A method for reducing reverse osmosis pressure based on electrochemistry

Abstract

The present invention provides a method for reducing reverse osmosis pressure based on electrochemistry. The present invention relates to the field of liquid osmosis technology. A container is used. A first chamber for accommodating a low-concentration solution and a second chamber for accommodating a high-concentration solution are formed inside the container. A reverse osmosis membrane is provided between the first chamber and the second chamber. The inner wall of the second chamber is also provided with a supporting base. The supporting base is sealed and slidably connected to the inner wall of the second chamber. The side wall of the supporting base is provided with a through supporting opening. The inner wall of the supporting opening is rotatably connected to an electrolysis device. The invention can interchange the positions of the two electrolysis areas, achieve relative continuity of electrolysis and reverse osmosis, and improve the efficiency of electrolysis and reverse osmosis. The present invention can connect an electrochemical device in series with a reverse osmosis device, reduce the concentration of ions in the liquid through the electrochemical device, greatly reduce the pressure of reverse osmosis, reduce resource consumption, and improve economic benefits.

Description

Technical Field

[0001] The present invention relates to the field of liquid permeation technology, in particular to a method for reducing reverse osmosis pressure based on electrochemistry. Background Art

[0002] Reverse osmosis technology can separate water and pollutants in sewage, thereby purifying the sewage. Reverse osmosis technology uses reverse osmosis membranes and pressurization technology to increase the pressure on the high-concentration solution side and then pressurize the water into the low-concentration solution side.

[0003] During the osmosis process, the concentration difference of the solution increases further. At this time, it is necessary to continue to increase the pressure on the side of the high-concentration solution in order to press the liquid into the side of the low-concentration solution, which increases the power of the equipment and the pressure resistance requirements of the equipment.

[0004] The ions in a high-concentration solution can be converted into solid matter by electrochemical methods. In this way, the concentration of the high-concentration solution can be reduced, thereby reducing the pressure required for the high-concentration solution. However, during the ion electrolysis process, the solid matter formed on the outside gradually thickens, affecting the time and effect of a continuous electrolysis. The entire electrolysis structure needs to be dismantled regularly for cleaning or replacement before subsequent operations can be carried out, which reduces the efficiency of electrolysis and reverse osmosis. Summary of the Invention

[0005] In response to the above problems, the present invention provides a method for reducing reverse osmosis pressure based on electrochemistry. The invention can swap the positions of two electrolysis areas, achieve relative continuity of electrolysis and reverse osmosis, and improve the efficiency of electrolysis and reverse osmosis.

[0006] In order to solve the above problems, the technical solution adopted by the present invention is:

[0007] A method for reducing reverse osmosis pressure based on electrochemistry uses a containing device, wherein a first chamber for containing a low-concentration solution and a second chamber for containing a high-concentration solution are formed inside the containing device, a reverse osmosis membrane is provided between the first chamber and the second chamber, and a supporting base is further provided on the inner wall of the second chamber, the supporting base is sealingly and slidingly connected to the inner wall of the second chamber, a through-carrying opening is provided on the side wall of the supporting base, and an electrolysis device is rotatably connected to the inner wall of the supporting opening, and the electrolysis device has at least two electrolysis areas; the method comprises the following steps: S1, placing the low-concentration solution in the first chamber, Place a high-concentration solution in the second chamber, and control the second chamber to be in a relatively closed state; S2, continuously increase the pressure in the second chamber, control the liquid to pass through the reverse osmosis membrane and enter the first chamber; at the same time, control the electrolysis device to be in a conductive state, control the metal ions in the second chamber to continuously electrolyze on the surface of the first electrolysis area of ​​the electrolysis device to reduce the concentration of the high-concentration solution; S3, when the surface solid material of the first electrolysis area has a predetermined thickness, rotate the electrolysis device to deflect by a predetermined angle, deflect the first electrolysis area to the outside for cleaning, and deflect the second electrolysis area to the inside to complete continuous electrolysis.

[0008] Preferably, the electrolysis device includes a rotating body, the electrolysis areas are arranged on the outer surface of the rotating body and spaced circumferentially, the side wall of the rotating body is provided with at least two first sealing grooves, and a matching first sealing device is provided outside the first sealing groove.

