JPS6411360B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for preventing water scaling in boilers and industrial cooling equipment. [Prior Art and Problems to be Solved by the Invention] Some types of boiler water and many industrial waters, such as water used in the operation of cooling towers, are treated with various inorganic and organic phosphorus-containing compounds. be done. Such treatments tend to produce calcium phosphate scale that adheres to the metal surfaces of boilers and metal heat exchangers. Known organic scale inhibitors and scale dispersants, both inorganic and those containing water-soluble polymers, are effective against a wide range of scales, but are not completely effective against calcium phosphate scale. Not that there is. Pure calcium phosphate scale may exist by itself, but is often found as a contaminant of calcium carbonate and calcium or magnesium salt scales. If such scale contains at least 10% calcium phosphate, it is suitable for treatment with the scale inhibitors of the present invention as disclosed below. [Means and Effects for Solving the Problems] A method for preventing scaling generally, and specifically and preferably suppressing calcium phosphate scaling within boilers and industrial cooling equipment, includes of water with several ppm of terpolymer having acryloylmorpholine as the first monomer unit. The second monomer unit is
It is a vinyl monomer containing carboxylate. Examples of comonomers are acrylic acid, methacrylic acid, maleic acid, crotonic acid, isocrotonic acid,
and itaconic acid. The third monomer unit is
Any vinyl monomer can be used as long as the resulting terpolymer is water soluble. Examples of third monomer units are methacrylic acid, maleic acid, itaconic acid, vinyl acetate, vinylsulfonic acid, AMPS, acrylamide, N-alkanol acrylamide, N-alkylacrylamide, methacrylamide, N-alkylmethacrylamide, acrylic acid Methyl, ethyl acrylate,
These are propyl acrylate, 2-hydroxyethyl acrylate, and 2-hydroxypropyl acrylate. These terpolymers have 5 to
It contains 95 mol% acryloylmorpholine monomer units, and the molecular weight is within the range of 1000-150000. In a preferred embodiment of the invention, the terpolymer is 10
Contains ~30 mol% acryloylmorpholine monomer units. Their molecular weight is preferably
It ranges from 3000 to 100000. A typical composition of the terpolymer according to the present invention is:
It is as follows.

