Method and system for monitoring material plug speed and length in dense-phase pneumatic conveying process

Abstract

The invention belongs to the technical field of material length measurement, and particularly relates to a method and system for monitoring the speed and length of a material plug in the dense-phase pneumatic conveying process. The method comprises the steps that S1, a discharge port of a feeding device is connected with a pipeline, and two material monitoring sensors are arranged at the two ends of the pipeline correspondingly; s2, an air source device is started, materials enter a pipeline through a feeding device, and material plug flowing is formed; s3, recording the time when the material plug enters and leaves the two material monitoring sensors; s4, calculating the length of the material plug; and S5, correcting the material plug length measured and calculated in the step S4. The material monitoring sensors are used for monitoring the material plug in the pipeline, the pressure transmitter is used for correcting the set interval of the material monitoring sensors, processing calculation is conducted according to the duration time and the interval time of feedback signals, and the speed and the length of the material plug passing through the pneumatic conveying pipeline are monitored in real time; and the blockage problem in the pipeline is predicted.

Description

Technical Field

[0001] The present invention belongs to the technical field of powder particle transportation, specifically to the technical field of equipment for measuring the length of materials during movement using fluid characteristics, and particularly to a method and system for monitoring the velocity and length of slugs in a dense-phase pneumatic transportation process. Background Art

[0002] Plug flow transportation, as a special transportation mode of dense-phase pneumatic transportation, is widely used in industries such as coal, chemical industry, grain, and building materials. Compared with dilute-phase pneumatic transportation, during the transportation process, materials accumulate in the pipeline to form slugs and flow in the form of material - gas - material. The size of the slug length directly affects the transportation stability and efficiency. An overly long slug will cause pipeline blockage and slug instability and fracture, which will further lead to problems such as pipeline wear and increased energy consumption of equipment operation. Therefore, measuring the slug length in a plug flow pneumatic transportation system is convenient for predicting the above situations.

[0003] CN115818260A discloses a plug flow generating device, which can automatically sense the pressure in the ash conveying pipeline and automatically open to supplement a large flow of compressed gas into the ash conveying pipeline when a blockage occurs in the ash conveying pipeline, so as to promote the ash material to flow forward and form a plug flow. This device can reduce the pipeline blockage problem and provide a method for forming a slug in a pneumatic transportation system. However, it fails to predict the specific length of the slug and the stability of the slug flow process.

[0004] Therefore, there is an urgent need to design a method and a dense-phase pneumatic transportation system for monitoring the slug velocity and length to solve the technical problem that there is currently no monitoring method for slug velocity and length, resulting in the inability to confirm whether the slug length is too short or too long.

[0005] It should be noted that the above information disclosed in this background art section is only used to understand the background art of the concept of this application. Therefore, it may include information that does not constitute prior art. Summary of the Invention

[0006] The embodiments of the present disclosure at least provide a method and a system for monitoring the velocity and length of slugs in a dense-phase pneumatic transportation process.

[0007] In a first aspect, the embodiments of the present disclosure also provide a method for monitoring the velocity and length of slugs in a dense-phase pneumatic transportation process. The method for monitoring the slug velocity and length includes the following steps:

[0008] Step S1, connect a pipeline to the discharge port of a feeding device, respectively set two material monitoring sensors at both ends of the pipeline, and electrically connect the two material monitoring sensors to a control module;

[0009] Step S2: Turn on the air source device. The material enters the pipeline through the feeding device. Driven by the airflow, the material gradually accumulates in the pipeline and flows in the pipeline in the form of a slug.

[0010] Step S3: The material monitoring sensors at the pipeline inlet respectively feedback the signals of the slug entering and leaving the monitoring range to the control module, and the control module respectively records the times t1 and t2.

[0011] The material monitoring sensors at the pipeline outlet respectively feedback the signals of the slug entering and leaving the monitoring range to the control module, and the control module respectively records the times t3 and t4.

