Method for cleaning long distance pipelines for slurry transportation

Abstract

The application discloses a cleaning method for long-distance pipelines for slurry transportation, which is to clean the long-distance pipelines for slurry transportation by using cavitation jet equipment and / or a spherical pipeline pig. Compared with conventional methods, the cleaning method can effectively remove different types of dirt in long-distance pipelines of different materials and lengths under the action of the cavitation jet equipment or the joint action of the cavitation jet equipment and the spherical pipeline pig without stopping and continuously opening, especially for pipelines with serious pollution and long length, the cleaning effect is better, and the cleaning method has the advantages of simple operation, low cleaning cost, high safety factor, high cleaning efficiency, good removal effect on different types of dirt, good adaptability and the like, can provide an efficient, environmentally-friendly and economical maintenance solution for the long-distance pipelines, and is especially suitable for high-value and difficult-to-stop slurry long-distance transportation systems, and has high use value and good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of special pipeline cleaning technology, and relates to a cleaning method for long-distance pipelines used for slurry transportation. Background Technology

[0002] Long-distance pipelines are pipeline systems used for transporting materials (such as slurries containing solid particles) over long distances. They are key facilities in slurry transport technology and play a vital role in modern industry, widely used in metallurgy, non-ferrous metals, and chemical industries. For example, in the mining of mineral resources (such as iron ore, copper ore, coal, and phosphate ore), long-distance pipelines (over 200 kilometers) can transport ore from mountainous areas to ports; similarly, in deep-sea mining (such as polymetallic nodule mining), long-distance pipelines are needed to lift minerals from the seabed to the surface; and in the recycling of industrial waste (such as fly ash and tailings), long-distance pipelines are also required to achieve resource recycling. Therefore, in the transportation of slurries, the stable operation of long-distance slurry pipelines is an inevitable choice for improving transportation efficiency and reducing transportation costs. However, the following problems and challenges also arise during the transportation of long-distance pipelines, specifically: (1) Settling and blockage: High-concentration slurries are prone to deposit in low-speed zones, causing pipeline blockage; blockage also occurs in areas with large temperature differences; blockage is also prone to occur in areas with complex terrain; blockage also occurs when there are abnormalities in the process; and blockage also occurs when there are slight abnormalities in the equipment. (2) Corrosion and wear: The problem of wear on pipelines caused by acidic or abrasive slurries has not been completely solved, and this situation will also exacerbate blockage. In particular, the volume of long-distance pipelines in existing slurry transportation technologies is getting larger and larger, and cleaning, as a key link to ensure the stable operation of pipelines, has also put forward higher requirements for cleaning technology. Therefore, it is necessary to obtain a suitable cleaning method to address the above problems.

[0003] Currently, the main cleaning methods used for pipelines include chemical cleaning, high-pressure water jet cleaning, PIG (pipeline cleaning machine) cleaning, cavitation cleaning, and pulse cleaning. However, these methods still have the following drawbacks: high energy consumption; low efficiency and long cleaning cycles; demanding conditions, especially unsuitable for cleaning non-metallic pipes; inability to remove hard scale; inability to clean severely blocked pipe sections; inability to directly clean ultra-long-distance pipelines, or requiring segmented cleaning for severely blocked sections of 10 kilometers or even several kilometers, necessitating shutdown or disconnection; high cleaning costs or poor cleaning results, making thorough cleaning difficult; high equipment pressure ratings; high safety risks; high investment costs; and potential equipment damage. In particular, existing cleaning methods are difficult to effectively clean long-distance pipelines with ultra-large diameters (e.g., DN≥80). Therefore, obtaining a cleaning method that is simple to operate, low in cleaning cost, high in safety, high in cleaning efficiency, effective in removing different types of scale, adaptable (applicable to pipes of different materials, lengths and diameters), and can effectively clean long-distance pipelines without interrupting transportation or shutting down is of great significance for ensuring the stable transportation of long-distance pipelines. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a cleaning method for long-distance pipelines used for slurry transportation that is simple to operate, low in cleaning cost, high in safety, high in cleaning efficiency, good in removing different types of scale, and has good adaptability.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This invention discloses a cleaning method for long-distance pipelines used for slurry transportation. When the nominal diameter of the long-distance pipeline to be cleaned is <80mm, cleaning method one is used to clean the long-distance pipeline; when the nominal diameter of the long-distance pipeline to be cleaned is ≥80mm, cleaning method two is used to clean the long-distance pipeline. Cleaning method one includes the following steps: S11. Obtain the flow rate of the long-distance pipeline to be cleaned; if the flow rate of the long-distance pipeline to be cleaned is more than 30% of the design flow rate, proceed to step S13; otherwise, proceed to step S12. S12. Use cavitation jet equipment to perform the first cleaning of the long-distance pipeline to be cleaned until the flow rate of the long-distance pipeline to be cleaned is more than 30% of the design flow rate. S13. Use cavitation jet equipment to perform a second cleaning on the long-distance pipeline to be cleaned, where the flow rate is more than 30% of the design flow rate, until the flow rate of the long-distance pipeline to be cleaned is the design flow rate. Cleaning method two includes the following steps: S21. Obtain the flow rate of the long-distance pipeline to be cleaned; if the flow rate of the long-distance pipeline to be cleaned is more than 30% of the design flow rate, proceed to step S23; otherwise, proceed to step S22. S22. Use cavitation jet equipment to perform the first cleaning of the long-distance pipeline to be cleaned until the flow rate of the long-distance pipeline to be cleaned is more than 30% of the design flow rate. S23. Using cavitation jet equipment and a pipeline pig, a second cleaning is performed on the long-distance pipeline to be cleaned, where the flow rate is more than 30% of the design flow rate, until the flow rate of the long-distance pipeline to be cleaned is more than 80% of the design flow rate; the pipeline pig is spherical. S24. Increase the diameter of the pipeline cleaning device, and use cavitation jet equipment and pipeline cleaning device to perform a third cleaning of the long-distance pipeline to be cleaned at a flow rate of more than 80% of the design flow rate, until the flow rate of the long-distance pipeline to be cleaned is the design flow rate, thus completing the cleaning of the long-distance pipeline.

[0006] The above-mentioned cleaning method, in a further improvement, step S12, when using a cavitation jet device to perform the first cleaning of the long-distance pipeline to be cleaned, includes the following steps: S121. Close the valve at the outlet end of the long-distance pipeline to be cleaned; S122. Turn on the cavitation jet device and input cavitation bubbles into the long-distance pipeline to be cleaned; the water-to-gas ratio in the cavitation bubbles is 1:400 to 1:20. S123. When the pressure at the end of the long-distance pipeline to be cleaned rises to 0.55MPa to 1.1MPa, open the valve at the outlet end of the long-distance pipeline to be cleaned to discharge the dirt in the pipeline until the pressure in the pipeline to be cleaned drops below 0.2MPa, then return to step S121. S124. Repeat steps S121 to S123, adjust the water-to-air ratio in the cavitation bubbles, and use cavitation bubbles with different water-to-air ratios to repeatedly clean the long-distance pipeline to be cleaned until the flow rate of the long-distance pipeline to be cleaned is more than 30% of the design flow rate.

[0007] A further improvement to the above-mentioned cleaning method, in step S13, when using a cavitation jet device to perform a second cleaning of the long-distance pipeline to be cleaned at a flow rate of more than 30% of the design flow rate, includes the following steps: S131. Close the valve at the outlet end of the long-distance pipeline to be cleaned; S132. Turn on the cavitation jet device and input cavitation bubbles into the long-distance pipeline to be cleaned; the water-to-gas ratio in the cavitation bubbles is 30:1 to 5:2. S133. When the pressure at the end of the long-distance pipeline to be cleaned rises to 0.55MPa to 1.1MPa, open the valve at the outlet end of the long-distance pipeline to be cleaned to discharge the dirt in the long-distance pipeline to be cleaned until the pressure in the long-distance pipeline to be cleaned drops to below 0.2MPa, then return to step S131. S134. Repeat steps S131 to S133, adjust the water-to-air ratio in the cavitation bubbles, and use cavitation bubbles with different water-to-air ratios to repeatedly clean the long-distance pipeline to be cleaned until the flow rate of the long-distance pipeline to be cleaned reaches or exceeds the normal flow rate.

