Questions regarding the shell side of the heat exchanger for hydrogenation feedstock/post-refining reaction products

The logic is very simple! Due to the mixing of hydrogen, the feedstock flows through the tube side; otherwise, it will **reduce the effectiveness of the circulating hydrogen and cause coking of the catalyst.

As mentioned on the second floor, hydrogen needs to be mixed; using the shell side can enhance the mixing of the feed oil and recycled hydrogen, and there are many baffles on the shell side. Another point is the issue of uniform heating of the heat exchanger, which can help reduce leaks caused by uneven heating of the heat exchanger.

3# 2001061713 As you put it, relatively speaking, the space in the shell side should be larger than that in the tube side; if the flow is through the shell side, wouldn’t the feed oil and recycled hydrogen mix better? My question is why the raw materials go through the tube side. Did you misread the question?

2# Troubles in life: Why does using mixed hydrogen oil in the shell side **reduce the effectiveness of the circulating hydrogen and lead to catalyst coking? Could you please explain further? Thank you.

Personally, I think it’s based on the principle of rational use of heat sources? The feed flows through the tube side to increase the temperature, while the reaction effluent flows through the shell side, allowing for better heat exchange with the feed due to its larger contact area. I’m not sure if this explanation is correct

6# cool99 According to your way of explaining it, anything that needs to be heated moves through the tube side, while the heat medium moves through the shell side. Then most of the other heat exchangers would also be unexplainable.

When selecting the shell-side medium, the main contradictions should be identified to determine which mediums are best suited for the tube side or the shell side. It should be considered comprehensively based on factors such as medium properties, temperature or pressure, allowable pressure drop, scaling, and the improvement of heat transfer coefficients. ①Media that are corrosive, toxic, subject to high temperatures or pressures, as well as those prone to scaling, should all be used in the tube side. This is mainly because if corrosive media are used in the shell side, the materials of both the tube side and the shell side will suffer from corrosion; therefore, corrosive media are generally used in the tube side, which helps to reduce the requirements for the materials used in the shell side ； Leakage of toxic media through the tube side is less likely ； Higher temperatures and pressures allow using the tube side, which reduces the requirements for the shell side material, and fouling on the tube side is easier to clean. ②It helps to increase the overall heat transfer coefficient and make the most of the pressure drop. In the shell side, the flow pattern and cross-sectional area of the fluid change continuously, and baffles can be used to promote turbulence; turbulence is achieved when Re > 100, whereas in the tube side turbulence occurs only when Re > 1000. Therefore, fluids with higher viscosity or lower flow rates, resulting in a lower Re value, are suitable for the shell side. Conversely, if turbulence can be achieved in the tube side, it is more appropriate to use that side for such fluids. From the perspective of pressure drop, it is also advantageous to have fluids with a lower Re value in the shell side. ③It is determined based on the values of the heat transfer coefficients of the two sides of the membrane; if there is a large difference, the side with the lower membrane heat transfer coefficient can be placed in the shell side, allowing for the use of external heat transfer enhancement devices such as twisted tubes or finned tubes.

Longlong explained it very well; I’ve learned it.

For issues like LZ, I have seen them before; there are actually 3 such scenarios: heat exchange between crude oil and reaction effluents, where crude oil flows through the tube side; heat exchange between mixed hydrogen and hot high-pressure gas, where mixed hydrogen flows through the tube side. In comparison to the shell-and-tube stage, the feed oil is at low temperature and high pressure, while the reaction effluent is at high temperature and low pressure. Hydrogen mixing occurs at low temperature and high pressure, while thermal separation takes place at high temperature and low pressure. Here, the layer with high pressure was chosen for the pipes, rather than the layer with high temperature. Later, I went to another location for testing, and found that for the heat exchange between the crude oil/reactor effluent, the reactor effluent flowed through the tube side, while for the heat exchange between the mixed hydrogen/heat-treated high-pressure gas, the heat-treated high-pressure gas flowed through the tube side – it was exactly the opposite. Here, the layer with higher temperature was chosen for the pipes, rather than the layer with higher pressure. The front is the post-furnace hydrogen mixing process, and the back is the pre-furnace hydrogen mixing process. So I think it should be considered comprehensively, as mentioned on the 8th floor. It’s related to design.

Is the poster from Huizhou Refinery? Thus, it can be briefly described. . .