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Brief Analysis of Thermal Reflux Technology
Release time: January 12, 2021Views: 1269

Compared with the traditional extraction production method, the extraction method has the advantages of high extraction efficiency, energy saving, simple operation and short time.

Disadvantages:

1, under the conditions of atmospheric production and conventional extraction of the same, long high temperature on the impact of drug quality;

2, the solvent ratio of the other solvent extraction reflux higher concentration, the need to re-allocation to return;

3, in atmospheric pressure extraction decompression enrichment process need to use the buffer tank to change the decompression to atmospheric pressure in order to reflow, the need for frequent operator operation, an increase of labor intensity.

Single-tank production mode:

First, the atmospheric pressure heat reflow production unit:

It is composed of extraction tank, condenser and concentrator. The working principle is normal pressure extraction method. By using the difference between the extraction tank and the concentrator, the high-concentration low-level natural flow is concentrated to the concentration, then evaporated and condensed to reflux. , The formation of a natural cycle of production, unmanned operation. Its set percolation, such as counter-current process as a whole;

Second, the atmospheric pressure extraction vacuum concentration of heat Reflux production unit:

It is composed of extraction tank, condenser, concentrator and solvent buffer tank. The working principle is normal pressure extraction, vacuum concentration, concentrated evaporation, condensing, recovering to buffer tank and breaking vacuum (or concentration) to reflux. Flow, upstream and other processes as a whole;

Third, the atmospheric pressure extraction vacuum concentration of heat Reflux production unit II:

It is composed of extraction tank-condenser-concentrator-solvent buffer-mixing tank-negative pressure pump. The working principle is normal pressure extraction-vacuum concentration-concentration evaporation to condensate recovery to buffer tank and then through negative pressure pump (or concentration) Vacuum direct pump back to the extraction (liquid into the tangent way) to form a dynamic mixing effect, the set of dynamic, countercurrent, percolation and other processes as a whole; without damage to the state of the vacuum does not affect the system to keep the equipment running best effect ,Improve work efficiency.

More than a single-tank production model, multi-tank heat reflux technology is still relatively rare in the actual production, multi-tank double decompression concentrated heat reflux technology manufacturers use even less, I would like to focus on here to introduce such production technology.

Multi - tank Heat Reflux Technology

Multi-tank countercurrent extraction we are more familiar with, and the technology in the domestic application is also more.

Usually the general pharmaceutical production will not choose a single production process to finalize equipment. Mostly a set of equipment to the service of different production processes.

At present, most of the production process manufacturers to adopt the traditional intermittent extraction process, percolation production process, heat backflow production process, most enterprises choose equipment to meet the needs of the production process, the universality of its wide.

These are often the design requirements will be high, large-scale production enterprises should be designed to extract a single tank can operate independently, can also produce more than run, the key is concentrated selection, configuration and evaporation capacity.

Heat reflux is the key to return flow! Usually the static extraction process of the total solvent production ratio of 1: 14-18, extraction and concentration of production time is generally completed in 8-10 hours (shipping, feeding, adding solvent, heating extraction - liquid - slag - cleaning); heat reflux ratio is generally 1:10, extraction and concentration of production time is 4-4.5 hours is half the time of traditional production. The reflux flow control in the dosage of about 10 times.

Two-tank two-way external circulation heat extraction (referred to as double-tank technology) is a kind of both can achieve the traditional mode of production, but also to achieve a modern production mode of extraction technology.

Features are as follows:

1, can achieve dynamic, percolation, heat reflux and other extraction process in one;

2, can maintain the independence of the traditional single-tank production, but also to achieve the simultaneous production of two-tank group;

3, can be dynamic extraction of low temperature external circulation;

4, can be two-way continuous extraction of two-pot, increase production capacity;

5, energy saving, consumption;

6, to improve production efficiency;

Production Technology of Multi - tank Double - effect Heat Reflux

Its overall composition is: multiple extraction - multiple condensing - multiple pumps - a double effect - a negative pressure pump - a solvent reflux casing preheater and other components;

