A water pump operation method based on demand feedback

Abstract

The present invention discloses a method for intelligent operation of water pumps based on demand feedback, and provides a method for intelligent control of water pumps that can be adjusted at any time according to the demand for water volume and water pressure, and is efficient in energy saving and carbon reduction. It mainly includes: an industrial control host, a router, a frequency converter, a water supply pump, a flow meter capable of remote communication, and a water pipe network. The purpose of the present invention is to solve the technical problems of random changes in flow and pressure in the water supply pipe network system, supplying the required water pump head and flow on demand, and not wasting energy due to overpressure water supply. The present invention also discloses the application of the method for intelligent operation of water pumps based on demand feedback in the real-time adjustment of water pump water supply according to the demand of the water pipe network, reducing oversupply, and saving energy and reducing carbon. Experimental results show that when water pump control and adjustment are carried out according to this method, energy saving of 10% to 30% can be achieved on the basis of existing frequency conversion, and electricity consumption and carbon emissions can be reduced.

Description

Technical Field

[0001] The present invention belongs to the technical fields of urban water supply, building water supply, heating, sewage lifting, agricultural irrigation, chemical industry, metallurgy, etc., and relates to the operation of centrifugal water pumps with intelligent control, and in particular to a method for intelligent operation of water pumps based on demand feedback. Background Art

[0002] Water pumps are widely used in various aspects of production and life, including urban water supply, building water supply, heating, sewage lifting, agricultural irrigation, chemical industry, and metallurgy. Their carbon emissions and energy consumption are among the highest in society. Therefore, energy conservation and emission reduction of water pumps are crucial to my country's comprehensive implementation of a green and low-carbon development strategy.

[0003] As a fluid transport equipment, water pump energy saving can be achieved by, on the one hand, improving the water pump structure, reducing mechanical loss and leakage loss, and increasing the effective utilization rate of shaft power; on the other hand, energy saving can be achieved by using a frequency converter to adjust the operating status of the water pump. Currently, the most widely used technology is variable frequency speed regulation and constant pressure water supply technology.

[0004] The reason for the introduction of variable frequency speed regulation constant pressure water supply technology is that the design flow and design head during pump design and selection are often considered based on the most unfavorable conditions. The application principle of this technology is as follows: before the water pump is put into operation, the operating pressure and other relevant operating parameters of the water pump are first set based on the water supply pressure that meets the most unfavorable point. During the operation of the water pump, the pressure sensor continuously collects the water pressure and water pressure change rate signals in the pipe network and transmits them to the variable frequency control system. The control system compares and calculates the feedback signal with the set pressure. If the actual pressure is lower than the set pressure, the control system issues a command to control the water pump to accelerate. If the actual pressure is higher than the set pressure, the control system controls the water pump to decelerate. When the set pressure is reached, the water pump maintains the operating frequency. Since the speed is proportional to the cube of the pump shaft power, the energy efficiency of the water pump after deceleration is very significant.

[0005] The existing variable frequency speed regulation constant pressure water supply technology has certain technical defects. Since it does not take into account the situation where the actual required water supply head of the pipe network system is reduced due to flow reduction and no flow at non-unfavorable points, the system cannot achieve variable frequency speed regulation water supply. Summary of the Invention

[0006] To solve the above problems, the present invention discloses a water pump intelligent operation method based on demand feedback, which is characterized by the following steps:

[0007] (1) Collect the as-built drawings of the water supply system and its design parameters, the elevation of each water point, water consumption and minimum working pressure, pipe materials and length;

[0008] (2)Collect the factory performance test data of the selected water supply pumps, including the flow rate, head, water power, input power, working voltage, working current, current frequency, motor speed, and pump efficiency parameters under different working conditions;

[0009] (3)Use the proportionality law to calculate the corresponding flow rate and head of the pump at different speeds, and draw the H-Q curve;

[0010] (4)Use the Hazen-Williams formula Design the calculation model Mod of the pipeline frictional head loss corresponding to different flow rates, pipe lengths, pipe diameters, and pipe materials ;

[0011] In the Hazen-Williams formula: q is the design flow rate, Ch is the Hazen-Williams coefficient, which is related to the pipe material, dj is the calculated inner diameter of the pipe, and l is the calculated pipe length;

[0012] (5)Use the formula Design the calculation model Mod of the local head loss corresponding to different pipe diameters and pipe fittings ; In the formula: is the pipeline frictional head loss, is the sum of the local loss coefficients of the pipe fittings, is the flow velocity.

