FR2604786A1 - METHOD FOR QUICK DETERMINATION OF THE COMPOSITION OF TERNARY SOLUTIONS - Google Patents

Abstract

THE PRESENT INVENTION CONCERNS A PROCESS FOR RAPID DETERMINATION OF THE COMPOSITION OF TERNARY SOLUTIONS INCLUDING THE CONTINUOUS MEASUREMENT OF THE REFRACTION INDEX N AND OF THE DENSITY D OF A SOLUTION CONSTITUTED OF THREE CONSTITUENTS, AND THE CALCULATION OF THE WEIGHT FRACTIONS X, X AND X RESPECTIVE CONSTITUENTS, ACCORDING TO THE FORMULAS DEFINED PREVIOUSLY. BY USING A COMPUTER TO CALCULATE WEIGHT FRACTIONS AND SENDING ELECTRONIC CONTROL SIGNALS TO THE RAW MATERIALS FEEDING SYSTEM, IT BECOMES POSSIBLE TO AUTOMATICALLY CONTROL THE FEEDING OF A TERNARY SYSTEM IN A MIXING SYSTEM OR A CONTINUOUS SOLUTION. CONTINUOUS REACTIONAL SYSTEM.

Description

METHOD FOR QUICK DETERMINATION OF THE COMPOSITION OF

TERNARY SOLUTIONS

  The present invention relates to a method for determining

  tion of the composition of solutions, which is useful, by

  example, in the reactions of solutions with three consti-

killing or ternary.

  In cases where a three-component or ternary solution (hereinafter referred to as "ternary solution")

  must be loaded into a mixing system or into a system

  reaction, it is necessary to control the composition

  tion of the ternary solution without delay. Analysis of the

  composition of a gas chromatography required

  site, for example, several hours of calculation. However, the mixing operation or the reaction takes place during the calculation period, so that such an analysis is not used to

  nothing for the control of the composition or the concentration

tion.

  In mixing systems or reaction systems-

  nels conventional, it is usual, in the case of a batch process, to calculate the composition in question from the quantities of the charged constituents. In the case of a continuous process, the process used to determine the composition is generally implemented, which includes the calculation of the latter from the quantity loaded with each material.

  first. However, flow meter errors and / or errors

  human operative laughter is inevitable, which makes the

  composition or concentration difficult to control.

  In fact, it is common to carry out meteorological operations.

  mixture or reaction despite an inadequate feed ratio of raw materials deviating from a defined ratio, without noticing the difference in the composition of the solution by

  in relation to a defined composition.

  An object of the present invention is therefore to provide

  a process for quickly and precisely determining-

  ment the composition of such a ternary solution.

  The present invention has been carried out taking into account that, when a linear additivity is generally recognizable in the refractive index of a ternary solution and that a sufficiently approximate linear additivity is also recognizable in the density of the ternary solution, the following equations (I) and (II) are valid for the solution: nD = al.Xl + bl.X2 + cl-X3 .......... Equation (I) d = a2. Xl + b2.X2 + c2.X3 .......... Equation (II) 1 = Xl + X2 + X3 .......... Equation (III)

  in which nD is the refractive index of the solu-

  tion, d is the density of the solution, al, b1 and c1 are parameters for the refractive indices of the respective constituents, a2, b2 and c2 are parameters for the densities of the respective constituents, XI is the weight fraction of the first constituent , X2 is the weight fraction of the second constituent, and

  X3 is the weight fraction of the third constituent.

  Equation (III) is valid on the basis of equilibrium

masses.

  Like all equations (I), (II) and (III) above

  are linear algebraic equations, the solutions can-

  wind is easily obtained and expressed in terms of the following formulas (IV), (V) and (VI): nD b1 cl d b2 C2

1 1 1

  X = Foimule (IV) al bl ci a b2 c2 i 1 i al nD c1 a2 d C2 1 1 X2 = - X2 = Formula (V) al bl Cl a2 b2 C2

1 1 1

al bl nD a2 b2 d

1 1 1

  X3 = alblc ai b1 Cl Formula (VI) 2b2 C2

1 1 1

  Consequently, when the values are first obtained

  their of al, b1, cl, a2, b2 and c2, in formulas (IV), (V) and (VI), by the method of least squares or all

  other suitable method using experimental results

  rate, we can know instantly and very easily the composition of the ternary system expressed by X1, X2 and X3 in

  determining the values of nD and d by means of a refraction

  tometer and a density meter and substituting them for nD and d in formulas (IV), (V) and (VI) to calculate X1, X2 and

  X3 using a calculation system.

