Energy-saving optimization method and system for circulating pump of cyclonic microbubble flotation column

Abstract

The application discloses an energy-saving optimization method and system of a cyclone micro-bubble flotation column circulating pump, and relates to the technical field of coal preparation. The energy-saving optimization system of the cyclone micro-bubble flotation column circulating pump is connected with a flotation column, the flotation column is fed through a feeding pipe, and the energy-saving optimization system of the cyclone micro-bubble flotation column circulating pump comprises a circulating pump, a main pipeline, a bypass pipeline, an adjusting valve, a pressure gauge and a main pipeline mixing section. A belt pulley calculated according to S2 steps is installed on one side end face of the circulating pump, a pair of opposite end faces of the main pipeline are connected with bottom end faces of the flotation column respectively, the circulating pump, a valve and a bubble generator are connected to the main pipeline, and the starting end of the bypass pipeline is arranged between the main pipeline located between the outlet of the circulating pump and the bubble generator. The application is used for solving the problem of energy waste of the circulating pump of the flotation column of a coal preparation plant caused by a large rich coefficient and throttling of a valve, and provides a replicable and low-cost technical scheme for energy saving of a flotation system of the coal preparation plant.

Description

Technical Field

[0001] This invention belongs to the field of coal sorting technology, specifically relating to an energy-saving optimization method and system for a cyclone microbubble flotation column circulating pump. Background Technology

[0002] Flotation is a key process in the separation of fine coal particles in coal preparation plants, and flotation columns, as core flotation equipment, are widely used in coal preparation plants. Currently, the most widely used flotation column in my country's coal preparation plants is the cyclone microbubble flotation column, which has the following characteristics: 1. It integrates flotation and gravity separation, and can complete roughing, cleaning, and scavenging within a single column. Therefore, high-ash fine slime has less pollution to clean coal, resulting in lower ash content and higher recovery rate. It is perfectly suitable for the flotation of coal slime smaller than 0.5mm, and especially suitable for the flotation of difficult-to-separate coal slime with high ash content and ultra-fine particle size (-0.045mm); 3. It adopts a jet self-priming energy-saving microbubble generator configured outside the column, which has a large aeration volume, good bubble quality, does not clog, is easy to adjust, operates stably, and is easy to maintain and replace.

[0003] A flotation column includes a circulating pump and a microbubble generator. The circulating pump significantly affects the separation efficiency of the slurry due to its flow velocity and hydrostatic pressure. When the pipe diameter is fixed, the fluid velocity is directly proportional to the flow rate. Studies show that to ensure a strong swirling force field within the column, the circulating slurry flow rate should be at least three times the feed slurry flow rate. Simultaneously, the circulating pressure determines the air intake of the jet bubble generator. In industrial production, for ease of observation, a disc pressure gauge is typically installed on the circulating slurry pipe to monitor whether the circulating slurry pressure meets process requirements by measuring the hydrostatic pressure. Furthermore, the circulating pressure needs to be flexibly adjusted based on process parameters such as coal quality characteristics, feed concentration, and flotation column structure.

[0004] The selection of a circulating pump needs to comprehensively consider three energy requirements: the head required to overcome the height difference in raising the slurry (in industrial layouts, the bubble generator is about 7m higher than the pump outlet); the head required to overcome pipeline resistance (about 4-6m); and the net pressure head required to generate the static pressure of the fluid for the flotation process (up to about 20m, corresponding to 0.20MPa). Therefore, the rated head of the circulating pump is usually above 30m to meet industrial production needs. Thus, a common problem in coal preparation plants is that, in order to ensure that the circulating pump can provide a sufficiently large flow rate (≥3 times the feed rate) and generate sufficient pressure to ensure the bubble generator produces sufficient air intake, a large margin is often reserved when selecting the circulating pump, resulting in a rated head of typically above 30m, far exceeding the actual production process requirements. During normal production, the circulating pressure of a cyclone microbubble flotation column is typically 0.10-0.16 MPa, corresponding to a head of approximately 10-16 m. Especially when the flotation column is used as a secondary cleaning flotation device or for flotating certain types of coal slime, the required circulating pressure is usually 0.10-0.12 MPa, corresponding to a head of approximately 10-12 m. To achieve pressure matching, valve throttling is commonly used on-site to regulate the static pressure of the circulating pump, i.e., reducing the pressure of the circulating slurry by increasing flow resistance by closing the valve. It should be noted that with a fixed pump speed, the pump flow rate and head are inversely proportional, as shown in the pump's QH characteristic curve. When reducing pressure through valve throttling, the flow rate will also decrease accordingly, potentially affecting the strength of the cyclone force field within the flotation column. Furthermore, valve throttling essentially consumes excess energy by artificially increasing pipeline resistance; a significant amount of electrical energy is wasted on overcoming valve resistance, converting into heat dissipation and resulting in significant energy waste. It is estimated that pumps in coal preparation plants account for over 60% of the total power consumption, with ineffective energy consumption due to large margins and valve throttling accounting for as much as 15%-30%. This is seriously inconsistent with the energy conservation and consumption reduction requirements of the entire coal preparation plant system. Therefore, the ideal adjustment method is to reduce the pressure to meet the air intake requirements of the bubble generator while maintaining sufficient flow to sustain the cyclone separation effect.

