Heating furnace tube
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Can anyone explain why the inlet diameter of the atmospheric pressure furnace is DN200 while the outlet diameter ranges from 150 to 250?
Based on my speculation, the inlet pipe of the atmospheric pressure furnace is DN200, while the furnace tubes are DN150. The reduction in diameter is intended to increase the linear velocity of the medium inside the furnace tubes, thereby reducing the risk of coking. The expansion of the diameter at the outlet to DN250 is due to the large amount of material that vaporizes inside the furnace tubes, resulting in a decrease in density and an increase in volume.
Because when the crude base oil is heated in a atmospheric pressure furnace, a large amount of light components undergo phase changes due to the heat, causing their volume to increase; in order to prevent excessive flow rates in the outlet pipeline from leading to erosion and leaks, the diameter of the outlet pipeline was enlarged； The reduction in diameter at the inlet is mainly intended to increase the flow rate of the medium, thereby preventing thermal pyrolysis due to low flow rates, which could lead to coking inside the furnace tubes and cause accidents.
Increase the flow rate inside the furnace tubes to reduce the likelihood of coking. The outlet diameter is increased to accommodate the increased volume of the fluid; think of the expansion of the return pipe for circulating water to understand this.
Since when the base oil enters the atmospheric-pressure furnace for heating, a large amount of light components undergo phase changes due to the heat, resulting in an increase in their volume, it is necessary to expand the diameter of the outlet pipeline in order to prevent excessive flow rates from causing erosion and leaks in the pipeline. The reduction in the diameter of the inlet pipeline is intended to increase the flow rate of the medium, thereby preventing thermal cracking and coking that can occur when the flow rate is too low.