# Patent

## Title
Terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning and its preparation method

## Abstract

A terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning, containing tourmaline, polyaspartic acid, polyepoxysuccinic acid, polymaleic acid, etidronic acid, zinc salt, and the like, wherein the content of the tourmaline is 5-500 g/t (calculated based on solid form); the content of polyaspartic acid, polyepoxysuccinic acid, polymaleic acid and etidronic acid is 2-60 g/t (calculated based on liquid form); and the content of the zinc salt is 0.2-0.8 g/t (calculated based on solid form), is provided. Also disclosed is a method of preparing the terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to PCT Application No. PCT/CN2014/95251, having a filing date of Dec. 29, 2014, based off of Chinese application No. 201410003767.X having a filing date of Jan. 3, 2014, the entire contents of which are hereby incorporated by reference.
FIELD OF TECHNOLOGY
The following relates to a corrosion and scale inhibitor, and in particular to a terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning, and its preparation method.
BACKGROUND
A circulating water system of central air conditioning generally comprises a cooling water system, a chilled water system and a heating water system, wherein the circulating cooling water system is generally open, and the chilled water and the heating water systems are mostly enclosed. In the open circulating cooling water system, as water contacts with the atmosphere constantly, the content of dissolved oxygen increases, which is likely to cause the electrochemical corrosion; CaCO3 in water is more likely to scale and separate out on the conduction surface with the gradual increase of the salt content of the circulating water in the process of the continuous evaporation of cooling water, and with the degassing of CO2. The cooling water absorbs such a great deal of dust, sand and the like in the air while contacting with the air that the sludge in the system accumulate. In addition, lighting, right temperature and sufficient oxygen and nutrient in the cooling tower are all beneficial to the growth of bacteria and algae, and the concentration of microorganisms and their nutrient sources increase with the circulating concentration, so that slime in the system increase. The corrosion, scale and slime mentioned above are not isolated but interalated with one another. For example, salt deposits and dirt are generally combined together, and corrosion can be caused or aggravated by scale and slime. Therefore, the main task of circulating cooling water treatment is to eliminate or reduce damage caused by scale, corrosion and biological slime.
Generally speaking, the water used in a central air conditioning water system is classified into three types, namely, untreated tap water, softened water and deionized water. The water quality of tap water varies from region to region. In coastal regions of South China, the water qualities of tap water are of ultra-low hardness and high corrosiveness, with water hardness less than 20 mg/L (in CaCO3, the same below), the total alkalinity less than 50 mg/L, and the pH value about 6. In softened water, however, scaling ions such as Ca2+ and Mg2+ are removed, and corrosive ions such as Na+ and Cl− are added, which will not generate the scale, but aggravate the corrosion. Although deionized water has no scaling irons or corrosive ions, it has dissolved oxygen, so the corrosion process can be slow at first and accelerates gradually.
The patent CN103420495A discloses a preparation method and application of a central air conditioning circulating water scale inhibitor which is a copolymer prepared by the polymerization of certain amounts of alkyl glycol ether, maleic anhydride and other polymerizable monomers. The patent CN1754844A discloses an acid antiscaling agent used in circulating water of central air conditioning. The acid antiscaling agent comprises ethylene diamine tetraacetic acid, sodium humate, polyphosphates and water. The two inhibitors above focus on scale inhibition, and pay little attention to corrosion inhibition. The patent CN102718329A discloses a composite corrosion and scale inhibitor of ultra-low hardness circulating cooling water, and a preparation method of the composite corrosion and scale inhibitor which consists of amino tri-methylene phosphonic acid, etidronic acid, diethylenetriaminepenta acid and the like. The patent CN102745823A discloses a quadripolymer corrosion and scale inhibitor PMAHS which consists of maleic anhydride, acrylic acid, hydroxyethyl acrylate, sodium methallylsulfonate, sodium persulfate, sodium persulfate, isopropanol and water, and a preparation method of the quadripolymer corrosion and scale inhibitor. Although the above two inhibitors are excellent in scale inhibition for calcium phosphate scale, calcium carbonate scale and the like, their complex formulae and the operation methods fail to meet the comprehensive requirements of the circulating cooling water system on corrosion inhibition, scale inhibition, sterilization and bacteriostasis.