[0005] To address the aforementioned issues, common solutions in existing technologies include replacing the pump with a smaller model or installing a frequency converter. However, replacing the pump with a smaller model presents several problems: high equipment procurement costs (tens of thousands to hundreds of thousands of yuan), long modification cycles (1-3 months), the need to dismantle pipelines and adjust equipment foundations, downtime affecting continuous production in the coal preparation plant, and waste of the original pump. Furthermore, it cannot adapt to the process characteristics of cyclone microbubble flotation columns, which require flexible adjustment of circulating pressure. If the coal quality or feed concentration changes, the replaced smaller model pump may not be able to simultaneously meet the flow rate and pressure requirements, affecting the flotation separation effect. While frequency converters can continuously adjust the motor speed, thereby regulating the flow and pressure of the circulating pump and adapting to fluctuations in process parameters, the investment per unit is relatively large, ranging from 80,000 to 150,000 yuan. For scenarios like cyclone microbubble flotation column circulating pumps, where the operating point is fixed for a long time and only needs to maintain a stable circulating pressure of 0.10-0.16MPa, there is still a redundant investment of "using a large motor for a small load." Moreover, frequency converter retrofitting involves complex processes such as circuit reconstruction and safety protection upgrades, making the retrofitting difficult and time-consuming. It is not suitable for the needs of low-cost, rapid, and energy-saving retrofitting of existing coal preparation plants.

[0006] Therefore, in order to address the above-mentioned technical problems, it is necessary to provide an energy-saving optimization method and system for a cyclone microbubble flotation column circulation pump.

[0007] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to provide an energy-saving optimization method and system for a cyclone microbubble flotation column circulating pump, which can adapt to the production needs of flexible adjustment of circulating pump pressure during production, realize full opening of main pipeline valves without throttling loss, precise pressure regulation of bypass, and at the same time ensure that bypass slurry participates in pipeline mineralization without affecting the flotation separation effect.

[0009] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution: An energy-saving optimization method for a cyclone microbubble flotation column circulation pump includes the following steps; S1. Determine the total target head required for the circulating pump using the following formula;

[0010] In the formula, ρ is the slurry density, g is the gravitational acceleration, Pmax is set to MPa, H is set to the total target head required by the circulating pump, Hsolid is the elevation difference of the site layout, and Hloss is the pipeline resistance loss. S2. Obtain the rated parameters of the circulating pump. Combined with the total target head determined in step S1, and based on the pump's proportional law and belt drive principle, assuming the pump end pulley diameter remains constant, the motor's rated speed remains constant, and there is no significant slippage in the belt drive, calculate and determine the new motor end pulley diameter d that meets the requirements using the following formula:

[0011] In the formula, Hr is the rated head of the pump, Htarget is the target head of the pump, D is the original pulley diameter of the motor, and d is the required new pulley diameter of the motor. S3. Complete the modification of the motor end pulley. Replace the original pulley with the new pulley with the diameter d of the pulley calculated in step S2. After the replacement is completed, adjust the valve of the main pipeline at the pump outlet to the fully open state. At the same time, install a pressure gauge on the main pipeline. At this time, keep the bypass closed. The circulating pump can stably output the highest circulating pressure Pmax required by the process. S4. Arrange bypass pipelines and regulating valves: Connect the circulating pump to the energy-saving optimization system of the cyclone microbubble flotation column circulating pump. Set the starting end of the bypass pipeline on the main pipeline between the outlet of the circulating pump and the bubble generator, and connect the end to the mixing section of the main pipeline between the outlet of the bubble generator and the flotation column. Only install regulating valves on the bypass pipeline. S5. According to production needs, the circulating pressure can be flexibly adjusted within the process requirements range by adjusting the regulating valve 10 to adapt to the sorting needs of different coal samples.

