Balanced proportion mixing system based on PLC control

Abstract

The invention belongs to the field of fire fighting equipment, and particularly discloses a PLC (programmable logic controller) control-based balance proportion mixing system which comprises a Venturi tube, a PLC, a variable frequency water pump and a variable frequency gear pump, the PLC is used for executing the following steps that S1, the use proportion of foam liquid and the output pressure of the variable frequency water pump are obtained; s2, the water flow output by the variable frequency water pump is obtained; s3, the ideal output flow of the foam liquid is obtained through calculation; s4, the flow of foam liquid output by the variable frequency gear pump is obtained; s5, comparing the flow of the foam liquid with the ideal output flow of the foam liquid; through a closed-loop control mechanism of the PLC and dynamic adjustment of the variable-frequency water pump and the variable-frequency gear pump, real-time accurate control over the mixing proportion of foam liquid and water is achieved, operation parameters of the water pump and the gear pump are automatically corrected based on real-time feedback of pressure and flow data, and it is ensured that the mixing proportion error is controlled within the extremely small range.

Description

Technical Field

[0001] The invention belongs to the field of fire-fighting equipment, and in particular relates to a balanced proportion mixing system based on PLC control. Background Art

[0002] In the field of fire protection, foam fire extinguishing systems extinguish fires through a mixture of foam liquid and water, and the accuracy of the mixing ratio directly affects the fire extinguishing effect.

[0003] Traditional foam proportion mixing systems usually use mechanical adjustment methods and rely on manual settings or fixed-ratio structural designs, making it difficult to dynamically adjust the mixing ratio according to actual working conditions. When faced with flow fluctuations and changes in foam liquid properties, the ratio cannot be automatically calibrated, which can easily lead to reduced fire extinguishing efficiency or equipment failure. In addition, traditional systems lack real-time monitoring and feedback adjustment mechanisms, and cannot dynamically calibrate key parameters such as water pump pressure and flow, further affecting mixing accuracy and system stability. Summary of the Invention

[0004] The purpose of the present invention is to provide a balanced proportion mixing system based on PLC control to solve the problem that the traditional foam proportion mixing system proposed in the above background technology cannot dynamically calibrate key parameters such as water pump pressure and flow, and is difficult to dynamically adjust the mixing ratio according to actual working conditions.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A balanced proportion mixing system based on PLC control, comprising a venturi tube, a PLC controller, a variable frequency water pump and a variable frequency gear pump;

[0007] The venturi tube is used for mixing the foam liquid with water;

[0008] The water inlet end of the variable frequency water pump is connected to the outlet end of the venturi tube, the inlet end of the venturi tube is connected to the water source, and the adsorption chamber inlet of the venturi tube is connected to the foam source through the variable frequency gear pump;

[0009] The PLC controller is used to perform the following steps:

[0010] S1. Obtain the usage ratio of the foam liquid and the output pressure of the variable frequency water pump;

[0011] S2. Sending control command 1 to the variable frequency water pump according to the output pressure of the variable frequency water pump, and obtaining the water flow output by the variable frequency water pump;

[0012] S3. Calculating an ideal output flow rate of the foam liquid according to the usage ratio of the water flow rate and the foam liquid;

[0013] S4, sending a second control command to the variable frequency gear pump according to the ideal output flow rate of the foam liquid, and obtaining the foam liquid flow rate output by the variable frequency gear pump;

[0014] S5. Compare the foam liquid flow rate with the ideal output flow rate of the foam liquid, and update the second control command according to the comparison result until the foam liquid flow rate is equal to the ideal output flow rate of the foam liquid.

[0015] Preferably, the ideal output flow rate of the foam liquid is calculated by the following formula:

[0016]

[0017] Among them, x is the usage ratio of foam liquid, Q1 is the water flow rate, and Q3 is the ideal output flow rate of foam liquid.

[0018] Preferably, the step of sending the second control command to the variable frequency gear pump according to the ideal output flow rate of the foam liquid includes:

[0019] Calculate the AC frequency used by the variable frequency gear pump when it outputs this flow rate, and send a one-time frequency instruction to the variable frequency gear pump based on the AC frequency. The formula is as follows:

[0020]

[0021] Among them, f 泡 is the AC frequency of the variable frequency gear pump, Q3 is the ideal output flow of the foam liquid, Q 齿 is the rated flow of the variable frequency gear pump.

[0022] Preferably, the output pressure of the variable frequency water pump is obtained by the following formula:

[0023] P=K1×Q 2

[0024] Among them, P is the output pressure of the variable frequency water pump, K1 is a constant calculated from the performance parameters of the variable frequency water pump, and Q is the output flow rate of water.

