Viscosity online detection device and method on high-viscosity fluid conveying pipeline

Abstract

The invention discloses an online viscosity detection device and method for a high-viscosity fluid conveying pipeline. The online viscosity detection device comprises a detection mechanism and a mass measurement mechanism, the detection mechanism is communicated with a conveying pipeline of the high-viscosity fluid, and a cleaning device and a nitrogen input device are connected to the detection mechanism; the detection mechanism comprises a detection cavity, a heat preservation device and a plurality of detectors; the mass measuring mechanism is located below the detection mechanism, the mass measuring mechanism comprises a mass balance, a cooling box and a cutting device, inert liquid is placed in the cooling box, and the bottom of the detection cavity is immersed in the inert liquid. By measuring and recording the pressure difference and temperature of the fluid in the pipeline, the flow is calculated according to the mass of the polymer cut by the cutter in unit time, and the viscosity of the fluid is calculated; nitrogen purging and inert liquid cooling are adopted, the stability and accuracy of the high-viscosity polymer in the testing process are ensured, and the device and the method are suitable for online viscosity measurement and sampling in industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of sampling for conveying pipelines, and particularly to an on-line viscosity detection device and method for a high-viscosity fluid conveying pipeline. Background Art

[0002] On-line sampling devices play a crucial role in modern industrial processes and are widely used in the chemical industry. Traditional on-line sampling devices are usually used to extract fluid samples from pipelines or reactors for off-line analysis. Such devices can effectively avoid production line shutdowns and enable continuous sampling and rapid analysis. However, most existing on-line sampling devices are limited to a single sampling function and cannot perform real-time detection of key physical parameters of fluids during sampling. This makes it necessary to rely on additional instruments to measure important parameters such as pressure, flow rate, or viscosity during the production process under certain complex process conditions, increasing process complexity and costs.

[0003] Especially when dealing with high-viscosity fluids, the limitations of existing samplers are more obvious. High-viscosity fluids such as polymer melts, resins, colloids, etc. are widely used in the chemical industry. Such fluids have high viscosity, high flow resistance, and are often accompanied by significant temperature and pressure changes. Traditional on-line sampling devices usually require a large driving force to achieve smooth sampling when facing high-viscosity fluids, and adverse reactions such as oxidation and solidification are likely to occur during the sample cooling process, affecting the authenticity of the sample.

[0004] Viscosity, as an important rheological parameter of high-viscosity fluids, has a direct impact on the flow behavior of fluids in pipelines. In high-viscosity processes, real-time monitoring of viscosity can help optimize the production process and prevent blockages and instabilities of fluids during transportation. However, existing on-line viscosity testing devices are usually independent of the sampling system, require additional installation and complex calibration and debugging, and cannot be directly integrated with on-line sampling devices. This separate testing method not only increases operation complexity but also has detection time lags and measurement errors.

[0005] Chinese Patent CN220552657U discloses a sampling device for high-viscosity liquid pipelines, which can place the sampling inlet of the sampling pipe in the central flow area of the pipeline lumen for sampling, effectively avoiding the problems of inconsistent sample index parameters and inaccurate analysis results caused by sampling in the outer ring flow area close to the pipe wall in the prior art. In addition, the device is equipped with a lifting drive device to achieve automatic switching of the sampling pipe between the sampling position and the liquid avoidance position, improving the convenience and efficiency of sampling. At the same time, the drainage port provided in the device can drain the high-viscosity liquid in the outer ring flow area

[0006] Preferably, the specific method in step S9 is to open the nitrogen valve to purge the detection chamber, blow out the residual solvent, close the nitrogen valve 3 after the purging is completed, and then close all valves to end the sampling.

[0007] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0008] 1. By integrating the on-line sampling and viscosity detection system for high-viscosity fluids, the present invention purges oxygen by introducing nitrogen into the cavity before sampling, preventing the polymer from flowing into the system and being oxidized under high-temperature conditions, thus solving the deficiency of the traditional exposure conditions of the existing detection device that easily leads to the oxidation and degradation of high-temperature polymers.