[0012] In one or more embodiments of the present invention, if H_solid and H_damage cannot be accurately calculated on-site in step S1, the following method is used for calculation; No need to calculate the specific head value: close the bypass valve completely, leave only the main line open, and fully open the main line valve. Start the motor and pump. At this time, the fluid static pressure monitored by the pressure gauge of the main line is the maximum static pressure generated under rated conditions.

[0013] In one or more embodiments of the present invention, when Hsolid and Hloss are difficult to determine in step S2, the pressure ratio is directly used instead of the head ratio, and the calculation formula is as follows:

[0014] In the formula, D is the diameter of the motor end pulley before the modification, P_set_max is the maximum circulating pressure required for production, and P_rated_max is the rated maximum static pressure monitored by the pressure gauge of the main pipeline when the bypass is closed and the main pipeline is fully open.

[0015] In one or more embodiments of the present invention, when the bypass pipeline is set between the outlet of the circulating pump and the bubble generator in step S4, it is necessary to ensure that the bypass slurry does not pass through the bubble generator, but can be fully mixed with the main pipeline slurry before entering the flotation column together.

[0016] In one or more embodiments of the present invention, the specific steps of S5 are as follows: S51. When the highest circulating pressure is required, close the regulating valve and all circulating slurry enters the bubble generator through the main pipeline. Monitor the pressure using a pressure gauge to see if the pressure meets the standard. S52. When a circulating pressure lower than the maximum value is required, increase the opening of the regulating valve to divert some of the slurry through the bypass pipeline, thereby reducing the slurry flow into the main pipeline and the bubble generator, and thus reducing the circulating pressure. Observe the pressure in real time through the pressure gauge of the main pipeline until the target pressure is adjusted.

[0017] In one or more embodiments of the present invention, during the adjustment process in step S5, it is ensured that the total flow rate of the circulating slurry meets the requirements of the flotation process, ensuring that a qualified swirling force field is formed in the flotation column, and at the same time ensuring that the bypass slurry and the main slurry are fully mixed so that the bypass particles participate in the pipe flow mineralization without affecting the flotation separation effect.

[0018] In one or more embodiments of the present invention, in step S4, after the liquid enters the main pipeline, the bypass pipeline leads the incoming liquid out of the main pipeline at a 30°-45° downstream direction, and after passing through the regulating valve, merges into the main pipeline between the bubble generator outlet and the flotation column at a 60°-90° downstream direction. The outlet of the bypass pipeline is obliquely inserted into the centerline of the main pipeline to form a forced vortex mixing zone. The energy-saving optimization system of the cyclone microbubble flotation column circulation pump is connected to the flotation column, which is fed through a feed pipe. The system includes a circulation pump, a main pipeline, a bypass pipeline, a regulating valve, a pressure gauge, and a mixing section of the main pipeline. A pulley calculated according to step S2 is installed on one end face of the circulation pump. A pair of opposite end faces of the main pipeline are connected to the bottom end face of the flotation column. The main pipeline connects to the circulation pump, valves, and a bubble generator. The starting end of the bypass pipeline is located between the outlet of the circulation pump and the bubble generator on the main pipeline. The end of the bypass pipeline is connected to the mixing section of the main pipeline between the bubble generator and the flotation column. The regulating valve is located on one end face of the bypass pipeline, and the pressure gauge is located on one end face of the main pipeline between the bubble generator and the flotation column. The mixing section of the main pipeline connects the main pipeline between the bubble generator and the flotation column.

[0019] In one or more embodiments of the present invention, the bypass pipeline is disposed below the main pipeline and is connected to the end face of the main pipeline. The angle between the bypass pipeline and the main pipeline is set to 30-45°, and the angle between the bypass pipeline and the main pipeline on the other side is set to 60-90°.

