Methods of producing concentrated urea-sulfuric acid reaction products
First Claim
1. A method for producing concentrated solutions of urea and sulfuric acid of predetermined composition which method comprises the steps of:
- (i) simultaneously adding urea, concentrated sulfuric acid, and optionally water to a reaction zone at relative rates corresponding to the concentration of each respective component in said predetermined composition and within the ranges of about 5 to about 75 weight percent urea, about 5 to 85 weight percent sulfuric acid, and 0 to about 35 weight percent water, in which said urea and sulfuric acid are introduced to said reaction zone separately of each other and, in combination, constitute at least about 65 weight percent of the feed to the reaction zone, (ii) continuously agitating said reacting liquid phase formed by the addition of said urea, sulfuric acid, and water to said reaction zone during the addition of said urea, acid and water to rapidly disperse said urea, acid, and water therein, (iii) cooling said reacting liquid phase during the addition of said urea, acid and water by an amount sufficient to maintain said liquid phase at a temperature of about 176°
F. or less and below the incipient decomposition temperature of said predetermined composition, and (iv) recovering from said reaction zone a product solution having said predetermined composition.
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Abstract
Stable concentrated solutions of urea and sulfuric acid containing mono- and/or diurea sulfates and less than 35 weight percent water, free of sulfamic acid and/or ammonium sulfamate, are produced by a unique process that involves the simultaneous and separate addition of urea, sulfuric acid and optionally water to a reaction zone at controlled rates and in stochiometric proportions equivalent to the composition of the desired product, and maintaining reaction temperatures below the incipient decomposition temperature for the particular composition. The heat generated by the highly exothermic reaction can be removed by cooling the liquid phase during the course of the reaction by direct air heat exchange with only nominal, if any, atmospheric emissions.
71 Citations
52 Claims
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1. A method for producing concentrated solutions of urea and sulfuric acid of predetermined composition which method comprises the steps of:
- (i) simultaneously adding urea, concentrated sulfuric acid, and optionally water to a reaction zone at relative rates corresponding to the concentration of each respective component in said predetermined composition and within the ranges of about 5 to about 75 weight percent urea, about 5 to 85 weight percent sulfuric acid, and 0 to about 35 weight percent water, in which said urea and sulfuric acid are introduced to said reaction zone separately of each other and, in combination, constitute at least about 65 weight percent of the feed to the reaction zone, (ii) continuously agitating said reacting liquid phase formed by the addition of said urea, sulfuric acid, and water to said reaction zone during the addition of said urea, acid and water to rapidly disperse said urea, acid, and water therein, (iii) cooling said reacting liquid phase during the addition of said urea, acid and water by an amount sufficient to maintain said liquid phase at a temperature of about 176°
F. or less and below the incipient decomposition temperature of said predetermined composition, and (iv) recovering from said reaction zone a product solution having said predetermined composition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 33)
- (i) simultaneously adding urea, concentrated sulfuric acid, and optionally water to a reaction zone at relative rates corresponding to the concentration of each respective component in said predetermined composition and within the ranges of about 5 to about 75 weight percent urea, about 5 to 85 weight percent sulfuric acid, and 0 to about 35 weight percent water, in which said urea and sulfuric acid are introduced to said reaction zone separately of each other and, in combination, constitute at least about 65 weight percent of the feed to the reaction zone, (ii) continuously agitating said reacting liquid phase formed by the addition of said urea, sulfuric acid, and water to said reaction zone during the addition of said urea, acid and water to rapidly disperse said urea, acid, and water therein, (iii) cooling said reacting liquid phase during the addition of said urea, acid and water by an amount sufficient to maintain said liquid phase at a temperature of about 176°
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17. A method for continuously producing concentrated, stable solutions of urea and sulfuric acid of predetermined composition which method comprises the steps of (i) continuously and simultaneously adding urea, sulfuric acid and water to a reacting liquid phase, hereinafter defined, in a reaction zone at relative rates corresponding to the concentration of each respective component in said predetermined composition and within the ranges of about 5 to about 75 weight percent urea, about 5 to 85 weight percent sulfuric acid, and 0 to about 35 weight percent water, in which said urea and sulfuric acid constitute at least about 65 weight percent of the feed to said reaction zone and are added separately to said reaction zone, (ii) admixing said urea, sulfuric acid and water in said reaction zone with a reacting liquid phase comprising urea, sulfuric acid, water and said reaction product of said predetermined composition, the quantity of said reacting liquid phase in said reaction zone corresponding to at least about one half the combined hourly addition rates of said urea, acid and water to said reaction zone and being sufficient to prevent the discharge of unreacted urea in the product from said reaction zone, (iii) agitating said reacting liquid phase continuously during the addition of said urea, sulfuric acid and water to rapidly disperse the same therein, (iv) cooling at least a portion of said reacting liquid phase by an amount sufficient to maintain the temperature of said reacting liquid phase at a level of about 120°
- F. to about 176°
F., and below the incipient decomposition temperature of said predetermined composition, and (v) continuously withdrawing product solution of said predetermined composition from said reaction zone. - View Dependent Claims (18)
- F. to about 176°
- 19. A composition of matter comprising about 5 to about 75 weight percent urea, about 5 to about 85 weight percent sulfuric acid, and about 0 to 35 weight percent water based on the combined weight of urea, sulfuric acid and water, and less than about 0.1 weight percent of a member selected from the group consisting of sulfamic acid, ammonium sulfamate, and combinations thereof, in which 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.