[0008] The above-mentioned cleaning method is further improved in step S22, where the long-distance pipeline to be cleaned is first cleaned using a cavitation jet device, including the following steps: S221. Close the valve at the outlet end of the long-distance pipeline to be cleaned; S222. Turn on the cavitation jet device and input cavitation bubbles into the long-distance pipeline to be cleaned; the water-to-gas ratio in the cavitation bubbles is 1:400 to 1:20. S223. When the pressure at the end of the long-distance pipeline to be cleaned rises to 0.55MPa to 1.1MPa, open the valve at the outlet end of the long-distance pipeline to be cleaned to discharge the dirt in the pipeline until the pressure in the pipeline to be cleaned drops below 0.2MPa, then return to step S221. S224. Repeat steps S221 to S223, adjust the water-to-air ratio in the cavitation bubbles, and use cavitation bubbles with different water-to-air ratios to repeatedly clean the long-distance pipeline to be cleaned until the flow rate of the long-distance pipeline to be cleaned is more than 30% of the design flow rate.

[0009] The above-mentioned cleaning method, in a further improvement, step S23, when using cavitation jet equipment and a pipeline cleaning device to perform a second cleaning of the long-distance pipeline to be cleaned at a flow rate of more than 30% of the design flow rate, includes the following steps: S231. Close the valve at the outlet end of the long-distance pipeline to be cleaned, and place the pipeline cleaning machine into the long-distance pipeline to be cleaned. S232. Turn on the cavitation jet device and input cavitation bubbles into the long-distance pipeline to be cleaned; the water-to-gas ratio in the cavitation bubbles is 30:1 to 5:2. S233. When the pressure at the end of the long-distance pipeline to be cleaned rises to 0.55MPa to 1.1MPa, open the valve at the outlet end of the long-distance pipeline to be cleaned to discharge the dirt in the long-distance pipeline to be cleaned until the pressure in the long-distance pipeline to be cleaned drops to below 0.2MPa, then return to step S231. S234. Repeat steps S231 to S233, adjust the water-to-air ratio in the cavitation bubbles, and use cavitation bubbles with different water-to-air ratios to repeatedly clean the long-distance pipeline to be cleaned until the flow rate of the long-distance pipeline to be cleaned is more than 80% of the design flow rate.

[0010] In a further improvement to the above cleaning method, in step S231, when the nominal diameter of the long-distance pipeline to be cleaned is 80mm to 600mm, the diameter of the pipeline pig is 20mm to 50mm and the diameter of the pipeline pig is ≤ the minimum diameter inside the long-distance pipeline to be cleaned; when the nominal diameter of the long-distance pipeline to be cleaned is greater than 600mm, the diameter of the pipeline pig is ≥ 80mm and the diameter of the pipeline pig is ≤ the minimum diameter inside the long-distance pipeline to be cleaned; the number of pipeline pigs is 1 to 30.

[0011] The above-mentioned cleaning method, in a further improvement, step S24, when using cavitation jet equipment and a pipeline cleaning device to perform a third cleaning of the long-distance pipeline to be cleaned at a flow rate of more than 80% of the design flow rate, includes the following steps: S241. Close the valve at the outlet end of the long-distance pipeline to be cleaned, and place the pipeline cleaning machine into the long-distance pipeline to be cleaned. S242. Turn on the cavitation jet device and input cavitation bubbles into the long-distance pipeline to be cleaned; the water-to-gas ratio in the cavitation bubbles is 30:1 to 5:2. S243. When the pressure at the end of the long-distance pipeline to be cleaned rises to 0.55MPa to 1.1MPa, open the valve at the outlet end of the long-distance pipeline to be cleaned to discharge the dirt in the pipeline until the pressure in the pipeline to be cleaned drops below 0.2MPa, then return to step S241. S244. Repeat steps S241 to S243, adjust the water-to-air ratio in the cavitation bubbles, and use cavitation bubbles with different water-to-air ratios to repeatedly clean the long-distance pipeline to be cleaned until the flow rate of the long-distance pipeline to be cleaned reaches or exceeds the normal flow rate.

[0012] In a further improvement to the above cleaning method, in step S241, the diameter of the pipeline cleaning device is ≤ 70% of the inner diameter of the long-distance pipeline to be cleaned and the diameter of the pipeline cleaning device is ≥ 80 mm; the number of pipeline cleaning devices is 1 to 10.

[0013] In a further improvement to the above-mentioned cleaning method, the material of the long-distance pipeline to be cleaned is a metal pipeline and / or a non-metal pipeline.

[0014] In a further improvement to the above-mentioned cleaning method, the cavitation jet equipment includes an air compressor, and the air compressor is connected to a control device for adjusting the frequency and working pressure of the air compressor. The air compressor is also connected to an air tank; the working pressure of the air compressor is ≤1.1MPa.

