Metallgesellschaft Aktiengesellschaft

Lurgi Gmbh

Klaus Hohmann

Herbert Bierbach

Helmut Saft

Rudolf Boensch

Jiri Pendl

Vaclav Cerny

Heinz Dittmar

Frantisek Hotek

Manfred Mai

Ernst Heinz

Rudolph Bönsch

Juergen Kuhn

Rolf Rennhack

In a process for producing fatty acid methyl ester (FAME) from fats or oils by transesterification with methanol in the presence of an alkaline catalyst in at least two reaction stages traversed in succession, each consisting of a stirred-tank reactor and a downstream separator, a phase containing FAME and a phase containing glycerol are generated, which are separated in the separator, wherein the phase containing FAME is recirculated into the stirred-tank reactor of the next succeeding reaction stage and the phase containing glycerol is recirculated into the stirred-tank reactor of the first reaction stage, and the crude FAME withdrawn from the separator of the last reaction stage is transferred into a separator and the FAME withdrawn is dried. To increase the yield of FAME, the aqueous phase containing glycerol, methanol, undissociated soaps and FAME, which is obtained upon withdrawal of the FAME, is thoroughly mixed with the phases withdrawn from the separators of the first to penultimate reaction stages, which contain glycerol and FAME, and the mixture is separated in a separator into a phase containing FAME and a phase containing glycerol.

Process for continuously preparing fatty acid methyl esters or fatty esters

Citric acid and/or the salts thereof are produced from a raw material containing carbohydrates. An aqueous solution of the raw material is converted into a first solution containing citric acid by means of fermentation, and from the first solution a second solution containing citric acid is obtained by means of a cell separation. The second solution is subjected to a protein precipitation at temperatures of 2 to 70.degree. C., and protein is separated by filtration. From the filtration, a third solution containing citric acid is obtained, and the same is passed through a first anion exchanger. The solution containing citric acid, which is discharged from the first anion exchanger, is passed through a second anion exchanger, which is selectively charged with citric acid. The second anion exchanger charged with citric acid is eluted with hydroxide solution or water, and there is thus obtained a fourth solution, in which citrate or citric acid is dissolved. Water is at least partly removed from the fourth solution.

Process for producing citric acid and/or citrates

The solutions are concentrated by multiple-effect evaporation in indirectly heated evaporators. The highest concentration of the solution is reached in a final evaporator stage, which is heated with live steam. The final evaporators stage includes two to four falling-film evaporators, all of which are heated with live steam. The falling-film evaporators are consecutively flown through by the solution. Vapor is withdrawn from that falling-film evaporator which is the first to be supplied with the solution and at least part of said vapor is directly contacted with the solution as it flows down through the heating zone of at least one other evaporator of the final stage. From that falling-film evaporator of the final stage which is the first to be supplied with the solution the vapor may be fed to all other evaporators of the final stage.

Process and apparatus for concentrating a solution

Bivalent or multivalent metal chloride in aqueous solution is decomposed in the presence of oxygen to produce HCl and the corresponding metal oxide. Hydrochloric acid recovered by adiabatic absorption from the decomoposition gas is concentrated by extractive distillation in contact with concentrated metal chloride solution. The resulting solution is concentrated by heat exchange with the hot decomposition gas. At least part of the solution of high concentration is supplied to the thermal decomposition stage at a metal chloride rate corresponding to the metal chloride content of the incoming aqueous liquor.

Process for thermally decomposing chlorides of bivalent or multivalent

A process for the thermal decomposition and conversion of metal chlorides to metal oxides in a fluidized bed wherein the fluidizing gas contains oxygen and the reaction temperature is maintained above the thermal decomposition temperature of the metal chloride but below the sintering temperature of the metal oxide thus produced. The gas velocity is determined by the critical relationship 0.34.rho..sup.0.9 .ltoreq. W.sub.G .ltoreq. 0.56.rho..sup.0.9 where W.sub.G is the approximate gas velocity through the fluidized bed chamber in the absence of the bed and .rho. is the density of the pure fluidized-bedmaterial (metal oxide). The height of the bed is also critical and should be that at which a critical pressure drop of 1200 to 2400 mm (water column) is obtained but at least 350 mm, measuring with the static or settled bed (nonfluidized).

Thermal transformation of metal chlorides to oxides in a fluidized bed

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Hofheim, Germany

Klaus Hohmann