Maleic anhydride purification device

Abstract

The utility model provides a maleic anhydride purification device and belongs to the field of separation devices. The utility model provides a maleic anhydride purification device which comprises a heating kettle, a first condensation pipe, a first collection kettle, a three-way pipe, a second condensation pipe, a connecting pipe, a second collection kettle and a condensate supply part. And desublimation of maleic anhydride in the first condensation pipe can be avoided.

Description

Technical Field

[0001] This utility model relates to the field of separation devices, specifically to a maleic anhydride purification device. Background Technology

[0002] Maleic anhydride is an important chemical raw material that can be used in the production of some electronic chemical materials. These electronic chemical materials have higher requirements for the metal ion content than conventional materials, and therefore also have higher requirements for the metal ion content of maleic anhydride as a raw material.

[0003] British Patent GB993712 discloses that the content of metal ions in maleic anhydride can be reduced by distillation. However, since maleic anhydride has a melting point of 51-56℃, it easily sublimates into a solid in the condenser when the distilled maleic anhydride is collected, thus clogging the condenser and causing a significant reduction in distillation efficiency. Utility Model Content

[0004] This invention was developed to solve the above-mentioned problems, and its purpose is to provide a maleic anhydride purification device that can effectively reduce ion content and prevent blockage inside the device.

[0005] This utility model provides a maleic anhydride purification device for purifying maleic anhydride containing impurities, characterized by the following features:

[0006] A heating vessel is used to contain maleic anhydride containing impurities and heat it to vaporize the maleic anhydride into gaseous maleic anhydride.

[0007] The first condenser tube is connected to the heating vessel and is used to receive gaseous maleic anhydride and perform the first condensation on it, with some of the gaseous maleic anhydride condensing to form the first condensate.

[0008] The first collecting vessel is connected to the first condenser tube and is used to receive the first condensate.

[0009] The three-way pipe has three ports, which are respectively connected to the heating vessel, the first condenser and the first collecting vessel;

[0010] The second condenser tube, connected to the first condenser tube, is used to receive gaseous maleic anhydride that has not been condensed in the first condenser tube.

[0011] The connecting pipe has one end connected to the first condenser pipe and the other end connected to the second condenser pipe;

[0012] The second collecting vessel includes a second collecting vessel body and a vacuum source. The second collecting vessel body is connected to the second condenser tube and is used to receive maleic anhydride liquefied in the second condenser tube. The vacuum source is used to provide a vacuum inside the second collecting vessel body.

[0013] The condensate supply unit includes several condensate supply devices for supplying and recovering condensate to the first condenser and the second condenser.

[0014] The maleic anhydride purification apparatus provided by this utility model may also have the following feature: wherein the heating vessel includes:

[0015] The heating vessel body has an opening at the top for connecting to a three-way pipe and a feed inlet for feeding, and a discharge outlet at the bottom for discharging.

[0016] A stirring component, installed in the main body of the heating vessel, is used to stir the materials inside the heating vessel.

[0017] A heating vessel sleeve is fitted over the outside of the main body of the heating vessel and is used to heat the vessel.

[0018] The maleic anhydride purification apparatus provided by this utility model may also have the following feature: the heating vessel further includes:

[0019] A thermometer, installed on the main body of the heating vessel, is used to monitor the temperature inside the heating vessel.

[0020] A barometer for the heating vessel is installed on the main body of the heating vessel to monitor the pressure inside the main body of the heating vessel.

[0021] The discharge pipe of the heating vessel is installed at the bottom of the main body of the heating vessel;

[0022] The discharge valve of the heating vessel is installed on the discharge pipe of the heating vessel and is used to control the opening and closing of the discharge pipe.

[0023] The maleic anhydride purification device provided by this utility model may also have the following feature: wherein the three-way pipe includes:

[0024] Spherical tube;

[0025] The first branch pipe is connected at one end to the spherical tube and at the other end to the main body of the heating vessel;

[0026] The second branch pipe is connected to the spherical tube at one end and to the first condenser tube at the other end;

[0027] The third branch pipe is connected to the spherical pipe at one end and to the first collecting vessel at the other end.

[0028] The maleic anhydride purification apparatus provided by this utility model may also have the following feature: wherein the first collecting vessel includes:

[0029] First collecting vessel body;

[0030] A heating jacket for the collecting vessel is fitted over the main body of the first collecting vessel and is used to heat the main body of the first collecting vessel.