[0013] (6)At the main branch node 1 of the water supply network, add a remotely communicable flowmeter and number it as Q1. According to the completion drawing, number the different pipe sections from the pump outlet to the flowmeter Q1 as 1, 2,..., k, with lengths of L'1, L'2,..., L'k respectively. Input their pipe inner diameters as d'1, d'2,..., d'k respectively, and perform pipe material matching for the k pipe sections. Input the elevation and minimum working head at Q1, and input the elbow pipe fitting parameters and numbers connecting the pipe sections L'1, L'2,..., L'k;

[0014] (7)At the main branch node 2 of the water supply network, repeat step (6). The numbers of the same pipe sections and pipe fittings as in (6) must be unique and not repeated or contradictory;

[0015] (8)According to the method in (7), add remotely communicable flowmeters to the n main branch nodes in the water supply network, numbered as Qi (where: 3 ≤ i ≤ n), number the flowmeters, pipe sections, and pipe fittings, and establish an input database.

[0016] (9)When s (0 < s ≤ n) water usage nodes have outflow, the corresponding x flowmeters will have data displayed and be transmitted to the industrial control host through the router. In the industrial control host, Mod and Mod Start the simulation. During the calculation, the flow rates of pipe sections and fittings with the same number are added together, ultimately calculating the corresponding head loss Hy and local head loss Hj at different flowmeter nodes. Using the corresponding data in the database, calculate the corresponding static pressure head Hz at different flowmeter nodes and match it with the required working head Hx. At different flowmeter nodes, add the above four heads together: Hy + Hj + Hz + Hx to obtain the output database. Select the maximum head Hmax from the calculation results as the operating head of the pump. Add the flow rates of X flowmeters and the resulting flow value Qmax is used as the operating flow rate of the pump.

[0017] (10) In the HQ spectrum of the water pump in the industrial control host, use Qmax as the horizontal coordinate and Hmax as the vertical coordinate to accurately find the coordinate points of Qmax and Hmax and their corresponding speeds. Calculate the current frequency; the industrial control host transmits the calculated current frequency value to the water pump's frequency converter through the router. The water pump motor operates according to the frequency converter's instructions, achieving frequency conversion control, meeting the flow and head requirements of the pipe network system, and achieving the goal of energy conservation and carbon reduction. Among them: is the current frequency, is the motor speed, is the number of pole pairs of the motor's rotating magnetic field.

[0018] This invention further discloses a demand-feedback-based intelligent pump operation method for real-time adjustment of water supply to the water network's demand, reducing oversupply and achieving energy conservation and carbon reduction. Experimental results show that using this method to control and adjust pumps can save 10% to 30% of energy compared to existing variable frequency drives, reducing electricity consumption and carbon emissions.

[0019] This invention addresses the technical deficiencies of existing variable-frequency speed-regulating and constant-pressure water pump control systems and provides an intelligent water pump control method that can be adjusted to meet water volume and pressure requirements, resulting in high efficiency, energy savings, and carbon reduction. The method primarily includes an industrial control host, a router, a frequency converter, a water supply pump, a flow meter capable of remote communication, and a water pipe network.

[0020] The purpose of this invention is to solve the technical problem of ensuring that the required pump head and flow rate are delivered on demand, without wasting energy due to overpressure, even when the flow and pressure in a water supply network system vary randomly. The challenge lies in achieving on-demand water delivery from the pump, thus meeting water supply needs without wasting energy.

[0021] The formula for the head-flow curve of a centrifugal water pump is: It is a downward concave decreasing curve. The water pressure-flow characteristic curve of the pipe network system is: , is an upward concave increasing curve. Among them: is the pump head, is the water pressure of the pipe network system, a, b, c are the simulation parameters of different water pump performance curves; is the static water pressure of the pipe network system, and Q is the flow rate.