〔Example〕

To illustrate the invention, the following is provided by way of example. The following examples include examples of copolymers consisting of acryloylmorpholine monomer units and carboxylate-containing monomer units, all of which are intended to illustrate the benefits of the present invention. That is, although the present invention relates only to a terpolymer obtained by adding a third vinyl monomer unit to such a copolymer, it shows that the above copolymer is basically effective in preventing scale in boilers and cooling water equipment. It's for a reason. It should be noted that the terpolymer according to the present invention is considered to be novel in itself, and can exhibit an effect equal to or better than that of the copolymer in terms of scale prevention effect. Thus, in the following examples, Examples 7 and 8 are conventional examples, Examples 1 to 4, Examples 6, 9 to 12, and 14 are reference examples for comparison, and Examples 5 and 13 are examples of the present invention. This is an example. Polymer Preparation Example 1 Copolymer of acrylic acid (70 mol%)/acryloylmorpholine (30 mol%) Acrylic acid (50.4 g), acryloylmorpholine (42.3 g), water and 50% NaOH (177.3 g),
A solution with a pH of 4.5 was placed in an autoclave with a pH of 1.5.
The solution was heated to 51°C (124°) in the presence of air. Ammonium persulfate (1.63 g) dissolved in water (10 g) and sodium bisulfite (4 g) dissolved in water (20 g) were added to the solution one after another.
The autoclave valve was immediately closed. The reaction temperature rose to 109℃ (228〓) in 0.6 minutes, and the polymerization took 7
Done in minutes. GC analysis showed that the sample contained 6700 ppm acrylic acid units and 3900 ppm acryloylmorpholine units. The molecular weight of the copolymer was determined using a polystyrene sulfonic acid standard.
It was 12000 as measured by GPC method. Example 2 Copolymer of acrylic acid/acryloylmorpholine A solution of acrylic acid (40.28 g) and acryloylmorpholine (19.72 g) in water (340 g) was added to a into a four neck round bottom reaction flask. The solution was heated to 60°C under nitrogen atmosphere. Ammonium persulfate (3g) and sodium bisulfite (9g)
I added them in order. The reaction temperature rose to 90°C and was maintained at 60°C for 2 hours with gradual cooling. At the end of the reaction, a small amount of gel formed in the solution, which was separated. GC analysis, GPC analysis, and C-13 NMR analysis revealed that the sample contained 450 ppm residual acrylic acid and 410 ppm residual acrylic acid.
The molecular weight of the copolymer was found to be 11,200, and the composition of the copolymer was approximately 90 mol% of acrylic acid units and 10 mol% of acryloylmorpholine units. Example 3 Copolymer of acrylic acid (70 mol%)/acryloylmorpholine (30 mol%) A solution of acrylic acid (34.80 g), acryloylmorpholine (29.20 g), 50% sodium hydroxide and water (330.11 g) with a pH of 4.5 is prepared. , a four-neck round bottom flask equipped with a mechanical stirrer, a thermometer, and a condenser. the solution under nitrogen atmosphere
It was heated to 60° C. and ammonium persulfate (0.64 g) dissolved in water (10 g) and sodium bisulfite (1.92 g) dissolved in water (20 g) were added one after another. The reaction was held at approximately 65°C for 5 hours. The molecular weight of the copolymer was determined by GPC analysis.
It was 90100. Example 4 Copolymer of acrylic acid (80 mol%)/acryloylmorpholine (20 mol%) A solution of acrylic acid (40.28 g) and acryloylmorpholine (19.72 g) dissolved in water (310 g) was prepared using a mechanical stirrer, a thermometer, and a four-necked round-bottomed flask equipped with a condenser. The solution was heated to 60° C. under a nitrogen atmosphere and ammonium persulfate (3 g) dissolved in water (10 g) and sodium bisulfite (9 g) dissolved in water (20 g) were added in sequence. The reaction was maintained at 70°C for 3 hours. According to GPC analysis, the molecular weight of the copolymer is 15600
It was shown that Example 5 Terpolymer of acrylic acid (69 mol%)/methacrylic acid (19.2 mol%)/acryloylmorpholine (11.8 mol%) Acrylic acid (30 g), methacrylic acid (10 g), and acryloyl morpholine (10 g) in water (260 g)
The solution was placed in one four-neck round-bottom reaction flask equipped with a mechanical stirrer, thermometer, and condenser. The solution was heated to 65°C under nitrogen atmosphere. Then, ammonium persulfate (2.5 g) dissolved in water (10 g) and sodium bisulfite (7.5 g) dissolved in water (20 g) were added to the solution one after another. The reaction was maintained at approximately 65°C for 3 hours. The molecular weight of the polymer measured by GPC analysis is
It was 19500. Example 6 Copolymer of acrylic acid (80 mol%)/methacryloylmorpholine (20 mol%) A solution of acrylic acid (42.60 g) and methacryloylmorpholine (23.25 g) dissolved in water (319.98 g) was mixed with a mechanical stirrer and a thermometer. , and a four-neck round-bottom reaction flask equipped with a condenser.
The solution was heated to 60°C under nitrogen atmosphere. Ammonium persulfate (3.29g) dissolved in water (10g)
and sodium bisulfite (9.88 g) dissolved in water (20 g) were added in sequence. The reaction is 3
It was maintained at approximately 75°C for an hour. Analysis showed that the sample contained 2.9% residual acrylic acid and the copolymer molecular weight was 3890. In all the above preparations, the molecular weight of the polymer was between 3000 and 150000. Testing of Polymers as Calcium Phosphate Inhibitors The following test method was used. Procedure for orthophosphoric acid (o- _PO4 ) hypertest (Stabilization test for _Ca3 ( _PO4 ) ₂ ) (Note that all chemicals are reagents except processing agents) 1. Deionize 300-350ml Pour water (DI water) into a 600ml beaker with a jacket and stir gently using a constant temperature water bath until the temperature reaches 70°C (158°C). 2. Pour the required amount of hardness test stock solution into a beaker with jacket. Use 250ppm CaCO ₃ or 50ml for any hardness. How to prepare the hardness test stock solution in Part 2 (1) Dissolve 7.356 g of CaCl ₂ 2H ₂ O in 800 ml of deionized water. (2) Dissolve 6.156 g of MgSO ₄ .7H ₂ O in 800 ml of deionized water. (3) Pour both solutions into volumetric flask 2 and dilute to the specified volume. (4) Shake the flask thoroughly. 3. Add sufficient amount of treatment solution to the jacketed beaker with stirring (typically 5 ml for a concentration of 10 ppm). 4. Add deionized water to the jacketed beaker to make up to 500 ml (add water up to the line of the beaker without turning on the stirrer). 5 While stirring, heat the beaker solution to 70℃ (158℃)
equilibrate to. 6 While stirring, dilute (0.1-0.4N) with NaOH.
Adjust pH to 8.5. 7. Add 5 ml of a 1000 ppm PO ₄ solution with a pH of 8.5 to a jacketed beaker and wait for about 3-5 seconds while stirring. 8 Check the pH of the beaker solution, and if necessary, change the pH.
Adjust to 8.5±0.1 while stirring. 9 Continue the experiment for 4 hours at 70°C (158〓) with stirring. 10 After 15 minutes, check the PH of the beaker solution and adjust the PH to 8.5 ± 0.1 if necessary. Additionally, check the pH of the solution every 30-45 minutes thereafter. 11 After 4 hours, immediately strain the solution through 0.45 μm paper under vacuum. The liquid was analyzed for o- _PO4 using standard procedures and the color was
Measure with 700nm specifications. 12 Results are reported as prevention rate (%) calculated using the formula below. Prevention rate (%) = (residual o-PO ₄ ) - (untreated o-PO ₄
)/(initial o- _PO4 )-(untreated o- _PO4 ) x 100 where initial o- _PO4 = o- in the mixture at the beginning of the experiment.
PO ₄ concentration Residual o-PO ₄ = o-PO ₄ concentration in the mixture at the end of the experiment with stabilizer Untreated o-PO ₄ = o-PO ₄ concentration in the mixture at the end of the experiment without stabilizer Calcium Carbonate Prevention Test The apparatus is based on a Mettler automatic titration system. E- _px converter is Mettler type
The two buffer-two temperature method described in the DK12E- _px converter manual
Calibrated according to method). This calibration is performed for temperature changes over the range 20-70°C
Allows to compensate for PH value. Mettler type E-
The output of the _px converter is in units of 100mV/PH. This signal is recorded as the "observed" mV change as the titration progresses, and the titration breakpoint PH is very easily obtained from the observed mV value. To convert to a "true" mV change, multiply the observed mV change by a number corresponding to the number on the dE/d _px dial. Standard PH = 7 (PH at 60℃
= 6.98) was prepared from Beckman buffer powder and used after each titration to measure the −1 mV (direct value) reference point. _CaCl2・_2H2O and
₃₆₀₀ ^{ppm Ca 2+} _and
Hardness test stock solution containing 2000ppm Mg ²⁺ (20X
Prepare synthetic #3 (equivalent to PCT test water). 2200ppm per day using _NaHCO3
A _HCO3 solution was prepared. Then, prepare a 0.1N NaOH titration solution using the Acculate reagent solution. Inhibitor solution in a 100ml volumetric flask,
Hardness test stock solution (20ml) and bicarbonate solution (20ml)
ml) and then diluted with distilled water. The solution is gently stirred to mix the reagents and then transferred to a jacketed 300 ml Pyrex beaker maintained at 60°C. Initial reagent concentrations were Ca ²⁺ 360ppm;
Mg ²⁺ 200ppm, HCO ₃ ^- 440ppm. Typically 5, 10, or 15 ppm of inhibitor activator (0.5,
1.0, or 1.5 ml stock solution) to obtain a weighing selection curve. The test solution is stirred for 6 minutes to thermally equilibrate. Place the dispensing tip for the NaOH titrant directly above the surface of the test solution. Next, lower the PH electrode into the solution as much as possible, but maintain the gap above the magnetic stirring bar.
Add titrant at 0.3 ml/min (Bulet drive speed = 2) until the band recorder indicates that a slight decrease in PH has occurred. actual PH
Break point (combined with bulk CaCO ₃ precipitation)
It is noteworthy that many test solutions exhibit significant turbidity before . If additional bases are added, generally
A second break point combined with precipitation of Mg(OH) ₂ is observed at higher PH values. After reaching the break point, add a few ml of 10% HCl to the test solution to dissolve the precipitated _CaCO3 . After each titration, the PH electrode shows PH = 6.98 (-1mV, true value)
standard buffer and maintain it at 60°C, and this reference point is indicated on the recorder. Rinse the jacketed beaker with deionized water and then add fresh test solution. 10ppm activity day quest 2010
(Dequest 2010) by titrating a test sample containing (hydroxyethylidene diphosphonic acid) (~
120mV, direct value), calibration verification is performed daily. The relative error of this titration method is generally ±1% (daily)
and ±2% (weeks). saturation rate
The ratios (SR)) are calculated using the following method. The method is called ``Mineol, a computer program for calculating the chemical equilibrium composition of aqueous systems'' written by J.C. Westaall et al. Ralph M. Parsons Laboratory, Water Quality Laboratory,
Technical Note No. 18, July 1976 (Sponsored by EPA,
Grant number R-803738) This is the method described on pages 8 to 10. Examples 7-14 Using the test method described above, the following additional examples in Table 1 were conducted.

