CN106807245A - A kind of hollow fiber ultrafiltration membrane rejection detection means based on PLC - Google Patents
A kind of hollow fiber ultrafiltration membrane rejection detection means based on PLC Download PDFInfo
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- CN106807245A CN106807245A CN201510873254.9A CN201510873254A CN106807245A CN 106807245 A CN106807245 A CN 106807245A CN 201510873254 A CN201510873254 A CN 201510873254A CN 106807245 A CN106807245 A CN 106807245A
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Abstract
A kind of hollow fiber ultrafiltration membrane rejection detection means based on PLC, is made up of detection part and control section.Solve current hollow fiber ultrafiltration membrane rejection detection means automaticity low, handoff procedure has pollution, regulation uncertainty is big manually, be difficult to quantitative control separation condition.The detection means perfect in shape and function, improves the shortcoming that conventional detection means is present.Using s7-200 series of PLC as master controller, using touch-screen as man-machine interface, the controllable and visual of experimentation is realized.Detection means design is analyzed operation principle first, and then the software and hardware to control system has carried out relevant design.Because the regulation process of constant pressure difference and flow velocity has a Multivariable Coupling phenomenon, therefore it is adjusted and obtain satisfied dynamic and static state performance to devise fuzzy controller.
Description
Technical field
The present invention relates to a kind of detection means, more particularly to a kind of hollow fiber ultrafiltration membrane rejection detection means based on PLC.
Background technology
Early 1980s, China begins one's study hollow fiber ultrafiltration membrane.Hollow fiber ultrafiltration membrane with its unit volume membrane area it is big, without supporting mass, easily controllable quality the advantages of and furtherd investigate and extensive use.Rejection is the important indicator for characterizing hollow fiber ultrafiltration membrane separating property.By investigation, in hollow fiber ultrafiltration membrane examination and test of products index on the market, rejection inspection ratio is up to 65%；Meanwhile, film manufacturer is wished in the index of third party authoritative institution inspection, and rejection inspection ratio also reaches 55%.National center of ocean standard and metrology is the third party authoritative institution for detecting liquid separating film, a part in this problem Shi Gai centers " hollow fiber ultrafiltration membrane performance detection technology platform development project ", it is intended to design a set of perfect in shape and function, high degree of automation, the hollow fiber ultrafiltration membrane rejection detection means for controlling separation condition can be quantified.This is to promoting China's hollow fiber ultrafiltration membrane industry to develop in a healthy way and participate in market competition significant old.
The content of the invention
It is low that the purpose of the present invention is directed to current hollow fiber ultrafiltration membrane rejection detection means automaticity, there is pollution in handoff procedure, regulation uncertainty is big manually, be difficult to quantitative control separation condition, devises a kind of hollow fiber ultrafiltration membrane rejection detection means based on PLC.
The technical solution adopted for the present invention to solve the technical problems is：Hollow fiber ultrafiltration membrane rejection detection means based on PLC is made up of detection part and control section.0.05~0.15MPa continuously adjustabe average transmembrane pressure differences are capable of achieving, regulation step-length is better than 0.01 MPa；On the premise of keeping constant average transmembrane pressure difference, crossflow velocity is linear adjustable in 0.05-0.6-n/s, and regulation step-length is better than 0.01 In/s；Test fluid temperature is adjustable in 20~50 DEG C, and regulation step-length is better than 0.1 DEG C；Also there is the automatic regulation function of " constant pressure difference and flow velocity ".
Described detection part is made up of polysulfone hollow fiber ultrafiltration membrane system, constant temperature reservoir, peristaltic pump, surge tank, pressure sensor, turbine flowmeter, mass flowmenter, manually-operated gate, relief valve, three-way magnetic valve, normally open solenoid valve, normally closed solenoid valve, electric control valve etc..The all pipelines of the detection means and parts select food-grade stainless steel 316 or highstrenghtpiston as material, to ensure Chemical cleaning to whole system without parsing.
The control main frame of described control section selection is the CPU224 in 7-200 series of PLC, and analog quantity spread module is EM231, EM232, EM235, and man-machine interface is Smartl000IE.
Described temperature adjustment is realized by constant temperature reservoir.
Described average transmembrane pressure difference and crossflow velocity are realized by adjusting wriggling pump discharge and motorized adjustment valve opening.
