阅读说明：本技术 一种处理循环冷却水的方法 (Method for treating circulating cooling water ) 是由 王传军 胡芳 孙振宏 纪俊杰 张桂珍 陈彩丽 于 2021-08-26 设计创作，主要内容包括：本发明公开了一种处理循环冷却水的方法,在循环冷却水中加入二氧化碳吸附剂,控制pH值不超过9.4。所述二氧化碳吸附剂为丙烯酸酯、有机胺、有机醇胺之中一种或几种的组合。优选,所述二氧化碳吸附剂乙醇胺和二乙醇胺。二氧化碳吸附剂的投加浓度为0.01～10mmol/L。根据具体情况还可适当投加其它水处理剂,如缓蚀剂、阻垢剂和杀菌剂等。本发明进一步优化现有技术,操作简单,具有很好的推广应用前景。(The invention discloses a method for treating circulating cooling water, which is characterized in that a carbon dioxide adsorbent is added into the circulating cooling water, and the pH value is controlled not to exceed 9.4. The carbon dioxide adsorbent is one or a combination of acrylate, organic amine and organic alcohol amine. Preferably, the carbon dioxide adsorbents ethanolamine and diethanolamine. The adding concentration of the carbon dioxide adsorbent is 0.01-10 mmol/L. Other water treatment agents such as corrosion inhibitors, scale inhibitors, bactericides and the like can be properly added according to specific conditions. The invention further optimizes the prior art, has simple operation and good popularization and application prospect.)

1. A method for treating circulating cooling water is characterized in that carbon dioxide adsorbent is added into the circulating cooling water, and the pH value is controlled not to exceed 9.4.

2. The method for treating recirculated cooling water according to claim 1, wherein the carbon dioxide adsorbent is one or a combination of acrylate, organic amine and organic alcohol amine.

3. The method of treating recirculating cooling water of claim 2 wherein said carbon dioxide sorbents ethanolamine and diethanolamine.

4. The method for treating recirculated cooling water according to claim 2 or 3, wherein the addition concentration of the carbon dioxide adsorbent is 0.01 to 10 mmol/L.

5. The method for treating circulating cooling water according to claim 1, wherein a corrosion inhibitor, a scale inhibitor or a bactericide is further added.

Technical Field

The invention relates to a water treatment method, in particular to a method for treating circulating cooling water, which can inhibit scaling, corrosion and microorganism propagation of a circulating water system.

Background

In the circulating cooling water system, the heavy calcium carbonate in water is decomposed into calcium carbonate by heating, and carbon dioxide escapes, so that the reaction is continuously carried out, and when the product of the concentration of carbonate and calcium ions reaches and exceeds the solubility product of calcium carbonate, the calcium carbonate is crystallized and separated out to form scale.

Ca(HCO₃)₂＝＝CaCO₃+CO₂+H₂O

Early on calcium carbonate deposition was prevented by direct water temperature limitation, acid addition or carbon dioxide addition.

The direct current limits the water temperature to slow down the decomposition of the heavy calcium carbonate at a lower temperature so as to play a role in inhibiting scale.

The hardness of calcium carbonate in water is changed into the hardness of non-carbonate calcium with higher solubility by adding acid, and the calcium content in water is not reduced but the alkalinity of carbonate is reduced after adding acid, so the possibility of calcium carbonate scaling is reduced.

Ca(HCO₃)₂+H₂SO₄→CaSO₄+2CO₂+2H₂O

Adding carbon dioxide to make it react with the following chemical reaction:

CaCO₃+CO₂+H₂O→Ca(HCO₃)₂

because the solubility of the calcium bicarbonate is greatly higher than that of the calcium carbonate, the calcium carbonate can be prevented from scaling on the heat exchanger.