[0020] In one or more embodiments of the present invention, one end face of the bypass pipeline is obliquely inserted into the centerline end face of the main pipeline. Compared with the prior art, the energy-saving optimization method and system of the cyclone microbubble flotation column circulation pump of the present invention has the following effects; Low cost, high efficiency, easy to implement, can be precisely matched to the process requirements of cyclone microbubble flotation column, and does not require replacement of existing equipment or affect the flotation separation effect; Through bypass pipelines and electric regulating valves, the flow rate and pressure entering the bubble generator can be independently adjusted without changing the total pump flow rate or affecting the swirling force field, so as to achieve continuous adjustment of the circulating pressure in the range of 0.10-0.16MPa, perfectly adapting to the process requirements of different coal qualities. The circulating pump is connected to a suitable pulley, and the main pipeline valve can be kept fully open. All the energy that was originally used to overcome valve resistance is saved, resulting in significant energy savings. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the energy-saving optimization system of the cyclone microbubble flotation column circulation pump in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the energy-saving optimization system of the cyclone microbubble flotation column circulation pump in Embodiment 2 of the present invention.

[0023] Explanation of key figure labels: 1-Flotation column, 2-Tailings box, 3-Concentration and collection tank, 4-First discharge pipe, 5-Second discharge pipe, 6-Circulation pump, 7-Bubble generator, 8-Feed pipe, 9-Pressure gauge, 10-Regulating valve, 11-Bypass pipeline, 12-Main pipeline, 13-Edge mixing zone. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0025] like Figure 1As shown, the energy-saving optimization method and system for the circulating pump of the cyclone microbubble flotation column in one embodiment of the present invention can accurately match the process requirements of the cyclone microbubble flotation column. The energy-saving optimization method for the circulating pump can not only effectively solve many drawbacks of the existing technology, but also provide strong support for energy saving and consumption reduction of the entire coal preparation plant system. It has important practical significance and engineering application value.

[0026] like Figure 1-2 As shown, an energy-saving optimization method for a cyclone microbubble flotation column circulation pump includes the following steps; S1. Determine the required total target head of the circulating pump using the following formula; The total target head (Hset) of the circulating pump is determined using the actual highest circulating pressure (Pmax) as the core benchmark, combined with the elevation difference (Hfixed) and pipeline resistance loss (Hloss) in the site layout, providing data support for the selection of the motor end pulley diameter. Clarify the calculation logic of the total target head (Hset). The total target head (Hset) must ensure that the circulating pump can stably provide the highest circulating pressure (Pmax) when the main pipeline valve is fully open and the bypass is closed, meeting the highest process requirements in the site.

[0027] In the formula, ρ is the slurry density (kg / m³), g is the gravitational acceleration (9.81m / s²), Pmax is set to MPa, H is set to the total target head required by the circulating pump, Hsolid is the elevation difference of the site layout, and Hloss is the pipeline resistance loss. Among them, it is suitable for scenarios where H-fixed and H-loss are difficult to determine accurately; If the elevation difference (Hfixed) and pipeline resistance loss (Hloss) cannot be accurately calculated on site, the following approximate method can be used to determine the proportional relationship without calculating the specific head value: Completely close the bypass valve, leave only the main pipeline open, and fully open the main pipeline valve. Start the motor and pump. At this time, the fluid static pressure monitored by the pressure gauge of the main pipeline is the maximum static pressure (Pmax) generated under rated conditions. S2. Obtain the rated parameters of the circulating pump. Combined with the total target head (Hset) determined in step S1, and based on the pump's proportional law (head is directly proportional to the square of the speed) and the belt drive principle (speed is inversely proportional to the pulley diameter), assuming the pump end pulley diameter remains constant, the motor's rated speed remains constant, and the belt drive has no significant slippage (consistent with the actual conditions at the coal preparation plant), calculate and determine the required new motor end pulley diameter d using the following formula:

[0028] In the formula, the pump's rated head is H_rated (m, the pump's inherent rated parameters); the pump's target head is H_set (m, the target pump head required for production, determined in step S1); and the original motor pulley diameter is D (mm, the diameter of the motor pulley before modification). The required diameter of the new pulley for the motor: d (mm, which needs to be calculated and determined, i.e., the diameter of the pulley at the motor end that needs to be replaced after the modification).

[0029] When Hsolid and Hloss are difficult to determine, if the approximate method supplemented in step S1 is used, the pressure ratio can be directly used to replace the head ratio. The approximate calculation formula is as follows:

[0030] In the formula, D (mm, diameter of the motor end pulley before modification); P_set_max (MPa, the maximum circulating pressure required for production, i.e., the on-site process requirement); P_rated_max (MPa, the rated maximum static pressure monitored by the pressure gauge of the main pipeline when the bypass is closed and the main pipeline is fully open).

