Oil braking method, system, terminal and medium of a liquid turboexpander

Abstract

This invention discloses a hydraulic braking method, system, terminal, and medium for a liquid turbine expander, relating to the field of expander braking technology. Its main technical solution includes: calculating the real-time hydraulic driving torque; calculating the speed deviation between the real-time speed of the braking rotor and the target speed; using the real-time hydraulic driving torque as a feedforward quantity and the speed deviation as a feedback quantity, substituting them into a dynamic matching control model to obtain the required target braking torque; adjusting the braking oil parameters of the hydraulic braking system according to the target braking torque to dynamically match the braking torque of the hydraulic braking system with the real-time hydraulic driving torque, thereby controlling the speed of the braking rotor. By introducing a composite control combining hydraulic driving torque feedforward with speed deviation PID feedback, precise matching of the braking torque and the real-time driving torque of the expander is achieved through dynamic linkage. This aims to reduce the risks of large speed control lag and large overshoot when inlet pressure and flow conditions fluctuate drastically.

Description

Technical Field

[0001] This invention relates to the field of expander braking technology, specifically to an oil braking method, system, terminal, and medium for a liquid turbine expander. Background Technology

[0002] Liquid turbine expanders are core equipment for recovering pressure energy from high-pressure liquids (such as liquefied natural gas, high-pressure chemical materials, and concentrated brine from seawater desalination). Their working principle involves using the high-pressure liquid to drive an impeller, converting pressure energy into mechanical energy to power a generator or other loads. To prevent overspeeding of the brake rotor during fluctuations in liquid flow or pressure, a reliable braking system is essential.

[0003] Existing wind brakes and electromagnetic brakes are both "passive" or "semi-open-loop" controls, which fail to perform linkage calculation and dynamic matching with the real-time driving torque of the expander. This results in significant lag and overshoot in speed control when the inlet operating conditions fluctuate drastically, affecting energy recovery efficiency and equipment safety. Summary of the Invention

[0004] The purpose of this invention is to provide an oil braking method, system, terminal, and medium for a liquid turbine expander, which solves the problem that existing braking methods fail to perform linkage calculation and dynamic matching with the real-time driving torque of the expander, resulting in significant lag and overshoot in speed control when the inlet operating conditions fluctuate drastically, affecting energy recovery efficiency and equipment safety.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] In a first aspect, a method for oil braking of a liquid turbine expander is provided, comprising the following operations:

[0007] S1, real-time acquisition of the expander's inlet pressure, outlet pressure, liquid medium volume flow rate, and brake rotor speed;

[0008] S2, based on the inlet pressure, outlet pressure, liquid medium volume flow rate and real-time rotational speed of the brake rotor, calculate the real-time hydraulic driving torque of the liquid medium acting on the impeller;

[0009] S3, obtain the preset target speed, and calculate the speed deviation between the real-time speed of the brake rotor and the target speed;

[0010] S4, the real-time hydraulic driving torque is used as a feedforward quantity, and the speed deviation is used as a feedback quantity. These are substituted into the dynamic matching control model to obtain the required target braking torque.

[0011] S5, according to the target braking torque, adjust the brake fluid parameters of the hydraulic braking system so that the braking torque of the hydraulic braking system is dynamically matched with the real-time hydraulic drive torque, and realize the control of the brake rotor speed.

[0012] A further solution is: In S2, the calculation formula for the real-time hydraulic driving torque of the liquid medium acting on the impeller is:

[0013]

[0014] in, For real-time hydraulic driving torque; These are calibration coefficients; For inlet pressure; To alleviate export pressure; This refers to the volumetric flow rate of the liquid medium. This is the real-time rotational speed of the brake rotor.

[0015] A further proposed solution is: In S4, the dynamic matching control model is:

[0016]

[0017] in, For target braking torque; For real-time hydraulic driving torque; Based on speed deviation Feedback control quantity.

[0018] A further approach is to use a PID control algorithm to control the speed deviation. Processing is performed to obtain the result based on the speed deviation. Feedback control quantity.

[0019] A further proposed solution is: before S4, a condition prediction process is included, which includes:

[0020] K1 calculates the rate of change of inlet pressure in real time;

[0021] K2, when the absolute value of the rate of change of the inlet pressure exceeds a preset threshold, corrects the target braking torque according to the rate of change of the inlet pressure.

[0022] In a second aspect, a system is provided, the system being adapted to the hydraulic braking method as described in the first aspect, the system comprising:

[0023] The acquisition module is used to execute S1 to acquire the inlet pressure, outlet pressure, liquid medium volume flow rate, and real-time rotational speed of the brake rotor of the expander in real time.

