JP2008307512A - Water treatment agent and control method of cooling water or the like - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water treatment agent and a control method of cooling water or the like, capable of suppressing formation of slime, attachment of scale and corrosion. <P>SOLUTION: The water treatment agent comprises an aqueous solution containing a water-soluble polymer, oxycarboxylic acid, an azole compound, an isothiazoline compound, and a phosphon compound as effective components. The agent is used in a state of keeping concentrations of the water-soluble polymer, oxycarboxylic acid, the azole compound, isothiazoline compound and phosphon compound, equal to or more than 12 mg/L, 10 mg/L, 1 mg/L, 0.3 mg/L, and 8 mg/L, respectively. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a water treatment agent suitable for use as cooling water in a cooling tower of a refrigeration air conditioner, and a management method for cooling water using the water treatment agent.

  Conventionally, as an example, a cooling tower of a refrigeration air conditioner directly contacts the cooling water and the atmosphere by sprinkling cooling water used for cooling a heat exchanger (condenser or absorber) of the refrigeration air conditioner. Thus, a part of the cooling water is evaporated and the cooling water is cooled by the heat of vaporization at that time. At this time, this cooling water comes into contact with the inner wall of the pipe of the heat exchanger of the refrigeration and air conditioning equipment, and the inner wall of the pipe corrodes. is there. Moreover, as the cooling water evaporates, the deposited salts adhere as a scale to the inner wall of the heat exchanger pipe, deteriorating the heat exchange performance. Also, microorganisms are mixed in from the atmosphere, and this grows and slime is generated and adheres to the heat exchanger, so that the heat exchange performance of the heat exchanger deteriorates, the water flow resistance increases, the piping of the heat exchanger Obstacles such as corrosion are promoted.

Therefore, in order to prevent the above-described obstacles, attempts have been made to add a water treatment agent to the cooling water. The water treating agent contains an isothiazolone compound, a carboxylic acid-based low molecular weight polymer and / or phosphonic acid, and an azole compound as active ingredients, and the isothiazolone compound is converted into 2-methyl-4 -The thing made into isothiazoline-3-one is proposed (for example, refer patent document 1).
JP 2002-193711 A

  However, in the water treatment agent described in JP-A-2002-193711 described above, since the isothiazolone compound is 2-methyl-4-isothiazolin-3-one, the price is increased and the growth of microorganisms is inhibited. In order to achieve this, the concentration of the isothiazolone compound has to be increased.

  The present invention has been made from the above-described actual state of the prior art, and its object is to reduce the production of slime and scale on the heat exchanger piping and the corrosion of the heat exchanger piping. An object of the present invention is to provide a method for managing a water treatment agent, cooling water, and the like that have been made possible.

  In order to achieve the above object, the present invention is a water treatment agent comprising an aqueous solution containing a water-soluble polymer, an oxycarboxylic acid, an azole compound, an isothiazoline compound, and a phosphonic compound as active ingredients. It is a feature.

  In the water treatment agent of the present invention, the isothiazoline compound is a mixture of 2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one and magnesium salt, 2 -N-octyl-4-isothiazolin-3-one, 2-ethyl-4-isothiazolin-3-one, 2-butyl-4-isothiazolin-3-one, 2-vinyl-4-isothiazolin-3-one, 2 -Hexyl-4-isothiazolin-3-one.

  The water treatment agent of the present invention is characterized in that the oxycarboxylic acid is citric acid, tartaric acid, malic acid, glycolic acid or a salt thereof.

  Further, in the water treatment agent of the present invention, the phosphone compound may be 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxy-ethylene-1, 1-bisphosphonic acid, aminotricarboxylic acid or a salt thereof, ethylenediaminetetra It is characterized by being methylenephosphonic acid or a salt thereof, nitrotrimethylenephosphonic acid or a salt thereof.

  Furthermore, the management method of the cooling water or the like of the present invention is a water treatment comprising an aqueous solution containing a water-soluble polymer, an oxycarboxylic acid, an azole compound, an isothiazoline compound, and a phosphonic compound as active ingredients in the cooling water that is the liquid to be treated. The concentration of the water-soluble polymer, oxycarboxylic acid, azole compound, isothiazoline compound and phosphone compound in the cooling water is adjusted so that the water-soluble polymer is 12 mg / L or more and the oxycarboxylic acid is 10 mg / L. It is characterized in that the azole compound is maintained at 1 mg / L or higher, the isothiazoline compound is maintained at 0.3 mg / L or higher, and the phosphone compound is maintained at 8 mg / L or higher.

