Fire pump system, cavitation monitoring method thereof and storage medium

Abstract

The invention discloses a fire pump system and a cavitation monitoring method thereof and a storage medium, and belongs to the technical field of fire fighting, the fire pump system comprises a fire pump, an inlet pressure gauge and an outlet pressure gauge are respectively arranged at an inlet and an outlet of the fire pump; the water inlet pipe is connected with the reservoir and an inlet of the fire pump; the water outlet pipe is connected with an outlet of the fire pump; the port pressure gauge is arranged at a water inlet port of the water inlet pipe; and the control unit is electrically connected with the port pressure gauge, the inlet pressure gauge and the outlet pressure gauge. The problem that in the prior art, cavitation monitoring and warning cannot be well conducted in combination with the specific service scene of the fire pump is solved.

Description

Technical Field

[0001] This invention relates to the field of fire protection technology, and more specifically, to a fire pump system and its cavitation monitoring method and storage medium. Background Technology

[0002] Fire pump systems are crucial fire protection infrastructure, typically employing centrifugal pumps as their core power source. Water is drawn from natural water sources or reservoirs through the inlet pipe, pressurized by the pump body, and then delivered to the fire scene through the outlet pipe. Once started, the operation of a fire pump is dynamically affected by changes in external environmental factors. If a malfunction occurs during operation, it will seriously threaten the smooth progress of firefighting efforts. Therefore, online status monitoring and fault early warning for fire pump systems are essential.

[0003] Cavitation is a common risk and failure during the operation of fire pumps. Once cavitation occurs, it will affect the flow rate and head of the fire pump, causing a high risk of impeller damage and resulting in significant vibration and noise. Current technologies cannot effectively integrate cavitation monitoring and alarms with the specific service scenarios of fire pumps.

[0004] In view of this, the present invention provides a fire pump system and its cavitation monitoring method and storage medium to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a fire pump system and its cavitation monitoring method and storage medium, which solves the problem that the existing technology cannot effectively combine the specific service scenarios of fire pumps for cavitation monitoring and alarm.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a fire pump system, comprising: The fire pump is equipped with an inlet pressure gauge and an outlet pressure gauge, respectively. The water inlet pipe connects the water storage tank to the inlet of the fire pump; The water outlet pipe is connected to the outlet of the fire pump; A pressure gauge is installed at the inlet port of the inlet pipe; The control unit is electrically connected to the port pressure gauge, inlet pressure gauge, and outlet pressure gauge.

[0007] A further preferred embodiment is that the inlet pressure gauge and the outlet pressure gauge are installed at the same height.

[0008] A further preferred embodiment is that the control unit can receive human information input and output information in the form of at least one of text, images, and sound.

[0009] A further preferred embodiment is that the fire pump is a centrifugal pump.

[0010] Secondly, the present invention also provides a method for monitoring cavitation in a fire pump system, applied to the aforementioned fire pump system, comprising the following steps: S1. Measure the initial height difference ΔZ0 between the fire pump and the water level in the storage tank before system startup; S2. Taking system startup as time t=0, perform the following operations in real time at each sampling time t=i×Δt: S2.1, Measurement port pressure Pa i Import pressure Pb i Export pressure Pc i ; S2.2 Calculate the head H i =(Pc i -Pb i ) / (ρg); S2.3, Calculate the flow rate Q by back-calculating the preset head-flow rate relationship H=f(Q). i ; S2.4 Calculate the real-time elevation difference Z i =ΔZ0+(Pa0-Pa i ) / (ρg); S2.5 Calculate the inlet pipe resistance coefficient k i =(Pa i -Pb i -Z i ρg) / Q i 2 ; S2.6, if k i If / k0 is greater than the preset threshold, an inlet pipe fault is indicated; S3. Based on the data from the period t=(im)×Δt to t=i×Δt, the average flow rate Q is calculated. i-m, i =(Q i-m +Q i-m+1 +…+Q i ) / (m+1); Water transfer volume V i-m, i =mΔtQ i-m, i ; Cross-sectional area S of the reservoir i-m, i =V i-m, i / (Z i-m -Z i ); S4. For each future time t = (i + j) × Δt, for j = 1, 2, ..., n, predict the elevation difference Z. i+j =Z i +jΔtQ i-m, i / S i-m, i Net Positive Suction Head (NPSH) ai+j =(P atm -P v-k i Q i-m, i 2 ) / (ρg)-Z i+j ; S5, Average flow rate Q i-m, i Substitute the preset flow rate - required net positive suction head (NPSH) relationship r =g(Q) to obtain NPSH r Predicted value; S6. Traverse j=1 to n, if there exists a minimum j min Make its corresponding effective net positive suction head (NPSH) less than NPSH r If the predicted value is obtained, a cavitation warning will be triggered and the time of its occurrence will be output. In the above, i, j, m, and n are natural numbers, Pa0 and k0 are the port pressure and inlet pipe resistance coefficient at the start-up time, respectively, Δt is the sampling time interval, and P... atm and P v Here, ρ is the standard atmospheric pressure and the vapor pressure of water, respectively; ρ is the density of water; and g is the acceleration due to gravity.

