JP3733815B2 - Exhaust purification system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In an internal combustion engine or the like, in order to reduce the amount of nitrogen oxide (NOx) in exhaust gas, a NOx reduction catalyst is provided in an exhaust gas exhaust passage, and a reducing agent is added to the NOx. The present invention relates to an exhaust gas purification system that purifies exhaust gas by utilizing catalytic action by reducing the amount of gas.
[0002]
[Prior art]
Uses catalytic action to purify nitrogen oxides (NOx) contained in exhaust gas from diesel engines and combustion equipment mounted on automobiles and ships such as large and small commercial vehicles and passenger cars Various exhaust purification systems that reduce nitrogen oxides have been put into practical use.
[0003]
In particular, three-way catalysts have been put into practical use in gasoline engines for automobiles and have been successful. However, in diesel engines, the three-way catalyst for gasoline cars cannot be used directly because the oxygen concentration in the exhaust gas is high. There is a problem.
[0004]
Therefore, in a diesel engine, adoption of the SCR method using a selective catalytic reduction catalyst (SCR catalyst) using a reducing agent such as urea water or ammonia (NH ₃ ) for purifying nitrogen oxides is being studied. This SCR method is a method in which a liquid reducing agent such as an aqueous urea solution, an aqueous ammonia solution, or liquid ammonia is injected into a high-temperature exhaust gas and brought into contact with a metal catalyst for denitration.
[0005]
As shown in FIG. 5, in the exhaust purification system 1A of the SRC method, an SCR catalyst 3 is provided in an exhaust passage 2 of an engine or the like, and an injection nozzle 8 is provided upstream of the SCR catalyst 3, and liquid is supplied from a tank 4. A reducing agent (reducing agent aqueous solution) L is supplied to the mixing unit 6 by a pump 5, and on the other hand, air A supplied from a compressed air supply device (air assist) 7 is supplied to the mixing unit 6, and an injection nozzle (injector) ) 8 and spray on the upstream side of the SCR catalyst 3. The reducing agent sprayed into the exhaust passage 2 from the injection hole 8 a of the injection nozzle 8 reduces and purifies nitrogen oxide in the exhaust gas G by the catalytic action of the SCR catalyst 3.
[0006]
Further, in this exhaust purification system 1A, the controller (control unit) 9 controls the on / off valve of the injection nozzle 8 while spraying the liquid reducing agent L while confirming the remaining of the liquid reducing agent L with the capacity meter switch 4a disposed in the tank 4. The amount is adjusted. When the remaining amount of the liquid reducing agent L decreases, this is detected by the capacity meter switch 4a, the warning lamp 10 is turned on, and replenishment of the liquid reducing agent L is promoted.
[0007]
The reduction action of this nitrogen oxide is carried out by the reaction of 4NO + 4NH ₃ + O ₂ = 4N ₂ + 6H ₂ O. As the SCR catalyst 3, alumina formed in pellets or honeycombs (aluminum oxide: Al ₂ O ₃ ) , Titania (titanium oxide: TiO ₂ ) or the like as a carrier, platinum (Pt), vanadium oxide (V ₂ O ₅ ), iron oxide (Fe ₂ O ₃ ), copper oxide (CuO), manganese oxide (Mn ₂ O ₃₎ ), Chromium oxide (Cr ₂ O ₃ ), molybdenum oxide (MoO ₃ ) and the like are known as active substances.
[0008]
[Problems to be solved by the invention]
However, in the conventional tank type exhaust purification system, it is necessary to spray the liquid reducing agent L in the form of a mist, so that the pump 6 for supplying the liquid reducing agent L to the injection nozzle 8 and the atomizing are performed. Since a pressurizing device such as the compressed air supply device 7 is required, there is a problem that the exhaust purification system 1A becomes complicated.
[0009]
Further, in the case of a liquid reducing agent in which a reducing agent is dissolved, such as an aqueous urea solution or an aqueous ammonia solution, since the concentration of the liquid reducing agent L changes because evaporation of the reducing agent occurs, it is difficult to manage the concentration. There is a problem that exhaust gas purification becomes insufficient.
[0010]
That is, even after filling, the concentration gradually decreases due to evaporation of the reducing agent, and even when the liquid reducing agent L at the beginning of filling is added, the concentration of the remaining aqueous solution L just before the addition in the tank 4 evaporates. Therefore, the concentration after mixing is not constant.