[0015] Compared with the prior art, the advantages of the present invention are as follows: (1) In view of the shortcomings of pipeline cleaning methods, such as complex operation, low safety, high energy consumption, high investment cost, high cleaning cost, low cleaning efficiency, poor cleaning effect, poor adaptability to different scale types and pipe types, need for pipeline shutdown or disconnection, and serious secondary pollution, this invention creatively proposes a cleaning method for long-distance pipelines for slurry transportation. A cavitation jet device is used to clean the long-distance pipeline to be cleaned. On the one hand, cavitation bubbles are introduced into the pipeline to be cleaned and fill the pipeline. When these cavitation bubbles collapse, a low-pressure micro-jet effect and cavitation collapse effect are formed, i.e., cavitation jets. These cavitation jets generate shear force and impact force in the pipeline through low-pressure, high-speed, and irregular movement, thereby impacting (knocking) the scale in the pipeline. This not only breaks down hard scale (such as carbonates, ferrous sulfide, silicates, etc.), but also... Furthermore, it can remove viscoelastic substances (such as petroleum wax) without damaging the pipeline, effectively protecting the pipeline while also effectively removing different types of scale inside the pipeline. On the other hand, by using cavitation jet equipment to introduce cavitation bubbles into the long-distance pipeline to be cleaned, the positive pressure and cavitation jet effect continuously amplify as the pipeline lengthens, maximizing the pressure difference at the pipeline end (outlet end). Under these conditions, the cavitation jet removes the scale at the pipeline end (outlet end) first, followed by the scale in the middle of the pipeline, and finally the scale at the beginning of the pipeline. That is, the scale removal sequence is from back to front. This ensures that the entire cleaning process not only avoids pipeline blockage and facilitates the smooth discharge of scale inside the long-distance pipeline, but also that the cavitation jet effect amplifies as the pipeline lengthens, resulting in the best scale removal effect at the end. In other words, the longer the long-distance pipeline, the better the cleaning effect. In addition, the cleaning process also includes: placing a spherical pipeline pig (such as a small ball made of polyurethane material, but not limited to) into the long-distance pipeline to be cleaned. On the one hand, the cleaning using cavitation jet equipment can open up the inner diameter of the pipeline, making it easier for the spherical pipeline pig to move irregularly in the pipeline without clogging it. On the other hand, the cavitation jet can provide sufficient reverse thrust to make the spherical pipeline pig move in the opposite direction. With the cooperation of the spherical pipeline pig, the pressure difference between the two ends of the pipeline can be effectively controlled, and the pressure difference at the end of the pipeline can always be kept at its maximum. This ensures that the cavitation jet effect at the end of the pipeline is always optimal, which is conducive to the discharge of dirt from the end of the pipeline.Furthermore, due to the irregularity of scale formation and the presence of bends within the pipeline, the cavitation jet injected into the pipeline is also irregular. Consequently, the trajectory of the spherical pipeline pig within the pipeline is also irregular. This irregular movement, on the one hand, increases the impact intensity and frequency of the spherical pipeline pig on the scale within the pipeline, promoting the removal of scale from the inner wall of the pipeline. On the other hand, the spherical pipeline pig also continuously changes its direction of movement within the pipeline, thereby altering the direction of turbulence. This promotes interaction with the cavitation jet, resulting in more thorough cleaning of the scale within the pipeline. In particular, during the advancement of the spherical pipeline pig, it also pushes the scale outward, leading to higher cleaning efficiency. Compared with conventional cleaning methods, the cleaning method of this invention has the following advantages: (a) No chemical pollution, requiring only water and air, no chemical cleaning agents, complying with environmental regulations, and avoiding the risk of secondary pollution; (b) Wide adaptability, not only thoroughly removing stubborn deposits on the inner wall of pipelines (such as carbonates, ferrous sulfide, silicates, etc.), but also effectively removing deposits of complex composition, especially viscoelastic substances (such as petroleum waxes) that are difficult to remove by traditional mechanical methods; (c) Inhibiting corrosion and extending pipeline life, not only thoroughly removing corrosion products and oxide layers, reducing corrosion inducing factors, but also strengthening the microstructure of the metal surface and improving corrosion resistance; (d) Restoring throughput and reducing energy consumption, by restoring the designed pipe diameter after removing deposits, reducing flow resistance, and significantly improving transmission efficiency, not only ensuring normal pipeline transmission, but also significantly reducing pumping energy consumption. For example, after cleaning a natural gas pipeline, the pump pressure requirement... (e) It can achieve trenchless and uninterrupted maintenance, without cutting the pipeline or large-scale excavation, thus reducing maintenance costs; (f) It can accurately handle local defects. The cavitation jet can accurately grind the edge of the defect and eliminate stress concentration points, providing a high cleanliness surface (Sa2.5 level or above) for subsequent lining repair or coating construction; (g) It has low requirements for the selection of spherical pipeline pigs. It can be simply placed in, which is convenient for promotion and use and reduces the cost of use; (h) The process is safe. The pump and the cavitation jet equipment operate at low pressure (pressure between 0.1MPa and 0.55MPa) during the entire operation until the pipeline reaches a safe range of more than 80%, at which point the pressure can be slightly increased; (i) The equipment investment is small and the modification is minimal. The cavitation jet equipment mainly uses an air compressor, which only needs to operate at a pressure not exceeding 1.1MPa and can produce 6m³ of gas. 3 / min or above is sufficient, and multiple small air compressors can also be used in combination; (j) Low energy consumption, low power of cavitation jet equipment, low water consumption, high efficiency, low requirements for the model and material of spherical pipeline pig, and the spherical pipeline pig can be reused repeatedly with low wear, resulting in very low overall cost. The cleaning method of this invention, under the action of cavitation jet equipment, or under the combined action of cavitation jet equipment and spherical pipeline pig, can effectively remove different types of scale in long-distance pipelines of different materials and lengths without stopping or disconnecting. In particular, the cleaning effect is better for pipelines with severe clogging and long lengths. It has the advantages of simple operation, low cleaning cost, high safety factor, high cleaning efficiency, good removal effect on different types of scale, and good adaptability. It can provide an efficient, environmentally friendly and economical maintenance solution for long-distance pipelines, especially suitable for high-value, difficult-to-stop long-distance slurry transportation systems. It has high use value and good application prospects.

[0016] Table 1. Comparison of the advantages and disadvantages of the cleaning method of the present invention and conventional cleaning methods.

[0017] (2) In this invention, the pressure at the end of the long-distance pipeline to be cleaned is also optimized. By introducing cavitation bubbles into the long-distance pipeline to be cleaned, a relatively higher pressure environment can be formed in the long-distance pipeline to be cleaned. When the valve at the outlet end (end) of the long-distance pipeline to be cleaned is opened, a cavitation jet with a larger pressure difference can be formed, which has stronger shearing force and impact force, thereby more effectively removing dirt on the inner wall of the pipeline and promoting the discharge of dirt outward. Ultimately, it can ensure that dirt in the long-distance pipeline to be cleaned is removed efficiently under the premise of greater safety and lower cost.

[0018] (3) In this invention, the water-to-air ratio of cavitation bubbles in different cleaning stages is also optimized. By optimizing the water-to-air ratio of cavitation bubbles in different cleaning stages, cavitation jets with different states and different descaling capabilities can be formed. This can efficiently remove different types of dirt in the pipe, effectively reduce the damage to the pipe, effectively reduce the processing cost, and more importantly, significantly improve the cleaning efficiency and cleaning cleanliness. Attached Figure Description

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0020] Figure 1 This is a process flow diagram of the cleaning process for the long-distance pipeline used for slurry transportation in Embodiment 1 of the present invention. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0022] Unless otherwise specified, the materials and instruments used in the following embodiments of the present invention are commercially available, and the equipment used is conventional equipment.

[0023] Example 1 A cleaning method for long-distance pipelines used for slurry transportation, specifically cleaning the phosphogypsum pipes that transport phosphogypsum, such as... Figure 1 As shown, it includes the following steps: (1) Preparations before cleaning: (1.1) The phosphogypsum pipe to be cleaned is used to transport 25% acidic phosphogypsum. It is made of PE pipe, DN300, and 1.8 km long. It is severely clogged, and the flow rate is less than 50 m³ / h. 3 / h, design flow rate is 304.8m³ / h. 3 / h, normal operating flow rate is 250m³ / h 3 / h or more.

[0024] (1.2) Connect a DN50 to DN100 pipe (DN80 was used in this case, and the pipe size can be adjusted according to actual needs) 3m from the outlet of the pipeline pump at the front end of the phosphogypsum pipe to be cleaned, and install a check valve. Simultaneously connect a cavitation jet device, which includes a variable frequency air compressor (maximum working pressure 1.1MPa), a control device connected to the variable frequency air compressor for adjusting its frequency and working pressure, and an air tank for providing the air source. Under the control of the control device, the frequency and working pressure of the variable frequency air compressor are adjusted, and the residual water (water source) in the pipeline and the gas (air source) in the air tank are then converted into cavitation bubbles and introduced into the pipeline. In this step, the pipeline pump is a variable frequency centrifugal pump, which provides power to the pipeline as the power source for the transported medium. In another embodiment, the pipeline pump can also be a non-variable frequency centrifugal pump.

[0025] (1.3) Close the valves of each branch pipe.

[0026] (1.4) Install a DN300 ball valve at the end of the pipeline (outlet end).

[0027] (1.5) Build a temporary slag and water filter tank at the end of the pipeline (outlet end), and drain the pipeline. Store the discharged liquid in the slag and water filter tank. At the same time, check whether there are any leaks in the system to prevent secondary pollution.

[0028] (2) Clean the phosphogypsum tubes: (2.1) Obtain the flow rate of the phosphogypsum pipe. Specifically, the phosphogypsum pipe is severely blocked, and the flow rate is less than 50 m³ / h.3 / h, meaning the flow rate of the phosphogypsum pipe is less than 30% of the design flow rate, therefore step (2.2) is executed; otherwise, proceed to step (2.3).