SUMMARY
An aspect relates to a terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning, characterized by its simple preparation method, convenience to purchase raw materials, low cost and remarkable effect. Its convenient use can be illustrated by the fact that the formula reagent can be added into the circulating cooling water system directly or by using an automatic dosing device after being diluted with water.
The following also provides a preparation method of the terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning.
In order to achieve the purposes and solve the technical problems, the following technical scheme is adopted in embodiments of the present invention. According to embodiments of the invention, the terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning comprises tourmaline, a copolymer and zinc salt, wherein the copolymer is a polymer of any three or four of polyaspartic acid, polyepoxysuccinic acid, polymaleic acid and etidronic acid; the content of tourmaline is 5-500 g/t (calculated based on solid form); the content of the copolymer is 2-60 g/t (calculated based on liquid form); the content of the zinc salt is 0.2-0.8 g/t (calculated based on solid form). The tourmaline in the terpolymerized corrosion and scale inhibitor disclosed by embodiments of the invention may be dravite, schorlite, elbaite, manganese tourmaline, uvite or the like.
The zinc salt in the terpolymerized corrosion and scale inhibitor disclosed by embodiments of the invention is any one or a mixture of zinc sulfate and zinc chloride.
The terpolymerized corrosion and scale inhibitor disclosed by embodiments of the invention further comprises 0.2-2 g/t (calculated based on solid form) of benzotriazole.
The content of the copolymer in the terpolymerized corrosion and scale inhibitor disclosed by embodiments of the invention is 6-16 g/t (calculated based on liquid form).
According to the terpolymerized corrosion and scale inhibitor disclosed by embodiments of the invention, the concentration rate of the circulating cooling water of central air conditioning is 3-12.
In addition, embodiments of the invention further discloses a preparation method of the terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air-conditioning. The preparation method comprises the following steps:
1) dissolving 2-60 g of the polymer of any three or four of polyaspartic acid, polyepoxysuccinic acid, polymaleic acid and etidronic acid into 1000 ml of deionized water, and adding 0.2-0.8 g of the zinc salt;
2) heating it to 55-75° C., performing a heat preservation reaction on the above polymer solution for 4-6 hours under the condition of stirring, and then cooling, thereby obtaining a terpolymerized mother liquor;
3) in 1 L of the circulating cooling water of central air conditioning, firstly feeding 6-600 mg of the tourmaline directly or through a recyclable tourmaline dosing device, and subsequently adding 1 g of the terpolymerized mother liquor directly.
In step 1), 0.2-2 g of benzotriazole is added into the corrosion and scale inhibitor for copper-containing devices.
In step 2), the optimal temperature is 65° C., and the optimal reaction time is 5 hours.
Compared with the prior art, the terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning has the advantages that:
1) the corrosion and scale inhibitor provided by embodiments of the invention is excellent in scale inhibition performance and corrosion inhibition effect, has an excellent protection function on materials such as carbon steel, stainless steel and copper alloy, and is beneficial to the safe and stable operation of the circulating cooling water system;
2) the corrosion and scale inhibitor provided by embodiments of the invention further has the functions of sterilization and bacteriostasis, the problem of water degradation caused in long-term operation of the circulating cooling water can be solved, and the circulating cooling water system can be in a stable state with good water quality;
3) the corrosion and scale inhibitor provided by embodiments of the invention has the advantage of low dosing concentration and generally depends on synergism of the formula components;
4) the corrosion and scale inhibitor provided by embodiments of the invention has the advantages of simple preparation method, convenience in use and the like. The production raw materials are easy to purchase, low in cost and remarkable in effect. The formula reagent can be added into the circulating cooling water system directly or by using the automatic dosing device after being diluted with water when being used.


