Wide-flow continuous mixing system and control method

Abstract

The invention discloses a wide-flow continuous mixing system, which comprises: a mixing tank, the top, the side surface and the bottom of which are respectively provided with a feed inlet, a liquid inlet and a liquid outlet; an outlet of the liquid inlet pipe communicates with the liquid inlet through a first branch pipe, and a flow meter is installed on the liquid inlet pipe and used for measuring the flow in the liquid inlet pipe; the liquid outlet pipe is arranged below the mixing tank and penetrates in the liquid outlet direction to form a liquid outlet front end and a liquid outlet rear end, an inlet is formed in the middle of the liquid outlet pipe, and the liquid outlet pipe is communicated with the liquid outlet through a liquid outlet branch pipe; the second branch pipe is communicated with the liquid inlet pipe and the liquid outlet front end; the two control valves are installed on the first branch pipe and the second branch pipe respectively, and any control valve is used for adjusting the flow in the corresponding branch pipe; and the controller is electrically connected with the flow meter and the control valve. According to the invention, a liquid inlet shunting structure is combined with an active grading adjusting mode, so that the flow adjusting capability of the mixing system is effectively improved, and the continuous, uniform and stable mixing requirements of sand liquid in a wider flow range are adapted and met.

Description

Technical Field

[0001] This invention relates to the field of oil and gas fracturing technology. More specifically, this invention relates to a wide-flow-rate continuous mixing system and its control method. Background Technology

[0002] In the field of oil and gas resource development, hydraulic fracturing technology is a core means to improve reservoir permeability. The mixing system, as a core component of fracturing equipment, directly affects the quality of fracturing operations. With the continuous advancement of oil and gas resource extraction technology, the maximum operating flow rate of some wells has reached 24 m³ / h. 3 For flow rates above / min, the applicable range for traditional sand mixing technology is typically 0-20m³ / min. 3 / min, which cannot meet the increasingly wide range of operational requirements, such as the pressure-balanced mixing device described in patent CN114452878B, which uses a pressure-flow regulating valve on the inlet pipe to improve the mixing device's performance for 20m³ / min operations. 3 While capable of adapting to different flow rates within a certain range (e.g., / min), the pressure-flow regulating valve is a passive regulating device. Its performance is limited by the operating pressure of the supply pump, and the regulating range typically does not exceed 35% of the maximum flow rate, i.e., not exceeding 7m³ / min. 3 / min, with a narrow adjustment range, and not applicable to flow rates of 20m³ / min. 3 Operating conditions exceeding a certain flow rate ( / min). Furthermore, due to the limited volume of the mixing tank, when faced with conditions where the upper limit of the inlet flow rate increases and the range of flow rate fluctuations widens, and the mixing system's flow rate regulation capability is insufficient, the liquid level within the mixing tank is prone to significant fluctuations, thus affecting the stability of solid-liquid mixing operations.

[0003] To solve the above problems, it is necessary to design a wide-flow-rate continuous mixing system and control method to improve the flow regulation capability of the mixing system and achieve continuous and stable solid-liquid mixing over a wide flow range. Summary of the Invention

[0004] The purpose of this invention is to provide a wide-flow-rate continuous mixing system and control method, which combines a liquid inlet diversion structure with an active graded adjustment method, effectively improving the flow regulation capability of the mixing system to adapt to and meet the requirements of continuous, uniform, and stable mixing of sand and liquid over a wider flow range.

