Is the steam tracing pipe for the storage tank properly installed?
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This post was last edited by Hoshino Tou Tou on 2023-12-27 at 14:44. Please help to take a look: there is a storage tank that is 16.5 meters high, without including the dome. The accessories attached to the tank keep freezing (the medium is acetic acid, which crystallizes below 17°C). Now, it is planned to install a DN25 steam pipe (with a steam pressure of 0.5 MPa and a temperature of over 170 degrees). The main steam enters the tank through vertical pipes from the ground level; from there, it splits into 5 branches leading to the magnetic flap level gauge, while 4 branches go to the vent valve, the drain manhole, the pressure tap for the nitrogen control valve, and the flange of the pressure sensor. The return air from the 9 branches starts from the top of the tank (yellow) and connects to each branch pipe (from horizontal pipes to vertical pipes; a DN25 drain valve is installed at the ground level); a drain valve is also added to the main pipe. Both the steam main pipe and the return air main pipe are DN25. I’m not sure whether the piping layout is appropriate. The image is not clear; see the attachment. The yellow tube is used for condensate flow.
Only the attachment is included; what about the main body? The temperature of the heat tracing medium is too high
It may be reasonable to use a DN25 steam pipe to provide heating for the pipes surrounding the storage tank, as your medium, acetic acid, crystallizes below 17°C, and steam heating can effectively raise the temperature to prevent crystallization. The steam pressure and temperature are also appropriate. However, specific considerations are also required for factors such as the layout and distance of the heat tracing pipes, as well as the insulation performance of the storage tank. It is recommended to have a professional engineer conduct an on-site assessment. .
Yes, just half an attachment. The body has a separate steam pipe, which was designed at the initial stage of the project. Yes, the steam temperature is a bit high; that’s all there is for now, as electric heating cannot provide sufficient heat.
Jacket heating or tube wrapping heating?
There are no issues with the process design for tube wrapping for heat preservation; for details, refer to the \"SHT 3126-2013 Standards for Design of Heating and Insulation Systems for Instruments and Pipelines in the Petrochemical Industry\". The key factor is the quality of construction (tube wrapping and insulation). In the case of jacket heating, it is not recommended that the steam temperature exceed the atmospheric boiling point of acetic acid.
Construct a heat tracing station, from which lines are drawn off to provide heat tracing.
The steam temperature is too high; it would be better to use hot water for heating. I suggest installing a pipe in series from top to bottom, avoiding too many branches. It’s sufficient to control the amount of steam by adjusting the opening degree of the inlet valve, while the condensate at the outlet can be discharged directly at atmospheric pressure (no drain valve is needed). Normally, just ensure that a slight amount of hot water flows out of the outlet pipe. Additionally, the magnetic flap level gauge should be equipped with a stainless steel tube for heating – do not use carbon steel, as this will prevent the float from functioning properly. Also, remember to insulate all accessories! We are in the south, and acidic magnetic flap level gauges can also freeze occasionally. For some glacial acetic acid storage tanks, we use pressure-type level gauges, with diaphragm boxes that extend into the tank, and no heating is required.
Reasonableness is key; taking into account the boiling point of the medium, hot water is recommended.