[0011]
Since the concentration of the reducing agent changes from time to time, an appropriate amount of the reducing agent cannot be supplied, and the purification efficiency of the SRC catalyst 3 is reduced to sufficiently reduce and purify the exhaust gas G. Or the excess reducing agent is exhausted while being mixed in the exhaust gas.
[0012]
The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a simple means for supplying a liquid reducing agent in an exhaust gas purification system such as an internal combustion engine using a catalyst, and the remaining liquid reducing agent. It is an object of the present invention to provide an exhaust purification system that can easily grasp the amount and can stably supply the concentration of the liquid reducing agent while keeping it substantially constant.
[0013]
A further object is to accurately grasp the remaining amount of the liquid reducing agent, and when the remaining amount is low, an exhaust purification system capable of generating a warning prompting the driver to supply the liquid reducing agent in a timely manner. Is to provide.
[0014]
[Means for Solving the Problems]
An exhaust gas purification system for achieving the above object is configured as follows.
[0015]
An injection nozzle and an exhaust gas purification catalyst are arranged in order from the upstream side in an exhaust passage of an internal combustion engine or the like, and a liquid reducing agent is sprayed from the injection nozzle and supplied to the catalyst, and nitrogen oxides in the exhaust gas In the exhaust purification system for reducing and purifying the gas, the replacement is provided with an exchange detection means that encloses the liquid reducing agent together with the pressurized gas and can inject the liquid reducing agent from the injection nozzle by the pressure of the pressurized gas. A possible cartridge is configured to be detachably connected to the liquid reducing agent supply line communicating with the injection nozzle.
[0016]
As this catalyst, there is an SCR catalyst or the like. In this SCR catalyst, the support is formed of Al ₂ O ₃ , TiO ₂ or the like, and the catalyst metal as the active substance is Pt, V ₂ O ₅ , Fe ₂ O ₃ , CuO, It can be formed of Mn ₂ O ₃ , Cr ₂ O ₃ , MoO ₃ or the like.
[0017]
Examples of the liquid reducing agent include urea aqueous solution, aqueous ammonia solution, and liquid ammonia. As the pressurized gas, liquid such as compressed air and other gases such as paint spray cans and lubricant spray cans are added. A well-known gas can be used. The cartridge is a detachable container formed to withstand the pressure of the pressurized gas, and the liquid reducing agent is newly supplied by exchanging the container.
[0018]
In the exhaust gas purification system for an internal combustion engine with this configuration, since the pressure for spraying the liquid reducing agent can be obtained by the pressurized gas in the cartridge, there is no need to provide a pressurizing mechanism such as a compressed air supply device. The purification system is simplified.
[0019]
In addition, since the liquid reducing agent is sealed in the cartridge, the evaporation of the reducing agent is suppressed even when the reducing agent is dissolved in the solution. The agent can be supplied to the injection nozzle. Therefore, the optimum amount can be accurately supplied to the catalyst, and the purification efficiency is improved.
[0020]
2) In the exhaust gas purification system for the internal combustion engine, a remaining amount detecting means for detecting the remaining amount of the liquid reducing agent in the cartridge, and a warning when the remaining amount falls below a predetermined lower limit amount It is formed with warning generating means.
[0021]
By providing the remaining amount detecting means and the warning generating means, the driver who has received the warning replaces the cartridge at an appropriate time, so that the liquid reducing agent can be easily managed and the supply of the liquid reducing agent can be prevented from being interrupted. .
[0022]
Further, the comparison between the remaining amount and the predetermined lower limit amount may be made directly by the weight of the liquid reducing agent, but the amount that can be converted from this weight, for example, the value of the capacity or the detection signal (voltage value, etc.) Or a value converted into a travel distance that can be traveled while consuming the liquid reducing agent, etc., and the present invention includes these values.
[0023]
3) In the exhaust gas purification system for an internal combustion engine, the remaining amount detection means integrates a control signal for controlling the operation of the injection nozzle, and calculates the consumption amount of the liquid reducing agent from the integrated value. Thus, it is constituted by a calculation means for calculating the remaining amount.
