A flow control metering device for on-site calibration of a gravity dosing system

Abstract

The utility model discloses a kind of for gravity dosing system field calibration formula flow control metering device, mainly applied to water treatment, environmental protection, chemical industry, pharmacy, food, petroleum and other industries.The utility model includes two structures, respectively through the solid difference module of the core of tensile spring and compression spring, the relative stability of the differential pressure of current-limiting module is realized, to the gain module of same structure, differential pressure precision is promoted in cooperation, to realize accurate flow control.The utility model is a kind of gravity dosing system metering device with simple structure, reliable operation, convenient maintenance, solve the open system in prior art, large floor area, installation condition is limited, system has no informatization etc. The utility model improves the operation convenience of dosing process, reliable operation, reduces maintenance rate, improves fine management level, creates conditions for lean management to reduce production cost, while providing a good foundation for ensuring the safety and quality target of process operation.

Description

Technical Field

[0001] This utility model relates to the field of dosing technology in industries such as water treatment, environmental protection, chemical industry, pharmaceutical industry, food industry, and petroleum industry, and in particular to a flow control metering device for on-site calibration of gravity dosing systems. Background Technology

[0002] Chemical dosing is a technical system that involves adding chemical agents to industrial or water treatment systems in a specific ratio to achieve goals such as water quality control, scale and corrosion prevention, sterilization, and denitrification. In industries such as water treatment, environmental protection, chemical, pharmaceutical, food, and petroleum, chemical dosing processes are generally divided into two forms: gravity dosing and pressure dosing.

[0003] (I) Gravity-based drug delivery

[0004] Gravity dosing utilizes the gravity of the pesticide solution for dosing. The method involves elevating the solution to a certain height and storing it, then controlling its flow into the dosing point via a metering device. (See attached diagram) Figure 1 (Typical method of gravity dosing system and metering device). Its advantages include:

[0005] It requires no energy to operate and is stable and reliable.

[0006] Simple to repair and maintain, with a low failure rate;

[0007] The energy-saving effect is significant.

[0008] Disadvantages include:

[0009] Open system, poor sanitation;

[0010] Cannot be connected to a pressure dosing system;

[0011] Large footprint;

[0012] Installation is limited by vertical conditions;

[0013] Metering data cannot be entered into the central control system.

[0014] (II) Pressure-based drug administration

[0015] Pressure dosing mainly includes two methods: water jet dosing and metering pump dosing. It is suitable for situations where the storage tank level is lower than the reaction tank level; for adding chemicals to pressure pipelines; and for water purification structures at high elevations or long distances. This is primarily applicable to scenarios where dosing cannot be done by gravity. It requires continuous power supply year-round, resulting in high energy consumption.

[0016] (III) Types and main problems of existing gravity dosing system metering devices:

[0017] 1. Floating cup (immersion type) metering device (with) Figure 2 ):

[0018] Principle: The metering device floats on the surface of the liquid, and the liquid level difference h remains constant. The flow rate is changed by changing the diameter of the orifice cap. Several orifice caps of different diameters are prepared, and the flow rate of each is measured and labeled. When in use, the required orifice cap is replaced to meet the dosing requirements under different water quality and water quantity.

[0019] Advantages: Simple structure, reliable operation, suitable for small-scale water treatment.

[0020] Disadvantages: Flow rate stepped adjustment, large dosing redundancy, inconvenient operation, poor hygiene, inability to input metering data into the central control system, and system openness (meaning the liquid solution is exposed to air at least once between entering the metering device and the dosing point). It is rarely used nowadays.

[0021] 2. Float cup (hole plug type) measuring device

[0022] The principle is the same as that of immersion, but the structure is slightly different. It is rarely used nowadays.

[0023] 3. Float cup (cone rod type) metering device (with) Figure 3 ):

[0024] Principle: The metering device floats on the surface of the liquid, and the liquid level difference h remains constant. By adjusting the up and down stroke of the cone rod, the size of the gap in the balance valve seat is adjusted, thereby changing the flow area and thus the flow rate.

[0025] Advantages: Simple structure, reliable operation, suitable for small-scale water treatment.

[0026] Disadvantages: Small flow rate adjustment range, poor flow rate information perception, inconvenient operation, poor sanitation, inability to input metering data into the central control system, and system openness. It is now rarely used.

[0027] 4. Orifice metering device (with) Figure 4 ):

[0028] Principle: The liquid level H in the constant level tank remains constant. The flow rate is changed by altering the outlet diameter of the orifice elbow. Several orifice elbows of different diameters are prepared, and the flow rate of each is measured and labeled. When in use, the required orifice elbow is replaced to meet the dosing requirements under different water qualities and quantities.

[0029] Advantages: It has a wider flow rate adjustment range and is easier to operate than the float cup type.

[0030] Disadvantages: Step-by-step flow regulation, large redundancy in chemical dosing, large footprint, poor sanitation, inability to input metering data into the central control system, and system openness. The constant level tank must be lower than the bottom of the high-level storage tank and higher than the liquid level in the reaction tank.

[0031] 5. Triangular weir metering device (attached) Figure 5 ):

[0032] Principle: With a constant liquid level H in the constant level tank and a constant flow area in the flow regulating valve, the output flow rate remains constant. Changing the flow area of ​​the flow regulating valve changes the flow rate. In this metering device, the height h from the bottom of the triangular weir to the liquid surface reflects the flow rate. An increase in flow rate causes h to rise, and a decrease in flow rate causes h to fall. The flow rate is read by measuring h.

[0033] Advantages: Smooth flow rate adjustment, wide flow rate adjustment range, and simple operation.

[0034] Disadvantages: Large footprint, poor sanitation, inability to input metering data into the central control system, and system accessibility. The constant level tank must be below the bottom of the high-level storage tank and above the liquid level of the reaction tank.

[0035] 6. Siphon metering device (with) Figure 6 ):

[0036] Principle: The liquid level H in the constant level tank remains constant, as does the diameter of the siphon tube. Raising the siphon tube shortens the flow rate by h, reducing the pressure difference at the siphon tube outlet and decreasing the flow rate; lowering the siphon tube increases the flow rate by h, increasing the pressure difference at the outlet and increasing the flow rate. The flow rate can be adjusted by changing the height of the siphon tube outlet.

[0037] Advantages: Smooth flow regulation and simple structure.

[0038] Disadvantages: Limited flow rate adjustment range, large footprint, inability to input metering data into the central control system, and system openness. The constant level tank must be below the bottom of the high-level storage tank and above the liquid level of the reaction tank.

[0039] 7. Continuous adjustment metering device (with attachment) Figure 7 ):

[0040] Principle: The liquid level H in the constant level tank remains constant. A flow regulating valve is installed at the outlet, followed by a tee and a vertical glass tube, and then an orifice plate chamber. When the regulating valve is fully open, the liquid level h in the glass tube will rise to its highest point (approximately equal to H), at which point the flow rate is maximum. When the regulating valve is fully closed, h is 0, and the flow rate is 0. That is, the flow rate decreases as h decreases. The measured flow rate can be directly calibrated onto the glass tube wall for reading.

[0041] Advantages: Smooth flow regulation and simple structure.

[0042] Disadvantages: Large footprint, poor sanitation, inability to input metering data into the central control system, and system accessibility. The constant level tank must be below the bottom of the high-level storage tank and above the liquid level of the reaction tank.

[0043] 8. Main problems with existing gravity dosing system metering devices:

[0044] All are open systems, and their hygiene conditions are poor.

[0045] It cannot be connected to a pressure (positive or negative pressure) dosing system;

[0046] It requires a constant position box, which occupies a large area;

[0047] Installation conditions are limited, and the following conditions must be met: Hbottom of storage tank ≥ Hconstant level tank ≥ Hreaction tank water surface.

[0048] The system lacks information technology and cannot be connected to the central control system. Utility Model Content

[0049] The purpose of this utility model is to overcome the shortcomings of existing technologies, which are all open systems with poor hygiene, cannot be connected to pressure (positive or negative pressure) dosing systems, require constant level tanks, occupy a large area, have limited installation conditions, and need to meet the following requirements: Hstorage bottom ≥ Hconstant level tank ≥ Hreaction tank water surface, lack information technology, and cannot be connected to a central control system. This utility model provides a flow control metering device for on-site calibration of gravity dosing systems.