[0031] Correct the required new pulley diameter d for the motor: Take the calculated theoretical value of d, combine it with the standard pulley series, belt drive efficiency and actual working conditions on site, and correct it to the closest standard specification to ensure stable belt drive and that the actual static pressure of the fluid provided by the pump meets the Pmax design.

[0032] S3. Complete the modification of the motor end pulley and replace it with the new pulley (diameter d) calculated in step S2. After the replacement, adjust the valve of the main pipeline 12 at the pump outlet to the fully open state to eliminate the energy waste caused by the valve throttling of the main pipeline 12. At the same time, install pressure gauge 9 on the main pipeline 12 to monitor the circulating pressure of the main pipeline 12 in real time and provide a direct basis for subsequent pressure adjustment. At this time, the bypass pipeline 11 remains closed, and the circulating pump 6 can stably output the highest circulating pressure Pmax required by the process to meet the highest circulating pressure requirement of on-site production. S4. Arrange bypass pipelines and regulating valves. Specific arrangement requirements are as follows: The starting end of the bypass pipeline 11 is set on the main pipeline 12 between the outlet of the circulating pump 6 and the bubble generator 7, and the end is connected to the mixing section 18 of the main pipeline between the outlet of the bubble generator 7 and the flotation column 1. This ensures that the slurry in the bypass pipeline 11 does not pass through the bubble generator 7, but can be fully mixed with the slurry in the main pipeline 12 before entering the flotation column 1. Only the regulating valve 10 is installed on the bypass pipeline 11. There is no need to install additional pressure gauges or other monitoring components. The opening degree of the regulating valve 10 is adjusted to achieve precise control of the circulating pressure and ensure that the slurry in the bypass pipeline 11 participates in the pipe flow mineralization. The structure is simple and easy to implement.

[0033] It should be noted that after the liquid enters the main pipeline, the bypass pipeline 11 draws the incoming liquid out from the main pipeline 12 at a 30°-45° downstream direction. After passing through the regulating valve 10, the liquid flows into the main pipeline 12 between the outlet of the bubble generator 7 and the flotation column 1 at a 60°-90° downstream direction. The inlet of the bypass pipeline 11 is obliquely inserted into the centerline of the main pipeline 12, forming a forced vortex mixing zone 13, and so on. Figure 1 As shown.

[0034] It should be noted that the explanations for the "leading out" and "merging into" of the bypass pipe 11 from the main pipe 12 are as follows; Leading to the conclusion: Minimize energy loss and avoid forming large separation vortices. Therefore, when fluid changes from the main pipe to the bypass, a small angle can smoothly guide the fluid; the optimal angle is 30°~45° (theoretically, the smaller the angle with the main flow direction, the better). Figure 2 (angle a1 in the middle).

[0035] Inflow: Angle of bypass slurry into main pipeline. From a process perspective, the bypass slurry must be thoroughly mixed with the main pipeline slurry, so theoretically, countercurrent inflow is best. However, countercurrent inflow results in significant resistance loss and may cause backflow. Therefore, a 60-90° angle (especially 90° vertical) is used. Figure 2 Angle a2) merges into the main pipeline, and the bypass pipeline should be inserted into the main pipeline to a certain depth, reaching the centerline of the main pipeline, to form a forced eddy mixing zone. Requirements: (a) Distance from the bubble generator outlet ≥ 2m to ensure stable flow at the bubble generator outlet; (b) Distance from the flotation column inlet ≥ 3m to ensure sufficient mixing.

[0036] S5. Based on production needs, the circulating pressure can be flexibly adjusted within the process requirements range by adjusting the regulating valve 10 to adapt to the sorting requirements of different coal samples. This specifically includes the following steps: S51. When the highest circulating pressure is required, close the regulating valve 10. All circulating slurry enters the bubble generator 7 through the main pipeline 12. Monitor whether the pressure meets the standard through the pressure gauge 9. S52. When a circulating pressure lower than the maximum value is required, increase the opening of the regulating valve 10 to divert some of the slurry through the bypass pipeline 11, thereby reducing the slurry flow into the main pipeline 12 and the bubble generator 7, and thus reducing the circulating pressure. Observe in real time through the pressure gauge of the main pipeline until the target pressure is adjusted.

