CN105664816B - Ultrasonic equipment based on amplitude controlling is used for the three-wave-length method of chemical plant installations - Google Patents

Abstract

The invention relates to the application field of ultrasonic equipment, and aims to provide a three-step method for applying an ultrasonic equipment based on amplitude control to a chemical plant. The method is mainly carried out in three steps: first, calibrate the experimental-level small-scale test equipment, and draw the amplitude curve in the small-scale production; then manufacture and verify the pilot-scale ultrasonic equipment; finally, manufacture and apply the ultrasonic equipment for industrial production. The invention can accurately measure the ultrasonic intensity, make the experimental results comparable, and can reproduce the experimental data repeatedly. Controlling the amplitude of the ultrasonic equipment can guide the design of the pilot equipment, ensure that the pilot equipment can reproduce the experimental results of the small equipment repeatedly, and provide a solid foundation for the design of the final production line. Solve the use of standardized processes and strict data to guide the perfect application of ultrasonic equipment in chemical production equipment. Guaranteed not to take detours, so that the experimental results in the laboratory can be accurately reproduced in the large-scale production line.

Description

A Three-Step Approach to Using Amplitude Control-Based Ultrasonic Devices in Chemical Plants

technical field

The invention relates to the application field of ultrasonic equipment, in particular to a three-step method for applying the ultrasonic equipment based on amplitude control to chemical equipment.

Background technique

Ultrasound is used in chemical engineering, biology and other processes, and has been more and more widely used. This is mainly based on ultrasonic cavitation. Ultrasonic cavitation refers to the dynamic process of growth and collapse of micro-air nuclei cavitation bubbles existing in liquids that vibrate under the action of sound waves, and when the sound pressure reaches a certain value. When ultrasonic waves act on liquids, a large number of small air bubbles can be generated. One reason is that a negative pressure is formed due to the local tensile stress in the liquid, and the reduction of the pressure makes the gas originally dissolved in the liquid supersaturated, and escapes from the liquid to become small bubbles. Another reason is that the strong tensile stress "tears" the liquid into a cavity, which is called cavitation.

The cavitation threshold is the lowest sound intensity or sound pressure amplitude at which cavitation occurs in a liquid medium. Negative pressure can only occur when the amplitude of the alternating sound pressure is greater than the static pressure. Cavitation occurs only when the negative pressure exceeds the viscosity of the liquid medium. The cavitation threshold varies with different liquid media. For the same liquid medium, different temperature, pressure, radius of cavitation nucleus and gas content, the cavitation threshold is also different. In general, the lower the gas content of the liquid medium, the higher the cavitation threshold. The cavitation threshold is also related to the viscosity of the liquid medium, the greater the viscosity of the liquid medium, the higher the cavitation threshold. The cavitation threshold is closely related to the frequency of ultrasound, the higher the frequency of ultrasound, the higher the cavitation threshold. The higher the frequency of ultrasonic waves, the harder it is to cause cavitation. To produce cavitation, the intensity of ultrasonic waves must be increased.

Ultrasound is widely used in various fields, that is, the application of its cavitation and its cavitation accompanied by mechanical effects, thermal effects, chemical effects, biological effects and so on. The application of mechanical effects and chemical effects, the former is mainly manifested in the increase of the heterogeneous reaction interface; the latter is mainly due to the high temperature and high pressure generated in the cavitation process, which leads to the decomposition of polymers, the breaking of chemical bonds and the generation of free radicals. Processes using mechanical effects include adsorption, crystallization, electrochemistry, heterogeneous chemical reactions, filtration, and ultrasonic cleaning, etc. Processes using chemical effects mainly include organic degradation, polymer chemical reactions, and other free radical reactions.