[0024]
According to this configuration, since the amount of consumption of the liquid reducing agent is calculated from the control signal for the injection nozzle, there is no need to provide a new sensor, and this calculation means adds a program to a controller such as an internal combustion engine. Therefore, it can be implemented relatively easily.
[0025]
4) Alternatively, in the exhaust gas purification system for an internal combustion engine, the remaining amount detecting means includes a weight sensor for detecting the weight of the cartridge, and a calculating means for calculating the remaining amount of the liquid reducing agent from a signal of the weight sensor. Consists of.
[0026]
According to this configuration, since the amount of the liquid reducing agent can be directly measured by the weight sensor, finer management with less error is possible.
[0027]
5) Then, further, when the replacement of the cartridge is detected by the exchange detection unit, configured to actuate the injection nozzle during a predetermined time period.
[0028]
This exchange detection means can be formed by a switch or the like that is turned ON / OFF according to the presence or absence of a cartridge, and a predetermined time for operating the injection nozzle is a liquid reducing agent supply line (between the cartridge and the injection hole) that accompanies cartridge replacement. This is a predetermined time that can be removed from the air and input to the controller in advance.
[0029]
With this configuration, since the replacement of the cartridge can be detected, the initial value that is the estimation criterion of the remaining amount can be accurately reset. In other words, the cartridge filling amount and concentration are accurately controlled by the cartridge manufacturer so as to become a predetermined value in the quality control of the factory before shipping, and this predetermined filling amount is used as an initial value of reset when the cartridge is replaced. By using it, the remaining amount can be estimated more accurately.
[0030]
In addition, since air is automatically vented when the cartridge is replaced, it is possible to prevent the air biting of the supply line of the liquid reducing agent and to always supply an appropriate amount of the liquid reducing agent in accordance with instructions from the controller.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of an exhaust purification system according to the present invention will be described with reference to the drawings.
[0032]
As shown in FIG. 1, an exhaust purification system 1 according to the present invention is provided with an SCR (selective contact reduction) catalyst 3 in an exhaust passage 2 of an engine or the like, and further, a liquid reducing agent is disposed upstream of the SCR catalyst 3. An injection nozzle (injector) 8 that can spray one urea aqueous solution L is provided.
[0033]
In this SCR catalyst 3, the support is formed of Al ₂ O ₃ , TiO ₂ or the like, and the catalyst metal as an active substance is Pt, V ₂ O ₅ , Fe ₂ O ₃ , CuO, Mn ₂ O ₃ , Cr ₂ O _3. , MoO ₃ or the like.
[0034]
The cartridge 21 is provided with a replaceable cartridge 21 in which the urea aqueous solution L and the pressurized gas P are enclosed and stored. The cartridge 21 is detachably connected to the injection nozzle 8 through a supply line 22 so that the inside of the cartridge 21 can be added. The urea aqueous solution L is supplied to the injection nozzle 8 by the pressure of the pressurized gas P, and is sprayed into the exhaust passage 2 from the injection hole 8a under the control of the controller (control unit) 9.
[0035]
The principle of this spraying is the same as that of commonly used paint spray cans and lubricant spray cans, and the cartridge 21 such as a cylinder is filled with liquid L and compressed gas (gas or air) P. Then, the liquid L is pressurized with the gas P, and when the outlet is opened, the liquid L is pushed out and sprayed from the outlet.
[0036]
This spraying is performed by controlling the opening and closing of the injection nozzle 8 by duty control so that the controller 9 has a target spray amount calculated by referring to various information of the engine.
[0037]
According to this configuration, since the pressure for spraying the liquid reducing agent L can be obtained by the pressurized gas P in the cartridge 21, it is not necessary to provide a pressure mechanism such as a compressed air supply device (air assist). The exhaust purification system 1 can be simplified.
[0038]
Further, since the liquid reducing agent L is sealed in the cartridge 21, there is no change in the concentration of the liquid reducing agent L due to evaporation or the like, and an appropriate amount of the reducing agent can be supplied to the catalyst 3 at a stable concentration, thereby improving the purification efficiency. Can keep.
[0039]
[Estimation of remaining amount]
Further, in order to estimate the remaining amount Ws of the urea aqueous solution L in the cartridge 21 and to warn the driver or the like as necessary, the cartridge 21 is replaced with a remaining amount detecting means constituted by a calculating means, a weight sensor 23, etc. An exchange detection means is provided for performing the calculation and control according to the flows shown in FIGS.