[0009] 2. After the high-viscosity fluid fills the detection tube and flows stably, the fluid temperature and pressure difference are measured by the upper and lower pressure sensors and the temperature sensor. The temperature sensor is installed in the middle of the cavity to monitor the fluid temperature in real time; the pressure sensors are installed in the upper and lower parts of the cavity respectively to record the pressure changes and ensure the accuracy of the pressure drop calculation.

[0010] 3. The pipe outlet of the system in this application is immersed in the inert liquid, and the inert liquid cooling tank is placed on the balance. When the high-viscosity fluid flows out of the pipe, it immediately enters the inert liquid for cooling, thus forming an oxygen-free environment to prevent the polymer from being oxidized; the cutter controlled by the motor cuts the cooled polymer spline at a set frequency, and the polymer spline freely falls into the inert liquid, and is weighed and recorded by the balance. The increased mass per unit time is the mass flow rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] 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, some of the following drawings are 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.

[0012] Figure 1 is a schematic structural diagram of the detection device in Embodiment 1;

[0013] Figure 2 is a schematic structural diagram of the base in Embodiment 1.

[0014] Among them, 1 - buffer valve; 2 - buffer zone; 3 - nitrogen valve; 4 - washing solvent valve; 5 - injection valve; 6 - upper pressure detection mechanism; 7 - detection chamber; 8 - insulation jacket; 9 - temperature detection mechanism; 10 - lower pressure detection mechanism; 11 - nitrogen input device; 12 - positive displacement pump; 13 - washing solvent; 14 - outlet valve; 15 - base; 16 - drive mechanism; 17 - cutter; 18 - cooling tank; 19 - mass balance; 20 - fluid chamber; 21 - tank body.

[0015] Drain it to the outside of the pipeline, which promotes the homogenization of the liquid index parameters in the pipeline and improves the accuracy of the sampling analysis results and production efficiency. However, this method does not consider the situation that polymers are easily oxidized at high temperatures. Sampling directly exposed to the atmosphere may cause the taken polymers to oxidize, denature or degrade, and there is no cooling system, making it difficult to sample. Therefore, it has defects.

[0016] Chinese Patent CN114689466A discloses an on-line viscosity detection device for polymer solutions. Its innovation lies in integrating a stirring component and a temperature control component, which can stir the polymer solution in real time during the detection process and accurately control the temperature in the detection box at the same time to ensure the accuracy and stability of the viscosity detection. The stirring component drives the stirring rod to rotate through a stirring motor, effectively preventing the precipitation or stratification of the polymer solution and improving the reliability of the detection data. The temperature control component uses electric heating tubes and semiconductor refrigeration chips, and cooperates with a fan to blow cold air or hot air in the detection box to achieve precise control of the detection environment and avoid the influence of environmental temperature changes on the viscosity of the polymer solution. These innovative designs significantly improve the practicability and accuracy of the on-line viscosity detection of polymer solutions. However, the device has a complex structure, limited applicability, and requires additional wiring to be connected to the polymer pipeline, making the operation cumbersome.

[0017] In response to this, the present invention relates to an on-line viscosity detection device and method for high-viscosity fluid conveying pipelines, which make up for the technical defect that existing samplers do not have the function of viscosity detection, and solve the disadvantages and deficiencies that polymers are easily oxidized during sampling under high-temperature conditions and traditional viscosity detection elements have complex structures and high costs. Obviously, it has positive practical significance. Summary of the Invention

[0018] The invention object of the present invention is an on-line viscosity detection device and method for high-viscosity fluid conveying pipelines, which integrates an on-line sampling and viscosity detection system for high-viscosity fluids and solves the deficiency that traditional high-temperature polymers are easily oxidized and degraded under exposed conditions.