[0024] The first calculation module is used to execute S2 to calculate the real-time hydraulic driving torque of the liquid medium acting on the impeller based on the inlet pressure, outlet pressure, liquid medium volume flow rate and brake rotor real-time speed.

[0025] The second calculation module is used to execute S3 to obtain a preset target speed and calculate the speed deviation between the real-time speed of the brake rotor and the target speed.

[0026] The processing module is used to execute S4 to take the real-time hydraulic driving torque as a feedforward quantity and the speed deviation as a feedback quantity, and substitute them into the dynamic matching control model to obtain the required target braking torque.

[0027] The adjustment module is used to execute S5 to adjust the brake oil pressure or brake oil flow rate of the hydraulic braking system according to the target braking torque, so as to dynamically match the braking torque of the hydraulic braking system with the real-time hydraulic drive torque and realize the control of the brake rotor speed.

[0028] Thirdly, a terminal is provided, including a processor and a memory, the memory being used to store processor-executable instructions; wherein the processor is configured to invoke the instructions stored in the memory to perform the hydraulic braking method as described in the first aspect.

[0029] Fourthly, a computer-readable storage medium is provided having computer program instructions stored thereon, which, when executed by a processor, implement the hydraulic braking method as described in the first aspect.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] By introducing a composite control system combining hydraulic drive torque feedforward with speed deviation PID feedback, precise matching of braking torque and real-time expander drive torque is achieved. This aims to reduce risks such as large speed control lag and large overshoot when inlet pressure and flow conditions fluctuate drastically. Attached Figure Description

[0032] Figure 1 This is a schematic flowchart of an oil braking method for a liquid turbine expander in this embodiment. Detailed Implementation

[0033] The invention will now be further described with reference to the accompanying drawings.

[0034] Example 1: This example provides a method for oil braking of a liquid turbine expander, such as... Figure 1 As shown, the following operations are included:

[0035] S100. Real-time acquisition of expander inlet pressure, outlet pressure, liquid medium volume flow rate, and brake rotor speed;

[0036] For example, in implementation, the oil braking method in this embodiment is applicable to a liquid turbine expander. The liquid turbine expander includes a vertical frame, a brake rotor assembly, a liquid inlet / outlet assembly, an oil braking system, a sealing and isolation assembly, and a support bearing assembly.

[0037] The vertical body adopts an integrated cast steel vertical cylinder. The top of the cylinder is equipped with a brake chamber end cover, and the bottom of the cylinder is equipped with a bearing chamber base. The side wall of the cylinder has a liquid inlet, a liquid outlet, a brake oil inlet and outlet, and a sealing gas interface. The interior of the cylinder is divided into a brake chamber, a working chamber, and a bearing chamber in sequence from top to bottom. The vertical coaxiality error of the cylinder is ≤0.02mm to ensure that the brake rotor runs vertically without swaying.

[0038] The liquid inlet is located at the top of the working chamber, and the liquid outlet is located at the bottom of the working chamber, in order to follow the gravity flow of the liquid medium and improve the medium flow efficiency.

[0039] The brake rotor assembly includes a main shaft, an impeller disposed within the working chamber, and a brake rotor disposed within the brake chamber. The brake rotor adopts a disc-type or blade-type structure. The main shaft is integrally forged from high-strength alloy steel and is vertically arranged. The impeller is interference-fitted and keyed to the main shaft. The brake rotor is coaxially fixed to the upper end of the main shaft and rotates synchronously with the main shaft.

[0040] The liquid inlet and outlet assembly includes a high-pressure inlet pipe, a volute-type flow channel, and a low-pressure outlet pipe. The volute-type flow channel is arranged close to the inner wall of the working chamber, and its cross-section adopts a gradually changing diffuser design to adapt to the flow characteristics of the liquid medium and reduce eddy current and cavitation losses.

[0041] The hydraulic braking system includes guide ribs, a brake fluid supply unit, a flow regulating valve, and a hydraulic pressure sensor. The guide ribs are located on the inner wall of the braking chamber. The brake fluid supply unit delivers temperature-controlled hydraulic fluid into the braking chamber and regulates the brake fluid flow rate or pressure via the flow regulating valve, thereby precisely adjusting the braking torque of the hydraulic braking system to achieve closed-loop control of the spindle speed. The brake fluid used is high-temperature resistant, anti-emulsification hydraulic fluid, and it is completely isolated from other liquid media.