[0029] (2.2) Use cavitation jet equipment to perform the first cleaning of the phosphogypsum pipe until the flow rate of the phosphogypsum pipe is more than 30% of the design flow rate. The specific steps are as follows: (2.21) Close the valve (ball valve) at the end (outlet end) of the phosphogypsum pipe.

[0030] (2.22) Connect the cavitation jet device to the front end of the phosphogypsum pipe to be cleaned, turn on the cavitation jet device, and introduce cavitation bubbles into the phosphogypsum pipe, wherein the water-to-air (liquid medium) ratio in the cavitation bubbles is 1:200 to 1:20. In this step, by controlling the water flow rate, air flow rate, and the water-to-air introduction frequency (e.g., a frequency of 40:3, i.e., first introduce air for 40 seconds, then introduce water for 3 seconds), the cavitation bubbles required for cleaning can be formed using the cavitation jet device.

[0031] (2.23) When the pressure at the end of the phosphogypsum pipe rises to 0.55 MPa, open the valve at the outlet end of the phosphogypsum pipe to discharge the dirt in the pipe. During the discharge of dirt, the pipeline pump on the phosphogypsum pipe can be turned on to assist the cavitation jet to discharge it outward until the pressure in the phosphogypsum pipe drops below 0.2 MPa, then return to step (2.21). (2.24) Repeat steps (2.21) to (2.23), adjusting the water-to-air ratio in the cavitation bubbles. Use cavitation bubbles with different water-to-air ratios to repeatedly clean the phosphogypsum tube until the flow rate of the phosphogypsum tube is more than 30% of the design flow rate. At this point, the minimum diameter inside the phosphogypsum tube reaches more than 80 mm. In this step, after each cleaning, the dirt in the sludge-water filter tank is filtered, and the resulting waste residue is transferred to a designated location.

[0032] (2.3) Use cavitation jet equipment and pipeline cleaning equipment to perform a second cleaning of the phosphogypsum pipe with a flow rate of more than 30% of the design flow rate until the flow rate of the phosphogypsum pipe is more than 80% of the design flow rate. The specific steps are as follows: (2.31) Close the valve at the outlet end of the phosphogypsum pipe and place a pipeline pig inside the phosphogypsum pipe. In this step, a simple PIG ball is used, specifically a polyurethane ball with a diameter of 40mm to 50mm. No launcher is required; it is simply placed into the pipe when the pump is stopped and the valve is removed (or, if there is a temporary quick-release blind flange at the pipe inlet, the blind flange can be opened to add the pig). The number of polyurethane balls placed into the phosphogypsum pipe each time can be one or several, such as five or ten, but is not limited to these numbers. Furthermore, these polyurethane balls can be reused.

[0033] (2.32) Turn on the cavitation jet device and introduce cavitation bubbles into the phosphogypsum tube, wherein the water-to-air ratio in the cavitation bubbles is 20:1 to 10:1. In this step, by controlling the water flow rate, air flow rate, and the water-to-air introduction frequency (e.g., a frequency of 40:3, i.e., first introduce air for 40 seconds, then introduce water for 3 seconds), the cavitation bubbles required for cleaning can be formed using the cavitation jet device.

[0034] (2.33) When the pressure at the end of the phosphogypsum pipe rises to 0.8 MPa, open the valve at the outlet end of the phosphogypsum pipe to discharge the dirt inside the pipe. During the discharge process, the pipeline pump on the phosphogypsum pipe can be turned on to assist the cavitation jet to discharge the dirt outwards until the pressure inside the phosphogypsum pipe drops below 0.2 MPa, then return to step (2.31). In other embodiments, the valve at the outlet end of the phosphogypsum pipe can be opened when the pressure at the end of the pipe is 0.6 MPa, 0.7 MPa, 0.9 MPa, or 0.95 MPa.

[0035] (2.34) Repeat steps (2.31) to (2.33), adjusting the water-to-air ratio in the cavitation bubbles. Use cavitation bubbles with different water-to-air ratios to repeatedly clean the phosphogypsum tube until the flow rate of the phosphogypsum tube is more than 80% of the design flow rate. At this point, the minimum diameter inside the phosphogypsum tube reaches more than 150 mm. In this step, after each cleaning, the dirt in the sludge-water filter tank is filtered, and the resulting waste residue is transferred to a designated location.

[0036] (2.4) Increase the diameter of the pipeline cleaning device, and use cavitation jet equipment and pipeline cleaning device to perform a third cleaning of the phosphogypsum pipe with a flow rate of more than 80% of the design flow rate until the flow rate of the phosphogypsum pipe reaches or exceeds the normal flow rate, thus completing the cleaning of the phosphogypsum pipe. The specific steps are as follows: (2.41) Close the valve at the outlet end of the phosphogypsum pipe (or remove the valve), and place a pipeline pig inside the phosphogypsum pipe. The pipeline pig used in this step is the same as in step (2.31), except that the pipeline pig used in step (2.41) is an 80mm diameter polyurethane ball. Furthermore, no launcher is required; it only needs to be placed inside the pipe when the pump is stopped and the valve is removed. The number of polyurethane balls placed into the phosphogypsum pipe each time can be one, or several, such as two, three, four, six, or ten, but is not limited to these numbers. Moreover, these polyurethane balls can be reused.

[0037] (2.42) Turn on the cavitation jet device and introduce cavitation bubbles into the phosphogypsum tube, wherein the water-to-air ratio in the cavitation bubbles is 10:1 to 5:2. In this step, by controlling the water flow rate, air flow rate, and the water-to-air introduction frequency (e.g., a frequency of 40:3, i.e., first introduce air for 40 seconds, then introduce water for 3 seconds), the cavitation bubbles required for cleaning can be formed using the cavitation jet device.

[0038] (2.43) When the pressure at the end of the phosphogypsum pipe rises to 1.0 MPa, open the valve at its outlet end to discharge the dirt inside the pipe into the sludge-water filter tank. During the discharge of dirt, the pipeline pump on the phosphogypsum pipe can be turned on to assist the cavitation jet to discharge it outwards until the pressure inside the pipe drops below 0.2 MPa, then return to step (2.41). In other embodiments, the valve at the outlet end of the phosphogypsum pipe can be opened when the pressure at the end of the pipe is 0.7 MPa, 0.8 MPa, 0.9 MPa, or 1.1 MPa.

[0039] (2.44) Repeat steps (2.41) to (2.43), adjusting the water-to-air ratio in the cavitation bubbles. Use cavitation bubbles with different water-to-air ratios to repeatedly clean the phosphogypsum tube until its flow rate reaches or exceeds the normal flow rate. At this point, the phosphogypsum tube returns to normal production status. In this step, after each cleaning, the dirt in the sludge-water filter tank is filtered, and the resulting waste residue is transferred to a designated location.

[0040] Example 2 A cleaning method for long-distance pipelines used for slurry transportation, specifically cleaning a phosphate concentrate pipe used for transporting slurry, includes the following steps: (1) Preparations before cleaning: (1.1) The material of the phosphate concentrate pipe is a spiral pipe (stainless steel) + PE pipe; model: DN331 (spiral pipe), DN335 (PE pipe); length: 46 km, of which 6 km is PE pipe; the blockage is very serious, and the flow rate is about 50% of the design flow rate. Based on the above situation, the existing chemical cleaning method and high-pressure water jet cleaning method cannot achieve effective cleaning, so they are excluded from the options.

[0041] (1.2) A DN100 pipeline is connected 5m from the outlet of the pipeline pump at the front end of the phosphate concentrate pipeline, and a check valve is installed. Simultaneously, a cavitation jet device is connected, comprising three variable frequency air compressors (maximum working pressure 1.1MPa), a control device connected to the variable frequency air compressors for adjusting their frequency and working pressure, and an air tank for providing the air source. Under the control of the control device, the frequency and working pressure of the variable frequency air compressors are adjusted, thereby generating cavitation bubbles from the residual water (water source) in the pipeline and the gas (air source) in the air tank, which are then introduced into the pipeline. In this step, the pipeline pump is a variable frequency centrifugal pump, which provides power to the pipeline as the power source for the transported medium. In another embodiment, the pipeline pump can also be a non-variable frequency centrifugal pump.