[0005] To achieve these objectives and other advantages according to the present invention, a wide-flow-rate continuous mixing system is provided, comprising: A mixing tank is provided with a feed inlet, a liquid inlet, and a liquid outlet on its top, side, and bottom, and a stirring device is provided inside the mixing tank. The inlet pipe has its outlet connected to the inlet of the mixing tank via a first branch pipe. A flow meter is installed on the inlet pipe and is configured to measure the flow rate within the inlet pipe. The liquid outlet pipe is located below the mixing tank and extends through it in the liquid outlet direction, forming a liquid outlet front end and a liquid outlet rear end. An inlet is provided in the middle of the liquid outlet pipe, which is connected to the liquid outlet of the mixing tank through a liquid outlet branch pipe. The second branch pipe connects the outlet of the inlet pipe to the outlet front end of the outlet pipe. Two control valves are installed on the first branch pipe and the second branch pipe respectively, and each control valve is set to regulate the flow rate in the corresponding branch pipe. The controller is electrically connected to both the flow meter and the control valve.

[0006] Preferably, in the wide flow continuous mixing system, the liquid outlet includes two liquid outlets, which are arranged opposite to each other on both sides of the liquid outlet pipe. The liquid outlet branch pipe and the inlet of the liquid outlet pipe are respectively arranged in a one-to-one correspondence with the two liquid outlets. Each liquid outlet is connected to the inlet of the liquid outlet pipe on the same side through the corresponding liquid outlet branch pipe.

[0007] Preferably, in the wide-flow continuous mixing system, the inlet pipe and the first branch pipe are coaxially and continuously arranged in the horizontal direction.

[0008] Preferably, the wide flow continuous mixing system further includes a support frame, which is mounted on the bottom of the mixing tank and fixedly connected thereto. The liquid outlet pipe passes through the inner side of the support frame. The second branch pipe bends downward and winds around the horizontal circumference of the support frame to the front end of the liquid outlet pipe and communicates with its liquid outlet front end. The horizontal winding section of the second branch pipe is fixedly connected to the support frame.

[0009] Preferably, the wide-flow continuous mixing system further includes a discharge pipe disposed at the lowest point of the second branch pipe and connected thereto; and a switch valve installed on the discharge pipe and configured to open or close the internal cross-section of the discharge pipe, wherein the switch valve is electrically connected to the controller.

[0010] Preferably, the wide-flow continuous mixing system further includes a level gauge installed inside the mixing tank and configured to detect the liquid level height inside the mixing tank, the level gauge being electrically connected to the controller.

[0011] The present invention also provides a control method for the wide-flow-rate continuous mixing system, comprising: S1. The inlet flow rate status is classified according to the detection data of the flow meter. When the detected real-time flow rate of the inlet pipe is lower than or equal to the set threshold, it is determined to be a low flow rate status; when the detected real-time flow rate of the inlet pipe is higher than the set threshold, it is determined to be a high flow rate status; the threshold is 50-60% of the maximum inlet flow rate. S2. In the low flow state, close the control valve located on the second branch pipe, and adjust the opening of the control valve on the first branch pipe according to the detection data of the flow meter. The opening increases as the real-time flow of the inlet pipe increases. S3. Under high flow conditions, control the opening of the control valve located on the first branch pipe to 100%, open the control valve located on the second branch pipe, and adjust the opening of the control valve on the second branch pipe according to the detection data of the flow meter. The opening of the control valve increases with the increase of the real-time flow of the inlet pipe.

[0012] Preferably, in the control method of the wide flow continuous mixing system, in S2, the low flow state is divided into two control stages according to a set first threshold. When the detected real-time flow of the inlet pipe is lower than or equal to the first threshold, the opening of the control valve on the first branch pipe is maintained at the set initial value. When the detected real-time flow of the inlet pipe is higher than the first threshold but lower than the boundary threshold, the opening of the control valve on the first branch pipe is controlled to change linearly with the real-time flow of the inlet pipe. When the detected real-time flow of the inlet pipe is equal to the boundary threshold, the opening of the control valve on the first branch pipe is controlled to be 100%.

[0013] Preferably, in the control method of the wide flow continuous mixing system, in S3, the high flow state is divided into two control stages according to the set second threshold. When the detected real-time flow of the inlet pipe is lower than or equal to the second threshold, the opening of the control valve on the second branch pipe is controlled to change linearly with the real-time flow of the inlet pipe. When the detected real-time flow of the inlet pipe is higher than the second threshold, the opening of the control valves located on the first branch pipe and the second branch pipe is controlled to be 100%.

