CN106153692B - A kind of cereal moisture percentage on-line equipment and its measurement method based on dielectric parameter - Google Patents
A kind of cereal moisture percentage on-line equipment and its measurement method based on dielectric parameter Download PDFInfo
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- CN106153692B CN106153692B CN201610819370.7A CN201610819370A CN106153692B CN 106153692 B CN106153692 B CN 106153692B CN 201610819370 A CN201610819370 A CN 201610819370A CN 106153692 B CN106153692 B CN 106153692B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
- G01N27/221—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance by investigating the dielectric properties
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
- G01N27/223—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance for determining moisture content, e.g. humidity
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
- G01R27/2617—Measuring dielectric properties, e.g. constants
- G01R27/2635—Sample holders, electrodes or excitation arrangements, e.g. sensors or measuring cells
- G01R27/2647—Sample holders, electrodes or excitation arrangements, e.g. sensors or measuring cells of coaxial or concentric type, e.g. with the sample in a coaxial line
Abstract
The present invention relates to a kind of cereal moisture percentage on-line equipment and its measurement method based on dielectric parameter；Including coaxial circles pillar dielectric parameter measurement sensor and controller；Coaxial circles pillar dielectric parameter measurement sensor include from inside to outside sequentially coaxially multilayer nest installation inner electrode assembly, external electrode, teflon insulation layer, shielded layer and polytetrafluoroethylene (PTFE) protective layer；Controller is realized by double-layer shielding coaxial-cable and coaxial circles pillar dielectric parameter measurement sensor and is electrically connected；The present invention by flowing cereal permittivity ε in measurement coaxial circles pillar electrode cavity ', dielectric loss ε " and temperature T calculate cereal moisture percentage, and pass through volume density amendment typeMeasurement error caused by grain measure density fluctuation in electrode cavity is corrected in the scope of application, improves measurement accuracy, realizes the On-line sampling system of flowing cereal moisture percentage.
Description
(1) technical field
The present invention relates to a kind of cereal moisture percentage on-line equipment and its measurement method based on dielectric parameter, belongs to cereal water
Divide line Measurement Technique field.
(2) background technique
Cereal moisture percentage is one of the important indicator of grain quality evaluation, and the detection of cereal moisture percentage is purchased cereal, added
Work etc. all has a very important significance.Cereal moisture percentage is excessively high, easily cause cereal fever, mildew etc., be unfavorable for storage with
Circulation.And cereal moisture percentage is too low, will affect grain quality, reduces the germination percentage of cereal seed.Cereal moisture percentage on-line checking
It is optimization Grain Drying Process control, improves one of bottleneck problem of Quality of Grain Drying.
The detection method of cereal moisture percentage can be divided into two class of direct method and indirect method, and direct method is by drying means or change
Method directly measures the amount of absolute moisture in cereal, and detection accuracy is high, but time-consuming, and requires to operating condition, uncomfortable
Online and in-site measurement is closed, now the Oven Method as cereal moisture percentage examination criteria is direct method.Indirect method is to pass through detection
Physical quantity (conductivity, dielectric constant etc.) related with moisture content, indirect determination cereal moisture percentage can meet online and live
Measurement request, such as electric-resistivity method, capacitance method, Near-Infrared Absorption Method, microwave method and NEUTRON METHOD.Electric-resistivity method is to utilize grain moisture content
Difference, the different principle of conductivity measure cereal moisture percentage, resistance by detecting the variation of broken grains resistance value indirectly
Method equipment cost is lower and on-line measurement easy to accomplish, but stability is more difficult to be met the requirements, and poor to the adaptability of environment.
Near-infrared collimation method is the measurement that cereal moisture percentage is carried out by the energy difference of the projection of measurement near infrared ray and reflection.Microwave method is
Absorption and principle of reflection using water to microwave energy, the phase and amplitude variation by measuring microwave signal carry out moisture content
Detection.Infrared method and microwave method measurement accuracy are high, reproducible, but influence vulnerable to cereal density, thickness etc., and detection device is multiple
Miscellaneous, price is higher.NEUTRON METHOD is to carry out cereal moisture percentage measurement using deceleration principle of the hydrogen atom in hydrone to fast neutron,
NEUTRON METHOD can measure the grain moisture of freezing state, but vulnerable to factors such as cereal density, shapes without destroying grain structure
It influences, and demarcates and safeguard complex, it is difficult to promote.Capacitance method is to lead to its dielectric constant according to grain moisture content difference
Different principles measures cereal moisture percentage by measuring capacitor indirectly, now domestic and international condenser type grain moisture detector is adopted more
Cereal moisture percentage, but the weighing of cereal weight are calculated with cereal capacitance, grain temperature value and cereal weight is measured simultaneously
The application of its on-line continuous measurement aspect is limited, and conventional capacitance method does not consider influence of the dielectric loss to measurement result.
