Device and method for evaluating scale inhibitor

Abstract

A device for evaluating a scale inhibitor for a circulating cooling water system, the device including: an open vessel, the open vessel including a first fixing hole, a second fixing hole, and at least one test hole; a stirrer; a test piece; a condenser; and a constant temperature heater. The open vessel is disposed inside the constant temperature heater. The first fixing hole is used to fix the stirrer. The second fixing hole is used to fix the condenser. The test hole is used to fix the test piece.

Claims

1. A device for evaluating a scale inhibitor, the device comprising: a) an open vessel (1), the open vessel (1) is adapted to contain a test solution having calcium ions; and the open vessel (1) comprising a first fixing hole (11), a second fixing hole (14), and at least one test hole; b) a stirrer (2), the stirrer (2) comprising a rotational shaft and a blade; c) a stainless-steel piece (3); d) a condenser (4); and e) a constant temperature heater (5); wherein: the open vessel (1) is operatively disposed inside the constant temperature heater (5); the stirrer (2), the stainless-steel piece (3), and the condenser (4) are operatively inserted into the open vessel (1) through the first fixing hole (11), the test hole, and the second fixing hole (14), respectively; the stirrer (2) is operatively fixed by the first fixing hole (11); the condenser (4) is operatively fixed by the second fixing hole (14); the stainless-steel piece (3) is operatively fixed by the test hole; the constant temperature heater (5) is adapted to heat the open vessel (1) at a constant temperature; the condenser (4) is adapted to condense water vapor formed by evaporation of the test solution, thereby maintaining a volume of the test solution constant; the blade is operatively inserted into the test solution, and is adapted to stir the test solution; the stainless-steel piece (3) is operatively inserted into the test solution, and is adapted to absorb calcium carbonate formed by crystallization of the calcium ions; and the stainless-steel piece (3) is operatively disposed parallel to the rotational shaft.

2. The device of claim 1, wherein: the open vessel (1) comprises three test holes; and the three test holes and the second fixing hole (14) are evenly arranged around the first fixing hole (11).

3. The device of claim 1, wherein the condenser (4) is a glass tube comprising two ends; one end of the glass tube communicates with the air inside the open vessel (1); the other end of the glass tube communicates with the atmosphere; the glass tube has an outer diameter between 3 and 6 mm and a length between 30 and 40 cm for condensing water vapor.

4. The device of claim 2, wherein the condenser (4) is a glass tube comprising two ends; one end of the glass tube communicates with the air inside the open vessel (1); the other end of the glass tube communicates with the atmosphere; the glass tube has an outer diameter between 3 and 6 mm and a length between 30 and 40 cm for condensing water vapor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described hereinbelow with reference to the accompanying drawings, in which:

(2) FIG. 1 is a structure diagram of a device for evaluating a scale inhibitor for a circulating cooling water system in accordance with one embodiment of the invention; and

(3) FIG. 2 is a top view of an open vessel in accordance with one embodiment of the invention.

(4) In the drawings, the following reference numbers are used: 1. Open vessel; 11. First fixing hole; 12. First test hole; 13. Second test hole; 14. Second fixing hole; 15. Third test hole; 2. Stirrer; 3. Test piece; 4. Condenser; and 5. Constant temperature heater.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(5) For further illustrating the invention, experiments detailing a device and a method for evaluating a scale inhibitor for a circulating cooling water system are described below. It should be noted that the following examples are intended to describe and not to limit the invention.

EXAMPLE 1

(6) As shown in FIGS. 1-2, a device for evaluating a scale inhibitor for a circulating cooling water system comprises: an open vessel 1; a stirrer 2; a test piece 3; a condenser 4; and a constant temperature heater 5. The open vessel 1 is disposed inside the constant temperature heater 5. The open vessel 1 is provided with a first fixing hole 11 for fixing the stirrer 2, and a second fixing hole 14 for fixing the condenser 4. The condenser 4 herein is a glass tube comprising two ends. One end of the glass tube communicates with the air inside the open vessel 1; and the other end of the glass tube communicates with the atmosphere. The glass tube has an outer diameter of 5 mm and a length of 35 cm for condensing the water vapor and maintaining a constant volume of a test solution in the open vessel 1. The open vessel 1 is provided with a first test hole 12, a second test hole 13, and a third test hole 15 for fixing test pieces 3, respectively. The test pieces herein are made of stainless steel No. 304 manufactured by Shandong Yangxin Senpu Technology Limited. The test pieces of stainless steel No. 304 have a size of 20103 mm and are suspended in the test solution in the open vessel 1. An arrangement of the stainless steel test piece is in parallel with a flow direction of the test solution. The first test hole 12, the second test hole 13, the third test hole 15, and the second fixing hole 14 are evenly arranged around the first fixing hole 11.

