Device and method for detecting crystallization point of industrial naphthalene

Abstract

The invention belongs to the technical field of naphthalene crystallization detection, and particularly relates to an industrial naphthalene crystallization point detection device and a method thereof.The industrial naphthalene crystallization point detection device comprises a test tube, a water bath pool, a high-precision thermometer and a shaking mechanism, and the test tube is used for containing industrial naphthalene; the water bath pool is used for stably cooling the test tube; the high-precision thermometer is used for detecting the temperature of industrial naphthalene; the shaking mechanism comprises a fixing plate, a motor, a rotating shaft and a poke rod, the fixing plate is fixedly connected with the water bath pool, the motor is fixedly connected with the fixing plate, a shaft of the motor is fixedly connected with the rotating shaft, the poke rod is fixedly connected with the rotating shaft, the poke rod is matched with the test tube, and the test tube is rotationally connected with the fixing plate. According to the scheme, the problem of inaccurate measurement of a high-precision thermometer caused by local supercooling or overheating during cooling crystallization is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of naphthalene crystallization detection, and particularly relates to an industrial naphthalene crystallization point detection device and a method thereof. Background Art

[0002] Naphthalene is a polycyclic aromatic hydrocarbon widely used in dyes, pharmaceuticals, pesticides, and other fields. It is also an important raw material for the production of phthalic anhydride. A key physical property of naphthalene is its crystallization point, which refers to the temperature at which a pure substance transitions from liquid to solid. For industrial naphthalene, the crystallization point can be used to assess its purity, as the presence of impurities can lower the crystallization point.

[0003] At present, the existing announcement number is CN209911263U, which is a refined naphthalene crystallization point detection device, including a water bath and a thermometer, and also including a support platform, a first fixed frame and a heating and heat preservation device, wherein the heating and heat preservation device is fixed above the water bath by the first fixed frame, and the thermometer is movably placed in the heating and heat preservation device; the utility model utilizes a preheating thermometer, eliminating the need to constantly remove the crystallized solid on the thermometer during the frequent testing of high-temperature liquid naphthalene, reducing the loss of the precision thermometer, and achieving fast and convenient measurement; the use of this device not only shortens the analysis time, but also reduces costs and saves energy.

[0004] But there is also a problem: the device does not shake during cooling and crystallization, which can easily cause uneven temperature, local overcooling or overheating, making the high-precision thermometer's measurement inaccurate. Summary of the Invention

[0005] The invention provides an industrial naphthalene crystallization point detection device, which is used to solve the problem of inaccurate measurement of a high-precision thermometer caused by local overcooling or overheating during cooling crystallization.

[0006] In order to solve this problem, this solution provides an industrial naphthalene crystallization point detection device, comprising: Test tube: used to hold industrial naphthalene; Water bath: used to stably cool the test tube; High-precision thermometer: used to detect the temperature of industrial naphthalene; Rocking mechanism: The rocking mechanism includes a fixed plate, a motor, a rotating shaft and a toggle rod. The fixed plate is fixedly connected to the water bath, the motor is fixedly connected to the fixed plate, the shaft of the motor is fixedly connected to the rotating shaft, the toggle rod is fixedly connected to the rotating shaft, the toggle rod cooperates with the test tube, and the test tube is rotatably connected to the fixed plate.

[0007] The principle of this solution is that the water bath is used to provide a stable temperature. The operator pours superheated industrial naphthalene into the test tube, places a preheated high-precision thermometer into the test tube, and then places the test tube into the water bath for cooling.

[0008] After the motor is started, the toggle rod is driven to perform periodic motion through the rotating shaft, and the toggle rod pushes the test tube to swing back and forth on its rotating connection point.

[0009] The benefits of this solution are: 1. This mechanical shaking allows the sample to flow continuously during the cooling process, breaking local temperature gradients and promoting even heat distribution. Furthermore, shaking can disturb the liquid state, introducing tiny bubbles or perturbations that serve as crystallization nuclei, thus avoiding "supercooling." 2. The shaking frequency and amplitude can be precisely controlled by a motor, facilitating standardized operating procedures.

[0010] Furthermore, the device includes a sealant, through which the high-precision thermometer is positioned within the test tube. Once cured, the sealant forms a stable barrier, preventing external air, moisture, and impurities from entering the test tube. This sealant prevents the sample from coming into contact with the outside world and potentially causing oxidation, moisture absorption, or contamination, which is particularly important for volatile or sensitive samples. It also prevents liquid leakage due to volume expansion during cooling, ensuring experimental safety.

