urea to a conventional ship's SCR device.

As shown in FIG. 3, urea, that is, an aqueous urea solution, is stored in a storage tank and transferred to the vaporizer/mixer 20 through a supply unit SU including a pump P. The amount of urea injected and the amount of compressed air supplied into the vaporizer/mixer are controlled through a control unit (not shown). When the SCR process is shut down, in order to prevent clogging of the urea injection nozzle, the urea injection nozzle (IU) or the like is purged using the water stored in the tank in the supply unit.

In the case of such a conventional urea supply system, since the urea aqueous solution is supplied from land and stored and supplied to the SCR device, the size of the tank for storing it increases. However, when the existing IMO Tier II regulations were applied, it is necessary to install such a tank. As there was no, there is a design difficulty in securing an additional space for tank installation in a limited space on board the ship. In addition, considering the reactivity with ammonia generated by decomposition during storage of urea aqueous solution while meeting the shipbuilding standards, the material of the storage tank is limited to some parts such as stainless steel, and a special coating may need to be applied inside the tank. The related piping production cost also has a high problem.

In addition, there is a problem that the service life continues to decrease over time when stored as an aqueous urea solution, and the service life varies depending on the storage temperature. Considering that the average one operation of a ship is about 30 days, the temperature is increased to 35℃. It should be kept below degrees Celsius, and since it should be kept above 1℃ to prevent freezing of the urea aqueous solution inside the storage tank, both a heating device and a cooling device are required for temperature control, and their installation space and installation cost are also problematic. .

The present invention is to solve this problem, to reduce the installation cost and installation space of the tank and piping, related devices, etc., and to propose a device capable of supplying a urea aqueous solution.

According to an aspect of the present invention for solving the above-described problem, the urea storage tank portion provided on the ship and storing urea powder;

A stirring tank receiving the urea powder and mixing it with fresh water to generate a urea aqueous solution to be supplied to the selective catalytic reduction device (SCR) provided in the ship;

A supply tank for receiving the urea powder from the urea storage tank and transferring the urea powder in a quantity to the stirring tank;

An injection device for generating bubbles for mixing the urea powder and fresh water by injecting gas under the stirring tank; And

There is provided an apparatus for producing a urea aqueous solution for SCR of a ship comprising a; control panel for controlling the urea storage tank unit and the supply tank to control the urea transfer and generation of the urea aqueous solution in the stirring tank.

Preferably, the urea storage tank unit comprises: a storage tank for storing the urea powder; A manhole provided above the storage tank to put the urea powder into the storage tank; A hopper provided below the storage tank and supplying the urea powder to be transferred to the supply tank; And a first ejector provided under the hopper; injecting gas to the first ejector, supplying the urea powder to the suction unit of the first ejector, and transferring the urea powder to the supply tank can do.

Preferably, the device comprises: a residual amount detector for sensing the weight of the urea powder stored in the supply tank; And a first vent line that discharges gas from the supply tank to prevent overpressure of the supply tank, further comprising, from the urea storage tank part in the control panel according to the amount of the urea powder detected by the residual amount sensor. It is possible to control the amount of the urea powder to be transferred to the supply tank.

Preferably, the supply tank has a funnel shape that becomes narrower toward the bottom, and at least one spiral feeder driven by a motor is provided inside the supply tank so that the urea powder can be transferred to the bottom. .

Preferably, the device includes: a fresh water supply line for supplying fresh water to the stirring tank; A heater provided in the stirring tank to supply thermal energy for preventing overcooling when the urea aqueous solution is generated; A first temperature sensor sensing the temperature of the stirring tank; And a first liquid level sensor for sensing the liquid level of the stirring tank, wherein the control panel controls the amount of fresh water to be supplied to the stirring tank according to the liquid level detected by the first liquid level sensor, and 1 The heater can be controlled according to the temperature value sensed by the temperature sensor.

