Process for time-dependent control of a metering unit for fluid components and apparatus for carrying out the process

摘要

The invention relates to a process for time-dependent control of a discontinuous (batch-operating) metering unit for fluid components in which, optionally, an adjustable or non-adjustable metering valve is connected by means of a metering line to a metering pump. By means of a measuring device of a capillary viscometer type, when the metering unit is operated, the volumetric flow rate of the fluid is measured intermittently from the pump data and the pressure difference between the outlet of the metering pump and the final section of a dimensionally stable section of the metering line having a constant diameter and connected to the outlet of the metering pump. Taking into account the geometric dimensions of the dimensionally stable section of the metering line, the pressure difference between inlet and outlet of the dimensionally stable section of the metering line, the elastic portions of the pump and of the system and the volumetric flow rate transported, rheological characteristic data are determined. These characteristic data are compared with stored theoretical curves for shear strain and theoretical curves of the first normal stress differential N1 and theoretical flow curves of fluids corresponding to the fluid transported. If the actual values deviate from the theoretical values, the open throughflow cross-section of the metering valve and/or the volumetric flow rate is adjusted until the measured actual values of shear rate, shear stress and shear viscosity agree with the theoretical values.