Because the requirement on the scale inhibition effect is higher and higher in production, the method of limiting the water temperature by direct current and adding acid or carbon dioxide is not beneficial to the improvement of the concentration multiple of circulating water, so that users are few and are not used independently. And fifthly and sixty years, special water treatment agents are used for scale inhibition, corrosion inhibition and sterilization. Scale inhibitors are water treatment chemicals that control the production of scale and sludge. The scale inhibitors used in the early days were all processed natural polymer products such as starch, sodium gluconate, tannin, sulfonated lignin, etc. The novel scale inhibitors developed in the 60 s of the 20 th century are all artificially synthesized or polymerized products, have higher scale inhibition rate than natural scale inhibitors, and can meet higher scale inhibition requirements. Commonly used scale inhibitors include polycarboxylic acids, phosphonic acids, organophosphates, and phosphonocarboxylic acids. The scale inhibitor can control not only scale, but also corrosion products, slime and sludge to a certain extent. A large amount of scale forming substances can be controlled by adding a small amount of scale inhibitor, and the scale inhibition mechanism of the scale inhibitor is as follows:

(1) the lattice is distorted. The crystal of inorganic scale (such as calcium carbonate) is arranged according to a certain crystal lattice when growing, and the crystal is compact and firmer. When the water contains polycarboxylic acid or organic phosphate as scale inhibitor, the group of the scale inhibitor has metal ion (such as Ca)²⁺) The chelating ability of the inorganic scale interferes with the crystallization of the inorganic scale, so that the crystal lattice is distorted and becomes irregular crystal, which is the effect of crystal lattice distortion. The lattice distortion changes the hard scale into amorphous soft scale. The scale is not easy to grow up, a large number of gaps are formed in the scale layer, the adhesion force between the gaps is poor, the scale is easy to wash away in water flow, and the scale can be discharged along with sewage.

(2) And (4) complexation and solubilization. The polyphosphate, organic phosphate or polycarboxylic acid can abstract calcium and magnesium ions in water to form a stable complex. This is practically equivalent to reducing the concentration of calcium and magnesium ions in the water, i.e. reducing Ca²⁺With CO₃ ^2-The opportunity to combine to form calcium carbonate. That is, the allowable concentration of calcium and magnesium ions in water is increased, that is, the solubility of calcium and magnesium ions is increased. The complexing solubilization can stabilize more calcium carbonate in water without precipitation.

(3) Agglomeration and dispersion. Negative ions dissociated from the anionic scale inhibitor (polycarboxylic acids) in water can adsorb micro-crystals of scale salt (such as calcium carbonate), so that the micro-crystals form an electric double layer and are further adsorbed on the molecular chain of the negative ions, and the micro-crystals are negatively charged. Because a plurality of micro-crystals on the molecular chain have the same charge and repel each other, the micro-crystals can not form large crystals, so that the scale forming salt is difficult to deposit on the metal heat transfer surface to form a scale layer. The negative ions of the anionic scale inhibitor have coagulation effect on the micro-crystal grains and can be dispersed in the whole water system to ensure that the micro-crystal grains are in an evenly dispersed state. The coagulation and dispersion effect enables the scale forming salt micro-crystal grains to stably suspend in the water, so that the chances of collision growth, crystal nucleus formation and further precipitation of the micro-crystal grains are actually reduced, and more scale forming salt can be contained in the water.

Patent CN 1141258C discloses a method for treating circulating cooling water, which has the technical core that: adding alkaline substances into the circulating cooling water to enable the pH value to reach 9.5-14, wherein the alkaline substances can be oxides, hydroxides, carbonates or bicarbonates of lithium, sodium and potassium or mixtures thereof. Other water treatment agents such as corrosion inhibitors, scale inhibitors, bactericides and the like can be properly added according to specific conditions. The presence of OH in water^-、CO₃ ^2-Then, the pH value is 9.4-11.0; OH alone in water^-Alkalinity, pH>11.0. Adding alkaline substances into circulating cooling water to enable the pH value to reach 9.5-14, and adding HCO (hydrogen peroxide oxide) into the water₃ ^-Will be completely removed while Ca is simultaneously added²⁺Is effectively reduced.

Disclosure of Invention

The invention aims to solve the technical problem of providing a simple and effective method for treating circulating cooling water, and solving the problems of scaling, corrosion and microorganism propagation of a water cooler of a circulating water system by a balanced carbon dioxide method.

