Is it harmful to the pipes when the medium temperatures of two pipes differ by 100°C as they meet?
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There are two pipes: one with a DN350 diameter operating at 220°C, and the other with a DN600 diameter operating at 325°C. Both have a working pressure of 1.7–1.9 MPa. Will their convergence cause significant damage to the pipes?
Mix directly in the pipeline? Generally, a mixing container or pipeline mixer is required, such as in a temperature and pressure reduction station @GuanGongYu @ylb913 @E Guan Man Ying @Zhi Zhe Ming @yjqin1
If no phase transition occurs, there should be no problem.
In our original aromatization unit, at the inlet to Reactor 1, there was feed material that had been heated in a heating furnace, as well as feed material that had not been heated by such a furnace; the temperature difference between these two types of material was around 150°C. They would mix together in a mixer before being fed into the pipelines. This is probably the best approach, as it places less strain on the pipelines and no special pipes are required; if it’s a direct connection, then considering the use of pipes made from special materials would be advisable. To ensure safety, it’s better to add it to the mixing equipment.
Given the large temperature differences, it is necessary to take into account the issues related to piping materials and stress.
Choosing the right material isn’t a big problem. Condensation may occur, and the pipes could vibrate; be careful to prevent such vibration, and choose materials that are resistant to erosion. Vaporization can occur, and the pipes may experience shock vibrations; therefore, the pipe layout should minimize sharp turns and elbows.
A large temperature difference places high demands on the piping; it is best to use a mixer
The stress caused by heat must be significant, right?
The phase remains unchanged; it is all gas. The pipe pressure rating is 600, and the material used is 12Cr2Mo.
If no chemical reaction occurs, there’s no major problem
If the flow rates of the two fluids are also relatively stable, then there’s not much of a problem; the concern is when the temperature changes from cold to hot. Frequent thermal cycling of the pipeline requires flexible component compensation.