Automation features of thermal processes for heating liquids

Abstract

This article discusses the principles of heat management using the example of a shell-and-tube heat exchanger with a control surface to which a heat transfer fluid and a heating product are supplied. The indicator of the process efficiency is the temperature of the product at the outlet of the heat exchanger, and the control objective is to maintain this temperature at a certain level. Automation of production processes is the main direction in which production is currently moving worldwide. Everything that was previously performed by humans, their functions, not only physical but also intellectual, are gradually being transferred to technology, which performs technological cycles and controls them. Thanks to automation, heat exchange technology has taken a big step forward. High-quality control, ensuring the safety of reactions, speed of processes, and much more are made possible by technical automation tools. Temperature is an indicator of the thermodynamic state of a system and is used as an output coordinate when controlling thermal processes. The dynamic characteristics of objects in temperature control systems depend on the physical and chemical parameters of the process and the design of the device. Therefore, it is impossible to formulate general recommendations for selecting a temperature control system, and each specific process must be analyzed. The general characteristics of temperature control systems include the significant inertia of thermal processes and industrial temperature sensors. The dynamic characteristics of objects in temperature control systems depend on the physical and chemical parameters of the process and the design of the device. Therefore, it is impossible to formulate general recommendations for selecting a temperature control system, and each specific process must be analyzed. The general characteristics of temperature control systems include the significant inertia of thermal processes and industrial temperature sensors.  Thermal processes play a significant role in chemical technology. Chemical reactions of substances, as well as their physical transformations, are usually accompanied by thermal phenomena. Thermal effects often form the basis of technological processes.  Heating is carried out using various heating media (the main ones being steam, hot water, furnace gases and heated air, high-boiling organic liquids), as well as electric current. The choice of heating medium depends primarily on the required heating temperature and the possibility of regulating it. In addition, the heat transfer fluid must ensure a sufficiently high heat exchange intensity at low consumption rates, have low viscosity but high density, heat capacity, and heat of vaporization. It is also desirable that the heat transfer fluid be non-flammable, non-toxic, thermally stable, have no destructive effect on the material of the apparatus, and at the same time be an affordable and inexpensive substance.