Vacuum negative pressure sampling system and sampling method

Abstract

The invention discloses a vacuum negative pressure sampling system and sampling method.The vacuum negative pressure sampling system comprises a sampler internally provided with a sampling cavity, an air exhaust passage and a purging passage, the air exhaust passage and the purging passage are connected with the sampler and communicated with the sampling cavity, an outlet of the sampler is connected with a first valve, an inlet of the sampler is connected with a stock bin, and a second valve is arranged on a connecting pipeline; the air exhaust passage comprises an external air source, a first electromagnetic valve, a vacuum generator and a second electromagnetic valve which are connected in sequence, the second electromagnetic valve is connected with the sampler, and a pressure switch is arranged on a connecting pipeline of the second electromagnetic valve and the sampler; the purging passage comprises a third electromagnetic valve, one end of the third electromagnetic valve is connected with an external air source, and the other end of the third electromagnetic valve is connected with a sampler. Vacuum negative pressure sampling is adopted, and compared with a traditional sampling mode, the sampling process is fully automatic, the control precision is higher, and the sampling process is efficient and free of pollution.

Description

Technical Field

[0001] The present invention relates to the field of sampling technology, and in particular to a vacuum negative pressure sampling system and a sampling method. Background Art

[0002] The traditional sampling method is to use manual sampling or mechanically place the sampling box into the silo to collect the material, which is easy to cause material contamination and lag in sampling results. For finer powder materials, the traditional sampling method cannot achieve full sealing, so a small amount of material will leak, causing environmental pollution and reducing the sampling accuracy.

[0003] Secondly, the traditional sampling method requires manual disassembly of the sampling box for cleaning, or cleaning through gas blowing into the sampling chamber. For example, in the invention patent applied for by the applicant, entitled "A Piston-propelled Automatic Sampler" and with application number CN202311114430.1, an air hole is provided at the discharge port to blow off the remaining material in the sampling chamber. However, this cleaning method is only applicable to sampling boxes with a small volume and a relatively standardized shape. For sampling boxes with a large volume or an irregular shape, it is difficult to clean the sampling box by blowing only at the discharge port. In addition, during the sampling process, material accumulation is prone to occur at the connection between the silo and the sampler. If it is not cleaned in time, it will cause difficulties in the next sampling. Summary of the invention

[0004] In order to solve the technical problems in the prior art that the sampler is prone to cause material contamination and has low sampling accuracy, the present invention provides a vacuum negative pressure sampling system and a sampling method to solve the above problems.

[0005] The present invention proposes a vacuum negative pressure sampling system, including a sampler with a sampling cavity inside, and an exhaust passage and a purge passage connected to the sampler and communicated with the sampling cavity, wherein the outlet of the sampler is connected to a first valve, the inlet of the sampler is connected to a silo and a second valve is arranged on the connecting pipeline; the exhaust passage includes an external air source, a first solenoid valve, a vacuum generator and a second solenoid valve connected in sequence, the second solenoid valve is connected to the sampler and a pressure switch is arranged on the connecting pipeline between the two; the purge passage includes a third solenoid valve, one end of the third solenoid valve is connected to the external air source, and the other end is connected to the sampler.

[0006] Furthermore, an exciter is installed on the outer surface of the sampler, and the exciter is connected to an external air source through a fourth solenoid valve.

[0007] Furthermore, the sampler is connected to the side wall of the silo, and the sampling cavity of the sampler includes a first straight cavity and a second straight cavity arranged obliquely, the pipeline where the first valve is located is coaxially arranged with the second straight cavity, and the pipeline where the second valve is located is coaxially arranged with the first straight cavity.

[0008] Furthermore, a pressure relief branch is provided on the connecting pipeline between the second solenoid valve and the sampler.

[0009] Furthermore, the pressure relief branch is a silencer and a sixth solenoid valve connected to each other, and the sixth solenoid valve is connected to the air extraction passage.

[0010] Furthermore, a filter is provided at one end of the exhaust passage and the purge passage close to the sampler.

