Introduction to the characteristics of traditional Chinese medicine pretreatment extraction and concentration equipment
2021-05-25 14:04:07
The pretreatment process of traditional Chinese medicine generally includes the steps of selecting, washing, purifying, cutting, drying and pulverizing the medicinal materials; the extraction process generally includes extraction, concentration, separation (alcohol precipitation/water sedimentation, filtration, centrifugation) and the like. Equipment selection should be carried out according to mainstream products and production processes, and equipment should be used correctly according to the performance and working principle of the equipment. Through the process, it can be seen that in the pre-treatment stage, the quality of the drug and the production cost have been basically finalized. If the production process and equipment performance are not well combined, problems such as unstable product quality, high raw material consumption, and high production cost will occur during the production process. After the processing of the pre-treatment and extraction processes, the medicinal material becomes an intermediate of the drug, and the Zui becomes a drug.
The pretreatment and extraction process of traditional Chinese medicine is a key process in production, and it is also a process that Zui is easily overlooked by managers. Equipment operators do not understand the working principle of the equipment, and it is impossible to use the equipment correctly. Therefore, the organic combination of equipment and production processes and the correct use of equipment are an important part of improving quality and efficiency.
1 pre-treatment equipment
1.1 The surface of the medicine washing machine (Chinese medicine decoction pieces) not only has mud and other debris, but also a large amount of mold. The purpose of the drug is to remove the sediment and most of the mold. At present, most pharmaceutical companies use roller-type washing machines to wash drugs with spray water. Some enterprises use different speeds and water to clean the medicinal materials. When the leaves, stems, roots and slices are used, different cleaning effects will occur.
The washing machine should wash different medicines with different speeds and water spray according to different varieties. Under the premise of washing, try to shorten the time of washing and avoid the loss of active ingredients. It can be modified for the drum type washing machine, and the speed regulating device and the pressurizing device are added to adopt different cleaning methods for different medicines.
1.2 Run-up machine At present, most Chinese medicine pharmaceutical companies are using water-filled vacuum drugs. The working principle of the vacuum moisturizer: vacuum is used to extract the air in the voids of the medicinal fiber, and the water rapidly enters the plant cell tissue through the capillary under negative pressure conditions. The purpose of the medicinal herbs is to allow the dehydrated plant cells to absorb the water from the imported pump, and to create conditions for the extraction process, because the active ingredients in the medicinal materials are generally exchanged under the action of water (or other solvent). Among them, the control of the degree of vacuum can achieve good penetration effect of Zui; control the amount of water can prevent the loss of active ingredients; control the time of the drug can reduce the enzymatic hydrolysis of the active ingredients (there are some corresponding hydrolase in some glycosidic cells, time passed Long partial glycosides will be hydrolyzed).
The use of the drug-running machine should pay attention to: (1) determine different vacuum degrees and time according to different medicinal materials; (2) determine different water addition amount according to different medicinal materials, try to achieve water and drug penetration.
The old-fashioned medicine machine is a water-filled vacuum medicine machine. Due to the poor effect of the medicine, it has been replaced by the vapor phase type medicine machine in recent years. Old equipment can use operation skills to make up for equipment defects. In order to ensure the degree of vacuum, the vacuum can be reduced to Zui in three times (ie, pulsation 3 times), and the water injection pipe can be changed into a drip tray. Improved.
1.3 Drying equipment There are still many pharmaceutical companies that use steam drying ovens and far infrared drying ovens. Due to high energy consumption, low efficiency, and great impact on the working environment (temperature, humidity and dust), it has been gradually replaced by microwave drying and sterilizing machines in recent years. Microwave drying and sterilizing machines are used by more and more enterprises due to their low energy consumption, high efficiency and little impact on the environment. In the pretreatment stage, the microwave sterilization dryer has three main functions: drying, sterilization, and wall breaking.
The principle of microwave heating: First, through "dielectric loss" (dielectric heating). The resonance frequency of a molecule with a permanent dipole in an electromagnetic field of 2450 MHz is extremely high, causing the molecule to rotate at an ultra-high speed, the kinetic energy is rapidly increased, resulting in an increase in temperature; the second is through ion conduction. The ionized substance moves at an ultra-high speed in an ultra-high frequency electromagnetic field, and generates a thermal effect due to friction. The polar molecules (mainly water molecules) are heated and vaporized and then pumped away by the axial fan on the equipment, and the materials are dried.
