Development Of Carbon Monoxide Analyzer For Ships

In nowadays, ships are widely used because of economical and national defence industrydevelopment. The CO and other toxic gases are easily accumulated due to the confinedatmosphere and difficult ventilation aboard the ship. To ensure the health and safety of the crew,it is critically important to accurately and reliably monitor the CO concentration. The aim of thedissertation is to develop a CO analyzer which is suitable for high humidity and vibration. Themain work can be interpreted as follows:According to the investigation of commercial CO analyzers, a non-mechanical-modulation,non-dispersive infrared absorption (NDIR) scheme for CO monitoring is put forward.‘Singlelight and two wavelengths’ technology is used and differential absorption for the quantificationmodel is set up. Using the ratio of reference and measurement signal, the concentration isdeduced, at the same time, the interference by the light source and the detector is eliminated.An electrically modulated IR radiator reflectIR-P1C, two channel single elementpyro-electric detector PYS3228with thermally compensated and a600-millimeter reflection gascell constitute the optical system. Light source modulation circuit is designed by PowerMOSFET IRF7301. Preamplifier and2-order amplifier and filter are designed too. Thermostatcircuit, pressure and temperature measurement circuit is realized.Data processing system is developed based on a high speed digital signal processor. Afterthe analog signal is converted by a16-bit Analog to Digital Converter, they are digitallyprocessed in the DSP. A band-pass-filter filters the fundamental wave-mode out of signals.Afterwards, a low-pass-filter smoothes out the signals. The DSP processes the signals inaccordance with programmed algorithm and a curve corresponding to the concentration is gainedbased on the least square method.Experiment result has shown good detection effects. Measurement range:0~115mg/m~3;Resolution:3.4mg/m~3; Linear error:±3%FS. It has high reliability and stability, can work at90%humidity.