[0011] Further optimization: Back-calculating the flow rate Q i If there are multiple solutions, the solution with a positive value and located within the actual operating range of the fire pump is selected.

[0012] A further preferred embodiment is that the preset head-flow relationship H=f(Q) is a function of head with respect to flow rate fitted based on test data from the fire pump manufacturer.

[0013] A further preferred embodiment is the preset flow rate-required net positive suction head (NPSH) relationship. r =g(Q) is the required net positive suction head (NPSH) function relating to flow rate, fitted based on test data from the fire pump manufacturer.

[0014] More preferably, the sampling time interval Δt is between 5 seconds and 100 seconds, m is between 10 and 100, and n is between 20 and 500.

[0015] Thirdly, the present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of a method for monitoring cavitation in a fire pump system.

[0016] In summary, the present invention has the following beneficial effects: 1. Accurate and dynamic monitoring of cavitation risk: It can diagnose in real time whether the inlet pipe is suddenly blocked and predict when cavitation will occur in the future.

[0017] 2. Hardware design adapted to mobile scenarios: The pressure gauge measurement results at the port can be converted into the difference between the liquid level and the fire pump height. The water storage tank does not need to be equipped with a liquid level gauge. Therefore, the fire pump system is self-contained, and all data communication can be carried out in the system according to the preset method.

[0018] 3. The method of dynamically back-calculating the equivalent cross-sectional area of ​​the reservoir can automatically adapt to irregular reservoirs (such as conical pits, sloping pools, etc.) whose cross-sectional area changes with depth.

[0019] 4. The inlet and outlet pressure gauges also have the function of indirect flow measurement. The current flow rate can be inferred from the pressure difference between the two gauges, which replaces the precision and expensive flow meter.

[0020] The monitoring and alarm method provided by this invention is as follows: by measuring pressure data and elevation difference in real time, combined with pre-stored pump characteristic curves and cavitation condition tables, the current flow rate, pipeline resistance coefficient, and flow rate and inlet pressure under extreme operating conditions are calculated. If the extreme flow rate is lower than a preset threshold or the inlet pressure is less than the critical cavitation value, an alarm is triggered. This invention solves the problems of insufficient flow rate and inaccurate cavitation risk monitoring caused by increased pipeline resistance or decreased water level in field water intake systems, achieving automated and highly reliable status assessment and early warning. This invention takes "dynamic parameter calculation" as its core, and through a three-pressure gauge hardware layout + fluid dynamics model + rolling prediction algorithm, it addresses the pain points of mobile fire fighting—eliminating the need for pre-installed sensors in water storage tanks and adapting to irregular water sources; it achieves cavitation prediction decision-making—quantifying the time from early warning to cavitation occurrence, reversing the traditional post-event reporting and intervention model. Ultimately, it provides a cost-effective, highly adaptable, and predictable cavitation monitoring solution for fire pump systems, and is particularly suitable for mobile fire pump application scenarios. Attached Figure Description

[0021] Figure 1 This is a structural block diagram of the fire-fighting water supply system in an embodiment of the present invention; Figure 2 This is a flowchart of the fire pump system cavitation monitoring method in an embodiment of the present invention; Figure 3 The present invention provides flow-head test data and fitting curves of fire pumps in embodiments of the present invention. Figure 4 This presents the flow rate-required net positive suction head (NPSH) test data and fitting curves of the fire pump in this embodiment of the invention.