[0011] Furthermore, a purge bypass is connected between the exhaust passage and the purge passage, a fifth solenoid valve is arranged on the purge bypass, the connection point between the purge bypass and the exhaust passage is located at the outlet of the second solenoid valve, and the connection point between the purge bypass and the purge passage is located at the inlet of the third solenoid valve.

[0012] Furthermore, the exhaust passage is connected to the first straight cavity, and the purge passage is connected to the second straight cavity.

[0013] The present invention also provides a sampling method, which adopts the vacuum negative pressure sampling system described above and includes the following steps: S11: System initialization, close all valves, and set the initial value of the pressure switch.

[0014] S12: Vacuuming the sampling chamber: Open the first solenoid valve and the second solenoid valve until the pressure switch reaches a specified value and then close the first solenoid valve and the second solenoid valve.

[0015] S13: Open the second valve to feed, and close it after a few seconds.

[0016] S14: The first valve is opened for the first time, and the first valve is closed after a certain amount of gas is released from the sampling chamber.

[0017] S15: Open the third solenoid valve to blow away the material, and then close the third solenoid valve after a few seconds.

[0018] S16: Open the first valve to discharge the material.

[0019] S17: Close the first valve, open the third solenoid valve and the second valve, and clean the sampling chamber.

[0020] The present invention also provides a sampling method, which adopts the vacuum negative pressure sampling system described above and includes the following steps: S21: System initialization, close all valves, and set the initial value of the pressure switch.

[0021] S22: Vacuuming the sampling chamber: Open the first solenoid valve and the second solenoid valve until the pressure switch reaches a specified value and then close the first solenoid valve and the second solenoid valve.

[0022] S23: Open the second valve to feed, and close it after a few seconds.

[0023] S24: The first valve is opened for the first time, and the first valve is closed after a certain amount of gas is released from the sampling chamber.

[0024] S25: Open the fifth solenoid valve to blow the material forward, close the fifth solenoid valve after a few seconds, open the third solenoid valve and the pressure relief branch, blow the material backward, and close the third solenoid valve and the pressure relief branch after a few seconds.

[0025] S26: Open the pressure relief branch to continue pressure relief, and close the pressure relief branch after a few seconds.

[0026] S27: Open the first valve to discharge the material.

[0027] S28: Close the first valve, open the third solenoid valve and the second valve, and clean the sampling chamber.

[0028] The beneficial effects of the present invention are: (1) The present invention adopts vacuum negative pressure sampling. Compared with the traditional sampling method, the sampling process is fully automated, the control accuracy is higher, and the sampling process is efficient and pollution-free.

[0029] (2) The present invention utilizes an exhaust passage to evacuate the sampling chamber, and then utilizes a purge passage to back-blow the material after sampling to prevent the material from compacting. High-precision material sampling is achieved through flexible switching of the two passages and the sampler inlet and outlet. At the same time, the purge passage can also spray the sampling chamber and the connection between the sampling chamber and the silo after sampling is completed, thereby avoiding material accumulation inside the sampler and at the connection between the sampler and the silo.

[0030] (3) The present invention configures the sampler to be two straight cavities, so that the inlet and outlet of the sampler can be connected to adjacent equipment through straight pipes to avoid clogging of materials in the pipeline. At the same time, a purge bypass is provided between the exhaust passage and the purge passage, and part of the pipeline of the exhaust passage is used to achieve the purge of one of the straight cavities. The material in the sampling cavity is completely dispersed through the cooperation of the purge bypass and the purge passage, which is conducive to rapid material discharge. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0032] Figure 1 is a schematic diagram of a specific implementation of the vacuum negative pressure sampling system of the present invention; Figure 2 It is a schematic diagram of a specific implementation of the vacuum negative pressure sampling system described in the present invention.

