THE MULTITUBULAR PHOTOREACTOR .1. RADIATION-FIELD FOR CONSTANT ABSORPTION REACTORS

The existing radiation field in a single-lamp, multitubular photoreact or has been modeled from first principles. The device consists of a tu bular lamp surrounded by cylindrical tubes of circular cross section, enclosed in a cylindrical reflector. The results show the existence of severe azimuthal asymmetries that cannot be avoided with the inclusio n of the reflector. Consideration of the reflected contributions led t o a rather complex radiation model. However, using the concept of inci dent radiation efficiency, the complete model was used to show that, i n a multitubular photoreactor designed properly, the reflected contrib utions should never represent more than 25 % of the total; consequentl y a slightly overdesigned result can be obtained using a much simpler design procedure. It is finally concluded that most probably the use o f three-dimensional equations for the thermal energy and mass balances will be unavoidable.