[0050] This utility model is achieved through the following technical solution:

[0051] A flow control metering device for on-site calibration of a gravity dosing system includes an inlet pipe, branch pipes, a flow limiting module, a differential pressure module, and an outlet pipe. The inlet pipe connects to a storage tank and a main valve is installed on it. The differential pressure module includes a housing, a rubber diaphragm, a tension spring, a balance valve core, and a balance valve seat. The rubber diaphragm is fixedly installed inside the housing, dividing the housing cavity into an upper and lower cavity. The tension spring is placed in the upper cavity, with its upper end connected to the top of the upper cavity and its lower end fixed to the upper side of the rubber diaphragm. The balance valve core is placed in the lower cavity and fixed to the lower side of the rubber diaphragm. The balance valve seat is located at the bottom of the lower cavity of the differential pressure module, and the balance valve core is located directly above the balance valve seat. The opening degree between the core and the balance valve seat changes as the rubber diaphragm moves up and down; one end of the branch pipe is connected to the drug inlet pipe, and the other end is connected to the upper cavity of the differential pressure module; the branch pipe has a built-in pressure-conducting isolation sleeve, and hydraulic oil is provided in the upper cavity. The inner side of the pressure-conducting isolation sleeve is connected to the hydraulic oil in the upper cavity of the differential pressure module, and the outer side of the pressure-conducting isolation sleeve is connected to the liquid inlet pipe. The flow limiting module is composed of an orifice plate chamber and a flow regulating valve connected in series. The orifice plate chamber is provided with a flow limiting orifice plate, and two differential pressure transmitter connecting pipes are provided on the outside. One end of the flow limiting module is connected to the drug inlet pipe, and the other end is connected to the liquid inlet of the lower cavity of the differential pressure module; the balance valve seat of the lower cavity of the differential pressure module is connected to the drug outlet pipe, and the other end of the drug outlet pipe is connected to the drug dosing point.

[0052] It also includes a gain module, which has the same structure as the solid difference module and is connected in series after the solid difference module. The upper cavity of the gain module is connected to the upper cavity of the solid difference module, the liquid inlet of the lower cavity of the gain module is connected to the balance valve seat of the lower cavity of the solid difference module, and the balance valve seat of the lower cavity of the gain module is connected to the drug outlet pipeline.

[0053] A flow control metering device for on-site calibration of a gravity dosing system includes an inlet pipe, a differential pressure module, branch pipes, a flow limiting module, and an outlet pipe. The inlet pipe connects to a storage tank and a main valve is installed on it. The differential pressure module includes a housing, a rubber diaphragm, a compression spring, a balance valve core, and a balance valve seat. The rubber diaphragm is fixedly installed inside the housing, dividing the housing cavity into an upper and lower cavity. The compression spring is placed in the upper cavity, with its upper end connected to the top of the upper cavity and its lower end fixed to the upper side of the rubber diaphragm. The balance valve core is placed in the lower cavity and fixed to the lower side of the rubber diaphragm. The balance valve seat is located at the bottom of the lower cavity of the differential pressure module. Directly below the balance valve seat, the opening degree between the balance valve core and the balance valve seat changes as the rubber diaphragm moves up and down; one end of the branch pipe is connected to the drug outlet pipe, and the other end is connected to the upper cavity of the differential pressure module. The branch pipe has a built-in pressure-conducting isolation sleeve. Hydraulic oil is provided in the upper cavity of the differential pressure module. The inner side of the pressure-conducting isolation sleeve is connected to the hydraulic oil in the upper cavity of the differential pressure module, and the outer side is connected to the drug liquid in the drug outlet pipe; the flow-limiting module is composed of an orifice plate chamber and a flow regulating valve connected in series. The orifice plate chamber has a flow-limiting orifice plate inside and two differential pressure transmitter connecting pipes outside. One end of the flow-limiting module is connected to the drug outlet pipe, and the other end is connected to the liquid outlet of the lower cavity of the differential pressure module; the other end of the drug outlet pipe is connected to the drug dosing point.

[0054] It also includes a gain module, which has the same structure as the solid difference module and is connected in series before the solid difference module. The upper cavity of the gain module is connected to the upper cavity of the solid difference module, the liquid outlet of the lower cavity of the gain module is connected to the balance valve seat of the lower cavity of the solid difference module, and the balance valve seat of the lower cavity of the gain module is connected to the drug inlet pipe.

[0055] The rubber diaphragm has a corrugated diaphragm structure with stainless steel reinforcing plates built into the middle.

[0056] The orifice plate chamber of the flow limiting module is connected to a differential pressure transmitter via a differential pressure transmitter connecting pipe, and the differential pressure transmitter is connected to a flow totalizer.

[0057] The ratios of the flow area of ​​the balance valve seat to the cross-sectional area of ​​its inner cavity in the aforementioned differential and gain modules are C and C, respectively. 增 If the design flow drift rate is E%, then for every meter increase in the static pressure Hn of the storage tank, the pressure difference drift ΔHp before and after the flow-limiting module of both the fixed differential module structure and the fixed differential + gain module structure will be... 压差 They respectively satisfy:

[0058] Solid-state module structure: △Hp 压差 = C / (C-1)

[0059] Solidity + Gain Module Structure: △Hp 压差 = C·C 增 / [(1-C)·(1-C) 增 )].

[0060] The compensation pressure Ht of the tension spring or compression spring in the solid difference module structure and the solid difference + gain module structure respectively satisfies:

[0061] Solid-state module structure: Ht ≥ + C·Hn

[0062] Solidity + Gain Module Structure: Ht 增 ≥ + C 增 ·Hn

[0063] Ht ≥ ·(Ht 增 + )+ ·Hn

[0064] C·Hn, C 增 ·Hn、 ·Hn represents the calibration compensation value for the solid-state module structure and the solid-state + gain module structure, respectively.

[0065] The upper end of the tension spring or compression spring is connected to a spring setting handle, which is installed in the upper part of the upper cavity of the solidity module to calibrate the compensation values ​​C·Hn and C. 增 ·Hn、 The specific value of Hn needs to be determined by adjusting the spring setting handles of the gain module and the differential module on-site, based on the liquid level Hn in the on-site storage tank.

[0066] The current limiting module is designed with a differential pressure of A, and a design installation space height of y·A (y is a coefficient, referring to y times A). The design height is Ht. 增 = x·A (where x is a coefficient, referring to taking A as x times), then the flow area s of the flow-limiting module's flow-limiting orifice. 限 , Solid difference module balance valve seat flow area s, Gain module balance valve seat flow area s 增 The flow area relationship of the three orifices satisfies:

[0067] ; .

[0068] The advantages of this utility model are: in order to solve the defects of existing technologies, which are all open systems, have poor sanitary conditions, cannot be connected to pressure (positive or negative pressure) dosing systems, require constant level tanks, occupy a large area, have limited installation conditions, and need to meet the following conditions: H storage tank bottom ≥ H constant level tank ≥ H reaction tank water surface, the system has no information system, and cannot be connected to the central control system.

[0069] This utility model employs a flow-limiting module capable of outputting the pressure difference across the flow-limiting orifice plate and changing the flow area of ​​the flow-limiting orifice, a fixed-pressure module that maintains a relatively stable input-output pressure difference, and branch pipes that isolate the liquid medicine from the hydraulic oil and ensure equal pressure on both sides, thus forming a closed system and controlling the flow rate of the drug. In addition, a gain module that significantly improves the pressure difference drift of the flow-limiting module is added, greatly enhancing the flow control accuracy of the device. With the assistance of connecting pipelines, valves, fittings, etc., this constitutes the utility model: a field calibration metering device for a gravity dosing system.

[0070] This invention improves the ease of operation and reliability of the dosing process, reduces the maintenance rate, enhances the level of refined management, creates conditions for lean management and reduces production costs, and provides a good foundation for ensuring the safety and quality objectives of the process operation. Attached Figure Description

[0071] Figure 1 This is a schematic diagram of a typical structure of an existing gravity dosing system and metering device.