Filler is cereal and air, the as mixing of cereal dry matter, water and air between measuring electrode.Its dielectric ginseng
Number measured value (dielectric constant and dielectric loss) is related with cereal moisture percentage, grain measure density and temperature, therefore using survey
The method detection cereal moisture percentage of amount cereal dielectric parameter need to carry out grain measure density and temperature adjustmemt.
Different cultivars cereal kernel size and skin-friction force difference, same kind different water cut cereal kernel size and
The difference of skin-friction force difference and cereal accumulation or flow regime can all cause cereal porosity i.e. volume in electrode cavity
The variation of density, and the inspection of cereal moisture percentage is carried out by the method for measurement cereal dielectric parameter (dielectric constant and dielectric loss)
Survey need it is different to cereal (same kind identical moisture content) accumulation or flow regime caused by volume density fluctuation be modified.
Static grain measure density fluctuation can (such as fixed volume cereal be freely fallen by unified charge mode when static measurement
Body charge) and it weighs cereal weight and corrects, but on-line weighing cereal weight under static measurement real-time is poor and complex working condition
Difficulty is larger, is difficult to realize real water ratio on-line real time measuring；Flowing grain measure density fluctuation is except logical when dynamic measures
Uniform and stable limit of grain stream in coordination electrode cavity is crossed to be similarly difficult to through cereal weight in real-time measurement electrode cavity outside
Amount is further corrected.
Cereal dielectric parameter measurement electrode mainly includes parallel-plate electrode and plane plate electrode etc., wherein between plane plate electrode
It for open electric field, is interfered vulnerable to external electromagnetic field, is not suitable for being applied to cereal moisture percentage on-line checking actual condition.And parallel-plate
Electrode is influenced relatively large by edge effect, and cereal mobility between parallel-plate electrode is poor, and it is aqueous in cereal to limit it
Application in terms of rate on-line checking.
Cereal moisture percentage on-line checking is also contemplated that the actual working conditions such as ambient humidity, dust and electromagnetic interference influence.
(3) summary of the invention
To solve the above-mentioned problems, the cereal moisture percentage on-line equipment that the present invention provides a kind of based on dielectric parameter and its
Measurement method；The present invention can adapt to the complex working conditions such as dusty, high humility and electromagnetic interference, by measuring cereal dielectric constant
And dielectric loss realizes the on-line real-time measuremen of flowing cereal moisture percentage, and cereal in electrode cavity can be corrected in the scope of application
Measurement error caused by volume density fluctuates.
The technical scheme adopted by the invention is that：
A kind of cereal moisture percentage on-line equipment based on dielectric parameter, including coaxial circles pillar dielectric parameter measurement sensor
And controller；The coaxial circles pillar dielectric parameter measurement sensor include from inside to outside sequentially coaxially multilayer nest installation it is interior
Electrode assembly, external electrode, teflon insulation layer, shielded layer and polytetrafluoroethylene (PTFE) protective layer；The inner electrode assembly is by half
The identical interior electrode of diameter, two insulation spacers and two equal potential belt electrode compositions；One, interior electrode both ends insulation spacer is electrical
It is influenced respectively with an equipotential ring electrode equipotential link with eliminating edge effect after insulation；The external electrode and interior electrode group
Length (i.e. interior electrode, two insulation spacers and the two equipotential ring electrodes of part coaxial placement, external electrode length and inner electrode assembly
The sum of length) it is equal；It is equipped with gap between inner electrode assembly and external electrode and constitutes column type electrode cavity, that is, dielectric parameter survey
Measure electric field；The controller is electrically connected by double-layer shielding coaxial-cable and the realization of coaxial circles pillar dielectric parameter measurement sensor
It connects, the dielectric parameter of cereal in coaxial circles pillar electrode cavity is measured；Shielded layer lower end ground connection, shielded layer length are bigger
In external electrode length, to shield the electromagnetic interference of outer bound pair dielectric parameter measurement electric field；It is arranged between shielded layer and external electrode poly-
Tetrafluoroethene insulating layer, to realize electric insulation；The polytetrafluoroethylene (PTFE) protective layer passes coaxial circles pillar dielectric parameter measurement
Damp proof, proofing dust and protecting is carried out inside sensor.The coaxial circles pillar dielectric parameter sensors topside and bottom are equipped with Method for Installation
Blue disk；Mounting flange is used to coaxial circles pillar dielectric parameter sensor being mounted on grain drying machine, to ensure that cereal contains
The real-time and accuracy of water rate measurement.
