JPS5919597A - Antiscaling agent for desalination of sea water - Google Patents

Abstract

PURPOSE:To enhance an antiscaling effect, by letting the titled agent contain a water-soluble copolymer having the units of a tri- or more polyhydric alcohol mono (metha) allyl ether, an unsaturated carboxylic acid (salt) and an unsaturated monomer. CONSTITUTION:The antiscaling agent for the desalination of sea water is prepared by letting it contain a water-soluble copolymer contain (a) the unit of a tri- or more polyhydric alcohol mono (metha) allyl ether, (b) the unit of an unsaturated carboxylic acid (salt) and (c) the unit of another unsaturated monomer. The mol ratio of said (a) to (b) is pref. held at (a):(b)=1:0.3-1:10, and the total of (a) and (b) is pref. held above 50% on the basis of the weight of said water-soluble copolymer. Said antiscaling agent is pref. added as the water-soluble copolymer in an addition amount of 0.1-50ppm of sea water.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scale 19j inhibitor for seawater desalination. More specifically, the present invention relates to a scale preventive agent for preventing salt scale deposition in seawater desalination bran 1-.

Is there a so-called evaporation method that evaporates and condenses seawater as a seawater desalination method? In this method, calcium carbonate and maxium hydroxide are used on the heat transfer surface of the desalination equipment.

The so-called scale/v (sieve surface) of calcium sulfate, etc. is formed, causing problems such as a reduction in heat transfer efficiency and a reduction in continuous operation time.The main method for preventing the formation and adhesion of these scales is There is a method of adding inhibitors.

As scale inhibitors, various types such as maleic acid homopolymer copolymer, acrylic yarn homopolymer or copolymer, carbonate, phosphorus-containing organic compound, natural polymer, etc. Anti-scaling agents have been proposed, but these cannot be said to be effective in preventing scale in seawater.

The inventors of the present invention have arrived at the present invention as a result of intensive studies to find a scale inhibitor that exhibits a better scale prevention effect than conventional ones when desalinating seawater.

In other words, the present invention provides mono(meth)allyl diether mono(M(a), unsaturation power/
A scale inhibitor for seawater desalination characterized by containing a water-soluble copolymer (a) having l/bonic acid (salt unit (b) and optionally other unsaturated monomer units (c)) be.

The mono(meth)allyl ether of the polyhydric alcohol on both lines forming the unit (a) of the copolymer (a) in the present invention has the general formula (where ■<1 is I] or C) (9, Y is a residue of a trihydric or higher polyhydric alcohol, p is an integer of 2 or more, preferably an integer of 2 to 7, particularly preferably an integer of 2 to 3) Agera number 1. 3 or more and 0] The residue of a polyhydric alcohol refers to an f group obtained by removing a hydroxyl group from a polyhydric alcohol.

The polyhydric alcohol forming the residue of a polyhydric alcohol having 3ωj1 or more is an aliphatic polyhydric alcohol.

Aliphatic amine polyhydric alcohol and /'mafko is its alkylene oxytoy' addition (Sura Jl).As aliphatic polyhydric alcohol, aliphatic 3411 + a) record /V
f Kosae is chrycerin, 1.2.4-butane 1-liol.

1. Trinotyrollethane, trinotyrolpropane.

1,2,6-hexanetriol IV fl and aliphatic 4
Aliphatic alcohols/I/1 such as benquerythritol, erythritol, d- and e-trait, etc.
Sen 1 alcohol atnit etc. Aliphatic hexahydric alcohol 1 word is d-
Omabi e-Turupi 1-, d- and e-mannite and sugars such as d-glucone, d-galacto-7,
d-gycylose, saccharose.

Examples of aliphatic amino polyhydric alcohols include triethanolamine, such as rough) -nu, ma)I/l to -nu.

and a mixture of two or more of them.

