The microwave detection method of moisture contained in coal on mine conveyer belt and equipment
Technical field
The present invention relates to a kind of detection method and equipment of moisture contained in coal.
Background technology
Along with the raising of coal mining intensity and mechanization level, the colliery is when improving output of coal, and the floating coal dust in dust-producing amount and mine operation place also improves greatly.Coal dust has caused great harm for operating personnel and safety in production: coal dust serious harm field worker is healthy on the one hand, the coal dust too high levels danger of gas explosion that lies dormant on the other hand.Facts have proved: moisture in coal content is high more, and the floating amount of its particle is just low more; Moisture in coal content is low more, and the floating amount of its particle is just high more.So coal seam water infusion, coal dust spraying are the important means that increases moisture in coal, reduces floating amount.And how to detect (special transfer point place) moisture in coal content on the conveying belt quickly and accurately, seem extremely important for control the floating of coal particle.Because during coal is in dynamically on the conveying belt,, can cause the floating of large tracts of land coal particle if it is too dry, also be that granule density is too high, can cause a series of problems such as gas explosion.
Down-hole transfer point drop is bigger, causes that very easily coal particle flies upward, if water spray dust blindly certainly will cause great water resource waste; The coal water cut is too much, does not meet relevant criterion, and gives conveying belt load-bearing build-up of pressure (the normal coal water cut standard of country is 2%-4%).If the coal of conveying belt is carried out the online detection of water cut at the transfer point place, when water cut less than 2% the time, knowing needs spraying, when water cut is not known and need be sprayed more than or equal to 2% the time, thereby realize online detection to moisture contained in coal on (transfer point place) conveying belt, when needs are controlled, can carry out Based Intelligent Control.
The method that detects moisture contained in coal at present mainly contains: oven drying method and infrared reflection method.Oven drying method is to measure the direct method of coal water percentage, be traditional, also be the most basic measuring method, the method measuring accuracy height, but since measuring period oversize, so be unsuitable for being used for the detection of moisture contained in coal on transfer point place, the down-hole conveying belt.Infrared reflection method is the variation according to light quantity, both can detect the geometric configuration of surperficial visual defects and measured object, can measure the water percentage of measured object etc. again, the product that is suitable in the production run detects, and easily be automated, but because shaven head is to the having relatively high expectations of sanitary condition, so also be unsuitable for being used for the detection of moisture contained in coal on transfer point place, the down-hole conveying belt.Said method all is not suitable for the detection of moisture contained in coal on transfer point place, the down-hole conveying belt.
Summary of the invention
One of task of the present invention is to provide a kind of microwave detection method of moisture contained in coal on mine conveyer belt.
Two of task of the present invention is to provide a kind of equipment of realizing above-mentioned detection method.
The present invention for realization task one adopts technical scheme is: the microwave detection method of moisture contained in coal on mine conveyer belt, may further comprise the steps: 1) determining of microwave frequency: under the drying regime with after adding water the damping capacity of microwave signal is being tested by coal under the different frequency, determine the absorption maximum frequency of water, thereby determine microwave frequency to be selected microwave signal; 2) determine the relation of coal water percentage and microwave signature attenuation amount: under multiple sample, measure earlier through the microwave attenuation amount behind the conveying belt, the back adopts oven drying method to accurately measure coal water percentage on the conveying belt, the relation curve of coal water percentage on microwave attenuation amount-measuring voltage and the conveying belt in view of the above draws, release formula: Y=aX+b according to relation curve, Y is the damping capacity of the microwave signal of detection after amplifying, a, b are constant, and X is the coal water percentage; 3) carry out error correction: by to the influence of samples such as coal differing heights, variable grain to the coal water cut, The average calculation error; 4) relation curve of match microwave attenuation amount and coal water cut, a of correction formula, b value.This moment, coal water percentage X=(Y-b)/a promptly can draw by the microwave attenuation amount.
