An On-Line Control and Reaction Process for pH Adjustment

Abstract

An on-line control and reaction process for pH adjustment and a control device for automatically adjusting pH value are provided. The process includes mixing a first enhancer and a second enhancer, optionally after diluting the first enhancer and/or the second enhancer with water, to form a mixture, setting a base pH value (δ1) and a target pH value (δ2), and adding pH adjuster into the mixture via a pH control unit and mixing to obtain a product with the target pH value. The pH control unit adjusts the adding of the pH adjuster by measuring or inputting certain parameters.

Claims

1. An on-line control and reaction process for pH adjustment of a binary enhancer composition comprising a first enhancer and a second enhancer, the process comprising: mixing the first enhancer and the second enhancer, optionally after diluting the first enhancer and/or the second enhancer with water, to form a mixture, 2) setting a base pH value (δ1) and a target pH value (δ2), 3) adding pH adjuster into the mixture via a pH control unit and mixing to obtain a product with the target pH value; wherein the pH control unit adjusts the adding of the pH adjuster by measuring or inputting the following parameters: a. the solid content ratio of the first enhancer in relation to the mixed product (r), said mixed product comprising the first enhancer and the second enhancer, b. the solid content of the first enhancer (α) and the solid content of the second enhancer (β), c. the pH value of the first enhancer (a) and the pH value of the second enhancer (b), d. the base pH value (δ1) and the target pH value (δ2) as provided in step 2), e. the flux of the product.

2. The process of claim 1, wherein the pH control unit adjusts the flux of the pH adjuster via at least the related parameter, K1, K2, K3 and K4 and utilizing the following formula (1):
flux of pH adjuster=X×(K1−K2+K3+K4)  (1), wherein X represents the flux of the product (X); K1 represents the amount of pH adjuster consumed with pH value increasing from the initial pH value to the base pH value (δ1) under varying solid content ratios of the first enhancer or second enhancer in relation to the mixed product (r), and satisfies K1=k.sub.1×r+t, wherein k.sub.1 is the slope obtained by linear fitting and t is the intercept; K2 represents the amount of pH adjuster consumed in relation to different pH values of the first enhancer (a) and different pH values of the second enhancer (b) under varying solid content ratios of the first enhancer or second enhancer in relation to the mixed product (r), and satisfies K2=2×r×k.sub.2×Δ.sub.pH1+2×(1−r)×k.sub.2′*Δ.sub.pH2, wherein k.sub.2 and k.sub.2′ represents slope or average slope obtained by linear fitting in plotting the amounts of pH adjuster consumed with pH value increasing from the respective low limit pH value, high limit pH value and average pH value of two enhancers, in which said low limit pH value and high limit pH value are respectively the nominal lowest and highest pH value of the enhancer sample, and Δ.sub.pH1 and Δ.sub.pH2 represent the difference between the inherent pH value of first enhancer, respectively second enhancer ((a) or (b)), and the average pH value of first enhancer, respectively second enhancer ((a.sub.ave.) or (b.sub.ave.)), in which each of said average pH value ((a.sub.ave.) or (b.sub.ave.)) is an average determined from the pH values of n samples of the first or second enhancer and n is ≧50; K3 represents the effect of the difference between the target reaction index (δ2) and base pH value (δ1) on the amount of pH adjuster on the basis of K2, and satisfies K3=(2×r×k.sub.2+2×(1−r)×k.sub.2′)×(δ2−δ1); K4 represents the effect of varying solid content (α) and solid content (β) on the amount of pH adjuster under base pH value (δ1), and satisfies K4=k.sub.4×(r×α/(1−r)×β)−C.sub.1, wherein k.sub.4 represents slope obtained by linear fitting in plotting the amounts of pH adjuster consumed when the pH value is adjusted up to base pH value (δ1) against different solid content ratios of first enhancer to second enhancer, C.sub.1 is a value calculated from the formula r.sub.0*α.sub.theo./((1−r.sub.0)*β.sub.theo.) in case of the theoretical solid content of first enhancer (α.sub.theo.) and the theoretical solid content of second enhancer)(β.sub.theo.), in which r.sub.0 is a standard ratio of first enhancer to the mixed product and is set to 1/2.