[0011] Furthermore, it also includes an air storage cylinder and a connecting pipe, one end of the connecting pipe is connected to the air storage cylinder, and the other end is connected to the test pipe.

[0012] When the industrial naphthalene sample is first added, the huge heat will cause the internal gas to expand. During the cooling process, the volume of the industrial naphthalene sample will shrink, resulting in negative pressure inside the test tube. If not handled, it may easily cause the test tube or sealant to rupture.

[0013] The gas storage cylinder acts as a "buffer gas chamber" that can absorb gas volume fluctuations caused by temperature changes and keep the entire system in a relatively stable pressure state.

[0014] If the gas storage cylinder is pre-filled with inert gas (such as nitrogen or argon), it can provide a protective atmosphere for the test tube during the experiment to prevent the sample from oxidation or moisture absorption.

[0015] Furthermore, the gas storage cylinder includes a cylinder body, a push rod and a piston, the cylinder body is fixedly connected to the fixed plate, the piston is slidingly and sealingly connected to the cylinder body, one end of the push rod is fixedly connected to the piston, and the other end is fixedly connected to the motor, and the motor is slidingly connected to the fixed plate.

[0016] When the industrial naphthalene sample is first injected into the test tube, the high temperature causes the gas inside to expand, pushing the piston downward. This downward movement of the piston simultaneously drives the push rod downward, which in turn drives the motor connected to it downward along the fixed plate. The downward movement of the motor lowers the lever, allowing it to move the test tube through a wider angle during rotation, resulting in a larger swing amplitude, which facilitates rapid and even heat dissipation from the sample.

[0017] As the water bath continues to cool the test tube, the sample temperature gradually decreases, and the gas inside the test tube contracts, causing the piston to move upward. This upward movement of the piston drives the push rod upward, which in turn drives the motor upward along the slide rail. The upward movement of the motor raises the position of the lever, reducing the angle that can be applied when moving the test tube, and thus gradually reducing the test tube's swing amplitude.

[0018] When the sample temperature approaches the crystallization point, the position of the toggle rod has risen to the point where it no longer touches the test tube. At this time, the test tube stops swinging, avoiding the interference of violent disturbances on the crystal formation process and helping to accurately determine the start time of crystallization.

[0019] This mechanism uses the change in gas volume caused by changes in sample temperature as a feedback signal to drive the piston, which in turn moves the toggle lever up and down. This allows for dynamic adjustment of the test tube's swing amplitude from large to small, or even to a complete stop, without the need for manual intervention or an additional control system. Furthermore, during the pre-crystallization phase, larger swings promote uniform cooling of the sample, minimizing localized overcooling. As the crystallization point approaches, the swing is reduced or even stopped to prevent disturbances that could affect the crystal nucleation process, ensuring more accurate and reliable observations.

[0020] Furthermore, it also includes a shaking plate, and the test tube and the fixed plate are rotatably connected through the shaking plate, and the test tube and the shaking plate are detachably fixedly connected.

[0021] The test tube is detachably fixed to the rocking plate. A pivoting connection between the rocking plate and the fixed plate allows the test tube to oscillate periodically under external power. To change samples or clean the test tube, simply release the detachable connection and the tube can be quickly removed without disassembling the entire rocking mechanism. The detachable structure of the test tube facilitates quick replacement, cleaning, and maintenance, significantly improving experimental efficiency.

[0022] Furthermore, the device further comprises a timer, which is used to record the duration of the maximum temperature of industrial naphthalene.

[0023] The timer is used to record the observed temperature. When the temperature reaches the highest point and stays at the highest temperature for more than 1 minute, this temperature is the crystallization point and this temperature is recorded.

[0024] Furthermore, it also includes a spring, one end of which is fixedly connected to the piston, and the other end of which is fixedly connected to the cylinder body.

[0025] The presence of the spring makes the system more stable in the face of volume changes caused by temperature changes, reduces violent pressure fluctuations, and prevents seal failure or container rupture.

[0026] This solution also provides a method for detecting the crystallization point of industrial naphthalene, comprising the following steps: Step S10: weighing a sample and placing it in a molten naphthalene test tube for melting and dehydration; Step S20: Pour the molten sample quickly into a test tube that has been preheated to a set temperature, insert a high-precision thermometer, and seal it; Step S30: Shake the test tube and check the temperature of the high-precision thermometer at regular intervals. When crystallization occurs and the temperature begins to rise, shake it again and then stop shaking. Step S40: Let the mixture stand and observe the temperature. When the temperature reaches the highest point and stays at the highest temperature for more than 1 minute, this temperature is the crystallization point and this temperature is recorded.