The most important factor affecting ultrasonic cavitation is the ultrasonic intensity. Others such as liquid medium, temperature, pressure, gas content, etc., also have influence. Obviously, the liquid medium, temperature, pressure, gas content, etc., are well known to the operator and can be accurately measured and controlled. The ultrasonic intensity is relatively unfamiliar to the operator, and it is difficult to accurately measure and control it. The production units of ultrasonic instruments or equipment, in order to facilitate the operator's understanding and control, or to avoid the precise measurement and control of ultrasonic intensity, or the concept itself is not clear enough. Intentionally or unintentionally, the power index of the ultrasonic equipment is used instead.

Ultrasonic intensity refers to the ultrasonic power per unit area. That is, when the ultrasonic transmitter emits ultrasonic waves into the liquid, the power per unit area at the emitting surface. Of course, the farther away from the emitting surface, the lower the ultrasonic intensity (due to the absorption of liquid and the diffusion of power). The power of ultrasonic equipment refers to the total ultrasonic power emitted by the transmitter into the liquid. It is the integral of the ultrasonic intensity and the area of the emitter. Clearly, the two parameters are related, but not simply correlated. The consequence of confusing these two concepts is that the experimental results lack comparability and repeatability. Or, after the results were obtained in the small test, the expansion of the pilot test got into trouble, which made it impossible to determine how to choose ultrasonic equipment in the actual production line of the chemical production device.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a three-step method for applying the ultrasonic equipment based on amplitude control to chemical equipment.

For solving technical problem, solution of the present invention is:

A three-step method for using amplitude-controlled ultrasonic devices in chemical plants is provided. The method is mainly divided into three steps: the first step is to calibrate the experimental-level small-scale test equipment, and draw the amplitude curve in the small-scale production; the second step is to manufacture and verify the pilot-scale ultrasonic equipment; the third step is to Fabrication and application of industrially produced ultrasonic equipment.

Specifically, the present invention comprises the following steps:

(1) Calibrate the ultrasonic equipment

For the calibration of ultrasonic equipment with power, power percentage or power absolute value as the adjustment scale mark, change the value with amplitude as the unit of measurement as the adjustment scale mark;

(2) Draw the amplitude curve during the small test chemical reaction

Apply the calibrated ultrasonic equipment to the small test experiment of corresponding chemical production, adjust the amplitude of the ultrasonic equipment step by step during the experiment, and observe the experimental effect at the same time; through multiple sets of experimental data, sort out the relationship between the experimental effect and the amplitude of the ultrasonic equipment Corresponding relationship, draw the relationship curve between the amplitude and the experimental effect;

The experimental effect refers to the specific purpose that the chemical reaction process needs to achieve;

(3) Manufacture of equipment for pilot chemical reaction process

The amplitude data corresponding to the best experimental effect is used as the optimal amplitude value for the pilot test, and the design and manufacture of the ultrasonic equipment are completed accordingly; the power range of the ultrasonic equipment is determined according to the amount and nature of the reaction material, and the pilot test It can be successfully completed and the power of the equipment is not overloaded as the basis;

(4) Verify the equipment used for the pilot chemical reaction process

Guided by the relationship curve between the amplitude and the experimental effect in the chemical reaction process of the small test, the experiment is carried out on the equipment of the chemical reaction process of the pilot test; the amplitude of the ultrasonic equipment is adjusted step by step during the experiment, and the reaction conditions are adjusted according to the needs of the reaction. The adjustment is based on the test results that can be repeated in the small test, and the power of the equipment is not overloaded;

(5) Application of ultrasonic equipment in chemical production equipment

According to the actual needs of chemical production, the ultrasonic equipment that has been verified and finalized by the pilot test is applied to the chemical production device in a series connection of monomers to meet the requirements of flow rate or ultrasonic action time; or, it is applied in a parallel connection of monomers In chemical production equipment, it meets the requirements of design output.

In the present invention, the ultrasonic device is equipped with an ultrasonic driving power source controlled by a constant amplitude, which can provide at least a terminal output amplitude of 100 microns under the condition of 20 kHz, and the amplitude is adjustable.