[0009] Preferably, the first sealing device includes a first sealing base, the inner wall of the first sealing base is provided with at least two first driving chambers, and the inner wall of the first driving chamber is sealingly and slidingly connected with a first sealing end adapted to the first sealing groove.

[0010] Preferably, the first chamber and the second chamber are placed horizontally, and a second sealing device located inside the supporting base is further provided inside the second chamber, and a predetermined distance is provided between the first sealing device and the second sealing device to form an adjustment area.

[0011] Preferably, the second sealing device includes a second sealing base and a third sealing base, the inner wall of the second sealing base is sealingly and slidingly connected with a second sealing end, and the side wall of the third sealing base is provided with a second sealing groove adapted to the second sealing end.

[0012] Preferably, the adjustment area is connected to a first pumping pipe for conveying a buffer solution. In step S3, after the second electrolytic area is deflected inward, a predetermined amount of buffer solution is pumped through the first pumping pipe to mix with the high-concentration solution. After mixing, a complex is formed to further reduce the concentration of the high-concentration solution.

[0013] Preferably, the predetermined amount of the buffer solution pumped is calculated based on the amount of solid matter on the surface of the first electrodeposition area.

[0014] Preferably, a discharge device is provided at the inner bottom of the second chamber, and a second pumping pipe for pumping the cleaning liquid is provided on the outer side of the discharge device.

[0015] The beneficial effects of the present invention are:

[0016] Compared with the prior art, the above method can exchange the positions of the two electrolysis areas without dismantling the electrolysis device, thereby achieving relative continuity of electrolysis and reverse osmosis and improving the efficiency of electrolysis and reverse osmosis. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the present invention.

[0018] Figure 2 For the present invention Figure 1 AA cross-sectional structural diagram.

[0019] Figure 3 For the present invention Figure 2 Schematic diagram of the enlarged structure at point B.

[0020] Figure 4 Schematic diagram of the series connection of electrochemical device and reverse osmosis equipment.

[0021] In the figure: 100, accommodating device; 110, first chamber; 111, third pumping pipe; 120, second chamber; 121, second pumping pipe; 200, discharging device; 300, supporting base; 310, supporting opening; 400, electrolysis device; 410, rotating body; 420, electrolysis area; 430, first sealing groove; 500, first sealing device; 510, first sealing base; 520, first driving chamber; 530, first sealing end; 600, second sealing device; 610, second sealing base; 611, second sealing end; 620, third sealing base; 700, adjustment area. DETAILED DESCRIPTION

[0022] The present invention will be further described below with reference to the accompanying drawings and examples.

[0023] In order to solve the problem of background technology, refer to the attached Figure 1 -Attached Figure 3A method for reducing reverse osmosis pressure based on electrochemistry uses a containing device 100. A first chamber 110 for containing a low-concentration solution and a second chamber 120 for containing a high-concentration solution are formed inside the containing device 100. A reverse osmosis membrane is arranged between the first chamber 110 and the second chamber 120. During the reverse osmosis process, it is necessary to increase the pressure in the second chamber 120. Under the action of pressure, water molecules in the high-concentration solution in the second chamber 120 can pass through the reverse osmosis membrane and enter the side of the first chamber 110, thereby realizing the reverse osmosis process.

[0024] Specifically, a supporting base 300 is further provided on the inner wall of the second chamber 120, and the supporting base 300 is sealed and slidably connected to the inner wall of the second chamber 120. A penetrating supporting opening 310 is opened on the side wall of the supporting base 300, and an electrolytic deposition device 400 is rotatably connected to the inner wall of the supporting opening 310. The electrolytic deposition device 400 has at least two electrolytic deposition areas 420. Electrolytic deposition metal is installed on the surface of the electrolytic deposition area 420, and the type of electrolytic deposition metal is determined according to the composition of the high-concentration solution. During operation, the sliding supporting base 300 moves inward to compress the space in the second chamber 120 to increase the internal pressure.

[0025] The specific steps include:

[0026] S1. Place a low-concentration solution in the first chamber 110 and a high-concentration solution in the second chamber 120, and control the second chamber 120 to be in a relatively closed state to avoid liquid leakage during the subsequent pressurization process.

