Reactors; Chemical Reactors

There are two main distinctions between reactors, batch and continuous. In a batch reactor a certain amount of the reactants is handled at one time. In continuous reactors, the process continues indefinitely. This is the most common type of reactor in petrochemical and refinery service.

A batch reactor is a closed system. An example is a batch of paper pulp being made for a specific or customized application.

A semibatch reactor is not a closed system. This type is useful in cases such as the manufacture of certain chemicals where a volatile chemical must be added slowly to a nonvolatile chemical (examples include the manufacture of certain glycols).

Tubular reactors (either long bent tube or shell and tube) may be either batch or continuous reactors.

Continuous reactors are "at work" all the time. This means newly introduced reactants mix to some extent with products. This extent is termed backmixing. A tower has many plates or baffles in it and experiences less backmixing as, for instance, a tank with no plates. Continuous reactors can then be found within towers and columns. Towers may be packed or plate (bubble cap or sieve tray) type. Optimum reactor design attempts to curtail the amount of "dead space" or areas where no reaction is taking place. It is also possible to have reactants take a shorter path than is necessary for optimum reaction. This is called shortcircuiting.

Catalytic reactors are continuous reactors more often than...