[0012] Step S4: The control module calculates the speeds v1 and v2 of the slug passing through the two material monitoring sensors. The calculation formula is:

[0013]

[0014] where x is the distance between the material monitoring sensors.

[0015] The control module calculates the lengths l1 and l2 of the slug passing through the two material monitoring sensors. The calculation formula is:

[0016]

[0017] Step S5: Correct the slug length calculated in Step S4 through the formula:

[0018]

[0019] Calculate the length l of the passing slug.

[0020] In an alternative embodiment, before performing Step S5, judge the stability of the slug during the flow process through the formula:

[0021]

[0022] If the above formula holds, the stability of the slug during the flow process is good, and enter Step S5;

[0023] Otherwise, judge that the slug has become unstable and broken during the flow process, and the measurement result is invalid. Return to Step S2.

[0024] In an alternative embodiment, pressure transmitters are respectively arranged on one side of the same position of the two material monitoring sensors;

[0025] Before performing Step S4, the control module judges the validity of the slug length passing through the material monitoring sensors and the pressure transmitters; the two pressure transmitters record the pressure difference data ΔP in the pipeline at time t4 and output it to the control module;

[0026] The control module estimates and calculates the gas friction pressure loss between the two material monitoring sensors. The specific calculation formula is as follows:

[0027]

[0028] Among them, λ is the friction coefficient of air, L is the length of the pipeline, here the distance x between the two material sensors is taken, D is the diameter of the pipeline, ρ is the density of the conveying gas, and v is the velocity of the conveying gas;

[0029] If ΔP > kΔP A , it is determined that the measured data of the passing slug is invalid, and return to step S2;

[0030] If ΔP ≤ kΔP A , then enter step S4;

[0031] Among them, k ∈ [1.1, 1.2].

[0032] In a second aspect, the embodiments of the present disclosure further provide a system for monitoring the slug velocity and length in the dense-phase pneumatic conveying process, which is applied to execute the method for monitoring the slug velocity and length in the dense-phase pneumatic conveying process as described above. The system for monitoring the slug velocity and length in the dense-phase pneumatic conveying process includes:

[0033] A conveying pipe for conveying slugs;

[0034] Two material monitoring sensors, which are arranged at intervals on the conveying pipe, and the interval distance is x;

[0035] Two pressure transmitters, which are arranged on the conveying pipe and on one side of the same position of the two material monitoring sensors;

[0036] A control module, and both of the two material monitoring sensors and the pressure transmitters are electrically connected to the control module.

[0037] In an optional implementation manner, the distance between adjacent slugs is greater than the interval distance x between the two material monitoring sensors.

[0038] In an optional implementation manner, the interval distance x between the two material monitoring sensors is 3 to 5 times the diameter of the conveying pipe.

[0039] In an optional implementation manner, the length of the conveying pipe is greater than 20 times the diameter of the conveying pipe.

[0040] In an optional implementation manner, the two material monitoring sensors are capacitive proximity sensors.

[0041] In an alternative embodiment, the system for monitoring the velocity and length of slugs in a dense-phase pneumatic conveying process further includes a feeding mechanism and a gas source mechanism, both of which are connected to the conveying pipe.

[0042] In an alternative embodiment, a vortex flowmeter is provided on one side of the gas source mechanism, and the vortex flowmeter is electrically connected to the control module.

[0043] Beneficial effects: As can be seen from the above technical solutions, the present invention provides a method and a system for monitoring the velocity and length of slugs in a dense-phase pneumatic conveying process. By measuring the pressure difference of the slug through the material monitoring sensor with a pressure transmitter, the effectiveness of the slug length is judged. Material monitoring sensors are arranged at both ends of the conveying pipeline, and the real-time monitoring of the slug length can be quickly realized, which is convenient for predicting the blockage of the slug in the pipeline. At the same time, the slug lengths measured by the two material monitoring sensors are corrected and analyzed, the monitoring of the unstable fracture behavior during the slug flow process is realized, and the stability of the slug flow process is judged.

