The purposes of this project are to evaluate and establish a stack sampling and analysis method for high solubility and strong polarity chemicals such as acrylamide, caprolactam, dimethyl sulfoxide and dimethyl formamide (ACDD). The stack sampling and analysis method includes isokinetic sampling, sample collection, preservation and instrumental analysis. Through five different stack sampling programs at various factories, the stack sampling and analysis method was tested and verified its effectiveness and the quality control/quality assurance protocol. Technical transfer meetings were also held twice to encompass the thorough goal of this project.
Because of the high solubility and strong polarity of ACDD, most factories applied scrubbers to clean up their exhaust gas, then emit through stacks. Upon stack sampling, not only particulate (mostly water droplets) phase but also gaseous phase should be thoroughly collected. Therefore, isokinetic sampling requirement is essential for ACDD in both particulate and gaseous phases. However, the physical characteristics of emission stacks after scrubbers are not suitable with upper stream 8D/ down stream 2D (D is the stack diameter) requirement for isokinetic sampling.
According to laboratory and real stack sampling tests, about 20-30% of ACDD remaining in the sampling tube suggested isokinetic sampling is required to minimize the inertial loss of large particles in the flue gas stream. Ethanol in two sequential impingers is used to absorb ACDD during sampling. The sampling flowrate of 10 lpm was recommended as the upper limit to avoid possible breakthrough, which is defined as 5% of the second impinge to the first one.
Gas Chromatography equipped with flame ionization detector (GC/FID) is used to analyze ACDD in this project. The chromatograph column is DB-624 with 60m, 0.25 mm I.d. and 1.4 um film thickness. With split ratio of 3:1 and carried gas linear velocity of 35 cm/sec, ACDD are well separated and quantified. The method detection limits of ACDD varied from 0.32 -0.88 ppm. Stored under refrigeration, ACDD can be preserved to seven days without significant deterioration.