In the present invention, the ultrasonic equipment used in small-scale experiments or pilot-scale experiments has a rod-like emitter with a variable cross-section.

In the present invention, the amplitude amplification factor is marked on the transmitting head or the horn of the ultrasonic device.

In the present invention, the horn or the emitting head can be disassembled and replaced, and multiple combined connections can be realized.

In the present invention, the experimental effect refers to the specific purpose that needs to be achieved in the chemical reaction process of the small test or pilot test; for example, realize dispersion, realize emulsification, complete chemical reaction, and so on. The introduction of ultrasonic waves can achieve the purpose of shortening the time of the chemical process, increasing the yield, and better dispersion, and these are the chemical reaction effects accurately measured by various methods.

Take graphene heat dissipation coating as an example. When there is no ultrasonic effect, it needs to be stirred for 2 hours to achieve the dispersion and homogenization effect, that is, the heat dissipation characteristics meet the requirements. When the ultrasonic amplitude of 20kHz is greater than 15 microns, the stirring time is shortened. This is called the experimental effect. The best experimental effect refers to: as the ultrasonic amplitude increases, the corresponding stirring time also decreases, and the heat dissipation effect can still meet the requirements. When the ultrasonic amplitude is greater than 70 μm, the reduction of the stirring time almost stagnates. Then, between the ultrasonic amplitude of 15 microns and 70 microns, the point with the greatest marginal effect on reducing the stirring time is the best experimental effect.

Compared with the prior art, the beneficial effects of the present invention are:

1. The present invention can accurately measure the ultrasonic intensity, make the experimental results comparable, and can reproduce the experimental data repeatedly.

2. By controlling the amplitude of the ultrasonic equipment, it can guide the design of the pilot test equipment, ensure that the pilot test equipment can reproduce the experimental results of the small test equipment repeatedly, and provide a solid foundation for the design of the final production line.

3. The present invention solves the problem of using standard flow and strict data to guide the perfect application of ultrasonic equipment in chemical production equipment. Starting from the small test in the laboratory, to the pilot test, and finally to the application in the chemical production equipment, it is guaranteed that there will be no detours, so that the experimental results in the laboratory can be accurately reproduced in the large-scale production line.

detailed description

The implementation process of the present invention will be described in detail below in conjunction with specific implementation examples.

(1) Calibrate the ultrasonic equipment

When other conditions are fixed, the intensity of ultrasonic emission is determined by the amplitude of the ultrasonic emitting head. Generally speaking, the usual high-power ultrasonic focused transmitters vibrate in a longitudinal manner. Then, the ultrasonic intensity is determined by the amplitude of the longitudinal vibration. As long as the longitudinal amplitude of the ultrasonic emitting head is determined, the intensity of the ultrasonic emission is also determined. In other words, the key to the problem here is the amplitude of the ultrasonic transmitter. As long as the amplitude is controlled, the emission intensity of the ultrasonic wave is also strictly controlled. This not only avoids the difficulty of directly controlling the ultrasonic intensity, but also ensures the control accuracy of the ultrasonic intensity, and the problem is easily solved. The same is true for ultrasonic vibrations in other modes (vibrations other than the longitudinal mode). As long as it is ultrasonic vibration, the amplitude must determine the ultrasonic intensity.