DETAILED DESCRIPTION OF THE EMBODIMENTS
A terpolymerized corrosion and scale inhibitor for used in circulating cooling water of central air conditioning, which consists of tourmaline, polyaspartic acid, polyepoxysuccinic acid, polymaleic acid or etidronic acid, zinc salt and the like, wherein any three or four of polyaspartic acid, polyepoxysuccinic acid, polymaleic acid and etidronic acid are polymerized; the tourmaline may be dravite, schorlite, elbaite, manganese tourmaline, uvite or the like. The content of the tourmaline is 5-500 g/t (calculated based on solid form, i.e. the solid addition amount in each ton of water); the content of polyaspartic acid, polyepoxysuccinic acid, polymaleic acid or etidronic acid is 2-60 g/t (calculated based on liquid form, i.e. the liquid addition amount in each ton of water); the content of the zinc salt is 0.2-0.8 g/t (calculated based on solid form zinc salt, i.e. the solid zinc salt addition amount in each ton of water). The zinc salt is selected from any one or two of zinc sulfate and zinc chloride. Copper corrosion can be effectively inhibited by adding 0.2-2 g/t (calculated based on solid form, i.e. the benzotriazole addition amount in each ton of water) of benzotriazole into the copper-containing devices.
Embodiment 1
A terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning, 20 g of polyaspartic acid, 15 g of polyepoxysuccinic acid, 12 g of etidronic acid and 0.6 g of ZnSO4 solid are sequentially dissolved into 1000 ml of deionized water that define a polymer solution, which is heated to 65° C., performed a heat preservation reaction for 5 hours under the condition of stirring, and then cooled, thereby the terpolymerized mother liquor is obtained.
In 1 L of the circulating cooling water of central air conditioning, firstly 100 mg of the tourmaline is feeded directly or through a recyclable tourmaline dosing device, and secondly 1 g of the terpolymerized mother liquor is added directly. The tourmaline can be recycled.
Embodiment 2
A terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning, 20 g of polyaspartic acid, 18 g of polyepoxysuccinic acid, 12 g of etidronic acid, 15 g of polymaleic acid and 0.6 g of ZnSO4 solid are sequentially dissolved into 1000 ml of deionized water that define a polymer solution, which is heated to 65° C., performed a heat preservation reaction for 5 hours under the condition of stirring, and then cooled, thereby the terpolymerized mother liquor is obtained.
In 1 L of the circulating cooling water of central air conditioning, firstly 100 mg of the tourmaline is feeded directly or through the recyclable tourmaline dosing device, and secondly 1 g of the terpolymerized mother liquor is added directly. The tourmaline can be recycled.
Embodiment 3
A terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning, 15 g of polyaspartic acid, 10 g of polyepoxysuccinic acid, 10 g of polymaleic acid and 0.6 g of ZnSO4 solid are sequentially dissolved into 1000 ml of deionized water that define a polymer solution, which is heated to 55° C., performed a heat preservation reaction for 4 hours under the condition of stirring, and then cooled, thereby the terpolymerized mother liquor is obtained.
In 1 L of the circulating cooling water of central air conditioning, firstly 120 mg of the tourmaline is feeded directly or through the recyclable tourmaline dosing device, and secondly 1 g of the terpolymerized mother liquor is added directly. The tourmaline can be recycled.
Embodiment 4
A terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning, 15 g of polyaspartic acid, 12 g of etidronic acid, 10 g of polymaleic acid, 0.6 g of ZnSO4 solid and 1.8 g of benzotriazole are sequentially dissolved into 1000 ml of deionized water that define a polymer solution, which is heated to 65° C., performed a heat preservation reaction for 5 hours under the condition of stirring, and then cooled, thereby the terpolymerized mother liquor is obtained.
In 1 L of the circulating cooling water of central air conditioning, firstly 120 mg of the tourmaline is feeded directly or through the recyclable tourmaline dosing device, and secondly 1 g of the terpolymerized mother liquor is added directly. The tourmaline can be recycled.
Embodiment 5
A terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning, 15 g of polyaspartic acid, 10 g of polyepoxysuccinic acid, 12 g of etidronic acid, 10 g of polymaleic acid and 0.6 g of ZnSO4 solid are sequentially dissolved into 1000 ml of deionized water that define a polymer solution, which is heated to 75° C., performed a heat preservation reaction for 6 hours under the condition of stirring, and then cooled, thereby the terpolymerized mother liquor is obtained.
In 1 L of the circulating cooling water of central air conditioning, firstly 120 mg of the tourmaline is feeded directly or through the recyclable tourmaline dosing device, and secondly 1 g of the terpolymerized mother liquor is added directly. The tourmaline can be recycled.
In the embodiments of the invention, a carbon steel test piece is made of #20 steel, and the specification is 500 mm*25 mm*2 mm. The corrosion inhibition performance is tested according to the National Standards of the People's Republic of China GB/T18175-2000, Determination of Corrosion Inhibition Performance of Water Treatment Agents—Rotation Specimen Method, a rotating hanging sample corrosion analyzer is adopted for corrosion inhibition test, the temperature is 45° C., and the rotation speed is 75 r/min. The scale inhibition performance is tested according to the National Standards of the People's Republic of China GB/T16632-2008, Determination of Scale Inhibition Performance of Water Treatment Agents—Calcium Carbonate Precipitation Method. 
Water with pH of 6.8, the electric conductivity of 134 μs/L, the total hardness (in CaCO3) of 48 mg/L, the total alkalinity (in CaCO3) of 22 mg/L and 16 mg/L of chloridion (Ci) is taken from a municipal water supply station in Guangzhou to prepare test water with the concentration rate of 5 (the concentration rate of the circulating cooling water is 3-12), pH is 7.6, the total hardness (in CaCO3) is 242 mg/L, and the total alkalinity (in CaCO3) is 108 mg/L.







