Tubular reactor is a kind of continuous operating of the reactor which is tubular and has a large aspect ratio. Structure of the reactor may be a single tube or the parallel connection of severl tubes; it can be empty tube such as tubular cracking furnace, or packed tube filled with granular catalyst for heterogeneous catalysis reaction, such as parallel multitubular fixed bed reactor. Generally, when the reactant is in turbulent state, the aspect ratio of empty pipe is greater than 50; when the ration between length of the fillingzone and particle diameter is greater than 100 (gas) or 200 (liquid), the flow of material can be approximately regarded as plug flow.
Tubular reactor has the following characteristics.
(1)As the the residence time of reactant moleculars in the reactor is equal, the concentration of reactants and the chemical reaction rate at any point of the reactor will not change over time, only change with tube length.
(2)With the characteristics of small volume, large surface area, large heat transfer area per unit volume, tubular reactor is especially suitable for reactions with larger thermal effects.
(3)As the reaction speed and flow speed of the reactants in tubular reactor is high, so it has high production capacity.
(4)Tubular reactor suitable for large-scale and continuous chemical production.
(5)Compared to tank reactors, its backmixing is relatively small, and at low flow rates, the fluid flow type inside the tube is close to the ideal type of fluid.
(6)Tubular reactors is not only suitable for the liquid phase reaction but also gas phase reactions.
In addition, the tubular reactor can achieve temperature-segmentation control. Its main disadvantage is that the required pipe is too long when the reaction rate is very low, which is not easy to implement in industry.