[0044] Other features and advantages of the present invention will be described in the following description, and in part will be obvious from the description, or understood by implementing the present invention. The objectives and other advantages of the present invention are realized and obtained by the structures specifically pointed out in the description, claims and drawings.

[0045] To make the above objectives, features and advantages of the present invention more obvious and understandable, the following specific preferred embodiments are given, and in conjunction with the accompanying drawings, the detailed description is as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0047] Figure 1 It is a schematic flow chart of a method for monitoring the velocity and length of slugs in a dense-phase pneumatic conveying process provided by an embodiment of the present disclosure;

[0048] Figure 2 It is a schematic structural diagram of a system for monitoring the velocity and length of slugs in a dense-phase pneumatic conveying process provided by an embodiment of the present disclosure;

[0049] Figure 3 It is a schematic structural diagram of the failure of air slug formation in a conveying pipe provided by an embodiment of the present disclosure.

[0050] In the figure:

[0051] 1. Feeding mechanism; 2. Three-way valve; 3. Vortex flowmeter; 4. Delivery pipe;

[0052] 5. Plug; 6-1. First material monitoring sensor; 6-2. Second material monitoring sensor; 7-1. First pressure transmitter; 7-2. Second pressure transmitter; 8. Control module; 9. Computer. Specific embodiments

[0053] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0054] Through research, it is found that the plug conveying technology utilizes materials to accumulate into plugs in the conveying pipeline, with air filling between the plugs, forming a form of "one section of material, one section of air", and moving forward relying on the static pressure difference at both ends of the plug. During the conveying process, the length of the plug directly affects the stability and efficiency of the conveying. The existing dense-phase plug flow pneumatic conveying system has almost no monitoring method for the length of the plug, and there is no definite judgment method for the stability of the plug conveying process. There are problems such as too long plug length and instability and fracture of the plug during the conveying process. A too short plug length will lead to a decrease in conveying capacity, while a too long plug may cause problems such as pipeline blockage and increased wear.

[0055] Regarding the defects existing in the above solutions, they are all the results obtained by the inventors through practice and careful research. Therefore, the discovery process of the above problems and the solutions proposed by the present disclosure for the above problems in the following text should be the contributions made by the inventors to the present disclosure during the process of the present disclosure.

[0056] The following will describe in detail some embodiments of the present invention with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other. In addition, in the drawings, in order to effectively describe the technical content, the thickness of the components can be exaggerated or reduced.

[0057] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0058] Based on the above research, the embodiments of the present disclosure provide a system for monitoring the speed and length of plugs during the dense-phase pneumatic conveying process. Refer to Figure 2, which includes: a feeding mechanism 1, a gas source mechanism, a conveying pipe 4, two material monitoring sensors, two pressure transmitters, and a control module 8. The feeding mechanism 1 is barrel-shaped and is used to hold the material to be conveyed. The discharging end of the feeding mechanism 1 is connected to the conveying pipe 4. In an optional embodiment, the feeding mechanism 1 is a vertical structure, and the discharging end of the feeding mechanism 1 is located at the bottom so that the material enters the conveying pipe 4 by gravity. The gas source mechanism is also connected to the conveying pipe 4 to continuously supply air into the conveying pipe 4. In an optional embodiment, the feeding mechanism 1, the gas source mechanism, and the conveying pipe 4 are connected by a three-way valve 2, and the other end of the conveying pipe 4 can be connected to a separation and dust removal device. When the gas source mechanism continuously supplies air into the conveying pipe 4, the feeding mechanism 1 feeds the material into the conveying pipe 4. Under the action of the wind force conveyed by the gas source mechanism, a plug 5 is formed in the conveying pipe 4 and is conveyed along the conveying pipe 4 to the separation and dust removal device through the static pressure difference.