[0022] In the diagram, 1. Water storage tank; 2. Port pressure gauge; 3. Inlet pipe; 4. Inlet pressure gauge; 5. Fire pump; 6. Outlet pressure gauge; 7. Outlet pipe; 8. Control unit.

[0023] Figure 1 In the image, the arrows indicate the direction of water flow. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings.

[0025] like Figure 1 As shown, a fire-fighting water supply system is used to draw water from a reservoir 1 near a fire scene and pressurize it for output. The system includes a fire pump 5, an inlet pipe 3, an outlet pipe 7, a port pressure gauge 2, an inlet pressure gauge 4, an outlet pressure gauge 6, and a control unit 8. The fire pump 5 is a centrifugal pump; its inlet is used to draw water from the reservoir 1, and its outlet is used to output pressurized water. An inlet pressure gauge 4 and an outlet pressure gauge 6 are fixedly installed at the inlet and outlet respectively to measure the pressure data at the pump's inlet and outlet in real time. The inlet pipe 3 is a flexible or rigid pipe, with one end connected to the reservoir 1 and the other end sealed to the inlet of the fire pump 5, used to transport water from the reservoir 1 to the inlet of the fire pump 5. The length of the inlet pipe 3 can be flexibly adjusted according to the site conditions to adapt to different water intake distances. One end of the outlet pipe 7 is sealed to the outlet of the fire pump 5, and the other end is connected to fire-fighting equipment (such as fire hoses, water guns, etc.), used to transport the pressurized water to the fire scene.

[0026] The port pressure gauge 2 is fixedly installed on the outer wall of the inlet pipe 3 near the inlet port, without extending into the inlet pipe 3 or obstructing the water inlet path, thus avoiding the impact of water flow impact on the accuracy of pressure measurement. Its core function is to measure the static pressure at the inlet port of the inlet pipe 3, providing data support for calculating the real-time height difference between the liquid level in the water storage tank 1 and the fire pump 5. The control unit 8 adopts an industrial-grade electronic computer or a dedicated control module, which is electrically connected to the port pressure gauge 2, the inlet pressure gauge 4, and the outlet pressure gauge 6 via wired or wireless means, respectively. It can receive the measurement data of each pressure gauge in real time. It also has human-machine interaction function, which can receive manually input initial parameters (such as initial height difference ΔZ0, preset threshold, etc.) and output measurement data, fault prompts, and warning information in the form of text, images, and sound through components such as touch screen and speaker.

[0027] In one specific embodiment, the inlet pressure gauge 4 and the outlet pressure gauge 6 are installed at the same height and are both on the same horizontal plane as the geometric center of the fire pump 5 inlet and outlet. This eliminates the influence of height difference on pressure measurement and ensures the accuracy of head calculation. The fire pump system is a vehicle-mounted mobile system that can be integrated into a fire truck for easy rapid transportation and deployment according to the needs of the fire scene. The inlet pipe 3 can flexibly extend into various types of outdoor water storage tanks 1 to draw water, demonstrating strong adaptability.

[0028] In one specific embodiment, the control unit 8 is an electronic computer that obtains the measurement results of the port pressure gauge 2, the inlet pressure gauge 4, and the outlet pressure gauge 6 in real time via wired communication; receives manual information input via a touch screen; and outputs information externally via text and image display on the touch screen and sound output from the speaker.

[0029] In the above technical solution, the inlet pressure gauge 4 and outlet pressure gauge 6 are installed at the same height and are coplanar with the geometric centers of the inlet and outlet of the fire pump 5. This effectively eliminates the interference of the installation height difference on pressure measurement, ensures the accuracy of head calculation, and provides reliable basic data support for subsequent flow back calculation, resistance coefficient calculation, and cavitation monitoring, avoiding deviations in monitoring results caused by pressure measurement errors. The port pressure gauge 2 adopts a non-intrusive installation on the outer wall, which not only avoids the impact of water flow impact on measurement accuracy but also accurately collects the static pressure at the inlet port, providing a feasible solution for real-time height difference calculation in irregular outdoor water storage tanks 1 without pre-installed liquid level sensors. The control unit 8 integrates data receiving, calculation, interaction, and early warning functions, realizing real-time acquisition and automated processing of data from each pressure gauge, reducing manual intervention, and improving monitoring efficiency. The system adopts a vehicle-mounted mobile design, which can be quickly transported to the fire scene and flexibly deployed. The water inlet pipe 3 can be easily extended into various types of field water storage tanks 1 to draw water, effectively solving the pain points of inconvenient water draw at field fire scenes and poor compatibility of monitoring equipment. It greatly improves the mobility, adaptability and practicality of the fire water supply system, and provides a stable and reliable water supply guarantee and monitoring support for the smooth conduct of fire fighting operations.