[0072] Figure 2 This is a schematic diagram of the structure of a floating cup (immersion type) metering device;

[0073] Figure 3 This is a schematic diagram of the structure of a float cup (cone rod) metering device;

[0074] Figure 4 This is a schematic diagram of the orifice metering device.

[0075] Figure 5 This is a schematic diagram of the triangular weir metering device.

[0076] Figure 6 This is a schematic diagram of the siphon metering device.

[0077] Figure 7 This is a schematic diagram of the structure of a continuously adjustable metering device;

[0078] Figure 8 This is a schematic diagram of the structure of Embodiment 1 (fixed difference module tension spring) of this utility model;

[0079] Figure 9 This is a schematic diagram of the structure of Embodiment 1 (fixed difference + gain module tension spring) of this utility model;

[0080] Figure 10 This is a schematic diagram of the structure of Embodiment 2 (fixed difference module compression spring) of this utility model;

[0081] Figure 11 This is a schematic diagram of the structure of Embodiment 2 (fixed difference + gain module compression spring) of this utility model;

[0082] Figure 12 This is a schematic diagram of the flow rate display section.

[0083] Figure 13 This is a schematic diagram illustrating an extended installation method for this utility model – an auxiliary water jet device.

[0084] Figure 14 This is a schematic diagram of an extended installation method for this utility model - pump-assisted dosing. Detailed Implementation

[0085] (I) Example 1 (Tension Spring Structure):

[0086] 1. Implementation Plan:

[0087] The following is in conjunction with the appendix Figure 9The following is a further detailed description of a specific embodiment of this utility model: A flow control metering device for on-site calibration of a gravity dosing system includes an inlet pipe 1, a branch pipe 16, a flow limiting module 2, a differential module 21, a gain module 22, and an outlet pipe 3; the inlet pipe 1 connects to a storage tank 14, and a main valve 15 is installed on it; the differential module 21 is composed of a housing 4, a rubber diaphragm 5, a tension spring 6, a balance valve core 7, a balance valve seat 8, and an inlet 10. A rubber diaphragm 5 is fixedly installed inside the housing 4, dividing the inner cavity of the housing into an upper cavity and a lower cavity. The rubber diaphragm 5 has a corrugated diaphragm structure with a stainless steel reinforcing plate built into its central part. The tension spring 6 is placed in the upper cavity, with the upper end connected to the spring setting handle 25 and the lower end fixed to the upper side of the rubber diaphragm 5. The balance valve core 7 is placed in the lower cavity and fixed to the lower side of the rubber diaphragm 5. The balance valve seat 8 is located at the bottom of the lower cavity of the differential module 21, and the balance valve core 7 is located directly above the balance valve seat 8. The opening and closing degree between the two changes with the up and down movement of the rubber diaphragm 5. The branch pipe 16 has a built-in pressure-conducting isolation sleeve 9. The inner side of the sleeve is connected to the hydraulic oil 20 in the upper cavity of the differential module 21, and the outer side is connected to the liquid medicine in the drug inlet pipe 1. The pressure-conducting isolation sleeve isolates the hydraulic oil inside the differential module from the liquid medicine outside, while making the pressure inside and outside equal. One end of the branch pipe 16 is connected to the drug inlet pipe 1, and the other end is connected to the upper cavity of the differential pressure module 21. The flow limiting module 2 is composed of an orifice plate chamber 11 and a flow regulating valve 12 connected in series. The orifice plate chamber 11 is provided with a flow limiting orifice plate 13 inside and two differential pressure transmitter connecting pipes 17 outside. One end of the flow limiting module 2 is connected to the drug inlet pipe 1, and the other end is connected to the liquid inlet 10 of the lower cavity of the differential pressure module 21. The gain module 22 has the same structure as the differential pressure module 21 and is connected in series after the differential pressure module 21 and before the drug outlet pipe. The upper cavity of the gain module 22 is connected to the upper cavity of the differential pressure module 21, and the liquid inlet 10 of the lower cavity of the gain module 22 is connected to the balance valve seat 8 of the lower cavity of the differential pressure module 21. The balance valve seat 8 of the lower cavity of the gain module 22 is connected to the drug outlet pipe 3. One end of the drug outlet pipe 3 is connected to the balance valve seat 8 of the gain module, and the other end is connected to the drug dosing point.

[0088] like Figure 12 As shown, the orifice plate chamber 11 is connected to a differential pressure transmitter 18 via a differential pressure transmitter connecting pipe 17. The differential pressure transmitter 18 is connected to a flow totalizer 19. The flow totalizer 19 uploads the instantaneous flow rate, cumulative flow rate, and liquid level data of the storage tank to the central control system to achieve information-based monitoring.

[0089] The rubber diaphragm 5 is installed inside the housing 4, separating the inner cavity of the housing 4 into an upper cavity and a lower cavity;

[0090] The rubber diaphragm 5 has a stainless steel reinforcing plate inside its abdominal portion. The stainless steel reinforcing plate and the balance valve core 7 move up and down with the tension spring 6.

[0091] The tension spring 6 is fixed to the rubber diaphragm 5, which drives the middle part of the rubber diaphragm 5 to move up and down.

[0092] The inlet pipe 1 is connected to the storage tank 14 and is used to transport the liquid medicine;

[0093] The main valve 15 is installed on the drug inlet pipe 1 to control the flow of the drug solution.

[0094] The flow limiting module 2 is located after the main valve 15 and before the differential pressure module 21, and controls the flow area and detects and outputs the pressure difference value on both sides of the flow limiting orifice plate.

[0095] The pressure-conducting isolation sleeve 9 isolates the inner hydraulic oil from the outer liquid medicine and makes the pressure on both sides equal.

[0096] The differential pressure transmitter connecting pipe 17 is connected to the differential pressure transmitter 18. The differential pressure transmitter 18 transmits electrical signals to the flow totalizer 19. The totalizer 19 can display and upload data such as flow rate in real time.

[0097] Differential pressure drift constraint conditions:

[0098] The solidity module and the solidity + gain module have balance valve seat to diaphragm cavity cross-sectional area ratios of C and C, respectively. 增 If the design flow drift rate is E%, then for every meter increase in the static pressure Hn of the storage tank, the pressure difference drift ΔHp before and after the flow-limiting module of both the fixed differential module structure and the fixed differential + gain module structure will be... 压差 They respectively satisfy:

[0099] Solid-state module structure: △Hp 压差 = C / (C-1)

[0100] Solidity + Gain Module Structure: △Hp 压差 = C·C 增 / [(1-C)·(1-C) 增 )]

[0101] Spring compensation pressure constraint conditions:

[0102] The spring compensation pressure Ht of the solidity module structure and the solidity + gain module structure satisfies:

[0103] Solid-state module structure: Ht ≥ + C·Hn

[0104] Solidity + Gain Module Structure: Ht 增 ≥ + C 增 ·Hn

[0105] Ht ≥ ·(Ht 增 + )+ ·Hn

[0106] Where: E% is the design flow drift rate, C, C 增 To balance the ratio of the valve seat flow area to the cross-sectional area of ​​each internal cavity, Hn is the static pressure of the drug storage tank.

[0107] C·Hn, C 增 ·Hn、 ·Hn represents the calibration compensation value for the solid-state module structure and the solid-state + gain module structure, respectively.

[0108] Orifice area constraint conditions:

[0109] The current limiting module is designed with a differential pressure of A, and a design installation space height of y·A (y is a coefficient, referring to A multiplied by y). The design height is Ht. 增 = x·A (where x is a coefficient, referring to taking A as x times), then the flow area slimited of the flow-limiting module's flow-limiting orifice, sbalanced of the solid-difference module's balance valve seat, and sgain of the balance valve seat are... 增 The flow area relationship of the three orifices satisfies:

[0110] ; .