Described constant pressure difference and flow velocity refers in following function：Average transmembrane pressure difference and crossflow velocity are set on touch-screen, then acting wriggling pump discharge and E7, E8 aperture makes actual average transmembrane pressure and flow velocity reach setting value.
The beneficial effects of the invention are as follows：The detection means perfect in shape and function invented, high degree of automation is currently in trial operation stage, various functions stabilization.Automatic constant pressure difference and flow rate function based on fuzzy control realize separation condition and quantitatively control, and simplify the During manual operation of experimenter, improve its operating efficiency.In milipore filter performance indications evaluate detecting system, the covering device is significant, has good directive function to the exploitation of milipore filter other performance index detection means.
Brief description of the drawings
The present invention is further described with reference to the accompanying drawings and examples.
Fig. 1 is hollow fiber ultrafiltration membrane rejection detection means schematic diagram.
Fig. 2 is PLC control system external wiring diagram.
Fig. 3 is PLC control system main program flow chart.
Fig. 4 is Basic Principle of Fuzzy Control System figure.
Specific embodiment
As shown in Figure 1, detection part by constant temperature reservoir A, peristaltic pump B, surge tank C, polysulfone hollow fiber ultrafiltration membrane system D, sampling container E, electronic scale F, temperature sensor T1/To/TP, pressure sensor PL/P0/PP, turbine flowmeter V1, mass flowmenter v2, manually-operated gate K1/K2/K3/K4/K5/K6 ,=relief valve K7, three-way magnetic valve E1/E4/E5/E9, normally open solenoid valve E2/E6, normally closed solenoid valve E3, electric control valve E7/E8 constitute.Rejection represents the ability that milipore filter removes specific components, and relational expression is as follows：Ru=(C2 of C1 mono-)/C1 × 100%, in formula, Ru is rejection (%)；C1 is solute concentration (mg/L) in raw water；C2 is solute concentration (mg/L) in product water.This be it is a kind of with standard substance by milipore filter when retention characteristic show a kind of method of membrane aperture size.Herein using detection means as an experiment porch, possess perfect function, can be with the operation of interior external pressure, anti-cleaning, regulation and control separation condition, sampling etc..By investigation extensively and improvement, all pipelines of the detection means and parts select food-grade stainless steel 316 or highstrenghtpiston as material, to ensure Chemical cleaning to whole system without parsing.E1, E4, E5 conducting direction are respectively El mono- 2, E4-2, E5-1, and E2 is normally opened, and E3 is normally closed.This valve state is combined for carrying out inner pressed hollow fiber ultrafiltration membrane experiment, and test fluid flow direction is as follows in experimentation：Raw water enters D by A, B, C, K6, V1, PI, T1, K7, E1-2；Produce water and converge to b points into water producing pipe road by E2 and E4-2, then A is returned by TO, PO, E8；Concentrated water reaches a points and enters concentrated water pipeline by E5-1, then returns to A by 11P, PP, E6, V2, E7, E9-1.As E1, E2, E3, E4：When E5 is inverse state, the external pressure type hollow fiber hyperfiltration membrane assembly of detection means is tested, and test fluid flow direction and inner pressed are basically identical, but raw water enters D by E1-1, produce water and converge to b points into water producing pipe road by E3 and E5-2, concentrated water reaches a points and enters concentrated water pipeline by E4-1.It can be found that when environment changing is tested in inside/outside compacting, produce water and concentrated water pipeline does not switch, the defect that the exactly conventional detection means of this point is present.Concentrated water and the switching of water producing pipe road can cause the pollution of test fluid, influence certainty of measurement.