The principle of microwave sterilization: Microwave sterilization is the result of the combined effect of thermal and biological effects of microwaves. The thermal effect of microwave on bacteria is to denature the protein and cause the bacteria to lose nutrients, reproduction and survival. The biological effect is that the microwave electric field changes the potential distribution of the cell membrane section, affecting the concentration of electrons and ions around the cell, thereby changing the permeability of the cell membrane. Therefore, the bacteria are malnourished, cannot be normally metabolized, the bacterial structure is dysfunctional, and growth and development are inhibited and die. In addition, nucleic acids (RNA) and deoxyribonucleic acid (DNA), which determine the normal growth of bacteria and stable genetic reproduction, are curly-shaped macromolecules that are tightly connected by a number of hydrogen bonds. A sufficiently strong microwave field can cause hydrogen bond relaxation, fragmentation, and recombination, thereby inducing genetic mutations, or chromosomal aberrations, or even breaks. Microwave sterilization dryers use the above functions of microwaves to achieve sterilization. According to the principle of microwave sterilization, attention should be paid to the time when the bacteria are sterilized. If the interval is too short, the damaged bacterial cells will be repaired and the test results will be distorted.
The principle of microwave plant cell wall breaking: the hard cell wall of the plant protects the protoplast and maintains a certain shape of the cell. The main component is cellulose, and the cell wall is unique to plant cells. Plant cells also contain plastids, which are the sites where plant cells produce and store nutrients. Most plant cells contain one or several vacuoles, which are filled with liquid. Polar water molecules in plant cells are mediators of microwave energy. After the Chinese medicine decoction pieces are moisturized, the dehydrated plant cells absorb water and swell, the water molecules in the cells can absorb microwave energy to a large extent, and the water molecules are vaporized under the action of microwave energy to rupture the cells, thereby extracting active components in the plant cells. Created conditions. The purpose of breaking the wall is to obtain the active ingredients in the plant cells. Whether the medicinal materials need to be broken or not is determined according to the target of extraction.
Microwave drying and sterilizing machine should pay attention to: (1) It must not run at no load, otherwise it will burn equipment and even explode; (2) The microwave source should have time record, the life of magnetron is generally around 4000h, and the microwave energy will be attenuated when used overtime. (3) The moisture content of the material below 14% will affect the sterilization effect; when the water content of the extract is higher than 40%, it should be dried by microwave vacuum dryer, and the tunnel microwave dryer may cause damage to the equipment; The penetration depth of microwave to water is about 2~3cm. Pay attention to the thickness of the material during operation; (5) The temperature is usually 80~90°C when drying the material. The higher the temperature, the better the absorption, and the material is too dry or even Carbonization; (6) The medicinal material must be permeable, otherwise the microwave can not be broken (can be cut open). When breaking the wall, the microwave energy should reach the energy and time for vaporizing the water in the plant cells; (7) when both the crushed material and the extract are in the raw material, the extracted and concentrated chemical liquid can be mixed into the crushed material. After microwave treatment, drying and sterilization can be completed at the same time, saving energy and saving time; (8) Microwave equipment used for pre-treatment should use a larger power as much as possible to ensure quality and yield.
1.4 Crushing equipment The pulverizer used by small and medium-sized pharmaceutical companies is mainly TF-400 type Chaitian pulverizer. Its working principle: the machine main shaft is equipped with a plate, a baffle and a fan blade, which are driven by a motor to rotate. The plate and the edge plate and the bending plate embedded on the outer casing constitute a crushing chamber, and the material enters the pulverizer through the feeding port, and through the rapid relative movement therebetween, multiple impacts and collisions are formed on the pulverized material to reach The purpose of crushing. The pulverized material is blown to the cyclone separator by airflow to be air-selected, and then sieved to separate the coarse powder and the fine powder, and the fine powder is sent to the powder collecting device for collecting the powder, and the coarse powder is sent back. The crushing room is re-grinded. In production use, some users feel that the actual production is far from the parameters provided by the manufacturer. In addition to the different types of processing and crushing fineness (screen mesh), an important reason is the incorrect use of circulating water and negative pressure chambers. The temperature of the circulating water is too high or there is no need to circulate water. In addition, the powder collecting device must be placed in the negative pressure chamber, and the fine material after the crushing can smoothly enter the powder collecting device under the action of the air flow. Generally, the single-machine dust removal method can be used to form a negative pressure between the powder collection, and the exhaust, cooling, and dust removal are solved together, and the output is greatly improved. In addition, roughing and mixing the materials to be pulverized before pulverization is also a good way to increase the yield and pulverization effect. Figure 1 is a schematic diagram of its equipment arrangement.