[0014] Preferably, the control method for the wide-flow-rate continuous mixing system further includes: detecting the real-time liquid level status in the mixing tank using a level gauge and transmitting the detected data to the controller for processing; the controller has preset low liquid level thresholds and high liquid level thresholds, and adjusts the opening of corresponding control valves under different flow conditions according to the detection data of the level gauge; when the detected real-time liquid level height in the mixing tank is greater than the high liquid level threshold, the opening of the corresponding control valve is reduced; when the detected real-time liquid level height in the mixing tank is less than the low liquid level threshold, the opening of the corresponding control valve is increased.

[0015] The present invention has at least the following beneficial effects: 1. This invention uses first and second branch pipes to divert the liquid inlet pipe, and the second branch pipe is connected to the liquid outlet front end of the liquid outlet pipe. Through the dynamic diversion of the two branches and jet-assisted mixing, continuous mixing control under a wide flow range can be achieved, which effectively improves the flow regulation capability of the mixing system to adapt to and meet the requirements of uniform and stable mixing of sand and liquid over a wider flow range. At the same time, it ensures the operating efficiency of the mixing system (mixing and discharge) and greatly improves the performance of the equipment. 2. Compared with the passive flow regulation method in the prior art, this application adopts an active and hierarchical regulation control strategy. It identifies the current flow status through multi-level threshold judgment and performs fine regulation and control on different flow conditions, so that the mixing system can better adapt to the work with high upper limit of liquid inlet flow and large variation range, and ensure stable system output pressure. 3. This invention can adapt to 20m 3 Operating conditions at different flow rates above / min, and also considering 20m 3 Operating conditions at flow rates of / min and below, with minimal pressure and level fluctuations across different flow rates, ensuring a flow rate of 0-32m. 3 The stability of the tank liquid level and discharge pressure over a wide flow range of / min ensures the stability and quality of solid-liquid mixing operations.

[0016] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0017] Figure 1 This is a schematic elevation view of a wide-flow-rate continuous mixing system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the A-direction structure of the wide flow rate continuous mixing system described in the above embodiments.

[0018] 1. Inlet pipe; 2. Flow meter; 3. Three-way pipe; 4. First control valve; 5. Second control valve; 6. First branch pipe; 7. Mixing tank; 8. Second branch pipe; 9. Outlet pipe; 10. Drain pipe; 11. Switch valve; 12. Level gauge. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0020] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified. In the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0021] like Figure 1-2 As shown, the present invention provides a wide-flow continuous mixing system, comprising: A mixing tank is provided with a feed inlet, a liquid inlet, and a liquid outlet on its top, side, and bottom, and a stirring device is provided inside the mixing tank. The inlet pipe has its outlet connected to the inlet of the mixing tank via a first branch pipe. A flow meter is installed on the inlet pipe and is configured to measure the flow rate within the inlet pipe. The liquid outlet pipe is located below the mixing tank and extends through it in the liquid outlet direction, forming a liquid outlet front end and a liquid outlet rear end. An inlet is provided in the middle of the liquid outlet pipe, which is connected to the liquid outlet of the mixing tank through a liquid outlet branch pipe. The second branch pipe connects the outlet of the inlet pipe to the outlet front end of the outlet pipe. Two control valves are installed on the first branch pipe and the second branch pipe respectively, and each control valve is set to regulate the flow rate in the corresponding branch pipe. The controller is electrically connected to both the flow meter and the control valve.

