CN106950145A - Suitable for the dynamic experiment method and apparatus of recirculating cooling water system pipeline scale - Google Patents

Abstract

The invention discloses a dynamic experiment method and device suitable for scaling of pipelines in a circulating cooling water system. A circulating water pump is used to extract a test water sample placed in a circulating cooling water tank of a constant temperature water tank, and then flows through a test piece tube with a metal test piece , and use a flowmeter to control the flow rate to simulate the working conditions of the pipe scaling in the circulating cooling water system. The present invention comprehensively studies the scaling behavior through the weight gain of the metal test piece, and organically combines the advantages of the traditional static method and the dynamic method. It is close to the actual working conditions, and it is convenient to study the fouling behavior. Compared with the traditional dynamic evaluation method, this method is not only simple to operate, but also has a wide range of applications. It also provides an effective and rapid method for evaluating the scaling behavior of circulating cooling water systems and provides The research on scaling and anti-scaling in circulating cooling water system provides a reference.

Description

A dynamic experimental method and device suitable for scaling of pipes in circulating cooling water systems

technical field

The invention belongs to the technical field of a scaling analysis method and device for circulating cooling water, and in particular relates to a dynamic experimental method and device suitable for scaling in a circulating cooling water system pipeline.

Background technique

Circulating cooling water is the main component of industrial water. At present, the water sources used in the circulating cooling water system mainly include groundwater, surface water and treated urban sewage. However, after the secondary biochemical treatment of urban sewage, the water quality is relatively simple, and still contains a large amount of inorganic ions and a small amount of organic matter. If it is reused In the circulating cooling water system, the cooling water will bring scaling problems to the system during the process of heat exchange and cooling and recycling. The direct consequence of fouling on the surface of the equipment is to reduce the working efficiency of the heat exchange system, affect industrial production in severe cases, and even paralyze the entire system. Adding scale inhibitors in the circulating cooling water system is an effective means to control system scaling. However, understanding the scaling process and trend of the circulating cooling water system is the premise to better solve the scaling problem. A lot of research focuses on the cause of scaling and the performance measurement of antiscalants. Some studies have also analyzed and determined some antiscalants and The effects of various ions in water on the scaling of circulating cooling water, but there are few studies on the scaling behavior of organic matter on circulating cooling water systems. It is undoubtedly of great significance to monitor and study the causes of scaling.

Scaling test technology is classified according to the monitoring means of deposits, including thermal methods and non-caloric fouling monitoring methods. Thermal methods can be divided into thermal resistance representation and temperature difference representation. Non-heat transfer dirt monitoring methods include direct weighing method, thickness measurement method, pressure drop measurement method, radioactive technology, time-lapse film method, and display method. Microphotography, electrolysis and chemical methods, etc. Fouling thermal resistance means that assuming that the presence of fouling on the heat transfer surface has negligible influence on the convective heat transfer coefficient between the wall and the fluid, the fouling thermal resistance of the heat transfer surface can be calculated by measuring the wall temperature and heat flow in the clean state and the fouling state measured indirectly. Direct weighing method: the fouling rate is expressed by mass flux, and the fouling rate is expressed according to the weight change before and after fouling within a period of time. At present, it is mostly used in laboratory simulation research, especially for the simulation research of the scaling induction period, which often uses this method to measure the scaling rate. Under the actual working conditions of circulating cooling water, the fouling process includes the crystallization process from free calcium ions to calcium carbonate, as well as the attachment and growth process of crystals on the surface of the equipment. These test methods are all static determination methods, which can only evaluate the former, but cannot effectively reflect the scaling behavior. The dynamic measurement method can better evaluate the fouling behavior and fouling process.

The dynamic method is to simulate the working conditions of the production site under the given conditions in the laboratory, including flow velocity, flow state, temperature, water quality, metal material and heat exchange intensity, etc. It is an ideal neutralization test method, which can It can well reflect the antiscalant performance under actual working conditions. However, the test time by this method is long (usually more than 10 days), and the equipment is complicated and expensive, and the results of scaling behavior evaluation cannot be obtained simply and quickly.

The traditional static method cannot reflect the process of scaling behavior, and at the same time, it has the disadvantage of uneven scaling in the static deposition method, while the dynamic method has the disadvantages of complicated equipment and long testing time.

