By analyzing the moisture content of the air after drying, we can check whether it meets the requirements of air separation equipment heating and instrument air for moisture content, so as to check the adsorption performance of the absorbents. There are two main measurement methods:
1) weight determination method: Use phosphorus pentoxide to absorb the moisture in the gas to increase the mass. Calculate the moisture content from the weight difference before and after absorption. In specific operation, put the glass wire mixed with phosphorus pentoxide into the drying tube, and cover a layer of glass wire on the tube, then weigh it with an analytical balance.
Connect the wet flow meter to the back of the drying tube, adjust the gas flow to about 60L per hour, and keep ventilating for 100 ~ After 200L, stop ventilation. Weigh the drying tube, and record the volume, temperature and atmospheric pressure of the inlet gas. Then moisture (g/m3) = weight difference before and after ventilation (g') ×1000/[Volume of sampling gas (L) xf] in the formula -- the conversion coefficient when the volume in measurement state is converted into the volume of gas in standard state.
2) dew point determination method. The condensation temperature (dew point) of the water vapor in the gas is related to the content of the water vapor in the gas. Use liquid nitrogen or dry ice to slowly cool the mirror surface of the metal rod. When the gas passes through the mirror surface, the moisture in it will be cooled down and condensation on the mirror surface. Then measure the dew point temperature with thermocouple, then the moisture content in the gas can be calculated.
In the specific operation, first wipe off the mirror dirt with carbon tetrachate, blow off the moisture in the pipeline, and adjust the gas to 100 ~ Enter the dew point meter at a flow rate of 200 ml/min, and then gradually cool the copper mirror. When approaching the dew point, keep the temperature drop speed at 3 ~ 5℃/min. When condensation appears, according to the measured dew point temperature, its water content can be found out according to the table. Or according to the measured dew point temperature, find out the saturated vapor pressure P1 of the water corresponding to this temperature, and then calculate the moisture content Cs (g/m3) in the gas according to the following formula: Cs = P1 (Pa) /101300 (Pa) ×18 (g/mol)/22.4 ×10-3 (m3/mol) ×273 K/293 K =. 0074P1 (g/cm3)