[0111] 2. Derivation of the mechanical equilibrium equations and various constraint conditions:

[0112] 1) Constraints on differential pressure drift of the solid differential module (see appendix) Figure 8 ):

[0113] Force balance equations for the solid-state module:

[0114] (Hn - Ht)·S = H 下 ·S·(1-C)

[0115] Lower chamber pressure:

[0116] H 下 = Equation (1)

[0117] Pressure difference across the current limiting module:

[0118] H 限 压差 = Hn -H 下

[0119] =(Hn - C·Hn ) / (1 - C)

[0120] H 限压差 = (Ht - C·Hn) / (1 - C) Equation (2)

[0121] In equations (1) and (2):

[0122] Hn: Static pressure of the storage tank (mH2O) (generally ≤ 8 mH2O for gravity dosing systems)

[0123] Ht: Spring compensation pressure (mH2O)

[0124] s: Cross-sectional area of ​​the balance valve seat (m²)

[0125] S: Cross-sectional area of ​​the solid-state module cavity (m²)

[0126] C: Area ratio coefficient (C = s / S)

[0127] Differential pressure stability characteristics:

[0128] Ideal working conditions limC→0 <![CDATA[H 限 压差 = Ht, achieving absolute constant pressure difference]]> Actual working conditions C ≠ 0 <![CDATA[generating a pressure difference drift ΔHp 压差 >

[0129] Pressure drift quantization model

[0130] As the static liquid level Hn in the storage tank changes, the pressure difference across the flow-limiting module will change; the increase or decrease in this difference is called the pressure difference drift ΔHp. 压差 When the liquid level in the storage tank rises by 1 meter, and Hn+1 - Hn = 1:

[0131] △Hp 压差 = Hn+1 限 压差 - H n 限 压差

[0132] Substituting equation (2) into the equation and simplifying...

[0133] △Hp 压差 = C / ( C - 1) Equation (3)

[0134] The engineering significance of equation (3):

[0135] △Hp 压差 For every 1 meter change in the static liquid level Hn of the drug storage tank, the pressure difference drift generated before and after the flow restriction module is only functionally related to C.

[0136] △Hp 压强 Positively correlated with C, the larger C is, the greater △Hp 压强 The larger;

[0137] Decreasing the C value can reduce ΔHp 压差 However, it is limited by C = r2 / R 2 (r is the radius of the balance valve seat, and R is the radius of the diaphragm cavity). Decreasing C requires increasing R, which leads to an increase in the size of the device. A balance needs to be struck between differential pressure stability and device compactness to determine a reasonable range for C.

[0138] 2) Fixed error module spring compensation pressure constraint conditions (attached) Figure 8 ):

[0139] Changes in the pressure difference across the current limiting module will cause changes in flow rate; different values ​​of Hn will result in different flow rates, which we call flow drift.

[0140] The flow formula is modified based on Bernoulli's equation:

[0141] Q = K· S·√Hn 压差 (K is the overall coefficient, S is the flow area)

[0142] Design flow drift rate E% (the percentage change in flow rate caused by a 1-meter increase in the liquid level of the storage tank):

[0143] Qn+1 / Qn=√(H n) 压差 +△Hp 压差 ) / √(Hn 压差 ) = 1 E%

[0144] Combining equations (2) and (3), we obtain the constraint conditions:

[0145] Ht = + C·

[0146] In this case, with As the value increases, the drift pressure difference decreases, and E% is negative here:

[0147] Ht = + C·

[0148] The engineering significance of the above formula:

[0149] The above formula consists of two parts, the first part: In the formula, C and E% are both constants; therefore, the entire front part is constant. The physical meaning of the front part: It satisfies the flow drift rate of... When the area ratio coefficient is C, the pressure difference across the flow-limiting module is called the lower limit of the pressure difference. In the design of the device, to ensure the flow drift rate of the device... For accuracy, the design value of the pressure difference across the current limiting module must be greater than this value. If the design value of the pressure difference for the current limiting module is A, then the above formula is Ht = + C·Hn, A≥ Therefore, the above formula can be written as:

[0150] Ht ≥ + C· Equation (4)

[0151] The physical meaning of C·Hn at the rear is: the pressure difference before and after the current limiting module changes with the change of Hn. When the device is applied to a scenario where the static pressure is Hn, the device's Ht must be superimposed with a C·Hn on the design value A in order to compensate for the pressure difference drift before and after the current limiting module caused by the change of Hn, so that the pressure difference before and after the current limiting module is equal to the design value A, and thus the device operates in accordance with the design requirements. C·Hn is called the calibration compensation value, which is why this device is called the field calibration type.

[0152] Mathematical derivation and proof of the calibration compensation value:

[0153] From equation (3), we know that: △Hp 压差 = C / (C-1)

[0154] When the device is installed in a storage tank with a static pressure of Hn, the pressure difference drift in the lower diaphragm chamber caused by Hn is:

[0155] Hp 压差 = Hn C / (C-1),

[0156] The resulting pressure drift value is:

[0157] Fp 下 = ·(1-C) · S = - Hn· C· S.

[0158] From equation (4), we know that: Ht = + ·C

[0159] Its calibrated compensation value is: = Hn·C

[0160] The calibrated compensation value results in a pressure value of: Fp 上 = Hn·C·S,

[0161] Fp 上 = Fp 下 If the constituent factors and absolute values ​​of the two forces are the same, it means that the calibration compensation value is equal to the differential pressure drift value. If the signs are opposite, it means that the directions of the two forces are opposite.

[0162] 3) Constraints on the area of ​​the flow passage in the solid differential module (see appendix) Figure 8 ):

[0163] The liquid medicine flows through the flow-limiting orifice of the flow-limiting module and the balancing valve seat of the differential pressure module to the outlet pipeline. To ensure a stable flow rate in the flow-limiting module, the flow capacity of the balancing valve seat must be greater than that of the flow-limiting orifice to avoid creating resistance to the orifice. In other words, the flow capacity of the differential pressure module must be greater than or equal to the flow capacity of the flow-limiting module. Let the design differential pressure of the flow-limiting module be A, and the design installation space height of the device be y·A (where y is a coefficient, indicating that A is taken as y times A). Then:

[0164] The flow formula is modified based on Bernoulli's equation:

[0165] Q = K·S·√H 压差 (K is the overall coefficient, S is the flow area)

[0166] Pressure difference across the current limiting module: A

[0167] Pressure difference across the solid differential module: = Design installation space height - Ht = y·A - A = (y-1)·A

[0168]

[0169] in conclusion:

[0170] in:

[0171] s: Cross-sectional area of ​​the balance valve seat bore

[0172] s 限 : Cross-sectional area of ​​the flow restrictor

[0173] 4) Key parameters Ht and C thresholds:

[0174] If the drift rate is required to be no more than 1.25% for every meter change in Hn, then...

[0175] Ht = + · C

[0176] Ht = C · (40.25+Hn)

[0177] Based on most usage scenarios, the Ht threshold is set to: 0.3 meters ≤ Ht ≤ 1 meter, and the Hn threshold ranges from 1 meter to 8 meters.

[0178] When Ht = 0.3 meters, Cmin = 0.0062 (Hn = 8 meters), Cmax = 0.0073 (Hn = 1 meter).

[0179] When Ht = 1 meter, Cmin = 0.021 (Hn = 8 meters), Cmax = 0.0245 (Hn = 1 meter).

[0180] Therefore, the threshold C is: 0.0062 ≤ C ≤ 0.0245, and the value of C must be less than the corresponding C value calculated by substituting Ht and Hn into the formula.

[0181] From the perspective of theoretical derivation and engineering practice, it is feasible to apply the above threshold range. Of course, if the tolerance for E% is greater, the threshold of C will also increase accordingly.

[0182] Based on the aforementioned C threshold, the upper limit of C is 0.0245, which means that the ratio of the inner diameter of the fixed differential module to the diameter of the balance valve seat must be more than 6.4 times to meet the flow drift accuracy requirements. When the flow rate is small, the device size is acceptable, but when the flow rate is large, the device size is very large. Therefore, this structure has certain limitations.

[0183] Through research and experimentation, it has been found that connecting a gain module in series can significantly improve the C threshold range.