Examples of alkylene oxide additives include ethylene oxide and propylene oxide. The number of alkylene ogides is common
The number is 1 to 40, preferably 1 to 10.

(=J+7 number per OH is usually 1 to 5, preferably 1
~3. Among the above polyhydric alcohols, preferably ua
4Tli alcohol, particularly preferably chrycerin and trinotyrolbropane.

3 (+Il+ or more polyhydric alcohol (vine)
As an allyl ether, for example, the following general formula % formula % [In the formula, R is the general formula (same as R1 of +1: I, is Cl
(3 ma is C2H5; A is an alkylene group with 2 to 3 carbon atoms', +1 + nl+02, +13 is a combination thereof, or 0 or 1 is 1 to 5, O or a positive number p; ml
, m2 is an integer from 1 to 4].

The above general formula (21, (3), (Jun, (5 points).

A specific compound is 1-(ivy)allyleoquine-
2,3-dihydroxypropane; 2-(ivy)allyloxy-1,3-dihydroxypropane; 1-(meth)allyloxy 3,4-dihydrokizibucun; 1-(ivy)allyloxy-2,2-dihydroxymethylpropane ;1-(ivy)allylleoquine-2,2-dihydroxymethylbutane;1-(ivy)allyloxyethoxy-2
, 3-dihydroxypropane and 1'-(ivy)allyloxy-2,2-2-trinotyrolethane. Preferred among these are i-(ivy)allyloxy-2,3- Dihydroxypropane; 2-
(7ri) Allyloxy-1,3-dihydroxypropane and 1-(ivy)allyloxy-2,2-dihydroxydinotylbutane.

Unsaturated carboxylic acids (monomers constituting 9 salt units include monoethylenically unsaturated polycarboxylic acids (salts) [maleic acid (salt), fumaric acid (salt), itaconic acid (fiiA))
], monoethylenically unsaturated monocarphonic acid (salt)
[(Notane acrylic acid (salt).

Crotonic acid (salt), cinnamic acid (salt), vinylbenzoic acid (
m) ff and] Kaagera 11ru. Preferred among these are acrylic acid (salts) and especially maleic acid (salts), and mixtures of two or more thereof.

Unsaturated carbonic acid (salt) units (bl is acid type O) may be used, and salts of alkali metals, ammonium or amines may be used.As alkali metals (4, Na, K
, Li'l. As amines (4, mono-, di- and trialkylamines having an alkyl group having 1 to 5 carbon atoms; mono-, di- and 1-realkanolamines such as triethanolamine, heterocyclic amines such as pyridine, etc.), etc. Sign.

Unsaturated carboxylic acids (salt No. 1:) are preferably used.Other unsaturated monomers (as 0) are optionally used as long as the copolymer (8) maintains water solubility. Choose from the following unsaturated monomers:

(1) Hydrophilic unsaturated monomer 1) Monoethylenically unsaturated sulfonic acid monomer: Aliphatic or aromatic monoethylenically unsaturated sulfonic acid monomer 4!tA
The word is vinyl sulfonic acid: styrene sulfonic acid; (
Tsuku) Allylnulfonic acid [(Tsuku) Allylnulfonic acid,
2-Hydroxy-8-(,l#)allyloxypropane sulfonic acid]; (meth)acrylnulphonic acids [nulfobropy/I/(tsuku)acrylate, 2-hydroxy-3-(ivy)acryloxypropylnull Honic acid, 2
-(Ivy)acryloylamino-2,2-dimethylethanesulfonic acid 7r); Alkali metal salt of the above sulfonic acid.

Ammonium salts, amine salts, etc.2) Monoethylenically unsaturated alcohols; (methane
3) Monoethylenically unsaturated mono- or polycarboxylic acid polyol/
I/(alkylene glycol.