[0019] To achieve the above invention object, the technical solution adopted by the present invention is: an on-line viscosity detection device for high-viscosity fluid conveying pipelines, connected to the conveying pipeline of high-viscosity fluids, comprising: a detection mechanism and a mass measurement mechanism;

[0020] The detection mechanism is connected to the conveying pipeline of the highly viscous fluid, and a cleaning device and a nitrogen input device are connected to the detection mechanism; the detection mechanism includes a detection chamber, a heat preservation device, and a plurality of detectors, the heat preservation device is located outside the detection chamber, and a plurality of the detectors are all located in the detection chamber;

[0021] The mass measurement mechanism is located below the detection mechanism, and the mass measurement mechanism includes a mass balance, a cooling box placed above the mass balance, and a cutting device. An inert liquid is placed in the cooling box, and the bottom of the detection chamber is immersed in the inert liquid.

[0022] Preferably, the detection mechanism further includes a buffer zone, the buffer zone is located between the detection chamber and the conveying pipeline of the highly viscous fluid and communicates with the detection chamber and the conveying pipeline of the highly viscous fluid, and both the cleaning device and the nitrogen input device are communicated with the buffer zone.

[0023] Preferably, a buffer valve is provided between the buffer zone and the conveying pipeline of the highly viscous fluid, a sampling valve is provided between the buffer zone and the detection chamber, a nitrogen valve is provided between the buffer zone and the nitrogen input device, and a washing solvent valve is provided between the buffer zone and the cleaning device.

[0024] Preferably, the detector includes an upper pressure detection mechanism located at the top of the detection chamber, a temperature detection mechanism located in the middle of the detection chamber, and a lower pressure detection mechanism located at the bottom of the detection chamber.

[0025] Preferably, the detection chamber is the internal cavity of the detection pipeline connected to the buffer zone, the heat preservation device is a heat preservation jacket, and the heat preservation jacket is sleeved on the outside of the detection pipeline.

[0026] Preferably, the cleaning device includes a volume pump and a washing solvent, the volume pump is connected to the washing solvent and the buffer zone, and the washing solvent is input into the buffer zone through the volume pump.

[0027] Preferably, the cutting device includes a cutter, a base, and a driving mechanism, the base is arranged at the bottom of the detection chamber, and the driving mechanism is connected to the cutter.

[0028] Preferably, a groove for cooperating with the cutter for cutting is arranged on the base, a fluid chamber for the highly viscous fluid to pass through is arranged in the base, the fluid chamber is communicated with the detection chamber, and an outlet valve is arranged between the detection chamber and the base.

[0029] Preferably, the groove on the base is immersed in the inert liquid.

[0030] Preferably, liquid silicone oil or fluorinated liquid is used as the cooling medium in the cooling box, and a circulating cooling device is equipped to keep the liquid temperature constant at 20-30°C.

[0031] Preferably, the cutting knife is controlled by a driving mechanism, whose frequency is adjusted by a PLC system. The cutting knife is made of wear-resistant alloy steel, and the cutting knife and the base are coated with an anti-sticking coating, and the anti-sticking coating includes a fluorine coating.

[0032] This application also claims to protect an on-line viscosity detection method for a high-viscosity fluid conveying pipeline, using the on-line viscosity detection device for a high-viscosity fluid conveying pipeline described above, including the following steps:

[0033] S1. After the nitrogen input device fills the detection chamber with sufficient nitrogen to evacuate all the air in the inner cavity of the device, the nitrogen input device is closed;

[0034] S2. Start the cutting device for timed shearing;

[0035] S3. Introduce the high-viscosity fluid in the conveying pipeline into the detection chamber, and let the high-viscosity fluid flow out after filling the detection chamber;

[0036] S4. The flowing high-viscosity fluid is cut into sections by the cutting device after being cooled by an inert liquid;

[0037] S5. Observe the outlet sample strip. After the cutting is stable, start timing, and zero the mass balance. At this time, observe the detector reading and record it. After the timing reaches the requirement, read the mass balance reading;

[0038] S6. Calculate the viscosity of the high-viscosity fluid through a mathematical model formula;

[0039] S7. After the sampling measurement is completed, first close the cutting device, then close the sample injection, and then discharge part of the inert liquid in the box;

[0040] S8. Open the cleaning device to wash the detection chamber; after the washing is completed, close the cleaning device and let it stand;

[0041] S9. After standing, open the nitrogen input device to purge the detection chamber to blow out the residual solvent. After the purging is completed, close the nitrogen input device to end the sampling.