[0037] During the adjustment process, ensure that the total flow rate of the circulating slurry meets the requirements of the flotation process, guarantee the formation of a qualified swirling force field within the flotation column 1, and simultaneously ensure that the bypass slurry in the bypass pipeline 11 is fully mixed with the slurry in the main pipeline 12, allowing the bypass particles to participate in the pipeline mineralization without affecting the flotation separation effect. When changing the coal sample, there is no need to replace the motor pulley or adjust the valve opening on the main pipeline 12. Simply adjust the regulating valve 10 on the bypass pipeline 11 using the above adjustment method to quickly switch to the circulation pressure required for the new coal sample. The valve on the main pipeline 12 remains fully open throughout the process, with no throttling loss, maximizing energy savings.

[0038] like Figure 1-2 As shown, the energy-saving optimization system of the circulating pump for the cyclone microbubble flotation column includes a circulating pump 6, a main pipeline 12, a bypass pipeline 11, a regulating valve 10, a pressure gauge 9, and a mixing section 18 for the main pipeline. A feed pipe 8 is installed on the inner wall of the flotation column 1, which connects to a slurry feed pipe. The slurry feed pipe is connected to upstream feeding equipment to supply slurry. A first discharge pipe 4 is installed at the bottom of the flotation column 1, which connects to the tailings box 2 via a second discharge pipe 5. A concentration collection tank 3 is installed at the top end face of the flotation column 1.

[0039] A pulley calculated according to step S2 is installed on one end face of the circulating pump 6, so that the circulating pump 6 can provide the highest circulating pressure required for production when the valve on the main pipeline 12 is fully open and the valve on the bypass pipeline 11 is fully closed. like Figure 2 As shown, a pair of opposite end faces of the main pipeline 12 are connected to the bottom end face of the flotation column 1, that is, the main pipeline 12 connects the outlet of the circulating pump 6 to the inlet of the bottom swirl section of the flotation column 1. The main pipeline 12 is connected to the circulating pump 6, multiple valves, and a bubble generator 7. In operation, the valves on the main pipeline 12 are fully open. The bubble generator 7 is used to pressurize the slurry and mix it with air to generate microbubbles.

[0040] The bypass pipe 11 starts at the main pipe 12 between the outlet of the circulating pump 6 and the bubble generator 7, and ends at the mixing section 18 of the main pipe between the bubble generator 7 and the flotation column 1. The bypass pipe 11 is located below the main pipe 12, and all its end faces are connected to the main pipe 12. One end face of the bypass pipe is obliquely inserted into the centerline end face of the main pipe.

[0041] The angle between the bypass pipe 11 and the main pipe 12 is set to 30-45°, and the angle between the bypass pipe 11 and the main pipe 12 on the other side is set to 60-90°.

[0042] The regulating valve 10 is located on one end face of the bypass pipeline 11. The regulating valve 10 is used to regulate the bypass flow, thereby controlling the flow and pressure entering the bubble generator 7.

[0043] Pressure gauge 9 is installed on one side of the main pipeline 12, which is located on the end face of the bubble generator 7. Pressure gauge 9 is used to monitor the circulating pressure of the main pipeline in real time, providing a direct basis for subsequent pressure adjustment.

[0044] The main pipeline mixing section 18 is connected to the main pipeline 12 and is located between the bubble generator 7 and the flotation column 1. The main pipeline mixing section 18 is used to fully mix the main pipeline slurry and the bypass slurry before they enter the interior of the flotation column 1 together.

[0045] Compared with the prior art, the present invention has the following beneficial effects: 1. Eliminates throttling losses on main pipelines, resulting in significant energy savings. After matching the pulley diameter to the highest circulating pressure, the main pipeline valve can remain fully open, saving all the energy originally used to overcome valve resistance, resulting in significant energy savings.

[0046] 2. Enables flexible adjustment of circulating pressure. By using bypass pipes and electric regulating valves, the flow rate and pressure entering the bubble generator can be independently adjusted without changing the total pump flow rate or affecting the swirling force field, achieving continuous adjustment of the circulating pressure within the range of 0.10-0.16MPa, perfectly adapting to the process requirements of different coal qualities.

[0047] 3. Ensure sorting effectiveness After the bypass slurry exits the bubble generator, it mixes with the main slurry and enters the flotation column together. In the mixing section and subsequent pipelines, there is still ample opportunity for the slurry to come into contact with bubbles, achieving pipe flow mineralization. At the same time, the total pump flow rate remains unchanged, the swirling force field in the column remains stable, and the flotation performance is better than before the modification.

