EPA-099-1602-02-02

099

1,450 千元

2010/01/01

2010/12/31

陳志傑

環檢所

程惠生

國立台灣大學

大氣空氣

煙道採樣、微粒、檢測比測

stack sampling, particulate, proficiency testing

鄭福田、林文印、黃景祥、黃榮芳、黃盛修

林暐舜

02-33668086#

d96841002@ntu.edu.tw

環保單位為加強固定污染源之稽查管制以及落實固定污染源設置變更操作許可制度，對於固定污染源之排放檢測一直是環保行政單位積極稽查與管制的目標。目前環境檢測機構在取得執業資格的審核程序上，因污染物之多樣性與不確定性使得其標準樣品在取得或製造上有困難，並無所謂的一級標準樣本，所以無法進行客觀和量化的評鑑，而僅就採樣人員的動作與操作程序的熟練度進行評比，無法得知整個採樣量測過程的品質，對於其精確度與準確度一直缺乏有效的稽核，且在現場採樣時亦必需考慮固定污染源的位置、採樣口高度、採樣平台及空間的限制、同軸等速採樣等規定，導致採樣的難度增加，使得檢測結果品質受到質疑。 因此，於1997年環保署環境檢驗所委託台灣大學職業醫學與工業衛生研究所與環境工程研究所建置一粒狀物排放管道模擬系統。粒狀物排放管道模擬系統為一內徑 60 cm，高14 m 之垂直管道，共設有四層採樣平台，在模擬系統底部地面設置有前過濾裝置、風扇(可控制範圍為0~14m/s)及其16 hp驅動馬達與空氣加熱器(總功率750 KW)；第一層設置有系統操作控制單元與混合氣體樣本鋼瓶，並且也做為粒狀物樣本及水氣注入處；在第二層則設置有空氣壓縮機、乾燥機以及壓縮空氣儲存槽等設備；第三層為採樣的測定點，其與第一層的粒狀物樣本注入口的距離約為9倍的管道直徑，使管道內氣流符合理論上的層流狀態；第四層為末端過濾設備避免排出的粒狀污染物造成環境污染。前述各層距離地面的高度分別為278、543、808以及1,073 cm，同時在每層採樣平台上各有兩個內徑10公分相互垂直的採樣測定孔。 經過歷年來利用粒狀物排放管道模擬系統對於執行檢測作業的環境檢測機構之能力進行驗證，結果顯示其執行能力皆有顯著的提升，在管道內風速量測方面，誤差值由24.5%進步至8.5%；管道內質量濃度量測方面，誤差值由22.2%進步至13.4%。藉由每年對環境檢測機構之能力的驗證，已達到以積極的方式督促其檢測能力的提升與協助改善缺失的目的。

煙道採樣、微粒、檢測比測

EPA-99-1602-02-02.zip

3MB

2011/2/1 上午 12:00:00

Determination of particulate matter emissions from stationary sources is the most complicate and challenging task among all environmental sampling and analytical procedures. It is speculated that the dust concentration measurement is affected by the interactions among exhaust velocity, temperature, humidity, aerosol concentration, aerosol size distribution, type of sampling equipment and level of experience of the sampling team. this program can be used to identify the factor(s) contributing to the variability of measurements. The primary goal is to enhance the proficiency of stack particulate measurement. The backbone of the proficiency testing system was built in 1997. A humidity generation system and a heater were added in the following years. This system simulating a stack is composed of an inlet filtration unit, a 15-Hp blower, a 13.4 m height, 60 cm diameter stainless steel duct, and an outlet filtration unit, as shown in Figure 1. The blower is capable of propelling the face velocity up to 15 m/sec. A Palas Powder Disperser is used to generate aerosol particles. A heater of 750 kW with a PID feedback system is used to control the temperature of the exhaust gas. A 120 kW steam generator is used to change the humidity of the exhaust gas, i.e., water content ranging from 2 % to 10 %. The major operation parameters include dust feeding rate, temperature, relative humidity, and fan rotation speed. Duct velocity ranging from 4 to 11 m/secand PM concentration ranging from 72 to 481 mg/m3 are randomly set for stack sampling team taking the test. In addition to velocity and aerosol concentration, blind gas samples of different combination of CO2, CO, O2 were also prepared for the sampling team to perform Orsat analysis. Statistical analysis is carried out each year after the completion of the proficiency testing program. After 10 years of operation, the proficiency testing program has been proven to be effective providing a quantitative way to grade the performance of the sampling teams. The measurement errors on duct velocity has been decreasing from 24.5% down to 8.5% since the launch of this program. The errors committed by the stack sampling teams on PM measurements are also decreasing, from 22.2 % down to 13.4 %, a bit higher than that of velocity measurement because of the error propagation. The more rigorous requirements by EPA authority are expected to drive the participants of stack sampling to concentrate more on all fundamentals, and further reduce the measurement errors in the future.

stack sampling, particulate, proficiency testing