[0042] (1.3) Close the valves of each branch pipe.

[0043] (1.4) Install a DN335 ball valve at the end of the pipeline (outlet end).

[0044] (1.5) Build a temporary slag and water filter tank at the end of the pipeline (outlet end), and drain the pipeline. Store the discharged liquid in the slag and water filter tank, and test for water, pressure and leaks to ensure that the pipeline can operate normally and prevent secondary pollution.

[0045] (2) Cleaning the phosphate concentrate pipe: (2.1) Use cavitation jet equipment and pipeline cleaning equipment to clean the phosphate concentrate pipe with a flow rate of more than 50% of the design flow rate until the flow rate of the phosphate concentrate pipe is more than 80% of the design flow rate. The specific steps are as follows: (2.11) Close the valve at the outlet end of the phosphate concentrate pipe and place a pipeline pig inside the phosphate concentrate pipe. In this step, a simple PIG ball is used, specifically a 50mm diameter polyurethane ball. No launcher is required; it is simply placed into the pipe when the pump is stopped and the valve is removed. The number of polyurethane balls placed into the phosphate concentrate pipe each time can be one or several, such as five or ten, but is not limited to these numbers. Furthermore, these polyurethane balls can be reused.

[0046] (2.12) Turn on the cavitation jet equipment and input cavitation bubbles into the phosphate concentrate pipe, wherein the water-to-air ratio in the cavitation bubbles is 20:1 to 10:1. In this step, by controlling the water flow rate, air flow rate, and the water-to-air flow rate (e.g., a frequency of 40:3, i.e., first air flow for 40 seconds, then water flow for 3 seconds), the cavitation jet equipment can be used to form the cavitation bubbles required for cleaning.

[0047] (2.13) When the pressure at the end of the phosphate concentrate pipe rises to 0.8 MPa, open the valve at the outlet of the phosphate concentrate pipe to discharge the dirt inside the phosphate concentrate pipe. During the discharge of dirt, the pipeline pump on the phosphate concentrate pipe can be turned on to assist the cavitation jet to discharge it outward until the pressure inside the phosphate concentrate pipe drops below 0.2 MPa, then return to step (2.11).

[0048] (2.14) Repeat steps (2.11) to (2.13), adjusting the water-to-air ratio in the cavitation bubbles. Use cavitation bubbles with different water-to-air ratios to repeatedly clean the phosphate concentrate pipe until the flow rate of the phosphate concentrate pipe is more than 80% of the design flow rate. At this point, the minimum diameter inside the phosphate concentrate pipe reaches more than 150 mm. In this step, after each cleaning, the dirt in the slag-water filter tank is filtered, and the resulting waste residue is transferred to a designated location.

[0049] (2.2) Increase the diameter of the pipeline cleaning device, and use cavitation jet equipment and pipeline cleaning device to clean the phosphate concentrate pipe with a flow rate of more than 80% of the design flow rate until the flow rate of the phosphate concentrate pipe reaches above the normal flow rate, thus completing the cleaning of the phosphate concentrate pipe. The specific steps are as follows: (2.21) Close the valve at the outlet end of the phosphate concentrate pipe and place a pipeline pig inside the phosphate concentrate pipe. The pipeline pig used in this step is the same as in step (2.11), except that the pipeline pig used in step (2.21) is an 80mm diameter polyurethane ball. Furthermore, no launcher is required; it only needs to be placed inside the pipe when the pump is stopped and the valve is removed. The number of polyurethane balls placed into the phosphate concentrate pipe each time can be one, or several, such as two, three, four, six, or ten, but is not limited to these numbers. Moreover, these polyurethane balls can be reused.

[0050] (2.22) Turn on the cavitation jet equipment and input cavitation bubbles into the phosphate concentrate pipe, wherein the water-to-air ratio in the cavitation bubbles is 10:1 to 5:2. In this step, by controlling the water flow rate, air flow rate, and water-to-air introduction frequency (e.g., a frequency of 40:3, i.e., first introduce air for 40 seconds, then introduce water for 3 seconds), the cavitation jet equipment can be used to form the cavitation bubbles required for cleaning.

[0051] (2.23) When the pressure at the end of the phosphate concentrate pipe rises to 1.0 MPa, open the valve at the outlet end of the phosphate concentrate pipe to discharge the dirt in the phosphate concentrate pipe to the slag water filter tank. During the discharge of dirt, the pipeline pump on the phosphate concentrate pipe can be turned on to assist the cavitation jet to discharge it outward until the pressure in the phosphate concentrate pipe drops to below 0.2 MPa, then return to step (2.21). (2.24) Repeat steps (2.21) to (2.23), adjusting the water-to-air ratio in the cavitation bubbles. Use cavitation bubbles with different water-to-air ratios to repeatedly clean the phosphate concentrate pipe until the flow rate of the phosphate concentrate pipe reaches or exceeds the normal flow rate. At this point, the phosphate concentrate pipe returns to normal production status. In this step, after each cleaning, the dirt in the slag-water filter tank is filtered, and the resulting waste residue is transferred to a designated location.

[0052] Table 2 shows the data regarding the cleaning time, processing cost, and damage to the pipeline during the cleaning of the phosphate concentrate pipe in Example 2.

[0053] Table 2. Cleaning effect on phosphate concentrate pipe in Example 2 of the present invention.

[0054] In Table 2, the different cleaning methods use the same type of pipe with identical functions, materials, and scale types. The scale formation is slightly different, but it does not affect the results.

[0055] As shown in Table 2, the cleaning method of this invention, which combines low-pressure cavitation jet and simple PIG cleaning, has an absolute advantage in terms of processing cost, cleaning efficiency, and scope of application.

[0056] Example 3 A cleaning method for long-distance pipelines used for slurry transportation, specifically involving cleaning an iron ore slurry pipe, including the following steps: (1) Preparations before cleaning: (1.1) This iron ore slurry pipe is used to transport iron ore slurry with a concentration of 35%, and is made of PE pipe; model and length: DN300 (1km), DN250 (0.75km); connection method: hot melt welding; function: to transport iron ore slurry with a concentration of 35% to the production section; the blockage is very serious, and its flow rate is 60m³ / h. 3 / hour, this flow rate is less than 30% of the design flow rate (design flow rate is 284m³ / h). 3 Based on the above, existing chemical cleaning, high-pressure water jet cleaning, and PIG methods cannot meet the basic requirements. Furthermore, cavitation cleaning and steam-water pulse cleaning are not options because the operating pressure exceeds the pipeline's pressure rating (1.0 MPa).

[0057] (1.2) A DN50 pipe is connected 2m from the outlet of the pipeline pump at the front end of the iron ore slurry pipe, and a check valve is installed. Simultaneously, a cavitation jet device is connected, which includes a variable frequency air compressor (maximum working pressure 1.1MPa), a control device connected to the variable frequency air compressor for adjusting its frequency and working pressure, and an air tank for providing the air source. Under the control of the control device, the frequency and working pressure of the variable frequency air compressor are adjusted, thereby generating cavitation bubbles from the residual water (water source) in the pipeline and the gas (air source) in the air tank, which are then introduced into the pipeline. In this step, the pipeline pump is a variable frequency centrifugal pump, which provides power to the pipeline as the power source for the transported medium. In another embodiment, the pipeline pump can also be a non-variable frequency centrifugal pump.

[0058] (1.3) Close the valves of each branch pipe.

