MATHEMATICAL MODEL OF THE HEATER WITH INTERMEDIATE HEAT
Keywords:непрямий підігрів, кібернетична модель, теплопередача, енергетичний баланс, система управління.
Track heaters are one of the technological equipment’s elements of oil and gas condensate deposits during the transportation of oil, oil products and natural gas. It was found that it is advisable to use line heaters with an intermediate heat carrier (water), which is heated during combustion associated (commercial) gas and transfers heat to the process flow through the heat exchange surface for soft heating of viscous oils and oil products to avoid hydrate formation during throttling of natural gas, with the aim of further transportation through pipelines to the place of collection, processing and consumption. A significant part of scientific publications relates to improving the efficiency of such devices with the use of various technological innovations for heat recovery from flue gases, as well as the use of high-quality control systems. On the basis of the analysis of the heater as an object of automation, the main input, disturbing factors and output parameters of control and regulation were established, and the information structure of the heater as a cybernetic system was developed. Based on the equations of the material and heat balance of the apparatus, the mathematical model of the dynamics of the process of heating technological streams has been developed, which includes the differential equations of the heat balance of the product heat exchanger, intermediate heat carrier, flue gases in the gas duct formed during gas combustion. The system of equations is supplemented by equations of heat transfer through two heat exchange surfaces from water to the target product and from flue gases to an intermediate heat carrier. The linearization of the nonlinear components of the developed model in the vicinity of the operating point is carried out. Based on the obtained mathematical description of the heater, a block diagram of the model was synthesized, which shows the relationship of input parameters, control action and output variables in deviations from the base point of the operating mode.
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