[0022] In the above technical solution, the mixing tank has a vertical structure and is equipped with an internal stirring device, which can be a conventional stirrer (such as a turbine stirrer, a propeller stirrer, etc.). A liquid inlet on the side of the mixing tank is used to introduce liquid. Solid bulk materials can enter from the feed inlet at the top of the mixing tank, be fully mixed with the liquid under the action of the stirring device, and then output through the bottom outlet. The inlet of the liquid inlet pipe is connected to the discharge port of the liquid supply pump, and the flow meter is used to measure the real-time liquid inlet flow rate and transmit the signal to the controller. Specifically, the inlet pipe, the first branch pipe, and the second branch pipe are connected at their intersection by a T-junction. The T-junction divides the inlet into two paths. One path is connected to the inlet on the side of the mixing tank via the first branch pipe, and the other path is connected to the outlet pipe at the bottom of the mixing tank via the second branch pipe. Each branch pipe is equipped with an independent control valve, which has a continuous opening adjustment function and is electrically connected to the controller. The control valve can adjust the working state (on / off, opening degree) of each control valve according to the real-time inlet flow rate measured by the flow meter, thereby realizing the continuous adjustable flow rate function within a wide flow range of 0-32 m³ / min.

[0023] In practical applications, the flow meter measures the real-time input flow rate of the inlet pipe and transmits the flow data to the controller. The controller has a preset flow control threshold. Within different flow ranges, the flow rate of the supply pump can be adapted to the flow rate by adjusting the opening of each control valve, and the controller can respond to rapid changes in flow rate. For example, the control valve on the first branch pipe (i.e., the first control valve) can be used as the main valve, and its opening can be adjusted across the entire flow range. The control valve on the second branch pipe (i.e., the second control valve) can only be opened when the flow rate is high (exceeding the flow control threshold), and its opening can be adjusted according to the flow rate changes at the inlet pipe. This allows the second branch pipe to handle 40% of the total inlet flow rate, thus diverting the inlet flow rate from the first branch pipe (mixing tank). At this time, the flow rate diverted by the second branch pipe enters the front end of the outlet pipe, which can generate a jet effect in the outlet pipe. This can enhance the (secondary) mixing of the pipeline in cases of insufficient mixing or sedimentation of solid materials in the outlet pipe, while also assisting the smooth output of the mixture along the outlet pipe. This achieves efficient and uniform mixing of sand and liquid within a wide flow range and ensures stable output pressure.

[0024] In another technical solution, the wide-flow continuous mixing system includes two outlets, which are arranged opposite each other on both sides of the outlet pipe. The outlet branch pipe and the inlet of the outlet pipe are each corresponding to one of the two outlets. Each outlet is connected to the inlet of the outlet pipe on the same side through a corresponding outlet branch pipe. Figure 2 As shown, the sand and liquid mixtures in the mixing tank enter the outlet pipes from both sides of the middle section. The oppositely positioned outlet pipe inlets ensure that the material input directions are opposite and directly opposite each other, which helps to further mix the mixture in the outlet pipes, thereby improving its mixing uniformity and preventing sand accumulation.

[0025] In another technical solution, in the wide-flow continuous mixing system, the inlet pipe and the first branch pipe are coaxially and continuously arranged in the horizontal direction, thereby ensuring the inlet efficiency and inlet pressure of the first branch pipe as the main inlet channel of the mixing tank, avoiding inlet pressure loss caused by pipe bends, and thus ensuring the mixing performance of the mixing tank.

[0026] In another technical solution, the wide flow continuous mixing system further includes a support frame, which is mounted on the bottom of the mixing tank and fixedly connected thereto. The liquid outlet pipe passes through the inner side of the support frame. The second branch pipe bends downward and winds around the horizontal circumference of the support frame to the front end of the liquid outlet pipe and communicates with its liquid outlet front end. The horizontal winding section of the second branch pipe is fixedly connected to the support frame.

[0027] In the above technical solution, the support frame can raise the mixing tank to a set height, which is greater than the diameter of the outlet pipe, thus leaving space for the arrangement of the outlet pipe at the bottom of the mixing tank. Specifically, the support frame includes four struts, which are spaced apart around the bottom of the mixing tank. The bottom end of any strut is fixedly supported on the ground, and the top end is fixedly connected to the bottom of the mixing tank through a support plate. The support plate, struts, and mixing tank body can be installed by welding or bolting.