The basic composition of the ultrasonic transmission system is two parts: ultrasonic driving power supply and ultrasonic equipment host (including transducer, horn, and transmitting head). The ultrasonic drive power supply generates high-frequency high-power AC current to drive the vibration of the host of the ultrasonic equipment. The ultrasonic device host emits ultrasonic waves under the impetus of the driving power. The process is that the transducer first converts high-frequency high-power AC current into ultrasonic mechanical vibration of the same frequency (here is generally longitudinal stretching vibration, strictly speaking, it is mainly longitudinal elastic deformation). The horn amplifies the amplitude of the vibration according to a fixed magnification. The transmitting head also further amplifies the amplitude according to a fixed magnification, and then transmits ultrasonic waves to the liquid. In order to ensure that the ultrasonic amplitude is controllable, the first thing that is required is an ultrasonic drive power supply with constant amplitude control. Under the control of this driving power supply, the amplitude of the transducer will not be affected by the external load. That is to say, as long as the amplitude of the transducer is set on the driving power supply, the output amplitude of the transducer can remain unchanged no matter it is no-load, full-load, or changing load. Correspondingly, it is the input and output power, which changes accordingly as the load changes. Using a car as an analogy, the amplitude is equivalent to the speed of the car, and the power is equivalent to the power of the car. When the speed of the car is constant, whether it is going uphill or downhill, it can remain the same. Correspondingly, when going uphill, the power consumption of the car increases; when going downhill, the power consumption of the car decreases. In this way, the amplitude of the transducer can be controlled through the driving power supply controlled by the constant amplitude. When adjusting the output of the drive power supply, it is actually adjusting the amplitude of the transducer, which can also be said to be setting the amplitude of the transducer.

The traditional way of adjusting the output of the constant amplitude drive power supply can be divided into steps or stepless adjustment, which is generally expressed as a percentage of output power. Either way, a fixed amplitude is set between the transducer's maximum and minimum amplitudes. As long as the output of the driving power supply is not readjusted, the output amplitude of the transducer can be kept constant. Can be calibrated in advance, different gears or different power percentages, corresponding to the actual transducer amplitude. That is to say, for the constant-amplitude drive power supply, the output power percentage or gear of the power supply is set, that is, the output amplitude of the transducer is set.

The amplitude magnification of the horn or the transmitter is determined by the shape of the horn or the transmitter. When their shape is determined, their magnification is also determined. In other words, the magnification can be changed by changing their shape. After they are connected to each other, a complete ultrasonic host is formed to obtain the ultrasonic amplitude we need. For example, the output amplitude of the transducer is 5 microns, the magnification of the horn is 2 times, and the magnification of the transmitter is 3 times. Then, the final output amplitude of the emitting head is 5×2×3=30 microns. The amplitude of the emitter is determined, and the corresponding ultrasonic intensity is also determined. Of course, the specific numerical value of the ultrasonic intensity cannot be known. But in any case, there is a specific value that characterizes the intensity of ultrasonic waves. Moreover, this value corresponds uniquely to the actual ultrasonic intensity.

Through the above approach, the first object of the present invention is achieved: accurately measure the ultrasonic intensity. Although the ultrasound intensity is not determined directly, a one-to-one correspondence with the ultrasound intensity can be determined. The ultrasonic amplitude can be known at any time, can be repeated, and can also be measured with an amplitude measuring instrument (such as the YP0901B amplitude measuring instrument produced by Hangzhou Chenggong Ultrasonic Equipment Co., Ltd.).

The working principle of the amplitude measuring instrument is described as follows: put the dial gauge against the radiation surface of the transmitter. Because the vibration frequency of the emitter is much higher than the resonant frequency of the dial gauge, although the emitter is moving back and forth, the measuring head of the dial gauge can be considered to be almost stationary. In this way, the amplitude of the ultrasonic emitting head can be obtained by measuring the displacement of the emitting head. If a laser is used to measure the displacement, a more accurate amplitude value can also be obtained.

The ultrasonic equipment used for small-scale experiments is driven by a constant amplitude ultrasonic drive power supply. Its output has a power percentage scale. Moreover, the output scale has been calibrated in advance, which corresponds to the output amplitude of the transducer one by one. How much ultrasonic amplitude is needed can be easily set by setting the output scale of the power supply. The magnification of the matching horn and transmitter head is directly marked on the body. Get any horn or transmitting head, you can intuitively know the magnification of this part. After combining them, the amplitude of the transmitter can be accurately known through the scale of the driving power supply, that is, the intensity of the ultrasonic wave can be determined.