[0042] The sealing and isolation assembly employs a multi-stage combined seal, including a mechanical seal and a labyrinth seal positioned between the brake chamber and the working chamber, as well as a vacuum seal positioned between the working chamber and the bearing chamber. An inert sealing gas is introduced through the sealing gas interface to form a gas seal barrier, reducing the risk of brake oil seeping into the working chamber and liquid media seeping into the bearing chamber, thereby ensuring the purity of the liquid media and the bearing lubrication effect.

[0043] The support bearing assembly includes an upper radial bearing, a lower radial bearing, and a thrust bearing. The upper radial bearing is located at the bottom of the braking chamber, while the lower radial bearing and the thrust bearing are both housed within the bearing cavity. All three bearings bear the radial force of the main shaft and the axial fluid thrust. Their vertical arrangement ensures uniform stress distribution, thereby reducing the wear rate.

[0044] Using a preset sampling period (e.g., 50ms, 70ms), two pressure transmitters are used to obtain the inlet pressure of the expander. Export pressure The volumetric flow rate of the liquid medium in the expander is obtained using a vortex flow meter. And using a magnetoelectric speed sensor to obtain the real-time rotor speed of the expander. .

[0045] S200. Based on the inlet pressure, outlet pressure, liquid medium volume flow rate and real-time rotational speed of the brake rotor, calculate the real-time hydraulic driving torque of the liquid medium acting on the impeller;

[0046] In this embodiment, in S200, the calculation formula for the real-time hydraulic driving torque of the liquid medium acting on the impeller is:

[0047]

[0048] in, For real-time hydraulic driving torque; These are calibration coefficients; For inlet pressure; To alleviate export pressure; This refers to the volumetric flow rate of the liquid medium. This is the real-time rotational speed of the brake rotor.

[0049] S300. Obtain the preset target speed and calculate the speed deviation between the real-time speed of the brake rotor and the target speed;

[0050] For example, during implementation, the speed deviation The calculation formula is: ,in, For speed deviation; The target rotational speed; This is the real-time rotational speed of the brake rotor.

[0051] S400. The real-time hydraulic driving torque is used as a feedforward quantity, and the speed deviation is used as a feedback quantity. These are substituted into the dynamic matching control model to obtain the required target braking torque.

[0052] In this embodiment, in S400, the dynamic matching control model is:

[0053]

[0054] in, For target braking torque; For real-time hydraulic driving torque; Based on speed deviation Feedback control quantity.

[0055] In this embodiment, a PID control algorithm is used to control the speed deviation. Processing is performed to obtain the result based on the speed deviation. Feedback control quantity.

[0056] For example, in the implementation process, a PID control algorithm is used to control the speed deviation. Processing is performed to obtain the result based on the speed deviation. The formula for calculating the feedback control quantity is:

[0057]

[0058] in, Based on speed deviation Feedback control quantity; For speed deviation; This is the proportionality coefficient; The integral coefficient; is the differential coefficient.

[0059] S500. Adjust the brake fluid parameters of the hydraulic braking system according to the target braking torque, so as to dynamically match the braking torque of the hydraulic braking system with the real-time hydraulic drive torque, and realize the control of the brake rotor speed.

[0060] For example, during implementation, brake fluid parameters include brake fluid pressure and / or brake fluid flow rate.

[0061] When the brake fluid parameters include brake fluid pressure, it is based on the target braking torque. Based on the pre-calibrated "braking torque-brake oil pressure" characteristic curve, the corresponding control signal is output to control the flow regulating valve to change the brake oil pressure, thereby changing the brake oil pressure in the brake chamber. This allows the actual braking torque output by the hydraulic braking system to dynamically match the current real-time hydraulic drive torque, thus achieving precise closed-loop control of the rotational speed.

[0062] When the brake fluid parameters include brake fluid flow rate, it is based on the target braking torque. Based on the pre-calibrated "braking torque - brake fluid flow" characteristic curve, the corresponding control signal is output to control the flow regulating valve to change the brake fluid flow, thereby changing the brake fluid pressure in the brake chamber. This allows the actual braking torque output by the hydraulic braking system to dynamically match the current real-time hydraulic drive torque, thus achieving precise closed-loop control of the rotational speed.

[0063] When the brake fluid parameters include brake fluid pressure and brake fluid flow rate, based on the target braking torque By combining the pre-calibrated "braking torque-brake oil pressure" characteristic curve and "braking torque-brake oil flow rate", the corresponding control signal is output to control the flow regulating valve to change the brake oil pressure and brake oil flow rate, thereby changing the brake oil pressure in the brake chamber. This allows the actual braking torque output by the hydraulic braking system to dynamically match the current real-time hydraulic drive torque, thus achieving precise closed-loop control of the rotational speed.