The key of experiment is the regulation and control to separation condition, and the goal of regulation and control to be realized of detection means of the present invention is：0.05~0.15 MPa continuously adjustabe average transmembrane pressure differences, regulation step-length is better than 0.01 MPa；On the premise of keeping constant average transmembrane pressure difference, crossflow velocity is linear adjustable in 0.05-0.6-n/s, and regulation step-length is better than 0.01 In/s；Test fluid temperature is adjustable in 20~50 DEG C, and regulation step-length is better than 0.1 DEG C.Wherein, average transmembrane pressure difference relational expression is as follows：Pmtm=(Pi+Po)/2 one Pp, in formula, Pmtm is average transmembrane pressure difference (Kpa)；Pi is membrane module inlet pressure (Kpa)；Po is membrane module concentrated water outlet pressure (Kpa)；Pp is that membrane module produces water out pressure (Kpa).Crossflow velocity relational expression is as follows：Vuf=Quf/S/3600, in formula, Vuf is crossflow velocity (m/s)；Quf is membrane module concentrated water flow (m3/ h)；S is film cross-sectional area (m2).Temperature adjustment is realized by constant temperature reservoir.Average transmembrane pressure difference and crossflow velocity are realized by adjusting wriggling pump discharge and E7, E8 aperture.Average transmembrane pressure difference and crossflow velocity are set on the touchscreen, and then acting wriggling pump discharge and E7, E8 aperture makes actual average transmembrane pressure and flow velocity reach setting value, and this function is referred to as " constant pressure difference and flow velocity ".There is Multivariable Coupling phenomenon in regulation process, change wriggling pump discharge, E7 apertures, E8 apertures wherein any one, and pressure difference and flow velocity can all change.Realize that " constant pressure difference and flow velocity " automatic regulation function is the research emphasis of this paper.Separating experiment is carried out under certain separation condition, the stable rear E9 that passes through is to product water sampling, then just can obtain rejection final result by follow-up optical analysis.
As shown in Fig. 2 the control main frame of control section selection is the CPU224 in 7-200 series of PLC, analog quantity spread module is EM231, EM232, EM235, and man-machine interface is Smartl000IE.All electrical equipments select external power supply.The pulse signal amplitude of turbine flowmeter output is 5 V, it is necessary to could be collected by PLC high-speed counters by optocoupler amplifier.The operating current of magnetic valve is beyond CPU output point rated current, so output point controls electromagnetic valve switch state by controlling electromagnetic relay contact break-make.Electromagnetic relay is inductive load, and a momentary spikes voltage can be produced between folding moment two contact, easily causes the metal migration of contact and aoxidizes, and can avoid the bad phenomenon by fly-wheel diode in parallel.Normal work by touch-screen need to only switch on power, a piece MPI cable of connection and CPU between, then process is simply provided.
As shown in figure 3, PLC realizes control function by the user program that reaction controlling is required.User program includes main program, some subprograms and interrupt service routine, PLC scan round main programs always.Write and the implementation procedure of PLC program are serial modes, and do not have sequencing between the most of functions of the device, but to be called at any time according to demand for control.So in program design, all function subprograms have been carried out into serial sort according to experiment flow, the logic of program was so both ensured, also the integrality of assurance function.The operational order of experimenter sends PLC to by person-computer union.The design of PLC main programs is in addition to possessing these basic functions such as the selection of inside/outside pressure, sampling, backwash, automatic/hand constant pressure difference and flow velocity, it is contemplated that the friendly of human-computer interaction, further being supplemented from the angle of experimenter makes main program function more perfect.For example, parameter setting subprogram, it allows the operating personnel liquid-tight degree of input test, effective membrane area, system time etc. on the touchscreen.The regulation process of constant pressure difference and flow velocity includes two inputs and 3 outputs, respectively average transmembrane pressure differential resetting value, crossflow velocity setting value and peristaltic pump flow control signal, E7 opening control signals, E8 opening control signals.The decoupling of this process is complicated, it is difficult to it is determined that accurate Mathematical Modeling.Fuzzy control is a kind of wide variety of intelligent control method, is particularly well-suited to unknown, the complicated luxuriant and rich with fragrance linear system of Controlling model.The control experience and knowledge of operator or expert can be stated as the rule of linguistic variable description for fuzzy control, then go control system with these rules.So, the present invention devises fuzzy controller to realize automatic constant pressure difference and flow velocity.
