Operating modes of the fuel oil circulation heating system when using water vapor or hot water

Abstract

Circulating heating of fuel oil in railway tanks is carried out, as a rule, with the help of saturated water vapor due to the preparation of a heating stream of fuel oil with a temperature of about 90°C. At the same time, a stream of hot water is also used as a heating coolant. Of interest are the operating characteristics of the fuel oil heater as part of such an installation, depending on the type of heating agent, the temperature of the heated fuel oil, and the steam pressure. The behavior of the existing system of circulating heating of fuel oil of the M100 brand while maintaining the fuel oil flow heater in the form of a shell-and-tube heat exchanger is considered. The basic parameters of the heat exchanger are determined at a saturated water vapor pressure of 1.7 bar, fuel oil temperatures of 40°C at the inlet, 90°C at the outlet. The change of all system parameters while maintaining the initial temperature of fuel oil depending on the amount of its heating is investigated: the heat transfer of fuel oil and steam, their costs, the heat capacity of the heater. The influence of steam pressure on all these parameters has been studied. Changes in the system were determined when water vapor was replaced by a heating water flow with a temperature of 115°C. The calculation method is based on the joint solution of the system of conservation equations, taking into account the criterion equations for the heat transfer of fuel oil in laminar flow and water in turbulent flow, the dependence of the thermophysical properties on the temperature of the flows. The system of equations does not use the approximations used earlier. It is shown that by changing the temperature of the heated fuel oil to 70°C, it is possible to increase the power of the heating oil system to 82% at a steam pressure of 1.7 bar, to 212% when the steam pressure increases to 3 bar, to 21% when replacing steam with hot water with an initial temperature of 115°C, the final temperature of 100°C.