zhengzhoumingyilab

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Troubleshooting method of glass reactor

1. Turn on the power switch, and the indicator light is not on: the external power supply is not connected or the contact is poor, please ask a professional electrician to check the power supply and socket.

2. The fuse is short-circuited, turn the power switch to the OFF position, and then replace the fuse.

3. The power indicator light is on, but it does not rotate, the rotating shaft is rusted, stop using it, and contact the supplier. The motor and electrical box are faulty, the seven-pin plug is not connected, and the seven-pin plug is reconnected.

4. The vacuum suddenly disappears, the glass is cracked, check the glass parts; if the switch is damaged, replace the switch.

5. There is a vacuum but cannot be pumped: the sealing ring is worn, please replace the sealing ring, connect the vacuum switch to leak, and replace the switch.

6. Sometimes there is no vacuum: there is dirt on the steel shaft. The connector is loose. Please remove the dirt and check the vacuum meter and vacuum pump.

7. Aging vacuum hose: Please replace the vacuum hose.

8. The main shaft is loose left and right: the top screw is loose.

9. The motor temperature is too high and overloaded: stop the machine, turn the machine shaft by hand, whether it is heavy, remove the dirt that the sealing ring cannot contact with the glass shaft, and apply vacuum grease.

10. The speed display does not match the actual: the voltage is unstable, and there is an error in itself.

11. The shell is electrified: the heating tube has cracks and water enters, please check it by a professional electrician

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What are the main components of a small rotary evaporator？

The small rotary evaporatoradopts a simple vertical cooler, high product, small footprint, and the height of the vertical condenser is reduced.

The lifting operation of the body is very convenient. The lift handle can move up and down smoothly and lock securely. There is also an auxiliary extension on the upper part of the body to adjust the position of the buffer bottle or small sample bottle. It can extend and slide up and down 30cm from the opening part, and it is equipped with a backflow prevention joint to prevent backflow. When used in combination with the vacuum controller NVC type connection, the recovery efficiency of the rotary evaporator can be improved, and a chemically resistant full Teflon gasket can be selected for the recovery of low-boiling organic solvents.

The main components:

1. Rotate the motor to drive the evaporating flask containing the sample through the rotation of the motor;

2. Evaporation tube, the evaporation tube has two functions, firstly, it plays the role of the sample rotation support shaft, and secondly, through the evaporation tube, the vacuum system sucks the sample out;

3. The vacuum system is used to reduce the air pressure of the rotary evaporator system;

4. Fluid heating pot, usually water is used to heat the sample;

5. Condenser tube, use double serpentine condenser or other condensing agents such as dry ice and acetone to condense samples;

6. Condensate the sample collection bottle, and the sample enters the collection bottle after cooling.

Features of the small rotary evaporator:

1. The instrument is developed by applying the principle of constant temperature heating and thin film evaporation under the condition of vacuum negative pressure.

2. The instrument is controlled by an imported frequency converter, and the stepless speed regulation makes the glass rotating bottle rotate at a constant speed, and the material forms a large-area uniform film on the bottle wall, and then the rotating bottle is heated evenly by a controllable constant temperature water bath.

3. It evaporates at high speed under the condition of vacuuming the system, and the solvent vapor is cooled by the glass double condenser and recovered in the collection bottle. The instrument is also equipped with a feeding interface and a feeding mechanism, which is convenient for automatic and continuous operation during the evaporation process.

4. Since the instrument works under vacuum conditions, and all parts in contact with materials are made of high temperature resistant high borosilicate glass and PTFE materials.

5. Therefore, the small rotary evaporator is especially suitable for the concentration, crystallization, separation and solvent recovery of heat-sensitive materials and materials that are contaminated with stainless steel and other metal materials.

6. Large contact area, high evaporation efficiency, easy to use, low noise, reliable sealing, can handle easily foaming materials, and complete specifications. Various specifications have been formed, which is convenient for users with different needs to choose.

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Difference Between Thin Film Evaporator and Molecular Distillation Apparatus

Molecular distillation is a liquid-liquid separation technology that makes the mean free path of vapor molecules larger than the distance between the evaporation surface and the condensation surface in a vacuum state. Therefore, the liquid mixture can be separated by utilizing the difference in the evaporation rate of each component in the feed liquid.

The difference between thin film evaporator and molecular distillation apparatus:

Conventional distillation techniques are generally carried out at the boiling temperature, but there is no such condition in molecular distillation, as long as there is a sufficient temperature difference between the hot and cold surfaces. This is also proved by the fact that the operating temperature of molecular distillation is much lower than the boiling point of the material.

In addition, if the conventional distillation is not careful, it is easy to cause bad phenomena such as bubbling and boiling, which of course will not occur in the molecular distillation process, because it is the free evaporation of the liquid film surface, the operating pressure is generally very low, and the heating time is also relatively short. In general, the evaporation and condensation of conventional distillation are reversible processes, and the liquid and gas phases are in dynamic phase equilibrium; while in the process of molecular distillation, the molecules escaped from the heating surface directly fly to the condensation surface, so the There is no limit to it.

Although thin-film evaporators and short-path molecular distillation apparatuses are both chemical production equipment and separation devices, there is really a big difference between thin-film evaporators and short-path molecular distillation apparatuses. Regarding this point, we only need to compare the structure and performance of the two devices.

From a structural point of view, the difference between the two is that the gas-phase outlet of the thin-film evaporator is at the top of the evaporator, so as to satisfy the rule that the steam of light components flows from the bottom to the top; while the short-path molecular distillation apparatus is just the opposite, and its gas-phase outlet is at the top of the evaporator. The bottom of the evaporator, mainly because the light components in this equipment are fully condensed on the built-in condenser.