  According to the present invention, generation of slime and scale adhesion to the heat exchanger piping and corrosion of the heat exchanger piping are suppressed, deterioration of the heat exchange performance of the heat exchanger and corrosion of the heat exchanger piping. In addition, it is possible to suppress the generation of pores due to water, and as a isothiazolone compound, 2-chloro-4-isothiazolin-3-one, which is expensive, is not used, but a general 5-chloro-2 as a disinfectant is used. -When a mixture of methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one is used, the isothiazolone compound is used alone as 2-methyl-4-isothiazolin-3-one; Since the same effect can be obtained, it is possible to obtain a management method for water treatment agents, cooling water, and the like that can be reduced in price.

  Hereinafter, an embodiment example of a management method for a water treatment agent and cooling water according to the present invention will be specifically described.

Calcium carbonate precipitates when a high-concentration solution of hydrogen carbonate ions and calcium ions is left to heat, and this calcium carbonate adheres to the pipe inner wall of the piping material (refrigeration air conditioner heat exchanger), etc. Generated. When calcium carbonate is generated (deposited), the concentration of dissolved calcium in the test water (sample) water decreases. Therefore, in order to accelerate the precipitation of calcium, the concentration of each additive component is determined using a calcium solution whose hydrogen carbonate ion is at a molar concentration of calcium ion, twice as high as a calcium solution (about 20 times normal tap water). As a result of conducting a test for examining the influence of the concentration of dissolved calcium under the test conditions shown in Table 1, the analysis results (analysis results of dissolved calcium) shown in Table 2 were obtained.

  Since the concentration of dissolved calcium before the test is 400 mg / L, as shown in Reagent No. 1 in Table 1, when no reagent (water treatment agent) is added, the calcium precipitation inhibition rate is (5 / 400) × 100 = 1.3%, which is bad. Similarly, when water soluble polymer 12 mg / L or more and phosphone compound 8 mg / L or more coexist, precipitation of calcium as shown in Reagent No. 5 to No. 6 and Reagent No. 10 to No. 22 in Table 1. It can be seen that the suppression rate is as good as 80% or more. In addition, the azole compound, the isothiazoline compound, and the oxycarboxylic acid did not show the effect of suppressing the precipitation of calcium carbonate. By this, it can be confirmed that the precipitation of calcium can be suppressed by 80% or more by coexisting 12 mg / L or more of the water-soluble polymer and 8 mg / L or more of the phosphone compound.

Next, when the isothiazoline compound is added to the solution and heated, the isothiazoline compound decomposes and becomes cloudy. Therefore, as a result of conducting a test (white turbidity confirmation test) for confirming the presence or absence of white turbidity of various reagents, the results shown in Table 3 were obtained. In this case, in the test conditions shown in Table 1, the test water was tap water having a low calcium concentration in order to distinguish it from precipitation of calcium carbonate.

  From the results shown in Table 3, it was found that by adding 8 mg / L or more of the phosphonic compound, the phosphonic compound is not clouded and the phosphonic compound has an effect of suppressing the decomposition of the isothiazoline compound.

Next, in order to grasp the corrosion inhibitory effect of iron and copper, a test for confirming the degree of corrosion when various kinds of additive components are changed is performed according to the corrosion test method shown in Table 4 (JISK0100 industrial water corrosion test method). The results of the test using the test water of Table 5 were obtained, and the iron corrosion test results shown in Table 6 and the copper corrosion test results shown in Table 7 were obtained.

According to the iron corrosion test results in Table 6 above, no significant effect on the inhibition of iron corrosion was observed for water-soluble polymers, azole compounds, isothiazoline compounds, and phosphone compounds, excluding oxycarboxylic acids. It was. However, it was confirmed that by adding 10 mg / L or more of oxycarboxylic acid, the corrosion degree of iron becomes 1/3 or less as compared with the case where oxycarboxylic acid is not added.

  According to the copper corrosion test results shown in Table 7 above, it was confirmed that the addition of 1 mg / L or more of the azole compound suppresses copper corrosion to about 1/3.

