1. Table 1 shows the saturated moisture content of compressed air. From the table, it can be seen that under a certain pressure, for every 10℃ increase in inlet air temperature, the saturated moisture content doubles, which means that the load of the adsorption agent in the dryer doubles.

Table 1  g/kg

3. The increase in the exhaust temperature of the compressor leads to a proportional increase in the content of oil vapor, and any filter is powerless against the oil vapor. When the exhaust temperature exceeds 60℃, if the content of oil vapor is calculated at 10mg/m³, the cumulative amount of trace oil in the 20m³ compressor over one year is:

10mg × 20m³/min × 60min × 24h × 300d × 10⁻⁶ = 86.4kg/year

So much lubricating oil enters the dryer, which will clog the pores of the adsorbent and cause "oil poisoning", losing its adsorption capacity. Therefore, when the intake temperature exceeds 60℃, the lifespan of the adsorbent is only guaranteed for one year.

4. Table 2 shows the test data of intake temperature and exhaust gas dew point. From Table 2, it can be concluded that, under the condition that other parameters remain unchanged, for every 5℃ increase in the inlet temperature, the atmospheric dew point of the exhaust gas will increase by about 10℃.

From the above analysis, it can be seen that the factor causing the deterioration of the gas quality of the outlet gas from the adsorption dryer due to the increase in intake air temperature is comprehensive. The increase in intake air temperature leads to an increase in saturated moisture content, which increases the load on the adsorbent. The increase in temperature significantly reduces the adsorption performance of the adsorbent, accelerates the "oil poisoning" of the adsorbent, and further deteriorates the performance of the adsorbent. The combined effect of these factors directly affects the increase in the dew point of the outlet gas, resulting in a deterioration of the quality.

The ISO7183 "Specification and Test for Compressed Air Dryers" stipulates that in the working conditions, the specification for the intake air temperature of the dryer is 38℃. If the temperature exceeds this value, special design is required, such as increasing the volume of the adsorption tank, replacing with high-performance adsorbents, increasing the regeneration gas volume, and shortening the working cycle, all of which will increase the cost and energy consumption. Therefore, reducing the intake air temperature is the most economical, safe, and reasonable measure.

Xi'an United Ultrafiltration Purification Equipment Co., Ltd. Technology Department

January 13th, 1998