Preferably, the device includes: an ion removing filter provided in the fresh water supply line; A first gas supply line connected to the injection device and transferring the gas to be supplied into the stirring tank; A concentration sensing device for sensing the concentration of the aqueous urea solution generated in the stirred tank; And a second ejector connected to the first gas supply line, wherein the liquid passing through the concentration sensing device is supplied to the suction port of the second ejector, together with the gas supplied to the first gas supply line. It can be introduced into the stirring tank.

Preferably, the device comprises: a service tank through which the urea aqueous solution generated in the stirring tank is transferred; A reducing agent supply line for supplying the urea aqueous solution from the service tank to the selective catalytic reduction device unit; A second level sensor for sensing the level of the service tank; And a second temperature sensor for sensing the temperature of the service tank.

Preferably, the device further includes a second gas supply line for supplying the gas to the first ejector, wherein the gas supplied through the first and second gas supply lines is nitrogen, control air ), may be any one of Service Air.

Preferably, the apparatus includes: a third gas supply line branched from the first and second gas supply lines and connected to the storage tank; And

A second vent line provided in the storage tank to relieve overpressure and negative pressure of the storage tank; further comprising,

By supplying the gas to the storage tank through the third gas supply line, solidification of the urea powder may be prevented, and the urea powder may be constantly transferred from the storage tank to the hopper.

Preferably, in the control panel,

1) determining an amount of the urea powder to be supplied from the storage tank to the supply tank;

2) transferring the urea powder to the supply tank by an amount determined in step 1) by injecting gas through the first ejector;

3) determining whether to generate the urea aqueous solution according to the level of the service tank detected by the second level sensor;

4) determining the amount of the urea powder and fresh water to be supplied to the stirring tank;

5) supplying the urea powder to the stirring tank by driving the spiral supply device;

6) Confirming that the level of the stirring tank is empty, and supplying fresh water to the stirring tank by the amount determined in step 4) through the fresh water supply line while detecting the level by the first level sensor. step; And

7) Nitrogen is injected into the bottom of the stirring tank through the injection device, and nitrogen is passed through the second ejector to form a liquid flow flowing from the stirring tank to the stirring tank through the concentration sensing device. Stirring the material inside the stirring tank while sensing the concentration of the aqueous urea solution generated in; control to prepare the aqueous urea solution.

According to another aspect of the present invention, in a method for producing an aqueous urea solution for supply to a selective catalytic reduction device (SCR) provided on a ship,

1) determining the amount of urea powder to be supplied to the supply tank from the storage tank in which the urea powder is stored;

2) transferring the urea powder to the supply tank by the amount determined in step 1);

3) determining whether or not the urea aqueous solution is generated by detecting the level of the service tank storing the generated urea aqueous solution;

4) determining the amount of fresh water and urea powder to be introduced into the stirring tank for generating the urea aqueous solution;

5) While transferring the urea powder from the supply tank to the stirring tank, confirming that the level of the stirring tank is empty, and detecting the level of the stirring tank, the stirring tank by the amount determined in step 4) Supplying fresh water to the furnace;

6) The urea powder and fresh water are mixed by air bubbles generated by injecting gas to the bottom of the stirring tank, and a part of the solution generated in the stirring tank is discharged to the outside of the tank to detect the concentration and then flow into the stirring tank. Includes;

The transport of the urea powder to the supply tank in step 2) and the inflow of the solution sensing the concentration in step 6) into the stirring tank are performed by injecting gas through an ejector. A method for preparing an aqueous urea solution is provided.

Preferably, the transfer of the urea powder from the supply tank to the stirring tank in step 5) may be performed by a spiral feeder provided in the lower inner side of the supply tank.

Preferably, a hopper for supplying the urea powder to be transferred to the supply tank is provided at a lower portion of the storage tank, and gas is injected into the storage tank to prevent solidification of the urea powder, and the urea powder is It can be constantly transferred from the storage tank to the hopper.

According to the apparatus and method for producing an aqueous urea solution for SCR of the present invention, it is possible to store urea in a powder state, generate an aqueous urea solution on board when necessary, and supply it to the SCR, so there is no need to install a large-scale storage tank to store the aqueous urea solution. It can reduce the production and installation cost of tanks and piping, improve the productivity of the ship, and contribute to securing the space inside the ship.