The coaxial circles pillar dielectric parameter measurement sensor internal Grain flow channel is divided into top breeze way, column type
Electrode cavity and lower buffer section；The coaxial circles pillar dielectric parameter measurement sensor feed inlet to external electrode top edge is upper
Portion's breeze way, external electrode top edge to external electrode lower edge are column type electrode cavity, external electrode lower edge to coaxial circles pillar
Dielectric parameter measurement sensor discharge port is lower buffer section, and top breeze way and lower buffer section can improve column type electrode appearance
The uniformity and stability of intracavitary grain stream.
The polytetrafluoroethylene (PTFE) column is by being vertically connected with polytetrafluoroethylene (PTFE) upper pillar stand and polytetrafluoro together by screw thread
Ethylene lower pillar stand composition；Polytetrafluoroethylene (PTFE) lower pillar stand lower end, which is connected through a screw thread, is mounted on polytetrafluoroethylene (PTFE) shielded layer pedestal
On crossbeam, it play fixed supporting role；Inner electrode assembly is nested in polytetrafluoroethylene (PTFE) column outer surface, inner electrode assembly outer surface and
Polytetrafluoroethylene (PTFE) upper pillar stand flush with outer surface；External electrode is nested in teflon insulation layer inner surface, external electrode inner surface and
Insulating layer inner surface is concordant；Teflon insulation layer is divided into insulating layer pedestal and insulating layer upper cover, to facilitate external electrode and screen
Cover the installation of layer；Shielded layer is nested in teflon insulation layer outer surface, shielded layer and teflon insulation layer outer surface
Concordantly；Polytetrafluoroethylene (PTFE) protective layer is located on outside polytetrafluoro insulating layer dimly, is shielded to inside.It is inner electrode assembly, outer
Electrode, shielded layer and polytetrafluoroethylene (PTFE) protective layer are the different round tube shape structure of diameter.
The lower buffer section is equipped with the temperature sensor being connected with controller, for measuring grain temperature.
The double-layer shielding coaxial-cable realizes the anti-interference transmission of signal using equipotential and ground connection dual shield；It is described
Signal inner core that double-layer shielding coaxial-cable is set gradually from inside to outside, inner insulating layer, internal shield, external insulation layer, external shield
Layer and protective layer composition, signal inner core and internal shield equipotential link, external shielding layer ground connection realize the anti-interference biography of signal
It is defeated.
In use, coaxial circles pillar dielectric parameter measurement sensor utilizes top mounting flange as cereal circulation passage
Being installed on grain drying machine with bottom mounting flange is suitable for place (at such as continous way grain drying machine grain discharging opening and Cirulation type grain
Dryer recycles at grain-entering mouth), the uniform and stable grain stream that flow velocity is consistent with grain drying machine row's grain speed is by coaxial circles
Pillar dielectric parameter measurement sensor feed inlet flows into, and flows through after electrode cavity by coaxial circles pillar dielectric parameter measurement sensor
Discharge port outflow, the permittivity ε of cereal in controller real-time measurement electrode cavity ', dielectric loss ε " and grain temperature value
T, and then realize the On-line sampling system of flowing cereal moisture percentage.
The cereal moisture percentage On-line Measuring Method based on dielectric parameter that the present invention also provides a kind of, when cereal from top to bottom
Coaxial circles pillar dielectric parameter measurement sensor is flowed through, temperature sensor measures grain temperature T；Controller continuous acquisition column type
Permittivity ε ' (the measurement frequency range f=0.3~300MHz) of flowing cereal, dielectric loss ε " (measurement frequency in electrode cavity
Rate range f=0.3~300MHz) and temperature value T, by volume density amendment typeSubstitute into the regression formula demarcated in advance
And temperature correction is carried out using temperature value T, realize the On-line sampling system of flowing cereal moisture percentage.
