METHOD OF AUTOMATIC CONTROL OF MOISTURE FREEZING-OUT PROCESS IN TWO-STAGE FREEZING-OUT PLANT

摘要

FIELD: automation of technological processes; automation of freezing-out of liquid products; chemical, microbiological, food-processing industries and plants of agricultural complexes.;SUBSTANCE: proposed method includes change of temperature and flow rate of cooling agent in crystallizers of proposed plant, as well as time of presence of product in crystallizers, flow rate of cooling water, power of adjustable drives of refrigerating machine compressors and drives of crystallizer drums by acting on rotational speed of drum and flow rate of cooling agent, cooling water, starting product and water obtained thawing frozen ice; starting product is preliminarily fed for cooling in recuperative heat exchanger washed with fresh water formed at thawing ice and then to heat exchanger washed with concentrated product; then, flow rate and content of dry products are measured at inlet of first crystallizer, present flow rate and content of dry agents in concentrated product at outlet of each crystallizer, time of presence of product in each crystallizer; these date are used for correcting the evaporating temperature of cooling agent in inner cavity of crystallizer drum and rotational speed through change of power of adjustable drives of compressors and drives of crystallizer drums depending on electric conductivity of ice, as well as though change of flow rate of water fed to additional condenser; amount of this water depends on present magnitudes of temperature and flow rate of fresh water at outlet of melting pots and on measured content of dry agents in starting product and time of presence in freezing-out plant and amount of frozen-out layer of ice for setting the required rotational speed of crystallizer drums; preliminary cooling of starting product is effected due to recuperation of heat of fresh water obtained after thawing of ice and due to recuperation of heat of concentrated product; frozen-out ice is thawed by heat of cooling agent delivered by refrigerating machine compressor at simultaneous cooling and condensation of cooling agent in thawing zone; evaporating temperature of cooling agent is reduced in inner cavity of crystallizer drums at deflection of content of dry agents in concentrated product at crystallizer outlet from preset magnitude towards increase and increased when content of dry agents in concentrated product is decreased.;EFFECT: enhanced accuracy and reliability of control; intensification of process; improved quality of finished product.;4 cl, 1 dwg