(2) Draw the amplitude curve during the small test chemical reaction

The testing machine built in the small test experiment has a basic structure of ultrasonic equipment host and ultrasonic drive power supply, and has a container designed separately for holding liquid. The host of the ultrasonic equipment is the generation and output part of the ultrasonic wave, and its ultrasonic emitting head is responsible for emitting ultrasonic waves into the liquid. The ultrasonic emitting part of the transmitter is generally a small cylinder. The diameter is about 10mm and the length is about 30mm. The liquid to be acted on is usually held in a beaker. The volume of the liquid is in the hundreds of milliliters. During the experiment, insert the ultrasonic transmitter directly into the liquid in the beaker. Less liquid, high ultrasonic intensity, concentrated ultrasonic energy. This will produce the fastest results.

Apply the calibrated ultrasonic equipment to the small test experiment of corresponding chemical production, adjust the amplitude of the ultrasonic equipment step by step during the experiment, and observe the experimental effect at the same time; through a series of experiments, the relationship between the experimental effect and the ultrasonic amplitude can be obtained. Corresponding relationship. Through multiple sets of experimental data, sort out the corresponding relationship between the experimental effect and the amplitude of the ultrasonic equipment, and draw the relationship curve between the amplitude and the experimental effect;

Generally speaking, there is not a linear relationship between the experimental effect and the ultrasonic amplitude. When the ultrasonic amplitude (that is, the ultrasonic intensity) is relatively low, there is almost no effect, even if the action time is long. When the ultrasonic amplitude exceeds a certain value, it starts to have an effect. The ultrasonic amplitude (strength) at which the effect begins is called ultrasonic threshold A1. After exceeding the threshold A1, as the ultrasonic intensity increases, the effect increases accordingly. There is a positive correlation between the ultrasonic amplitude and the experimental effect. When the ultrasonic amplitude reaches a certain value A2, if the amplitude is increased, the experimental effect will hardly increase. According to this, not only can the qualitative conclusion of whether the ultrasonic effect is effective, but also clarify the range of the amplitude (ultrasonic intensity) of the effective ultrasonic effect. This has laid a solid foundation for the selection of ultrasonic equipment used in the next pilot test.

(3) Manufacture of equipment for pilot chemical reaction process

The amplitude data corresponding to the best experimental effect in the small test process is used as the best amplitude value for the pilot test, and the selection or manufacture of ultrasonic equipment is completed based on this; the power range of the ultrasonic equipment is determined according to the amount and nature of the reaction material. Confirmation is based on the fact that the pilot test can be successfully completed and the power of the equipment is not overloaded;

According to the data of the small test, and considering the feasibility, equipment stability, equipment manufacturing cost and other factors, the optimum amplitude (ultrasonic intensity) range of the pilot test machine can be determined. This amplitude range, at least including from A1 to A2, can ensure the effect of ultrasonic waves. At the same time, it is also necessary to comprehensively consider the feasibility, stability and manufacturing cost of the equipment. On the premise of ensuring the amplitude, the emission area S1 of the emission head is enlarged as much as possible. The upper limit of the emission area S1 is the power P1 under the condition of the maximum load medium when the maximum amplitude (ultrasonic intensity D1) is reached. The output power P2 of the ultrasonic equipment can only work normally if it is greater than 1.2 times of P1. Otherwise, the emission area S1 is reduced.

That is, P2≧1.2P1＝1.2×S1×D1

(4) Verify the equipment used for the pilot chemical reaction process

Guided by the relationship curve between the amplitude and the experimental effect in the chemical reaction process of the small test, the experiment is carried out on the equipment of the chemical reaction process of the pilot test; the amplitude of the ultrasonic equipment is adjusted step by step during the experiment, and the reaction conditions are adjusted according to the needs of the reaction. Adjustment. Take the test results that can be repeated in small tests as the standard, and ensure that the power of the equipment is not overloaded.

