Analytical Assessment of Valve Throughput Coefficient

Abstract

The current level of industry development for the gas and oil production of equipment requires the development of engineering methods for calculating the hydraulic characteristics of manufactured products. Due to the complexity of the designs of distribution and control units for oil and gas transportation networks, the hydraulic characteristics of their control components increasingly affect the performance of regulation. In the construction of distribution and control units, pipeline fittings are used, in particular, wedge gate valves and shut-off valves. One of the main hydraulic characteristics of these products is the throughput, which is assessed by the throughput coefficient. Therefore, now the design engineer needs simple and accurate methods to determine the theoretical value of the throughput coefficient at the design stages of the product. The throughput is related to the hydraulic resistance of the passage part of the pipeline fittings, because it affects the level of pressure reduction when fluid moves from the inlet to the outlet of the product. There are methods for determining local hydraulic resistance caused by a change in the geometry of the passageway, based on the Weisbach formula and empirically determined local resistance coefficients. Engineering methods are proposed for determining the throughput coefficient of two types of pipeline fittings - a wedge valve and a shut-off valve. The methods are based on a well-established approach, expressed in the use of the connection of the throughput with a set of local hydraulic resistances that arise in the path of the working medium. The methods use information about the values of local hydraulic resistance values obtained empirically with the possibility of their approximation to obtain intermediate values of these indicators. The geometric features of the passage channels of the products under consideration are taken into account. They are compared with the existing nomenclature of information about the values of the coefficients of local hydraulic resistance. The proposed methods make it possible to reduce the time for carrying out calculations with obtaining a result whose accuracy is sufficient for use in engineering calculations. Expressions are obtained that allow determining the values of the throughput coefficient of the wedge gate valve and the shut-off valve, taking into account the geometric features and the relative position of the flow sections of pipeline valves, as well as the physical properties of the working medium.