  Figure la and figure lb are histograms

  presenting the conformity between the values actually measured

  rees and the calculated values, respectively for density and refractive index, in a mode

  of the present invention.

  FIG. 2 is a graph showing the conformity between the values actually measured and the values calculated, for this mistletoe, of the weight fraction of polymerization solutions in the embodiment of the present invention.

  FIG. 3 is a histogram representing the conformity

  between the values actually measured and the values

  calculated with respect to the weight fraction of the solu-

  tions in the embodiment of the present invention.

  Figure 4 is a block diagram showing an example of the composition measurement system to be used

in the present invention.

  The present invention has thus made it possible to control

  ler or quickly adjust the composition of a ternary solution by measuring the refractive index and the

  density of the solution, which can be performed instantly

  and by calculating the weight fractions of the constituents

  solution kills based on formulas (IV), (V) and

  (VI) mentioned above using a computer or ana-

  log. As a result, it has now become possible to

  automatically control the power of a ter-

  nary (ternary solution), whose weight fraction has been

  difficult to control, in a solu- mixing system

  tion or in a continuous reaction system, of a

  so that each raw material is loaded automatically

  matically in the mixer or in the reactor, according to a desired ratio, by measuring the refractive index and the

  density of the ternary solution to be loaded, using a

  a fractometer and a hydrometer which are integrated into the raw material supply system, possibly using a thermometer integrated into the system to correct, depending on the temperature, the index of

  refraction and density; conversion of the re-index

  measured fraction and density, solution, frac-

  weighting of the respective constituents (possibly with correction as a function of temperature) using a computer connected to the measurement system; then sending electrical control signals to the raw material supply system. The parameters a1, b1 and cl, and the parameters a2, b2 and c2, are eigenvalues fixed when the types of the three constituents and their combination are given at a constant temperature. It is obvious that the eigenvalues of the parameters vary when the

  type of constituents, or the temperature of the measurement (tem-

  temperature at which the refractive index is measured and

density) varies.

  The values of these parameters are constants which are obtained by measuring, at a certain temperature,

  the refractive index and the density of a ter-

  nary given, while varying the ratio between the

  constituents, and by calculation, from the measured values

  rees, using the least squares method, and ana-

  logues. Although the parameters al, b1 and cl, as well as a2, b2

  and c2, may vary, of course, depending on the consti-

  killing of the solution and / or the temperature at which the refractive index and density are measured, it has been confirmed that each parameter can be easily defined at

  advance by experience and that the process according to the pre-

  This invention can be applied to various solutions with a ternary system. For example, it has been confirmed that the

  weight fraction of each constituent of a ter-

  nary consisting of sodium acrylate, acrylamide and water, polymerization solution which constitutes a typical example in the production of anionic or nonionic flocculants,

  and a ternary system consisting of methacryl chloride

  oyloxyethyl-trimethylammonium, acrylamide and water, solu-

  tion of polymerization which constitutes a typical example in the production of cationic flocculants, can be known by the process of the present invention with satisfactory precision, that is to say with a standard deviation of uncertainty not exceeding not 1.4% in terms of percentage of the concentration. The standard deviation of the uncertainty (as a percentage of the concentration) is defined by the formula: Standard deviation of the uncertainty (a) = (measured value - calculated value) 2 (% N - 1

where N is the number of samples.

  An example of the measuring device or system required

  to analyze the composition of ter-

  is shown in Figure 4.

  This system includes a refractometer, a hydrometer,

  an interface and a computer, and measures the index of

  fraction and density or conductivity of the mass

  mique to indicate the composition (in terms of Xl, X2 and X3) of the ternary solution in question, according to the formulas

  operational (IV), (V) and (VI) programmed in advance.

  The refractive index detector 1 and the density or density detector 2 are connected in series with each other by means of a sampling pipe. The solution of the ternary mixture, after

  having passed through the refractive index detector 1,

  pours the density or density detector 2. The refractive index detector i gives on this occasion a linear signal of power in direct current of 4-20 mA, indicative of the refractive index, and transmits the signal to

interface 4.