(7) The open vessel herein is a five-neck flask that is self-designed and is processed by Yanzhibao Experimental Equipment Marketing Center in Qinhuai district, Nanjing, China. The open vessel has a capacity of 500 mL. The first fixing hole 11, the first test hole 12, the second test hole 13, the second fixing hole 14, and the third test hole 15 are all ground according to the 24# ground standard. The first fixing hole 11 is arranged at a center position, as shown in FIG. 2.

(8) Scale inhibition of hydrolyzed polymaleic anhydride (HPMA), provided by Nanjing Naco Water Treatment Technology Co., Ltd., was evaluated, and a method for evaluating HPMA for a circulating cooling water system comprises the following steps:

(9) 1) Treatment of a test piece: Wash the test piece 3 in acetone in the presence of ultrasonic wave, and desiccate the test piece 3 in a desiccator.

(10) 2) Preparation of a test solution: a) Dilute the HPMA scale inhibitor in a 100 mL volumetric flask to a HPMA concentration of 5 mg/mL (referring to a dry basis). Prepare a 0.01 mol/L EDTA standard solution and preserve the 0.01 mol/L standard EDTA solution in a brown volumetric flask. Prepare a 200 g/L potassium hydroxide solution and preserve the 200 g/L potassium hydroxide solution in a plastic reagent bottle. Prepare a 0.01 mol/L borax buffer solution. b) Prepare a sodium bicarbonate mother solution comprising a HCO.sub.3.sup. concentration of 18.3 mg/mL. Prepare a calcium chloride mother solution comprising a Ca.sup.2+ concentration of 6.0 mg/mL. Titrate the sodium bicarbonate mother solution and the calcium chloride mother solution by using a hydrochloric acid standard solution and the EDTA standard solution, respectively. A HCO.sub.3.sup. concentration of the sodium bicarbonate mother solution after the titration is 18.1 mg/mL, and a Ca.sup.2+ concentration of the calcium chloride mother solution is 5.9 mg/mL. c) Add 300 mL distilled water into a 500 mL volumetric flask; transfer the titrated calcium chloride mother solution, 1 mL HPMA solution, 20 mL prepared borax buffer solution to the volumetric flask by using pipettes, respectively. Transfer the titrated sodium bicarbonate mother solution to the volumetric flask by using a pipette while shaking. Add distilled water into the volumetric flask to the test solution having a calcium ion concentration of 240 mg/L and a bicarbonate ion concentration of 366 mg/L;

(11) 3) Scale formation test: Transfer the test solution prepared in step 2) to an open vessel 1; provide three test pieces 3 prepared in step 1) and measure weight thereof represented by m.sub.11, m.sub.12, and m.sub.13, respectively, as shown in Table 1.

(12) TABLE-US-00001 TABLE 1 Test data and calculating results of Examples 1-3 HPMA HEDP PAA m.sub.01 (mg) 4262.6 4262.6 4262.6 m.sub.02 (mg) 3994.2 3994.2 3994.2 m.sub.03 (mg) 4255.3 4255.3 4255.3 m.sub.01 (mg) 4266.0 4266.0 4266.0 m.sub.02 (mg) 3997.2 3997.2 3997.2 m.sub.03 (mg) 4258.5 4258.5 4258.5 m.sub.0 (mg) 3.2 3.2 3.2 m.sub.11 (mg) 4209.9 4309.9 4109.5 m.sub.12 (mg) 4033.1 4233.2 4333.1 m.sub.13 (mg) 4309.8 4109.8 4009.8 m.sub.11 (mg) 4211.8 4311.8 4111.8 m.sub.12 (mg) 4035.2 4235.0 4335.6 m.sub.13 (mg) 4311.8 4111.6 4011.9 m.sub.1 (mg) 2.0 1.8 2.3 .sub.01 (mg/L) 108.5 108.5 108.5 .sub.02 (mg/L) 108.7 108.7 108.7 .sub.03 (mg/L) 107.4 107.4 107.4 .sub.0 (mg/L) 108.2 108.2 108.2 .sub.11 (mg/L) 215.4 223.8 211.4 .sub.12 (mg/L) 215.8 224.1 210.7 .sub.13 (mg/L) 213.5 222.1 209.1 .sub.1 (mg/L) 214.9 223.3 210.4 static scale inhibition rate .sub.1 (%) 81.0 87.3 77.5 dynamic scale inhibition rate .sub.2 (%) 37.5 43.8 28.1 comprehensive scale inhibition rate (%) 59.3 65.6 52.8 Fix the three test pieces 3 in a first test hole 12, a second test hole 13, and a third test hole 15 by using stainless steel strips, respectively, for suspending the three test pieces 3 in the test solution. Fix a condenser 4 in a second fixing hole 14; fix a stirrer 2 in a first fixing hole 11, control a stirrer speed at 160 rpm; maintain the open vessel 1 inside a constant temperature heater 5 for 10 h; and take off the three test pieces 3, desiccate, and measure weight thereof represented by m.sub.11, m.sub.12, m.sub.13, respectively, as shown in Table 1. The constant temperature heater 5 herein is a constant temperature water bath, and a temperature thereof is controlled at 80 C.

