A miniature gas chromatograph for mining with a temperature acquisition circuit

Abstract

To minimize noise in the analog section of the temperature acquisition circuit of a mining micro gas chromatograph, ensuring that voltage changes accurately reflect thermistor variations while avoiding current surges from the digital section's micro gas pump startup / shutdown and solenoid valve opening / closing, this invention proposes a mining micro gas chromatograph with a temperature acquisition circuit. The separation performance of the micro-chromatographic chip is significantly affected by temperature control accuracy. The temperature acquisition circuit collects the voltage across the thermistor of the micro-chromatographic chip, amplifies it, and transmits it to an analog-to-digital converter to convert the analog signal into a digital signal.

Description

Technical Field

[0001] This utility model belongs to the field of gas chromatography technology, and in particular relates to a miniature gas chromatograph for mining with a temperature acquisition circuit. Background Technology

[0002] In coal mine production, spontaneous combustion of coal seams can have a serious impact on safe production. It not only damages various coal mine equipment but also produces toxic and harmful gases that can harm mine workers. Therefore, predicting spontaneous combustion of coal seams is an indispensable part of ensuring safe coal mine production. Since different components of gas are produced at different stages during spontaneous combustion, gas chromatography analysis of these gases is currently the primary method used for predicting spontaneous combustion of coal seams.

[0003] As a core component in predicting spontaneous combustion of coal seams in coal mines, the miniature gas chromatograph for mining is compact in size and, when equipped with an intrinsically safe power supply, easy to carry. It can acquire test results quickly and can be used for on-site analysis in coal mines. The separation performance of the chromatographic chip in the miniature gas chromatograph for mining is greatly affected by the accuracy of temperature control. Simultaneously, it is crucial to minimize the noise of the analog circuitry in the miniature gas chromatograph for mining and improve the signal-to-noise ratio to more accurately reflect temperature changes.

[0004] Temperature control is a critical factor affecting separation efficiency and analytical accuracy in microchromatographic chips. Therefore, there is an urgent need for a micro gas chromatograph with a high-precision, low-noise temperature acquisition circuit to improve the overall performance of the chromatographic system. Utility Model Content

[0005] To minimize noise in the analog section of the temperature acquisition circuit of a mining micro gas chromatograph, ensuring that voltage changes accurately reflect thermistor variations while avoiding current surges from the digital section's micro gas pump startup / shutdown and solenoid valve opening / closing, this invention proposes a mining micro gas chromatograph with a temperature acquisition circuit. The separation performance of the micro-chromatographic chip is significantly affected by temperature control accuracy. The temperature acquisition circuit collects the voltage across the thermistor of the micro-chromatographic chip, amplifies it, and transmits it to an analog-to-digital converter to convert the analog signal into a digital signal.

[0006] A miniature gas chromatograph for mining applications with a temperature acquisition circuit includes a miniature gas pump, a miniature chromatographic chip, an enricher, a miniature gas valve, and a miniature gas detector. The miniature chromatographic chip integrates a thermistor for sensing local temperature changes within the chip, and the temperature acquisition circuit acquires the voltage signal across the thermistor.

[0007] The temperature acquisition circuit includes an operational amplifier. The non-inverting input of the operational amplifier is connected to one end of the voltage sampling point of the thermistor R1 through a resistor R4. The other end of the thermistor R1 is connected to the power input. One end of the voltage sampling point of the thermistor R1 is grounded through a resistor R5.

[0008] The inverting input of the operational amplifier is grounded through resistor R3, and the inverting input is also connected to the output of the operational amplifier through resistor R2, forming a negative feedback circuit.

[0009] The operational amplifier is AD8552, the thermistor has a room temperature resistance of 500 ohms, resistor R4 has a resistance of 1000 ohms, resistor R5 has a resistance of 100 ohms, resistor R3 has a resistance of 1000 ohms, and resistor R2 has a resistance of 4000 ohms.

