Control of oils and greases adsorptive recovery in conditions of non-stationarity

In various fields of production and transport, the demand for oils and greases, which are complex substances harmful to the environment, is constantly growing, and their production requires significant financial costs. An actual task is the creation of control systems for adsorptive purification of used oils and greases, which will be able to meet the requirements of their regeneration quality in conditions of insufficient information provision and non-stationarity of a significant number of characteristics of the technological system. The analysis of properties of raw materials, adsorbent and adsorber from the point of view of the necessary and potentially possible information support was carried out. Three main sources of non-stationarity are singled out: periodic arrival of raw material with new properties; random changes in properties of current raw materials and adsorbent; gradual changes of the working surfaces of the adsorber due to interaction with adsorbent and adsorbate. The first source is recognized as the most significant, therefore, two components are provided for the general control algorithm – control in the modes of variable and stable raw materials (significant and non-significant changes in properties of raw materials, respectively). For each source of non-stationarity, a corresponding adaptation block for pressure and temperature control systems in adsorber with PI-controllers is proposed. The properties of the substances that will be used to correct controllers tasks and their setting parameters have been determined. A system of individual adaptation blocks interaction in both modes of the general control algorithm has been created. For the stable raw materials mode, general view of transfer functions for control channels is given and the adaptive control system structure is proposed with implementation of current identification of the control channel model and calculation of the corresponding PI-controllers setting parameters. The obtained results will allow to reduce duration and amplitudes of quality indicators deviations of regenerated substances from the set values, which will increase control system efficiency as a whole. The proposed methods can be applied to those technologies where there is a problem of stabilizing properties of input material flows, in particular, in technologies using secondary raw materials.