[0031] The feed valve of the first collecting vessel is installed at the connection between the three-way pipe and the first collecting vessel;

[0032] The discharge pipe of the first collecting vessel is installed at the bottom of the main body of the first collecting vessel;

[0033] The discharge valve of the first collecting vessel is installed on the discharge pipe of the first collecting vessel and is used to control the opening and closing of the discharge pipe of the first collecting vessel.

[0034] The maleic anhydride purification device provided by this utility model may also have the following feature: wherein the connecting tube includes:

[0035] A first connecting section is installed at the top of the first condenser tube and communicates with the interior of the first condenser tube; and

[0036] The second connecting section is installed on the top of the second condenser tube and communicates with the inside of the second condenser tube. The first connecting section and the second connecting section are detachably connected.

[0037] The maleic anhydride purification device provided by this utility model may also have the following feature: the condensate supply unit includes:

[0038] A combined cooling and heating unit supplies and recovers condensate to the first and second condenser coils.

[0039] The maleic anhydride purification device provided by this utility model may also have the following feature: the temperature of the condensate used in the first condenser is lower than the temperature of the condensate used in the second condenser.

[0040] The maleic anhydride purification apparatus provided by this utility model may also have the following feature: wherein the second collecting vessel further includes:

[0041] The vacuum tube is connected at one end to the main body of the second collection vessel and at the other end to the vacuum source;

[0042] Vacuum valves, installed on vacuum tubes; and

[0043] A vacuum tube barometer is installed on a vacuum tube.

[0044] The maleic anhydride purification apparatus provided by this utility model may also have the following feature: wherein the second collecting vessel further includes:

[0045] The discharge pipe of the second collecting vessel is installed at the bottom of the main body of the second collecting vessel;

[0046] The discharge valve of the second collecting vessel is installed on the discharge pipe of the second collecting vessel and is used to control the opening and closing of the discharge pipe of the second collecting vessel.

[0047] Functions and effects of utility models

[0048] According to the maleic anhydride purification device involved in this utility model, because it has a second condenser connected to the first condenser, the maleic anhydride purification device provided by this utility model can not only purify maleic anhydride and reduce its metal ion content, but also prevent maleic anhydride from sublimating in the first condenser. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the maleic anhydride purification device in an embodiment of this utility model. Detailed Implementation

[0050] To make the technical means, creative features, objectives and effects of this utility model easy to understand, the following describes this utility model in detail with reference to the embodiments and accompanying drawings.

[0051] <Example 1>

[0052] A purification device for maleic anhydride

[0053] like Figure 1 As shown, the maleic anhydride purification device 1 provided in this embodiment includes: a heating vessel 10, a first condenser 61, a first collecting vessel 30, a three-way pipe 20, a second condenser 71, a connecting pipe 40, a second collecting vessel 80, and a condensate supply unit 91.

[0054] The heating vessel 10 includes: a heating vessel body 11, a stirring component 12, a heating vessel heating jacket 13, a thermometer 14, a heating vessel pressure gauge 15, a heating vessel discharge pipe 16, and a heating vessel discharge pipe valve 17.

[0055] The heating vessel body 11 has a first opening for communicating with the three-way pipe 20, a discharge port at its bottom for installing the heating vessel discharge pipe 16, and a feed port at its top for feeding (not shown in the figure).

[0056] The agitator 12 is installed on the heating vessel body 11 and is used to agitate the materials inside the heating vessel body 11.

[0057] The heating jacket 13 is fitted on the outside of the heating vessel body 11 and is used to heat the material inside the heating vessel body 11 to vaporize it.

[0058] The thermometer 14 is installed on the heating vessel body 11 to detect the temperature inside the heating vessel body 11.

[0059] The pressure gauge 15 of the heating vessel is installed on the heating vessel body 11 and is used to detect the pressure inside the heating vessel body 11.

[0060] The discharge pipe 16 of the heating vessel is installed at the discharge port at the bottom of the heating vessel body 11.

[0061] The discharge valve 17 of the heating vessel is installed on the discharge pipe 16 of the heating vessel.

[0062] The tee pipe 20 includes: a ball-shaped pipe 21, a first branch pipe 22, a second branch pipe 23, and a third branch pipe 24.