[0048] 4. Simple structure, easy to implement This invention only requires replacing the pulley and adding a bypass pipeline, without modifying the equipment foundation, motor, or pump body. The modification process is simple, the downtime is short, and the investment payback period is usually no more than 3 months.

[0049] 5. High compatibility and high promotional value. It can be directly applied to the energy-saving renovation of existing cyclone microbubble flotation columns, and can also be applied to newly built cyclone microbubble flotation column systems, with broad prospects for promotion and application. Example 1

[0050] Upgrade Plan: The central coal preparation plant of the coking park in the Shanghai Temple Energy and Chemical Base of Xinwen Mining Group currently has a flotation column circulating pump with a capacity of Q=1600m³ / h, H=30m, and N=250kW. The pump's flow rate and head margin are relatively large, requiring control through closing the pump inlet valve during actual production, which undoubtedly wastes a significant amount of energy. The upgrade aims to achieve energy conservation and consumption reduction by changing the diameter of the pulley at the motor end of the flotation column circulating pump. Before the upgrade, the diameter of the primary flotation motor pulley was 385mm; after the upgrade, the diameter is 335mm. Similarly, the diameter of the secondary flotation motor pulley was 430mm before the upgrade, and 335mm after the upgrade.

[0051] It should be noted that the embodiment is a practical application in industry, but only the diameter of the pulley at the motor end of the circulating pump was changed, without adding bypass piping. The new pulley diameter was determined based on the maximum circulating pressure of 0.15 MPa. Then, considering pipeline losses, etc., the belt diameter of the first flotation column was ultimately reduced to 335 mm, and the diameter of the second flotation column was reduced from 430 mm to 335 mm.

[0052] Under the premise of ensuring normal production operation at a circulating pressure of 0.1-0.15MPa, the upgraded system can reduce power consumption by 64kW for the 8 primary flotation columns and 72kW for the 4 secondary flotation columns, for a total reduction of 136kW. In terms of electricity costs alone, the upgrade saves 136 kWh per hour, 2176 kWh per day, directly saving 1719.04 yuan (at an electricity price of 0.79 yuan / kWh), and 567,300 yuan annually.

[0053] With the above improvements, without adding a bypass pipe, a daily electricity saving of 2176 kWh has been achieved. It is clear that the energy-saving effect of the technical solution of this application is significant. If the bypass pipe is added, the energy-saving effect will be even stronger.

[0054] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0055] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An energy-saving optimization method for a circulating pump in a cyclone microbubble flotation column, characterized in that, Includes the following steps; S1. Determine the total target head required for the circulating pump using the following formula; ； In the formula, ρ is the slurry density, g is the gravitational acceleration, Pmax is set to MPa, H is set to the total target head required by the circulating pump, Hsolid is the elevation difference of the site layout, and Hloss is the pipeline resistance loss. S2. Obtain the rated parameters of the circulating pump. Combined with the total target head determined in step S1, and based on the pump's proportional law and belt drive principle, assuming the pump end pulley diameter remains constant, the motor's rated speed remains constant, and there is no significant slippage in the belt drive, calculate and determine the new motor end pulley diameter d that meets the requirements using the following formula: ； In the formula, Hrated is the rated head of the pump, Htarget is the target head of the pump, D is the original pulley diameter of the motor, and d is the required new pulley diameter of the motor. S3. Complete the modification of the motor end pulley. Replace the original pulley with the new pulley with the diameter d of the pulley calculated in step S2. After the replacement is completed, adjust the valve of the main pipeline at the pump outlet to the fully open state. At the same time, install a pressure gauge on the main pipeline. At this time, keep the bypass closed. The circulating pump can stably output the highest circulating pressure Pmax required by the process. S4. Arrange bypass pipelines and regulating valves: Connect the circulating pump to the energy-saving optimization system of the cyclone microbubble flotation column circulating pump. Set the starting end of the bypass pipeline on the main pipeline between the outlet of the circulating pump and the bubble generator, and connect the end to the mixing section of the main pipeline between the outlet of the bubble generator and the flotation column. Only install regulating valves on the bypass pipeline. S5. Based on production needs, the circulating pressure can be flexibly adjusted within the process requirements range by adjusting the regulating valve to adapt to the sorting needs of different coal samples.