In order to solve the technical problems, the invention adopts the technical scheme that: a method for treating recirculated cooling water comprises adding carbon dioxide adsorbent into recirculated cooling water, and controlling pH to be not more than 9.4.

The carbon dioxide adsorbent is one or a combination of acrylate, organic amine and organic alcohol amine. Preferably, the carbon dioxide adsorbents ethanolamine and diethanolamine. The concentration of the carbon dioxide adsorbent is 0.01-10 mmol/L.

Corrosion inhibitors, scale inhibitors or bactericides are also added.

The invention has the beneficial effects that: the risk of scaling on the heat exchange surface of the water cooler is reduced, and the adhesion rate can be controlled within 20 mcm. The formed calcium carbonate crystal grains are softer rhombohedral structure calcite crystals, and are convenient to clean.

Drawings

FIG. 1 is a 1 micron image of soft scale after treatment using the method of the present invention.

FIG. 2 is a 20 micron image of soft scale after treatment using the method of the present invention.

Fig. 3 is a 1 micron image of the hard scale after being treated by the conventional method.

Fig. 4 is a 20 micron image of the hard scale after being treated by the conventional method.

FIG. 5 is an X-ray diffraction curve of soft scale treated by the method of the present invention.

FIG. 6 is an X-ray diffraction curve of a hard scale treated by a conventional method.

FIG. 7 is an infrared spectrum of soft scale after treatment by the method of the present invention.

FIG. 8 is an infrared spectrum of the scale after being treated by the conventional method.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention; it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those skilled in the art without any inventive work are within the scope of the present invention.

According to the method for treating the circulating cooling water, the carbon dioxide adsorbent is added into the circulating cooling water, and the pH value is controlled not to exceed 9.4.

The carbon dioxide adsorbent is one or a combination of acrylate, organic amine and organic alcohol amine. Preferably, the carbon dioxide adsorbents ethanolamine and diethanolamine. The concentration of the carbon dioxide adsorbent is 0.01-10 mmol/L.

Corrosion inhibitors, scale inhibitors or bactericides are also added.

The invention solves the scaling problem of the circulating water system by a carbon dioxide balancing method, further enriches the application of the prior art, is a supplement and perfect to the prior art and achieves the aim of the invention. After a carbon dioxide adsorbent is added into circulating cooling water, circulating water can enrich carbon dioxide to enable the carbon dioxide to perform chemical reaction: CaCO₃+CO₂+H₂O→Ca(HCO₃)₂Because the solubility of the calcium bicarbonate is greatly higher than that of the calcium carbonate, the scaling property of water is reduced, and the calcium carbonate is prevented from scaling on a heat exchanger.

By adopting the method, the scaling property and the corrosivity of the circulating water can be obviously reduced without adding other water treatment agents, so that necessary auxiliary measures are taken in combination with the specific conditions of the system in the using process, and the effect is more remarkable. In order to further control the problems of corrosion, scaling, microorganism breeding and the like generated in the operation, other water treatment agents such as scale inhibitors, corrosion inhibitors, bactericides and the like can be properly added according to the specific conditions such as the content of scaling substances, the content of corrosive substances, the total amount of microorganisms and the like in the circulating water. If the method is applied to a large circulating water system for continuous driving, the existing water treatment system is optimized because the water slag separated out in the system can not be removed in time, a slag removal unit such as a filter is added to remove the water slag regularly, the water slag is prevented from accumulating in the system and entering the system again to interfere the heat exchange of the system, or the water slag is prevented from structural deformation due to long-term accumulation, and finally the water slag is difficult to remove.

