In order to design a gas purifier to meet the required 1 ppm to 10 ppb hydrocarbon reduction challenge while accepting a 1 SLM flowrate for one year, it was necessary to perform experiments on a laboratory-scale, observe the characteristic system adsorption, and then attempt scale-up based upon these results.Accordingly, a test manifold was developed, as displayed in Figure 1, to facilitate research with the 35K test purifier provided by Aeronex.
Figure 1: Test manifold for laboratory-scale experimentation.
This system arrangement offers flexibility in the performance of a variety of different experiments.First, the merging of the ultra-high purity air and 1 ppm butane in air lines and the purifier bypass makes it possible to ratio these two gases for calibration purposes.Secondly, during generation of a 35K purifier breakthrough curve, the 1 ppm butane in air may be passed through the purifier continuously at a rate of 1 SLM for analysis with the gas chromatograph.
Prior to insertion into the test manifold, the ZSM-5 loaded purifier must be activated in order to remove water vapor and other contaminants adsorbed by the zeolite during exposure to the atmosphere.Accordingly, an activation system was developed in which the adsorbent bed is heated and purged with a hot, inert purge gas.The purge gas itself is cleaned of hydrocarbon contaminants by passing it through a large shop purifier.This set-up is displayed in Figure 2, below.
Figure 2: Experimental set-up for activation/regneration of ZSM-5.
conditions for activation are still in the development stages, but typically
helium is flowed through the system at a rate of 1 to 1.5 SLM and a pressure
of 7 psig, while the oven temperature is set at 250°C.At
a minimum, the activation process must be allowed to proceed for 48 hours.