In addition, when preparing an aqueous urea solution, gas such as nitrogen is injected into the bottom of the stirring tank so that the urea powder is smoothly dissolved by the generated bubbles.

In particular, since the urea aqueous solution can be prepared and immediately supplied to the SCR when necessary without long-term storage in the state of an aqueous urea solution, it is possible to prevent deterioration of the performance as a reducing agent due to stratification or dissociation of the urea aqueous solution in the storage tank according to the concentration gradient during long-term storage I can.

1 and 2 schematically show a high pressure (HP) SCR system and a low pressure (LP) SCR system among conventional SCR systems, respectively.
3 schematically shows an example of a urea supply system for supplying urea to a conventional ship's SCR device.
4 schematically shows an apparatus for producing an aqueous urea solution for SCR of a ship according to an embodiment of the present invention.
FIG. 5 is a detailed illustration of the apparatus for preparing an aqueous urea solution shown in FIG. 4.
6 shows a specific shape of a device implementing the apparatus for preparing an aqueous urea solution schematically illustrated in FIGS. 4 and 5.

In order to fully understand the operational advantages of the present invention and the object achieved by the implementation of the present invention, reference should be made to the accompanying drawings illustrating preferred embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, the configuration and operation of a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Here, in adding reference numerals to elements of each drawing, it should be noted that only the same elements are marked with the same numerals as possible, even if they are indicated on different drawings.

In the embodiments of the present invention to be described later, the ship is equipped with an engine that can use fuel oil such as low sulfur oil and high sulfur oil alone as fuel for a propulsion engine or fuel for a power generation engine, or in combination with other fuels such as LNG. It may be all types of ships where an engine using fuel oil is provided and a selective catalytic reduction system (SCR) for treating exhaust gas is applied. Representatively, ships with self-propelled capabilities such as LPG carriers, LNG carriers, liquid hydrogen carriers, and LNG Regasification Vessels, as well as LNG Floating Production Storage Offloading (FPSO), and LNG Floating Storage Regasification Unit (FSRU) It may also include offshore structures that do not have propulsion capabilities, but are floating on the sea.

4 schematically shows an apparatus for producing an aqueous urea solution for SCR according to an embodiment of the present invention. FIG. 5 shows the device for preparing an aqueous urea solution shown in FIG. 4 in more detail, and FIG. 6 illustrates a specific shape of the device implementing the device for preparing an aqueous urea solution schematically illustrated in FIGS. 4 and 5. FIG.

Looking at the device of this embodiment with reference to Figures 4 to 6, the urea storage tank unit 100 provided on the ship and storing urea powder, the selective catalytic reduction device (SCR) provided on the ship by mixing it with fresh water by receiving the urea powder. The stirring tank 200 for generating an aqueous urea solution to be supplied to (not shown), the supply tank 300 for receiving urea powder from the urea storage tank and transferring the amount of urea powder to the stirring tank, and the SCR generated in the stirring tank It is configured to include a service tank 500 to which the urea aqueous solution to be supplied is transferred.

An injection device that creates bubbles for mixing urea powder and fresh water by injecting gas into the lower part of the stirring tank is provided in the stirring tank, and each component such as urea transfer from the urea storage tank and supply tank and generation of urea aqueous solution in the stirring tank They are controlled by the control panel 400.

The urea storage tank 100 includes a storage tank 110 for storing urea powder, a manhole 120 provided at the top of the storage tank so that urea powder can be injected into the storage tank, and a supply tank provided under the storage tank. It includes a hopper 130 to which the urea powder to be transferred to is supplied. A first ejector 140 is provided under the hopper. The gas is injected into the first ejector, and the urea powder is supplied to the suction part of the first ejector, so that the urea powder is transferred to the supply tank together with the gas.

In the storage tank, the amount of urea powder transferred to the supply tank and filled in the supply tank may be a capacity capable of generating about two urea aqueous solutions in the stirring tank.