[0028] The second branch pipe includes a bent section and a horizontally wound section. The horizontally wound section is flush with the liquid outlet end of the liquid outlet pipe. The bent section is obliquely bent to connect the higher liquid inlet pipe with the lower horizontally wound section. The horizontally wound section is arranged along the outer periphery of the overall support frame during the winding process, which avoids structural interference and also provides auxiliary positioning and support points for the second branch pipe through the support frame, ensuring the connection and operational stability of the second branch pipe.

[0029] In another technical solution, the wide flow continuous mixing system further includes a discharge pipe, which is located at the lowest point of the second branch pipe and communicates with it; a switch valve, which is installed on the discharge pipe and configured to open or close the internal cross section of the discharge pipe, and the switch valve is electrically connected to the controller.

[0030] The drain pipe is connected to the second branch pipe at its lowest point, and the liquid is drained by a switch valve for maintenance, cleaning, and emergency discharge of the entire equipment (mixing system). Specifically, the drain pipe is installed horizontally or inclined downwards; the connection point between the drain pipe and the second branch pipe is directly opposite the outlet of the drain pipe, meaning the drain port on the second branch pipe is located on the extension line of the drain pipe's length to facilitate drainage. The switch valve is located at the end of the drain pipe near the second branch pipe to prevent sand accumulation inside the drain pipe.

[0031] In another technical solution, the wide-flow continuous mixing system further includes a level gauge installed inside the mixing tank and configured to detect the liquid level height inside the mixing tank, the level gauge being electrically connected to the controller.

[0032] The level gauge is positioned to avoid interfering with the stirring device inside the tank. It can be a conventional non-contact type, such as a radar level gauge or an ultrasonic level gauge, which receives reflected signals from the liquid surface and calculates the time difference to obtain real-time level data. The level gauge transmits the measured mixing tank level data to the controller via an electrical signal for processing. This allows the controller to further control the valves on each branch pipe based on the liquid level, preventing the tank level from becoming too high or too low.

[0033] The present invention also provides a control method for the wide-flow-rate continuous mixing system, comprising: S1. The inlet flow rate status is classified according to the detection data of the flow meter. When the detected real-time flow rate of the inlet pipe is lower than or equal to the set threshold, it is determined to be a low flow rate status; when the detected real-time flow rate of the inlet pipe is higher than the set threshold, it is determined to be a high flow rate status; the threshold is 50-60% of the maximum inlet flow rate. Here, the maximum inlet flow rate refers to the maximum inlet flow rate within the applicable operating conditions of this mixing system; S2. In the low flow state, close the control valve located on the second branch pipe, and adjust the opening of the control valve on the first branch pipe according to the detection data of the flow meter. The opening increases as the real-time flow of the inlet pipe increases. S3. Under high flow conditions, control the opening of the control valve located on the first branch pipe to 100%, open the control valve located on the second branch pipe, and adjust the opening of the control valve on the second branch pipe according to the detection data of the flow meter. The opening of the control valve increases with the increase of the real-time flow of the inlet pipe.

[0034] In the above technical solution, refined diversion control under high and low flow conditions is achieved by setting a dividing threshold. Under low flow conditions, the control valve on the second branch pipe is closed, and only the control valve on the first branch pipe is adjusted to match the flow rate of the liquid supply pump. Under high flow conditions, the control valve on the first branch pipe is fully open, and the opening of the control valve on the second branch pipe is adjusted to match the flow rate of the liquid supply pump, thereby achieving adaptability and continuous adjustment over a wide (inlet) flow range. Specifically, when the total inlet flow exceeds the dividing threshold, diversion occurs through the second branch pipe, ensuring the stability of the inlet flow in the mixing tank and preventing an excessively high inlet ratio from affecting the mixing uniformity and the mixing effect of the stirring device. Simultaneously, the liquid diverted through the second branch pipe enters from the front end of the outlet pipe, undergoes secondary mixing with the mixture entering from the middle of the outlet pipe, and is output from the rear end of the outlet pipe. This improves the overall material mixing uniformity and ensures stable output pressure of the mixture. The above control method achieves continuous mixing control over a wide flow range through dual-branch dynamic diversion and jet-assisted mixing, thereby improving the mixing capacity of the mixing system to adapt to and meet the requirements of uniform and stable mixing of sand and liquid over a wider flow range. At the same time, it ensures the operating efficiency of the mixing system (mixing and discharge) and greatly improves the performance of the equipment.