[0022] In the actual water supply process, in order to meet the demand for water volume and water pressure at the same time, water is often oversupplied. Figure 2 The water supply curve of the pump is 1. The current variable frequency speed regulation constant pressure water supply technology can meet the requirements of constant water supply pressure (see Figure 2 5) by reducing the pump speed (see Figure 2 2,3), under the condition of constant water supply pressure, using the proportional law Energy consumption has been greatly reduced compared with the water supply curve 1. However, since the set constant water supply pressure cannot be met, the demand of the pipe network is not met. Figure 2 The low speed operation condition of the middle water supply curve 6 is not achievable. In view of the above difficulties and reasons, the present invention is proposed. is the shaft power of the pump, is the speed of the water pump motor.

[0023] The more detailed technical contents and implementation methods of the present invention are as follows:

[0024] (1) The completed drawings and design parameters of the water supply system (including water pumps and their pipe networks) shall be collected, including but not limited to water pump parameters, water pump installation height, suction tank design water level, water pump inlet and outlet pipe diameters, lengths, number of elbows and tees and their parameters, elevation of each water point, water consumption and minimum working pressure, pipe materials and lengths, etc.

[0025] (2) Collect the factory performance test data of the selected water supply pump, including but not limited to flow rate, head, water power, input power, operating voltage, operating current, current frequency, motor speed, pump efficiency and other parameters under different working conditions.

[0026] (3) Using the proportionality law, calculate the flow rate and head corresponding to different pump speeds, and draw the HQ curve. Taking a multi-stage centrifugal pump as an example, draw the following head (H)-flow rate (Q) graph and input it into the industrial control host.

[0027] (4) Using the Hezen-Williams formula ( ), design different flow rates, different pipe lengths, pipe diameters, different pipe materials, and the corresponding pipeline head loss calculation model Mod In the Hezen-Williams formula, q is the design flow rate, Ch is the Hezen-Williams coefficient, which is related to the pipe material, dj is the calculated inner diameter of the pipe, and l is the calculated pipe length.

[0028] (5) Using the formula , design local head loss calculation models Mod for different pipe diameters and different pipe fittings ; Where: is the head loss along the pipeline is the sum of local loss coefficients of pipe fittings is the flow velocity.

[0029] (6) At the main branch node 1 of the water supply network, add a flowmeter with remote communication capabilities, and number it as Q1. According to the completion drawing, number the different pipe sections from the pump outlet to the flowmeter Q1 as 1, 2, …… k, and their lengths are L1, L2, …… L k , input their inner diameters of the pipes as d1, d2, …… d k , and perform pipe material matching for the k pipe sections, input the elevation and the lowest working head at Q1, input the elbow pipe fitting parameters and numbers connecting the L1, L2, …… L k pipe sections;

[0030] (7) At the main branch node 2 of the water supply network, repeat step (6). The numbers of the same pipe sections and pipe fittings as in (6) must be unique and cannot be repeated or contradictory;

[0031] (8) According to the method in (7), add flowmeters with remote communication capabilities to the n main branch nodes in the water supply network, and their numbers are Qi (where: 3 ≤ i ≤ n), number the flowmeters, pipe sections, and pipe fittings, and establish an input database.

[0032] (9) When s (0 < s ≤ n) water consumption nodes have outflows, the corresponding x (x ≤ s) flowmeters will have data displayed, and the data will be transmitted to the industrial control host through the router. The Mod and Mod are started to begin simulation calculations; during the calculation, the flows of the pipe sections and pipe fittings with the same number are superimposed, and finally the head loss along the pipeline Hy and the local head loss Hj corresponding to different flowmeter nodes are calculated; using the corresponding data in the database, calculate the static head Hz corresponding to different flowmeter nodes and match it with the required working head Hx; at different flowmeter nodes, add the above four heads together, Hy + Hj + Hz + Hx, to obtain the output database; select the maximum head Hmax of the calculation results as the operating head of the pump; add the flows of the X flowmeters together, and the obtained flow value Qmax is used as the operating flow of the pump;

[0033] (10) In the H-Q diagram of the pump in the industrial control host, with Qmax as the abscissa and Hmax as the ordinate, accurately find the coordinate point of Qmax, Hmax, and its corresponding rotational speed, using Calculate the current frequency; the industrial control host transmits the calculated current frequency value to the water pump's frequency converter through the router. The water pump motor operates according to the instructions of the frequency converter to achieve frequency conversion control, meet the flow and head requirements of the pipe network system, and achieve the operation purpose of energy saving and carbon reduction; is the current frequency is the motor speed is the number of pole pairs of the motor's rotating magnetic field.