3. The process of claim 1, wherein the first enhancer is a polyacrylamide enhancer and the second enhancer is a dialdehyde modified polyacrylamide enhancer.

4. The process of claim 1, wherein the solid content of the first or second enhancer (α or β) is from 5 to 100%.

5. The process of claim 1, wherein the pH value of the first or second enhancer (a or b) is from 2 to 8.

6. The process of claim 1, wherein δ2 is 7.5 to 11.

7. The process of claim 1, wherein the first enhancer is a polyacrylamide enhancer.

8. The process of claim 7, wherein the polyacrylamide enhancer has a weight average molecular weight of from 500,000 to 5,000,000 g/mol.

9. The process of claim 3, wherein the dialdehyde modified polyacrylamide enhancer has a weight average molecular weight of from 200,000 to 2,000,000 g/mol.

10. The process of claim 1, wherein parameter K5 is introduced to calibrate the actual concentration of pH adjuster,
K5=C.sub.nominal/C.sub.2, in which C.sub.nominal is a nominal concentration of the product and C.sub.2 is an actual concentration as measured of the product.

11. The process of claim 10, wherein the flux of the pH adjuster=X×(K1−K2+K3+K4)×K5.

12-14. (canceled)

15. A method of blending a binary enhancer comprising polyacrylamide and dialdehyde-modified polyacrylamide, the method comprising: combining a stream of the polyacrylamide and a stream of the dialdehyde-modified polyacrylamide and optionally water to form a mixture having an initial pH; dosing pH adjuster into the mixture to adjust the pH of the mixture to greater than 7 to form the binary enhancer.

16. The method of claim 15, wherein the stream of the polyacrylamide is diluted with water prior to being combined with the stream of the dialdehyde-modified polyacrylamide.

17. The method of claim 15, wherein the stream of the dialdehyde-modified polyacrylamide is diluted with water prior to being combined with the stream of the polyacrylamide.

18. The method of claim 15, wherein the pH adjuster is metered into the mixture via a static mixer.

19. A system for forming a binary enhancer, the system comprising: pipelines configured to combine a stream of polyacrylamide and a stream of dialdehyde-modified polyacrylamide to form a mixture; a pH control unit configured to dose pH adjuster into the mixture to adjust the pH of the mixture to greater than 7.

20. The system of claim 19, further comprising at least one static mixer configured to dilute at least one of the stream of polyacrylamide and the stream of dialdehyde-modified polyacrylamide.

21. The system of claim 19, further comprising a static mixer configured to dose the pH adjuster into the mixture.

Description

ILLUSTRATIONS TO THE DRAWINGS

[0056] FIG. 1 schematically shows an on-line automatic control device for pH adjustment in accordance with the process of the present disclosure. According to FIG. 1, a binary enhancer is provided at first which comprises dialdehyde-modified polyacrylamide GPAM1 and polyacrylamide PAM2. Meanwhile, the solid contents α and β of both compounds are measured and also the respective inherent pH values, e.g., 3 to 4, as the parameters a and b, respectively. Herein, optionally, GPAM 1 and PAM 2 are introduced separately via pipelines into a diluting unit 3 comprising a mixer such as a static mixer, so as to be mixed with water. The dilution step may be carried out as required and depend on the source and viscosity of these two enhancers GPAM 1 and PAM 2. Subsequently, after mixing these two enhancers, the base pH value ⊕1 4 is set to e.g. pH=8 and compared with the target pH value δ2, i.e., the target reaction index 6 (e.g., the pH=9). Then the ideal indication for the amount (or flux) of the pH adjuster can be obtained from the pH control unit 5, according to which a suitable dosage of the pH adjuster 7 (e.g., the aqueous NaOH solution) is added to the mixture of GPAM 1 and PAM 2. The mixture is mixed in the mixer 8 for a sufficient period, thereby obtaining the final output product PM which satisfies the target pH value. In the pH control unit, the parameter X, i.e., the flux of the final product PM can be determined according to the on-site output.