[0184] 5) Constraints on differential pressure drift of the solid-state + gain module (see appendix) Figure 9 ):

[0185] The force balance equation for the lower cavity of the gain module is:

[0186] (Hn-Ht 增 )·S 增 =H 增 下 ·S 增 ·(1-C2)

[0187] In the formula:

[0188] Hn: Static pressure of the drug storage tank (mH2O)

[0189] H 增 下 : Lower chamber pressure of the gain module (mH2O)

[0190] Ht 增 Gain module spring compensation pressure (mH2O)

[0191] s 增 Gain module balance valve seat cross-sectional area (m²)

[0192] S 增 Cross-sectional area of ​​the gain module cavity (m²)

[0193] C 增 Gain module area ratio coefficient (C) 增 = s 增 / S 增 )

[0194] The pressure in the lower chamber of the gain module is obtained:

[0195] H增 下 =(Hn- Ht 增 ) / (1-C 增 )

[0196] The force balance equation for the lower cavity of the solid-state module is:

[0197] (Hn-Ht)·S=H 下 ·S·(1- C)+ H 增 下 · C · S

[0198] In the formula:

[0199] Hn: Static pressure of the drug storage tank (mH2O)

[0200] H 下 : Lower cavity pressure of the solid differential module (mH2O)

[0201] Ht: Fixed error module spring compensation pressure (mH2O)

[0202] s: Cross-sectional area of ​​the balance valve seat of the solid differential module (m²)

[0203] S: Cross-sectional area of ​​the diaphragm cavity in the solid-state module (m²)

[0204] C: Fixed error module area ratio coefficient (C1=s / S)

[0205] The pressure in the lower cavity of the solidity module is obtained by solving:

[0206] H 下 =[Hn·(1-CC 增 )- Ht·(1-C 增 )+ C·Ht 增 ] / [(1-C)·(1-C 增 )]

[0207] Quantization model of pressure difference drift in lower cavity of solid module

[0208] A 1-meter rise in the drug storage tank level results in the following pressure differential drift in the lower chamber of the gain module:

[0209] △Hp 增 压差 = Hn+1 压差 - Hn 压差 = - C 增 / (1-C 增 )

[0210] Differential pressure drift in the lower chamber of the solid differential module:

[0211] △Hp 压差= H 限 n+1 压差 - H 限 n 压差

[0212] = H(n+1) - H(n+1) 下 -((Hn -Hn 下 ))

[0213] △Hp 压差 = = Equation (5)

[0214] The engineering significance of equation (5):

[0215] △Hp 压差 The pressure difference drift before and after the flow-limiting module is characterized by the increase of 1 meter in the static liquid level Hn in the storage tank, which is only related to C and C. 增 It exhibits a functional relationship;

[0216] Based on the formula results, the ΔHp of the solidity module with the added gain module can be seen. 压差 The value is equal to the product of the pressure difference drift of the two modules;

[0217] In the formula, C, C 增 Both are two decimal places, therefore, the numerator C·C 增 →0; Denominator 1-C→1 1-C 增 →1, △Hp 压强 = This means that the pressure drift in the lower cavity of the solid differential module approaches 0, which also means that the pressure drift across the flow limiting module approaches 0, and the flow drift also approaches 0.

[0218] The formula reflects C and C 增 Synergistic reduction effect on pressure difference changes.

[0219] 6) Fixed error + gain module spring compensation pressure constraint conditions (attached) Figure 9 ):

[0220] The flow formula is modified based on Bernoulli's equation:

[0221] Q = K·S·√H 压差 (K is the overall coefficient, S is the flow area)

[0222] Design flow drift rate E% (the percentage change in flow rate caused by a 1-meter increase in the liquid level of the storage tank):

[0223] Qn+1 / Qn = √(Hn) 压差 +△Hp 压差 ) / √(Hn 压差 ) = 1 E%

[0224] Constraints:

[0225] Ht = ·(Ht 增 + ) + ·Hn

[0226] In this case, with As the value increases, the drift pressure difference increases, and E% here is a positive value:

[0227] Ht = ·(Ht 增 + ) + ·Hn

[0228] Ht 增 = + C 增 ·Hn

[0229] The engineering meaning of the above formula:

[0230] The above formula consists of two parts, the first part: ·(Ht 增 + ), where C and C 增 、E%,Ht 增 All are constants; therefore, the entire front section is constant. The physical meaning of the front section: It satisfies the design flow drift rate of... The area ratio coefficients are C and C, respectively. 增 When the pressure difference across the flow-limiting module is at that point, we call it the lower limit of the pressure difference. In designing the device, to ensure the accuracy of the flow drift rate, the design value of the pressure difference across the flow-limiting module must be greater than the lower limit of the pressure difference. If the design value is A, then the form of equation (9) is Ht = + ·Hn, where A≥ ·(Ht 增 + Therefore, the above formula can be written as:

[0231] Ht ≥ ·(Ht 增 + ) + ·Hn formula (6)

[0232] rear • Hn, physical meaning: The pressure difference before and after the current-limiting module changes with Hn. When the device is applied to a scenario with a static pressure of Hn, the device's Ht must be superimposed on the design value A. Only by adjusting the amount of Hn can the pressure difference drift across the current-limiting module caused by changes in Hn be compensated, so that the pressure difference across the current-limiting module equals the design value A, thereby ensuring that the device operates in accordance with design requirements. •Hn is called the calibration compensation value, which is why this device is called the field calibration type.

[0233] Derivation and proof of the calibration compensation value of the solid error + gain module:

[0234] From equation (5), it can be seen that when the device is installed in a storage tank with a static pressure of Hn, the pressure drift of the lower chamber of the solidity module caused by Hn is:

[0235] △Hp 压强 =

[0236] The pressure Fp in the lower chamber of the solid differential module is formed by the pressure difference drift. 下 :

[0237] Fp 下 = Hn· · (1-C) · S

[0238] = · Hn·S

[0239] = ·Hn·S

[0240] From equation (6) Ht ≥ ·(Ht 增 + ) + ·Hn can be known

[0241] The pressure generated by its calibrated compensation value:

[0242] Fp 上 = ·Hn·S

[0243] Fp 上 = Fp 下 If the constituent factors and absolute values ​​of the two forces are the same, it means that the calibration compensation value is equal to the differential pressure drift value. If the signs are opposite, it means that the directions of the two forces are opposite.

[0244] 7) Constraints on the area of ​​the flow passage in the solid-state + gain module (see appendix) Figure 9):

[0245] The liquid medicine flows through the flow-limiting orifice of the flow-limiting module, the balancing valve seat of the differential pressure module, and the balancing valve of the gain module to the outlet pipe. To ensure a stable flow rate in the flow-limiting module, the flow capacity of the latter two valve seats must be greater than the flow capacity of the flow-limiting orifice to avoid creating resistance to the orifice. The design pressure difference of the flow-limiting module is A, and the flow area s of the flow-limiting orifice of the flow-limiting module... 限 The design installation space height is y·A (y is a coefficient, referring to A being y times), and the design height is Ht. 增 = x·A (where x is a coefficient, meaning x times A):

[0246] Gain-fixed module current carrying capacity ≥ Fixed module current carrying capacity ≥ Current limiting module current carrying capacity

[0247] The flow formula is modified based on Bernoulli's equation:

[0248] Q = K·S·√H 压差 (K is the overall coefficient, S is the flow area)

[0249] The current carrying capacity of the fixed-variable module is greater than or equal to the current carrying capacity of the current-limiting module.

[0250] Pressure difference across the current limiting module: A

[0251] Pressure difference across the solid differential module: = Ht_increase - Ht = x·A - A = (x-1)·A

[0252]

[0253]

[0254] Gain module current carrying capacity ≥ Solidity module current carrying capacity

[0255] Pressure difference across the gain module: = Design installation space height - Ht 增 = y·A - x·A = (yx)·A

[0256] Pressure difference across the solid differential module: = Ht 增 -Ht = x·A - A = (x-1)·A

[0257]

[0258]

[0259] in conclusion:

[0260] ;

[0261] 3. Analysis of the working process of this embodiment:

[0262] When the main valve is closed: the rubber diaphragms of the differential module and the gain module are under the compensating pressure Ht and Ht of the tension spring. 增 Under its influence, it is pulled to the highest level; the balance valve seats of the two modules are fully opened at this time.