[0059] (1.4) Install a DN250 ball valve at the end of the pipeline (outlet end).

[0060] (1.5) Build a temporary slag and water filter tank at the end of the pipeline (outlet end), and drain the pipeline. Store the discharged liquid in the slag and water filter tank. At the same time, check whether there are any leaks in the system to prevent secondary pollution.

[0061] (2) Clean the iron ore slurry pipe: (2.1) Obtain the flow rate of the iron ore slurry pipe. Specifically, the pipe is severely blocked and its flow rate is less than 30% of the design flow rate. Therefore, proceed to step (2.2) or skip to step (2.3).

[0062] (2.2) Use cavitation jet equipment to perform the first cleaning of the iron ore slurry pipe until the flow rate of the iron ore slurry pipe is more than 30% of the design flow rate. The specific steps are as follows: (2.21) Close the valve (ball valve) at the end (outlet end) of the iron ore slurry pipe.

[0063] (2.22) Connect the cavitation jet device to the front end of the iron ore slurry pipe, turn on the cavitation jet device, and input cavitation bubbles into the pipe, wherein the water-to-air ratio in the cavitation bubbles is 1:200 to 1:20. In this step, by controlling the water flow rate, air flow rate, and water-to-air introduction frequency (e.g., a frequency of 40:3, i.e., first introduce air for 40 seconds, then introduce water for 3 seconds), the cavitation bubbles required for cleaning can be formed using the cavitation jet device.

[0064] (2.23) When the pressure at the end of the iron ore slurry pipe rises to 0.55 MPa, open the valve at the outlet end of the iron ore slurry pipe to discharge the dirt inside the iron ore slurry pipe. During the discharge of dirt, the pipeline pump on the iron ore slurry pipe can be opened to assist the cavitation jet to discharge it outward until the pressure inside the iron ore slurry pipe drops below 0.2 MPa, then return to step (2.21). (2.24) Repeat steps (2.21) to (2.23), adjusting the water-to-air ratio in the cavitation bubbles. Use cavitation bubbles with different water-to-air ratios to repeatedly clean the iron ore slurry pipe until the pipe flow rate is more than 30% of the design flow rate. At this point, the minimum diameter inside the iron ore slurry pipe will also reach more than 80 mm. In this step, after each cleaning, the dirt in the slag-water filter tank is filtered, and the resulting waste residue is transferred to a designated location.

[0065] (2.3) Use cavitation jet equipment and pipeline cleaning equipment to perform a second cleaning of the iron ore slurry pipe with a flow rate of more than 30% of the design flow rate until the flow rate of the iron ore slurry pipe is more than 80% of the design flow rate. The specific steps are as follows: (2.31) Close and remove the valve at the outlet end of the iron ore slurry pipe, place a pipeline pig into the iron ore slurry pipe, and then restore the valve. In this step, a simple PIG ball is used; specifically, it is a 50mm diameter polyurethane ball. No launcher is required; it is simply placed into the pipe when the pump is stopped and the valve is removed. The number of polyurethane balls placed into the iron ore slurry pipe each time can be one or several, such as five or ten, but is not limited to these numbers. Furthermore, these polyurethane balls can be reused.

[0066] (2.32) Turn on the cavitation jet equipment and introduce cavitation bubbles into the iron ore slurry pipe, wherein the water-to-air ratio in the cavitation bubbles is 20:1 to 10:1. In this step, by controlling the water flow rate, air flow rate, and the water-to-air introduction frequency (e.g., a frequency of 40:3, i.e., first introduce air for 40 seconds, then introduce water for 3 seconds), the cavitation bubbles required for cleaning can be formed using the cavitation jet equipment.

[0067] (2.33) When the pressure at the end of the iron ore slurry pipe rises to 0.8 MPa, open the valve at the outlet of the iron ore slurry pipe to discharge the dirt in the iron ore slurry pipe. During the discharge of dirt, the pipeline pump on the iron ore slurry pipe can be used to assist the cavitation jet to discharge it outward until the pressure in the iron ore slurry pipe drops below 0.2 MPa, then return to step (2.31).

[0068] (2.34) Repeat steps (2.31) to (2.33), adjusting the water-to-air ratio in the cavitation bubbles. Use cavitation bubbles with different water-to-air ratios to repeatedly clean the iron ore slurry pipe until the flow rate of the iron ore slurry pipe is more than 80% of the design flow rate. At this point, the minimum diameter inside the iron ore slurry pipe reaches more than 150 mm. In this step, after each cleaning, the dirt in the slag-water filter tank is filtered, and the resulting waste residue is transferred to a designated location.

[0069] (2.4) Increase the diameter of the pipeline cleaning device, and use cavitation jet equipment and pipeline cleaning device to perform a third cleaning of the iron ore slurry pipe with a flow rate of more than 80% of the design flow rate until the flow rate of the iron ore slurry pipe reaches or exceeds the normal flow rate, thus completing the cleaning of the iron ore slurry pipe. The specific steps are as follows: (2.41) Close the valve at the outlet end of the iron ore slurry pipe and place a pipeline pig inside the iron ore slurry pipe. The pipeline pig used in this step is the same as in step (2.31), except that the pipeline pig used in step (2.41) is an 80mm diameter polyurethane ball. Furthermore, no launcher is required; it only needs to be placed inside the pipe when the pump is stopped and the valve is removed. The number of polyurethane balls placed into the iron ore slurry pipe each time can be one, or several, such as two, three, four, six, or ten, but is not limited to these numbers. Moreover, these polyurethane balls can be reused.

[0070] (2.42) Turn on the cavitation jet equipment and introduce cavitation bubbles into the iron ore slurry pipe, wherein the water-to-air ratio in the cavitation bubbles is 10:1 to 5:2. In this step, by controlling the water flow rate, air flow rate, and the water-to-air introduction frequency (e.g., a frequency of 40:3, i.e., first introduce air for 40 seconds, then introduce water for 3 seconds), the cavitation bubbles required for cleaning can be formed using the cavitation jet equipment.

[0071] (2.43) When the pressure at the end of the iron ore slurry pipe rises to 1.0 MPa, open the valve at the outlet end of the iron ore slurry pipe to discharge the dirt in the pipe to the slag water filter tank. During the discharge of dirt, the pipeline pump on the iron ore slurry pipe can be turned on to assist the cavitation jet to discharge it outward until the pressure in the pipe drops below 0.2 MPa, then return to step (2.41). (2.44) Repeat steps (2.41) to (2.43), adjusting the water-to-air ratio in the cavitation bubbles. Use cavitation bubbles with different water-to-air ratios to repeatedly clean the iron ore slurry pipe until the flow rate of the iron ore slurry pipe reaches or exceeds the normal flow rate. At this point, the iron ore slurry pipe returns to normal production status. In this step, after each cleaning, the dirt in the slag-water filter tank is filtered, and the resulting waste residue is transferred to a designated location.

[0072] Table 3 shows the data regarding the cleaning time, processing cost, and damage to the pipeline during the cleaning of the iron ore slurry pipe in Example 3.

[0073] Table 3. Cleaning effect on iron ore slurry pipe in Example 3 of the present invention.

[0074] As shown in Table 3, the cleaning method of this invention, which combines low-pressure cavitation jet and simple PIG cleaning, has an absolute advantage in terms of processing cost, cleaning efficiency, and scope of application.

[0075] Example 4 A cleaning method for long-distance pipelines used for slurry transportation, specifically: cleaning the slurry pipe of a phosphate fertilizer plant, including the following steps: (1) Preparations before cleaning: (1.1) The slurry pipe is made of carbon steel with a rubber lining; model: DN450 reduced to DN400; length: 4.6km; it is severely clogged, and the flow rate is 60% of the design flow rate. Furthermore, most of the slurry pipe is underground, with some sections crossing roads and others crossing ponds. Based on these conditions, existing chemical cleaning methods, high-pressure water jet cleaning methods, and PIG methods cannot meet the basic requirements, and the PIG method is not an option because it damages the lining.