[0035] In another technical solution, the control method of the wide-flow continuous mixing system, in step S2, divides the low-flow state into two control stages based on a set first threshold. When the detected real-time flow rate of the inlet pipe is lower than or equal to the first threshold, the opening of the control valve on the first branch pipe is maintained at a set initial value. When the detected real-time flow rate of the inlet pipe is higher than the first threshold but lower than the boundary threshold, the opening of the control valve on the first branch pipe is controlled to change linearly with the real-time flow rate of the inlet pipe. When the detected real-time flow rate of the inlet pipe is equal to the boundary threshold, the opening of the control valve on the first branch pipe is controlled to be 100%. The first threshold is lower than the boundary threshold. The initial control value of the control valve in the open state is not 0 to prevent the control valve opening from being too low and affecting the liquid inlet effect. When the real-time flow rate of the inlet pipe is too low, the opening of the control valve on the first branch pipe is maintained at a set initial value (e.g., 20%). Within the normal flow range (first threshold - boundary threshold), the opening of the control valve on the first branch pipe is linearly and continuously controlled with the change of the inlet flow rate, so that when the inlet flow rate reaches the boundary threshold, the opening of the control valve on the first branch pipe reaches 100% (fully open state).

[0036] In another technical solution, the control method of the wide-flow continuous mixing system, in step S3, divides the high-flow state into two control stages based on a set second threshold. When the detected real-time flow rate of the inlet pipe (higher than the boundary threshold and lower than or equal to the second threshold) is controlled, the opening of the control valve on the second branch pipe is controlled to change linearly with the real-time flow rate of the inlet pipe. When the detected real-time flow rate of the inlet pipe is higher than the second threshold, the opening of the control valves on the first and second branches is controlled to be 100%. The second threshold is greater than the boundary threshold and less than the maximum inlet flow rate. When the real-time flow rate of the inlet pipe is too high (close to the maximum inlet flow rate), the control valves on the first and second branches are fully opened.

[0037] In another technical solution, the control method of the wide-flow-rate continuous mixing system further includes: detecting the real-time liquid level status in the mixing tank using a level gauge and transmitting the detected data to the controller for processing; the controller has preset low liquid level thresholds and high liquid level thresholds, and adjusts the opening of the corresponding control valves under different flow conditions according to the detection data of the level gauge; when the detected real-time liquid level height in the mixing tank is greater than the high liquid level threshold, the opening of the corresponding control valve is reduced; when the detected real-time liquid level height in the mixing tank is less than the low liquid level threshold, the opening of the corresponding control valve is increased.

[0038] The high liquid level threshold is greater than the low liquid level threshold. Here, the corresponding control valve mainly refers to the control valve on the first branch pipe, which responds to changes in liquid level by increasing or decreasing the inlet flow rate. For example, under low flow conditions, the opening of the control valve on the first branch pipe can be directly adjusted; while under high flow conditions, the openings of the control valves on both the first and second branch pipes can be adjusted, requiring simultaneous and synchronous adjustment of the openings of both control valves.

[0039] The above control method is illustrated using a wide-flow-rate continuous mixing system as an example. The wide-flow-rate continuous mixing system includes: an inlet pipe, a flow meter, a three-way pipe, a first branch pipe, a second branch pipe, two control valves, a mixing tank, an outlet pipe, a discharge pipe, a switch valve, a level gauge, and other auxiliary components.

