CN100554957C - The on-line continuous detection method of mother liquid of polyvinyl alcohol - Google Patents
The on-line continuous detection method of mother liquid of polyvinyl alcohol Download PDFInfo
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- CN100554957C CN100554957C CNB2005100273391A CN200510027339A CN100554957C CN 100554957 C CN100554957 C CN 100554957C CN B2005100273391 A CNB2005100273391 A CN B2005100273391A CN 200510027339 A CN200510027339 A CN 200510027339A CN 100554957 C CN100554957 C CN 100554957C
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- pva
- stoste
- polyvinyl alcohol
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- temperature
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Abstract
A kind of on-line continuous detection method that is used for the mother liquid of polyvinyl alcohol in technological parameter detection technique field, step is as follows: 1) on the top of PVA stoste preparation still a gaseous pressure measuring point is set, at this place's setting pressure transmitter, the range of this transmitter is determined according to the maximum pressure in the PVA stoste preparation still; 2) in the bottom of PVA stoste preparation still a liquid phase P VA stoste temperature transmitter is set,, selects the temperature transmitter of suitable range for use according to the variation range of temperature of charge; 3) record gaseous pressure in the PVA stoste preparation still by above-mentioned pressure unit, temperature transmitter records PVA stoste boiling temperature, will above two signals access Distributed Control System (DCS) or intelligence instrument, promptly try to achieve the concentration of PVA stoste according to operational model.The present invention adopts conventional instrument to get final product the online PVA of obtaining original liquid concentration, and method is simple, realizes easily.
Description
Technical field
What the present invention relates to is a kind of on-line detection method that is used for the detection technique field, specifically, is a kind of on-line continuous detection method of mother liquid of polyvinyl alcohol.
Background technology
Polyvinyl industry is the textile raw material production industry of producing vinylon fibre etc., and its product is widely used in departments such as weaving, papermaking, building materials.Wherein, the aqueous solution of polyvinyl alcohol (PVA) (PVA) is as the stoste of spinning, and spinning technique has strict requirement to its concentration change scope, and absolute error requires ± 0.2% usually.The process for preparation of polyvinyl alcohol (PVA) stoste is: according to the concentration requirement of technology to PVA stoste, calculate the required solvent water yield and PVA amount (usually contain among the PVA 20% to 50% moisture content do not wait), add in the stoste preparation still after being heated to water about 90 degree, the PVA material is added in the stoste preparation still again, and stir; Feed chuck with steam and heat,, the PVA aqueous solution need be heated to fluidized state usually, so that the dissolving of PVA because that PVA is difficult for is soluble in water.In the scope that the concentration of PVA stoste is just in time requiring, then the stoste preparation promptly comes to an end, and stoste send follow-up spinning process to use.Be lower than requirement as the PVA original liquid concentration, then need add suitable substance P VA material; And when the PVA original liquid concentration is higher than requirement, then by continuing heating evaporation aqueous solvent wherein to improve the concentration of stoste, till reaching the requirement of technology to original liquid concentration.At present still do not have suitable detection means that the PVA original liquid concentration is carried out online detection, can only obtain by the laboratory sampling analysis.The problem of doing existence like this is: the human factor of manual analysis is inevitable; Sample analysis generally needs 30 to 45 fens clock times, and is big like this time lag, little to the directive significance of process.
Find patent of invention number by prior art documents: 01113259.0, denomination of invention: the on-line continuous detection method of concentration and density of liquid medium.The precondition of this patent of invention tracer liquid concentration of medium is: its density of different concentration is also different.This precondition is set up suitable a big chunk liquid medium.But regrettably, PVA stoste does not satisfy this condition: promptly under concentration differed bigger situation, its variable density was very little, and existing detection means can not detect this variation.Therefore, must adopt other suitable method that the PVA original liquid concentration is carried out on-line continuous detects.
Summary of the invention
The objective of the invention is to overcome deficiency of the prior art and limitation, a kind of on-line continuous detection method of mother liquid of polyvinyl alcohol is provided, makes it adopt conventional instrument to get final product online acquisition mother liquid of polyvinyl alcohol information, method is simple, realize that applicable scope is wide easily.
The present invention is achieved through the following technical solutions, and concrete steps are as follows:
1) on the top of PVA stoste preparation still a gaseous pressure measuring point is set, at this place's setting pressure transmitter, the range of this transmitter is determined according to the maximum pressure in the polyvinyl alcohol (PVA) stoste preparation still;
2) in the bottom of PVA stoste preparation still a liquid phase polyvinyl alcohol (PVA) stoste temperature transmitter is installed, the range of this temperature transmitter is determined according to the variation range of temperature of charge;
3) record gaseous pressure in the PVA stoste preparation still by above-mentioned pressure unit, temperature transmitter records PVA stoste boiling temperature, above two signals are inserted Distributed Control System (DCS) or intelligence instrument, can try to achieve the concentration (con) of PVA stoste according to following operational model:
con=c1*T+c2*P+c3
Wherein, the T in the formula is the temperature of PVA stoste in the PVA stoste preparation still; P is the gaseous pressure in the PVA stoste preparation still.
C1, c2, c3 are several important parameters, their meaning and act on as follows: c1: under the situation of other condition constant (being meant that mainly gaseous pressure is constant), PVA stoste boiling temperature changes the pairing concentration change value of unit, c1 be generally on the occasion of; C2: under the situation of other condition constant (mainly being that the stoste boiling temperature is constant), pressure changes the pairing concentration change value of unit, and c2 is generally negative value; C3: instrument is regulated, correction factor, and its effect is to make the adjustment of measuring system convenient and easy, and concerning certain concrete measuring system, it is unique adjusting parameter.
It is 0.075 grade pressure unit that the present invention adopts precision, and its range is 0.15MPa.
