Temperature drop of benzene during transportation
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Dear colleagues: We have an insulated pipeline that is approximately 8,000 meters long, with a diameter of DN50. The fluid flowing through it is benzene, at a flow rate of around 3 tons per hour. The insulation consists of rock wool with a thickness of 50 mm. To ensure that the outlet temperature remains above 15°C, what should be the minimum inlet temperature? The ambient temperature is -20°C. How should it be calculated? Is there any software that can simulate this operating condition? Thank you
Multiple calculations are required to obtain the answer. 1. Let X be the temperature of benzene inside the pipe; given that the insulation material is rock wool with a thickness of 50 mm, calculate the temperature of the outer surface of the insulation layer. 2. Heat loss can be calculated using the formula Q = K * F * (T_benzene – T_air), where F represents the external surface area of the insulation layer, which is 8000 square meters. The value of K ranges from 10 to 20 KCAL/M2·℃·HR. 3. Once the heat loss is determined, the terminal temperature can be calculated; if the value of X meets the specified conditions, then it represents the desired result. It is suggested that the heat dissipation along the benzene transport path should be treated as an integral problem, but accuracy isn’t necessary; it’s also possible to perform calculations in segments, for example every 2000 meters.
Thank you for the reply; knowing this is enough. Could I ask again how the K value is determined, and where can I find this information?
Upon further consideration, it seems that it’s still not possible to determine: namely, how much benzene should be used. If I use 1000 meters as a unit, does that mean the amount of benzene should be calculated based on that 1000 meters of pipeline? Can the resulting value be the outlet temperature of this 1000-meter pipeline?
For information on data and calculation methods, etc., refer to the Chemical Engineering Design Manual, Insulation Design Section.
Calculated in segments, the flow rate of benzene remains at 3 tons per hour. The K value is related to wind speed; I’ve only provided a range so that you can check the wind speed conditions in your area. If calculated using a spreadsheet, the data can be modified flexibly.
This calculation method is fine; by selecting the design wind speed, it is possible to determine the heat dissipation coefficient
Thank you, I’ll look for relevant books to study, and I’ll ask you again if there are any things I don’t understand!