[0064] The hydraulic braking method for the liquid turbine expander in this embodiment employs two key aspects. First, it introduces a composite control system combining hydraulic drive torque feedforward with speed deviation PID feedback to achieve precise dynamic matching between the braking torque and the expander's real-time drive torque. This aims to reduce risks such as large speed control lag and overshoot when inlet pressure and flow conditions fluctuate drastically. Second, by real-time acquisition of multi-source parameters such as inlet / outlet pressure, medium flow rate, and rotor speed, the real-time hydraulic drive torque is calculated more accurately. Combined with a dynamic matching control model, the brake oil pressure / flow rate is closed-loop controlled to achieve high-precision steady-state control of the rotor speed. This aims to reduce overspeed risks and ensure equipment operational safety. Furthermore, the braking torque can be dynamically matched with the hydraulic drive torque in real-time, preventing speed loss or deviation from the optimal operating point due to fluctuations in operating conditions. This allows the expander to operate near its optimal efficiency point, maximizing the conversion of liquid pressure into mechanical energy and significantly improving the expander's energy recovery and utilization rate.

[0065] In this embodiment, before S400, there is also a condition prediction process, which includes:

[0066] K100. Real-time calculation of the rate of change of inlet pressure;

[0067] K200. When the absolute value of the rate of change of the inlet pressure exceeds a preset threshold, the target braking torque is corrected according to the rate of change of the inlet pressure.

[0068] For example, during implementation, the formula for correcting the target braking torque based on the rate of change of the inlet pressure is as follows:

[0069] ,

[0070] in, The corrected target braking torque; For real-time hydraulic driving torque; Based on speed deviation Feedback control quantity; The preset feedforward enhancement coefficient; This represents the rate of change of inlet pressure.

[0071] The hydraulic braking method for the liquid turbine expander in this embodiment has two main aspects. First, by calculating the inlet pressure change rate in real time, it identifies severe disturbances such as sudden pressure rises and falls in advance. This aims to achieve proactive prediction and intervention before speed deviations occur, thereby reducing the lag in the combined hydraulic drive torque feedforward and speed deviation PID feedback control. Second, when the absolute value of the inlet pressure change rate exceeds a threshold, the pressure change rate and feedforward enhancement coefficient are introduced to pre-correct and compensate the target braking torque, and the braking torque is matched in the initial stage of severe operating condition fluctuations. This aims to significantly reduce speed shocks, peak overshoot, and oscillation amplitude, thereby improving speed stability. Third, for scenarios with instantaneous pressure changes and large operating condition disturbances, such as LNG and high-pressure chemical fluids, pre-correction based on operating condition prediction allows the braking torque to adjust synchronously with the pressure change trend. This aims to reduce the risk of rotor overspeed and speed instability due to sudden operating condition changes, thereby significantly improving the equipment's anti-disturbance adaptability.

[0072] Example 2: This example provides a system applicable to the hydraulic braking method described in Example 1. The system includes an acquisition module, a first calculation module, a second calculation module, a processing module, and an adjustment module.

[0073] The acquisition module executes S100 to acquire the inlet pressure, outlet pressure, liquid medium volumetric flow rate, and real-time rotational speed of the brake rotor of the expander in real time. The first calculation module executes S200 to calculate the real-time hydraulic driving torque of the liquid medium acting on the impeller based on the inlet pressure, outlet pressure, liquid medium volumetric flow rate, and real-time rotational speed of the brake rotor. The second calculation module executes S300 to acquire a preset target rotational speed and calculate the rotational speed deviation between the real-time rotational speed of the brake rotor and the target rotational speed. The processing module executes S400 to use the real-time hydraulic driving torque as a feedforward quantity and the rotational speed deviation as a feedback quantity, and substitute them into the dynamic matching control model to obtain the required target braking torque. The adjustment module executes S500 to adjust the brake oil pressure or brake oil flow rate of the hydraulic braking system according to the target braking torque, so as to dynamically match the braking torque of the hydraulic braking system with the real-time hydraulic driving torque and realize the control of the brake rotor rotational speed.

[0074] In this embodiment, the system employs a composite control approach. Firstly, it incorporates a hydraulic drive torque feedforward combined with speed deviation PID feedback to achieve precise dynamic matching between the braking torque and the expander's real-time drive torque. This aims to reduce risks such as large speed control lag and overshoot when inlet pressure and flow conditions fluctuate drastically. Secondly, by real-time acquisition of multi-source parameters such as inlet / outlet pressure, medium flow rate, and rotor speed, the system more accurately calculates the real-time hydraulic drive torque. Combined with a dynamic matching control model, it achieves closed-loop regulation of brake oil pressure / flow rate, enabling high-precision steady-state control of the rotor speed. This aims to reduce overspeed risks and ensure equipment operational safety. Thirdly, the braking torque can dynamically match the hydraulic drive torque in real-time, preventing speed loss or deviation from the optimal operating point due to fluctuations in operating conditions. This allows the expander to operate closer to its optimal efficiency point, maximizing the conversion of liquid pressure into mechanical energy and significantly improving the expander's energy recovery and utilization rate.