[0063] The spherical tube 21 is spherical, with an opening on its side that connects to the first branch tube 22, an opening at its top that connects to the second branch tube 23, and an opening at its bottom that connects to the third branch tube 24.

[0064] One end of the first branch pipe 22 is connected to the first opening of the heating vessel body 11, and the other end is connected to the spherical pipe 21.

[0065] One end of the second branch pipe 23 is connected to the first condenser pipe 61, and the other end is connected to the spherical pipe 21.

[0066] One end of the third branch pipe 24 is connected to the first collecting vessel 30, and the other end is connected to the spherical pipe 21.

[0067] In this embodiment, the spherical tube 21, the first branch tube 22, the second branch tube 23, and the third branch tube 24 are integrally formed.

[0068] The first collecting vessel 30 includes: a first collecting vessel body 31, a collecting vessel heating jacket 32, a first collecting vessel feed valve 33, a first collecting vessel discharge pipe 34, and a first collecting vessel discharge valve 35.

[0069] The first collecting vessel body 31 has a feed inlet at its top, through which it is connected to the third branch pipe 24 in the three-way pipe 20. The first collecting vessel body 31 and the third branch pipe 24 are detachably connected. In this embodiment, the first collecting vessel body 31 and the third branch pipe 24 are connected by a flange. In other embodiments, they can also be connected by a clamp or other means.

[0070] The heating jacket 32 ​​of the collecting vessel is fitted outside the first collecting vessel body 31 and is used to heat the first collecting vessel body 31.

[0071] The first collecting vessel feed valve 33 is installed at the feed inlet of the first collecting vessel body 31 and is used to control the opening and closing of the third branch pipe 24 and the first collecting vessel body 31.

[0072] The discharge pipe 34 of the first collecting vessel is installed at the bottom of the first collecting vessel body 31 and is used to discharge the material collected in the first collecting vessel body 31 from the bottom of the first collecting vessel body 31.

[0073] The discharge valve 35 of the first collecting vessel is installed on the discharge pipe 34 of the first collecting vessel and is used to control the opening and closing of the discharge pipe 34 of the first collecting vessel.

[0074] The first condenser tube 61 has an internal spiral tube for material passage. The spiral tube is connected to the second branch tube 23 through its bottom opening and to the connecting tube 40 through its top opening. A hollow glass cover is fitted over the spiral tube. The bottom and top of the glass cover each have an opening, which are respectively connected to the condensate supply port and condensate recovery port of the condensate supply unit 91 for introducing and discharging condensate, thereby condensing the material inside the spiral tube.

[0075] The second condenser tube 71 has an internal spiral tube for material passage. The spiral tube is connected to the connecting pipe 40 through its top opening and to the second collecting vessel 80 through its bottom opening. A hollow glass cover is fitted over the spiral tube. The bottom and top of the glass cover each have an opening, which are respectively connected to the condensate supply port and condensate recovery port of the condensate supply unit 91 for introducing and discharging condensate, thereby condensing the material inside the spiral tube.

[0076] The connecting pipe 40 includes a first connecting section 41 and a second connecting section 42.

[0077] One end of the first connecting section 41 is connected to the spiral tube of the first condenser tube 61 through the top opening of the spiral tube of the first condenser tube 61, and the other end is connected to the second connecting section 42.

[0078] One end of the second connecting section 42 is connected to the first connecting section 41, and the other end is connected to the spiral tube of the second condenser tube 71 through the top opening of the spiral tube.

[0079] In this embodiment, the first connecting segment 41 and the second connecting segment 42 are detachably connected, more specifically, they are detachably connected via clips. In other embodiments, the first connecting segment 41 and the second connecting segment 42 can be connected by other detachable methods, such as flange connection; they can also be integrally formed.

[0080] The second collecting vessel 80 includes: a second collecting vessel body 81, a vacuum tube 82, a second collecting vessel pressure gauge 83, a vacuum tube valve 84, a vacuum source 85, a second collecting vessel discharge pipe 86, and a second collecting vessel discharge valve 87.

[0081] The second collecting vessel body 81 has an opening at its top for connecting to the spiral tube in the second condenser tube 71, an opening on its top side for connecting to the vacuum tube 82, and an opening at its bottom for installing the discharge pipe 86 of the second collecting vessel. The second collecting vessel body 81 and the second condenser tube 71 are detachably connected. In this embodiment, the second collecting vessel body 81 and the second condenser tube 71 are connected by a flange. In other embodiments, they can also be connected by clamps or other means.