[0027] The beneficial effects of this solution are: 1. Through melting dehydration and preheating treatment, the purity of the sample and the consistency of the initial conditions are ensured.

[0028] 2. The combination of periodic shaking and temperature monitoring not only promotes uniform cooling of the sample, but also improves the accuracy of crystallization point judgment.

[0029] 3. Specific judgment criteria are stipulated (such as temperature recovery and staying at the highest temperature for more than 1 minute), so that the experimental results have high credibility and repeatability.

[0030] Furthermore, in step S30, the measuring instrument is shaken at an angle of 10-45° and an amplitude of 20-100 mm, 60-70 times per minute, with the shaking angle and amplitude gradually decreasing over time. By setting dynamically changing shaking parameters (angle and amplitude decreasing over time), the present invention achieves precise control of the disturbance intensity during the industrial naphthalene crystallization process. This method not only improves the accuracy and repeatability of crystallization point measurements but also enhances the system's adaptability and automation capabilities, possessing significant technological advancement significance and practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a structural diagram of an industrial naphthalene crystallization point detection device. Figure 2 This is a state diagram of an industrial naphthalene crystallization point detection device when it is just poured. Figure 3 This is a state diagram of an industrial naphthalene crystallization point detection device after cooling for a period of time.

[0032] The figure marks in the specification include: 1. water bath; 2. shaking plate; 3. test tube; 4. high-precision thermometer; 5. connecting pipe; 6. sealant; 7. toggle rod; 8. rotating shaft; 9. motor; 10. placement plate; 11. push rod; 12. piston; 13. cylinder; 14. spring; 15. fixing plate. DETAILED DESCRIPTION

[0033] Basically as attached Figure 1 As shown: The present invention provides an industrial naphthalene crystallization point detection device, comprising the following main components: Test tube 3: used to contain the industrial naphthalene sample to be tested.

[0034] The test tube 3 is rotatably connected to the fixed plate 15 via the shaking plate 2 and is fixedly connected to the shaking plate 2 in a detachable manner (such as a snap or magnetic connection).

[0035] The test tube 3 is made of special glass or quartz glass that is resistant to low temperatures, has good thermal conductivity, and is highly transparent, so as to facilitate observation of changes in the sample state.

[0036] Water bath 1: provides a stable and controllable cooling environment for the test tube 3.

[0037] The water bath 1 is fixedly arranged at the bottom of the device, and the test tube 3 is placed inside it for cooling.

[0038] The inner tank of the water bath 1 is made of stainless steel or corrosion-resistant engineering plastics, which has good thermal conductivity and chemical stability.

[0039] High-precision thermometer 4: Real-time detection of temperature changes of industrial naphthalene samples.

[0040] The high-precision thermometer 4 is inserted into the test tube 3 and sealed with the test tube 3 by a sealant 6 to prevent gas leakage or sample contamination.

[0041] The high-precision thermometer 4 uses a platinum resistance temperature sensor (Pt100) or a digital high-precision probe with fast response speed and high measurement accuracy.

[0042] The rocking mechanism includes a fixed plate 15, a motor 9, a rotating shaft 8, and a toggle lever 7. The fixed plate 15 serves as the basic support platform for the entire rocking mechanism and is fixedly connected to the water bath 1. A placement plate 10 is provided on the fixed plate 15, and the placement plate 10 is arranged perpendicular to the fixed plate 15. The motor 9 is mounted on the placement plate 10 to provide power output. The rotating shaft 8 is rigidly connected to the output shaft of the motor 9. The toggle lever 7 is fixed to the rotating shaft 8 and rotates synchronously with it. The test tube 3 is rotationally connected to the fixed plate 15 through the rocking plate 2. The toggle lever 7 is used to toggle the rocking plate 2 to rotate the test tube 3.

[0043] Sealant 6 seals the gap between high-precision thermometer 4 and test tube 3. This sealant prevents external air and moisture from entering test tube 3, thus preventing sample oxidation, moisture absorption, or volatilization. Sealant 6 is made of high- and low-temperature-resistant silicone or epoxy resin, offering excellent airtightness and durability.