Glycerin, polyoxyalkylene licor/l/f
(Do) Engineering 7 Ter: Hydroxyethyl/I/(Tsuku9 Acrylate, Hydroxypropy)Ly (Tsuku) Acrylate-1-71-Lyethylene Glyco/L/(Tsuku) Acrylate T and (2) Weakly Hydrophilic to Hydrophobic Monomer 1) Alkyl nucleates of monoethylenically unsaturated carboxylic acids: methyl(ivy)acrylate-1~, ethyl)v(tsuku)acrylate-1-, maleic acid diethyl ester, 2-ethylhexyl/I/(meth) ) Acrylate, 1-decyl (meth)acrylate, thearyl (meth)acrylate, etc. 2) Monoethylenically unsaturated amino 1-: (meth)acrylamide; N-argyl (meth)acrylamide j Kosaba N-methylacrylamide; N-Hydroxyalgium) Ly (Ivy) Acrylamide l-;N
, N-dihydroxyargyl (ivy) acrylic amine F, etc.
/: Vinyl acrylate, propionate vinyl/L/, #allylic acid and 4) Monoethylenically unsaturated di-1-lyl.

(Ivy) Acrylonitrile, etc. 5) Aromatic monoethylenically unsaturated monomer: Styrene 2 - Alkyl styrene 1 Koeha G (-Noti/I-7 Styrene, etc. 6) Monoethylenically unsaturated ether # Single i substance ：vinyl ethyl ether, vinyl
BRO BI LUE - CHIL VINIL I SO FICH LUE - TER, ALILE LE
(3) Halogen-containing monomer: Vinyl chloride, vinylidene chloride, etc. Among these other unsaturated monomers, preferred are vinyl sulfonic acid and nuthylene sulfonic acid.

() Ta) Allylic alcohol, () Ta,
) Arylylamide, vinyl #11 acid, styrene,
Vinyl chloride and mixtures of two or more of the above.

In the present invention, the molar ratio of units (a) and units (b) in the water-soluble copolymer (a) is as follows, taking into consideration the scale prevention effect: M(a): (b) = 1: 0
．． 8-1: 10 Thea) Ro.

In the above molar ratio, if (b) is less than 0.03, (a) remains in the system and it is difficult to copolymerize completely (b).
When l exceeds 10, the effect of the hydroxyl groups in the resulting water-soluble copolymer is reduced, and a sufficient l scale prevention effect cannot be obtained. Maj, 1T (b) or unsaturated monocarboxylic acid (salt)
In this case, preferably (a):(b)=1:0.8~
1 : 8 Te J) Su(1)) or unsaturated polycarboxylic acid (14 in the case of chlorine, 0 per mole compared to unsaturated monocarboxylic acid (salt)) Carbo(1) is combined with (5 ) is usually 50% or more, preferably 65% or more, based on the weight of (a) and (l).If the total amount of (a) and (l) is less than 50%, the resulting water-soluble copolymer (a) is hydroxyl. , 2i('s effect decreases and sufficient scale protection effect cannot be obtained.

Amount of unit (c) (i) Weigh 2 tons of copolymer or water-soluble
The water-soluble copolymerization is not particularly limited, and is usually 50% or less, preferably 35% or more, based on the weight of the material W [(C
) In the case of weakly hydrophilic to hydrophobic monomers, the proportion is usually 30% or less, preferably 20% or more. If the amount is greater than (c) or the above-mentioned amount, the effect of the water-soluble copolymer shed will be reduced, and it will not matter whether the scale prevention effect is sufficient.

The water-soluble copolymer (a) in the present invention is prepared by preparing 8 double-sided polyhydric alcohol-)vO) mono(meth)allyl ether, an unsaturated carboxylic acid, and other unsaturated monomers as necessary in an aqueous solution. It can be manufactured by copolymerization.

A specific method for producing this 1L copolymer is the method described in Japanese Patent Application No. 57-4868 (in the case of maleic acid) and the use of other unsaturated carboxylic acids in place of maleic acid in this method. I can give you a method.

