Analysis of the effectiveness of operation of the technological equipment of installations for the preparation and processing of natural gas

Abstract

The increasingly stringent demands on the quality of the products of gas-processing plants and reduction of the discharge of deleterious wastes into the environment make it absolutely necessary to improve the technology of gas processing and enhance the effectiveness of the technological equipment. The task of good preparation of natural gas, of stratal water, and of gas condensate in particularly topical at the Astrakhan Gas Processing Plant (AGPP) because the gas supplied to it has a very complex composition, is aggressive and ecologically dangerous. The technical and economic indices of the technological installations including the costs of repairs were therefore analyzed. The results of the analysis were the basis for working out suggestions for the reconstruction of these installations.Installation U171 for the Separation of Stratal Gas. The installation U171 is intended for the separation and scrubbing of gas supplied to the plant from the wells. Each of the four separation lines ensures gas-liquid separation of the untreated gas and compensation of fluctuations of the flow rate caused by pulsating plugs of gas condensate. The installation contains buffer and separation tanks and other equipment. After separation in the buffer tank the gas and liquid (condensate, stratal water) are throttled from 7 to 6.2 MPa and are delivered to the separation tank which acts as three-phase separator operating on the gravitational principle. Practice during the entire period of operation of the plant showed that the installation did not attain the planned regime. Deviations of the productivity from the specified one have a considerable effect on the hydrodynamic flow regime of the biphase mixture in the gas-condensate pipes. Thus the project envisages the speeds of the biphase mixture in the gas-condensate pipes corresponding to the speed of the stream in annularly disperse regime. But when the speed of the stream drops below the minimal level, the regime changes to plug flow which complicates the process of separation. Constant fluctuations of the flow rate bring about failure of the level and flow-rate regulators.Gas after separation contains a large amount of undesirable admixtures which greatly impair the indices of operation of the subsequent equipment, viz., the installations ensuring desulfurization of the gas U172. Condensate often gets into the aqueous phase and passes along the entire technological chain, and water gets into the condensate. Investigations showed that the separation of emulsions can be improved solely by improving the design of separating devices or by adding a demulsifier to the mixture. The costs of repair work on the installation U171 increase practically every year (by a factor of 2.1 in 1991, by a factor of 4.8 in 1995) because of the frequent clogging of filters and failure of control instruments and of the stop and control fittings.Installation U165 for Filtering Water and Incineration of Industrial Wastes. The installation U165 ensures degassing of water upon pressure decrease, filtering o...