A new dust trap for cleaning gas at major pipeline compressor stations

Abstract

When natural gases are transported, there are usually accompanying mechanical impurities (liquid, sand, and corrosion and erosion products), which affect the reliability of the gas pumping plant (GPP), compressor stations (CS), major pipelines (MP), and users' equipment.To reduce the adverse effects of those components on the working lives of compressors employing centrifugal pumps, one employs single-stage or two-stage gas purifiers. A single-stage unit usually employs a dust trap (DT) designed by the Central Petroleum Design Company and equipped with cyclones 600 mm in diameter designed by the Gas Industry Research Institute.Such plant provides a comparatively high degree of removal for mechanical impurities (100% for ones of 40-50 ~m size), but it is of poor performance in removing liquid, and it also has elevated hydraulic resistance, which increases the energy consumption. Better gas treatment is provided by two-stage cleaning, with a separating filter located after the DT, which improves the performance but at the same time raises the resistance and increases the energy consumption.The DT characteristics may be improved, including the efficiency and resistance from research conducted by the Central Petroleum Design Company (TsKBN) involving the creation of a new DT ahead of the pumps that provides improved performance in treating the gas to remove solid impurities (down to a level of 5 mg/m 3) and also of improved performance in removing liquid (down to 15 mg/m3), with reduced resistance (by 30-35%), and containing less metal (by 10-15%).The research involved developing a new working element and performing comparative tests on various designs for trapping impurities.The basic design parameters of these elements are shown in Figs. 1 and 2 and in Table 1. A distinctive feature of the new element is that it provides two-stage removal of liquid and mechanical impurities and is equipped with a channel for recirculating the gas that provides improved efficiency and throughput [1, 2].The components were tested on TsKBN atmospheric and pilot-plant testers employing conditions as close as possible to those of actual operations as regards speed and initial contents of liquid and mechanical impurities, which involved the addition to the gas flow of dust, water, oil, and a two-phase dust plus oil mixture.Results. The lowest resistance coefficients occurred in the Russian components from TsKBN and VNIIGAZ and from the foreign firms of Paladon and Klanki. The effects of the medium (water and dust) on the resistance were slight throughout the speed range. Increasing the diameter or length in a given model raised the resistance by up to 21%. The material from which the component was made had only a slight effect on the resistance (reduction by up to 3% for corrosion-resistant steels by comparison with carbon ones).It was found that the TsKBN and Paladon components removed over 99% of the water; the performance in removing dust increased with the speed and attained 98% in the speed range used for the TsKBN component, or 94%...