[0044] The air storage cylinder consists of a cylinder body 13, a piston 12, and a push rod 11. Cylinder body 13 is fixedly connected to the placement plate 10 and is located above the motor 9. The piston 12 is in a sliding, sealed connection with the cylinder body 13. Push rod 11 is fixedly connected to piston 12 at one end and to the motor 9 at the other end, located above the motor 9. The motor 9 is vertically slidably connected to the placement plate 10 and can move up and down along the track.

[0045] One end of the spring 14 is fixedly connected to the piston 12, and the other end is fixedly connected to the cylinder body 13. The spring 14 is made of stainless steel or alloy steel, which has good elasticity and corrosion resistance. The connecting pipe 5 connects the gas storage cylinder and the test pipe 3 so that gas can flow between the two.

[0046] The timer records the duration of industrial naphthalene at the highest temperature, assisting in determining the start time of crystallization and ensuring the consistency and accuracy of the experimental data.

[0047] As attached Figure 1-3 As shown: During the specific operation, after the industrial naphthalene sample is injected into the test tube 3, the internal gas expands due to the high temperature, pushing the piston 12 downward, and the piston 12 drives the push rod 11 and the motor 9 to move downward, so that the position of the toggle rod 7 is lowered. After the motor 9 is started, the toggle rod 7 is driven to perform periodic motion via the rotating shaft 8, and the toggle rod 7 pushes the shaking plate 2 to swing back and forth on its rotation connection point. The toggle tube toggles the test tube 3 to generate a large swing angle.

[0048] As the sample gradually cools, the gas in the test tube 3 contracts, and the piston 12 moves back under the action of the spring 14 and the air pressure difference. The push rod 11 drives the motor 9 to move upward, the position of the toggle rod 7 rises, and the toggle angle decreases, eventually staggering the test tube 3 to stop it from swinging.

[0049] Throughout the process, the shaking frequency and amplitude decrease over time, starting with an initial 45° angle and 100mm amplitude, gradually decreasing to within 10° and below 20mm. When the sample temperature rises and remains at its highest point for more than one minute, it is considered the crystallization point, and a timer records this temperature. The entire system maintains airtightness through sealant 6, an air reservoir, and other structures to prevent sample contamination or loss.

[0050] The beneficial effects of this solution are as follows: 1. This mechanical shaking allows the sample to flow continuously during the cooling process, breaking local temperature gradients and promoting even heat distribution. Furthermore, the shaking can disturb the liquid state, introducing tiny bubbles or disturbance points that serve as crystallization nuclei, thus avoiding "supercooling." 2. The shaking frequency and amplitude can be precisely controlled by motor 9, facilitating standardized operating procedures. 3. The sealant 6 prevents the sample from coming into contact with the outside world and potentially causing oxidation, moisture absorption, or contamination, which is particularly important for volatile or sensitive samples. It also prevents liquid leakage due to volume expansion during the cooling process, ensuring experimental safety. 4. The gas cylinder acts as a "buffer chamber," absorbing gas volume fluctuations caused by temperature changes and maintaining a relatively stable pressure state for the entire system. The gas cylinder is pre-filled with an inert gas (such as nitrogen or argon) to provide a protective atmosphere for the test tube 3 during the experiment, preventing oxidation or moisture absorption of the sample. 5. This mechanism uses the change in gas volume caused by changes in sample temperature as a feedback signal to drive the piston 12 to move, driving the toggle rod 7 to move up and down. It can achieve dynamic adjustment of the swing amplitude of the test tube 3 from large to small, or even stop completely, without manual intervention or additional control system.

[0051] This scheme also provides a method for detecting the crystallization point of industrial naphthalene. The operator weighs 30g~40g of the sample and places it in a molten naphthalene test tube. Then, the sample is completely melted, and 2g of anhydrous copper sulfate is weighed and added (dehydrated in the molten naphthalene test tube, and dehydrated for 5 minutes. Note: If the entire sample turns blue after adding anhydrous copper sulfate, more anhydrous copper sulfate should be added for dehydration until the sample does not change color after adding anhydrous copper sulfate).

[0052] Then quickly pour the molten sample into the test tube 3 which has been preheated to 90℃ in the water bath 1, so that the sample reaches the scale line of the test tube 3, and immediately plug it with a cork equipped with a precision thermometer (the thermometer is preheated to 80℃~85℃), and insert the precision thermometer to 20mm from the bottom of the naphthalene crystallization point tester.