[0033] In the figure, 1, sampler, 2, fifth solenoid valve, 3, exhaust passage, 4, purge passage, 5, first valve, 6, silo, 7, second valve, 8, first solenoid valve, 9, vacuum generator, 10, second solenoid valve, 11, pressure switch, 12, third solenoid valve, 13, exciter, 14, fourth solenoid valve, 15, filter, 16, pressure relief branch, 17, muffler, 18, sixth solenoid valve, 19, first straight cavity, 20, second straight cavity, 21, purge bypass. DETAILED DESCRIPTION

[0034] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0035] Embodiment 1 like Figure 1-Figure 2 As shown, a vacuum negative pressure sampling system includes a sampler 1 with a sampling cavity inside, and an exhaust passage 3 and a purge passage 4 connected to the sampler 1 and communicated with the sampling cavity, the outlet of the sampler 1 is connected to a first valve 5, the inlet of the sampler 1 is connected to a silo 6 and a second valve 7 is arranged on the connecting pipeline; the exhaust passage 3 includes an external air source, a first solenoid valve 8, a vacuum generator 9 and a second solenoid valve 10 connected in sequence, the second solenoid valve 10 is connected to the sampler 1 and a pressure switch 11 is arranged on the connecting pipeline between the two; the purge passage 4 includes a third solenoid valve 12, one end of the third solenoid valve 12 is connected to the external air source, and the other end is connected to the sampler 1.

[0036] The sampler 1 is a structure with two ends connected, which can be directly connected to the front-end silo 6 and the rear-end material receiving equipment. The on-off is controlled by a valve. The exhaust passage 3 is used to vacuum the sampling chamber. The external air source can provide compressed air to the pipeline. The setting of the vacuum generator 9 can convert the positive air pressure into negative pressure, thereby achieving a negative pressure effect. The first solenoid valve 8 and the second solenoid valve 10 are set at both ends of the vacuum generator 9, which can control the on-off of the pipelines before and after the vacuum generator 9. When the vacuum generator 9 fails, the first solenoid valve 8 and the second solenoid valve 10 can be disconnected and the vacuum generator 9 can be replaced without affecting the sampling work.

[0037] The pressure switch 11 is used to monitor the internal pressure of the sampling chamber. When sampling, the sampling chamber needs to be kept in a negative pressure state. Since the pipeline between the pressure switch 11 and the sampling chamber is in a normally connected state, the internal pressure can be monitored and adjusted in real time.

[0038] The purge passage 4 has two functions. The first function is to break up the material. When the material is sucked into the sampling chamber under the action of negative pressure, the material is easy to compact due to the large adsorption force. The purge passage 4 needs to purge the material before the sampler 1 unloads the material to break up the material. The second function is to clean the channel. After the sampling chamber is emptied, the purge passage 4 can be opened to clean the sampling chamber and the connection between the sampling chamber and the silo 6 to avoid the material sticking to the wall and causing a decrease in sampling accuracy.

[0039] When the sampler 1 is unloading, in order to speed up the unloading speed, a vibrator 13 is preferably installed on the outer surface of the sampler 1 , and the vibrator 13 is connected to an external air source through a fourth solenoid valve 14 .

[0040] Since the exhaust passage 3 and the purge passage 4 need to introduce external air into the sampling chamber, in order to prevent impurities from entering the sampling chamber, a filter 15 is preferably provided at one end of the exhaust passage 3 and the purge passage 4 close to the sampler 1 to reduce the possibility of material contamination.

[0041] The structure of sampler 1: The sampler 1 is usually connected to the side wall of the silo 6, and the outlet of the sampler 1 is located at the bottom for connecting to the material receiving equipment below. Therefore, there is an angular deflection from the silo 6 to the outlet of the sampler 1. The angular deflection can be achieved by a bent pipe or by the bending design of the sampler 1 itself. Since the diameter of the pipeline is often smaller than the main size of the equipment, it is not easy to clean after the material is accumulated. Therefore, the present invention preferably sets the bending part on the sampler 1. As shown in the figure, the sampling cavity of the sampler 1 includes a first straight cavity 19 and a second straight cavity 20 arranged obliquely, the pipeline where the first valve 5 is located is coaxially arranged with the second straight cavity 20, and the pipeline where the second valve 7 is located is coaxially arranged with the first straight cavity 19. In this way, the connecting pipeline at the inlet and the connecting pipeline at the outlet of the sampler 1 can be straight pipes.

[0042] The sampling process of the vacuum sampling system described in this embodiment is as follows: S11: System initialization, closing all valves, and setting the initial value of the pressure switch 11. In this embodiment, the initial setting value of the pressure switch 11 is -80 KPa.