[0042] Preferably, all valves in the detection device are in the closed state initially before the detection starts.

[0043] Preferably, the specific method of step S1 is to open the outlet valve, the sample injection valve, and the nitrogen valve in sequence, fill the inner cavity of the device with sufficient nitrogen to evacuate all the air, and then close the nitrogen valve.

[0044] Preferably, the specific method of step S2 is to start the driving mechanism to drive the cutting knife for timed shearing.

[0045] Preferably, the specific method of step S3 is to open the buffer valve, introduce the high-viscosity fluid from the conveying pipeline into the buffer area and the detection chamber, and start to flow out through the sample outlet after the fluid fills the detection chamber.

[0046] Preferably, the specific method of step S4 is that the outflowing highly viscous fluid is cut into segments by a cutter after being cooled by an inert liquid.

[0047] Preferably, the specific method of step S5 is to observe the outlet sample strip. After the cutting into segments is stable, start timing and zero the mass balance. At this time, observe the readings of the temperature detection mechanism, the upper pressure detection mechanism and the lower pressure detection mechanism and record them; after the timing reaches the requirement, read the reading of the mass balance to obtain the pressure difference and the mass flow rate.

[0048] Preferably, the mathematical model formula in step S6 is

[0049] where: μ is the polymer viscosity; ΔP is the pressure drop; L is the length of the detection section; r is the radius of the detection section; Q is the polymer mass flow rate.

[0050] Preferably, the specific method of step S7 is to first close the driving mechanism, then close the buffer valve, and then discharge part of the inert liquid in the tank.

[0051] Preferably, the specific method of step S8 is to open the washing solvent valve, then open the volumetric pump, introduce the washing solvent to wash the detection cavity. After the washing is completed, close the volumetric pump and the washing solvent valve and let it stand for a period of time. Specific embodiments

[0052] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0053] Embodiment 1

[0054] As Figures 1 to 2 shown, an on-line viscosity detection device on a highly viscous fluid conveying pipeline, which is connected to the highly viscous fluid conveying pipeline, includes: a detection mechanism and a mass measurement mechanism;

[0055] The detection mechanism is communicated with the highly viscous fluid conveying pipeline, and a cleaning device and a nitrogen input device 11 are connected to the detection mechanism; the detection mechanism includes a detection cavity 7, a heat preservation device and a plurality of detectors, the heat preservation device is located outside the detection cavity, and a plurality of the detectors are all located in the detection cavity;

[0056] The mass measurement mechanism is located below the detection mechanism, and the mass measurement mechanism includes a mass balance 19, a cooling box 18 placed above the mass balance and a cutting device. An inert liquid is placed in the cooling box, and the bottom of the detection cavity is immersed in the inert liquid.

[0057] Preferably, the detection mechanism further includes a buffer zone 2, which is located between the detection chamber and the conveying pipeline of the highly viscous fluid and communicates with the detection chamber and the conveying pipeline of the highly viscous fluid. Both the cleaning device and the nitrogen input device are communicated with the buffer zone.

[0058] Preferably, a buffer valve 1 is provided between the buffer zone and the conveying pipeline of the highly viscous fluid, a sampling valve 5 is provided between the buffer zone and the detection chamber, a nitrogen valve 3 is provided between the buffer zone and the nitrogen input device, and a washing solvent valve 4 is provided between the buffer zone and the cleaning device.

[0059] Preferably, the detector includes an upper pressure detection mechanism 6 located at the top of the detection chamber, a temperature detection mechanism 9 located in the middle of the detection chamber, and a lower pressure detection mechanism 10 located at the bottom of the detection chamber.

[0060] Preferably, the detection chamber is the internal cavity of the detection pipeline connected to the buffer zone, and the heat preservation device is a heat preservation jacket 8, which is sleeved on the outside of the detection pipeline.

[0061] Preferably, the cleaning device includes a positive displacement pump 12 and a washing solvent 13. The positive displacement pump is connected to the washing solvent and the buffer zone, and the washing solvent is input into the buffer zone through the positive displacement pump.