[0040]
By providing the remaining amount detecting means and the warning generating means (warning lamp) 10, it is possible to grasp the accurate remaining amount Ws and warn the driver to display or replace the remaining amount Ws. Therefore, since the cartridge 21 can be replaced at an appropriate time and the liquid reducing agent L can be supplied, interruption of the liquid reducing agent L can be prevented.
[0041]
Furthermore, since the replacement detection means for detecting the replacement of the cartridge 21 is provided, the initial value of the remaining amount Ws can be reset to a predetermined value, so that the remaining amount Ws can be estimated accurately. Also, when the replacement of the cartridge 21 is detected, the supply nozzle 22 can be automatically vented by operating the injection nozzle 8 for a predetermined time, so that the air nozzle is prevented and the injection nozzle is prevented. 8 accurate operation can be maintained.
[0042]
[Estimation of remaining amount (part 1)]
First, the case where the replacement detection means 24 for detecting the replacement of the cartridge 21 is provided will be described.
[0043]
The replacement detection means 24 can be formed by a simple ON / OFF switch 24 that is turned off when an empty cartridge 21 is removed and turned on when a new cartridge 21 is mounted. In this case, when the output from the switch 24 to the controller 9 changes from the OFF signal to the ON signal, it is determined that the replacement has been performed, and the initial value of the remaining liquid amount Ws is reset to a predetermined amount at the time of shipment from the factory. Note that ON and OFF may be set in reverse.
[0044]
Further, in this configuration, the remaining amount detection means integrates the control signal of the controller 9 that controls the operation of the injection nozzle 8, and calculates the remaining amount Ws of the liquid reducing agent L from this integrated value, thereby calculating the remaining amount Ws. Is configured to calculate.
[0045]
Therefore, it is possible to provide the remaining amount detection means simply by adding a simple ON / OFF switch 24 and a new remaining amount calculation program, so that it is not necessary to provide a new expensive sensor.
[0046]
In this case, calculation and control are performed according to the flow of FIG. The portion of the flow in FIG. 2 is repeatedly called from the main control program every predetermined period. When this flow starts, first, the remaining amount Ws of the urea aqueous solution L in the cartridge 21 is calculated in step S11.
[0047]
The remaining amount Ws is calculated by subtracting the consumed weight Wc from the remaining amount (weight) Ws of the urea aqueous solution L before the flow is called. The consumed weight Wc is obtained by integrating the duty ratio of a duty signal for controlling the opening and closing of the injection nozzle 8, converting the integrated value into a spray amount, and multiplying the converted value by the specific gravity of the urea aqueous solution L. .
[0048]
In step S12, it is determined whether or not the cartridge 21 has been replaced by the output of the replacement detection means 24. If it is determined that the cartridge 21 has been replaced (YES), the remaining amount Ws is determined in step S13. In step S14, a signal for operating the injection nozzle 8 is output for a predetermined time, for example, for a few seconds, and the supply line 22 is bleed, and then the process proceeds to step S15. If the cartridge 21 has not been replaced (NO), the process goes directly to step S15.
[0049]
The air supply line 22 is vented to prevent air from entering the supply pipe line 22 when the cartridge 21 is replaced, so that the injection nozzle 8 cannot be accurately injected due to the air. Yes, an air vent valve (not shown) may be provided, and the air vent valve may be opened for a predetermined time.
[0050]
Then, a calculation is performed to determine whether or not to issue a warning prompting replacement of the cartridge. In this calculation, first, in step S15, the distance Dp that can be traveled without replacement is estimated from the current remaining amount Ws, and in step S16, the warning distance in which the travelable distance Dp is a predetermined threshold value. It is determined whether or not it becomes smaller than Dw.
[0051]
The travelable distance Dp is, for example, data obtained by previously inputting the consumption amount Wa of the aqueous urea solution L per unit time when traveling at a constant reference speed (flat ground) of 60 km / h, or during actual traveling It can be calculated by estimating from the accumulated data and dividing the remaining amount Ws by this consumed amount Wa, that is, by setting Dp = Ws / Wa. Further, as the warning distance Dw, a standard distance that requires traveling before replacement, for example, 50 km is adopted.
