Frequency-domain Tera Hertz device and method for monitoring CO concentration in coal spontaneous combustion gas

Abstract

The invention relates to a frequency-domain Tera Hertz device and method for monitoring CO concentration in coal spontaneous combustion gas. The device comprises a coal spontaneous combustibility determinator, an adjusting valve, a pipeline, a purifier, a check valve, a gas chamber, a frequency-domain Tera Hertz generator, a Tera Hertz signal receiver, a computer, a safety valve, a tee, an intelligent vacuum pump, a gas collection bag and a gate valve. The method comprises the steps as follows: vacuumizing the device by the intelligent vacuum pump at first, purifying the coal spontaneous combustion gas generated by the coal spontaneous combustibility determinator by the purifier, keeping the internal pressure of the gas chamber constant by the safety valve, controlling the on / off of the parts in the device by the adjusting valve, the check valve, the gate valve and the like, transmitting Tera Hertz wave with the frequency-domain Tera Hertz generator, absorbing part of Tera Hertz wave by CO when the Tera Hertz wave transmits the gas chamber, then receiving the Tera Hertz wave transmitting the gas chamber with the Tera Hertz signal receiver, calculating the CO concentration according to corresponding formula, and continuously carrying out the steps to realize monitoring of the CO concentration. The device is simple in structure, easy and simple to operate, and high in precision.

Description

technical field [0001] The invention relates to a frequency domain terahertz device and method for monitoring CO concentration in coal spontaneous combustion gas, belonging to the field of coal combustion safety, and is especially suitable for monitoring the CO concentration in coal spontaneous combustion gas. Background technique [0002] Terahertz (THz) is an electromagnetic wave with unique properties and a frequency in the range of 0.1~10 THz (wavelength is 3mm~30μm), which belongs to the category of far-infrared and sub-millimeter waves. Terahertz pulses have high peak power, high resolution, and terahertz rays can penetrate gas-phase substances, so they can be used to detect polarized gases such as carbon monoxide and ammonia. In addition, CO has the largest absorption peak for the terahertz signal at 1.5THz, and other polar molecules (except water vapor) in the coal spontaneous combustion gas have very small absorption peaks at this frequency, so it has an impact on t...

AI Technical Summary

Problems solved by technology

[0004] At present, the most widely used device for measuring the concentration of CO in coal spontaneous combustion gas is mainly a gas chromatograph. The coal spontaneous combustion gas sample is brought into the chromatographic column through the carrier gas for separation. The separated gas components flow out of the chromatographic column and enter the detector. The detector converts its concentration signal into an electrical signal, and after processing, the chromatographic outflow curve is obtained. The concentration of CO can be analyzed by using the chromatographic peak corresponding to CO on the curve, but this device can only be tested after repeated experiments. Obtain ideal measurement results, and during the test, the interval between sample injections needs to be more than 10 minutes, so continuous monitoring of CO concentration cannot be achieved

The Fourier transform infrared spectrometer is mainly composed of an infrared light source, an aperture, an interferometer, a sample chamber, a detector, various infrared mirrors, a laser, a control circuit board and a power supply. The light emitted by the infrared light source is divided into two beams by the interferometer. And produce interference, the interference light signal reaches the detector after passing through the sample chamber, and then processes the signal through Fourier transform to obtain the CO concentration of the gas. Although this instrument can monitor the CO concentration, it can only measure the amplitude information. Moreover, the obtained absorption peak is not sharp enough, and the spectral lines overlap seriously, which makes the detection accuracy of gas concentration low

The ultrasonic detector is mainly composed of a pair of ultrasonic transducers, a sample chamber, a temperature sensor and a signal processing system. During measurement, an ultrasonic pulse is emitted from one transducer to the other, and the propagation time of the pulse in the sample chamber is measured. Then calculate the sound velocity, and then calculate the gas concentration according to the functional relationship between the sound velocity, the temperature measured by the temperature sensor and the mixing ratio of the gas medium, but this instrument is mainly used for gas concentration detection with large flow and large diameter, and It is easily affected by surrounding pressure, temperature, humidity and other factors, and the accuracy is low, so it is difficult to monitor the concentration of CO generated during the spontaneous combustion of small flow coal with high precision

Images