[0059] Referring to Figure 1 , in some embodiments, the conveying pipe 4 is horizontally arranged, and a plurality of bolt interfaces are respectively opened at the same height at both ends of the conveying pipe 4 for installing the material monitoring sensors and the pressure transmitters 7, that is, the two material monitoring sensors are installed at intervals, and both of the two pressure transmitters 7 are installed on one side of the same position of the material monitoring sensors, that is, the interval distances between the two material monitoring sensors and the two pressure transmitters are both x. The two material monitoring sensors are respectively denoted as the first material monitoring sensor 6-1 and the second material monitoring sensor 6-2 along the conveying direction of the plug 5, and the two pressure transmitters are respectively denoted as the first pressure transmitter 7-1 and the second pressure transmitter 7-2 along the conveying direction of the plug 5. The first material monitoring sensor 6-1 and the second material monitoring sensor 6-2 are both electrically connected to the control module 8, and the first pressure transmitter 7-1 and the second pressure transmitter 7-2 are also both electrically connected to the control module 8. The first material monitoring sensor 6-1 and the second material monitoring sensor 6-2 can monitor the passing of the plug 5 in the pipeline in real time and output continuous feedback signals to the control module 8. The control module 8 respectively records the time when the plug 5 enters and leaves the first material monitoring sensor 6-1 and the second material monitoring sensor 6-2 according to the feedback signals, and at the same time records the pressure difference data ΔP between the first pressure transmitter 7-1 and the second pressure transmitter 7-2 at the moment when the plug 5 leaves the second material monitoring sensor 6-2, that is, the time when the plug 5 enters the monitoring range of the first material monitoring sensor 6 is denoted as t1, the time when the plug 5 leaves the monitoring range of the first material monitoring sensor 6 is denoted as t2, the time when the plug 5 enters the monitoring range of the second material monitoring sensor 6 is denoted as t3, and the time when the plug 5 leaves the monitoring range of the second material monitoring sensor 6 is denoted as t4.

[0060] In at least one embodiment, the length of the conveying pipe 4 is greater than 20 times the diameter of the conveying pipe 4. The interval distance x between the two material monitoring sensors 6-1 and 6-2 is 3 to 5 times the diameter of the conveying pipe 4. Refer toFigure 3 When the interval distance between the two material monitoring sensors is less than 3 times the diameter of the conveying pipe 4, no air plug is formed between two adjacent material plugs 5 under this condition, resulting in errors in the measurement results.

[0061] Specifically, denote the diameter of the conveying pipe 4 as D, then the length of the conveying pipe 4 is greater than 20D; denote the distance between the first material monitoring sensor 6-1 and the second material monitoring sensor 6-2 as x, then the value range of x is 3D - 5D.

[0062] In some embodiments, the conveying pipe 4 is made of a visible material, such as a material with a transparent effect, for the convenience of personnel observation and recording.

[0063] After the control module 8 receives the signals fed back by the first material monitoring sensor 6-1 and the second material monitoring sensor 6-2, it calculates and determines whether the material plug 5 is stable during the conveying process according to the formula, and further calculates the length of the material plug 5 after determining that the flow state of the material plug 5 is stable. The specific calculation method will be further described below.

[0064] Refer to Figure 2 In at least one embodiment, the air source mechanism has a vortex flowmeter 3, and the vortex flowmeter 3 is electrically connected to the control module 8. The vortex flowmeter 3 can monitor the flow rate of the negative pressure gas in the conveying pipe 4 and feed it back to the control module 8.

[0065] Refer to Figure 2 In some embodiments, the control module 8 is electrically connected to the computer 9, so that the computer 9 can display the length data and stability situation of the material plug 5 output to the computer 9 after being calculated by the control module 8.