[0027] S2. Continue to increase the pressure in the second chamber 120, control the liquid to pass through the reverse osmosis membrane and enter the first chamber 110; at the same time, control the electrolysis device 400 to be in a conductive state, control the metal ions in the second chamber 120 to continuously electrolyze on the surface of the first electrolysis area 420 of the electrolysis device 400 to reduce the concentration of the high-concentration solution; in this process, the metal ions in the high-concentration solution can be continuously electrolyzed and precipitated on the surface of the electrolysis area 420 to form a solid metal element; in this process, the content of metal ions in the high-concentration solution is reduced, the concentration of the high-concentration solution is reduced, the concentration difference is narrowed, and ultimately the pressure that needs to be applied to the second chamber 120 during the reverse osmosis process is reduced.

[0028] S3. After the solid material on the surface of the first electrolytic deposition area 420 has been deposited to a predetermined thickness, the electrolytic deposition device 400 is rotated to a predetermined angle, the first electrolytic deposition area 420 is deflected to the outside for cleaning, and the second electrolytic deposition area 420 is deflected to the inside to complete continuous electrolytic deposition.

[0029] In the above manner, without dismantling the electrolysis device 400, the positions of the two electrolysis areas 420 can be swapped, thereby achieving relative continuity of electrolysis and reverse osmosis, and improving the efficiency of electrolysis and reverse osmosis.

[0030] The cross section of the electrolytic deposition device 400 can be a circular or elliptical main body.

[0031] When the cross-section of the electrolysis device 400 is selected as an elliptical cylinder, only two electrolysis areas 420 can be set here, and the two electrolysis areas 420 are set on the longer side of the arc of the elliptical main body; during the rotation of the elliptical cylinder, the longer two ends of the elliptical cylinder can be staggered with the load-bearing opening 310, and the lateral dimension of the longer arc side is smaller, and the deflection can be completed without contacting the load-bearing opening 310; after the deflection is completed, the longer side of the ellipse can be tightly pressed against the inner wall of the load-bearing opening 310, ensuring the sealing during the electrolysis and reverse osmosis process, and avoiding liquid leakage.

[0032] When the cross-section of the electrolysis device 400 is selected to be a circular cylinder, the electrolysis device 400 here includes a rotating body 410, the cross-section of the rotating body 410 is circular, and the electrolysis areas 420 are arranged on the outer surface of the rotating body 410 and are circumferentially spaced. At this time, the electrolysis areas 420 here can be designed as multiple circumferentially arranged areas according to the size of the rotating body 410 and the needs, and there is a predetermined spacing between the multiple electrolysis areas 420; in order to ensure the overall sealing and the ability to be dislocated during rotation, the size of the load-bearing opening 310 here is larger than the diameter of the rotating body 410, and at least two first sealing grooves 430 are opened on the side wall of the rotating body 410, and a corresponding first sealing device 500 is provided on the outside of the first sealing groove 430.

[0033] The first sealing device 500 here is a telescopic sealing device. Before the deflection switching, the first sealing device 500 is first controlled to shrink and stagger with the rotating body 410. After the deflection switching, the first sealing device 500 is controlled to extend and engage with the first sealing groove 430 to achieve a sealing effect and prevent liquid leakage. Controlling the first sealing device 500 to shrink first can make way for solid matter on the surface of the electrolysis area 420 to prevent friction and falling during rotation.

[0034] Specifically, the first sealing device 500 includes a first sealing base 510, and the inner wall of the first sealing base 510 is provided with at least two first driving chambers 520. The inner wall of the first driving chamber 520 is sealed and slidably connected with a first sealing end 530 adapted to the first sealing groove 430. The first driving chamber 520 here is connected to a hydraulic device, and the control oil is pumped into the first driving chamber 520 through the hydraulic device to push the first sealing end 530 to move toward the outside. The shape of the first driving chamber 520 is adapted to the internal size of the first sealing groove 430. The first driving chamber 520 extends into the first sealing groove 430 to form a sealing area with a U-shaped cross-section, thereby enhancing the overall sealing effect.

[0035] Furthermore, in order to facilitate the cleaning of the surface of the electrolysis area 420 after the electrolysis device 400 is deflected to the outside, the first chamber 110 and the second chamber 120 are placed horizontally, and a second sealing device 600 located on the inner side of the supporting base 300 is also provided inside the second chamber 120. There is a predetermined distance between the first sealing device 500 and the second sealing device 600 to form an adjustment area 700.