Contents of the invention

The present invention provides a kind of dynamic experiment method and device applicable to the scaling of circulating cooling water system pipelines in order to overcome the defects existing in the prior art. The circulating water pump is used to extract the test water sample placed in the circulating cooling water tank of the constant temperature water tank, and then Flow through the test piece tube with the metal test piece, and use the flow meter to control the flow rate, so as to simulate the working conditions of the pipe scaling in the circulating cooling water system. Compared with the traditional dynamic evaluation method, this method is not only easy to operate, has a wide range of applications, but also provides effective and rapid evaluation. The method of scaling behavior in circulating cooling water system provides a reference for the research of scaling and anti-scaling in circulating cooling water system.

The present invention adopts following technical scheme for solving the above-mentioned technical problem, is applicable to the dynamic experiment method of pipeline fouling of circulating cooling water system, is characterized in that specific process is:

(1) Select the actual water in the industrial circulating cooling water system, natural water source water samples, industrial wastewater water samples or urban sewage water samples as the test water samples, analyze the test water samples before the test, and specifically analyze the scale-causing ion Ca ^{2 +} , Mg ²⁺ , CO ₃ ^2- and HCO ₃ ^- concentrations;

(2) Put the metal test piece in acetone and ultrasonically clean it for 5 minutes, then wash it with distilled water and dry it in a vacuum drying oven, number the metal test piece, weigh it, and put it into the test piece tube;

(3) Transfer the test water sample to the circulating cooling water tank, control the temperature of the constant temperature water tank to 50-90°C, and draw the test water sample in the circulating cooling water tank through the circulating water pump to flow into the test piece tube through the flowmeter to scour the metal test piece, and then Return to the circulating cooling water tank, the flow rate of the flow meter is controlled at 0.5-10L/min;

(4) Take out the metal test piece at 1h, 2h, 4h, 8h, 16h, 32h and 64h after the start of the experiment, put it in a vacuum drying oven, weigh it again after drying, and calculate the weight gain of the metal test piece before and after the experiment. Scale amount, through the scanning electron microscope and X-ray diffractometer to analyze the microscopic morphology and crystal form of the scaling on the surface of the metal test piece, so as to further analyze the scaling situation.

The dynamic experimental device suitable for scaling of circulating cooling water system pipes according to the present invention is characterized in that it includes a constant temperature water tank, a circulating cooling water tank, a cooling pipe, a test piece tube, a metal test piece, a flow meter and a circulating water pump, wherein the circulating cooling The water tank is installed in the constant temperature water tank. There are three fixing holes on the top of the circulating cooling water tank. One of the fixing holes is equipped with a condensation pipe, and the other two fixing holes are respectively equipped with silicone tubes. The silicone tubes are respectively connected to the circulating water pump. The liquid inlet is connected with the liquid outlet of the test piece tube, the liquid outlet of the circulating water pump is connected with the liquid inlet of the flowmeter through the silicone tube, and the liquid outlet of the flowmeter is connected with the liquid inlet of the test piece tube through the silicone tube.

Further preferably, the condensing tube is a glass tube, one end of the glass tube communicates with the air on the inner upper part of the circulating cooling water tank, the other end of the glass tube communicates with the outside atmosphere, the outer diameter of the glass tube is 3-6mm, and the length is 30mm. -40cm, for condensing water vapor.

Further preferably, the material of the metal test piece is 304 stainless steel or 316L stainless steel, the shape of the metal test piece is circular or rectangular, and the size of the metal test piece matches the inner diameter of the test piece tube.

Further preferably, the test piece tube is a transparent glass tube or a transparent plexiglass tube, the diameter of the test piece tube is 6-30 mm, and the length is 0.2-1 m.

Compared with the prior art, the present invention has the following beneficial effects: the present invention successfully solves the uneven fouling problem of the traditional static evaluation method, and realizes the organic combination of the traditional static evaluation method and the dynamic evaluation method. Compared with the traditional dynamic evaluation method The method is simple to operate and has a wide range of applications. It can not only effectively and conveniently evaluate the scaling behavior of circulating cooling water systems dynamically, but also provide a reference for the research on scaling and scale inhibition in circulating cooling water systems.