[0052]
If the travelable distance Dp is not less than or equal to the warning distance Dw (NO), the process returns to the main control, and if it is the following (YES), the warning lamp 10 is turned on in step S17. Lights up and informs the driver that the urea aqueous solution L in the cartridge 21 is low and prompts replacement. Then, return and return to the main control. It should be noted that a warning may be given by voice instead of the warning lamp 10, or the voice and the warning lamp 10 may be used in combination.
[0053]
Further, the amount of the urea aqueous solution L estimated to be consumed when traveling the warning distance Dw is calculated in advance as a predetermined lower limit amount Wp, and the remaining amount Ws and the predetermined amount are directly used instead of steps S15 and S16. It is also possible to compare the lower limit value Wp and to go to step S17 and generate a warning when the remaining amount Ws becomes equal to or less than the predetermined lower limit amount Wp.
[0054]
[Estimation of remaining amount (part 2)]
Next, the replacement detection means 21 is not provided, but a weight sensor 23 for measuring the weight of the cartridge 21 is provided. The weight of the cartridge 21 is measured, and the result is output to the controller 9. The case where it comprises is demonstrated.
[0055]
When this weight sensor 23 is used, when a sufficient amount of urea aqueous solution L remains, when it is once removed and then returned, or when a used cartridge 21 having a residual amount different from the new amount is attached. The erroneous estimation of the remaining amount that occurs can be avoided. Further, since the amount of the liquid reducing agent L can be directly measured, finer management can be performed with less error.
[0056]
In this case, calculation and control are performed according to the flow of FIG. 3 is repeatedly called at predetermined intervals from the main control program and starts. First, in step S21, the total weight Cw of the cartridge 21 is detected and the weight of the cartridge 21 (pressurized gas) is detected. The remaining amount Ws is calculated. In step S22, it is determined whether or not the weight Cw is the same as that at the time of shipment from the factory, that is, whether or not the weight Cw is equal to or greater than a predetermined weight Co. If it is exchanged, a signal for operating the ejection nozzle 8 is output for a predetermined time, and then the process goes to Step S24. If the following (NO), the process goes to Step S24 as it is because the cartridge 21 is not exchanged.
[0057]
Then, in step S24 to step S26, a calculation for determining whether or not to issue a warning for prompting the replacement of the cartridge is performed, but this calculation is the same as the above-described step S15 to step S17, and thus description thereof is omitted. .
[0058]
[Estimation of remaining amount (part 3)]
Further, a case will be described in which the replacement detection means 24 and the weight sensor 23 for measuring the weight of the cartridge 21 are provided together so that the presence or absence of replacement of the cartridge 21 can be detected.
[0059]
The merit in this case is that when only the weight sensor 23 according to the flow of FIG. 3 is installed, the weight of the new cartridge 21 is reduced so as not to repeat the operation of the ejection nozzle 8 for bleeding for a predetermined time. However, when the replacement detection means 24 is added, the air release jet is based on this replacement detection means 24. Therefore, the weight sensor 23 only needs to know the remaining amount Ws with a certain degree of accuracy, and an inexpensive weight sensor 23 is required, and an expensive weight sensor 23 is unnecessary.
[0060]
Further, since the cartridge manufacturer fills the cartridge 21 with a precise value so that the cartridge manufacturer has a predetermined value in the quality control of the factory, the initial value of the remaining amount is set when the cartridge 21 is replaced. By resetting to a value, the remaining amount can be estimated more accurately.
[0061]
In this case, calculation and control are performed according to the flow of FIG. This flow part of FIG. 4 is repeatedly called from the main control program every predetermined period and starts. First, in step S31, it is determined whether or not the cartridge 21 has been replaced, and it is determined that the replacement has been performed. In the case (YES), in step S32, a signal for operating the injection nozzle 8 is output for a predetermined time, and then the process goes to step S33. If the cartridge 21 has not been replaced (NO), the step is continued. Go to S33.
[0062]
In this step S33, the total weight Cw of the cartridge 21 is detected by the weight sensor 23, and the remaining amount Ws is calculated by subtracting the weight of the cartridge 21 (including the weight of the pressurized gas).
[0063]
Then, in step S34 to step S36, a calculation for determining whether or not to warn the replacement of the cartridge 21 is performed. This calculation is the same as the above-described step S15 to step S17. Omit.