[0066] The embodiment of the present disclosure also provides a method for monitoring the speed and length of the material plug in the dense-phase pneumatic conveying process. The dense-phase pneumatic conveying system shown above is applied to execute this method, and it includes the following steps: Step S1, the outlet conveying pipe 4 of the feeding mechanism 1, the first material monitoring sensor 6-1 and the second material monitoring sensor 6-2 are respectively arranged at both ends of the conveying pipe 4 and are electrically connected to the control module 8;

[0067] Step S2, turn on the air source mechanism, the material enters the conveying pipe 4 through the feeding mechanism 1, and the material gradually accumulates in the conveying pipe 4 under the drive of the air flow and flows in the conveying pipe 4 in the form of a material plug 5;

[0068] Step S3, the first material monitoring sensor 6-1 respectively feeds back the signals of the material plug 5 entering and leaving the monitoring range to the control module 8, and the control module 8 respectively records the moments t1 and t2; the second material monitoring sensor 6-2 respectively feeds back the signals of the material plug 5 entering and leaving the monitoring range to the control module 8, and the control module 8 respectively records the moments t3 and t4;

[0069] Step S4. The control module 8 measures the speed v1 of the material plug 5 passing through the first material monitoring sensor 6-1 and the speed v2 of passing through the second material monitoring sensor 6-2. The calculation formula is:

[0070]

[0071] where x is the interval distance between the material monitoring sensors;

[0072] The control module 8 measures the lengths l1 and l2 of the material plug 5 passing through the two material monitoring sensors. The calculation formula is:

[0073]

[0074] Step S5. Correct the length of the material plug 5 measured in step S4 through the formula:

[0075]

[0076] Calculate the length l of the material plug 5 passing through.

[0077] In at least one embodiment, before executing step S5, judge the stability of the material plug 5 during the flow process through the formula:

[0078]

[0079] If the above formula holds, the stability of the material plug 5 during the flow process is good, and step S5 is entered;

[0080] Otherwise, it is judged that the material plug 5 has become unstable and broken during the flow process, the measurement result is invalid, and step S2 is returned, that is, measure the length of the next section of the material plug 5.

[0081] Before executing step S4, the control module 8 judges the validity of the length of the material plug 5 passing through the material monitoring sensor and the pressure transmitter; the two pressure transmitters record the pressure difference data ΔP in the pipeline at time t4 and output it to the control module 8;

[0082] The control module 8 pre-estimates and calculates the gas friction pressure loss between the two material monitoring sensors. The specific calculation formula is as follows:

[0083]

[0084] where λ is the friction coefficient of air, L is the length of the pipeline, here take the distance x between the two material sensors, D is the diameter of the pipeline, ρ is the density of the conveying gas, and v is the speed of the conveying gas;

[0085] If ΔP > kΔP A , it is judged that the measurement data of the passed material plug 5 is invalid, and step S2 is returned;

[0086] If ΔP ≤ kΔP A , then proceed to step S4;

[0087] where k ∈ [1.1, 1.2].

[0088] On the other hand, when the above-mentioned plug 5 becomes unstable and breaks, or when the situation of ΔP > kΔP A occurs continuously, it is necessary to consider factors such as whether there are defects in the system design, whether the system assembly is in place, and whether there are faults in the relevant equipment. Therefore, when necessary, the machine should be stopped for inspection and maintenance to ensure continuous measurement under stable system conditions, so as to obtain the accurate length of the plug 5.

[0089] In addition, it should be noted that the installation of two material monitoring sensors and a pressure transmitter on the conveying pipe 4 mentioned above is only a setting in some embodiments. In other embodiments, the number of material monitoring sensors and pressure transmitters can be greater than two, that is, three or more. In this case, adjacent two material monitoring sensors and pressure transmitters can still form the monitoring system mentioned above. Therefore, the number of material monitoring sensors and pressure transmitters cannot be regarded as a limitation to the inventive concept. Technical solutions that implement the same or essentially the same monitoring method as the present invention through material monitoring sensors and pressure transmitters and achieve the effect of judging the conveying state of the plug 5 and calculating the length of the plug 5 are all within the protection scope of the present invention.