The water-soluble copolymer (a) is prepared by copolymerizing the monomers described above, but instead of copolymerizing their precursors [by hydrolysis] (a)
It can also be produced by copolymerizing a monomer that can become (b) and then hydrolyzing it.

f Kotoe uses its anhydride (maleic anhydride, itaconic anhydride and IC) instead of unsaturated carboxylic acid, EST/I/(
alkyl esters of monoethylenically unsaturated carboxylic acids listed above), nitriles (such as acrylonitrile), amides (such as acrylamide), and/or 3
Copolymerization is carried out using a polyhydric alcohol mono (instead of methane allyl ether, NTE/I/, etc.) and then hydrolyzed to form the monomer unit (a).
, (1)) and the necessary [(0) copolymer (a) can be produced. In the above method, as acecool and ester of mono(meth)allyl ether of trihydric or higher polyhydric alcohol, For example, the following general formulas (51, (6+, and (7)) can be used.

R.

C)l2=C-CH20-+Y,,)-→OX+
) p 2-4611 This is a j group except for all, and R
is IIyofko+, r C1l:l.

R' is H, CH3 is C2H, , X is I]
This is a residue of a monocarboxylic acid (4F acid, etc.), X2 is a residue of a dicarboxylic acid (oxalic acid, maleic acid, etc.) C=Q, l'2 is an integer of 1 or more .In 4.5 of the above method, polymerization can be carried out by the usual method (Washikiru Gyūsukeso 0) and other solutions (9), and hydrolysis can also be carried out by the usual method (under heating, using an acid or It can be done in the presence of alkali).

Is it the molecule of the water-soluble copolymer W in the present invention? (4 usually 4
00~100.000. Preferably 500-20,00
It is 0.

The molecular weight can be measured by aqueous G, P, C, (Gelper 7-Section Chromatography) or vapor pressure permeation d1.

The scale inhibitor of the present invention is a water-soluble copolymer (containing Al), and the concentration of the water-soluble copolymer added to dU water (4 scale/l/considering the Vj stopping effect) is usually 0.
1-50 ppm, preferably 11-30 ppm.

The scale inhibitor of the present invention may be a water-soluble copolymer (containing Al) or may be used in combination with a known Q scale inhibitor, corrosion inhibitor, and/or antifoaming agent as required. Known inhibitors include maleic acid homopolymers or copolymers, acrylic acid homopolymers or copolymers, polyphosphates, organic compounds containing natural polymers, etc. I can do it.
Known corrosion inhibitors include amines, polyvalent metal salts, and oxycarboxylic acids.

In addition, sponge balls, which are sometimes used to prevent sludge from adhering to seawater evaporators, may be used in combination, if necessary.

The scale inhibitor of the present invention contains a water-soluble copolymer, and can be used in solid form or as an aqueous solution, preferably an aqueous solution in view of ease of addition to seawater.

This invention 0) The anti-scaling agent is applied during the operation of the seawater desalination equipment at the same time as the start of operation, or continuously (intermittently) by pumping directly into the recirculation pipe system or from within the feed tank. Furthermore, depending on the type of desalination equipment, it can also be added to and supplied to the supplementary seawater as necessary.

Conventional seawater desalination equipment can be used to apply the scale inhibitor of the present invention, including multi-stage flash method, multi-effect can type, vapor compression type 4c, and various evaporation methods [e.g. [industrial water] 168, 63 (1972)].

The scale-preventing effect of the water-soluble copolymer (a) was actually confirmed by a scale dispersion test and a scale (=J adhesion prevention tenuto) test.

While conventional scale inhibitors do not show sufficient scale prevention effects on seawater (particularly magnesium hydroxide), the scale inhibitor of the present invention can be used to desalinate seawater by using calcium carbonate, magnesium hydroxide, etc. It sufficiently and effectively suppresses and prevents scale formation, and is particularly effective in preventing the formation of 7-kale caused by magnesium hydroxide compared to conventional scale inhibitors. Therefore.