(13) 4) Measurement of calcium ion concentration: Cool the test solution in the open vessel 1 to a room temperature; transfer the test solution and filter the test solution by using a middle speed quantitative filter paper; and add 25 mL of a filtrate to a 250 mL Erlenmeyer flask. Add 55 mL of distilled water, 5 mL of the potassium hydroxide solution prepared in step 2), and 0.1 g of calconcarboxylic acid into the Erlenmeyer flask to yield a mixture. Titrate the mixture in parallel for three times by using the EDTA standard solution obtained in step 2). Calculate calcium ion concentration represented by .sub.11, .sub.12/and .sub.13, respectively, as shown in Table 1.

(14) 5) Blank test: Repeat steps 1)-4) to conduct the blank test in which prepare a test solution without adding the scale inhibitor; measure weight of three test pieces 3 before the blank test represented by m.sub.01, m.sub.02, and m.sub.03; measure weight of the three test pieces 3 after the blank test represented by m.sub.01, m.sub.02, and m.sub.03; titrate calcium ion concentration of the test solution in parallel for three times; and calculate calcium ion concentration represented by .sub.01, .sub.02, and .sub.03, respectively.

(15) 6) Calculation of scale inhibition rate: a) Calculate a static scale inhibition rate .sub.1: define a stable calcium ion concentration of the test solution without adding the scale inhibitor as .sub.0; define a stable calcium ion concentration of the test solution in the presence of the scale inhibitor as .sub.1; .sub.0=(.sub.01+.sub.02+.sub.03)/3=108.2 mg/L, .sub.1=(.sub.11+.sub.12+.sub.13)/3=214.9 mg/L; and calculate the static inhibition rate .sub.1 according to the following formula:
.sub.1=(.sub.1.sub.0)/(240.sub.0)100%=81.0% b) Calculate a dynamic scale inhibition rate .sub.2: define an average increased weight of the test piece 3 in condition of not adding the scale inhibitor as m.sub.0; define an average increased weight of the test piece 3 in the presence of the scale inhibitor as m.sub.1; m.sub.0=(m.sub.01+m.sub.02+m.sub.03m.sub.01m.sub.02m.sub.03)/3=3.2 mg, m.sub.1=(m.sub.11+m.sub.12+m.sub.13m.sub.11m.sub.12m.sub.13)/3=2.0 mg; and calculate the dynamic scale inhibition rate .sub.2 according to the following formula:
.sub.2=(m.sub.0m.sub.1)/m.sub.0100%=37.5%; and c) Calculate a comprehensive scale inhibition rate according to the following formula:
=(.sub.1+.sub.2)/2100%=59.3%

EXAMPLE 2

(16) In this example, the performance of scale inhibition of 1-hydroxyethylidene-1, 1-diphosphonic acid (HEDP), provided by Nanjing Naco Water Treatment Technology Co., Ltd., was evaluated. A device and a method for evaluating HEDP for a circulating cooling water system are the same as those of Example 1, and test data and calculating results are shown in Table 1.

EXAMPLE 3

(17) In this example, the performance of scale inhibition of polyacrylic acid (PAA), provided by Nanjing Naco Water Treatment Technology Co., Ltd., was evaluated. A device and a method for evaluating PAA for a circulating cooling water system are the same as those of Example 1, and test data and calculating results are shown in Table 1.

(18) The device and the method for evaluating a scale inhibitor for a circulating cooling water system of the invention realizes a proper combination of a conventional static evaluation method and a dynamic evaluation method. The method of the invention is capable of reflecting the chelation, the dispersion, and the lattice distortion of the scale inhibitor, and fast evaluating the comprehensive performance of the scale inhibitor. The method of the invention has a simple operation and is timesaving, thereby providing an effective evaluating method for the development, selection, and combination of the scale inhibitors for the circulating cooling water system.

(19) While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.