CN107024502A - A kind of low disturbance constant temperature trace thermal conductivity detector (TCD) of big flow - Google Patents

Abstract

A high flow low disturbance constant temperature trace thermal conductivity detector. The positive and negative poles of the working power supply are respectively connected to the zero-adjusting resistor and the metal base. The two connected metal bases are respectively equipped with heating wire resistors. The upper sides of the two metal bases are respectively equipped with a left output tube and a right output tube. The lower side of the base is respectively fixed with a left serpentine tube and a right serpentine tube. The fixed resistors, zeroing resistors, and fixed resistors connected in series are respectively connected to the A terminal and B terminal of the power supply output. The two metal bases are respectively equipped with series The connected heating wire resistors, the serially connected heating wire resistance terminals are respectively connected to the A terminal and B terminal of the power supply output. Compared with the existing technology: the cost of introducing new technology hot wire will be much lower than the cost of the original device, and because the application of the serpentine tube will greatly reduce the disturbance of the original air flow to the hot wire and reduce the damage rate of the hot wire .

Description

A Large Flow Low Disturbance Constant Temperature Trace Thermal Conductivity Detector

technical field

The invention relates to a large-flow, low-disturbance constant-temperature trace thermal conductivity detector, which relates to the technical field of diffusible hydrogen analysis, and is a detection device capable of detecting the content of trace gas elements in a relatively relaxed environment.

Background technique

At present, most of the thermal conductivity pools use thermistor as the detection unit, which has the disadvantages of narrow detection range, poor linearity, and great influence from the external environment. At the same time, the unfavorable factors such as expensive parts and components will bring problems to large-scale promotion and use. Certain unfavorable factors, especially the detection of trace elements, will greatly affect the accuracy of the detection under low flow conditions.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned defects, make subversive improvements to the above-mentioned deficiencies, not only reduce the cost, but more importantly, it is a high-flow, low-disturbance, constant-temperature trace thermal conductivity detector that maximizes the technology.

Its technology is realized in this way: including fixed resistance, zeroing resistance, fixed resistance, heating wire resistance, left serpentine tube, right serpentine tube, heating wire resistance, working voltage source, left output tube, right output tube, metal base It is characterized in that: the positive and negative poles of the working power supply are respectively connected to the zero-adjusting resistor and the metal base. The metal bases connected to each other are respectively provided with heating wire resistors, and the upper sides of the two metal bases are respectively provided with left output tubes, The right output tube, the left serpentine tube and the right serpentine tube are respectively fixed on the underside of the two metal bases, the fixed resistor, the zero adjustment resistor, and the fixed resistor connected in series are respectively connected to the A terminal and the B terminal of the power output, and the two metal bases There are respectively serially connected heating wire resistors in the seat, and the ends of the serially connected heating wire resistors are respectively connected with the A terminal and the B terminal of the power output.

The obvious advantages and effects of implementing this technology are: the cost of the hot wire introduced with the new patented technology will be much lower than the cost of the original device, and because the application of the serpentine tube will greatly reduce the disturbance of the original airflow to the hot wire, reduce The damage rate of the hot wire.

Description of drawings

Fig. 1 is a structural representation of the present invention,

Among them, 1-fixed resistance, 2-zeroing resistance, 3-fixed resistance, 4-heating wire resistance, 5-left serpentine tube, 6-right serpentine tube, 7-heating wire resistance, 8-working power supply, 9 -Left output pipe, 10-Right output pipe, 11-Metal base.

detailed description

Below in conjunction with accompanying drawing, the present invention will be further described:

See accompanying drawing 1, the positive and negative poles of working power supply 8 are respectively connected to zero-adjusting resistor 2 and metal base 11. The metal base 11 that is connected to each other is provided with heating wire resistance 4 respectively, forming an electric bridge, and the two metal bases 11 The upper side is provided with a left output tube 9 and a right output tube 10 respectively, and the lower sides of the two metal bases 11 are respectively fixed with a left serpentine tube 5 and a right serpentine tube 6, and the fixed resistor 1, the zeroing resistor 2, The fixed resistors 3 are respectively connected to the A terminal and the B terminal of the power supply output. The two metal bases 11 are respectively provided with a heating wire resistor 7 and a heating wire resistor 4 for serial connection. Connect the A terminal and B terminal of the power supply output.

The heating wire resistor 7 and the heating wire resistor 4 adopt a structure in which the heat-resistant solid core has a wire groove on the outer surface of the ceramics, and the heating wire is tightly wound around it.

See accompanying drawing 1, when working, accept control system command, work power supply 8 supplies power, electric bridge works, through electric bridge balance, based on different gases have different thermal conductivities, the heating wire has the characteristic that resistance changes with temperature, when there is a constant When the direct current passes through the heat conduction cell, the heating wire resistance 7 is heated, and the gas enters the heat conduction cell in the metal base 11 through the left serpentine tube 6 and the right serpentine tube 5, and a part of the heat of the heat wire is released due to the heat conduction of the carrier gas. A part of the gas is output from the left output pipe 9 and the right output pipe 10, and the other part is passed to the thermal conductivity pool. When the heat generated by the hot wire reaches a balance with the dissipated heat, the temperature of the hot wire is stabilized at a certain value. The thermal conductivity cell is kept within the set temperature range; the detector effectively overcomes the influence of additional factors caused by the disturbance of the large-flow airflow on the hot wire; at the same time, a serpentine tube is added at the inlet (cold state) of the carrier gas and sample gas Preheating, the control temperature is the same as the system setting temperature, avoiding the impact of temperature difference on the heating wire and the occurrence of condensation, not only avoiding the impact of cold airflow on the heating wire, but also effectively improving the detection accuracy and sensitivity.

After the gas is output from the left output pipe 9 and the right output pipe 10, due to the difference in thermal conductivity between the carrier gas and the binary mixed gas of the components to be measured and the thermal conductivity of the pure carrier gas, the heat dissipation in the measuring cell changes accordingly. There is a difference between the resistance value of the hot wire in the reference pool and the measurement pool hole, the bridge is out of balance, and the detector has a voltage signal output. The greater the concentration of the component to be measured in the carrier gas, the more significant the thermal conductivity of the gas in the measurement cell changes, the more significant the temperature and resistance change, and the stronger the voltage signal. At this time, the output voltage signal is proportional to the concentration of the sample, which is the quantitative basis of the thermal conductivity detector. At the same time, a temperature detection and control system is added to the thermal conductivity pool. After setting the temperature, the pool body remains at the set temperature to ensure a constant temperature. Thereby overcoming the disturbance of the large flow to the hot wire.

Claims (1)

1. A high-flow low-disturbance constant temperature trace thermal conductivity detector, including fixed resistance, zeroing resistance, fixed resistance, heating wire resistance, left serpentine tube, right serpentine tube, heating wire resistance, working voltage source, left The output tube, the right output tube, and the metal base are characterized in that: the positive and negative poles of the working power supply are respectively connected to the zero-adjusting resistor and the metal base. The upper side is respectively equipped with a left output tube and a right output tube, and the lower sides of the two metal bases are respectively fixed with a left serpentine tube and a right serpentine tube. After series connection, the fixed resistor, zero adjustment resistor, and fixed resistor are A The two metal bases are respectively provided with series-connected heating wire resistors, and the series-connected heating wire resistance terminals are respectively connected to the A-terminal and B-terminal of the power output.