[0040] Control methods include: Within the permissible operating conditions (flow rate) range of the mixing system, the first threshold, the boundary threshold, and the second threshold are set sequentially from low to high, and are respectively 25%, 60%, and 90% of the maximum inlet flow rate.

[0041] The controller reads the real-time inlet flow rate detected by the flow meter and compares it with various thresholds: When the real-time inlet flow rate is less than or equal to the first threshold, the control valve on the first branch pipe is kept at 20% opening to maintain a low liquid flow rate, and the control valve on the second branch pipe is closed. When the first threshold < real-time inlet flow rate ≤ boundary threshold, the opening of the control valve on the first branch pipe is linearly related to the real-time inlet flow rate (when the real-time inlet flow rate is 60% of the maximum inlet flow rate, the opening of the control valve on the first branch pipe is 100%), and the control valve on the second branch pipe is closed. When the threshold is less than the real-time inlet flow rate and less than the second threshold, the control valve on the first branch pipe is fully open, and the opening of the control valve on the second branch pipe changes linearly with the real-time inlet flow rate (when the real-time inlet flow rate is 90% of the maximum inlet flow rate, the opening of the control valve on the second branch pipe is 100%), in order to match the flow rate of the supply pump. When the real-time inlet flow rate exceeds the second threshold, both control valves are fully open to ensure high-flow delivery.

[0042] Simultaneously, a mixing tank level control is introduced. The controller reads the real-time liquid level height detected by the level gauge and compares it with the set liquid level thresholds (the low liquid level threshold is 25% of the maximum allowable liquid level height in the mixing tank, and the high liquid level threshold is 90% of the maximum allowable liquid level height in the mixing tank). When the low liquid level threshold ≤ real-time liquid level height ≤ high liquid level threshold, the opening of each control valve remains unchanged. When the real-time liquid level height < low liquid level threshold, under low flow conditions, the opening of the control valve on the first branch increases, and under high flow conditions, the opening of the control valves on the first and second branches increases proportionally. When the real-time liquid level height is greater than the high liquid level threshold, under low flow conditions, the opening of the control valve on the first branch decreases, and under high flow conditions, the opening of the control valves on the first and second branches decreases proportionally.

[0043] Experiments have verified that the pressure fluctuation of the above-mentioned wide-flow-rate continuous mixing system is ≤0.05MPa and the liquid level fluctuation is ≤±1% at a flow rate of 32m³ / min.

[0044] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A wide-flow-rate continuous mixing system, characterized in that, include: A mixing tank is provided with a feed inlet, a liquid inlet, and a liquid outlet on its top, side, and bottom, and a stirring device is provided inside the mixing tank. The inlet pipe has its outlet connected to the inlet of the mixing tank via a first branch pipe. A flow meter is installed on the inlet pipe and is configured to measure the flow rate within the inlet pipe. The liquid outlet pipe is located below the mixing tank and extends through it in the liquid outlet direction, forming a liquid outlet front end and a liquid outlet rear end. An inlet is provided in the middle of the liquid outlet pipe, which is connected to the liquid outlet of the mixing tank through a liquid outlet branch pipe. The second branch pipe connects the outlet of the inlet pipe to the outlet front end of the outlet pipe. Two control valves are installed on the first branch pipe and the second branch pipe respectively, and each control valve is set to regulate the flow rate in the corresponding branch pipe. The controller is electrically connected to both the flow meter and the control valve.

2. The wide-flow-rate continuous mixing system as described in claim 1, characterized in that, The liquid outlet includes two liquid outlets, which are arranged opposite each other on both sides of the liquid outlet pipe. The liquid outlet branch pipe and the inlet of the liquid outlet pipe are respectively arranged in a one-to-one correspondence with the two liquid outlets. Each liquid outlet is connected to the inlet of the liquid outlet pipe on the same side through the corresponding liquid outlet branch pipe.

