High-precision online dissolved oxygen measuring instrument

Abstract

The invention discloses a high-precision online dissolved oxygen measuring instrument. The instrument comprises a dissolved oxygen sampling circuit, a temperature compensation sampling circuit, an MCU processor and a key display unit, wherein the dissolved oxygen sampling circuit, the temperature compensation sampling circuit and the key display unit are electrically connected with the MCU processor; the temperature compensation sampling circuit is divided into a constant current reference circuit, a differential amplification circuit and a secondary amplification circuit. According to the high-precision online dissolved oxygen measuring instrument, on one hand, in the constant-current reference circuit of the temperature compensation sampling circuit, an electric signal provided by the input end of the constant-current reference circuit is shaped through a logic inverter; after shaping, the waveform noise of the electric signal is small, and the input signal is more stable and reliable; and on the other hand, the differential amplification circuit is used for amplifying the temperature signal, so that the gate current can be completely or partially offset and reduced, the common-mode signal interference is inhibited, the temperature drift of the output signal is greatly reduced, and the measurement precision of the dissolved oxygen is further improved.

Description

technical field [0001] The invention relates to the field of online chemical analysis instruments, in particular to a high-precision online dissolved oxygen measuring instrument. Background technique [0002] With the rapid development of domestic industry and agriculture, water pollution is becoming more and more serious, and it is urgent to monitor and treat sewage. As an important index for evaluating the quality of aqueous solution, the oxygen content in aqueous solution is an essential monitoring item in water quality monitoring. At present, the domestic water quality inspection includes the detection of the oxygen content of the aqueous solution. One is to take the sample to the laboratory for analysis. This detection method has a long detection cycle, time-consuming and labor-intensive, and most of the detection instruments used in the detection use foreign equipment and technology. , foreign equipment is not only expensive and bulky, some of them do not even meet th...

AI Technical Summary

Problems solved by technology

However, the existing dissolved oxygen detectors, on the one hand, basically do not compensate the atmospheric pressure and salinity in the measurement environment; , but most of them use the fixed value compensation method, that is, input a fixed temperature value and substitute it into the formula to calculate the oxygen content of the aqueous solution. The value compensation method is inconsistent with the actual situation, and the measurement result error of the oxygen content in the aqueous solution is still relatively large; while a few existing dissolved oxygen detectors use a dissolved oxygen electrode with a temperature sensor to measure the temperature of the aqueous solution in real time through the temperature sensor. The measurement of the oxygen content of the aqueous solution is compensated in real time, but the temperature signal transmitted by the temperature sensor will also fluctuate with the fluctuation of the aqueous solution during the measurement process. The measurement result is greatly affected by the temperature drift, and the final measured oxygen content of the aqueous solution is still not accurate enough. not stable enough

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