This dissertation is devoted to developing an integrated unit for environmental monitoring based on novel sensor devices for gas detectors and analyzers, which are used for diagnostics, calibration, prediction of technogenic risks, and determination of hazardous gas concentrations in the air. The aim of the dissertation was to develop functionally simple, reliable sensor devices and integrate them to environmental safety systems. To produce multi- and mono-sensor gas analyzers, capable of complex environmental monitoring in terms of safe human exposure or safe technological processes, reliable devices providing information about the condition of strategic works (water-, oil- and gas pipelines, etc.) should be available. In Ukraine, single sensors have been developed so far, but there is no manufacture of integrated units of sensor devices incorporating sensing elements, primary converters, autonomous micro-generators and block-modules. Based on the sensor devices developed in this work, production of portable and fixed gas analyzers or automated fixed systems of continuous monitoring of atmosphere can be launched. Such sensor devices and equipment based on them are of paramount importance to increase the safety in the confined space of industrial and communal enterprises. Taking into account modern tendencies, achievements and standards in this sphere, a novel two-electrode chlorine sensor working in different ranges (from 5 to 25000 ppm) and a three-electrode hydrogen sulfide sensor (from 1 to 100 ppm) were made. By their specifications, these sensors compare favourably with their foreign counterparts, the chlorine and hydrogen sulfide micro-generators take precedence in the world, whereas the block-modules do not have analogues at all. The sensors developed offer continuous performance for 2 years in the air at relative humidities from 10 to 90 %, at temperatures from –30 to +50 0С. Metrological characteristics of the chlorine sensors based on a solid electrolyte and the hydrogen sulfide sensor based on a matrix electrolyte were determined. Solid electrolytes were synthesized and studied, and specimens with a resistance of R = 9 Оhm and conductivity of æ = 1,6∙10-4 Оhm-1∙сm-1 were selected. The sensors without preliminary preparation (activation) measure the concentration of gas pollutants for chlorine (from 0 to 25000 ppm), for hydrogen sulfide ( from 0 to 100 ppm) with a response time (up to 90 % of the signal) less than 15 s or recovery time (up to 95 % of the signal) less than 30 s. The absolute error does not exceed +15. Comparative analysis of the sensors with their foreign counterparts manufactured by leading companies showed that the sensors compare favourably in terms of selectivity, speed of response, life cycle, and dynamic range on both mg/m3 and g/m3 levels, which enables their use in multi-channel gas analysers and their integration into the system of environmental safety. Chlorine and hydrogen sulfide micro-generators, on passing direct current, yield 100 % of chlorine gas and 99,6 % of hydrogen sulfide for current, respectively. Laboratory and industrial specimens of sensing elements, sensors, autonomous micro-generators and block-modules (sensor/micro-generator) were made. Such an idea enabled remote checking, calibration and seasoning of the devices as well as creating instrumentation based on them to monitor the levels of air pollution with toxic gases. The developed low-cost chlorine and hydrogen sulfide sensors proved to be competitive with their foreign counterparts. A range of domestic gas analysers were produced for monitoring harmful emissions at fuel industry enterprises, controlling purification of emissions from heat plants and monitoring of working and living environments for toxic substances. A ТОХІ+ software complex was used to predict the effects of accidental toxic gas leaks at industrial plants. It was revealed that the most favourable conditions for the distribution of hazardous gases are dark (night) time, increased cloudiness, and low wind speeds. It was proposed to the “Ukrainian atom instruments and systems” company to employ the ТОХІ+ software complex in their Ecological Monitoring System in addition to the sensors by KPI Igor Sikorsky which they already use. The instruments developed (the sensor, micro-generator, and block-module) are intended to be integrated into the National system of environmental monitoring as primary sources of reliable information. Two utility model patents of Ukraine were granted. Two licenses were sold: the patent licence and the know-how licence. Product line depth will provide entirely meeting the demands for such instruments in a wide price range and all possible fields of application.
Key words: environmental safety, monitoring, pollutant emissions, electrodes, sensing elements of sensors, micro-generator cells, block-modules, integrated unit of sensor devices.