The second is the performance of the equipment. This difference is also caused by the difference in structure. For example, the minimum operating pressure of the thin-film evaporator can reach 1mbar, while the short-path molecular distillation apparatus is lower and can reach the operation of 0.001mbar. pressure. However, the molecular distillation apparatus also has certain limitations. Due to the built-in condenser, there is no way to add a bottom bearing to the wiped film rotor, which will generate large vibrations during operation, thereby affecting the effect of the wiped film.

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How to maintain the single-layer glass reactor？

The single-layer glass reactor can provide high temperature reaction (the highest temperature can reach 300 ℃); it can also be vacuumed to do negative pressure reaction. The single-layer glass reactor can perform various solvent synthesis reactions under constant temperature conditions. The reaction part of the instrument is a fully sealed structure that can be controlled. It can continuously suck in various liquids and gases under negative pressure, and it can also be refluxed or distilled at different temperatures.

So how to maintain the single-layer glass reactor?

1. Check the instrument carefully before use. Whether the glass bottle is damaged and whether the interfaces are consistent, please handle it gently.

2. Wipe each interface with a soft cloth (can be replaced with a napkin), and then apply a little vacuum grease. (Be sure to cover the vacuum grease after use to prevent dust from entering.)

3. The ports of the glass reactor should not be screwed too tightly, and should be loosened regularly to avoid long-term locking to cause the connector to seize.

4. Turn on the power switch first, then let the machine run from slow to fast, and then turn off the switch when the machine is stopped.

5. The PTFE switches everywhere can't be tightened with excessive force, it is easy to damage the glass.

6. After each use, you must use a soft cloth to wipe off all kinds of oil stains, stains, and solvent remaining on the surface of the machine to keep it clean.

7. Loosen each PTFE switch after the machine stops, and the PTFE piston will be deformed if it is in the working state for a long time.

8. Clean the sealing ring regularly by removing the sealing ring, checking whether there is dirt on the shaft, wiping it with a soft cloth, applying a little vacuum grease, and reinstalling it to keep the shaft and the sealing ring smooth.

9. The electrical parts must not be exposed to water, and it is strictly forbidden to get wet.

10. It is necessary to purchase original parts from the factory. Using other parts at will can cause fatal damage to the machine.

11. When doing any repairs or inspections on the glass reactor, be sure to cut off the power and water source first.

The above are the relevant knowledge points of the single-layer glass reactor. I hope that the above content can be helpful to everyone. Thank you for your watching and support. If you need a single-layer glass reactor, choose Mingyi

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How to solve the temperature adjustment problem of vacuum freeze dryer

The vacuum freeze dryer is an excellent drying method. The dried product can be stored for a long time at room temperature without any additives under the sealed condition. The structure of freeze-dried items is porous and crisp, and the rehydration is fast when used. The color, fragrance, taste, shape and activity of the items are basically unchanged after rehydration. The vacuum freeze dryer is especially suitable for the food, health, health, and pharmaceutical industries. . The vacuum freeze dryer is to freeze the wet material or solution into a solid state at a lower temperature (-10℃～-50℃), and then make the water in it sublimate directly into a gaseous state under a vacuum (1.3～13 Pa). , Drying technology to dehydrate materials.

The working principle of the vacuum freeze dryer is to first freeze the dried items to below the triple point temperature, and then directly sublime the solid water (ice) in the items into water vapor under vacuum conditions, and remove them from the items. , Make the item dry. After pre-processing, the materials are first quick-frozen, then vacuum dried, sublimated and dehydrated, and then packaged in the post-processing workshop. The heating system of the vacuum freeze dryer provides sublimation latent heat to the material, and the refrigeration system provides the required cold energy to the water trap and the drying bin. The quality requirements for freeze-dried products are: unchanged biological activity, uniform appearance and color, full shape, firm structure, solid, fast dissolving speed, and low residual moisture. To obtain high-quality products, you should have a more comprehensive understanding of the theory and technology of freeze-drying. The freeze-drying process of the vacuum freeze dryer includes three stages: pre-freezing, sublimation and re-freezing. The vacuum freeze dryer is reasonable and effective. Shortening the cycle of freeze-drying has obvious economic value in industrial production.

In the process of freeze-drying, the temperature of the liquid products needs to be controlled within a certain range required by the process during the cooling and pre-freezing of the liquid products and the subsequent sublimation of the moisture in the solid products. This requires the vacuum freeze dryer to have a certain accuracy. Temperature adjustment function. The temperature adjustment problem of the vacuum freeze dryer is better solved without setting the temperature adjustment unit. The specific plan is as follows:

1. Under the premise of surplus refrigeration compressor refrigeration, a refrigeration branch that can provide appropriate refrigeration capacity is added next to the refrigeration system pipeline that provides cooling to the front box of the vacuum freeze dryer. Amount needed;

2. At the same time, when the temperature is adjusted, the refrigeration compressor is cooling two evaporators with different evaporating temperatures. The difference in working conditions may have a greater impact on the refrigeration compressor due to the lag of the expansion valve control, and it may be severe. It will cause the liquid shock of the refrigeration compressor to cause failure, which requires a good grasp of the control of the return steam pressure. The current technicians have added an electromagnetic valve to the return steam pipeline of the front box evaporator, and the pressure controller is used to control the return steam pressure. The pressure difference between the front and back of the solenoid valve is monitored to control the opening or closing of the valve to reduce the load impact during temperature adjustment, and to ensure the smooth operation of the vacuum freeze dryer compressor;

3. In order to prevent the pressure increase in the front box evaporator caused by the closing of the electromagnetic valve, and the temperature adjustment effect cannot be guaranteed, the vacuum freeze dryer technicians will return in front of the electromagnetic valve. A return steam branch pipe is added to the steam pipeline, which is connected to the second-stage compressed suction pipe of the refrigeration compressor. Through practice on multiple vacuum freeze dryers, the results have proved that this treatment scheme is feasible, and it can avoid . It avoids the increase in the cost of adding a temperature control unit, and solves the temperature control effect caused by the commonly used capillary temperature control. The result is not ideal and the load impact on the compressor.