Example 1

This example is a static scale inhibition test, performed in the laboratory using hardness measurement. The hard scale assay method is a method capable of simultaneously determining the chelating contribution, the dispersion contribution and the lattice distortion contribution of a scale inhibitor, and comprises the following basic steps: and (3) carrying out a scale inhibition test according to a calcium carbonate deposition method for measuring scale inhibition performance of a water treatment agent, flushing a scale sample on the wall of the device for 2min at a flow speed of 1m/s by using stock solution after finishing the scale inhibition test, and discarding residues on the wall of the device to be considered as hard scales. Used upMeasuring hydrochloric acid to wash the wall of the container, diluting the washing solution to a certain scale, and analyzing Ca in the washing solution²⁺And (4) concentration. The higher the concentration, the more the amount of the hard scale, the worse the comprehensive scale inhibition performance.

Different carbon dioxide adsorbents are added into the water, and the test results are shown in table 1.

TABLE 1 fouling data from the tests

Example 2

This example is a dynamic simulation experiment method for cooling water, which is described in HG/T2160-2008.

The test water quality is groundwater in Tianjin city, and the water quality data is as follows: 24.6mg/L of chloride ions, 10.5mg/L of calcium ions, 4.56mmol/L of total alkalinity, 8.48 of pH value and 582mg/L of conductivity.

A certain amount of carbon dioxide adsorbent 20mg/L is added into the water, the water is stably operated for 15 days when the concentration multiple reaches 8 times, and the experimental data of the uniform corrosion rate and the adhesion rate of the carbon steel are shown in Table 2.

The test results are shown in Table 2.

TABLE 2 Corrosion data obtained by testing

Example 3

This embodiment is applied to the circulating cooling water treatment system of a building in Beijing. Water replenishing: pH7.77, conductivity 560us/cm, total hardness 256mg/L, calcium hardness 152mg/L, total alkalinity 192mg/L, chloride 35.5 mg/L. The equipment pipeline is made of copper material. And adding 20mg/L of diethanolamine and 20mg/L of corrosion and scale inhibitor produced by the company along with water supplement. The method is applied to open the heat exchanger after one year, and the surface of the copper pipe of the equipment is smooth, clean and free of attachments; the daily operation data is as follows: pH9.00, the conductivity is 3900us/cm, the total hardness is 1176mg/L, the calcium hardness is 372mg/L, the total alkalinity is 907mg/L, chloride is 230.4mg/L, and the concentration multiple reaches 7 times; the corrosion rate of the carbon steel hanging piece is 0.0262mm/a, and the corrosion rate of the red copper hanging piece is 0.0011 mm/a.

In combination with the field use condition, the precipitated scale is sampled and analyzed compared with the circulating scale sample of the traditional method, and the specific results are as follows:

(1) SEM image: the soft scale 1 micron image is shown in figure 1; the soft scale 20 micron image is shown in figure 2; hard scale 1 micron image is shown in figure 3; the hard scale 20 micron image is shown in figure 4.

As can be seen from the above two groups of photographs, the shapes of the two types of scales are obviously different, wherein the arrangement structure of the soft scale is mainly a honeycomb loose structure, the configuration of the hard scale is mainly a columnar regular crystal, and the configuration is obviously tighter than the arrangement of the soft scale, so that the difficulty in later-stage removal is increased.

(2) X-ray diffraction (XRD): see figure 5 for soft scale X-ray diffraction; the X-ray diffraction pattern of the scale is shown in FIG. 6.

The crystal forms of calcium carbonate in the soft scale and the hard scale are different, the main component of the soft scale is calcite with a rhombus structure, and the components of the hard scale comprise aragonite and magnesium calcite with a cubic structure.

(3) Infrared: the infrared spectrum of the soft scale is shown in figure 7; the infrared spectrum of the scale is shown in figure 8.

The infrared analysis of the soft scale and the hard scale shows that the main absorption peak can judge that the two scales are both CaCO₃Scale, but the infrared absorption of both scales changed, indicating that there was not a homogeneous type of CaCO₃And (5) structure.

The scale and corrosion inhibition requirements are met through field use, the concentration multiple is increased, the purpose of water saving is achieved, and the safe operation of the system is effectively ensured.

The above-mentioned embodiments are only for illustrating the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and to carry out the same, and the present invention shall not be limited to the embodiments, i.e. the equivalent changes or modifications made within the spirit of the present invention shall fall within the scope of the present invention.