2 extraction and concentration equipment
2.1 The hot reflux extraction unit has a variety of Chinese medicine extraction equipment, each with its own merits. Due to different production processes, the combination of equipment is different. The hot reflux extraction unit is a relatively fast extraction device popularized in recent years.
Features of the hot reflux extraction unit (shown in Figure 2): (1) Combining the three principles of reflux extraction, seepage extraction and Soxhlet extraction of existing extraction equipment, combined with external thermal circulation concentration technology, will extract and concentrate The two processes are concentrated on one equipment at the same time; (2) the secondary steam generated by concentration is continuously sent to the extraction tank as a new heat source for extraction, maintaining the extraction temperature in the extraction tank; (3) extracting a large amount of tanks The steam enters the refluxer and condenses into a hot condensate and falls back into the extraction tank. The new solvent is uniformly applied to the surface of the medicinal material. The new solvent passes through the medicinal material layer from top to bottom, dissolves the soluble substance in the medicinal material to the bottom of the extraction tank, and eliminates the medicinal material. Cold pile, fully extracted. The extract enters the concentration tank, continuously reducing the concentration difference of the liquid medicine in the extraction tank, and the Zui greatly increases the yield of the active ingredient; because the amount of the solvent used is small, the concentrated liquid is less, and the extraction and concentration process takes a short time, saving energy.
Note on the use of the heat return unit: (1) The amount of medicinal material in each tank should be verified by verification. The principle of hot reflux extraction determines that the amount of feed is larger than that of the multi-purpose extraction tank. (2) Determine the time to start reflux based on the concentration of the chemical solution. If the reflux time is too early, the low concentration of the extract will prolong the effective extraction time. The reflux time is too late, and the saturation of the extract concentration is not conducive to the extraction of the active ingredients, and wastes energy. After the extraction (boiling) for 1 h, some of the liquid medicine should be placed in the concentration tank, and the reflux should be started and timed. Note that the air in the tank should be removed when the extraction tank is boiling, otherwise the pressure will be generated in the tank. (3) To control the temperature of the reflux liquid, do not be too low. At the same time, it is necessary to control the temperature inside the extraction tank and try to keep the temperature constant. Cold extraction (below 90 °C) has less impurities, good clarity, high heat extraction efficiency and poor clarity. The purpose of boiling is to enhance the diffusion and osmosis of the solution. Although boiling can narrow the concentration difference of the solution in a short time, many macromolecular impurities are dissolved. The main purpose of reflux is to dynamically reduce the concentration difference of the solution in the extraction tank at a suitable temperature in the form of percolation. Under the action of osmotic pressure, the concentrated solution in the cell is continuously expanded outward, and the extracellular solvent is continuously Enter the cell. (4) Determine the extraction time. Excessive extraction will increase the impurities in the extract to increase the difficulty of the later separation. If the time is too short, the extraction will be incomplete and the raw materials will be wasted (the concentration of the solution should be checked during the extraction process).
Some companies use hot reflux extraction units as multi-function extraction tanks, which is very wrong. Because the extraction tank of the hot reflux unit generally adopts an inverted cone design, the slag removal is convenient, but the bottom is not heated. According to the process of the multi-function extraction tank, the medicine will form a cold pile at the bottom of the extraction tank, reducing the extraction amount of the active ingredients, resulting in waste of the medicine.
2.2 Concentration equipment 2.2.1 Double-effect concentrator Double-effect concentrator (as shown in Figure 3), the secondary steam generated by one steam concentration is concentrated in the next step, and the concentrated liquid is connected in series to achieve a concentrated effect. And so on, its fundamental purpose is to save energy. For example, one-time concentration of one ton of evaporation requires 1.2 tons of steam, two-effect concentration requires only 0.57 tons of steam, and three-effects requires only 0.43 tons of steam. That is, the steam generated by one concentration is used as a secondary concentrated heat source to achieve energy saving. Continuous concentration at low temperature under vacuum conditions is more suitable for heat sensitive materials.