[0263] After the main valve is opened: the static pressure Hn of the storage tank is transmitted to the upper chambers of the differential pressure module and the gain module through the pressure-conducting isolation sleeve. The rubber diaphragms and balance valve cores of both modules are compressed to their lowest levels, and the two balance valves are closed. When the liquid medicine enters the lower chamber of the differential pressure module through the flow-limiting module, as the pressure increases, the balance valve core of the differential pressure module gradually opens, and the liquid medicine also begins to enter the lower chamber of the gain module. When the pressure in the lower chamber of the differential pressure module rises to (Hn-Ht)·S, the pressure in the upper and lower chambers reaches equilibrium, and the valve core and seat opening of the differential pressure module remains relatively stable. Similarly, the liquid medicine entering the lower chamber of the gain module causes the pressure in the lower chamber of the gain module to rise, and the balance valve core gradually opens. When the pressure in the lower chamber of the gain module rises to (Hn-Ht)·S, the pressure in the upper and lower chambers reaches equilibrium, and the valve core and seat opening of the differential pressure module remain relatively stable. 增 When the pressure in the upper and lower chambers reaches equilibrium, the valve core and seat opening of the gain module also remain relatively stable. At this time, the pressure difference across the flow limiting module remains stable, and the flow rate of the device remains unchanged.

[0264] When the pressure Hn in the drug inlet tube changes: the equilibrium pressure in the lower chamber of the solid differential module = (Hn) Ht)S, the balancing pressure of the lower cavity of the gain module = (Hn) Ht 增 )·S 增 When the pressure Hn in the drug inlet tube changes ΔH n Time, change ΔHn will be transmitted to the upper cavity of the solid-state module and the gain module through the pressure-conducting isolation sleeve. At this time, the equilibrium pressure in the lower cavity of the solid-state module = (Hn) Ht)·S, the balancing pressure of the lower cavity of the gain module = (Hn) Ht 增 )·S 增 However, due to the different force-bearing areas of the upper and lower cavities, they differ by C and C respectively. 增 The pressure in the upper and lower chambers of the two modules is equal, but the pressure intensity is not equal. This will cause the pressure drift in the lower chamber as previously analyzed and calculated. The unit pressure drift in the lower chamber of the fixed-variable module = Approaching 0, as long as Hp 压差 If the value is small enough, the resulting flow rate drift is within the design requirement E%, and the pressure change in the lower chamber of the fixed differential module can be ignored. For the flow-limiting module, the pressure difference across it can be considered unchanged, and therefore the flow rate remains unchanged.

[0265] Drug outlet pressure H 出 When the pressure changes: the pressure in the lower chamber of the gain module changes from (Hn) Ht 增 )·S 增 It is confirmed that when the pressure in the discharge pipe changes... ΔH 出 This means that a pressure difference is generated on both sides of the gain module's balance valve seat. ΔH 出 Lower cavity pressure (Hn) Ht 增 )·S 增 It is certain. ΔH 出 Changes in pressure will cause the balancing valve core to rise or fall, resulting in a decrease or increase in the flow area of ​​the balancing valve, thus keeping the flow rate through the balancing valve seat constant. Therefore, the pressure difference and flow rate on both sides of the flow limiting module remain unchanged.

[0266] (II) Example 2 (Compression Spring Structure):

[0267] 1. Implementation Plan:

[0268] The following is in conjunction with the appendix Figure 10 , 11 The following is a further detailed description of a specific embodiment of this utility model. Embodiment 2 and Embodiment 1 can be referred to as twin structures, as their mathematical models are completely identical. However, structurally, a compression spring is used for pressure compensation, and each has its own applicable scenarios compared to Embodiment 1.

[0269] As shown in the attached figure: A flow control metering device for on-site calibration of a gravity dosing system, characterized in that it includes a drug inlet pipe 1, a gain module 22, a differential module 21, a branch pipe 16, a flow limiting module 2, and a drug outlet pipe 3; the drug inlet pipe 1 connects to a drug storage tank 14, and a main valve 15 is installed on it; the differential module 21 is composed of a housing 4, a rubber diaphragm 5, a compression spring 23, a balance valve core 7, a balance valve seat 8, and a liquid outlet 24. A rubber diaphragm 5 is fixedly installed inside the housing 4, which divides the inner cavity of the housing into an upper cavity and a lower cavity. The rubber diaphragm 5 has a corrugated diaphragm structure with a stainless steel reinforcing plate built into its central part. The compression spring 23 is placed in the upper cavity, with its upper end connected to the spring setting handle 25 and its lower end fixed to the upper side of the rubber diaphragm 5. The balance valve core 7 is placed in the lower cavity and fixed to the lower side of the rubber diaphragm 5. The balance valve seat 8 is located at the bottom of the lower cavity of the differential module 21, and the balance valve core 7 is located directly below the balance valve seat 8. The opening and closing degree between the two changes with the up and down movement of the rubber diaphragm 5. The gain module 22 has the same structure as the differential module 21 and is connected in series after the drug inlet pipe before the differential module 21. The upper cavity of the gain module 22 is connected to the upper cavity of the differential module 21, and the liquid outlet 24 of the lower cavity of the gain module 22 is connected to the balance valve seat 8 of the lower cavity of the differential module 21. The balance valve seat 8 is connected to the drug inlet pipe 3; the branch pipe 16 has a built-in pressure-conducting isolation sleeve 9, the inner side of which is connected to the hydraulic oil 20 in the upper cavity of the differential pressure module 21, and the outer side is connected to the liquid medicine in the drug inlet pipe 1. One end of the branch pipe 16 is connected to the drug inlet pipe 1, and the other end is connected to the upper cavity of the differential pressure module 21; the flow limiting module 2 is composed of an orifice plate chamber 11 and a flow regulating valve 12 connected in series. The orifice plate chamber 11 is provided with a flow limiting orifice plate 13 inside and two differential pressure transmitter connecting pipes 17 outside. One end of the flow limiting module 2 is connected to the drug outlet pipe 1, and the other end is connected to the liquid outlet 24 in the lower cavity of the differential pressure module 21; one end of the drug outlet pipe 3 is connected to the flow limiting module 2 and the branch pipe 16, and the other end is connected to the drug dosing point.

[0270] like Figure 12 As shown, the orifice plate chamber 11 is connected to a differential pressure transmitter 18 via a differential pressure transmitter connecting pipe 17. The differential pressure transmitter 18 is connected to a flow totalizer 19. The flow totalizer 19 uploads the instantaneous flow rate, cumulative flow rate, and liquid level data of the storage tank to the central control system to achieve information-based monitoring.

[0271] The rubber diaphragm 5 is installed inside the housing 4, separating the inner cavity of the housing 4 into an upper cavity and a lower cavity;

[0272] The rubber diaphragm 5 has a stainless steel reinforcing plate inside its abdominal portion. The stainless steel reinforcing plate and the balance valve core 7 move up and down with the compression spring 23.

[0273] The compression spring 23 is fixed to the rubber diaphragm 5, which drives the middle part of the rubber diaphragm 5 to move up and down.

[0274] The inlet pipe 1 is connected to the storage tank 14 and is used to transport the liquid medicine;

[0275] The main valve 15 is installed on the drug inlet pipe 1 to control the flow of the drug solution.

[0276] The flow limiting module 2 is located after the solid difference module 21 and before the drug outlet pipeline 3, and controls the flow area and detects and outputs the pressure difference value on both sides of the flow limiting orifice plate.

[0277] The pressure-conducting isolation sleeve 9 isolates the inner hydraulic oil from the outer liquid medicine and makes the pressure on both sides equal.

[0278] The differential pressure transmitter connecting pipe 17 is connected to the differential pressure transmitter 18. The differential pressure transmitter 18 transmits electrical signals to the flow totalizer 19. The totalizer 19 can display and upload data such as flow rate in real time.