[0010] The operational amplifier's output terminal IN0 is connected to the input terminal of the analog-to-digital converter (ADC) of the mine-use micro gas chromatograph to realize the digital processing of the temperature signal.

[0011] Using the AD8552 high-precision operational amplifier for voltage amplification enables high-precision voltage amplification. The higher the amplification factor, the greater the voltage per degree Celsius, thus improving the resolution and consequently increasing the accuracy of temperature control.

[0012] At room temperature, the resistance of the thermistor is about 500 ohms. Therefore, the resistance of the voltage divider resistor R5 is 100 ohms. As the temperature rises, the voltage across R5 will decrease, and the output voltage IN0 will also decrease. Therefore, at room temperature, IN0 has the maximum output.

[0013] The input voltage range of the analog-to-digital converter module is 0-5V, so the maximum output of IN0 cannot exceed 5V. In order to make the maximum output close to 5V and improve the accuracy of temperature acquisition, R3 is set to 1000 ohms and R2 is set to 4000 ohms. Attached Figure Description

[0014] Figure 1 Flowchart of a Mining Micro Gas Chromatograph

[0015] Figure 2 Schematic diagram of temperature acquisition and amplification circuit for a miniature gas chromatograph used in mining Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of this utility model. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of this utility model. In the description of this utility model, it should be noted that the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the scope of protection of this utility model.

[0017] The embodiments of this utility model shown below will be described with reference to the accompanying drawings.

[0018] To address the problems existing in the current technology, improve the temperature control accuracy of the mining micro gas chromatograph, control the noise of the analog circuit of the mining micro gas chromatograph, and improve the signal-to-noise ratio to more accurately reflect the collected temperature changes, thereby improving the separation performance of the micro chromatographic chip.

[0019] The mining-use micro gas chromatograph mainly consists of a micro gas pump, an integrated micro chromatography chip, a enricher, a micro gas valve, a micro gas detector, and supporting software systems. The micro gas pump is used for gas intake, the micro gas valve is used for switching gas pipelines, and the micro chromatography chip, using MEMS technology to etch the chromatographic column onto a silicon wafer, significantly reduces its size. The enricher concentrates low-concentration sample gases into high-concentration gases, with enrichment factors reaching hundreds of times. The workflow of the mining-use micro gas chromatograph is as follows: the target gas is drawn into the enricher by the micro gas pump. After the target gas intake is complete, a carrier gas carries the target gas located in the enricher into the micro chromatography chip for separation. The separated gases are then detected one by one by the micro detector. The back-end data processing software processes the data and outputs it as a waveform graph.

[0020] The micro-chromatographic chip consists of a chromatographic column several meters long. When the carrier gas carries the gas to be measured into the chromatographic column, due to the different forces between different gases and the stationary phase, a flow rate difference is formed when the gas flows in the column. After a period of time, the gas flows out of the chromatographic column and is separated.

[0021] like Figure 1As shown, before introducing the analyte gas, the enricher and the microchromatographic chip need to be heated to a specified temperature. Then, the analyte gas is introduced into the enricher for enrichment. After enrichment, the analyte gas, along with the carrier gas, enters the microchromatographic chip for separation. The gas flowing out of the microchromatographic chip is detected by a gas detector, and the display shows the signal waveform of the gas detector in real time. After the test, the carrier gas is introduced for a period of time to carry away any remaining gas in the microchromatographic chip and the enricher, preventing interference with the next test.

[0022] Since the separation performance of a micro-chromatographic chip is greatly affected by the accuracy of temperature control, this invention proposes a mining micro-gas chromatograph with a temperature acquisition circuit. This circuit acquires the voltage across the thermistor of the micro-chromatographic chip, amplifies it, and transmits it to an analog-to-digital converter (ADC) to convert the analog signal into a digital signal. The temperature acquisition circuit in this invention minimizes noise in the analog section, ensuring that voltage changes accurately reflect the thermistor's changes, while minimizing current surges from the digital section's micro-pump start / stop and solenoid valve opening / closing.