Selected range of the present invention is 90 ℃ to 125 ℃ a temperature transmitter, and its error perhaps directly adopts platinum resistance Pt100 can reach requirement in 0.2 ℃.
In PVA stoste process for preparation, the boiling temperature of PVA stoste and pressure, PVA original liquid concentration have definite corresponding relation, the present invention utilizes high-precision pressure unit that gaseous pressure in the PVA stoste preparation still and liquidus temperature are carried out the on-line continuous detection, according to model formation, at line computation PVA original liquid concentration.
Principle of work of the present invention is: along with the carrying out of stoste process for preparation in the PVA stoste preparation still, the concentration of PVA stoste also changes, thereby therefore the respective change that may cause gaseous pressure and PVA stoste boiling temperature detects gaseous pressure with the high-precision pressure transmitter in step 1; In step 2, PVA stoste boiling temperature is detected with temperature transmitter; Take all factors into consideration of the influence of above-mentioned signal, in step 4, utilize Model Calculation just can obtain the concentration of PVA stoste measurement result.
The invention has the beneficial effects as follows: 1, system utilizes the relationship model between PVA original liquid concentration and measured signal, is easy to realize.2, adopt conventional instrument, stable and reliable for performance, the response time fast (retardation time is little).3, price is low, and is easy to maintenance, long service life.4, measuring system of the present invention has higher precision, and typical absolute error value can satisfy technological requirement in ± 0.2%.
Embodiment
Provide embodiment in conjunction with content of the present invention:
Top at PVA stoste preparation still is provided with a gaseous pressure measuring point, the gaseous pressure measuring point is on the liquid level of PVA stoste, the range of pressure unit is 0.15MPa, middle part at PVA stoste preparation still is provided with one of PVA stoste temperature point, and PVA stoste temperature point is under the liquid level of PVA stoste.
Technological parameter and other parameter are: the variation range of PVA original liquid concentration is 12% to 19%; The temperature of charge variation range is 100 ℃ to 115 ℃; Pressure range is that 0.02MPa is to 0.09MPa.
Two signals of pressure and temperature that pressure unit, PVA stoste Temperature Detector record are sent into the DCS Distributed Control System (DCS), can obtain the concentration (con) of PVA stoste by following model calculation:
con=0.07*T-16.66*P+6.31
T is a PVA stoste boiling temperature in the formula, and 0.07 is PVA stoste boiling temperature when once changing, the concentration change value (0.07%) that it is corresponding; P is the pressure signal (gauge pressure) that pressure unit records, and-16.66 when changing a MPa for pressure, the concentration change value that it is corresponding; 6.31 be the adjusting parameter value of this system through gained after the adjustment.
The result that puts into operation of system's two-and-a-half years of the embodiment of the invention shows, the PVA original liquid concentration Error Absolute Value that is recorded by the present invention can satisfy the requirement of technology in ± 0.2%.
Claims (3)
1, a kind of on-line continuous detection method of mother liquid of polyvinyl alcohol is characterized in that step is as follows:
1) on the top of polyvinyl alcohol (PVA) stoste preparation still a gaseous pressure measuring point is set, at this place's setting pressure transmitter, the range of this transmitter determines that according to the maximum pressure in the polyvinyl alcohol (PVA) stoste preparation still described pressure unit is on the stoste liquid level;
2) in the bottom of polyvinyl alcohol (PVA) stoste preparation still a liquid phase polyvinyl alcohol (PVA) stoste temperature transmitter is installed, the range of this temperature transmitter determines that according to the variation range of temperature of charge described temperature transmitter is under the stoste liquid level;
3) record gaseous pressure in the polyvinyl alcohol (PVA) stoste preparation still by above-mentioned pressure unit, temperature transmitter records polyvinyl alcohol (PVA) stoste boiling temperature, above two signals are inserted Distributed Control System (DCS) or intelligence instrument, promptly try to achieve the concentration c on of polyvinyl alcohol (PVA) stoste according to following operational model:
con=c1*T+c2*P+c3
Wherein, T in the formula is the gaseous pressure in the polyvinyl alcohol (PVA) stoste preparation still, c1: under the certain situation of gaseous pressure for polyvinyl alcohol (PVA) stoste boiling temperature in the polyvinyl alcohol (PVA) stoste preparation still, P, polyvinyl alcohol (PVA) stoste boiling temperature changes the pairing concentration change value of unit, c1 be on the occasion of; C2: under the certain situation of stoste boiling temperature, pressure changes the pairing concentration change value of unit, and c2 is a negative value; C3: instrument is regulated, correction factor.
2, the on-line continuous detection method of mother liquid of polyvinyl alcohol according to claim 1 is characterized in that, the employing precision is 0.075 grade a pressure unit, and its range is 0.15MPa.
3, the on-line continuous detection method of mother liquid of polyvinyl alcohol according to claim 1 is characterized in that, selected range is 90 ℃ to 125 ℃ a temperature transmitter, and its error perhaps directly adopts platinum resistance Pt100 in 0.2 ℃.
Priority Applications (1)
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CNB2005100273391A CN100554957C (en) | 2005-06-30 | 2005-06-30 | The on-line continuous detection method of mother liquid of polyvinyl alcohol |
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CNB2005100273391A CN100554957C (en) | 2005-06-30 | 2005-06-30 | The on-line continuous detection method of mother liquid of polyvinyl alcohol |
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CN1712959A CN1712959A (en) | 2005-12-28 |
CN100554957C true CN100554957C (en) | 2009-10-28 |
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CN103674894A (en) * | 2013-12-30 | 2014-03-26 | 安徽皖维集团有限责任公司 | Method for detecting concentration of polyvinyl alcohol solution in production of polyvinyl-alcohol optical film by utilizing refractometer |
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