Detergents, production spray drying

Such solid enzyme preparations are conventionally produced by means of freeze drying or spray drying. As freezedrying process is unsuitable for large-scale productions, spray drying is used as the most fitted process for the industrial mass production of solid enzyme preparations. Especially in the case of solid enzyme preparations to be used in detergents, spray-drying process is most frequently used. 

The introduction of concentrated laundry detergent powders in Japan during 1986-1987 produced a substantial increase in the consumption of LAB in the subsequent 3-4 years as the market changed from low-density, spray-dried powders to the concentrated (compact) products. In these products, which may contain up to 40% surfactant, the cost/performance advantages of LAS are of significance. In addition, LAB sulfonic acid is well suited for the production of high-active, high-density (about 1.0 g/cm3) laundry powders by routes other... 

Figure 15 Spray-dried detergent production (O) (from Ref. 13).

Sodium Sulfate. Although considered a weak builder by some manufacturers, sodium sulfate (Na2S04) contributes little to detergent performance. It is commercially available from natural sources and as a byproduct from rayon processing. In dry mix and agglomerated type products, sodium sulfate is used to improve finished product flow characteristics. In spray-dried products, sodium sulfate acts as an inert filler and aids in density control. 

Sodium Chloride. Sodium chloride (NaCl) is used by some detergent manufacturers, its main function being as an inert filler or diluent. In spray-drying operations, NaCl is used to control Crutcher slurry viscosity and the density of the spray-dried bead or granules. In liquid formulations, NaCl is used to control product viscosity through the salt effect. Although salt is used to some extent in autodish formulations, it is not recommended because of potential machine and dishware corrosion. 

Spray-dried powders are formulated to give the best overall cleaning performance and flow characteristics at the lowest possible formulation costs. Typical spray-dried detergent formulations are shown in Table 36.6. Slurry preparation is considered to be the single most important factor in spray drying. Control of the raw material order of addition, slurry solids level, slurry temperature, viscosity, and aeration enable manufacturers to deliver the desired final product characteristics. The spray tower itself is simply a contained heat source that removes moisture at a uniform rate dependent upon the quality and the quantity of feed to the dryer. If feed variables are not controlled, variability in the... 

Dry cyclones are the primary collection equipment used to capture the detergent dust in the spray dryer exhaust and recycle it back to the crutcher. The dry cyclones can remove up to 90 percent by weight of the detergent product fines from the exhaust air. Fabric filters have been used after cyclones but have limited applicability, especially on efficient spray dryers, because of condensing water and organic aerosols binding the fabric filters [4, 21]. 

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