(5) Application of ultrasonic equipment in chemical production equipment

The basic structure of the testing machine built during the pilot test includes ultrasonic equipment host, ultrasonic drive power supply, reactor and control system. The first purpose of the pilot test machine is to reproduce the experimental results of the small test machine under enlarged conditions. Then, according to the actual needs of chemical production, the ultrasonic equipment confirmed by the pilot test will be applied to the chemical production device in the form of single series connection to meet the requirements of flow rate or ultrasonic action time; or, the application of single unit parallel connection In chemical production equipment, it meets the requirements of design output.

A typical three-step method application example of the present invention is described as follows:

The ultrasonic equipment confirmed by type selection becomes a single unit with practical value, and becomes a complete production line through simple repetition (series and/or parallel connection). Here, the parallel connection mainly solves the output requirements, and the series connection mainly solves the flow velocity and the ultrasonic action time requirements. In the production device, the transmitter head of the ultrasonic equipment host is inserted into the reaction kettle, and the liquid to be acted on is also in the reaction kettle, which is strongly affected by the ultrasonic waves. In order to improve uniformity and processing efficiency, the reactor also has a circulation system.

Claims (4)

1. The three-step method of using the ultrasonic equipment based on amplitude control for chemical plant, it is characterized in that, comprising the following steps: (1) Calibrate the ultrasonic equipment For the calibration of ultrasonic equipment with power, power percentage or power absolute value as the adjustment scale mark, change the value with amplitude as the unit of measurement as the adjustment scale mark; (2) Draw the amplitude curve during the small test chemical reaction Apply the calibrated ultrasonic equipment to the small test experiment of corresponding chemical production, adjust the amplitude of the ultrasonic equipment step by step during the experiment, and observe the experimental effect at the same time; through multiple sets of experimental data, sort out the relationship between the experimental effect and the amplitude of the ultrasonic equipment Corresponding relationship, draw the relationship curve between the amplitude and the experimental effect; The experimental effect refers to the specific purpose that the chemical reaction process needs to achieve; (3) Manufacture of equipment for pilot chemical reaction process The amplitude data corresponding to the best experimental effect is used as the optimal amplitude value for the pilot test, and the design and manufacture of the ultrasonic equipment are completed accordingly; the power range of the ultrasonic equipment is determined according to the amount and nature of the reaction material, and the pilot test It can be successfully completed and the power of the equipment is not overloaded as the basis; (4) Verify the equipment used for the pilot chemical reaction process Guided by the relationship curve between the amplitude and the experimental effect in the chemical reaction process of the small test, the experiment is carried out on the equipment of the chemical reaction process of the pilot test; the amplitude of the ultrasonic equipment is adjusted step by step during the experiment, and the reaction conditions are adjusted according to the needs of the reaction. The adjustment is based on the test results that can be repeated in the small test, and the power of the equipment is not overloaded; (5) Application of ultrasonic equipment in chemical production equipment According to the actual needs of chemical production, the ultrasonic equipment that has been verified and finalized by the pilot test is applied to the chemical production device in a series connection of monomers to meet the requirements of flow rate or ultrasonic action time; or, it is applied in a parallel connection of monomers In chemical production equipment, meet the design output requirements; The ultrasonic equipment is equipped with an ultrasonic driving power supply controlled by a constant amplitude, which can provide at least a terminal output amplitude of 100 microns under the condition of 20 kHz, and the amplitude is adjustable. 2. The method according to claim 1, characterized in that, the ultrasonic equipment used in small-scale experiments or pilot-scale experiments has a rod-like emitter with variable cross-section. 3. The method according to claim 1, characterized in that the amplitude magnification is marked on the transmitting head or the horn of the ultrasonic equipment. 4. The method according to claim 3, characterized in that the horn or the emitting head can be disassembled and replaced, and multiple combined connections can be realized.