[0025] Preferably, the step of sending a control command to the variable frequency water pump according to the output pressure of the variable frequency water pump comprises:

[0026] Calculate the AC frequency used by the variable frequency water pump when it outputs this pressure, and send a one-time frequency instruction to the variable frequency water pump based on the AC frequency. The formula is as follows:

[0027]

[0028] Among them, P is the output pressure of the variable frequency water pump, K1 is a constant, which is calculated from the performance parameters of the variable frequency water pump, and f 水is the AC power frequency of the variable frequency water pump.

[0029] Preferably, after the control command 1 is sent to the variable frequency water pump according to the output pressure of the variable frequency water pump, the real-time pressure of the variable frequency water pump is measured by a pressure sensor, and the real-time pressure of the variable frequency water pump is compared with the ideal output pressure of the variable frequency water pump. The control command 1 is updated according to the comparison result until the real-time pressure of the variable frequency water pump is equal to the ideal output pressure of the variable frequency water pump.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention realizes real-time and precise control of the mixing ratio of foam liquid and water through the closed-loop control mechanism of the PLC controller, combined with the dynamic adjustment of the variable-frequency water pump and the variable-frequency gear pump. The foam liquid usage ratio can be modified in real time through the human-machine interface to quickly adapt to the needs of different types of foam liquid or changes in fire intensity. Based on the real-time feedback of pressure and flow data, the operating parameters of the water pump and gear pump are automatically corrected through PID control logic to ensure that the mixing ratio error is controlled within an extremely small range.

[0032] The present invention combines the negative pressure adsorption effect of the venturi tube with the secondary stirring of the water pump impeller to improve the mixing uniformity of the foam liquid and water and enhance the fire extinguishing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0034] Figure 1 It is a structural flow chart of the present invention. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0036] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0037] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0038] As attached Figure 1 As shown:

[0039] Example 1: This example provides a balanced proportion mixing system based on PLC control, including a venturi tube, a PLC controller, a variable frequency water pump and a variable frequency gear pump;

[0040] The venturi tube is used to mix the foam liquid with water;

[0041] The water inlet of the variable frequency water pump is connected to the outlet of the venturi tube, the inlet of the venturi tube is connected to the water source, and the adsorption chamber inlet of the venturi tube is connected to the foam source through the variable frequency gear pump;

[0042] When the variable frequency water pump is running, it draws water into the Venturi tube and outputs the mixed foam mixture to the nozzle or ignition point. The variable frequency gear pump is used to transport the foam liquid to the inlet of the adsorption chamber of the Venturi tube. The Venturi tube is set at the water inlet end of the variable frequency water pump, so that the water flow first passes through the Venturi tube when it is sucked into the variable frequency water pump. When the water flow passes through the Venturi tube, the flow rate increases through its tapering section, thereby forming a negative pressure in its adsorption chamber, sucking the foam liquid into the water flow and mixing it with the water flow to obtain a foam mixture;

[0043] Since the Venturi tube is set at the water inlet end of the variable frequency water pump, after the variable frequency water pump is started, the adsorption chamber of the Venturi tube is always in a negative pressure state. Even if the flow rate of the foam mixture is small, it can still be ensured that the foam liquid is sucked into the Venturi tube and mixed with water to form a foam mixture. After the initial mixing, it enters the variable frequency water pump and is stirred and mixed twice by the impeller of the variable frequency water pump, so that the foam liquid and water are fully mixed to achieve the best fire extinguishing effect.

[0044] The PLC controller is used to perform the following steps:

[0045] S1. Obtain the usage ratio of the foam liquid and the output pressure of the variable frequency water pump;

[0046] S2. Send control command 1 to the variable frequency water pump according to the output pressure of the variable frequency water pump, and obtain the water flow output by the variable frequency water pump through the flow sensor;

[0047] S3. Calculate the ideal output flow rate of the foam liquid based on the usage ratio of water flow rate to foam liquid;

[0048] The ideal output flow rate of the foam liquid is calculated by the following formula:

[0049]

[0050] Among them, x is the usage ratio of foam liquid, Q1 is the water flow rate, and Q3 is the ideal output flow rate of foam liquid.

[0051] S4. Sending control command 2 to the variable frequency gear pump according to the ideal output flow rate of the foam liquid, and obtaining the foam liquid flow rate output by the variable frequency gear pump through the flow sensor;

[0052] Sending control command 2 to the variable frequency gear pump according to the ideal output flow of the foam liquid includes:

[0053] Calculate the AC frequency used by the variable frequency gear pump when it outputs this flow rate, and send a one-time frequency instruction to the variable frequency gear pump based on the AC frequency. The formula is as follows:

[0054]

[0055] Among them, f 泡 is the AC frequency of the variable frequency gear pump, Q3 is the ideal output flow of the foam liquid, Q 齿 is the rated flow of the variable frequency gear pump.