The regression formula demarcated in advance is as follows：
In formula：M is cereal moisture percentage (%), and ε ' is cereal dielectric constant, and ε " is cereal dielectric loss, and A and B are that volume is close
Amendment type coefficient is spent,To demarcate regression formula, T is grain temperature, and f is measurement frequency.
The ε ', ε ", A and B, f can be obtained by controller, and wherein ε ', ε " are controller measured value, and A and B, f are to survey
It controls device internal processes preset value and needs artificial setting.The fixed value that the rating test that A and B, f can be done by early period obtains, so
Artificial setting is input to controller afterwards, and controller realizes that cereal contains according to ε ', the ε " that A and these fixed values of B, f and measurement obtain
The measurement of water rate.
Compared with prior art, the present invention has the following advantages and beneficial effects：
1, the present invention by measurement coaxial circles pillar electrode cavity in flowing cereal permittivity ε ', dielectric loss ε " and
Temperature T calculates cereal moisture percentage, and passes through volume density amendment typeCereal in electrode cavity is corrected in the scope of application to hold
Measurement error caused by product density fluctuation, improves measurement accuracy, realizes the On-line sampling system of flowing cereal moisture percentage；
2, the present invention is improved anti-interference using technologies such as equal potential belt, the transmission of double layer screen signal and electrode cavity electrostatic screens
Ability reduces measurement error, while using polytetrafluoroethylene (PTFE) protective layer to coaxial circles pillar dielectric parameter measurement sensor internal
Damp proof, proofing dust and protecting is carried out, the complex working condition at grain-drying scene dusty, high humility and high electromagnetic interference is suitable for.
(4) Detailed description of the invention
Fig. 1 is the work flow diagram of the cereal moisture percentage On-line Measuring Method of the present invention based on dielectric parameter；
Fig. 2 is coaxial circles pillar dielectric parameter measurement sensor cross-sectional view of the present invention (teflon insulation layer bottom
Seat crossbeam is axial)；
Fig. 3 is coaxial circles pillar dielectric parameter measurement sensor cross-sectional view of the present invention (teflon insulation layer bottom
Seat beam vertical direction)；
Fig. 4 is teflon insulation layer upper cover of the present invention and external electrode, shielded layer sectional arrangement drawing；
Fig. 5 is teflon insulation layer pedestal of the present invention and external electrode, shielded layer sectional arrangement drawing；
Fig. 6 is polytetrafluoroethylene (PTFE) column of the present invention and inner electrode assembly sectional arrangement drawing；
In figure：1. teflon insulation layer, 2. polytetrafluoroethylene (PTFE) columns, 3. external electrodes, 4. shielded layers, electrode group in 5.
Part, 6. polytetrafluoroethylene (PTFE) protective layers, 7. temperature sensors, 8. equipotential ring electrodes, 9. insulation spacers, electrode in 10., 11. chargings
Mouthful, 12. discharge ports, 13. crossbeams, 14. top mounting flanges, 15. top breeze ways, 16. electrode cavities, 17. lower buffers
Section, 18. bottom mounting flanges, 19. teflon insulation layer upper cover, 20. teflon insulation layer pedestal, 21. poly- four
Vinyl fluoride upper pillar stand, 22. polytetrafluoroethylene (PTFE) lower pillar stands.
(5) specific embodiment
Embodiment 1：Attached drawing is one embodiment of the present of invention, but is not intended to limit the scope of the invention, below with reference to attached
Figure introduces specific implementation method of the invention.
As shown in Figure 1, the cereal moisture percentage On-line Measuring Method described in the present embodiment based on dielectric parameter is, cereal is from upper
Concentric cylinder formula dielectric parameter measurement sensor is flowed through under and, flows paddy in controller continuous acquisition coaxial circles pillar electrode cavity
The permittivity ε of object ' (measurement frequency range f=0.3~300MHz), dielectric loss ε " (measurement frequency range f=0.3~
300MHz) and temperature value T, by volume density amendment typeSubstitute into the regression formula demarcated in advance and using temperature value T into
Trip temperature correction, realizes the On-line sampling system of flowing cereal moisture percentage.
The regression formula demarcated in advance is as follows：
In formula：M is cereal moisture percentage (unit：%), ε ' is cereal dielectric constant, and ε " is cereal dielectric loss, and A and B hold
Product density revision formula coefficient,To demarcate regression formula, T is grain temperature, and f is measurement frequency.