[0090] In at least one embodiment, the specific measurement process of the length of the plug 5 passing through the conveying pipe 4 by the control module 8 is as follows:

[0091] Step A11, set the set distance between the first material monitoring sensor 6-1 and the second material monitoring sensor 6-2 as x and assign a value;

[0092] Step A12, number the plugs 5 passing through the conveying pipe 4, and set the number of the plug 5 as n;

[0093] Step A21, initialize n = 1;

[0094] Step A22, when the nth plug 5 passes through the material monitoring sensor and the pressure transmitter, the corresponding material monitoring sensor and pressure transmitter feedback signals and output them to the control module 8;

[0095] Step A23, the control module 8 records the time t n1 , t n2 when the plug 5 passes through the first material monitoring sensor 6 n3 , t n4 , and the time t n4The pressure difference value ΔP measured by the first pressure transmitter 7-1 and the second pressure transmitter 7-2 n ;

[0096] Step A31, the control module performs an estimated calculation on the gas friction pressure loss ΔP detected by the two material monitoring sensors. The specific calculation formula is as follows: A For the following:

[0097] Step A32, the control module judges the pressure difference value ΔP n and the estimated ΔP A . If ΔP n > kΔP A , it is judged that the measured data of the plug is invalid, and step A42 is entered. If ΔP n ≤ kΔP A , step A33 for calculating the plug length is entered;

[0098] Step A33, set the length of the nth plug 5 measured by the first material monitoring sensor 6-1 to l n1 . The specific calculation formula is:

[0099]

[0100] Set the length of the nth plug 5 measured by the second material monitoring sensor 6-2 to l n2 . The specific calculation formula is:

[0101]

[0102] Step A34, verify the stability of the flow process of the plug 5, and judge whether there is an unstable fracture behavior in the flow process. The specific calculation formula is as follows:

[0103]

[0104] When the condition is met, it is proved that the data sizes measured by the first material monitoring sensor 6-1 and the second material monitoring sensor 6-2 are close. The control module 8 outputs the length l of the nth plug 5 n to the computer 9 and enters step A41. The specific calculation formula is as follows:

[0105] When the condition is not met, the plug 5 has a fracture behavior during the flow from the first material monitoring sensor 6-1 to the second material monitoring sensor 6-2, the length of the plug 5 is shortened, and unstable phenomena occur during the conveying process. The control module 8 outputs that the nth plug 5 has an unstable fracture to the computer 9 and enters step A42.

[0106] Step A41, output the length l of the nth plug 5n , proceed to step A43;

[0107] Step A42, output that the measurement data of the nth material plug 5 is invalid, and proceed to step A43;

[0108] Step A43, n = n + 1, return to step A22, and measure the length of the next material plug 5 passing through;

[0109] Step A44, end.

[0110] In several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For another example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Taking the above ideal embodiments of the present invention as inspiration, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for monitoring the velocity and length of a slug in a dense-phase pneumatic conveying process, characterized in that, The method for monitoring the speed and length of the material plug includes the following steps: Step S1: Connect a pipeline to the discharge port of the feeding device, respectively set two material monitoring sensors at both ends of the pipeline, and electrically connect the two material monitoring sensors to the control module (8); Step S2: Turn on the air source device, and the material enters the pipeline through the feeding device. The material gradually accumulates in the pipeline under the drive of the air flow and flows in the pipeline in the form of a material plug (5); Step S3: The material monitoring sensor at the pipeline inlet respectively feeds back the signals of the material plug (5) entering and leaving the monitoring range to the control module (8), and the control module (8) respectively records the times t1 and t2; The material monitoring sensor at the pipeline outlet respectively feeds back the signals of the material plug (5) entering and leaving the monitoring range to the control module (8), and the control module (8) respectively records the times t3 and t4; Step S4: The control module (8) calculates the speeds v1 and v2 of the material plug (5) passing through the two material monitoring sensors. The calculation formula is: where x is the interval distance between the material monitoring sensors; The control module (8) calculates the lengths l1 and l2 of the material plug (5) passing through the two material monitoring sensors. The calculation formula is: Step S5: Correct the length of the material plug (5) calculated in Step S4 through the formula: Calculate the length l of the passing material plug (5).

