Concentrating evaporators – Processes – Spraying
Patent
1993-07-16
1995-07-11
Bascomb, Jr., Wilbur
Concentrating evaporators
Processes
Spraying
159 401, 159 409, 159 163, 159DIG3, 159DIG34, 252 891, B01D 118
Patent
active
054317800
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for the production of fine-particle, solid, pourable or free-flowing useful materials or mixtures of such useful materials, which are suitable as and/or for use in wetting agents, detergents and/or cleaning preparations, from aqueous preparations thereof. The process according to the invention uses the known principles of spray-drying, except that superheated steam is now used as the hot gas stream.
The spray-drying of aqueous preparations of useful materials of the type mentioned has been carried out worldwide on an industrial scale for decades. Hot air or mixtures of air and hot waste combustion gases are used as the drying gas stream. Washing powders or useful materials and/or mixtures thereof for the production of laundry detergents in pourable and free-flowing powder form are industrially obtained in corresponding spray-drying towers, generally at ambient pressure, either in co-current or more frequently in countercurrent. From the extensive specialist literature available, reference is made purely by way of example to Masters, K. "Spray Drying--An Introduction to Principles of Operational Practice and Applications", Leonard Hill Books, London, An Intertext Publisher, 1972.
The advantages and disadvantages of this drying process using hot air as the drying gas are well known and are discussed in detail in the specialist literature. In addition to the wide availability of the gas phase, the advantages include inter alia the possibility of operating in open systems (normally corresponding spray-drying towers) which provide for easy disposal of the hot gas phase by discharge into the atmosphere. In addition, detailed physico-chemical studies of the drying process itself have shown that drying with hot air takes place effectively and quickly, even where comparatively mild hot gas temperatures are used. The drying process on the water-containing droplet of material begins at comparatively low temperatures, for example of the order of 40.degree. C., irrespective to a large extent of the temperature of the hot gas used, and continues effectively with a comparatively slow increase in the temperature of the droplet to the boiling range of water under normal pressure, so that the material to be dried is only subjected to a moderate heat effect. In overall terms, the drying process in hot air takes place quickly and effectively, even in its final phases, so that drying of the useful materials to the freeflowing product can be accompanied by a comparatively mild heat effect on the useful materials in the drying process.
However, the disadvantages and limitations of spray drying are also generally known, particularly in the field with which the present invention is concerned, namely the drying of useful materials or mixtures thereof, for example for laundry detergents and/or cleaning preparations. Reference is made purely by way of example to the following points: numerous useful materials in this field are sensitive to oxidation, particularly as organic components. The treatment with hot air can lead to substantial losses of value, particularly at relatively high temperatures. The drying of organic or substantially organic useful materials, for example corresponding surfactants based on natural materials, creates considerable problems arising out of the danger of fire or even explosion of the material being dried. Important components of the useful material, more particularly detergent-range nonionic surfactants, show a more or less pronounced tendency towards pluming and are discharged from the tower together with the steam-laden waste air. In overall terms, there is an increased danger of environmental pollution from the large throughput of water-containing, solid and gaseous materials or auxiliaries through the spray-drying tower. Attempts at recycling the drying gas stream have been largely unsuccessful in the industrial application of this process.
2. Discussion of Related Art
It has been known from the beginning of th
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Bauer Volker
Raehse Wilfried
Bascomb, Jr. Wilbur
Grandmaison Real J.
Henkel Kommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Szoke Ernest G.
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