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Do you know these about glass reactor?

There are several heating methods for glass reactors

The glass reactor has heating methods such as far infrared heating, steam heating, water bath circulation heating, heat conduction oil heating, or heat conduction oil electric heating. It is mainly heated by circulating steam in the oil, by welding a jacket outside the kettle, or directly inserting an electric heating tube into the jacket.

Glass reactors are widely used in pressure vessels in chemical, food, coating, hot melt adhesive, silica gel, paint, medicine, and petrochemical production processes, such as reaction, evaporation, synthesis, polymerization, saponification, sulfonation, chlorination, nitration, etc. , Such as reactors, reaction kettles, decomposition pots, polymerization kettles, etc. The reaction kettle is mainly composed of four parts: inner tank, jacket, stirring device, and support seat (the structure with heat preservation can be adopted according to the process requirements).

There are currently three most common heating methods:

1. Steam heating: When the heating temperature is below 100°C, steam can be used to heat the double-layer glass reactor. When the temperature requirement is within the range of 100-180℃, saturated steam can be used, and when the temperature requirement is higher, high-pressure superheated steam can be used to stop heating;

2. Electric heating: Electric heating is wound on the insulating layer of the double-layer glass reactor cylinder through a resistance wire, or installed on a special insulator some distance away from the double-layer glass reactor. Therefore, a small gap can be formed between the resistance wire and the double-layer glass reactor body;

3. Water heating: When the temperature requirements are not high during the consumption process, water heating can be used to stop heating;

At present, the most mainstream method is to use water or mineral oil to stop heating. Because of its low cost, convenient medium change, and easy maintenance, it is the choice of Fangda customers.

How to choose a glass reactor suitable for your own process conditions

The temperature control system of the glass reactor is composed of a processor and bottom equipment. The processor is very delicate, and there is an information layer that collects the data used on site, and manages it through processing and classification after collection. At the same time, it also has a control layer, that is to say, it is calculated from various aspects in the use of the glass reactor. So as to realize the control function. So how to choose a glass reactor suitable for your own process conditions, before choosing a glass reactor, you must first make a simple combing of the use conditions of the glass reactor and your own process.

1, select the appropriate size of the kettle body, the volume of the kettle body required = the total amount of materials * 1.33. We can calculate the size of the kettle body we need according to this formula.

2, when determining whether the reactor needs to be filtered or an ordinary reactor, if there is crystallization after the reaction is completed, this part of the product needs to be extracted, and it is recommended to use a filtration reactor

3, to determine the viscosity of the material, you must have a rough understanding of the viscosity of your material before selecting the kettle, so that we can hang a suitable stirring paddle and motor.

4. To determine the physical properties of our materials, we do not need homogeneous emulsification, ultrasonic dispersion, etc. If this part of the function is needed, we should complete the customization of the kettle body before buying, because most of the kettles cannot be compared after the purchase. Greatly change its process conditions.

5, Condensing device, there is a reflux device under the condenser of the standard kettle, whether it is confirmed that it needs to be directly refluxed into the kettle or need to install a collection device, the 1-5 liter glass reactor has an optional water separator.

6, determine if PH test is needed

7, determine whether to install a PTFE spray device, which is mainly used to clean the kettle

8, determine whether you need to lift the rotating frame, the body of the glass reactor can be lifted and rotated, which is convenient for pouring and cleaning.

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Tips in the use of rotary evaporator

First, Method to prevent solvent spray during rotary steaming:

1, the temperature should not be too high, and the temperature of the water bath should not exceed 30 degrees Celsius.

2, don’t pack too much, if it’s a low boiling point solvent, consider not heating it and adjust the vacuum slowly.

3, replace the recovery bottle with a larger capacity. Generally, the smaller the volume of the recovery bottle, the easier it is to bump.

4, the vacuum pressure should not be too high, people should not leave during the steaming process, always pay attention, and open the vacuum valve as soon as there is a sign of spraying.

5, for solvents with low boiling point and easy to bumpy spray, use your finger to operate the rotary vapor vent to properly vent and pressurize.

6, first externally rotate in the water bath until water mist appears outside the flask, and then gradually decrease the volume of water bath contact until it stabilizes and does not bump.

7, use anti-flushing anti-boiling ball, which can be poured back after spraying. This needs to ensure that the explosion-proof ball is clean, so wash and dry before each use.

Second, how to choose the appropriate temperature of the rotary evaporator

The best way to use Rotary Evaporator is called the golden "Δ20°C rule". In order to fully condense the vapor, the temperature of the cooling circulator should be set to be about 20°C lower than the vapor temperature. For example, at a bath temperature of 50°C, a solvent vapor temperature of 30°C is generated, and then it is condensed at 10°C.

Three, how to choose the pressure of the rotary evaporator

The pressure and temperature of the rotary evaporation are very important. Generally speaking, there is a linear relationship between the temperature of the water bath and the evaporation rate. The more energy you use in the evaporation process and the more energy removed from the condensing part, the higher the distillation efficiency. The premise is that you also need to pay attention that the condenser has sufficient cooling capacity and remains stable under pressure.