As shown in Figure 2-5, the cereal moisture percentage on-line measurement device described in the present embodiment based on dielectric parameter, including it is same
Axial cylindrical formula dielectric parameter measurement sensor and controller, the coaxial circles pillar dielectric parameter measurement sensor are coaxial multi-layer
Nested structure, by inner electrode assembly, external electrode, polytetrafluoroethylene (PTFE) column, teflon insulation layer, shielded layer, polytetrafluoroethyl-ne
Alkene protective layer composition, the inner electrode assembly are made of interior electrode, two insulation spacers and two equal potential belt electrodes, interior electrode two
Respectively with an equipotential ring electrode equipotential link after insulation spacer electric insulation, eliminating edge effect influences at end, interior electrode,
Insulation spacer is identical as equal potential belt electrode radius and is located on polytetrafluoroethylene (PTFE) column outer surface；The external electrode is embedded in poly- four
On vinyl fluoride insulating layer inner surface, external electrode inner surface is concordant with polytetrafluoroethylene (PTFE) inner insulating layer inner surface, external electrode and interior electricity
Pole component coaxial placement, external electrode length are equal with the sum of interior electrode, insulation spacer and equal potential belt electrode length；Interior electrode and outer
Cylindrical electrode cavity, that is, dielectric parameter measurement electric field is constituted between electrode, (controller can be by existing commercially available part certainly for controller
Row assembling design is completed, and belongs to measurement module, may be implemented according to the prior art, can carry out cereal permittivity ε ', cereal
The measurement of dielectric loss ε " and grain temperature T, and then realize the measurement of cereal moisture percentage) pumping signal is same through double layer screen
Shaft cable loads on interior electrode and external electrode, i.e., measures to the dielectric parameter of cereal in coaxial circles pillar electrode cavity；Institute
It states shielded layer and is embedded in teflon insulation layer outer surface, shielded layer outer surface and teflon insulation layer flush with outer surface,
Itself and external electrode coaxial placement and ground connection, shielded layer length are slightly larger than external electrode length, to shield outer bound pair dielectric parameter measurement
The electromagnetic interference of electric field；The teflon insulation layer is by teflon insulation layer pedestal and teflon insulation layer
Lid forms, and polytetrafluoroethylene (PTFE) column installation crossbeam, teflon insulation are remained at polytetrafluoroethylene (PTFE) shielded layer pan outlet
Layer pedestal and teflon insulation layer upper cover are designed with mounting flange, are convenient for installing；The polytetrafluoroethylene (PTFE) is vertical
Column is made of the polytetrafluoroethylene (PTFE) upper pillar stand being connected through a screw thread with polytetrafluoroethylene (PTFE) lower pillar stand, the polytetrafluoroethylene (PTFE) lower pillar stand
By being threadably mounted on polytetrafluoroethylene (PTFE) shielded layer base crossbeam, it play fixed supporting role, and ensure polytetrafluoroethylene (PTFE) column
With the coaxial assembly of teflon insulation layer；The polytetrafluoroethylene (PTFE) upper pillar stand ring set has interior electrode, insulation spacer and equipotential
Ring electrode has hollow out inside upper pillar stand, and electrode and equipotential ring electrode transmission signal line, upper pillar stand top design in arrangement is facilitated to have
The tip bell of taper, plays the role of being uniformly distributed when cereal is that flows from above to below, to increase grain stream in electrode cavity
The uniformity；The polytetrafluoroethylene (PTFE) protective layer is located on outside teflon insulation layer and shielded layer, to coaxial circles pillar
Dielectric parameter measurement sensor internal carries out damp proof, proofing dust and protecting.The coaxial circles pillar dielectric parameter sensor is as cereal
It is suitable for place's (grain stream is uniform and stable, and flow velocity and main equipment are consistent) that flow channel, which is installed on, to ensure cereal moisture percentage
The real-time and accuracy of measurement.
The coaxial circles pillar dielectric parameter measurement sensor feed inlet to external electrode top edge is top breeze way, dispatch from foreign news agency
Pole top edge to external electrode lower edge is that middle part measures active section, and external electrode lower edge to coaxial circles pillar dielectric parameter measurement passes
Sensor discharge port is lower buffer section, and top breeze way and the effect of lower buffer section are the uniform of grain stream in raising electrode cavity
Degree and stability.
The lower buffer section is equipped with the temperature sensor being connected with controller, for measuring grain temperature.