Instead of transferring the urea powder from the storage tank to the supply tank by the suction force of the first ejector via the hopper, the urea powder may be transferred by providing a spiral feeder like a supply tank to be described later.

A pipe for transferring the urea powder from the storage tank to the lower hopper is connected, and a first valve V1 is provided in the pipe. The opening and closing of the first valve can be controlled by the control panel.

The urea storage tank unit 100 is provided with a storage amount measuring device 150 for notifying that filling of urea powder is required when the amount of urea stored in the storage tank falls below a reference value.

The supply tank 300 is provided with a residual amount detector 310 that detects the weight of the stored urea powder, and transfers the urea powder by the first ejector from the storage tank 110 through the hopper 130 according to the sensed residual amount of the urea powder. Thus, the supply tank 300 is filled with urea powder. In this way, the transfer of urea powder from the urea storage tank to the supply tank is controlled by the control panel 400.

The residual quantity detector and the storage quantity measurement device provided in the urea storage tank include a weight sensor, and noise may be generated according to the vibration of the vessel and the pitch/yaw/roll motion, so the weight sensors provided in this apparatus suppress noise. An electronic filter may be installed, or a function corresponding thereto may be provided.

Since the urea powder and gas are supplied from the hopper to the supply tank together through the first ejector, the first vent line VL1 is provided to discharge the gas from the supply tank 300 to prevent overpressure of the supply tank. In addition, a second vent line VL2 is also provided in the storage tank 110 to relieve overpressure and negative pressure in the storage tank, and gas in the storage tank can be discharged to the outside of the device.

The supply tank 300 has a funnel shape and a Hopper-type structure whose interior becomes narrower toward the bottom, and urea powder is transferred from the supply tank to the stirring tank through an outlet at the bottom. A spiral feeder (320) driven by a motor is provided inside the supply tank, so that a predetermined amount of urea powder may be transferred to the lower portion while the spiral feeder is rotated by the motor.

Two spiral supply devices 320 are installed in the lower inner side of the supply tank. If only one side of the spiral supply device is operated, the urea powder on the other side of the supply tank can be accumulated without being transferred to the stirring tank, so it is preferable to operate the spiral supply devices installed on both sides together or alternately.

The operation of the motor driving the helical supply device 320 is also controlled by the control panel 400, and the feed rate of the urea powder can be adjusted by the control panel.

The urea powder transferred to the lower portion of the supply tank by the spiral supply device is supplied to the stirring tank 200 through a pipe connected to the stirring tank. The piping is provided with second valves V2a and V2b, which are opened and closed by a control panel, so that the amount of urea powder supplied to the stirring tank can be finely adjusted.

The urea powder may not be supplied from the storage tank to the supply tank while the urea powder is transferred to the stirring tank so that a quantity of urea powder can be transferred to the stirring tank to generate a necessary concentration of the urea aqueous solution.

The urea powder transferred from the supply tank to the stirring tank is dissolved in fresh water in the stirring tank, and an aqueous urea solution is generated in the stirring tank.

A fresh water supply line CL for supplying fresh water to the stirring tank 200 is provided, and fresh water for generating a urea aqueous solution can be supplied from the fresh water supply system (not shown) of the ship to the stirring tank. In the fresh water supply line, a fresh water supply valve (not shown) for controlling the supply of fresh water and an ion removing filter 250 capable of removing unnecessary ions such as Ca and Mg are provided. The supply of fresh water may also be controlled by controlling the fresh water supply valve in the control panel 400.

In the stirring tank, when gas is injected from the injection device 210 provided at the lower part, the injected gas moves to the top of the stirring tank in the form of bubbles to stir the urea powder and fresh water.

The stirring tank includes a heater 220 that supplies thermal energy to prevent overcooling when an aqueous urea solution is generated, a first temperature sensor 230 that detects the temperature of the stirring tank, and a first liquid level sensor that detects the liquid level of the stirring tank. 240 may be provided.

