Contactor pressures have little effect on the glycol absorption process as long as the pressures remain below 3,000 psig. At a constant temperature the water content of the inlet gas decreases with increasing pressure, thus less water must be removed if the gas is dehydrated at a higher pressure. In addition, a smaller contactor can be used at high pressure as the actual velocity of the gas is lower, which decreases the required diameter of the contactor.
At lower pressure less wall thickness is required to contain the pressure in a given diameter contactor, therefore, an economic trade-off exists between operating presssure and contactor cost. Typically, dehydration pressures of 500 to 1,200 psi are most economical.