Since scale adhesion can be almost completely prevented, the thermal efficiency of the heat transfer portion will decrease less even if continuous operation is performed for a longer period of time than in the past.

The present invention will be further explained by Examples and Reference Examples of the present invention, but the present invention is not limited to this fI.

In the Examples, the scale dispersion test 1- and the scale adhesion prevention test were conducted in the manner described above.

(1) Nuke/L10] Dispersion test 1~: 100 m of artificial seawater with a concentration factor of 2 times in a female cylinder on the stopper side of 100 m
ff and 1 ske/L/inhibitor of the present invention in solid content.
It was added so that it was 0 ppm, and then heated to 85°C.
2% Na2 (-033mE) was added to force scale formation in the presence of a scale inhibitor.

A method of measuring the time (minutes) until the end of the line.

(2) SCA/L/Tear, 1-Artificial seawater containing a scale inhibitor at a concentration rate of 2 times (1 e/hrO)
Supplied into a stainless steel vibrator with an inner diameter of 6 mm at a high speed,
While circulating the inside of the vibrator, some parts of the vibrator were heated to 115-120℃ from the outside surface of the vibrator in an oil bath, and after testing for a certain period of time,
By dissolving and removing the Nuke/V components on the inner surface of the vibrator in the heat transfer part at 15 to 120°C by acid washing and quantifying Ca2+ and Mg2+ by atomic absorption spectrometry, we investigated the anti-sealing effect of the scale inhibitor. evaluated.

Reference Example I Ie (1) A fourth flask was equipped with a stirrer, a 2-drop T funnel, a nitrogen gas introduction tube, and a reflux condenser tube, and 1-allyloxy-2,3-dihydroxypropane 1 was added thereto.
82 g, maleic acid 116 g, and 400 g of abacus water were charged. Separately, take 18 g of ammonium persulfate in a beaker, add 90 g of water, dissolve it uniformly, and pour the initiator aqueous solvent into a funnel. 11. tco. 0 in the system due to nitrogen scum
After removing oxygen, the monomer aqueous solution in Furanuco was heated to 85°C, and an initiator aqueous solution was added dropwise from the dropping funnel over 30 minutes. Subsequently, the mixture was aged at 90°C for 1 hour to obtain 748 g of a transparent and uniform water-soluble copolymer O] aqueous solution. The solid content of the aqueous solution was 348% (W/w), and the molecular weight was G.
1000th -) fX from PC.

The aqueous solution was used as a scale inhibitor in Case 1 of Example 1.

Reference Example 2 350 g of toluene was placed in a reaction vessel similar to Reference Example 1 and heated to 80°C. Separately, in a beaker, 2-methyl-
4-allyloxymethy/I/-1,3-shiogisolan 7
2g and 98g of maleic anhydride were taken and heated to 50°C to dissolve them. After cooling to room temperature, add 18 g of peroxide #1 and dissolve it uniformly to prepare a monomer solution.

This monomer solution was added dropwise to the previously prepared toluene for 30 minutes,
Continue to polymerize at 80°C for 1 hour, and then polymerize at 100°C for 1 hour. After completion of polymerization, cool to 40°C, separate the precipitated copolymer from the toluene solution, and dry under reduced pressure.
One piece of 74g of copolymer was obtained.

Water is added to the above copolymer, boiled, and the acetaldehyde produced by hydrolysis is discharged from the system together with water.
Sefco distilled in time. History (Heat for 2 hours.

Upon contact with hydrolysis, a transparent and uniform aqueous solution of water-soluble copolymer 3
I got 45g. The aqueous solution 0] solids content 1 ratio is 51% (
w/w,), molecular weight is 600th by GPC -)
f co.

The aqueous solution was prepared in Example 1, case ① - II/II.
Used as a JJ inhibitor.