TABLE 1







List of corrosion and scale inhibition performance of embodiments 1-5



















Polyepoxysuccinic
etidronic
Polymaleic


Corrosion




Tourmaline
Polyaspartic
acid
acid
acid
Zinc
Benzotriazole
rate
Scale inhibition


Embodiment
(mg/L)
acid (mg/L)
(mg/L)
(mg/L)
(mg/L)
salt (mg/L)
(mg/L)
mm/a
rate %



















1
100
20
15
12
0
0.6
0
0.042
94


2
100
0
18
12
15
0.6
0
0.036
96


3
120
15
10
0
10
0.6
0
0.032
98


4
120
15
0
12
10
0.6
1.8
0.003
96


5
120
15
10
12
10
0.6
0
0.003
98









In the embodiments 1-5 in the table 1, the tourmaline, the polyaspartic acid, the polyepoxysuccinic acid, the etidronic acid, the polymaleic acid, the zinc sulfate and the like are mixed in different ratios, and thus multi-component composite formulae with synergistic effect can be obtained.
Corrosion rates obtained from hanging sample corrosion tests (carbon steel corrosion tests in embodiments 1-3, copper alloy corrosion tests in embodiment 4 and stainless steel corrosion tests in embodiment 5) show that:
Under the working condition of simulated circulating cooling water, the composite formulae all have good corrosion inhibition performance, the corrosion rates are all less than 0.075 mm/a, and the corrosion is less than the corrosion rate upper limit 0.075 mm/a (the corrosion rate upper limit 0.005 mm/a of copper alloy and stainless steel) of the carbon steel devices according to GB 50050-2007 Code for Design of Industrial Recirculating Cooling Water Treatment, and the scale inhibition performance can also meet provisions of the national standard. The corrosion and scale inhibitor provided by embodiments of the invention has the advantages of excellent performance, simple preparation method, convenience in use, low dosing concentration and the like, and has wide application prospects and high economic values.
The following provides a simple formula and a simple operation method which not only can meet the requirements of the circulating cooling water system on corrosion and scale inhibition, but also are small in dosage, low in cost and good in effect, and remarkable economic benefits and wide social benefits can be made.
The content above is only relatively optimal embodiments of the invention and does not limit embodiments of the invention in any mode, and content within the technical scheme of embodiments of the invention, any simple modification and equivalent variation and embellishment to the embodiments according to the technical essence of embodiments of the invention all belong to the technical scheme of embodiments of the invention.

## Claims

1. A terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning, comprising: tourmaline, a copolymer and zinc salt, wherein the tourmaline may be dravite, schorlite, elbaite, manganese tourmaline, or uvite, the zinc salt is any one or a mixture of zinc sulfate and zinc chloride, wherein the copolymer is a polymer of any three or four of polyaspartic acid, polyepoxysuccinic acid, polymaleic acid and etidronic acid; wherein a content of tourmaline is 5-500 grams per metric ton (g/t) calculated based on solid form; a content of the copolymer is 2-60 grams per metric ton (g/t) calculated based on liquid form; and a content of the zinc salt is 0.2-0.8 grams per metric ton (g/t) calculated based on solid form.

2. The terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning according to claim 1, wherein the content of the copolymer is 6-16 g/t calculated based on liquid form.

3. The terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning according to claim 1, wherein a concentration rate of the circulating cooling water of central air conditioning is 3-12.

4. A preparation method of the terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning according to the claim 1, wherein the preparation method comprises the following steps:
1) dissolving 2-60 g of the polymer of any three or four of polyaspartic acid, polyepoxysuccinic acid, polymaleic acid and etidronic acid into 1000 ml of deionized water, and adding 0.2-0.8 g of the zinc salt;
2) heating to 55-75° C., and performing a heat preservation reaction on the polymer solution for 4-6 hours under the condition of stirring, and then cooling, thereby obtaining a terpolymerized mother liquor; and
3) in 1 L of the circulating cooling water of central air conditioning, firstly feeding 6-600 mg of the tourmaline directly or through a recyclable tourmaline dosing device, and subsequently adding 1 g of the terpolymerized mother liquor directly.

5. The preparation method of the terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning according to claim 4, wherein in step 1), 0.2-2 g of benzotriazole is added into the corrosion and scale inhibitor for copper-containing devices.

6. The preparation method of the terpolymerized corrosion and scale inhibitor used in circulating cooling water of central air conditioning according to claim 4, wherein in step 2), the optimal temperature is 65° C., and the optimal reaction time is 5 hours.