[0030] A method for monitoring cavitation in a fire pump system, applied to the aforementioned fire pump system, such as... Figure 1-4 As shown, it includes the following steps: S1. Before the system starts, the initial height difference ΔZ0 between the geometric center of the fire pump 5 inlet and the free liquid surface of the water storage tank 1 is measured by the rope measuring method, ultrasonic logging tool measurement method or laser rangefinder measurement method, and the initial height difference is input into the control unit 8. S2. Taking the system startup time as t=0, set the sampling time interval Δt, and perform the following operations in real time at each sampling time t=i×Δt (i is a natural number): S2.1 Measure the port pressure (Pa) using port pressure gauge 2, inlet pressure gauge 4, and outlet pressure gauge 6 respectively. i Import pressure Pb i Export pressure Pc i The measurement data is then transmitted to the control unit 8. S2.2, Control Unit 8 according to formula H i =(Pc i -Pb i ) / (ρg) calculates the current head H i , where ρ is the density of water and g is the acceleration due to gravity; S2.3, Control Unit 8 calculates the current flow rate Q based on the pre-stored head-flow rate relationship H=f(Q). i The head-flow relationship H=f(Q) is a function of head with respect to flow rate fitted based on test data from the fire pump manufacturer; specifically, it is a quadratic function. S2.4, Control Unit 8 according to formula Z i =ΔZ0+(Pa0-Pa i ) / (ρg) Calculate the real-time elevation difference Z i Where Pa0 is the port pressure at system startup time (t=0); S2.5, Control Unit 8 according to formula k i =(Pa i -Pb i -Z i ρg) / Q i 2 Calculate the current inlet pipe resistance coefficient k i Q i 2 Current traffic Q i The square of; S2.6, Control Unit 8 calculates k i The ratio of the inlet pipe resistance coefficient k0 at the system startup time, if k i If / k0 is greater than the preset threshold, the human-machine interaction module will prompt an inlet pipe fault. S3 and Control Unit 8 perform the following calculation operations based on historical data within the time period from t=(im)×Δt to t=i×Δt (m is a natural number, ranging from 10 to 100): S3.1 Calculate the average flow rate Q during this period. i-m,i =(Q i-m +Q i-m+1 +…+Q i ) / (m+1); S3.2 Calculate the water transfer volume V during this period. i-m,i =m×Δt×Q i-m,i ; S3.3, According to formula S i-m,i =V i-m,i / (Z i-m -Z i Calculate the equivalent cross-sectional area S of reservoir 1 during this period. i-m,i Z i-m The real-time elevation difference at time t = (im) × Δt; S4 and Control Unit 8 perform the following prediction operation for n future sampling times (j=1, 2, ..., n, where n is a natural number with a value of 20-500), i.e., time t=(i+j)×Δt: S4.1, According to formula Z i+j =Z i +j×Δt×Q i-m,i / S i-m,i Predict the real-time elevation difference Z at each future moment i+j ; S4.2, According to formula (NPSH) ai+j =(P atm -P v -k i ×Q i-m,i 2 ) / (ρg)-Z i+j Calculate the effective net positive suction head (NPSH) at each future time point. ai+j , where P atm P is the standard atmospheric pressure. v Q is the vaporization pressure of water. i-m,i 2 Average flow rate Q i-m,i The square of; S5, Control Unit 8 will average flow rate Q i-m,i Substitute the pre-stored flow rate - required net positive suction head (NPSH) relationship r =g(Q), to obtain the required net positive suction head (NPSH). r Predicted value; S6, Control Unit 8 iterates through all future moments from j=1 to n, if there exists a minimum j min , so that j min The corresponding effective net positive suction head (NPSH) is less than NPSH. r If the predicted value is obtained, a cavitation warning will be triggered, and the estimated time of cavitation occurrence, t=(i+j), will be output through the human-computer interaction module. min )×Δt.

[0031] Furthermore, in step S2.3, the flow rate Q is calculated backwards. i If multiple solutions exist, the solution with a positive value that is within the actual working flow range of fire pump 5 shall be selected.

