US 4,397,675 AGranted

Method of producing urea-sulfuric acid reaction products

AssigneeUnion Oil Company of California

InventorDonald C. Young

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Abstract

Stable, urea-sulfuric acid reaction products of predetermined composition containing mono- and/or diurea sulfates and less than 35 weight percent water are produced from concentrated, urea-sulfuric acid reaction product feeds of different compositions by simultaneously and separately adding a selected feed solution and reactant urea and/or sulfuric acid, and optionally water, to a reaction zone in stoichiometric proportions so that the composition of the total feed to the reaction zone corresponds to the predetermined composition. Reaction temperature is maintained at a level below the incipient decomposition temperature of the predetermined composition, and the resulting products are essentially or completely free of sulfamic acid and/or ammonium sulfamate. Depending upon the relative proportions of unreacted sulfuric acid and urea in the total feed, the reaction may be exothermic or endothermic and, when desired, the otherwise endothermic reactions can be made exothermic by the reaction of excess urea and sulfuric acid to autogenously maintain the desired reaction temperature.

Claims18

Dependent claims

A method for producing a concentrated urea-sulfuric acid reaction product of predetermined composition within the range of about 5 to about 75 weight percent urea, about 5 to about 85 weight percent sulfuric acid, and about 0 to about 35 weight percent water, wherein at least a portion of said urea and sulfuric acid are present as a member selected from the group consisting of monourea sulfate, diurea sulfate, and combinations thereof, and the combination of said urea and sulfuric acid correspond to at least about 65 weight percent of said predetermined composition, which method includes the steps of (i) simultaneously and separately feeding to the reaction zone (a) at least about 10 weight percent based on the total feed to said reaction zone of a feed solution of a urea-sulfuric acid reaction product having a composition within said range and a urea/sulfuric acid weight ratio at least about 10 percent different from that of said predetermined composition, and (b) at least about 10 weight percent based on the total feed to said reaction zone of a reactant selected from the group consisting of urea, sulfuric acid, water and combinations thereof, at least one of said reactants being selected from urea, sulfuric acid and combinations thereof, in proportions and at feed rates correlated with the differences in the concentration of said urea, sulfuric acid and water between said feed solution and said predetermined composition sufficient to produce a total feed to said reaction zone having a composition corresponding to that of said predetermined composition, (ii) maintaining in said reaction zone a weight amount of said predetermined composition corresponding to at least about one-tenth of the hourly feed rate of said total feed to said reaction zone, (iii) agitating the reacting liquid phase formed by the addition of said total feed to said reaction zone during the addition of said total feed thereto at a rate sufficient to rapidly disperse said feed in said liquid phase, (iv) maintaining the temperature of said liquid phase within the range of about 120.degree. F. to about 176.degree. F. and below the incipient decomposition temperatures of both said predetermined composition and said feed solution, and (v) withdrawing said reaction product of said predetermined composition from said reaction zone.

A method for producing a concentrated urea-sulfuric acid reaction product of predetermined composition within the range of about 5 to about 75 weight percent urea, about 5 to about 85 weight percent sulfuric acid, and about 0 to about 35 weight percent water, wherein at least a portion of said urea and sulfuric acid are present as a member selected from the group consisting of monourea sulfate, diurea sulfate, and combinations thereof, and said urea and said sulfuric acid, in combination, constitute at least about 65 weight percent of said predetermined composition, which method includes the steps of (i) continuously, simultaneously and separately feeding to a reaction zone (a) at least about 10 weight percent, based on the total feed to said reaction zone, of a feed solution of a urea-sulfuric acid reaction product having a composition within said range and a urea/sulfuric acid ratio of at least 10 percent different from that of said predetermined composition, and (b) at least about 10 weight percent based on the total feed to said reaction zone of a reactant selected from the group consisting of urea, sulfuric acid, water, and combinations thereof, at least one of said reactants being selected from urea, sulfuric acid, and combinations thereof, in proportions and at feed rates correlated with the differences in the concentration of said urea, sulfuric acid and water between said feed solution and said predetermined composition and sufficient to produce a total feed to said reaction zone having a composition corresponding to that of said predetermined composition, (ii) maintaining within said reaction zone a weight amount of a reacting liquid phase formed by the admixture of said feed solution and said reactant corresponding to at least about 0.2 times the hourly feed rate of said total feed to said reaction zone, (iii) agitating the reacting liquid phase formed by the addition of said total feed to said reaction zone during the addition of said total feed to rapidly disperse said feed solution and said reactant within said reaction zone, (iv) maintaining the temperature of said reacting liquid phase within the range of about 120.degree. F. to about 176.degree. F. and below the incipient decomposition temperature of both of said predetermined composition and said feed solution, and (v) continuously withdrawing said reaction product of said predetermined composition from said reaction zone.

Dependencies are inferred from the claim text.