[0076] (1.2) A DN100 pipeline is connected 3m from the outlet of the pipeline pump at the front end of the slurry pipe, and a check valve is installed. Simultaneously, a cavitation jet device is connected, which includes two variable frequency air compressors (maximum working pressure 1.1MPa), a control device connected to the variable frequency air compressors for adjusting their frequency and working pressure, and an air tank for providing the air source. Under the control of the control device, the frequency and working pressure of the variable frequency air compressors are adjusted, thereby generating cavitation bubbles from the residual water (water source) in the pipeline and the gas (air source) in the air tank, which are then introduced into the pipeline. In this step, the pipeline pump is a variable frequency centrifugal pump, which provides power to the pipeline as the power source for the transported medium. In another embodiment, the pipeline pump can also be a non-variable frequency centrifugal pump.

[0077] (1.3) Close the valves of each branch pipe.

[0078] (1.4) Install a DN400 ball valve at the end of the pipeline (outlet end).

[0079] (1.5) Build a temporary slag and water filter tank at the end of the pipeline (outlet end), and drain the pipeline. Store the discharged liquid in the slag and water filter tank. At the same time, test the water, pressure and leaks to ensure that the pipeline can operate normally and prevent secondary pollution.

[0080] (2) Clean the slurry pipe: (2.1) Use cavitation jet equipment and pipeline cleaning equipment to clean the slurry pipe with a flow rate of more than 60% of the design flow rate until the flow rate of the slurry pipe is more than 80% of the design flow rate. The specific steps are as follows: (2.11) Close the valve at the outlet end of the slurry pipe and place a pipeline pig into the slurry pipe. In this step, a simple PIG ball is used, specifically a 50mm diameter polyurethane ball. No launcher is required; it is simply placed into the pipe when the pump is stopped and the valve is removed. The number of polyurethane balls placed into the slurry pipe each time can be one or several, such as five or ten, but is not limited to these. Furthermore, these polyurethane balls can be reused.

[0081] (2.12) Turn on the cavitation jet device and introduce cavitation bubbles into the slurry pipe, wherein the water-to-air ratio in the cavitation bubbles is 20:1 to 10:1. In this step, by controlling the water flow rate, air flow rate, and water-to-air introduction frequency (e.g., a frequency of 40:3, i.e., first introduce air for 40 seconds, then introduce water for 3 seconds), the cavitation bubbles required for cleaning can be formed using the cavitation jet device.

[0082] (2.13) When the pressure at the end of the slurry pipe rises to 0.8 MPa, open the valve at the outlet of the slurry pipe to discharge the dirt in the slurry pipe. During the discharge of dirt, the pipeline pump on the slurry pipe can be turned on to assist the cavitation jet to discharge it outward until the pressure in the slurry pipe drops below 0.2 MPa, then return to step (2.11).

[0083] (2.14) Repeat steps (2.11) to (2.13), adjusting the water-to-air ratio in the cavitation bubbles. Use cavitation bubbles with different water-to-air ratios to repeatedly clean the slurry pipe until the flow rate of the slurry pipe is more than 80% of the design flow rate. At this point, the minimum diameter inside the slurry pipe reaches more than 150 mm. In this step, after each cleaning, the dirt in the slurry water filter tank is filtered, and the resulting waste residue is transferred to a designated location.

[0084] (2.2) Increase the diameter of the pipeline cleaning device, and use cavitation jet equipment and pipeline cleaning device to clean the slurry pipe with a flow rate of more than 80% of the design flow rate until the flow rate of the slurry pipe reaches above the normal flow rate, thus completing the cleaning of the slurry pipe. The specific steps are as follows: (2.21) Close the valve at the outlet end of the slurry pipe and place a pipeline pig into the slurry pipe. The pipeline pig used in this step is the same as in step (2.11), except that the pipeline pig used in step (2.21) is an 80mm diameter polyurethane ball. Furthermore, no launcher is required; it only needs to be placed into the pipeline when the pump is stopped and the valve is removed. The number of polyurethane balls placed into the slurry pipe each time can be one, or several, such as two, three, four, six, or ten, but is not limited to these numbers. Moreover, these polyurethane balls can be reused.

[0085] (2.22) Turn on the cavitation jet device and introduce cavitation bubbles into the slurry pipe, wherein the water-to-air ratio in the cavitation bubbles is 10:1 to 5:2. In this step, by controlling the water flow rate, air flow rate, and the water-to-air introduction frequency (e.g., a frequency of 40:3, i.e., first introduce air for 40 seconds, then introduce water for 3 seconds), the cavitation bubbles required for cleaning can be formed using the cavitation jet device.

[0086] (2.23) When the pressure at the end of the slurry pipe rises to 1.0 MPa, open the valve at the outlet of the slurry pipe to discharge the scale in the slurry pipe into the slurry water filter tank. During the discharge of scale, the pipeline pump on the slurry pipe can be turned on to assist the cavitation jet to discharge it outward until the pressure in the slurry pipe drops below 0.2 MPa, then return to step (2.21).

[0087] (2.24) Repeat steps (2.21) to (2.23), adjusting the water-to-air ratio in the cavitation bubbles. Use cavitation bubbles with different water-to-air ratios to repeatedly clean the slurry pipe until the flow rate of the slurry pipe reaches or exceeds the normal flow rate. At this point, the slurry pipe returns to normal production status. In this step, after each cleaning, the dirt in the slurry water filter tank is filtered, and the resulting waste residue is transferred to a designated location.

[0088] Table 4 shows the data regarding the cleaning period, processing cost, and damage to the pipeline during the cleaning of the slurry pipe in Example 4.

[0089] Table 4. Cleaning effect on slurry pipe in Example 4 of the present invention.

[0090] In Table 4, the different cleaning methods use the same type of pipe with identical functions, materials, and scale types. The scale formation is slightly different, but it does not affect the results.

[0091] As shown in Table 4, the cleaning method of this invention, which combines low-pressure cavitation jet and simple PIG cleaning, has an absolute advantage in terms of processing cost, cleaning efficiency, and scope of application.

[0092] The results above show that, compared with conventional cleaning methods, the cleaning method of the present invention, under the action of cavitation jet equipment, or under the combined action of cavitation jet equipment and spherical pipe cleaning equipment, can effectively remove different types of scale in long-distance pipelines of different materials and lengths without stopping or disconnecting the pipeline. In particular, it has better cleaning effect for pipelines with severe clogging and long lengths. It has the advantages of simple operation, low cleaning cost, high safety factor, high cleaning efficiency, good removal effect on different types of scale, and good adaptability. It can provide an efficient, environmentally friendly and economical maintenance solution for long-distance pipelines, and is especially suitable for high-value, difficult-to-stop long-distance slurry transportation systems. It has high use value and good application prospects.