Note on the use of double-effect concentrator: (1) In order to speed up the concentration, vacuum concentration and decompression can be used. The degree of vacuum should be determined according to the nature of the material and the production process; (2) Do not vacuum when recovering organic solvent. Too large to reduce the loss of organic solvents; (3) When the equipment is used as a concentration process, * condenser should not pass into the condensate, otherwise internal reflux will occur, slowing down the concentration rate. When recovering ethanol, * condenser should pass Condensate is added to cause condensation to facilitate the recovery of ethanol; (4) The equipment must be returned to normal pressure during discharge.
2.2.2 Single-effect concentrator (ethanol recovery)
The single-effect concentrator (shown in Figure 4) has a large ethanol recovery capacity, sometimes referred to as an ethanol recycler, but is less energy efficient than double-effect and three-effect concentrators. The equipment adopts the combination of external heating natural circulation and vacuum negative pressure evaporation, and the evaporation speed is fast, the concentration ratio can reach 1.3; the cleaning is convenient (the upper cover of the heater can be cleaned), the operation is simple, and the floor space is small.
The energy consumption of a single-effect concentrator has two main aspects: (1) industrial vapor used to heat the dilute solution in the heater to evaporate the solvent in the solution; (2) when the vaporized solvent vapor is recondensed into a solvent liquid The cooling water required in the condenser. The former needs to supply heat, while the latter needs to take away heat. The solvent vapor produced by the heated solution contains a large amount of heat energy, which is not only not used here, but also consumes a large amount of cooling water to cool it (sometimes to turn on the refrigeration equipment to ensure the cooling effect). The greater the yield, the greater the amount of evaporation required, the more heating steam is required, and the more cooling water is consumed. This is why the single-effect concentrator consumes a lot of energy.
When using the single-effect concentrator, pay attention to: (1) When recovering ethanol, the temperature inside the evaporator should be controlled at about 80 °C. (2) The degree of vacuum should not be too large. If the vacuum is too high, the ethanol will be sucked away, resulting in low recovery rate; if the degree of vacuum is too large, the liquid will be excessively boiled and the liquid will be lost. (3) The temperature of the cooling circulating water should be lower than 40 ° C. The lower the temperature, the better the condensation effect. Under normal circumstances, the ethanol concentration of the single-effect concentrator can reach about 85%, and then refined by the distillation tower can reach 90% to 92%.
3 Conclusion
In short, in traditional Chinese medicine pharmaceutical companies, pre-treatment extraction process is very important. Scientific production processes, suitable production equipment, rigorous operating procedures and the cooperation of experienced operators are indispensable for the production of traditional Chinese medicine.
The pretreatment and extraction process of traditional Chinese medicine is a key process in production, and it is also a process that Zui is easily overlooked by managers. Equipment operators do not understand the working principle of the equipment, and it is impossible to use the equipment correctly. Therefore, the organic combination of equipment and production processes and the correct use of equipment are an important part of improving quality and efficiency.
1 pre-treatment equipment
1.1 The surface of the medicine washing machine (Chinese medicine decoction pieces) not only has mud and other debris, but also a large amount of mold. The purpose of the drug is to remove the sediment and most of the mold. At present, most pharmaceutical companies use roller-type washing machines to wash drugs with spray water. Some enterprises use different speeds and water to clean the medicinal materials. When the leaves, stems, roots and slices are used, different cleaning effects will occur.
The washing machine should wash different medicines with different speeds and water spray according to different varieties. Under the premise of washing, try to shorten the time of washing and avoid the loss of active ingredients. It can be modified for the drum type washing machine, and the speed regulating device and the pressurizing device are added to adopt different cleaning methods for different medicines.
1.2 Run-up machine At present, most Chinese medicine pharmaceutical companies are using water-filled vacuum drugs. The working principle of the vacuum moisturizer: vacuum is used to extract the air in the voids of the medicinal fiber, and the water rapidly enters the plant cell tissue through the capillary under negative pressure conditions. The purpose of the medicinal herbs is to allow the dehydrated plant cells to absorb the water from the imported pump, and to create conditions for the extraction process, because the active ingredients in the medicinal materials are generally exchanged under the action of water (or other solvent). Among them, the control of the degree of vacuum can achieve good penetration effect of Zui; control the amount of water can prevent the loss of active ingredients; control the time of the drug can reduce the enzymatic hydrolysis of the active ingredients (there are some corresponding hydrolase in some glycosidic cells, time passed Long partial glycosides will be hydrolyzed).