The double-layer shielding coaxial-cable by signal inner core, inner insulating layer, internal shield, external insulation layer, external shielding layer with
And protective layer composition, signal inner core and internal shield equipotential link, external shielding layer ground connection realize the anti-interference transmission of signal.
In the present invention, the coaxial circles pillar dielectric parameter measurement sensor internal is cylinder, straight up and down, still
Inner electrode assembly is to be nested on column, and interior electrode outer surface and column flush with outer surface, dispatch from foreign news agency are extremely nested in polytetrafluoroethyl-ne
Alkene insulating layer, external electrode inner surface are concordant with polytetrafluoroethylene (PTFE) inner surface；Polytetrafluoroethylene (PTFE) column and teflon insulation layer
Length be greater than the length of inner electrode assembly and external electrode, i.e., namely grain stream is all from top to bottom for sensor internal cavity
Road can be divided into three sections, and from sensor feed inlet to external electrode top edge, this section of cavity two sides are polytetrafluoroethylene (PTFE) material, be
Non- dielectric parameter measurement region is top breeze way；External electrode top edge to external electrode lower edge, this section of cavity two sides are metal
The internal and external electrode of material, i.e. dielectric parameter measurement region are electrode cavity；External electrode lower edge is to sensor discharge port, this section
Cavity two sides are polytetrafluoroethylene (PTFE) material, are also non-dielectric parameter measurement regions, are lower buffer section, top breeze way and lower part
Breeze way can improve the uniformity and stability of grain stream in column type electrode cavity.
Embodiment 2：Using the cereal moisture percentage on-line measurement device and method described in embodiment 1 based on dielectric parameter to jade
Rice and rice moisture content carry out On-line sampling system.
According to rating test early period, determine that the calibration specific accounting equation of regression formula is：
In formula：M is cereal moisture percentage, and ε ' is cereal dielectric constant, and ε " is cereal dielectric loss, and A and B repair for volume density
Formal coefficient,To demarcate regression formula, To demarcate back
The specific accounting equation of formula of making a public possession, C0、C1、C2、C3For the regression coefficient of specific accounting equation, T is grain temperature, and f is measurement frequency
Rate.
Following table is calculating parameter table needed for the calibration specific accounting equation of regression formula：
Calculating parameter table
Using the present invention to corn and rice (the Moisture of Maize range of different volume densities：12.23%-30.67%,
Rice moisture content range：12.29%-22.69%；Corn volume density fluctuation range：32kg/m3-60kg/m3, rice volume is close
Spend fluctuation range：23kg/m3-49kg/m3) moisture content measures.The surveyed moisture content of the present invention is contained with Oven Method measurement standard
Water rate compares, and test result shows to utilize the surveyed moisture content of the present invention and Oven Method measurement standard moisture content absolute error
Maximum value is no more than 0.5%, and effectively has modified measurement error caused by volume density fluctuates, and can satisfy field application and wants
It asks.
The present invention realizes the On-line sampling system of flowing cereal moisture percentage by measurement cereal dielectric constant and dielectric loss,
Measurement accuracy and stability with higher, and grain measure density fluctuation in electrode cavity can be corrected in the scope of application and caused
Measurement error, and can adapt to the complex working conditions such as grain-drying scene dusty, high humility and electromagnetic interference.