The working principle is: multiple extraction at the same time feeding - at the same time by adding the proportion of the solvent - while heating extraction (pump cycle until boiling) - dimensional boiling 30 minutes after the extraction of liquid (pump flow to match with the liquid flow) Into the 80 degrees of the solvent until the concentration of evaporation of the solvent reflux, double-effect concentrated recovery solvent (a two effect) mostly at 75 degrees in the preheater to 80 degrees or more through circulation, extraction tank boiling off jacket steam heating, Extraction of the bottom of the heating to maintain the normal extraction; and then concentrated by the reflux solvent for recycling production (extraction 1 - extract 2 - enrichment - pump - preheat - extraction 1)

Process characteristics

Heat reflux method is a hot dipping method, because the solvent recycling, reflow method than the percolation method of the solvent with less, more complete extraction. As the refluxing extraction requires continuous heating, the leaching solution is heated for a long time, so it is not suitable for the leaching of heat-sensitive active ingredients. Usually used for hard texture, extraction of Chinese medicine raw materials more difficult leaching treatment.

The difference between recirculation and reflow hot-dip method is that the refluxing hot-melt solvent can only be recycled, the extracted solute is still in the extractor, can not be continuously updated; and circulating reflux cold soak solvent can be recycled, The solvent is renewed, the extracted solute is continuously removed from the extractor, and the extraction is complete, so the amount of the solvent is the least. In order to avoid the reflow method of continuous leaching liquid heating damage, the choice of appropriate evaporation device, can be partially overcome this shortcoming.

Continuous countercurrent extraction process

The foregoing is primarily a single-stage contact leaching process whereby the leaching of the medicinal material is usually performed in the same extraction unit using fresh solvent or leachate as the solvent. But the diffusion of solute must follow the law from high concentration phase to low concentration phase transfer direction, that is, the fundamental driving force of diffusion is the concentration difference of the active ingredients in the medicine and solvent, diffusion occurs only in the presence of concentration difference condition. Resulting in leaching. However, in the single-stage leaching process, due to the inherent limitations of the process, the concentration difference required for the diffusion can not be maintained stably, and the equilibrium conditions of the solid-liquid mass transfer can not be fundamentally changed even by mechanical stirring or forced circulation, , The fluid coefficient, equipment volume, energy consumption and other process indicators is not ideal. In order to overcome these shortcomings, in the current production of traditional Chinese medicine, the application of chemical mass transfer principle, proposed a multi-stage continuous countercurrent leaching process, the solvent and material contact order for its active ingredient content from low to high direction of reverse movement, the main common A tank group countercurrent leaching process and continuous leaching process.

Countercurrent Extraction Process of Tank

In order to overcome the shortcomings of conventional extraction methods such as high solvent consumption, high extraction temperature and low productivity, a series of multi-stage semi-continuous extraction process is adopted. The multiple extraction units are rationally combined, and solid-liquid contact mass transfer The process is simultaneously carried out simultaneously in a plurality of leaching units. Through the process configuration and adjustment, the concentration gradient of each unit is rationally arranged, the countercurrent mass transfer principle is introduced, and the fresh solvent is firstly introduced into the extraction unit with the lowest active component content, so that the extraction time is shortened and the amount of solvent is reduced to a maximum extent. Extraction of active ingredients in traditional Chinese medicine materials.

Multi-tank countercurrent extraction method is characterized by:

1) The system is flexible, the extraction unit can be used independently, can also be combined to run, continuous countercurrent extraction operation.

2) The solid-liquid contact of the tank-type countercurrent extraction is carried out in different extraction units at the same time. Although the raw materials of Chinese medicine do not move between the tanks, the counter flow operation can be realized by the process configuration and the process adjustment. The extraction unit obtains a suitable concentration gradient.

3) Under the combined process, the solvent of each extraction unit participates in the extraction process of all extraction tanks, that is to ensure the concentration gradient required for mass transfer, but also to achieve the application of solvent, reducing the amount of solvent, greatly reducing the volume of leaching solution , To reduce the workload of the subsequent separation and concentration process.

4) The requirements of raw material pretreatment and single-stage leaching is about the same, through a flexible process configuration and adjustment to obtain better raw material adaptability and operating parameters, access to the best extraction results, and the operating unit can be flexibly take appropriate Of the leaching process, such as mechanical mixing, temperature dip, percolation and so on.

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