The use of the drug-running machine should pay attention to: (1) determine different vacuum degrees and time according to different medicinal materials; (2) determine different water addition amount according to different medicinal materials, try to achieve water and drug penetration.
The old-fashioned medicine machine is a water-filled vacuum medicine machine. Due to the poor effect of the medicine, it has been replaced by the vapor phase type medicine machine in recent years. Old equipment can use operation skills to make up for equipment defects. In order to ensure the degree of vacuum, the vacuum can be reduced to Zui in three times (ie, pulsation 3 times), and the water injection pipe can be changed into a drip tray. Improved.
1.3 Drying equipment There are still many pharmaceutical companies that use steam drying ovens and far infrared drying ovens. Due to high energy consumption, low efficiency, and great impact on the working environment (temperature, humidity and dust), it has been gradually replaced by microwave drying and sterilizing machines in recent years. Microwave drying and sterilizing machines are used by more and more enterprises due to their low energy consumption, high efficiency and little impact on the environment. In the pretreatment stage, the microwave sterilization dryer has three main functions: drying, sterilization, and wall breaking.
The principle of microwave heating: First, through "dielectric loss" (dielectric heating). The resonance frequency of a molecule with a permanent dipole in an electromagnetic field of 2450 MHz is extremely high, causing the molecule to rotate at an ultra-high speed, the kinetic energy is rapidly increased, resulting in an increase in temperature; the second is through ion conduction. The ionized substance moves at an ultra-high speed in an ultra-high frequency electromagnetic field, and generates a thermal effect due to friction. The polar molecules (mainly water molecules) are heated and vaporized and then pumped away by the axial fan on the equipment, and the materials are dried.
The principle of microwave sterilization: Microwave sterilization is the result of the combined effect of thermal and biological effects of microwaves. The thermal effect of microwave on bacteria is to denature the protein and cause the bacteria to lose nutrients, reproduction and survival. The biological effect is that the microwave electric field changes the potential distribution of the cell membrane section, affecting the concentration of electrons and ions around the cell, thereby changing the permeability of the cell membrane. Therefore, the bacteria are malnourished, cannot be normally metabolized, the bacterial structure is dysfunctional, and growth and development are inhibited and die. In addition, nucleic acids (RNA) and deoxyribonucleic acid (DNA), which determine the normal growth of bacteria and stable genetic reproduction, are curly-shaped macromolecules that are tightly connected by a number of hydrogen bonds. A sufficiently strong microwave field can cause hydrogen bond relaxation, fragmentation, and recombination, thereby inducing genetic mutations, or chromosomal aberrations, or even breaks. Microwave sterilization dryers use the above functions of microwaves to achieve sterilization. According to the principle of microwave sterilization, attention should be paid to the time when the bacteria are sterilized. If the interval is too short, the damaged bacterial cells will be repaired and the test results will be distorted.
The principle of microwave plant cell wall breaking: the hard cell wall of the plant protects the protoplast and maintains a certain shape of the cell. The main component is cellulose, and the cell wall is unique to plant cells. Plant cells also contain plastids, which are the sites where plant cells produce and store nutrients. Most plant cells contain one or several vacuoles, which are filled with liquid. Polar water molecules in plant cells are mediators of microwave energy. After the Chinese medicine decoction pieces are moisturized, the dehydrated plant cells absorb water and swell, the water molecules in the cells can absorb microwave energy to a large extent, and the water molecules are vaporized under the action of microwave energy to rupture the cells, thereby extracting active components in the plant cells. Created conditions. The purpose of breaking the wall is to obtain the active ingredients in the plant cells. Whether the medicinal materials need to be broken or not is determined according to the target of extraction.