  The signal from the detector. density or density 2 is converted into a DC signal of

  4-20 mA by means of a converter 3 and transmitted to the inter-

  side 4. The interface 4 is constructed so as to convert the input signals into GP-IB (general purpose interface bus) signals and therefore it converts the electric current signals coming from the refractive index detector 1 and converter 3 to GP-IB signals so that the

  signaling of the computer can be done without

  blows. The computer system 5 comprises a device for

  storage or memory, printer, screen, and the like.

  The computer, in which the formulas were introduced

  XtC (IV), (V) and (VI) used to calculate the weighted fractions

  them from the refractive index and the density of

  the solution in ternary mixture, processes the signals indi-

  refractive index and density (or

  density) of the solution of the circulating ternary mixture

  continuously in the sampling line. We can thus know in real time the composition of the solution of the ternary mixture. In addition, it is possible to

  output external control signals from the interface

  nes, indicated by a to d in FIG. 4, so that

  see control in real time of external valves and ana-

logues.

Examples

  The refractive index (nD) and the den-

  site (d) respectively of a number of solutions in

  ternary system composed of methacryloyloxy chloride-

  ethyl-trimethylammonium (DMC), acrylamide (AAm) and water, using an Abbe refractometer and an aerometer according to JIS standards, respectively. The results thus obtained

are shown in Table 1.

  We replace the variables X1, X2, X3, nD and d, in equations (I) and (II) indicated above, by the results indicated in table i and we determine the parameters al, bl, cl, a2, b2 and c2 by the method of least squares. The

  results thus obtained are shown in Table 2.

TABLE 1

  Weight fraction Refractive index Density No DMC Xl AAm X2 H20 X3 (nD) (d)

1 0.0 0.1053 0.8947 1.3505 1.0110

2 0.0 0.2959 0.7041 1.3817 1.0280

3 0.0 0.5000 0.5000 1.4153 1.0430

4 0.0 0.0 1.0000 1.3335 0.9982

0.3890 0.0 0.6110 1.3978 1.0520

6 0.0 0.2490 0.7510 193,740 1.0230

  7 0.1990 0.1220 0.6790 1.3857 1.0370

  8 0.3930 0.2480 0.3590 1.4415 1.0740

  9 0.5910 0.0400 0.3690 1.4410 1.0850

0.4910 0.0610 0.4480 1.4260 1.0720

  11 0.2460 0.2800 0.4740 1.4200 1.0570

  12 0.1230 0.3900 0.4870 1.4178 1.0500

  13 00 410 0.1300 0.8290 1.3610 1.0 160

  14 0X0400 0.1280 0.8320 1.3605 1.0160

0.2010 0.2485 0.5505 1.4073 1.0500

  16 0.3460 0.0630 0.5910 1.4005 1.0520

  17 0.2120 0.1864 0.6017 1.3982 1.0460

  18 0.1460 0.2060 0.6470 1.3903 1.0380

  19 0.3130 0.1380 0.5490 1.4076 1.0550

0.2040 0.0 0.7960 1.3663 1.0260

21 0.5000 0.0 0.5000 1.4183 1.0690

22 0.7800 0.0 0.2200 1.4716 1.1090

23 0.0 0.1050 0.8950 1X3505 1.0110

24 0.0 0.2960 0.7040 1.3817 1.0380

0.0 0.5000 0.5000 1.4153 1.0430

26 0.0 0.5000 0.5000 1.4152 1.0450

27 0.0 0.3695 0.6305 1.3940 1.0340

28 0.0 0.2747 0.7253 1.3776 1> 0320

29 0.0 0.2010 0.7990 1.3661 1.0190

0.0 0.1481 0.8519 1.3577 1.04040

31 0.0 0.1074 0.8926 1.3507 1.0110

  TABLE 1 (continued) Weight fraction Refractive index Density No DMC Xl AAm X2 H20 X3 (nD) (d)

