GB1087550A - Improvements in or relating to nitro-cellulose production - Google Patents

Abstract

Continuous nitration of cellulose by a sulphuric acid/nitric acid nitration agent mixture is effected in apparatus comprising a cylindrical drum 1 (see Fig. 1) capable of rotation about its longitudinal axis and adapted to operate with its longitudinal axis in the horizontal plane. The drum terminates in end portions of decreasing cros-section, which end portions 9 and 10 serve for the continuous introduction and for the continuous removal of nitration reactants into and from the drum, respectively. Connected in sealed fashion to the internal wall of the drum is a continuous helical strip 14 (see Figure 2) which is open at its central axial region and which has turns of constant pitch within the cylindrical portion of the drum and a turn or turns 16 and 18 of varying pitch extending into the end portions of the drum; the <PICT:1087550/C3/1> <PICT:1087550/C3/2> helical strip ensures that the reactants undergo translatory movement axially of the drum and that introduction and removal of reactants into and from the drum take place at a constant rate. Associated with the internal wall of the drum and with the helical strip are agitation members (not shown) for establishing a turbulent state within the reactants in the drum in a plane perpendicular to the direction of the translatory movement; as illustrated in Fig. 3 (not shown), the agitation members preferably comprise paddles spaced equidistantly around the turns of the helical strip thus to divide the reactants into a number of portions. Preferably, the drum carries annular track members 2 and 3 supported by bearing wheels 4 and 5 and is rotated by a gear reducer/motor unit 8 arranged to drive a pinion 7 rigidly secured on its output shaft and meshing with the gear ring 6 connected to the drum. The drum may have means 11 for heating or cooling, a de-gassing duct 12 at its discharge end, which discharge may be provided with a funnel 19 of variable diameter, and a pipe 13 for the introduction of the nitration agent at the inlet end 17, which inlet may have a diameter slightly less than that of the central aperture 15 of the helical strip. Suitable dimensions and speed of operation of the apparatus are given in an example together with the operating temperature and proportions of the components of the nitration agent mixture; the cellulose may be bleached cotton linters and/or chemical wood pulp.