[0082] Vacuum tube 82 is installed on the opening on the top side of the second collecting vessel body 81, with one end connected to the inside of the second collecting vessel body 81 and the other end connected to the vacuum source 85.

[0083] The second collecting vessel pressure gauge 83 is installed on the vacuum tube 82 and is used to detect the internal pressure of the vacuum tube 82.

[0084] Vacuum tube valve 84 is installed on vacuum tube 82 and is used to control the opening and closing of vacuum tube 82.

[0085] The vacuum source 85 is used to provide a vacuum to the interior of the second collecting vessel body 81 and the space connected to the second collecting vessel body 81 through the vacuum tube 82. In this embodiment, the vacuum source is a vacuum pump.

[0086] The discharge pipe 86 of the second collecting vessel is installed at the bottom of the body 81 of the second collecting vessel and is connected to the interior of the body 81 of the second collecting vessel.

[0087] The second collection vessel discharge valve 87 is installed on the second collection vessel discharge pipe 86 and is used to control the opening and closing of the second collection vessel discharge pipe.

[0088] The condensate supply unit 91 is used to supply and recover condensate to the first condenser 61 and the second condenser 71 via pipelines. In this embodiment, the condensate supply unit 91 includes a combined cooling and heating unit that can simultaneously supply and recover condensate at multiple different temperatures. Specifically, in this embodiment, the combined cooling and heating unit supplies 10°C condensate to the first condenser and 60°C condensate to the second condenser. In other embodiments, the condensate supply unit 91 may include two independent combined cooling and heating units, which independently supply condensate to the first condenser 61 and the second condenser 71, respectively.

[0089] The method of using the maleic anhydride purification device provided in this embodiment includes the following steps:

[0090] Step 1: Set the maleic anhydride purification device 1 to the initial state: close the heating vessel discharge valve 17, the first collection vessel discharge valve 35, the first collection vessel feed valve 33 and the second collection vessel discharge valve 87, and open the vacuum tube valve 84;

[0091] Step 2: Add maleic anhydride containing impurities into the heating vessel body 11 through the feed port of the heating vessel body 11. Turn on the vacuum source, and the heating vessel heating jacket 13 and the collecting vessel heating jacket 32 ​​start working. The condensate supply unit 91 starts to supply and recover condensate to the first condenser tube 61 and the second condenser tube 71 through pipelines. In this embodiment, the negative pressure provided by the vacuum source is -0.099MPa, the heating temperature of the heating vessel heating jacket 13 is 110°C, the heating temperature of the collecting vessel heating jacket 32 ​​is 60°C, the temperature of the condensate used in the first condenser tube 61 is 50°C, and the temperature of the condensate used in the second condenser tube 71 is 65°C.

[0092] Step 3: Open the feed valve 33 of the first collecting vessel. The material in the heating vessel body 11 is heated and vaporized. It enters the first condenser 61 through the three-way pipe. Some of the gaseous maleic anhydride is liquefied in the first condenser 61 and enters the first collecting vessel body 31 under the action of gravity. The maleic anhydride that is not liquefied in the first condenser 61 will enter the second condenser 71 through the connecting pipe under the guidance of negative pressure and sublimate into a solid in the top area. Then, under the action of the condensate in the second condenser 71, it is liquefied into maleic anhydride and enters the second collecting vessel body 81 under the action of gravity.

[0093] Step 4: Turn off the vacuum source 85, close the feed valve 33 of the first collection vessel, open the discharge valve 35 of the first collection vessel and the discharge valve 87 of the second collection vessel, and collect the maleic anhydride in the body 31 of the first collection vessel and the body 81 of the second collection vessel, which is the purified maleic anhydride.

[0094] <Test Example>

[0095] Purification test of maleic anhydride

[0096] In this test example, commercially available maleic anhydride was purified using the maleic anhydride purification apparatus described in Example 1 and a conventional distillation apparatus, respectively.

[0097] In this test example, the method for purifying commercially available maleic anhydride using the maleic anhydride purification apparatus of Example 1 is as described in Example 1.

