STARCHES & CELLULOSE
cationic starch production
The AVA HRM ring layer mixer and the continuous AVA HTK-T reactors are used in series production of cationized starches. In the first stage, the starch powder (native starch) is intensively and homogeneously mixed with the etherifying agent and sodium hydroxide (catalyst) in the ring layer mixer at circumferential agitator speeds of up to 40 m/s. Following this, etherification is carried out in an AVA HTK-T heated reactor. The reaction process is maintained continuously at processing times of between 1 h to 4 h. Finally the starch enhanced with sodium hydroxide solution is neutralized by adding acid. In this final process step a highly uniform mixing of the element is ensured by a further AVA HRM ring layer mixer.
production of alkali cellulose
The first step in producing cellulose ethers is the preparation of the alkali cellulose. Depending on the task, the milled pulp is mixed homogeneously with water, ethanol, and sodium hydroxide. At this stage, optimal homogeneity of the mixture is of particular importance in order to achieve a high degree of alkalization. AVA agitators are designed to achieve best possible mixture homogeneity with uniform, controlled cooling. The AVA HTC-T horizontal mixers and AVA HVW-T vertical mixers are particularly well suited to this process step.
production of cellulose ether
The first step in cellulose ether production, as described above, need not necessarily take place in a separate machine. The subsequent etherification through the addition of monochloroacetic acid (MCA), dimethyl ether (DME), and other additives can be performed using the same machine. Exothermic reactions cause process pressures of up to 40 bar. The recovery of solvents is carried out in the same reactor in a vacuum. The heatable and coolable AVA HTC-R-series horizontal reactors are well suited to this application.
homogenizing of cellulose ether
Several batches of cellulose ether are collected in a vertical AVA HVM mixer and homogenized together with further additives (small components) in a short mixing time. The result is a consistently high-quality final product with no batch variations.
granulation/cooling of modified celluloses
Horizontal mixers of type AVA HTK-T and ring layer mixers of type AVA HRM are ideally suited to granulating and cooling cellulose ether. The high peripheral velocities of the HRM-series agitators allow for increasing the particle size over a retention time of a few seconds to configure the system for subsequent process stages. Compact machines achieve high throughputs during this manufacturing stage.