Modeling of saturated steam selection methods at various medium pressures

Abstract

The article presents the results of modeling methods for selecting saturated steam at different pressures in low, medium, and high-pressure boilers. The aim of the research is to identify the cause of a violation of the representativeness of the sample by modeling the selection of saturated steam by three selection structures at different pressures. The main requirements for sampling devices are considered, including: optimization of the design of the device for sampling saturated steam, observance of isokinetic sampling, and minimization of abrupt changes in pressure and temperature of the sample taken. It is noted that the design of the sampling device should minimize the amount of stagnant zones in the sampling device and promote the maintenance of flow velocity in the sampling device. The importance of maintaining equal flow velocities in the pipeline and the sampling device is shown to be important when sampling saturated steam to avoid two-phase fluid stratification and steam condensation. It is revealed that the prevention of changes in the pressure and temperature of the saturated vapor sample in sampling devices leads to the provision of constant concentrations of impurities in the vapor. The results of simulation of saturated steam flow sampling in a low-pressure boiler using a single-strip sampling device, in a high-pressure boiler using a outlet probe and in a medium-pressure boiler - without a sampling device are presented. The modeling results showed non-compliance with the equality of flow velocities in all three sampling devices at different pressures, and the formation of a film on the surface of all three sampling devices. The need to comply with the main requirements for sampling saturated steam to ensure the representativeness of the sample by maintaining isokinetic flow, minimizing stagnant zones, and avoiding changes in pressure during sampling is confirmed.