[0043] S12: Vacuum the sampling chamber: open the first solenoid valve 8 and the second solenoid valve 10. At this time, the exhaust passage 3 is fully connected, and the external air source enters the sampling chamber through the vacuum generator 9, so that the sampling chamber is filled with vacuum until the pressure switch 11 reaches the specified value, and then closes the first solenoid valve 8 and the second solenoid valve 10.

[0044] S13: Open the second valve 7 to feed, and close it after a few seconds. In this embodiment, the second valve 7 is closed after opening for 5 seconds.

[0045] S14: The first valve 5 is opened for the first time, and a certain amount of gas is released from the sampling chamber, and then the first valve 5 is closed. After the sampling chamber is connected with the silo 6, the material rushes into the sampling chamber under the high pressure inside the silo 6. At this time, the pressure inside the sampling chamber is too high, and the material will gather in a local area in the sampling chamber. The first valve 5 is opened to release the gas and pressure. At this time, due to the agglomeration of the material, only a small amount of material will be discharged. When the vibrator 13 is installed, the vibrator 13 is also turned on at the same time. The vibrator 13 and the first valve 5 are opened for 10 seconds and then closed.

[0046] S15: Open the third solenoid valve 12. At this time, the purge passage 4 is fully connected, and compressed air is blown into the sampling chamber to disperse the agglomerated materials. At the same time, the pressure in the sampling chamber is increased to facilitate material discharge. The third solenoid valve 12 is closed after 1 second.

[0047] S16: Open the first valve 5 to discharge the material. Since the material is blown away, the material can fall smoothly at this time. When the vibrator 13 is installed, the vibrator 13 is also turned on at the same time. After 10 seconds, the material in the sampling chamber is completely discharged, and the first valve 5 and the vibrator 13 are closed.

[0048] S17: Open the third solenoid valve 12 and the second valve 7. At this time, the purge passage 4 is opened again, and compressed gas is blown into the sampling chamber again to clean the sampling chamber. At the same time, the sampler 1 is connected to the silo 6, and the compressed gas flows toward the silo 6, which can clean the connection between the sampler 1 and the silo 6 to avoid material blocking the connection and affecting the next sampling.

[0049] Embodiment 2 On the basis of the first embodiment, a pressure relief branch 16 is provided on the connecting pipeline between the second solenoid valve 10 and the sampler 1 .

[0050] After the sampler 1 is filled with material, it needs to rely on positive pressure to discharge the material, but the pressure cannot be too high, otherwise it will cause the material to spray out. The function of the pressure relief branch 16 is to adjust the internal pressure of the sampling chamber.

[0051] The pressure relief branch 16 may be, but is not limited to, a silencer 17 and a sixth solenoid valve 18 connected to each other, and the sixth solenoid valve 18 is connected to the air extraction passage 3. The silencer 17 has a pressure relief function. In this embodiment, the pressure relief branch 16 is connected to the air extraction passage 3, and the number of pipelines can be reduced without affecting the effective operation of each step of the system.

[0052] In specific operation, in step S15 of the first embodiment, the third solenoid valve 12 and the sixth solenoid valve 18 are opened simultaneously, and the purge passage 4 will cause the internal pressure of the sampling chamber to increase sharply. The simultaneous opening of the pressure relief branch 16 can play a role in reducing pressure. In addition, before step S16, the third solenoid valve 12 needs to be opened separately to relieve the pressure of the sampling chamber without introducing external gas. At this time, the pressure regulation accuracy is higher. Since the speed of material delivery is related to pressure, the speed of material delivery can be accurately controlled by accurately adjusting the internal pressure of the sampler 1.

[0053] Embodiment 3 Since the sampler 1 is a bent structure composed of two straight cavities, after the material enters the sampler 1 under high pressure, it accumulates into blocks in the sampler 1. If it only relies on the purge passage 4 for purging, the purge time cannot be too long due to the limitation of pressure requirements, so it may not be possible to blow the material in the other cavity. For this reason, the present embodiment makes the following improvements on the above embodiment: a purge bypass 21 is connected between the exhaust passage 3 and the purge passage 4, and a fifth solenoid valve 2 is arranged on the purge bypass 21. The connection point of the purge bypass 21 and the exhaust passage 3 is located at the outlet of the second solenoid valve 10, and the connection point of the purge bypass 21 and the purge passage 4 is located at the inlet of the third solenoid valve 12.