Claims (2)
1. a kind of cereal moisture percentage on-line equipment based on dielectric parameter, it is characterised in that：Including coaxial circles pillar dielectric parameter
Measurement sensor and controller；The coaxial circles pillar dielectric parameter measurement sensor includes that sequentially coaxially multilayer is embedding from inside to outside
Cover inner electrode assembly, external electrode, teflon insulation layer, shielded layer and the polytetrafluoroethylene (PTFE) protective layer of installation；The interior electricity
Pole component is made of the identical interior electrode of radius, two insulation spacers and two equal potential belt electrodes；One, interior electrode both ends are absolutely
It is influenced respectively with an equipotential ring electrode equipotential link with eliminating edge effect after edge gasket electric insulation；The external electrode
With inner electrode assembly coaxial placement, the equal length of external electrode length and inner electrode assembly；Between inner electrode assembly and external electrode
Column type electrode cavity, i.e. dielectric parameter measurement electric field are constituted equipped with gap；The controller passes through double-layer shielding coaxial-cable
It realizes and is electrically connected with coaxial circles pillar dielectric parameter measurement sensor, the dielectric of cereal in coaxial circles pillar electrode cavity is joined
Number measures；Shielded layer lower end ground connection, shielded layer length are slightly larger than external electrode length, to shield outer bound pair dielectric parameter measurement
The electromagnetic interference of electric field；Teflon insulation layer is set between shielded layer and external electrode, to realize electric insulation；Described poly- four
Vinyl fluoride protective layer carries out damp proof, proofing dust and protecting to coaxial circles pillar dielectric parameter measurement sensor internal；The concentric cylinder
Formula dielectric parameter measurement sensors topside and bottom are equipped with mounting flange；Mounting flange is used for coaxial circles pillar dielectric
Parameter measurement sensor is mounted on grain drying machine, to ensure the real-time and accuracy of cereal moisture percentage measurement；
The coaxial circles pillar dielectric parameter measurement sensor internal Grain flow channel is divided into top breeze way, the column type
Electrode cavity and lower buffer section；The coaxial circles pillar dielectric parameter measurement sensor feed inlet to external electrode top edge is upper
Portion's breeze way, external electrode top edge to external electrode lower edge are column type electrode cavity, external electrode lower edge to coaxial circles pillar
Dielectric parameter measurement sensor discharge port is lower buffer section, and top breeze way and lower buffer section can improve column type electrode appearance
The uniformity and stability of intracavitary grain stream；
Polytetrafluoroethylene (PTFE) column is stood by being vertically connected under polytetrafluoroethylene (PTFE) upper pillar stand and polytetrafluoroethylene (PTFE) together by screw thread
Column composition；Polytetrafluoroethylene (PTFE) lower pillar stand lower end, which is connected through a screw thread, to be mounted on shielded layer base crossbeam, and fixed support is played
Effect；Inner electrode assembly is nested in polytetrafluoroethylene (PTFE) column outer surface, inner electrode assembly outer surface and polytetrafluoroethylene (PTFE) upper pillar stand
Flush with outer surface；External electrode is nested in teflon insulation layer inner surface, and external electrode inner surface is concordant with insulating layer inner surface；
Teflon insulation layer is divided into insulating layer pedestal and insulating layer upper cover, to facilitate the installation of external electrode and shielded layer；Shielded layer
It is nested in teflon insulation layer outer surface, shielded layer and teflon insulation layer flush with outer surface；Polytetrafluoroethylene (PTFE) is protected
Sheath is located on outside teflon insulation layer, is shielded to inside；Inner electrode assembly, external electrode, shielded layer and poly- four
Vinyl fluoride protective layer is the different round tube shape structure of diameter；
The lower buffer section is equipped with the temperature sensor being connected with controller, for measuring grain temperature；
The double-layer shielding coaxial-cable realizes the anti-interference transmission of signal using equipotential and ground connection dual shield；The bilayer
Screened coaxial cable is by the signal inner core, inner insulating layer, internal shield, external insulation layer, the external shielding layer that set gradually from inside to outside
And protective layer composition, signal inner core and internal shield equipotential link, external shielding layer ground connection realize the anti-interference biography of signal
It is defeated.
2. a kind of measurement method of the cereal moisture percentage on-line equipment based on dielectric parameter as described in claim 1, feature
It is that steps are as follows：
When cereal flows through coaxial circles pillar dielectric parameter measurement sensor from top to bottom, temperature sensor measures grain temperature T；It surveys
Control the dielectric constant of flowing cereal in device continuous acquisition column type electrode cavity, dielectric lossAnd temperature value T, it will hold
Product density revision formulaIt substitutes into the regression formula demarcated in advance and carries out temperature correction using temperature value T, realize flowing cereal
The On-line sampling system of moisture content；
The regression formula demarcated in advance is as follows：
M=F()(T, f)
In formula：M is cereal moisture percentage,For cereal dielectric constant,For cereal dielectric loss, A and B are volume density amendment
Formula coefficient, F () it is calibration regression formula, T is grain temperature, and f is measurement frequency, f=0.3 ~ 300 MHz；
It is described、, A, B and f by controller obtain, wherein、For controller measured value, A, B and f are in controller
Portion's program preset value needs artificially to be arranged；A, the fixed value that B and f is obtained by the rating test that early period is done, then artificially
Setting is input to controller, and controller is obtained according to these fixed values of A, B and f and measurement、Realize cereal moisture percentage
Measurement.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610819370.7A CN106153692B (en) | 2016-09-12 | 2016-09-12 | A kind of cereal moisture percentage on-line equipment and its measurement method based on dielectric parameter |
Applications Claiming Priority (1)
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