The control panel 400 controls the opening and closing of the valve according to the level value sensed by the first level sensor 240 to control the amount of fresh water to be supplied to the stirring tank, and is sensed by the first temperature sensor 230. The temperature of the urea aqueous solution in the stirring tank may be controlled by controlling the heater 220 according to the temperature value. Since the dissolution of urea is an endothermic reaction, by supplying thermal energy to the stirring tank through the heater 220, it is possible to increase the dissolution rate while preventing overcooling. For example, when preparing 500kg of AUS40 (40% Urea solution), the heat of dissolution is-61.1 kcal/kg x 500 kg x 0.4 = -12 220 kcal. The heater may be installed as an electric heater or a steam heater type.

The line for supplying gas to the device of this embodiment is a first gas supply line SL1 connected to the injection device 210 to transfer gas to be supplied into the stirring tank, and the first ejector of the urea storage tank 100 140 and a second gas supply line SL2 for transferring gas to be supplied to the hopper 130, and a third gas supply line SL3 connected to the storage tank 110 of the urea storage tank unit, and After supplying gas into the apparatus through a single supply line, the gas can be supplied in each configuration by branching to the first to third gas supply lines. Gas supplied in each configuration through the first to third gas supply lines is, for example, nitrogen (N ₂ ), dry air, control air, service air, etc. Can be.

By supplying gas to the storage tank through the third gas supply line, solidification such as sticking and agglomeration of the urea powder can be prevented, and the urea powder can be uniformly transferred from the storage tank to the hopper. In addition, a fourth gas supply line SL4 for supplying gas to the supply tank 300 may be provided so that the urea powder can be smoothly transferred.

Outside the stirring tank 200, a concentration sensing device 260 for sensing the concentration of the urea aqueous solution generated in the stirring tank is provided, and the second ejector 270 is connected to a line branched from the first gas supply line SL1. Thus, the liquid that has passed through the concentration sensing device is supplied to the suction port of the second ejector so that it can be introduced into the stirring tank together with the gas.

When it is confirmed that the urea aqueous solution of the required concentration has been generated through the concentration sensing device 260, the generated urea aqueous solution is supplied from the stirring tank 200 to the service tank under the stirring tank through a pipe connected to the service tank 500. . A third valve V3 that can be controlled by a control panel is provided in the pipe.

The urea aqueous solution generated in the stirring tank may have a concentration of around 40±1%, and when the necessary concentration of urea aqueous solution is confirmed, it is transferred to the service tank, and if the required concentration conditions are not met, additional urea powder or bill is added and stirred And repeat the process of measuring the concentration.

A reducing agent supply line (UL) for supplying the urea aqueous solution from the service tank to the onboard selective catalytic reduction device unit outside the equipment, and a return line (RL) for returning the urea aqueous solution to the service tank are provided. A supply pump (not shown) for pumping an aqueous urea solution may be provided in the reducing agent supply line.

The service tank is provided with a second liquid level sensor 520 for sensing the liquid level of the service tank and a second temperature sensor 510 for sensing the temperature of the service tank. According to the level of the service tank detected by the second level sensor 520, the control panel 400 determines whether or not the production of urea aqueous solution is necessary.

For example, when the urea aqueous solution is supplied and used outside the device and the level of the service tank drops to around 70%, the control panel can control the production of the urea aqueous solution to start. The necessary urea aqueous solution is continuously supplied from the service tank to the outside of the device without interruption even while the urea aqueous solution is generated in the stirring tank by the control of the control panel.When the urea aqueous solution of the required concentration is completed, about 40% of the urea aqueous solution remains. Inject the urea aqueous solution generated into the service tank.

In the control panel, it is possible to control the production of an aqueous urea solution in the device by the following steps.