[0098] In this test case, a total of 40 kg of commercially available maleic anhydride was added to the maleic anhydride purification device 1, and 39.5 kg of purified maleic anhydride was finally recovered.

[0099] In this test example, the conventional distillation apparatus used consists of only a heating vessel, a reflux condenser connected to the heating vessel, a collecting vessel connected to the reflux condenser, and a vacuum source connected to the collecting vessel for providing negative pressure to the apparatus. In this test example, when distilling using the conventional distillation apparatus, the heating temperature of the heating vessel is 110°C, the temperature of the condensate in the condenser is 65°C, and the negative pressure provided by the vacuum source is -0.099 MPa.

[0100] In this test case, a total of 40 kg of commercially available maleic anhydride was added to the conventional distillation apparatus, and 37 kg of purified maleic anhydride was finally recovered.

[0101] The metal ion content in commercially available maleic anhydride and purified maleic anhydride is shown in Table 1.

[0102] Table 1 Metal Ion Content

[0103] Na / ppb K / ppb Fe / ppb Ca / ppb Commercially available maleic anhydride 112 22 228 769 Maleic anhydride purified by conventional distillation 36 6 81 163 Maleic anhydride purified by the apparatus in Example 1 ＜1 ＜1 2 ＜1

[0104] As shown in Table 1, the maleic anhydride purification device provided in Example 1 can effectively reduce its ion content while ensuring a high recovery rate. The reason why conventional distillation devices have poor deionization efficiency and large distillation losses may be because they cannot suppress material sublimation. Sublimated material will block the pipeline and further cause flushing, thereby carrying ions from the heating vessel into the collecting vessel.

[0105] The role and effect of the embodiments

[0106] According to the maleic anhydride purification device involved in the above embodiments, because it has a second condenser connected to the first condenser, the maleic anhydride purification device provided in the above embodiments can not only purify maleic anhydride and reduce its ion content, but also prevent maleic anhydride from sublimating in the first condenser.

[0107] Furthermore, since the second collecting vessel includes a vacuum source, which can provide negative pressure to the second collecting vessel and the space connected to it, maleic anhydride can be vaporized at a lower temperature, saving energy consumption in production.

[0108] Furthermore, since the vacuum source is installed on the body of the second collecting vessel through a vacuum tube, and the vacuum tube is installed at the top side opening of the body of the second collecting vessel, this can both prevent the vacuum tube opening from being blocked by the material entering the second collecting vessel and prevent the material entering the second collecting vessel from being sucked out.

[0109] Furthermore, since the heating vessel includes a stirring element, the material inside the heating vessel can be heated more evenly during heating, making it less prone to coking, thereby improving the recovery rate of purified maleic anhydride.

[0110] Furthermore, since the tee includes a spherical tube, the gas and liquid phases will converge inside the spherical tube. The presence of the spherical tube can play a good buffering role, preventing excessive local pressure in the system from causing safety accidents.

[0111] Furthermore, since the connecting pipe includes a first connecting section and a second connecting section, and the two are detachably connected, it can be easily installed, disassembled, and cleaned.

[0112] Furthermore, since the temperature of the condensate in the first condenser is lower than that in the second condenser, a large amount of gaseous maleic anhydride can be condensed into liquid and allowed to enter the first collecting vessel. Unliquefied maleic anhydride will enter the second condenser under negative pressure and undergo sublimation. The condensate in the second condenser needs a higher temperature to reliquefy the sublimated maleic anhydride and allow it to enter the second collecting vessel. If the second condenser is not installed, and only the condensate in the first condenser is increased, although the sublimation of maleic anhydride in the condenser can be reduced, the gaseous maleic anhydride cannot be liquefied in time, resulting in a significant increase in pressure within the condenser and the three-way pipe, which poses a serious safety hazard.

[0113] Furthermore, since the bottom of the first collecting vessel has a first collecting vessel discharge pipe and the bottom of the second collecting vessel has a second collecting vessel discharge pipe, the purified maleic anhydride can be collected directly by discharging from the discharge pipe, which greatly simplifies the steps and improves efficiency.

[0114] The above embodiments are preferred embodiments of this utility model and are not intended to limit the scope of protection of this utility model.