[0032] Furthermore, the sampling time interval Δt ranges from 5 seconds to 100 seconds, and the vaporization pressure of water P v Using standard values ​​at room temperature, ρ = 1000 kg / m³, g = 9.8 N / kg.

[0033] Furthermore, the preset flow rate-required net positive suction head (NPSH) relationship... r =g(Q) is the functional relationship between the required net positive suction head (NPSH) and the flow rate, fitted based on test data from the fire pump manufacturer. Specifically, it is a quadratic function.

[0034] In one specific embodiment, the initial height difference ΔZ0 between the fire pump 5 and the water level in the storage tank 1 is obtained using the rope measuring method. The specific operation steps are as follows: (1) Prepare tools: Find a rope with a length mark, and attach a weight to the first end as a counterweight; (2) Make the measuring rope: Mark the rope, with the initial end marked as 0; (3) Connecting the circuit: Place the second end of the measuring rope at the same height as the fire pump 5 and connect it to the resistance setting of a multimeter. Connect the other end of the multimeter to the ground. (4) Lowering the measuring rope: Slowly lower the counterweight end into the water storage tank 1; (5) Detecting water level: When the counterweight contacts the water surface, the measuring rope forms a loop through the well water and the ground, and the multimeter pointer will swing or the light will light up; (6) Read data: Retrieve the measuring rope, read the length mark of the wet part of the measuring rope, and calculate the vertical distance between the water surface and the fire pump 5.

[0035] A computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of a cavitation monitoring method for a fire pump system. The storage medium can be a USB flash drive, portable hard drive, read-only memory (ROM), random access memory (RAM), hard disk, etc., and can be used to store the program code of the monitoring method, facilitating its recall and execution by the control unit 8, thereby automating the monitoring process.

[0036] This invention applies theoretical knowledge and principles of fluid mechanics and centrifugal pumps. The following section focuses on a detailed explanation of each step in the cavitation monitoring method for fire pump systems.

[0037] The main starting point of this invention is that while the fire pump system starts normally, changes in the suction pipe during operation may occur due to certain factors, leading to increased resistance and potential cavitation risks. Therefore, monitoring and alarm / / or warnings are necessary. The factors considered are mainly twofold: first, the inlet pipe may be blocked by foreign objects or bend due to unforeseen circumstances, causing a sharp increase in its resistance coefficient and a decrease in the effective net positive suction head (NPSH); second, the water in the storage tank 1 is continuously pumped away by the fire pump 5, causing a drop in the liquid level, increasing the suction head of the fire pump 5, and further reducing the effective NPSH. Once the effective NPSH exceeds the required NPSH, cavitation will occur.

[0038] Considering that the diameters of the inlet pipe, outlet pipe, and pump inlet / outlet are usually not significantly different, the technical solution of this invention approximately ignores the changes in the dynamic pressure energy of the liquid at each point. For a certain section of pipe, the pressure difference between its two ends is proportional to the square of the flow rate, and the proportionality coefficient is defined as its resistance coefficient.

[0039] In the technical solution of this invention, the system startup time is t=0, the current time is t=i×Δt, and the future time is t=(i+j)×Δt. All measurements, calculations, judgments, and alarms are executed in a rolling manner with a time interval of Δt.

[0040] Before system startup, measure the initial height difference ΔZ0 between fire pump 5 and the liquid level in water storage tank 1.

[0041] The time t = i × Δt is the current time. The main purpose is to calculate and record the current head H based on the measured value. i Current traffic Q i Current elevation difference Z i Current inlet pipe resistance coefficient k i This information can serve two purposes: firstly, it can be used for future data projections; secondly, it can be used to analyze the current inlet pipe resistance coefficient k. i The ratio of the inlet pipe resistance coefficient k0 at the system startup time is used to determine whether the inlet pipe is always normal. If the ratio is greater than the preset threshold, it indicates that the inlet pipe resistance suddenly increases during the operation of the fire pump system, which is likely related to foreign object blockage. Therefore, an alarm is triggered to indicate an inlet pipe fault.

[0042] Furthermore, considering that the flow rate during operation may experience some random fluctuations, in order to more accurately and objectively extrapolate future data, it is necessary to select the recent period from t=(im) ×Δt to t=i×Δt to calculate the average flow rate Q. i-m, i and water transfer volume V i-m, i And by the water transport volume V i-m, i With average flow Q i-m, i The ratio of the effective cross-sectional area S of the reservoir in the recent period is obtained. i-m, i .