[0056] S5. Compare the foam liquid flow rate with the ideal output flow rate of the foam liquid, and update the second control command according to the comparison result until the foam liquid flow rate is equal to the ideal output flow rate of the foam liquid.

[0057] Specifically, the output pressure of the variable frequency water pump is obtained by the following formula:

[0058] P=K1×Q 2

[0059] Among them, P is the output pressure of the variable frequency water pump, K1 is a constant calculated from the performance parameters of the variable frequency water pump, and Q is the output flow rate of water.

[0060] The system is controlled by a PLC controller. The relevant input values ​​and measured values ​​in the device can be displayed on the external touch screen of the PLC controller as needed. The data is real-time and accurate. It supports real-time modification of parameters during the fire extinguishing process to adapt to the switching of foam types or changes in fire intensity, making it convenient for staff to view and adjust data, such as:

[0061] When the fire cannot be extinguished by using a foam fire extinguishing agent with a mixing ratio of 3%, it is necessary to add a foam fire extinguishing agent with a mixing ratio of 6% to the foam tank. At this time, you only need to quickly enter the corresponding value on the PLC control panel to adapt to the use of foam fire extinguishing agents with different ratios. In addition, when the foam fire extinguishing agent has insufficient foaming multiples and poor fire extinguishing performance due to product quality or storage time, you only need to enter a higher mixing ratio value on the PLC control panel to avoid the situation where the mixing ratio is constant and the number of foams produced is far less than the foam required for fire extinguishing, resulting in the inability to extinguish the fire, or the number of foams produced is far higher than the foam required for fire extinguishing, resulting in blockage of equipment pipelines.

[0062] Specifically, sending a control command to the variable frequency water pump according to the output pressure of the variable frequency water pump includes:

[0063] Calculate the AC frequency used by the variable frequency water pump to output this pressure, and send a one-time frequency instruction to the variable frequency water pump based on the AC frequency. The formula is as follows:

[0064]

[0065] Among them, P is the output pressure of the variable frequency water pump, K1 is a constant, which is calculated from the performance parameters of the variable frequency water pump, and f 水 is the AC power frequency of the variable frequency water pump.

[0066] From the above, we can know that: when working, the usage ratio of the foam liquid and the output pressure of the variable frequency water pump are first input into the PLC controller, which will obtain the control instruction by calculating the AC frequency used when the variable frequency water pump outputs this pressure, and send the instruction to the variable frequency water pump, so that the variable frequency water pump runs at the specified AC frequency for 10s, and uses the flow sensor to measure the water flow output by the variable frequency water pump during the running time. Then, according to the preset foam liquid usage ratio, the output flow of the foam liquid at the water flow is calculated, and the corresponding AC frequency is calculated to obtain the control instruction. After the instruction is sent to the variable frequency gear pump, the actual output flow of the foam liquid in the foam liquid pipeline is measured by the flow sensor, and the ideal flow is compared with the actual flow. When the actual flow is less than the ideal flow, an instruction to increase the frequency is sent to the variable frequency gear pump, thereby causing the variable frequency gear pump to increase the output flow value, and vice versa, until the error between the ideal flow and the actual flow is within an acceptable range, so that the actual flow is stable within the range of the foam liquid usage ratio;

[0067] The mixing ratio is automatically adjusted in real time under PLC control to ensure the accuracy of the mixing ratio.

[0068] Example 2: This example is basically the same as the previous example, except that after control command 1 is sent to the variable frequency water pump according to the output pressure of the variable frequency water pump, the real-time pressure of the variable frequency water pump is measured by the pressure sensor, and the real-time pressure of the variable frequency water pump is compared with the ideal output pressure of the variable frequency water pump. Control command 1 is updated according to the comparison result until the real-time pressure of the variable frequency water pump is equal to the ideal output pressure of the variable frequency water pump.

[0069] As can be seen from the above, the control frequency is calculated according to the input pressure of the variable frequency water pump input by the PLC controller, and the variable frequency water pump quickly reaches the speed to output this pressure. After 10 seconds, the pressure sensor at the outlet of the variable frequency water pump measures the pressure value and feeds it back to the PLC controller. The PLC controller compares the real-time pressure with the ideal pressure. If the real-time pressure is lower than the ideal pressure, the PLC controller sends an instruction to increase the frequency to the inverter of the variable frequency water pump. The variable frequency water pump increases the speed and thus increases the pressure at its outlet until the real-time pressure is equal to the ideal pressure, at which point the output of the instruction is stopped, so that the real-time pressure value is stabilized at the required output pressure value; vice versa, if you want to increase or decrease the pressure, you only need to increase or decrease the pressure value on the control panel to make the variable frequency water pump respond quickly.