[0036] The first sealing device 500 and the second sealing device 600 here work alternately, which can control the interior of the second chamber 120 to be continuously in a sealed state, thereby preventing the liquid in the second chamber 120 from leaking out in a horizontal state; before the electrolysis device 400 is deflected, the second sealing device 600 is first controlled to seal, and then the first sealing device 500 is controlled to contract, and then the electrolysis device 400 is controlled to deflect a predetermined angle; after the deflection of the electrolysis device 400 is completed, the first sealing device 500 is first controlled to extend to achieve sealing, and then the second sealing device 600 is controlled to contract, so that the deflected electrolysis device 400 can contact with the high-concentration solution in the second chamber 120, thereby realizing a continuous electrolysis process.

[0037] It should be noted here that before the electrolysis device 400 is deflected, some high-concentration solution remains in the adjustment area 700, and this part of the high-concentration solution will be discharged under the action of gravity after the first sealing device 500 is opened; a containing device is provided on the outside of the electrolysis device 400 for centralized collection; at the same time, some of the outflowing high-concentration solution can clean the deflection path of the electrolysis device 400 to ensure the normal deflection of the electrolysis device 400.

[0038] Please refer to the attached Figure 3The second sealing device 600 here includes a second sealing base 610 and a third sealing base 620. The inner wall of the second sealing base 610 is sealed and slidably connected to the second sealing end 611, and the side wall of the third sealing base 620 is provided with a second sealing groove adapted to the second sealing end 611. Similarly, the second sealing end 611 here is controlled to retract under the action of oil. In the process of controlling the extension of the second sealing end 611, the second sealing end 611 can be pushed into the corresponding second sealing groove to form a sealing barrier, thereby avoiding liquid leakage in the second chamber 120; the above-mentioned sealing structure does not affect the movement and pressurization of the supporting base 300, and can also ensure an overall excellent sealing effect.

[0039] Furthermore, the adjustment area 700 is connected to a first pumping pipe for conveying a buffer solution. After the second electrolytic region 420 is deflected inward in step S3, a predetermined amount of buffer solution is pumped through the first pumping pipe to mix with the high concentration solution. After mixing, a complex is formed to further reduce the concentration of the high concentration solution.

[0040] The above-mentioned buffer solution is selected according to the composition of the sewage, and common persulfate, metal ions that can form complexes or some organic ligands can be selected; through the above-mentioned placement, the buffer solution can be mixed with some excess ions in the sewage, which can adjust the pH stability while further reducing the concentration of the high-concentration solution and reducing the pressure of reverse osmosis.

[0041] Before mixing, the high-concentration solution in the second chamber 120 and the buffer solution in the adjustment area 700 are in a state of separation from each other. After the second sealing device 600 is opened, the solutions on both sides can be quickly mixed, and the two quickly contact to form a complex. In order to achieve the above purpose, the pressure difference design within the box adjustment area 700 in the second chamber 120 can be greatly deviated, and the solution with high pressure can quickly flow into the side with low pressure to achieve rapid mixing.

[0042] The predetermined amount of buffer solution pumped is calculated based on the amount of solid matter on the surface of the first electrolysis area 420. The solid matter generated by electrolysis on the surface of the electrolysis area 420 can be inferred from the reduction in metal ions in the high-solubility solution. The amount of excess residual ions is calculated based on the reduction, and then the appropriate buffer solution is added to ensure the accuracy and stability of the buffer solution added.

[0043] A discharge device 200 is provided at the bottom inner side of the second chamber 120, and a second pumping pipe 121 for pumping cleaning liquid is provided on the outer side of the discharge device 200; after one reverse osmosis is completed in the second chamber 120, the discharge device 200 at the bottom can be opened, and the remaining high-concentration solution and the formed complex in the second chamber 120 can be quickly discharged at the discharge device 200. At the same time, the second pumping pipe 121 here can pump in part of the cleaning liquid to accelerate the discharge of the complex and improve the cleaning effect.

[0044] The discharge device 200 here can also be selected as a plate-shaped sealing structure, which ensures the sealing of the second chamber 120 during the pressurization process while being able to move to a larger opening to achieve rapid discharge of the complex.