Description of drawings

Fig. 1 is a schematic structural view of a dynamic experimental device suitable for fouling of pipelines in a circulating cooling water system in the present invention.

In the figure: 1-constant temperature water tank, 2-circulating cooling water tank, 3-condensing pipe, 4-test piece tube, 5-metal test piece, 6-flow meter, 7-circulating water pump.

detailed description

In order to further elaborate the content of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention.

Example

Referring to Fig. 1, the dynamic experimental device applicable to the fouling of circulating cooling water system pipelines provided by the present invention includes a constant temperature water tank 1, a circulating cooling water tank 2, a condensation pipe 3, a test piece tube 4, a metal test piece 5, a flow meter 6 and The circulating water pump 7, wherein the circulating cooling water tank 2 is installed in the constant temperature water tank 1, and the top of the circulating cooling water tank 2 is provided with three fixing holes, one of which is equipped with a condensation pipe 3, and the other two fixing holes are respectively equipped with Silicone tube, one end of the silicone tube is inserted below the liquid level of the circulating cooling water tank 2 to test the water sample to prevent the sample from generating air bubbles, and the other end of the silicone tube is respectively connected to the liquid inlet of the circulating water pump 7 and the liquid outlet of the test piece tube 4 The liquid outlet of the circulating water pump 7 is connected with the liquid inlet of the flowmeter 6 through a silicone tube, and the liquid outlet of the flowmeter 6 is connected with the liquid inlet of the test piece tube 4 through a silicone tube.

The metal test piece 5 used in this embodiment is a 316L stainless steel test piece, provided by Sanhexing Metal Materials Co., Ltd., Longgang District, Shenzhen, with a size of 2×8×12mm. The 316L stainless steel test piece is placed horizontally in the test piece tube 4 , and the 316L stainless steel test piece is parallel to the flow direction of the test water sample; the test piece tube 4 used in this embodiment is a transparent plexiglass tube with a size of 12mm in outer diameter*1.5mm in wall thickness, which was produced by Bujixiong, Longgang District, Shenzhen Provided by Fengfa metal material firm; the circulating cooling water tank 2 used in this embodiment is a four-hole flat-bottomed beaker, which is processed by Yanzhibao Experimental Equipment Marketing Center, Qinhuai District, Nanjing; the constant temperature water tank 1 used in this embodiment That is, the constant temperature water bath is the HW.SY11-KP2 type water bath of Beijing Changfeng Instrument and Meter Company; the model of the circulating water pump 7 used in this embodiment is MP-6RZ, provided by Wenzhou Haoquan Pump Industry Co., Ltd. ; The model of the flow meter 6 used in this embodiment is LZM-15, provided by Yuyao Juyi Environmental Protection Equipment Co., Ltd.

In this example, the dynamic evaluation of the fouling behavior of the pipes in the circulating cooling water system is carried out. The test water samples are taken from the effluent of the secondary biochemical pool of Xiaoshangzhuang Sewage Treatment Plant in Xinxiang City. The specific operation steps of the dynamic experimental method applicable to the fouling of the pipes of the circulating cooling water system in this embodiment are as follows:

1. Prepare the metal test piece:

Place the metal test piece in acetone for ultrasonic cleaning for 5 minutes, after cleaning, place it in a vacuum desiccator for drying, and set aside;

2. Prepare water samples for testing:

Prepare concentrated water samples: Take 1000mL of test water samples in a 1000mL beaker and place them in a constant temperature water tank. The temperature of the constant temperature water tank is set at 55°C. Concentrate to 200mL to obtain a 5-fold concentrated water sample for use;

3. Fouling test:

Take 1000mL of the 5 times concentrated water sample obtained in step 2 and transfer it to the circulating cooling water tank, take 28 prepared metal test pieces, number them and weigh them as m ₁ , m ₂ , m ₃ ... m ₁₄ , and place them side by side horizontally Plug the fixed plug in the test piece tube, connect the device, and fix the condensing device in the fixed hole on the circulating cooling water tank, adjust the flow rate of the test water sample to 7L/min through the flow meter, and place the circulating cooling water tank in a constant temperature water tank In the experiment, take out two metal test pieces at 1h, 2h, 4h, 8h, 16h, 32h and 64h respectively and vacuum dry them, and call their masses M ₁ , M ₂ , M ₃ ... M ₁₄ , and the constant temperature water tank The temperature is controlled at 80°C;

4. Calculation of fouling amount:

Scaling test C _i =M _i -m _i , the result data of scaling amount is shown in Table 1.