Microwave drying and sterilizing machine should pay attention to: (1) It must not run at no load, otherwise it will burn equipment and even explode; (2) The microwave source should have time record, the life of magnetron is generally around 4000h, and the microwave energy will be attenuated when used overtime. (3) The moisture content of the material below 14% will affect the sterilization effect; when the water content of the extract is higher than 40%, it should be dried by microwave vacuum dryer, and the tunnel microwave dryer may cause damage to the equipment; The penetration depth of microwave to water is about 2~3cm. Pay attention to the thickness of the material during operation; (5) The temperature is usually 80~90°C when drying the material. The higher the temperature, the better the absorption, and the material is too dry or even Carbonization; (6) The medicinal material must be permeable, otherwise the microwave can not be broken (can be cut open). When breaking the wall, the microwave energy should reach the energy and time for vaporizing the water in the plant cells; (7) when both the crushed material and the extract are in the raw material, the extracted and concentrated chemical liquid can be mixed into the crushed material. After microwave treatment, drying and sterilization can be completed at the same time, saving energy and saving time; (8) Microwave equipment used for pre-treatment should use a larger power as much as possible to ensure quality and yield.
1.4 Crushing equipment The pulverizer used by small and medium-sized pharmaceutical companies is mainly TF-400 type Chaitian pulverizer. Its working principle: the machine main shaft is equipped with a plate, a baffle and a fan blade, which are driven by a motor to rotate. The plate and the edge plate and the bending plate embedded on the outer casing constitute a crushing chamber, and the material enters the pulverizer through the feeding port, and through the rapid relative movement therebetween, multiple impacts and collisions are formed on the pulverized material to reach The purpose of crushing. The pulverized material is blown to the cyclone separator by airflow to be air-selected, and then sieved to separate the coarse powder and the fine powder, and the fine powder is sent to the powder collecting device for collecting the powder, and the coarse powder is sent back. The crushing room is re-grinded. In production use, some users feel that the actual production is far from the parameters provided by the manufacturer. In addition to the different types of processing and crushing fineness (screen mesh), an important reason is the incorrect use of circulating water and negative pressure chambers. The temperature of the circulating water is too high or there is no need to circulate water. In addition, the powder collecting device must be placed in the negative pressure chamber, and the fine material after the crushing can smoothly enter the powder collecting device under the action of the air flow. Generally, the single-machine dust removal method can be used to form a negative pressure between the powder collection, and the exhaust, cooling, and dust removal are solved together, and the output is greatly improved. In addition, roughing and mixing the materials to be pulverized before pulverization is also a good way to increase the yield and pulverization effect. Figure 1 is a schematic diagram of its equipment arrangement.
2 extraction and concentration equipment
2.1 The hot reflux extraction unit has a variety of Chinese medicine extraction equipment, each with its own merits. Due to different production processes, the combination of equipment is different. The hot reflux extraction unit is a relatively fast extraction device popularized in recent years.
Features of the hot reflux extraction unit (shown in Figure 2): (1) Combining the three principles of reflux extraction, seepage extraction and Soxhlet extraction of existing extraction equipment, combined with external thermal circulation concentration technology, will extract and concentrate The two processes are concentrated on one equipment at the same time; (2) the secondary steam generated by concentration is continuously sent to the extraction tank as a new heat source for extraction, maintaining the extraction temperature in the extraction tank; (3) extracting a large amount of tanks The steam enters the refluxer and condenses into a hot condensate and falls back into the extraction tank. The new solvent is uniformly applied to the surface of the medicinal material. The new solvent passes through the medicinal material layer from top to bottom, dissolves the soluble substance in the medicinal material to the bottom of the extraction tank, and eliminates the medicinal material. Cold pile, fully extracted. The extract enters the concentration tank, continuously reducing the concentration difference of the liquid medicine in the extraction tank, and the Zui greatly increases the yield of the active ingredient; because the amount of the solvent used is small, the concentrated liquid is less, and the extraction and concentration process takes a short time, saving energy.
Note on the use of the heat return unit: (1) The amount of medicinal material in each tank should be verified by verification. The principle of hot reflux extraction determines that the amount of feed is larger than that of the multi-purpose extraction tank. (2) Determine the time to start reflux based on the concentration of the chemical solution. If the reflux time is too early, the low concentration of the extract will prolong the effective extraction time. The reflux time is too late, and the saturation of the extract concentration is not conducive to the extraction of the active ingredients, and wastes energy. After the extraction (boiling) for 1 h, some of the liquid medicine should be placed in the concentration tank, and the reflux should be started and timed. Note that the air in the tank should be removed when the extraction tank is boiling, otherwise the pressure will be generated in the tank. (3) To control the temperature of the reflux liquid, do not be too low. At the same time, it is necessary to control the temperature inside the extraction tank and try to keep the temperature constant. Cold extraction (below 90 °C) has less impurities, good clarity, high heat extraction efficiency and poor clarity. The purpose of boiling is to enhance the diffusion and osmosis of the solution. Although boiling can narrow the concentration difference of the solution in a short time, many macromolecular impurities are dissolved. The main purpose of reflux is to dynamically reduce the concentration difference of the solution in the extraction tank at a suitable temperature in the form of percolation. Under the action of osmotic pressure, the concentrated solution in the cell is continuously expanded outward, and the extracellular solvent is continuously Enter the cell. (4) Determine the extraction time. Excessive extraction will increase the impurities in the extract to increase the difficulty of the later separation. If the time is too short, the extraction will be incomplete and the raw materials will be wasted (the concentration of the solution should be checked during the extraction process).