[0043] Based on this, we perform prediction calculations for each time point t=(i+j)×Δt in the future time period from t=(i+1)×Δt to t=(i+n)×Δt, and approximately assume that the flow rate and the cross-sectional area of ​​reservoir 1 in the future time period are always the average flow rate Q of the recent time period. i-m, i and the cross-sectional area S of the water storage tank i-m, i The inlet pipe resistance coefficient will remain constant at the current inlet pipe resistance coefficient k during the future period. i Therefore, the elevation difference Z is first calculated based on the volume conservation principle. i+j Then calculate the effective net positive suction head (NPSH) separately. ai+j And the required net positive suction head (NPSH) prediction r Predicted value.

[0044] Finally, determine whether cavitation will occur in the future. If it does, issue an alarm and simultaneously output the cavitation occurrence time information. Specifically, it iterates through j=1 to n, and if a minimum j exists... min Make its corresponding effective net positive suction head (NPSH) less than NPSH r If the predicted value is obtained, a cavitation warning will be triggered and the time of its occurrence will be output. From the predicted time of cavitation occurrence, it can be determined how long the fire pump system can continue to operate normally at the current flow rate, thus providing on-site personnel with crucial information about firefighting capabilities.

[0045] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] Example 1: Please refer to Figure 1-4 This embodiment describes the fire-fighting water intake system and its monitoring and alarm methods in detail.

[0047] In this embodiment, the fire pump system draws water from a water storage tank 1. The fire pump 5 is a constant-speed centrifugal pump, model CDF100-240A (manufacturer: Hunan Kailite Pump Industry Co., Ltd.), with a rated flow rate Q. n =0.06m 3 / s, the actual working flow range of fire pump 5 is 0.01 m³ / s. 3 / s to 0.09 m 3 / s. In this embodiment, the flow rate and head are both in SI units, and the vaporization pressure of the water intake is P. v =3170Pa, density of water ρ=1000kg / m³ 3 The acceleration due to gravity is g = 9.8 N / kg.

[0048] Figure 3 The points in the diagram represent the head H values ​​measured at different flow rates Q during the pre-shipment testing of fire pump 5. The curve represents the fitted function curve, and the fitted function expression is H=f(Q)=AQ. 2 +BQ+C=-2689.4Q 2 -73.258Q+70.283, that is, A=-2689.4, B=-73.258, C=70.283.

[0049] Figure 4 The points in the diagram represent the required net positive suction head (NPSH) measured at different flow rates Q during the pre-shipment testing of fire pump 5. r The value represents the fitted function curve, and the fitted function expression is NPSH. r =g(Q)=114.39Q 2 -2.265Q+2.018.

[0050] It should be noted that the above head-flow rate relationship H=f(Q) and required net positive suction head (NPSH)-flow rate relationship are... r =g(Q) are two different performance parameters of the centrifugal pump, obtained by fitting a suitable functional expression based on test data. Head H characterizes the pump's work capacity, defined as the increase in energy gained per unit weight of liquid passing through the pump, usually denoted by the symbol H, with units of meters (m); while the required net positive suction head (NPSH)... rThe NPSH (Potential Energy Standard) characterizes the pump's resistance to cavitation. It is defined as the excess energy exceeding the vaporization pressure that a unit weight of liquid at the pump's inlet must possess to prevent cavitation at a given flow rate. r This is an inherent characteristic of pumps, and it typically increases with increasing flow rate. Therefore, the head H and the required net positive suction head (NPSH) are... r The different patterns of change in flow rate Q lead to different coefficients in the function expressions obtained by fitting the test data. In this Example 1, a quadratic function is used for fitting, which is merely one example.

[0051] Before the system was started, the initial height difference ΔZ0 between the geometric center of the fire pump 5 inlet and the liquid level of the water tank 1 was measured manually using the rope measuring method, which was 2.00m.