[0054] The purge bypass 21 and the purge passage 4 blow compressed gas into the sampling chamber from two different directions, achieving an up and down stirring effect in the sampling chamber, which helps to quickly break up the material.

[0055] In a further design, the exhaust passage 3 is connected to the first straight cavity 19, and the purge passage 4 is connected to the second straight cavity 20. The second straight cavity 20 is located at the lower part of the sampler 1, so the purge passage 4 blows into the sampler 1 from the lower part of the sampler 1, and the inlet of the exhaust passage 3 is the inlet of the purge bypass 21, so the purge bypass 21 and the purge passage 4 can spray the first straight cavity 19 and the second straight cavity 20 respectively. In addition, the fifth solenoid valve 2 is connected between the purge passage 4 and the exhaust passage 3, so that the application of the fifth solenoid valve 2 is realized by using part of the pipelines of the purge passage 4 and the exhaust passage 3. The pipeline structure of the entire system structure is very streamlined, and different working states can be achieved by adjusting the on and off of each solenoid valve. The whole process is fully automated, and no manual intervention or disassembly of the sampler 1 is required. The sampling process is efficient and pollution-free.

[0056] The sampling process of the vacuum negative pressure sampling system described in this embodiment includes the following steps: S21: System initialization, closing all valves, and setting the initial value of the pressure switch 11. In this embodiment, the initial setting value of the pressure switch 11 is -80 KPa.

[0057] S22: Vacuuming the sampling chamber: Open the first solenoid valve 8 and the second solenoid valve 10 until the pressure switch 11 reaches a specified value, and then close the first solenoid valve 8 and the second solenoid valve 10.

[0058] S23: Open the second valve 7 to feed, and close it after opening for 5 seconds.

[0059] S24: The first valve 5 is opened for the first time. When the vibration exciter 13 is installed, the vibration exciter 13 is also turned on at the same time. The vibration exciter 13 and the first valve 5 are closed after being opened for 10 seconds.

[0060] S25: Open the fifth solenoid valve 2. At this time, the gas enters the first straight cavity 19 from the interface of the exhaust passage 3 to blow away the material in the forward direction. After 2 seconds, the fifth solenoid valve 2 is closed. Then, the third solenoid valve 12 and the sixth solenoid valve 18 of the pressure relief branch 16 are opened. At this time, the gas enters the second straight cavity 20 from the interface of the purge passage 4 to blow away the material in the reverse direction. After 10 seconds, the third solenoid valve 12 and the sixth solenoid valve 18 of the pressure relief branch 16 are closed.

[0061] S26: Open the sixth solenoid valve 18 of the pressure relief branch 16 to continue to relieve pressure, and close the sixth solenoid valve 18 of the pressure relief branch 16 after 2 seconds.

[0062] S27: Open the first valve 5 to discharge the material.

[0063] S28: Close the first valve 5, open the third solenoid valve 12 and the second valve 7, and clean the sampling cavity.

[0064] In a preferred embodiment of the present invention, the first valve 5 and the second valve 7 are both ball valves.

[0065] Furthermore, the terms “first”, “second”, etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance.

[0066] In this specification, the schematic representation of the terms does not necessarily refer to the same embodiment. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in one or more embodiments.

[0067] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A vacuum negative pressure sampling system, characterized in that: It comprises a sampler (1) having a sampling cavity therein, and an exhaust passage (3) and a purge passage (4) connected to the sampler (1) and in communication with the sampling cavity, wherein the outlet of the sampler (1) is connected to a first valve (5), the inlet of the sampler (1) is connected to a silo (6), and a second valve (7) is arranged on the connecting pipeline; The air extraction passage (3) comprises an external air source, a first solenoid valve (8), a vacuum generator (9) and a second solenoid valve (10) which are connected in sequence, the second solenoid valve (10) being connected to the sampler (1) and a pressure switch (11) being arranged on the connecting pipeline between the two. The purge passage (4) comprises a third solenoid valve (12), one end of the third solenoid valve (12) being connected to an external gas source and the other end of the third solenoid valve (12) being connected to a sampler (1).