[0093] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A cleaning method for long-distance pipelines used for slurry transportation, characterized in that, When the nominal diameter of the long-distance pipeline to be cleaned is <80mm, cleaning method one is used to clean the long-distance pipeline; when the nominal diameter of the long-distance pipeline to be cleaned is ≥80mm, cleaning method two is used to clean the long-distance pipeline. The first cleaning method includes the following steps: S11. Obtain the flow rate of the long-distance pipeline to be cleaned; if the flow rate of the long-distance pipeline to be cleaned is more than 30% of the design flow rate, proceed to step S13; otherwise, proceed to step S12. S12. Use cavitation jet equipment to perform the first cleaning of the long-distance pipeline to be cleaned until the flow rate of the pipeline to be cleaned is more than 30% of the design flow rate; the first cleaning of the long-distance pipeline to be cleaned using cavitation jet equipment includes the following steps: S121. Close the valve at the outlet end of the long-distance pipeline to be cleaned; S122. Turn on the cavitation jet device and input cavitation bubbles into the long-distance pipeline to be cleaned; the water-to-gas ratio in the cavitation bubbles is 1:400 to 1:

20. S123. When the pressure at the end of the long-distance pipeline to be cleaned rises to 0.55MPa to 1.1MPa, open the valve at the outlet end of the long-distance pipeline to be cleaned to discharge the dirt in the pipeline until the pressure in the pipeline to be cleaned drops below 0.2MPa, then return to step S121. S124. Repeat steps S121 to S123, adjust the water-to-air ratio in the cavitation bubbles, and use cavitation bubbles with different water-to-air ratios to repeatedly clean the long-distance pipeline to be cleaned until the flow rate of the long-distance pipeline to be cleaned is more than 30% of the design flow rate. S13. A second cleaning is performed on the long-distance pipeline to be cleaned, where the flow rate is more than 30% of the design flow rate, using a cavitation jet device until the flow rate of the pipeline to be cleaned reaches the design flow rate. The second cleaning of the long-distance pipeline to be cleaned using a cavitation jet device includes the following steps: S131. Close the valve at the outlet end of the long-distance pipeline to be cleaned; S132. Turn on the cavitation jet device and input cavitation bubbles into the long-distance pipeline to be cleaned; the water-to-gas ratio in the cavitation bubbles is 30:1 to 5:

2. S133. When the pressure at the end of the long-distance pipeline to be cleaned rises to 0.55MPa to 1.1MPa, open the valve at the outlet end of the long-distance pipeline to be cleaned to discharge the dirt in the long-distance pipeline to be cleaned until the pressure in the long-distance pipeline to be cleaned drops to below 0.2MPa, then return to step S131. S134. Repeat steps S131 to S133, adjust the water-to-air ratio in the cavitation bubbles, and use cavitation bubbles with different water-to-air ratios to repeatedly clean the long-distance pipeline to be cleaned until the flow rate of the long-distance pipeline to be cleaned reaches or exceeds the normal flow rate. Cleaning method two includes the following steps: S21. Obtain the flow rate of the long-distance pipeline to be cleaned; if the flow rate of the long-distance pipeline to be cleaned is more than 30% of the design flow rate, proceed to step S23; otherwise, proceed to step S22. S22. Use cavitation jet equipment to perform the first cleaning of the long-distance pipeline to be cleaned until the flow rate of the pipeline to be cleaned is more than 30% of the design flow rate; the first cleaning of the long-distance pipeline to be cleaned using cavitation jet equipment includes the following steps: S221. Close the valve at the outlet end of the long-distance pipeline to be cleaned; S222. Turn on the cavitation jet device and input cavitation bubbles into the long-distance pipeline to be cleaned; the water-to-gas ratio in the cavitation bubbles is 1:400 to 1:

20. S223. When the pressure at the end of the long-distance pipeline to be cleaned rises to 0.55MPa to 1.1MPa, open the valve at the outlet end of the long-distance pipeline to be cleaned to discharge the dirt in the pipeline until the pressure in the pipeline to be cleaned drops below 0.2MPa, then return to step S221. S224. Repeat steps S221 to S223, adjust the water-to-air ratio in the cavitation bubbles, and use cavitation bubbles with different water-to-air ratios to repeatedly clean the long-distance pipeline to be cleaned until the flow rate of the long-distance pipeline to be cleaned is more than 30% of the design flow rate. S23. A second cleaning is performed on the long-distance pipeline to be cleaned, where the flow rate is more than 30% of the design flow rate, using a cavitation jet device and a pipeline pig, until the flow rate of the pipeline to be cleaned is more than 80% of the design flow rate; the pipeline pig is spherical; the second cleaning of the long-distance pipeline to be cleaned, where the flow rate is more than 30% of the design flow rate, using the cavitation jet device and the pipeline pig includes the following steps: S231. Close the valve at the outlet end of the long-distance pipeline to be cleaned, and place the pipeline cleaning machine into the long-distance pipeline to be cleaned. S232. Turn on the cavitation jet device and input cavitation bubbles into the long-distance pipeline to be cleaned; the water-to-gas ratio in the cavitation bubbles is 30:1 to 5:

2. S233. When the pressure at the end of the long-distance pipeline to be cleaned rises to 0.55MPa to 1.1MPa, open the valve at the outlet end of the long-distance pipeline to be cleaned to discharge the dirt in the long-distance pipeline to be cleaned until the pressure in the long-distance pipeline to be cleaned drops to below 0.2MPa, then return to step S231. S234. Repeat steps S231 to S233, adjust the water-to-air ratio in the cavitation bubbles, and use cavitation bubbles with different water-to-air ratios to repeatedly clean the long-distance pipeline to be cleaned until the flow rate of the long-distance pipeline to be cleaned is more than 80% of the design flow rate. S24. Increase the diameter of the pipeline cleaning tool, and use cavitation jet equipment and the pipeline cleaning tool to perform a third cleaning of the long-distance pipeline to be cleaned at a flow rate of more than 80% of the design flow rate, until the flow rate of the long-distance pipeline to be cleaned reaches the design flow rate, thus completing the cleaning of the long-distance pipeline; when using cavitation jet equipment and the pipeline cleaning tool to perform a third cleaning of the long-distance pipeline to be cleaned at a flow rate of more than 80% of the design flow rate, the following steps are included: S241. Close the valve at the outlet end of the long-distance pipeline to be cleaned, and place the pipeline cleaning machine into the long-distance pipeline to be cleaned. S242. Turn on the cavitation jet device and input cavitation bubbles into the long-distance pipeline to be cleaned; the water-to-gas ratio in the cavitation bubbles is 30:1 to 5:

2. S243. When the pressure at the end of the long-distance pipeline to be cleaned rises to 0.55MPa to 1.1MPa, open the valve at the outlet end of the long-distance pipeline to be cleaned to discharge the dirt in the pipeline until the pressure in the pipeline to be cleaned drops below 0.2MPa, then return to step S241. S244. Repeat steps S241 to S243, adjust the water-to-air ratio in the cavitation bubbles, and use cavitation bubbles with different water-to-air ratios to repeatedly clean the long-distance pipeline to be cleaned until the flow rate of the long-distance pipeline to be cleaned reaches or exceeds the normal flow rate.

2. The cleaning method according to claim 1, characterized in that, In step S231, when the nominal diameter of the long-distance pipeline to be cleaned is 80mm to 600mm, the diameter of the pipeline pig is 20mm to 50mm and the diameter of the pipeline pig is ≤ the minimum diameter inside the long-distance pipeline to be cleaned; when the nominal diameter of the long-distance pipeline to be cleaned is greater than 600mm, the diameter of the pipeline pig is ≥ 80mm and the diameter of the pipeline pig is ≤ the minimum diameter inside the long-distance pipeline to be cleaned; the number of pipeline pigs is 1 to 30.

3. The cleaning method according to claim 2, characterized in that, In step S241, the diameter of the pipeline pig is ≤ 70% of the inner diameter of the long-distance pipeline to be cleaned and the diameter of the pipeline pig is ≥ 80 mm; the number of pipeline pigs is 1 to 10.

4. The cleaning method according to any one of claims 1 to 3, characterized in that, The long-distance pipeline to be cleaned is made of metal and / or non-metal.

5. The cleaning method according to any one of claims 1 to 3, characterized in that, The cavitation jet device includes an air compressor, which is connected to a control device for adjusting the air compressor frequency and working pressure, and an air tank is also connected to the air compressor; the working pressure of the air compressor is ≤1.1 MPa.

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