2. The energy-saving optimization method for the circulating pump of the cyclone microbubble flotation column according to claim 1, characterized in that, If H_solid and H_loss cannot be accurately calculated on-site in step S1, the following method shall be used for calculation; No need to calculate the specific head value: close the bypass valve completely, leave only the main line open, and fully open the main line valve. Start the motor and pump. At this time, the fluid static pressure monitored by the pressure gauge of the main line is the maximum static pressure generated under rated conditions.

3. The energy-saving optimization method for the circulating pump of the cyclone microbubble flotation column according to claim 1 or 2, characterized in that, In step S2, when Hsolid and Hloss are difficult to determine, the pressure ratio is directly used instead of the head ratio, and the calculation formula is as follows: ； In the formula, D is the diameter of the motor end pulley before the modification, P_set_max is the maximum circulating pressure required for production, and P_rated_max is the rated maximum static pressure monitored by the pressure gauge of the main pipeline when the bypass is closed and the main pipeline is fully open.

4. The energy-saving optimization method for the circulating pump of the cyclone microbubble flotation column according to claim 2, characterized in that, In step S4, when the bypass pipeline is set between the outlet of the circulating pump and the bubble generator, it is necessary to ensure that the bypass slurry does not pass through the bubble generator, but can be fully mixed with the main pipeline slurry before entering the flotation column together.

5. The energy-saving optimization method for the circulating pump of the cyclone microbubble flotation column according to claim 4, characterized in that, The specific steps of S5 are as follows: S51. When the highest circulating pressure is required, close the regulating valve and all circulating slurry enters the bubble generator through the main pipeline. Monitor the pressure using a pressure gauge to see if the pressure meets the standard. S52. When a circulating pressure lower than the maximum value is required, increase the opening of the regulating valve to divert some of the slurry through the bypass pipeline, thereby reducing the slurry flow into the main pipeline and the bubble generator, and thus reducing the circulating pressure. Observe the pressure in real time through the pressure gauge of the main pipeline until the target pressure is adjusted.

6. The energy-saving optimization method for the circulating pump of the cyclone microbubble flotation column according to claim 5, characterized in that, In step S5, during the adjustment process, it is ensured that the total flow rate of the circulating slurry meets the requirements of the flotation process, that a qualified swirling force field is formed in the flotation column, and that the bypass slurry and the main slurry are fully mixed so that the bypass particles participate in the mineralization of the pipeline flow without affecting the flotation separation effect.

7. The energy-saving optimization method for the circulating pump of the cyclone microbubble flotation column according to claim 5, characterized in that, In step S4, after the liquid enters the main pipeline, the bypass pipeline leads the liquid into the main pipeline in a 30°-45° downstream direction from the main pipeline. After passing through the regulating valve, the liquid flows into the main pipeline between the bubble generator outlet and the flotation column in a 60°-90° downstream direction. The port of the bypass pipeline is obliquely inserted into the center line of the main pipeline to form a forced eddy mixing zone.

8. An energy-saving optimization system for a cyclone microbubble flotation column circulation pump, applied to the energy-saving optimization method for the cyclone microbubble flotation column circulation pump according to any one of claims 1-7, connected to a flotation column, wherein the flotation column is fed through a feed pipe, characterized in that, include: The circulating pump has a pulley on one end face, which is calculated according to step S2. The main pipeline has a pair of opposite end faces that are respectively connected to the bottom end face of the flotation column, and a circulation pump, valves and a bubble generator are connected to the main pipeline; The bypass pipeline starts at the main pipeline between the outlet of the circulating pump and the bubble generator, and ends at the mixing section of the main pipeline between the bubble generator and the flotation column. A regulating valve is installed on one end face of the bypass pipeline; The pressure gauge is located on one end face of the main pipeline, which is situated on the side of the bubble generator. The main pipeline mixing section connects the main pipeline to the bubble generator and the flotation column.

9. The energy-saving optimization system for the cyclone microbubble flotation column circulation pump according to claim 8, characterized in that, The bypass pipeline is located below the main pipeline and is connected to the end face of the main pipeline. The angle between the bypass pipeline and the main pipeline is set to 30-45°, and the angle between the bypass pipeline and the main pipeline on the other side is set to 60-90°.

10. The energy-saving optimization system for the cyclone microbubble flotation column circulation pump according to claim 8, characterized in that, One end face of the bypass pipeline is obliquely inserted into the center line end face of the main pipeline.

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