1) determining the amount of urea powder to be supplied from the storage tank to the supply tank via the hopper;

2) transferring the urea powder to the supply tank by the amount determined in step 1) by injecting gas with the first ejector;

3) determining whether to generate urea aqueous solution according to the level of the service tank detected by the second level sensor;

4) determining the amount of urea powder and fresh water to be supplied to the stirring tank;

5) supplying the urea powder to the stirring tank from the lower portion of the supply tank by driving the spiral supply device by a motor;

6) confirming that the liquid level of the stirring tank is empty, and supplying fresh water to the stirring tank by the amount determined in step 4) through the fresh water supply line while detecting the liquid level by the first liquid level sensor; And

7) The concentration of the urea aqueous solution generated in the stirring tank by injecting nitrogen into the bottom of the stirring tank through the injection device and passing nitrogen through the second ejector to form a liquid flow flowing from the stirring tank to the stirring tank through the concentration sensing device. A urea aqueous solution can be prepared through the step of generating an aqueous urea solution by stirring the material inside the stirring tank while sensing.

The urea aqueous solution generated through each step is transferred to the service tank, and when it is sensed that the transfer of the aqueous solution has been completed by the weight sensor provided in the stirring tank, the third valve is closed.

Looking in more detail at the process in which the urea powder and fresh water of steps 4) to 7) are supplied to generate an aqueous urea solution in the stirring tank, it is sequentially performed according to the following process.

-Determining the amount of fresh water and urea powder to be supplied;

-Fresh water supply step: Operate the valve of the fresh water supply line (CL)

-Urea powder supply step: about 1 minute after the start of fresh water supply, urea supply, spiral supply in the supply tank are operated alternately on both sides;

-Heating step: When the heater is immersed in the water supplied into the stirring tank, heating starts by the heater. Working at 20 degrees, stopping at 35 degrees. When the amount of urea powder + water in the stirring tank exceeds 250kg, the On/Off function starts.

-Stirring step through Air Bubbling by injecting gas into the stirring tank with an injection device: Start immediately after the urea powder is added.

-Sensing the weight reduction of the supply tank;

-Detecting an increase in the weight of the stirred tank;

-Calculating the weight of the injected water by subtracting the weight reduction amount of the supply tank from the weight of the stirring tank;

-Calculating an expected concentration based on the calculated amount of water and the amount of urea powder added;

-Correcting the input of water and urea according to the calculated expected concentration;

-Stopping the input of water and urea when the mixing amount of the set urea aqueous solution is reached;

-Continuing Air Bubbling for an additional 5 minutes after stopping;

-Stopping Air Bubbling and heating;

-Forming a flow to the concentration sensor by spraying nitrogen or dry air to the ejector connected to the sensor line, and measuring the concentration;

-The step of determining whether the concentration reaches 40 ± 1% by measuring the concentration by the second ejector 270 and the concentration detecting device 260

-When the concentration condition is satisfied: The 3rd valve connected to the service tank is opened to transfer the created urea aqueous solution.

-If the concentration condition is not satisfied: Calculate the input amount of fresh water or urea powder -> Operate the heater and spray device -> Inject the calculated urea or fresh water -> Stop the heater and spray device after 5 minutes of filling -> The second ejector And repeating the concentration sensing step after forming a urea solution flow through the concentration sensing device.

The control panel receives the measured values detected by each sensor and sensing device, including the first and second level sensors, and the first and second temperature sensors, and controls the operation of each component in the device including each valve through this. Thus, the urea powder can be transferred to produce an aqueous urea solution of a required concentration and amount, and the stored urea aqueous solution can be supplied to the SCR.

Such a control panel is linked to the ship's Integrated Automation System (IAS), and can be controlled to automatically start the production of urea aqueous solution when the selective catalytic reduction device is operated.

As discussed above, the control panel controls the generation of urea aqueous solution in the stirring tank according to the level of the inside of the tank detected by the urea aqueous solution tank, and supplies the urea aqueous solution to the urea aqueous solution tank and supplies it to the SCR. Since the urea aqueous solution can be manufactured and supplied, there is no need to install a storage tank to store a large amount of the urea aqueous solution, thereby reducing the installation cost and installation space of tanks and piping, and the number of working hours. In addition, since the tank and piping in the device may be made of expensive materials or special painting may not be applied, manufacturing cost may be reduced.