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Freeze drying process of freeze dryer

Since the development of laboratory freeze dryers, its types have gradually increased. According to its functions, it can be divided into: ordinary freeze dryer, capping freeze dryer, multi-manifold common freeze dryer, multi-manifold capping freeze dryer, T-frame freeze dryer, in-situ type freeze dryer.

The freeze-drying process includes pre-cooling, primary drying, secondary drying and storage stages, which are all very complicated heat and mass transfer processes; and these processes are closely related to the thermophysical properties of medicines, foods, excipients, and cryoprotectants .

Therefore, it is necessary to clarify the factors that affect the heat and mass transfer of the drying process, and to determine the thermophysical properties of the relevant materials, in order to formulate a reliable procedure, adopt an optimized freeze-drying process, and produce high-quality medicines and foods; and can achieve shortening The purpose of production time, energy saving, and cost reduction.

The freeze-drying of the product needs to be carried out in a certain device, which is called a vacuum freeze dryer, or freeze dryer for short. According to the system, the freeze dryer is composed of four main parts: the refrigeration system, the vacuum system, the heating system, and the control system. According to the structure, it is composed of a freeze-drying box or drying box, a condenser or a water vapor condenser, a refrigerator, a vacuum pump and valves, and electrical control components.

The freeze-drying process is actually the material change and transfer process of water. The freeze-drying process has two exothermic processes and two absorption processes: the liquid biological product releases heat and solidifies into a solid biological product, and the solid biological product absorbs heat under vacuum and sublimates into water vapor. The water vapor releases heat in the condenser to condense into frost, and after freeze-drying, the frost absorbs heat in the condenser and melts into water.

The heat mass transfer phenomenon takes place during the entire freeze-drying process. The heat transfer runs through the whole process of freeze-drying. The pre-freezing stage, the drying stage, the second stage and the defrosting stage are all carrying out heat transfer; the mass transfer is only carried out in the drying stage, and the water vapor generated in the dry box products is condensed into frost in the condenser. The process is actually the process of mass transfer. Only when mass transfer occurs, the product can be dried. In the drying stage, heat transfer is to promote mass transfer, and improving heat transfer can also improve mass transfer.

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Introduction to the advantages of glass reactor products

The glass reactor is mainly based on its double-layer glass feature. We can place the reaction material (reaction solvent) in the middle layer, and stir the reaction under normal pressure or negative pressure. The glass reactor is sandwiched by the double-layer reactor. , Inject a constant temperature (high temperature or low temperature) hot solution or cooling liquid to heat or cool the materials in the reactor at a constant temperature, and can provide stirring. In this way, the medium in the interlayer of the glass reactor (such as: refrigerating liquid, heating water or heating oil) is stirred to make a cyclic reaction to achieve heating or cooling. It is widely used as an ideal equipment in modern biochemical new material synthesis experiments.

Product advantages of glass reactor:

① It adopts maintenance-free brushless DC brushless motor, continuous and stable operation for a long time, outstanding performance, external PC through RS485 data transmission port, control the instrument and record the speed, torque data, etc.

② Without any tools, swing arm fixture design, installation and all the kettle body disassembly and replacement can be completed in a few minutes

③ The motor kettle cover can be raised and lowered manually, the kettle body can be rotated at 90 degrees, which is convenient for cleaning or loading and unloading, etc.

④ Glass production adopts international standards, ISO3585

⑤ There is a tetrafluoroethylene O-ring between the kettle body and the kettle cover

⑥ PTFE + mechanical components double seals, ceramic bearings, seals without wear debris

⑦ Different kettle body specifications can be arbitrarily switched on the same frame

⑧ The annular spoiler in the sandwich design, the heat conduction liquid is a spiral flow heat conduction, and the temperature control is more delicate and accurate

⑨ Designed gas-liquid separator can be completely refluxed into the kettle or collected in the receiving bottle

⑩ All tetrafluoroethylene no dead angle discharge valve

⑪ Propeller mixing paddle (made of stainless steel wrapped with PTFE, high strength)

⑫ Glass reactor is mainly used for synthesis reaction, stirring distillation, concentration extraction, etc. The glass parts adopt international standards, and the unique quick-release fixture design is easy to use. It can be replaced within a few minutes. The replacement of the kettle body of different specifications from 500ml to 5000ml is simple and quick.

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There are four processes for using molecular distillation apparatus as follows

Molecular distillation is also called short-path distillation. It is a relatively new liquid-liquid separation technology that has not been widely used in industrial production. Its application can solve a large number of problems that cannot be solved by conventional distillation technology. Molecular distillation is a distillation method that operates under high vacuum. At this time, the mean free path of vapor molecules is larger than the distance between the evaporation surface and the condensation surface, so that the difference in the evaporation rate of each component in the liquid can be measured. Use it to separate liquid mixtures. Molecular evaporator, degassing system, feeding system, heating system, cooling vacuum system and control system are the main components of a complete molecular distillation apparatus. The molecular evaporator is the core part of the molecular distillation device.

The short path distillation apparatus is quite suitable for molecular distillation, the molecular flow from the heating surface directly to the surface of the condenser. Molecular distillation has the following four processes:

1. Molecules diffuse from the liquid phase to the evaporation surface

Generally, the diffusion rate in the liquid phase is the main factor controlling the molecular distillation rate, so the thickness of the liquid layer should be reduced as much as possible and the flow of the liquid layer should be strengthened.