32 0.0 0.079 0.9201 1.3459 1.0080

33 0.0 0.0587 0.9413 1.3427 1.0070

34 0.0 0.0436 0.9564 1.3402 1.0060

0.0 0.0275 0X9725 1.3379 1.0050

36 0.7800 0.0 0.22200 1.4762 1.1130

37 0.6138 0.0 0.3862 1.4430 1.0870

38 0.4645 0.0 0.5355 1.4145 1.0660

39 0.3449 0.0 0.6551 1.3927 1.0480

0.2577 0.0 0.7423 1.3770 1.0370

41 0.1915 0.0 0.8085 1.3657 1.0260

42 0.1428 0.0 0.8580 1.3574 1.0190

43 0.1060 0.0 0.8940 1.3516 1.0140

44 0.0781 0.0 0.9219 1.3469 1.0110

0.0570 0.0 0.9430 1.3430 1.0080

46 0.0419 0.0 0.9581 1.3401 1.0070

47 0.0222 0.0 0.9778 1.3373 1.0030

48 0.2985 0.0 0.7015 1.3842 1.0410

49 0t1586 0.0 0.8414 1.3609 1.0200

0.0789 0.0 0.9211 1.3469 1.0110

TABLE 2

  al 1.5085 a2 1.1384 b1 1.4967 b2 1.0888 cl t1.3325 c2 1.0004 According to the results indicated in table 2, the equations for carrying out the estimate can be expressed as follows : nD = 1.5085. X1 + 1.4967.X2 + 1.3325.X3 ... Equation (VII) d = 1.1384.X1 + 1.0888.X2 + 1.0004. X3 ... Equation (VIII)

  To assess the accuracy of equation (VII) relative-

  ment to the index of refraction (nD) and equation (VII) relative to the density (d), we compare the values of nD and d obtained by replacing X1, X2 and X3, on the right side 1It of the equations (VII) and (VIII), by the true fraction

  weight (calculated values of nD and d), with the values

  their of nD and d actually measured, as indicated by

  Table 3. Figures la and lb show histo-

  grams of the results shown in Table 3. From these results, we can consider that equations (VII) and (VIII) are indicative of nD and d, respectively, with

satisfactory accuracy.

TABLE 3

  Refractive index (nD) Density (d)

  Values of nD Real values- Values of d Real values-

  n calculated only measured calculated only measured

  lon the equation minus values according to rees minus va-

  (VII) calculated the equation their calcu-

(VIII)

1 1.350 0.001 1.010 0.001

2 1.381 0.001 1.027 0.001

3 1.415 0.001 1.045 -0.002

4 1.332 0.001 1,000 -0.002

1.401 -0.003 1.054 -0.002

6 1.373 0.001 1.022 0.001

7 1.387 -0.002 1.039 -0.002

8 1.442 -0.001 1.077 -0.003

9 1.443 -0.002 1.085 -0.000

1.429 -0.003 1.074 -0.002

11 1.422 -0.002 1.059 -0.002

12 1,418 -0,000 1,052 -0.002

13 1.361 -0,000 1.018 -0.002

14 1.361 -0,000 1.017 -0.001

1.049 -0.001 1.050 -0.000

16 1.404 -0.003 1.054 -0.002

17 1,400 -0,002 1,046 -0,000

18 1,391 -0,000 1,038 0,000

19 1.410 -0.002 1.056 -0.001

1.368 -0.002 1.029 -0.003

21 1,420 -0.002 1.069 -0,000

22 1.469 0.002 1.108 0.001

23 1.350 0.001 1.010. 0.001

24 1.381 0.001 1.027 0.001

1.415 0.001 1.045 -0.002

26 1.415 0.001 1.045 0.000

27 1.393 0.001 1.033 0.001

28 1.378 0.000 1.025 0.007

  TABLE 3 (continued) Refractive index (rin) Density (d)

  Values of nD Real Values- Values of d Real Values-

  n calculated only measured calculated only measured

  lon the equation minus values according to rees minus va-

  (VII) calculated the equation their calcu-

(VIII)