[0279] Differential pressure drift and differential pressure constraints:

[0280] The solidity module and the solidity + gain module have balance valve seat to diaphragm cavity cross-sectional area ratios of C and C, respectively. 增 If the design flow drift rate is E%, then for every meter increase in the static pressure Hn of the storage tank, the pressure difference drift ΔHp before and after the flow-limiting module of both the fixed differential module structure and the fixed differential + gain module structure will be... 压差 They respectively satisfy:

[0281] Solid-state module structure: △Hp 压差 = C / (C-1)

[0282] Solidity + Gain Module Structure: △Hp 压差 = C·C 增 / (1-C)·(1-C) 增 )

[0283] Spring compensation pressure constraint conditions:

[0284] The spring compensation pressure Ht of the solidity module structure and the solidity + gain module structure satisfies:

[0285] Solid-state module structure: Ht ≥ + C·Hn

[0286] Solidity + Gain Module Structure: Ht 增 ≥ + C 增 ·Hn

[0287] Ht ≥ ·(Ht增 + ) ·Hn

[0288] C·Hn, C 增 ·Hn、 ·Hn represents the calibration compensation value for the solid-state module structure and the solid-state + gain module structure, respectively.

[0289] Orifice flow area constraint conditions:

[0290] The current limiting module is designed with a differential pressure of A, and a design installation space height of y·A (y is a coefficient, referring to A multiplied by y). The design height is Ht. 增 = x·A (where x is a coefficient, referring to taking A as x times), then the flow area slimited of the flow-limiting module's flow-limiting orifice, sbalanced of the solid-difference module's balance valve seat, and sgain of the balance valve seat are... 增 The flow area relationship of the three orifices satisfies:

[0291] ;

[0292] 2. Derivation of the mechanical equilibrium equations and various constraint conditions:

[0293] The derivation results are completely consistent with those in Example 1, and will not be repeated here.

[0294] 3. Analysis of the working process of this embodiment:

[0295] When the main valve is closed: the rubber diaphragms of the differential module and the gain module are pressed to the bottom by the compensating pressure Ht and Ht+ of the compression spring; the balance valve seats of the two modules are fully open at this time.

[0296] After the main valve is opened: the liquid medicine enters the lower chamber of the gain module through the inlet pipe, flows out through the outlet, then enters the differential pressure module, and then flows into the flow limiting module through the outlet of the differential pressure module. Due to the flow limiting of the flow limiting module, the lower chambers of the gain module and the differential pressure module are filled with liquid medicine, and the pressure gradually increases. The opening of the two balance valves also gradually decreases. When the pressure in the lower chamber of the differential pressure module rises to (Ht + H) 出 When the pressure in the upper and lower chambers reaches equilibrium (Ht), the valve core and seat opening remains relatively stable. When the pressure in the lower chamber of the gain module rises to (Ht... 增 + H 出 When the pressure in the upper and lower chambers reaches equilibrium, the opening of the valve core and seat of the flow limiting module also remains relatively stable. At this time, the pressure difference across the flow limiting module remains stable, and the flow rate of the device remains unchanged.

[0297] When the pressure Hn in the drug inlet tube changes: the lower chamber force of the gain module is determined by (Ht)增 + H 出 S is a fixed value, and the pressure in the upper and lower chambers is balanced. (Ht) 增 + H 出 S = H 下 ·(1- C)·S + Hn·C·S, when the pressure in the inlet pipe changes When ΔHn, that is: (Ht) 增 + H 出 )· S = H 下 ·(1- C)·S+ (Hn ΔHn)·C·S, to maintain the equilibrium of the formula, H 下 This will result in a corresponding change, namely the pressure drift in the lower chamber of the gain module that we analyzed and calculated earlier. Similarly, the fixed-variance module also has a pressure drift problem in the lower chamber, but the drift generated by the fixed-variance module is smaller, and its unit pressure drift is = Approaching 0, as long as Hp 压差 The flow rate drift caused by the value is within the design requirement E%. The pressure change in the lower cavity of the fixed differential module can be ignored. For the flow limiting module, the pressure difference before and after it can be regarded as unchanged, and the flow rate remains unchanged.

[0298] Drug outlet pressure H 出 When the pressure in the drug delivery pipeline changes: ΔH 出 At that time, the pressure-conducting isolation sleeve will... ΔH 出 Synchronous conduction is performed to the upper cavities of the solid-state module and the gain module, while the lower cavities of the solid-state module and the gain module must be synchronized. ΔH 出 Only then can a new balance be achieved, and at the same time, the output of the current limiting module will also increase. ΔH 出 Regarding the current limiting module, upstream and downstream synchronization is required. ΔH 出 Since the pressure difference remained unchanged, the flow rate also remained unchanged.

[0299] Compression spring structure and tension spring structure are essentially twin structures. Except for the installation position of the flow limiting module and the order of liquid flow through each stage, the various constraints and mathematical models are completely the same.

[0300] (III) Flow rate adjustment in Examples 1 and 2:

[0301] The principle of this invention is to keep the pressure difference across the flow-limiting module constant and change the flow rate by altering the cross-sectional area of ​​the flow passage. When the flow area of ​​the flow regulating valve is smaller than the orifice area of ​​the flow-limiting orifice plate, the actual flow area is the flow area of ​​the flow regulating valve, its minimum opening is 0, and the flow rate is 0. When the flow area of ​​the flow regulating valve is larger than the orifice area of ​​the flow-limiting orifice plate, the actual flow area is the orifice area of ​​the flow-limiting orifice plate, and the flow rate is the maximum (upper limit) flow rate of this device. The structure of this invention always follows the latter pattern.

[0302] The differential pressure transmitter is connected to the differential pressure transmitter via a connecting pipe. The differential pressure is converted into an electrical signal and sent to the flow totalizer. The flow totalizer processes the data and displays the required parameters such as instantaneous flow rate, cumulative flow rate, and liquid level in the storage tank. At the same time, the data is synchronously uploaded to the central control room via the communication interface.

[0303] (iv) Installation schemes for Examples 1 and 2:

[0304] Standard installation method:

[0305] When Hmin-hmax ≥ 1 meter, the installation conditions for gravity dosing are met, and it can be directly installed in the pipeline without being restricted by the requirement that it must be higher than the liquid level in the reaction tank.

[0306] Extended installation methods:

[0307] Water jet auxiliary dosing (with) Figure 13 ):

[0308] When Hmin-hmax < 1 meter, or even Hmax < h, the vacuum at the water jet nozzle can be used to create a reverse gravity dosing system for chemical dosing. This method is more suitable for water plants, as it is simpler, more reliable, and more energy-efficient than pump-driven systems. Current gravity dosing devices are all open systems and cannot create a closed vacuum, thus failing to achieve the desired effect.

[0309] Pump-driven auxiliary dosing (with) Figure 14 )

[0310] When Hmin-hmax < 1 meter, or even when Hmax < h, power sources such as acid-resistant pumps and diaphragm pumps can be used for power injection. In this case, the main function of this device is to control and measure the flow rate. It cannot utilize the gravity of the liquid itself, resulting in high energy consumption, which is not recommended.

[0311] The above installation method enables this device to be applied to various scenarios, comprehensively solving the problem of installation limitations.

[0312] (V) On-site flow rate calibration in Examples 1 and 2:

[0313] After the device is installed according to the installation requirements, calibration begins when the liquid level in the storage tank is at the middle level.

[0314] a.

[0315] Spring structure device: The spring of the solidity module is pulled to its tightest position, and the spring tension of the gain module is completely released;

[0316] Compression spring structure device: compresses the compression spring of the differential module to its maximum and completely releases the compression spring pressure of the gain module;

[0317] b. Open the main valve;

[0318] c. Fully open the flow regulating valve (7);

[0319] d. Tighten the gain module spring setting handle 25, and observe the flow display window at the same time. When the flow data reaches the rated flow on the device's nameplate, stop adjusting.

[0320] e. Newly installed devices must be observed for a period of time until the air in the pipelines and devices has been completely drained with the liquid.

[0321] f. Observe the flow display window. If the flow rate is drifting, readjust the fixed differential module spring setting handle 25 until the flow rate reaches the rated flow rate on the device's nameplate. Then, continue to turn it 1 / 2 to 1 / 3 turn. At this time, the displayed flow rate will be slightly higher than the rated flow rate. Lock the spring.