[0057] Said pH control unit 5 may be operated manually or automatically, preferably automatically. In one embodiment of the present disclosure as shown in FIG. 7, which is just illustrative and depicts the structure essential for understanding the present invention, the pH control unit 5 is an automatic control device comprising at least input port A, output port B and calculation center C, in which input port A receives the signals corresponding to the following parameters and input them into the calculation center C: the solid content ratio of the first enhancer in relation to the mixed product (r), the solid content of the first enhancer (α) and the solid content of the second enhancer (β),

[0058] the pH value of the first enhancer (a) and the pH value of the second enhancer (b),

[0059] the base pH value (δ1) as set,

[0060] the target pH value, i.e. target reaction index (δ2),

[0061] the flux of the final output product (X) and

[0062] optionally actual concentration of pH adjuster as measured (C.sub.2);

[0063] and then calculation center C transmits into output port B the flux of pH adjuster as calculated according to the process as described above, especially according to formula (1), said output port B adapting the pH adjuster flux to the calculated flux of pH adjuster via pipeline and flux control apparatus.

[0064] In the calculation center C (e.g., a calculator), the above formula (1) and parameters in relation to K1-K4 and optional K5 like k.sub.1, t, k.sub.2, k.sub.2′, a.sub.ave., b.sub.ave., k.sub.4, C.sub.1 and optional C.sub.nominal are set and fixed in advance. Said calculation center C may transmit the calculated flux value of the pH adjuster via electrical signal to the output port B and control the port B to adjust the flux of the pH adjuster.

[0065] The process and the on-line automatic control device according to the present invention are in particular suitable for use in papermaking, water treatment, mining and petroleum industries.

[0066] FIG. 2 is a schematic diagram for K1 calculation in the examples.

[0067] FIGS. 3 to 5 are schematic diagrams for K2 calculation in the examples.

[0068] FIG. 6 is a schematic diagram for K4 calculation in the examples.

[0069] FIG. 7 is the schematic diagram for the automatic control device for the pH adjusting unit.

REFERENCE SIGNS LIST

[0070] 1 dialdehyde-modified polyacrylamide GPAM [0071] 2 polyacrylamide PAM [0072] 3 diluting unit [0073] 4 setting base pH value [0074] 5 pH control unit [0075] 6 setting target pH value, target reaction index [0076] 7 pH adjuster, aqueous NaOH solution [0077] 8 mixer [0078] PM final output product

[0079] The arrow represents the flowing direction of the stream (FIG. 1) or the transmitting direction of data (FIG. 7).

EXAMPLES

[0080] The invention is described in more detail by referring to the following Examples, but is not limited to these Examples.

1. Calculation Examples for the Flux of pH Adjuster

(1) Reagents as Used

[0081] TX 15241: dialdehyde-modified DADMAC/polyacrylamide (GPAM) having the solid content of 9-12% in general, the pH of 2.36 to 3.46 and the viscosity at 25° C. of 16-28 cps, available from Ecolab Company

TX 15951: polyacrylamide (PAM) having the solid content of 19.5-22% in general, the pH of 2.5-3.49 and the viscosity at 25° C. of 4000 to 10000 cps, available from Ecolab Company
TX 16389: 48% NaOH having the solid content of 46-50% in general, available from Ecolab Company

(2) Calculations of the Parameters K1 to K5

[0082] It is well understood for a person skilled in the art that the following calculation examples are just illustrative and can be conducted by programming of the computers or other auxiliary devices.

Calculation of K1

[0083] The base pH value δ1 was set at 8. The amount of pH adjuster consumed with pH value increasing from the initial pH value of the product to the base pH value 8 under varying solid content ratios (r) of the polyacrylamide TX 15951 in the mixed product was measured.