2. The method for monitoring the speed and length of the material plug in the dense-phase pneumatic conveying process according to claim 1, characterized in that Before executing Step S5, judge the stability of the material plug (5) during the flowing process through the formula: If the above formula holds, the stability of the material plug (5) during the flowing process is good, and enter Step S5; Otherwise, judge that the material plug (5) has become unstable and broken during the flowing process, and the measurement result is invalid, and return to Step S2.

3. The method for monitoring the speed and length of the material plug in the dense-phase pneumatic conveying process according to claim 1, characterized in that Pressure transmitters are respectively arranged on one side of the same position of the two material monitoring sensors; Before executing Step S4, the control module (8) judges the validity of the length of the material plug (5) passing through the material monitoring sensors and the pressure transmitters; the two pressure transmitters record the pressure difference data ΔP in the pipeline at time t4 and output it to the control module (8); the control module (8) estimates and calculates the gas friction pressure loss between the two material monitoring sensors. The specific calculation formula is as follows: where λ is the friction coefficient of air, L is the length of the pipeline, here take the distance x between the two material sensors, D is the diameter of the pipeline, ρ is the density of the conveying gas, and v is the speed of the conveying gas; If ΔP > kΔP A , it is determined that the measurement data of the passed material plug (5) is invalid, and the process returns to step S2; If ΔP ≤ kΔP A , then proceed to step S4; where k ∈ [1.1, 1.2].

4. A system for monitoring the velocity and length of a slug in a dense-phase pneumatic conveying process, characterized in that, Applied to execute the method for monitoring the speed and length of the material plug in the dense-phase pneumatic conveying process according to any one of claims 1-3, the system for monitoring the speed and length of the material plug in the dense-phase pneumatic conveying process includes: A conveying pipe (4) for conveying the material plug (5); Two material monitoring sensors, which are arranged at intervals on the conveying pipe (4), and the interval distance is x; Two pressure transmitters, which are arranged on the conveying pipe (4) and on one side of the same position of the two material monitoring sensors; A control module (8), both of the material monitoring sensors and the pressure transmitter are electrically connected to the control module (8).

5. The system for monitoring the slug velocity and length in the dense-phase pneumatic conveying process according to claim 4, characterized in that The distance between adjacent slugs (5) is greater than the spacing distance x between the two material monitoring sensors.

6. The system for monitoring the slug velocity and length in the dense-phase pneumatic conveying process according to claim 4, characterized in that The spacing distance x between the two material monitoring sensors is 3 to 5 times the diameter of the conveying pipe (4).

7. The system for monitoring the slug velocity and length in the dense-phase pneumatic conveying process according to claim 4, characterized in that The length of the conveying pipe (4) is greater than 20 times the diameter of the conveying pipe (4).

8. The system for monitoring the slug velocity and length in the dense-phase pneumatic conveying process according to claim 4, characterized in that The two material monitoring sensors are capacitive proximity sensors.

9. The system for monitoring the slug velocity and length in the dense-phase pneumatic conveying process according to claim 4, characterized in that The system for monitoring the slug velocity and length in the dense-phase pneumatic conveying process further includes a feeding mechanism (1) and a gas source mechanism, and the feeding mechanism (1) and the gas source mechanism are both connected to the conveying pipe (4).

10. The system for monitoring the slug velocity and length in the dense-phase pneumatic conveying process according to claim 8, characterized in that One side of the gas source mechanism is provided with a vortex flowmeter (3), and the vortex flowmeter (3) is electrically connected to the control module (8).

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