2. Free evaporation of molecules on the surface of the liquid layer

As the temperature rises, the evaporation rate continues to rise. However, as the temperature rises, the separation factor sometimes decreases. Therefore, the thermal stability of the processed material must be used as a prerequisite to select an economical and reasonable distillation temperature.

3. Molecules fly from the evaporation surface to the condensation surface

When the vapor molecules fly from the evaporation surface to the condensation surface, they may collide with each other, and may also collide with air molecules remaining between the two surfaces. Because evaporating molecules are much heavier than air molecules and most of them move in the same direction, their collisions will not have a large impact on the direction of flight and the speed of evaporation. However, the chaotic thermal motion state of residual gas molecules appears between the two sides, so the main factor that affects the direction of flight and the evaporation speed is the number of residual gas molecules.

4, molecules condense on the condensation surface

It is only necessary to make the temperature difference between the hot and cold sides sufficient (usually in the range of 70-100 degrees Celsius), and the form of the condensing surface is reasonable and smooth, then it is considered that the condensing step can be completed in an instant, so it is very important to have a reasonable condenser The choice of form.

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What kind of rotary evaporator has the highest distillation efficiency

Rotary evaporator, referred to as rotary evaporator, is an instrument used in laboratories to continuously distill a large amount of volatile solvents under reduced pressure, and can separate and purify reaction products.

The rotary evaporator is mainly composed of a rotary motor, an evaporation tube, a vacuum system, a fluid heating pot, a condenser tube, and a condensed sample collection bottle. Its working principle is to make the evaporation flask in a negative pressure state through a vacuum pump, and through electronic control, make the flask rotate at a constant speed at a suitable speed to increase the evaporation area. The Suke purchasing steward learned that the rotary evaporator system can seal and reduce pressure to 400-600 mmHg, and the rotation speed can reach 4 to 200 rpm, so that the solvent can form a thin film and increase the evaporation area. The force generated by the rotation can effectively inhibit the boiling of the solution.

To purchase a high-efficiency rotary evaporator, you need to consider the following factors:

1. Choose the size of the rotary evaporator according to the experimental needs

What is the amount of distillation required for one experiment? What is the number of distilled samples? What are the solvents for distillation? What are their boiling points? Through the above questions, determine what temperature range of the rotary evaporator is needed, what level of temperature control accuracy is required, and how large the volume of the evaporating flask and collection flask should be. Generally speaking, a laboratory-grade rotary evaporator with a capacity of less than 5L is enough, and an industrial-grade CNC rotary evaporator can be adapted to a 20L large-capacity evaporating flask.

2. Vacuum is the core indicator

Under the corrosion of various solvents and in the state of motion, whether the system can maintain a high vacuum degree is the most important criterion for measuring the rotary evaporator. Choose a rotary evaporator sealed with Teflon material and glass, which can withstand various solvents, has long-lasting and reliable air tightness, and can maintain a high vacuum degree above -0.098MPa.

3. Selection of heating pot and heating medium

The temperature of the heating pot should be 20 degrees higher than the boiling point of the solvent. Note that the boiling point of the solvent under vacuum may be different from the boiling point under normal conditions. The heating medium is generally tap water or distilled water. If the heating medium is silicone oil, the ignition point is at least 25°C higher than the maximum temperature of the heating pot.

4. Choice of condenser

There are two common condensers on the market, vertical condensers and inclined condensers. The vertical condenser occupies a small space, and the vertical condenser for the large-capacity evaporator is more space-saving.

5. Optional explosion-proof glass components

Distilling flammable and explosive solvents, it is recommended to choose glass components with explosion-proof coating. Choose a rotary evaporator with automatic deflation function to prevent manual deflation from causing an explosion if the speed is not well controlled.

6. Parameters affecting evaporation efficiency

Understanding the factors that affect the distillation efficiency of the rotary evaporator will help you to better choose the right product and obtain the best experimental results through the correct experimental operation. Soke Purchasing Manager has summarized the following factors that have an impact on the efficiency of the rotary evaporator for your reference:

(1) The vacuum value of the system, among which the most critical factors are the materials of the vacuum pump, sealing ring and vacuum tube.

(2) The temperature of the heating pot. The higher the temperature, the faster the distillation effect, but considering the heat sensitivity of the ingredients and the safety of operation, the commonly used temperature is 60 degrees Celsius. It is generally recommended to lower the vacuum value to achieve faster distillation efficiency.

(3) Rotation speed of distillation flask. The faster the speed, the larger the heated area, but at the same time the thicker the thickness of the liquid film will increase the heat transfer temperature difference. Therefore, materials with different viscosities have different applicable optimum speeds.

(4) The temperature of the cooling medium. It is generally recommended to maintain a temperature difference of 40°C between the cooling medium and the heating pot, which can improve the condensation efficiency and reduce the effect of steam on the vacuum of the system.

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The advantages of freeze drying technology of freeze dryer compared with ordinary drying technology

There are various drying methods, such as sun-drying, boil-drying, drying, spray drying and vacuum drying, etc., but common drying methods are usually carried out at a temperature above 0°C or higher. The dried products generally have the problems of reduced volume and hard texture. Most of the volatile components will be lost. Some heat-sensitive materials will be denatured and deactivated, and some materials may even be oxidized. Therefore, there is a big difference in the properties of the dried product compared to the one before drying. So what are the advantages of freeze drying technology of freeze dryer compared with ordinary drying technology?

1. Many heat-sensitive substances will not undergo denaturation or inactivation, which is collected and sorted by the medical education network.

2. When drying at low temperature, the loss of some volatile components in the substance is very small.

3. During the freeze-drying process, the growth of microorganisms and the action of enzymes cannot proceed, so the original properties can be maintained.