When preparing a urea aqueous solution, by injecting gas, that is, nitrogen into the lower part of the stirring tank, to mix the urea powder and fresh water with the bubbles generated, and agitating the solution in the stirring tank while sensing the concentration of the urea aqueous solution in the stirring tank by an ejector. It is possible to shorten the manufacturing time by increasing the stirring efficiency.

In addition, by preparing an aqueous urea solution and supplying it to the SCR if necessary without storing it in the state of an aqueous urea solution for a long time, during long-term storage, the aqueous solution of urea can be prevented from stratified or dissociated according to the concentration gradient, resulting in deterioration of its performance as a reducing agent. . In particular, since a heating device and a cooling device for temperature control are not required for long-term storage in the state of an aqueous urea solution, installation space and installation cost of these devices can be reduced.

It is obvious to those of ordinary skill in the art that the present invention is not limited to the above embodiments, and can be implemented with various modifications or variations within the scope not departing from the technical gist of the present invention. I did it.

100: urea storage tank part
110: storage tank
120: manhole
130: hopper
140: first ejector
150: storage amount measuring device
200: stirring tank
210: injection device
220: heater
230: first temperature sensor
240: first liquid level sensor
250: ion removal filter
260: density detection device
270: second ejector
300: supply tank
310: residual quantity detector
320: spiral feeder
400: control panel
500: service tank
510: second temperature sensor
520: second level sensor
SL1: first gas supply line
SL2: 2nd gas supply line
SL3: 3rd gas supply line
SL4: 4th gas supply line
CL: fresh water supply line
UL: Reductant supply line
RL: return line

Claims (13)