3. The wide-flow-rate continuous mixing system as described in claim 1, characterized in that, The inlet pipe and the first branch pipe are coaxially and continuously arranged in the horizontal direction.

4. The wide-flow-rate continuous mixing system as described in claim 1, characterized in that, It also includes a support frame, which is mounted on the bottom of the mixing tank and fixedly connected thereto. The liquid outlet pipe passes through the inside of the support frame. The second branch pipe bends downward and winds around the horizontal circumference of the support frame to the front end of the liquid outlet pipe and then communicates with the front end of the liquid outlet pipe. The horizontal winding section of the second branch pipe is fixedly connected to the support frame.

5. The wide-flow-rate continuous mixing system as described in claim 1, characterized in that, It also includes a drain pipe, which is located at the lowest point of the second branch pipe and communicates with it; and a switch valve, which is installed on the drain pipe and configured to open or close the internal cross section of the drain pipe, the switch valve being electrically connected to the controller.

6. The wide-flow-rate continuous mixing system as described in claim 1, characterized in that, It also includes a level gauge, which is installed inside the mixing tank and configured to detect the liquid level height inside the mixing tank, and the level gauge is electrically connected to the controller.

7. The control method for a wide-flow-rate continuous mixing system as described in any one of claims 1-6, characterized in that, include: S1. The inlet flow rate status is classified according to the detection data of the flow meter. When the detected real-time flow rate of the inlet pipe is lower than or equal to the set threshold, it is determined to be a low flow rate status; when the detected real-time flow rate of the inlet pipe is higher than the set threshold, it is determined to be a high flow rate status; the threshold is 50-60% of the maximum inlet flow rate. S2. In the low flow state, close the control valve located on the second branch pipe, and adjust the opening of the control valve on the first branch pipe according to the detection data of the flow meter. The opening increases as the real-time flow of the inlet pipe increases. S3. Under high flow conditions, control the opening of the control valve located on the first branch pipe to 100%, open the control valve located on the second branch pipe, and adjust the opening of the control valve on the second branch pipe according to the detection data of the flow meter. The opening of the control valve increases with the increase of the real-time flow of the inlet pipe.

8. The control method for a wide-flow-rate continuous mixing system as described in claim 7, characterized in that, In S2, the low flow state is divided into two control stages according to the set first threshold. When the detected real-time flow of the inlet pipe is lower than or equal to the first threshold, the opening of the control valve on the first branch pipe is kept at the set initial value. When the detected real-time flow rate of the inlet pipe is higher than the first threshold and lower than the boundary threshold, the opening of the control valve on the first branch pipe is controlled to change linearly with the real-time flow rate of the inlet pipe; when the detected real-time flow rate of the inlet pipe is equal to the boundary threshold, the opening of the control valve on the first branch pipe is controlled to be 100%.

9. The control method for a wide-flow-rate continuous mixing system as described in claim 7, characterized in that, In S3, the high flow rate state is divided into two control stages according to the set second threshold. When the detected real-time flow rate of the inlet pipe is lower than or equal to the second threshold, the opening of the control valve on the second branch pipe is controlled to change linearly with the real-time flow rate of the inlet pipe. When the detected real-time flow rate of the inlet pipe is higher than the second threshold, the opening of the control valves located on the first branch pipe and the second branch pipe is controlled to be 100%.

10. The control method for a wide-flow-rate continuous mixing system as described in claim 7, characterized in that, Also includes: The real-time liquid level in the mixing tank is detected by a level gauge and the detected data is transmitted to the controller for processing. The controller has preset low liquid level thresholds and high liquid level thresholds, and adjusts the opening of the corresponding control valve under different flow conditions according to the detection data of the liquid level gauge. When the detected real-time liquid level height of the mixing tank is greater than the high liquid level threshold, the opening of the corresponding control valve is reduced; when the detected real-time liquid level height of the mixing tank is less than the low liquid level threshold, the opening of the corresponding control valve is increased.

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