[0062] Preferably, the cutting device includes a cutting knife 17, a base 15 and a driving mechanism 16. The base is arranged at the bottom of the detection chamber, and the driving mechanism is connected to the cutting knife.

[0063] Preferably, a groove 21 for cooperating with the cutting knife for cutting is provided on the base, a fluid chamber 20 for the highly viscous fluid to pass through is provided inside the base, the fluid chamber is communicated with the detection chamber, and an outlet valve 14 is provided between the detection chamber and the base.

[0064] Preferably, the groove on the base is immersed in the inert liquid.

[0065] Preferably, liquid silicone oil or fluorinated liquid is used as the cooling medium in the cooling tank, and a circulating cooling device is equipped to keep the liquid temperature constant at 20 - 30 °C.

[0066] Preferably, the cutting knife is controlled by the driving mechanism, its frequency is adjusted by the PLC system, the material of the cutting knife is wear-resistant alloy steel, and the cutting knife and the base are coated with an anti-sticking coating, and the anti-sticking coating includes a fluorine coating.

[0067] Example 2

[0068] This embodiment is based on the above-mentioned Embodiment 1, and the same parts as those in the above-mentioned Embodiment 1 will not be described in detail.

[0069] This embodiment relates to an on-line viscosity detection method for a high-viscosity fluid conveying pipeline. Using the on-line viscosity detection device for a high-viscosity fluid conveying pipeline described above, it includes the following steps:

[0070] S1. After the nitrogen input device injects sufficient nitrogen into the detection cavity to evacuate all the air in the device cavity, the nitrogen input device is closed;

[0071] S2. The cutting device is started for timed shearing;

[0072] S3. The high-viscosity fluid in the conveying pipeline is introduced into the detection cavity. After the high-viscosity fluid fills the detection cavity, it flows out;

[0073] S4. The flowing high-viscosity fluid is cut into segments by the cutting device after being cooled by an inert liquid;

[0074] S5. Observe the outlet sample strip. After the cutting is stable, start timing and zero the mass balance. At this time, observe the detector reading and record it. After the timing reaches the requirement, read the mass balance reading;

[0075] S6. Calculate the viscosity of the high-viscosity fluid through a mathematical model formula;

[0076] S7. After the sampling measurement is completed, first close the cutting device, then close the sample injection, and then discharge part of the inert liquid in the box;

[0077] S8. Open the cleaning device to wash the detection cavity; after the washing is completed, close the cleaning device and let it stand;

[0078] S9. After standing, open the nitrogen input device to purge the detection cavity to blow out the residual solvent. After the purging is completed, close the nitrogen input device to end the sampling.

[0079] Preferably, all the valves in the detection device are in the closed state initially before the detection starts.

[0080] Preferably, the specific method of step S1 is to open the outlet valve, the sample injection valve, and the nitrogen valve in sequence. After injecting sufficient nitrogen to evacuate all the air in the device cavity, close the nitrogen valve.

[0081] Preferably, the nitrogen injection time is at least 2 s; or the nitrogen injection time is determined according to the oxygen concentration in the cavity. When the oxygen concentration in the detection cavity is lower than 1%, close the nitrogen valve and let it stand for 5 seconds.

[0082] Preferably, the specific method of step S2 is to start the driving mechanism to drive the cutter for timed shearing.

[0083] Preferably, the specific method of step S3 is to open the buffer valve, introduce the high-viscosity fluid from the conveying pipeline into the buffer area and the detection cavity. After the fluid fills the detection cavity, start to flow out through the sample outlet.

[0084] Preferably, the specific method of step S4 is that the outflowing highly viscous fluid is cut into segments by a cutter after being cooled by an inert liquid.

[0085] Preferably, the specific method of step S5 is to observe the outlet sample strip. After the cutting into segments is stable, start timing and zero the mass balance. At this time, observe the readings of the temperature detection mechanism, the upper pressure detection mechanism and the lower pressure detection mechanism and record them; after the timing reaches the requirement, read the reading of the mass balance to obtain the pressure difference and the mass flow rate.