2. The vacuum negative pressure sampling system according to claim 1, characterized in that: An exciter (13) is installed on the outer surface of the sampler (1), and the exciter (13) is connected to an external air source via a fourth solenoid valve (14).

3. The vacuum negative pressure sampling system according to claim 1, characterized in that: The sampler (1) is connected to the side wall of the silo (6); the sampling chamber of the sampler (1) comprises a first straight chamber (19) and a second straight chamber (20) which are arranged obliquely; the pipeline where the first valve (5) is located is coaxially arranged with the second straight chamber (20); and the pipeline where the second valve (7) is located is coaxially arranged with the first straight chamber (19).

4. The vacuum negative pressure sampling system according to claim 3, characterized in that: A pressure relief branch (16) is provided on the connecting pipeline between the second solenoid valve (10) and the sampler (1).

5. The vacuum negative pressure sampling system according to claim 4, characterized in that: The pressure relief branch (16) comprises a silencer (17) and a sixth solenoid valve (18) which are connected to each other, and the sixth solenoid valve (18) is connected to the air extraction passage (3).

6. The vacuum negative pressure sampling system according to claim 1, characterized in that: A filter (15) is provided at one end of the exhaust passage (3) and the purge passage (4) close to the sampler (1).

7. The vacuum negative pressure sampling system according to claim 4, characterized in that: A purge bypass (21) is connected between the air extraction passage (3) and the purge passage (4), and a fifth solenoid valve (2) is arranged on the purge bypass (21). The connection point between the purge bypass (21) and the air extraction passage (3) is located at the outlet of the second solenoid valve (10), and the connection point between the purge bypass (21) and the purge passage (4) is located at the inlet of the third solenoid valve (12).

8. The vacuum negative pressure sampling system according to claim 7, characterized in that: The air extraction passage (3) is in communication with the first straight cavity (19), and the purge passage (4) is in communication with the second straight cavity (20).

9. A sampling method, characterized in that: The method adopts the vacuum negative pressure sampling system according to any one of claims 1 to 8, comprising the following steps: S11: System initialization, closing all valves and setting the initial value of the pressure switch (11); S12: evacuating the sampling chamber: opening the first solenoid valve (8) and the second solenoid valve (10) until the pressure switch (11) reaches a specified value, and then closing the first solenoid valve (8) and the second solenoid valve (10); S13: Open the second valve (7) to feed material, and close it after a few seconds; S14: opening the first valve (5) for the first time, and closing the first valve (5) after a certain amount of gas is released from the sampling chamber; S15: Open the third solenoid valve (12) to blow away the material, and close the third solenoid valve (12) after a few seconds; S16: Open the first valve (5) to discharge the material; S17: Close the first valve (5), open the third solenoid valve (12) and the second valve (7), and clean the sampling chamber.

10. A sampling method, characterized in that: The method adopts the vacuum negative pressure sampling system according to claim 7 or claim 8, and comprises the following steps: S21: System initialization, closing all valves and setting the initial value of the pressure switch (11); S22: evacuating the sampling chamber: opening the first solenoid valve (8) and the second solenoid valve (10) until the pressure switch (11) reaches a specified value, and then closing the first solenoid valve (8) and the second solenoid valve (10); S23: Open the second valve (7) to feed material, and close it after a few seconds; S24: opening the first valve (5) for the first time, and closing the first valve (5) after a certain amount of gas is released from the sampling chamber; S25: opening the fifth solenoid valve (2) to blow the material forward, closing the fifth solenoid valve (2) after a few seconds, opening the third solenoid valve (12) and the pressure relief branch (16) to blow the material backward, and closing the third solenoid valve (12) and the pressure relief branch (16) after a few seconds; S26: Open the pressure relief branch (16) to continue pressure relief, and close the pressure relief branch (16) after a few seconds; S27: Open the first valve (5) to discharge the material; S28: Close the first valve (5), open the third solenoid valve (12) and the second valve (7), and clean the sampling chamber.

Images