[0084] During this procedure, r value was varied with other parameters to be fixed. TX 15951 and TX 15241 were formulated into 1 kg of the respective mixed products with different ratios, and each of the compositions of TX 15921 and TX 15241 with different ratios were titrated with pH adjuster TX 16389 solution one by one. The respective amounts of TX 16389 consumed for adjusting the pH value from the initial pH value to the base pH value of 8 were recorded in Table 1. Plotting the corresponding curve according to the values as shown in Table 1, and linear fitting to obtain FIG. 2 and the formula of K1:

K1=(4.9754×r+3.5422).

TABLE-US-00001 TABLE 1 Effects of varying r values on the amount of TX 16389 r Amount of TX 16389, ml 0.33 5.2317 0.497 5.8678 0.53 6.2444 0.5515 6.3424

Calculation of K2

[0085] In this batch, the nominal low limit pH value of TX 15951 was 2.5 and the nominal high limit pH value was 3.49. The average pH value as measured from 80 samples was 3.38. The nominal low limit pH value of TX 15241 was 2.36 and the nominal high limit pH value was 3.46. The average pH value as measured from 80 samples was 2.91. Then, TX 15951 and TX15241 were formulated into a mixed product according to the ratio r of TX 15951 in the mixed product of 0.5.

[0086] In the experiment, the amounts of TX 16389 consumed by titration with pH value gradually increasing from the respective low limit pH value, high limit pH value and average pH value of TX 15241 and TX 15951 to different pH values were studied and recorded in Tables 2 and 3. Plotting FIGS. 3, 4, and 5 according to the measured data in Tables 2 and 3, and calculating the average slope values k.sub.2 and k.sub.2′ of the linear curves of TX 15241 and TX 15951.

TABLE-US-00002 TABLE 2 TX 15241 Low limit pH value Average pH value High limit pH value Amount of TX Amount of TX Amount of TX pH 16389 pH 16389 pH 16389 7.48 2.0783 8.09 1.715 7.73 1.07 8.38 2.31 8.76 1.872 8.45 1.275 9.31 2.49 9.21 2.027 9.14 1.652 9.48 2.53 9.29 2.067 9.43 1.7767 9.56 2.66 9.62 2.228 9.55 1.9967 9.92 2.408

TABLE-US-00003 TABLE 3 TX 15951 Low limit pH value Average pH value High limit pH value Amount of TX Amount of TX Amount of TX pH 16389 pH 16389 pH 16389 7.85 4.79 8.51 5.34 7.96 3.331 8.26 5.59 8.83 6.055 8.43 4.35 8.74 6.66 9.17 6.78 8.88 5.325 9.22 7.74 9.46 7.34 9.19 6.01 9.63 8.55 9.79 7.94 9.68 7.09

[0087] As shown in FIGS. 3-5, the relations of respective pH value changes as calculated by the linear fitting under the low limit pH value, the average pH value and the high limit pH value of TX 15951 with the amount of TX 16389 were respectively shown as follows, wherein Y.sub.1, Y.sub.1′, Y.sub.1″ and X.sub.1, X.sub.1′, X.sub.1″ corresponded to the Y-coordinate and the X-coordinate, respectively:

Y.sub.1=2.1391X.sub.1−12.032  (FIG. 3),

Y.sub.1′=2.0506X.sub.1′−12.082  (FIG. 4),

Y.sub.1″=2.1847X.sub.1″−14.064  (FIG. 5), and

the average value of slope k.sub.2 is 2.1248.

[0088] The relations of respective pH value changes as calculated by the linear fitting under the low limit pH value, the average pH value and the high limit pH value of TX 15241 with the amount of TX 16389 were respectively shown as follows, wherein Y.sub.2, Y.sub.2′, Y.sub.2″ and X.sub.2, X.sub.2′, X.sub.2″ corresponded to the Y-coordinate and the X-coordinate, respectively:

Y.sub.2=0.2492X.sub.2+0.213  (FIG. 3),

Y.sub.2′=0.4637X.sub.2′−2.2195  (FIG. 4),

Y.sub.2″=0.4823X.sub.2″−2.719  (FIG. 5), and

the average value of slope k.sub.2 was 0.3984.

