Microwave extraction process
    Under the existing equipment and the tea extract ammonia base , Tan and other production experience , microwave extraction equipment production line mainly consists of four components: pre-treatment , extraction, separation and concentration of the liquid feed system . The following section briefly address four points corresponding process.
    A pretreatment
    1.1 crushing , feeding
With traditional extraction as herbs properly broken , you can increase the contact area is conducive to the extraction proceeds, microwave extraction usually requires according to the characteristics of herbs to be broken into particles 2 10mm , in order to facilitate feeding and inhibit the feeding process dust flying in specialized workshops equipped with feed , after grinding the ingredients put in the feed container, and transported through the conduit to the extraction tank , the use of a vacuum conveyor generally more appropriate .
    1.2 Solvent preheat
Microwave extraction at different temperatures results in a larger difference in exactly the same microwave power , solvents , media, extraction amount, the thermal effect is better than cold extraction , which is not evident in the extraction experiments, the small , but large-scale it is especially important when production .
Considered in the design of solvent using a plate heat exchanger will be heated to a suitable temperature .
    1.3 herbs plus solvent soaked
How much water content is directly related to the operation time , but also directly affect the extraction yield , low moisture content should be taken to the main herbs seeds humidifier measures to effectively absorb microwave energy , can be added in front of the microwave extraction solvent immersion, this operation microwave extraction can be carried out in the tank . Microwave extraction tank from the tank , the role of the cavity microwave , blender, feed inlet , a gate , a microwave source , power conditioning equipment , temperature control devices, pressure control devices and other components . The device with conventional dynamic extraction tank structure is similar, except that the steam jacket heating to microwave heating chamber , the three-dimensional planar heating to heat , heat to the steam jacket wall heat liquid itself . Microwave extraction tank suitable for massive, flaky , granular, powdery material extraction , can be insulated , temperature , atmospheric pressure, positive pressure , negative pressure extraction, herbal extracts and meet different requirements of process parameters . As well as some equipment manufacturers with steam or electric auxiliary heating in the bottom of the tank .
Microwave applications engineering system uses microwave frequencies of 915MHz and 2450MHz, domestic microwave frequencies currently used mostly herbal extracts microwave choose 2450MHz, tank volume 0.5-3m. Due to the limited penetration depth of the microwave , microwave extraction equipment must be equipped with a stirrer , dynamic extraction.
    Microwave extraction under microwave irradiation because of the presence of molecular motion , temperature, and traditional process does not require the same height , plus the time is shortened , so you can reduce the risk of heat damage to the material composition can also save energy.
    In the microwave field , the difference in the microwave absorbing capacity of various materials so that certain regions of the matrix material or extraction system in some of the components are selectively heated , so that the energy difference between the internal substances or potential difference is sufficient to give the material extracted i.e. the power system is separated from the substrate or out .
According microwave extraction tank conditions, we can design it as a dynamic extraction tank , dynamic parameter extraction of microwave extraction tank design approach combines the characteristics of the design.
Using microwave extraction tank , microwave leakage could harm the human body is a focus of attention , a professional manufacturer of industrial machinery and equipment production microwave microwave leakage devices are strictly controlled within national standards , without causing electromagnetic environment pollution will not endanger the health of the operator , in design, we still put the role of warehouse and ancillary microwave device settings within the operating level between the slag surface and separated by a retaining structure and other areas , to ensure safety.
3 liquid material separation, slag
Because herbs organizations with suction capillary action between liquid and powder , solvent residue and difficult separation sucking part . In the conventional extraction plant for ethanol, the water can simply be added to the residue directly above the outlet following release , replacement of the residue in ethanol eluate , and then be recovered by distillation of the organic solvent for some specific , in the extraction blowing steam into the bottom of the tank , which was distilled directly recycled. For microwave extraction solvent consumption compared to conventional extraction due to the decrease of the above issues can not be ignored and therefore the dregs liquid holdup become our proposal directly into the material residue after extraction oscillating sieve residue field from the dregs to the extruder screw extrusion, extraction solution to the centrifuge or filter to collect , reduce the labor intensity and maximum residue collected extract.
    4 Concentration System
Due to the amount of microwave extraction solvent to extract only the traditional 50 % or less , concentrated system specifications can be reduced accordingly , solvent recyclable , saving energy and solvent usage.
    5 Use and suggestions for improvement
    5.1 microwave extraction varieties suitable for the production of a single , crushing herbs need to - particle extraction time is generally 2 ~ 10mm, microwave extraction tank insulation facilities they need .
    5.2 current domestic microwave extraction tank mostly fixed microwave frequency , and different materials for different frequency microwave absorption are quite different , it is recommended to configure the frequency selector.
    5.3 current domestic microwave extraction tank mostly fixed microwave frequency , and different materials for different frequency microwave absorption are quite different , it is recommended to configure the frequency selector. According to the article view, the tank bottom slag microwave extraction method using conventional pipe replacement slagging door more favorable.