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27. A method for producing concentrated solutions of urea and sulfuric acid of predetermined composition, which method comprises the steps of:
- (i) simultaneously adding urea, concentrated sulfuric acid, and optionally water, to a reaction zone at relative rates corresponding to the concentration of each respective component in said predetermined composition, and within the ranges of about 10 to about 70 weight percent urea, about 10 to about 80 weight percent sulfuric acid, and 0 to about 35 weight percent water, in which said urea and said sulfuric acid, in combination, constitute at least about 65 weight percent of the feed to said reaction zone and are introduced into said reaction zone separately of each other, and in which the weight ratio of said sulfuric acid to said urea is at least about 1, (ii) continuously agitating the resulting liquid phase in said reaction zone during the addition of said urea, acid, and optionally water, to rapidly disperse said urea, acid, and water therein, (iii) cooling said liquid phase during said addition of said urea, acid, and water, by an amount sufficient to maintain said liquid phase at a temperature of about 176°
F. or less, and below the incipient decomposition temperature of said predetermined composition, and (iv) recovering from said reaction zone a product solution having said predetermined composition free of reaction byproducts resulting from the decomposition of a member selected from the group consisting of urea, sulfuric acid, and combinations thereof. - View Dependent Claims (28)
- (i) simultaneously adding urea, concentrated sulfuric acid, and optionally water, to a reaction zone at relative rates corresponding to the concentration of each respective component in said predetermined composition, and within the ranges of about 10 to about 70 weight percent urea, about 10 to about 80 weight percent sulfuric acid, and 0 to about 35 weight percent water, in which said urea and said sulfuric acid, in combination, constitute at least about 65 weight percent of the feed to said reaction zone and are introduced into said reaction zone separately of each other, and in which the weight ratio of said sulfuric acid to said urea is at least about 1, (ii) continuously agitating the resulting liquid phase in said reaction zone during the addition of said urea, acid, and optionally water, to rapidly disperse said urea, acid, and water therein, (iii) cooling said liquid phase during said addition of said urea, acid, and water, by an amount sufficient to maintain said liquid phase at a temperature of about 176°
- 29. A composition of matter comprising the reaction product of urea and sulfuric acid, which composition contains 0 to about 35 weight percent water, about 10 to about 80 weight percent sulfuric acid, and about 10 to about 70 weight percent urea, wherein said urea and said sulfuric acid, in combination, constitute at least about 65 weight percent of said composition, the weight ratio of said sulfuric acid to said urea is at least about one, and wherein said composition is free of urea-sulfuric acid reaction by-products resulting from the decomposition of a member selected from the group consisting of urea, sulfuric acid, and combinations thereof.
- 31. A composition of matter comprising the reaction product of urea and sulfuric acid, about 10 to about 80 weight percent sulfuric acid, and which composition contains 0 to about 35 weight percent water, about 10 to about 70 weight percent urea, wherein said urea and said sulfuric acid, in combination, constitute at least about 65 weight percent of said composition, and wherein said composition is free of urea-sulfuric acid reaction by-products resulting from the decomposition of a member selected from the group consisting of urea, sulfuric acid and combinations thereof.
- 34. A composition of matter formed by the reaction of urea and sulfuric acid to convert at least a portion of said urea and sulfuric acid to a member selected from the group consisting of the monourea adduct of sulfuric acid, the diurea adduct of sulfuric acid, and combinations thereof, which composition comprises 0 to about 35 weight percent water, about 10 to about 80 weight percent sulfuric acid, and about 10 to about 70 weight percent urea, wherein said urea and sulfuric acid, in combination, constitute at least about 65 weight percent of said composition, and wherein said composition is free of decomposition products of urea, sulfuric acid, and combinations thereof, formed by said reaction of said urea and sulfuric acid.
- 35. The composition of matter produced by the method which comprises the steps of reacting urea, sulfuric acid, and optionally water, in proportions within the ranges of about 10 to about 70 weight percent urea, about 10 to about 80 weight percent sulfuric acid, and 0 to about 35 weight percent water, in which said urea and said sulfuric acid, in combination, constitute at least about 65 weight percent of the combination of said urea, sulfuric acid, and water, and maintaining the temperature of said combination of said urea, sulfuric acid and water below its incipient decomposition temperature.
- 39. A method for producing reaction products of urea and sulfuric acid, which method comprises the steps of combining urea, sulfuric acid, and optionally water, in proportions corresponding to about 10 to about 70 weight percent urea, about 10 to about 80 weight percent sulfuric acid, and 0 to about 35 weight percent water, wherein said urea and said sulfuric acid, in combination, constitute at least about 65 weight percent of said reaction product, reacting said urea with said sulfuric acid in said combination to produce said reaction products, and, at all times during said reaction, maintaining the temperature of said combination at a level below the incipient decomposition temperature of said combination.
Specification