[0089] Meanwhile, taking into consideration the effect of the deviation of ratio r from base 0.5, the coefficient (r/0.5) was multiplied, i.e., 2×r.

[0090] Thereby, the formula was obtained:

K2=2×r×2.1248×(a−3.38)+2×(1−r)×0.3984×(b−2.91).

Calculation of K3

[0091] After calculating the parameter K2 as above described, the following formula could be easily obtained:

K3=(2×r×2.1248+2×(1−r)×0.3984)×(δ2−8).

Calculation of K4

[0092] TX 15951 and TX 15241 were formulated according to the solid content ratios as recited in the left column of Table 4 into some 1 kg mixed products with different ratios, and the pH adjuster TX 16389 was used to adjust individual mixed products into the base pH of 8. The amount of the consumed TX 16389 was recorded as the data shown in the right column of Table 4. FIG. 6 was plotted according to all data in Table 4.

[0093] In addition, according to the formulation, the theoretical solid content α.sub.theo. of TX 15951 could be obtained as 20% and the theoretical solid content β.sub.theo. of TX 15241 as 10%. Considering the deviation of the actual solid content of the product from the standard value, the standard value r.sub.0 of the ratio of TX 15951 in the mixed product was set to be 1/2, and the value of C.sub.1 was obtained as 2 according to the formula r.sub.0*α.sub.theo./((1−r.sub.0)*β.sub.theo.. Furthermore, by combining the slope 1.5408 obtained from FIG. 6, K4 could be obtained as follows:

K4=1.5408×(r×α/((1−r)×β)−2)

TABLE-US-00004 TABLE 4 TX 15951: TX 15241 TX 16389 amount, ml 1.23 5.2317 1.13 5.8678 0.99 6.2444 0.55 6.3424

Calculation of K5

[0094] Since the nominal concentration of pH adjuster TX 16389 was 48%, the parameter K5 for rectifying the amount of pH adjuster TX 16389 was 48%/C.sub.2.

[0095] Substituting K1 to K5 as calculated above into the formula (1), the formula (2) about the amount of pH adjuster could be obtained as follows:

Amount of pH adjuster=X×((4.9754×r+3.5422)−(2×r×2.1248×(a−3.38)+2×(1−r)×0.3984×(b−2.91)+(2×r×2.1248+2×(1−r)×0.3984)×(δ2−8)+1.5408×(r×α/((1−r)×β)−2))×(48%/C.sub.2).

2. Application Example

[0096] In the automatic control device as shown in FIG. 7, comprising at least port A, output port B and calculation center C, the above-described formula (2) was programmed and fixed in the calculator of the calculation center C.

[0097] Then, the binary enhancer consisting of TX 15241 and TX 15951 and TX 16389 with the concentration of 48% were fed into the on-line control and reaction device for pH adjustment as shown in FIG. 1. The solid contents (α, β), pH values (a, b), the solid content ratio (r) of polyacrylamide in the mixed product, flux of the final output product (X) and target pH value (δ2) were measured beforehand. Following this, these parameters were input into the output port A and then a suitable amount of pH adjuster could be achieved through the calculation in the calculator of the calculation center C and by adjusting the valve of output port B. Individual parameters and the amount of pH adjuster were shown in Table 5.

TABLE-US-00005 TABLE 5 Individual input parameters of the binary enhancer and the amount of pH adjuster Ratio of TX 15951 in Solid flux of the the Solid content pH final Amount Target mixed content of of TX value of pH value output of pH pH product TX 15951 15241 TX of TX product adjuster value (%) r (%) α (%) β 15951 a 15241 b (ml/min) X (ml/min) δ2 0.5 20 10 2.5 3 1.6 15.78 8.80

[0098] After such an adjustment, the obtained target pH value of the resulting final output product solution was 8.80, and the actual value as measured was 8.85.