Reference Example 3 An aqueous solution was obtained in the same manner as in Reference Example 1 except for changing the raw materials or ratio, and cases Ill, IV and ■ of Example 1 were obtained.
Used as an anti-scaling agent.

Reference Example 4 Put 300g of toluene into the same reaction vessel as Reference Example 1.
, heat to 80°C. Separately, 648 g of 1-allyloxy-2,3-diacetoxypropane and 588 g of maleic anhydride were placed in a beaker, heated to 50°C to dissolve them, and 62 g of styrene was mixed therein. After cooling to room temperature, add 7 g of benzoyl monooxide to a jar and dissolve uniformly to prepare a monomer solution. This monobaric body solution was prepared in the previous 1-
) Add dropwise to V-Ene over 45 minutes and polymerize at 80°C for 1 hour and at 100°C for 2 hours. After the polymerization was completed, the copolymer was cooled to 40°C to precipitate, and the copolymer was filtered and dried under reduced pressure to obtain 116 g of copolymer.

55 g of water was added to the above copolymer and heated under reflux for 13 hours to effect hydrolysis. The resulting homogeneous aqueous solution was evaporated to dryness to obtain 98 g of a hydrolyzed copolymer.

The hydrolysis rate is 493% based on the gaization value, and the molecular weight is 1100% based on GPC.

98 g of water was added to the copolymer to give a solid content of 50.0%.
An aqueous solution of (w/, ) was prepared and used as a scale inhibitor in case ① of Example 1.

Example 1 Monoallyl diether of trihydric or higher polyhydric alcohols (V-(a), unsaturated carboxylic acid (salt)) as shown in Table 1.゛If necessary, a scale dispersibility test is conducted using an aqueous solution of a water-soluble copolymer having another unsaturated monomer unit (c) as a scale inhibitor.The results are shown in Table 1. .

From the results in Table 1, it is clear that the scale inhibitor of the present invention does not produce f
The ability to stably disperse this amount/L/m can be seen.

Example 2 A water-soluble copolymer shown in Table 2 was prepared in the same manner as in Reference Example 1, and the resulting aqueous solution was used as a scale inhibitor, and a scale resistance test was conducted for 20 hours.
The 11° prevention effect was evaluated and the results are shown in Table 2.

Table 1 Table 2 Table 2 shows that the scale inhibitor according to the present invention can prevent scale adhesion in seawater desalination equipment.

Claims (1)

[Scope of Claims] 1 Mono(meth)allyl ether unit of trivalent or higher polyhydric alcohol (a), unsaturated carboxylic acid (salt) unit (b)
) and, if necessary, a water-soluble copolymer (A) having another unsaturated monomer unit (c). 2 The molar ratio of (a) and (b) is (a): (b) =
1:0.3 to 1:10J) The inhibitor according to claim 1. 3. The sum of (a) and (b) is 50 based on the weight of (a)
% or more of the inhibitor according to claim 1 or claim 2, wherein fX +i is at least %. 4 The molecular weight of the water-soluble copolymer (5) is 400 to 100,
000, the inhibitor according to any one of claims 1 to 3. 5 The amount of water-soluble copolymer added to seawater is 01 to 5.
The inhibitor according to any one of claims 1 to 4, wherein n and yr are 0 ppm. 6. The inhibitor according to any one of claims 1 to 5, wherein the trivalent or higher polyhydric alcohol is an aliphatic triol and/or an algylene oxide adduct thereof. 7. Aliphatic triol or chrycerin, 1.2.4-
7. The inhibitor according to claim 6, wherein the inhibitor is a compound selected from the group consisting of butanetriol, 1,2,6-hexanetriol, trimethylolethane and o:+-rimethylolpropane. 8. The inhibitor according to claim 6 or 7, which is an adduct of alkylene oxide or ethylene oxide and/or an adduct of propylene oxide. 9. The inhibitor according to claims 1 to 8, which is an unsaturated carbonic acid or maleic acid.