4. Since the drying is carried out in a frozen state, the volume is almost unchanged, the original structure is maintained, and no concentration phenomenon occurs.

5. Since the moisture in the material exists in the form of ice crystals after pre-freezing, the dissolved inorganic salt substances originally dissolved in the water are evenly distributed in the material. During sublimation, the dissolved substances dissolved in the water are precipitated, which avoids the phenomenon of surface hardening caused by the precipitation of inorganic salts on the surface due to the migration of the internal moisture of the material to the surface in the general drying method.

6. The dried material is loose, porous, and sponge-like. After adding water, it dissolves quickly and completely, and restores its original properties almost immediately.

7. Since the drying is carried out under vacuum, there is very little oxygen, so some easily oxidized substances are protected.

8. Drying can remove more than 95% to 99% of moisture, so that the dried product can be stored for a long time without deterioration.

9. Because the material is in a frozen state and the temperature is very low, the temperature of the heat source for heating is not high, and the normal temperature or low temperature heater can meet the requirements. If the freezer compartment and the drying compartment are separated, the drying compartment does not need to be insulated, and there will not be a lot of heat loss, so the use of heat energy is very economical.

 Even the best technology has its disadvantages. The main disadvantage of vacuum freeze-drying technology is its high cost. Because it needs vacuum and low temperature conditions, the vacuum freeze dryer must be equipped with a vacuum system and a low temperature system, so the investment cost and operating cost are relatively high.

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The determinants of the time of vacuum freezing, drying and freeze-drying samples

Vacuum freeze dryer is also called freeze dryer. The basic principle of freeze vacuum drying is heat and mass transfer under low temperature and low pressure conditions. Due to the different properties of the freeze-dried materials, freeze-drying methods and quality requirements for freeze-dried products, the models describing the freeze-drying process and their solutions are also different. Generally, there are three major stages in the freeze-vacuum drying process: freezing stage, sublimation drying stage, and analytical drying stage. The whole process is actually a process in which heat and mass transfer are carried out at the same time. The heat and mass transfer rate together affect the drying rate, thereby affecting the entire freeze-drying cycle. All factors that affect heat and mass transfer will affect the drying rate. Therefore, the determinants of the time of vacuum freezing, drying, and freeze-drying samples are mainly as follows.

Freeze drying chamber pressure

The pressure in the freeze-drying chamber of the vacuum freeze dryer affects the rate of heat and mass transfer. For mass transfer, the lower the pressure, the better; for heat transfer, the higher the pressure, the better. The mass transfer rate is mainly determined by the temperature and pressure difference between the sublimation interface and the surface of the drying layer. To increase the escape rate of water vapor in the drying layer, the temperature of the sublimation interface can be increased to increase the water vapor pressure of the interface; the vacuum degree of the freeze-drying chamber can also be increased, and the vapor pressure on the surface of the drying layer can be reduced.

Heat transfer method

According to the traditional classification, it can be divided into: heat conduction (caused by particles with different temperatures in thermal motion, which can be generated in solid, liquid, and gas), thermal convection (convection is due to the relative occurrence of parts of fluids with different temperatures. Movement, intermixing with each other to transfer heat energy), thermal radiation (all objects with a temperature higher than absolute zero, regardless of their temperature, are continuously radiating electromagnetic waves of different wavelengths) and medium heating (microwave heating). Since the process of sublimation drying involves the transfer of heat and quality (water vapor), which heat transfer method is used to transfer heat to the material more effectively has a greater impact on the drying rate.

Concentration of organic solvent in the sample

The concentration of the organic solvent in the sample has a greater impact on the freeze-drying rate. The higher the concentration, the slower the freeze-drying rate, and the lower the concentration, the faster the freeze-drying rate. To

Crystal size

The size of crystals formed during pre-freezing largely affects the rate of freeze-drying and the rate of dissolution of the product after freeze-drying. There are the following differences between quick freezing and slow freezing: the ice crystals produced by quick freezing are smaller, and the ice crystals produced by slow freezing are larger. Large ice crystals are good for sublimation, while small ice crystals are not good for sublimation. Fast freezing will result in low sublimation rate and fast resolution rate; slow freezing will result in fast sublimation rate and slow resolution rate.

The number of samples

When the sample is freeze-dried, there is a certain surface area to material thickness ratio after being divided into the container, that is, the freeze-drying is related to the sample amount. Large surface area and small thickness are conducive to water sublimation, easy to freeze-dry and ideal quality. When drying, the dry load per unit area of the tray is an important factor in determining the drying time: in general, the thinner the thickness of the material accumulation, the faster the heat and mass transfer speed, and the shorter the drying time. However, the thinner the material, the fewer samples dried per batch per unit freeze-drying area, which is not good for improving the unit freeze-drying area and the output per unit time.

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Practical skills to improve the distillation efficiency of rotary evaporators

Practical skills to improve the distillation efficiency of rotary evaporators

The distillation efficiency of the rotary evaporator determines the number of samples that can be distilled every day. In the case of the same solvent, the higher the distillation efficiency, the more samples that can be distilled. So what are the practical skills to improve the distillation efficiency of the rotary evaporator?

1. The vacuum value of the system

The vacuum degree is the most important process parameter of the rotary evaporator, and users often encounter the problem that the vacuum degree cannot be reached. This is often related to the nature of the solvent used. In biochemical and pharmaceutical industries, water, ethanol, acetic acid, petroleum ether, chloroform, etc. are commonly used as solvents, while general vacuum pumps cannot withstand strong organic solvents. Special vacuum pumps with strong corrosion resistance can be selected. Water circulation is recommended. Vacuum pump.