As shown in figure 4, according to controlled device feature, fuzzy control principle of the present invention is as schemed.Ep, eu are actual average transmembrane pressure and crossflow velocity deviation；Kep, Keu are input quantizing factor；EP, EU are input quantized value；U1, U2, U3 are that fuzzy controller quantifies output；Ku1, Ku2, Ku3 are the output quantization factor；U1, u2, u3 are reality output amount.Consider the factors such as control accuracy, control algolithm complexity and control stability, the quantification gradation of two defeated people's linguistic variables and 3 output language variables is set to -3, -2, -1,0, l, 2,3, Linguistic Value is set to { NB, NM, NS, Z, PS, PM, PB }, from Triangleshape grade of membership function.The implementation process of fuzzy controller is as follows：1. two basic domain interval [a.b] round off principles of input are quantified as the domain element of domain interval [n, n] respectively according to formula y=2n [e- (a-b)/2]/(b-a) for obfuscation；Fuzzy Linguistic Variable assignment table is obtained further according to membership function.2. this process of fuzzy reasoning includes that degree of membership is assembled and rale activation.Degree of membership aggregation is exactly, by Fuzzy Linguistic Variable assignment table, to determine the final obfuscation result of input quantity；If certain regular precondition is met, the rule is activated, and exports corresponding controlled quentity controlled variable.The foundation of rule base is based on manual control strategy, relies on the priori of operating personnel.For example, when two deviations are PB, the amplitude of wriggling pump discharge increase should be increased；Deviation ep is PM, and when deviation eu is Ns, the amplitude that E7 and E8 apertures reduce should reduce；Deviation ep is Ns, and when deviation eu is z, fine setting reduces E7 apertures.3. the controlled quentity controlled variable that output quantity defuzzification fuzzy reasoning is obtained is that the fuzzy subset on Fuzzy Linguistic Variable domain could obtain the quantized value of controlled quentity controlled variable, it is necessary to be weighted the method for average and carry out inverse fuzzy operation.In order to save internal memory, response speed is improved, the present invention utilizes Fuzzy Linguistic Variable assignment table and fuzzy rule base, offline fuzzy Control query table is established according to Larsen rationalistic method.
Claims (6)
1. a kind of hollow fiber ultrafiltration membrane rejection detection means based on PLC, is made up of detection part and control section；0.05~0.15MPa continuously adjustabe average transmembrane pressure differences are capable of achieving, regulation step-length is better than 0.01 MPa；On the premise of keeping constant average transmembrane pressure difference, regulation step-length is better than 0.01 In/s；Test fluid temperature is adjustable in 20~50 DEG C, and regulation step-length is better than 0.1 DEG C；Also there is the automatic regulation function of " constant pressure difference and flow velocity ".
2. the hollow fiber ultrafiltration membrane rejection detection means based on PLC according to claim 1, it is characterized in that described detection part is made up of polysulfone hollow fiber ultrafiltration membrane system, constant temperature reservoir, peristaltic pump, surge tank, pressure sensor, turbine flowmeter, mass flowmenter, manually-operated gate, relief valve, three-way magnetic valve, normally open solenoid valve, normally closed solenoid valve, electric control valve etc.；The all pipelines of the detection means and parts select food-grade stainless steel 316 or highstrenghtpiston as material, to ensure Chemical cleaning to whole system without parsing.
3. the hollow fiber ultrafiltration membrane rejection detection means based on PLC according to claim 1, it is characterized in that the control main frame of described control section selection is the CPU224 in 7-200 series of PLC, analog quantity spread module is EM231, EM232, EM235, and man-machine interface is Smartl000IE.
4. the hollow fiber ultrafiltration membrane rejection detection means based on PLC according to claim 1, it is characterized in that described temperature adjustment is realized by constant temperature reservoir.
5. the hollow fiber ultrafiltration membrane rejection detection means based on PLC according to claim 1, it is characterized in that described average transmembrane pressure difference and crossflow velocity are realized by adjusting wriggling pump discharge and motorized adjustment valve opening.
6. the hollow fiber ultrafiltration membrane rejection detection means based on PLC according to claim 1, it is characterized in that described constant pressure difference and flow velocity refer in following function：Average transmembrane pressure difference and crossflow velocity are set on touch-screen, then acting wriggling pump discharge and E7, E8 aperture makes actual average transmembrane pressure and flow velocity reach setting value.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108181479A (en) * | 2017-12-25 | 2018-06-19 | 南京工业大学 | Automatic analyzer for molecular weight cut-off of membrane |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108181479A (en) * | 2017-12-25 | 2018-06-19 | 南京工业大学 | Automatic analyzer for molecular weight cut-off of membrane |
| CN108181479B (en) * | 2017-12-25 | 2022-01-07 | 南京工业大学 | Automatic analyzer for molecular weight cut-off of membrane |
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Application publication date: 20170609 |