Next, as a result of conducting a test for grasping the microbial inhibition effect using test water (test solution) having the composition shown in Table 9 under the microbial inhibition test conditions shown in Table 8, the microbial inhibition shown in Table 10 was obtained. Test results were obtained. In addition, the test water used the cooling water currently used for the normal cooling tower in which microorganisms inhabit and the nutrients required for reproduction are fully contained.

  From the results shown in Table 10, it was confirmed that by adding 0.3 mg / L or more of the isothiazoline compound, the microorganism (viable cell count) was reduced to about 1/200 or less.

  In each of the above-described tests, in order to improve the scale inhibitory effect, the stability of isothiazoline, the anticorrosive effect and the bactericidal effect of iron and copper, each concentration of the additive component of the water treatment agent for cooling water is 12 mg of water-soluble polymer. / L or higher, azole compound at 1 mg / L or higher, isothiazoline compound at 0.3 mg / L or higher, phosphone compound at 8 mg / L or higher, and oxycarboxylic acid at 10 mg / L or higher. I understood. Therefore, the target concentration of the water treatment agent addition component for cooling water is 12 mg / L for the water-soluble polymer, 1 mg / L for the azole compound, 0.3 mg / L for the isothiazoline compound, and 8 mg / L for the phosphone compound. The oxycarboxylic acid is set to 10 mg / L.

  In actual water treatment, a high-concentration water treatment agent is added so that the added component has a target concentration in the cooling water. The concentration of the water treatment agent additive component can be determined by the formula of the concentration of the water treatment agent additive component = (target maintenance concentration of cooling water) × dilution ratio if the number of dilutions in the cooling water is known. .

If the concentration of each additive component in the water treatment agent is increased, the dilution rate can be increased, so the amount used (cooling water) can be reduced, but the content of the additive component increases, so the raw material cost (additive component) Cost of raw materials). On the contrary, if the concentration of each additive component of the water treatment agent is lowered, the content of the additive component is reduced, so the raw material cost (the raw material cost of the additive component) can be kept low, but the dilution factor is lowered. As a result, the amount used (cooling water) increases and the distribution cost increases. Therefore, in order to appropriately suppress both the raw material cost (the raw material cost of the additive component) and the distribution cost, when the dilution factor is set to 3000, the relationship between the target maintenance concentration in the cooling water and the additive component in the water treatment agent is The concentration of the added component of the treatment agent = (target maintenance concentration of cooling water) × dilution ratio can be obtained as shown in Table 11.

Claims (5)

  A water treatment agent comprising an aqueous solution containing a water-soluble polymer, an oxycarboxylic acid, an azole compound, an isothiazoline compound, and a phosphone compound as active ingredients.   The isothiazoline compound is a mixture of 2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one and magnesium salt, 2-n-octyl-4-isothiazoline-3 -One, 2-ethyl-4-isothiazolin-3-one, 2-butyl-4-isothiazolin-3-one, 2-vinyl-4-isothiazolin-3-one, 2-hexyl-4-isothiazolin-3-one The water treatment agent according to claim 1, wherein   The water treatment agent according to claim 1, wherein the oxycarboxylic acid is citric acid, tartaric acid, malic acid, glycolic acid or a salt thereof.   The phosphone compound includes 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxy-ethylene-1, 1-bisphosphonic acid, aminotricarboxylic acid or a salt thereof, ethylenediaminetetramethylenephosphonic acid or a salt thereof, nitrotrimethylene The water treatment agent according to claim 1, which is phosphonic acid or a salt thereof.   A water treatment agent comprising an aqueous solution containing a water-soluble polymer, an oxycarboxylic acid, an azole compound, an isothiazoline compound, and a phosphone compound as active ingredients is added to the cooling water that is the liquid to be treated. Concentrations of polymer, oxycarboxylic acid, azole compound, isothiazoline compound, and phosphone compound are 12 mg / L or more for the water-soluble polymer, 10 mg / L or more for the oxycarboxylic acid, and 1 mg / L or more for the azole compound. A method for managing cooling water or the like, wherein the isothiazoline compound is used in a state maintained at 0.3 mg / L or more and the phosphone compound is maintained at 8 mg / L or more.