The test was carried out using the water shown in [Table].
2) Molecular weight was determined by GPC in aqueous solution using sulfonated polystyrene standards.
In the examples above, Examples 7 and 8 represent prior art calcium phosphate inhibitors. These results demonstrate that copolymers consisting of acryloylmorpholine monomer units and carboxylate-containing vinyl monomer units have scale-inhibiting effects, some of which are more effective than conventional scale inhibitors, and that the present invention is particularly effective. It has been observed that comparable or better scale prevention effects can be achieved by using terpolymers in accordance with the invention. As described above, even with the above-mentioned copolymer, it is possible to obtain effects superior to those of the prior art in some cases, but for practical reasons, the present invention relates only to the case where a terpolymer is used.

Claims (1)

[Scope of Claims] 1. A method for preventing scaling in boilers and industrial cooling equipment, which comprises converting water present in these equipment into acryloylmorpholine monomer units of 90 to
5 mol%, 5 to 90 mol% of carboxylate-containing vinyl monomer units, and 90 to 5 mol% of vinyl monomer units capable of rendering the resulting terpolymer water-soluble, and with a molecular weight in the range of 1000 to 150000. A method comprising treating with 2 to 20 ppm of a terpolymer within. 2. The water contains 30-10 mol% of acryloylmorpholine monomer units, 40-80 mol% of carboxylate-containing vinyl monomer units, and 30-10 mol% of vinyl monomer units capable of rendering the resulting terpolymer water-soluble. The method of claim 1, comprising treating with 2 to 20 ppm of a terpolymer having a molecular weight of from 1000 to 150000.