Requirements of heat transfer oil systems for expansion tubes

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The expansion tube is the main channel that connects the heat transfer oil system to the overhead tank. Given the specific characteristics of the heat transfer oil system, strict requirements are also imposed on the expansion tube: 1. As the temperature rises in the system, the volume of the heat transfer oil increases; the excess volume flows into the overhead tank through the expansion tube, thereby reducing the operating pressure of the system. 2. During the heating and operation of the heat transfer oil system, the water and low-boiling substances present in the heat transfer oil vaporize, generating a large amount of gas that increases the pressure in the system. The vaporized gas is released from the expansion tube into the overhead tank and then discharged. 3. During operation, the removal of water and low-boiling substances from the heat transfer oil leads to a lack of oil in the system, causing the oil to coking and disrupting the normal operation of the system. Therefore, the heat transfer oil in the high-level tank is replenished into the system through expansion tubes to ensure the proper operation of the heat transfer oil system. 4. When the heat transfer oil system is in operation and a power outage or an emergency shutdown occurs, the flow of heat transfer oil within the system comes to a stop. The heat transfer oil in the furnace tubes continues to heat up due to the residual heat from the oil furnace, which accelerates the overheating, cracking, and aging of the heat transfer oil. Therefore, to prevent the heat transfer oil from aging, the cold oil in the high-level tank is replaced by the hot oil in the expansion tube replacement system, and the hot oil in the system is slowly transferred into the low-level storage tank. In summary, it is required that the expansion tube remain unobstructed and that pipeline resistance be reduced. The expansion tube should be as steep as possible, with no horizontal or bell-shaped sections. If a turn is required, the angle should be at least 120 degrees; valves are generally not recommended to be installed to prevent accidental operation.