[0070] It is important to note that the construction and arrangement of the present application shown in a number of different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, directional changes, etc.) without departing substantially from the novel teachings and advantages of the subject matter described in this application. For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of the element may be inverted or otherwise changed, and the nature or number or position of the discrete elements may be altered or changed. Therefore, all such modifications are intended to be included within the scope of the present invention. The order or sequence of any process or method steps may be changed or reordered according to alternative embodiments. In the claims, any "means plus function" clause is intended to cover the structure of the function described herein, and is not only structurally equivalent but also equivalent structures. Without departing from the scope of the present invention, other replacements, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the exemplary embodiments. Therefore, the invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0071] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (i.e., those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0072] It will be appreciated that in the development of any actual embodiment, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will, for those of ordinary skill having the benefit of this disclosure, be a routine undertaking of design, fabrication, and production without undue experimentation.

[0073] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A balanced proportion mixing system based on PLC control, characterized by: Including Venturi tube, PLC controller, variable frequency water pump and variable frequency gear pump; The venturi tube is used for mixing the foam liquid with water; The water inlet end of the variable frequency water pump is connected to the outlet end of the venturi tube, the inlet end of the venturi tube is connected to the water source, and the adsorption chamber inlet of the venturi tube is connected to the foam source through the variable frequency gear pump; The PLC controller is used to perform the following steps: S1. Obtain the usage ratio of the foam liquid and the output pressure of the variable frequency water pump; S2. Sending control command 1 to the variable frequency water pump according to the output pressure of the variable frequency water pump, and obtaining the water flow output by the variable frequency water pump; S3. Calculating an ideal output flow rate of the foam liquid according to the usage ratio of the water flow rate and the foam liquid; S4, sending a second control command to the variable frequency gear pump according to the ideal output flow rate of the foam liquid, and obtaining the foam liquid flow rate output by the variable frequency gear pump; S5. Compare the foam liquid flow rate with the ideal output flow rate of the foam liquid, and update the second control command according to the comparison result until the foam liquid flow rate is equal to the ideal output flow rate of the foam liquid.

2. A PLC-controlled balanced ratio mixing system according to claim 1, characterized in that: The ideal output flow rate of the foam liquid is calculated by the following formula: Among them, x is the usage ratio of foam liquid, Q1 is the water flow rate, and Q3 is the ideal output flow rate of foam liquid.

3. The PLC-controlled balanced ratio mixing system according to claim 1, characterized in that: The sending of the second control command to the variable frequency gear pump according to the ideal output flow of the foam liquid includes: Calculate the AC frequency used by the variable frequency gear pump when it outputs this flow rate, and send a one-time frequency instruction to the variable frequency gear pump based on the AC frequency. The formula is as follows: Among them, f 泡 is the AC frequency of the variable frequency gear pump, Q3 is the ideal output flow of the foam liquid, Q 齿 is the rated flow of the variable frequency gear pump.

4. The PLC-controlled balanced ratio mixing system according to claim 1, characterized in that: The output pressure of the variable frequency water pump is obtained by the following formula: P=K1×Q 2 Among them, P is the output pressure of the variable frequency water pump, K1 is a constant calculated from the performance parameters of the variable frequency water pump, and Q is the output flow rate of water.

5. The PLC-controlled balanced ratio mixing system according to claim 1, characterized in that: The sending of a control command to the variable frequency water pump according to the output pressure of the variable frequency water pump comprises: Calculate the AC frequency used by the variable frequency water pump when it outputs this pressure, and send a one-time frequency instruction to the variable frequency water pump based on the AC frequency. The formula is as follows: Among them, P is the output pressure of the variable frequency water pump, K1 is a constant, which is calculated from the performance parameters of the variable frequency water pump, and f 水 is the AC power frequency of the variable frequency water pump.

6. The PLC-controlled balanced ratio mixing system according to claim 1, characterized in that: After the control command 1 is sent to the variable frequency water pump according to the output pressure of the variable frequency water pump, the real-time pressure of the variable frequency water pump is measured by a pressure sensor, and the real-time pressure of the variable frequency water pump is compared with the ideal output pressure of the variable frequency water pump. The control command 1 is updated according to the comparison result until the real-time pressure of the variable frequency water pump is equal to the ideal output pressure of the variable frequency water pump.

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