[0045] The pressurization method here can be selected as hydraulic pressurization, and the supporting base 300 is pushed toward the first chamber 110 by the hydraulic telescopic device to increase the pressure in the second chamber 120 to achieve reverse osmosis; at the same time, the supporting base 300 can concentrate the high-concentration solution and complex in the second chamber 120 in a smaller range during the process of moving toward the inside, which can accelerate the rapid discharge of subsequent complexes.

[0046] Finally, it should be noted that this solution can be used to remove impurities from circulating water in liquid systems. Circulating water is used as the cooling medium for heat exchange equipment. If the water quality deteriorates, it will cause scaling in the equipment pipes, trigger under-scale corrosion, reduce the heat transfer efficiency of the heat exchanger, and have a significant impact on the efficiency of all production links.

[0047] The main reasons affecting the quality of circulating water are as follows:

[0048] 1. Water evaporates in the reverse osmosis equipment, resulting in an increase in the salt content of the water, the decomposition and escape of carbon dioxide in the water, and the "Ca" in the water during the circulating cooling process. 2+ Mg 2+ The probability of contact between cations and anions doubles, thus generating substances such as "salt scale". These sediments clog pipes, reduce heat transfer efficiency, increase energy consumption, and affect the normal operation of equipment.

[0049] 2. When water comes into contact with air in the reverse osmosis equipment, the dissolved oxygen in the water becomes saturated, which leads to electrochemical corrosion of the metal (oxidative corrosion). During the cooling process, when hot water and air produce convection, a large amount of dust, sediment, microorganisms, etc. in the air are inhaled, which increases the sludge in the system. Under suitable conditions of sunlight, temperature and oxygen, bacteria and algae will grow in the reverse osmosis equipment.

[0050] 3. Microorganisms and suspended matter in the circulating water will clog pipes and damage equipment, thereby affecting the stability of conductivity. Secondly, excessively high conductivity may also be due to a small concentration ratio, which means that the proportion of make-up water is large, which may lead to water quality deterioration, equipment corrosion and other problems, thereby increasing conductivity.

[0051] It is known that the circulating water volume of a copper mine is 300m 3 / h, the water intake of the electrochemical treatment equipment is selected according to about 8% of the total circulating water volume, that is, the processing volume per hour is controlled at 24m³, ensuring that the electrochemical equipment processes the circulating water twice within 24 hours. Therefore, a 100-unit containing device (single device processing capacity 25m³ / h) electrochemical treatment equipment is selected to remove calcium and magnesium ions in the water, control alkalinity, and kill bacteria and algae; it has the following advantages.

[0052] (1) Electrochemical water treatment equipment is based on the basic principles of water electrochemistry. It uses the electrochemical properties of water and minerals in the water in the reaction chamber to create an oxidation reaction environment and a reduction reaction environment near the inner wall of the electrode (anode) and the reaction chamber (cathode), respectively, so as to achieve the pre-deposition of scale and its removal and the online production of bactericidal and algaecidal substances.

[0053] (2) Water is electrolyzed near the inner wall of the reaction chamber to produce hydroxide, which raises the pH value to 14. In a highly alkaline environment, calcium ions in the water precipitate in the form of calcium carbonate scale and adhere to the inner wall. As the scale deposited on the inner wall of the reaction chamber increases, the deposited scale is regularly scraped off and discharged from the circulating water system to maintain the mineral balance in the circulating water and achieve stable water quality.

[0054] (3) The chloride ions in the water near the anode of the equipment are oxidized to produce free chlorine (≥0.1 mg / L), as well as ozone, hydrogen peroxide and other substances, which effectively kill microorganisms entering the reaction chamber and continuously control the growth of bacteria and algae in the entire circulating water system.

[0055] (4) By taking advantage of the natural increase in alkalinity during water evaporation, the circulating water can be kept in an alkaline environment through appropriate pH adjustment to reduce corrosion; at the same time, the concentration of magnesium ions in the water will effectively prevent the occurrence of corrosion.

[0056] (5) Electrochemical water treatment equipment solves the scaling, corrosion and microbial contamination problems of the circulating water system, and the circulating water system no longer needs to add chemical scale inhibitors, corrosion inhibitors and bactericidal algaecides; electrochemical water treatment is a green and environmentally friendly water treatment technology without any pollution, which avoids the secondary pollution caused by the addition of chemical agents in the wastewater discharged from the circulating water system and reduces the burden of sewage treatment.

