Questions regarding the volume of expansion tanks and oil storage tanks in organic heat carrier boilers? ? ?

The volume of the oil storage tank shall be no less than 1.2 times the total amount of organic heat carrier in the organic heat carrier furnace. Does the total amount of organic heat carrier include the volume of the entire pipeline?

The total amount of organic heat carriers includes the capacity within the pipelines. In other words, if you drain the entire hot oil system into the oil storage tank, there should still be at least 0.2 times that amount as a safety reserve. An oil storage tank is also known as a drain tank or a discharge tank.

Should the volume of the oil storage tank include the volume of the pipelines as well? And how is the volume of the expansion tank determined?

When calculating the volume of expansion in the expansion tank, is a temperature difference of 300° used?

The design and use of the expansion tank are very important factors for the successful operation of the entire system; it allows for storing the total amount of heat transfer oil that expands when heated from room temperature to the operating temperature. The main functions of the expansion tank are to store the amount of expansion that occurs in the heat transfer oil due to heating; to release gases from the system during the heating process when the heater is started; to replenish the heat transfer oil throughout the system; and, in the event of a sudden power outage, to use the cold medium in the tank to replace the hot medium inside the heater. Therefore, the proper design of the expansion tank is crucial for the lifespan of the heat transfer oil as well as for the other components in the heat transfer oil system. The following aspects should be given special attention during design: Pressure: The expansion tank can be either open or closed; a horizontal, closed container is recommended. Its gas space should be filled with nitrogen to prevent air from entering, thereby avoiding the oxidation and decomposition of the heat transfer oil and reducing its evaporation. Pressure in the expansion tank is maintained through staged control using nitrogen inlet pipelines and exhaust gas discharge pipelines. In addition, a vent pipe also needs to be installed. Volume: The expansion tank can store the total amount of heat transfer oil that expands when heated from room temperature to the operating temperature. Therefore, its volume should be at least 1.3 times the increased volume of the total oil amount in the entire system due to thermal expansion. Therefore, it is first necessary to determine the volume expansion amount V0 of the heat transfer oil (unit: m3). Generally, when the temperature of the heat transfer oil increases by 100 °C, its volume expands by approximately 10%; thus, V0 = (T2 – T1) / 100 × 10% × V1. Here, T1 is the temperature of the heat transfer oil before heating, in °C; T2 is the temperature of the heat transfer oil after heating, in °C; and V1 is the total volume of the heating system at the lowest level of the expansion tank, in m3. Once this value is known, the effective volume V2 of the heat transfer oil can be calculated (unit: m3). V2 = 1.3×V0. Finally, to calculate the volume V of the expansion tank, using a safety factor of 1.1 and a filling coefficient of 70%, the estimated volume of the expansion tank is V = 1.1×V2 / 0.7. Location: The temperature inside the heat transfer oil expansion tank is high; it is a device subject to thermal displacement. Therefore, in its design, one of its foundations should be a fixed end, while the other should be a sliding end. The installation height of the expansion tank should be higher than that of all equipment; consideration must also be given to the pump’s net positive suction head and the saturated vapor pressure of the heat transfer oil. The installation location of the expansion tank must not be directly above the heater; it should be at least 1.5 meters away from the heater. It not only prevents fires caused by the overflow of heat transfer oil, but also reduces the degree of heating of the heat transfer oil. The distance between the expansion tank and the oil-gas separator should also be at least 1 m, to prevent the heat from the heating system from affecting the expansion tank. Temperature: Heat transfer oil can undergo oxidation at high temperatures; oxidation is not significant below 100 ℃. However, when the temperature of the heat transfer oil exceeds 100 ℃, the oxidation rate increases. Therefore, the temperature in the expansion tank must not exceed 70 ℃ to prevent oxidation of the heat transfer oil, and as a result, the expansion tank does not require insulation. Instrumentation: Pressure gauges, thermometers, and level gauges should be installed in the expansion tank. The level gauge must have a low-level alarm function or a low-level switch installed, in order to prevent gas from entering the heat transfer oil system. The expansion tank maintains a high liquid level under normal operating conditions; this ensures that there is sufficient heat transfer oil available when it is necessary to replace the oil, thereby preventing the heat transfer oil inside the heater from overheating. The content is for reference only. If you are a designer, it is recommended that you look for the standard files and manuals you use. There can be some differences among different manufacturers in various regions. :)

This post was last edited by a decade beyond on 2016-12-3 at 21:29. The oil storage tank should be able to hold all of the heat transfer oil during maintenance of the circulation system. The following aspects should be taken into account in the design of such a tank: Pressure: The expansion tank can be of either open or closed type; it is recommended to use a horizontal, closed container, with its gas space filled with nitrogen in order to prevent contact between the heat transfer oil and air. Staged control using nitrogen inlet pipelines and exhaust emission pipelines is employed to maintain the pressure in the expansion tank, and a vent pipe must also be installed. Volume: The volume of the oil storage tank should be no less than 1.2 times the total volume of the heat transfer oil. The total volume of the heat transfer oil is equal to the sum of the volume of all the heat transfer oil pipelines and the volume of the expansion tank. With an installation factor of 80%, the volume of the oil storage tank can be estimated as: V = 1.2 × V0 / 0.8. Where: V –– the volume of the oil storage tank, in m3; V0 –– the total volume of heat transfer oil in the entire system, in m3. Installation location: The oil storage tank needs to be placed at the lowest point of the heating system so that it can hold the heat transfer oil used in that system during maintenance work. Temperature: The temperature of the heat transfer oil in the expansion tank must not exceed 70 °C to prevent high-temperature oxidation of the heat transfer oil. However, the operating temperature during maintenance should be higher than the temperature after the heat transfer oil is heated. Instrumentation: The expansion tank should be equipped with a pressure gauge, a thermometer, and a level gauge. The oil storage tank should be at a low liquid level during normal operation, ready to receive the heat transfer oil that flows in at any time. Since both the expansion tank and the oil storage tank are closed containers, when overpressure occurs in the entire heat transfer oil system, the safety valve installed on top of the oil storage tank can release pressure to protect the system; the heat transfer oil discharged through this safety valve is sent to the exhaust gas release system. :)