Some companies use hot reflux extraction units as multi-function extraction tanks, which is very wrong. Because the extraction tank of the hot reflux unit generally adopts an inverted cone design, the slag removal is convenient, but the bottom is not heated. According to the process of the multi-function extraction tank, the medicine will form a cold pile at the bottom of the extraction tank, reducing the extraction amount of the active ingredients, resulting in waste of the medicine.
2.2 Concentration equipment 2.2.1 Double-effect concentrator Double-effect concentrator (as shown in Figure 3), the secondary steam generated by one steam concentration is concentrated in the next step, and the concentrated liquid is connected in series to achieve a concentrated effect. And so on, its fundamental purpose is to save energy. For example, one-time concentration of one ton of evaporation requires 1.2 tons of steam, two-effect concentration requires only 0.57 tons of steam, and three-effects requires only 0.43 tons of steam. That is, the steam generated by one concentration is used as a secondary concentrated heat source to achieve energy saving. Continuous concentration at low temperature under vacuum conditions is more suitable for heat sensitive materials.
Note on the use of double-effect concentrator: (1) In order to speed up the concentration, vacuum concentration and decompression can be used. The degree of vacuum should be determined according to the nature of the material and the production process; (2) Do not vacuum when recovering organic solvent. Too large to reduce the loss of organic solvents; (3) When the equipment is used as a concentration process, * condenser should not pass into the condensate, otherwise internal reflux will occur, slowing down the concentration rate. When recovering ethanol, * condenser should pass Condensate is added to cause condensation to facilitate the recovery of ethanol; (4) The equipment must be returned to normal pressure during discharge.
2.2.2 Single-effect concentrator (ethanol recovery)
The single-effect concentrator (shown in Figure 4) has a large ethanol recovery capacity, sometimes referred to as an ethanol recycler, but is less energy efficient than double-effect and three-effect concentrators. The equipment adopts the combination of external heating natural circulation and vacuum negative pressure evaporation, and the evaporation speed is fast, the concentration ratio can reach 1.3; the cleaning is convenient (the upper cover of the heater can be cleaned), the operation is simple, and the floor space is small.
The energy consumption of a single-effect concentrator has two main aspects: (1) industrial vapor used to heat the dilute solution in the heater to evaporate the solvent in the solution; (2) when the vaporized solvent vapor is recondensed into a solvent liquid The cooling water required in the condenser. The former needs to supply heat, while the latter needs to take away heat. The solvent vapor produced by the heated solution contains a large amount of heat energy, which is not only not used here, but also consumes a large amount of cooling water to cool it (sometimes to turn on the refrigeration equipment to ensure the cooling effect). The greater the yield, the greater the amount of evaporation required, the more heating steam is required, and the more cooling water is consumed. This is why the single-effect concentrator consumes a lot of energy.
When using the single-effect concentrator, pay attention to: (1) When recovering ethanol, the temperature inside the evaporator should be controlled at about 80 °C. (2) The degree of vacuum should not be too large. If the vacuum is too high, the ethanol will be sucked away, resulting in low recovery rate; if the degree of vacuum is too large, the liquid will be excessively boiled and the liquid will be lost. (3) The temperature of the cooling circulating water should be lower than 40 ° C. The lower the temperature, the better the condensation effect. Under normal circumstances, the ethanol concentration of the single-effect concentrator can reach about 85%, and then refined by the distillation tower can reach 90% to 92%.
3 Conclusion
In short, in traditional Chinese medicine pharmaceutical companies, pre-treatment extraction process is very important. Scientific production processes, suitable production equipment, rigorous operating procedures and the cooperation of experienced operators are indispensable for the production of traditional Chinese medicine.
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