| Summary: | 碩士 === 國立臺北科技大學 === 環境工程與管理研究所 === 97 === From the air quality monitoring data as performed in recent years, it can be seen that the ozone content in northern Taiwan has gradual increase year after year; therefore, the precursor VOCs for the generation of ozone should be improved in faster way so as to reduce the contamination of ozone, and of course, ozone is the current key focus of the air pollution control.
In order to improve air quality effectively, certain petrochemical supplier in the air quality area in northern Taiwan is taken as target for lab simulation of the main equipment and device of the on-site storage tank for the measurement of leak rate of VOCs; meanwhile, one representative pollution source (Ja factories) is selected to perform on-site leak rate measurement of VOCs; the results obtained from both will be compared and verified to each other so as to understand the volatile organic compound leak status in the equipment and device of the process and to prepare related control project; it is hoped that through the implementation of economically inspired system, the petrochemical suppliers can add or improve the efficiency of pollution control equipment so as to achieve the purpose of the reduction of pollution release.
From the research result of this study, it can be seen that, in the mass flow rate test of the flow system of the equipment device (valve) and when seven materials such as: lead-free gasoline, benzene, toluene, xylene, etc., are monitored under different mass flow rate, for the equipment device (ball valve) hour leak rate relation, the results all show that the equipment device leak concentration will rise along with mass flow rate. For seven similar attribute VOCs such as lead-free gasoline, the suggested value of release coefficient of the valve is: under the flow of the material, it is about 7.1×10-4~7.6×10-4(-), and under the non-flow condition of the material, it is 1.8×10-5(1/hr). Meanwhile, the suggested value of release coefficient in the flange is: under the flow of the material, it is about 2.1×10-2(-),and under the non-flow condition of the material, it is 3.0×10-5(1/hr).
If only three factories of ja, Yi and Bin are taken as the main enterprises under control in that city, then the annual leaked VOCs due to two devices of valve and flange reach a maximum of 5.11 tons/year and a minimum of 0.51 tons/year, that is, an annual average of about 2.81 tons. If 4,000 valves and 7,000 flanges are used in the entire city, then the leaked VOCs caused by those two devices reach a maximum of 19.63 tons/year and minimum of 2.15 tons/year, that is, an average of 9.92 tons per year.
It can be seen from this study that the current domestic VOCs control focuses on the checking of pipeline release, hence, many suppliers neglect the leak control because the pipeline concentration can usually meet the regulation; principally speaking, for VOCs material, from the storage in the source, transport to process, to the final release through the pipeline, about 90% is dissipated due to volatility (due to the volatile nature); for other equipment and device (for example, pump, compressor and sampling connector system, etc.), since there is still no localized release coefficient and there is no complete VOCs release database for the device due to leak in the city and county organizations, hence , there is a leak of perfect VOCs control work (including release list, reasonability of the air pollution charge, and the reduction and control on O3); therefore, fore perfect VOCs control to be achieved, it is suggested that the local government should reinforce and implement the control and audit of the leak of the pipeline fittings.
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