[0053] Hold the crystallization point tester at 45° to the horizontal with an amplitude of 100 mm, shake the tester 60 to 70 times per minute, check the temperature on the precision thermometer every 0.5 min, and gradually lower the temperature. When crystallization appears and the temperature begins to rise, shake it once more and then stop shaking. Let it stand and observe the temperature.

[0054] When the temperature reaches its highest point and remains at that highest point for more than 1 minute, that temperature is the crystallization point. Read this temperature and estimate it to 0.01°C. At the same time, record the temperature near the middle of the exposed part of the mercury column of the precision thermometer. If the temperature rises or returns to the highest temperature for less than 1 minute, the test is invalid and needs to be repeated.

[0055] The beneficial effects of this solution are: 1. Through melting dehydration and preheating treatment, the purity of the sample and the consistency of the initial conditions are ensured.

[0056] 2. The combination of periodic shaking and temperature monitoring not only promotes uniform cooling of the sample, but also improves the accuracy of crystallization point judgment.

[0057] 3. Specific judgment criteria are stipulated (such as temperature recovery and staying at the highest temperature for more than 1 minute), so that the experimental results have high credibility and repeatability.

[0058] The above is only an embodiment of the present invention, and the common knowledge such as the specific structure and characteristics of the scheme is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. An industrial naphthalene crystallization point detection device, comprising: Test tube (3): used to contain industrial naphthalene; Water bath (1): used to stably cool the test tube (3); High-precision thermometer (4): used to detect the temperature of industrial naphthalene; It is characterized by further comprising: The shaking mechanism comprises a fixed plate (15), a motor (9), a rotating shaft (8) and a toggle lever (7), wherein the fixed plate (15) is fixedly connected to the water bath (1), the motor (9) is fixedly connected to the fixed plate (15), the shaft of the motor (9) is fixedly connected to the rotating shaft (8), the toggle lever (7) is fixedly connected to the rotating shaft (8), the toggle lever (7) is matched with the test tube (3), and the test tube (3) is rotationally connected to the fixed plate (15).

2. A device for detecting the crystallization point of industrial naphthalene according to claim 1, characterized in that, It also includes a sealant (6), and the high-precision thermometer (4) is located inside the test tube (3) through the sealant (6).

3. A device for detecting the crystallization point of industrial naphthalene according to claim 2, characterized in that, It also includes an air storage cylinder and a connecting pipe (5), one end of the connecting pipe (5) is connected to the air storage cylinder, and the other end is connected to the test pipe (3).

4. A device for detecting the crystallization point of industrial naphthalene according to claim 3, characterized in that, The gas storage cylinder comprises a cylinder body (13), a push rod (11) and a piston (12); the cylinder body (13) is fixedly connected to a fixed plate (15); the piston (12) is slidingly and sealingly connected to the cylinder body (13); one end of the push rod (11) is fixedly connected to the piston (12) and the other end is fixedly connected to the motor (9); and the motor (9) is slidingly connected to the fixed plate (15).

5. An industrial naphthalene crystallization point detection device according to claim 1, characterized in that, It also includes a shaking plate (2), the test tube (3) and the fixed plate (15) are rotatably connected via the shaking plate (2), and the test tube (3) and the shaking plate (2) are detachably fixedly connected.

6. An industrial naphthalene crystallization point detection device according to claim 1, characterized in that, The invention also comprises a timer, which is used for recording the duration of the maximum temperature of the industrial naphthalene.

7. An industrial naphthalene crystallization point detection device according to claim 4, characterized in that, It also includes a spring (14), one end of which is fixedly connected to the piston (12) and the other end of which is fixedly connected to the cylinder (13).

8. A method for detecting the crystallization point of industrial naphthalene, characterized in that: The following steps are involved: step S10: Weigh the sample and place it in a molten naphthalene test tube for melting and dehydration; Step S20: quickly pour the molten sample into the test tube (3) that has been preheated to the set temperature, insert a high-precision thermometer (4), and seal it; Step S30: Shake the test tube (3) and check the temperature of the high-precision thermometer (4) at regular intervals. When crystallization occurs and the temperature begins to rise, shake the tube once more and then stop shaking. Step S40: Let the mixture stand and observe the temperature. When the temperature reaches the highest point and stays at the highest temperature for more than 1 minute, this temperature is the crystallization point and this temperature is recorded.

9. A method for detecting the crystallization point of industrial naphthalene according to claim 8, characterized in that, In step S30, the shaking angle is 10-45°, the amplitude is 20-100 mm, the measuring instrument is shaken 60 to 70 times per minute, and the shaking angle and amplitude gradually decrease over time.

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