[0075] In this embodiment, a terminal is also provided, including a processor and a memory, the memory being used to store processor-executable instructions; wherein the processor is configured to invoke the instructions stored in the memory to execute the oil braking method as described in Embodiment 1.

[0076] In this embodiment, a computer-readable storage medium is also provided, on which computer program instructions are stored, which, when executed by a processor, implement the hydraulic braking method as described in Embodiment 1.

[0077] Although the invention has been described herein with reference to several illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope and spirit of the principles disclosed herein. More specifically, various variations and modifications can be made to the components and / or layout of the subject matter arrangement within the scope of the disclosure, drawings, and claims. Besides variations and modifications to the components and / or layout, other uses will be apparent to those skilled in the art.

Claims

1. A method for oil braking of a liquid turbine expander, characterized in that, Includes the following operations: S1, real-time acquisition of the expander's inlet pressure, outlet pressure, liquid medium volume flow rate, and brake rotor speed; S2, based on the inlet pressure, outlet pressure, liquid medium volume flow rate and real-time rotational speed of the brake rotor, calculate the real-time hydraulic driving torque of the liquid medium acting on the impeller; S3, obtain the preset target speed, and calculate the speed deviation between the real-time speed of the brake rotor and the target speed; S4, the real-time hydraulic driving torque is used as a feedforward quantity, and the speed deviation is used as a feedback quantity. These are substituted into the dynamic matching control model to obtain the required target braking torque. S5, according to the target braking torque, adjust the brake fluid parameters of the hydraulic braking system so that the braking torque of the hydraulic braking system is dynamically matched with the real-time hydraulic drive torque, and realize the control of the brake rotor speed.

2. The hydraulic braking method according to claim 1, characterized in that, In S2, the formula for calculating the real-time hydraulic driving torque of the liquid medium acting on the impeller is: ； in, For real-time hydraulic driving torque; These are calibration coefficients; For inlet pressure; To alleviate export pressure; This refers to the volumetric flow rate of the liquid medium. This is the real-time rotational speed of the brake rotor.

3. The hydraulic braking method according to claim 2, characterized in that, In S4, the dynamic matching control model is: ； in, For target braking torque; For real-time hydraulic driving torque; Based on speed deviation Feedback control quantity.

4. The hydraulic braking method according to claim 3, characterized in that: The PID control algorithm is used to control the speed deviation. Processing is performed to obtain the result based on the speed deviation. Feedback control quantity.

5. The hydraulic braking method according to claim 3, characterized in that, Before S4, there is also a condition prediction process, which includes: K1 calculates the rate of change of inlet pressure in real time; K2, when the absolute value of the rate of change of the inlet pressure exceeds a preset threshold, corrects the target braking torque according to the rate of change of the inlet pressure.

6. A system, characterized in that, The system is applicable to the hydraulic braking method as described in any one of claims 1-5, and the system comprises: The acquisition module is used to execute S1 to acquire the inlet pressure, outlet pressure, liquid medium volume flow rate, and real-time rotational speed of the brake rotor of the expander in real time. The first calculation module is used to execute S2 to calculate the real-time hydraulic driving torque of the liquid medium acting on the impeller based on the inlet pressure, outlet pressure, liquid medium volume flow rate and brake rotor real-time speed. The second calculation module is used to execute S3 to obtain a preset target speed and calculate the speed deviation between the real-time speed of the brake rotor and the target speed. The processing module is used to execute S4 to take the real-time hydraulic driving torque as a feedforward quantity and the speed deviation as a feedback quantity, and substitute them into the dynamic matching control model to obtain the required target braking torque. The adjustment module is used to execute S5 to adjust the brake oil pressure or brake oil flow rate of the hydraulic braking system according to the target braking torque, so as to dynamically match the braking torque of the hydraulic braking system with the real-time hydraulic drive torque and realize the control of the brake rotor speed.

7. A terminal, characterized in that, include: A processor and a memory, wherein the memory is used to store processor-executable instructions; The processor is configured to invoke instructions stored in the memory to execute the hydraulic braking method as described in any one of claims 1-5.

8. A computer-readable storage medium having computer program instructions stored thereon, characterized in that, When the computer program instructions are executed by the processor, the oil braking method as described in any one of claims 1-5 is implemented.

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