Upgrading dust traps for compressor stations on major pipelines as an alternative to new plant

Abstract

UDC 621.928.9 Efficient and reliable treatment of the pumped gas in dust traps is essential to the reliable operation of gas pumps at compressor stations on major pipelines, which includes reducing the energy consumption in transporting natural gas. This is possible only if the equipment meets the latest specifications. Many of the dust traps currently operated (in particular at the Severgazprom compressor station) are oil traps made in the 1960s and 1970s, whose design life has come to an end. Expert diagnosis has indicated that in the main the engineering state of this plant is satisfactory, and it is possible to continue to operate it with the working parameters for a fairly long time. However, that company has collaborated with the Central Petroleum Design Company to establish that the states of the inner components and the working conditions of them are such that the efficiency is very low (20--30%), as there is a lack of oil economizing equipment, a lack of recycling plant, and so on. These two companies have therefore drawn up engineering specifications for upgrading the plant under the conditions of existing pumping stations or at engineering factories. A comprehensive economic study has shown that the second possibility is promising and has the tollowing advantages: - fuller and better expert diagnosis, together with the scope for eliminating defects under factory conditions, which means that the working life can be extended (by up to 10 years); - it is possible to install additional pipes for draining purposes and for lacking monitoring instruments; and - the minimum volume of work is required at the pumping station. The maker selected was the production association Sevmash (Severodvinsk), which has a license from the Russian Federation State Mining and Engineering Inspectorate for reconstructing (upgrading) and preparing vessels working under pressure, together with permission from the northern area of that body for performing operations in upgrading dust traps. The Central Petroleum Design Company drafted a project for upgrading an oil and dust trap, which was agreed with the Severgazprom Company and Sevmash. Operation Sequence. A preliminary diagnosis was performed at the point of use; any dust trap suitable for upgrading was removed and sent to the factory, where a complete check was performed on the state of the vessel, and any defects were eliminated. The dust trap was then upgraded: the upper end was cut off, and all the internal components were cut off and removed; a previously manufactured cyclone group was installed, additional tubes were welded in, and the upper end was welded on. The apparatus was given a complete heat treatment and all necessary checks on the welded joints; hydraulic tests with the trial pressure provided the final diagnosis of the body by means of acoustic emission and potentiometric methods. Then the trap was transported to the pumping station, The upgraded trap operates as follows: the gas passes through the inlet pipe and is distributed between the four cyclones. Centrifugal forces transfer impurities in the gas to the walls of the cyclone, and the gravitational tbrce causes them to move downwards and collect at the bottom, where they are periodically removed through the drainage pipe. The treated gas passes through the upper part of the equipment to the gas outlet.