[0086] Preferably, the mathematical model formula in step S6 is

[0087] where: μ is the polymer viscosity; ΔP is the pressure drop; L is the length of the detection section; r is the radius of the detection section; Q is the polymer mass flow rate.

[0088] Preferably, the specific method of step S7 is to first close the driving mechanism, then close the buffer valve, and then drain part of the inert liquid in the tank.

[0089] Preferably, the specific method of step S8 is to open the washing solvent valve, then open the volume pump, introduce the washing solvent to wash the detection cavity. After the washing is completed, close the volume pump and the washing solvent valve and let it stand for a period of time.

[0090] Preferably, the specific method of step S9 is to open the nitrogen valve, purge the detection cavity to blow out the residual solvent. After the purging is completed, close the nitrogen valve 3, and then close all the valves to end the sampling.

[0091] Example 3

[0092] This example is based on the above Example 2, and the same parts as the above Example 1 will not be elaborated.

[0093] In this example, the viscosity of the SBS melt is measured by the detection device of Example 1, and the stability of the sampled sample is verified.

[0094] The detection method of this example includes: sequentially opening the outlet valve, the sampling valve and the nitrogen valve, introducing nitrogen into the detection cavity, and continuously purging for 30 seconds to remove the oxygen in the cavity. After the oxygen concentration in the detection cavity is lower than 1%, close the nitrogen valve and let it stand for 5 seconds;

[0095] Next, open the buffer valve and slowly introduce the SBS melt into the buffer zone and further into the detection pipeline. Observe the fluid state at the outlet of the sampler to ensure that the fluid in the detection pipeline is fully filled and flowing smoothly. The temperature detection mechanism records the fluid temperature as 239°C. Subsequently, record the pressure data through the upper pressure detection mechanism and the lower pressure detection mechanism respectively. The reading of the upper pressure gauge is 5.72 MPa, the reading of the lower pressure gauge is 3.23 MPa, the distance between the upper and lower pressure gauges is 0.1 m, and the diameter of the detection pipeline is 0.012 m. Start the drive mechanism to drive the cutter to cut the cooled SBS melt at a fixed frequency, and the cut polymer splines fall into the inert liquid in the cooling tank, and the coolant temperature is maintained at 20°C. After the cut polymer splines are hardened, they are accumulated in the mass balance for weighing, and the measured spline flow rate is 0.89 kg / h.

[0096] Calculate the viscosity of the polymer according to the following formula:

[0097] Where μ is the polymer viscosity; ΔP is the pressure drop; L is the length of the detection section; r is the radius of the detection section; Q is the polymer mass flow rate.

[0098] Substitute the data into the formula, and the measured viscosity is about 5130 Pa·s.

[0099] After the experiment, conduct molecular weight and molecular weight distribution tests on the obtained splines. Using GPC testing, the molecular weights of the original sample and the sampled sample are 112532 g / mol and 114743 g / mol respectively, and the PDI is about 1.1 for both. The results show that the molecular weight and molecular weight distribution of the splines both conform to the characteristics of non-degradation, and no thermal degradation or oxidation phenomenon occurs. This proves that the device can effectively prevent the oxidation or degradation of the polymer during the sampling process through the nitrogen purge and inert liquid cooling design. In addition, compare the obtained viscosity results with the viscosity data measured by the laboratory rheometer. The rheometer uses oscillatory frequency scanning and measures the viscosity as 5350 Pa·s at 10 rad / s. The two results are basically the same, further verifying the accuracy and reliability of the viscosity test of this device.

[0100] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An online viscosity detection device for a high-viscosity fluid delivery pipeline, characterized in that: Connected to the pipeline for conveying high-viscosity fluid, including: detection mechanism and quality measurement mechanism; The detection mechanism is connected to a delivery pipeline of a high-viscosity fluid, and a cleaning device and a nitrogen input device are connected to the detection mechanism; the detection mechanism includes a detection chamber, a heat preservation device and a plurality of detectors, the heat preservation device is located outside the detection chamber, and the plurality of detectors are located inside the detection chamber; The mass measurement mechanism is located below the detection mechanism and includes a mass balance, a cooling box placed above the mass balance, and a cutting device. Inert liquid is placed in the cooling box, and the bottom of the detection cavity is immersed in the inert liquid.