[0064]
In the above description, the exhaust gas purification of an engine such as an automobile is taken as an example, and the urea aqueous solution is taken as an example as a liquid reducing agent. However, other exhaust gases other than these internal combustion engines such as a combustion furnace are used. The present invention can also be used for purification of liquids, and liquid reducing agents can also be used in aqueous solutions in which reducing agents such as urea aqueous solutions and aqueous ammonia solutions are dissolved, and in which reducing agents such as liquid ammonia themselves are in liquid form. Therefore, the present invention is not limited to the above-described embodiment.
[0065]
【The invention's effect】
As described above, according to the exhaust purification system of the present invention, the following effects can be achieved.
[0066]
Since the pressurized gas is sealed together with the liquid reducing agent in the cartridge and the pressure source for spraying the liquid reducing agent in the cartridge is provided, there is no need to provide a pressurized mechanism such as a compressed air supply device, and exhaust purification. The system can be simplified and the exhaust purification system can be reduced in size and weight.
[0067]
Also, since the liquid reducing agent is sealed in the cartridge, there is no change in the concentration of the liquid reducing agent due to evaporation of the reducing agent, etc., and an appropriate amount of reducing agent can be supplied to the catalyst at a stable concentration, thus maintaining good purification efficiency. be able to.
[0068]
Furthermore, by providing the remaining amount detecting means and the warning generating means, it is possible to grasp the accurate remaining amount and issue a warning prompting the driver to display or replace the remaining amount. As a result, the liquid reductant can be reliably managed and the cartridge can be replaced at an appropriate time to supply the liquid reductant, so that exhaust gas purification failure due to interruption of the liquid reductant can be avoided.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an exhaust purification system according to the present invention.
FIG. 2 is a diagram showing a control flow of an exhaust purification system according to the present invention using replacement detection means for a cartridge.
FIG. 3 is a diagram showing a control flow of an exhaust purification system according to the present invention using weight detection means for a cartridge.
FIG. 4 is a diagram showing a control flow of an exhaust purification system according to the present invention using replacement detection means and weight detection means for a cartridge.
FIG. 5 is a configuration diagram showing a conventional exhaust purification system.
[Explanation of symbols]
1 Exhaust purification system 2 Exhaust passage 3 SCR catalyst (catalyst)
8 Injection nozzle 8a Injection hole 9 Controller (residual amount detection means)
10 Warning lamp (Warning generation means)
21 cartridge
22 Supply pipeline
23 Weight sensor (remaining amount detection means)
24 ON / OFF switch (exchange detection means)
G Exhaust gas L Urea aqueous solution (liquid reducing agent)
P Pressurized gas Ws Remaining amount Wc Consumption amount Wp Predetermined lower limit amount

Claims (4)

An injection nozzle and an exhaust gas purification catalyst are arranged in order from the upstream side in an exhaust passage of an internal combustion engine or the like, and a liquid reducing agent is sprayed from the injection nozzle and supplied to the catalyst, and nitrogen oxides in the exhaust gas In the exhaust gas purification system for reducing and purifying the above, an exchangeable cartridge that encloses the liquid reducing agent together with a pressurized gas and can inject the liquid reducing agent from the injection nozzle by the pressure of the pressurized gas. An exhaust purification system comprising an exchange detection means for detachably connecting to the liquid reducing agent supply line communicating with an injection nozzle and detecting exchange of the cartridge . Remaining amount detection configured by calculating means for calculating the residual amount of the liquid reducing agent by integrating the control signal for controlling the operation of the injection nozzle and calculating the consumption amount of the liquid reducing agent from the integrated value. exhaust gas purification system according to claim 1, characterized in that it has means, and a warning generating means for the residual amount to generate a warning when it becomes less than a predetermined lower limit value. A remaining amount detecting means comprising a weight sensor for detecting the weight of the cartridge, a calculating means for calculating the remaining amount of the liquid reducing agent from the signal of the weight sensor, and the remaining amount is equal to or less than a predetermined lower limit value. exhaust gas purification system according to claim 1; and a warning generating means for generating a warning when the. The exhaust purification system according to any one of claims 1 to 3 , wherein when the replacement of the cartridge is detected by the replacement detection means, the injection nozzle is operated for a predetermined time.

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