Table 1 embodiment test data and calculation result statistical table

time (h) 1 2 4 8 16 32 64 Scaling (mg) 0.3 0.9 1.1 1.2 1.3 1.5 1.6

The invention successfully solves the uneven fouling of the traditional static evaluation method and realizes the organic combination of the traditional static evaluation method and the dynamic evaluation method. Compared with the traditional dynamic evaluation method, the method is simple to operate and has a wide application field. The convenient method for evaluating the scaling behavior of the circulating cooling water system also provides a reference for the research on scaling and anti-scaling of the circulating cooling water system.

Claims (5)

1. A dynamic experimental method applicable to pipe scaling in circulating cooling water systems, characterized in that the specific process is: (1) Select the actual water in the industrial circulating cooling water system, natural water source water samples, industrial wastewater water samples or urban sewage water samples as the test water samples, analyze the test water samples before the test, and specifically analyze the scale-causing ion Ca ^{2 +} , Mg ²⁺ , CO ₃ ^2- and HCO ₃ ^- concentrations; (2) Put the metal test piece in acetone and ultrasonically clean it for 5 minutes, then wash it with distilled water and dry it in a vacuum drying oven, number the metal test piece, weigh it, and put it into the test piece tube; (3) Transfer the test water sample to the circulating cooling water tank, control the temperature of the constant temperature water tank to 50-90°C, and draw the test water sample in the circulating cooling water tank through the circulating water pump to flow into the test piece tube through the flowmeter to scour the metal test piece, and then Return to the circulating cooling water tank, the flow rate of the flow meter is controlled at 0.5-10L/min; (4) Take out the metal test piece at 1h, 2h, 4h, 8h, 16h, 32h and 64h after the start of the experiment, put it in a vacuum drying oven, weigh it again after drying, and calculate the weight gain of the metal test piece before and after the experiment. Scale amount, through the scanning electron microscope and X-ray diffractometer to analyze the microscopic morphology and crystal form of the scaling on the surface of the metal test piece, so as to further analyze the scaling situation. 2. A dynamic experimental device suitable for scaling of pipes in circulating cooling water systems, characterized in that it includes constant temperature water tanks, circulating cooling water tanks, cooling pipes, test piece tubes, metal test pieces, flow meters and circulating water pumps, wherein the circulating cooling water tanks are installed in In the constant temperature water tank, there are three fixing holes on the top of the circulating cooling water tank, one of which is equipped with a condensation pipe, and the other two fixing holes are respectively equipped with silicone tubes, which are respectively connected to the liquid inlet of the circulating water pump. It is connected with the liquid outlet of the test piece tube, the liquid outlet of the circulating water pump is connected with the liquid inlet of the flowmeter through the silicone tube, and the liquid outlet of the flowmeter is connected with the liquid inlet of the test piece tube through the silicone tube. 3. The dynamic experimental device suitable for fouling of circulating cooling water system pipes according to claim 2, characterized in that: the condensation tube is a glass tube, and one end of the glass tube communicates with the air on the inner upper part of the circulating cooling water tank , the other end of the glass tube communicates with the outside atmosphere, the outer diameter of the glass tube is 3-6mm, and the length is 30-40cm, which is used to condense water vapor. 4. The dynamic experimental device suitable for scaling of circulating cooling water system pipes according to claim 2, characterized in that: the material of the metal test piece is 304 stainless steel or 316L stainless steel, and the shape of the metal test piece is circular Or rectangular, and the size of the metal test piece matches the inner diameter of the test piece tube. 5. The dynamic experimental device suitable for fouling of circulating cooling water system pipes according to claim 2, characterized in that: the test piece tube is a transparent glass tube or a transparent plexiglass tube, and the diameter of the test piece tube is 6-30mm, length 0.2-1m.