[0034] Compared to existing constant-pressure variable-frequency regulation technologies, the demand-feedback-based intelligent pump operation method disclosed in this invention offers the following positive benefits: It reduces energy waste caused by preset excess pressure, maximizing energy conservation and carbon reduction. The pump supply can be adjusted in real time based on the demand of the water network, reducing energy waste associated with excess supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart of the water pump intelligent operation method based on demand feedback;

[0036] Figure 2 The head (pressure)-flow curve of the centrifugal water pump and the water supply network; 1 is the head-flow curve when the centrifugal water pump speed is n0, 2 is the head-flow curve when the centrifugal water pump speed is n1 (n0>n1), 3 is the head-flow curve when the centrifugal water pump speed is n2 (n1>n2), 4 is the pressure-flow demand relationship curve of the water supply network system, 5 is the constant water supply pressure and pressure-flow curve set by the variable frequency centrifugal water pump, and 6 is the head-flow curve when the centrifugal water pump speed is n3 (n2>n3);

[0037] Figure 3 This is the HQ map of a water pump in the industrial control host;

[0038] Figure 4 This is the water distribution system diagram of Example 2. DETAILED DESCRIPTION

[0039] The present invention is described below by way of specific embodiments. Unless otherwise specified, the technical means used in the present invention are methods well known to those skilled in the art. In addition, the embodiments should be understood to be illustrative rather than limiting the scope of the present invention, the spirit and scope of the present invention being limited only by the claims. For those skilled in the art, various changes or modifications to the material components and dosages in these embodiments, without departing from the spirit and scope of the present invention, also fall within the scope of protection of the present invention. The raw materials and reagents used in the present invention are all commercially available.

[0040] Example 1

[0041] A method for intelligent operation of water pumps based on demand feedback:

[0042] (1) Collect the as-built drawings of the water supply system and its design parameters, the elevation of each water point, water consumption and minimum working pressure, pipe materials and length;

[0043] (2) Collect the factory performance test data of the selected water supply pump, including flow rate, head, water power, input power, working voltage, working current, current frequency, motor speed, and pump efficiency parameters under different working conditions;

[0044] (3) Using the proportionality law, calculate the flow rate and head corresponding to different pump speeds and draw the HQ curve;

[0045] (4) Using the Hezen-Williams formula ( ), design different flow rates, different pipe lengths, pipe diameters, different pipe materials, and the corresponding pipeline head loss calculation model Mod ;

[0046] In the Hezen-Williams formula: q is the design flow rate, Ch is the Hezen-Williams coefficient, which is related to the pipe material, dj is the calculated inner diameter of the pipe, and l is the calculated pipe length;

[0047] (5) Using the formula , design the local head loss calculation model Mod for different pipe diameters and different pipe fittings Where: is the head loss along the pipeline, is the sum of the local loss coefficients of the pipe fittings, is the flow rate.

[0048] (6) At the main branch node 1 of the water supply network, add a flow meter capable of remote communication and number it Q1. According to the completion drawing, the different pipe sections from the water pump outlet to the flow meter Q1 are numbered 1, 2, ... k, and their lengths are L1, L2, ... L k , input the inner diameters of the pipes as d1, d2, ...d k , and match the pipe materials for k pipe sections, input the elevation and minimum working head at Q1, input the connections L1, L2, ... L k Parameters and numbers of elbow fittings of pipe sections;

[0049] (7) Repeat step (6) at the main branch node 2 of the water supply network. The numbers of the same pipe sections and fittings as in (6) must be unique and must not be repeated or contradictory.

[0050] (8) According to the method in (7), flow meters capable of remote communication are added to n main branch nodes in the water supply network, which are numbered Qi (where: 3≤i≤n). The flow meters, pipe sections, and pipe fittings are numbered and an input database is established.

