Modernization of a Gas-Drying Absorber 1800 mm in Diameter

Abstract

A natural reduction in production pressure during the exploitation of a gas field results in a corresponding change in the operating parameters of all production equipment in the plant used for complex gas preparation (PCGP) and, among other things, the gas-drying absorbers. In maintaining the design output of gas, the actual velocity of the gas flow in the absorber is appreciably increased, and the moisture content of the initial gas also increases. Moreover, the operating velocities of the gas are increased even in the well; this has contributed to flooding, and salt and mechanical-impurity contamination of the raw gas that proceeds into the PCGP in preparing it for transport. In addition, the glycol that circulates continuously within the system of the drying and regeneration plant is contaminated during operation by compressor oil, hydrocarbons, decomposition products, and salts. The increase in contamination of the glycol by salts with decreasing production pressure is also caused by high gas velocities in the well and by the entrainment of salt-containing water by the gas flow with subsequent accumulation of the salts in the glycol [1]. The interplate carry-over of liquid into the mass-exchange section of a plate gas-drying absorber increases with decreasing production pressure due to higher gas velocities in the plate absorber; this diminishes its operating efficiency, and occasionally leads to malfunction of overflow hoppers and the section on the whole. The liquid load on the filtering section of the absorber, which is arranged (along the path of motion of the gas) after the mass-exchange section, increases at the same time. Contamination of the glycol by the indicated impurities results in clogging of the filtering elements, a reduction in thei r effective surface, and an increase in resistance with a simultaneous increase in gas velocity in the subassembly in question. The increase in gas velocity causes the glycol film discharging through the surface of the filtering element to disperse; here, drops of glycol are picked-up by the gas flow with its increased velocity and are carried away with the dried gas. All of the above-enumerated factors involved with the pressure drop lead to a reduction in operating efficiency of the plate absorbers, a decrease in the time to overhaul, and an increase in glycol lost with the dried gas. In recent years, structured packings have come into increasingly widespread use to improve the operating efficien