Why are the tubes in the heating furnace of a hydrocracking reactor arranged with material entering from the top and exiting from the bottom?
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Is there anything special about it? Are all heating furnaces heated in this way?
They all have air flow from top to bottom, right? In typical furnaces, there is a convection zone at the top and a radiation zone at the bottom; the temperature is lower at the top and higher at the bottom. So, it goes in from above and out from below.
Typical furnaces have a convection zone at the top and a radiation zone at the bottom; the temperature is lower at the top and higher at the bottom, which facilitates gradual heating
Ordinary heating furnaces have material entering from the top and exiting from the bottom
The driving force for convective heat transfer is the temperature difference; if the flue gas moves upward, the medium moves downward.
Because the heating furnace has a convection zone at the top and a radiation zone at the bottom, with lower temperatures at the top and higher temperatures at the bottom; to achieve heating, it is necessary to first pass through the area with lower temperatures and then through the area with higher temperatures – this is what makes sense. Furthermore, if one passes through the convection zone below first, the temperature difference is too large. It’s not good for the furnace tubes either, so it’s inlet at the top and outlet at the bottom.
The smoke rises upward, so the heating medium should flow from top to bottom to enhance convection, haha
The temperature is low at the top and high at the bottom; start with the lower temperature area and then move to the higher temperature area. Also, I think it uses less energy for materials to flow from top to bottom rather than from bottom to top.
There are several points regarding the heat flow from top to bottom in the heating furnace: 1. The temperature at the top of the entire furnace is relatively low, and introducing cold oil helps to make full use of this heat. 2. The cold oil flows from top to bottom, and its temperature gradually rises; by the time it reaches the lower radiation section, its temperature is already very high. 3. It facilitates control of the furnace exit temperature. 4. Flow from top to bottom to increase fluid mobility. This is just my humble opinion; I hope experts can offer more guidance.
Beneficial for the medium in the heating furnace tubes! Since the temperature in the upper convection chamber is lower than that in the radiation chamber, an energy-saving design with air intake at the top and exhaust at the bottom is adopted! ~
Counterflow heat transfer. Additionally, coagulation separation is relatively easy.