Claims

1. A maleic anhydride purification apparatus for purifying maleic anhydride containing impurities, characterized in that, include: A heating vessel is used to contain the maleic anhydride containing impurities and heat it to vaporize the maleic anhydride into gaseous maleic anhydride. The first condenser tube is connected to the heating vessel and is used to receive the gaseous maleic anhydride and perform the first condensation on it, with part of the gaseous maleic anhydride condensing to form the first condensate. The first collecting vessel is connected to the first condenser tube and is used to receive the first condensate. The three-way pipe has three ports, which are respectively connected to the heating vessel, the first condenser and the first collecting vessel; The second condenser tube is connected to the first condenser tube and is used to receive gaseous maleic anhydride that has not been condensed in the first condenser tube. The connecting pipe has one end connected to the first condenser pipe and the other end connected to the second condenser pipe; The second collecting vessel includes a second collecting vessel body and a vacuum source. The second collecting vessel body is connected to the second condenser tube and is used to receive maleic anhydride liquefied in the second condenser tube. The vacuum source is used to provide a vacuum to the second collecting vessel body. The condensate supply unit includes several condensate supply devices for supplying and recovering condensate to the first condenser tube and the second condenser tube.

2. The maleic anhydride purification apparatus according to claim 1, Its features are: The heating vessel includes: The heating vessel body has an opening at the top for connecting to the three-way pipe and a feed inlet for feeding, and a discharge outlet at the bottom for discharging. A stirring component is installed in the heating vessel body and is used to stir the materials inside the heating vessel body; A heating vessel sleeve is fitted over the outside of the heating vessel body and is used to heat the heating vessel.

3. The maleic anhydride purification apparatus according to claim 2, Its features are: The heating vessel further includes: A thermometer is installed on the heating vessel body to monitor the temperature inside the heating vessel body; A pressure gauge for the heating vessel is installed on the main body of the heating vessel to monitor the pressure inside the main body of the heating vessel. The discharge pipe of the heating vessel is installed at the bottom of the main body of the heating vessel; A discharge valve for the heating vessel is installed on the discharge pipe of the heating vessel and is used to control the opening and closing of the discharge pipe of the heating vessel.

4. The maleic anhydride purification apparatus according to claim 1, Its features are: The tee pipe includes: Spherical tube; The first branch pipe has one end connected to the spherical tube and the other end connected to the main body of the heating vessel; The second branch pipe has one end connected to the spherical pipe and the other end connected to the first condenser pipe; The third branch pipe is connected at one end to the spherical pipe and at the other end to the first collecting vessel.

5. The maleic anhydride purification apparatus according to claim 1, Its features are: The first collection vessel includes: First collecting vessel body; A heating jacket for the collecting vessel is fitted over the body of the first collecting vessel and is used to heat the body of the first collecting vessel. The first collecting vessel feed valve is installed at the connection between the three-way pipe and the first collecting vessel; The discharge pipe of the first collecting vessel is installed at the bottom of the main body of the first collecting vessel; The first collection vessel discharge valve is installed on the first collection vessel discharge pipe and is used to control the opening and closing of the first collection vessel discharge pipe.

6. The maleic anhydride purification apparatus according to claim 1, Its features are, The connecting pipe includes: A first connecting section is installed at the top of the first condenser tube and communicates with the interior of the first condenser tube; and The second connecting section is installed on the top of the second condenser tube and communicates with the inside of the second condenser tube. The first connecting section and the second connecting section are detachably connected.

7. The maleic anhydride purification apparatus according to claim 1, characterized in that, in, The condensate supply unit includes: A combined cooling and heating unit is used to supply and recover condensate to the first condenser and the second condenser respectively.

8. The maleic anhydride purification apparatus according to claim 1, characterized in that, in, The temperature of the condensate used in the first condenser is lower than the temperature of the condensate used in the second condenser.

9. The maleic anhydride purification apparatus according to claim 1, Its features are, The second collection vessel further includes: The vacuum tube is connected at one end to the main body of the second collection vessel and at the other end to the vacuum source; A vacuum valve is installed on the vacuum tube; and A vacuum tube barometer is installed on the vacuum tube.

10. The maleic anhydride purification apparatus according to claim 1, Its features are, The second collection vessel further includes: The discharge pipe of the second collecting vessel is installed at the bottom of the main body of the second collecting vessel; The second collection vessel discharge valve is installed on the discharge pipe of the second collection vessel and is used to control the opening and closing of the discharge pipe of the second collection vessel.

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