[0322] g. Adjust the spring setting lever 25 of the differential module while observing the flow display window. Stop when the flow data reaches the rated flow and lock the spring.

[0323] h. Once the on-site calibration is completed, the device can be put into normal use.

[0324] Gravity dosing systems are static pressure controlled (H constant) systems. The flow rate (velocity) of the liquid in the system is independent of the specific gravity of the liquid. Therefore, the flow rate calibrated with water when the device leaves the factory may differ from the specific gravity of the liquid at each application site, but the flow rate of the liquid after on-site calibration is still the same as that at the factory. This has been proven in fluid mechanics and will not be elaborated here.

[0325] Other factors affecting flow measurement include liquid viscosity and temperature, but fortunately these factors have little impact and do not affect the use of the device, so no special compensation is needed and they are ignored here.

Claims

1. A flow control metering device for on-site calibration of gravity dosing systems, characterized in that: It includes a drug inlet pipe, branch pipes, a flow-limiting module, a differential pressure module, and a drug outlet pipe. The drug inlet pipe connects to a drug storage tank and is equipped with a main valve. The differential pressure module includes a housing, a rubber diaphragm, a tension spring, a balance valve core, and a balance valve seat. The rubber diaphragm is fixedly installed inside the housing, dividing the housing cavity into an upper and lower cavity. The tension spring is placed in the upper cavity, with its upper end connected to the top of the upper cavity and its lower end fixed to the upper side of the rubber diaphragm. The balance valve core is placed in the lower cavity and fixed to the lower side of the rubber diaphragm. The balance valve seat is located at the bottom of the lower cavity of the differential pressure module, and the balance valve core is located directly above the balance valve seat. The opening and closing of the balance valve core and the balance valve seat... The degree changes with the up-and-down movement of the rubber diaphragm; one end of the branch pipe is connected to the drug inlet pipe, and the other end is connected to the upper cavity of the differential pressure module; the branch pipe has a built-in pressure-conducting isolation sleeve, and hydraulic oil is provided in the upper cavity. The inner side of the pressure-conducting isolation sleeve is connected to the hydraulic oil in the upper cavity of the differential pressure module, and the outer side of the pressure-conducting isolation sleeve is connected to the liquid inlet pipe. The flow-limiting module is composed of an orifice plate chamber and a flow regulating valve connected in series. The orifice plate chamber is provided with a flow-limiting orifice plate, and two differential pressure transmitter connecting pipes are provided on the outside. One end of the flow-limiting module is connected to the drug inlet pipe, and the other end is connected to the liquid inlet of the lower cavity of the differential pressure module; the balance valve seat of the lower cavity of the differential pressure module is connected to the drug outlet pipe, and the other end of the drug outlet pipe is connected to the drug dosing point.

2. The flow control metering device for on-site calibration of gravity dosing systems according to claim 1, characterized in that: It also includes a gain module, which has the same structure as the solid difference module and is connected in series after the solid difference module. The upper cavity of the gain module is connected to the upper cavity of the solid difference module, the liquid inlet of the lower cavity of the gain module is connected to the balance valve seat of the lower cavity of the solid difference module, and the balance valve seat of the lower cavity of the gain module is connected to the drug outlet pipeline.

3. A flow control metering device for on-site calibration of gravity dosing systems, characterized in that: It includes a drug inlet pipe, a differential pressure module, branch pipes, a flow-limiting module, and a drug outlet pipe; the drug inlet pipe connects to a drug storage tank, and a main valve is installed on the drug inlet pipe; the differential pressure module includes a shell, a rubber diaphragm, a compression spring, a balance valve core, and a balance valve seat. The rubber diaphragm is fixedly installed inside the shell, dividing the shell's inner cavity into an upper cavity and a lower cavity. The compression spring is placed in the upper cavity, with its upper end connected to the top of the upper cavity and its lower end fixed to the upper side of the rubber diaphragm. The balance valve core is placed in the lower cavity and fixed to the lower side of the rubber diaphragm. The balance valve seat is located at the bottom of the lower cavity of the differential pressure module, and the balance valve core is located directly below the balance valve seat. The opening degree between the balance valve core and the balance valve seat changes as the rubber diaphragm moves up and down; one end of the branch pipe is connected to the drug outlet pipe, and the other end is connected to the upper cavity of the differential pressure module. The branch pipe has a built-in pressure-conducting isolation sleeve. Hydraulic oil is provided in the upper cavity of the differential pressure module. The inner side of the pressure-conducting isolation sleeve is connected to the hydraulic oil in the upper cavity of the differential pressure module, and the outer side is connected to the drug liquid in the drug outlet pipe; the flow limiting module is composed of an orifice plate chamber and a flow regulating valve connected in series. The orifice plate chamber is provided with a flow limiting orifice plate, and two differential pressure transmitter connecting pipes are provided on the outside. One end of the flow limiting module is connected to the drug outlet pipe, and the other end is connected to the liquid outlet of the lower cavity of the differential pressure module; the other end of the drug outlet pipe is connected to the drug dosing point.

4. A flow control metering device for on-site calibration of a gravity dosing system according to claim 1 or 3, characterized in that: The rubber diaphragm has a corrugated diaphragm structure with stainless steel reinforcing plates built into the middle.

5. A flow control metering device for on-site calibration of a gravity dosing system according to claim 1 or 3, characterized in that: The orifice plate chamber of the flow limiting module is connected to a differential pressure transmitter via a differential pressure transmitter connecting pipe, and the differential pressure transmitter is connected to a flow totalizer.

6. A flow control metering device for on-site calibration of a gravity dosing system according to claim 3, characterized in that: It also includes a gain module, which has the same structure as the solid difference module and is connected in series before the solid difference module. The upper cavity of the gain module is connected to the upper cavity of the solid difference module, the liquid outlet of the lower cavity of the gain module is connected to the balance valve seat of the lower cavity of the solid difference module, and the balance valve seat of the lower cavity of the gain module is connected to the drug inlet pipe.

7. A flow control metering device for on-site calibration of a gravity dosing system according to claim 2 or 6, characterized in that: The ratios of the flow area of ​​the balance valve seat to the cross-sectional area of ​​its inner cavity in the aforementioned differential and gain modules are C and C, respectively. 增 For every meter increase in the static pressure Hn of the drug storage tank, the pressure difference drift ΔHp before and after the current-limiting module of both the fixed differential module structure and the fixed differential + gain module structure will increase. 压差 They respectively satisfy: Solid-state module structure: △Hp 压差 = C / (C-1) Solidity + Gain Module Structure: △Hp 压差 = C·C 增 / [(1-C)·(1-C) 增 )].

8. A flow control metering device for on-site calibration of a gravity dosing system according to claim 7, characterized in that: The compensation pressure Ht of the compression spring or tension spring of the solid difference module structure and the solid difference + gain module structure respectively satisfies: Solid-state module structure: Ht ≥ + C·Hn Solidity + Gain Module Structure: Ht 增 ≥ + C 增 ·Hn Ht ≥ ·(Ht 增 + )+ ·Hn Where: E% is the design flow drift rate, C·Hn, C 增 ·Hn、 ·Hn represents the calibration compensation value for the solid-state module structure and the solid-state + gain module structure, respectively.

9. A flow control metering device for on-site calibration of a gravity dosing system according to claim 8, characterized in that: The upper end of the tension spring or compression spring is connected to a spring setting handle, which is installed on the upper part of the upper cavity of the solidity module and the gain module to calibrate the compensation values ​​C·Hn and C. 增 ·Hn The specific value of Hn needs to be determined by adjusting the spring setting handles of the gain module and the differential module on-site, based on the liquid level Hn in the on-site storage tank.

10. A flow control metering device for on-site calibration of a gravity dosing system according to claim 2 or 6, characterized in that: The current limiting module is designed with a differential pressure of A and a design installation space height of y·A, where y is a coefficient, referring to a multiple of A. The design height is Ht. 增 = x·A, where x is a coefficient, referring to taking A as x times, then the flow area s of the flow-limiting module's flow-limiting orifice. 限 , Solid difference module balance valve seat flow area s, Gain module balance valve seat flow area s 增 The flow area relationship of the three orifices satisfies: ； 。

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