2. The device for online viscosity detection on a high-viscosity fluid delivery pipeline according to claim 1, characterized in that: The detection mechanism also includes a buffer zone, which is located between the detection cavity and the delivery pipeline of the high-viscosity fluid and connects the detection cavity and the delivery pipeline of the high-viscosity fluid. The cleaning device and the nitrogen input device are both connected to the buffer zone.

3. The device for online viscosity detection on a high-viscosity fluid delivery pipeline according to claim 2, characterized in that: A buffer valve is arranged between the buffer zone and the delivery pipeline of the high-viscosity fluid, an injection valve is arranged between the buffer zone and the detection chamber, a nitrogen valve is arranged between the buffer zone and the nitrogen input device, and a washing solvent valve is arranged between the buffer zone and the cleaning device.

4. The device for online viscosity detection on a high-viscosity fluid delivery pipeline according to claim 1, characterized in that: The detector comprises an upper pressure detection mechanism located at the top of the detection cavity, a temperature detection mechanism located in the middle of the detection cavity and a lower pressure detection mechanism located at the bottom of the detection cavity.

5. The device for online viscosity detection on a high-viscosity fluid delivery pipeline according to claim 1, characterized in that: The detection cavity is an internal cavity of the detection pipeline connected to the buffer zone, and the heat preservation device is a heat preservation jacket, which is sleeved on the outside of the detection pipeline.

6. The device for online viscosity detection on a high-viscosity fluid delivery pipeline according to claim 1, characterized in that: The cleaning device comprises a volumetric pump and a washing solvent. The volumetric pump is connected to the washing solvent and the buffer zone, and the washing solvent is input into the buffer zone through the volumetric pump.

7. The device for online viscosity detection on a high-viscosity fluid delivery pipeline according to claim 1, characterized in that: The cutting device comprises a cutter, a base and a driving mechanism, wherein the base is arranged at the bottom of the detection cavity, and the driving mechanism is connected with the cutter.

8. The device for online viscosity detection on a high-viscosity fluid delivery pipeline according to claim 7, characterized in that: The base is provided with a groove body for cooperating with a cutter for cutting, the base is provided with a fluid cavity for high-viscosity fluid to pass through, the fluid cavity is connected with the detection cavity, and an outlet valve is provided between the detection cavity and the base.

9. The device for online viscosity detection on a high-viscosity fluid delivery pipeline according to claim 7, characterized in that: The tank on the base is immersed in the inert liquid.

10. A method for online viscosity detection on a high-viscosity fluid delivery pipeline, characterized in that: The device for online viscosity detection on a high-viscosity fluid delivery pipeline according to any one of claims 1 to 9 comprises the following steps: S1. After the nitrogen input device introduces sufficient nitrogen into the detection cavity to exhaust all the air in the cavity of the device, the nitrogen input device is closed; S2, start the cutting device to perform timed shearing; S3, passing the high-viscosity fluid in the delivery pipeline into the detection cavity, and the high-viscosity fluid flows out after filling the detection cavity; S4, the outflowing high-viscosity fluid is cooled by an inert liquid and then cut into sections by a cutting device; S5. Observe the outlet sample strip. When the cut section is stable, start timing and return the mass balance to zero. Observe and record the reading of the detector. When the timing reaches the requirement, read the mass balance reading. S6. Calculate the viscosity of high viscosity fluid through mathematical model formula; S7. After the measurement and sampling are completed, the cutting device is first closed, then the sample feed is closed, and then part of the inert liquid in the box is discharged; S8, open the cleaning device to clean the detection cavity; after the cleaning is completed, close the cleaning device and let it stand; S9. After standing still, open the nitrogen input device to purge the detection cavity to blow out the residual solvent. After the purge is completed, close the nitrogen input device to end sampling.

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