Showing papers in "Chemical and Petroleum Engineering in 1980"

Calculation of the shock pressure during the filling of a pipeline having local resistance

Abstract: At the present time there are well-developed methods for the calculation of the not fully established motion of a liquid in pipelines completely filled with liquid. Calculation of the hydrodynamic parameters of the not fully established motion of a liquid during the filling of a pipeline is complicated from a mathematical point of view, since in this case it is required to solve equations of motion of a liquid, the boundary condition to which is given at a moving boundary. In [i] a method is proposed for calculating the process of the filling of a pipeline of both constant and variable cross section, under the assumption that the liquid is incompressible. However, in the cases of the greatest practical importance, characterized by considerable fluctuations of the pressure of the liquid, the assumption of its incompressibility leads to significant errors in the calculation [2], It is particularly important to take into account the compressibility of the liquid in calculation of the process of the filling of a pipeline with local resistances, With the approach of the liquid to a local resistance, the hydraulic resistance changes sharply and there arise jumps of the pressure and the velocity. The fluctuations of the pressure and the velocity after filling of a section of the pipeline with a local resistance with a liquid can be calculated using the one-dimensional equations of the not fully established motion of a weakly compressible liquid in a cylindrical pipeline [3]:

Selection of width of a pump impeller at its outlet

Abstract: Selection of width of an impeller a : its ou=let b= is generally made on the basis of practical data. Generalization of experimental results enables to recommend the selection b= as a function of specific speed n e using statistlcai data, However, recon~endation regarding the selection b2 can also be based on analysis of power loss in the pump. It should be noted that ba is related to power loss of two types, viz., hydraulic loss due to transformation of velocity head beyond the impeller into piezometric head in ~he bypass and loss on disk frictionwhich depends on the outer diameter of the impeller.

Surfacing of knives of choppers for polymeric materials

Abstract: Knives of choppers for polymeric materials operate under complex conditions of impact-abrasive wear. To decrease the wear of the knives, their cutting edges are surfaced with IN-1 electrodes [I, 2]. Experience inthe industrial use of such knives has shownthat they are not inferior to knives made of heat-treated steel R6M5. However, because of the low hardness (HRC 50-52) of the surfacing metal, the cutting edges of the knife are dulled, something which leads to a decrease in its durability.