[0023] like Figure 2 The diagram shown is a schematic of the temperature acquisition circuit used in the mining micro gas chromatograph of this invention.

[0024] A mining-use miniature gas chromatograph with a temperature acquisition circuit includes a miniature gas pump, a miniature chromatographic chip, an enricher, a miniature gas valve, and a miniature gas detector. The mining-use miniature gas chromatograph also includes a supporting software system. The miniature chromatographic chip integrates a thermistor for sensing local temperature changes, and the temperature acquisition circuit collects the voltage signal across the thermistor.

[0025] The temperature acquisition circuit includes an operational amplifier. The non-inverting input of the operational amplifier is connected to one end of the voltage sampling point of the thermistor R1 through a resistor R4. The other end of the thermistor R1 is connected to the power input. One end of the voltage sampling point of the thermistor R1 is grounded through a resistor R5.

[0026] The inverting input of the operational amplifier is grounded through resistor R3, and the inverting input is also connected to the output of the operational amplifier through resistor R2, forming a negative feedback circuit.

[0027] The operational amplifier is AD8552, the thermistor has a room temperature resistance of 500 ohms, resistor R4 has a resistance of 1000 ohms, resistor R5 has a resistance of 100 ohms, resistor R3 has a resistance of 1000 ohms, and resistor R2 has a resistance of 4000 ohms.

[0028] The output terminal IN0 of the operational amplifier is connected to the input terminal of the analog-to-digital converter (ADC) of the mining micro gas chromatograph to realize the digital processing of the temperature signal.

[0029] This invention relates to a miniature gas chromatograph for mining applications with a temperature acquisition circuit. It employs an AD8552 high-precision operational amplifier for voltage amplification, enabling high-precision voltage amplification. The higher the amplification factor, the greater the voltage per degree Celsius, thus improving the resolution and overall temperature control accuracy.

[0030] At room temperature, the resistance of the thermistor is about 500 ohms. Therefore, the resistance of the voltage divider resistor R5 is 100 ohms. As the temperature rises, the voltage across R5 will decrease, and the output voltage IN0 will also decrease. Therefore, at room temperature, IN0 has the maximum output.

[0031] Since the input voltage range of the analog-to-digital converter module is 0-5V, the maximum output of IN0 cannot exceed 5V. In order to make the maximum output close to 5V and improve the accuracy of temperature acquisition, R3 is set to 1000 ohms and R2 is set to 4000 ohms.

[0032] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of this utility model and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of this utility model should be included within its protection scope. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A mine micro gas chromatograph with temperature acquisition circuit, characterized in that, It includes a miniature air pump, a miniature chromatography chip, an enricher, a miniature gas valve, and a miniature gas detector; the miniature chromatography chip integrates a thermistor to sense local temperature changes within the chip, and a temperature acquisition circuit collects the voltage signal across the thermistor. The temperature acquisition circuit includes an operational amplifier. The non-inverting input of the operational amplifier is connected to one end of the voltage sampling point of the thermistor R1 through a resistor R4. The other end of the thermistor R1 is connected to the power input. One end of the voltage sampling point of the thermistor R1 is also grounded through a resistor R5. The inverting input terminal of the operational amplifier is grounded through resistor R3, and the inverting input terminal is also connected to the output of the operational amplifier through resistor R2, forming a negative feedback circuit. Among them, the thermistor has a resistance of 500 ohms at room temperature, resistor R4 has a resistance of 1000 ohms, resistor R5 has a resistance of 100 ohms, resistor R3 has a resistance of 1000 ohms, and resistor R2 has a resistance of 4000 ohms.

2. The mine-used micro gas chromatograph with temperature acquisition circuit according to claim 1, characterized in that, The operational amplifier is AD8552.

3. The mine-used micro gas chromatograph with temperature acquisition circuit according to claim 1 or 2, characterized in that, The output terminal IN0 of the operational amplifier is connected to the input terminal of the analog-to-digital converter of the mining micro gas chromatograph.

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