Process for the preparation of urea
AssigneeDsm N.V.
InventorsJacob F. Scholten, Franciscus A. L. Van Laak
Life of this patent
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Abstract
Process for the preparation of urea from ammonia and carbon dioxide in which the composition of the various process streams is measured via an ultrasonic measuring principle and in which the results of these measurements are used for process control. The process is particularly suitable for continuous measurements in a urea process.
Claims17
Process for the preparation of urea from ammonia and carbon dioxide, characterised in that the composition of the various process streams is measured via an ultrasonic measuring principle, with the results of these measurements being used for process control.
Process for the preparation of urea from ammonia and carbon dioxide in which:
- NH3 and CO2 are supplied to the high-pressure section of a urea plant and are converted in a reactor into a liquid stream (1) consisting essentially of urea, ammonium carbamate, water and ammonia and a gas stream (2) consisting essentially of ammonia, carbon dioxide, water vapour and inert gases;
- this liquid stream (1) is separated into a gas stream (3) consisting essentially of ammonia, carbon dioxide and water vapour and a liquid stream (4) consisting essentially of urea and water;
- this liquid stream (4), following expansion, is passed to a reduced-pressure section where there are obtained one or more gas streams (5) consisting essentially of ammonia, carbon dioxide and water vapour and liquid stream (6) consisting essentially of urea and water;
- this liquid stream (6) is passed to an evaporation section where virtually water-free urea is released;
- the various gas streams (5) are condensed and recirculated as low-pressure carbamate solution (8) to the synthesis section, where it absorbs gas stream (2), and is passed to the high-pressure carbamate condenser as carbamate stream (9);
- the gas stream (3) is condensed with the aid of carbamate stream (9) in the high-pressure carbamate condenser, in which process carbamate stream (10) evolves, which is passed to the synthesis, characterized in that the composition of the various streams is determined via an ultrasonic measuring principle and in which the urea process is controlled with the results of the measurements.
Dependencies are inferred from the claim text.