The present invention for the technical scheme that realization task two adopts is: realize the equipment of above-mentioned microwave detection method, comprise microwave signal source, metering circuit and detecting circuit; Metering circuit comprises the emission electromagnetic horn and receives electromagnetic horn that detecting circuit comprises isolator, low noise amplifier, microwave detector, dc amplification circuit and signal acquisition processing circuit; Microwave signal source is connected with the emission electromagnetic horn circuit of metering circuit by directional coupler, receiving electromagnetic horn is connected with the isolator circuit, isolator is connected with amplifier circuit in low noise, low noise amplifier is connected with the microwave detector circuit, microwave detector is connected with dc amplification circuit, and dc amplification circuit is connected with signal acquisition processing circuit.
The invention has the beneficial effects as follows: can detect the coal water percentage on the conveying belt fast, and not be subject to the influence of external environment, be fit to the detection of moisture contained in coal on the conveying belt.
Description of drawings
Fig. 1 is the test block diagram of definite microwave frequency of the present invention;
Fig. 2 is the connection block diagram of equipment of the present invention.
Embodiment
Below in conjunction with accompanying drawing the present invention is described in further detail: the microwave detection method of moisture contained in coal on mine conveyer belt, may further comprise the steps: 1) determining of microwave frequency: under the drying regime with after adding water the damping capacity of microwave signal is being tested by coal under the different frequency, determine the absorption maximum frequency of water to microwave signal, thereby determine microwave frequency to be selected, determine that through testing microwave frequency is 9.7GHz, concrete method of testing is seen Fig. 1; 2) determine the relation of coal water percentage and microwave signature attenuation amount: under multiple sample, measure earlier through the microwave attenuation amount behind the conveying belt, the back adopts oven drying method to accurately measure coal water percentage on the conveying belt, the relation curve of coal water percentage on microwave attenuation amount-measuring voltage and the conveying belt in view of the above draws, release formula: Y=aX+b according to relation curve, Y is the damping capacity of the microwave signal of detection after amplifying, a, b are constant, and X is the coal water percentage; 3) carry out error correction: by to the influence of samples such as coal differing heights, variable grain to the coal water cut, The average calculation error; 4) relation curve of match microwave attenuation amount and coal water cut, a of correction formula, b value.This moment, coal water percentage X=(Y-b)/a promptly can draw by the microwave attenuation amount.
Realize the equipment of above-mentioned microwave detection method, comprise microwave signal source, directional coupler, metering circuit and detecting circuit.Signal source frequency is 9.7GHz, about output power 0dBm.Chip adopts the HMC588LC4B of Hittite company, output power+5dBm.Directional coupler is the microstrip line form, and degree of coupling 30dB is used for real time detection signal source output power.Metering circuit is made up of emission electromagnetic horn and reception electromagnetic horn, and the gain of electromagnetic horn is about 8dB, is used for the emission and the reception of signal.
Detecting circuit is made up of isolator, low noise amplifier, microwave detector, dc amplification circuit and signal acquisition processing circuit.The microwave signal that antenna receives is at first passed through isolator and low noise amplifier through after the decay of tested article, is used for improving system's standing wave and improves gain.Carry out detection and amplifier then, be sent to digital signal processing unit and carry out AD conversion and processing, show.Low noise amplifier adopts the NE3210 of NEC Corporation, and it has very low noise figure and high-gain.Microwave detector is selected the AD8319 of AD company for use, and measurement range reaches 10GHz, dynamic range〉40dB.Signal acquisition processing circuit comprises A/D change-over circuit, single-chip microcomputer treatment circuit, digital display circuit.
Except that two electromagnetic horns, all the other all devices are installed in the explosion-proof shell.For preventing that dust from entering antenna and influencing measuring accuracy, antenna adopts organic glass to seal processing.
Certainly, protection scope of the present invention is not limited to the foregoing description, so long as those of ordinary skill in the art is through creatively improving, and just should be within protection scope of the present invention.