[0052] The sampling time interval was set to Δt = 50s. Taking system startup as the time t = 0 × Δt = 0, and i = 0 (i.e., t = 0) as an example, the following gauge pressure values ​​were measured: Port pressure Pa0 = 2.94 × 10⁻⁶. 4 Pa, inlet pressure Pb0 = -2.7 × 10 3 Pa, outlet pressure Pc0 = 5.9 × 10 5 Pa, therefore the head H0 is calculated as H0 = (Pc0 - Pb0) / (ρg) = [5.9 × 10 Pa]. 5 -(-2.7×10 3 )] / (9.8×10 3 =60.48m. Based on the preset head-flow relationship H=f(Q), the flow rate Q0 is calculated as follows: Q0=[-B-sqrt(B 2 -4A(C-H0))] / (2A)=[73.258-sqrt(73.258 2 +4×2689.4×(70.283-60.48))] / (-2×2689.4)=0.048m 3 / s.

[0053] Calculate the real-time elevation difference Z0 = ΔZ0 + (Pa0 - Pa0) / (ρg) = ΔZ0 = 2.00m; Calculate the inlet pipe resistance coefficient k0 = (Pa0 - Pb0 - Z0ρg) / Q i 2 =(2.94×10 4 +2.7×10 3 -2.00×9.8×10 3 ) / 0.048 2 =5.43×10 6 .

[0054] At time t=1×Δt=50s, with i=1 (i.e., t=50s), the following gauge pressure value is measured: Port pressure Pa1=2.842×10 4 Pa, inlet pressure Pb1 = -2.9 × 10 3 Pa, outlet pressure Pc1 = 6.0 × 10 5 Pa, therefore the head H1 = (Pc1 - Pb1) / (ρg) = [6.0 × 10 Pa] is calculated. 5 -(-2.9×10 3 )] / (9.8×10 3 =61.52m. Based on the preset head-flow relationship H=f(Q), the flow rate Q1 is calculated as follows: Q1=[-B-sqrt(B 2 -4A(C-H1))] / (2A)=[73.258-sqrt(73.258 2 +4×2689.4×(70.283-61.52))] / (-2×2689.4)=0.045m 3 / s.

[0055] Calculate the real-time elevation difference Z1 = ΔZ0 + (Pa0 - Pa1) / (ρg) = 2.00 + (2.94 × 10⁻¹⁰) 4 -2.842×10 4 ) / (9.8×10 3 =2.00 + 0.10 = 2.10m; Calculate the inlet pipe resistance coefficient k1 = (Pa1 - Pb1 - Z1ρg) / Q1 2 =(2.842×10 4 +2.9×10 3 -2.10×9.8×10 3 ) / 0.045 2 =5.30×10 6 .

[0056] Therefore, k1 / k0 = 5.30 × 10 6 / 5.43×10 6 =0.976, which is less than its preset threshold of 1.3, so there is no inlet pipe fault at t=50s.

[0057] In this embodiment, m=10 and n=20. When the time reaches t=i×Δt=15×50=750s, the following calculations are made based on the data from the period from t=5×Δt to t=15×Δt, i.e., from t=250s to t=750s: 1) Average flow rate Q i-m, i =0.050m 3 / s; 2) Water transfer volume Vi-m, i =mΔtQ i-m, i =10×50×0.05=25m 3 ; 3) The cross-sectional area S of the water storage tank 1 i-m, i =V i-m, i / (Z i-m -Z i )=25 / (Z5-Z 15 )=20m 2 .

[0058] The average flow rate Q i-m, i =0.050m 3 Substitute / s into the preset flow rate - required net positive suction head (NPSH) relationship r =g(Q)=114.39Q 2 NPSH is obtained by calculating -2.265Q + 2.018. r The predicted value is 2.19m.

[0059] For each future time point j=1, 2, ..., n, i.e., time t=(i+j) ×Δt, that is, for time points t=16×50=800s, t=17×50=850s, ..., t=35×50=1750s respectively, calculate the corresponding elevation difference Z. i+j And effective net positive suction head (NPSH) ai+j Iterate through j from 1 to 20 and find that there exists a minimum j. min =16 makes its corresponding effective net positive suction head (NPSH) less than NPSH r The predicted value triggers a cavitation warning and outputs the occurrence time t = (15 + 16) × 50 = 1550s. Since the current time has reached t = i × Δt = 15 × 50 = 750s, the remaining time is 1550 seconds. 750 = 800s. To make it easier for users, the display shows the text "Cavitation is expected to occur in 800 seconds" and simultaneously emits a warning sound.