From the structural point of view, the enclosed space of the rotary evaporator is composed of glass components such as evaporating flask, evaporating tube, sealing ring, condenser tube, vacuum buffer bottle, vacuum pump, and vacuum pipeline. Among them, the most critical and variable factors affecting the vacuum of the system Yes: vacuum pump, sealing ring and vacuum tube.

Vacuum pump and vacuum controller: The lower the vacuum pump limit, the lower the vacuum value of the system. When distilling, it is necessary to set a reasonable vacuum value through the vacuum controller to ensure the distillation efficiency while avoiding bumping. At present, the ultimate vacuum of the diaphragm vacuum pump can reach 2mbar, and the ultimate vacuum of the circulating water pump is about 50mbar (0.095kpa). If the budget permits, a vacuum controller or vacuum valve is necessary, which can control the system vacuum required for distillation.

Sealing ring: As a key seal for the evaporator tube and condenser tube, its wear resistance and corrosion resistance are the key. The materials commonly used as sealing rings are: PTFE and rubber. Obviously, the wear resistance and corrosion resistance of PTFE will be better. Individual manufacturers add stainless steel buffer shrapnel to the seal ring, which has better wear resistance.

Vacuum tube material: Generally, the manufacturers do not have standard vacuum tubes. When purchasing by themselves, silicone tubes are naturally the best, because their aging efficiency is slower than that of rubber tubes.

2. Heating pot temperature

The higher the heating pot temperature, the faster the solvent distillation effect, but considering the heat sensitivity of the target component and the safety of operation, the commonly used temperature is 60°C. In addition, above 80°C, changing to silicone oil as the medium will cause cleaning problems. Generally, it is recommended to lower the vacuum value to achieve faster distillation efficiency. Currently on the market, *diaphragm vacuum pumps can reach an ultimate vacuum of 2mbar, and DMF can be distilled at room temperature.

3. Rotation speed of evaporating flask

The faster the rotating speed of the evaporating flask, the larger the infiltration area of the inner surface of the flask and the larger the heated area; but at the same time, the thicker the liquid film thickness will increase the heat transfer temperature difference. For materials with different viscosities, there is an optimal speed. And the rotating power is provided by the motor. There are brushless DC motors, AC motors and stepping motors on the market, and they are uneven. The feedback of the DC brushless motors is very good.

4. The temperature of the cooling medium

In order to ensure the best distillation efficiency, the cooling medium is generally recommended to maintain a temperature difference of 40°C with the temperature of the heating pot in order to quickly condense the hot steam and reduce the influence of the steam on the vacuum of the system.

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Tips for choosing small and laboratory freeze dryers

 Commonly used names for small freeze dryers are: laboratory freeze dryers, experimental freeze dryers, small freeze dryers, small freeze dryers, laboratory freeze dryers, laboratory vacuum freeze dryers, small vacuum freeze dryers , Experimental freeze dryer, experimental freeze dryer, etc.

 Vacuum freeze-drying technology is also called freeze-drying technology, which quickly freezes items at low temperatures, and then in a vacuum and low temperature environment, the frozen water molecules in the items are directly sublimated into a process in which water vapor escapes. The product obtained by freeze-drying It is called a lyophilized product, so the lyophilized product will not destroy the original chemical structure and morphology of the sample, and the biologically active material can still restore the conformation and biological function before lyophilization after being re-dissolved. Freeze-drying technology is widely used in the scientific research and production of chemical, food, materials, medicine, biological products and other fields, such as biological products, biochemical drugs; microorganisms and algae; there are also some drying operations for vulnerable and oxidizable substances, such as biological products. Dehumidification preservation of specimens and biological tissues, historical archives, cultural relics, dehumidification of microporous parts, etc. Vacuum freeze dryer is abbreviated as freeze dryer. The basic composition of laboratory series freeze dryer includes vacuum pump, cold trap, freeze-drying chamber, vacuum and temperature control system, and other functional accessories such as multi-manifold, capping device, common type, etc. Factors to consider when choosing a small lyophilizer for laboratory use.

Factors to be considered when choosing a laboratory freeze dryer

1. The choice of the manufacturer The first choice is a strong freeze dryer manufacturer, and has many years of professional experience and professional technology in the production of freeze dryers, and supports non-standard customization and solutions.

2. Cold trap temperature The cold trap is a device that is placed between the freeze-drying chamber and the vacuum pump to trap steam. The lower the temperature of the cold trap, the stronger the capture capacity of the cold trap, but the lower the temperature of the cold trap, the higher the requirement for refrigeration, and the relatively high machine cost and operating cost.

3. The amount of ice that the cold trap can capture is related to the total amount of sublimation of water or other solvents in the laboratory's daily experimental operation samples.

4. Ultimate vacuum The ultimate vacuum reflects the leakage of the freeze dryer and the pumping efficiency of the vacuum pump. The vacuum degree of the experiment operation should be within a reasonable range. The vacuum degree is too high, which is not conducive to heat transfer, and the drying speed drops instead.

5. The freeze-drying machine of the laboratory series of the control display system is mainly used for freeze-drying of materials, small batch production and freeze-drying process condition tests. The control system must have real-time display of freeze-drying process parameters, such as cold trap temperature, vacuum degree, stage time and total process time, etc.; set, modify and effectively execute freeze-drying process procedures; it is recommended to have a communication interface to facilitate data collection and storage .