29 1.365 0.001 1.018 0.001

1.357 0X001 1.014 0.000

31 1,350 0.001 1.010 0.001

32 1.346 0.000 1.007 0.001

33 1.342 0.001 1.006 0.001

34 1.340 0.001 1.004 r0.002

1.337 0.001 1.003 0.002

36 1.469 0.007 1.108 0.005

37 1,440 0.003 - 1.085 0.002

38 1.414 0.000 1.065 0.001

* 39 1,393 -0,000 1,048 -0,000

1.378 -0.001 1.036 0.001

41 1.366 -0,000 1.027 -0.001

42 1.359 -0.001 1.021 -0.002

43 1.351 0.001 1.015 -0.001

44 1.346 0.001 1.011 -0.000

1,342 0.001 1,008 -0,000

46 1.340 0.000 1.006 0.001

47 1.336 0.001 1.003 -0.000

48 1.385 -0.001 1.042 -0.001

49 1.360 0.001 1.022 -0.002

1.346 0.001 1.011 -0.000

  Then, to assess the accuracy of the calculated values

  The values of X1, X2 and X3, we compare the values actually me-

  of X1, X2 and X3 with the values of X1, X2 and X3 ob-

  held by replacing respectively nD, d, al, b1, cl, a2, b2 and c2, in formulas (IV), (V) and (VI) indicated above

  above, by the values of nD and d and the values of the pa-

  rameters above actually measured (cf. equations (VII) and (VIII)). Figure 2 is a graphical representation of

  results of the comparison and Figure 3 is a representation

  a histogram of the same results. This numbers

  indicate that the composition values actually measured

  rees agree well with the values estimated by the cal-

ass.

  In a continuous mixing process for the polymer

  sation of a ternary system made up of DMC, AAm and

  of water, there is a supply solution

  tion prepared by mixing the constituents, a refractometer and a hydrometer (and a thermometer). The refractive index and density data thus measured are entered into a computer, by means of appropriate signal converters, and the weight fractions of the respective constituents are calculated according to equations (III), (VII) and

  (VIII) and the formulas (IV) to (VI) above and they are shown

  che. The supply of raw materials is controlled according to the results thus displayed. It is thus possible to

  synthesize the polymer with good quality and composition

constant sition.

  The method according to the present invention makes it possible to know the composition of a solution instantly and

  with satisfactory precision by simple measurement of the

  dice of refraction and density of the solution, then by computer processing, which allows to always control

  feed raw materials precisely.

  Therefore, even in a continuous polymerization process in which a solution of monomers consisting of three components, difficult to control due to the

  consumption of raw materials, is subject to a poly-

  merit, it is now possible to load the ma-

  raw materials in a polymerization or ana-

  log, under automatic control, according to a quantitative report

  tif necessary and appropriate, by providing the feed section

  tation of the monomer solution belonging to the polymerization apparatus of a refractometer, a hydrometer and a computer, possibly also a thermometer for correction as a function of temperature, by continuously measuring the index of refraction and density of the ternary solution, whereby the computer quickly calculates the weight fractions of the respective constituents and sends the resulting electrical signals to the power system

raw material.

R E V E N D I C AT I ON S

  1.- Method for rapid determination of the composition of

  ternary solutions including continuous measurement of in-

  refractive dice nD and the density d of a solution consisting of three constituents and the calculation of the weight fractions X1, X2 and X3 of the respective constituents, according to formulas (IV), (V) and (VI) indicated below , the

  fractions being considered as indicative of the ratio

  port between the constituents of the solution: nD b1 cl d b2 c2

1 1 1

  X1 = 1 Formula (IV) al nD cl a2 d c2

1 1 1

  X2 = Formula (V) IL al bl nD a2 b2 d 1 i i X3 = Formula (VI) al bl C1 in which / is a2 b2 c2

1 1 1

  nD is the refractive index of the solution, d is the density of the solution, al, b1 and cl are parameters for the refractive indices of the respective constituents, a2, b2 and c2 are the parameters for the densities of the respective constituents , X1 is the weight fraction of the first constituent, X2 is the weight fraction of the second constituent, and

  X3 is the weight fraction of the third constituent.

  2.- Method according to claim 1, characterized in that

  the solution consists of sodium acrylate,

mide and water.

  3.- Method according to claim 1, characterized in that

  the solution consists of methacryloyloxy chloride-

  ethyl-trimethylammonium, acrylamide and water.

  4.- Method according to claim 3, characterized in that, at 20 C, aI is equal to 1.5085, b1 is equal to 1.4967, c1 is equal to 1.3325, a2 is equal to 1.1384, b2 is equal to

1.0888 and c2 is equal to 1.0004.

  5.- Method according to claim 1, characterized in that the calculation is carried out using a computer which are

  connected a refractive index detector and a detector

  density or density.