A urea storage tank provided on the ship and storing urea powder;
A stirring tank receiving the urea powder and mixing it with fresh water to generate a urea aqueous solution to be supplied to the selective catalytic reduction device (SCR) provided in the ship;
A supply tank for receiving the urea powder from the urea storage tank and transferring the urea powder in a quantity to the stirring tank;
An injection device for generating bubbles for mixing the urea powder and fresh water by injecting gas under the stirring tank; And
A control panel for controlling the urea transfer from the urea storage tank and the supply tank and the generation of an aqueous urea solution in the stirring tank. The method of claim 1, wherein the urea storage tank part,
A storage tank for storing the urea powder;
A manhole provided above the storage tank to put the urea powder into the storage tank;
A hopper provided below the storage tank and supplying the urea powder to be transferred to the supply tank; And
Includes; a first ejector provided under the hopper,
Injecting gas to the first ejector, supplying the urea powder to the suction unit of the first ejector, and transferring the urea powder to the supply tank. The method of claim 2,
A residual amount detector for sensing the weight of the urea powder stored in the supply tank; And
A first vent line for preventing overpressure of the supply tank by discharging gas from the supply tank; further comprising,
A urea aqueous solution manufacturing apparatus for a ship, characterized in that the control panel controls the amount of the urea powder to be transferred from the urea storage tank to the supply tank according to the amount of the urea powder sensed by the residual amount detector. The method of claim 3,
The supply tank is formed in a funnel shape that becomes narrower toward the bottom, and at least one spiral feeder driven by a motor is provided inside the supply tank to transfer the urea powder to the bottom. Urea aqueous solution manufacturing device for SCR. The method of claim 4,
A fresh water supply line for supplying fresh water to the stirring tank;
A heater provided in the stirring tank to supply thermal energy for preventing overcooling when the urea aqueous solution is generated;
A first temperature sensor sensing the temperature of the stirring tank; And
Further comprising a; a first liquid level sensor for sensing the liquid level of the stirring tank,
In the control panel, the amount of fresh water to be supplied to the stirring tank is adjusted according to the level value sensed by the first level sensor, and the heater is controlled according to the temperature value sensed by the first temperature sensor. Urea aqueous solution manufacturing device for ship's SCR. The method of claim 5,
An ion removing filter provided in the fresh water supply line;
A first gas supply line connected to the injection device and transferring the gas to be supplied into the stirring tank;
A concentration sensing device for sensing the concentration of the aqueous urea solution generated in the stirred tank; And
Further comprising a; a second ejector connected to the first gas supply line,
The apparatus for producing a urea aqueous solution for SCR for ships, characterized in that the liquid passing through the concentration sensing device is supplied to the suction port of the second ejector and introduced into the stirring tank together with the gas supplied to the first gas supply line. The method of claim 6,
A service tank to which the urea aqueous solution generated in the stirring tank is transferred;
A reducing agent supply line for supplying the urea aqueous solution from the service tank to the selective catalytic reduction device unit;
A second level sensor for sensing the level of the service tank; And
A second temperature sensor for sensing the temperature of the service tank; urea aqueous solution manufacturing apparatus for a ship further comprising. The method of claim 7,
Further comprising; a second gas supply line for supplying the gas to the first ejector,
The gas supplied through the first and second gas supply lines is any one of nitrogen, control air, and service air. The method of claim 8,
A third gas supply line branched from the first and second gas supply lines and connected to the storage tank; And
A second vent line provided in the storage tank to relieve overpressure and negative pressure of the storage tank; further comprising,
For SCR of a ship, characterized in that by supplying the gas to the storage tank through the third gas supply line to prevent solidification of the urea powder, and to constantly transfer the urea powder from the storage tank to the hopper. Urea aqueous solution manufacturing device. The method of claim 7, wherein in the control panel,
1) determining an amount of the urea powder to be supplied from the storage tank to the supply tank;
2) transferring the urea powder to the supply tank by an amount determined in step 1) by injecting gas through the first ejector;
3) determining whether to generate the urea aqueous solution according to the level of the service tank detected by the second level sensor;
4) determining the amount of the urea powder and fresh water to be supplied to the stirring tank;
5) supplying the urea powder to the stirring tank by driving the spiral supply device;
6) Confirming that the level of the stirring tank is empty, and supplying fresh water to the stirring tank by the amount determined in step 4) through the fresh water supply line while detecting the level by the first level sensor. step; And
7) Nitrogen is injected into the bottom of the stirring tank through the injection device, and nitrogen is passed through the second ejector to form a liquid flow flowing from the stirring tank to the stirring tank through the concentration sensing device. Stirring the material inside the agitating tank while sensing the concentration of the aqueous urea solution generated in; Controlled to prepare the aqueous urea solution for SCR of a ship. In the method for producing an aqueous urea solution for supply to a selective catalytic reduction device (SCR) provided on a ship,
1) determining the amount of urea powder to be supplied to the supply tank from the storage tank in which the urea powder is stored;
2) transferring the urea powder to the supply tank by the amount determined in step 1);
3) determining whether or not the urea aqueous solution is generated by detecting the level of the service tank storing the generated urea aqueous solution;
4) determining the amount of fresh water and urea powder to be introduced into the stirring tank for generating the urea aqueous solution;
5) While transferring the urea powder from the supply tank to the stirring tank, confirming that the level of the stirring tank is empty, and detecting the level of the stirring tank, the stirring tank by the amount determined in step 4) Supplying fresh water to the furnace;
6) The urea powder and fresh water are mixed by air bubbles generated by injecting gas to the bottom of the stirring tank, and a part of the solution generated in the stirring tank is discharged to the outside of the tank to detect the concentration and then flow into the stirring tank. Includes;
The transport of the urea powder to the supply tank in step 2) and the inflow of the solution sensing the concentration in step 6) into the stirring tank are performed by injecting gas through an ejector. Urea aqueous solution preparation method. The method of claim 11,
In the step 5), the transfer of the urea powder from the supply tank to the stirring tank is performed by a spiral feeder provided in the lower inner side of the supply tank. . The method of claim 12,
A hopper through which the urea powder to be transferred to the supply tank is supplied is provided in the lower portion of the storage tank,
Injecting gas into the storage tank to prevent solidification of the urea powder, and to ensure that the urea powder is constantly transferred from the storage tank to the hopper.

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