6. Freeze-drying methods and functions According to specific samples, there are different options for freeze-drying methods. Common laboratory freeze-drying experiments adopt freeze-drying in the freeze-drying cavity or hanging bottle freeze-drying. If the freeze-drying cavity is freeze-dried, you need to buy a freeze-drying cavity, and you need to do the vial freeze-drying and choose a capping Device; if it is a hanging bottle freeze-drying, you should choose a multi-manifold, which is suitable for round-bottomed flasks, wide-mouth filter flasks or ampoules, but pay attention to whether you need to choose the corresponding adapter to combine with; if the samples involved in the user test For both intracavity freeze-drying and external bottle freeze-drying, you can choose a freeze-drying cavity with an external hanging port.

Different experiments and different samples have different functional requirements for the freeze dryer. Generally speaking, for the freeze-drying of food, Chinese herbal medicine, powder materials and other samples, it is generally recommended to use a shelf-type freeze dryer; for the operation of vials, you must choose Freeze dryer with capping device; it is recommended to use the bottle-hanging method for freeze-drying preservation of microbial strains and be sure to choose the ampoule adapter for freeze-drying; if you want to study the freeze-drying process curve, you must choose the controller to support eutectic Point test equipment and software and other working models.

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The single-layer reactor heats up too slowly in winter, what should I do?

The single-layer reactor is an ideal equipment for modern chemical sample, medium sample experiment, biopharmaceutical and new material synthesis. The reaction kettle body is directly heated by the silver film heating piece, so that the materials in the reaction kettle are heated at a constant temperature, and stirring can be provided. The materials are reacted in the reactor, and the evaporation and reflux of the reaction solution can be controlled. After the reaction is completed, the lid and motor part of the single-layer glass reactor are mechanically lifted (electric lift is optional) to facilitate the dumping and discharging of materials, and the operation is extremely convenient.

The single-layer reactor can simultaneously complete high-temperature, low-temperature, and vacuum reaction experiments. The operation is simple and convenient, the reaction process is clear at a glance, and it is convenient to control the reaction process. In the winter, the temperature of the single-layer reactor is too slow, and it takes time and energy. The larger the capacity, the slower the temperature rise! So how should users deal with this problem? In response to this problem, give customers the following suggestions:

1. Properly increase the set temperature of the high-temperature oil bath (high-temperature circulator) to make the single-layer glass reactor accept a higher temperature and shorten the heating time. When the reactivity of the double-layer glass is close to the use temperature, the temperature of the high temperature oil bath (high temperature circulator) is lowered to the actual use temperature.

2. Choose thermal insulation cotton and wrap the single-layer glass reactor to have a thermal insulation effect, which can effectively prevent excessive temperature loss and increase the rate of temperature rise.

For example: the actual use temperature: 100℃, the temperature of the high temperature oil bath (high temperature circulator) can be set to: 120℃, when the temperature of the single-layer glass reactor rises to about 90℃, the high temperature oil bath (high temperature circulation) The temperature is set to the required value: 100°C. It can effectively increase the heating rate and shorten the waiting time.

3. Do not fill up the solution in the single-layer glass reactor at one time, which will affect the heating rate. You can choose to add liquid in batches. The liquid addition is about one-half of the capacity. After the temperature rises to close to the set temperature, the material is added to the kettle. According to the above method, adding liquid in batches can also effectively provide the heating rate!

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What is the use method of the rotary evaporator

Rotary evaporator is a laboratory instrument used to distill and extract materials. The first question that customers should consider after purchasing the instrument is the use of rotary evaporator. This article will ask you to explain the use of rotary evaporator one by one.

The use method of the rotary evaporator is also relatively simple, which is convenient for the staff to operate.

1. Use a hose to connect to the condensate, and use a vacuum hose to connect to a vacuum pump to vacuum.

2. Pour water into the heating tank (using pure water). If you use tap water, please leave it for a day or two before using it.

3. The method of adjusting the angle of the main unit: As long as the main unit and the column connecting screw are loosened, the main unit can be tilted at any angle between 0-45 degrees.

4. Turn on the condensate, turn on the power supply, connect the evaporating flask to the host (don't let go), turn on the vacuum pump to reach a certain vacuum, then release it.

5. The method of adjusting the height of the main unit: press down the pressure bar located at the bottom of the heating tank, adjust the arc left and right to make the main unit reach a suitable position, and then leave the pressure bar to reach the required height.

6. Turn on the speed control switch and the green light is on, adjust the speed knob on the left side of it, and the evaporating flask starts to rotate. Turn on the temperature control switch and the green light is on, adjust the temperature control knob on the left side of the heating tank to start automatic temperature control heating, and the rotary steaming enters the trial operation. Once the temperature and vacuum reach the required range, the solvent can be evaporated to the receiving bottle.

7. Stop the low-temperature coolant circulating pump, stop the heating of the water bath, turn off the circulating water of the water pump, pour out the solvent in the receiving bottle, wash the buffer ball, and the receiving bottle. After steaming, first stop the rotation, then ventilate the atmosphere, then stop the water pump, and then remove the distillation flask

8. After the evaporation is completed, first turn off the speed control switch and the temperature control switch, and press the lower lever to make the host rise. Then turn off the vacuum pump and open the vent valve above the condenser to communicate with the atmosphere. Remove the evaporating flask to complete the evaporation process.

In addition to mastering the use of the rotary evaporator, the user should also master the precautions for rotary steaming: the important point is that the glass should be handled with care, and washed and dried after use; secondly, the heating tank should be filled with water and then energized, and it is strictly forbidden to dry without water. Burning; apply a small amount of vacuum grease evenly before installation of the grinding instrument used; the precious solution should be simulated first to ensure the safety of the experiment; turn off the switch and unplug the power plug at the end of the work