[0051] (9) When s (0 < s ≤ n) water-using nodes have outflows, x (x ≤ s) corresponding flow meters will display data and transmit it to the industrial control host through a router. The Mod in the industrial control host and Mod are started to begin simulation calculations. During the calculation, for pipe segments and pipe fittings with the same number, their flows are superimposed, and finally the corresponding frictional head loss Hy and local head loss Hj at different flow meter nodes are calculated. Using the corresponding data in the database, the static head Hz corresponding to different flow meter nodes is calculated and matched with the required working head Hx. At different flow meter nodes, the sum of the above four heads Hy + Hj + Hz + Hx can obtain the output database. Select the maximum head Hmax of the calculation results as the operating head of the water pump. Add up the flows of the X flow meters, and the obtained flow value Qmax is used as the operating flow of the water pump;

[0052] (10) In the H-Q diagram of the water pump in the industrial control host, with Qmax as the abscissa and Hmax as the ordinate, accurately find the coordinate point of Qmax, Hmax, and its corresponding rotational speed. Using calculate the current frequency. The industrial control host transmits the calculated current frequency value to the frequency converter of the water pump through the router, and the water pump motor operates according to the instructions of the frequency converter to achieve variable frequency control, meet the flow and head requirements of the pipe network system, and achieve the operating purpose of energy conservation and carbon reduction. Among them is the current frequency is the motor speed is the number of pole pairs of the rotating magnetic field of the motor.

[0053] Embodiment 2

[0054] Actual application example

[0055] For a 21-story office building with district water supply, the 13th to 21st floors are the high-rise area. The ground elevation of the 13th floor is 55.4 m, and the floor height of each floor above is 4 m. There is a fire water tank on the top floor of the 21st floor with an effective water depth of 4 m. The selected water supply pump is a light vertical multi-stage centrifugal pump, with a rated flow Q = 20 m 3 / h, a rated head of H = 106 m, and a rated power of P = 11 kW. The pump room is located in the basement on the first floor, the lowest operating water level of the water collection tank is -4 m, the water outlet pipe of the water pump is a thin-walled stainless steel pipe with a diameter of DN100, and the water distribution system diagram is shown in Figure 4 . Intelligent control implementation method:

[0056] (1) The industrial control host inputs the head (H)-flow (Q) diagram of the selected water pump, the frictional head loss calculation model Mod and the local head loss calculation model Mod 。

[0057] (2)According to the completion drawing, number all remotely communicable flow meters of the branch pipes from the 13th floor to the roof (Q1~Q 10 ), and input the elevation and minimum working head corresponding to each flow meter.

[0058] (3)Number all the water supply main pipes from the water pump to the roof (L1~L 10 ), and number all the water distribution branch pipes from all branch nodes on the 13th floor to the roof to the flow meters (LZ1~LZ 10 ). Corresponding input of pipe diameter, pipe length, material, and the type and quantity of its pipe fittings for all pipe segments.

[0059] (4)All the above data form a corresponding input database and are stored in the industrial control host.

[0060] (5)When there is out - flow at i (0 < i ≤ 10) water - using nodes in the pipe network system, the corresponding i flow meters will display data, and the data will be transmitted to the industrial control host through the router. Mod and Mod in the industrial control host are started to begin the simulation calculation of Hy and Hj; at the same time, using the corresponding data in the input database, calculate the matching of Hz and Hx to obtain the output database. The output database contains i different lift and i flow rate data. Select the maximum lift as the operating lift Hmax of the water pump, and select the sum of the i flow rates as the operating flow rate Qmax of the water pump.

[0061] (6)Case 1: When there is flow out at the 13th, 15th, 16th floors and the roof, the displayed values of Q1, Q3, Q4, Q 10 , are respectively: 0.7 L / s, 0.2 L / s, 0.2 L / s, 1 L / s. The above flow rate data is transmitted through the router, and the industrial control host calculates and finally determines that Hmax = 102.1 m, Qmax = 7.56 m 3 / h. The industrial control host compares with the H - Q diagram of the selected water pump, and finally determines that the operating frequency f of the water pump = 47.25 Hz, and the shaft power N = 5.4 kW. If the constant - pressure variable - frequency regulation technology is adopted to meet the water supply demand of the roof, the operating power of the water pump is f = 49 Hz, and the shaft power N = 6.0 kW. It can be seen that the former saves about 10% more energy than the latter.