[0060] It should be noted that the measured and calculated values ​​in this embodiment are real-time and continuously updated, and can be applied to water storage tanks 1 of various shapes as well as situations where water storage tank 1 is simultaneously replenished and pumped.

[0061] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A fire pump system, characterized in that: include: The fire pump is equipped with an inlet pressure gauge and an outlet pressure gauge, respectively. The water inlet pipe connects the water storage tank to the inlet of the fire pump; The water outlet pipe is connected to the outlet of the fire pump; A pressure gauge is installed at the inlet port of the inlet pipe; The control unit is electrically connected to the port pressure gauge, inlet pressure gauge, and outlet pressure gauge.

2. A fire pump system according to claim 1, characterized in that: The inlet pressure gauge and the outlet pressure gauge are installed at the same height.

3. A fire pump system according to claim 1, characterized in that: The control unit can receive human information input and output information in the form of at least one of text, images, and sound.

4. A fire pump system according to claim 1, characterized in that: The fire pump is a centrifugal pump.

5. A method for monitoring cavitation in a fire pump system, applied to any one of the fire pump systems described in claims 1-4, characterized in that: Includes the following steps: S1. Measure the initial height difference ΔZ0 between the fire pump and the water level in the storage tank before system startup; S2. Taking system startup as time t=0, perform the following operations in real time at each sampling time t=i×Δt: S2.1, Measurement port pressure Pa i Import pressure Pb i Export pressure Pc i ; S2.2 Calculate the head H i =(Pc i -Pb i ) / (ρg); S2.3, Calculate the flow rate Q by back-calculating the preset head-flow rate relationship H=f(Q). i ; S2.4 Calculate the real-time elevation difference Z i =ΔZ0+(Pa0-Pa i ) / (ρg); S2.5 Calculate the inlet pipe resistance coefficient k i =(Pa i -Pb i -Z i ρg) / Q i 2 ; S2.6, if k i If / k0 is greater than the preset threshold, an inlet pipe fault is indicated; S3. Based on the data from the period t=(im)×Δt to t=i×Δt, the average flow rate Q is calculated. i-m, i =(Q i-m +Q i-m+1 +…+Q i ) / (m+1); Water transfer volume V i-m, i =mΔtQ i-m, i ; Cross-sectional area S of the reservoir i-m, i =V i-m, i / (Z i-m -Z i ); S4. For each future time t = (i + j) × Δt, for j = 1, 2, ..., n, predict the elevation difference Z. i+j =Z i +jΔtQ i-m, i / S i-m, i Net Positive Suction Head (NPSH) ai+j =(P atm -P v -k i Q i-m, i 2 ) / (ρg)-Z i+j ; S5, Average flow rate Q i-m, i Substitute the preset flow rate - required net positive suction head (NPSH) relationship r =g(Q) to obtain NPSH r Predicted value; S6. Traverse j=1 to n, if there exists a minimum j min Make its corresponding effective net positive suction head (NPSH) less than NPSH r If the predicted value is obtained, a cavitation warning will be triggered and the time of its occurrence will be output. In the above, i, j, m, and n are natural numbers, Pa0 and k0 are the port pressure and inlet pipe resistance coefficient at the start-up time, respectively, Δt is the sampling time interval, and P... atm and P v Here, ρ is the standard atmospheric pressure and the vapor pressure of water, respectively; ρ is the density of water; and g is the acceleration due to gravity.

6. The method for monitoring cavitation in a fire pump system according to claim 5, characterized in that: Back-inferring traffic Q i If there are multiple solutions, the solution with a positive value and located within the actual operating range of the fire pump is selected.

7. A method for monitoring cavitation in a fire pump system according to claim 5, characterized in that: The preset head-flow relationship H=f(Q) is a function of head with respect to flow rate fitted based on test data from the fire pump manufacturer.

8. A method for monitoring cavitation in a fire pump system according to claim 5, characterized in that: The preset flow rate-required net positive suction head (NPSH) relationship r =g(Q) is the required net positive suction head (NPSH) function relating to flow rate, fitted based on test data from the fire pump manufacturer.

9. A method for monitoring cavitation in a fire pump system according to claim 5, characterized in that: The sampling time interval Δt is between 5 seconds and 100 seconds, m is between 10 and 100, and n is between 20 and 500.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by the processor, it implements the steps of the fire pump system cavitation monitoring method as described in any of claims 5-9.

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