[0057] The present invention can connect the electrochemical device and the reverse osmosis device in series, reduce the concentration of ions in the liquid through the electrochemical device, and ultimately greatly reduce the pressure of the reverse osmosis, reduce resource consumption, and improve economic benefits.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for reducing reverse osmosis pressure based on electrochemistry, using a containing device (100), wherein a first chamber (110) for containing a low-concentration solution and a second chamber (120) for containing a high-concentration solution are formed inside the containing device (100), and a reverse osmosis membrane is provided between the first chamber (110) and the second chamber (120), characterized in that: The inner wall of the second chamber (120) is further provided with a bearing base (300), the bearing base (300) is sealingly and slidingly connected to the inner wall of the second chamber (120), the side wall of the bearing base (300) is provided with a through bearing opening (310), the inner wall of the bearing opening (310) is rotatably connected to an electrolytic deposition device (400), and the electrolytic deposition device (400) has at least two electrolytic deposition areas (420); The steps include: S1, placing a low-concentration solution in the first chamber (110), placing a high-concentration solution in the second chamber (120), and controlling the second chamber (120) to be in a relatively closed state; S2, continuously increasing the pressure in the second chamber (120), controlling the liquid to pass through the reverse osmosis membrane and enter the first chamber (110); at the same time, controlling the electrolysis device (400) to be in a conductive state, controlling the metal ions in the second chamber (120) to continuously electrolyze on the surface of the first electrolysis region (420) of the electrolysis device (400) to reduce the concentration of the high-concentration solution; S3. After the solid material on the surface of the first electrolytic deposition area (420) has been deposited to a predetermined thickness, the electrolytic deposition device (400) is rotated to a predetermined angle, the first electrolytic deposition area (420) is deflected to the outside for cleaning, and the second electrolytic deposition area (420) is deflected to the inside to complete continuous electrolytic deposition; The electrolysis device (400) comprises a rotating body (410), the electrolysis areas (420) are arranged on the outer surface of the rotating body (410) and are spaced apart in the circumferential direction, the side wall of the rotating body (410) is provided with at least two first sealing grooves (430), and a first sealing device (500) is provided on the outer side of the first sealing groove (430); The first chamber (110) and the second chamber (120) are placed horizontally, and a second sealing device (600) located inside the supporting base (300) is further provided inside the second chamber (120). A predetermined distance is provided between the first sealing device (500) and the second sealing device (600) to form an adjustment area (700).

2. The method for reducing reverse osmotic pressure based on electrochemistry according to claim 1, characterized in that: The first sealing device (500) comprises a first sealing base (510), the inner wall of the first sealing base (510) being provided with at least two first driving chambers (520), and the inner wall of the first driving chamber (520) being sealingly and slidingly connected to a first sealing end (530) adapted to the first sealing groove (430).

3. The method for reducing reverse osmotic pressure based on electrochemistry according to claim 1, characterized in that: The second sealing device (600) comprises a second sealing base (610) and a third sealing base (620); the inner wall of the second sealing base (610) is sealingly and slidingly connected to a second sealing end (611); and the side wall of the third sealing base (620) is provided with a second sealing groove adapted to the second sealing end (611).

4. The method for reducing reverse osmotic pressure based on electrochemistry according to claim 1, characterized in that: The regulating area (700) is connected to a first pumping pipe for conveying a buffer solution. In step S3, after the second electrolytic area (420) is deflected inward, a predetermined amount of buffer solution is pumped through the first pumping pipe to mix with the high-concentration solution. After mixing, a complex is formed to further reduce the concentration of the high-concentration solution.

5. The method for reducing reverse osmotic pressure based on electrochemistry according to claim 4, characterized in that: The predetermined amount of the buffer solution pumped is calculated based on the amount of solid matter on the surface of the first electrolytic region (420).

6. The method for reducing reverse osmosis pressure based on electrochemistry according to claim 4, characterized in that: A discharge device (200) is provided at the bottom of the inner side of the second chamber (120), and a second pumping pipe (121) for pumping cleaning liquid is provided outside the discharge device (200).

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