Lutz Friedel

Two phase pressure drop in a rupture disc/safety valve unit

Abstract For straightforward engineering design purposes, the pressure drop of a rupture disc/safety valve unit is related by means of experimentally determined relative discharge reduction coefficients to the flow resistance of the safety valve in the unit. In the case of single phase flow the pressure drop can be calculated on the basis of the liquid or gas/vapour flow discharge coefficients available from the respective suppliers catalogues. For two phase flow conditions reference must be made to the fitting correlations of S.D. Morris or H.C. Simpson et al. , which are presently the most accurate methods available.

Effect of Pressure Waves in the Feed Lines upon the Performance of Full Lift Safety Valves

During full lift safety valve venting of pressure loaded equipment, undesirable instabilities in the valve disc movement, so-called fluttering or chattering, may occur due to temporary force imbalance on the valve disc. These results among other things from the interactions between the flow through the valve and flow in the valve inlet line after activation of the device are presented.

Predictive Accuracy of Design Methods for the Relief Cross‐Sections on Chemical Reactors in the Case of Two‐Phase Flow Discharge

The most common methods for calculating the minimum relief cross-section are discussed. Furthermore, the predictive accuracy of these methods will be assessed. For this, either the (formal) reaction kinetics or the characteristic reaction state at prescribed pressures during relief must be available.

Berechnung der maximal möglichen Überhitzung siedender Fluide am Beispiel der Leckströmung

Cf Article en Anglais dans Chemical & Engineering Technology, 1998, Vol 21, No 3, pp. 267-272

Recalculation of the pressure behaviour in the reactor and in the catchtank during emergency depressurization

Abstract To assess the predictive accuracy of the (extended) SAFIRE computer programwiith respect to the thermodynamic and fluid-dynamic processes during depressurization, the results from experiments with the chemically non-reacting medium R114 have been recalculated. The curves for the pressure and the other transient thermohydraulic parameters, such as mass flow quality in the vent line and mass discharge per time unit, are described with satisfactory accuracy. To check the complete computer program including the reaction-kinetic part, the pressure curves in the reactor and in the catchtank connected via the vent line during relief of a methanol/acetic anhydride esterification runaway were recalculated. In this case, the measured and calculated transient pressures in the reactor and in the catchtank are similar.