[0062] (7)Case 2: When there is flow out at the 13th, 15th, 16th floors, the displayed values of Q1, Q3, Q4 are respectively: 0.7 L / s, 0.2 L / s, 0.2 L / s. The above flow rate data is transmitted through the router, and the industrial control host calculates and finally determines that Hmax = 78.0 m, Qmax = 3.96 m 3 / h. The industrial control host compared the HQ spectrum of the selected water pump and ultimately determined the pump's operating frequency f = 41 Hz and shaft power N = 3.7 kW. If constant-voltage variable-frequency regulation technology is used to meet rooftop water supply requirements, the pump's operating power would be f = 46.5 Hz and shaft power N = 4.7 kW. This demonstrates that the former saves approximately 21.3% in energy compared to the latter.

Claims

1. A water pump intelligent operation method based on demand feedback, characterized in that Follow these steps: (1) Collect the as-built drawings of the water supply system and its design parameters, the elevation of each water point, water consumption and minimum working pressure, pipe materials and length; (2) Collect the factory performance test data of the selected water supply pump, including flow rate, head, water power, input power, working voltage, working current, current frequency, motor speed, and pump efficiency parameters under different working conditions; (3) Using the proportionality law, calculate the flow rate and head corresponding to different pump speeds and draw the HQ curve; (4) Using the Hezen-Williams formula Design different flow rates, different pipe lengths, pipe diameters, and different pipe materials, and the corresponding pipeline head loss calculation model Mod ; In the Hezen-Williams formula: is the head loss along the pipeline, For the design flow rate, is the Hezen-Williams coefficient, which is related to the pipe material. Calculate the inside diameter for the pipe, To calculate the pipe length; (5) Using the formula Design a local head loss calculation model Mod for different pipe diameters and different pipe fittings Where: is the head loss along the pipeline, is the sum of the local loss coefficients of the pipe fittings, is the flow rate; (6) At the main branch node 1 of the water supply network, add a flow meter capable of remote communication and number it Q1. According to the completion drawing, the different pipe sections from the water pump outlet to the flow meter Q1 are numbered 1, 2, ... k, and their lengths are L1, L2, ... L k , input the inner diameters of the pipes as d1, d2, ...d k , and match the pipe materials for k pipe sections, input the elevation and minimum working head at Q1, input the connections L1, L2, ... L k Parameters and numbers of elbow fittings of pipe sections; (7) Repeat step (6) at the main branch node 2 of the water supply network. The numbers of the same pipe sections and fittings as in (6) must be unique and must not be repeated or contradictory. (8) According to the method in (7), add flow meters capable of remote communication to n main branch nodes in the water supply network, numbering them as Qi, where: 3≤i≤n, number the flow meters, pipe sections, and pipe fittings, and establish an input database; (9) When s (0 < s ≤ n) water-using nodes have outflows, the corresponding x (x ≤ s) flow meters will display data and transmit it to the industrial control host through the router. In the industrial control host, Mod and Mod is started to begin simulation calculations. During the calculations, for pipe segments and pipe fittings with the same number, their flows are superimposed, and finally the corresponding frictional head loss Hy and local head loss Hj at different flow meter nodes are calculated. Using the corresponding data in the database, the static head Hz corresponding to different flow meter nodes is calculated and matched with the required working head Hx. At different flow meter nodes, the sum of the above four heads Hy + Hj + Hz + Hx gives the output database. The maximum head Hmax of the calculation results is selected as the operating head of the water pump. The sum of the flows of X flow meters is calculated, and the obtained flow value Qmax is used as the operating flow of the water pump. (10) In the HQ spectrum of the water pump in the industrial control host, use Qmax as the horizontal coordinate and Hmax as the vertical coordinate to accurately find the coordinate points of Qmax and Hmax, and their corresponding speeds. Calculate the current frequency; the industrial control host transmits the calculated current frequency value to the water pump's frequency converter through the router. The water pump motor operates according to the frequency converter's instructions, achieving frequency conversion control, meeting the flow and head requirements of the pipe network system, and achieving the goal of energy conservation and carbon reduction. Among them: is the current frequency, is the motor speed, is the number of pole pairs of the motor's rotating magnetic field.

2. The application of the demand feedback-based intelligent operation method of water pumps as described in claim 1 in real-time adjustment of water pump water supply according to the demand of the water network, reduction of oversupply, energy saving and carbon reduction.

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