| 摘要 |
<p>A method for the modernisation of a plant for urea production of the type comprising a reactor (2) for urea synthesis, a stripping unit (3) with carbon dioxide and at least one vertical condensation unit (4) of the film type type, includes the step of providing in said at least one condensation unit (4) means for subjecting to substantially total condensation at least a portion of a flow comprising ammonia and carbon dioxide in vapour phase leaving said stripping unit (3), and is characterized in that it further comprises the steps of providing a second stripping unit (47), means (9) for feeding a first portion of the flow of reaction mixture comprising urea, carbamate and free ammonia in aqueous solution leaving the reactor (2) to said stripping unit (3), means (48) for feeding a second portion of the flow of reaction mixture comprising urea, carbamate and free ammonia in aqueous solution leaving the reactor (2) to said second stripping unit (47)and means (49) for feeding at least a portion of a flow comprising ammonia and carbon dioxide in vapour phase leaving said second stripping unit (47) directly to the reactor synthesis (2). Thanks to the present method of modernisation, a substantial de-bottlenecking of the equipment of the high-pressure section downstream the synthesis reactor (2) may be achieved, especially for large installation, to the full advantage of the overall production capacity, which may be therefore increased in a optimal way.</p> |
